JP5152080B2 - Optical film, method for manufacturing optical film, polarizing plate using the same, and liquid crystal display device - Google Patents

Description

  The present invention relates to an optical film, and more specifically, a resin obtained by blending a cellulose ester and an acrylic resin with a cellulose ester having a specific repeating unit (hereinafter also referred to as having a graft chain) as an additive. The present invention relates to an optical film which is good and does not cause breakage failure even when productivity is increased, and a method for manufacturing the same.

  The demand for liquid crystal display devices is expanding in applications such as liquid crystal televisions and personal computer liquid crystal displays. In general, a liquid crystal display device is composed of a liquid crystal cell in which a transparent electrode, a liquid crystal layer, a color filter, etc. are sandwiched between glass plates, and two polarizing plates provided on both sides thereof. The optical element (polarizing plate protective film) is sandwiched between a child (also referred to as a polarizing film or a polarizing film). As this polarizing plate protective film, a cellulose triacetate film is usually used.

  Recent technological advances have accelerated the increase in size of liquid crystal display devices and diversified uses of liquid crystal display devices. For example, it can be used as a large display installed on a street or in a store, or used as an advertising display in a public place using a display device called digital signage.

  In such an application, since it is assumed to be used outdoors, degradation due to moisture absorption of the polarizing film becomes a problem, and higher moisture resistance is required for the polarizing plate protective film. However, it has been difficult to obtain sufficient moisture resistance with cellulose ester films such as cellulose triacetate films that have been used in the past, and there has been a problem that the optical effect increases when the film thickness is increased to obtain moisture resistance. . Furthermore, in recent years, there has been a demand for thinning of the apparatus, so that the polarizing plate itself becomes a problem.

  On the other hand, as a low hygroscopic optical film material, polymethyl methacrylate, which is a representative of acrylic resin, is excellently used for optical films because it exhibits excellent transparency and dimensional stability in addition to low hygroscopicity. .

  However, as described above, the liquid crystal display device is increased in size, the width of the film original is wide, and the winding length is required to be long. Therefore, although the film original is wide, workability is poor due to insufficient improvement in brittleness, and handling properties are not sufficient for producing an optical film used for a large liquid crystal display device.

  As a technique for improving moisture resistance and workability, a technique in which an acrylic resin is combined with an impact-resistant acrylic rubber-methyl methacrylate copolymer or butyl-modified acetyl cellulose has been proposed (for example, see Patent Document 1).

  However, this method can improve moisture resistance, but the improvement in haze (film transparency) and brittleness is insufficient, so that the optical film used for large liquid crystal display devices does not have sufficient performance and handleability. Not found out.

  On the other hand, a resin composition in which a cellulose ester having a graft chain is combined with a thermoplastic resin (olefin resin, styrene resin, aromatic polycarbonate resin, aromatic polyester resin, aliphatic polyester resin, etc.) has been proposed. (For example, refer to Patent Document 2). However, even with this method, improvement in hygroscopicity is seen, but it has been found that improvement in haze and brittleness is still insufficient.

  The resin composition proposed above does not have sufficient compatibility of the mixed resin components, has a high haze and insufficient transparency, and when used as an optical film, the contrast of the image is lowered. It turns out that a problem occurs. Furthermore, when melt film formation was attempted, there was a frequent problem that the film was broken by the conveyance stress.

  Melt film formation is a method of extruding molten resin from a die and then winding it around a cooling roll to form a film, but at the mass production stage, to increase film productivity and to adjust the film thickness The cooling roll is formed by increasing the roll rotation speed with respect to the die extrusion speed. At this time, it is considered that stretching of the film occurs between the die and the cooling roll. The resin component melted in the extruder is weakly entangled, and when it is stretched while cooling between the dice and the cooling roll, the mixed resin is entangled and weakly entangled, and there is a conveyance stress on it. It is assumed that the film is likely to break. Furthermore, by increasing the production rate, the cooling with the cooling roll becomes insufficient, and the cooling rate of the resin becomes slow. As a result, the mixed resin components each form a stable state, so that different resin components are easily phase separated. Thereby, it can be estimated that a fracture occurs when tension is applied to the phase-separated portion.

  Melting and mixing two or more kinds of polymers is widely known as a polymer blend or a polymer alloy, and is widely used as a method for modifying defects of individual polymers. However, in many cases where two or more kinds of polymers are melt-mixed, they are often separated into individual phases due to differences in viscosity, molecular weight, molecular structure, etc., and have a coarse dispersion structure. As a method for improving such phase separation, means for incorporating a compatibilizer has been tried, but it is very difficult to select an optimal compatibilizer for the resin to be mixed without adversely affecting the performance of the film. It has become difficult.

  Under the above circumstances, with the recent expansion of applications of liquid crystal display devices, it is strongly demanded that the optical film used be improved in productivity while maintaining high performance.

Japanese Patent Laid-Open No. 5-119217 JP 2007-231050 A

  Therefore, the present invention has been made in view of the above-mentioned problems, and the object thereof is an optical film having a low haze and causing no breakage failure during production, a method for producing an optical film, a polarizing plate using the same, and the subject matter It is to provide a liquid crystal display device using a polarizing plate. In particular, an object of the present invention is to provide an optical film suitably used as a polarizing plate protective film in a large-sized liquid crystal display device or a liquid crystal display device for outdoor use.

  The above object of the present invention can be achieved by the following configuration.

  1. Cellulose ester (CE) having a substitution degree of 2.0 to 3.0 and cellulose having a repeating unit represented by the following general formula (G-1) or (G-2), which is different from the cellulose ester (CE) An optical film comprising an ester (GCE) and an acrylic resin.

(In the formula, A and B each represent a divalent hydrocarbon group having 1 to 12 carbon atoms or a divalent hydrocarbon group having 1 to 12 carbon atoms substituted with a hydroxyl group. (Cel represents a cellulose ester residue, and n is 1 to 70.)
2. The acrylic resin is a polymer obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the following general formula (AM) and at least one acrylic ester monomer or methacrylic ester monomer. 2. The optical film as described in 1 above.

(Wherein R ¹ , R ² , and R ³ are each independently an alkyl group, a cycloalkyl group, an aryl group, an acylamino group, an alkylthio group, an arylthio group, an alkenyl group, a halogen atom, an alkynyl group, or a heterocyclic ring. Group, alkylsulfonyl group, arylsulfonyl group, alkylsulfinyl group, arylsulfinyl group, phosphono group, acyl group, carbamoyl group, sulfamoyl group, sulfonamido group, cyano group, alkoxy group, aryloxy group, heterocyclic oxy group, siloxy Group, acyloxy group, sulfonic acid group, sulfonic acid salt, aminocarbonyloxy group, amino group, anilino group, imide group, ureido group, alkoxycarbonylamino group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic thio group, Thioureido group, carbo Sill group, salts of carboxylic acids, hydroxyl group, mercapto group, a nitro group or a substituent having an ethylenically unsaturated bond. The bonded R ^1, R ^2, and any two of R ³ to each other, An annular structure may be formed.)
3. 1 or above characterized in that it contains at least one selected from a carbon radical scavenger, a primary antioxidant having hydrogen radical donating ability for peroxy radicals, and a secondary antioxidant having a reducing action on peroxide. 2. The optical film according to 2.

  4). The optical film according to any one of 1 to 3, wherein the optical film contains acrylic particles.

  5). 5. The method for producing an optical film, wherein the optical film according to any one of 1 to 4 is produced by a melt casting film forming method using a touch roll.

  6). 5. A polarizing plate using the optical film according to any one of 1 to 4 above.

  7). 7. A liquid crystal display device using the polarizing plate described in 6 above.

  By the above-mentioned means of the present invention, there are provided an optical film having good haze and no breakage failure during production, a method for producing the optical film, a polarizing plate using the optical film, and a liquid crystal display device using the polarizing plate. Can do.

  In particular, it is possible to provide an optical film that is suitably used as a polarizing plate protective film used in a large-sized liquid crystal display device or a digital signage liquid crystal display device.

It is a general | schematic flow sheet which shows one embodiment of the apparatus which enforces the manufacturing method of the optical film which concerns on this invention. It is a principal part expansion flow sheet of the manufacturing apparatus of FIG. (A) is an external view of the principal part of a casting die, (b) is sectional drawing of the principal part of a casting die. It is sectional drawing of 1st Embodiment of a pinching rotary body. It is sectional drawing in the plane perpendicular | vertical to the rotating shaft of 2nd Embodiment of a pinching rotary body. It is sectional drawing in the plane containing the rotating shaft of 2nd Embodiment of a pinching rotary body. It is a disassembled perspective view which shows the outline of the block diagram of a liquid crystal display device.

  Conventionally, as a polarizing plate protective film, a cellulose ester film is generally used. However, the cellulose ester film has a drawback of higher hygroscopicity than an acrylic film. However, when an acrylic resin is mixed with cellulose ester to improve the hygroscopicity, the haze increases without being compatible with each other, making it difficult to use as an optical film. Furthermore, when the two resins were mixed by extrusion molding to form a melt film, there was a frequent problem that the film was broken by a conveying stress during the melt film formation.

  However, as a result of the study by the present inventors, a cellulose ester having a specific substitution degree, a cellulose ester having a specific graft chain, and an acrylic resin were mixed to form a melt film. As a result, it has been found that the optical film can be obtained without causing any problem that the film breaks, and without increasing the haze. This is presumed that the entanglement between the cellulose ester and the acrylic resin melted in the extruder is strengthened, and the film is hardly broken even when a film is formed by melt extrusion and subjected to a conveyance stress.

  As a result, it has been found that an optical film having improved defects such as cellulose ester and acrylic resin, transparent, and improved problems such as brittleness can be obtained with high productivity without breakage failure, and as a result, the present invention has been achieved. It is.

  Furthermore, it is preferable that the optical film contains acrylic particles.

  In particular, by applying the optical film to at least one surface of a polarizing plate, it is possible to obtain a liquid crystal display device in which the viewing angle variation and the color shift are reduced.

  Hereinafter, the present invention will be described in detail.

<Optical film>
In the present invention, the “optical film” is a functional film used for various display devices such as a liquid crystal display, a plasma display, and an organic EL display, and more specifically, a polarizing plate protective film and a retardation film for a liquid crystal display device. , An antireflection film, a brightness enhancement film, a hard coat film, an antiglare film, an antistatic film, an optical compensation film for expanding the viewing angle, and the like. The optical film of the present invention is preferably used for a polarizing plate protective film (including a polarizing plate protective film provided with a functional layer) and a retardation film.

<Cellulose ester (CE)>
The cellulose ester constituting the optical film used in the present invention (hereinafter also referred to as CE) is not particularly limited as long as it is a cellulose ester having an average substitution degree of 2.0 to 3.0. Acid esters and the like are also used, but it is preferable to use a lower mixed fatty acid ester of cellulose in view of the characteristics of the obtained film such as optical characteristics. Lower fatty acid means a fatty acid having 6 or less carbon atoms, such as cellulose acetate, cellulose propionate, cellulose acetate propionate, cellulose butyrate, cellulose acetate butyrate, cellulose pivalate, cellulose caproate, cellulose Acetate caproate and the like are preferable as the lower fatty acid ester of cellulose. In a cellulose ester substituted with a fatty acid having 7 or more carbon atoms, the mechanical properties of the resulting cellulose ester film tend to be low.

  Among the cellulose esters, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate caproate are preferable. Among these, cellulose diacetate or cellulose acetate propionate is preferable, and cellulose diacetate is particularly preferable.

  Next, the substitution degree of the acyl group of the cellulose ester used for this invention is demonstrated.

  Cellulose has a total of three hydroxyl groups, one at the 2nd, 3rd, and 6th positions of 1 glucose unit. The degree of substitution is the average number of acyl groups bonded to 1 glucose unit. Is a numerical value indicating Therefore, the maximum substitution degree is 3.0. These acyl groups may be substituted on the 2nd, 3rd and 6th positions of the glucose unit on average, or may be substituted with a distribution.

  A preferable substitution degree is a cellulose ester that simultaneously satisfies the following formulas (I), (II), and (III) when the substitution degree of the acetyl group is X and the substitution degree of other acyl groups is Y. In addition, the substitution degree of an acetyl group and the substitution degree of other acyl groups are determined by the method prescribed in ASTM-D817-96.

Formula (I) 2.0 ≦ X + Y ≦ 3.0
Formula (II) 1.2 ≦ X ≦ 2.6
Formula (III) 0 ≦ Y ≦ 1.4
Moreover, the cellulose ester from which the substitution degree of an acyl group differs may be blended, and the cellulose ester film whole may be in the said range. The part not substituted with the acyl group is usually present as a hydroxyl group.

  The cellulose ester used in the present invention preferably has a number average molecular weight (Mn) of 50,000 to 150,000, more preferably a number average molecular weight of 55,000 to 120,000, and a number average molecular weight of 60000 to 100,000. Most preferred.

  Further, the cellulose ester used in the present invention preferably has a weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of 1.3 to 5.5, particularly preferably 1.5 to 5.0. More preferably, it is 1.7-4.0, More preferably, the cellulose ester of 2.0-3.5 is used preferably.

  Mn and Mw / Mn were calculated by gel permeation chromatography in the following manner.

  The measurement conditions are as follows.

Solvent: Tetohydrofuran Equipment: HLC-8220 (manufactured by Tosoh Corporation)
Column: TSKgel SuperHM-M (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Sample concentration: 0.1% by mass
Injection volume: 10 μl
Flow rate: 0.6 ml / min
Calibration curve: Standard polystyrene: PS-1 (manufactured by Polymer Laboratories)
A calibration curve with 9 samples from Mw = 2,560,000 to 580 was used.

  The cellulose ester raw material cellulose used in the present invention may be wood pulp or cotton linter, and the wood pulp may be softwood or hardwood, but softwood is more preferred. A cotton linter is preferably used from the viewpoint of peelability during film formation. The cellulose ester made from these can be mixed suitably or can be used independently.

  For example, the ratio of cellulose ester derived from cellulose linter: cellulose ester derived from wood pulp (coniferous): cellulose ester derived from wood pulp (hardwood) is 100: 0: 0, 90: 10: 0, 85: 15: 0, 50:50: 0, 20: 80: 0, 10: 90: 0, 0: 100: 0, 0: 0: 100, 80:10:10, 85: 0: 15, 40:30:30.

  The cellulose ester can be obtained, for example, by substituting the hydroxyl group of the raw material cellulose with acetic anhydride, propionic anhydride and / or butyric anhydride in the usual manner using an acetyl group, propionyl group and / or butyl group within the above range. . The method for synthesizing such a cellulose ester is not particularly limited, and for example, it can be synthesized with reference to the method described in JP-A-10-45804 or JP-A-6-501040.

  The alkaline earth metal content of the cellulose ester used in the present invention is preferably in the range of 1 to 50 ppm. If it exceeds 50 ppm, lip adhesion stains increase or breakage tends to occur at the slitting part during or after hot stretching. Even if it is less than 1 ppm, it tends to break, but the reason is not well understood. In order to make it less than 1 ppm, since the burden of a washing | cleaning process will become large too much, it is unpreferable also in that point. Furthermore, the range of 1-30 ppm is preferable. The alkaline earth metal as used herein refers to the total content of Ca and Mg, and can be measured using an X-ray photoelectron spectrometer (XPS).

  The residual sulfuric acid content in the cellulose ester used in the present invention is preferably in the range of 0.1 to 45 ppm in terms of elemental sulfur. These are considered to be contained in the form of salts. If the residual sulfuric acid content exceeds 45 ppm, the deposits on the die lip during heat melting increase, such being undesirable. Moreover, since it becomes easy to fracture | rupture at the time of slitting at the time of hot drawing or after hot drawing, it is not preferable. A smaller amount is preferable, but if it is less than 0.1, it is not preferable because the load of the cellulose ester washing process becomes too large, and it is not preferable because it may easily break. This is not well understood, although an increase in the number of washings may affect the resin. Furthermore, the range of 1-30 ppm is preferable. The residual sulfuric acid content can be measured by a method prescribed in ASTM-D817-96.

  The free acid content in the cellulose ester used in the present invention is preferably 1 to 500 ppm. If it exceeds 500 ppm, deposits on the die lip will increase and breakage will easily occur. It is difficult to make it less than 1 ppm by washing. Furthermore, it is preferable that it is the range of 1-100 ppm, and also it becomes difficult to fracture | rupture. A range of 1 to 70 ppm is particularly preferable. The free acid content can be measured by the method prescribed in ASTM-D817-96.

  By washing the synthesized cellulose ester more sufficiently than when it is used in the solution casting method, the residual acid content can be within the above range, and a film is produced by the melt casting method. In this case, adhesion to the lip portion is reduced and a film having excellent flatness can be obtained, and a film having good dimensional change, mechanical strength, transparency, moisture resistance, Rt value and Ro value described later can be obtained. . In addition to washing with water, cellulose ester can be washed with a poor solvent such as methanol or ethanol, or as a result, a mixed solvent of a poor solvent and a good solvent can be used as a poor solvent. Low molecular organic impurities can be removed. Furthermore, washing of the cellulose ester is preferably performed in the presence of an antioxidant such as a hindered amine or a phosphite, which improves the heat resistance and film forming stability of the cellulose ester.

  In order to improve the heat resistance, mechanical properties, optical properties, etc. of cellulose ester, it can be dissolved in a good solvent of cellulose ester and then reprecipitated in a poor solvent to remove low molecular weight components and other impurities of cellulose ester. it can. At this time, it is preferable to carry out in the presence of an antioxidant as in the case of washing the cellulose ester.

  Furthermore, another polymer or a low molecular weight compound may be added after the cellulose ester reprecipitation treatment.

  Moreover, it is preferable that the cellulose ester used by this invention is a thing with few bright spot foreign materials when it is made into a film. A bright spot foreign material is an arrangement in which two polarizing plates are arranged orthogonally (crossed Nicols), a cellulose ester film is arranged between them, light from the light source is applied from one side, and the cellulose ester film is applied from the other side. This is the point where the light from the light source appears to leak when observed. At this time, the polarizing plate used for the evaluation is desirably composed of a protective film having no bright spot foreign matter, and a polarizing plate using a glass plate for protecting the polarizer is preferably used. One of the causes of bright spot foreign matter is the unacetylated or low acetylated cellulose contained in the cellulose ester. Use a cellulose ester with less bright spot foreign matter (use a cellulose ester with a small dispersion degree of substitution). And filtering the melted cellulose ester, or removing the bright spot foreign matters through the filtration process in the same way once in the solution state in at least one of the process of synthesizing the cellulose ester and the process of obtaining the precipitate You can also. Since the molten resin has a high viscosity, the latter method is more efficient.

As the film thickness decreases, the number of bright spot foreign matter per unit area decreases, and as the cellulose ester content in the film decreases, the bright spot foreign matter tends to decrease. 0.01 mm or more is preferably 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, further preferably 50 pieces / cm ² or less, and 30 pieces / cm ² or less. More preferably, it is more preferably 10 pieces / cm ² or less, but most preferably none. Moreover, it is preferable that it is 200 pieces / cm < ² > or less also about the bright spot of 0.005-0.01 mm or less, It is more preferable that it is 100 pieces / cm < ² > or less, It is 50 pieces / cm < ² > or less. Even more preferred is 30 / cm ² or less, still more preferred is 10 / cm ² or less, and most preferred is none.

  When removing bright spot foreign matter by melt filtration, filtering the cellulose ester composition to which a plasticizer, a deterioration inhibitor, an antioxidant, etc. are added and mixed is more effective than filtering the melted cellulose ester alone. It is preferable because the removal efficiency of point foreign matters is high. Of course, the cellulose ester may be dissolved in a solvent during the synthesis and reduced by filtration. What mixed the ultraviolet absorber and other additives suitably can be filtered. Filtration is preferably performed at a viscosity of a melt containing cellulose ester of 10,000 Pa · s or less, more preferably 5000 Pa · s or less, even more preferably 1000 Pa · s or less, and even more preferably 500 Pa · s or less. . As the filter medium, conventionally known materials such as glass fibers, cellulose fibers, filter paper, and fluorine resins such as tetrafluoroethylene resin are preferably used, and ceramics, metals and the like are particularly preferably used. The absolute filtration accuracy is preferably 50 μm or less, more preferably 30 μm or less, still more preferably 10 μm or less, and even more preferably 5 μm or less. These can be used in combination as appropriate. The filter medium can be either a surface type or a depth type, but the depth type is preferably used because it is relatively less clogged.

