WO2012133602A1

WO2012133602A1 - Polarizing plate and liquid crystal display device

Info

Publication number: WO2012133602A1
Application number: PCT/JP2012/058279
Authority: WO
Inventors: 公彦矢可部; 英樹松久
Original assignee: 住友化学株式会社
Priority date: 2011-03-25
Filing date: 2012-03-22
Publication date: 2012-10-04
Also published as: JP2012203211A; CN103443669A; KR102079894B1; CN103443669B; TW201303440A; KR20140029407A; KR20180132976A

Abstract

The present invention provides a polarizing plate formed by laminating protective films respectively on both surfaces of a polarizing film comprising a polyvinyl alcohol resin with adhesive layers lying respectively therebetween. The protective film on one of the surfaces is a stretched polyethylene terephthalate film that contains an ultraviolet-absorbing agent and that exhibits a light transmittance of 10% or less at a wavelength of 380nm, while the protective film on the other thereof exhibits a light transmittance of 60% or more at a wavelength of 320nm. Further, each adhesive layer comprises a cured product of an ultraviolet-curable resin composition that contains an epoxy compound. The polarizing plate exhibits excellent ultraviolet absorbance, excellent tight adhesion between the polarizing film and the protective films, high wet-heat resistance, and high productivity, with no damage to the surface appearance.

Description

Polarizing plate and liquid crystal display device

The present invention relates to a polarizing plate and a liquid crystal display device using the same.

In recent years, low-power consumption, low-voltage operation, lightweight and thin liquid crystal display devices are rapidly spreading as information display devices such as mobile phones, portable information terminals, computer monitors, and televisions. . Further, along with the development of the liquid crystal technology, liquid crystal display devices of various modes have been proposed, and the conventional problems of the liquid crystal display devices such as response speed, contrast, and viewing angle are being solved.

On the other hand, in response to strong market demands for further reduction in thickness and weight of liquid crystal display devices, liquid crystal panels, diffusion plates, backlight units, and drive ICs constituting liquid crystal display devices have been made thinner and smaller. Yes. Under such circumstances, it is required to reduce the thickness of the polarizing plate, which is a member constituting the liquid crystal panel, in units of 10 μm. In view of this, a triacetyl cellulose film generally used as a protective film for a polarizing plate has been replaced with a thinner one from the conventional 80 μm to 120 μm.

However, a polarizing plate using a triacetyl cellulose film as a protective film is often inferior in heat-and-moisture resistance and cold-heat shock resistance. In harsh environments, the polarizing performance may be deteriorated or the polarizing film may be damaged.

The reason why polarizing plates are often inferior in moisture and heat resistance is that the moisture permeability and water absorption rate of the triacetyl cellulose film that is a constituent element thereof are high. Therefore, in place of the triacetyl cellulose film, it has been studied to use a stretched polyethylene terephthalate film that is relatively low in moisture permeability and low in water absorption, corresponding to the above-mentioned thinning as a protective film (for example, JP2009-157348-). A).

However, the optical film used for the polarizing plate may need to absorb ultraviolet light for the purpose of preventing the liquid crystal and the polarizing film from being deteriorated by ultraviolet rays. However, an ordinary polyethylene terephthalate film has an ultraviolet absorbing ability for the polarizing plate. It may be insufficient as a protective film.

Therefore, an object of the present invention is a polarizing plate using a stretched polyethylene terephthalate film as a protective film, and has excellent ultraviolet absorption ability, excellent adhesion between the polarizing film and the protective film, high heat and humidity resistance, and appearance. It is providing the polarizing plate which is excellent also in productivity, without impairing. Another object of the present invention is to provide a liquid crystal display device having excellent environmental resistance using the polarizing plate.

The present invention includes the following.
[1] A polarizing plate comprising a polarizing film made of a polyvinyl alcohol-based resin and a protective film laminated on both surfaces of the polarizing film via an adhesive layer, wherein the protective film on one side contains an ultraviolet absorber In addition, it is made of a stretched polyethylene terephthalate film having a light transmittance of 10% or less at a wavelength of 380 nm, the protective film on the other surface has a light transmittance of 60% or more at a wavelength of 320 nm, and the adhesive layer contains an epoxy compound A polarizing plate comprising a cured product layer of an ultraviolet curable resin composition.

[2] The stretched polyethylene terephthalate film has an antiglare property, or an antiglare layer is laminated on the surface of the stretched polyethylene terephthalate film opposite to the surface to be bonded to the polarizing film. 1].

[3] The polarizing plate according to [1] or [2], wherein the protective film laminated on the surface of the polarizing film opposite to the stretched polyethylene terephthalate film is an optical compensation film.

[4] The protective film laminated on the side opposite to the stretched polyethylene terephthalate film of the polarizing film includes an adhesive layer on the side opposite to the side laminated on the polarizing film [1] to [3 ] The polarizing plate in any one of.

[5] A liquid crystal display device comprising a liquid crystal panel in which the polarizing plate according to [4] is bonded to a liquid crystal cell via the adhesive layer.

According to the present invention, it has excellent ultraviolet light absorption ability, and is excellent in adhesion between a polarizing film and a protective film made of a stretched polyethylene terephthalate film, and in durability under harsh environments, and without impairing the appearance. It is possible to provide an excellent polarizing plate. Moreover, according to this invention, the liquid crystal display device which is excellent in the environmental resistance using the said polarizing plate can be provided.

<Polarizing plate>
The polarizing plate of the present invention comprises a protective film formed by laminating a polarizing film made of a polyvinyl alcohol resin and an adhesive layer made of a cured product layer of an ultraviolet curable resin composition containing an epoxy compound on both sides thereof. The protective film on one side is a stretched polyethylene terephthalate film. This stretched polyethylene terephthalate film contains an ultraviolet absorber and has a light transmittance of 10% or less at 380 nm. Moreover, the other one side is provided with a protective film having a light transmittance of 320 nm of 60% or more. Hereinafter, the polarizing plate of the present invention will be specifically described.

(Polarizing film)
The polarizing film used in the present invention is usually a step of uniaxially stretching a polyvinyl alcohol resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with a dichroic dye, and dichroism. It is manufactured by a known method through a step of treating a polyvinyl alcohol-based resin film adsorbed with a dye with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution.

As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal modified with aldehydes, polyvinyl acetal, and the like can be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, and preferably about 1,500 to 5,000.

A film obtained by forming such a polyvinyl alcohol resin is used as an original film of a polarizing film. The method for forming the polyvinyl alcohol-based resin into a film is not particularly limited, and a known method is employed. The film thickness of the polyvinyl alcohol-based raw film can be, for example, about 10 μm to 150 μm.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after the dyeing of the dichroic dye. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, you may uniaxially stretch in these several steps.

In the uniaxial stretching, rolls having different peripheral speeds may be uniaxially stretched or may be stretched uniaxially using a hot roll. The uniaxial stretching may be dry stretching in which stretching is performed in the atmosphere, or may be wet stretching in which stretching is performed in a state where a solvent is used and the polyvinyl alcohol-based resin film is swollen. The draw ratio is usually about 3 to 8 times.

As a method of dyeing a polyvinyl alcohol resin film with a dichroic dye, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye is employed. Specifically, iodine or a dichroic dye is used as the dichroic dye. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. Further, the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C.
The immersion time (dyeing time) in this aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in this aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight and preferably about 1 × 10 ⁻³ to 1 part by weight per 100 parts by weight of water. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic dye solution used for dyeing is usually about 20 to 80 ° C. The immersion time (dyeing time) in this aqueous solution is usually about 10 to 1,800 seconds.

The boric acid treatment after dyeing with a dichroic dye can usually be performed by immersing the dyed polyvinyl alcohol resin film in a boric acid-containing aqueous solution.

The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight and preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight and preferably about 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., more preferably 60 to 80 ° C.

The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C. Further, the immersion time is usually about 1 to 120 seconds.

After washing with water, a drying process is performed to obtain a polarizing film. The thickness of the polarizing film is usually about 5 to 40 μm. The drying treatment can be performed using a hot air dryer or a far infrared heater. The temperature for the drying treatment is usually about 30 to 100 ° C, preferably 50 to 80 ° C. The drying treatment time is usually about 60 to 600 seconds, and preferably 120 to 600 seconds.

The moisture content of the polarizing film is reduced to a practical level by the drying treatment. The water content is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizing film is lost, and the polarizing film may be damaged or broken after drying. Moreover, when a moisture content exceeds 20 weight%, the thermal stability of a polarizing film may be inferior.

(Stretched polyethylene terephthalate film)
As the stretched polyethylene terephthalate film, one or more biaxially stretched films formed by melt extrusion of one or more polyethylene terephthalate resins, then longitudinally stretched, and then laterally stretched, or one or more polyethylene terephthalate-based films One or more uniaxially stretched films obtained by forming a resin film by melt extrusion and transversely stretching can be used.

Polyethylene terephthalate resin means a resin in which 80 mol% or more of repeating units are composed of ethylene terephthalate, and may contain other dicarboxylic acid components and diol components. Examples of other dicarboxylic acid components include isophthalic acid, 4,4′-dicarboxydiphenyl, 4,4′-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid, sebacic acid, 1,4 -Dicarboxycyclohexane etc. are mentioned.

Examples of other diol components include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like.

Each of these other dicarboxylic acid components and other diol components may be used alone or in combination with one or more other types. Further, hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid can be used in combination. Further, as other copolymerization components, dicarboxylic acids containing a small amount of amide bond (—NHCO—, etc.), urethane bond (—NHCOO—, etc.), ether bond (—O—), carbonate bond (—OCOO—), etc. An acid component or a diol component may be used.

Polyethylene terephthalate resin can be produced by direct polycondensation of terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as required), dialkyl esters of terephthalic acid and ethylene glycol (and if necessary) A method of transesterification with a dialkyl ester of another dicarboxylic acid or other diol), followed by polycondensation, ethylene glycol ester of terephthalic acid (and other dicarboxylic acids if necessary) (and other if necessary) The method of polycondensation of the diol ester) is employed.

The molecular weight of the polyethylene terephthalate resin is usually 0.45 to 1.0 dL when the resin is dissolved in a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) and expressed by intrinsic viscosity measured at 30 ° C. / G, preferably 0.50 to 1.0 dL / g, more preferably 0.52 to 0.80 dL / g. When the intrinsic viscosity is less than 0.45 dL / g, productivity at the time of film production may decrease, or the mechanical strength of the film may decrease. If the intrinsic viscosity exceeds 1.0 dL / g, the melt extrusion stability of the polymer in film production may be inferior.

