TWI684796B - Method for fabricating polarizing plate - Google Patents

Abstract

Provided is a method for fabricating a polarizing plate. The method includes the following steps: a resin layer forming step of forming a polyvinyl alcohol resin layer on at least a surface of substrate film to obtain a laminated film; a stretching step of stretching the laminate film to obtain a stretched film; a dying step of forming a polarizer layer by dying the polyvinyl alcohol resin layer of the extended film using a dichroic dye, to obtain a polarized, laminated layer; a laminating step of laminating a protective film on the surface of a side opposite to the substrate film of the polarizer layer of the polarized, laminated film, to obtain a multilayer film; and a peeling step of peeling the multilayer film off from the substrate film to obtain a polarizing plate. In the aforesaid peeling step, the angle between the peeling direction of the substrate film and the orienting direction of the polarizer layer is 20° or less.

Description

The invention relates to a method for manufacturing a polarizing plate.

The polarizing plate is widely used as a polarizing light supply element of a liquid crystal display device. As such a polarizing plate, a polarizing layer composed of a polyvinyl alcohol-based resin and a protective film laminate such as triethyl cellulose have been conventionally used. While the polarizing layer (polarizing film) requires high optical performance, in recent years, with the development of mobile devices such as notebook personal computers and mobile phones for liquid crystal display devices, there has been a demand for thin-walled and lightweight.

As an example of a method of manufacturing such a thin polarizer, it is proposed to apply a solution containing a polyvinyl alcohol-based resin on the surface of the base film, and after providing the resin layer, extend the laminated film composed of the base film and the resin layer, Then, by dyeing, crosslinking (fixing), and drying, a polarizing layer is formed from the resin layer, and a polarizing laminate film having a polarizing layer can be obtained (for example, refer to JP-2000-338329-A). The method of using it as a polarizing plate as it is has been disclosed, or after attaching a protective film to the film, peeling off the base material film and using it as a polarizing plate.

[Patent Document 1] JP-2000-338329-A

In the manufacturing method of the polarizing plate described above, there may be slight floating or peeling between the base film and the resin layer. This is caused by differences in the behavior of the base film and the resin layer when the laminated film composed of the base film and the resin layer is stretched, dyed, crosslinked, and dried. Especially in the extension step, When stretching more than 5 times, the amount of deformation of the base film and the resin layer becomes larger, the difference in behavior at each step becomes significant, and the above floating and peeling are likely to occur.

In order to suppress the occurrence of floating and peeling, it is necessary to increase the adhesion between the base film and the resin layer, for example, a method of providing an easy bonding layer and an undercoat layer with high adhesion. On the other hand, if the adhesion between the base film and the resin layer is increased and the polarizer is used after the base film is peeled off, cohesive failure of the resin layer occurs due to the peeling of the base film. The quality of the board has an impact.

Therefore, the present invention aims to provide a method of manufacturing a polarizing plate in which the adhesion between the base film and the resin layer has strength to withstand the steps of stretching, dyeing, and cross-linking, and the base film can be peeled off beautifully.

The present inventors discovered that the laminated film composed of the base film and the resin layer has different adhesion between the base film and the resin layer in the alignment direction of the resin layer and the direction perpendicular thereto, and thus completed the present invention.

The method for manufacturing a polarizing plate of the present invention includes: forming a polyvinyl alcohol-based resin layer on at least one surface of a base film to obtain a resin layer forming step of a laminated film; and extending the laminated film to obtain an extended film ; The polyvinyl alcohol-based resin layer of the stretched film is dyed with a dichroic dye to form a polarizing layer to obtain a polarizing laminated film dyeing step; on the side opposite to the base film of the polarizing layer of the polarizing laminated film, The step of bonding the protective film to obtain a multilayer film; and the step of peeling the base film from the multilayer film to obtain a polarizing plate; wherein, in the above peeling step, the peeling direction of the base film and the alignment direction of the polarizing layer are Angle of 20 Degrees below.

In the above peeling step, at the peeling point, the angle formed by the multilayer film and the polarizing plate is preferably smaller than the angle formed by the multilayer film and the base film, and the angle formed by the multilayer film and the polarizing plate is preferably 45 degrees or less.

According to the present invention, the laminate film composed of the base film and the resin layer is subjected to treatments such as stretching and dyeing, and then the base film can be peeled off beautifully to manufacture a polarizing plate.

Hereinafter, a preferred embodiment of the method for manufacturing the polarizing plate of the present invention will be described in detail while referring to the drawings.

[Manufacturing method of polarizing plate]

FIG. 1 is a flowchart showing an embodiment of the method of manufacturing a polarizing plate of the present invention. According to this, the manufacturing method of the polarizing plate sequentially includes: a resin layer forming step (S10) of forming a polyvinyl alcohol-based resin layer on at least one surface of the base film to obtain a laminated film; stretching the laminated film to obtain an extension The stretching step of the film (S20); the polyvinyl alcohol resin layer of the stretched film is dyed with a dichroic dye to form a polarizing layer, and a dyeing step (S30) to obtain a polarized laminated film; the polarized light with the polarized laminated film The surface on the opposite side of the base film of the layer is bonded with a protective film to obtain a multilayer film (S40); and the base film is peeled from the multilayer film to obtain a polarizing plate peeling step (S50).

The polarizing plate obtained by this manufacturing method becomes a polarizing plate provided with a polarizing layer having a thickness of 10 μm or less on the protective film, for example. The polarizing plate can be attached to other optical films, liquid crystal cells, etc. with an adhesive layer interposed therebetween, for example.

<Peeling Step (S50)>

In the peeling step (S50), the method of peeling the base film is not particularly limited, and the peeling direction is such that the angle formed by the peeling direction of the base film and the alignment direction of the polarizing layer is 20 degrees or less.

FIG. 2 is a schematic model top view showing the relationship between the peeling direction of the base film and the alignment direction of the polarizing layer in the peeling step (S50). In FIG. 2, the base film 11 is peeled off from the multilayer film 10 to form a polarizing plate 12 composed of a protective film and a polarizing layer. Here, the alignment direction of the polarizing layer is represented by arrow A, the peeling direction of the base film 11 is represented by arrow B, and the angle formed by the peeling direction of the base film (arrow B) and the alignment direction of the polarizing layer (arrow A) is θ said. In the present invention, the angle θ formed by the peeling direction (arrow B) of the base film and the alignment direction (arrow A) of the polarizing layer is 20 degrees or less, preferably 10 degrees or less, and more preferably 5 degrees or less for peeling.

By peeling off at an angle θ of 20 degrees or less, the base film 11 can be peeled off without causing cohesive damage to the polarizing layer. In addition, by peeling at an angle θ of 20 degrees or less, the base film 11 can be peeled smoothly.

The alignment direction of the polarizing layer refers to the direction in which the main chain of the polyvinyl alcohol-based resin constituting the polarizing layer is aligned due to extension, and the direction of the highest refractive index in the plane of the polarizing layer. The alignment direction of the polarizing layer and the extension in the extension step (S20) are uniaxial extensions, which are consistent with the extension direction. In the case of biaxial extension, the alignment direction is mostly the direction of higher magnification extension, and the extension in the two directions is consistent with one of the extension directions.

