TWI672531B - A polarizer - Google Patents

Abstract

The present invention provides a polarizing plate, which sequentially includes a first protective film, a first adhesive layer, a polarizing film, a second adhesive layer, and a second protective film. The storage elasticity of the first adhesive layer at 80 ° C. The rate is 0.1 MPa or more and less than 800 MPa, and the storage elastic modulus of the second adhesive layer at 80 ° C is 800 MPa or more and less than 10,000 MPa.

Description

Polarizer

The present invention relates to a polarizing plate in which a protective film is bonded to both sides of a polarizing film via an adhesive layer.

A polarizing plate that is widely used in an image display device typified by a liquid crystal display device or the like generally has a structure of a double-area layer protective film on a polarizing film. For example, as described in Japanese Patent Application Laid-Open No. 2003-139952 and Japanese Patent Application Laid-Open No. 2011-017820, an adhesive is usually used for bonding between a polarizing film and a protective film. Adhesives for protective film bonding include water-based adhesives and active energy ray-curable adhesives.

Generally, a polarizing plate is a polarizing plate that is manufactured into a long object (polarizing plate reel) by a roll-to-roll method, for example, is cut to a size suitable for the size of the drawing surface of an applicable image display device. The sheet-like body is assembled into an image display device by being attached to the image display element. Therefore, the processability of the polarizing plate when it is cut into a sheet-like body is pursued (even if it is subjected to stress such as during cutting, peeling between the polarizing film and the protective film is unlikely to occur).

Furthermore, for an image display device to which a polarizing plate is applied, When durability is sought in the environment in which it is installed, further durability is required for the polarizing plate system. In Japanese Patent Application Laid-Open No. 2003-139952, it is described that an adhesive with a storage elastic modulus at 90 ° C. of 0.5 to 5000 MPa is used as an adhesive for laminating a protective film to improve the heat resistance of a polarizing plate. Furthermore, in Japanese Patent Application Laid-Open No. 2011-017820, it is described that a hardened product is used at 80 ° C. in order to improve durability (also referred to as cold and thermal shock resistance) when subjected to an environment such as repeated high and low temperature conditions. Adhesive showing a storage elastic modulus of 600 MPa or more. However, these conventional polarizers still have room for improvement in terms of both processability and resistance to cold and hot shock.

Therefore, an object of the present invention is to provide a polarizing plate which is a polarizing plate which has good processability at the time of cutting and the like and is excellent in cold and heat shock resistance.

This invention provides the following polarizing plates.

[1] A polarizing plate comprising a first protective film, a first adhesive layer, a polarizing film, a second adhesive layer, and a second protective film in order; the storage elastic modulus of the first adhesive layer at 80 ° C. It is 0.1 MPa or more and less than 800 MPa. The storage elastic modulus of the second adhesive layer at 80 ° C. is 800 MPa or more and less than 10,000 MPa.

[2] The polarizing plate according to the item [1], wherein the storage elastic modulus of the second adhesive layer at 80 ° C. is 1,000 MPa or more.

[3] The polarizing plate according to [1] or [2], wherein at least one of the first adhesive layer and the second adhesive layer is a cured product layer of an active energy ray-curable adhesive. .

[4] The polarizing plate as described in [3], wherein the aforementioned activity The energy ray-curable adhesive contains a radical polymerizable compound.

[5] The polarizing plate according to any one of [1] to [4], wherein the first protective film and the second protective film are selected from a polyester resin and a polycarbonate resin , A resin in the group consisting of a polyolefin resin, a (meth) acrylic resin, and a cellulose ester resin.

[6] The polarizing plate according to [5], wherein the first protective film is made of (meth) acrylic resin, and the second protective film is made of polyolefin resin or cellulose ester resin. Make up.

[7] The polarizing plate according to any one of [1] to [6], wherein at least one of the first protective film and the second protective film is a retardation film.

According to the present invention, it is possible to provide a polarizing plate which is excellent in workability at the time of cutting and the like and is excellent in cold and heat shock resistance.

10‧‧‧The first protective film

15‧‧‧The first adhesive layer

20‧‧‧Second protective film

25‧‧‧The second adhesive layer

30‧‧‧ polarizing film

FIG. 1 is a schematic cross-sectional view showing an example of a layer structure of a polarizing plate of the present invention.

Hereinafter, the polarizing plate of the present invention will be described in detail.

(1) Structure of polarizing plate

As shown in FIG. 1, the polarizing plate of the present invention is configured by sequentially including a first protective film 10, a first adhesive layer 15, a polarizing film 30, a second adhesive layer 25, and a second protective film 20. That is, the first protective film 10 is laminated on one side of the polarizing film 30 via the first adhesive layer 15, and the second protective film 20 is The second adhesive layer 25 is laminated on the other surface of the polarizing film 30. The storage elastic modulus of the first adhesive layer 15 at 80 ° C is 0.1 MPa or more and less than 800 MPa, and the storage elastic modulus of the second adhesive layer 25 at 80 ° C is 800 MPa or more and less than 10000 MPa. The polarizing plate of the present invention having such a structure exhibits good processability (difficult to peel off the film on the end face of the polarizing plate when processing such as cutting or end surface grinding is applied) and good cold and hot shock resistance.

The polarizing plate of the present invention is not limited to the example shown in FIG. 1 and may contain layers other than the above. If specific examples of other layers are given, for example: an adhesive layer laminated on the outside of the first protective film 10 and / or the second protective film 20; a separation film laminated on the outside of the adhesive layer (also referred to as "peeling Film "); a protective film (also referred to as a" surface protective film ") laminated on the outside of the first protective film 10 and / or the second protective film 20; laminated on the first protective film via an adhesive layer or an adhesive layer 10 and / or an optical functional film on the outer surface of the second protective film 20.

The polarizing plate of the present invention may be an elongated object of a polarizing plate having the above-mentioned layer structure or a winding roll thereof. In this case, the term "workability" refers to the workability when a polarizing plate sheet is cut out from an elongated object or a winding reel; the so-called cold and heat shock resistance refers to an elongated object or a winding reel, or from the length. Cold or hot stamping resistance of the polarizer sheet-like body cut by the shaped object or the winding roller. As mentioned above, the term "hot and cold shock resistance" refers to durability when placed under repeated high-temperature and low-temperature conditions. More specifically, it refers to resistance to cracks and cracks in a polarizing film under the environment. .

Further, the polarizing plate of the present invention may be a sheet-like body of a polarizing plate having the above-mentioned layer structure. In this case, the workability refers to a self-polarizing plate Sheeting Processability when cutting out smaller-sized sheeting, or when grinding the end surface of a polarizing plate sheet; the so-called cold and heat shock resistance refers to a polarizing plate or a polarizing plate The body is then cut to smaller and smaller polarizing plate pieces, which are resistant to cold and hot shock.