In the polarizing plate of the present invention, the stretched polyethylene terephthalate film laminated on the polarizing film via an adhesive layer contains an ultraviolet absorber to prevent the polarizing film from being deteriorated by ultraviolet rays, and the light transmittance at 380 nm is 10 % Or less, preferably 5% or less. When the stretched polyethylene terephthalate film to be laminated has a light transmittance of 380 nm exceeding 10%, there is a possibility that sufficient ultraviolet absorbing ability cannot be exhibited.

The ultraviolet absorber contained in the stretched polyethylene terephthalate film used in the present invention is not particularly limited, but mainly includes an organic ultraviolet absorber and an inorganic ultraviolet absorber.

Examples of organic ultraviolet absorbers include salicylic acid ultraviolet absorbers such as phenyl salicylate, pt-butylphenyl salicylate, p-octylphenyl salicylate, and benzophenone ultraviolet absorbers such as 2- Hydroxy-4-benzyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy- 4-methoxybenzophenone, 2-2′-dihydroxy-4,4′-dimethoxybenzophenone, and the like, benzotriazole-based ultraviolet absorbers such as 2- (2′-hydroxy-5′-t-octylphenyl) -benzotriazole, 2- (2'-hydroxy-5 -T-octylphenyl) -benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'5'-di-t-butylphenyl) 5- Chlorobenzotriazole and the like; natural product-based ultraviolet absorbers such as oryzanol, shea butter, baicalin and the like; biological ultraviolet absorbers such as keratinocytes, melanin, and urocanic acid. These organic ultraviolet absorbers can be used alone or in combination of two or more. These organic ultraviolet absorbers can be used in combination with a hindered amine compound as an ultraviolet stabilizer.

Inorganic UV absorbers include titanium oxide, zinc oxide, indium oxide, tin oxide, talc, kaolin, calcium carbonate, titanium oxide-based composite oxide, zinc oxide-based composite oxide, ITO (tin-doped indium oxide), ATO (Antimony-doped tin oxide) and the like. Examples of the titanium oxide-based composite oxide include zinc oxide doped with silica and alumina. Each of these inorganic ultraviolet absorbers can be used in one kind, and can be used in combination with one or more other kinds. Moreover, you may use together an organic type ultraviolet absorber and an inorganic type ultraviolet absorber.

Further, the polyethylene terephthalate resin can contain additives other than the above-described ultraviolet absorber as necessary. Examples of the additive include a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, and an impact resistance improving agent. The amount added is preferably in a range that does not adversely affect the optical properties.

Polyethylene terephthalate resin is usually used in the form of pellets granulated by an extruder for blending such additives and for forming a film as described later. The size and shape of the pellet are not particularly limited, but are usually cylindrical, spherical, or flat spherical with a height and diameter of 5 mm or less.

The polyethylene terephthalate resin can be formed into a film and stretched to obtain a transparent and homogeneous polyethylene terephthalate film having high mechanical strength. As the manufacturing method, for example, the following method is adopted.

First, dried pellets made of polyethylene terephthalate resin are supplied to a melt-extrusion apparatus and heated to a melting point or higher to melt. Next, the melted resin is extruded from a die and rapidly cooled and solidified on the rotary cooling drum so that the temperature is equal to or lower than the glass transition temperature to obtain a substantially amorphous unstretched film. The melting temperature is appropriately determined according to the melting point of the polyethylene terephthalate resin and the extruder, but is usually 250 to 350 ° C.

In the polyethylene terephthalate resin, two or more kinds of resins having different resin structures and compositions may be mixed as necessary. For example, it is possible to use a mixture of pellets containing a particulate filler, an ultraviolet absorber, or an antistatic agent as an antiblocking agent, and non-compounded pellets.

Also, the number of laminated films to be extruded may be two or more if necessary. For example, a pellet containing a granular filler as an antiblocking agent and a non-compounded pellet are prepared and supplied to the same die from different extruders, consisting of two types and three layers of “filler blend / no blend / filler blend”. For example, extruding a film.

When obtaining a biaxially stretched film, the unstretched film is usually first stretched in the extrusion direction at a temperature equal to or higher than the glass transition temperature. The stretching temperature is usually 70 to 150 ° C, preferably 80 to 130 ° C, and more preferably 90 to 120 ° C. The draw ratio is usually 1.1 to 6 times, and preferably 2 to 5.5 times. If the draw ratio is less than 1.1, the strength in the longitudinal direction of the stretched polyethylene terephthalate film may be insufficient for practical use. Moreover, when it exceeds 6 times, the intensity | strength of a horizontal direction may be insufficient for practical use. This stretching can be completed once or divided into a plurality of times as necessary. Usually, even when stretching is performed a plurality of times, the total stretching ratio is preferably within the above range.

The longitudinally stretched film thus obtained can then be heat treated. Then, if necessary, relaxation treatment can be performed. This heat treatment temperature is usually 150 to 250 ° C., preferably 180 to 245 ° C., more preferably 200 to 230 ° C. The heat treatment time is usually 1 to 600 seconds, preferably 1 to 300 seconds, and more preferably 1 to 60 seconds.

The temperature of the relaxation treatment is usually 90 to 200 ° C., preferably 120 to 180 ° C. Further, the relaxation amount is usually 0.1 to 20%, preferably 2 to 5%.
More preferably, the temperature and amount of relaxation treatment are set such that the heat shrinkage rate at 150 ° C. of the polyethylene terephthalate film after the relaxation treatment is 2% or less.

When obtaining a biaxially stretched film, it is usually stretched in the transverse direction by a tenter after the longitudinal stretching treatment or after heat treatment or relaxation treatment as necessary. This stretching temperature is usually 70 to 150 ° C, preferably 80 to 130 ° C, and more preferably 90 to 120 ° C. The draw ratio is usually 1.1 to 6 times, and preferably 2 to 5.5 times.
If the draw ratio in the transverse drawing is less than 1.1 times, the strength in the transverse direction may be insufficient for practical use. Moreover, when this draw ratio exceeds 6 times, the balance of intensity | strength with a vertical direction will deteriorate, and it may not endure practical use.

After this, heat treatment and relaxation treatment can be performed as necessary. The heat treatment temperature is usually 150 to 250 ° C, preferably 180 to 245 ° C, and more preferably 200 to 230 ° C. The heat treatment time is usually 1 to 600 seconds, preferably 1 to 300 seconds, and more preferably 1 to 60 seconds.

The relaxation treatment temperature is usually 100 to 230 ° C, preferably 110 to 210 ° C, and more preferably 120 to 180 ° C. Further, the relaxation amount is usually 0.1 to 20%, preferably 1 to 10%, more preferably 2 to 5%. The temperature and amount of relaxation treatment are preferably set such that the amount of relaxation and the temperature during relaxation treatment are such that the heat shrinkage rate at 150 ° C. of the polyethylene terephthalate film after relaxation treatment is 2% or less.

In the uniaxial stretching and biaxial stretching treatments, when the stretching treatment temperature exceeds 250 ° C., the optical performance may be deteriorated due to thermal degradation of the resin or excessive crystallization. On the other hand, when the stretching treatment temperature is less than 70 ° C., excessive stress may be applied to stretching, or the film may solidify and stretching itself may be impossible.

Further, in the uniaxial stretching and biaxial stretching treatment, heat treatment can be performed again or the stretching treatment can be performed in order to relieve the distortion of the orientation main axis in the stretching direction as represented by bowing. The maximum value of the distortion with respect to the stretching direction of the orientation main axis due to bowing is usually within 45 °, but is preferably relaxed within 30 °, and more preferably within 15 °. When the maximum value of the distortion of the orientation main axis exceeds 45 °, when the polarizing plate is formed into a single sheet in a later process, optical characteristics may be nonuniform between the single sheets.

Here, the stretching direction means a direction in which the stretching ratio in the longitudinal stretching or the lateral stretching is large. In the biaxial stretching of a polyethylene terephthalate film, the transverse stretching ratio is usually slightly larger than the longitudinal stretching ratio. In this case, the stretching direction refers to a direction perpendicular to the longitudinal direction of the film. In uniaxial stretching, the film is generally stretched in the transverse direction as described above. In this case, the stretching direction is the direction perpendicular to the longitudinal direction.

Also, the orientation main axis means the molecular orientation direction at an arbitrary point on the stretched polyethylene terephthalate film. Moreover, the distortion with respect to the extending | stretching direction of an orientation main axis means the angle difference of an orientation main axis | shaft and an extending direction. Further, the maximum value is the maximum value in the direction perpendicular to the long direction.

The orientation main axis can be measured using, for example, a retardation film / optical material inspection apparatus RETS (manufactured by Otsuka Electronics Co., Ltd.) or a molecular orientation meter MOA (manufactured by Oji Scientific Instruments Co., Ltd.).

The stretched polyethylene terephthalate film can be easily obtained as a commercial product. For example, “Diafoil”, “Hostafan”, “Fusion” (above, manufactured by Mitsubishi Plastics, Inc.), “ Teijin Tetron Film, Melinex, Mylar, Teflex (made by Teijin DuPont Films Ltd.), Toyobo Ester Film, Toyobo Espet Film, Cosmo Shine, Crisper ( As described above, manufactured by Toyobo Co., Ltd., “Lumirror” (manufactured by Toray Film Processing Co., Ltd.), “Embron”, “Embret” (manufactured by Unitika Ltd.), “Skyroll” (manufactured by SKC) “Corfil” (manufactured by Kogo Co., Ltd.), “Zuitsu Polyester Film” (manufactured by Zuitsu), Li ester film "(Futamura Chemical Co., Ltd.) and the like. Among these, from the viewpoints of productivity and inexpensiveness, a biaxially stretched product is preferably used in the present invention.

(Coating layer)
The stretched polyethylene terephthalate film used in the present invention is preferably provided with a coating layer (an easy adhesion layer) having an adhesive function on the surface to be bonded to the polarizing film, as long as the effects of the present invention are not hindered. By forming the easy adhesion layer, the adhesion between the polarizing film and the stretched polyethylene terephthalate film can be improved.

The component constituting the easy-adhesion layer is not particularly limited. For example, a polyester resin, a urethane resin, or an acrylic resin having a polar group in the skeleton and a relatively low molecular weight and a low glass transition temperature. Examples thereof include resins. Moreover, a crosslinking agent, an organic or inorganic filler, a surfactant, a lubricant and the like can be contained as necessary.

