TW201325895A - Polarizing plate and manufacturing method thereof - Google Patents

Abstract

This invention is related to a polarizing plate comprising at least a polarizing film and a protecting film, wherein the protecting film is laminated on at least one side of the above polarizing film, and an adhesive layer is set on the outset surface of the opposite side of the above polarizing film, and wherein the shrinkage force for every 2 mm wide the on the direction orthogonal to the absorption axial of the above polarizing film, is below 1.0N when it is kept at temperature of 80 DEG C for 240 minutes, and the storage modulus of the above adhesive layer is above 0.2 Mpa at 23 DEG C.

Description

Polarizing plate and manufacturing method thereof

The present invention relates to a polarizing plate and a method of manufacturing the same.

The polarizing plate is widely used as a supply element for polarized light in a liquid crystal display device or as a detecting element for polarized light. As such a polarizing plate, a polarizing plate containing a polarizing film of a polyvinyl alcohol-based resin and a protective film containing triacetyl cellulose has been conventionally used. However, in recent years, notebook computers of liquid crystal display devices and The development of mobile devices such as mobile phones, and the development of large-scale televisions, etc., have thin and light weight requirements.

In the elliptically polarizing plate in which a retardation film (linear polarizing plate) is laminated on a conventional polarizing film (linear polarizing plate), a flexible adhesive having a low storage modulus is used. A method of preventing the crack of the retardation film caused by heat shrinkage of the polarizing film or the like in combination with the liquid crystal cell. However, the use of an adhesive having a low modulus of elasticity has a problem that the dimensional change of the polarizing plate is large.

In the patent document 2 (JP-A-2002-122739), the product of the linear expansion coefficient in the MD direction of the protective layer of the polarizing film and the elastic modulus of the adhesive constituting the polarizing plate is set in a specific range. Alleviate light leakage The method of phenomena. However, this method also relaxes the expansion and contraction of the polarizing film by using a protective film having a low linear expansion ratio and an adhesive having a low elastic modulus, so that the dimensional change of the polarizing plate is large.

Further, in Patent Document 3 (International Publication No. 2009/069799), a polarizing plate in which a one-layer transparent protective layer (triethylenesulfonated cellulose film) of a polarizing film is formed is described, and a phase difference plate is laminated. When a circular polarizing plate is bonded to a liquid crystal cell by using an adhesive having a high storage modulus, it is possible to suppress bulging or light leakage which is likely to occur at the edge of the polarizing film when it is bonded to a liquid crystal cell and exposed to a high-humidity environment. method. However, even if the size of the polarizing plate can be suppressed by this method, the photochemical film such as a retardation film may be broken due to shrinkage of the polarizing film.

The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a polarizing plate having a light leakage phenomenon and a small dimensional change, and a method for producing the same, in which cracking or peeling of other optical films such as a polarizing film or a retardation film are suppressed.

The present invention relates to a polarizing plate comprising at least one layer of a protective film of the polarizing film, and an adhesive layer on an outermost surface opposite to the protective film, wherein the polarizing film comprises at least one polarizing film and a protective film. The shrinkage force per 2 mm width in the direction perpendicular to the absorption axis of the polarizing film is 1.0 N or less at 240 ° C for 240 minutes, and the storage modulus of the adhesive layer at 23 ° C is 0.20 MPa or more.

The polarizing film includes at least one optical film on the opposite side of the protective film, and the optical film farthest from the polarizing film is opposite to the polarizing film It is desirable to have the aforementioned adhesive layer on the surface.

When the contraction force per 2 mm width of the polarizing film in the absorption axis direction of the polarizing film is maintained at a temperature of 80 ° C for 240 minutes, it is preferably 2.5 N or less. Further, the thickness of the polarizing film is preferably 10 μm or less.

It is preferable that the adhesive layer has a storage modulus at 80 ° C of 0.15 MPa or more. Further, the optical film is preferably a protective film or a retardation film.

Further, the present invention relates to a liquid crystal display device in which at least one side of a liquid crystal cell is bonded to the polarizing plate via the adhesive layer.

Further, the present invention relates to a method of producing a polarizing plate comprising the steps of the following steps: an undercoat layer forming step of applying a primer solution on one side of a substrate film to form an undercoat layer; The alcohol-based resin layer forming step of forming a polyvinyl alcohol-based resin layer on the undercoat layer, and obtaining a laminated film comprising the base film, the undercoat layer, and the polyvinyl alcohol-based resin layer in this order; In the polarizing film formation treatment step, the polyvinyl alcohol-based tree layer is subjected to a polarizing film treatment to form a polarizing film, and the base film, the undercoat layer and the polarizing film layer are provided in the order of the polarizing film. a protective film bonding step of bonding a protective film to a surface of the polarizing laminate film opposite to the substrate film; and a substrate film peeling step of peeling the base film from the polarizing laminate film; and adhering a layering step of the most surface layer of the adhesive layer on the opposite side of the protective film; It is characterized in that the shrinkage force per 2 mm width in the direction orthogonal to the absorption axis of the polarizing film is 1.0 N or less at a temperature of 80 ° C for 240 minutes, and the storage elastic modulus of the adhesive layer at 23 ° C is 0.20. More than MPa.

It is preferable that an optical film lamination step of laminating at least one other optical film on the surface side on which the base film is peeled off is provided between the base film peeling step and the pressure-adhesive layer stacking step.

In the above-described adhesive layering step, the above-mentioned adhesive layer on the opposite side to the polarizing film of the optical film farthest from the polarizing film is preferable.

Further, the present invention relates to a method of producing a polarizing plate comprising the steps of the following steps: an undercoat layer forming step of applying a primer solution on one side of a substrate film to form an undercoat layer; The alcohol-based resin layer forming step of forming a polyvinyl alcohol-based resin layer on the undercoat layer, and obtaining a laminated film comprising the base film, the undercoat layer, and the polyvinyl alcohol-based resin layer in this order; In the polarizing film formation treatment step, the polarizing film is treated as a polarizing film on the polyvinyl alcohol-based tree-finishing layer, and the base film, the undercoat layer, and the polarizing film layer are polarized in this order. a laminated film; a protective film bonding step of bonding a protective film to a surface of the polarizing laminated film opposite to the base film; and a base film peeling step of peeling the base film from a polarizing laminated film And an optical film lamination step with an adhesive layer on the outermost surface on the opposite side of the protective film, and an optical film with an adhesive layer laminated on the side of the adhesive layer side as the outermost surface; and having the following characteristics The shrinkage force per 2 mm width in the direction orthogonal to the absorption axis of the polarizing film is 1.0 N or less at 240 ° C for 240 minutes, and the storage elastic modulus of the adhesive layer at 23 ° C is 0.20 MPa or more.

It is preferable to include an optical film lamination step including at least one additional optical film on the surface side on which the base film is peeled off between the base film peeling step and the optical film lamination step with the adhesive layer.

In the polarizing film obtained in the polyvinyl alcohol-based resin layer forming step, the thickness of the polyvinyl alcohol-based resin layer is preferably 20 μm or less.

The polarizing film formation treatment step preferably includes an extending step of extending the laminated film, and a dyeing step of dyeing the polyvinyl alcohol-based resin layer with a dichroic material.

In the aforementioned stretching step, it is desirable that the stretching ratio is more than 5 times. Further, it is preferable that the adhesive has a storage modulus at 80 ° C of 0.15 MPa or more. Further, the optical film is preferably a protective film or a retardation film.

According to the present invention, a polarizing film having a small shrinkage force is combined with an adhesive having a high modulus of elasticity, and a polarizing plate in which cracking or peeling of other optical films such as a polarizing film and a retardation film and light leakage are suppressed, and dimensional change is small can be obtained.

1‧‧‧Polar plate

10‧‧‧Protective film

11‧‧‧ polarizing film

11A‧‧‧Absorption axis

12‧‧‧ phase difference film

12B‧‧‧遅phase axis

C‧‧‧Long-term direction

‧‧‧‧ angle

‧‧‧‧ angle

S10‧‧‧ polyvinyl alcohol resin layer forming step

S20‧‧‧ polarizing film processing steps

S21‧‧‧Extension step

S22‧‧‧Staining step

S30‧‧‧Protective film bonding step

S40‧‧‧Substrate film peeling step

S50‧‧‧Optical film lamination step

S60‧‧‧Adhesive lamination step

S60’) ‧‧·Optical film lamination step with adhesive layer

Fig. 1 is a flow chart showing an embodiment of a method of producing a polarizing plate of the present invention.

Fig. 2 is a flow chart showing another embodiment of the method for producing a polarizing plate of the present invention.

Fig. 3 is a schematic view for explaining the arrangement relationship of the respective constituent elements of the polarizing plate of the present invention.

Hereinafter, a preferred embodiment of the method for producing a polarizing plate of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a flow chart showing an embodiment of a method of manufacturing a polarizing plate of the present invention. The method for producing a polarizing plate of the present invention shown in Fig. 1 includes a polyvinyl alcohol-based resin layer forming step (S10) in the following order, and a polyvinyl alcohol-based resin is formed on the surface of one side of the base film. a layer as a laminated film; a polarizing film forming treatment step (S20): applying a polarizing film treatment to the polyvinyl alcohol-based resin layer as a polarizing film; and a protective film bonding step (S30), which is applied to the polarizing film The surface of the substrate film side is bonded to the surface on the opposite side; the substrate film peeling step (S40) is to peel the base film from the laminated film; the adhesive layering step (S60) is applied to the protective film. The most surface layer of the adhesive layer on the opposite side. Further, between the base film peeling step (S40) and the adhesive layering step (S60), an optical film laminating step of depositing at least one optical film on the surface side on which the base film is peeled off may be included (S50). .

