JP2011118088A - Long polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a long polarizing plate which is suitable for enhancing the contrast of a liquid crystal display panel, and in which the deformation of the polarizing plate is prevented during storage or transportation while keeping clear property and the occurrence of the deterioration of contrast is prevented. <P>SOLUTION: In the long polarizing plate, a polarizing film is inserted between a hard coat film and an optical compensation film, and furthermore, a protective film is laminated on the surface of the hard coat film and is wound in a roll-like state. The hard coat film has a hard coat layer, containing a compound obtained by curing an ultraviolet curing type resin which is 300 to 700 mPa in viscosity at 25°C, on a base material film and is 2 to 20 nm in arithmetic average surface roughness Ra (JIS B0601:2001). The optical compensation film contains at least cellulose acetate propionate and an ester compound, which in turn has equal to or above one and equal to or below 12 of at least one pyranose structure or furanose structure and is formed by esterifying all or a part of OH group of the structures. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a long polarizing plate and a liquid crystal display device.

  In general, two polarizing plates are bonded to a liquid crystal cell constituting a liquid crystal display panel of a liquid crystal display device (LCD). This polarizing plate is composed of two cellulose-based protective films, each of which is a polarizing element (polarizing film) in which a polyvinyl alcohol (hereinafter abbreviated as PVA) film adsorbed and dyed with iodine or a dichroic dye is oriented in a certain direction. It has a three-layer structure sandwiched between.

  On one surface of the polarizing plate used in the liquid crystal cell, a hard coat film in which a hard coat layer is provided on a base material of a cellulose-based protective film is used in order to prevent physical damage. . In particular, the hard coat film is required to be a clear type rather than an anti-glare treatment type that blurs the outline of the image reflected on the surface from the viewpoint of higher contrast and visibility (clearness).

  In addition, a cellulose ester film having not only a function of a polarizing plate protective film but also a phase difference function is mounted on the surface of the polarizing plate opposite to the hard coat film. Typical examples include a film in which a so-called retardation increasing agent is added to a cellulose ester resin to develop a phase difference, and optical compensation using a mixed fatty acid ester of cellulose such as cellulose acetate propionate as a cellulose ester resin. There are films (for example, Patent Documents 1 and 2).

  On the other hand, in recent years, liquid crystal display panels have been improved in contrast, and studies have been made on improving contrast in each member such as polarizing plates, color filters, and backlights. When this member is used, a new problem is observed.

  For example, when manufacturing a long polarizing plate, it is carried out while tying a protective film such as a polyester film so as not to be scratched during storage or transportation. In addition, it has been found that when the protective film and the hard coat film are brought into close contact with each other during transportation or the like, the contrast of the liquid crystal display device using the polarizing plate in the non-adhered portion is lowered. This is not a problem in the case of a liquid crystal display device having a relatively low contrast. Recently, liquid crystal display devices using a direct type backlight (LED method) have been put on the market, and the above unevenness of contrast has become more conspicuous.

  As a result of earnest analysis of the phenomenon by the present inventors, when partial adhesion due to the blocking or the like occurs, stress concentrates on the non-adhered part and the entire polarizing plate of the part is deformed, and the hard coat film and Has found that the optical compensation film on the opposite side is distorted, resulting in an increase in internal scattering of the optical compensation film and a decrease in contrast. In particular, when a long polarizing plate is stored under high temperature and high humidity for a long time, the deformation failure is likely to occur partially due to blocking or the like.

  Patent Document 3 discloses a coating film containing at least one organic component having a polymerizable functional group, inorganic ultrafine particles, and inorganic and / or organic fine particles having a primary particle size larger than the primary particle size of the inorganic ultrafine particles. A technique for preventing blocking of a hard coat film by a hard coat film formed from components is disclosed. However, if a large amount of fine particles are added to the hard coat layer in order to prevent blocking sufficiently, the haze is likely to increase, maintaining the clearness and preventing the deformation of the polarizing plate, which is the subject of the present invention, and preventing the decrease in contrast. It was difficult to achieve both purposes.

JP 2000-1111914 A JP 2001-188128 A JP 2001-13303 A

  Accordingly, an object of the present invention is a long polarizing plate suitable for increasing the contrast of a liquid crystal display panel, and prevents the deformation of the polarizing plate during storage and transportation while maintaining the clearness, and does not cause a decrease in contrast. The present invention provides a long polarizing plate and a high-contrast liquid crystal display device using the same.

  The above object of the present invention is achieved by the following configurations.

1. A long polarizing plate having a polarizing film sandwiched between two protective films (A) and (B),
The protective film (A) has a hard coat layer containing a reaction product obtained by curing an ultraviolet curable resin having a viscosity at 25 ° C. of 300 to 700 mPa on the base film, and the arithmetic average roughness Ra of the surface (JIS B0601: 2001) is a hard coat film of 2 to 20 nm,
The protective film (B) is an ester compound in which at least one of cellulose acetate propionate and at least one of a pyranose structure or furanose structure is 1 to 12, and all or part of the OH groups of the structure are esterified. And an optical compensation film containing
Further, a long polarizing plate characterized in that a protective film is bonded to the surface of the hard coat film and wound into a roll.

  2. The hard coat layer contains a polyfunctional acrylate and a monofunctional acrylate, and the mass ratio of the polyfunctional acrylate and the monofunctional acrylate is polyfunctional acrylate: monofunctional acrylate = 80: 20 to 98: 2. 2. The polarizing plate according to 1 above.

  3. 3. The long polarizing plate as described in 1 or 2 above, wherein the substrate film contains a cellulose ester, and the degree of acetyl substitution of the cellulose ester is in the range of 2.8 to 3.0. .

  4). Tan-delta of the film width direction of the said base film has the following relationship, The elongate polarizing plate of any one of said 1-3 characterized by the above-mentioned.

0.5 ≧ tan δ ₋₄₀ / tan δ _peak ≧ 0.23
Here, tan δ _peak is a maximum value obtained by measuring a tan δ value of 25 ° C. to 210 ° C., and tan δ- ₄₀ is a value of tan δ at a temperature of −40 ° C. when tan δ _peak is indicated.

  5. The base film contains a thermoplastic acrylic resin and a cellulose ester resin, and the mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is thermoplastic acrylic resin: cellulose ester resin = 95: 5 to 50:50. 5. The long polarizing plate according to any one of 1 to 4 above, wherein the long polarizing plate is provided.

  6). 6. The long polarizing plate according to any one of 1 to 5, wherein the optical compensation film satisfies the following formulas (I) and (II).

(I) 40 ≦ Ro ≦ 100 (nm)
(II) 90 ≦ Rt ≦ 300 (nm)
Ro = (nx−ny) × d
Rt = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the plane of the retardation film, ny is the refractive index in the direction perpendicular to the slow axis in the plane, nz is the refractive index in the thickness direction, and d is the refractive index in the thickness direction) Represents the thickness (nm) of the retardation film, and the refractive index is measured at 590 nm.)
7). A liquid crystal display device comprising a polarizing plate cut out from the long polarizing plate according to any one of 1 to 6 in at least one of the liquid crystal cells.

  8). 8. The liquid crystal display device according to 7, wherein the liquid crystal display device has a direct type backlight.

  According to the present invention, it is a long polarizing plate suitable for increasing the contrast of a liquid crystal display panel, and prevents the deformation of the polarizing plate during storage and transportation while maintaining clearness, and does not cause a decrease in contrast. A polarizing plate and a high-contrast liquid crystal display device using the same can be provided.

It is explanatory drawing of the protrusion concerning this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

  As a result of intensive studies on the above problems, the inventor is a long polarizing plate in which a polarizing film is sandwiched between two protective films (A) and (B), and the protective film (A) is 25 A hard coat layer containing a reaction product obtained by curing an ultraviolet curable resin having a viscosity at 300 ° C. of 300 to 700 mPa is formed on the base film, and the arithmetic average roughness Ra (JIS B0601: 2001) of the surface is 2 A hard coat film having a thickness of 20 nm, wherein the protective film (B) has at least one cellulose acetate propionate and at least one pyranose structure or furanose structure, and no more than 12 OH groups in the structure. Or an optical compensation film containing a partially esterified ester compound, and further protecting the surface of the hard coat film. When the film is wound and stored while being transported, while the protective film is bonded to the polarizing plate, the long polarizing plate is characterized in that the film is bonded and wound into a roll. By using an optical compensation film in combination with the other surface of the polarizing film that can effectively disperse the stress generated by the blocking of the polarizing plate, and also effectively suppress the increase in internal scattering even when the stress is applied to the polarizing plate. The inventors have found that while maintaining clearness, the polarizing plate during storage and transportation is prevented from being deformed, and a long polarizing plate that does not cause a decrease in contrast can be obtained.

  The long polarizing plate of the present invention is suitable for a liquid crystal display device having a contrast of 5000 or more, and particularly suitable for a liquid crystal display device having a direct backlight.

  Details of the present invention will be described below.

<Surface shape>
The hard coat film according to the present invention has a surface arithmetic average roughness Ra of 2 to 20 nm, more preferably 3 to 20 nm, and particularly preferably 4 to 20 nm. If it is less than 2 nm, it is not possible to prevent partial blocking that is likely to occur particularly at high temperatures and high humidity. If it exceeds 20 nm, the clearness of the hard coat film is inferior due to the effect of surface irregular reflection. The arithmetic average roughness Ra is a value measured with an optical interference type surface roughness meter (RST / PLUS, manufactured by WYKO) based on the provisions of JIS B0601: 2001.

In order for the hard coat layer according to the present invention to have an arithmetic average roughness Ra in the above range, the hard coat layer preferably has a protrusion shape. The height of the protrusion shape is 1 nm to 1 μm, preferably 10 nm to 0.5 μm. The width is 50 nm to 100 μm, preferably 50 nm to 50 μm. The height and width of the protrusion shape can be obtained from cross-sectional observation. FIG. 1 is an explanatory view of the protrusion. As shown in FIG. 1, the center line a is drawn on the cross-sectional observation image, and the distance between the two intersections of the lines b and c and the center line a forming the mountain ridge is defined as the protrusion size width t and did. Further, the distance from the summit to the center line a is obtained as the height h of the protrusion size. The number of protrusions on the hard coat layer is preferably 500 to 200000 pieces / mm ² . Specifically, it can be measured by the following method.

  The number of protrusions was measured by measuring the hard coat layer with an optical interference surface roughness meter (RST / PLUS, manufactured by WYKO, magnification 50 times). Next, the number of protrusions in this measurement area (100 μm × 100 μm square) was read from the image. This series of measurements is performed 10 times, and the number of protrusions of the hard coat layer of the hard coat film can be determined from the average value of 10 times. As the number of protrusions, protrusions having a height of 3 nm or more from the average line of the roughness curve are counted.

  The method for forming the protrusion shape is achieved by coating, drying, and curing a coating composition containing an ultraviolet curable resin having a viscosity at 25 ° C. of 300 to 700 mPa, which will be described later. In particular, it is preferable to control the treatment temperature in the decreasing rate drying section in the drying step of the coating composition to a high temperature condition.

  This is because, when a coating composition containing a low-viscosity resin and a solvent is applied on a film substrate, the film surface is dissolved by the solvent contained in the coating composition, and the resin coating on it is dried. In particular, it is presumed that a fine protrusion shape is formed because convection is generated in the coating film due to being placed in a high temperature state in the decreasing rate drying section, and the surface state tends to be uneven.

  In addition, the formation of the protrusion shape can be controlled by appropriately selecting the type of resin of the base film, the type of solvent that dissolves the ultraviolet curable resin, and the like.