The method for forming the easy-adhesion layer on a stretched polyethylene terephthalate film is not particularly limited. For example, a method for forming a stretched polyethylene terephthalate resin in a method in which all stretching steps are completed. For example, a method of forming between the longitudinal stretching and the transverse stretching step, a method of forming immediately before or after being bonded to the polarizing film, and the like are employed. Among these, from the viewpoint of productivity, a method in which a polyethylene terephthalate-based resin is formed after being longitudinally stretched and then stretched laterally is preferably employed.

The thickness of the easy-adhesion layer is usually 0.01 to 5 μm, preferably 0.03 to 0.6 μm, as the thickness after drying. If the thickness is less than 0.01 μm, the adhesion to the stretched polyethylene terephthalate film may be inferior. On the other hand, if the thickness exceeds 5 μm, the hydrophilicity of the coating layer becomes excessive and the water resistance of the laminate may be inferior.

The coating layer formed on the stretched polyethylene terephthalate film can be laminated with a functional layer other than the easy adhesion layer as long as the effects of the present invention are not hindered. Examples of the laminated functional layer include a conductive layer, a hard coat layer, a smoothing layer, an easy-sliding layer, and an anti-blocking layer.

(Give antiglare properties to stretched polyethylene terephthalate film)
The stretched polyethylene terephthalate film preferably has antiglare properties (haze) when the film is used on the viewing side of the polarizing plate. As a method for imparting antiglare properties, for example, a method of mixing inorganic fine particles or organic fine particles into the polyethylene terephthalate resin to form a film, or a method of producing the multilayer film, inorganic fine particles or organic fine particles are present on one side. A method of forming a stretched film from an unstretched film having a mixed layer is employed. In addition, the surface of the stretched polyethylene terephthalate film opposite to the surface to be bonded to the polarizing film is coated with a coating solution prepared by mixing inorganic fine particles or organic fine particles with a curable binder resin, and the binder resin is cured. Antiglare property can also be imparted by a method of laminating a glare layer.

Examples of the inorganic fine particles include silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, calcium carbonate, calcium phosphate, and the like. Examples of the organic fine particles include crosslinked polyacrylic acid particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles, and polyimide particles.

The haze value of a stretched polyethylene terephthalate film having antiglare properties or a film obtained by laminating an antiglare layer on a stretched polyethylene terephthalate film and imparting antiglare properties is preferably in the range of 3 to 45%. If the haze value is less than 3%, a sufficient antiglare effect may not appear. On the other hand, if it exceeds 45%, the screen of the liquid crystal display device using this film may be whitened, resulting in a decrease in image quality. This haze value can be measured using a haze / transmittance meter HM-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K 7136. In measuring the haze value, in order to prevent warping of the film, for example, a measurement sample in which the film surface is bonded to a glass substrate using an optically transparent adhesive so that the antiglare property-imparting surface becomes the surface. Is preferably used.

In addition, when a stretched polyethylene terephthalate film is used on the backlight side of the polarizing plate, the antiglare property may not be given. In this case, the haze value is usually less than 6%.

On the stretched polyethylene terephthalate film with antiglare properties, or on the stretched polyethylene terephthalate film with an antiglare layer laminated on it, a conductive layer, hard coat layer, low reflection layer, smooth Functional layers other than the anti-glare layer, such as a protective layer, an easy-sliding layer, and an anti-blocking layer, can be laminated. Moreover, as a resin composition (coating liquid) for forming the antiglare layer, a resin composition having any of these functions can also be selected.

When a functional layer such as the above-mentioned antiglare layer is laminated on the surface of the stretched polyethylene terephthalate film opposite to the surface to be bonded to the polarizing film, the functional layer of the stretched polyethylene terephthalate film is closely adhered to the functional layer. In order to improve the property, a coating layer similar to the above can be formed.

(Adhesive layer)
The adhesive layer with which the polarizing plate of this invention is provided is a layer which bears adhesion | attachment with a polarizing film and a protective film, and consists of a hardened | cured material layer of the ultraviolet curable resin composition containing an epoxy compound. By using an ultraviolet curable resin composition containing an epoxy compound, it becomes possible to improve the adhesion between the polarizing film and the protective film, and to make a solvent-free adhesive. Since the process of drying the agent layer is unnecessary, productivity can be improved. When an ultraviolet curable resin composition containing an epoxy compound is used as an adhesive, a polarizing film and a protective film are laminated via the adhesive, and then ultraviolet rays are laminated on the opposite side of the stretched polyethylene terephthalate film. By irradiating from the protective film surface side and hardening the said adhesive agent, the adhesive bond layer which consists of a hardened | cured material layer of the said ultraviolet curable resin composition is formed.

As the epoxy compound, an alicyclic epoxy compound can be preferably used. By using an ultraviolet curable resin composition containing an alicyclic epoxy compound as an adhesive, it is possible to further improve the adhesion between the polarizing film and the stretched polyethylene terephthalate film and the durability of the polarizing plate in a harsh environment. it can.

Here, the alicyclic epoxy compound is one having an epoxy group directly on the ring of the saturated cyclic compound, and a glycidyloxy group or epoxyethyl group bonded directly or via alkylene to the ring of the saturated cyclic compound. Say what you are. In addition, you may have another epoxy group in the structure.

An alicyclic epoxy compound having an epoxy group directly in the ring of a saturated cyclic compound is a base having a C—C double bond of a cyclic compound having a C—C double bond in the ring using a peroxide. It can be obtained by epoxidation under sexual conditions.

Examples of the cyclic compound having a C—C double bond in the ring include a compound having a cyclopentene ring, a compound having a cyclohexene ring, and a polycyclic compound thereof. The cyclic compound having a C—C double bond in the ring may have a C—C double bond outside the ring. Examples of such a compound include 1-vinyl-3-cyclohexene and monocyclic ring. Examples include limonene and α-pinene, which are monoterpenes of the formula.

Further, the alicyclic epoxy compound having an epoxy group directly on the ring of the saturated cyclic compound may be a compound having a structure obtained by dimerizing the epoxidized product obtained above through an appropriate functional group. Examples of the bond structure composed of the functional group include an ester bond (—COO—), an ether bond (—O—), and an alkylene bond (— (CH ₂ ) _n — etc., where n is an integer of 1 or more). Is mentioned. The dimerized structure of the epoxidized product may have a plurality of these bonds.

As a method for producing an alicyclic epoxy compound having an epoxy group directly on the ring of the saturated cyclic compound, for example, a method of epoxidizing after synthesizing a cyclic compound having a C—C double bond in the ring, A method of synthesizing a compound in which a C—C double bond is epoxidized into a target structure by further reacting a functional group as described above is employed. From the viewpoint of suppressing side reactions of epoxy groups and the like, usually, a method of epoxidizing after synthesizing a cyclic compound having a C—C double bond in the ring is preferably employed.

The method for synthesizing a cyclic compound having a C—C double bond in the ring varies depending on the skeleton of the target epoxy compound and is not particularly limited. For example, as a synthesis example of a dimerized cyclic compound, 3 An example is a method of obtaining 3-cyclohexenylmethyl 3-cyclohexenecarboxylate, which is an ester compound, by a Tishchenko reaction using a suitable catalyst from -cyclohexene-1-carboxaldehyde.

Further, the ester compound and a dicarboxylic acid compound or an ester thereof, a diol compound or an ester thereof, a polyalkylene glycol or an ester thereof, or a hydroxycarboxylic acid compound or an ester thereof, if necessary, are subjected to an ester exchange reaction. By doing so, a compound having a cyclohexenyl group at both ends is obtained.

Examples of dicarboxylic acid compounds and esters thereof include oxalic acid, adipic acid, sebacic acid, and dimethyl esters thereof. Examples of the diol compound and its ester include ethylene glycol, diethylene glycol, 1,2-propanediol, polyethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and dimethyl esters thereof. It is done. Examples of hydroxycarboxylic acid compounds and esters thereof include lactic acid, 3-hydroxybutyric acid, citric acid, and dimethyl esters and acetates thereof, lactide, propiolactone, butyrolactone, caprolactone, and the like.

An alicyclic epoxy compound having an epoxy group directly in the ring of the saturated cyclic compound is obtained by epoxidizing the cyclic compound having the C—C double bond thus obtained with a peroxide. be able to. Examples of the peroxide include hydrogen peroxide, peracetic acid, and tert-butyl hydroperoxide.

As an alicyclic epoxy compound having an epoxy group directly on the ring of a saturated cyclic compound preferably used in an adhesive comprising an ultraviolet curable resin composition, for example, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxy 1,2-epoxy-4-vinylcyclohexane, 1,2-epoxy-1-methyl-4- (1-methylepoxyethyl) cyclohexane, 3,4-epoxycyclohexylmethyl methacrylate, 2,2-bis ( 4- (1,2-epoxyethyl) -1,2-epoxycyclohexane adduct of hydroxymethyl) -1-butanol, ethylene bis (3,4-epoxycyclohexanecarboxylate), oxydiethylene bis (3,4-epoxy Cyclohexanecarboxylate , 1,4-cyclohexane dimethyl bis (3,4-epoxycyclohexane carboxylate), 3- (3,4-epoxycyclohexyl-methoxycarbonyl) propyl 3,4-epoxycyclohexane carboxylate and the like.

An alicyclic epoxy compound in which a glycidyloxy group or an epoxyethyl group is bonded to a ring of a saturated cyclic compound directly or via alkylene has a hydrogenated aromatic ring of a glycidyl etherified aromatic compound having a hydroxyl group described later. A glycidyl etherified product of a saturated cyclic compound having a hydroxyl group, an epoxidized product of a saturated cyclic compound having a vinyl group, and the like.

Examples of the glycidyl etherified product of an aromatic compound having a hydroxyl group include glycidyl etherified products of bisphenol A and oligomers thereof, and glycidyl etherified products of bisphenol F and oligomers thereof. Bisphenol A and bisphenol F, which are precursors of these aromatic glycidyl ether compounds, are selectively subjected to nuclear hydrogenation under pressure in the presence of a catalyst, and the resulting hydrogenated bisphenol A and hydrogenated bisphenol F are then epichloroform. When hydrin is reacted, an alicyclic epoxy compound in which a glycidyloxy group is directly bonded to the ring of the saturated cyclic compound is obtained.