Fig. 2 is a flow chart showing another embodiment of the method for producing a polarizing plate of the present invention. Manufacture of the polarizing plate of the present invention shown in Fig. 2 The method is the same as the production method shown in Fig. 1 from the polyvinyl alcohol-based resin layer forming step (S10) to the substrate film peeling step (S40). In the manufacturing method shown in FIG. 2, the step after the base film peeling step (S40) is provided with an optical film lamination step (S60'), and the optical surface with the adhesive layer is attached to the outermost surface on the opposite side of the protective film. The film is laminated in such a manner that the adhesive layer becomes the outermost surface. Further, between the base film peeling step (S40) and the optical film laminating step (S60') having the adhesive layer, it is also possible to include at least one optical film laminated on the side where the base film is peeled off. An optical film lamination step (S50).

The polarizing film formation treatment step (S20) includes an extending step (S21) of extending the laminated film, and a dyeing step (S22) of dyeing the polyvinyl alcohol-based resin layer with a dichroic material. In the polarizing film formation treatment step (S20), the stretching step (S21) and the dyeing step (S22) are not limited to this order, and the stretching step (S21) may be performed after the dyeing step (S22), or the stretching step may be simultaneously performed ( S21) and a dyeing step (S22).

[Substrate film]

In the material of the base film used in the present invention, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, and elongation is used. Specific examples of the thermoplastic resin include a cellulose ester resin such as cellulose triacetate, a polyester resin, a polyether sulfonic acid resin, a polysulfonic acid resin, and a polycarbonate resin. Polyamide type resin, polyimide type resin, polyolefin type resin, (meth) acrylate type resin, cyclic polyolefin type resin (norborning type resin), polyallylate type resin, A polystyrene resin, a polyvinyl alcohol resin, a mixture of these, a copolymer, and the like. The base film may be one type of the above resin. The layer may also be a mixture of two or more kinds of resins. Of course, it is also possible to form a multilayer film instead of a single layer.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of such a cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Among them, cellulose triacetate is particularly preferred. Cellulose triacetate is commercially available in a variety of products, and is also advantageous in terms of ease of entry and price. Examples of the cellulose triacetate product include Fujitac (registered trademark) TD80 (Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UF (Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UZ (Fuji Film Co., Ltd.), Fujitac (registered trademark) TD40UZ (Fuji Film Co., Ltd.), KC8UX2M (Konica Minolata Opto Co. Co., Ltd.), KC4UY (Konica Minolata Opto Co. Co., Ltd.) Wait.

The polyester resin is a polymer having an ester bond, and is mainly a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. The polycarboxylic acid to be used is mainly a divalent dicarboxylic acid such as isodecanoic acid, p-citric acid, dimethyl decanoate or dimethyl naphthalate. Further, the polyol to be used is also a 2-membered diol, and examples thereof include propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanediol.

Specific examples of the polyester-based resin include polyethylene terephthalate, p-butyl phthalate, polyethylene naphthalate, polybutylene naphthalate, and polypropylene propylene terephthalate. , polybutylene naphthalate, poly(p-hexanedicarboxylate), cyclohexanedimethylene naphthalate, and the like. These mixed resins and copolymers can also be suitably used.

The polycarbonate resin is a polymer comprising a monomer unit bonded via a carbonate group. The engineering plastic for the compound is a resin having high impact resistance, heat resistance and flame retardancy. Further, since it has high transparency, it can be suitably used for optical use. In optical applications, in order to reduce the photoelastic coefficient, a resin called a modified polycarbonate which is modified by a polymer skeleton, and a co-polycarbonate which improves wavelength dependence may be suitably used.

This polycarbonate resin is widely sold, for example, Panlite (registered trademark) (Emperor Chemicals Co., Ltd.), Iupilon (registered trademark) (Mitsubishi Engineering-Plastics Co.), SD Polyca (registered trademark) (Sumitomo Dow) (share)), Caliber (registered trademark) (Dow Chemicals (share)).

The polyolefin-based resin is preferably a polyethylene or a polypropylene which is easily stretched at a high rate. Further, an ethylene-propylene copolymer or the like obtained by copolymerizing propylene with ethylene can also be used. The copolymerization may be another type of monomer, and other monomers which may be copolymerized with propylene include, for example, ethylene and an α-olefin. As the α-olefin, an α-olefin having 4 or more carbon atoms is desirably used, and an α-olefin having 4 to 10 carbon atoms is preferable. Specific examples of the α-olefin having 4 to 10 carbon atoms include, for example, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, and the like. Chain monoolefins; branched monoolefins such as 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene; vinylcyclohexane; The copolymer of propylene and other monomers copolymerizable therewith may be a random copolymer or a block copolymer. The content of the other monomer-derived constituent units in the copolymer can be measured by infrared (IR) spectroscopy in accordance with the method described in the "Handbook of Polymer Analysis" (published by Kiyoshiya Shoten, 1995). Seek.

In the above, as a polyacrylate constituting a polyacrylate resin film As the resin, a single polymer of propylene, a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, and a propylene-ethylene-1-butene random copolymer are preferable.

Moreover, the stereoregularity of the polyacrylate resin constituting the polyacrylate resin film is substantially the same row or the opposite row. A polyacrylate-based resin film containing a polyacrylate-based resin having a substantially uniform or aligned stereoregular resin is excellent in handleability and excellent in mechanical strength in a high-temperature environment.

As the cyclic polyolefin resin, it is preferred to use a norbornene resin. The cyclic polyolefin-based resin is a general term for a resin which is polymerized by using a cyclic olefin as a polymerization unit. For example, JP-A-1-240517, JP-A-3-14882, and JP-A-3-122137 The resin described in the bulletin and the like. Specific examples are a ring-opened (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, an α-olefin such as a cyclic olefin and ethylene, propylene, and a copolymer thereof (representatively a random copolymer) And these graft polymers modified with unsaturated carboxylic acids or their derivatives, and these hydrides and the like. Specific examples of the cyclic olefin include norbornene monomers.

As a cyclic polyolefin resin, various products have been marketed. Specific examples include Topas (registered trademark) (manufactured by Ticona Co., Ltd.), Arton (registered trademark) (JSR (share) system), ZEONOR (registered trademark) (made by Japan Zeon Co., Ltd.), and ZEONEX (registered trademark) (Japan Zeon Co., Ltd.), Apel (registered trademark) (Mitsui Chemical Co., Ltd.).

Any suitable (meth)acrylic resin can be used as the (meth)acrylic resin. For example, poly(meth)acrylic acid such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth)acrylate copolymer, methacrylic acid Methyl ester-acrylate-(meth)acrylic acid copolymer, methyl (meth)acrylate-styrene copolymer (MS resin, etc.), alicyclic hydrocarbon-based polymer (for example, methyl methacrylate-A) A cyclohexyl acrylate copolymer, a methyl methacrylate-(meth)acrylic acid norbornene ester copolymer, etc.). Preferably, a poly(meth)acrylic acid C _1-6 alkyl ester such as methyl (meth) acrylate is used. As the (meth)acrylic resin, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is preferably used.

Any suitable additive may be added to the base film other than the above thermoplastic resin. Examples of such additives include ultraviolet absorbers, oxidation inhibitors, slip agents, plasticizers, release agents, coloring inhibitors, flame retardants, nucleating agents, charge inhibitors, pigments, and color formers. The content of the above-exemplified thermoplastic resin in the substrate film is desirably 50 to 100% by weight, preferably 50 to 99% by weight, more desirably 60 to 98% by weight, particularly desirably 70 to 97% by weight. When the content of the thermoplastic resin in the base film is less than 50% by weight, the high transparency and the like which are inherent in the thermoplastic resin may be insufficient.

The thickness of the base film can be appropriately determined, but it is preferably 1 to 500 μm in terms of workability such as strength and workability, preferably 1 to 300 μm, and more preferably 6 to 200 μm. The thickness of the substrate film is preferably from 5 to 150 μm.

In order to improve the adhesion to the polyvinyl alcohol-based resin layer, the base film is used. It is to be noted that at least the surface on the side where the polyvinyl alcohol-based resin layer is formed may be subjected to corona treatment, plasma treatment, flame treatment or the like. Further, in order to improve the adhesion, a thin layer such as an undercoat layer may be formed on the surface of the base film on the side where the polyvinyl alcohol-based resin layer is formed.

[Undercoat]

The undercoat layer is not particularly limited as long as it exhibits a certain degree of strong adhesion to both the base film and the polyvinyl alcohol resin layer. For example, a thermoplastic resin excellent in transparency, heat stability, and elongation can be used. Specifically, an acrylic resin or a polyvinyl alcohol-based resin may be mentioned, but it is not limited to these.

The resin constituting the undercoat layer may be used in a state of being dissolved in a solvent. Depending on the solubility of the resin, aromatic hydrocarbons such as benzene, toluene, and xylene, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and esters such as ethyl acetate and isobutyl acetate may be used. A chlorinated hydrocarbon such as chlorinated methane, trichloroethane or chloroform, an alcohol such as ethanol, 1-propanol, 2-propanol or 1-butanol, or the like, and a general organic solvent can be used. However, when the undercoat layer is formed by using a melt containing an organic solvent, the substrate may be dissolved, and it is preferable to select a solvent in consideration of the solubility of the substrate. It is desirable to form an undercoat layer from a coating liquid using water as a solvent in consideration of the influence on the environment. Among them, a polyvinyl alcohol-based resin having good adhesion is preferable.

The polyvinyl alcohol-based resin used as the undercoat layer may, for example, be a polyvinyl alcohol resin or a derivative thereof. Examples of the derivative of the polyvinyl alcohol resin include polyvinyl formal, polyvinyl acetal, and the like, and polyvinyl alcohol resin is ethylene. An olefin such as propylene, an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or crotonic acid, an alkyl ester of an unsaturated carboxylic acid, or a modified acrylamide. Among the above polyvinyl alcohol-based resin materials, a polyvinyl alcohol-based resin is preferably used.

In order to increase the strength of the undercoat layer, it is also possible to add a crosslinking agent to the above thermoplastic resin. As the crosslinking agent to be added to the resin, a known one such as an organic system or an inorganic system can be used. A suitable crosslinking agent can be appropriately selected for the thermoplastic resin to be used. For example, an epoxy-based, isocyanate-based, dialdehyde-based or metal-based crosslinking agent can be selected. As the epoxy-based crosslinking agent, either one-liquid curing type or two-liquid curing type can be used. Ethylene glycol epoxy propyl ether, polyethylene glycol epoxy propyl ether, glycerol di or triepoxypropyl ether, 1,6-hexanediol diepoxypropyl ether, trimethylolpropane Epoxy such as triepoxypropyl ether, diepoxypropylaniline or diepoxypropylamine.