  The resin for the base film is a cellulose ester resin, and is preferably a cellulose triacetate having an acetyl substitution degree in the range of 2.8 to 3.0.

  As the solvent species for dissolving the ultraviolet curable resin, it is preferable to use a solvent that swells or partially dissolves a base film described later.

  In addition, other methods that can form the protrusion shape can be used together, such as a method of adding fine particles, a method of forming a protrusion on the surface by pressing a mold, and a resin having a different SP value (solubility parameter). Further, a method for forming surface irregularities (for example, a method described in JP 2007-182519 A or JP 2009-13384 A) may be combined.

<Haze>
The haze value (Hh) of the hard coat film according to the present invention is preferably 0.7% or less from the viewpoint of clearness. In addition, when the haze value (Hh) of the hard coat film is less than 0.2%, it is difficult to design from the viewpoint of the handleability of the hard coat film. The difference between the haze value (Hh) of the hard coat film and the haze value (Hf) of the base film is 0.02% to 0.3%, thereby achieving the object effect of the present invention. In addition, it is preferable in that sufficient brightness and high contrast can be obtained when used outdoors such as a large-sized liquid crystal display device or digital signage.

  In order to control the haze value of the hard coat layer, adjustment of the resin and solvent content mass ratio of the resin constituting the hard coat layer, the type and amount of the additive, the hard coat layer coating composition, and the reduction rate of the drying process This can be achieved under the processing temperature conditions in the drying section. In addition, since the arithmetic average roughness Ra of the hard coat layer also affects the haze value as the surface haze, it is effective to control the shape and number of the protrusions.

  Haze measurement can be performed using a haze meter (NDH2000; manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS-K7136.

<Hard coat film>
The hard coat film according to the present invention is composed of at least a base film and a hard coat layer, and the hard coat layer is coated with a coating composition containing an ultraviolet curable resin having a viscosity of at least 25 ° C. of 300 to 700 mPa. It is cured and formed through a crosslinking reaction by ultraviolet irradiation.

  By selecting an ultraviolet curable resin having a viscosity of 300 to 700 mPa at 25 ° C. according to the present invention and using such a low viscosity resin, the arithmetic operation within the scope of the present invention is applied to the surface of the hard coat film as described above. A protrusion shape having an average roughness Ra can be formed. The viscosity of the resin can be measured using a rotary rheometer (Rheostress RS600: Thermo HAAKE), an E-type viscometer, or the like.

  As the ultraviolet curable resin, a component containing a monomer having an ethylenically unsaturated double bond is preferably used. Specific examples of the ultraviolet curable resin include, for example, an ultraviolet curable urethane acrylate resin and an ultraviolet curable resin. A polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, an ultraviolet curable epoxy resin, or the like is preferably used. Of these, ultraviolet curable acrylate resins are preferred.

  As the ultraviolet curable acrylate resin, a polyfunctional acrylate is preferable. The polyfunctional acrylate is preferably selected from the group consisting of pentaerythritol polyfunctional acrylate, dipentaerythritol polyfunctional acrylate, pentaerythritol polyfunctional methacrylate, and dipentaerythritol polyfunctional methacrylate. Here, the polyfunctional acrylate is a compound having two or more acryloyloxy groups or methacryloyloxy groups in the molecule.

  Examples of the polyfunctional acrylate monomer include ethylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, and tetramethylolmethane triacrylate. , Tetramethylolmethane tetraacrylate, pentaglycerol triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, glycerin triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol Ritolol hexaacrylate, tris (acryloyloxyethyl) isocyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, Tetramethylol methane trimethacrylate, tetramethylol methane tetramethacrylate, pentaglycerol trimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerol trimethacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetramethacrylate Acrylate, dipentaerythritol penta methacrylate, dipentaerythritol hexa methacrylate, and the like preferably. These compounds are used alone or in admixture of two or more. Moreover, oligomers, such as a dimer and a trimer of the said monomer, may be sufficient.

  Particularly preferred low-viscosity resins include trimethylolpropane triacrylate, glycerin triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate and the like.

  In addition, the hard coat layer according to the present invention contains a monofunctional acrylate in a content ratio of the polyfunctional acrylate and the monofunctional acrylate in a polyfunctional acrylate: monofunctional acrylate = 80: 20 to 99: 2, more Even in a severe durability test, it is preferable from the viewpoint of further exerting the object effect of the present invention.

  Monofunctional acrylates include isobornyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, isostearyl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, lauryl acrylate, isooctyl acrylate, tetrahydrofurfuryl acrylate, behenyl Examples include acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and cyclohexyl acrylate. Monofunctional acrylates can be obtained from Shin Nakamura Chemical Co., Ltd., Osaka Organic Chemical Industry Co., Ltd., and the like.

  The hard coat layer contains a photopolymerization initiator for promoting the curing of the ultraviolet curable resin. The amount of the photopolymerization initiator is, by mass ratio, photopolymerization initiator: UV curable resin = 20: It is preferable to contain by 100-0.01: 100.

  Specific examples of the photopolymerization initiator include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof, but are not particularly limited thereto. .

  The hard coat layer according to the present invention can also contain particles within a range that does not impair the clearness that is the effect of the present invention, and the inorganic fine particles include silicon oxide, titanium oxide, aluminum oxide, tin oxide, indium oxide, Mention may be made of ITO, zinc oxide, zirconium oxide, magnesium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. In particular, silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide and the like are preferably used.

  These inorganic fine particles are preferably coated with an organic component having a reactive functional group on a part of the surface because the scratch resistance is improved while maintaining the transparency of the hard coat film. As a method for coating an organic component having a reactive functional group on a part of the surface, for example, a compound containing an organic component such as a silane coupling agent reacts with a hydroxyl group present on the surface of the metal oxide fine particles, and the surface A mode in which an organic component is bonded to a part of the metal particle, a mode in which an organic component is attached to a hydroxyl group present on the surface of a metal oxide fine particle by an interaction such as a hydrogen bond, or one or more inorganic particles in a polymer particle The aspect containing microparticles | fine-particles etc. are mentioned.

  Organic particles include polymethacrylic acid methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicon resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, and melamine resin. Powder, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, polyfluoroethylene resin powder, or the like can be added.

  Preferred fine particles include crosslinked polystyrene particles (for example, SX-130H, SX-200H, SX-350H manufactured by Soken Chemical), polymethyl methacrylate-based particles (for example, MX150, MX300 manufactured by Soken Chemical), and fluorine-containing acrylic resin fine particles. . Examples of the fluorine-containing acrylic resin fine particles include commercial products such as FS-701 manufactured by Nippon Paint. Examples of the acrylic particles include Nippon Paint: S-4000, and examples of the acrylic-styrene particles include Nippon Paint: S-1200, MG-251.

  The average particle size of these fine particle powders is not particularly limited, but is preferably 0.01 to 5 μm, and more preferably 0.01 to 1.0 μm. Moreover, you may contain 2 or more types of microparticles | fine-particles from which a particle size differs. The average particle diameter of the fine particles can be measured by, for example, a laser diffraction particle size distribution measuring device.

  The hard coat layer according to the present invention is provided by applying, drying, and curing an ultraviolet curable resin composition diluted with a solvent that swells or partially dissolves the base film on the base film in the following manner. It is preferable from the point that a protrusion shape is easily obtained in the hard coat layer.

  The solvent for dissolving or swelling the base film can include the following solvents when the base film is a cellulose ester resin film or a film composed of a cellulose ester resin and an acrylic resin. It is not limited.

Ethers having 3 to 12 carbon atoms: specifically, dibutyl ether, dimethoxymethane, diethoxyethane, propylene oxide, 1,4 dioxane, 1,3 dioxolane, 1,3,5 trioxane, tetrahydrofuran, anisole and Phenetole, etc.
Ketones having 3 to 12 carbon atoms: specifically acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, etc.
Esters having 3 to 12 carbon atoms: specifically, ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate, and γ- Ptylolactone, etc.
Organic solvent having two or more kinds of functional groups: Specifically, methyl 2-methoxyacetate, ethyl 2-ethoxyacetate, ethyl 2-ethoxypropionate, 2-methoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 1 2, acetoxyacetone, acetylacetone, diacetone alcohol, methyl acetoacetate, ethyl acetoacetate and the like.

  These can be used alone or in combination of two or more. As a solvent solvent for dissolving or swelling the base film, a ketone solvent is preferable, and methyl ethyl ketone and cyclohexanone are particularly preferable.

  In addition to the above solvent, the hard coat layer according to the present invention can also contain a solvent that does not dissolve or swell the base film. As a solvent that does not dissolve the base film, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol, cyclohexanol, propylene glycol monoethyl ether, isobutyl acetate, methyl isobutyl ketone, 2-octanone, 2 -Pentanone, 2-hexanone, 2-heptanone, 3-pentanone, 3-heptanone, 4-heptanone, toluene and the like.

  These can be used alone or in combination of two or more.

  The ratio of the solvent to be used is not particularly limited, but the mass ratio of the total amount of solvent (A) that dissolves or swells the base film and the total amount of solvent (B) that does not dissolve or swell the base film ( A / B) is preferably from 10/90 to 90/10, more preferably from 80/20 to 65/35.

  Moreover, 0.1-40 micrometers is suitable for an application quantity as a wet film thickness, Preferably, it is 0.5-30 micrometers. The dry film thickness is from 0.1 to 30 μm, preferably from 1 to 20 μm, particularly preferably from 6 to 15 μm.

  The hard coat layer is coated on the base film using a known coat method such as gravure coater, dip coater, reverse coater, wire bar coater, die coater, and ink jet method. Then, after coating, it can be formed by drying, UV curing treatment, and if necessary, heat treatment for UV curing.

  The drying is preferably performed at a high temperature of 70 ° C. or higher, more preferably 80 ° C. or higher, and particularly preferably 90 ° C. or higher.

  In general, it is known that the drying process changes from a constant state to a gradually decreasing state when drying starts. The decreasing section is called the decreasing rate drying section. In the constant rate drying section, the amount of heat flowing in is all consumed for solvent evaporation on the coating film surface, and when the solvent on the coating film surface decreases, the evaporation surface moves from the surface to the inside and enters the decreasing rate drying section. Thereafter, the temperature of the coating film surface rises and approaches the hot air temperature, so that the temperature of the ultraviolet curable resin composition rises, the resin viscosity decreases, and the fluidity increases. In this case, the use of an ultraviolet curable resin having a viscosity at 25 ° C. of 300 to 700 mPa is advantageous in forming a protrusion shape on the surface.

  As a light source for UV curing treatment, any light source that generates ultraviolet rays can be used without limitation. For example, low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, metal halide lamp, excimer laser, ultraviolet laser, cold cathode tube, hot cathode tube, black light, LED (light emitting diode), etc. are applicable. A high-pressure mercury lamp that emits ultraviolet light having a wavelength of 365 nm is preferable.

Irradiation conditions vary depending on each lamp, but the irradiation amount of ultraviolet rays is usually 50 to 1000 mJ / cm ² , preferably 50 to 300 mJ / cm ² .

  Moreover, when irradiating an ultraviolet-ray, it is preferable to carry out, applying tension | tensile_strength in the conveyance direction of a film, More preferably, it is performing applying tension | tensile_strength also in the width direction. The tension to be applied is preferably 30 to 300 N / m. The method for applying tension is not particularly limited, and tension may be applied in the transport direction on the back roll, or tension may be applied in the width direction or biaxial direction by a tenter. Thereby, a film having further excellent flatness can be obtained.