Examples of the glycidyl etherified product of a saturated cyclic compound having a hydroxyl group include 1,4-cyclohexanedimethanol diglycidyl ether and the like.

Examples of the epoxidized product of a saturated cyclic compound having a vinyl group include 1,3-bis (epoxyethyl) cyclohexane, 1,2,4-tris (epoxyethyl) cyclohexane, and 2,4-bis (epoxyethyl) -1. -Vinylcyclohexane etc. are mentioned.

Among the alicyclic epoxy compounds described above, 3,4-epoxy has good cured product characteristics for improving the durability of the polarizing plate, or has moderate curability and is available at a relatively low price. A glycidyl etherified product of cyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and hydrogenated bisphenol A is preferred, and 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate is more preferred.

Each of these alicyclic epoxy compounds may be used alone or in combination with one or more other.

Such alicyclic epoxy compounds can be easily obtained as commercial products. For example, “Celoxide”, “Cyclomer” (manufactured by Daicel Chemical Industries, Ltd.), “ And “Syra Cure” (manufactured by Dow Chemical Co., Ltd.).

In the adhesive comprising the ultraviolet ray curable resin composition, an ultraviolet curable compound other than the alicyclic epoxy compound can be blended. As such an ultraviolet curable compound, epoxy compounds other than an alicyclic epoxy compound can be used. By using together an epoxy compound other than the alicyclic epoxy compound, the adhesion between the polarizing film and the stretched polyethylene terephthalate film can be further improved.

Examples of the epoxy compound other than the alicyclic epoxy compound include a glycidyl etherified product of an aromatic compound or a chain compound having a hydroxyl group, a glycidyl aminated product of a compound having an amino group, and a chain shape having a C—C double bond. Examples thereof include epoxidized compounds.

The glycidyl etherified product of an aromatic compound or chain compound having a hydroxyl group is obtained by addition condensation of a compound such as epichlorohydrin to the hydroxyl group of the aromatic compound or chain compound under alkaline conditions. For example, bisphenol type epoxy resin, polyaromatic ring type epoxy resin, alkylene glycol type epoxy resin and the like can be mentioned.

Examples of the bisphenol-type epoxy resin include glycidyl etherified products of bisphenol A and oligomers thereof, glycidyl etherified products of bisphenol F and oligomers thereof, and 3,3 ′, 5,5′-tetramethyl-4,4′- Examples thereof include glycidyl etherified products of biphenol and oligomers thereof.

Examples of the polyaromatic epoxy resin include glycidyl etherified products of phenol novolac resins, glycidyl etherified products of cresol novolac resins, glycidyl etherified products of phenol aralkyl resins, glycidyl etherified products of naphthol aralkyl resins, and phenol dicyclopentadiene resins. And glycidyl etherified products. Furthermore, a glycidyl etherified product of trihydroxyphenylmethane and an oligomer thereof, a glycidyl etherified product of trisphenol PA and an oligomer thereof, and the like are also included.

Examples of the alkylene glycol type epoxy resin include glycidyl etherified product of ethylene glycol, glycidyl etherified product of diethylene glycol, glycidyl etherified product of 1,4-butanediol, glycidyl etherified product of 1,6-hexanediol, and the like. .

The glycidyl aminated product of a compound having an amino group is obtained by addition condensation of a compound such as epichlorohydrin to the amino group under basic conditions.
The compound having an amino group may have a hydroxyl group at the same time. For example, glycidyl amination product of 1,3-phenylenediamine and oligomer thereof, glycidyl amination product and oligomer of 1,4-phenylenediamine, glycidyl amination and glycidyl etherification product of 3-aminophenol and oligomer thereof And glycidyl amination and glycidyl etherification products of 4-aminophenol and oligomers thereof.

An epoxidized product of a chain compound having a CC double bond is an epoxidation of a CC compound of a chain compound having a CC double bond under basic conditions using a peroxide. It is obtained by making it. Examples of the chain compound having a C—C double bond include butadiene, polybutadiene, isoprene, pentadiene, hexadiene and the like. Terpenes having a double bond are also used. For example, linacole etc. are mentioned as an acyclic monoterpene. Examples of the peroxide include hydrogen peroxide, peracetic acid, tert-butyl hydroperoxide, and the like.

These epoxy compounds other than these alicyclic epoxy compounds and oligomers thereof may be used alone or in combination with one or more other compounds.

Epoxy compounds other than such alicyclic epoxy compounds, oligomers thereof, and the like can be easily obtained from commercial products. For example, “Epicoat” (manufactured by Japan Epoxy Resin Co., Ltd.) under the trade name. , “Epiclon” (manufactured by DIC Corporation), “Epototo” (manufactured by Toto Kasei Co., Ltd.), “Adeka Resin” (manufactured by ADEKA Corporation), “Denacol” (manufactured by Nagase ChemteX Corporation), “Dow Epoxy” (Dow Chemical Co., Ltd.) Product), “Tepic” (manufactured by Nissan Chemical Industries, Ltd.) and the like.

The epoxy equivalent of the epoxy compound used in the present invention is usually 30 to 2,000 g / eq, preferably 50 to 1,500 g / eq, and more preferably 70 to 1,000 g / eq. . When the epoxy equivalent is less than 30 g / eq, the flexibility of the adhesive layer may be lowered or the adhesive strength may be lowered. On the other hand, if it exceeds 2,000 g / eq, the curing rate may decrease, or the rigidity and strength required for the cured adhesive layer may be insufficient. This epoxy equivalent is a value measured according to JIS K 7236 (ISO 3001).

Also, an oxetane compound can be used as an ultraviolet curable compound other than the alicyclic epoxy compound. By using the oxetane compound in combination, the curing rate of the ultraviolet curable resin composition can be improved.

The oxetane compound is a compound having an oxetane ring and is not particularly limited as long as it is ultraviolet curable. For example, 1,4-bis {[(3-ethyloxetane-3-yl) methoxy] Methyl} benzene, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, bis (3-ethyl-3-oxetanylmethyl) ether, 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl-3 -(Cyclohexyloxymethyl) oxetane, phenol novolac oxetane, 1,3-bis [(3-ethyloxetane-3-yl) methoxy] benzene and the like.

The oxetane compound can be easily obtained as a commercial product. Examples thereof include “Aron Oxetane” (manufactured by Toagosei Co., Ltd.), “ETERRNACOLL” (manufactured by Ube Industries, Ltd.), and the like. .

The compounding ratio of the alicyclic epoxy compound in the ultraviolet curable resin composition is 100 parts by weight in total of the ultraviolet curable compound (alicyclic epoxy compound, epoxy compound other than the alicyclic epoxy compound and oxetane compound). The alicyclic epoxy compound is preferably 30 to 95 parts by weight, more preferably 50 to 90 parts by weight, and even more preferably 70 to 85 parts by weight. When 30 parts by weight or more of the alicyclic epoxy compound is blended with respect to 100 parts by weight of the total amount of the ultraviolet curable compound, the effect of improving the durability of the polarizing plate adhered by the cured product of the ultraviolet curable resin composition is improved. is there. Moreover, when it exceeds 95 weight part, the toughness of a hardened | cured material layer may be inferior, or the cure rate of an ultraviolet curable resin composition may fall.

It is preferable to use a compound that is not diluted with an organic solvent or the like as the ultraviolet curable compound. In addition, in a small amount of components such as a photopolymerization initiator and a sensitizer constituting the active energy ray-curable resin composition described later, the compound in which the organic solvent is removed and dried rather than the one dissolved in the organic solvent It is preferable to use a single powder or liquid.

The ultraviolet curable resin composition containing an epoxy compound used in the present invention is a curable composition that is cured by irradiation with ultraviolet rays and gives an adhesive force to films that sandwich the cured product layer. The ultraviolet curable resin composition containing an epoxy compound preferably contains a cationic polymerization initiator.

The cationic polymerization initiator is a substance that generates a cationic species or a Lewis acid by irradiation with ultraviolet rays and initiates an epoxy group polymerization reaction. This cationic polymerization initiator is preferably provided with latency. By providing the latency, the usable time of the ultraviolet curable composition used in the present invention is prolonged, and the workability is also improved.

The compound that generates a cationic species or a Lewis acid upon irradiation with ultraviolet rays is not particularly limited, and examples thereof include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; and iron-allene. A complex etc. can be mentioned.

Examples of the aromatic diazonium salt include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, benzenediazonium hexafluoroborate, and the like.

Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.

Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate, 4,4′-bis [diphenylsulfonio] diphenyl sulfide, bishexafluorophosphate, 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide, bishexafluoroantimonate, 4,4′-bis [Di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluorophosphate, 7- [di (p-toluyl) sulfur Honio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenyl sulfide Hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4′-diphenylsulfonio-diphenyl sulfide Hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4′-di (p-toluyl) ) Sulfonio-diphenyl sulfide, tetrakis (pentafluorophenyl) borate and the like.

Examples of iron-allene complexes include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II) -tris. And (trifluoromethylsulfonyl) methanide.

Each of these cationic polymerization initiators may be used alone or in combination with one or more other. Among them, aromatic sulfonium salts are particularly preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and therefore can provide a cured layer having excellent curability and good mechanical strength and adhesive strength. .

The compounding amount of the cationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the total amount of the ultraviolet curable compound. If the amount is less than 0.5 parts by weight, curing may be insufficient, and the mechanical strength and adhesive strength of the cured product layer may be reduced. On the other hand, when the amount exceeds 20 parts by weight, the ionic substance in the cured product layer is increased, so that the hygroscopic property of the cured product layer is increased, and the durability performance of the obtained polarizing plate may be lowered.

These cationic polymerization initiators can be easily obtained from commercial products, for example, “Kayarad” (manufactured by Nippon Kayaku Co., Ltd.), “Syracure” (manufactured by Union Carbide), Photoacid generator “CPI” (manufactured by San Apro Co., Ltd.), photoacid generators “TAZ”, “BBI”, “DTS” (manufactured by Midori Chemical Co., Ltd.), “Adekaoptomer” (manufactured by ADEKA Corporation) , “RHODORSIL” (manufactured by Rhodia) and the like.

Various additives can be added to the ultraviolet curable resin composition as long as the effects of the present invention are not impaired. Examples of the additive include an ion trap agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, and an antifoaming agent. Examples of the ion trapping agent include inorganic compounds such as powdered bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based, and mixed systems thereof. Examples of the antioxidant include hindered phenol antioxidants.