Examples of the isocyanate-based crosslinking agent include trilene diisocyanate, hydrogenated trichloroethylene diisocyanate, trimethylolpropane-trichloroethylene diisocyanate adduct, and triphenylmethane three. Isocyanate, methylene bis(4-phenylmethane triisocyanate), isophorone diisocyanate, and isocyanates such as ketoxime blocks or phenolic blocks.

The dialdehyde-based crosslinking agent may, for example, be glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, maleic aldehyde or sebacaldehyde.

The metal-based crosslinking agent may, for example, be a metal salt, a metal oxide, a metal hydroxide or an organometallic compound, and the type of the metal is not particularly limited, and may be appropriately selected. Metal salts, metal oxides, metal hydroxides, for example, sodium, potassium, magnesium, calcium, aluminum, iron, nickel, zirconium, titanium, lanthanum, boron, zinc, copper, vanadium, chromium, tin, etc. Originally having a price above two a salt of a subvalent metal and its oxide, hydroxide.

The organometallic compound is a compound in which a metal atom is directly bonded to an organic group or has at least one structure bonded to an organic group via an oxygen atom or a nitrogen atom in the molecule. The organic group means a functional group containing at least a carbon element, and may, for example, be an alkyl group, an alkoxy group, a decyl group or the like. Further, the bonding means not only a covalent bond but also a coordination bond by a chelating compound or the like.

Suitable examples of the above metal organic compound include titanium organic compounds, zirconium organic compounds, aluminum organic compounds, and cerium organic compounds. These metal organic compounds may be used singly or in combination of two or more kinds as appropriate.

Specific examples of the titanium organic compound include, for example, tetra-n-butyl titanate, tetraisopropyl titanate, butyl titanate dimer, tetrakis(2-ethylhexyl) titanate, and titanic acid. Titanium orthoesters such as tetramethyl ester; titanium acetylacetonate, titanium tetraacetate, titanium acetylacetonate, titaniuim octylene glyconate, titanium lactate, titaniuim triethanolaminate, Titanium chelates such as titanium acetonate and titanium; titanium acylates such as titanium hydroxystearate; and the like.

Specific examples of the zirconium organic compound include zirconium n-propionate, zirconium n-butyrate, zirconium tetraethoxide, zirconium monoacetate, zirconium acetoacetate, zirconium acetoacetate醯 acetone and so on.

Specific examples of the aluminum organic compound include, for example, aluminum acetonitrile, an aluminum organic acid chelate, and the like. Specific examples of the above-mentioned cerium organic compound include compounds of the above-described titanium organic compound and a ligand exemplified as the zirconium organic compound.

In addition to the above-mentioned low molecular crosslinking agent, a methylolated melamine resin or a polymer-based crosslinking agent such as a polyamide resin may be used. "Sumirez (registered trademark) resin 650 (30)" and Sumirez (registered trademark) resin 675" (both trade names) sold by Sumitomo Chemtex Co., Ltd., etc. .

When a polyvinyl alcohol-based resin is used as the thermoplastic resin, a polyamine epoxy resin, a methylolated melamine, a dialdehyde, a metal chelate crosslinking agent or the like is particularly preferable.

The ratio of the thermoplastic resin to the crosslinking agent to be used for forming the undercoat layer is in the range of about 0.1 to 100 parts by weight based on 100 parts by weight of the resin, depending on the type of the resin and the type of the crosslinking agent. It is preferable to determine it suitably, especially in the range of about 0.1 to 50 weight part. Further, it is preferable that the coating liquid for the undercoat layer has a solid content concentration of about 1 to 25% by weight.

The thickness of the undercoat layer is preferably from 0.05 to 1 μm. More preferably, it is 0.5 to 1.0 μm. When the thickness is less than 0.05 μm, the effect of improving the adhesion between the base film and the polyvinyl alcohol layer is small, and when it is thicker than 1 μm, the polarizing plate becomes thick, which is not preferable.

In the formation of the undercoat layer, the coating method to be used is not particularly limited, and is applied by a wire bar coating method, a reverse roll coating method, a concave coating method, or the like, and a die coating method. Cloth method, comma coating, lip coating method, spin coating method, web coating method, fountain coating method, dip coating method, A spraying method or the like can be suitably selected and used by a known method.

[Polyvinyl alcohol-based resin layer forming step]

In the polyvinyl alcohol-based resin layer forming step (S10), a resin layer (polyvinyl alcohol-based resin layer) containing a polyvinyl alcohol-based resin is formed on one surface of the base film. The polyvinyl alcohol-based resin may, for example, be a polyvinyl alcohol resin or a derivative thereof. Examples of the derivative of the polyvinyl alcohol resin include polyvinyl formal and polyvinyl acetal, and the polyvinyl alcohol resin is unsaturated with an olefin such as ethylene or propylene, acrylic acid, methacrylic acid or crotonic acid. A carboxylic acid, an alkyl ester of an unsaturated carboxylic acid, a acrylamide or the like is modified. Among the above polyvinyl alcohol-based resin materials, a polyvinyl alcohol resin is preferably used.

The average degree of polymerization of the polyvinyl alcohol-based resin is preferably from 100 to 10,000, and more preferably from 1,000 to 10,000. In particular, 1500 to 8000 is ideal, and it is ideal at 2000 to 5000. The average degree of polymerization referred to herein is also a value obtained by the method specified in JIS K 6726 (1994). If the average degree of polymerization is less than 100, it is difficult to obtain ideal optical characteristics. When the amount exceeds 10,000, the solubility in water is deteriorated, and formation of a polyvinyl alcohol-based resin layer is difficult.

The polyvinyl alcohol-based resin used in the present invention is preferably a saponified product. The range of saponification degree is preferably from 80.0 mol% to 100.0 mol%, more preferably from 90.0 mol% to 99.5 mol%, and further preferably from 94.0 mol% to 99.0 mol%. When the degree of saponification is less than 80.0 mol%, the water resistance and the moist heat resistance after the production of the polarizing plate are remarkably poor. In addition, when a polyvinyl alcohol-based resin having a degree of saponification of more than 99.5 mol% is used, the dyeing speed is remarkably slow, and there is a case where a polarizing laminated film having insufficient polarizing performance cannot be obtained, and the production is required to be several times as many times as usual. The unfavorable situation of time.

The degree of saponification referred to herein is that the acetic acid group contained in the polyvinyl acetate-based resin of the raw material of the polyvinyl alcohol-based resin is changed to a hydroxyl group in the saponification step. The ratio expressed by the unit ratio (% by mole) is a value defined by the following formula. It can be obtained by the method specified in JISK 6726 (1994).

Degree of saponification (% by mole) = (number of hydroxyl groups) ÷ (number of hydroxyl groups + number of acetate groups) × 100

The higher the degree of saponification, the higher the ratio of the hydroxyl group, that is, the lower the ratio of the acetate group which inhibits crystallization.

Further, the polyvinyl alcohol-based resin used in the present invention may have a modified partially modified polyvinyl alcohol. For example, the polyvinyl alcohol-based resin may be an olefin such as ethylene or propylene, an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or crotonic acid, an alkyl ester of an unsaturated carboxylic acid or a acrylamide or the like. The ratio of upgrading is ideally less than 30%, and less than 10% is ideal. When the modification is more than 30 mol%, it becomes difficult to adsorb the dichroic dye, and the polarizing performance is lowered.

The polyvinyl alcohol-based resin having such a property may, for example, be PVA124 manufactured by Kuraray (saponification degree; 98.0 to 99.0 mol%, PVA117 (saponification degree: 98.0 to 99.0 mol%), PVA624 (saponification) Degree: 95.0 to 96.0 mol%) and PVA617 (saponification degree: 94.5 to 95.5 mol%); for example, AH-26 (saponification degree: 97.0 to 98.8 mol%) manufactured by Nippon Synthetic Chemical Industry Co., Ltd., AH -22 (saponification degree: 97.5 to 98.5 mol%), NH18 (saponification degree: 98.0 to 99.0 mol%), and N-300 (saponification degree: 98.0 to 99.0 mol%); for example, JAPAN VAM & POVAL CO. , LTD (share) JC-33 (saponification degree: 99.0 mol% or more), JM-33 (saponification degree: 93.5 to 95.5 mol%), JM-26 (saponification degree: 95.5 to 97.5 mol%), JP-45 (saponification degree: 86.5 to 89.5 mol%), JF-17 (saponification degree: 98.0 to 99.0 mol%), JF-17L (saponification degree: 98.0 to 99.0% by mole) and JF-20 (saponification degree: 98.0 to 99.0% by mole) and the like can be suitably used in the present invention.

The above polyvinyl alcohol-based resin may be added as needed, and an additive such as a plasticizer or a surfactant may be used. The plasticizer may, for example, be a polyol, a condensate thereof or the like, such as glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol or polyethylene glycol. The blending amount of the additive is not particularly limited, but it is preferably 20% by weight or less in the polyvinyl alcohol-based resin.

The thickness of the polyvinyl alcohol-based resin layer is desirably more than 3 μm and not more than 20 μm, more preferably 5 to 20 μm. When it is 3 μm or less, it becomes too thin after stretching, and the dyeability is remarkably deteriorated. When the thickness exceeds 20 μm, the thickness of the polarizing plate becomes thick, which is not preferable.

In the polyvinyl alcohol-based resin layer of the present invention, the polyvinyl alcohol-based resin solution obtained by dissolving the powder of the polyvinyl alcohol-based resin in a good solvent is applied to the surface of one side of the base film, and the solvent is evaporated to form a solvent. . In this way, a thin polyvinyl alcohol-based resin layer can be formed.