  The hard coat layer may contain a conductive agent in order to impart antistatic properties, and preferred conductive agents include metal oxide particles or π-conjugated conductive polymers. An ionic liquid is also preferably used as the conductive compound. In addition, the hard coat layer has a nonionic surfactant such as a silicone surfactant, a fluorosurfactant or a polyoxyether, an anionic surfactant, from the viewpoint of coating properties and the uniform dispersibility of fine particles. An agent and a fluorine-siloxane graft polymer may be contained. The fluorine-siloxane graft polymer refers to a copolymer polymer obtained by grafting polysiloxane containing siloxane and / or organosiloxane alone and / or organopolysiloxane to at least a fluorine-based resin. Examples of commercially available products include ZX-022H, ZX-007C, ZX-049, and ZX-047-D manufactured by Fuji Kasei Kogyo Co., Ltd. Moreover, it is preferable to add these components in 0.01-3 mass% with respect to the solid content component in a coating liquid.

  The hard coat layer may be a single layer or a plurality of layers. In order to easily control the hard coat property, haze, and arithmetic average roughness Ra of the hard coat layer, the hard coat layer may be divided into two or more layers.

  The thickness of the uppermost layer when two or more layers are provided is preferably in the range of 0.05 to 2 μm. Two or more layers may be formed as a simultaneous multilayer. The simultaneous multi-layer is to form a hard coat layer by applying two or more hard coat layers on a base material without going through a drying step. In order to laminate the second hard coat layer on the first hard coat layer without a drying process, the layers are stacked one after another by an extrusion coater or simultaneously by a slot die having a plurality of slits. Can be done.

  The hard coat film in the present invention has a pencil hardness, which is an index of hardness, of H or higher, more preferably 3H or higher. If it is 3H or more, it is not only difficult to be scratched in the polarizing plate forming step of the liquid crystal display device, but also used for outdoor applications, and is a surface protective film for large liquid crystal display devices and liquid crystal display devices for digital signage. When used as an excellent film strength. The pencil hardness is evaluated by pencil hardness evaluation specified by JIS K5400 using a test pencil specified by JIS S 6006 after the prepared hard coat film is conditioned at a temperature of 23 ° C. and a relative humidity of 55% for 2 hours or more. It is the value measured according to the method.

<Base film, optical compensation film>
The base film used for the hard coat layer according to the present invention is preferably easy to produce, transparent, easily adhered to the hard coat layer, and optically isotropic. Further, in the present invention, the optical compensation film according to the present invention can be prepared in the same manner as the base film, and a stretching operation is performed in the production process in order to impart a retardation to the optical compensation film. Is preferred.

  The term “transparent” as used in the present invention means that the visible light transmittance is 60% or more, preferably 80% or more, and particularly preferably 90% or more.

  The base film according to the present invention is preferably a cellulose ester film, and the cellulose ester is preferably a lower fatty acid ester of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. For example, cellulose acetate, cellulose propionate, cellulose butyrate and the like, and JP-A Nos. 10-45804 and 08-231761 And mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate as described in U.S. Pat. No. 2,319,052.

  Especially, it is preferable that a base film is a cellulose triacetate film in which the acetyl substitution degree of a cellulose ester exists in the range of 2.8-3.0.

  Moreover, although the optical compensation film according to the present invention is a cellulose acetate propionate film, a cellulose acetate propionate film having an acyl group substitution degree represented by the following formula is preferably used.

Formula (i) 2.6 ≦ X + Y ≦ 3.0
Formula (ii) 0 ≦ X ≦ 2.5
X represents the acetyl substitution degree, and Y represents the propionyl substitution degree. Among them, it is preferable that 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9. The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  The cellulose ester has a number average molecular weight (Mn) of 125,000 or more and less than 155000, a weight average molecular weight (Mw) of 265,000 or more and less than 310,000, and a cellulose ester having a Mw / Mn of 1.9 to 2.1 is a physical property as a film. From the viewpoint of

  The number average molecular weight (Mn) and molecular weight distribution (Mw) of the cellulose ester can be measured using high performance liquid chromatography. The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation)
A calibration curve with 13 samples from Mw = 100000 to 500 was used. The 13 samples are preferably used at approximately equal intervals.

  The refractive index of the base film and the optical compensation film is preferably 1.30 to 1.70, and more preferably 1.40 to 1.65. The refractive index is measured by the method of JIS K7142 using an Atpe refractometer 2T.

  The base film has the following relationship with tan δ measured by changing the temperature from 25 ° C. to 210 ° C. at a humidity of 55% RH in the width direction of the film. It is preferable from the point of exhibiting.

0.5 ≧ tan δ ₋₄₀ / tan δ _peak ≧ 0.23
Here, tan δ _peak is the maximum value obtained by measuring the tan δ value by changing the temperature from 25 ° C. to 210 ° C., and tan δ- ₄₀ is the value of tan δ at a temperature of −40 ° C. when tan δ _peak is indicated.

  By making the balance of the storage elastic modulus and the loss elastic modulus with respect to the tan δ in the film width direction of the base film, that is, the temperature within the above range, the object effect of the present invention is more effectively exhibited.

  The tan δ was measured, for example, by using a sample that had been conditioned for 24 hours in an atmosphere of 23 ° C. and 55% RH in advance and increasing the temperature under the following conditions at a humidity of 55% RH or setting the temperature.

Measuring device: RSA III manufactured by TI Instruments
Sample: width 5 mm, length 50 mm (gap set to 20 mm)
Measurement conditions: Tensile mode Measurement temperature: 25-210 ° C or -40 ° C
Temperature rising condition: 5 ° C / min
Frequency: 1Hz
<Cellulose ester resin / thermoplastic acrylic resin-containing film>
The base film according to the present invention contains a thermoplastic acrylic resin and a cellulose ester resin, and the content mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is thermoplastic acrylic resin: cellulose ester resin = 95: 5 to It is preferable to use a film that is 50:50.

  The acrylic resin includes a methacrylic resin. Although it does not restrict | limit especially as an acrylic resin, What consists of 50-99 mass% of methyl methacrylate units and 1-50 mass% of other monomer units copolymerizable with this is preferable. Other monomers that can be copolymerized include alkyl methacrylates having 2 to 18 carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, acrylic acid, methacrylic acid, and the like. Unsaturated group-containing divalent carboxylic acids such as saturated acid, maleic acid, fumaric acid and itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, 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, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer. n-Butyl acrylate is particularly preferably used.

  Moreover, it is preferable that a weight average molecular weight (Mw) is 80000-500000, More preferably, it exists in the range of 110000-500000.

  The weight average molecular weight of the acrylic resin can be measured by gel permeation chromatography including the measurement conditions. There is no restriction | limiting in particular as a manufacturing method of an acrylic resin, 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. Commercial products can also be used. For example, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electrochemical Industry Co., Ltd.) and the like can be mentioned. . Two or more acrylic resins can be used in combination. As the acrylic resin, a graft copolymer obtained by grafting a (meth) acrylic resin to a copolymer of a (meth) acrylic rubber and an aromatic vinyl compound described in JP-A-2009-84574 may be used. . In the graft copolymer, a copolymer of (meth) acrylic rubber and an aromatic vinyl compound forms a core, and the (meth) acrylic resin forms a shell around the copolymer. -It is preferably a shell-type graft copolymer.

  The total mass of the acrylic resin and the cellulose ester resin in the base film is preferably 55% by mass or more of the base film, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

  The base film may be configured to contain resins and additives other than thermoplastic acrylic resins and cellulose ester resins.

<Acrylic particles>
The base film may contain acrylic particles because it is excellent in improving brittleness. An acrylic particle represents the acrylic component which exists in the state of particle | grains (it is also called an incompatible state) in the base film containing the said thermoplastic acrylic resin and cellulose-ester resin in a compatible state.

  The acrylic particles are not particularly limited, but are preferably acrylic particles having a layer structure of two or more layers, and particularly preferably a multilayer structure acrylic granular composite. Examples of commercially available acrylic granular composites that are multilayer polymers include, for example, “Metablene” manufactured by Mitsubishi Rayon Co., “Kaneace” manufactured by Kaneka Chemical Co., Ltd., “Paralloid” manufactured by Kureha Chemical Co., Ltd., Rohm and “Acryloid” manufactured by Haas, “Staffyroid” manufactured by Ganz Kasei Kogyo Co., Ltd., “Parapet SA” manufactured by Kuraray Co., Ltd., and the like can be used.

  In addition, specific examples of acrylic particles that are graft copolymers suitably used as acrylic particles include unsaturated carboxylic acid ester monomers, unsaturated carboxylic acid monomers in the presence of rubbery polymers. And a graft copolymer obtained by copolymerizing a mixture of a monomer, an aromatic vinyl monomer, and, if necessary, a monomer composed of other vinyl monomers copolymerizable therewith.

  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.

  Moreover, when adding an acrylic particle to a base film, it is preferable at the point which obtains a film with high transparency that the refractive index of the mixture of an acrylic resin and a cellulose-ester resin and the refractive index of an acrylic particle are near. Specifically, the refractive index difference between the acrylic particles and the acrylic resin is preferably 0.05 or less, more preferably 0.02 or less, and particularly preferably 0.01 or less.

  There is no restriction | limiting in particular in the method of mix | blending an acrylic particle with an acrylic resin, After blending an acrylic resin and another arbitrary component previously, it is a single screw or a twin screw extruder, adding an acrylic particle normally at 200-350 degreeC. Thus, a method of uniformly melting and kneading is preferably used.

  In addition, a method in which a solution in which acrylic particles are dispersed in advance is added to and mixed with a solution (dope solution) in which an acrylic resin and a cellulose ester resin are dissolved, and a solution in which acrylic particles and other optional additives are dissolved and mixed. A method such as in-line addition can be used.

  Moreover, as an acrylic particle, a commercially available thing can also be used. 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.

  The acrylic fine particles are in the range of acrylic fine particles: acrylic resin and cellulose ester resin total mass = 0.5: 100 to 30: 100 with respect to the total mass of the acrylic resin and cellulose ester resin constituting the film. By containing, it is preferable from the point that an objective effect is exhibited more preferable, More preferably, it is the range of 1.0: 100-15: 100 of acrylic fine particles: total mass of acrylic resin and cellulose-ester resin.

<Other additives>
In order to improve the fluidity and flexibility of the composition, a plasticizer can be used in combination with the base film and the optical compensation film according to the present invention. Examples of the plasticizer include phthalate ester, fatty acid ester, trimellitic ester, phosphate ester, polyester, and epoxy. Of these, polyester and phthalate plasticizers are preferably used. Polyester plasticizers are superior in non-migration and extraction resistance compared to phthalate ester plasticizers such as dioctyl phthalate. It can be applied to a wide range of uses by selecting or using these plasticizers according to the use.

  The optical compensation film according to the present invention is an ester compound (hereinafter referred to as a sugar ester compound) in which at least one of a pyranose structure or furanose structure is at least one and not more than 12 and all or a part of the OH groups in the structure are esterified. ).

  As described above, the optical compensation film according to the present invention contains a cellulose acetate propionate and a sugar ester compound, thereby forming an optical compensation film that hardly causes internal scattering even if a slight stress is applied. .

  The optical compensation film preferably has a retardation satisfying the following formulas (I) and (II) for widening the viewing angle.

(I) 40 ≦ Ro ≦ 100 (nm)
(II) 90 ≦ Rt ≦ 300 (nm)
Ro = (nx−ny) × d
Rt = ((nx + ny) / 2−nz) × d
In the formula, nx is the refractive index in the slow axis direction in the plane of the retardation film, ny is the refractive index in the direction perpendicular to the slow axis in the plane, nz is the refractive index in the thickness direction, and d is the position. Represents the thickness (nm) of the retardation film. The measurement wavelength of the refractive index is 590 nm.

  The retardation can be obtained at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH using, for example, KOBRA-21ADH (Oji Scientific Instruments).