The viscosity at 25 ° C. of the ultraviolet curable resin composition before curing is not particularly limited as long as it is a viscosity that can be applied to the film by an appropriate method, but a range of 10 to 30,000 mPa · s is preferable, A range of 50 to 6,000 mPa · s is more preferable. If the viscosity of the active energy ray-curable resin composition is less than 10 mPa · s, the apparatus that can be applied is limited, and even if it can be applied, a uniform coating without unevenness may not be obtained. On the other hand, if it exceeds 30,000 mPa · s, it is difficult to flow, so that the apparatus that can be applied in the same way is limited, and a uniform coating film without unevenness may not be obtained. The viscosity of the active energy ray-curable resin composition is a value measured at 60 rpm after the composition is adjusted to 25 ° C. using a B-type viscometer.

The adhesive layer provided on both surfaces of the polarizing film may use the same type of ultraviolet curable resin composition, or may use different types of ultraviolet curable resin compositions. When the same ultraviolet curable resin composition is used, the process is simple because only one type of adhesive is required.

As a method for forming the adhesive layer (adhesive layer before curing) made of the ultraviolet curable resin composition shown above on the polarizing film or the protective film to be laminated, for example, the polarizing film or the laminated protective film is used. A method of coating the composition on a film, a method of spraying the composition, a method of pasting the composition previously formed into a film, and the like are employed. Among them, the method of applying the composition or the method of pasting the film-like composition is preferable because of relatively high uniformity of the coating film, and the method of applying the composition is more highly productive. preferable.

As a coating method, for example, a die coater, a comma coater, a reverse roll coater, a gravure coater, a rod coater, a wire bar coater, a doctor blade coater, an air doctor coater, or the like is employed.

The thickness of the adhesive layer is usually 0.1 to 20 μm, preferably 0.2 to 10 μm, and more preferably 0.5 to 5 μm. When the thickness is less than 0.1 μm, the adhesion between the polarizing film by the cured adhesive layer and the protective film to be laminated may be insufficient. Further, if the thickness exceeds 20 μm, the curing of the adhesive layer may not proceed sufficiently, or even if cured, the flexibility of the film may deteriorate due to the thickness, or the effect of thinning may not be obtained. .

The polarizing plate of the present invention can be obtained by irradiating the laminate of the polarizing film and the protective film laminated via the adhesive layer with ultraviolet rays and curing the adhesive layer.

Examples of the light source include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps having a light emission distribution at a wavelength of 400 nm or less.

The irradiation intensity is determined by the ultraviolet curable resin composition and the irradiation time, and is not particularly limited. For example, the irradiation intensity in the wavelength region effective for activating the initiator is 0.1 to It is preferably 1000 mW / cm ² .

The irradiation time is determined by the active energy ray-curable resin composition and the irradiation intensity, and is not particularly limited. For example, the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to It is preferably set to be 2,000 mJ / cm ² . When the cumulative amount of light to the active energy ray-curable resin composition is less than 10 mJ / cm ² , the generation of active species derived from the initiator is not sufficient, and the resulting adhesive layer may be insufficiently cured. .
Moreover, when it exceeds 2,000 mJ / cm < ² >, deterioration of a protective film, an ultraviolet curable adhesive, and a polarizing film may arise with the irradiated ultraviolet-ray.

(Protective film, optical compensation film)
The polarizing plate of the present invention is a protective film having a light transmittance of 60% or more in the range of 320 nm through an adhesive layer on the surface opposite to the surface on which the stretched polyethylene terephthalate film of the polarizing film is laminated. Alternatively, an optical compensation film is provided.

As the protective film or the optical compensation film, as long as the light transmittance in the above-mentioned range of 320 nm satisfies 60% or more, those having optical properties as an optical film can be used as appropriate according to the purpose, and particularly limited. Although it is not, as a protective film, transparent, such as a cellulose resin film which consists of triacetyl cellulose (TAC) etc., an olefin resin film, an acrylic resin film, a polycarbonate resin film, a polyester resin film etc., for example A film is mentioned.

Further, as the optical compensation film, those obtained by stretching the film mentioned as the protective film to give refractive index anisotropy, those containing an optical anisotropy imparting additive, and optical anisotropy on the surface Examples include those having a layer formed.

Further, as described later, these protective films or optical compensation films can be laminated with an optical functional film or coated with an optical functional layer.

Also, the protective film or the optical compensation film can be laminated with an optical functional film or coated with an optical functional layer, as will be described later.

The cellulose-based resin film is a film composed of a cellulose part or a completely esterified product, and examples thereof include a film composed of cellulose acetate ester, propionate ester, butyrate ester, mixed ester thereof and the like. Among these, a triacetyl cellulose film, a diacetyl cellulose film, a cellulose acetate propionate film, and a cellulose acetate butyrate film are preferably used.

The olefin resin film is a film made of a resin obtained by polymerizing a chain olefin monomer such as ethylene and propylene, or a cyclic olefin monomer such as norbornene and other cyclopentadiene derivatives using a polymerization catalyst. is there.

Examples of the olefin resin composed of a chain olefin monomer include polyethylene or polypropylene resin. Among these, a polypropylene resin made of a homopolymer of propylene is preferable. Also preferred is a polypropylene resin in which propylene is the main component and a comonomer copolymerizable therewith is usually copolymerized in a proportion of 1 to 20% by weight, preferably 3 to 10% by weight.

As the comonomer copolymerizable with propylene, ethylene, 1-butene, or 1-hexene is preferable. Among these, ethylene copolymerized at a ratio of 3 to 10% by weight is preferable because of relatively excellent transparency and stretch processability. By making the copolymerization ratio of ethylene 1% by weight or more, an effect of improving transparency and stretch processability appears. On the other hand, when the ratio exceeds 20% by weight, the melting point of the resin is lowered, and the heat resistance required for the protective film and the optical compensation film may be impaired.

An olefin resin obtained by polymerizing a cyclic olefin monomer is generally referred to as a cyclic (poly) olefin resin, an alicyclic (poly) olefin resin, or a norbornene resin. Here, it is called a cyclic olefin resin.

Examples of the cyclic olefin-based resin include a resin obtained by performing ring-opening metathesis polymerization from cyclopentadiene and olefins using norbornene obtained by Diels-Alder reaction or a derivative thereof as a monomer, followed by hydrogenation; dicyclopentadiene and Resins obtained by ring-opening metathesis polymerization from olefins or methacrylic acid esters using tetracyclododecene or derivatives thereof obtained by Diels-Alder reaction and subsequent hydrogenation; norbornene, tetracyclododecene, them A resin obtained by carrying out ring-opening metathesis copolymerization using two or more of these derivatives or other cyclic olefin monomers in the same manner and subsequent hydrogenation; norbornene, tetracyclododece , Derivatives thereof, and resins obtained by addition copolymerization of an aromatic compound having a vinyl group.

Such a cyclic olefin-based resin can be easily obtained as a commercial product. For example, under the trade name, “Topas” (Topas Advanced Polymers GmbH), “Arton” (manufactured by JSR Corporation), “Zeonor”, “Zeonex” (manufactured by ZEON CORPORATION), “Apel” (manufactured by Mitsui Chemicals, Inc.), and the like.

Preferable specific examples of the acrylic resin film include a film made of a methyl methacrylate resin. The methyl methacrylate resin is a polymer containing 50% by weight or more of methyl methacrylate units. The content of methyl methacrylate units is preferably 70% by weight or more, and may be 100% by weight. The polymer having a methyl methacrylate unit of 100% by weight is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.

This methyl methacrylate-based resin is usually a monofunctional monomer mainly composed of methyl methacrylate and a polyfunctional monomer used as necessary, as a radical polymerization initiator and as required. It can be obtained by polymerization in the presence of a chain transfer agent.

Monofunctional monomers that can be copolymerized with methyl methacrylate include, for example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxy methacrylate. Methacrylic acid esters other than methyl methacrylate such as ethyl; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, etc. Acrylic acid esters of: 2- (hydroxymethyl) methyl acrylate, 3- (hydroxyethyl) methyl acrylate, 2- (hydroxymethyl) ethyl acrylate, 2- (hydroxymethyl) acrylic acid Hydroxyacrylic esters such as chill; Unsaturated acids such as methacrylic acid and acrylic acid; Halogenated styrenes such as chlorostyrene and bromostyrene; Substituted styrenes such as vinyltoluene and α-methylstyrene; Acrylonitrile and methacrylonitrile Unsaturated nitriles such as maleic anhydride, unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride, and unsaturated imides such as phenylmaleimide and cyclohexylmaleimide. Each of these monomers may be used alone or in combination with one or more other monomers.

Examples of polyfunctional monomers that can be copolymerized with methyl methacrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and tetraethylene glycol di (meth) acrylate. , Ethylene glycol such as nonaethylene glycol di (meth) acrylate, tetradecaethylene glycol (meth) acrylate, etc., and both terminal hydroxyl groups of oligomers thereof esterified with acrylic acid or methacrylic acid; both terminal hydroxyl groups of propylene glycol or oligomers thereof Esterified with acrylic acid or methacrylic acid; neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, butanediol di (meth) a Esterification of hydroxyl groups of dihydric alcohols such as relates with acrylic acid or methacrylic acid; Bisphenol A, alkylene oxide adducts of bisphenol A, or both terminal hydroxyl groups of these halogen-substituted products are esterified with acrylic acid or methacrylic acid Those obtained by esterifying polyhydric alcohols such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid, and those obtained by ring-opening addition of epoxy groups of glycidyl acrylate or glycidyl methacrylate to the terminal hydroxyl groups; succinic acid, Ring opening of glycidyl acrylate or glycidyl methacrylate epoxy group to adipic acid, terephthalic acid, phthalic acid, dibasic acids such as halogen substitution products, and alkylene oxide adducts Those were; aryl (meth) acrylate; diaryl compounds such as divinylbenzene, and the like. Among these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and neopentyl glycol dimethacrylate are preferably used.

The methyl methacrylate resin may be a modified methyl methacrylate resin modified by performing a reaction between functional groups of the resin. As the reaction, for example, demethanol condensation reaction in a polymer chain between a methyl ester group of methyl acrylate and a hydroxyl group of 2- (hydroxymethyl) methyl acrylate, and a carboxyl group of acrylic acid and 2- (hydroxymethyl) ) Intrapolymer dehydration condensation reaction with hydroxyl group of methyl acrylate.