FIG. 3 is a schematic top view showing a preferred example of the peeling direction in the peeling step (S50) of the present invention. In the example shown in Figure 3, the basic The angle θ formed by the peeling direction B of the material film and the alignment direction A of the polarizing layer is 0.

p，多層膜10與基材薄膜11所成的角度為

k。於本發明，較理想為

p<

k，更理想為

p

45度。而且，

p最好為0度。藉由

p<

k，進一步為

p

45度下剝離基材薄膜，抑制對偏光層之內聚破壞的同時，可平滑地剝離基材薄膜。 In addition, in the peeling step (S50), at the peeling point, the angle formed by the multilayer film (the film before peeling the base film) and the polarizing plate is greater than that formed by the multilayer film (the film before peeling the base film) and the base film The angle is small, ideal for peeling the substrate film. FIG. 4 is a schematic top view of the model showing the relationship between the angle formed by the multilayer film and the polarizing plate and the angle formed by the multilayer film and the base film at the peeling point. In FIG. 4, at the peeling point C, the base film 11 is peeled off from the multilayer film 10 to form a polarizing plate 12 composed of a protective film and a polarizing layer. Here, at the peeling point C, the angle formed by the multilayer film 10 and the polarizing plate 12 is

p, the angle formed by the multilayer film 10 and the substrate film 11 is

k. In the present invention, it is more desirable to

p<

k, more ideally

p

45 degree. and,

p is preferably 0 degrees. By

p<

k, further

p

The base film can be peeled off at 45 degrees, and the base film can be peeled off smoothly while suppressing the cohesive damage to the polarizing layer.

p及

k之上述條件為有效。 In FIG. 4, at the peeling point C, the base film 11 and the polarizing plate 12 are peeled off at an angle to the multilayer film 10 in the opposite direction, but the multilayer film 10 may also be The polarizing plate 12 is peeled off at an angle in the same direction. Even in this case, regarding the angle

p and

The above condition of k is valid.

p、

k可根據夾持滾輪的大小、配置位置等適當選擇而調整。於第5圖所示的例，

p=0度、

p<

k。 Fig. 5 is a schematic top view of a model showing a preferred example of the peeling angle in the peeling step (S50) of the present invention. As shown in Figure 5, the angle

p,

k can be adjusted according to appropriate selection according to the size and arrangement position of the clamping roller. In the example shown in Figure 5,

p=0 degrees,

p<

k.

Hereinafter, each step other than the peeling step (S50) of FIG. 1 will be described in detail.

<Step of forming resin layer (S10)>

In the resin layer forming step (S10), a polyvinyl alcohol-based resin layer is formed on at least one surface of the base film.

(Substrate film)

As the resin used for the base film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, and extensibility is used, and a suitable resin can be selected according to the glass transition temperature Tg or melting point Tm of these. The base film is preferably used in a temperature range suitable for the extension of the polyvinyl alcohol-based resin deposited thereon.

Specific examples of thermoplastic resins include polyolefin resins, polyester resins, cyclic polyolefin resins (norbornene resins), (meth)acrylic resins, cellulose ester resins, and polycarbonate resins. Resins, polyvinyl alcohol-based resins, vinyl acetate-based resins, polyacrylate-based resins, polystyrene-based resins, polyether-based resins, poly-based resins, polyamide-based resins, polyimide-based resins and These mixtures, copolymers, etc.

For the base film, only one of the above resins may be used, or a mixture of two or more resins may be used. The substrate film may be a single layer or a multilayer film.

As the polyolefin-based resin, for example, polyethylene, polypropylene, etc., it is desirable to easily and stably extend at a high rate. Furthermore, an ethylene-polypropylene copolymer obtained by copolymerizing propylene and ethylene can be used. The copolymerization may also be other types of monomers, as other types of monomers copolymerizable with propylene, such as ethylene and α-olefin. As the α-olefin, it is reasonable to use an α-olefin having 4 or more carbon atoms It is desirable that it is an α-olefin having 4 to 10 carbon atoms. Specific examples of α-olefins having 4 to 10 carbon atoms, such as linear monoolefins such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, etc. Class; branched monoolefins such as 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene; vinyl cyclohexane, etc. The copolymer of propylene and other monomers copolymerizable therewith may be a random copolymer or a block copolymer. The content rate of the structural unit derived from this other monomer in the copolymer is determined by performing infrared (IR) spectrometry according to the method described on page 616 of the "Polymer Analysis Handbook" (issued in 1995 by Kikuniya Bookstore). Get.

Among the above, as the propylene-based resin constituting the propylene-based resin film, a single polymer of propylene, a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, and a propylene-ethylene-1-butene free Regular copolymers are ideal.

In addition, the three-dimensional regularity of the propylene-based resin constituting the propylene-based resin film is substantially isotactic or syndiotactic. A propylene resin film composed of a propylene resin substantially having isotactic or syndiotactic three-dimensional regularity has good usability and good mechanical strength in a high-temperature environment.

Polyester resins are polymers with ester linkages, mainly polycondensates of polyvalent carboxylic acids and polyvalent alcohols. Among the polyvalent carboxylic acids used, divalent dicarboxylic acids, such as terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalene dicarboxylate, are mainly used. Furthermore, for the polyvalent alcohol used, divalent diols such as propylene glycol, butylene glycol, neopentyl glycol, cyclohexanedimethanol, and the like are mainly used. As specific resins, for example, polyethylene terephthalate, Polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polypropylene naphthalate, polycyclohexane terephthalate Methyl ester, cyclohexyl methyl naphthalate, etc. For these mixed resins, copolymers can be suitably used.

As the cyclic polyolefin resin, it is preferable to use norbornene resin. The cyclic polyolefin resin is a general term for resins polymerized by polymerization units, for example, the resins described in Japanese Patent Laid-Open No. 1-240517, Japanese Patent Laid-Open No. 3-14882, Japanese Patent Laid-Open No. 3-122137, and the like. As specific examples, for example, ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, α-olefins of cyclic olefins with ethylene, propylene, and their copolymers (represented as random copolymers) and These graft copolymers modified with unsaturated carboxylic acids, their derivatives, and these hydrides. As a specific example of the cyclic olefin, for example, a norbornene-based monomer.

As the cyclic polyolefin resin, various products are commercially available. As specific examples, for example, Topas (registered trademark) (manufactured by Ticona Corporation), Arton (registered trademark) (manufactured by JSR Corporation), ZEONOR (registered trademark) (manufactured by NEON Corporation), ZEONEX (registered trademark) (Japan NEON (registered trademark) Stock system), APL (registered trademark) (Mitsui Chemical Co., Ltd. system).

As the (meth)acrylic resin, any suitable (meth)acrylic resin can be used. For example, poly(meth)acrylates such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymers, methyl methacrylate-(meth)acrylate copolymers, methyl methacrylate Ester-acrylate-(meth)acrylic acid copolymer, methyl (meth)acrylate-styrene copolymer (MS resin, etc.), polymers with alicyclic hydrocarbons (such as methyl methacrylate) Ester-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). Poly(meth)acrylate and other poly(meth)acrylate C1-6 alkyl esters are more desirable. As the (meth)acrylic resin, it is more preferable to use methyl methacrylate resin having methyl methacrylate as the main component (50 to 100% by weight, more preferably 70 to 100% by weight).