<Sugar ester compound>
The optical compensation film according to the present invention includes an ester compound in which at least one of a pyranose structure or furanose structure is 1 to 12, and all or a part of OH groups of the structure is esterified. .

  The proportion of esterification is preferably 70% or more of the OH groups present in the pyranose structure or furanose structure.

  Examples of the sugar ester compound used in the present invention include the following, but the present invention is not limited thereto.

  Glucose, galactose, mannose, fructose, xylose or arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose or kestose .

  In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included.

  Among these compounds, compounds having both a pyranose structure and a furanose structure are particularly preferable.

  Examples include sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose, and more preferably sucrose.

  The monocarboxylic acid used for esterifying all or part of the OH group in the pyranose structure or furanose structure is not particularly limited, and is a known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic A monocarboxylic acid or the like can be used. The carboxylic acid used may be one type or a mixture of two or more types.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, Examples include unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid.

  Examples of preferable alicyclic monocarboxylic acids include acetic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include aromatic monocarboxylic acids having an alkyl group or alkoxy group introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, cinnamic acid, benzylic acid, biphenylcarboxylic acid, and naphthalene. Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as carboxylic acid and tetralin carboxylic acid, or derivatives thereof. More specifically, xylyl acid, hemelic acid, mesitylene acid, prenylic acid, γ-isoduric acid, jurylic acid, mesitic acid, α-isoduric acid, cumic acid, α-toluic acid, hydroatropic acid, atropic acid, hydrocinnamic acid, salicylic acid, o-anisic acid, m-anisic acid, p-anisic acid , Creosote acid, o-homosalicylic acid, m-homosalicylic acid, p-homosalicylic acid, o-pyroca Succinic acid, β-resorcylic acid, vanillic acid, isovanillic acid, veratromic acid, o-veratrumic acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratrumic acid, o-homoveratrumic acid, phthalonic acid, p- Although coumaric acid can be mentioned, benzoic acid is particularly preferable.

  The oligosaccharide ester compound can be applied as a compound having 1 to 12 at least one of the pyranose structure or furanose structure according to the present invention.

  Oligosaccharides are produced by allowing an enzyme such as amylase to act on starch, sucrose, etc. Examples of oligosaccharides that can be applied to the present invention include maltooligosaccharides, isomaltoligosaccharides, fructooligosaccharides, galactooligosaccharides, xylooligos. Sugar.

Moreover, the said ester compound is a compound which condensed 1 or more and 12 or less of at least 1 sort (s) of the pyranose structure or furanose structure represented with the following general formula (A). However, R < ₁₁ > -R < ₁₅ >, R < ₂₁ > -R < ₂₅ > represents a C2-C22 acyl group or a hydrogen atom, m and n represent the integer of 0-12 respectively, and m + n represents the integer of 1-12.

R _{11 to} R ₁₅ and R _{21 to} R ₂₅ are preferably a benzoyl group or a hydrogen atom. The benzoyl group may further have a substituent R ₂₆ (p is 0 to 5), and examples thereof include an alkyl group, an alkenyl group, an alkoxyl group, and a phenyl group, and further, these alkyl groups, alkenyl groups, and phenyl groups. May have a substituent. Oligosaccharides can also be produced by the same method as the ester compound of the present invention.

  Specific examples of the sugar ester compound according to the present invention are shown below, but the present invention is not limited thereto.

  The sugar ester compound according to the present invention is preferably contained in the optical compensation film in an amount of 0.5 to 30% by mass, particularly preferably 5 to 30% by mass.

  Moreover, it is preferable to use the compound of the following general formula (c) for the optical compensation film according to the present invention. The compound having a structure represented by the general formula (c) is a polyester plasticizer, and a polyester plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be used.

Formula (c): B- (GA) _n -GB
(In the formula, B is an arylcarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A Represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In the general formula (c), a benzene monocarboxylic acid residue represented by B and an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue represented by G, an alkylene dicarboxylic acid residue or aryl dicarboxylic group represented by A It is composed of an acid residue and can be obtained by a reaction similar to that of a normal polyester plasticizer.

  Examples of the aryl carboxylic acid component of the polyester plasticizer used in the present invention include benzoic acid, para-tert-butyl benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethyl benzoic acid, ethyl benzoic acid, and normal propyl benzoic acid. There are acid, aminobenzoic acid, acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester plasticizer that can be preferably used in the optical compensation film according to the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2 -Butanediol, 1,3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1, 3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3propanediol (3,3) 3-dimethylolheptane), 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2 4-trimethyl 1,3-pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol These glycols are used as one kind or a mixture of two or more kinds.

  In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  In addition, examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. It can be used as a seed or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  The polyester plasticizer used in the optical compensation film according to the present invention has a number average molecular weight of preferably 300 to 1500, more preferably 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxyl group (hydroxyl group) value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl group (hydroxyl group) value is 15 mgKOH / g or less. Is.

  Although the specific compound of the aromatic terminal ester plasticizer of the structure shown to the general formula (c) which can be used for this invention below is shown, this invention is not limited to this.

  Since the hard coat film is usually arranged on the viewing side, the base film preferably also contains an ultraviolet absorber. As the ultraviolet absorber used, a benzotriazole-based, 2-hydroxybenzophenone-based or salicylic acid phenyl ester-based And the like. For example, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3 Triazoles such as 5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone And benzophenones. Here, among ultraviolet absorbers, ultraviolet absorbers having a molecular weight of 400 or more are less likely to volatilize at a high boiling point and are difficult to disperse even during high-temperature molding, so that the weather resistance is effectively improved with a relatively small amount of addition. be able to.

  Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2-methylenebis [4- (1, 1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis ( Hindered amines such as 1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid Bis (1,2,2,6,6-pentamethyl-4-piperidyl), 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl L] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine and the like, hindered phenol and hindered amine A hybrid system having both structures can be mentioned, and these can be used alone or in combination of two or more. Among these, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1,3,3- Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

  Furthermore, various antioxidants can also be added to the base film in order to improve the thermal decomposability and thermal colorability during molding. It is also possible to add an antistatic agent to give the base film antistatic performance.

  A flame retardant acrylic resin composition containing a phosphorus flame retardant may be used for the base film.

  Phosphorus flame retardants used here include red phosphorus, triaryl phosphate ester, diaryl phosphate ester, monoaryl phosphate ester, aryl phosphonate compound, aryl phosphine oxide compound, condensed aryl phosphate ester, halogenated alkyl phosphorus. Examples thereof include one or a mixture of two or more selected from acid esters, halogen-containing condensed phosphates, halogen-containing condensed phosphonates, halogen-containing phosphites, and the like.

  Specific examples include triphenyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, tris (β-chloroethyl) phosphate, tris (dichloropropyl). Examples thereof include phosphate and tris (tribromoneopentyl) phosphate.

  The base film is preferably a “film that does not cause ductile fracture”. Here, the ductile fracture is a fracture caused by applying a stress larger than the strength of a certain material, and is defined as a fracture accompanied by significant elongation or drawing of the material until the final fracture. The fracture surface is characterized by numerous indentations called dimples.

  Whether or not the film is “a film in which ductile fracture does not occur” is evaluated based on the fact that breakage such as breakage is not observed even when a large stress is applied to bend the film in two.

  In addition to the increase in the size of liquid crystal display devices and the increasing brightness of backlight light sources, the use of digital signage and other outdoor applications demands higher brightness. It is required to withstand use in a high-temperature environment, and it is preferable that the substrate film has sufficient heat resistance when the tension softening point is 105 ° C to 145 ° C, particularly 110 ° C. It is preferable to control to ˜130 ° C.

  As a specific method of measuring the tension softening point, for example, using a Tensilon tester (ORIENTEC, RTC-1225A), the optical film is cut out at 120 mm (length) × 10 mm (width) and pulled with a tension of 10 N. However, the temperature can be continuously increased at a temperature increase rate of 30 ° C./min, and the temperature at 9 N can be measured three times, and the average value can be obtained.

  From the viewpoint of heat resistance, the substrate film preferably has a glass transition temperature (Tg) of 110 ° C. or higher. More preferably, it is 120 ° C. or higher. Especially preferably, it is 150 degreeC or more.

  The glass transition temperature referred to here is an intermediate value determined according to JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 model manufactured by Perkin Elmer) at a temperature rising rate of 20 ° C./min. Point glass transition temperature (Tmg).

  Moreover, as a protective film for a polarizing plate of a liquid crystal display device, unevenness or a change in retardation value may occur due to a dimensional change due to moisture absorption, which may cause problems such as a decrease in contrast and color unevenness. If the polarizing plate protective film used for the liquid crystal display device used in the above, the above problem becomes significant. For this reason, the dimensional change rate (%) is preferably less than 0.5%, and more preferably less than 0.3%.

  Moreover, it is preferable that the base film has a defect of 5 μm or more in diameter in the film plane of 1 piece / 10 cm square or less. More preferably, it is 0.5 piece / 10 cm square or less, more preferably 0.1 piece / 10 cm square or less.

  Here, the diameter of the defect indicates the diameter when the defect is circular, and when the defect is not circular, the range of the defect is determined by observing with a microscope by the following method, and the maximum diameter (diameter of circumscribed circle) is determined.

  The range of the defect is the size of the shadow when the defect is observed with the transmitted light of the differential interference microscope when the defect is a bubble or a foreign object. When the defect is a change in the surface shape, such as transfer of a roll flaw or an abrasion, the size is confirmed by observing the defect with the reflected light of a differential interference microscope.

  In addition, when observing with reflected light, if the size of the defect is unclear, aluminum or platinum is deposited on the surface for observation.

  In order to obtain a film having excellent quality expressed by such a defect frequency with high productivity, it is necessary to filter the polymer solution with high precision immediately before casting, to increase the cleanliness around the casting machine, It is effective to set drying conditions after rolling stepwise and to dry efficiently while suppressing foaming.

  When the number of defects is greater than 1/10 cm square, for example, when the film is tensioned during processing in a later process, the film may break with the defects as a starting point, and productivity may decrease. Moreover, when the diameter of a defect becomes 5 micrometers or more, it can confirm visually by polarizing plate observation etc., and when used as an optical member, a bright spot may arise.

  Even when it cannot be visually confirmed, when a hard coat layer is formed on the film, the coating agent may not be formed uniformly, resulting in a defect (missing coating). Here, the defect is a void in the film (foaming defect) generated due to the rapid evaporation of the solvent in the drying process of the solution casting, a foreign substance in the film forming stock solution, or a foreign substance mixed in the film forming process. This refers to the foreign matter (foreign matter defect) in the film.

  In addition, the base film preferably has a breaking elongation of at least one direction of 10% or more, more preferably 20% or more, in the measurement based on JIS-K7127-1999.

  The upper limit of the elongation at break is not particularly limited, but is practically about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film caused by foreign matter and foaming.

  The thickness of the base film and the optical compensation film is preferably 20 μm or more. More preferably, it is 30 μm or more.

  The upper limit of the thickness is not particularly limited, but in the case of forming a film by a solution casting method, the upper limit is about 250 μm from the viewpoint of applicability, foaming, solvent drying and the like. The thickness of the film can be appropriately selected depending on the application.

  The base film and the optical compensation film preferably have a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%. In order to achieve excellent transparency expressed by such total light transmittance, it is necessary not to introduce additives and copolymerization components that absorb visible light, or to remove foreign substances in the polymer by high-precision filtration. It is effective to reduce the diffusion and absorption of light inside the film.