The polycarbonate resin constituting the polycarbonate resin film is usually obtained by reacting a dihydric phenol and a carbonate precursor such as phosgene or diphenyl carbonate by an interfacial polycondensation method or a melt transesterification method. An aromatic polycarbonate resin using bisphenol A as a dihydric phenol is common. In addition, a polymer obtained by polymerizing a carbonate prepolymer by a solid phase transesterification method, a polymer obtained by subjecting a cyclic carbonate compound to ring-opening polymerization, or the like can also be used.

The dihydric phenol is not particularly limited as long as it does not impair the performance as an optical transparent resin. For example, in addition to bisphenol A (2,2-bis (4-hydroxyphenyl) propane) , Hydroquinone, resorcinol, 4,4′-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane, bis {(4-hydroxy-3,5-dimethyl) phenyl} methane, 1,1-bis (4-hydroxyphenyl) Ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane, 2 , 2-bis {(4-hydroxy-3-methyl) phenyl} propane, 2,2-bis {( -Hydroxy-3,5-dimethyl) phenyl} propane, 2,2-bis {(4-hydroxy-3,5-dibromo) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2 -Bis (4-hydroxyphenyl) -3-methylbutane, 2,4-bis (4-hydroxyphenyl) -2-methylbutane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2-bis (4- Hydroxyphenyl) -4-methylpentane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis {(4-hydroxy-3-methyl) phenyl} fluorene, 9,9-bis {(4- Hydroxy-3,5-dimethyl) phenyl} fluorene, 9,9-bis {(4-hydroxy-3,5-dibromo) phenyl} fluorene, α, α′-bis 4-hydroxyphenyl) -o-diisopropylbenzene, α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene, α, α′-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 4,4 Examples include '-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl ether, and each of these is used alone or in combination with one or more other.

Further, a monohydric phenol compound may be used in combination in order to adjust the molecular weight to an appropriate range or to seal the hydroxyl terminal of the polymer chain. The monohydric phenol is not particularly limited as long as it is a compound that functions as a terminal blocking agent. For example, phenol, 4-tert-butylphenol, 1-phenyl-1- (4-hydroxyphenyl) propane, etc. Is mentioned.

Examples of methods for forming a chain olefin resin, cyclic olefin resin, methyl methacrylate resin, polycarbonate resin, etc. into a protective film include casting a resin dissolved in a solvent onto a metal band or drum. Then, a solvent casting method for obtaining a film by drying and removing the solvent, and a melt extrusion method for obtaining a film by heating and kneading the resin to a temperature higher than its melting temperature, extruding from a die, and cooling are employed. Of these, the melt extrusion method is preferably employed from the viewpoint of productivity.

Moreover, as a polyester-type resin film which can be used as a protective film provided through an adhesive layer on the side opposite to the side on which the stretched polyethylene terephthalate film is laminated in the polarizing film, the light transmission in the above-mentioned range of 320 nm. If the rate satisfies 60% or more, the same type of polyethylene terephthalate resin as that constituting the stretched polyethylene terephthalate film can be used.

In addition, the optical compensation film made of the cellulose resin film is not particularly limited as long as it has a refractive index characteristic suitable for the purpose. For example, the cellulose resin film mentioned above is uniaxial or biaxial. A film obtained by stretching, a film in which a compound having a retardation adjusting function is contained in a cellulose resin film, a film in which a compound having a retardation adjusting function is applied on the surface of a cellulose resin film, those films, Examples include films obtained by uniaxial or biaxial stretching.

The optical compensation film made of a cellulose resin film can be easily obtained as a commercial product. For example, “Fujitac WV” (manufactured by Fuji Film Co., Ltd.) and “Konica Minolta TAC Film KC8UCR” are commercially available. (Made by Konica Minolta Opto Co., Ltd.).

In order to use the olefin resin film, the acrylic resin film, the polycarbonate resin film, and the polyethylene terephthalate resin film exemplified as the protective film, and the multilayer extruded film made thereof as an optical compensation film, usually, An unstretched film is stretched to give the film refractive index anisotropy. The stretching method is selected according to the required refractive index anisotropy and is not particularly limited, but is usually longitudinal uniaxial stretching, transverse uniaxial stretching, or longitudinal and transverse sequential biaxial stretching. Is adopted.

Many resins, including olefin resins and polycarbonate resins, have positive refractive index anisotropy and have the highest refractive index in the direction in which stress is applied. gives the refractive index anisotropy of the normal _{_{_{n x> n y = n z}}} . Here, n _x is the refractive index in the in-plane slow axis direction (up direction refractive index in the plane) of the film, n _y is perpendicular to the fast axis in the fast axis direction (the plane of the film _Nz is the refractive index in the normal direction of the film. These resins are transverse uniaxially stretched film provides a refractive index anisotropy of the normal _{_{_{n x> n y ≒ n z}}} . Meanwhile, the resin having a negative refractive index anisotropy as acrylic resin, since most refractive index stressed direction is reduced, the longitudinal uniaxially stretched film that is generally n _{x =} n _z> n giving the refractive index anisotropy of _y, the transverse uniaxially stretched film provides a refractive index anisotropy of the normal _{_{_{n x ≒ n z> n y}}} . Resins having a positive refractive index anisotropy was sequentially biaxially-oriented film provides a refractive index anisotropy of the normal _{_{_{n x> n y> n z}}} .

In addition, in order to impart desired refractive index characteristics, a heat-shrinkable film is bonded to a target film, and the film is shrunk in place of or along with the stretching process or after the stretching process. It is. Usually, this operation is performed in order to obtain an optical compensation film having a refractive index anisotropy is _{_n} _x> _n _z> _n _y or _{_{_{n z> n x ≧ n y}}} .

These optical compensation film, when the thickness was d, plane retardation value _{R 0} is at the _{_{(n x -n y) × d}} , the retardation value _{R th} in the thickness direction _{_{[(n x + n y)}} / 2 −n _z ] × d.

The optical compensation film can be easily obtained as a commercial product. For example, as an optical compensation film made of a cyclic polyolefin-based resin, “Zeonor Film” (manufactured by Zeon Corporation), “ “Arton film” (manufactured by JSR Corporation), “Essina retardation film” (manufactured by Sekisui Chemical Co., Ltd.), “Pure Ace ER” (manufactured by Teijin Chemicals Ltd.), and the like. Examples of the optical compensation film made of a polycarbonate-based resin include “Pure Ace WR” (manufactured by Teijin Chemicals Ltd.).

Furthermore, an optical functional film can be laminated or an optical functional layer can be coated on the protective film or the optical compensation film laminated on the polarizing film via the adhesive layer. Examples of the optical functional film and the optical functional layer include an antiglare layer, a conductive layer, a hard coat layer, and an antireflection layer.

(Adhesive layer)
The polarizing plate of this invention can have an adhesive layer on the surface on the opposite side to the surface where the polarizing film is laminated | stacked in the transparent resin film laminated | stacked on the opposite side to the said stretched polyethylene terephthalate film. Such an adhesive layer can be used for bonding with a liquid crystal cell.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited as long as it satisfies various properties (transparency, durability, reworkability, etc.) for optical film applications. For example, (meth) acrylic acid ester An acrylic resin having a glass transition temperature (Tg) of 0 ° C. or less, obtained by radical polymerization of an acrylic monomer composition containing a small amount of a (meth) acrylic monomer having a functional group as a main component in the presence of a polymerization initiator; An acrylic pressure-sensitive adhesive containing a crosslinking agent is used.

Here, the (meth) acrylic acid ester as the main component of the acrylic resin has the following formula:
CH ₂ = C (R ¹ ) COOR ²
Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 1 to 14 carbon atoms or an aralkyl group, and a hydrogen atom or an aralkyl group of the alkyl group represented by R ² These hydrogen atoms may be substituted by an alkoxyl group having 1 to 10 carbon atoms.

Examples of such an acrylate ester include acrylic acrylate in which R ¹ is H, R ² is n-butyl acrylate, R ¹ is H, and R ² is 2-ethylhexyl group. Acid 2-ethylhexyl etc. are mentioned. For example, when R ¹ is H and R ² is an alkyl group substituted with an alkoxyl group, 2-methoxyethyl acrylate, ethoxymethyl acrylate, and the like can be given.

The (meth) acrylic monomer having a functional group is a polar functional group such as a hydroxyl group, a carboxyl group, an amide group, an amino group, and an epoxy group, and one olefinic double bond (usually a (meth) acryloyl group). ) In the molecule.

Examples of the acrylic monomer having such a functional group include those having a hydroxyl group, and specifically, 2-hydroxyethyl acrylate is preferably used. Acrylic acid is preferably used as the carboxyl group.

The acrylic monomer composition may further contain a monomer other than the (meth) acrylic acid ester and the (meth) acrylic monomer having a functional group. Examples include a monomer having one olefinic double bond and at least one aromatic ring in the molecule, a styrene monomer, a (meth) acrylic acid ester having an alicyclic structure in the molecule, and a vinyl monomer. And monomers having a plurality of (meth) acryloyl groups in the molecule.

Among them, as a monomer having one olefinic double bond and at least one aromatic ring in the molecule, the following formula:
_{^{_{CH 2 = C (R 3)}}} -COO- (CH 2 CH 2 O) n -Ar-R 4
The monomer represented by these is preferable.

In the above formula, R ³ represents a hydrogen atom or a methyl group, n is an integer of 1 to 8, Ar is an arylene group, R ⁴ is a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, a carbon number of 7 Represents an aralkyl group having 11 to 11 carbon atoms or an aryl group having 6 to 10 carbon atoms.

Examples of such monomers include 2-phenoxyethyl (meth) acrylate, 2- (2-phenoxyethoxy) ethyl (meth) acrylate, (meth) acrylate of ethylene oxide-modified nonylphenol, and 2- (o-phenylphenoxy) ethyl. (Meth) acrylate etc. are mentioned. Among these, 2-phenoxyethyl acrylate is preferable.

Monomers other than the (meth) acrylic acid ester and the (meth) acrylic monomer having a functional group may be used singly or a plurality of different types may be used in combination. The content of the structural unit derived from this monomer with respect to the entire acrylic resin is usually 0 to 20% by weight, preferably 0 to 10% by weight.