  In another embodiment, a cellulose ester obtained by dissolving the raw material cellulose ester at least once in a solvent and then drying the solvent may be used. In that case, a cellulose ester which is dissolved in a solvent together with at least one of a plasticizer, an ultraviolet absorber, a deterioration inhibitor, an antioxidant and a matting agent and then dried is used. As the solvent, a good solvent used in a solution casting method such as methylene chloride, methyl acetate or dioxolane can be used, and a poor solvent such as methanol, ethanol or butanol may be used at the same time. You may cool to -20 degrees C or less in the process of dissolution, or you may heat to 80 degrees C or more. When such a cellulose ester is used, each additive in a molten state can be easily made uniform, and optical characteristics can be made uniform.

<Cellulose ester (GCE) having a repeating unit represented by formula (G-1) or (G-2)>
The cellulose ester used in the present invention is different from the cellulose ester (CE) and has a repeating unit represented by the general formula (G-1) or (G-2) (hereinafter referred to as GCE or grafting). (Also referred to as cellulose ester).

  Specific examples of A in general formula (G-1) or (G-2) are given below.

A-1-CH ₂ CH _{2-
A-2 -CH 2 CH 2 CH} 2 -
A-3 -CH = CH-

A-6 —CH ₂ C (CH ₃ ) ₂ —
A-7 —CH ₂ (CH ₂ ) ₂ CH ₂ —
A-8 —CH ₂ (CH ₂ ) ₃ CH ₂ —
Specific examples of B in the general formula (G-1) are given below.

B-1 _{-CH 2} CH 2 -
_{B-2 -CH 2 (CH 2} ) 2 CH 2 -

B-5 —CH ₂ (CH ₂ ) ₃ CH ₂ —
In the present invention, the grafted cellulose ester is a cellulose having an unsubstituted hydroxyl group, or in the presence of a cellulose ester in which some hydroxyl groups have already been substituted with an acyl group such as an acetyl group, a propionyl group, a butyryl group, or a phthalyl group. Esterification reaction of polybasic acid or anhydride thereof with polyhydric alcohol, cyclic diester (for example, lactide (L-lactide, D-lactide or a mixture thereof)), lactone (for example, β-butyrolactone, δ-valero) Lactone, γ-butyrolactone, ε-caprolactone), and self-condensation of L-lactic acid and D-lactic acid.

  Examples of the polybasic acid anhydride used in the esterification reaction include, but are not limited to, maleic anhydride, phthalic anhydride, and fumaric anhydride.

  Examples of the polyhydric alcohol that can be used in the esterification reaction include glycerin, ethylene glycol, and propylene glycol, but are not particularly limited.

  As the catalyst used for the esterification reaction, the reaction can be carried out without a catalyst, but a known Lewis acid catalyst or the like can be used. Examples of catalysts that can be used include metals such as tin, zinc, titanium, bismuth, zirconium, germanium, antimony, sodium, potassium, and aluminum, and derivatives thereof. Particularly, the derivatives include metal organic compounds, carbonates, oxides, halides. Is preferred. Specific examples include octyl tin, tin chloride, zinc chloride, titanium chloride, alkoxy titanium, germanium oxide, zirconium oxide, antimony trioxide, and alkyl aluminum. Moreover, an acid catalyst typified by p-toluenesulfonic acid can also be used as the catalyst. Moreover, in order to accelerate | stimulate the dehydration reaction of carboxylic acid and alcohol, you may add well-known compounds, such as carbodiimide and dimethylaminopyridine.

  Such a reaction may be a reaction in an organic solvent capable of dissolving cellulose ester and other compounds to be reacted, or a reaction using a batch kneader capable of heating and stirring while adding a shearing force. It may be by reaction using a uniaxial or biaxial extruder.

  The ratio of the repeating unit represented by the general formula (G-1) or (G-2) (hereinafter also referred to as a graft chain) is expressed in terms of hydroxy acid with respect to 1 mol of glucose unit constituting the cellulose ester ( For example, in terms of ε-caprolactone, in terms of hydroxyhexanoic acid, in lactide in terms of lactic acid, etc., the average may be 0.1 to 15 mol, for example, preferably 0.2 to 2 mol, more preferably 0.3 to 1. 0.0 mole. In addition, by making the graft chain ratio of the hydroxy acid component with respect to the whole cellulose ester the above ratio, the compatibility between the cellulose ester, which is a constituent of the optical film of the present invention, and the acrylic resin is improved, and the haze of the film is lowered. Great effect.

  The ratio (mole) of the hydroxy acid component refers to the hydroxy acid component added (or grafted) to the entire glucose unit of the cellulose ester, regardless of whether the degree of polymerization of the graft chain is greater than 1 or 1. The average number of moles added is shown.

  The average degree of polymerization of the graft chain (or the average number of moles added in terms of hydroxy acid of the hydroxy acid component constituting the graft chain) may be 1 to 70, preferably 1 to 20, more preferably in terms of hydroxy acid. Is 2-10.

  The average molecular weight of the graft chain is a number average molecular weight of 100 to 10,000, preferably 100 to 5000, and more preferably 200 to 2000. When the polymerization degree and molecular weight of the graft chain (particularly, the graft chain of an α-hydroxy acid component such as lactide) increase, the characteristics of the graft chain are greatly reflected. For example, if the polymerization degree and molecular weight of the graft chain are too large, the effect tends to decrease in improving the compatibility between the cellulose ester and the acrylic resin.

In the grafted cellulose ester, the acyl group and the degree of substitution of the graft chain, the degree of polymerization of the graft chain (molecular weight), and the like can be determined by conventional methods such as nuclear magnetic resonance spectrum (NMR) ( ¹ H-NMR, ¹³ C-NMR, etc. ) And the like.

  The grafted cellulose ester used in the present invention may have a hydroxyl group. Examples of such a hydroxyl group include a hydroxyl group at the end of a graft chain, a hydroxyl group remaining in a glucose unit, and the like. Such a hydroxyl group may be protected by a protecting group as necessary. The protecting group is not particularly limited as long as it is a non-reactive group capable of protecting a hydroxyl group, and is an alkyl group (for example, methyl group, ethyl group, hexyl group, cyclohexyl group, etc.), cycloalkyl group (for example, cyclohexyl group). Etc.), aryl group (eg phenyl group etc.), aralkyl group (eg benzyl group etc.), bridged cyclic hydrocarbon group (eg adamantyl group etc.), oxacycloalkyl group (eg 5-8 membered oxacyclo) Alkyl group), alkoxyalkyl group (for example, C1-6 alkoxy-C1-6 alkyl group), alkylcarbonyl group (C1-10 alkylcarbonyl group), acyl group (acetyl group, pivaloyl group, benzoyl group, cycloalkylcarbonyl group, Arylcarbonyl group, etc.).

  A protecting group may protect a hydroxyl group individually or in combination of 2 or more types.

  In the grafted cellulose ester in which the hydroxyl group is protected by the protecting group, the ratio of the protecting group (or the protecting ratio of the hydroxy group of the graft chain) is preferably in the range of 0.5 to 1 mol with respect to 1 mol of the graft chain. .

  Moreover, when the grafted cellulose ester has a carboxyl group, the carboxyl group may also be protected (or sealed) in the same manner as the hydroxyl group.

  When the raw material before grafting is a cellulose ester, the degree of substitution can be selected as appropriate, but 2.0 to 3.0 is preferable from the viewpoint of compatibility and brittleness. Further, when the substituent of the raw material cellulose ester is an acyl group, an acyl group having 2 to 20 carbon atoms is preferable, and specifically, acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, octanoyl, lauroyl, stearoyl Etc.

  When a graft chain is introduced into cellulose or cellulose ester, an oligomer or polyester having a repeating unit represented by the general formula (G-1) or (G-2) may be generated as a side reaction. But you can. These oligomers and polyesters have a number average molecular weight of 300 to 10,000, and preferably 500 to 8,000 from the viewpoint of plasticity.

  The grafted cellulose ester is preferably mixed in a proportion of 0.1 to 50% by mass, more preferably in a proportion of 0.5 to 30% by mass with respect to the total mass of the resin forming the optical film. preferable.

  At this time, the haze is not particularly limited as long as the haze when the optical film is formed is 1.0 or less, but the haze is preferably 0.5 or less. More preferably, the haze when the optical film is formed is 0.3 or less.

<Acrylic resin>
The acrylic resin used in the present invention is a polymer containing at least one of an acrylate monomer or a methacrylic acid ester monomer as a constituent component, but a single monomer polymer or a copolymer of two or more monomers. But you can.

  Preferred monomers include alkyl methacrylates having 2 to 18 carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, α, β-unsaturated acids such as acrylic acid and methacrylic acid, maleic acid, and fumaric acid. Acids, itaconic acid-containing unsaturated group-containing divalent carboxylic acids, styrene, α-methylstyrene and other aromatic vinyl compounds, acrylonitrile, methacrylonitrile and other α, β-unsaturated nitriles, maleic anhydride, maleimide, N -Substituted maleimide, glutaric anhydride and the like can be mentioned, and these can be used alone or in combination of two or more monomers.

  Among these, from the viewpoint of thermal decomposition resistance and fluidity of the copolymer, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, n-butyl methacrylate, n-butyl acrylate, isobutyl methacrylate, isobutyl acrylate, 2-ethylhexyl methacrylate 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, cyclohexyl methacrylate, cyclohexyl acrylate, and the like are preferable, and methyl methacrylate, methyl acrylate, and n-butyl methacrylate are particularly preferably used.

  The acrylic resin used in the optical film of the present invention has a weight average molecular weight (Mw) of 800, particularly from the viewpoint of improving brittleness as an optical film and improving transparency when it is compatible with cellulose ester and grafted cellulose ester. More than 500000 is preferable. Especially preferably, it exists in the range of 2000-50000. When the weight average molecular weight (Mw) of the acrylic resin is less than 10,000, the brittleness improvement effect is small, but the compatibility is improved. Conversely, when the weight average molecular weight (Mw) exceeds 10,000, the compatibility with the cellulose ester tends to deteriorate, but the brittleness is improved. In consideration of the ratio between the cellulose ester and the acrylic resin, it is preferable to select a molecular weight satisfying compatibility and brittleness.

  The weight average molecular weight of the acrylic resin of the present invention can be measured by gel permeation chromatography. The measurement conditions are as follows.

Solvent: Tetohydrofuran Equipment: HLC-8220 (manufactured by Tosoh Corporation)
Column: TSKgel SuperHM-M (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Sample concentration: 0.1% by mass
Injection volume: 10 μl
Flow rate: 0.6 ml / min
Calibration curve: Standard polystyrene: PS-1 (manufactured by Polymer Laboratories)
A calibration curve with 9 samples from Mw = 2,560,000 to 580 was used.

  There is no restriction | limiting in particular as a manufacturing method of the acrylic resin in this invention, You may use any well-known methods, such as suspension polymerization, emulsion polymerization, block polymerization, or solution polymerization. Here, as a polymerization initiator, a normal peroxide type and an azo type can be used, and a redox type can also be used. Regarding the polymerization temperature, suspension or emulsion polymerization may be performed at 30 to 100 ° C, and bulk or solution polymerization may be performed at 80 to 160 ° C. In order to control the reduced viscosity of the obtained copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.

  A commercially available thing can also be used as an acrylic resin which concerns on this invention. For example, Actflow UMM-1001, UT-1001 (manufactured by Soken Chemical Co., Ltd.), ARUFON UP-1000, UP-1080, UP-1170, UP-2000 (manufactured by Toagosei Co., Ltd.), Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Acripet V, VH4, MD, MF, VH5 (Mitsubishi Rayon Co., Ltd.), Dialan BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 KT80 (manufactured by Denki Kagaku Kogyo Co., Ltd.) and the like. Two or more acrylic resins can be used in combination.

  The acrylic resin is preferably mixed at a rate of 1 to 70% by mass, more preferably at a rate of 10 to 50% by mass, with respect to the total mass of the resin forming the optical film.

  At this time, the haze is not particularly limited as long as the haze when the optical film is formed is 1.0 or less, but the haze is preferably 0.5 or less. More preferably, the haze when the optical film is formed is 0.3 or less.

(Acrylic resin obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the general formula (AM) and at least one acrylic ester monomer or methacrylic ester monomer)
The optical film of the present invention is obtained by copolymerizing, as an acrylic resin, an ethylenically unsaturated monomer having a partial structure represented by the general formula (AM) and at least one acrylic ester monomer or methacrylic ester monomer. It is preferable to contain the resulting polymer (hereinafter also referred to as AMP).

In the general formula (AM), R ¹ , R ² , and R ³ are each independently an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group, a pentyl group, a hexyl group, Octyl group, dodecyl group, trifluoromethyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), aryl group (eg, phenyl group, naphthyl group, etc.), acylamino group (eg, acetylamino group, benzoyl) Amino group, etc.), alkylthio group (eg, methylthio group, ethylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkenyl group (eg, vinyl group, 2-propenyl group, 3-butenyl group, 1 -Methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4- Xenyl group, cyclohexenyl group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom etc.), alkynyl group (eg, propargyl group etc.), heterocyclic group (eg, pyridyl group, thiazolyl group, etc.) Oxazolyl group, imidazolyl group, etc.), alkylsulfonyl group (eg, methylsulfonyl group, ethylsulfonyl group, etc.), arylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, etc.), alkylsulfinyl group (eg, methylsulfinyl group, etc.) ), Arylsulfinyl group (for example, phenylsulfinyl group), phosphono group, acyl group (for example, acetyl group, pivaloyl group, benzoyl group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl) Base Butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylamino) Sulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), sulfonamide group (for example, methanesulfonamide group, benzenesulfonamide) Group), cyano group, alkoxy group (for example, methoxy group, ethoxy group, propoxy group, etc.), aryloxy group (for example, phenoxy group, naphthyl group) Si group etc.), heterocyclic oxy group, siloxy group, acyloxy group (eg acetyloxy group, benzoyloxy group etc.), sulfonic acid group, salt of sulfonic acid, aminocarbonyloxy group, amino group (eg amino group, Ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, etc.), anilino group (for example, phenylamino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino group) 2-pyridylamino group, etc.), imide group, ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2- Pyridylaminoureido Etc.), alkoxycarbonylamino group (eg methoxycarbonylamino group, phenoxycarbonylamino group etc.), alkoxycarbonyl group (eg methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl etc.), aryloxycarbonyl group (eg phenoxycarbonyl) Groups), heterocyclic thio groups, thioureido groups, carboxyl groups, carboxylic acid salts, hydroxyl groups, mercapto groups, nitro groups, and the like. These substituents may be further substituted with the same substituent.

Any two of R ¹ , R ² , and R ³ may be bonded to each other to form a cyclic structure, and the ring in the case of forming a cyclic structure includes a saturated or unsaturated monocyclic ring Specific examples include, for example, pyridine ring, thiazole ring, piperidine ring, piperazine ring, pyrrole ring, morpholine ring, imidazole ring, indole ring, quinoline ring, pyrimidine ring, Heterocycles such as isoindoline ring can be mentioned.

  Examples of the substituent having an ethylenically unsaturated bond include a vinyl group, allyl group, acryloyl group, methacryloyl group, styryl group, acrylamide group, methacrylamide group, vinyl cyanide group, 2-cyanoacryloxy group, 1 , 2-epoxy group, vinyl benzyl group, vinyl ether group and the like, preferably vinyl group, acryloyl group, methacryloyl group, acrylamide group, and methacrylamide group.

  Although the preferable specific example of the ethylenically unsaturated monomer which has the partial structure represented by the said general formula (AM) used by this invention below is illustrated, it is not limited to these.

  The ethylenically unsaturated monomers having a partial structure represented by the general formula (AM) can be used alone or in combination of two or more, particularly preferably N-vinylpyrrolidone, N-acryloylmorpholine, N-vinylpiperidone, N-vinylcaprolactam or a mixture thereof.

  The ethylenically unsaturated monomer having a partial structure represented by the general formula (AM) used in the present invention can be obtained as a commercial product or synthesized with reference to known literature.

  Examples of the acrylic acid ester monomer or methacrylic acid ester monomer copolymerized with the ethylenically unsaturated monomer having a partial structure represented by the general formula (AM) include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, Butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, octyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, methacrylic acid Dimethylaminoethyl, diethylaminoethyl methacrylate, etc., or methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, i-butyl acrylate, t-butyl acrylate Octyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethoxyethyl acrylate, diethylene glycol ethoxylate acrylate, 3-methoxybutyl acrylate, acrylic acid Examples include benzyl, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, and the like. These can be copolymerized with an ethylenically unsaturated monomer having a partial structure represented by the general formula (AM) singly or in combination of two or more.

  Of these monomers, methyl methacrylate, butyl methacrylate, and methyl acrylate are preferred.

  The weight average molecular weight of the acrylic copolymer used in the present invention is preferably in the range of 800 to 500,000. Especially preferably, it exists in the range of 2000-50000. When the weight average molecular weight (Mw) of the acrylic resin is less than 10,000, the brittleness improvement effect is small, but the compatibility is improved. Conversely, when the weight average molecular weight (Mw) exceeds 10,000, the compatibility with the cellulose ester tends to deteriorate, but the brittleness is improved. In consideration of the ratio between the cellulose ester and the acrylic resin, it is preferable to select a molecular weight satisfying compatibility and brittleness.

  The proportion of the ethylenically unsaturated monomer having the partial structure represented by the general formula (AM) in the acrylic copolymer used in the present invention is compatible with the obtained copolymer polymer and the combined resin, It is selected in consideration of the effect on transparency and mechanical strength. Preferably, the copolymer contains 10 to 80% by mass, more preferably 30 to 70% by mass of an ethylenically unsaturated monomer having a partial structure represented by the general formula (AM) in the molecule. It is preferable to do this.

  The method for polymerizing the acrylic copolymer in the present invention is not particularly limited, but conventionally known methods can be widely adopted, and examples thereof include radical polymerization, anionic polymerization, and cationic polymerization. Examples of the initiator for the radical polymerization method include azo compounds and peroxides, and examples thereof include azobisisobutyronitrile (AIBN), azobisisobutyric acid diester derivatives, and benzoyl peroxide. The polymerization solvent is not particularly limited. For example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, halogenated hydrocarbon solvents such as dichloroethane and chloroform, ether solvents such as tetrahydrofuran and dioxane, and amide solvents such as dimethylformamide. And alcohol solvents such as methanol, ester solvents such as methyl acetate and ethyl acetate, ketone solvents such as acetone, cyclohexanone and methyl ethyl ketone, and water solvents. Depending on the selection of the solvent, solution polymerization for polymerization in a homogeneous system, precipitation polymerization for precipitation of the produced polymer, and emulsion polymerization for polymerization in a micellar state can also be performed.

  The weight average molecular weight of the copolymer can be adjusted by a known molecular weight adjusting method. Examples of such a molecular weight adjusting method include a method of adding a chain transfer agent such as carbon tetrachloride, lauryl mercaptan, octyl thioglycolate, and the like. The polymerization temperature is usually from room temperature to 130 ° C, preferably 50 to 110 ° C.

  The acrylic copolymer is preferably mixed in a proportion of 1 to 70% by mass, more preferably in a proportion of 10 to 50% by mass with respect to the total mass of the resin forming the optical film.

  At this time, the haze is not particularly limited as long as the haze when the optical film is formed is 1.0 or less, but the haze is preferably 0.5 or less. More preferably, the haze when the optical film is formed is 0.3 or less.

<Acrylic particles>
The optical film of the present invention preferably contains acrylic particles.

  The acrylic particle according to the present invention represents an acrylic component present in a particle state (also referred to as an incompatible state) in an optical film containing the cellulose ester, grafted cellulose ester, and acrylic resin in a compatible state. .

  The acrylic particles may be obtained by, for example, collecting a predetermined amount of the produced optical film, dissolving it in a solvent, stirring, and sufficiently dissolving and dispersing the PTFE membrane filter having a pore diameter less than the average particle diameter of the acrylic particles. It is preferable that the weight of the insoluble matter filtered and collected is 90% by mass or more of the acrylic particles added to the optical film.