A method of coating a polyvinyl alcohol-based resin solution on a substrate film by a wire bar coating method, a reverse roll coating method, a roll coating method such as a concave coating method, or a die coating method A doctor blade coating method, a lip coating method, a spin coating method, a mesh coating method, a spray coating method, a dip coating method, a spray coating method, or the like can be suitably selected and used. The drying temperature is, for example, 50 to 200 ° C, desirably 60 to 150 ° C, and the drying time is, for example, 2 to 20 minutes.

Further, in the polyvinyl alcohol-based resin layer of the present invention, a raw material film containing a polyvinyl alcohol-based resin may be adhered to the surface of one side of the base film. form.

[Polarization film processing step (S20)] (extension step)

In the stretching step (S21), the laminated film including the base film and the polyvinyl alcohol-based resin is stretched. At this time, the one-axis extension is ideal. Further, it is preferable that the original length of the laminated film is extended to more than 5 times in one axis. Preferably, the one-axis extension is a stretching ratio of more than 5 times and less than 17 times. More preferably, the one-axis extension is a stretching ratio of more than 5 times and less than 8 times. When the stretching ratio is 5 times or less, the polyvinyl alcohol-based resin layer is not sufficiently aligned, and as a result, the degree of polarization of the polarizing film is not sufficiently high. On the other hand, when the stretching ratio exceeds 17 times, the laminated film at the time of stretching tends to be cracked, and the thickness of the laminated film becomes unnecessarily thin, and the workability and workability in the subsequent step are lowered.

The extension processing in the extension step (S21) is not limited to one extension, and may be performed in multiple stages. When the multi-stage processing is performed, it is preferable to carry out the stretching treatment by combining the entire length of the elongation processing up to a stretching ratio of more than 5 times.

In the extending step (S21), when the one-axis stretching is performed, the longitudinal stretching process performed in the longitudinal direction of the laminated film, the lateral stretching process performed in the width direction, the oblique stretching process, or the like is performed. The vertical stretching method may be a roll stretching method, a compression stretching method, or the like, and a lateral stretching method may be a tenter method or the like.

Further, the stretching treatment may be either a wet stretching method or a dry stretching method. However, when the dry stretching method is used, it is preferable to select a temperature point from a wide range when the laminated film is stretched.

(staining step)

In the dyeing step (S22), the polyvinyl alcohol-based resin layer of the laminated film is dyed with a dichroic substance. Examples of the dichroic substance include iodine and an organic dye. For organic dyes, for example, red BR, red LR, red R, pink LB, flaming red BL, Bordeaux red GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy RY, green LG, purple LB, Purple B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Dark Red GL, Dark Red KGL, Congo Red, Bright Purple BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Direct Sky blue, direct fast orange S (direct fast orange S), direct fast black (direct fast black) and so on. These dichroic substances may be used alone or in combination of two or more kinds.

The dyeing step is carried out, for example, by immersing the entire layered film including the base film and the polyvinyl alcohol-based resin layer in a solution (dyeing solution) containing the above-mentioned dichroic substance. As the dyeing solution, a solution in which the above-mentioned dichroic substance is dissolved in a solvent can be used. In the solvent of the dyeing solution, water is generally used, but an organic solvent compatible with water may be added. The concentration of the dichroic substance is preferably 0.01 to 10% by weight, more preferably 0.02 to 7% by weight, and particularly preferably 0.025 to 5% by volume.

When iodine is used as a dichroic substance, since the dyeing efficiency can be further improved, it is preferable to add an iodide. Such an iodide may, for example, be potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, cesium iodide, calcium iodide, tin iodide, iodine. Titanium and the like. The addition ratio of these iodides is preferably 0.01 to 20% by weight in the dyeing solution. Among the iodides, potassium iodide is particularly preferred. When adding potassium iodide, iodine and The ratio of potassium iodide is preferably in the range of 1:5 to 1:100 by weight, more preferably in the range of 1:6 to 1:80, and particularly preferably in the range of 1:7 to 1:70.

The immersion time of the laminated film in the dyeing solution is not particularly limited, but is usually in the range of 15 seconds to 15 minutes, and preferably 20 seconds to 6 minutes. Further, the temperature of the dyeing solution is preferably in the range of 10 to 60 ° C, and preferably in the range of 20 to 40 ° C.

In the dyeing step, the dichroic substance is adsorbed on the polyvinyl alcohol-based resin layer of the laminated film to align the dichroic substance. The dyeing step (S22) may be carried out immediately before or after the stretching step (S21), but the stretching step is applied to the laminated film at a point where the alignment of the dichroic substance adsorbed by the polyvinyl alcohol-based resin layer is good. It is ideal after (S21).

(other steps)

In the polarizing film formation treatment step (S20), in addition to the stretching step (S21) and the dyeing step (S22), a crosslinking step can be performed. The crosslinking step can be carried out, for example, by immersing the laminated film in a solution (crosslinking solution) containing a crosslinking agent. As the crosslinking agent, a conventionally known one can be used. For example, a boron compound such as boric acid or borax, glyoxal or glutaraldehyde can be mentioned. These are either a class or a combination of two or more types.

As the crosslinking solution, a solution in which a crosslinking agent is dissolved in a solvent can be used. For the solvent, for example, water may be used, but an organic solvent compatible with water may be further contained. The concentration of the crosslinking agent in the crosslinking solution is not limited thereto, but is preferably in the range of 1 to 20% by weight, and preferably 6 to 15% by weight.

In the crosslinking solution, it is also possible to add an iodide. The in-plane polarization characteristics of the polyvinyl alcohol-based resin can be made more uniform by the addition of the iodide. As the iodide, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, cesium iodide, calcium iodide, tin iodide, titanium iodide . The content of the iodide is 0.05 to 15% by weight, preferably 0.5 to 8% by weight.

The immersion time of the laminated film in the crosslinking solution is usually from 15 seconds to 20 minutes, and preferably from 30 seconds to 15 minutes. Further, the temperature of the crosslinking solution is preferably in the range of 10 to 80 °C.

The crosslinking step is carried out by mixing the crosslinking agent in the dyeing solution, and the crosslinking step and the dyeing step (S22) can be carried out simultaneously. Further, the crosslinking step may be performed simultaneously with the stretching step (S21).

In the polarizing film formation treatment step (S20), it is preferred to carry out the cleaning step and the drying step. In the cleaning step, a water washing treatment can be performed. The water washing treatment can be usually carried out by immersing the laminated film which has undergone the extending step (S21) and the dyeing step (S22) in pure water such as ion-exchanged water or distilled water. The water washing temperature is usually from 3 to 50 ° C, preferably from 4 ° C to 20 ° C. The immersion time is usually 2 to 300 seconds, preferably 8 seconds to 240 seconds.

The washing step may be carried out by combining a washing treatment with an iodide solution and a water washing treatment, or a solution of a liquid alcohol such as methanol, ethanol, isopropanol, butanol or propanol. Further, after the washing step, a step of removing water by using a nip roll or a jet scraper may be used.

After the washing step, it is desirable to dry the laminated film. In this drying, a drying step containing a temperature of 60 ° C or higher is preferable, and it contains 70 ° C or more. The drying step of the temperature is ideal. Of course, a multi-stage dry operation step containing different temperatures is also possible. At this time, in the multi-stage drying step, any one of the drying steps may be 60 ° C or higher.

In addition to the temperature, it is necessary to enhance the drying force, and it is also possible to optimize the circulation method of the hot air such as the air volume and the wind direction, or to provide an IR heater that can be locally heated. As these subsidies are more efficient in drying, they contribute to the improvement of productivity.

The upper limit of the drying temperature is preferably lower than the boiling point of water, and it is preferably less than 100 °C. Further, it is preferably 95 ° C or less, and most preferably 90 ° C or less.

From the above polarizing film formation treatment step (S20), the polyvinyl alcohol-based resin layer functions as a polarizing film. In the present specification, the polyvinyl alcohol-based resin layer subjected to the polarizing film formation treatment step (S20) is referred to as a polarizing film.

The obtained polarizing film had a shrinkage force per 2 mm width in a direction orthogonal to the absorption axis of the polarizing film, and was 1.0 N or less when held at a temperature of 80 ° C for 240 minutes. Further, the contraction force per 2 mm width in the absorption axis direction of the polarizing film is preferably 2.5 N or less when held at a temperature of 80 ° C for 240 minutes. Further, the thickness of the obtained polarizing film is preferably 10 μm or less.

[Protective film bonding step]

In the protective film bonding step (S30), a protective film is bonded to the surface opposite to the surface on the base film side of the polarizing film. The method of bonding a protective film is a method of bonding a polarizing film and a protective film with an adhesive, and bonding the polarizing film and a protective film with an adhesive.

(protective film)

In the protective film used in the present invention, a simple protective film having no optical function may be used, and a protective film having an optical function such as a retardation film or a brightness enhancement film may be used. The material of the protective film is not particularly limited, and examples thereof include a cyclic polyolefin resin film and a cellulose acetate resin film made of a resin such as triethyl fluorenyl cellulose or diethyl hydrazine cellulose. A polyester resin film made of a resin such as polyethylene terephthalate, polyethylene naphthalate or polybutylene terephthalate, a polycarbonate resin film, an acrylic resin film, and polyacrylic acid. An ester-based resin film or the like is a film widely used in the art.

For the cyclic polyolefin-based resin, a product such as Topas (registered trademark) (Ticona), Arton (registered trademark) (JSR), and ZEONOR (registered trademark) (Japan Zeon) are available. System), ZONEX (registered trademark) (made by Japan Zeon Co., Ltd.), Apel (registered trademark) (Mitsui Chemical Co., Ltd.). When the cyclic polyolefin-based resin is formed into a film, a known method such as a solvent casting method or a melt-extrusion method can be suitably used. Pre-formed ring-shaped polycondensation, such as the squirrel (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (made by Sekisui Chemical Co., Ltd.), ZEONOA (registered trademark) membrane (manufactured by Optes) A product of a film made of an olefin resin may be used.