  Also, reduce the surface roughness of the film surface by reducing the surface roughness of the film contact part (cooling roll, calender roll, drum, belt, coating substrate in solution casting, transport roll, etc.) during film formation. It is also effective to reduce the diffusion and reflection of light on the film surface by reducing the refractive index of the acrylic resin.

<Formation of base film and optical compensation film>
Although the example of the film forming method of a base film and an optical compensation film is demonstrated, this invention is not limited to this.

  As a method for forming the base film and the optical compensation film, production methods such as an inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, and a hot press method can be used.

  From the viewpoint of suppressing the residual solvent using a cellulose ester resin or an acrylic resin for dissolution, a method using a melt casting film forming method is preferable. Methods formed by melt casting can be classified into melt extrusion molding methods, press molding methods, inflation methods, injection molding methods, blow molding methods, stretch molding methods, and the like. Among these, the melt extrusion method is preferable, in which a film having excellent mechanical strength and surface accuracy can be obtained.

  Further, from the viewpoint of suppression of coloring, suppression of defect of foreign matter, suppression of optical defect such as die line, solution casting film formation is preferable.

  In the present invention, a method of extruding a film forming material onto a drum or an endless belt after the film forming material is heated to develop its fluidity is also included as a melt casting film forming method.

(Organic solvent)
The organic solvent useful for forming the dope for producing the base film and the optical compensation film by the solution casting method is not limited as long as it dissolves acrylic resin, cellulose ester resin and other additives at the same time. Can be used.

  For example, as a chlorine organic solvent, methylene chloride, as a non-chlorine organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- Examples include 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane. Methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used.

  In addition to the organic solvent, the dope preferably contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy, and when the proportion of alcohol is small, the acrylic resin and cellulose ester resin dissolve in a non-chlorine organic solvent system. There is also a role to promote.

  In particular, in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms, at least 15 to 45 mass in total of at least three kinds of acrylic resin, cellulose ester resin, and acrylic particles are used. It is preferable that the dope composition is dissolved in%.

  Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Ethanol is preferred because of the stability of these dopes, the relatively low boiling point, and good drying properties.

(Solution casting method)
The base film and the optical compensation film can be produced by a solution casting method. In the solution casting method, a step of preparing a dope by dissolving a resin and an additive in a solvent, a step of casting the dope on a belt-like or drum-like metal support, and a step of drying the cast dope as a web , A step of peeling from the metal support, a step of stretching or maintaining the width, a step of further drying, and a step of winding up the finished film.

  The concentration of cellulose ester in the dope, and the concentration of cellulose ester resin / acrylic resin is preferably higher because the drying load after casting on the metal support can be reduced. The load increases, and the filtration accuracy deteriorates. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  The metal support in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support.

  The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is set to −50 ° C. to a temperature at which the solvent boils and does not foam. A higher temperature is preferred because the web can be dried faster, but if it is too high, the web may foam or the flatness may deteriorate.

  The preferable support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short.

  When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. .

  In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

  In order for the cellulose ester film to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Especially preferably, it is 20-30 mass% or 70-120 mass%.

  The amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Note that M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

  Further, in the drying step of the cellulose ester film or the cellulose ester resin / acrylic resin film, it is preferable that the web is peeled off from the metal support and further dried to make the residual solvent amount 1% by mass or less, more preferably 0. 0.1 mass% or less, particularly preferably 0 to 0.01 mass% or less.

  In the film drying step, generally, a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method in which the web is dried while being conveyed by a tenter method are employed.

(Stretching process)
The optical compensation film according to the present invention is preferably subjected to a stretching treatment for adjusting the retardation.

  In the stretching step, the film can be sequentially or simultaneously stretched in the longitudinal direction (MD direction) and the width direction (TD direction) of the film. The draw ratios in the biaxial directions perpendicular to each other are preferably in the range of 1.0 to 2.0 times in the MD direction and 1.07 to 2.0 times in the TD direction, respectively. It is preferable to carry out within a range of 1.0 to 1.5 times and 1.07 to 2.0 times in the TD direction. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls and the roll peripheral speed difference is used to stretch the roll in the MD direction. And a method of stretching in the MD direction, a method of stretching in the lateral direction and stretching in the TD direction, a method of stretching in the MD / TD direction simultaneously and stretching in both the MD / TD directions, and the like.

  These width maintenance or width direction stretching in the film forming step is preferably performed by a tenter, and may be a pin tenter or a clip tenter.

  The film transport tension in the film forming process such as in the tenter depends on the temperature, but is preferably 120 N / m to 200 N / m, and more preferably 140 N / m to 200 N / m. 140 N / m to 160 N / m is most preferable.

  When stretching, assuming that the glass transition temperature of the optical compensation film is Tg, (Tg-30) to (Tg + 100) ° C., more preferably (Tg-20) to (Tg + 80) ° C., and even more preferably (Tg-5) to (T Tg + 20) ° C.

  The Tg of the optical compensation film can be controlled by the material type constituting the film and the ratio of the constituting materials. In the application of the present invention, the Tg when the film is dried is preferably 110 ° C. or higher, more preferably 120 ° C. or higher.

  Accordingly, the glass transition temperature is preferably 190 ° C. or lower, more preferably 170 ° C. or lower. At this time, the Tg of the film can be determined by the method described in JIS K7121.

  It is preferable that the temperature during stretching is 150 ° C. or more and the stretching ratio is 1.15 times or more because the surface is appropriately roughened. Roughening the film surface is preferable because it improves not only the slipperiness but also the surface processability, particularly the adhesion of the hard coat layer. The arithmetic average roughness Ra is preferably 2.0 nm to 4.0 nm, more preferably 2.5 nm to 3.5 nm.

(Melting method)
The base film and the optical compensation film may be formed by a melt film forming method. The melt film-forming method refers to heating and melting a composition containing an additive such as a resin and a plasticizer to a temperature exhibiting fluidity, and then casting a melt containing a fluid cellulose ester.

  More specifically, the heat melting molding method can be classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like. Among these molding methods, the melt extrusion method is preferable from the viewpoint of mechanical strength and surface accuracy. It is preferable that a plurality of raw materials used for melt extrusion are usually kneaded in advance and pelletized.

  Pelletization may be performed by a known method. For example, dry cellulose ester, plasticizer, and other additives are fed to an extruder with a feeder and kneaded using a single-screw or twin-screw extruder, and formed into a strand from a die. It can be done by extrusion, water cooling or air cooling and cutting.

  The additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders.

  A small amount of additives such as particles and antioxidants are preferably mixed in advance in order to mix uniformly.

  The extruder is preferably processed at as low a temperature as possible so as to be able to be pelletized so that the shear force is suppressed and the resin does not deteriorate (decrease in molecular weight, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

  A film is formed using the pellets obtained as described above. Of course, the raw material powder can be directly fed to the extruder by a feeder without being pelletized to form a film as it is.

  Using a single or twin screw extruder, the pellets are melted at a temperature of about 200 to 300 ° C., filtered through a leaf disk filter, etc. to remove foreign matter, and then formed into a film from a T die. The film is nipped by a cooling roll and an elastic touch roll, and solidified on the cooling roll.

  When introducing from the supply hopper to the extruder, it is preferable to prevent oxidative decomposition or the like under vacuum, reduced pressure, or inert gas atmosphere.

  The extrusion flow rate is preferably performed stably by introducing a gear pump or the like. Further, a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances.

  The stainless steel fiber sintered filter is a united stainless steel fiber body that is intricately intertwined and compressed, and the contact points are sintered and integrated. The density of the fiber is changed depending on the thickness of the fiber and the amount of compression, and the filtration accuracy is improved. Can be adjusted.

  Additives such as plasticizers and particles may be mixed with the resin in advance, or 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.

  The film temperature on the touch roll side when the film is nipped between the cooling roll and the elastic touch roll is preferably Tg or more and Tg + 110 ° C. or less of the film. A well-known roll can be used for the roll which has the elastic body surface used for such a purpose.

  The elastic touch roll is also called a pinching rotator. As the elastic touch roll, a touch roll disclosed in registered patent 3194904, registered patent 3422798, Japanese Patent Laid-Open No. 2002-36332, Japanese Patent Laid-Open No. 2002-36333, or the like can be preferably used. These can also use what is marketed.

  When peeling the film from the cooling roll, it is preferable to control the tension to prevent deformation of the film.

  Moreover, it is preferable that the film obtained as described above is stretched by the stretching operation after passing through the step of contacting the cooling roll.

  As a method of stretching, a known roll stretching machine or tenter can be preferably used. The stretching temperature is usually preferably performed in the temperature range of Tg to Tg + 60 ° C. of the resin constituting the film.

  Prior to winding, the ends may be slit and cut to the width of the product, and knurling (embossing) may be applied to both ends to prevent sticking or scratching during winding. The knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressing. In addition, since the film has deform | transformed and cannot use as a product normally, the holding | grip part of the clip of both ends of a film is cut out and reused.

<Functional layer>
The hard coat film according to the present invention may be provided with functional layers such as an antistatic layer, a backcoat layer, an antireflection layer, a slippery layer, an adhesive layer, an antiglare layer, and a barrier layer.

<Back coat layer>
In the hard coat film according to the present invention, a back coat layer may be provided on the surface of the base film opposite to the side on which the hard coat layer is provided to prevent curling and sticking.

  As particles added to the backcoat layer, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, tin oxide, and oxide. Mention may be made of indium, zinc oxide, ITO, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate.

  The particles contained in the backcoat layer are preferably 0.1 to 50% by mass with respect to the binder. When the back coat layer is provided, the increase in haze is preferably 1.5% or less, more preferably 0.5% or less, and particularly preferably 0.1% or less.

  As the binder, a cellulose ester resin such as diacetylcellulose is preferable.

<Antireflection layer>
The hard coat film according to the present invention can be used as an antireflection film having an external light antireflection function by coating an antireflection layer on the hard coat layer.

  The antireflection layer is preferably laminated in consideration of the refractive index, the film thickness, the number of layers, the layer order, and the like so that the reflectance is reduced by optical interference. The antireflection layer is preferably composed of a low refractive index layer having a refractive index lower than that of the support, or a combination of a high refractive index layer having a refractive index higher than that of the support and a low refractive index layer. Particularly preferably, it is an antireflection layer composed of three or more refractive index layers, and three layers having different refractive indexes from the support side are divided into medium refractive index layers (high refractive index layers having a higher refractive index than the support). Are preferably laminated in the order of a layer having a lower refractive index) / a high refractive index layer / a low refractive index layer. Alternatively, an antireflection layer having a layer structure of four or more layers in which two or more high refractive index layers and two or more low refractive index layers are alternately laminated is also preferably used.

  As the layer structure of the antireflection film, the following structure is conceivable, but is not limited thereto.

Base film / hard coat layer / low refractive index layer Base film / hard coat layer / medium refractive index layer / low refractive index layer Base film / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index Layer Base film / hard coat layer / high refractive index layer (conductive layer) / low refractive index layer Base film / hard coat layer / antiglare layer / low refractive index layer Low refraction essential for antireflection film The refractive index layer preferably contains silica-based fine particles, and the refractive index thereof is lower than the refractive index of the substrate film as the support, and is in the range of 1.30 to 1.45 at 23 ° C. and a wavelength of 550 nm. Preferably there is.

  The film thickness of the low refractive index layer is preferably 5 nm to 0.5 μm, more preferably 10 nm to 0.3 μm, and most preferably 30 nm to 0.2 μm.

  The composition for forming a low refractive index layer preferably contains at least one kind of particles having an outer shell layer and porous or hollow inside as silica-based fine particles. In particular, the particles having the outer shell layer and having a porous or hollow interior are preferably hollow silica-based fine particles.

  The composition for forming a low refractive index layer may contain an organosilicon compound represented by the following general formula (OSi-1) or a hydrolyzate thereof, or a polycondensate thereof.