  The acrylic particles used in the present invention are not particularly limited, but are preferably acrylic particles having a layer structure of two or more layers, and particularly preferably the following multilayer structure acrylic granular composite.

  The multilayer structure acrylic granular composite is formed by laminating an innermost hard layer polymer, a cross-linked soft layer polymer exhibiting rubber elasticity, and an outermost hard layer polymer from the center to the outer periphery. This refers to a particulate acrylic polymer having a structure.

  That is, the multilayer structure acrylic granular composite is a multilayer structure acrylic granular composite comprising an innermost hard layer, a crosslinked soft layer, and an outermost hard layer from the central portion toward the outer peripheral portion. This three-layer core-shell multilayer acrylic granular composite is preferably used.

  Preferred embodiments of the multilayer structure acrylic granular composite used in the acrylic resin composition according to the present invention include the following. (A) Monomer composed of 80 to 98.9% by mass of methyl methacrylate, 1 to 20% by mass of alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, and 0.01 to 0.3% by mass of polyfunctional grafting agent An innermost hard layer polymer obtained by polymerizing a mixture of the body, (b) in the presence of the innermost hard layer polymer, an alkyl acrylate having an alkyl group of 4 to 8 carbon atoms of 75 to 98.5% by mass. A crosslinked soft layer polymer obtained by polymerizing a mixture of monomers comprising 0.01 to 5% by mass of a polyfunctional crosslinking agent and 0.5 to 5% by mass of a multifunctional grafting agent, (c) In the presence of a polymer comprising an inner hard layer and a crosslinked soft layer, a mixture of monomers comprising 80 to 99% by mass of methyl methacrylate and 1 to 20% by mass of alkyl acrylate having 1 to 8 carbon atoms in the alkyl group. Outermost obtained by polymerizing The layered polymer has a three-layer structure, and the obtained three-layered polymer is the innermost hard layer polymer (a) 5 to 40% by mass, the soft layer polymer (b) 30 to 60% by mass. And the outermost hard layer polymer (c) 20 to 50% by mass, having an insoluble part when fractionated with acetone, and an insoluble granular part having a methyl ethyl ketone swelling degree of 1.5 to 4.0 Complex.

  As disclosed in Japanese Patent Publication No. 60-17406 or Japanese Patent Publication No. 3-39095, not only the composition and particle size of each layer of the multilayer structure acrylic granular composite are defined, but also the multilayer structure acrylic granular composite. By setting the tensile modulus of the body and the degree of swelling of methyl ethyl ketone in the acetone-insoluble part within a specific range, it is possible to realize a further sufficient balance between impact resistance and stress whitening resistance.

  Here, the innermost hard layer polymer (a) constituting the multi-layer structure acrylic granular composite is 80 to 98.9% by mass of methyl methacrylate and 1 to 20% of alkyl acrylate having 1 to 8 carbon atoms in the alkyl group. % And a mixture of monomers consisting of 0.01 to 0.3% by mass of a polyfunctional grafting agent is preferred.

  Here, examples of the alkyl acrylate having 1 to 8 carbon atoms in the alkyl group include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like. And n-butyl acrylate are preferably used.

  The proportion of the alkyl acrylate unit in the innermost hard layer polymer (a) is 1 to 20% by mass. When the unit is less than 1% by mass, the thermal decomposability of the polymer is increased, while the unit is 20% by mass. If it exceeds 50%, the glass transition temperature of the innermost hard layer polymer (c) is lowered, and the impact resistance imparting effect of the three-layer structure acrylic granular composite is lowered.

  Examples of the polyfunctional grafting agent include polyfunctional monomers having different polymerizable functional groups, such as allyl esters of acrylic acid, methacrylic acid, maleic acid, and fumaric acid, and allyl methacrylate is preferably used. . The polyfunctional grafting agent is used to chemically bond the innermost hard layer polymer and the soft layer polymer, and the ratio used during the innermost hard layer polymerization is 0.01 to 0.3% by mass. .

  The crosslinked soft layer polymer (b) constituting the acrylic granular composite is an alkyl acrylate 75-98.5 having 1 to 8 carbon atoms in the presence of the innermost hard layer polymer (a). What is obtained by polymerizing a monomer mixture consisting of mass%, polyfunctional crosslinking agent 0.01 to 5 mass% and polyfunctional grafting agent 0.5 to 5 mass% is preferred.

  Here, as the alkyl acrylate having 4 to 8 carbon atoms in the alkyl group, n-butyl acrylate or 2-ethylhexyl acrylate is preferably used.

  In addition to these polymerizable monomers, it is possible to copolymerize 25% by mass or less of other monofunctional monomers capable of copolymerization.

  Other monofunctional monomers that can be copolymerized include styrene and substituted styrene derivatives. As for the ratio of the alkyl acrylate having 4 to 8 carbon atoms in the alkyl group and styrene, the glass transition temperature of the polymer (b) decreases as the former increases, that is, the ratio can be softened.

  On the other hand, from the viewpoint of the transparency of the resin assembly, the refractive index of the soft layer polymer (b) at room temperature is set to the innermost hard layer polymer (a), the outermost hard layer polymer (c), and the hard heat. It is more advantageous to make it closer to the plastic acrylic resin, and the ratio between them is selected in consideration of these.

  As the polyfunctional grafting agent, those mentioned in the item of the innermost layer hard polymer (a) can be used. The polyfunctional grafting agent used here is used to chemically bond the soft layer polymer (b) and the outermost hard layer polymer (c), and the proportion used during the innermost hard layer polymerization is impact resistance. 0.5-5 mass% is preferable from a viewpoint of the property provision effect.

  As the polyfunctional crosslinking agent, generally known crosslinking agents such as divinyl compounds, diallyl compounds, diacrylic compounds, and dimethacrylic compounds can be used, and polyethylene glycol diacrylate (molecular weight 200 to 600) is preferably used.

  The polyfunctional cross-linking agent used here is used to generate a cross-linked structure at the time of polymerization of the soft layer (b) and develop an effect of imparting impact resistance. However, if the above-mentioned polyfunctional grafting agent is used during the polymerization of the soft layer, the polyfunctional crosslinking agent is not an essential component because the crosslinked structure of the soft layer (b) is generated to some extent. Is preferably 0.01 to 5% by mass from the viewpoint of imparting impact resistance.

  In the presence of the innermost hard layer polymer (a) and the soft layer polymer (b), the outermost hard layer polymer (c) constituting the multilayer structure acrylic granular composite is 80 to 99 masses of methyl methacrylate. % And a mixture of monomers consisting of 1 to 20% by mass of an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group is preferred.

  Here, as the acrylic alkylate, those described above are used, and methyl acrylate and ethyl acrylate are preferably used. The ratio of the alkyl acrylate unit in the outermost hard layer (c) is preferably 1 to 20% by mass.

  Further, for the purpose of improving the compatibility with the acrylic resin during the polymerization of the outermost hard layer (c), an alkyl mercaptan or the like can be used as a chain transfer agent to adjust the molecular weight.

  In particular, it is preferable to provide the outermost hard layer with a gradient such that the molecular weight gradually decreases from the inside toward the outside in order to improve the balance between elongation and impact resistance. Specifically, the outermost hard layer is divided into two or more monomer mixtures for forming the outermost hard layer, and the amount of chain transfer agent to be added each time is increased sequentially. It is possible to decrease the molecular weight of the polymer forming the layer from the inside to the outside of the multilayer structure acrylic granular composite.

  The molecular weight formed at this time can also be examined by polymerizing a mixture of monomers used each time under the same conditions and measuring the molecular weight of the resulting polymer.

  The particle diameter of the acrylic particles preferably used in the present invention is not particularly limited, but is preferably 10 nm or more and 1000 nm or less, more preferably 20 nm or more and 500 nm or less, and particularly 50 nm. As mentioned above, it is most preferable that it is 400 nm or less.

  In the acrylic granular composite that is a multilayer structure polymer preferably used in the present invention, the mass ratio of the core and the shell is not particularly limited, but when the entire multilayer structure polymer is 100 parts by mass, The core layer is preferably 50 parts by mass or more and 90 parts by mass or less, and more preferably 60 parts by mass or more and 80 parts by mass or less. In addition, the core layer here is an innermost hard layer.

  Examples of such commercially available multilayered acrylic granular composites include, for example, “Metablene” manufactured by Mitsubishi Rayon Co., “Kane Ace” manufactured by Kaneka Chemical Co., Ltd., “Paralloid” manufactured by Kureha Chemical Co., Ltd., Rohm and Haas “Acryloid” manufactured by KK, “Staffyroid” manufactured by Ganz Kasei Kogyo Co., Ltd., “Parapet SA” manufactured by Kuraray Co., Ltd., and the like can be used alone or in combination of two or more.

  In addition, specific examples of the acrylic particles that are graft copolymers that are preferably used as the acrylic particles preferably used in the present invention include unsaturated carboxylic acid ester monomers, unsaturated monomers in the presence of a rubbery polymer. A graft copolymer obtained by copolymerizing a mixture of a monomer comprising a saturated carboxylic acid monomer, an aromatic vinyl monomer, and, if necessary, other vinyl monomers copolymerizable therewith. Is mentioned.

  There is no particular limitation on the rubbery polymer used for the acrylic particles as the graft copolymer, but diene rubber, acrylic rubber, ethylene rubber, and the like can be used. Specific examples include polybutadiene, styrene-butadiene copolymer, block copolymer of styrene-butadiene, acrylonitrile-butadiene copolymer, butyl acrylate-butadiene copolymer, polyisoprene, butadiene-methyl methacrylate copolymer, Butyl acrylate-methyl methacrylate copolymer, butadiene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-isoprene copolymer, and ethylene-methyl acrylate copolymer A polymer etc. are mentioned. These rubbery polymers can be used alone or in a mixture of two or more.

  In addition, when adding acrylic particles to the optical film of the present invention, the refractive index of the mixture of cellulose ester, grafted cellulose ester, and acrylic resin is close to the refractive index of the acrylic particles, so that a highly transparent film is obtained. It is preferable in terms of obtaining.

  In order to satisfy such a refractive index condition, a method for adjusting the composition ratio of each monomer unit of the acrylic resin and / or a composition ratio of the rubbery polymer or monomer used for the acrylic particles is adjusted. Depending on the method, the refractive index difference can be reduced, and an optical film excellent in transparency can be obtained.

  The method for blending acrylic particles in the present invention is not particularly limited, and after pre-blending the resin composition of the optical film of the present invention, usually at 200 to 350 ° C., uniaxial or biaxial extrusion while adding acrylic particles A method of uniformly melt-kneading with a machine is preferably used.

  Also, a solution in which acrylic particles are dispersed in advance is added to and mixed with a solution (dope solution) in which the resin composition of the optical film of the present invention is dissolved, and acrylic particles and other optional additives are dissolved and mixed. A method such as in-line addition of the prepared solution can be used.

  A commercially available thing can also be used as an acrylic particle concerning this invention. For example, metabrene W-341 (C2) (manufactured by Mitsubishi Rayon Co., Ltd.), Chemisnow MR-2G (C3), MS-300X (C4) (manufactured by Soken Chemical Co., Ltd.) and the like can be mentioned.

  It is preferable to contain the said acrylic particle in the ratio of 0.1-30 mass% with respect to the total mass of resin which forms an optical film, and it is still more preferable to contain in the ratio of 1.0-15 mass%.

<Additives>
Among the three additives (1) to (3) described below, the optical film of the present invention has the purpose of further improving the performance of a polarizing plate produced using the optical film and a liquid crystal display device. It is preferable to add at least one or more. Particularly preferably, all three types are added.

(1) Carbon radical scavenger (2) Primary antioxidant having hydrogen radical donating ability for peroxy radicals (3) Secondary antioxidant additive having a reducing action on peroxide (Carbon radical scavenger)
The optical film of the present invention preferably contains at least one carbon radical scavenger.

  In the present invention, the “carbon radical scavenger” has a group (for example, an unsaturated group such as a double bond or a triple bond) that allows a carbon radical to rapidly undergo an addition reaction, and is followed by polymerization or the like after the addition of the carbon radical. It means a compound that gives a stable product in which no reaction takes place.

  Examples of the carbon radical scavenger include compounds having a radical polymerization inhibitory ability such as a group (unsaturated group such as (meth) acryloyl group and aryl group) that reacts quickly with a carbon radical in the molecule, and a phenolic or lactone based compound. Particularly useful are compounds represented by the following general formula (1) or general formula (2).

In the general formula (1), R ₁₁ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, particularly preferably a hydrogen atom or a methyl group. .

R ₁₂ and R ₁₃ each independently represent an alkyl group having 1 to 8 carbon atoms, and may be linear or have a branched structure or a ring structure.

R ₁₂ and R ₁₃ are preferably a structure represented by “* —C (CH ₃ ) ₂ —R ′” containing a quaternary carbon (* represents a linking site to an aromatic ring, and R ′ has 1 carbon atom. Represents an alkyl group of ˜5).

R ₁₂ is more preferably a tert-butyl group, a tert-amyl group or a tert-octyl group. R ₁₃ is more preferably a tert-butyl group or a tert-amyl group. As the compound represented by the general formula (1), commercially available products include “Sumilizer GM, Sumilizer GS” (both trade names, manufactured by Sumitomo Chemical Co., Ltd.) and the like.

  Specific examples (I-1 to I-18) of the compound represented by the general formula (1) are illustrated below, but the present invention is not limited thereto.

In the general formula (2), R _{22 to} R ₂₅ each independently represent a hydrogen atom or a substituent, and the substituent represented by R _{22 to} R ₂₅ is not particularly limited. (For example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group) Etc.), aryl groups (eg phenyl group, naphthyl group etc.), acylamino groups (eg acetylamino group, benzoylamino group etc.), alkylthio groups (eg methylthio group, ethylthio group etc.), arylthio groups (eg phenylthio) Group, naphthylthio group, etc.), alkenyl group (for example, vinyl group, 2-propenyl group, 3- Tenenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, etc.), halogen atom (for example, fluorine atom, chlorine atom, bromine atom) , Iodine atoms, etc.), alkynyl groups (eg, propargyl group, etc.), heterocyclic groups (eg, pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, etc.), alkylsulfonyl groups (eg, methylsulfonyl group, ethylsulfonyl group, etc.) ), Arylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, etc.), alkylsulfinyl group (eg, methylsulfinyl group, etc.), arylsulfinyl group (eg, phenylsulfinyl group, etc.), phosphono group, acyl group (eg, Acetyl group, pivaloyl group, benzoyl group, etc.), potassium Vamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group) , Methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group Group), sulfonamide group (for example, methanesulfonamide group, benzenesulfonamide group, etc.), cyano group, alkoxy group (for example, Methoxy group, ethoxy group, propoxy group etc.), aryloxy group (eg phenoxy group, naphthyloxy group etc.), heterocyclic oxy group, siloxy group, acyloxy group (eg acetyloxy group, benzoyloxy group etc.), sulfone Acid group, salt of sulfonic acid, aminocarbonyloxy group, amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, etc.), anilino Groups (for example, phenylamino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino group, 2-pyridylamino group, etc.), imide group, ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexyl) Ureido group, octyl urei Group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), alkoxycarbonylamino group (eg methoxycarbonylamino group, phenoxycarbonylamino group etc.), alkoxycarbonyl group (eg methoxycarbonyl group) Ethoxycarbonyl group, phenoxycarbonyl, etc.), aryloxycarbonyl group (eg, phenoxycarbonyl group, etc.), heterocyclic thio group, thioureido group, carboxyl group, carboxylic acid salt, hydroxyl group, mercapto group, nitro group, etc. Groups. These substituents may be further substituted with the same substituent.

In the general formula (2), R ₂₆ represents a hydrogen atom or a substituent, and examples of the substituent represented by R ₂₆ include the same groups as the substituents represented by R _{22 to} R _25. .

  In the general formula (2), n represents 1 or 2.

In the general formula (2), when n is 1, R ₂₁ represents a substituent, and when n is 2, R ₂₁ represents a divalent linking group. When R ₂₁ represents a substituent, examples of the substituent include the same groups as the substituents represented by R _{22 to} R ₂₅ .

When R ₂₁ represents a divalent linking group, examples of the divalent linking group include an alkylene group that may have a substituent, an arylene group that may have a substituent, an oxygen atom, a nitrogen atom, and a sulfur atom. Or a combination of these linking groups.

  In the general formula (2), n is preferably 1.

  Next, although the specific example of a compound represented by the said General formula (2) in this invention is shown, this invention is not limited by the following specific examples.

  The carbon radical scavenger can be used alone or in combination of two or more thereof, and the amount of the carbon radical scavenger is appropriately selected within a range that does not impair the object of the present invention, but the total mass of the resin that forms the optical film. On the other hand, it is preferable to add 0.001-10.0 mass parts normally, More preferably, it is 0.01-5.0 mass parts, Most preferably, it is 0.1-1.0 mass part.

(Primary antioxidant)
The optical film of the present invention preferably contains at least one primary antioxidant having a hydrogen radical donating ability for peroxy radicals.

  In the present invention, the “primary antioxidant having the ability to donate a hydrogen radical to a peroxy radical” is a compound having at least one hydrogen atom in the molecule that is rapidly extracted by the peroxy radical, and is a hydroxyl group or a primary or An aromatic compound substituted with a secondary amino group or a heterocyclic compound having a sterically hindered group is preferable, and a phenol compound or a hindered amine compound having an alkyl group at the ortho position is more preferable.

(Phenolic compounds)
The phenolic compounds preferably used in the present invention include 2,6-dialkylphenol derivative compounds such as those described in US Pat. No. 4,839,405, columns 12-14. Such a compound includes a compound represented by the following general formula (3).

_Wherein, R 31 _{to R 36} represents a hydrogen atom or a substituent. Examples of the substituent include a halogen atom (eg, fluorine atom, chlorine atom), an alkyl group (eg, methyl group, ethyl group, isopropyl group, hydroxyethyl group, methoxymethyl group, trifluoromethyl group, t-butyl group, etc.), A cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), an aralkyl group (eg, benzyl group, 2-phenethyl group, etc.), an aryl group (eg, phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group, etc.), alkoxy Groups (eg methoxy, ethoxy, isopropoxy, butoxy), aryloxy (eg phenoxy), cyano, acylamino (eg acetylamino, propionylamino), alkylthio (eg methylthio) Group, ethylthio group, butylthio group, etc.), aryl O group (for example, phenylthio group), sulfonylamino group (for example, methanesulfonylamino group, benzenesulfonylamino group, etc.), ureido group (for example, 3-methylureido group, 3,3-dimethylureido group, 1,3-dimethylureido) Group), sulfamoylamino group (dimethylsulfamoylamino group etc.), carbamoyl group (eg methylcarbamoyl group, ethylcarbamoyl group, dimethylcarbamoyl group etc.), sulfamoyl group (eg ethylsulfamoyl group, dimethylsulfamoyl group) Moyl group etc.), alkoxycarbonyl group (eg methoxycarbonyl group, ethoxycarbonyl group etc.), aryloxycarbonyl group (eg phenoxycarbonyl group etc.), sulfonyl group (eg methanesulfonyl group, butanesulfonyl group, phenylsulfonyl group) Group), acyl group (eg, acetyl group, propanoyl group, butyroyl group, etc.), amino group (methylamino group, ethylamino group, dimethylamino group, etc.), cyano group, hydroxy group, nitro group, nitroso group, amine oxide Group (for example, pyridine-oxide group), imide group (for example, phthalimide group, etc.), disulfide group (for example, benzene disulfide group, benzothiazolyl-2-disulfide group, etc.), carboxyl group, sulfo group, heterocyclic group (for example, pyrrole group, Pyrrolidyl group, pyrazolyl group, imidazolyl group, pyridyl group, benzimidazolyl group, benzthiazolyl group, benzoxazolyl group, etc.). These substituents may be further substituted.