The cyclic polyolefin resin film may be a film that extends through one axis or two axes. Due to the elongation, an arbitrary retardation value is imparted to the cyclic polyolefin resin film. For extension, the film roll is usually continuously carried out during the winding, to heat the furnace, to proceed in the direction in which the rolls are made, in a direction perpendicular to the direction, or to both of them. The temperature of the heating furnace is usually in the range from the glass transition temperature of the cyclic polyolefin-based resin to the glass transition temperature of +100 °C. The magnification of the extension is usually 1.1 to 6 times in each direction, and ideally 1.1 to 3.5 times.

Since the cyclic polyolefin-based resin film generally has poor surface activity, it is ideal for surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, and saponification treatment on the bottom surface adhered to the polarizing film. . Among them, corona treatment is particularly suitable for plasma treatment which is relatively easy to implement.

For the cellulose acetate resin film, a suitable product can be used, for example, Fujitac (registered trademark) TD 80 (made by Fujifilm Co., Ltd.), Fujitac (registered trademark) TD80UF (made by Fujifilm Co., Ltd.), Fujitac (registered) Trademark) TD80UZ (Fuji Film Co., Ltd.), Fujitac (registered trademark) TD40UZ (made by Fujifilm Co., Ltd.), KC8UX2M (Konica Minalta Opto Co., Ltd.), KC4UY (Konica Minolta Opto Co., Ltd.).

A liquid crystal layer or the like can be formed on the surface of the cellulose acetate resin film in order to improve the viewing angle characteristics. Further, in order to impart a phase difference, the cellulose acetate-based resin may be stretched. The cellulose acetate-based resin film is usually subjected to a saponification treatment in order to improve the adhesion to the polarizing film. For the saponification treatment, a method of immersing in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide can be employed.

When the protective film produced as described above is in the state of a roll, the films tend to be adjacent to each other and tend to form a block. Therefore, it is preferable to apply a concavo-convex process to the end portion of the roll, or to insert a tape at the end portion, or to fit it. The film is wound into a roll by a protective film or the like.

The thickness of the protective film is preferably thin, but when it is too thin, the strength is lowered, and the workability is poor. On the other hand, when the thickness is too large, the transparency is lowered, or the ripening time required after lamination is lengthened. Therefore, the thickness of the protective film is 90 μm. The lower is ideal, and it is preferably 5 to 60 μm. In addition, the thickness of the panel and the module are required to be thinner, and the thickness of the polarizing film is also required. Therefore, the total thickness of the polarizing film and the protective film is preferably 100 μm or less, more preferably 90 μm or less, and still more preferably 80 μm. the following.

Further, an optical layer such as a hard coat layer, an antiglare layer, or an antireflection layer may be directly formed on the surface of the protective film. A method of forming these optical layers on the surface of the protective film is not particularly limited, and a known method can be used.

(Adhesion of protective film using adhesive)

When an adhesive is used for the adhesion between the protective film and the polarizing film, the adhesive usually contains an acrylic resin, a styrene resin, a polyoxymethylene resin or the like as a base polymer, and an isocyanate compound or an epoxy compound is added thereto. A crosslinker composition such as an aziridine compound. Further, fine particles may be contained to form an adhesive layer which exhibits light scattering properties.

The thickness of the adhesive layer is preferably from 1 to 40 μm, but the thickness is preferably within a range of characteristics that do not deteriorate workability and durability, and is preferably from 3 to 25 μm. It has good workability at 3 to 25 μm, and is also a suitable thickness in suppressing dimensional change of the polarizing film. When the adhesive layer is less than 1 μm, the adhesiveness is lowered, and when it exceeds 40 μm, the adhesive is likely to overflow.

In the method of bonding a protective film to a polarizing film with an adhesive, after the adhesive layer is provided on the surface of the protective film, it may be bonded to the polarizing film, and after the adhesive layer is provided on the surface of the polarizing film, the protective film may be bonded thereto. Also.

The method of forming the adhesive layer is not particularly limited, and the above solution containing the base polymer and other components is coated on the polarizing film or the protective film. After the cloth is dried to form an adhesive layer, the protective film may be bonded to the polarizing film. After the adhesive layer is formed on the separator, the protective film may be transcribed on the protective film surface or the polarizing film surface. Further, when the adhesive layer is formed on the surface of the protective film or the polarizing film, the protective film or the polarizing film surface or one side or both sides of the adhesive may be subjected to a close treatment as needed, for example, corona treatment or the like may be applied.

(Adhesive film bonding using an adhesive)

When an adhesive is used for the bonding of the protective film and the polarizing film, for example, a water-based adhesive such as a polyvinyl alcohol-based resin aqueous solution or an aqueous two-liquid urethane-based emulsion adhesive can be used as the adhesive. When a cellulose acetate film which has been hydrophilized by a saponification treatment or the like is used as the protective film, a water-based adhesive for bonding to a polarizing film is used, and a polyvinyl alcohol-based resin water bath can be suitably used. A vinyl alcohol-based resin is used as an adhesive, and a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate of a vinyl acetate individual polymer has vinyl acetate and other copolymerizable copolymers thereof. A vinyl alcohol-based copolymer obtained by saponifying a monomer copolymer, and a modified polyvinyl alcohol-based polymer obtained by modifying a part of these hydroxyl groups. The water-based adhesive may be added as a polyvalent aldehyde, a water-soluble epoxy compound, a melamine-based compound, a zirconia compound, a zinc compound or the like as an additive. When such a water-based adhesive is used, the adhesive layer thus obtained is usually 1 μm or less, and the cross section is observed by a general optical microscope, and the adhesive layer is not actually observed.

The method of bonding the polarizing film and the protective film with a water-based adhesive is not particularly limited. For example, the surface of the polarizing film and/or the protective film is uniformly coated with an adhesive, and the other film is superposed on the coated surface. Rolling, etc. Method etc. Usually, the adhesive is applied at a temperature of 15 to 40 ° C after its preparation, and the bonding temperature is usually in the range of 15 to 30 ° C.

When a water-based adhesive is used, after the polarizing film and the protective film are bonded together, the laminated film is dried in order to remove water contained in the aqueous adhesive. The temperature of the drying oven is preferably from 30 ° C to 90 ° C. When the temperature is less than 30 ° C, the surface of the polarizing film and the surface of the protective film tend to be easily peeled off. When the temperature is above 90 ° C, the optical properties are deteriorated due to heat. The drying time can be set from 10 to 1000 seconds.

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

Further, as an adhesive when the polarizing film and the protective film are bonded together, a photocurable adhesive can also be used. The photocurable adhesive agent may, for example, be a mixture of a photocurable epoxy resin and a photocationic polymerization initiator.

When the polarizing film and the protective film are bonded together with a photocurable adhesive, a conventionally known method can be used, and for example, a casting method, a Myer bar coating method, or a concave coating method can be used. Cloth method, comma coater method, doctor blade method, die coating method, dip coating method, spray method, etc., on the bonding surface of the polarizing film and/or the protective film A method in which an adhesive is applied and the two are overlapped. The casting method is a method in which the polarizing film or the protective film of the object to be coated is moved in a direction slightly perpendicular to the horizontal direction, or in an oblique direction therebetween, and the surface is flown down to expand the adhesive. .

After applying an adhesive to the surface of the polarizing film or the protective film, the polarizing film and the protective film are bonded by a nip roll or the like via the adhesive application surface. then. In addition, a method in which the adhesive film is placed on the protective film and the adhesive film is dropped between the polarizing film and the protective film, and the laminated film is uniformly pressed by a roller or the like, and can be suitably used. At this time, metal or rubber or the like can be used as the material of the roller. Further, it is also preferable to use a method in which an adhesive is dropped between the polarizing film and the protective film, and the laminated film is passed between a roll and a roll and pressurized. At this time, these rollers are the same material, and different materials are also available. The thickness of the adhesive layer after bonding using the above-mentioned rolls and before curing is preferably 5 μm or less and preferably 0.01 μm or more.

On the surface of the polarizing film and/or the protective film, in order to improve the adhesion, a surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, or saponification treatment may be suitably applied. The saponification treatment may be a method of immersing in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide.

When a photocurable resin is used as an adhesive, the polarizing film is bonded to the protective film, and then the active energy ray is irradiated to cure the photocurable adhesive. The light source of the active energy ray is not particularly limited, but an active energy ray having a light-emitting distribution at a wavelength of 400 nm or less is preferable. Specifically, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, and an ultraviolet ray are used. Lights, microwave-excited mercury lamps, metal halide lamps, etc. are ideal.

The light-irradiating strength of the photocurable developer is appropriately determined depending on the composition of the photocurable adhesive, and is not particularly limited, and the irradiation intensity in the wavelength region effective for activation of the polymerization initiator is 0.1 to 6000 mW/cm. ² is ideal. When the irradiation intensity is 0.1 mW/cm ² or more, the reaction time is not excessively long, and when it is 6000 mW/cm ² or less, the heat of the light source and the heat of the photocurable adhesive are yellowed or the epoxy resin is yellowed or The deterioration of the polarizing film is small. The light irradiation time of the photocurable adhesive is not particularly limited as long as it is to be cured by the cured photocurable adhesive, but the integrated light amount expressed by the product of the above-described irradiation intensity and irradiation time is set to 10 to 10,000 mJ/cm ² is ideal. When the amount of light of the photocurable adhesive is 10 mJ/cm ² or more, the amount of the active species derived from the polymerization initiator is sufficient to allow the curing reaction to proceed more reliably. When the amount is 10000 mJ/cm ² or less, the irradiation time is not excessively long. Can maintain good productivity. Further, the thickness of the adhesive layer after the active energy ray irradiation is usually about 0.001 to 5 μm, preferably 0.01 μm or more and 2 μm or less, and more preferably 0.01 μm or more and 1 μm or less.

When the photocurable adhesive is cured by irradiation with an active energy ray, it is preferable that the polarizing film has a degree of polarization, a transmittance, a hue, and a transparency of the protective film, and the functions of the polarizing film are not deteriorated.