(2) Polarizing film

The polarizing film 30 is a film having a function of selectively penetrating linearly polarized light from a certain direction of natural light. Examples include: an iodine-based polarizing film that adsorbs / orientates iodine to a polyvinyl alcohol-based resin film, a dye-based polarizing film that adsorbs / orients dichroic dye to a polyvinyl alcohol-based resin film, and coating a lyotropic liquid crystal ( lyotropic liquid crystal), a dichroic dye in a state, and a coating type polarizing film that is oriented / immobilized. These polarizing films are known as absorption-type polarizing films because they selectively penetrate linearly polarized light from one direction of natural light and absorb linearly polarized light from the other direction. The polarizing film 30 is not limited to an absorptive polarizing film, and is a reflective polarizing film that selectively penetrates linearly polarized light from one direction of natural light and reflects linearly polarized light from the other direction, or straightens the other direction. Any scattering type polarizing film for polarized light scattering is not a problem, but in terms of excellent visibility, an absorption type polarizing film is preferred. Among them, an iodine-based polarizing film excellent in polarization and transmittance is more preferable.

The polyvinyl alcohol resin can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate-based resin include copolymers of vinyl acetate homopolymers and copolymers of other monomers copolymerizable with vinyl acetate. Examples of other monomers that can be copolymerized with vinyl acetate include: unsaturated carboxylic acids, olefins, Vinyl ethers, unsaturated sulfonic acids, (meth) acrylamidoamines having ammonium groups, and the like.

The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, and preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, aldehyde-modified polyvinyl formaldehyde or polyvinyl acetal may be used. The average degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, and preferably about 1500 to 5,000. The average degree of polymerization of the polyvinyl alcohol resin can be obtained in accordance with JIS K 6726.

As the film made of such a polyvinyl alcohol-based resin, an original sheet film that can be used as the polarizing film 30 can be used. The method of forming a polyvinyl alcohol-type resin into a film is not specifically limited, A well-known method can be employ | adopted. The thickness of the polyvinyl alcohol-based original sheet film is, for example, 150 μm or less, and preferably 100 μm or less (for example, 50 μm or less).

The polarizing film 30 can be manufactured by a method including the following steps: a step of uniaxially extending the polyvinyl alcohol-based resin; a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye and adsorbing the dichroic dye; A step of treating a polyvinyl alcohol-based resin film to which a dichroic dye is adsorbed (a cross-linking treatment) with a boric acid aqueous solution; and a step of washing with a boric acid aqueous solution after the treatment.

The uniaxial extension of the polyvinyl alcohol-based resin film may be performed before the dyeing of the dichroic pigment, simultaneously with the dyeing, or after the dyeing. When performing a uniaxial extension after dyeing, this uniaxial extension can be performed before or during a boric acid treatment. Moreover, one-axis extension may be performed in these plural stages.

When one axis is extended, it can be extended to one axis between rollers with different rotation speeds, or it can be extended to one axis by using hot rollers. Moreover, the uniaxial stretching may be dry stretching in the air, or wet stretching in which the polyvinyl alcohol-based resin film is stretched in a swollen state using a solvent or water. The stretching ratio is usually about 3 to 8 times.

A method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye is, for example, a method of immersing the film in an aqueous solution containing a dichroic dye. As a dichroic pigment, iodine and a dichroic organic dye can be used. The polyvinyl alcohol-based resin film is preferably subjected to a treatment of immersion in water before the dyeing treatment.

The dyeing treatment with iodine is generally a method of impregnating a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide. The content of iodine in this aqueous solution may be about 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide may be about 0.5 to 20 parts by weight per 100 parts by weight of water. Moreover, the temperature of this aqueous solution may be about 20 to 40 ° C. On the other hand, the dyeing treatment with a dichroic organic dye is generally a method of impregnating a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic organic dye. The aqueous solution containing a dichroic organic dye may contain an inorganic salt such as sodium sulfate as a dyeing auxiliary agent. The content of the dichroic organic dye in this aqueous solution may be about 1 × 10 ^-4 to 10 parts by weight per 100 parts by weight of water. The temperature of this aqueous solution can be about 20 to 80 ° C.

The boric acid treatment after dyeing with a dichroic pigment is generally a method of immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. When using iodine as a dichroic pigment, this contains boric acid The aqueous solution preferably contains potassium iodide. The amount of boric acid in the boric acid-containing aqueous solution may be about 2 to 15 parts by weight per 100 parts by weight of water. The amount of potassium iodide in this aqueous solution may be about 0.1 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution may be 50 ° C or higher, for example, 50 to 85 ° C.

The polyvinyl alcohol-based resin film after boric acid treatment is usually water-washed. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol-based resin film in water. The temperature of the water in the water washing treatment is usually about 5 to 40 ° C. The polarizing film 30 can be obtained by performing a drying process after washing with water. Drying can be performed using a hot air dryer or a far-infrared heater. A polarizing plate can be obtained by bonding a protective film on both sides of the polarizing film 30 with an adhesive.

Moreover, as another example of the manufacturing method of the polarizing film 30, the method described in Unexamined-Japanese-Patent No. 2000-338329, and Unexamined-Japanese Patent Unexamined-Japanese-Patent No. 2012-159778 is mentioned, for example. In this method, a solution containing a polyvinyl alcohol-based resin is applied to the surface of a base film to provide a resin layer, and then a laminated film including the base film and the resin layer is extended, followed by dyeing treatment, crosslinking treatment, and the like. A polarizing element layer (polarizing film layer) is formed from a resin layer. The polarizing laminated film including the base film and the polarizing element layer can be peeled off and removed after the protective film is pasted on the polarizing element layer, and further bonded on the level of the polarizing element exposed by the peeling of the base film. The other protective film becomes the polarizer.

The thickness of the polarizing film 30 may be 40 μm or less, and preferably 30 μm or less (for example, 20 μm or less). In addition, according to Japanese Patent Application Laid-Open No. 2000-338329 or Japanese Patent Application Laid-Open No. 2012-159778 The method can more easily manufacture the thin film polarizing film 30, and the thickness of the polarizing film 30 can be set to, for example, 20 μm or less, and further set to 10 μm or less. The thickness of the polarizing film 30 is usually 2 μm or more. Reducing the thickness of the polarizing film 30 is advantageous for reducing the thickness of the polarizing plate and even the image display device.

(3) Protective film

The first protective film 10 and the second protective film 20 may each include a translucent (preferably optically transparent) thermoplastic resin, such as, for example, a chain polyolefin resin (polypropylene resin, etc.). 、 Polyolefin resins such as cyclic polyolefin resins (such as norzene resins); such as cellulose ester resins of triethyl cellulose and diethyl cellulose; such as polyethylene terephthalate Polyester resins of esters, polyethylene naphthalate, polybutylene terephthalate; polycarbonate resins; (meth) acrylic resins; or resin films of such mixtures, copolymers, etc. . In addition, "(meth) acrylic acid" means methacrylic acid and / or acrylic acid, and when it is called "(meth) acrylic acid ester" etc., "(meth)" also has the same meaning. Among them, the first protective film 10 and the second protective film 20 are each a group selected from the group consisting of a polyester resin, a polycarbonate resin, a polyolefin resin, a (meth) acrylic resin, and a fiber ester resin. The resin composition is preferred.