The molecular weight of the acrylic resin contained in the acrylic pressure-sensitive adhesive is preferably 1,000,000 to 2,000,000 as the value indicated by the weight average molecular weight (Mw) in terms of standard polystyrene by gel permeation chromatography (GPC). When the weight average molecular weight is 1 million or more, the adhesiveness under high temperature and high humidity is improved, and there is a tendency that the possibility of floating or peeling between the glass substrate and the pressure-sensitive adhesive layer tends to be reduced. It is preferable because the property tends to be improved. In addition, when the weight average molecular weight is 2 million or less, even if the size of the transparent resin film bonded to the pressure-sensitive adhesive layer changes, the pressure-sensitive adhesive layer changes following the change in size, so that the liquid crystal cell This is preferable because there is no difference between the brightness of the peripheral edge and the brightness of the center, and white spots and color unevenness tend to be suppressed. Furthermore, the molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably in the range of 3-7.

The acrylic resin contained in the acrylic pressure-sensitive adhesive can be composed only of a relatively high molecular weight as described above, but it can also be composed of a mixture with a different acrylic resin. Examples of the acrylic resin used by mixing include those having, as a main component, a structural unit derived from the (meth) acrylic acid ester represented by the above formula and having a weight average molecular weight in the range of 50,000 to 300,000. be able to.

As a method for producing the acrylic resin contained in the acrylic pressure-sensitive adhesive, various known methods such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a suspension polymerization method are employed. In the production of this acrylic resin, a polymerization initiator is usually used. Examples of the polymerization initiator include azo compounds, organic peroxides, inorganic peroxides, redox initiators in which a peroxide and a reducing agent are used in combination. Among these, 2,2'-azobisisobutyronitrile, benzoyl peroxide, and ammonium persulfate are preferably used. The blending amount of such a polymerization initiator is usually about 0.001 to 5 parts by weight with respect to 100 parts by weight of the total amount of acrylic monomers.

The acrylic resin thus obtained is mixed with a crosslinking agent to form a pressure-sensitive adhesive composition. The crosslinking agent is a compound having in the molecule at least two functional groups capable of crosslinking reaction with a structural unit derived from a monomer having a polar functional group in the acrylic resin. For example, an isocyanate compound, an epoxy compound, A metal chelate type compound, an aziridine type compound, etc. are mentioned.

Among these crosslinking agents, isocyanate compounds are preferably used. As the isocyanate compound, in addition to the compound itself having at least two isocyanato groups (—NCO) in the molecule, an adduct obtained by reacting it with a polyol or the like, a dimer thereof, a trimer, etc. are used. For example, tolylene diisocyanate, an adduct obtained by reacting tolylene diisocyanate with a polyol, a dimer of tolylene diisocyanate, and a trimer of tolylene diisocyanate, and hexamethylene diisocyanate, hexamethylene diisocyanate Examples thereof include adducts obtained by reacting with polyols, dimers of hexamethylene diisocyanate, trimers of hexamethylene diisocyanate, and the like.

The blending amount of the crosslinking agent with respect to 100 parts by weight of the acrylic resin is usually 0.01 to 5 parts by weight, preferably 0.1 to 5 parts by weight, and more preferably 0.2 to 3 parts by weight. When the amount of the crosslinking agent relative to 100 parts by weight of the acrylic resin is 0.01 parts by weight or more, particularly 0.1 parts by weight or more, the durability of the pressure-sensitive adhesive layer tends to be improved. Moreover, when it is 5 parts by weight or less, white spots tend to be inconspicuous when the polarizing plate with the pressure-sensitive adhesive layer is applied to a liquid crystal display device.

The pressure-sensitive adhesive layer used in the present invention preferably has antistatic properties in order to gradually discharge static electricity charged on the polarizing plate. The polarizing plate is often charged with static electricity when the release film (separator) protecting the pressure-sensitive adhesive layer is peeled off and bonded to the liquid crystal cell, but if the pressure-sensitive adhesive layer has antistatic properties. , The static electricity is gradually reduced, and the display circuit of the liquid crystal cell is prevented from being broken and the liquid crystal molecules are prevented from being disturbed in alignment.

In order to impart antistatic properties to the pressure-sensitive adhesive layer, generally, a method in which the pressure-sensitive adhesive contains metal fine particles, metal oxide fine particles, or fine particles coated with a metal, etc .; ionic conductivity comprising an electrolyte salt and an organopolysiloxane A method of incorporating an organic composition; a method of incorporating an organic salt antistatic agent, and the like are employed. On the other hand, the required antistatic holding time is required to be at least about 6 months from the viewpoint of production, distribution, and storage period of a general polarizing film.

Therefore, in order to impart antistatic properties to the pressure-sensitive adhesive used in the present invention, a method of containing an ionic compound having a melting point of 30 to 80 ° C. and having an organic cation is preferably employed. The melting point of this ionic compound is more preferably 35 to 70 ° C. When the melting point exceeds 80 ° C., the compatibility between the ionic compound and the acrylic resin may be deteriorated. If the melting point is less than 30 ° C., the antistatic long-term stability may be inferior.

As the organic cation component constituting the ionic compound having a melting point of 30 to 80 ° C., a pyridinium cation and an imidazolium cation are preferable because they are less likely to be charged when the release film (separator) is peeled off. On the other hand, the anion component which is a counter ion of the organic cation component may be an inorganic anion or an organic anion. Among these, an anionic component containing a fluorine atom is preferable and a hexafluorophosphate anion is more preferable because an ionic compound having excellent antistatic performance is provided.

Specific examples of the ionic compound include N-hexylpyridinium hexafluorophosphate, N-octylpyridinium hexafluorophosphate, N-octyl-4-methylpyridinium hexafluorophosphate, N-butyl-4-methylpyridinium hexafluorophosphate, N- Examples include methyl-4-hexylpyridinium hexafluorophosphate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and the like. Each of such ionic compounds may be used alone or in combination with one or more other ionic compounds.

The content of the ionic compound with respect to 100 parts by weight of the acrylic resin is preferably 0.2 to 8 parts by weight, and more preferably 0.5 to 3 parts by weight. When the ionic compound is contained in an amount of 0.2 parts by weight or more based on 100 parts by weight of the acrylic resin, it is preferable because the antistatic performance of the pressure-sensitive adhesive layer using this pressure-sensitive adhesive composition is improved. Moreover, it is preferable that the content is 8 parts by weight or less because it is easy to maintain the durability of the pressure-sensitive adhesive layer.

Such ionic compounds are also commercially available, for example, pyridinium cation type ionic compounds (manufactured by Koei Chemical Co., Ltd.), imidazolium cation type ionic compounds (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), aliphatic quaternary ammonium Cationic ionic compounds (manufactured by Nisshinbo Industries, Inc.) and the like can be mentioned.

In the pressure-sensitive adhesive composition, if necessary, a silane coupling agent, a crosslinking catalyst, a weathering stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, an inorganic filler, and a resin other than the acrylic resin, etc. In addition, light diffusing fine particles such as organic beads may be blended. It is also useful to blend an ultraviolet curable compound into the pressure-sensitive adhesive composition and form a harder pressure-sensitive adhesive layer by irradiating and curing ultraviolet rays after forming the pressure-sensitive adhesive layer.

These components constituting the pressure-sensitive adhesive composition are coated on a suitable base material in a state dissolved in a suitable solvent such as ethyl acetate and dried to form a pressure-sensitive adhesive layer.

As a method for forming the pressure-sensitive adhesive layer on the transparent resin film, for example, a release film is used as the substrate, the pressure-sensitive adhesive composition is applied to form the pressure-sensitive adhesive layer, and the resulting pressure-sensitive adhesive layer is transparent. A method of laminating on the surface of the resin film, a method of applying a pressure-sensitive adhesive composition to the surface of the transparent resin film to form a pressure-sensitive adhesive layer, and bonding a release film to the pressure-sensitive adhesive surface are employed. Moreover, after obtaining a pressure-sensitive adhesive layer on a release film, a release film is further bonded to obtain a double-sided separator type pressure-sensitive adhesive sheet that is not supported by an optical film (for example, a protective film or an optical compensation film). it can. Such a double-sided separator-type pressure-sensitive adhesive sheet is used for laminating a release film on one side at a necessary time and bonding with a transparent resin film. As a commercial item of a double-sided separator type pressure-sensitive adhesive sheet, for example, a non-carrier pressure-sensitive adhesive film / sheet (manufactured by Lintec Corporation, manufactured by Nitto Denko Corporation) can be mentioned.

The release film is, for example, a film made of various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyarylate, polypropylene or polyethylene, and silicone on the adhesive surface of the substrate. It has been subjected to a release treatment such as a treatment, and is also called a separator film or a separator.

The pressure-sensitive adhesive layer thus coated and dried is usually aged at a temperature of 23 ° C. and a humidity of 65% for about 3 to 20 days, and after the reaction of the crosslinking agent has sufficiently proceeded, the liquid crystal cell and other optical films Used for pasting.

The thickness of the pressure-sensitive adhesive layer is preferably 10 to 30 μm, more preferably 15 to 25 μm. When the thickness of the pressure-sensitive adhesive layer is 30 μm or less, the adhesiveness at high temperature and high humidity is improved, and the possibility of occurrence of floating or peeling between the glass substrate and the pressure-sensitive adhesive layer tends to be low, and Reworkability tends to improve. Further, if the thickness is 10 μm or more, even if the size of the transparent resin film bonded thereto changes, the pressure-sensitive adhesive layer changes following the change in size, so that the brightness of the peripheral portion of the liquid crystal cell There is no difference between the brightness and the brightness of the central portion, and white spots and color unevenness tend to be suppressed.

<Liquid crystal display device>
The polarizing plate as described above, that is, a polarizing plate having a laminated structure of stretched polyethylene terephthalate film / adhesive layer / polarizing film / adhesive layer / transparent resin film / adhesive layer / release film containing an ultraviolet absorber. Can peel the release film from the pressure-sensitive adhesive layer and paste it on one or both sides of the liquid crystal cell to form a liquid crystal panel. This liquid crystal panel can be applied to a liquid crystal display device.

The polarizing plate of the present invention can be used, for example, as a polarizing plate disposed on the viewing side in a liquid crystal display device. In particular, when an antiglare layer is laminated on the stretched polyethylene terephthalate film constituting the polarizing plate of the present invention, the polarizing plate of the present invention is disposed on the viewing side. The viewing side refers to the side opposite to the backlight side with respect to the liquid crystal cell of the liquid crystal display device. The polarizing plate disposed on the backlight side of the liquid crystal display device may be the polarizing plate of the present invention or a conventionally known polarizing plate.