[Substrate film peeling step]

In the method for producing a polarizing plate of the present invention, after the protective film is bonded to the protective film bonding step (S30) of the polarizing film, the substrate film peeling step (S40) is performed. In the base film peeling step (S40), the base film is peeled off from the laminated film, and the method of peeling the base film is not particularly limited, and the release film can be applied to a usual polarizing plate with an adhesive (separator). The stripping step is stripped in the same manner. After the protective film bonding step (S30), the protective film may be directly peeled off immediately, and after the protective film is applied to the bonding step (S30), it may be wound into a roll shape, and then peeled off during the winding out.

[Optical film lamination step]

The polarizing plate of the present invention manufactured as above, in the optical film lamination step In (S50), other optical films may be laminated in practice. Further, the protective film may have the function of these optical films. In another example of the optical film, a protective film, a retardation film, and a polarizing light that transmits a polarized light having opposite properties, and a reflective polarizing film that exhibits a polarized light having opposite properties, may be provided with a concave-convex shape on the surface. The anti-glare functional film is provided with a surface reflection preventing function film, a reflective film having a reflecting function on the surface, a semi-transmissive reflecting film having a reflecting function and a transmitting function, and a viewing angle compensation film. The ideal is a protective film or a retardation film.

The protective film may be the same film as the above protective film. The retardation film is, for example, a retardation film containing a triethylenesulfonyl cellulose resin, a polycarbonate resin, or a cyclic polyolefin resin. For the product of the retardation film containing a cyclic polyolefin resin, an Arton (registered trademark) film (manufactured by JSR), Escena (registered trademark) (made by Sekisui Chemical Co., Ltd.), Zeonoa ( Registered trademark) film (made by Optes), etc.

For example, DBEF (manufactured by 3M Co., Ltd., can be started by Sumitomo 3M), APF, which is a product of a reflective polarizing film that reflects the polarized light of the opposite nature. (3M company system, can be started by Sumitomo 3M (shares)). The viewing angle compensation film may be a liquid crystal compound coated on the surface of the substrate, and an optical compensation film having an alignment. A product which is a liquid crystal compound coated on the surface of the substrate and which has an optical compensation film which is aligned, may be a WV film (manufactured by Fuji Film Co., Ltd.), an NH film (manufactured by Nippon Oil Co., Ltd.), NR. Membrane (Nippon Oil Co., Ltd.) and the like.

[Adhesive layering step]

In the adhesive layering step (S60) shown in Fig. 1, in the above The most surface layer layer adhesive on the opposite side of the protective film (the side on which the base film is peeled off). When at least one optical film is to be laminated on the surface side from which the base film is peeled off, in this step, the layer adhesive layer on the side opposite to the polarizing film of the optical film farthest from the polarizing film is preferable.

The polarizing plate of the present invention is a polarizing plate having a polarizing film and a protective film which suppress a predetermined contraction force, and an adhesive layer having a storage modulus of 0.20 MPa or more at 23 ° C on the outermost side thereof, the polarizing plate It is attached to the liquid crystal cell via the aforementioned adhesive layer.

In the conventional polarizing film, a single film of a polyvinyl alcohol-based resin layer is stretched and dyed, and it is necessary to directly thin the single film when it is thinned. However, such thinning is extremely difficult in the operability of the subsequent steps, and the polarizing film thus obtained is a film having a large shrinkage force. Therefore, in order to alleviate the shrinkage force of such a polarizing film, it is known that the adhesive layer of the outermost layer of the polarizing plate has a low storage elastic modulus at 23 ° C in the outermost layer of the polarizing plate.

On the other hand, in the present invention, a predetermined polarizing film having a thin shape and a low shrinkage force produced by using a base film is provided, and the storage elastic modulus at 23 ° C is 0.20 MPa or more as the outermost layer of the polarizing plate. The adhesive layer, and thus the cracking or peeling of the polarizing film or the like, light leakage can be suppressed, and the change in the size behavior when the polarizing plate is moved from a high temperature environment to a room temperature environment can be more effectively suppressed.

Moreover, the storage elastic modulus at 23 ° C of the adhesive layer provided on the outermost layer of the polarizing plate is not less than 0.20 MPa, and the storage elastic modulus at 80 ° C is 15 MPa or more, which is particularly effective in suppressing the high temperature environment. Size lifting Dynamic changes.

When the storage modulus at 23 ° C is less than 0.2 MPa, for example, the size behavior when moving from a high temperature environment to a room temperature environment becomes large. Further, the storage modulus at 80 ° C was changed from the 0.15 MPa hour to the size in a high temperature environment.

The storage modulus of the adhesive layer formed of the adhesive at 23 ° C was 0.20 MPa or more. It is desirable that the adhesive layer has a storage modulus at 80 ° C of 0.15 MPa or more.

The adhesive used in this step is formed by using various adhesives conventionally used for image display devices as a substrate. For example, there are adhesives such as acrylic, rubber, urethane, polyoxyl, and polyvinyl ether. Further, an energy ray hardening type, a heat curing type, or the like may be used. Among these, a pressure-sensitive adhesive having an acrylic resin such as excellent transparency, weather resistance, and heat resistance as a base polymer is particularly suitable.

The acrylic resin is not particularly limited, and is butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. a single polymer of an alkyl acrylate, or a copolymer of two or more kinds of alkyl (meth) acrylate, and a copolymer of one or more kinds of alkyl (meth) acrylate and a polar monomer. Suitable for use. Examples of the polar monomer include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acrylamide, (methyl). 2-N,N-dimethylaminoethyl acrylate, cyclopropyloxy (meth)acrylate, etc., having a carboxyl group, a hydroxyl group, a decylamino group, an amine group, an epoxy group or the like.

These acrylic resins can be used alone, but usually And use a crosslinking agent. The crosslinking agent may, for example, be a metal carboxylic acid salt formed between a divalent or polyvalent metal ion and a carboxyl group, a guanamine bond formed between the polyamine compound and the carboxyl group, a polyepoxide compound or a polyol compound, and An ester bond is formed between the carboxyl groups, and a polyisocyanate compound is formed to form a guanamine bond with the carboxyl group. Among them, a polyisocyanate compound is widely used as an organic crosslinking agent.

The energy ray-curable pressure-sensitive adhesive has a property of being cured by irradiation with an energy ray such as an ultraviolet ray or an electron beam, and is also adhered to a film such as a film before being irradiated with an energy ray, and is irradiated by an energy ray. A pressure-sensitive adhesive that reinforces the adhesion properties of adhesion. In the energy ray-curable pressure-sensitive adhesive, it is preferable to use an ultraviolet-curable pressure-sensitive adhesive. The energy ray-curable pressure-sensitive adhesive is generally composed of an acrylic resin and an energy ray polymerizable compound as a main component. Usually, a crosslinking agent is further blended, and a photoinitiator, a photosensitizer or the like may be mixed as needed.

The pressure sensitive adhesive used in the present invention, in addition to the above-mentioned base polymer and cross-linking agent, is required to adjust the adhesion, cohesive force, viscosity, elastic modulus, glass transition temperature, etc. of the pressure-sensitive adhesive as needed. For example, a resin such as a natural product or a synthetic resin, an adhesive imparting resin, a strong oxidation preventing agent, a dye, a pigment, an antifoaming agent, an etchant, a photopolymerization initiator, and the like may be blended. Further, it may be a fine pressure-sensitive adhesive layer which exhibits light scattering properties by containing fine particles.

The pressure-sensitive adhesive layer specified in the present invention is composed of a pressure-sensitive adhesive having a storage modulus of 0.20 MPa or more at 23 ° C. The storage modulus is a viscoelasticity measuring device using a product, and for example, as shown in the examples described later, It was measured by the viscoelasticity measuring apparatus "DYNAMlC ANALYZER RDA II" by REOMETRIC company. The storage elastic modulus of the pressure-sensitive adhesive used for the optical film for a normal image display device or image display device is about 0.10 MPa, and the storage elastic modulus of the adhesive layer specified in the present invention is 0.20 MPa. The above) is a relatively high value.

The means for setting the storage modulus to such a high value is not particularly limited. For example, in the usual pressure-sensitive adhesive as described above, an oligomer is blended, specifically, an urethane acrylate system is blended. The oligomer is effective. It is preferable that after the urethane acrylate-based oligomer is blended, a pressure-sensitive adhesive which is added with an isocyanate-based crosslinking agent is a pressure-sensitive adhesive which exhibits a high storage modulus from a low-temperature field to a high-temperature field. . A pressure-sensitive adhesive which is blended with a urethane acrylate-based oligomer or a film-like pressure-sensitive adhesive which is cured by ultraviolet rays by coating it on a support film is known.

The thickness of the pressure-sensitive adhesive layer is preferably from 1 to 40 μm. In order to obtain a thin composite polarizing plate, it is preferable to form a thin pressure-sensitive adhesive layer in a range that does not deteriorate properties such as workability and durability. For example, when it is 3 to 25 μm, good workability is maintained. It is suitable to suppress the dimensional change of the polarizing film.

The method of forming the adhesive layer is not particularly limited. For example, after the adhesive layer is formed on the polarizing film or the optical film by using the above-mentioned adhesive, the laminate includes a separation of the resin film applied by the release treatment such as polyfluorene. The method of the article, or the method of transcribed on the polarizing film or the optical film after forming the adhesive layer on the above-mentioned separator. Further, when the adhesive layer is formed on the polarizing film or the optical film, it is preferably laminated on the polarizing film and the optical film or the adhesive as needed. The side surface (one side or both sides) may be subjected to a treatment for improving the adhesion, such as corona treatment.

[Lamination step of optical film with adhesive layer]

In the lamination step (S60')) of the optical film with the adhesive layer shown in Fig. 2, the outermost surface of the opposite side of the protective film (the side on which the base film is peeled off) is placed on the front side. An adhesive optical film formed of an adhesive is laminated on the outermost surface of the adhesive layer side. Here, the adhesive layer is the same adhesive layer as the above-described adhesive layer lamination step, and the optical film is the same optical film as the above-described optical film lamination step.

The adhesive layer is a surface that is bonded to the liquid crystal cell of the polarizing plate, that is, it is ideally located on the outermost side of the polarizing plate. This is because the closer to the polarizing film, the more the shrinkage of the polarizing film is affected. It is preferable that the above-mentioned adhesive layer is provided at a position far from the polarizing film to reduce dimensional change.