_{Further, R 31} is a hydrogen _{atom, R 32,} R ₃₆ the compound is t- butyl group. Specific examples of the phenol compound include n-octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate, n-octadecyl 3- (3,5-di-t-butyl-4 -Hydroxyphenyl) -acetate, n-octadecyl 3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl 3,5-di-t-butyl-4-hydroxyphenylbenzoate, n-dodecyl 3,5 -Di-t-butyl-4-hydroxyphenylbenzoate, neo-dodecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, dodecyl beta (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, ethyl α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl α- (4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2- (n- Octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (n-octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-phenylacetate, 2- (n-octadecyl) Thio) ethyl 3,5-di-t-butyl-4-hydroxyphenyl acetate, 2- (n-octadecylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (2-hydroxy Ethylthio) ethyl 3,5-di-t-butyl-4-hydroxybenzoate, diethyl glycol bis- (3,5-di-t-butyl-4- Droxy-phenyl) propionate, 2- (n-octadecylthio) ethyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide-N, N-bis- [ethylene 3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], n-butylimino-N, N-bis- [ethylene 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2 -(2-stearoyloxyethylthio) ethyl 3,5-di-tert-butyl-4-hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl 7- (3-methyl-5-tert-butyl-4 -Hydroxyphenyl) heptanoate, 1,2-propylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyl Nyl) propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], neopentyl glycol bis- [3- (3,5-di-t-butyl-) 4-hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), glycerin-1-n-octadecanoate-2,3-bis- (3 5-di-t-butyl-4-hydroxyphenyl acetate), pentaerythritol tetrakis- [3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate], 3,9-bis- {2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethyl ester L} -2,4,8,10-tetraoxaspiro [5.5] undecane, 1,1,1-trimethylolethane-tris- [3- (3,5-di-t-butyl-4-hydroxy Phenyl) propionate], sorbitol hexa- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl 7- (3-methyl-5-tert-butyl-4-hydroxy Phenyl) propionate, 2-stearoyloxyethyl 7- (3-methyl-5-tert-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediol-bis [(3 ', 5'-di-t -Butyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis (3,5-di-t-butyl-4-hydroxyhydrocinnamate ) Is included. The phenol compound of the above type is commercially available from Ciba Japan Co., Ltd. under the trade names “Irganox 1076” and “Irganox 1010”, for example.

  The above phenol compounds can be used alone or in combination of two or more thereof, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention, but with respect to the total mass of the resin forming the optical film, Usually, it is preferable to add 0.001-10.0 mass part, More preferably, it is 0.05-5.0 mass part, Most preferably, it is 0.1-2.0 mass part.

(Hindered amine compounds)
The hindered amine compound preferably used in the present invention is preferably a hindered amine compound represented by the following general formula (4).

_Wherein, R 41 _{to R 47} represents a substituent. The substituent is synonymous with the substituents represented by _R 31 _{to R 36} in the general formula (3). R ₄₄ is preferably a hydrogen atom and a methyl group, R ₄₇ is a hydrogen atom, and R ₄₂ , R ₄₃ , R ₄₅ and R ₄₆ are preferably a methyl group. Specific examples of hindered amine compounds include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis (1 , 2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (N-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-benzyloxy-2,2) , 6,6-tetramethyl-4-piperidyl) sebacate, bis (N-cyclohexyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6- Pentamethyl-4-piperidyl) 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1-acryloyl-2,2,6,6- Tramethyl-4-piperidyl) 2,2-bis (3,5-di-tert-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1,2,2,6,6-pentamethyl-4- Piperidyl) decanedioate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -1- [ 2- (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy) ethyl] -2,2,6,6-tetramethylpiperidine, 2-methyl-2- (2,2, 6,6-tetramethyl-4-piperidyl) amino-N- (2,2,6,6-tetramethyl-4-piperidyl) propionamide, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylate, and the like.

  Further, it may be a polymer type compound. As specific examples, N, N ′, N ″, N ″ ′-tetrakis- [4,6-bis- [butyl- (N-methyl-2,2,6, 6-tetramethylpiperidin-4-yl) amino] -triazin-2-yl] -4,7-diazadecane-1,10-diamine, dibutylamine and 1,3,5-triazine-N, N′-bis ( 2,2,6,6-tetramethyl-4-piperidyl) -1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine polycondensate, di Polycondensate of butylamine, 1,3,5-triazine and N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{(1,1,3,3 -Tetramethylbutyl) amino-1,3,5-tri Gin-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], Between 1,6-hexanediamine-N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) and morpholine-2,4,6-trichloro-1,3,5-triazine Polycondensate, poly [(6-morpholino-s-triazine-2,4-diyl) [(2,2,6,6-tetramethyl-4-piperidyl) imino] -hexamethylene [(2,2,6 , 6-tetramethyl-4-piperidyl) imino]], etc., high molecular weight HALS in which a plurality of piperidine rings are bonded via a triazine skeleton; dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl- 1-piperidine ester Polymer with diol, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis (2-hydroxy-1,1-dimethyl) (Ethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane and the like, and the like are exemplified by compounds in which a piperidine ring is bonded through an ester bond, but the present invention is not limited thereto. It is not a thing.

  Among these, polycondensates of dibutylamine, 1,3,5-triazine and N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{(1, 1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2 , 2,6,6-tetramethyl-4-piperidyl) imino}], a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, etc. Those having a molecular weight (Mn) of 2,000 to 5,000 are preferred.

  The hindered amine compound of the above type is commercially available from Ciba Japan Co., Ltd. under the trade names “Tinuvin 144” and “Tinuvin 770” and from ADEKA Co., Ltd. under the name “ADK STAB LA-52”.

  The above hindered amine compounds can be used alone or in combination of two or more thereof, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention, but with respect to the total mass of the resin forming the optical film, Usually, it is preferable to add 0.001-10.0 mass part, More preferably, it is 0.05-5.0 mass part, Most preferably, it is 0.1-2.0 mass part.

(Antioxidant secondary agent)
The optical film of the present invention preferably contains at least one secondary antioxidant having a reducing action on peroxide.

  In the present invention, the “secondary antioxidant having a reducing action on peroxide” means a reducing agent that rapidly reduces peroxide to convert it to a hydroxyl group.

  The secondary antioxidant having a reducing ability for peroxide is preferably a phosphorus compound or a sulfur compound.

(Phosphorus compounds)
The phosphorus compound preferably used in the present invention is preferably a phosphorus compound selected from the group consisting of phosphite, phosphonite, phosphinite, or tertiary phosphane. Is preferably a compound having a partial structure represented by the following general formulas (5-1), (5-2), (5-3), (5-4), and (C-5) in the molecule.

Wherein, Ph ₁ and Ph ₁ 'represents a substituent. The substituent is synonymous with the substituents represented by _R 31 _{to R 36} in the general formula (3). More preferably, Ph ₁ and Ph ₁ ′ represent a phenylene group, and the hydrogen atom of the phenylene group is a phenyl group, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or 6 to 12 carbon atoms. Or an alkyl cycloalkyl group or an aralkyl group having 7 to 12 carbon atoms. Ph ₁ and Ph ₁ ′ may be the same as or different from each other. X represents a single bond, a sulfur atom or a —CHR— group. R represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms. Moreover, these may be substituted with a substituent having the same meaning as the substituent represented by R _{31 to} R ₃₆ in the general formula (3).

Wherein, Ph ₂ and Ph ₂ 'each represent a substituent. The substituent is synonymous with the substituents represented by _R 31 _{to R 36} in the general formula (3). More preferably, Ph ₂ and Ph ₂ ′ represent a phenyl group or a biphenyl group, and the hydrogen atom of the phenyl group or biphenyl group is an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or a carbon number. It may be substituted with a 6-12 alkylcycloalkyl group or an aralkyl group having 7-12 carbon atoms. Ph ₂ and Ph ₂ ′ may be the same as or different from each other. Moreover, these may be substituted with a substituent having the same meaning as the substituent represented by R _{31 to} R ₃₆ in the general formula (3).

In the formula, Ph ₃ represents a substituent. The substituent is synonymous with the substituents represented by _R 31 _{to R 36} in the general formula (3). More preferably, Ph ₃ represents a phenyl group or a biphenyl group, and the hydrogen atom of the phenyl group or biphenyl group is an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or a 6 to 12 carbon atom. It may be substituted with an alkylcycloalkyl group or an aralkyl group having 7 to 12 carbon atoms. Moreover, these may be substituted with a substituent having the same meaning as the substituent represented by R _{31 to} R ₃₆ in the general formula (3).

In the formula, Ph ₄ represents a substituent. The substituent is synonymous with the substituents represented by _R 31 _{to R 36} in the general formula (3). More preferably, Ph ₄ represents an alkyl group having 1 to 20 carbon atoms or a phenyl group, and the alkyl group or phenyl group is a substituent having the same meaning as the substituent represented by R _{31 to} R ₃₆ in the general formula (3). It may be substituted by a group.

In the formula, Ph ₅ , Ph ₅ ′ and Ph ₅ ″ represent substituents. The substituents have the same meaning as the substituents represented by R _{31 to} R ₃₆ in the general formula (3). More preferably, Ph ₅ , Ph ₅ ′ and Ph ₅ ″ represent an alkyl group having 1 to 20 carbon atoms or a phenyl group, and the alkyl group or phenyl group is a substituent represented by R _{31 to} R ₃₆ in the general formula (3). It may be substituted with a substituent having the same meaning as

  Specific examples of phosphorus compounds include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-). t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 6- [ 3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butyldibenz [d, f] [1,3,2] dioxaphosphine Monophosphite compounds such as pin and tridecyl phosphite; 4,4'-butylidene-bis (3-methyl-6-t-butyl) Diphosphite compounds such as phenyl-di-tridecyl phosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12-C15) phosphite); triphenylphosphonite, tetrakis (2,4- Di-tert-butylphenyl) [1,1-biphenyl] -4,4'-diylbisphosphonite, tetrakis (2,4-di-tert-butyl-5-methylphenyl) [1,1-biphenyl]- Phosphonite compounds such as 4,4'-diylbisphosphonite; phosphinite compounds such as triphenylphosphinite and 2,6-dimethylphenyldiphenylphosphinite; triphenylphosphine and tris (2,6-dimethoxyphenyl) Phosphine compounds such as phosphine; and the like.

  Phosphorus compounds of the above type are, for example, from Sumitomo Chemical Co., Ltd., “Sumilizer GP”, ADEKA Co., Ltd. “IRGAFOS P-EPQ”, commercially available from Sakai Chemical Industry Co., Ltd. under the trade name “GSY-P101”.

  The above phosphorus compounds can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention, but with respect to the total mass of the resin forming the optical film. Usually, it is preferable to add 0.001-10.0 mass parts, More preferably, it is 0.05-5.0 mass parts, Most preferably, it is 0.05-2.0 mass parts.

(Sulfur compounds)
The sulfur compound preferably used in the present invention is preferably a sulfur compound represented by the following general formula (6).

Formula (6) R ₆₁ —S—R ₆₂
In the formula, R ₆₁ and R ₆₂ represent a substituent. The substituent is synonymous with the substituents represented by _R 31 _{to R 36} in the general formula (3).

  Specific examples of the sulfur compound include dilauryl-3,3-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3-thiodipropionate, laurylstearyl-3,3. -Thiodipropionate, pentaerythritol-tetrakis (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane Etc.

  The above-mentioned type of sulfur-based compound is commercially available from Sumitomo Chemical Co., Ltd. under the trade names “Sumilizer TPL-R” and “Sumilizer TP-D”, for example.

  The above sulfur-based compounds can be used alone or in combination of two or more thereof, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention, but with respect to the total mass of the resin forming the optical film. Usually, it is preferable to add 0.001-10.0 mass parts, More preferably, it is 0.05-5.0 mass parts, Most preferably, it is 0.05-2.0 mass parts.

<Other additives>
In the optical film of the present invention, additives such as an acid scavenger, an ultraviolet absorber, a plasticizer, a mat agent, an optical anisotropy control agent and an antistatic agent may be used in combination as other additives.

(Acid scavenger)
Since decomposition is accelerated by an acid in a high temperature environment where melt film formation is performed, the optical film of the present invention preferably contains an acid scavenger as a stabilizer. Any acid scavenger useful in the present invention can be used without limitation as long as it is a compound that reacts with an acid to inactivate the acid, and is described in U.S. Pat. No. 4,137,201. A compound having an epoxy group is preferred. Epoxy compounds as such acid scavengers are known in the art and are derived by condensation of various polyglycol diglycidyl ethers, particularly about 8 to 40 moles of ethylene oxide per mole of polyglycol. Glycol, diglycidyl ether of glycerol, etc., metal epoxy compounds (such as those conventionally used in and with vinyl chloride polymer compositions), epoxidized ether condensation products, diphenols of bisphenol A Glycidyl ether (ie, 4,4'-dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid ester (especially an ester of an alkyl of about 4 to 2 carbon atoms of a fatty acid of 2 to 22 carbon atoms (for example, Butyl epoxy stearate) And epoxidized vegetable oils and other unsaturated natural oils (sometimes epoxies) that may be represented and exemplified by compositions of various epoxidized long chain fatty acid triglycerides and the like (eg, epoxidized soybean oil, epoxidized linseed oil, etc.) Natural fatty glycerides or unsaturated fatty acids, which generally contain 12 to 22 carbon atoms). Further, as a commercially available epoxy group-containing epoxide resin compound, EPON 815C and other epoxidized ether oligomer condensation products of the following general formula (7) can also be preferably used.

  In formula, n is an integer of 0-12. Other acid scavengers that can be used include those described in paragraphs 87 to 105 of JP-A-5-194788.

  The acid scavenger can be used singly or in combination of two or more, and the amount of the acid scavenger is appropriately selected within a range not impairing the object of the present invention, but is usually based on the total mass of the resin forming the optical film. It is preferable to add 0.001-10.0 mass parts, More preferably, it is 0.05-5.0 mass parts, Most preferably, it is 0.05-2.0 mass parts.

  In addition, although an acid scavenger may be called an acid scavenger, an acid capture agent, an acid catcher etc. with respect to resin, in this invention, it can use without a difference by these names.

(UV absorber)
In the optical film of the present invention, from the viewpoint of preventing deterioration of the polarizer and the display device with respect to ultraviolet rays, the optical film is excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less, and from the viewpoint of liquid crystal display properties, visible light having a wavelength of 400 nm or more is used. It is preferable to contain an ultraviolet absorber that absorbs little. Examples of the ultraviolet absorber used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, triazine compounds, and the like. However, benzophenone compounds, less colored benzotriazole compounds, and triazine compounds are preferable. Further, ultraviolet absorbers described in JP-A Nos. 10-182621 and 8-337574, and polymer ultraviolet absorbers described in JP-A Nos. 6-148430 and 2003-113317 may be used.

  Specific examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzo Triazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5 Chlorobenzotriazole, 2- (2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy- '-Tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-(2-octyloxycarbonylethyl) -phenyl) -5 -Chlorobenzotriazole, 2- (2'-hydroxy-3 '-(1-methyl-1-phenylethyl) -5'-(1,1,3,3-tetramethylbutyl) -phenyl) benzotriazole, 2 -(2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H- Benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2) - can be exemplified mixtures of benzotriazol-2-yl) phenyl] propionate, and the like.

  As commercially available products, TINUVIN 171, TINUVIN 900, TINUVIN 928, TINUVIN 360 (all manufactured by Ciba Japan), LA31 (manufactured by ADEKA Corporation), RUVA- 100 (manufactured by Otsuka Chemical).

  Specific examples of benzophenone compounds include 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy- 5-benzoylphenylmethane) and the like, but are not limited thereto.

  The above ultraviolet absorbers can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention, but with respect to the total mass of the resin forming the optical film. Usually, it is preferable to add 0.1-5 mass parts, More preferably, it is 0.2-3 mass parts, Most preferably, it is 0.5-2 mass parts.

  The benzotriazole structure or triazine structure may be part of the polymer, or may be regularly pendant to the polymer, and part of the molecular structure of other additives such as plasticizers, antioxidants, and acid scavengers. May be introduced.

  Although it does not specifically limit as a conventionally well-known ultraviolet absorptive polymer, For example, the polymer which homopolymerized RUVA-93 (made by Otsuka Chemical), the polymer which copolymerized RUVA-93, and another monomer, etc. are mentioned. . Specific examples include PUVA-30M obtained by copolymerization of RUVA-93 and methyl methacrylate at a ratio (mass ratio) of 3: 7, and PUVA-50M obtained by copolymerization at a ratio of 5: 5 (mass ratio). It is done. Furthermore, the polymer etc. which are described in Unexamined-Japanese-Patent No. 2003-113317 are mentioned.

(Plasticizer)
In the optical film of the present invention, at least one plasticizer may be added to the film.

  A plasticizer is generally an additive that has the effect of improving brittleness or imparting flexibility by being added to a polymer. In this case, a plasticizer is added in order to lower the melting temperature than the melting temperature alone, and to lower the melt viscosity of the film constituent material containing the plasticizer than the resin alone at the same heating temperature. Moreover, since it adds also in order to improve the hydrophilic property of a cellulose ester and to improve the water vapor transmission rate of an optical film, it has a function as a moisture permeation preventive agent.

  Here, the melting temperature of the film constituent material means a temperature at which the material is heated and fluidity is developed. In order to melt and flow the resin according to the present invention, it is necessary to heat at least a temperature higher than the glass transition temperature. Above the glass transition temperature, the elastic modulus or viscosity decreases due to heat absorption, and fluidity is exhibited. However, in the resin according to the present invention, the molecular weight of the cellulose ester is reduced due to thermal decomposition at the same time as melting at a high temperature, which may adversely affect the mechanical properties of the resulting film. Therefore, the resin is melted at a temperature as low as possible. There is a need. In order to lower the melting temperature of the film constituting material, it can be achieved by adding a plasticizer having a melting point or glass transition temperature lower than the glass transition temperature of the resin according to the present invention.

  The above plasticizers can be used alone or in combination of two or more, and the amount of the plasticizer is appropriately selected within the range not impairing the object of the present invention. 0.1 to 20% by mass is preferably added, and more preferably 0.2 to 10 parts by mass.

  In the present invention, an ester plasticizer comprising a polyhydric alcohol and a monovalent carboxylic acid, and an ester plasticizer comprising a polyvalent carboxylic acid and a monohydric alcohol are preferred.

  Examples of polyhydric alcohols that are raw materials for ester plasticizers include the following, but the present invention is not limited to these. Adonitol, arabitol, ethylene glycol, glycerin, diglycerin, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, ditrimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, xyl Mention may be made of the toll and the like. In particular, ethylene glycol, glycerin, and trimethylolpropane are preferable.

  Specific examples of ethylene glycol ester plasticizers that are one of the polyhydric alcohol esters include ethylene glycol alkyl ester plasticizers such as ethylene glycol diacetate and ethylene glycol dibutyrate, and ethylene glycol dicyclopropyl. Examples thereof include ethylene glycol cycloalkyl ester plasticizers such as carboxylate and ethylene glycol dicyclohexylcarboxylate, and ethylene glycol aryl ester plasticizers such as ethylene glycol dibenzoate and ethylene glycol di4-methylbenzoate. These alkylate groups, cycloalkylate groups, and arylate groups may be the same or different, and may be further substituted. Further, it may be a mix of alkylate group, cycloalkylate group and arylate group, and these substituents may be covalently bonded. Further, the ethylene glycol part may be substituted, and the ethylene glycol ester partial structure may be part of the polymer or regularly pendant, and may be an antioxidant, an acid scavenger, an ultraviolet absorber, etc. It may be introduced into a part of the molecular structure of the additive.

  Specific examples of the glycerin ester plasticizer that is one of the polyhydric alcohol esters include glycerol alkyl esters such as triacetin, tributyrin, glycerol diacetate caprylate, glycerol oleate propionate, and glycerol tricyclopropylcarboxylate. Glycerol glycerol esters such as glycerol tricyclohexyl carboxylate, glycerol aryl esters such as glycerol tribenzoate and glycerol 4-methylbenzoate, diglycerol tetraacetylate, diglycerol tetrapropionate, diglycerol acetate tricaprylate, diglycerol Tetralaurate, diglycerin alkyl ester, diglycerin tetracyclobutylcarboxylate, diglycerin tet Diglycerol cycloalkyl esters such as cyclopentyl carboxylate, diglycerin tetrabenzoate, diglycerin aryl ester such as diglycerin 3-methylbenzoate or the like. These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different, and may be further substituted. Further, it may be a mixture of alkylate group, cycloalkylcarboxylate group, and arylate group, and these substituents may be bonded by a covalent bond. Furthermore, the glycerin and diglycerin part may be substituted, the partial structure of the glycerin ester and the diglycerin ester may be part of the polymer or regularly pendant, and the antioxidant, acid scavenger, You may introduce | transduce into a part of molecular structure of additives, such as a ultraviolet absorber.