Each of the first protective film 10 and the second protective film 20 may be an unstretched film or a film stretched through one axis or two axes. The two-axis extension may be a simultaneous two-axis extension that simultaneously extends in two extension directions, or a successive two-axis extension that extends in the other direction after extending in the set direction. The first protective film 10 and / or the second protective film 20 are also It may be a protective film having an optical function such as a retardation film. A retardation film is an optically functional film used for the purpose of compensating a retardation caused by a liquid crystal cell of an image display element. For example, a film including the thermoplastic resin (e.g., uniaxial or biaxial stretching), or a liquid crystal layer formed on the film can be used as a retardation film having an arbitrary retardation value.

Examples of the chain polyolefin resin include copolymers of two or more kinds of chain olefins other than homopolymers of chain olefins such as polyethylene resins and polypropylene resins.

Cyclic polyolefin resins are resins containing cyclic olefins as representative examples of norzene, tetracyclododecene (alias: dimethano octahydronaphthalene), or derivatives thereof. Collectively. Specific examples of cyclic polyolefin resins are: ring-opened (co) polymers of cyclic olefins and their hydrides, addition polymers of cyclic olefins, and cyclic olefins such as ethylene and propylene. Copolymers of linear olefins or aromatic compounds having vinyl groups, and modified (co) polymers and the like modified with unsaturated carboxylic acids or derivatives thereof. Among them, a norbornene-based resin using a norbornene-based monomer such as norcene or a polycyclic norcene-based monomer as a cyclic olefin is more suitable.

The cellulose ester resin may be a resin in which at least a part of hydroxyl groups in cellulose is esterified with acetic acid, or a mixed ester in which a part is esterified with acetic acid and a part is esterified with other acids. The cellulose ester resin is preferably an ethyl cellulose resin. Specific examples of the ethyl cellulose-based resin include triethyl cellulose, diethyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, and the like.

Polyester-based resins are resins other than the above-mentioned cellulose ester-based resins having an ester bond, and are generally those containing a polycondensate of a polycarboxylic acid or a derivative thereof and a polyhydric alcohol. Specific examples of the polyester-based resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polytrimethylene terephthalate. Diesters, polynaphthalate, polycyclohexane dimethyl terephthalate, cyclohexane dimethyl polynaphthalate. Among them, polyethylene terephthalate is suitable from the viewpoints of mechanical properties, solvent resistance, scratch resistance, cost, and the like. Polyethylene terephthalate means a resin composed of more than 80 mol% of repeating units composed of ethylene terephthalate, and may also contain structural units derived from other copolymerization components.

Other copolymerization components include a dicarboxylic acid component and a diol component. Examples of the dicarboxylic acid component include isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, and adipic acid , Sebacic acid, sodium 5-sulfoisophthalate, 1,4-dicarboxycyclohexane, and the like. Examples of the diol component include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Methylene glycol and the like. A dicarboxylic acid component and a diol component may be used in combination of 2 or more types each as needed. The dicarboxylic acid component and the diol component may be used in combination with a hydroxycarboxylic acid such as p-hydroxybenzoic acid or p-β-hydroxyethoxybenzoic acid. It is also possible to use a small amount of a dicarboxylic acid component and / or a diol component having a amine bond, a urethane bond, an ether bond, or a carbonate bond as other copolymerization components.

Polycarbonate resin is made of carbonic acid and glycol or bisphenol. Formed polyester. Among them, from the viewpoints of heat resistance, weather resistance, and acid resistance, it is preferable to use the aromatic polycarbonate having a diphenylalkane in the molecular chain. Polycarbonate can be exemplified by: 2,2-bis (4-hydroxyphenyl) propane (alias bisphenol A), 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4 -Hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) isobutane, 1,1-bis (4-hydroxyphenyl) ethane bisphenol-derived polycarbonate.

The (meth) acrylic resin may be a polymer containing methacrylate as a main monomer (containing 50% by weight or more), and a copolymer in which the polymer is copolymerized with a small amount of other copolymerization components is preferred. The (meth) acrylic resin is preferably a copolymer of methyl methacrylate and methyl acrylate, and a third monofunctional monomer may be further copolymerized.

Examples of the third monofunctional single system include, for example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, and methacrylic acid 2- Methacrylic esters other than ethylhexyl ester, 2-hydroxyethyl methacrylate and methyl methacrylate; such as ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, Acrylic esters of 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate; such as methyl 2- (hydroxymethyl) acrylate, methyl 2- (1-hydroxyethyl) acrylate, 2- (hydroxymethyl ) Hydroxyalkyl acrylates of ethyl acrylate, 2- (hydroxymethyl) butyl acrylate; such as methacrylic acid, unsaturated acids of acrylic acid; such as chlorostyrene, brominated styrene halogenated styrenes; such as ethylene Substituted styrenes such as methyl toluene and α-methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated anhydrides such as maleic anhydride and citraconic anhydride; such as phenylmaleic acid Amine, Cyclohexyl Malaya Unsaturated sulfonium imines and the like. The third monofunctional monomer may be used alone or in combination of two or more.

A polyfunctional monomer may be further copolymerized with a (meth) acrylic resin. Examples of the polyfunctional monomer include, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di ( The two terminal hydroxyl groups of ethylene glycol of meth) acrylate, nonaethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, or their oligomers are obtained through (meth) acrylic acid. Esterified; those whose hydroxy groups at both ends of propylene glycol or oligomers are esterified with (meth) acrylic acid; such as neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, butane Diols of glycol di (meth) acrylates whose hydroxyl groups are esterified with (meth) acrylic acid; bisphenol A, alkylene oxide adducts of bisphenol A, or two of these halogen substitutes Those whose terminal hydroxyl groups are esterified with (meth) acrylic acid; those such as trimethylolpropane and neopentyl alcohol are esterified with (meth) acrylic acid, and those terminal hydroxyl groups are ring-opened to add glycidyl groups (Meth) acrylate epoxy groups; diacids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, halogenated substitutes, and alkylene oxides, etc. Ring-opening ring-opening addition of epoxy group are glycidyl (meth) acrylates of glycidyl, and the like; (meth) acrylic acid aryl esters; divinylbenzene such as an aromatic divinyl compound. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

The (meth) acrylic resin may be one which further undergoes a reaction between functional groups of the copolymer and is modified. Examples of this reaction system include: methyl ester group of methyl acrylate and 2- (hydroxymethyl) acrylic acid Demethylation condensation reaction in the polymer chain of the hydroxyl group of methyl ester, dehydration condensation reaction in the polymer chain of the carboxyl group of acrylic acid and the hydroxyl group of methyl 2- (hydroxymethyl) acrylate, and the like.