The cellulose ester resin is an ester of cellulose and fatty acid. Specific examples of such cellulose ester resins include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Moreover, for example, those copolymers and a part of hydroxyl groups are modified with other kinds of substituents and the like. Among these, cellulose triacetate is particularly desirable. Cellulose triacetate is commercially available in various products, which is advantageous in terms of availability and cost. Examples of commercially available products of cellulose triacetate include Fujitac (registered trademark) TD80 (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UF (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UZ (Fuji Film Co., Ltd.), Fujitac (registered trademark) TD40UZ (Fuji Film Co., Ltd.), KC8UX2M (Konica Minolta (Co., Ltd.)), KC4UY (Konica Minolta (Co., Ltd.) Stock) system etc.

Polycarbonate resins are engineering plastics composed of polymers in which monomer units are bonded through carbonate groups, and have high impact resistance, heat resistance, and flame retardancy. Moreover, due to its high transparency, it is also suitable for optical applications. For optical applications, in order to reduce the photoelastic coefficient, modified polycarbonate resins called polymer skeleton modifications, copolymerized polycarbonates with improved wavelength dependence, etc. are also commercially available, and can also be suitably used. Such polycarbonate resins are widely sold on the market, such as PANLITE (registered trademark) (Teijin Chemical Co., Ltd.), IUPILON (Registered trademark) (Mitsubishi Engineering Plastics (share)), SD POLYCA (registered trademark) (SUMITOMO DOW (share)), CALIBER (registered trademark) (Dow Chemical (share)), etc.

In addition to the above-mentioned thermoplastic resin, any suitable additives can be added to the base film. As such additives, for example, ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, coloring inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and coloring agents. The content of the thermoplastic resin exemplified above in the base film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the content of the thermoplastic resin in the base film is less than 50% by weight, the high transparency originally possessed by the thermoplastic resin may not be fully discovered.

The thickness of the base film before stretching can be appropriately determined, but generally from the operability point of strength, usability, etc., it is more preferably 1 to 500 μm, more preferably 1 to 300 μm, more preferably 5 to 200 μm, and most preferably 5 to 150 μm.

The base film may be subjected to corona treatment, plasma treatment, flame treatment, etc. at least on the surface on the side where the polyvinyl alcohol resin layer is formed in order to improve the adhesion with the resin layer composed of polyvinyl alcohol resin. In addition, in order to improve adhesion, a thin layer such as an undercoat layer may be formed on the surface of the base film on the side where the resin layer is formed. Especially in the stretching step (S50), when stretching at a stretching ratio of more than 5 times, the substrate film and the resin layer are liable to float and peel off. ideal.

[Undercoat]

The undercoat layer is not particularly limited as long as it can exert a certain strength adhesion between the base film and the polyvinyl alcohol-based resin layer. For example, a thermoplastic resin with excellent transparency, thermal stability, and extensibility is used. Specific examples include acrylic resins and polyvinyl alcohol resins, but not limited thereto.

The resin constituting the undercoat layer can be used in a state of being dissolved in a solvent. Depending on the solubility of the resin, aromatic hydrocarbons such as benzene, toluene, and xylene, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and esters such as ethyl acetate and isobutyl acetate can be used , Such as chlorinated hydrocarbons such as dichloroethylene, trichloroethylene, chloroform, ethanol, 1-propanol, 2-propanol, 1-butanol and other common organic solvents. However, when a solution containing an organic solvent is used to form an undercoat layer, the substrate is dissolved, and the solubility of the substrate is also taken into consideration, so it is preferable to select a solvent. When considering the impact on the environment, it is more ideal to form a primer layer with a coating solution using water as a solvent. Among them, it is desirable to use a polyvinyl alcohol-based resin with better adhesion.

The polyvinyl alcohol-based resin used as the undercoat layer includes, for example, polyvinyl alcohol resin and its derivatives. As derivatives of polyvinyl alcohol-based resins, in addition to polyvinyl formaldehyde, polyvinyl acetal, etc., for example, polyvinyl alcohol-based resins use unsaturated carboxylic acids such as olefins such as ethylene and propylene, acrylic acid, methacrylic acid, and 2-butenoic acid. Modified by acid, alkyl ester of unsaturated carboxylic acid, acrylamide, etc. Among the polyvinyl alcohol-based resin materials, it is preferable to use polyvinyl alcohol resin.

In order to increase the strength of the undercoat layer, a crosslinking agent may be added to the above thermoplastic resin. As the crosslinking agent added to the resin, conventional ones such as organic type and inorganic type can be used. The thermoplastic resin to be used may be selected more appropriately. For example, it is possible to select an epoxy-based, isocyanate-based, dialdehyde-based, or metal-based 联剂。 Joint agent. As the epoxy-based crosslinking agent, any one of the one-liquid curing type and the two-liquid curing type can be used. For example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylol Propylene triglycidyl ether, diglycidyl aniline, diglycidyl propylamine and other epoxy resins.

As the isocyanate-based crosslinking agent, for example, toluene diisocyanate, hydrogenated toluene diisocyanate, trimethylolpropane-toluene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis(4-phenyl)methane tris Isocyanates such as isocyanate, isophorone diisocyanate, and ketoxime block or phenol block of these.

Examples of the dialdehyde-based cross-linking agent include glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, maleic dialdehyde, and phthalaldehyde.

As the metal-based crosslinking agent, for example, metal salts, metal oxides, metal hydroxides, and organometallic compounds, the type of metal is not particularly limited, and may be appropriately selected. As metal salts, metal oxides, metal hydroxides, for example, sodium, potassium, magnesium, calcium, aluminum, iron, nickel, zirconium, titanium, silicon, boron, zinc, copper, vanadium, chromium, tin, etc. have a divalent or higher The salt of the valence metal and its oxide and hydroxide.

The so-called organometallic compound refers to a compound having a structure in which at least one metal atom directly bonds an organic group in a molecule, or bonds an organic group via an oxygen atom, a nitrogen atom, or the like. The organic group refers to a functional group containing at least a carbon element, such as an alkyl group, an alkoxy group, an acetyl group, and the like. In addition, the term "bonding" refers to not only covalent bonding, but also coordination bonding such as chelating compounds.

As a suitable example of the above metal organic compound, for example, titanium organic compound Compounds, zirconium organic compounds, aluminum organic compounds and silicon organic compounds. These metal organic compounds may be used alone, or two or more of them may be appropriately mixed and used.

As specific examples of the above-mentioned titanium organic compound, for example, tetra-n-butyl titanate, tetraisopropyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, tetramethyl titanate, etc. Titanium ortho esters; titanium acetone acetone, titanium tetraacetone acetone, titanium acetone acetone, titanium octadiolate, titanium lactate, titanium triethanolamine, titanium ethylacetate, etc. Titanium chelate compounds; titanium hydroxystearate and other titanium compounds.

Specific examples of the zirconium organic compound include, for example, zirconium n-propoxide, zirconium n-butoxide, zirconium tetraacetone, zirconium monoacetone, zirconium diacetone, zirconium diacetone, zirconium diethylacetate, and the like.

As specific examples of the above-mentioned aluminum organic compound, for example, acetylacetonate aluminum and aluminum organic acid chelate. As a specific example of the above-mentioned silicon organic compound, for example, a compound having a ligand exemplified by the above-mentioned titanium organic compound and zirconium organic compound.