Although the operation mode of the liquid crystal cell is not particularly limited, a transmission type VA mode or IPS mode liquid crystal cell is preferable from the viewpoint of the thin wall and high productivity that are the characteristics of the polarizing plate of the present invention. A relatively large liquid crystal cell for a television in these modes is more preferable.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In these examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. Evaluation was performed as follows.

<Light transmittance>
About the protective film laminated | stacked on a polarizing film, the light transmittance of 320mn and 380mn was measured using Shimadzu Corporation spectrophotometer UV2450.

<Light resistance evaluation>
The obtained polarizing plate was cut out into 40 mm x 40 mm, and it bonded to the glass substrate through the adhesive on the outer surface of the protective film laminated | stacked on the opposite side to the stretched polyethylene terephthalate film. Thereafter, it was put into a sunshine weather meter (S80 manufactured by Suga Test Instruments Co., Ltd.) so that the stretched polyethylene terephthalate film was irradiated with ultraviolet rays. After irradiation for 500 hours, the product was taken out and visually evaluated for the presence or absence of discoloration from the initial stage.

<Heat and heat resistance evaluation>
The obtained polarizing plate was cut out into 40 mm x 40 mm, and it bonded to the glass substrate through the adhesive on the outer surface of the protective film laminated | stacked on the opposite side to the stretched polyethylene terephthalate film. Thereafter, the film was put into an oven at 60 ° C. and 90% RH for 1000 hours, and after taking out, the appearance of the polarizing film caused by insufficient reaction of the adhesive layer composed of the cured layer of the ultraviolet curable resin composition was visually evaluated.

<Adhesion evaluation>
Put the blade of the cutter into the interface between the polarizing film of the obtained polarizing plate and the protective film on both sides, and the protective film and the polarizing film depending on whether or not the cutter blade proceeds as it is and peeling occurs between the protective film and the polarizing film The adhesion was evaluated.

[Production Example 1] Production of polarizing film A polyvinyl alcohol film having an average polymerization degree of about 2,400 and a saponification degree of 99.9 mol% or more and a thickness of 75 µm was immersed in pure water at 30 ° C, and then iodine / potassium iodide / It was immersed at 30 ° C. in an aqueous solution having a weight ratio of pure water of 0.02 / 2/100. Then, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / pure water of 12/5/100 at 56.5 ° C., subsequently washed with 8 ° C. pure water, dried at 65 ° C., A polarizing film in which iodine was adsorbed and oriented on polyvinyl alcohol was obtained. Stretching was performed mainly in the process of iodine staining and boric acid treatment, and the total stretching ratio during the process was 5.3 times.

[Production Example 2] Preparation of UV-curable adhesive composition The following components were mixed to prepare a liquid adhesive composition.

3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate 40 parts Bisphenol A type epoxy resin 60 parts Diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate (cationic polymerization initiator) 4.0 parts

[Production Example 3] Preparation of aqueous adhesive The following components were mixed to prepare an aqueous adhesive.

Pure water 100 parts Carboxyl group-modified polyvinyl alcohol [Kuraray Poval KL318 (available from Kuraray Co., Ltd.) 3.0 parts Water-soluble polyamide epoxy resin (aqueous solution with a solid content concentration of 30%) [Smiles Resin 650 (from Sumika Chemtex Co., Ltd.) Acquired)] 1.5 parts

<Example 1>
After subjecting the stretched polyethylene terephthalate film having an ultraviolet absorber having a light transmittance of 1% at 380 nm to corona treatment on the bonding surface, the ultraviolet curable adhesive composition obtained in Production Example 2 was used as a chamber doctor. The film was coated to a thickness of 3 μm by a coating apparatus equipped with Moreover, after giving a corona treatment to the bonding surface of the optical compensation film which consists of a cyclic olefin resin film with a light transmittance of 90% of 320 nm, the ultraviolet curable adhesive composition obtained in Production Example 2 was similarly applied. The coating was applied to a thickness of 3 μm.

Immediately after applying the adhesive composition to each film, the polarizing polyethylene film obtained in Production Example 1 was bonded to one side with a stretched polyethylene terephthalate film and the other side with an optical compensation film made of a cyclic olefin resin film. It bonded by the bonding roll through the coating surface of the agent composition. Thereafter, at a line speed of 20 m / min, the metal halide lamp is irradiated from the side of the optical compensation film made of a cyclic olefin resin film so that the integrated light quantity at a wavelength of 280 to 320 nm is 320 mJ / cm ^2. Was cured to obtain a polarizing plate. The evaluation results are shown in Table 1.

<Example 2>
In place of the stretched polyethylene terephthalate film in Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that a stretched polyethylene terephthalate film having an ultraviolet absorber having a light transmittance of 9% at 380 nm was used. The evaluation results are shown in Table 1.

<Example 3>
In place of the optical compensation film made of a cyclic olefin resin film in Example 1, an optical compensation film made of a cellulose resin having a light transmittance of 320% of 320 nm was used, except that an optical compensation film made of a cellulose resin was used. Thus, a polarizing plate was obtained. The evaluation results are shown in Table 1.

<Example 4>
In place of the optical compensation film made of the cyclic olefin resin film in Example 1, a protective film made of a polyethylene terephthalate film having a light transmittance of 320 nm of 60% was used, and irradiation with a metal halide lamp was performed at a wavelength of 280 to 320 nm. A polarizing plate was obtained in the same manner as in Example 1 except that the integrated light amount was 450 mJ / cm ² . The evaluation results are shown in Table 1.

<Comparative Example 1>
Instead of the stretched polyethylene terephthalate film in Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that a stretched polyethylene terephthalate film having an ultraviolet absorber having a light transmittance of 380 nm of 31% was used. The evaluation results are shown in Table 1.

<Comparative Example 2>
Example 4 except that a protective film made of a polyethylene terephthalate film having a light transmittance of 320 nm of 30% was used instead of the protective film made of a polyethylene terephthalate film having a light transmittance of 320 nm of 59% in Example 4. In the same manner, a polarizing plate was obtained. The evaluation results are shown in Table 1.

As can be seen from the results in Table 1, the polarizing plate of the present example has excellent ultraviolet absorbing ability and excellent adhesion between the polarizing film and a protective film made of a stretched polyethylene terephthalate film, and in a wet and hot environment. Also has high durability. Moreover, the external appearance was favorable in any Example.

<Comparative Example 3>
Corona treatment of an optical compensation film comprising a stretched polyethylene terephthalate film having a UV absorber with a light transmittance of 1% at 380 nm and a cyclic olefin resin film with a light transmittance of 320% at 90% on the bonding surface side of the polarizing film, respectively. After applying, the water-based adhesive obtained in Production Example 3 was applied and bonded to both surfaces of the polarizing film.
Thereafter, it was immediately dried for 5 minutes with a hot air circulating dryer set at 80 ° C. to obtain a polarizing plate.

The polarizing plate of this comparative example was easily peeled off between the polarizing film and the protective film, and had poor adhesion.

<Example 5>
(A) Production of viewing-side polarizing plate Instead of the stretched polyethylene terephthalate film in Example 1, the side opposite to the surface to be bonded to the polarizing film of the stretched polyethylene terephthalate film having an ultraviolet absorber having a light transmittance of 380 nm of 1% A polarizing plate was obtained in the same manner as in Example 1 except that a stretched polyethylene terephthalate film having an antiglare layer composed of a cured layer of a resin composition for forming an antiglare layer on the surface was used. The outer surface of the optical compensation film made of the cyclic olefin-based resin film of the polarizing plate thus obtained was subjected to corona treatment, an acrylic pressure-sensitive adhesive layer having a thickness of 20 μm was provided, and a viewing-side polarizing plate with a pressure-sensitive adhesive layer was obtained. Then, it cut | judged by aligning an absorption axis to the long side direction to the screen size of the liquid crystal television mentioned later, and obtained the visual recognition side polarizing plate sheet.

(B) Production of backlight-side polarizing plate Corona treatment was applied to the outer surface of the optical compensation film composed of the cyclic olefin resin film of the polarizing plate obtained in Example 1, and an acrylic pressure-sensitive adhesive layer having a thickness of 20 μm was provided. A backlight side polarizing plate with an adhesive layer was obtained. Then, it cut | judged by aligning an absorption axis to the short side direction to the screen size of the liquid crystal television mentioned later, and obtained the backlight side polarizing plate sheet.

(C) Production of Liquid Crystal Display Device From the liquid crystal panel of a commercially available liquid crystal television on which a liquid crystal panel having a vertical alignment mode liquid crystal cell was mounted, the polarizing plates on both sides were peeled off and the liquid crystal cell was taken out. The liquid crystal cell is bonded to the front side (viewing side) of the viewing side polarizing plate sheet and the back side (backlight side) of the backlight side polarizing plate sheet via respective adhesive layers. Produced.

Next, this liquid crystal panel was assembled in the configuration of backlight / light diffusion plate / diffusion sheet / liquid crystal panel to produce a liquid crystal display device. When this liquid crystal display device was operated, defects such as color unevenness were not observed.

Claims

A polarizing film comprising a polarizing film comprising a polyvinyl alcohol-based resin, and a protective film laminated on both surfaces of the polarizing film via an adhesive layer,
The protective film on one side is composed of a stretched polyethylene terephthalate film containing an ultraviolet absorber and having a light transmittance of 10% or less at a wavelength of 380 nm,
The protective film on the other surface has a light transmittance at a wavelength of 320 nm of 60% or more,
An adhesive bond layer is a polarizing plate which consists of a hardened | cured material layer of the ultraviolet curable resin composition containing an epoxy compound.
The stretched polyethylene terephthalate film has an antiglare property, or an antiglare layer is laminated on the surface of the stretched polyethylene terephthalate film opposite to the surface to be bonded to the polarizing film. The polarizing plate as described in.
3. The polarizing plate according to claim 1, wherein the protective film laminated on the opposite side of the polarizing film from the stretched polyethylene terephthalate film is an optical compensation film.
The protective film laminated on the side opposite to the stretched polyethylene terephthalate film of the polarizing film comprises an adhesive layer on the side opposite to the side laminated on the polarizing film. The polarizing plate as described in.
A liquid crystal display device comprising a liquid crystal panel in which the polarizing plate according to claim 4 is bonded to a liquid crystal cell via an adhesive layer.