General formula (OSi-1): Si (OR) ₄
In the organic silicon compound represented by the general formula, R represents an alkyl group having 1 to 4 carbon atoms. Specifically, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and the like are preferably used.

  In addition, a silane coupling agent, a curing agent, a surfactant and the like may be added as necessary.

<Polarizing plate>
The long polarizing plate of the present invention using the hard coat film and the optical compensation film according to the present invention will be described. The polarizing plate can be produced by a general method. Hard coating film according to the present invention, the back side of the optical compensation film is subjected to alkali saponification treatment, the treated hard coating film, the optical compensation film on both sides so as to sandwich a polarizing film produced by immersing and stretching in an iodine solution, Bonding is preferably performed using a completely saponified polyvinyl alcohol aqueous solution.

  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 ones in which iodine is dyed on a system film and ones in which a dichroic dye is dyed, but it is not limited to this.

  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. A polarizing film having a thickness of 5 to 30 μm, preferably 8 to 15 μm, is preferably used.

<Protect film>
The polarizing plate of the present invention is prepared by laminating the hard coat film according to the present invention, a polarizing film, and the optical compensation film according to the present invention in this order, and further a protective film is stuck on the surface of the hard coat film side. It is a long polarizing plate wound up in a roll while being combined. The protective film is used for the purpose of protecting the polarizing plate by preventing a failure such as a scratch during shipment of the polarizing plate, product inspection, storage or transportation.

  Here, the long polarizing plate means a roll-shaped polarizing plate having a length of 100 m or more, and the longer the length is 1500 m, 2500 m, or 5000 m, the more the productivity at the time of manufacturing the polarizing plate is improved. A manufacturing effect can be obtained.

  For example, in the production of a hard coat film and an optical compensation film, 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. And a width suitable for the production 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 the film is manufactured and wound on a roll, it may be cut to obtain a roll having a desired width and used for processing such a roll-shaped polarizing plate.

  The material of the film used as the protective film is not particularly limited. For example, cellulose ester film, polyester film, polycarbonate film, polyarylate film, polysulfone (including polyethersulfone) film, polyethylene film , Polypropylene film, cellophane, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, norbornene resin film, polymethylpentene film, polyether ketone film, polyether ketone imide film, polyamide film , Fluorine resin film, nylon film, polymethylmethacrylate film, acrylic film And the like can be given. Of these, polycarbonate films and polyester films are preferable, and polyester films are particularly preferable.

  Although the polyester which comprises a polyester-type film is not specifically limited, It is preferable that it is polyester which has the film formation property which has a dicarboxylic acid component and a diol component as main structural components.

  The main constituent dicarboxylic acid components are terephthalic acid, isophthalic acid, phthalic acid, 2-6 naphthalene dicarboxylic acid, 2-7 naphthalene dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylethane dicarboxylic acid, cyclohexane dicarboxylic acid Examples include acid, diphenyldicarboxylic acid, diphenylthioether dicarboxylic acid, diphenylketone dicarboxylic acid, and phenylindane dicarboxylic acid. Examples of the diol component include ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyethoxyphenyl) propane, bis ( 4-hydroxyphenyl) sulfone, bisphenol full orange hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like.

  Among the polyesters having these as main components, from the viewpoint of transparency, mechanical strength, dimensional stability, etc., as dicarboxylic acid components, terephthalic acid and / or 2-6 naphthalenedicarboxylic acid, as diol components, ethylene glycol and Polyester having / or diethylene glycol as a main constituent component is preferable. Of these, polyesters mainly composed of polyethylene terephthalate or polyethylene 2-6 naphthalate, copolymer polyesters composed of terephthalic acid, 2-6 naphthalenedicarboxylic acid and ethylene glycol, and mixtures of two or more of these polyesters are mainly used. Polyester as a constituent component is preferable.

  The thickness of the polyester film used for this invention becomes like this. Preferably it is 70-150 micrometers, More preferably, it is 80-140 micrometers. When the protective film is less than 50 μm, the polarizing plate is wrinkled when the separate film is peeled off, and a bonding error tends to occur. On the other hand, when the thickness exceeds 200 μm, the polarizing plate is easily broken and wrinkled in the step of taking out the polarizing plate.

<Adhesive layer>
The pressure-sensitive adhesive layer used on one side of the polarizing plate protective film to be bonded to the substrate of the liquid crystal cell is preferably optically transparent and exhibits moderate viscoelasticity and adhesive properties.

  Specific examples of the adhesive layer include adhesives or adhesives such as acrylic copolymers, epoxy resins, polyurethane, silicone polymers, polyethers, butyral resins, polyamide resins, polyvinyl alcohol resins, and synthetic rubbers. A film such as a drying method, a chemical curing method, a thermal curing method, a thermal melting method, a photocuring method, or the like can be formed and cured using a polymer such as the above. Among them, the acrylic copolymer can be preferably used because it is most easy to control the physical properties of the adhesive and is excellent in transparency, weather resistance, durability and the like.

<Liquid crystal display device>
By incorporating the polarizing plate of the present invention produced using the hard coat film and retardation film according to the present invention into a display device, various image display devices with excellent visibility can be produced.

  The hard coat film according to the present invention is incorporated in a polarizing plate, and is a reflective type, transmissive type, transflective liquid crystal display device or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS. It is preferably used in liquid crystal display devices of various drive systems such as a type and an OCB type. Particularly, it is preferably used for a high contrast VA type (PVA type, MVA type) liquid crystal display device.

  Further, the backlight used in the liquid crystal display device of the present invention may be a sidelight type, a direct type, or a combination of these, but a direct type backlight improves contrast. From the viewpoint of A particularly preferred direct type backlight is an LED backlight for a color liquid crystal display device having a red (R) LED, a green (G) LED, and a blue (B) LED, for example, the peak of the red (R) LED. Preferably, the wavelength is 610 nm or more, the peak wavelength of the green (G) LED is in the range of 530 ± 10 nm, and the peak wavelength of the blue (B) LED is 480 nm or less. Examples of types of green (G) LEDs having a peak wavelength within the above range include DG1112H (manufactured by Stanley Electric Co., Ltd.), UG1112H (manufactured by Stanley Electric Co., Ltd.), and E1L51-3G (manufactured by Toyoda Gosei Co., Ltd.). E1L49-3G (manufactured by Toyoda Gosei Co., Ltd.), NSPG500S (manufactured by Nichia Chemical Co., Ltd.), and the like. The types of LEDs used as red (R) LEDs include, for example, FR1112H (manufactured by Stanley Electric Co., Ltd.), FR5366X (manufactured by Stanley Electric Co., Ltd.), NSTM515AS (manufactured by Nichia Corporation), GL3ZR2D1COS (Sharp) GM1JJ35200AE (manufactured by Sharp Corporation) and the like. As types of LEDs used as blue (B) LEDs, DB1112H (manufactured by Stanley Electric Co., Ltd.), DB5306X (manufactured by Stanley Electric Co., Ltd.), E1L51-3B (manufactured by Toyoda Gosei Co., Ltd.), E1L4E-SB1A (manufactured by Stanley Electric Co., Ltd.) Toyoda Gosei Co., Ltd.), NSPB630S (Nichia Chemical Co., Ltd.), NSPB310A (Nichia Chemical Co., Ltd.), and the like.

  The above-described three color LEDs can be combined to form a backlight. Alternatively, a white LED can be used.

  In addition, as a direct type backlight (or direct type), a direct type backlight using a point light source such as a direct type backlight described in JP-A No. 2001-281656 or an LED described in JP-A No. 2001-305535 is used. Light, a direct backlight described in JP-A-2002-311412, and the like can be mentioned, but not limited thereto.

  Even when such a backlight is used, a liquid crystal display device with high front contrast and excellent visibility can be obtained for a long period of time by using the long polarizing plate of the present invention.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
First, Table 1 shows resins used for producing the base film and the optical compensation film of this example.

<Preparation of base film 1 (cellulose triacetate film)>
<Preparation of ester compound 1>
251 g of 1,2-propylene glycol, 278 g of phthalic anhydride, 91 g of adipic acid, 610 g of benzoic acid, 0.191 g of tetraisopropyl titanate as an esterification catalyst, 2 L four-neck equipped with a thermometer, stirrer, and slow cooling tube The flask is charged and gradually heated with stirring until it reaches 230 ° C. in a nitrogen stream. The ester compound 1 was obtained by making it dehydrate-condense for 15 hours, and depressurizingly distilling unreacted 1, 2- propylene glycol at 200 degreeC after completion | finish of reaction. The acid value was 0.10 and the number average molecular weight was 450.

<Preparation of base film 1>
(Silicon dioxide dispersion)
Aerosil R812 (manufactured by Nippon Aerosil Co., Ltd.) 10 parts by mass (average diameter of primary particles 7 nm)
90 parts by mass of ethanol (silicon dioxide dispersion dilution)
Resin A (cellulose ester) was added to a dissolution tank containing methylene chloride and heated to completely dissolve, and this was then added to Azumi Filter Paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. Filtered using 244. While finely stirring the filtered cellulose ester solution, the fine particle dispersion was slowly added thereto. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle dispersion dilution.

(Dope solution 1)
90 parts by mass of resin A (cellulose triacetate synthesized from linter cotton, acetyl group substitution degree 2.88, Mn = 14000)
Ester compound 1 10 parts by weight Tinuvin 928 (manufactured by Ciba Japan Co., Ltd.) 2.5 parts by weight Silicon dioxide dispersion diluent 4 parts by weight Methylene chloride 432 parts by weight Ethanol 38 parts by weight While stirring, it completely dissolved, and Azumi Filter Paper No. 24, and the dope liquid 1 was prepared.

  Next, the belt casting apparatus was used to uniformly cast on a stainless steel band support. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100%, and the stainless steel band support was peeled off. The cellulose ester film web was evaporated at 35 ° C., slit to 1.6 m width, and stretched 1.1 times in the TD direction (the width direction of the film) with a tenter and the draw ratio in the MD direction was 1.05 times. While stretching, the film was dried at a drying temperature of 160 ° C. The residual solvent amount at the start of drying was 20%. Then, after being dried for 15 minutes while being transported in a drying device at 120 ° C. with a number of rolls, it is slit to 1.6 m width, subjected to knurling with a width of 15 mm and a height of 10 μm at both ends of the film, and wound around a core. The base film 1 was obtained. The residual solvent amount of the base film was 0.2%, the film thickness was 40 μm, and the winding number was 4000 m.

<Preparation of hard coat film 1>
On the produced base film 1, the following UV curable resin composition 1 filtered through a polypropylene filter having a pore size of 0.4 μm was applied to the surface of the base film 1 using a micro gravure coater, After drying at a constant rate drying zone temperature of 95 ° C. and a decreasing rate drying zone temperature of 95 ° C., the irradiance of the irradiated part is 100 mW using an ultraviolet lamp while purging with nitrogen so that the oxygen concentration becomes 1.0% by volume or less. / in cm ^2, thereby curing the coated layer to irradiation dose as 0.3 J / cm ^2, after forming the hard coat layer of the dry film thickness of 7 [mu] m, to prepare a hard coat film 1 of a roll wound.

<Preparation of fluorine-siloxane graft polymer>
The commercial name of the raw material used for the preparation of the fluorine-siloxane graft polymer is shown.