  As other polyhydric alcohol ester plasticizers, specifically, polyhydric alcohol ester plasticizers described in paragraphs 30 to 33 of JP-A-2003-12823, paragraphs 64- of JP-A-2006-188663. 74 polyhydric alcohol ester plasticizer.

  These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different, and may be further substituted. Further, it may be a mixture of alkylate group, cycloalkylcarboxylate group, and arylate group, and these substituents may be bonded by a covalent bond. Furthermore, the polyhydric alcohol part may be substituted, and the partial structure of the polyhydric alcohol may be part of the polymer or regularly pendant, and may be an antioxidant, an acid scavenger, an ultraviolet absorber. May be introduced into a part of the molecular structure of the additive.

  Among the ester plasticizers composed of the polyhydric alcohol and the monovalent carboxylic acid, alkyl polyhydric alcohol aryl esters are preferable. Specifically, the ethylene glycol dibenzoate, glycerin tribenzoate, diglycerin tetrabenzoate, penta Examples include erythritol tetrabenzoate, exemplified compound 16 described in paragraph 31 of JP-A No. 2003-12823, and exemplified compound 48 described in paragraph 71 of JP-A No. 2006-188663.

  Specific examples of the dicarboxylic acid ester plasticizer that is one of the polyvalent carboxylic acid esters include alkyl dicarboxylic acid alkyl ester plasticizers such as didodecyl malonate, dioctyl adipate, and dibutyl sebacate. Alkyl dicarboxylic acid cycloalkyl ester type plasticizers such as cyclopentyl succinate and dicyclohexyl adipate, alkyl dicarboxylic acid aryl ester type plasticizers such as diphenyl succinate and di4-methylphenyl glutarate, dihexyl-1,4-cyclohexane Cycloalkyl dicarboxylic acid alkyl ester plasticizers such as dicarboxylate and didecylbicyclo [2.2.1] heptane-2,3-dicarboxylate, dicyclohexyl-1,2-cyclobutanedicarboxylate, dicis Cycloalkyldicarboxylic acid cycloalkyl ester plasticizers such as ropropyl-1,2-cyclohexyldicarboxylate, diphenyl-1,1-cyclopropyldicarboxylate, di2-naphthyl-1,4-cyclohexanedicarboxylate, etc. Cycloalkyldicarboxylic acid aryl ester plasticizer, diethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate and other aryl dicarboxylic acid alkyl ester plasticizers, dicyclopropyl phthalate, dicyclohexyl phthalate, etc. Aryl dicarboxylic acid cycloalkyl ester plasticizers, and aryl dicarboxylic acid aryl ester plasticizers such as diphenyl phthalate and di-4-methylphenyl phthalate And the like. These alkoxy groups and cycloalkoxy groups may be the same or different, may be mono-substituted, and these substituents may be further substituted. The alkyl group and cycloalkyl group may be mixed, and these substituents may be bonded together by a covalent bond. Furthermore, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used.

  Also, the partial structure of phthalate ester may be part of the polymer or regularly pendant to the polymer, and it may be part of the molecular structure of additives such as antioxidants, acid scavengers, and UV absorbers. It may be introduced.

  Examples of other polycarboxylic acid ester plasticizers include alkyl polycarboxylic acid alkyl esters such as tridodecyl tricarbarate and tributyl-meso-butane-1,2,3,4-tetracarboxylate. Plasticizers, alkylpolycarboxylic acid cycloalkyl ester plasticizers such as tricyclohexyltricarbarate, tricyclopropyl-2-hydroxy-1,2,3-propanetricarboxylate, triphenyl 2-hydroxy- Alkyl polyvalent carboxylic acid aryl ester plasticizers such as 1,2,3-propanetricarboxylate, tetra-3-methylphenyltetrahydrofuran-2,3,4,5-tetracarboxylate, tetrahexyl-1,2, 3,4-cyclobutanetetracarboxylate, tetrabu Cycloalkyl polycarboxylic acid alkyl ester plasticizers such as ru-1,2,3,4-cyclopentanetetracarboxylate, tetracyclopropyl-1,2,3,4-cyclobutanetetracarboxylate, tricyclohexyl- Cycloalkyl polycarboxylic acid cycloalkyl ester plasticizers such as 1,3,5-cyclohexyl tricarboxylate, triphenyl-1,3,5-cyclohexyl tricarboxylate, hexa-4-methylphenyl-1,2, Cycloalkyl polycarboxylic acid aryl ester plasticizers such as 3,4,5,6-cyclohexylhexacarboxylate, tridodecylbenzene-1,2,4-tricarboxylate, tetraoctylbenzene-1,2,4 , 5-tetracarboxylate and other aryl polyvalent Rubinoic acid alkyl ester plasticizers, tricyclopentylbenzene-1,3,5-tricarboxylate, tetracyclohexylbenzene-1,2,3,5-tetracarboxylate and other aryl polyvalent carboxylic acid cycloalkyl esters Plasticizers of aryl polyvalent carboxylic acid aryl esters such as plasticizers triphenylbenzene-1,3,5-tetracarboxylate, hexa-4-methylphenylbenzene-1,2,3,4,5,6-hexacarboxylate Agents. These alkoxy groups and cycloalkoxy groups may be the same or different, and may be mono-substituted, and these substituents may be further substituted. The alkyl group and cycloalkyl group may be mixed, and these substituents may be bonded together by a covalent bond. Furthermore, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used. Also, the partial structure of phthalate ester may be part of the polymer or regularly pendant into the polymer, and introduced into part of the molecular structure of additives such as antioxidants, acid scavengers, UV absorbers, etc. May be.

  Among the ester plasticizers composed of the polyvalent carboxylic acid and the monohydric alcohol, alkyl dicarboxylic acid alkyl esters are preferable, and specific examples include the dioctyl adipate.

  Examples of other plasticizers used in the present invention include phosphate ester plasticizers, carbohydrate ester plasticizers, and polymer plasticizers.

  Specific examples of the phosphoric acid ester plasticizer include phosphoric acid alkyl esters such as triacetyl phosphate and tributyl phosphate, phosphoric acid cycloalkyl esters such as tricyclobenthyl phosphate and cyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, Examples thereof include phosphoric acid aryl esters such as cresyl phenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, trinaphthyl phosphate, trixylyl phosphate, tris ortho-biphenyl phosphate. These substituents may be the same or different, and may be further substituted. Moreover, the mix of an alkyl group, a cycloalkyl group, and an aryl group may be sufficient, and substituents may couple | bond together by the covalent bond.

  Also, alkylene bis (dialkyl phosphate) such as ethylene bis (dimethyl phosphate), butylene bis (diethyl phosphate), alkylene bis (diaryl phosphate) such as ethylene bis (diphenyl phosphate), propylene bis (dinaphthyl phosphate), phenylene bis (dibutyl) And phosphate esters such as arylene bis (diaryl phosphate) such as arylene bis (dialkyl phosphate), phenylene bis (diphenyl phosphate), naphthylene bis (ditoluyl phosphate) such as biphenylene bis (dioctyl phosphate). These substituents may be the same or different, and may be further substituted. Moreover, the mix of an alkyl group, a cycloalkyl group, and an aryl group may be sufficient, and substituents may couple | bond together by the covalent bond.

  Furthermore, the partial structure of the phosphate ester may be part of the polymer or may be regularly pendant, and may be introduced into part of the molecular structure of additives such as antioxidants, acid scavengers, and UV absorbers. It may be. Among the above-mentioned compounds, phosphoric acid aryl ester and arylene bis (diaryl phosphate) are preferable, and specifically, triphenyl phosphate and phenylene bis (diphenyl phosphate) are preferable.

  Next, the carbohydrate ester plasticizer will be described. The carbohydrate means a monosaccharide, disaccharide or trisaccharide in which the saccharide is present in the form of pyranose or furanose (6-membered ring or 5-membered ring). Non-limiting examples of carbohydrates include glucose, saccharose, lactose, cellobiose, mannose, xylose, ribose, galactose, arabinose, fructose, sorbose, cellotriose and raffinose. The carbohydrate ester refers to an ester compound formed by dehydration condensation of a carbohydrate hydroxyl group and a carboxylic acid, and specifically means an aliphatic carboxylic acid ester or an aromatic carboxylic acid ester of a carbohydrate. Examples of the aliphatic carboxylic acid include acetic acid and propionic acid, and examples of the aromatic carboxylic acid include benzoic acid, toluic acid, and anisic acid. Carbohydrates have a number of hydroxyl groups depending on the type, but even if a part of the hydroxyl group reacts with the carboxylic acid to form an ester compound, the whole hydroxyl group reacts with the carboxylic acid to form an ester compound. Also good. In the present invention, it is preferable that all of the hydroxyl groups react with the carboxylic acid to form an ester compound.

  Specific examples of the carbohydrate ester plasticizer include glucose pentaacetate, glucose pentapropionate, glucose pentabylate, saccharose octaacetate, saccharose octabenzoate and the like. Among these, saccharose octaacetate, saccharose Octabenzoate is more preferred, and sucrose octabenzoate is particularly preferred.

  Examples of these compounds are listed below, but the present invention is not limited thereto.

Monopet SB: manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Monopet SOA: manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Specific examples of the polymer plasticizer include aliphatic hydrocarbon polymers, alicyclic hydrocarbon polymers, and ethyl polyacrylate. , Acrylic polymers such as polymethyl methacrylate, copolymers of methyl methacrylate and 2-hydroxyethyl methacrylate (eg, any ratio between 1:99 and 99: 1), polyvinyl isobutyl Ethers, vinyl polymers such as poly N-vinyl pyrrolidone, styrene polymers such as polystyrene and poly 4-hydroxystyrene, polybutylene succinates, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyethers such as polyethylene oxide and polypropylene oxide , Polyamide, polyureta , And a polyurea or the like. The number average molecular weight is preferably about 1,000 to 500,000, particularly preferably 5,000 to 200,000. If it is 1000 or less, a problem arises in volatility, and if it exceeds 500000, the plasticizing ability is lowered, and the mechanical properties of the optical film are adversely affected. These polymer plasticizers may be a homopolymer composed of one type of repeating unit or a copolymer having a plurality of repeating structures. Two or more of the above polymers may be used in combination.

(Matting agent)
In the optical film according to the present invention, a matting agent can be added in order to impart slipperiness, optical and mechanical functions. Examples of the matting agent include inorganic compound fine particles and organic compound fine particles.

  The shape of the matting agent is preferably a spherical shape, a rod shape, a needle shape, a layer shape, a flat shape or the like. Examples of the matting agent include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. Examples thereof include inorganic fine particles such as oxides, phosphates, silicates, and carbonates, and crosslinked polymer fine particles. Among these, silicon dioxide is preferable because it can reduce the haze of the film. These fine particles are preferably surface-treated with an organic substance because the haze of the film can be reduced.

  The surface treatment is preferably performed with halosilanes, alkoxysilanes, silazane, siloxane, or the like. The larger the average particle size of the fine particles, the greater the sliding effect, and the smaller the average particle size, the better the transparency. The average primary particle size of the fine particles is in the range of 0.01 to 1.0 μm. The average particle size of the primary particles of preferable fine particles is preferably 5 to 50 nm, more preferably 7 to 14 nm. These fine particles are preferably used for generating irregularities of 0.01 to 1.0 μm on the optical film surface.

  As the fine particles of silicon dioxide, Aerosil 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, TT600, NAX50, etc. manufactured by Nippon Aerosil Co., Ltd. P10, KE-P30, KE-P100, KE-P150 and the like can be mentioned, and Aerosil 200V, R972V, NAX50, KE-P30 and KE-P100 are preferable. Two or more kinds of these fine particles may be used in combination.

  When using 2 or more types together, it can mix and use in arbitrary ratios. Fine particles having different average particle sizes and materials, for example, Aerosil 200V and R972V can be used in a mass ratio of 0.1: 99.9 to 99.9: 0.1.

  These matting agents are preferably added by kneading. Further, as another form, after mixing and dispersing a matting agent dispersed in a solvent in advance with a resin and / or a plasticizer and / or an antioxidant and / or an ultraviolet absorber, a solid material obtained by volatilizing or precipitating the solvent is obtained. It is preferable to use this in the process of producing the resin melt from the viewpoint that the matting agent can be uniformly dispersed in the resin.

  The matting agent can also be added to improve the mechanical, electrical and optical properties of the film.

  The slipperiness of the resulting film improves as the fine particles are added, but the haze increases as the fine particles are added, so the blending amount is appropriately selected within the range not impairing the object of the present invention. It is preferable to add 0.001-5 mass parts with respect to the total mass of resin which forms a film, More preferably, it is 0.005-1 mass part, More preferably, it is 0.01-0.5 mass part. is there.

(Optical anisotropy control agent)
A retardation increasing agent for controlling optical anisotropy is optionally added. Since these adjust the retardation of an optical film, it is preferable to use an aromatic compound having at least two aromatic rings as a retardation increasing agent. The aromatic compound is used in the range of 0.01 to 20 parts by mass with respect to the total mass of the resin forming the optical film. And it is preferable to use in 0.05-15 mass parts, and it is still more preferable to use in 0.1-10 mass parts. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic hetero ring in addition to the aromatic hydrocarbon ring. The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring. Details of these are described in JP-A No. 2004-109410, JP-A No. 2003-344655, JP-A No. 2000-275434, JP-A No. 2000-1111914, JP-A No. 12-275434, and the like.

<Method for producing optical film>
Although the example of the manufacturing method of the optical film of this invention is demonstrated, this invention is not limited to this.

  As a method for forming the optical film of the present invention, a production method such as an inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, or a hot press method can be used. From the viewpoint of suppression, suppression of optical defects such as die lines, etc., solution casting by casting method has been preferred, but solution casting method requires a large amount of organic solvent and has a large environmental load. It was. In addition, since the solvent remaining inside the film must be removed, the capital investment and production cost for the production line such as the drying line, the drying energy, and the recovery and regeneration device for the evaporated solvent are enormous. Reducing energy is also an important issue. From the above viewpoint, the optical film of the present invention is preferably produced by melt casting.

(Melt casting method)
The optical film of the present invention is preferably produced by melt casting as described above. The molding method by melt casting, which is heated and melted without using the solvent used in the solution casting method (for example, methylene chloride, etc.), more specifically, melt extrusion molding method, press molding method, inflation method, injection molding method And can be classified into blow molding, stretch molding and the like. Among these, in order to obtain a polarizing plate protective film having excellent mechanical strength and surface accuracy, the melt extrusion method is excellent.

  Hereinafter, the manufacturing method of the optical film of the present invention will be described by taking the melt extrusion method as an example.

  FIG. 1 is a schematic flow sheet showing the overall configuration of an apparatus for carrying out the method for producing an optical film according to the present invention, and FIG. 2 is an enlarged view of a cooling roll portion from a casting die.

  1 and 2, the method for producing an optical film according to the present invention comprises mixing film materials and then extruding from a casting die 4 onto a first cooling roll 5 by using an extruder 1 to produce a first cooling roll. 5, and is further circumscribed in order by a total of three cooling rolls of the second cooling roll 7 and the third cooling roll 8, and is cooled and solidified to form a film 10. Next, the film 10 peeled off by the peeling roll 9 is then stretched in the width direction by holding both ends of the film by the stretching device 12 and then wound by the winding device 16. In addition, a touch roll 6 is provided that clamps the molten film on the surface of the first cooling roll 5 in order to correct the flatness. The touch roll 6 has an elastic surface and forms a nip with the first cooling roll 5. Details of the touch roll 6 will be described later.

  In the method for producing an optical film according to the present invention, the conditions for melt extrusion can be carried out in the same manner as the conditions used for other thermoplastic resins such as polyester. The material is preferably dried beforehand. It is desirable to dry the moisture to 1000 ppm or less, preferably 200 ppm or less by using a vacuum or reduced pressure drier or a dehumidifying hot air drier.

  For example, resin dried under hot air, vacuum or reduced pressure is melted at an extrusion temperature of about 200 to 300 ° C. using the extruder 1, filtered through a leaf disk type filter 2, and the like to remove foreign matters.

  When introducing into the extruder 1 from a supply hopper (not shown), it is preferable to prevent oxidative decomposition or the like under vacuum, reduced pressure, or inert gas atmosphere.

  When additives such as a plasticizer are not mixed in advance, they may be kneaded in the middle of the extruder. In order to add uniformly, it is preferable to use a mixing apparatus such as a static mixer 3.

  In the present invention, the resin and other additives that are added as necessary are preferably mixed before melting, and more preferably the resin and the additive are mixed before heating. Mixing may be performed by a mixer or the like, or may be performed in the resin preparation process as described above. When a mixer is used, a general mixer such as a V-type mixer, a conical screw type mixer, a horizontal cylindrical type mixer, a Henschel mixer, or a ribbon mixer can be used.

  After the film constituent materials are mixed as described above, the mixture may be directly melted using the extruder 1 to form a film. Once the film constituent materials are pelletized, the pellets are extruded. The film may be melted by the machine 1 to form a film. When the film constituent material includes a plurality of materials having different melting points, a so-called braided semi-melt is once produced at a temperature at which only the material having a low melting point is melted, and the semi-melt is supplied to the extruder 1. It is also possible to form a film by introducing it. If the film component contains a material that is easily pyrolyzed, in order to reduce the number of times of melting, a method of directly forming a film without producing pellets, or after making a paste-like semi-molten material as described above A method of forming a film is preferred.

  As the extruder 1, various commercially available extruders can be used, but a melt-kneading extruder is preferable, and a single-screw extruder or a twin-screw extruder may be used. When forming a film directly without producing pellets from film constituent materials, it is preferable to use a twin-screw extruder because an appropriate degree of kneading is necessary, but even with a single-screw extruder, the screw shape is a Maddock type. By changing to a kneading type screw such as a unimelt type or a dull mage, moderate kneading can be obtained, so that it can be used. When a pellet or braided semi-melt is once used as a film constituent material, it can be used in either a single screw extruder or a twin screw extruder.

  In the extruder 1 and the cooling step after extrusion, it is preferable to reduce the oxygen concentration by replacing with an inert gas such as nitrogen gas or by reducing the pressure.

  The preferable conditions for the melting temperature of the film constituent material in the extruder 1 vary depending on the viscosity and discharge amount of the film constituent material, the thickness of the sheet to be manufactured, etc., but generally the glass transition temperature Tg of the film Tg to Tg + 100 ° C., preferably Tg + 10 ° C. to Tg + 90 ° C. The melt viscosity at the time of extrusion is 1 to 10000 Pa · s, preferably 10 to 1000 Pa · s. Further, the residence time of the film constituting material in the extruder 1 is preferably short, and is within 5 minutes, preferably within 3 minutes, more preferably within 2 minutes.

  The residence time depends on the type of the extruder 1 and the extrusion conditions, but can be shortened by adjusting the material supply amount, L / D, screw rotation speed, screw groove depth, and the like. is there.

  The shape, rotation speed, and the like of the screw of the extruder 1 are appropriately selected depending on the viscosity, the discharge amount, and the like of the film constituent material. In the present invention, the shear rate in the extruder 1 is 1 / second to 10000 / second, preferably 5 / second to 1000 / second, more preferably 10 / second to 100 / second.

  The extruder 1 that can be used in the present invention is generally available as a plastic molding machine.

  The film constituent material extruded from the extruder 1 is sent to the casting die 4 and extruded from the slit of the casting die 4 into a film shape. The casting die 4 is not particularly limited as long as it is used for producing a sheet or a film. The material of the casting die 4 is sprayed or plated with hard chromium, chromium carbide, chromium nitride, titanium carbide, titanium carbonitride, titanium nitride, super steel, ceramic (tungsten carbide, aluminum oxide, chromium oxide), etc. Processing such as buffing, lapping using a # 1000 or higher grinding wheel, plane cutting using a # 1000 or higher diamond grinding wheel (the cutting direction is perpendicular to the resin flow direction), electrolytic polishing, electrolytic composite polishing, etc. And the like. A preferred material for the lip portion of the casting die 4 is the same as that of the casting die 4. The surface accuracy of the lip is preferably 0.5S or less, and more preferably 0.2S or less.