In addition to the above-mentioned low-molecular cross-linking agent, a polymer-based cross-linking agent such as methylolated melamine resin, polyamide epoxy resin, or the like can be used. As such a commercially available product of polyamide epoxy resin, "SUMIREZ (registered trademark) RESIN 650 (30)" and "SUMIREZ (registered trademark) RESIN 675" sold by Sumitomo Chemtex Corporation (both are products) Name) etc.

In the case where a polyvinyl alcohol-based resin is used as a thermoplastic resin, polyamine epoxy resin, methylolated melamine, dialdehyde, metal chelate crosslinking agent, etc. are particularly desirable.

The ratio of the thermoplastic resin and the crosslinking agent used to form the undercoat layer ranges from 0.1 to 100 parts by weight of the crosslinking agent for 1 part by weight of the resin, depending on the type of resin, the type of crosslinking agent, etc. It may be appropriately determined, and it is particularly preferable to select from a range of 0.1 to 50 parts by weight. Furthermore, the coating liquid for an undercoat layer preferably has a solid content concentration of about 1 to 25% by weight.

The thickness of the undercoat layer is preferably 0.05 to 1 μm. More preferably, it is 0.1 to 0.4 μm. If it is thinner than 0.05 μm, the effect of improving the adhesion between the base film and the polyvinyl alcohol layer is small. If it is thicker than 1 μm, the polarizing plate becomes thicker, which is undesirable.

The coating method used for the formation of the undercoat layer is not particularly limited, and roller coating methods such as wire bar coating method, reverse coating method, and gravure coating method, slit coating method, and corner wheel coating method can be used. Common methods such as comma coating, lip coating, spin coating, screen coating, fountain coating, dip coating, spray coating, etc. Appropriately choose to adopt.

(Resin layer)

As the polyvinyl alcohol resin used in the resin layer, a saponified polyvinyl acetate resin can be used. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate which is a separate polymer of vinyl acetate, for example, a copolymer of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having ammonium groups.

Polyvinyl alcohol-based resin, ideally using completely saponified products. Saponification A range of 80.0 mol% to 100.0 mol% is more desirable, a range of 90.0 mol% to 99.5 mol% is more ideal, and a range of 94.0 mol% to 99.0 mol% is more ideal. When the degree of saponification is less than 80.0 mol%, the water resistance, humidity resistance and heat resistance after the formation of the polarizing layer are significantly deteriorated.

The saponification degree here refers to the ratio of the acetic acid group contained in the polyvinyl acetate resin of the raw material of the polyvinyl alcohol resin by the saponification step, expressed in unit ratio (mol %), as shown in the following formula Defined value. It can be obtained according to the method specified in JIS K 6726 (1994).

Saponification degree (mol%) = (number of hydroxyl groups) ÷ (number of hydroxyl groups + number of acetate groups) × 100

The higher the degree of saponification, the higher the proportion of hydroxyl groups, that is, the lower the proportion of acetic acid groups that hinder crystallization.

Moreover, the polyvinyl alcohol-based resin may be a partly modified polyvinyl alcohol. For example, polyvinyl alcohol resins are modified with olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and 2-butenoic acid, alkyl esters of unsaturated carboxylic acids, and acrylic amides. The proportion of modification is less than 30 mol% is ideal, less than 10% is more ideal. In the case where the modification exceeds 30 mol%, the absorption of the dichroic pigment is difficult, resulting in a bad situation in which the polarization performance is reduced.

The average degree of polymerization of the polyvinyl alcohol-based resin is not particularly limited, but it is preferably 100 to 10,000, more preferably 1500 to 8000, and even more preferably 2000 to 5000. Here, the average degree of polymerization is a value determined according to the method specified in JIS K 6726 (1994).

As the polyvinyl alcohol resin having such characteristics, for example, PVA124 (saponification degree: 98.0 to 99.0 mol%) manufactured by Kurarav, PVA117 (Degree of saponification: 98.0 to 99.0 mol%), PVA624 (degree of saponification: 95.0 to 96.0 mol%), and PVA617 (degree of saponification: 94.5 to 95.5 mol%), etc.; for example, AH-made by Japan Synthetic Chemical Industry Co., Ltd. 26 (degree of saponification: 97.0 to 98.8 mol%), AH-22 (degree of saponification: 97.5 to 98.5 mol%), NH-18 (degree of saponification: 98.0 to 99.0 mol%), and N-300 (degree of saponification: 98.0 to 99.0 mol%), etc.; Japan VAM&POVAL (share) JC-33 (saponification degree: 99.0 mol% or more), JM-33 (saponification degree: 93.5 to 95.5 mol%), JM-26 (saponification degree: 95.5 to 97.5 mol%), JP-45 (saponification degree: 86.5 to 89.5 mol%), JF-17 (saponification degree: 98.0 to 99.0 mol%), JF-17L (saponification degree: 98.0 to 99.0 mol) %) and JF-20 (saponification degree: 98.0 to 99.0 mol %), etc., these can be suitably used for the formation of the polyvinyl alcohol-based resin film of the present invention.

To the polyvinyl alcohol-based resin, additives such as plasticizers and surfactants may be added as needed. As the plasticizer, polyalcohol and its condensate, etc., for example, glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, polyethylene glycol and the like can be used. The amount of additives to be blended is not particularly limited, and it is preferably 20% by weight or less in the polyvinyl alcohol-based resin.

The thickness of the resin layer is preferably more than 3 μm and less than 30 μm, and more preferably 5 to 20 μm. If it is 3 μm or less, it becomes too thin after stretching, and the dyeability is significantly deteriorated. If it exceeds 30 μm, the thickness of the polarizing layer finally obtained exceeds 10 μm, which is undesirable.

The resin layer of the present invention is preferably a polyvinyl alcohol-based resin solution obtained by dissolving a powder of a polyvinyl alcohol-based resin in a good solvent, coated on the surface of one side of the substrate film, and evaporating the solvent by drying form. By such as This forms a resin layer, possibly forming a thin resin layer. As a method of applying the polyvinyl alcohol-based resin solution to the base film, for example, a roller coating method such as a wire bar coating method, a reverse coating method, a gravure coating method, a slit coating method, and a corner wheel can be used Known methods such as the coating method, the lip coating method, the spin coating method, the screen coating method, the spray coating method, the dip coating method, and the spray coating method are appropriately selected and adopted. The drying temperature is, for example, 50 to 200°C, and more preferably 60 to 150°C. The drying time is, for example, 2 to 20 minutes.

In addition, the resin layer of the present invention can be formed by bonding a raw material film composed of a polyvinyl alcohol-based resin to one surface of the base film.

<Extended Step (S20)>

Here, the laminated film composed of the base film and the polyvinyl alcohol-based resin layer is stretched to obtain a stretched film. Preferably, it is one-axis extension with an extension ratio of more than 5 times and less than 17 times. More desirably, it is a one-axis extension with an extension ratio of more than 5 times and less than 8 times. When the stretching magnification is 5 times or less, the resin layer composed of the polyvinyl alcohol-based resin cannot be sufficiently aligned, and as a result, the polarization degree of the polarizing layer cannot be sufficiently increased. On the other hand, when the stretch ratio exceeds 17 times, the laminated film is likely to break during stretching, and the thickness of the stretched film is thinner than necessary, which may reduce the workability/operability in the subsequent steps. The extension processing in the extension step (S20) is not limited to one-stage extension, and may be performed in multiple stages. In the case of performing multi-stage stretching, all stages of the stretching process are combined to perform an stretching process with a stretching ratio of more than 5 times.