The glass transition temperature of the (meth) acrylic resin is preferably 80 to 160 ° C. The glass transition temperature can be adjusted by adjusting the polymerization ratio of the methacrylate monomer and the acrylate monomer, the carbon chain length of each ester group, the type of the functional group and the polyfunctional monomer. Regulated relative to the polymerization ratio of the entire monomer.

In addition, the introduction of a ring structure into the main chain of the polymer can also be effectively used as a means for increasing the glass transition temperature of the (meth) acrylic resin. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic fluorene imine structure, and a lactone structure. Specific examples include cyclic acid anhydride structures such as glutaric anhydride structure and succinic anhydride structure, cyclic fluorene imine structures such as glutarimide structure and succinimide structure, and butyrolactone and valerolactone. Alicyclic structure. The larger the content of the ring structure in the main chain, the more the glass transition temperature of the (meth) acrylic resin can be increased. The cyclic acid anhydride structure and the cyclic fluorene imine structure can be introduced by a method of introducing and copolymerizing a monomer having a cyclic structure such as maleic anhydride and maleimide, and by A method of introducing a cyclic acid anhydride structure by dehydration / demethanol condensation reaction after polymerization, a method of introducing an amine compound into a cyclic amidine structure, and the like. A resin (polymer) having a lactone ring structure can be prepared by polymerizing a polymer having a hydroxyl group and an ester group in a polymer chain, and then heating the hydroxyl group and the ester group in the obtained polymer as needed to obtain It is obtained by cyclization and condensation in the presence of a catalyst of an organophosphorus compound to form a lactone ring structure.

The (meth) acrylic resin may contain additives if necessary. Examples of the additives include lubricants, anti-caking agents, heat stabilizers, antioxidants, antistatic agents, light resistance agents, impact resistance improvers, and surfactants.

The (meth) acrylic resin may also contain acrylic rubber particles of an impact modifier from the viewpoints of film-forming properties and impact resistance of the film. The acrylic rubber particles are particles containing an elastic polymer mainly composed of an acrylic ester as an essential component, and examples thereof include a single-layer structure substantially containing only the elastic polymer, and multiple layers including the elastic polymer as one layer. Constructor. Examples of the elastic polymer include a crosslinked elastic polymer in which an alkyl acrylate is used as a main component and other vinyl-based monomers and crosslinkable monomers copolymerizable with the main component are copolymerized. Examples of the alkyl acrylate which is a main component of the elastic polymer include those having an alkyl group having a carbon number of about 1 to 8 such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. It is preferable to use an alkyl acrylate having an alkyl group having 4 or more carbon atoms. Examples of other vinyl-based monomers that can be copolymerized with the alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule, and more specifically, methyl such as methyl methacrylate Acrylates, aromatic vinyl compounds such as styrene, vinyl cyanide compounds such as acrylonitrile, and the like. Examples of the crosslinkable monomer include crosslinkable compounds having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, examples thereof include ethylene glycol di (meth) acrylate The (meth) acrylates of polyhydric alcohols of butanediol di (meth) acrylate, such as alkenyl (meth) acrylate of allyl (meth) acrylate, divinylbenzene, and the like.

A protective film may include a laminate of a film containing a (meth) acrylic resin containing no rubber particles and a film containing a (meth) acrylic resin containing rubber particles. Further, a (meth) acrylic resin layer may be formed on one or both sides of a phase difference expression layer containing a resin different from the (meth) acrylic resin, and a person expressing the phase difference may be a protective film.

The first protective film 10 and / or the second protective film 20 may contain an ultraviolet absorber. When a polarizing plate is applied to an image display device such as a liquid crystal display device, a protective film containing an ultraviolet absorber is arranged on the visible side of an image display element (for example, a liquid crystal cell), thereby suppressing the image display element from ultraviolet rays. While degraded. Examples of the ultraviolet absorber include a salicylate-based compound, a benzophenone-based compound, a benzotriazole-based compound, a cyanoacrylate-based compound, and a nickel salt-based compound.

The first protective film 10 and / or the second protective film 20 may be films made of the same resin or films made of different resins. An example of a combination of the first protective film 10 and the second protective film 20 is a first protective film 10 which is bonded via a first adhesive layer 15 having a small storage elastic modulus at 80 ° C. and which is made of a (meth) acrylic resin. The second protective film 20 bonded to the second adhesive layer 25 having a large storage elasticity is a combination of a polyolefin resin or a cellulose ester resin. In this way, when comparing the first protective film 10 and the second protective film 20, a protective film having low mechanical properties (breaking stress) is laminated on the polarizing film 30 via the first adhesive layer 15 having low storage elasticity. With this, the processability can be further improved. In addition, the first protective film 10 and the second protective film 20 may be the same or different in thickness, presence or absence of additives, types, retardation characteristics, and the like.

The first protective film 10 and / or the second protective film 20 may have, for example, a hard coat layer, an anti-glare layer, an anti-reflection layer, a light diffusion layer, and antistatic on the outer surface (the surface opposite to the polarizing film 30). Layer, antifouling layer, surface treatment layer (coating layer) of conductive layer.

The thickness of the first protective film 10 and / or the second protective film 20 is usually 5 to 200 μm, preferably 10 to 120 μm, and more preferably 10 to 85 μm. Reducing the thickness of the first protective film 10 and / or the second protective film 20 is advantageous for reducing the thickness of the polarizing plate and the image display device. The thinner the protective film, the easier it is to reduce the cold and hot shock resistance. However, according to the present invention, even if the thicknesses of the first protective film 10 and the second protective film 20 are thin, the cold and hot shock resistance of the polarizing plate can be effectively improved. .

(4) Adhesive layer

The storage elastic modulus of the first adhesive layer 15 at 80 ° C is 0.1 MPa or more and less than 800 MPa, and the storage elastic modulus of the second adhesive layer 25 at 80 ° C is 800 MPa or more and less than 10,000 MPa. The storage elastic modulus of the first adhesive layer 15 and the second adhesive layer 25 satisfies such a relationship, whereby the workability of the polarizing plate and the resistance to cold and hot impact can be highly balanced. The storage elastic modulus of the adhesive layer can be measured by the method described in the paragraph of the examples described later.