  The slit of the casting die 4 is configured so that the gap can be adjusted. This is shown in FIG. Of the pair of lips forming the slit 32 of the casting die 4, one is a flexible lip 33 having low rigidity and easily deformed, and the other is a fixed lip 34. A large number of heat bolts 35 are arranged at a constant pitch in the width direction of the casting die 4, that is, in the length direction of the slits 32. Each heat bolt 5 is provided with a block 36 having an embedded electric heater 37 and a cooling medium passage, and each heat bolt 35 penetrates each block 36 vertically. The base of the heat bolt 35 is fixed to the die body 31, and the tip is in contact with the outer surface of the flexible lip 33. While constantly cooling the block 36, the input to the embedded electric heater 37 is increased or decreased to increase or decrease the temperature of the block 36, thereby causing the heat bolt 35 to thermally expand and contract, thereby displacing the flexible lip 33 and thereby increasing the film thickness. adjust. Thickness gauges are installed at the required locations in the wake of the die, and the web thickness information detected by this is fed back to the control device. This thickness information is compared with the set thickness information by the control device, and corrections coming from the device It is also possible to control the power or ON rate of the heat bolt heating element by a control amount signal. The heat bolt preferably has a length of 20 to 40 cm and a diameter of 7 to 14 mm, and a plurality of, for example, several tens of heat bolts are preferably arranged at a pitch of 20 to 40 mm. Instead of the heat bolt, a gap adjusting member mainly composed of a bolt for adjusting the slit gap by manually moving back and forth in the axial direction may be provided. The slit gap adjusted by the gap adjusting member is usually 200 to 1000 μm, preferably 300 to 800 μm, more preferably 400 to 600 μm.

  The first to third cooling rolls are made of seamless steel pipe having a wall thickness of about 20 to 30 mm, and the surface is finished to a mirror surface. Inside, a pipe for flowing a coolant is arranged so that heat can be absorbed from the film on the roll by the coolant flowing through the pipe. Of the first to third cooling rolls, the first cooling roll 5 corresponds to the rotary support according to the present invention.

  On the other hand, the touch roll 6 in contact with the first cooling roll 5 has an elastic surface and is deformed along the surface of the first cooling roll 5 by the pressing force to the first cooling roll 5. A nip is formed between the two. The touch roll 6 is also called a pinching rotary body. As the touch roll 6, a touch roll disclosed in registered patent 3194904, registered patent 3422798, Japanese Patent Application Laid-Open No. 2002-36332, Japanese Patent Application Laid-Open No. 2002-36333, or the like can be preferably used. These can also use what is marketed. These will be described in more detail below.

  FIG. 4 is a cross-sectional view showing an example of the pinching rotator. (The 1st example of touch roll 6 (henceforth, outline section of touch roll A)) is shown. As shown in the drawing, the touch roll A has an elastic roller 42 disposed inside a flexible metal sleeve 41.

  The metal sleeve 41 is made of stainless steel having a thickness of 0.3 mm and has flexibility. If the metal sleeve 41 is too thin, the strength is insufficient, whereas if it is too thick, the elasticity is insufficient. For these reasons, the thickness of the metal sleeve 41 is preferably 0.1 to 1.5 mm. The elastic roller 42 is formed in a roll shape by providing a rubber 44 on the surface of a metal inner cylinder 43 that is rotatable via a bearing. When the touch roll A is pressed toward the first cooling roll 5, the elastic roller 42 presses the metal sleeve 41 against the first cooling roll 5, and the metal sleep 41 and the elastic roller 42 have the shape of the first cooling roll 5. It deforms corresponding to the familiar shape, and forms a nip with the first cooling roll. Cooling water 45 flows in a space formed between the metal sleeve 41 and the elastic roller 42.

  FIG. 5 is a cross-sectional view taken along a plane perpendicular to the rotation axis, showing a second example (hereinafter referred to as touch roll B) of the pinching rotator.

  FIG. 6 is a cross-sectional view showing an example of a plane including the rotation axis of the second example (touch roll B) of the pinching rotator.

  5 and 6 show a touch roll B which is another embodiment of the pinching rotator. The touch roll B includes a flexible, seamless stainless steel pipe (thickness 4 mm) outer cylinder 51, and a highly rigid metal inner cylinder 52 arranged on the same axis as the inner side of the outer cylinder 51. It is roughly composed. A coolant 54 flows in the space 53 between the outer cylinder 51 and the inner cylinder 52. Specifically, in the touch roll B, outer cylinder support flanges 56a and 56b are attached to the rotation shafts 55a and 55b at both ends, and a thin metal outer cylinder 51 is attached between the outer peripheral portions of the both outer cylinder support flanges 56a and 56b. Yes. A fluid supply pipe 59 is disposed in the same axial center in a fluid discharge hole 58 formed in the axial center portion of one rotary shaft 55a and forming a fluid return passage 57. The fluid supply pipe 59 is thin-walled. It is connected and fixed to a fluid shaft cylinder 60 arranged at the axial center in the metal outer cylinder 51. Inner cylinder support flanges 61a and 61b are attached to both ends of the fluid shaft cylinder 60, respectively, and a thickness of about 15 to 20 mm between the outer periphery of the inner cylinder support flanges 61a and 61b and the other end side outer cylinder support flange 56b. A metal inner cylinder 52 having a thickness is attached. A cooling liquid flow space 53 of, for example, about 10 mm is formed between the metal inner cylinder 52 and the thin metal outer cylinder 51, and the metal inner cylinder 52 has a flow space 53 and an inner space near both ends. An outlet 52a and an inlet 52b are formed to communicate with the intermediate passages 62a and 62b outside the cylinder support flanges 61a and 61b, respectively.

  Further, the outer cylinder 51 is thinned within a range in which the thin cylinder theory of elastic mechanics can be applied in order to have flexibility, flexibility, and resilience close to rubber elasticity. The flexibility evaluated by the thin-walled cylinder theory is expressed by the thickness t / roll radius r, and the flexibility increases as t / r decreases. In this touch roll B, the flexibility is the optimum condition when t / r ≦ 0.03. Usually, the touch roll generally used has a roll diameter R = 200 to 500 mm (roll radius r = R / 2), a roll effective width L = 500 to 1600 mm, and a horizontally long shape with r / L <1. is there. As shown in FIG. 6, for example, when the roll diameter R = 300 mm and the roll effective width L = 1200 mm, the appropriate range of the wall thickness t is 150 × 0.03 = 4.5 mm or less, but the molten sheet width is 1300 mm. On the other hand, when the average linear pressure is clamped at 98 N / cm, the equivalent spring constant is equal by setting the wall thickness of the outer cylinder 51 to 3 mm compared to the rubber roll of the same shape. The nip width k in the roll rotation direction of the nip is also about 9 mm, which is almost the same as the nip width of this rubber roll of about 12 mm. The deflection amount at the nip width k is about 0.05 to 0.1 mm.

  Here, t / r ≦ 0.03. However, in the case of a general roll diameter R = 200 to 500 mm, flexibility is sufficiently obtained especially in the range of 2 mm ≦ t ≦ 5 mm. Thinning by processing can be easily performed, and it is an extremely practical range. If the wall thickness is 2 mm or less, high-precision processing cannot be performed due to elastic deformation during processing.

  The converted value of 2 mm ≦ t ≦ 5 mm is 0.008 ≦ t / r ≦ 0.05 with respect to a general roll diameter, but in practical use, the roll diameter under the condition of t / r≈0.03. The wall thickness should be increased in proportion to For example, when roll diameter: R = 200, t = 2 to 3 mm, and when roll diameter: R = 500, t = 4 to 5 mm.

  The touch rolls A and B are urged toward the first cooling roll by urging means (not shown). The urging force of the urging means is F, and the value F / W (linear pressure) obtained by dividing the width of the film in the nip in the direction along the rotation axis of the first cooling roll 5 is 9.8 to 147 N / cm. Set to

  According to the present embodiment, a nip is formed between the touch rolls A and B and the first cooling roll 5, and the flatness may be corrected while the film passes through the nip. Accordingly, since the film is sandwiched over a long time with a small linear pressure compared to the case where the touch roll is formed of a rigid body and no nip is formed between the first cooling roll and the flatness is more reliably corrected. Can do. That is, when the linear pressure is smaller than 9.8 N / cm, the die line cannot be sufficiently eliminated. On the other hand, if the linear pressure is greater than 147 N / cm, the film is difficult to pass through the nip, resulting in unevenness in place of the film thickness.

  Moreover, since the surface of the touch rolls A and B can be made smoother than the case where the surface of the touch rolls is made of rubber, the surface of the touch rolls A and B can be made smoother. Can be obtained. In addition, as a material of the elastic body 44 of the elastic roller 42, ethylene propylene rubber, neoprene rubber, silicon rubber, or the like can be used.

  Now, in order to satisfactorily eliminate the die line by the touch roll 6, it is important that the viscosity of the film when the touch roll 6 clamps the film is in an appropriate range. Cellulose esters are known to have a relatively large change in viscosity with temperature. Therefore, in order to set the viscosity when the touch roll 6 clamps the optical film to an appropriate range, it is important to set the temperature of the film when the touch roll 6 clamps the film to an appropriate range. . When the glass transition temperature of the optical film is Tg, it is preferable to set the temperature T of the film immediately before the film is sandwiched between the touch rolls 6 so as to satisfy Tg <T <Tg + 110 ° C. If the film temperature T is lower than Tg, the viscosity of the film is too high and the die line cannot be corrected. On the contrary, if the temperature T of the film is higher than Tg + 110 ° C., the film surface and the roll do not adhere uniformly, and the die line cannot be corrected. Preferably, Tg + 10 ° C. <T2 <Tg + 90 ° C., more preferably Tg + 20 ° C. <T2 <Tg + 70 ° C. In order to set the temperature of the film when the touch roll 6 clamps the optical film to an appropriate range, the first cooling roll starts from the position P1 at which the melt extruded from the casting die 4 contacts the first cooling roll 5. What is necessary is just to adjust the length L along the rotation direction of the 1st cooling roll 5 of the nip of 5 and the touch roll 6. FIG.

  In the present invention, preferred materials for the first roll 5 and the second roll 6 include carbon steel, stainless steel, resin, and the like. The surface accuracy is preferably increased, and the surface roughness is set to 0.3 S or less, more preferably 0.01 S or less. In the present invention, it was discovered that the die line correction effect is more greatly manifested by reducing the pressure from the opening (lip) of the casting die 4 to the first roll 5 to 70 kPa or less. The reduced pressure is preferably 50 to 70 kPa. Although there is no restriction | limiting in particular as a method of keeping the pressure of the part from the opening part (lip | rip) of the casting die 4 to the 1st roll 5 below 70 kPa, Cover the roll periphery from the casting die 4 with a pressure | voltage resistant member, and reduce pressure. There are methods. At this time, the suction device is preferably subjected to a treatment such as heating with a heater so that the device itself does not become a place where the sublimate is attached. In the present invention, if the suction pressure is too small, the sublimate cannot be sucked effectively, so it is necessary to set the suction pressure to an appropriate value.

  In the present invention, a film-like resin in a molten state from the T die 4 is cooled and solidified while being brought into close contact with the first roll (first cooling roll) 5, the second cooling roll 7, and the third cooling roll 8 in order. The unstretched resin film 10 is obtained.

  In the embodiment of the present invention shown in FIG. 1, the cooled and solidified unstretched film 10 peeled from the third cooling roll 8 by the peeling roll 9 is guided to a stretching machine 12 via a dancer roll (film tension adjusting roll) 11. Therefore, the film 10 is stretched in the transverse direction (width direction). By this stretching, the molecules in the film are oriented.

  As a method for stretching the film in the width direction, a known tenter or the like can be preferably used. In particular, it is preferable to set the stretching direction to the width direction because lamination with a polarizing film can be performed in a roll form. By stretching in the width direction, the slow axis of the optical film becomes the width direction.

  On the other hand, the transmission axis of the polarizing film is also usually in the width direction. By incorporating a polarizing plate in which the transmission axis of the polarizing film and the slow axis of the optical film are parallel to each other into the liquid crystal display device, the display contrast of the liquid crystal display device can be increased and a good viewing angle can be obtained. Is obtained.

  The glass transition temperature Tg of the film constituting material can be controlled by varying the material type constituting the film and the ratio of the constituting material. When a retardation film is produced as an optical film, Tg is preferably 120 ° C. or higher, preferably 135 ° C. or higher. In the liquid crystal display device, in the image display state, the temperature environment of the film changes due to the temperature rise of the device itself, for example, the temperature rise derived from the light source. At this time, if the Tg of the film is lower than the use environment temperature of the film, the retardation value derived from the orientation state of the molecules fixed inside the film by stretching and the dimensional shape as the film are greatly changed.

  If the Tg of the film is too high, the temperature is increased when the film constituent material is made into a film, so that the energy consumption for heating is increased, and the material itself may be decomposed when it is made into a film, resulting in coloring. Therefore, Tg is preferably 250 ° C. or lower.

  The stretching step may be performed by known heat setting conditions, cooling, and relaxation treatment, and may be appropriately adjusted so as to have the characteristics required for the target optical film.

  In order to provide the physical properties of the retardation film and the functionality of the retardation film for expanding the viewing angle of the liquid crystal display device, the stretching step and the heat setting treatment are appropriately selected and performed. When such a stretching step and heat setting treatment are included, the heating and pressurizing step is performed before the stretching step and heat setting treatment.

  When the optical film of the present invention is manufactured as a retardation film, and further as a retardation film in which the functions of a polarizing plate protective film are combined, it is necessary to perform refractive index control, and the refractive index control may be performed by a stretching operation. preferable. Hereinafter, the stretching method will be described.

  In the retardation film stretching step, the required retardation is obtained by stretching 1.0 to 2.0 times in one direction of the film and 1.01 to 2.5 times in the direction perpendicular to the film plane. Ro and Rt can be controlled. Here, Ro indicates in-plane retardation, and Rt indicates thickness direction retardation.

  Retardation Ro and Rt are calculated | required by a following formula.

Formula (i) Ro = (nx−ny) × d
Formula (ii) Rt = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film (refractive index is 23 ° C., 55 (Measured at a wavelength of 590 nm in an environment of% RH), d represents the thickness (nm) of the film.)
The refractive index of the optical film is an Abbe refractometer (4T), the thickness of the film is a commercially available micrometer, and the retardation value is an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments). Etc.) can be used for measurement.

  Stretching can be performed, for example, sequentially or simultaneously in the longitudinal direction of the film and the direction orthogonal to the longitudinal direction of the film, that is, the width direction. At this time, if the stretching ratio in at least one direction is too small, a sufficient phase difference cannot be obtained, and if it is too large, stretching becomes difficult and film breakage may occur.

  For example, when stretching in the melt casting direction (longitudinal direction), if the shrinkage in the width direction is too large, the value of nz becomes too large. In this case, it can be improved by suppressing the width shrinkage of the film or stretching in the width direction. When stretching in the width direction, the refractive index may be distributed in the width direction. This distribution may appear when the tenter method is used. By stretching the film in the width direction, a shrinkage force is generated at the center of the film, and the phenomenon is caused by the end being fixed. It is thought to be called the Boeing phenomenon. Even in this case, by stretching in the casting direction, the bowing phenomenon can be suppressed and the distribution of the phase difference in the width direction can be reduced.

  By stretching in the biaxial directions perpendicular to each other, the film thickness variation of the obtained film can be reduced. When the film thickness variation of the retardation film is too large, the retardation becomes uneven, and unevenness such as coloring may be a problem when used in a liquid crystal display.

  The film thickness variation of the optical film is preferably in the range of ± 3%, and more preferably ± 1%. For the purposes as described above, the method of stretching in the biaxial directions perpendicular to each other is effective, and the stretching ratio in the biaxial directions perpendicular to each other is finally 1.0 to 2.0 times in the casting direction. The width direction is preferably 1.01 to 2.5 times, the casting direction is 1.01 to 1.5 times, and the width direction is 1.05 to 2.0 times. It is more preferred to obtain the required retardation value.

  When the absorption axis of the polarizer exists in the longitudinal direction, the transmission axis of the polarizer coincides with the width direction. In order to obtain a long polarizing plate by roll-to-roll bonding, the retardation film is preferably stretched so as to obtain a slow axis in the width direction.

  For example, when a cellulose ester that obtains positive birefringence with respect to stress is used, the slow axis of the retardation film can be provided in the width direction by stretching in the width direction from the above-described configuration.

In this case, in order to improve the display quality, the slow axis of the retardation film is preferably in the width direction, and in order to obtain the desired retardation value,
Formula (Stretch ratio in the width direction)> (Stretch ratio in the casting direction)
It is necessary to satisfy the following conditions.

  After stretching, after slitting the edge of the film into a product width by the slitter 13, the film is subjected to knurling (embossing) on both ends of the film by a knurling device comprising an embossing ring 14 and a back roll 15. By winding with the winder 16, sticking in the optical film (original winding) F and generation of scratches are prevented. The knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressing. In addition, since the grip part of the clip of the both ends of a film is deform | transforming normally and cannot be used as a film product, it is cut out and reused as a raw material.

  Next, in the film winding process, the film is wound on the take-up roll while keeping the shortest distance between the outer peripheral face of the cylindrical roll film and the outer peripheral face of the mobile transport roll immediately before the roll. It is. In addition, a means such as a static elimination blower for removing or reducing the surface potential of the film is provided in front of the winding roll.

  The winding machine related to the production of the optical film according to the present invention may be a commonly used winding method such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress, etc. Can be rolled up. In addition, it is preferable that the initial winding tension at the time of winding of a polarizing plate protective film is 90.2-300.8 N / m.

  In the film winding step in the method according to the present invention, the film is preferably wound under environmental conditions of a temperature of 20 to 30 ° C. and a humidity of 20 to 60% RH. Thus, the tolerance of the humidity change of thickness direction retardation (Rt) improves by prescribing | regulating the temperature and humidity in the winding-up process of a film.

  If the temperature in the winding process is less than 20 ° C., wrinkles are generated and the film winding quality is deteriorated, which is unpractical. If the temperature in the film winding process exceeds 30 ° C., wrinkles are also generated, and the film winding quality is deteriorated, so that it cannot be put into practical use.

  Moreover, if the humidity in the film winding process is less than 20% RH, it is not preferable because it is easily charged and cannot be put into practical use due to deterioration in film winding quality. If the humidity in the film winding process exceeds 60% RH, the winding quality, sticking failure, and transportability deteriorate, which is not preferable.

  When winding the polarizing plate protective film in a roll shape, the winding core may be any material as long as it is a cylindrical core, but is preferably a hollow plastic core, as a plastic material May be any heat-resistant plastic that can withstand the heat treatment temperature, and examples thereof include phenol resins, xylene resins, melamine resins, polyester resins, and epoxy resins. A thermosetting resin reinforced with a filler such as glass fiber is preferred. For example, a hollow plastic core: a wound core made of FRP and having an outer diameter of 6 inches (hereinafter, inch represents 2.54 cm) and an inner diameter of 5 inches is used.

  The number of windings to these winding cores is preferably 100 windings or more, more preferably 500 windings or more, the winding thickness is preferably 5 cm or more, and the width of the film substrate is 80 cm or more. It is preferably 1 m or more.

  Although the film thickness of the optical film according to the present invention varies depending on the purpose of use, the finished film is preferably 10 to 500 μm. In particular, the lower limit is 20 μm or more, preferably 35 μm or more. The upper limit is 150 μm or less, preferably 120 μm or less. A particularly preferable range is 25 to 90 μm. When the retardation film also serves as a polarizing plate protective film, if the film is thick, the polarizing plate after polarizing plate processing becomes too thick. Not suitable. On the other hand, if the film is thin, it is difficult to develop retardation as a retardation film. In addition, the moisture permeability of the film increases, and the ability to protect the polarizer from humidity decreases, which is not preferable.

  The slow axis or the fast axis of the retardation film exists in the film plane, and θ1 is −1 to + 1 °, preferably −0.5 to + 0.5 °, where θ1 is an angle formed with the film forming direction. To be.

  This θ1 can be defined as an orientation angle, and the measurement of θ1 can be performed using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments).

  When each θ1 satisfies the above relationship, it contributes to obtaining high luminance in a display image, suppressing or preventing light leakage, and contributing to faithful color reproduction in a color liquid crystal display device.