In the stretching step (S20) of this embodiment, the longitudinal direction of the longitudinal direction of the laminated film and the lateral direction of the width direction can be implemented Extended processing, etc.

As a longitudinal stretching method, for example, a method of stretching between rollers, a method of compressive stretching, etc., and as a transverse stretching method, for example, a tenter method. Furthermore, it is not limited to uniaxial extension, but may be biaxial extension. In the case of uniaxial extension, it can be either fixed end extension or free end extension.

In addition, any one of the wet-stretching method and the dry-stretching method can be used for the stretching process. However, if the dry-stretching method is used, the temperature when the laminated film is stretched can be selected from a wide range, which is preferable.

<Dyeing Step (S30)>

Here, the resin layer of the stretched film is dyed with a dichroic pigment. Examples of dichroic dyes include iodine and organic dyes. As the organic dye, for example, red BR, red LR, red R, pink LB, ruby red BL, red wine (bordeaux) GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy blue RY, Green LG, Purple LB, Purple B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Super Blue G, Super Blue GL, Super Orange GL, Direct Sky Blue, Direct Lightfast Orange S, Kuraku Black, etc. These dichroic substances may be used alone or in combination of two or more.

The dyeing step is performed, for example, by dipping the entire stretched film in a solution (dyeing solution) containing the dichroic dye. As the dyeing solution, a solution in which the above dichroic dye is dissolved in a solvent can be used. As the solvent of the dyeing solution, water is generally used, and an organic solvent having compatibility with water may be further added. The concentration of the dichroic pigment is preferably 0.01 to 10% by weight, more Ideally it is 0.02 to 7% by weight, particularly preferably 0.025 to 5% by weight.

In the case of using iodine as a dichroic pigment, since the dyeing efficiency can be further improved, it is desirable to add iodide. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. The addition ratio of these iodides to the dyeing solution is preferably 0.01 to 20% by weight. Among iodide, potassium iodide is ideal. In the case of adding potassium iodide, the ratio of iodine to potassium iodide is more preferably in the range of 1:5 to 1:100, more preferably in the range of 1:6 to 1:80, and particularly preferably in the range of 1:7 to 1 by weight ratio. : 70 range.

The immersion time of the stretched film in the dyeing solution is not particularly limited, but it is usually in the range of 15 seconds to 15 minutes, and more preferably in the range of 30 seconds to 3 minutes. Moreover, the temperature of the dyeing solution is preferably in the range of 10 to 60°C, and more preferably in the range of 20 to 40°C.

In the dyeing step, after dyeing, cross-linking treatment can be performed. The cross-linking treatment can be performed, for example, by dipping the stretched film in a solution (cross-linking solution) containing a cross-linking agent. As the crosslinking agent, conventionally known substances can be used. For example, boron compounds such as boric acid and borax, glyoxal, glutaraldehyde, etc. One of these may be used, and two or more may be used in combination.

As the cross-linking solution, a solution in which a cross-linking agent is dissolved in a solvent can be used. As the solvent, for example, water can be used, and an organic solvent having compatibility with water can be further included. The concentration of the cross-linking agent of the cross-linking solution is not particularly limited, but it is preferably in the range of 1 to 20% by weight, and more preferably in the range of 6 to 15% by weight.

In the cross-linking solution, iodide can be added. By adding iodide, the in-plane polarization characteristics of the resin layer can be more uniform. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. The content of iodide is 0.05 to 15% by weight, more preferably 0.5 to 8% by weight.

The dipping time of the stretched film to the cross-linking solution is usually preferably 15 seconds to 20 minutes, and more preferably 30 seconds to 15 minutes. Furthermore, the temperature of the cross-linking solution is preferably in the range of 10 to 90°C.

Finally, it is ideal to perform a washing step and a drying step. As a washing step, water washing treatment can be performed. The water washing treatment is usually performed by immersing the stretched film in pure water such as ion-exchanged water or distilled water. The water washing temperature is usually 3 to 50°C, more preferably 4 to 20°C. The dipping time is usually 2 to 300 seconds, more preferably 3 seconds to 240 seconds.

The washing step can be combined with the washing treatment of the iodide solution and the washing treatment with water, and a solution prepared by mixing liquid alcohols such as methanol, ethanol, isopropanol, butanol, and propanol can be suitably used.

After the washing step, the drying step is ideal. As the drying step, any suitable method (for example, natural drying, air drying, heat drying) can be used. For example, in the case of heat drying, the drying temperature is usually 20 to 95°C, and the drying time is usually about 1 to 15 minutes. Through the above dyeing step (S30), the resin layer can have a function of polarizing light. In this specification, a resin layer having a function of polarizing light is called a polarizing layer, and a laminate having a polarizing layer on a base film is called a polarizing laminated film.

(Polarizing layer)

The polarizing layer, specifically, a uniaxially extending polyvinyl alcohol-based resin layer absorbs the alignment dichroic dye.

The thickness of the polarizing layer (thickness of the extended polyvinyl alcohol-based resin layer) is preferably 15 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less. When the thickness of the polarizing layer is 10 μm or less, a thin polarizing laminate film can be formed.

<Laminating step (S40)>

Here, a protective film is bonded to the surface opposite to the surface of the polarizing layer of the polarizing laminate film on the side of the base material film to obtain a multilayer film. As a method of bonding the protective film, for example, a method of bonding the polarizing layer and the protective film with an adhesive, and a method of bonding the polarizing layer and the protective film with an adhesive. After the bonding step (S40), the polarizing plate is formed through the above-mentioned peeling step (S50).

(Protection film)

The protective film may be a simple protective film having no optical function, or may be a protective film having both optical functions of a so-called retardation film and brightness enhancement film.

The material of the protective film is not particularly limited, for example, a cyclic polyolefin-based resin film, such as a triacetyl acetyl cellulose, diethyl acetyl cellulose resin composed of cellulose acetate-based resin film, such as polyethylene terephthalate Polyester-based resin films, polycarbonate-based resin films, acrylic-based resin films, polypropylene-based resin films made of resins of diesters, polyethylene naphthalate, and polybutylene terephthalate, for example A film widely used in this field.

As the cyclic polyolefin resin film, suitable commercially available products such as Topas (registered trademark) (manufactured by Ticona), Arton (registered trademark) (manufactured by JSR), and ZEONOR (registered trademark) (NEON (Japan) share) System), ZEONEX (registered trademark) (Japan NEON Co., Ltd.), APL (registered trademark) (Mitsui Chemical Co., Ltd.). When such a cyclic polyolefin resin film is formed into a thin film, conventional methods such as a solvent casting method and a melt extrusion method can be suitably used. In addition, pre-made film rings such as Escena (registered trademark) (manufactured by Sekisui Chemical Industry Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Industry Co., Ltd.), and ZEONOR (registered trademark) film (manufactured by Japan Optes (company)) can be used. Commercial product of thin polyolefin resin film.