Further, in the production of the liquid crystal display device, the above-mentioned polarizing film is bonded to at least one side of the liquid crystal cell via the above-mentioned adhesive layer.

Example

Hereinafter, the present invention will be more specifically described by showing examples and comparative examples, but the present invention is not limited by these examples.

[Measurement of storage elastic modulus]

In the following examples, the storage elastic modulus of the adhesive (pressure-sensitive adhesive) was measured by using a cylinder having a diameter of 8 mm and a thickness of 1 mm as a test piece, and using a measuring instrument "DYNAMIC ANARYZER RDA II" manufactured by REOMETRIC Co., Ltd. at a frequency of 1 Hz. The storage elastic modulus (G') at 23 ° C and 80 ° C was measured by a torsional shear method.

[adhesive]

In the following examples, the following materials were used as the adhesive.

(Adhesive A)

A copolymer of butyl acrylate and acrylic acid is blended with an urethane acrylate oligomer, and an organic solvent solution of an isocyanate-based crosslinking agent is added, and a 38 μm thick polyethylene terephthalate film is applied. On the release treated surface of the (separator film), a sheet-like adhesive having a thickness of 25 μm after drying was applied by a die coater. Here, as a result of measuring the storage modulus of the adhesive by the above-described method, the storage elastic modulus of the adhesive A was 0.41 MPa at 23 ° C and 0.19 MPa at 80 ° C.

(Adhesive B)

An organic solvent solution of an acrylic adhesive (C) obtained by adding an isocyanate crosslinking agent to a copolymer of butyl acrylate and methyl acrylate and 2-phenoxyethyl acrylate and 2-hydroxyethyl acrylate. The release-treated surface of the polyethylene terephthalate film (separator film) having a thickness of 38 μm which was subjected to release treatment was applied by a die coater to a sheet-like adhesive with a separator film having a thickness of 20 μm after drying. Agent. Further, as a result of measuring the storage modulus of the adhesive B by the above-described method, the storage elastic modulus of the adhesive B was 0.08 MPa at 23° and 0.04 MPa at 80°C.

(Adhesive C)

An organic solvent solution obtained by adding an isocyanate crosslinking agent to a copolymer of butyl acrylate and acrylic acid is applied to a release treatment surface of a polyethylene terephthalate film (separation film) having a thickness of 38 μm. The die coater is coated to have a thickness of 15 μm and a separator-like flaky paste after drying. Attention. Further, as a result of measuring the storage modulus of the adhesive C by the above-described method, the storage elastic modulus of the adhesive C was 0.05 MPa at 23° and 0.04 MPa at 80°C.

(Adhesive D)

An adhesive layer of a urethane acrylate oligomer and an isocyanate crosslinking agent is added to a copolymer of butyl acrylate and acrylic acid, and a polyethylene terephthalate film (separation film) subjected to a release treatment is applied. The mold-treated surface was formed into a sheet-like adhesive having a thickness of 5 μm. Further, as a result of measuring the storage modulus of the adhesive D by the above-described method, the storage elastic modulus of the adhesive D was 0.5 MPa at 23° and 0.21 MPa at 80°C.

[Relax film with adhesive]

In the following examples, the following retardation film was used as the retardation film with an adhesive.

(Relax film X with adhesive)

A film (phase difference film/adhesive A/partition film) to which the adhesive A was applied after corona treatment was applied to one surface of a retardation film containing a norbornene resin having a thickness of 20 μm.

(Relax film Y with adhesive)

A film (phase retardation film/adhesive B/partition film) to which the adhesive B adhered was applied to one surface of a retardation film containing a norbornene resin having a thickness of 20 μm.

(Example 1) (1) Fabrication of substrate film

Will comprise random copolymerization of propylene/ethylene with about 5% by weight of ethylene units Sumitomo Noblen FLX80E4, a separate polymer containing propylene, is placed on both sides of the resin layer of Sumitomo Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Sumitomo Noblen W151, melting point Tm=138°C. A base film having a three-layer structure of a resin layer having a melting point of Tm = 163 ° C was produced by co-extrusion molding using a multi-layer extrusion molding machine. The total thickness of the obtained base film was 90 μm, and the thickness ratio of each layer (FLX80E4/W151/FLX80E4) was 3/4/3.

(2) Formation of undercoat layer

Polyvinyl alcohol powder ("Z-200" manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average polymerization degree 1100, average saponification degree: 99.5 mol%) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 3 wt%. . The obtained polyvinyl alcohol aqueous solution was subjected to corona treatment on one surface of the base material film cut into 25 cm × 35 cm, and coated on a treated surface thereof by a table bar coater, and dried at 80 ° C for 10 minutes. An undercoat layer having a thickness of 0.2 μm was formed.

(3) Step of forming a polyvinyl alcohol-based resin layer

Polyvinyl alcohol powder ("PVA124" manufactured by Kuraray Co., Ltd., average polymerization degree 2400, average saponification degree: 98.0 to 99.0 mol%) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 8 wt%. The obtained aqueous solution was applied to the undercoat layer by a table bar coater and dried at 80 ° C for 5 minutes to prepare a "base film / undercoat layer / polyvinyl alcohol resin layer". A laminated film of layer structure. The thickness of the polyvinyl alcohol-based resin layer at this time was 11 μm.

(4) Polarization film processing step (extension step)

The above laminated film is cut off to obtain a product having a width of 18 cm and a length of 30 cm. Layer film. The laminated film was stretched 5.8 times in the width direction at one end of the free end by a tenter stretching device at an extension temperature of 160 °C. The thickness of the polyvinyl alcohol-based resin layer at this time was 5.1 μm.

(dyeing step, cross-linking step)

Next, a film of 10 cm × 16 cm was cut out from the center portion of the laminated film which was stretched, and the polyvinyl alcohol-based resin layer was dyed and crosslinked by the following procedure. First, the cut laminated film was immersed in a dyeing solution containing 30 ° C of an aqueous solution of iodine and potassium iodide at 30 ° C for about 150 seconds to dye the polyvinyl alcohol-based resin layer, and then washed at 100 ° C in pure water. Take excess iodine solution. Next, it was immersed in a crosslinking solution containing a boric acid and potassium iodide solution at 76 ° C for 600 seconds. Thereafter, the film was washed in pure water at 10 ° C for 4 seconds, and finally dried at 80 ° C for 300 seconds, and the polyvinyl alcohol-based resin layer was polarized to obtain a "base film / undercoat layer containing 10 cm × 15 cm. A polarizing laminated film having a three-layer structure of a polarizing film. The thickness of the polarizing film (polyvinyl alcohol-based resin layer) at this time was 5.1 μm.

The contraction force in the direction orthogonal to the absorption axis and the contraction force in the absorption axis direction were measured only by the following measurement method for the polarizing film of the obtained polarizing laminated film. As a result, the contraction force in the direction in which the polarizing film was orthogonal to the absorption axis was 0.28 N, and the contraction force in the direction of the absorption axis was 1.2 N.

(Method for measuring contraction force)

The obtained polarizing laminated film was cut into a width of 2 mm and a length of 50 mm by Super Cutter (manufactured by Takino Seiki Seisakusho Co., Ltd.) so that the direction in which the contraction force was measured became a long axis. The base film was peeled off from the obtained strip-shaped sheet (polarized laminated film) into a test piece having only a polarizing film.

The shrinkage force of the test piece was measured using a thermomechanical analyzer (SII, manufactured by Nanotechnology Co., Ltd., type TMA/6100). This measurement is carried out in a certain size mode (the distance between fixers is set to 10 mm). After the test piece is placed in a room at 20 ° C for a sufficient period of time, the temperature of the sample is set from 20 ° C to 80 ° C and the temperature is raised in 1 minute. After the temperature was raised, the indoor temperature of the sample was set to 80 °C. After allowing to stand for 4 hours after the temperature rise, the contraction force of the test piece in the longitudinal direction was measured in an environment of 80 °C. In this measurement, the static load was reset to 0 mN, and the jig was a probe made of SUS.

(5) Protective film bonding step

First, polyvinyl alcohol powder ("KL-318" manufactured by Kuraray Co., Ltd., average polymerization degree: 1800) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 3 wt%. Into the obtained polyvinyl alcohol aqueous solution, 1 part by weight of a crosslinking agent (Sumireze resin 650 manufactured by Chem Chem) was mixed with 2 parts by weight of the polyvinyl alcohol powder to prepare an adhesive solution.

Next, the above-mentioned adhesive solution was applied onto the polyvinyl alcohol-based resin layer of the obtained polarizing laminate film, and then a protective film containing triethyl fluorenyl cellulose (TAC) (manufactured by Konica Mninolta Opto Co., Ltd.) KC4UY") was bonded together to obtain a 5-layer base film-attached polarizing plate including "base film/undercoat layer/polarizing film/adhesive layer/protective film".

(6) Substrate film peeling step

The substrate film was peeled off from the obtained base film polarizing plate of 10 cm × 15 cm, and a polarizing plate α of four layers including "undercoat layer / polarizing film / adhesive layer / protective film" was produced.

(7) Adhesive layering step

Corona treatment was applied to the surface of the primer layer side of the obtained polarizing plate, and the adhesive layer A was bonded to the surface thereof to prepare a "separator film / adhesive A / undercoat layer / polarizing film / adhesive layer / protective film". A polarizing plate with an adhesive attached.

(8) Production of evaluation samples

The obtained polarizing plate with an adhesive was cut into a sample for evaluation at a shaft angle as shown in Table 1. In addition, the "axis angle of the polarizing film" in the first table is the angle α in the counterclockwise direction of the absorption axis 11A of the polarizing film 11 in the longitudinal direction C of the polarizing plate from the side of the protective film 10 (refer to FIG. 3). ). In addition, the "axis angle of the retardation film" is the angle β in the counterclockwise direction of the 遅 phase axis 12B of the retardation film 12 in the longitudinal direction C of the polarizing plate 1 from the protective film 10 side (see FIG. 3). .