Mainly from the viewpoint of processability, the storage elastic modulus of the first adhesive layer 15 at 80 ° C is preferably 600 MPa or less, more preferably 400 MPa or less, more preferably 200 MPa or less, and even more preferably 100 MPa or less. On the other hand, when the storage elastic modulus of the first adhesive layer 15 is too low, even when the storage elastic modulus of the second adhesive layer 25 is within a predetermined range, there is a deviation. The cold and hot shock resistance of the light plate may cause defects such as cracks and cracks in the polarizing film 30. Therefore, the storage elastic modulus of the first adhesive layer 15 at 80 ° C is preferably 0.5 MPa or more, more preferably 1 MPa or more, and even more preferably 5 MPa or more, and more preferably 10 MPa or more.

The storage elastic modulus of the second adhesive layer 25 at 80 ° C is preferably from 900 MPa or more, and more preferably from 1000 MPa or more, and from the standpoint of durability of the polarizing plate, especially from the viewpoint of cold and heat shock resistance. Above 2000 MPa is particularly preferred. On the other hand, if the storage elastic modulus of the second adhesive layer 25 is too high, even if the storage elastic modulus of the first adhesive layer 15 is within a predetermined range, the processability is reduced. Therefore, the storage elastic modulus of the second adhesive layer 25 at 80 ° C is preferably 8000 MPa or less, more preferably 6000 MPa or less, and even more preferably 5000 MPa or less.

From the viewpoint of considering both processability and cold and hot shock resistance, the difference between the storage elastic modulus of the second adhesive layer 25 at 80 ° C and the storage elastic modulus of the first adhesive layer 15 at 80 ° C is preferably 100 MPa or more. And more preferably 500 MPa or more, especially 900 MPa or more, and more preferably 1000 MPa or more, and more preferably 2000 MPa or more (for example, 2,500 MPa or more).

The adhesive for forming the first adhesive layer 15 and the second adhesive layer 25 is not particularly limited as long as it can obtain the above-mentioned predetermined storage elastic modulus. Examples of the adhesive include water-based adhesives that are heated by ultraviolet rays, visible light, and electron rays. , X-ray and other hardening adhesives that harden by irradiation with active energy rays. The curable adhesive system contains a curable (polymerizable) compound as a main component. A specific example of the water-based adhesive is a polymer Vinyl alcohol-based resins or urethane resins may be dissolved or dispersed in water, and they may contain, for example, polyaldehyde, melamine-based compounds, zirconia compounds, zinc compounds, glyoxal, and water-soluble epoxy resins. Sexual ingredients and cross-linking agents. When a curable adhesive is used (including the case where an aqueous adhesive contains a curable component and a crosslinking agent), the formed adhesive layer is a cured product layer of the curable adhesive.

Among the above, since the drying step of removing the solvent by heating can be omitted, a hardening adhesive is more preferable, and an active energy ray hardening adhesive is more preferable. The water-based adhesive and the thermosetting adhesive require a heating step, but may cause warping in the polarizing plate due to the heating. An aspect of the polarizing plate using the active energy ray-curable adhesive is a state in which at least one of the first adhesive layer 15 and the second adhesive layer 25 is a cured product layer of the active energy ray-curable adhesive. Similarly, it is preferable that both of the first adhesive layer 15 and the second adhesive layer 25 are hardened layers of the active energy ray-curable adhesive.

The storage elastic modulus of the 1st adhesive layer 15 and the 2nd adhesive layer 25 at 80 degreeC can be adjusted according to the following policy, for example. That is, when the adhesive layer is formed from a hardening adhesive, the storage elastic modulus of the adhesive layer depends on the structure of the hardening compound containing the hardening adhesive as a main component and the combination of the hardening compounds. For example, when the curable compound contains an alicyclic epoxy compound or an aromatic epoxy compound, it tends to increase the storage elastic modulus; when it contains an aliphatic epoxy compound, it tends to reduce the storage elastic modulus. The storage elasticity of the adhesive layer can also be adjusted by the degree of cross-linking of the hardening compound. When the amount of the hardenable compound is more than that, the storage elastic modulus of the adhesive layer tends to be high. The storage elasticity of the adhesive layer can be adjusted by adding components other than the main component to the curable adhesive. For example, when a polymer component (thermoplastic resin, etc.) is added, the storage elasticity of the adhesive layer becomes low. The tendency.

When the hardenable adhesive is classified according to its hardening form, a cationic polymerizable adhesive containing a cationic polymerizable compound as the hardenable compound, and a radical polymerization containing a radical polymerizable compound as the hardenable compound may be mentioned. Type adhesives, mixed hardening adhesives containing both cationically polymerizable compounds and radical polymerizable compounds. Specific examples of the cationically polymerizable compound include an epoxy compound having one or more epoxy groups in the molecule, an oxetane compound having one or more oxetane rings in the molecule, and an ethylene compound. Specific examples of the radical polymerizable compound include a (meth) acrylic compound and an ethylene compound having one or more (meth) acrylfluorenyl groups in the molecule. The curable adhesive may contain one or two or more kinds of cationically polymerizable compounds and / or one or two or more kinds of radically polymerizable compounds.

(4-1) Cationic polymerization type adhesive

The cationically polymerizable compound whose main component is a cationically polymerizable adhesive is a compound or oligomer that undergoes cation polymerization by irradiation and heating with active energy rays such as ultraviolet, visible light, electron rays, and X-rays. Examples of epoxy compounds and oxetane Compounds, vinyl compounds, etc. Among them, the cationically polymerizable compound is preferably an epoxy compound. The epoxy compound refers to a compound having one or more epoxy groups in a molecule, and a compound having two or more epoxy groups is preferable. The epoxy compound may be used alone or in combination of two or more. Examples of the epoxy compound system include an alicyclic epoxy compound, an aromatic epoxy compound, a hydrogenated epoxy compound, and an aliphatic epoxy compound. Among these, from the viewpoints of weather resistance, hardening speed, and adhesiveness, the epoxy compound preferably contains an alicyclic epoxy compound and an aliphatic epoxy compound, and more preferably contains an alicyclic epoxy compound.

An alicyclic epoxy compound is a compound having one or more epoxy groups bonded to an alicyclic ring in the molecule. The "epoxy group bonded to the alicyclic ring" means an oxygen atom -O- which bridges in the structure represented by the following formula (I). In the following formula (I), m is an integer of 2 to 5.

A compound obtained by removing one or a plurality of hydrogen atoms in (CH ₂ ) _m in the above formula (I) and bonded to another chemical structure can be an alicyclic epoxy compound. One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group.

Among them, an alicyclic epoxy compound having an epoxy-based cyclopentane structure [one of m = 3 in the above formula (I)] and an epoxy-cyclohexane structure [one of m = 4 in the above formula (I)], It is advantageous in terms of improving the storage elasticity of the adhesive layer, and it is also advantageous in terms of the adhesion between the polarizing film and the protective film. Profit. Specific examples of the alicyclic epoxy compound will be described below. Here, the names of the compounds are listed first, and the corresponding chemical formulas are shown. The same symbols are used for the compound names and the corresponding chemical formulas.