The cyclic polyolefin resin film may be uniaxially stretched or biaxially stretched. By stretching, the cyclic polyolefin resin film can be given an arbitrary phase difference value. Stretching is usually carried out continuously while rolling out the film roll, and extends in the heating furnace in the direction of travel of the roll, the direction perpendicular to the direction of travel, or both. The temperature of the heating furnace generally ranges from the vicinity of the glass transition temperature of the cyclic polyolefin resin film to the glass transition temperature +100°C. The stretch magnification is usually 1.1 to 6 times in each direction, more preferably 1.1 to 3.5 times.

As the cellulose acetate-based resin film, suitable commercially available products can be suitably used, for example, Fujitac (registered trademark) TD80 (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UF (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) Registered trademark) TD80UZ (Fuji Film Co., Ltd.), Fujitac (registered trademark) TD40UZ (Fuji Film Co., Ltd.), KC8UX2M (Konica Minolta Co., Ltd.), KC4UY (Konica Minolta (Co., Ltd.) ) System) etc.

On the surface of the cellulose acetate resin film, in order to improve the viewing angle characteristics, a liquid crystal layer or the like can be formed. Furthermore, in order to impart a phase difference, the cellulose acetate resin film may be stretched. Cellulose acetate resin film High adhesion to the polarizing layer, usually saponification treatment. As the saponification treatment, for example, a method of dipping in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide can be used.

An optical layer such as a hard coat layer, an anti-glare layer, and an anti-reflection layer can be formed on the surface of the protective film. The method of forming these optical layers on the surface of the protective film is not particularly limited, and a conventional method can be used.

The thickness of the protective film is required to be thinner, and the thinnest possible is more desirable, 90 μm or less is more desirable, and 50 μm or less is more desirable. Conversely, when it is too thin, the strength decreases, and the workability deteriorates, so 5 μm or more is preferable.

(Adhesive layer)

Adhesives constituting the adhesive layer usually use acrylic resin, styrene resin, polysiloxane resin, etc. as the matrix polymer, to which is added crosslinking of isocyanate compound, epoxy compound, aziridine, etc. The composition of the agent. Furthermore, mixing fine particles in the adhesive can form an adhesive layer that exhibits light scattering properties.

The thickness of the adhesive layer is preferably 1 to 40 μm. In the range of the characteristics that do not impair workability and durability, thin coating is more ideal, and more preferably 3 to 25 μm. When it is 3 to 25 μm, it can have good processability and suppress the dimensional change of the polarizing film, and is an appropriate thickness. When the adhesive layer is less than 1 μm, the adhesiveness is lowered, and when it exceeds 40 μm, defects such as sticking out of the adhesive are likely to occur.

The method of forming the adhesive layer on the polarizing layer or the protective film is not particularly limited, and a solution containing each component represented by the above matrix polymer can be coated on the polarizing layer or the protective film, and dried to form After the adhesive layer, it can be attached to the separator and other kinds of films. After forming the adhesive layer on the separator, It is laminated on the surface of the polarizing layer or the surface of the protective film. In addition, when forming the adhesive layer on the polarizing layer or the protective film, if necessary, the surface of the polarizing layer or the protective film, or one or both sides of the adhesive may be subjected to adhesion treatment, such as corona treatment.

(Adhesive layer)

As the adhesive constituting the adhesive layer, for example, an aqueous adhesive such as a polyvinyl alcohol-based resin aqueous solution or an aqueous two-component urethane-based emulsified adhesive is used. Among them, a polyvinyl alcohol-based resin aqueous solution is suitably used. For the use of polyvinyl alcohol resin as a bonding agent, in addition to the homopolymer of vinyl alcohol obtained by the saponification of polyvinyl acetate as a separate polymer of vinyl acetate, vinyl acetate and other monomers copolymerizable therewith The vinyl alcohol-based copolymer obtained by saponification of the copolymer, and the modified polyvinyl alcohol-based polymers whose hydroxyl groups are partially modified. To the water-based bonding agent, polyvalent aldehyde, water-soluble epoxy compound, melamine-based compound, zirconia compound, zinc compound, etc. may be added as additives. In the case of using such an aqueous cement, the cement layer obtained from it is usually thinner than 1 μm, and the cross-section is observed under a normal optical microscope, and the cement layer cannot be seen in practice.

The bonding method of the film using the water-based bonding agent is not particularly limited. For example, the bonding agent is evenly coated or run down on the surface of the polarizing layer or the protective film, and another film is laminated on the coated surface, and bonded by a roller, etc. Drying method, etc. Generally, the bonding agent is applied at a temperature of 15 to 40°C after preparation, and the bonding temperature is usually in the range of 15 to 30°C.

In the case of using a water-based bonding agent, after the film is bonded, it is dried to remove water contained in the water-based bonding agent. The temperature of the drying furnace is ideal 30 to 90°C. When the temperature is less than 30°C, the joint surface tends to be easily peeled off. At 90°C or higher, the optical performance may deteriorate due to heat. The drying time may be 10 to 1000 seconds.

After drying, it is cured at room temperature or a slightly higher temperature, for example, at a temperature of about 20 to 45°C for about 12 to 600 hours. The temperature during curing is generally set to be lower than the temperature used during drying.

In addition, as the non-aqueous adhesive, a photocurable adhesive can be used. As the photocurable adhesive, for example, a mixture of a photocurable epoxy resin and a photocationic polymerization initiator.

As a method of bonding films with a photocurable adhesive. Traditionally known methods can be used, for example, by casting, Mayer bar, gravure coating, notch coating, blade coating, slit coating, dip coating Method, spraying method, etc., a method of applying a bonding agent on the bonding surface of the film and overlapping two films. The so-called flow casting method refers to a method in which two films of a coated object are moved in a vertical direction, a horizontal direction, or an oblique direction therebetween, and a bonding agent is flowed down on the surface and diffused.

After applying the bonding agent to the surface of the polarizing layer or the protective film, the polarizing lamination film and the protective film are pinched and bonded together with a nip roller. Furthermore, a method of uniformly pressing and spreading the laminate with a roller or the like can be suitably used. In this case, as the material of the roller, metal, rubber, or the like can be used. In addition, it is preferable to adopt the method of passing the laminate between the rollers and the rollers under pressure and diffusion. In this case, the rollers can be the same material or different materials. The thickness of the adhesive layer after being bonded by using the above-mentioned nip rollers before drying or hardening is preferably 5 μm or less and 0.01 μm or more.

In order to improve the bonding property, the surface of the bonding surface of the polarizing layer and the protective film may be appropriately subjected to plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, saponification treatment and other surface treatments. As the saponification treatment, for example, a method of dipping in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide is used.

In the case of using a photo-curable resin as an adhesive, after the film is laminated, the photo-curable adhesive is cured by irradiating active energy rays. The light source of the active energy line is not particularly limited. The active energy line with a luminous distribution below 400 nm is ideal. Specifically, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, chemical lamps, black light lamps, and microwave excitation are used. Mercury lamps, metal halide lamps, etc.