<Comparative Example 1>

In the same manner as in Example 1, except that the adhesive C was used instead of the adhesive A, an adhesive-attached polarizing film including a "separator film/adhesive layer/undercoat layer/polarizing film/adhesive layer/protective film" was prepared. board. Further, a sample for evaluation was produced in the same manner as in Example 1.

<Example 2>

After the surface of the undercoat layer side of the polarizing plate α of Example 1 was subjected to corona treatment, the adhesive D was adhered to the surface. In addition, the retardation film side of the retardation film X to which the adhesive is applied is bonded to the absorption axis of the polarizing plate and the 遅 phase axis of the retardation film by 45°. Further, a corona treatment is applied to the surface opposite to the adhesive to which the adhesive retardation film X is attached. In this way, the preparation includes "separator film / adhesive A / retardation film / adhesive D / undercoat / polarizing film / adhesive layer / protective film", with phase A polarizing plate with an adhesive attached to the film.

Further, in the same manner as in Example 1, a sample for evaluation was prepared.

<Comparative Example 2>

The separator film / adhesive B / retardation film / adhesive D / bottom was produced in the same manner as in Example 2 except that the retardation film Y with the adhesive was used and the retardation film Y with the adhesive was used. An adhesive-attached polarizing plate having a retardation film formed of a coating layer/polarizing film/adhesive layer/protective film. Further, in the same manner as in Example 1, a visual sample for evaluation was prepared.

<Comparative Example 3> (1) Production of polarizing film

In this comparative example, a polarizing film was produced without using a base film. First, a polyvinyl alcohol resin film having an average polymerization degree of about 2400, a degree of saponification of 99.9 mol% or more and a thickness of 75 μm was stretched about 5 times in a dry axis, and after being immersed in pure water at 60 ° C for 1 minute while being kept under tension. It was immersed in a dyeing solution containing an aqueous solution of iodine and potassium iodide at 30 ° C for 60 seconds. Thereafter, the mixture was immersed in a 72 ° C crosslinking solution containing an aqueous solution of boric acid and potassium iodide for 300 seconds. Then, it was washed with pure water of 10 ° C for 5 seconds, and then dried at 80 ° C for 3 minutes to obtain a polarizing film in which iodine was adsorbed and aligned in the polyvinyl alcohol resin film.

The thickness of the polarizing film at this time was 28 μm, and the contraction force was measured by the above-described method. As a result, the contraction force in the direction orthogonal to the extending direction was 2.10 N, and the contraction force in the extending direction was 3.70 N.

(2) Production of polarizing plate

After the obtained polarizing film was coated with the same adhesive solution prepared in the protective film bonding step of Example 1, it was mixed with triethylenesulfonyl cellulose. A protective film ("KC4UY" manufactured by Konical Minolota Opto Co., Ltd.) was bonded to each other to obtain a three-layer polarizing plate β containing a "polarizing film/adhesive layer/protective film".

(3) Lamination of retardation film

On the polarizing film side of the polarizing plate β, the norbornene-type retardation film having a thickness of 33 μm is inclined at 45° to the 遅 phase axis of the retardation film of the absorption axis of the polarizing film, and is used for bonding the protective film. A five-layer polarizing plate including a "retardation film/adhesive layer/polarizing film/adhesive layer/protective film" was produced by laminating the same adhesive. Further, the bonding surface of the retardation film was previously subjected to corona treatment before bonding.

(4) Formation of adhesive layer

Corona treatment was applied to the retardation film side of the obtained polarizing plate, and the adhesive B was adhered thereto to obtain "partition film / adhesive B / retardation film / adhesive layer / polarizing film / adhesive layer / protective film A polarizing plate with an adhesive attached to a retardation film.

(5) Production of evaluation samples

The obtained polarizing plate with an adhesive was cut in the same manner as in Example 1 at a shaft angle shown in Table 1, and a sample for evaluation was prepared.

[Evaluation of durability of polarizing plate]

The separator films of the evaluation samples prepared in Examples 1 and 2 and Comparative Examples 1 to 4 were peeled off, and the pressure-sensitive adhesive layer of each evaluation sample was applied to a glass plate having a thickness of 0.7 mm at a temperature of 50 ° C. The conditions of 0.5 MPa were treated in an autoclave for 20 minutes. After naturally cooling, each sample was placed in an oven maintained at a temperature of 85 ° C, and a heating test was maintained for 500 hours. Right here In the sample after the heating test, the amount of dimensional change from the initial size ("value after test" - [initial value]) was measured with NEXIVVMR-12072 (manufactured by Nikon Co., Ltd.). The results are shown in Table 2.

1‧‧‧Polar plate

10‧‧‧Protective film

11‧‧‧ polarizing film

11A‧‧‧Absorption axis

12‧‧‧ phase difference film

12B‧‧‧遅phase axis

C‧‧‧Long-term direction

‧‧‧‧ angle

‧‧‧‧ angle

Claims (17)

A polarizing plate comprising at least one polarizing film and a protective film, wherein the polarizing plate is characterized by at least one layer of a protective film of the polarizing film, and an adhesive layer is provided on an outermost surface opposite to the protective film, and The shrinkage force per 2 mm width of the polarizing film in the direction perpendicular to the absorption axis is maintained at a temperature of 80 ° C for 240 minutes and 1.0 N or less, and the storage elastic modulus of the pressure-sensitive adhesive layer at 23 ° C is 0.20 MPa or more. The polarizing plate according to claim 1, wherein at least one optical film is provided on the opposite side of the protective film of the polarizing film, and the polarizing film is the farthest from the polarizing film. The aforementioned adhesive layer is provided on the opposite side. The polarizing plate according to the first or second aspect of the invention, wherein the contraction force per 2 mm width in the absorption axis direction of the polarizing film is maintained at a temperature of 80 ° C for 240 minutes and is 2.5 N or less. The polarizing plate according to any one of claims 1 to 3, wherein the polarizing film has a thickness of 10 μm or less. The polarizing plate according to any one of claims 1 to 4, wherein the adhesive layer has a storage modulus at 80 ° C of 0.15 MPa or more. The polarizing plate according to any one of claims 1 to 5, wherein the optical film is a protective film or a retardation film. A liquid crystal display device is bonded to a polarizing plate according to any one of claims 1 to 6 via at least one side of the liquid crystal cell via the adhesive layer. A method for manufacturing a polarizing plate comprises the steps of: forming an undercoat layer by applying a primer solution on one side of a substrate film to form an undercoat layer; forming a polyvinyl alcohol-based resin layer in the step of: A polyvinyl alcohol-based resin layer is formed on the layer, and a laminated film provided in the order of the base film, the undercoat layer, and the polyvinyl alcohol-based resin layer is provided. The polarizing film forming step is a step of forming the polyvinyl alcohol. The polarizing film is applied to the resin layer to form a polarizing film, and the polarizing film is provided in the order of the base film, the undercoat layer and the polarizing film. The protective film bonding step is performed on the polarizing layer. a protective film is bonded to the surface of the film opposite to the substrate film; a substrate film peeling step is performed by peeling the base film from the polarizing laminated film; and an adhesive layering step is performed on the opposite side of the protective film The most surface area layer of the adhesive layer; and characterized in that the contraction force per 2 mm width of the polarizing film in the direction orthogonal to the absorption axis is maintained at a temperature of 80 ° C for 240 minutes and 1.0 N or less, and the aforementioned adhesive layer is at 23 ° C. Hidden elastic modulus 0.20MPa to on. The method for producing a polarizing plate according to the eighth aspect of the invention, wherein the substrate film peeling step and the adhesive layer stacking step include at least one sheet on the side surface on which the base film is peeled off. An optical film lamination step of an optical film. The method for producing a polarizing plate according to claim 9, wherein in the adhesive layering step, the adhesive layer is opposite to the polarizing film of the optical film farthest from the polarizing film. Floor. A method for manufacturing a polarizing plate comprises the steps of: forming an undercoat layer by applying a primer solution on one side of a substrate film to form an undercoat layer; forming a polyvinyl alcohol-based resin layer in the step of: A polyvinyl alcohol-based resin layer is formed on the layer, and a laminated film having the base film, the undercoat layer, and the polyvinyl alcohol-based resin layer is provided, and a polarizing film forming step is performed to: The polarizing film is applied to the resin layer to form a polarizing film, and a polarizing laminated film having the base film, the undercoat layer and the polarizing film described above is provided, and a protective film bonding step is performed on the polarizing laminated film. a protective film is bonded to the surface opposite to the substrate film; and the substrate film is peeled off: the base film is peeled off from the polarizing laminate film; An optical film laminating step with an adhesive layer: an optical film having an adhesive layer laminated on the outermost surface opposite to the protective film and having the adhesive layer side as the outermost surface; and having the following characteristics: The shrinkage force per 2 mm width of the polarizing film in the direction orthogonal to the absorption axis was maintained at a temperature of 80 ° C for 240 minutes and 1.0 N or less, and the storage modulus of the adhesive layer at 23 ° C was 0.20 MPa or more. The method for producing a polarizing plate according to claim 11, wherein the substrate film peeling step and the step of attaching the adhesive layer optical film layer are included on a side opposite to the base film. An optical film lamination step of laminating at least one other optical film. The method for producing a polarizing plate according to any one of the invention, wherein the polyvinyl chloride resin layer is the laminated film obtained in the polyvinyl alcohol resin film forming step. The thickness is below 20 μm. The method for producing a polarizing plate according to any one of the preceding claims, wherein the polarizing film forming step includes an extending step of extending the laminated film, and the polyvinyl alcohol resin A dyeing step in which the layer is dyed with a dichroic substance. The method for manufacturing a polarizing plate according to claim 14, wherein In the aforementioned stretching step, the stretching ratio is more than 5 times. The method for producing a polarizing plate according to any one of claims 8 to 15, wherein the adhesive layer has a storage modulus at 80 ° C of 0.15 MPa or more. The method for producing a polarizing plate according to any one of claims 8 to 16, wherein the optical film is a protective film or a retardation film.