Radical polymerizable fluororesin (A): Cefal coat CF-803 (hydroxyl value 60, number average molecular weight 15,000; manufactured by Central Glass Co., Ltd.)
One-end radical polymerizable polysiloxane (B): Silaplane FM-0721 (number average molecular weight 5,000; manufactured by Chisso Corporation)
Radical polymerization initiator: Perbutyl O (t-butylperoxy-2-ethylhexanoate; manufactured by NOF Corporation)
Curing agent: Sumidur N3200 (biuret type prepolymer of hexamethylene diisocyanate; manufactured by Sumika Bayer Urethane Co., Ltd.)
(Synthesis of radical polymerizable fluororesin)
In a glass reactor equipped with a mechanical stirrer, thermometer, condenser and dry nitrogen gas inlet, cefal coat CF-803 (1554 parts by mass), xylene (233 parts by mass), and 2-isocyanatoethyl methacrylate (6 3 parts by mass) and heated to 80 ° C. in a dry nitrogen atmosphere. After reacting at 80 ° C. for 2 hours and confirming that the absorption of isocyanate disappeared by the infrared absorption spectrum of the sampled material, the reaction mixture was taken out to obtain 50% by mass of a radically polymerizable fluororesin via a urethane bond. .

(Preparation of fluorine-siloxane graft polymer)
In a glass reactor equipped with a mechanical stirrer, thermometer, condenser and dry nitrogen gas inlet, the above synthesized radical polymerizable fluororesin (26.1 parts by mass), xylene (19.5 parts by mass), acetic acid n-butyl (16.3 parts by mass), methyl methacrylate (2.4 parts by mass), n-butyl methacrylate (1.8 parts by mass), lauryl methacrylate (1.8 parts by mass), 2-hydroxyethyl methacrylate (1 .8 parts by mass), FM-0721 (5.2 parts by mass), and perbutyl O (0.1 parts by mass) were heated to 90 ° C. in a nitrogen atmosphere, and held at 90 ° C. for 2 hours. Perbutyl O (0.1 part) was added, and the solution was further maintained at 90 ° C. for 5 hours to obtain a 35 mass% fluorine-siloxane graft polymer solution having a weight average molecular weight of 171,000. The weight average molecular weight was determined by GPC. The mass% of the fluorine-siloxane graft polymer was determined by HPLC (liquid chromatography).

<Ultraviolet curable resin composition 1>
Pentaerythritol tri / tetraacrylate (denoted as PETA in the table: NK ester A-TMM-3L, manufactured by Shin-Nakamura Chemical Co., Ltd.) 100 parts by mass Irgacure 184 (manufactured by Ciba Japan Co., Ltd.) 5 parts by mass Fluoro-siloxane Graft polymer (35% by mass) 2 parts by mass Propylene glycol monomethyl ether (denoted as PGME in the table) 10 parts by mass Methyl acetate (denoted as MA in the table) 50 parts by mass Methyl ethyl ketone (denoted as MEK in the table) 50 parts by mass The viscosity at 25 ° C. of the ultraviolet curable resin was 600 mPa. The viscosity was measured using an E-type viscometer.

<Preparation of hard coat films 2-17>
<Preparation of base film 2-5>
Instead of the resin A used for the base film 1 shown in Table 1, the base films 2 to 5 having a film thickness of 40 μm and a winding number of 4000 m were obtained in the same manner as the base film 1 except that the resins B to D and I were used. Produced.

  For the base film 6, a commercially available PET film having a thickness of 40 μm (polyethylene terephthalate film: manufactured by Teijin DuPont) was used.

  Preparation of hard coat film 1 except that the base film, solvent composition, and UV curable resin listed in Table 2 were used instead of the base film, solvent composition, and UV curable resin used in hard coat film 1. In the same manner, hard coat films 2 to 17 were produced.

  The viscosity of the ultraviolet curable resin was measured in the same manner as described above, and the respective viscosities were measured and listed in Table 2.

  Abbreviations in Table 2 are as follows.

IPA: Isopropanol GTA: Glycerin triacrylate TMPTA: Trimethylolpropane triacrylate TMOPTA: Trimethylolpropane ethoxytriacrylate BOGA: Ethoxylated bisphenol A diacrylate HDDA: 1,6 hexanediol diacrylate DPTA: Ditrimethylolpropane tetraacrylate DPHA: KAYARAD DPHA (dipentaerythritol hexaacrylate made by Nippon Kayaku)
(Measurement of arithmetic average roughness Ra)
The hard coat layer surfaces of the prepared hard coat films 1 to 17 were measured 10 times using an optical interference type surface roughness meter (RST / PLUS, manufactured by WYKO), and each hard coat was determined from the average of the measurement results. The arithmetic average roughness Ra of the film was determined and listed in Table 2.

<Preparation of optical compensation film 101>
For the optical compensation film 101, cellulose esters D to H shown in Table 1 were used.

<Fine particle dispersion>
Fine particles (Aerosil R812 (Nippon Aerosil Co., Ltd.)) 11 parts by mass (average diameter of primary particles 16 nm, apparent specific gravity 90 g / liter)
89 parts by mass of ethanol or more was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle additive solution>
Cellulose ester D was added to a dissolution tank containing methylene chloride and heated to completely dissolve, and this was then added to Azumi filter paper No. 3 manufactured by Azumi Filter Paper Co., Ltd. Filtered using 244. While finely stirring the filtered cellulose ester solution, the fine particle dispersion was slowly added thereto. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.

Methylene chloride 99 parts by weight Cellulose ester D 4 parts by weight Fine particle dispersion 11 parts by weight A dope solution 2 having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose ester D was added to a pressurized dissolution tank containing a solvent while stirring. This was heated and stirred to completely dissolve, and a plasticizer and an ultraviolet absorber were further added and dissolved. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

  In addition to adding 100 parts by mass of the main dope solution and 5 parts by mass of the fine particle additive solution, mix thoroughly with an in-line mixer (Toray static type in-pipe mixer Hi-Mixer, SWJ), and then use a belt casting device to It was cast uniformly on a 2 m stainless steel band support.

  On the stainless steel band support, the solvent was evaporated until the residual solvent amount became 110%, and the stainless steel band support was peeled off. When peeling, the film is stretched so that the longitudinal (MD) stretch ratio is 1.1 times, and then both ends of the web are held by a tenter, and the stretch ratio in the width (TD) direction is 1.3. It extended | stretched so that it might become double. After stretching, hold for several seconds while maintaining its width, release the width holding after relaxing the tension in the width direction, further carry for 30 minutes in the third drying zone set at 125 ° C., and perform drying, An optical compensation film 1 having a thickness of 60 μm and a winding length of 4000 m having a knurling width of 1.6 m, an end portion having a width of 1 cm and a height of 8 μm was produced.

<Composition of dope solution 2>
Methylene chloride 390 parts by mass Ethanol 80 parts by mass Cellulose ester D 100 parts by mass Plasticizer: Sugar ester compound Compound 3 10 parts by mass Plasticizer: Aromatic terminal ester plasticizer (1) 2.5 parts by mass <Optical compensation film 102- Production of 108>
Optical compensation films 101 to 108 were produced in the same manner as described above except that the composition of the dope solution was changed as shown in Table 3.

  With respect to the obtained optical compensation films 101 to 108, the in-plane retardation value Ro, the retardation value Rt in the thickness direction, and the internal haze were measured by the following measurements.

<Measurement of retardation value>
Ro = (nx−ny) × d
Rt = ((nx + ny) / 2−nz) × d
(In the formula, nx, ny, and nz represent the refractive indexes in the principal axis x, y, and z directions of the refractive index ellipsoid, respectively, and nx and ny represent the refractive index in the film in-plane direction, and nz represents the thickness of the film. (The refractive index in the direction, nx> ny, and d represents the thickness (nm) of the film.)
Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), in a film that was allowed to stand for 24 hours in an environment of 23 ° C. and 55% RH, the retardation of the film at a wavelength of 590 nm was measured in the same environment. went.

(Measurement of internal haze)
Adhesive polyethylene terephthalate film with acrylic adhesive applied on both sides of the optical compensation film, and haze of optical compensation film according to JIS-K7136 (NDH2000; manufactured by Nippon Denshoku Industries Co., Ltd.) It measured using.

  Next, the haze of the polyethylene terephthalate film with an adhesive coated with an acrylic adhesive was measured using a haze meter.

  From the measured haze of the optical compensation film, the haze of the polyethylene terephthalate film with an adhesive coated with an acrylic adhesive was subtracted to determine the internal haze.

<Preparation of long polarizing plate 201>
(Alkaline saponification treatment)
A long polarizing plate 201 was prepared using one each of the hard coat film 1 and the optical compensation film 101 as a protective film for the polarizing plate.

(A) Production of Polarizing Film What was impregnated with 10 parts by mass of glycerin and 170 parts by mass of water in 100 parts by mass of polyvinyl alcohol (hereinafter abbreviated as PVA) having a saponification degree of 99.95 mol% and a polymerization degree of 2400. After melt-kneading and defoaming, it was melt-extruded from a T-die onto a metal roll to form a film. Thereafter, the PVA film obtained by drying and heat treatment had an average thickness of 25 μm, a moisture content of 4.4%, a film width of 1.6 m, and a length of 4000 m.

  Next, the obtained PVA film was continuously processed in the order of preliminary swelling, dyeing, uniaxial stretching by a wet method, fixing treatment, drying, and heat treatment to prepare a polarizing film. That is, the PVA film was preliminarily swollen in water at a temperature of 30 ° C. for 30 seconds, and immersed in an aqueous solution having an iodine concentration of 0.4 g / liter and a potassium iodide concentration of 40 g / liter at a temperature of 35 ° C. for 3 minutes. Subsequently, the film was uniaxially stretched 6 times in a 50% aqueous solution with a boric acid concentration of 4% under the condition that the tension applied to the film was 700 N / m, and the potassium iodide concentration was 40 g / liter and the boric acid concentration was 40 g / liter. Then, it was immersed in an aqueous solution having a zinc chloride concentration of 10 g / liter and a temperature of 30 ° C. for 5 minutes for fixing. Thereafter, the PVA film was taken out, dried with hot air at a temperature of 40 ° C., and further heat-treated at a temperature of 100 ° C. for 5 minutes. The obtained polarizing film had an average thickness of 13 μm, a polarizing performance of a transmittance of 43.0%, a polarization degree of 99.5%, and a dichroic ratio of 40.1.

(B) Production of Polarizing Plate According to the following steps 1 to 4, the long coat polarizing plate 201 was produced by laminating the hard coat film 1, the polarizing film, and the optical compensation film 101 by roll-to-roll.

  Process 1: The above-mentioned polarizing film was immersed for 1 to 2 seconds in the storage tank of the polyvinyl alcohol adhesive agent solution of 2 mass% of solid content.

  Step 2: The hard coat film 1 and the optical compensation film 101 were subjected to alkali saponification treatment under the following conditions. Next, excess adhesive adhered to the polarizing film immersed in the polyvinyl alcohol adhesive solution in Step 1 was lightly removed, and this polarizing film was sandwiched between the hard coat film 1 and the optical compensation film 101 and laminated and arranged.

(Alkaline saponification treatment)
Saponification step 2.5M-KOH 50 ° C. 120 seconds Water washing step Water 30 ° C. 60 seconds Neutralization step 10 parts by mass HCl 30 ° C. 45 seconds Water washing step Water 30 ° C. 60 seconds After saponification treatment, water washing, neutralization, water washing in this order And then dried at 100 ° C.

Step 3: The laminate was bonded at a speed of about 2 m / min at a pressure of ^{20 to} 30 N / cm ² with two rotating rollers. At this time, it was carried out with care to prevent bubbles from entering.

  Step 4: The sample prepared in Step 3 was dried in a dryer at a temperature of 100 ° C. for 5 minutes to prepare a polarizing plate.