The light irradiation intensity of the light-curing adhesive is appropriately determined according to the composition of the light-curing adhesive, and is not particularly limited. The irradiation intensity in the wavelength region in which the activation of the polymerization initiator is effective is preferably 0.1 to 6000 mW/cm ² . When the irradiation intensity is 0.1 mW/cm ² or more, the reaction time does not become too long. When it is 6000 mW/cm ² or less, the heat radiated from the light source and the heat generated when the photocurable adhesive is cured The yellowing of the oxygen resin and the deterioration of the polarizing film are less likely to occur. The light irradiation time for the light-curing adhesive is applicable according to the cured light-curing adhesive, and is not particularly limited. It means that the cumulative light amount as a product of the above-mentioned irradiation intensity and irradiation time is preferably set to 10 to 10000 mJ/cm ² . In the case where the accumulated light amount to the photo-curable adhesive is 10 mJ/cm ² or more, reactive species from the polymerization initiator are sufficiently generated to allow the hardening reaction to proceed more reliably. In the case of 10000 mJ/cm ² or less, The reaction time does not become too long, and good productivity can be maintained. In addition, the thickness of the adhesive layer after irradiation with active energy rays is usually 0.001 to 5 μm, preferably 0.01 μm or more and 2 μm or less, and more preferably 0.01 μm or more and 1 μm or less.

In the case where the photocurable adhesive on the polarizing layer and the protective film is cured by irradiating active energy rays, the functions of the polarizing plate after all steps of the transmittance, hue, transparency, etc. of these films are not reduced Hardening under conditions is ideal.

(Resin laminated film on both sides)

In the manufacturing method of the present invention, the formation of the resin layer in the resin layer forming step (S10) is not limited to the case where it is formed on one surface of the base film, but also includes the case where it is formed on both surfaces of the base film. When resin layers are formed on both surfaces of the base film, two polarizing plates are formed through the steps S10 to S50. In this case, through the bonding step (S40), a multilayer film composed of the first protective film/first polarizing layer/base film/second polarizing layer/second protective film is obtained.

In the case of forming resin layers on both surfaces of the base film, the so-called peeling step (S50) of peeling the base film from the multilayer film to obtain a polarizing plate means that the multilayer film is formed between the first polarizing layer and the base film The first peeling step that separates by peeling, and the multilayer film composed of the separated base film/second polarizing layer/second protective film is between the base film and the second polarizing layer by The second peeling step of peeling and separating. In the first peeling step, the first polarizing plate is formed, and in the second peeling step, the second polarizing plate is formed.

The angle θ formed by the peeling direction of the substrate film (arrow B) and the alignment direction of the polarizing layer (arrow A) refers to the peeling direction of the substrate film in the first peeling step (that is, the substrate film/second The angle between the direction of peeling of the laminate composed of the polarizing layer/the second protective film) and the orientation direction of the first polarizing layer means, in the second peeling step, the peeling direction of the base film and the orientation of the second polarizing layer The angle formed by the direction. Therefore, the condition of the angle θ is as described above.

p，於第1剝離步驟，係指多層膜(亦即第1保護膜/第1偏光層/基材薄膜/第2偏光層/第2保護膜所構成的積層體)與第1偏光板(亦即第1偏光層/第1保護膜所構成的積層體)所成的角度，於第2剝離步驟，係指多層膜(亦即基材薄膜/第2偏光層/第2保護膜所構成的積層體)與第2偏光板(亦即第2偏光層/第2保護膜所構成的積層體)所成的角度。再者，在剝離點，多層膜與基材薄膜所成的角度

k，於第1剝離步驟，係指多層膜(亦即第1保護膜/第1偏光層/基材薄膜/第2偏光層/第2保護膜所構成的積層體)與基材薄膜(亦即基材薄膜/第2偏光層/第2保護膜所構成的積層體)所成的角度，於第2剝離步驟，係指多層膜(亦即基材薄膜/第2偏光層/第2保護膜所構成的積層體)與基材薄膜所成的角度。於是，角度

p、

k的條件如上述。 Moreover, at the peeling point, the angle formed by the multilayer film and the polarizer

p, in the first peeling step, refers to the multilayer film (that is, the layered body composed of the first protective film/first polarizing layer/base film/second polarizing layer/second protective film) and the first polarizing plate ( That is, the angle formed by the first polarizing layer/first protective film) in the second peeling step refers to the multilayer film (that is, the base film/second polarizing layer/second protective film) The angle between the second polarizer (that is, the second polarizer/the second protective film). Furthermore, at the peeling point, the angle formed by the multilayer film and the substrate film

k, in the first peeling step, it refers to the multilayer film (that is, the laminate of the first protective film/first polarizing layer/substrate film/second polarizing layer/second protective film) and the substrate film (also That is, the angle formed by the base film/second polarizing layer/second protective film) refers to the multilayer film (ie, base film/second polarizing layer/second protection) in the second peeling step The angle formed by the laminate formed by the film and the base film. Thus, the angle

p,

The condition of k is as described above.

(Other optical layers)

The above-mentioned polarizing plate can be used as a polarizing plate by stacking other optical layers in practical use.

Furthermore, the protective film may have the functions of these optical layers.

As an example of other optical layers, for example, a reflective polarizing film that transmits light of a certain polarized light, reflects light that shows polarized light of the opposite nature, and has a surface Concavo-convex shape film with anti-glare function, film with surface anti-reflection function, reflection film with reflection function on the surface, semi-transmissive reflection film with reflection function and transmission function, viewing angle compensation film.

A commercially available product of a reflective polarizing film equivalent to light passing through a certain polarized light and reflecting polarized light of the opposite nature, such as DBEF (manufactured by 3M Corporation, available from Sumitomo 3M Co., Ltd.), APF (3M Corporation System, available from Sumitomo 3M (shares), etc. As the viewing angle compensation film, for example, a liquid crystal compound is coated on the surface of the substrate, an optical compensation film for alignment, a retardation film made of polycarbonate-based resin, and a retardation film made of cyclic polyolefin-based resin. As a commercially available product corresponding to an optical compensation film coated with a liquid crystal compound on the surface of a substrate and aligned, for example, WV film (manufactured by Fuji Film Co., Ltd.), NH film (manufactured by New Japan Petroleum Co., Ltd.), NR film (New Japan Petroleum Corporation) etc. Moreover, as a commercially available product equivalent to a phase difference film composed of a cyclic polyolefin resin, for example, Arton (registered trademark) film (manufactured by JSR Corporation), Escena (registered trademark) (manufactured by Sekisui Chemical Industry Co., Ltd.), ZEONOR (registered trademark) film (Optes (stock) system), etc.

[Example] [Manufacture of polarizing plates of Examples 1 to 10 and Comparative Examples 1 to 6] <Fabrication of substrate film>

Separate polymer of propylene is placed on both sides of the resin layer composed of a random copolymer of propylene/ethylene containing about 5 wt% of ethylene units (Sumitomo Chemical Co., Ltd. "Sumitomo Noprene W151", melting point Tm=138°C) Multi-component polypropylene (Sumitomo Chemical Co., Ltd. "Sumitomo Noprene FLX80E4", melting point Tm = 163 ℃) resin layer consisting of a three-layer structure of the base film, the use of many The layer extrusion molding machine is produced by co-extrusion molding. The total thickness of the obtained base film was 90 μm, and the thickness ratio of each layer (FLX80E4/W151/FLX80E4) was 3/4/3.