  When the retardation film is used for the multi-domain VA mode, the retardation film is arranged in the above region with the fast axis of the retardation film being θ1, which contributes to the improvement of display image quality. When the plate and the liquid crystal display device are in the MVA mode, for example, the configuration shown in FIG. 7 can be adopted.

  In FIG. 7, 21a and 21b are protective films, 22a and 22b are retardation films, 25a and 25b are polarizers, 23a and 23b are slow axis directions of the film, 24a and 24b are transmission axis directions of the polarizer, 26a, Reference numeral 26b denotes a polarizing plate, 27 denotes a liquid crystal cell, and 29 denotes a liquid crystal display device.

  The retardation Ro distribution in the in-plane direction of the optical film is preferably adjusted to 5% or less, more preferably 2% or less, and particularly preferably 1.5% or less. Further, the retardation Rt distribution in the thickness direction of the film is preferably adjusted to 10% or less, more preferably 2% or less, and particularly preferably 1.5% or less.

  In the retardation film, the retardation value distribution variation is preferably small. When a polarizing plate including a retardation film is used in a liquid crystal display device, the retardation distribution variation is preferably small from the viewpoint of preventing color unevenness and the like. .

  The retardation film is adjusted to have a retardation value suitable for improving the display quality of the VA mode or TN mode liquid crystal cell, and is preferably used for the MVA mode by dividing the retardation film into the above multi-domain as the VA mode. In order to achieve this, it is required to adjust the in-plane retardation Ro to a value greater than 30 nm and 95 nm or less, and the thickness direction retardation Rt to a value greater than 70 nm and 400 nm or less.

  The in-plane retardation Ro was observed obliquely from the normal line of the display surface when the two polarizing plates were arranged in crossed Nicols and the liquid crystal cell was arranged between the polarizing plates, for example, as shown in FIG. It mainly compensates for light leakage due to the deviation of the polarizing plate from the crossed Nicols state. The retardation Rt in the thickness direction mainly compensates for the birefringence of the liquid crystal cell similarly observed when viewed from an oblique direction when the liquid crystal cell is in the black display state in the TN mode or VA mode, particularly in the MVA mode. To contribute.

  As shown in FIG. 7, in the liquid crystal display device, when two polarizing plates are arranged above and below the liquid crystal cell, 22a and 22b in the figure select the distribution of the thickness direction retardation Rt. It is preferable that the total value of both of the above-mentioned ranges and the thickness direction retardation Rt be larger than 140 nm and 500 nm or less. In this case, in-plane retardation Ro and thickness direction retardation Rt of 22a and 22b are preferably the same for improving productivity of an industrial polarizing plate. Particularly preferably, the in-plane retardation Ro is larger than 35 nm and not larger than 65 nm, and the thickness direction retardation Rt is larger than 90 nm and not larger than 180 nm, and is applied to the MVA mode liquid crystal cell in the configuration of FIG. is there.

  In the liquid crystal display device, for example, a TAC film having an in-plane retardation Ro = 0 to 4 nm and a thickness direction retardation Rt = 20 to 50 nm and a thickness of 35 to 85 μm as one commercially available polarizing plate protective film, for example, When used at the position 22b in FIG. 7, the polarizing film disposed on the other polarizing plate, for example, the retardation film disposed on 22a in FIG. 7, has an in-plane retardation Ro of greater than 30 nm and 95 nm. It is preferable to use a film having a thickness direction retardation Rt of greater than 140 nm and less than or equal to 400 nm. The display quality is improved and the production of the film is preferred.

  The production effect obtained by the present invention becomes more remarkable particularly in a long roll of 100 m or more, and the longer the length is 1500 m, 2500 m, or 5000 m, the more the production effect of polarizing plate production is obtained.

  For example, in the production of a polarizing plate protective film, the roll length is 10 to 5000 m, preferably 50 to 4500 m in consideration of productivity and transportability. At this time, the width of the film is the width of the polarizer or the production line. A suitable width can be selected. A film with a width of 0.5 to 4.0 m, preferably 0.6 to 3.0 m, may be wound into a roll shape and used for polarizing plate processing. After being manufactured and wound on a roll, it may be cut to obtain a roll having a desired width, and such a roll may be used for polarizing plate processing.

  In the production of the polarizing plate protective film, functional layers such as an antistatic layer, a hard coat layer, a slippery layer, an adhesive layer, an antiglare layer, and a barrier layer may be coated before and / or after stretching. At this time, various surface treatments such as corona discharge treatment, plasma treatment, and chemical treatment can be performed as necessary.

  In the film forming process, the clip holding portions at both ends of the cut film are pulverized as described above, or after granulating as necessary, and then used as film raw materials of the same type or of different types. It can be reused as a raw material for film.

  Moreover, the optical film of a laminated structure can also be produced by coextruding compositions having different additive concentrations such as the above-mentioned plasticizer, ultraviolet absorber and matting agent.

  For example, an optical film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. In addition, the type of plasticizer and ultraviolet absorber can be changed between the core layer and the skin layer. For example, the skin layer contains a low-volatile plasticizer and / or an ultraviolet absorber, and the core layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption.

  The glass transition temperature of the skin layer and the core layer may be different, and the glass transition temperature of the core layer is preferably lower than the glass transition temperature of the skin layer. At this time, the glass transition temperatures of both the skin and the core can be measured, and an average value calculated from these volume fractions can be defined as the glass transition temperature Tg and similarly handled. Moreover, the viscosity of the melt at the time of melt casting may be different between the skin layer and the core layer, and the viscosity of the skin layer> the viscosity of the core layer or the viscosity of the core layer ≧ the viscosity of the skin layer may be used.

  The optical film according to the present invention has a dimensional stability of ± 2.0 when measured at 80 ° C. and 90% RH, based on the dimensions of the film left at 23 ° C. and 55% RH for 24 hours. %, Preferably less than 1.0%, more preferably less than 0.5%.

  When the optical film according to the present invention is used for a polarizing plate protective film as a retardation film, the retardation film itself has a variation within the above range, and the retardation has an absolute value and an orientation angle as the initial values. This is preferable because it does not deviate from the setting and does not cause deterioration in display quality.

(Polarizer)
The polarizing plate of the present invention will be described.

  The polarizing plate can be produced by a general method. The back side of the optical film of the present invention is subjected to alkali saponification treatment, and the treated optical film is bonded to at least one surface of a polarizing film produced by immersing and stretching in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. It is preferable. The optical film of the present invention may be used on the other surface, or another polarizing plate protective film may be used. With respect to the optical film of the present invention, a commercially available cellulose ester film can be used as the polarizing plate protective film used on the other surface. For example, as a commercially available cellulose ester film, KC8UX2M, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC8UCR-3, KC8UCR-4 (above, manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used. Alternatively, it is also preferable to use a polarizing plate protective film that also serves as an optical compensation film having an optical anisotropic layer formed by aligning liquid crystal compounds such as discotic liquid crystal, rod-shaped liquid crystal, and cholesteric liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP-A-2003-98348. By using in combination with the optical film of the present invention, a polarizing plate having excellent flatness and a stable viewing angle expansion effect can be obtained.

  The polarizing film, which is the main component of the polarizing plate, is an element that transmits only light having a polarization plane in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol film. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed. As the polarizing film, a polyvinyl alcohol aqueous solution is formed and dyed by uniaxially stretching or dyed, or uniaxially stretched after dyeing, and then preferably subjected to a durability treatment with a boron compound. On the surface of the polarizing film, one side of the optical film of the present invention is bonded to form a polarizing plate. It is preferably bonded with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like.

  Instead of the alkali treatment, polarizing plate processing may be performed by performing easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232.

  Since the polarizing film is stretched in a uniaxial direction (usually the longitudinal direction), when the polarizing plate is placed in a high-temperature and high-humidity environment, the stretching direction (usually the longitudinal direction) shrinks, and the direction perpendicular to the stretching (usually the width direction) ) Will grow. As the thickness of the polarizing plate protective film decreases, the expansion / contraction ratio of the polarizing plate increases, and in particular, the amount of contraction in the stretching direction of the polarizing film increases. Usually, since the stretching direction of the polarizing film is bonded to the longitudinal direction (MD direction) of the polarizing plate protective film, it is particularly important to suppress the stretching ratio in the longitudinal direction when the polarizing plate protective film is thinned. Since the optical film of the present invention is extremely excellent in dimensional stability, it is suitably used as such a polarizing plate protective film.

  That is, even when the durability test is performed at 60 ° C. and 90% RH, the wavy unevenness does not increase, and even if the polarizing plate has an optical compensation film on the back side, the viewing angle characteristics fluctuate after the durability test. Good visibility can be provided without doing so.

  The polarizing plate can be constructed by further bonding a protective film on one surface of the polarizing plate and a separate film on the opposite surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate. Moreover, a separate film is used in order to cover the contact bonding layer bonded to a liquid crystal board, and is used for the surface side which bonds a polarizing plate to a liquid crystal cell.

  In the polarizing plate of the present invention, a polarizing plate protective film of a cellulose derivative is used on the surface opposite to the retardation film as viewed from the polarizer, and a general-purpose TAC film or the like can be used. The polarizing plate protective film located on the side far from the liquid crystal cell can be provided with another functional layer in order to improve the quality of the display device.

  For example, it may be affixed to a film containing a known functional layer as a constituent for display in order to prevent reflection, anti-glare, scratch resistance, dust adhesion prevention, brightness improvement, or the polarizing plate surface of the present invention. It is not limited to.

  In general, a retardation film is required to obtain stable optical characteristics that the fluctuation of Ro or Rt is small as the above-mentioned retardation value. In particular, in a liquid crystal display device in a birefringence mode, these fluctuations may cause image unevenness.

  Since the long optical film or the long retardation film produced by the melt casting film forming method according to the present invention is mainly composed of cellulose resin, it is subjected to alkali treatment by utilizing saponification inherent to cellulose resin. There is an advantage that the process can be utilized. When the resin which comprises a polarizer is polyvinyl alcohol, it can be bonded with the said elongate film using complete saponified polyvinyl alcohol aqueous solution similarly to the conventional polarizing plate protective film. For this reason, the present invention is excellent in that the conventional polarizing plate processing method can be applied as it is, and particularly excellent in that a long roll polarizing plate can be obtained.

  The production effect obtained by the present invention becomes more remarkable particularly in a long roll of 100 m or more, and the longer the length is 1500 m, 2500 m, or 5000 m, the more the production effect of polarizing plate production is obtained.

  For example, in the retardation film production, the roll length is 10 m or more and 5000 m or less, preferably 50 m or more and 4500 m or less in consideration of productivity and transportability. The width of the film at this time is the width of the polarizer or the production. A width suitable for the line can be selected. A film is produced with a width of 0.5 m or more and 4.0 m or less, preferably 0.6 m or more and 3.0 m or less, wound into a roll, and may be used for polarizing plate processing. After a film is manufactured and wound on a roll, the film may be cut to obtain a roll having a desired width, and such a roll may be used for polarizing plate processing.

  In the film forming process, the clip gripping portions at both ends of the cut film are pulverized or granulated as necessary, and then used as a film material of the same product type or as a film material of a different product type. It may be reused.

  An optical film having a laminated structure can be produced by co-extrusion of a composition containing a cellulose resin having different additive concentrations such as the plasticizer, the ultraviolet absorber, and the matting agent. For example, an optical film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. In addition, the type of plasticizer and ultraviolet absorber can be changed between the core layer and the skin layer. For example, the skin layer contains a low-volatile plasticizer and / or an ultraviolet absorber, and the core layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. The glass transition temperature of the skin layer and the core layer may be different, and the glass transition temperature of the core layer is preferably lower than the glass transition temperature of the skin layer. At this time, the glass transition temperatures of both the skin and the core can be measured, and an average value calculated from these volume fractions can be defined as the glass transition temperature Tg and similarly handled. Also, the viscosity of the melt containing the cellulose ester during melt casting may be different between the skin layer and the core layer, and the viscosity of the skin layer> the viscosity of the core layer or the viscosity of the core layer ≧ the viscosity of the skin layer may be used.

(Liquid crystal display device)
The polarizing plate including the optical film of the present invention can exhibit high display quality as compared with a normal polarizing plate.

  The polarizing plate of the present invention includes a multi-domain vertical alignment (MVA) mode, a patterned vertical alignment (PVA) mode, a continuous pinwheel alignment (CPA) mode, an OCB (Optical Compensation InP mode, OCB (Optical Compensation InP) mode, and the like. Can be used.

  Liquid crystal display devices are being applied as devices for colorization and moving image display, and the display quality is improved by the present invention, and the improvement of contrast and the resistance of polarizing plates improve the display of moving images that are less fatigued and faithful. It becomes possible.

  By incorporating the polarizing plate bonded with the optical film of the present invention into a liquid crystal display device, it is possible to produce various liquid crystal display devices with excellent visibility, but particularly outdoors such as large liquid crystal display devices and digital signage. It is preferably used for a liquid crystal display device for use.

  In a liquid crystal display device including at least a polarizing plate including a retardation film, one polarizing plate including a retardation film is disposed with respect to the liquid crystal cell, or two polarizing plates are disposed on both sides of the liquid crystal cell. At this time, it can contribute to improvement in display quality by using the retardation film side included in the polarizing plate so as to face the liquid crystal cell of the liquid crystal display device. In FIG. 7, the films 22a and 22b face the liquid crystal cell of the liquid crystal display device.

  In such a configuration, the retardation film can optically compensate the liquid crystal cell. When the polarizing plate of the present invention is used in a liquid crystal display device, at least one polarizing plate in the liquid crystal display device may be the polarizing plate of the present invention. By using the polarizing plate of the present invention, a liquid crystal display device with improved display quality and excellent viewing angle characteristics can be provided.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further in detail, this invention is not limited to a following example, unless the summary is exceeded. In the following, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

<Preparation of resin>
(Cellulose ester having a repeating unit represented by general formula (G-1) or (G-2) (grafted cellulose ester))
<Synthesis Example 1> Synthesis of Grafted Cellulose Ester (GCE-1) 80 parts of cellulose acetate (manufactured by Daicel Chemical Industries, Ltd., L-20, substitution degree 2.41) was added to the reactor, and the temperature was 110 ° C. for 4 hours. The film was dried under reduced pressure at 4 Torr (1 Torr is 133.322 Pa). Thereafter, purging was performed with dry nitrogen, a reflux condenser was attached, 20 parts of ε-caprolactone and 67 parts of cyclohexanone that had been dried and distilled in advance were added, and the mixture was heated to 160 ° C. and stirred to dissolve cellulose acetate uniformly. To this reaction solution, 0.25 part of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, 10 parts of the reaction product was dissolved in 90 parts of chloroform, and then slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate was filtered to remove the homopolymer of ε-caprolactone. . Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the grafted cellulose ester (GCE-1) in which (epsilon) -caprolactone reacted with the cellulose acetate. And the primary structure of the cellulose ester obtained by < ¹ > H-NMR was analyzed. As a result, the average number of moles of ε-caprolactone units reacted per mole of glucose unit was 0.43, the average degree of substitution was 0.08, and the average degree of polymerization was 5.1.

<Synthesis Example 2> Synthesis of Grafted Cellulose Ester (GCE-2) 70 parts of cellulose acetate (manufactured by Daicel Chemical Industries, Ltd., L-20, substitution degree 2.41) was added to the reactor, and the temperature was 110 ° C. for 4 hours. It dried under reduced pressure at 4 Torr. Thereafter, purging was performed with dry nitrogen, a reflux condenser was attached, 30 parts of ε-caprolactone and 67 parts of cyclohexanone that had been dried and distilled in advance were added, and the mixture was heated to 160 ° C. and stirred to dissolve cellulose acetate uniformly. To this reaction solution, 0.25 part of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, after dissolving 10 parts of the reaction product in 90 parts of chloroform, it is slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate is removed by filtration to remove the homopolymer of ε-caprolactone. Furthermore, it was heated and dried at 60 ° C. for 5 hours or more to obtain grafted cellulose ester (GCE-2) in which ε-caprolactone was reacted with cellulose acetate, and the cellulose ester obtained by ¹ H-NMR was obtained. The primary structure was analyzed, and as a result, the average number of moles of ε-caprolactone units reacted per mole of glucose units was 0.86, the average degree of substitution was 0.12, and the average degree of polymerization was 7.4.

<Synthesis Example 3> Synthesis of Grafted Cellulose Ester (GCE-3) 60 parts of cellulose acetate (manufactured by Daicel Chemical Industries, Ltd., LM-80, substitution degree 2.10) was added to the reactor, and the temperature was 110 ° C. for 4 hours. It dried under reduced pressure at 4 Torr. Thereafter, purging was performed with dry nitrogen, a reflux condenser was attached, and 40 parts of ε-caprolactone and 67 parts of cyclohexanone that had been dried and distilled in advance were added and heated to 160 ° C. and stirred to dissolve cellulose acetate uniformly. To this reaction solution, 0.25 part of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, 10 parts of the reaction product was dissolved in 90 parts of chloroform, and then slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate was filtered to remove the homopolymer of ε-caprolactone. . Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the grafted cellulose ester (GCE-3) in which (epsilon) -caprolactone reacted with the cellulose acetate. And the primary structure of the cellulose ester obtained by < ¹ > H-NMR was analyzed. As a result, the average number of moles of ε-caprolactone units reacted per mole of glucose units was 1.29, the average degree of substitution was 0.34, and the average degree of polymerization was 3.9.

<Synthesis Example 4> Synthesis of Grafted Cellulose Ester (GCE-4) 70 parts of cellulose acetate (L-20, substitution degree 2.41 made by Daicel Chemical Industries, Ltd.) and 30 parts of L-lactide were added to the reactor. , 65 ° C., 12 hours, 4 Torr. Thereafter, purging was performed with dry nitrogen, a reflux condenser was attached, 67 parts of cyclohexanone that had been dried and distilled in advance was added, and the mixture was heated to 160 ° C. and stirred to dissolve cellulose acetate uniformly. To this reaction solution, 0.25 part of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, 10 parts of the reaction product was dissolved in 90 parts of chloroform, and then slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate was filtered off to remove the L-lactide homopolymer. . Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the grafted cellulose ester (GCE-4) in which L-lactide reacted with the cellulose acetate. And the primary structure of the cellulose ester obtained by < ¹ > H-NMR was analyzed. As a result, the average number of moles of lactic acid units reacted per mole of glucose units was 0.85, the average degree of substitution was 0.22, and the average degree of polymerization was 3.9.

<Synthesis Example 5> Synthesis of Grafted Cellulose Ester (GCE-5) To the reactor, 50 parts of cellulose acetate (Daicel Chemical Industries, L-20, substitution degree 2.41) and 50 parts of L-lactide were added. , 65 ° C., 12 hours, 4 Torr. Thereafter, purging was performed with dry nitrogen, a reflux condenser was attached, 67 parts of cyclohexanone that had been dried and distilled in advance was added, and the mixture was heated to 160 ° C. and stirred to dissolve cellulose acetate uniformly. To this reaction solution, 0.25 part of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, 10 parts of the reaction product was dissolved in 90 parts of chloroform, and then slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate was filtered off to remove the L-lactide homopolymer. . Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the grafted cellulose ester (GCE-5) in which L-lactide reacted with the cellulose acetate. And the primary structure of the cellulose ester obtained by < ¹ > H-NMR was analyzed. As a result, the average number of moles of lactic acid units reacted per mole of glucose units was 1.93, the average degree of substitution was 0.30, and the average degree of polymerization was 6.4.

Synthesis Example 6 Synthesis of Grafted Cellulose Ester (GCE-6) 50 parts of cellulose acetate (manufactured by Daicel Chemical Industries, Ltd., NAC, substitution degree 2.74) was added to the reactor, and 110 ° C., 4 hours, 4 Torr. And dried under reduced pressure. Thereafter, purging was performed with dry nitrogen, a reflux condenser was attached, 50 parts of ε-caprolactone and 67 parts of cyclohexanone that had been dried and distilled in advance were added, and the mixture was heated to 160 ° C. and stirred to dissolve cellulose acetate uniformly. To this reaction solution, 0.25 part of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, after dissolving 10 parts of the reaction product in 90 parts of chloroform, it was slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate (graft) was separated by filtration. The coalescence was removed. Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the grafted cellulose ester (GCE-6) in which (epsilon) -caprolactone reacted with the cellulose acetate. And the primary structure of the cellulose ester obtained by < ¹ > H-NMR was analyzed. As a result, the average number of moles of ε-caprolactone units reacted per mole of glucose units was 1.66, the average degree of substitution was 0.17, and the average degree of polymerization was 10.1.