A: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, B: 3,4-epoxy-6-methylcyclohexylmethyl 3,4-cyclo Oxy-6-methylcyclohexane carboxylate, C: ethylene bis (3,4-epoxycyclohexane carboxylate), D: bis (3,4-epoxycyclohexylmethyl) Adipate, E: bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, F: diethylene glycol bis (3,4-epoxycyclohexylmethyl ether) ), G: ethylene glycol bis (3,4-epoxycyclohexyl methyl ether), H: 2,3,14,15-diepoxy-7,11,18,21-tetraoxapine [5.2.2.5.2.2] Icosane, I: 3- (3,4-epoxycyclohexyl) -8,9-epoxy-1,5-dioxaspiro [5.5] undecane , J: 4-vinylcyclohexene dioxide, K: limonene dioxide, L: bis (2,3-epoxycyclopentyl) ether, M: dicyclopentadiene dioxide.

Aromatic epoxy compound with aromatic in the molecule Ring and epoxy compounds. Specific examples thereof include bisphenol-type epoxy compounds such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S or oligomers thereof; phenol novolac epoxy Resins, novolac epoxy resins such as cresol novolac epoxy resin, hydroxybenzaldehyde novolac epoxy resin; glycidyl ethers of 2,2 ', 4,4'-tetrahydroxydiphenylmethane, 2, Polyfunctional epoxy compounds such as glycidyl ether of 2 ', 4,4'-tetrahydroxybenzophenone; polyfunctional epoxy resin such as epoxidized polyvinyl phenol.

The hydrogenated epoxy compound is a glycidyl ether of a polyhydric alcohol having an alicyclic ring, and the aromatic polyhydric alcohol can be selectively hydrogenated on the aromatic ring under the presence of a catalyst under pressure, and thereby The obtained hydrogenated polyhydroxy compound is subjected to glycidyl etherification. Specific examples of the aromatic polyol include bisphenol compounds such as bisphenol A, bisphenol F, and bisphenol S; novolac resins such as phenol novolac resin, cresol novolac resin, and hydroxybenzaldehyde novolac resin Resin; polyfunctional compounds such as tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, and polyvinylphenol. The epichlorohydrin of the alicyclic polyol obtained by the hydrogenation reaction of the aromatic ring starting from the aromatic polyol is reacted to form a glycidyl ether. Preferred among the hydrogenated epoxy compounds are glycidyl ethers of hydrogenated bisphenol A.

The aliphatic epoxy compound is a compound having at least one oxetane ring (a three-membered cyclic ether) bonded to an aliphatic carbon atom in the molecule. For example: monofunctional epoxy compounds such as butyl glycidyl ether, 2-ethylhexyl glycidyl ether; 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl Glycol diglycidyl ether, 1,4-cyclohexyl Difunctional epoxy compounds such as alkane dimethanol diglycidyl ether; trifunctional or higher functional epoxy compounds such as trimethylolpropane triglycidyl ether, neopentaerythritol tetraglycidyl ether; 4-vinylcyclohexane dioxide Epoxy compounds such as alkene, limonene dioxide and the like having one epoxy group directly bonded to an alicyclic ring and an oxetane ring bonded to an aliphatic carbon atom. Among them, from the viewpoint of the adhesiveness between the polarizing film and the protective film, it is a bifunctional epoxy compound (also referred to as a fat) having an oxetane ring bonded to an aliphatic carbon atom in the molecule. Group diepoxy compounds) are preferred. Such a suitable aliphatic diepoxide can be represented by the following formula (II), for example.

Y in the above formula (II) is an alkylene group having 2 to 9 carbon atoms, an alkylene group having 4 to 9 total carbon atoms between ether bonds, or a divalent hydrocarbon group having 6 to 18 carbon atoms having an alicyclic structure .

The aliphatic diepoxy compound represented by the formula (II) is specifically a diglycidyl ether of an alkanediol, a diglycidyl ether of an oligomeric alkylene glycol having a repeating number of about 4, or an alicyclic diol Diglycidyl ether.

Specific examples of glycols which can form the aliphatic diepoxy compound represented by the formula (II) are described below. Alkanes are: ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol Glycol, neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptane Diol, 3,5-heptanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol and the like. Oligomeric alkylene glycols include diethylene glycol, triethylene glycol, tetraethylene glycol, and dipropylene glycol. The alicyclic diols include: cyclohexanediol such as 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, Cyclohexanedimethanol, such as 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol.

An oxetane compound, which is one of the cationically polymerizable compounds, is a compound containing one or more oxetane rings (oxetane) in the molecule. Specific examples include: 3-ethyl 3-Hydroxymethyloxetane (also known as oxetanol), 2-ethylhexyloxetane, 1,4-bis [{(3-ethyloxetane Alk-3-yl) methoxy} methyl] benzene (also known as stubyl dioxetane), 3-ethyl-3 [{(3-ethyloxetane-3- Yl) methoxy} methyl] oxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3- (cyclohexyloxy) methyl-3-ethyl Oxetane. The oxetane compound may be used as a main component of the cationically polymerizable compound, or may be used in combination with an epoxy compound. By using an oxetane compound in combination, there is a case where the curing speed and adhesion can be improved.

Examples of the vinyl compound that can be a cationically polymerizable compound include aliphatic or alicyclic vinyl ether compounds. Specific examples include n-pentyl vinyl ether, iso-pentyl vinyl ether, n-hexyl vinyl ether, Vinyl ethers of alkyl or alkenyl alcohols having 5 to 20 carbon atoms, such as n-octyl vinyl ether, 2-ethylhexyl vinyl ether, n-dodecyl vinyl ether, stearyl vinyl ether, and oleyl vinyl ether; Hydroxy-containing vinyl ethers such as 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether; cyclohexyl vinyl ether, 2-methyl Vinyl ethers of monoalcohols with aliphatic or aromatic rings, such as cyclohexyl vinyl ether, cyclohexyl methyl vinyl ether, benzyl vinyl ether; glycerol monovinyl ether, 1,4-butanediol monovinyl ether, 1 4,4-butanediol divinyl ether, 1,6-hexanediol divinyl ether, neopentyl glycol divinyl ether, neopentyl tetraol divinyl ether, neopentyl tetraol divinyl ether, trimethylolpropane Divinyl ether, trimethylolpropane trivinyl ether, 1,4-dihydroxycyclohexane monovinyl ether, 1,4-dihydroxycyclohexane divinyl ether, 1,4-dihydroxymethyl cyclohexane Mono- to polyvinyl ethers of polyols such as monovinyl ether, 1,4-dihydroxymethylcyclohexane divinyl ether; diethylene glycol divinyl ether, triethylene glycol divinyl ether, diethylene glycol monobutyl ether Mono- to divinyl ethers of polyalkylene glycols such as vinyl monoethylene ether; other vinyl ethers such as glycidyl vinyl ether, glycol vinyl ether methacrylate, and the like. An ethylene compound can be used as a main component of a cationically polymerizable compound, and can also be used together with an epoxy compound, or an epoxy compound and oxetane. By using an ethylene compound in combination, the hardening speed and the viscosity of the adhesive may be reduced.