<Formation of primer layer>

Polyvinyl alcohol powder ("Z-200" manufactured by Japan Synthetic Chemical Industry Co., Ltd., average polymerization degree 1100, average saponification degree 99.5 mol%) was dissolved in hot water at 95°C, and a polyvinyl alcohol aqueous solution with a concentration of 3% by weight was prepared . The obtained aqueous solution was mixed with 5 parts by weight of a cross-linking agent ("SUMIREZ RESIN 650" manufactured by Sumitomo Chemical Co., Ltd.) for 6 parts by weight of polyvinyl alcohol powder. The resulting mixed aqueous solution was cut into a corona-treated surface of the above-mentioned substrate film subjected to corona treatment after being cut into a size of 25 cm×35 cm, and coated with a desktop bar coater, and dried at 80° C. for 10 minutes to form a thickness. Undercoat layer of 0.2μm.

<Step of forming resin layer (S10)>

Polyvinyl alcohol powder ("PVA124" manufactured by Kuraray Co., Ltd., average degree of polymerization 2400, average degree of saponification 98.0 to 99.0 mol%) was dissolved in hot water at 95°C, and a polyvinyl alcohol aqueous solution with a concentration of 8% by weight was prepared. The obtained aqueous solution was coated on the above-mentioned undercoat layer with a desktop bar coater, and dried at 80° C. for 5 minutes to produce three layers consisting of a base film/undercoat layer/polyvinyl alcohol-based resin layer Structured laminated film. The thickness of the polyvinyl alcohol-based resin layer is 9.8 μm.

<Extended Step (S20)>

The end of the uncoated polyvinyl alcohol-based resin was cut from the film to obtain a laminated film having a width of 18 cm and a length of 30 cm. The laminated film was stretched by a tenter stretching device at a stretching temperature of 160°C and 5.8 times in the width direction. Extend from one axis of the end to obtain an extended film. The thickness of the obtained stretched film was 45.5 μm, and the thickness of the polyvinyl alcohol-based resin layer was 4.2 μm.

<Dyeing Step (S30)>

The central portion of the stretched film was cut out by 10 cm×10 cm, and the polarized stretched film was produced in the following procedure. First, the stretched film is immersed in a 30°C dyeing solution containing an aqueous solution of iodine and potassium iodide at 30°C, immersed for about 150 seconds to dye the polyvinyl alcohol-based resin layer, and then rinse the excess iodine solution with pure water at 10°C . Then, it is immersed in a 76°C cross-linking solution containing an aqueous solution of boric acid and potassium iodide for about 600 seconds. Then, it was washed with pure water at 10°C for 4 seconds, and finally, dried at 80°C for 300 seconds to form a polarizing layer, thereby obtaining a 10 cm square polarizing laminated film.

<Laminating step (S40)>

For the polarizing laminated film, the protective film is bonded in the following procedure. First, a polyvinyl alcohol powder ("KL-318" manufactured by Kuraray Co., Ltd., average polymerization degree 1800) was dissolved in hot water at 95°C to prepare a 3% by weight aqueous solution of polyvinyl alcohol. The obtained aqueous solution was mixed with 1 part by weight of 2 parts by weight of polyvinyl alcohol powder ("SUMIREZ RESIN 650" manufactured by Sumitomo Chemical Co., Ltd.) as a bonding agent solution.

Then, on the polarizing layer of the polarizing laminate film, after applying the above-mentioned binder solution, a protective film composed of triacetyl cellulose (TAC) (Konica Minolta Optical Co., Ltd. "KC4UY") was bonded. To obtain a multilayer film composed of 5 layers of protective film/adhesive layer/polarizing layer/undercoat layer/base film.

<Peeling Step (S50)>

p、多層膜與基材薄膜所成的角度

k，以下述表1所示的數值實施。再者，於剝離點，於角度

p及角度

k皆不為0度的情況，對多層膜而言基材薄膜與偏光板，在相反側具有一角度進行剝離。 The end of the obtained 10 cm square multilayer film was cut off to obtain an 8 cm square multilayer film. The base film was peeled from the 8 cm square multilayer film, and a polarizing plate composed of four layers of protective film/adhesive layer/polarizing layer/undercoat layer was produced. At this time, the angle θ formed by the peeling direction of the base film (arrow B) and the alignment direction of the polarizing layer (arrow A), and the angle formed by the multilayer film and the polarizing plate

p. The angle formed by the multilayer film and the substrate film

k, implemented with the numerical values shown in Table 1 below. Furthermore, at the peeling point, at the angle

p and angle

When neither k is 0 degrees, for the multilayer film, the base film and the polarizing plate are peeled off at an angle on the opposite side.

[Evaluation of polarizing plates of Examples 1 to 10 and Comparative Examples 1 to 6]

The "state of peeling surface" and "stability of peeling" of each polarizing plate produced as mentioned above were evaluated. The evaluation results are shown in Table 1 below. In addition, the "peeling stability" refers to an evaluation in which the peeling of the base film can be performed stably. Although there is no cohesive failure, it is known as zippering. The stability at the time of stripping cannot be obtained. In the case of a seam shape, the peeling force during peeling repeatedly increases and decreases slightly, causing the peeling point to change back and forth, causing a problem of unstable peeling angle.

10‧‧‧Multilayer film

11‧‧‧ Base film

12‧‧‧ Polarizer

A, B‧‧‧arrow

C‧‧‧Peeling point

k、

p‧‧‧角度 θ,

k,

p‧‧‧Angle

S10, S20, S30, S40, S50

FIG. 1 is a flowchart showing an embodiment of the method of manufacturing a polarizing plate of the present invention.

FIG. 2 is a schematic top view of the model showing the relationship between the peeling direction of the base film and the alignment direction of the polarizing layer.

Fig. 3 is a schematic top view of a model showing a preferred example of the peeling direction in the peeling step of the present invention.

Fig. 4 is a schematic top view of the model showing the relationship between the angle formed by the multilayer film and the polarizing plate and the angle formed by the multilayer film and the base film.

Fig. 5 is a schematic top view of a model showing a preferred example of the peeling angle regarding the peeling step of the present invention.

Method for manufacturing polarizing plate

10‧‧‧Multilayer film

11‧‧‧ Base film

12‧‧‧ Polarizer

A, B‧‧‧arrow

C‧‧‧Peeling point

θ ‧‧‧ Angle

Claims (3)

A method of manufacturing a polarizing plate, comprising: forming a polyvinyl alcohol-based resin layer having a thickness of more than 3 μm and less than 30 μm on at least one surface of a base film having a thickness of 5 to 200 μm, and a resin layer forming step to obtain a laminated film ; Extend the laminated film uniaxially in the transverse direction to obtain the stretching step of the stretched film; the polyvinyl alcohol-based resin layer of the stretched film is dyed with a dichroic dye to form a polarizing layer, and a dyeing step to obtain a polarized laminated film; The step of bonding the protective film to obtain a multilayer film; and the step of peeling off the base film from the multilayer film to obtain a polarizing plate; wherein, In the peeling step, the angle formed by the peeling direction of the base film and the alignment direction of the polarizing layer is 20 degrees or less. The method for manufacturing a polarizing plate as described in item 1 of the patent application range, wherein at the peeling step, at the peeling point, the angle formed by the multilayer film and the polarizing plate is greater than that formed by the multilayer film and the substrate film The angle is small. The method for manufacturing a polarizing plate as described in item 2 of the patent application range, wherein in the peeling step, at the peeling point, the angle formed by the multilayer film and the polarizing plate is 45 degrees or less.

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