<Synthesis Example 7> Synthesis of Grafted Cellulose Ester (GCE-7) 20 parts of cellulose acetate (manufactured by Daicel Chemical Industries, NAC, substitution degree 2.74) and 80 parts of L-lactide were added to a reactor. The film was dried under reduced pressure at 4 Torr for 24 hours at ° C. Thereafter, purging was performed with dry nitrogen, a reflux condenser was attached, and the mixture was heated to 140 ° C. and stirred to dissolve cellulose acetate uniformly. To this reaction liquid, 0.10 parts of tin octoate was added and heated at 140 ° C. with stirring for 1 hour. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, 10 parts of the reaction product was dissolved in 90 parts of chloroform, and then slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate was filtered off to remove the L-lactide homopolymer. . Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and the grafted cellulose ester (GCE-7) which L-lactide reacted with the cellulose acetate was obtained. And the primary structure of the cellulose ester obtained by < ¹ > H-NMR was analyzed. As a result, the average number of moles of lactic acid units reacted per mole of glucose units was 14.1, the average degree of substitution was 0.23, and the average degree of polymerization was 60.5.

<Synthesis Example 8> Synthesis of Grafted Cellulose Ester (GCE-8) 5.0 g of the grafted cellulose ester (GCE-1) obtained in Synthesis Example 1 was dissolved in 50 g of dehydrated pyridine at room temperature. Then, 50 g of propionic anhydride and 0.5 g of dimethylaminopyridine were added and reacted at 100 ° C. for 1 hour. After the reaction, it was cooled to room temperature and the product was precipitated in methanol. Furthermore, it washed and vacuum-dried and obtained the grafted cellulose ester (GCE-8) which introduce | transduced the protective group.

  When the obtained grafted cellulose ester (GCE-8) was analyzed by NMR, it was confirmed that all hydroxyl ends of the graft chain were propionylated.

(Acrylic resin (AMP) obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the general formula (AM) and at least one acrylate monomer or methacrylate monomer)
<Synthesis Example 9> Synthesis of Acrylic Resin (AMP) A copolymer (AMP-1) of exemplary compound AM-1 and methyl methacrylate was synthesized according to the method described below.

  In 100 ml of toluene, 3.0 g of the compound AM-1 (commercial product) and 7.0 g of methyl methacrylate were added, and then 0.1 g of azoisobutyronitrile was added. The reaction was heated to 80 ° C. under a nitrogen atmosphere for 5 hours. After 70 ml of toluene was distilled off under reduced pressure, it was dropped into a large excess of methanol. The deposited precipitate was collected by filtration and vacuum dried at 40 ° C. to obtain 6.5 g of a copolymer (AMP-1). This copolymer was confirmed by GPC analysis based on standard polystyrene to have a weight average molecular weight of 10,000 and Mw / Mn of 2.5.

  From the NMR spectrum, it was confirmed that the copolymer was a copolymer of Exemplified Compound AM-1 and methyl methacrylate. The composition of the polymer was AM-1: methyl methacrylate≈30: 70.

  The copolymer polymers AMP-2 to 10 were synthesized by the same synthesis method as described above except that the monomer types and composition ratios shown in Table 1 were changed, and the weight average molecular weight and composition were confirmed. Details of the synthesized polymers are shown in Table 1.

<Synthesis Example 10> Synthesis of Acrylic Resin (AC-1) An acrylic resin (AC-1) was synthesized according to the method described below.

  In 100 ml of toluene, 7.0 g of methyl methacrylate, 2.0 g of methyl acrylate, and 1.0 g of 2-hydroxyethyl methacrylate were added, and then 0.1 g of azoisobutyronitrile was added. The reaction was heated to 80 ° C. under a nitrogen atmosphere for 5 hours. After 70 ml of toluene was distilled off under reduced pressure, it was dropped into a large excess of methanol. The deposited precipitate was collected by filtration and vacuum dried at 40 ° C. to obtain 7.5 g of a copolymer (AC-1). This copolymer was confirmed by GPC analysis based on standard polystyrene to have a weight average molecular weight of 7000 and Mw / Mn of 2.4.

  From the NMR spectrum, it was confirmed that the copolymer was a copolymer of methyl methacrylate: methyl acrylate: 2-hydroxyethyl methacrylate. The composition of the polymer was approximately methyl methacrylate: methyl acrylate: 2-hydroxyethyl methacrylate = 70: 20: 10.

  In addition to the synthesized acrylic resin (AMP), the following commercially available acrylic resins were used.

AC-2: Act Flow UMM-1001 (manufactured by Soken Chemical Co., Ltd.) Mw1000
AC-3: Acripet V (Mitsubishi Rayon Co., Ltd.) Mw100,000
(Cellulose ester (CE))
The following cellulose esters CE-1 to CE-7 were prepared by known methods.

CE-1: Cellulose acetate propionate (acyl group total substitution degree 2.9, acetyl group substitution degree 2.4, propionyl group substitution degree 0.5, molecular weight Mw = 200000)
CE-2: Cellulose acetate propionate (acyl group total substitution degree 2.8, acetyl group substitution degree 0.2, propionyl group substitution degree 2.6, molecular weight Mw = 200000)
CE-3: cellulose acetate propionate (acyl group total substitution degree 2.6, acetyl group substitution degree 1.4, propionyl group substitution degree 1.2, molecular weight Mw = 200000)
CE-4: cellulose acetate propionate (acyl group total substitution degree 2.6, acetyl group substitution degree 1.0, propionyl group substitution degree 1.6, molecular weight Mw = 200000)
CE-5: cellulose acetate propionate (acyl group total substitution degree 2.2, acetyl group substitution degree 2.0, propionyl group substitution degree 0.2, molecular weight Mw = 200000)
CE-6: Cellulose acetate propionate (acyl group total substitution degree 2.2, acetyl group substitution degree 0.6, propionyl group substitution degree 1.6, molecular weight Mw = 200000)
CE-7: cellulose acetate propionate (acyl group total substitution degree 1.9, acetyl group substitution degree 0.3, propionyl group substitution degree 1.6, molecular weight Mw = 200000)
In addition, the following commercially available cellulose esters were used.

CE-8: Cellulose acetate NAC (manufactured by Daicel Chemical Industries, Ltd., degree of acetyl substitution 2.74)
CE-9: Cellulose acetate L-20 (Daicel Chemical Industries, Inc., acetyl group substitution degree 2.41)
CE-10: Cellulose acetate LM-80 (manufactured by Daicel Chemical Industries, Ltd., degree of acetyl substitution 2.10)
<Preparation of optical film 1>
As described below, an optical film 1 was prepared by melt casting using cellulose ester, acrylic resin, and grafted cellulose ester.

Cellulose ester CE-1 60 parts by mass Acrylic resin AMP-1 30 parts by mass Grafted cellulose ester GCE-1 10 parts by mass Cellulose ester, acrylic resin and grafted cellulose ester were dried at 70 ° C. under reduced pressure for 3 hours to room temperature. After cooling, it was mixed.

  The above mixture was melt-mixed at 230 ° C. using a twin-screw extruder and pelletized.

  Using this pellet, an optical film was produced by a production apparatus of the type shown in FIG. Hereinafter, the manufacturing process will be described with reference to FIG.

  Under a nitrogen atmosphere, it was melted at 250 ° C., extruded from the casting die 4 onto the first cooling roll 5, and formed by pressing the film between the first cooling roll 5 and the touch roll 6.

  The heat bolt was adjusted so that the gap width of the casting die 4 was 0.5 mm within 30 mm from the end in the width direction of the film and 1 mm at other locations. The touch roll A was used as the touch roll, and 80 ° C. water was poured as cooling water therein.

  From the position P1 at which the resin extruded from the casting die 4 contacts the first cooling roll 5 to the position P2 at the upstream end in the rotation direction of the first cooling roll 5 in the nip between the first cooling roll 5 and the touch roll 6. 1 The length L along the peripheral surface of the cooling roller 5 was set to 20 mm. Thereafter, the touch roll 6 was separated from the first cooling roll 5, and the temperature T of the melted part immediately before being sandwiched between the first cooling roll 5 and the touch roll 6 was measured. In the present embodiment, the temperature T of the melted part immediately before being sandwiched between the nips of the first cooling roll 5 and the touch roll 6 is 1 mm upstream from the nip upstream end P2, and a thermometer (an independent meter). It was measured by HA-200E manufactured by Co., Ltd. As a result of the measurement in this example, the temperature T was 141 ° C. The linear pressure of the touch roll 6 against the first cooling roll 5 was 14.7 N / cm. Furthermore, after being introduced into a tenter and stretched 1.2 times at 160 ° C in the width direction, it was cooled to 30 ° C while relaxing 3% in the width direction, and then released from the clip. Was subjected to a knurling process with a width of 10 mm and a height of 5 μm, and wound on a winding core with a winding tension of 220 N / m and a taper of 40%. In addition, the extrusion amount and the take-up speed were adjusted so that the film had a thickness of 80 μm, and the finished film width was slit and wound up so as to have a width of 1430 mm. The winding core had an inner diameter of 152 mm, an outer diameter of 165 to 180 mm, and a length of 1550 mm.

  A prepreg resin obtained by impregnating glass fibers and carbon fibers with an epoxy resin was used as the core material for the core. The surface of the core was coated with an epoxy conductive resin, the surface was polished, and the surface roughness Ra was finished to 0.3 μm. The winding length was 2500 m. This film original fabric sample of the present invention is designated as an optical film 1.

  Moreover, when the glass transition temperature of the produced optical film 1 was measured using a differential scanning calorimeter (DSC-7 type manufactured by Perkin Elmer), a peak was observed only at one location of Tg: 136 ° C. 3 It was found that the seed resin was present in a compatible state. Furthermore, when the retardation of the optical film 1 was measured in an environment of a temperature of 23 ° C. and a humidity of 55% RH using an automatic birefringence meter KOBRA-21-ADH (manufactured by Oji Scientific Instruments), Ro was 2 nm and Rt was It was 41 nm. The retardation of the optical film 31 was 1 nm for Ro and 2 nm for Rt.

(Preparation of optical films 2 to 42)
Optical films 2 to 42 were produced in the same manner except that the type and amount of resin were changed as shown in Table 2 in the production of the optical film 1. Moreover, when the retardation of the optical film 31 was measured in the same manner as described above, Ro was 1 nm and Rt was 2 nm.

<Evaluation method>
The following evaluation was implemented about the obtained optical films 1-42.

(Haze: Transparency evaluation that greatly affects contrast)
About each produced said film sample, 23 degreeC55% RH atmosphere WHEREIN: One film sample was measured using the haze meter (NDH2000 type | mold, Nippon Denshoku Industries Co., Ltd.) according to JISK-7136. .

(Ductile fracture: brittleness evaluation)
In an atmosphere of 23 ° C. and 55% RH, the optical film was cut out at 100 mm (vertical) × 10 mm (width), folded at the center in the vertical direction once into a mountain fold and a valley fold, and this evaluation was evaluated as 3 The measurement was repeated and evaluated according to the following criteria. In addition, the evaluation break here means that it broke and separated into two or more pieces, and when a break is made, it means that the crack is broken and the two or more pieces are not separated, but a cut is made halfway. Represent.

○: Cannot be broken 3 times △: At least 1 out of 3 breaks ×: At least 1 out of 3 breaks (breaking failure)
Evaluation was made according to the following criteria.

◎: No breakage occurred in 10 film formation tests ○: One break occurred in 10 film formation tests Δ: Break occurred twice in 10 film formation tests ×: In 10 film formation tests Break occurred 3 times or more.

<Characteristic evaluation as a liquid crystal display device>
<Preparation of polarizing plate>
A polarizing plate using each optical film as a polarizing plate protective film was prepared as follows.

  A 120 μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched in the transport direction 5 times at 50 ° C. to prepare a polarizing film.

  Next, the optical film 1 subjected to alkali saponification treatment on one side of the polarizing film was bonded using a polyvinyl alcohol aqueous solution as an adhesive.

  Furthermore, KC8UCR-5 manufactured by Konica Minolta Opto Co., Ltd., which is a retardation film subjected to alkali saponification treatment, was bonded to the other surface of the polarizing film and dried to prepare a polarizing plate P1. Similarly, polarizing plates P2 to P42 were produced using the optical films 2 to 42.

  The polarizing plate using the optical film of the present invention was excellent in film cutting property and easy to process.

<Production of liquid crystal display device>
Using each of the produced polarizing plates P1 to P42, display characteristics of the optical film were evaluated.

  The polarizing plates on both sides of the 32-inch television AQ-32AD5 manufactured by Sharp Corporation are peeled off in advance, and the prepared polarizing plates P1 to P42 are placed so that KC8UCR-5 is on the glass surface side of the liquid crystal cell. And it bonded so that an absorption axis might turn to the same direction as the polarizing plate previously bonded, and produced the liquid crystal display devices 1-42.

(Variation of viewing angle: Evaluation of heat and moisture resistance as a polarizing plate protective film)
The following evaluation was performed using the liquid crystal display devices 1 to 42 produced as described above.

  The viewing angle of the liquid crystal display device was measured using EZ-Contrast 160D manufactured by ELDIM in an environment of 23 ° C. and 55% RH. Subsequently, the polarizing plate treated at 60 ° C. and 90% RH for 1000 hours was measured in the same manner, and the viewing angle fluctuation was evaluated in four stages according to the following criteria.

◎: No viewing angle variation ○: Slight viewing angle variation is observed △: Viewing angle variation is recognized ×: Viewing angle variation is large (color shift: heat and moisture resistance evaluation as a polarizing plate protective film)
Regarding the produced liquid crystal display devices 1 to 51, the display was displayed in black in an environment of 23 ° C. and 55% RH and observed from an oblique angle of 45 °. Subsequently, the polarizing plate treated at 60 ° C. and 90% RH for 1000 hours was observed in the same manner, and the color change was evaluated in four stages according to the following criteria.

：: No color change ○: Color change is slightly recognized Δ: Color change is observed ×: Color change is large Table 3 shows the results of the above evaluation.

  As shown in Table 3, the optical film of the present invention was transparent and exhibited the characteristics of excellent improvement in brittleness, and was able to reduce the occurrence of breakage failure. Moreover, the polarizing plate and liquid crystal display device produced using the optical film of the present invention exhibited excellent properties in visibility and color shift.

Example 2
As shown in Table 4 below, the resin type, addition amount, additive type, addition amount, acrylic particles, plasticizer and ultraviolet absorber were added, and optical films 43 to 51 were produced in the same manner as in Example 1. Polarizing plates P43 to 51 and liquid crystal display devices 43 to 51 were produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 5.

  For the optical films 52 and 53, as shown in Table 4, the type of resin, the amount added, the type of additive, the amount added, and further acrylic particles and a plasticizer were added and introduced into the tenter in the manufacturing method of Example 1. Then, it was produced in the same manner as in Example 1 except that the film was stretched 1.4 times at 160 ° C. in the width direction. When the retardation of the produced optical films 52 and 53 was measured using an automatic birefringence meter KOBRA-21-ADH (manufactured by Oji Scientific Instruments) under an environment of a temperature of 23 ° C. and a humidity of 55% RH, 40 nm, Rt was 125 nm, Ro was 42 nm, and Rt was 128 nm. Accordingly, in the production of polarizing plates, optical films 52 and 53 are used as retardation films, and KC8UX2M manufactured by Konica Minolta Opto Co., Ltd. is bonded to the other surface to produce polarizing plates P52 and 53. The liquid crystal display devices 52 and 53 were produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 5. The following was used as an additive.

(1) -A: Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.)
(1) -B: Sumizer GM (manufactured by Sumitomo Chemical Co., Ltd.)
(3) -A: IRGANOX 1010 (manufactured by Ciba Japan)
(3) -B: IRGANOX 1076 (manufactured by Ciba Japan)
(4) -A: ADK STAB LA-52 (manufactured by ADEKA Corporation)
(5) -A: ADK STAB PEP-36 (manufactured by ADEKA Corporation))
(5) -B: GSY-P101 (manufactured by Sakai Chemical Industry Co., Ltd.)
The following were used as acrylic particles.

AP-1: Metabrene W-341 (Mitsubishi Rayon Co., Ltd.)
AP-2: Chemisnow MR-2G (manufactured by Soken Chemical Co., Ltd.)
The following were used as plasticizers.

  The following was used as the ultraviolet absorber.

UV-1: TINUVIN 928 (manufactured by Ciba Japan)
UV-2: ADK STAB LA-31 (manufactured by ADEKA Corporation)

  The optical film of the present invention was able to be produced without causing breakage failure, with the transparency (haze) being equal to or slightly lower than that of the film containing no additive. Moreover, the polarizing plate and the liquid crystal display device produced using the optical film of the present invention were able to further improve the visibility.

DESCRIPTION OF SYMBOLS 1 Extruder 2 Filter 3 Static mixer 4 Casting die 5 Rotating support body (1st cooling roll)
6 Nipping pressure rotating body (touch roll)
7 Rotating support (second cooling roll)
8 Rotating support (3rd cooling roll)
9, 11, 13, 14, 15 Transport roll 10 Cellulose ester film 12 Stretcher 16 Winding device 21a, 21b Protective film 22a, 22b Retardation film 23a, 23b Film slow axis direction 24a, 24b Polarizer transmission axis Direction 25a, 25b Polarizer 26a, 26b Polarizing plate 27 Liquid crystal cell 29 Liquid crystal display device 31 Die body 32 Slit 41 Metal sleeve 42 Elastic roller 43 Metal inner cylinder 44 Rubber 45 Cooling water 51 Outer cylinder 52 Inner cylinder 53 Space 54 Cooling Liquid 55a, 55b Rotating shaft 56a, 56b Outer cylinder support flange 60 Fluid shaft cylinder 61a, 61b Inner cylinder support flange 62a, 62b Intermediate passage 110 Core body 117 Support plate 118 Base 120 Cellulose ester film original

Claims (7)

Cellulose ester (CE) having a substitution degree of 2.0 to 3.0 and cellulose having a repeating unit represented by the following general formula (G-1) or (G-2), which is different from the cellulose ester (CE) An optical film comprising an ester (GCE) and an acrylic resin.

(In the formula, A and B each represent a divalent hydrocarbon group having 1 to 12 carbon atoms or a divalent hydrocarbon group having 1 to 12 carbon atoms substituted with a hydroxyl group. (Cel represents a cellulose ester residue, and n is 1 to 70.) The acrylic resin is a polymer obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the following general formula (AM) and at least one acrylic ester monomer or methacrylic ester monomer. The optical film according to claim 1.

(Wherein R ¹ , R ² , and R ³ are each independently an alkyl group, a cycloalkyl group, an aryl group, an acylamino group, an alkylthio group, an arylthio group, an alkenyl group, a halogen atom, an alkynyl group, or a heterocyclic ring. Group, alkylsulfonyl group, arylsulfonyl group, alkylsulfinyl group, arylsulfinyl group, phosphono group, acyl group, carbamoyl group, sulfamoyl group, sulfonamido group, cyano group, alkoxy group, aryloxy group, heterocyclic oxy group, siloxy Group, acyloxy group, sulfonic acid group, sulfonic acid salt, aminocarbonyloxy group, amino group, anilino group, imide group, ureido group, alkoxycarbonylamino group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic thio group, Thioureido group, carbo Sill group, salts of carboxylic acids, hydroxyl group, mercapto group, a nitro group or a substituent having an ethylenically unsaturated bond. The bonded R ^1, R ^2, and any two of R ³ to each other, An annular structure may be formed.)   2. A carbon radical scavenger, a primary antioxidant having a hydrogen radical donating ability for peroxy radicals, and a secondary antioxidant having a reducing action on peroxides. Or the optical film of 2.   The optical film according to claim 1, wherein the optical film contains acrylic particles.   A method for producing an optical film, comprising producing the optical film according to any one of claims 1 to 4 by a melt casting film forming method using a touch roll.   A polarizing plate using the optical film according to claim 1.   A liquid crystal display device using the polarizing plate according to claim 6.

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