The cationically polymerizable adhesive system may further include a cationically polymerizable compound other than the above, such as a cyclic lactone compound, a cyclic acetal compound, a cyclic thioether compound, and a spiro orthoester compound.

From the viewpoint of the adhesiveness between the polarizing film and the protective film, when the entire amount of the curable compound contained in the cationically polymerizable adhesive (when the curable adhesive is mixed) is 100% by weight, The content of the cationic polymerizable compound (the content of all cationic polymerizable compounds contained in the cationic polymerizable adhesive, the total content of these when the polymer contains two or more cationic polymerizable compounds) is 50% by weight or more. Better, and more preferably 60% by weight or more, and more preferably 70% by weight or more. As described above, the cationically polymerizable adhesive may further contain a polymer component (such as a thermoplastic resin). Thereby, the storage elastic modulus of an adhesive layer can be reduced, and the adhesiveness between a polarizing film and a protective film can be improved.

The cation polymerization type adhesive may be active energy ray hardening or thermal hardening, but since the heating step can be omitted and warping of the polarizing plate caused by the heating can be prevented, active energy ray hardening is preferred. . When a cationic polymerizable adhesive containing a cationic polymerizable compound is applied with active energy ray hardening properties, it is preferred that a photocationic polymerization initiator is added to the adhesive. Photocationic polymerization initiators can be irradiated with active energy rays such as visible light, ultraviolet rays, X-rays, or electron rays to generate cationic species or Lewis acids to initiate the polymerization of cation-hardening compounds. Since the photocationic polymerization initiator performs a catalytic action with light, even if it is mixed with a photocationic curable compound, it has excellent storage stability and handling properties. Examples of compounds that generate cationic species or Lewis acids upon irradiation with active energy rays include, for example, onium salts of aromatic iodonium salts, aromatic sulfonium salts, aromatic diazonium salts, and iron-aromatic hydrocarbon complexes.

The aromatic iodonium salt is a compound having a diaryl iodonium cation. Typical examples of the cation include a diphenyl iodonium cation. The aromatic sulfonium salt is a compound having a triarylsulfonium cation. Typical examples of the cation include a triphenylsulfonium cation and 4,4'-bis (diphenylsulfonyl) diphenylsulfide cation. The aromatic diazonium salt is a compound having a diazonium cation. Typical examples of the cation include a benzenediazonium cation. And, iron- Aromatic complexes are typically cyclopentadiene iron (II) aromatic cation complex salts.

The cations shown above are paired with anions (negative ions) to constitute a photocationic polymerization initiator. Examples of the anionic photo-cationic polymerization initiator composition, may include: phosphorus-based special anion _{[(Rf) n PF 6-} n] -, hexafluorophosphate anion PF ₆ ^-, a hexafluoroantimonate anion ester SbF ₆ ^- , antimony-pentafluoro-hydroxy ester anion SbF ₅ (OH) ^-, hexafluoro arsenate anions AsF ₆ ^-, tetrafluoroborate anion BF ₄ ^-, tetrakis (pentafluorophenyl) borate anion B (C ₆ F ₅ ) ₄ ^- etc. From the viewpoint of the cationic polymerizable compound and available curable adhesive layer of the security point of view, in particular phosphorus-based anion _{[(Rf) n PF 6-} n] -, hexafluorophosphate PF ₆ anion ^- better.

The photocationic polymerization initiator may be used alone or in combination of two or more. Among them, aromatic sulfonium salts are suitable for use because they have ultraviolet absorbing properties even in a wavelength region around 300 nm, so they can obtain hardened materials that are excellent in hardenability and have good mechanical strength and adhesive strength.

The blending amount of the photocationic polymerization initiator is usually 0.5 to 10 parts by weight, and preferably 6 parts by weight or less based on 100 parts by weight of the cationically polymerizable compound. By blending a photocationic polymerization initiator in an amount of 0.5 parts by weight or more, the cationic polymerizable compound can be sufficiently hardened, and the obtained polarizer can be given high mechanical strength and adhesion strength. On the other hand, when the amount of the photocationic polymerization initiator becomes too large, there may be a case where the hygroscopicity of the cured product is increased due to an increase in the ionic substance in the cured product, and the durability of the polarizing plate may be reduced.

As described above, it is also possible to The agent contains a radically polymerizable compound in addition to the cationically polymerizable compound, and becomes a curable adhesive agent for mixing molding. By using the radical polymerizable compound in combination, the effect of improving the hardness and mechanical strength of the adhesive layer can be expected, and the viscosity, the curing speed, and the like of the curable adhesive can be adjusted more easily.

(4-2) Radical polymerization type adhesive

A radically polymerizable compound as a main component of a radically polymerizable adhesive refers to a compound that undergoes a radical polymerization reaction and is hardened by irradiation and heating with active energy rays such as ultraviolet rays, visible light, electron rays, and X-rays, or Specific examples of the oligomer include compounds having an ethylenically unsaturated bond. Examples of the compound having an ethylenically unsaturated bond include a (meth) acrylic compound having one or more (meth) acrylfluorenyl groups in the molecule, and examples thereof include styrene, styrenesulfonic acid, and vinyl acetate. Esters, vinyl propionate, vinyl compounds of N-vinyl-2-pyrrolidone, and the like. Among them, the radical polymerizable compound is preferably a (meth) acrylic compound.

Examples of the (meth) acrylic compound include compounds containing a (meth) acrylfluorenyl group, such as a (meth) acryl-based oligomer having at least two (meth) acrylfluorenyloxy groups in the molecule. It is obtained by reacting a (meth) acrylic acid ester monomer having at least one (meth) acrylfluorenyloxy group in the molecule, a (meth) acrylamide monomer, and a functional group-containing compound in two or more types. The (meth) acrylic acid-based oligomer is preferably a (meth) acrylic acid ester oligomer having at least two (meth) acryloxy groups in the molecule. The (meth) acrylic compound may be used alone or in combination of two or more.

Examples of the (meth) acrylate monomer include: A monofunctional (meth) acrylate monomer having one (meth) acryloxy group, a bifunctional (meth) acrylate monomer having two (meth) acryloxy groups in a molecule, and A polyfunctional (meth) acrylate monomer having three or more (meth) acryloxy groups in the molecule.