  Step 5: A commercially available acrylic pressure-sensitive adhesive is applied to the optical compensation film 1 of the polarizing plate prepared in Step 4 so that the thickness after drying is 25 μm, and dried in an oven at 110 ° C. for 5 minutes to form an adhesive layer. Then, a peelable protective film was attached to the adhesive layer.

  The film was wound up in a roll while bonding a peelable protective film (PET) to the hard coat layer surface of the long polarizing plate. The winding length was 4000 m.

<Preparation of long polarizing plates 202 to 257>
In the production of the long polarizing plate 201, the long polarizing plates 202 to 257 were produced in the same manner except that the combination of the hard coat film 1 and the optical compensation film 101 was changed as shown in Tables 4 and 5. did.

<Production of Liquid Crystal Display Device 201>
Using the liquid crystal display panel used in the 32 type VA type liquid crystal display device, the polarizing plate on the viewing side and the backlight side, which had been pasted together, was peeled off, and the polarizing plate 201 produced was evaluated for the following deformation failure. After carrying out a durability test (stored at 80 ° C. and 90% for 240 hours), the roll-shaped long polarizing plate is drawn out, 20 arbitrary locations are cut out to a predetermined size, and the hard coat layer is The pressure-sensitive adhesive layer on the optical compensation film side and the liquid crystal cell glass were bonded so as to be on the viewing side. Further, a total of 20 liquid crystal display devices 201 were produced by bonding the polarizing plate 201 on the backlight side so that the absorption axis of the polarizing film was orthogonal so that the optical compensation film 101 side was the liquid crystal cell side. .

  As the backlight, a flat LED lamp: one having the structure shown in FIG. 9 described in JP-A-2006-148036 was used.

<Production of liquid crystal display devices 202 to 257>
20 liquid crystal display devices 202 to 257 were produced in the same manner except that the polarizing plate 201 was changed to the polarizing plates 202 to 257 in the production of the liquid crystal display device 201, respectively.

<Production of liquid crystal display devices 258 to 260>
A flat LED lamp that is a backlight used in the production of the liquid crystal display devices 242, 248, and 257: the configuration shown in FIG. 9 described in Japanese Patent Laid-Open No. 2006-148036 has a cold cathode tube that is an edge type conventional light source. Liquid crystal display devices 258 to 260 were fabricated in the same manner except that the configuration was changed to a comparative configuration (configuration of sidelight, light guide plate, and light diffusion plate).

<Evaluation>
The following evaluation was performed about the produced polarizing plates 201-257 and the liquid crystal display devices 201-260.

<Polarizer>
(Observation of deformation failure)
The produced roll-shaped long polarizing plates 201 to 257 were stored for 240 hours at 80 ° C. and 90%. The long polarizing plate subjected to the durability test was fed out and observed from the hard coat layer side, and the state of deformation failure was observed according to the following criteria.

A: Deformation failure is not observed at all. O: Deformation failure is observed in a small part, but there is no problem in actuality. Δ: Deformation failure is partially observed. There is a problem in actual harm ×: It can be seen that a partial deformation failure is clearly seen even from a distance.

<Liquid crystal display device>
(Evaluation of front contrast)
Measurement was performed after the backlights of 20 liquid crystal display devices were lit continuously for one week in an environment of 23 ° C. and 55% RH. For the measurement, ELDIM EZ-Contrast 160D was used to measure the luminance from the normal direction of the display screen of white display and black display on the liquid crystal display device, and the ratio was defined as the front contrast. The average value and variation of the front contrast were measured.

Front contrast = (brightness of white display measured from normal direction of display device) / (brightness of black display measured from normal direction of display device)
A: Variation in front contrast of 0 to less than 3% and almost no unevenness O: Variation in front contrast of less than 3 to 6% and slight variation Δ: Variation in front contrast of less than 6 to 10% The unevenness is slightly large. X: The front contrast is a variation of 10% or more, and the unevenness is large. The obtained results are shown in Tables 4 and 5 below.

  As can be seen from the results of Tables 4 and 5, the arithmetic average roughness Ra of the hard coat film surface is 2 to 20 nm, and the polarizing plate of the present invention in combination with the optical compensation film according to the present invention has a high temperature and high Excellent performance in both prevention of deformation failure when stored under humidity and both front contrast average value and front contrast variation when the polarizing plate after storage under high temperature and high humidity is incorporated into a liquid crystal display device. You can see that it works.

  Further, in the conventional liquid crystal display devices 258 to 260 having an edge type backlight using a cold cathode tube, the polarizing plates 242, 248 and 257 used were deformed, but the average front contrast of the liquid crystal display device was used. Because of the low value, the variation in front contrast was inconspicuous, and all were evaluated as good.

Example 2
In the production of the hard coat film 1, the ester compound 1 of the base film is changed to the ester compound B and the ester compound C described in Table 6, and the base films 7 and 8 are changed so as to change the tan δ in the width direction of the film. Produced. Next, the ultraviolet curable resin composition 1 was applied to these base films, and hard coat films 18 and 19 were produced in the same manner as the hard coat film 1. Polarizing plates 301 and 302 and liquid crystal display devices 301 and 302 were produced using the produced hard coat films 18 and 19 and the optical compensation film 105.

<Synthesis of ester compound B>
251 g of 1,2-propylene glycol, 370 g of adipic acid, 122 g of benzoic acid, and 0.09 g of tetraisopropyl titanate as an esterification catalyst were charged into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a quick cooling tube. The temperature is gradually raised with stirring until it reaches 230 ° C. in an air stream. The ester compound B was obtained by making it dehydrate-condense for 15 hours and distilling unreacted 1, 2- propylene glycol under reduced pressure at 200 degreeC after completion | finish of reaction. The acid value was 0.55 and the number average molecular weight was 500.

<Synthesis of ester compound C>
Using 570 parts (3.5 moles) of isophthalic acid, 305 parts (2.5 moles) of benzoic acid, 737 parts (5.5 moles) of dipropylene glycol, and 0.40 parts of tetraisopropyl titanate as a catalyst Then, while stirring in a nitrogen stream, a reflux condenser is attached to reflux excess monohydric alcohol, and heating is continued at 130 to 250 ° C. until the acid value becomes 2 or less. Removed. Subsequently, the distillate was removed under reduced pressure of 6.65 × 10 ³ Pa to 4 × 10 ² Pa or less at 200 to 230 ° C. to obtain an ester compound C. The acid value was 0.2 and the number average molecular weight was 491.

<Evaluation>
(Measurement of tan δ in the width direction of the base film)
The dynamic viscoelasticity of the base film was measured under the following conditions to determine tan δ ₋₄₀ / tan δ _peak . The sample used was conditioned at 23 ° C. and 55% RH for 24 hours in advance, and the humidity was 55% RH and the temperature was increased under the following conditions, or the temperature was set and measured.

Measuring device: RSA III manufactured by TI Instruments
Sample: width 5 mm, length 50 mm (gap set to 20 mm)
Measurement conditions: Tensile mode Measurement temperature: 25-210 ° C or -40 ° C
Temperature rising condition: 5 ° C / min
Frequency: 1Hz
In the durability test of the polarizing plate of Example 1, it evaluated similarly except having changed the storage time into 360 hours.

As can be seen from the results in Table 6, in a severe test, by using a base film having a tan δ in the width direction of 0.5 ≧ tan δ ₋₄₀ / tan δ _peak ≧ 0.23 as the hard coat film, An excellent deformation failure prevention effect can be obtained, and the front contrast and front contrast variation when used in a liquid crystal display device are also excellent.

Example 3
In the production of the hard coat film 1, the monofunctional acrylate is applied to the hard coat layer coating composition 1, and the kind and the total amount of acrylate are 100 parts by mass with respect to the polyfunctional acrylate (pentaerythritol tri / tetraacrylate). Hard coat films 20 to 30 were produced in the same manner except that the addition amount was changed as described in Table 7. Polarizers 401 to 411 and liquid crystal display devices 401 to 411 were produced using these produced hard coat films 20 to 30.

  In Table 7, the polyfunctional acrylate pentaerythritol tri / tetraacrylate is PETA, the monofunctional acrylate 2-hydroxypropyl acrylate (manufactured by Osaka Organic Chemical Co.) is HPA, and benzyl acrylate (manufactured by Osaka Organic Chemical Co., Ltd.). ) Was shown as BZA, and tetrahydrofurfuryl acrylate (Osaka Organic Chemical Co., Ltd.) was shown as THFA.

  Table 7 shows the viscosity at 25 ° C. of the ultraviolet curable resin either alone or in combination.

<Evaluation>
In the durability test of the polarizing plate of Example 1, it evaluated similarly except having changed the storage time into 480 hours. The results obtained are shown in Table 7.

  As can be seen from the results in Table 7, the monofunctional acrylate is contained on the base film, and the mass ratio of the polyfunctional acrylate to the monofunctional acrylate is polyfunctional acrylate: monofunctional acrylate = 80: 20 to 98: 2 It was found that by using the hard coat film provided with the hard coat layer for the polarizing plate and the liquid crystal display device of the present invention, even in a more severe durability test, particularly excellent performance for preventing deformation failure was exhibited. .

Claims (8)

A long polarizing plate having a polarizing film sandwiched between two protective films (A) and (B),
The protective film (A) has a hard coat layer containing a reaction product obtained by curing an ultraviolet curable resin having a viscosity at 25 ° C. of 300 to 700 mPa on the base film, and the arithmetic average roughness Ra of the surface (JIS B0601: 2001) is a hard coat film of 2 to 20 nm,
The protective film (B) is an ester compound in which at least one of cellulose acetate propionate and at least one of a pyranose structure or furanose structure is 1 to 12, and all or part of the OH groups of the structure are esterified. And an optical compensation film containing
Further, a long polarizing plate characterized in that a protective film is bonded to the surface of the hard coat film and wound into a roll.   The hard coat layer contains a polyfunctional acrylate and a monofunctional acrylate, and the mass ratio of the polyfunctional acrylate and the monofunctional acrylate is polyfunctional acrylate: monofunctional acrylate = 80: 20 to 98: 2. The polarizing plate according to claim 1.   The long polarizing film according to claim 1 or 2, wherein the base film contains a cellulose ester, and the cellulose ester has an acetyl substitution degree in the range of 2.8 to 3.0. Board. Tan-delta of the film width direction of the said base film has the following relationship, The elongate polarizing plate of any one of Claims 1-3 characterized by the above-mentioned.
0.5 ≧ tan δ ₋₄₀ / tan δ _peak ≧ 0.23
Here, tan δ _peak is a maximum value obtained by measuring a tan δ value of 25 ° C. to 210 ° C., and tan δ- ₄₀ is a value of tan δ at a temperature of −40 ° C. when tan δ _peak is indicated.   The base film contains a thermoplastic acrylic resin and a cellulose ester resin, and the mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is thermoplastic acrylic resin: cellulose ester resin = 95: 5 to 50:50. It exists, The elongate polarizing plate of any one of Claims 1-4 characterized by the above-mentioned. The long polarizing plate according to claim 1, wherein the optical compensation film satisfies the following formulas (I) and (II).
(I) 40 ≦ Ro ≦ 100 (nm)
(II) 90 ≦ Rt ≦ 300 (nm)
Ro = (nx−ny) × d
Rt = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the plane of the retardation film, ny is the refractive index in the direction perpendicular to the slow axis in the plane, nz is the refractive index in the thickness direction, and d is the refractive index in the thickness direction) Represents the thickness (nm) of the retardation film, and the refractive index is measured at 590 nm.)   A liquid crystal display device comprising a polarizing plate cut out from the long polarizing plate according to claim 1 in at least one of the liquid crystal cells.   The liquid crystal display device according to claim 7, wherein the liquid crystal display device has a direct type backlight.

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