Examples of the monofunctional (meth) acrylate monomer are alkyl (meth) acrylates. The alkyl (meth) acrylate may be linear or branched as long as its alkyl group has 3 or more carbon atoms. Specific examples of alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, and butyl (meth) acrylate Esters, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like. Also, aralkyl (meth) acrylates such as benzyl (meth) acrylate; (meth) acrylates of terpene alcohols such as isobornyl (meth) acrylate; such as (meth) Tetrahydrofuran methyl acrylate (meth) acrylate with tetrahydrofuran methyl structure; such as cyclohexyl (meth) acrylate, cyclohexyl methyl methacrylate, dicyclopentyl acrylate, dicyclopentyl (meth) acrylate (Meth) acrylates having a cycloalkyl group at the alkyl portion of an alkenyl ester, 1,4-cyclohexanedimethanol monoacrylate; such as those of N, N-dimethylaminoethyl (meth) acrylate Aminoalkyl (meth) acrylate; such as 2-phenoxyethyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, ethyl carbitol (meth) acrylate, The phenoxy polyethylene glycol (meth) acrylate has a (meth) acrylate having an ether bond at the alkyl portion as a monofunctional (meth) acrylate monomer.

Moreover, it can also be used for monofunctional (meth) acrylate which has a hydroxyl group in an alkyl part, and monofunctional (meth) which has a carboxyl group in an alkyl part. Acrylate. Specific examples of the monofunctional (meth) acrylate having a hydroxyl group at the alkyl portion include 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, and (methyl) ) 4-hydroxybutyl acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, trimethylolpropane mono (meth) acrylate, neopentyltetraol mono (meth) acrylate. Specific examples of the monofunctional (meth) acrylate having a carboxyl group at the alkyl portion include 2-carboxyethyl (meth) acrylate and ω-carboxy-polycaprolactone (n ≒ 2) mono (methyl) ) Acrylate, 1- [2- (meth) acryloxyethyl] phthalate, 1- [2- (meth) acryloxyethyl] hexahydrophthalate, 1- [2- (meth) acryloxyethyl] succinate, 4- [2- (meth) acryloxyethyl] trimellitate, N- (meth) acryl Oxy-N ', N'-dicarboxymethyl-p-phenylenediamine.

The (meth) acrylamide monomer is preferably (meth) acrylamide having a substituent at the N-position. A typical example of the substituent at the N-position is an alkyl group. The nitrogen atoms of meth) acrylamide form a ring together. In addition to the carbon atom and the nitrogen atom of (meth) acrylamide, this ring may also have an oxygen atom as a ring member. Further, a substituent such as an alkyl group or a pendant oxygen group (= O) may be bonded to a carbon atom constituting the ring.

Specific examples of N-substituted (meth) acrylamide include: N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (methyl) Acrylamide, N-n-butyl (meth) acrylamide, N-third butyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-alkyl (methyl) Acrylamide; such as N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide. The N-substituent may be an alkyl group having a hydroxyl group, and examples thereof include N-hydroxymethyl (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N -(2-hydroxypropyl) (meth) acrylamide and the like. In addition, specific examples of the N-substituted (meth) acrylamide forming the 5-membered ring or the 6-membered ring described above are: N-acrylfluorenyl pyrrolidine, 3-propenylmethyl-2- Azolidone, 4-propenylmethylmorpholine, N-propenylmethylpiperidine, N-methacrylmethylpiperidine and the like.

Examples of bifunctional (meth) acrylate monomers include butanediol di (meth) acrylate, polyoxyalkylene glycol di (meth) acrylate, and halogen-substituted alkylene glycol di (meth) acrylate. Acrylate), di (meth) acrylates of aliphatic polyols, di (meth) acrylates of hydrogenated dicyclopentadiene or tricyclodecanedialkanol, di Alkanol or di Di (meth) acrylates of alkanedialkanols, alkylene oxide adducts of bisphenol A or bisphenol F, di (meth) acrylates of bisphenol A, or bisphenol F Epoxy esters, etc.

More specific examples of bifunctional (meth) acrylate monomers include ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di ( (Meth) acrylates, trimethylolpropane di (meth) acrylate, neopentaerythritol di (meth) acrylate, bis (trimethylolpropane) di (meth) acrylate, diethylene glycol Alcohol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol di (meth) Acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, polysiloxane di (meth) acrylate, hydroxytrimethylacetic acid neopentyl glycol two (Meth) acrylate, 2,2-bis [4- (meth) acryloxyethoxyethoxyphenyl] propane, 2,2-bis [4- (meth) acryloxy Ethoxyethoxycyclohexyl] propane, hydrogenated dicyclopentadiene di (meth) acrylate, tricyclic Dimethanol di (meth) acrylate, 1,3-bis Alkane-2,5-diyldi (meth) acrylate [aka: di Alkanol di (meth) acrylate], acetal compound of hydroxytrimethylacetaldehyde and trimethylolpropane [chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5 -Ethyl-5-hydroxymethyl-1,3-di Alkane] di (meth) acrylate, gins (hydroxyethyl) trimeric isocyanate di (meth) acrylate, 1,4-cyclohexanedimethanol diacrylate, and the like.

Trifunctional or higher polyfunctional (meth) acrylate monomers, representative examples are glycerol tri (meth) acrylate, alkoxylated glycerol tri (meth) acrylate, trimethylolpropane tris (methyl) Base) acrylate, bis (trimethylolpropane) tri (meth) acrylate, bis (trimethylolpropane) tetra (meth) acrylate, neopentaerythritol tri (meth) acrylate, new Pentaerythritol tetra (meth) acrylate, dinepentaerythritol tetra (meth) acrylate, dinepentaerythritol penta (meth) acrylate, dinepentaerythritol hexa (meth) acrylate, etc. Poly (meth) acrylates of trifunctional or higher aliphatic polyhydric alcohols, other examples include poly (meth) acrylates of trifunctional or higher halogen-substituted polyols, tertiary polyalkylene oxide adducts of glycerol ( (Meth) acrylate, alkylene oxide adduct of trimethylolpropane, tri (meth) acrylate, 1,1,1-ginseng [(meth) acryloxyethoxyethoxyethoxy] Propane, ginseng (hydroxyethyl) trimer isocyanate tri (meth) acrylate, and the like.

On the other hand, among (meth) acrylic acid oligomers, there are urethane (meth) acrylic acid oligomers, polyester (meth) acrylic acid oligomers, and epoxy (meth) acrylic acid. Oligomers, etc.

The urethane (meth) acrylic acid oligomer refers to a compound having a urethane bond (-NHCOO-) and at least two (meth) acrylfluorene groups in the molecule. Specifically, it may be a urethane reaction product of a hydroxyl-containing (meth) acrylic monomer having at least one (meth) acrylfluorenyl group and at least one hydroxyl group in a molecule, and a polyisocyanate. The urethane compound containing an isocyanate group at the end obtained by reacting a polyhydric alcohol with a polyisocyanate, and (A) having at least one (meth) acrylfluorenyl group and at least one hydroxyl group in the molecule, respectively. Group) urethane reaction products of acrylic monomers and the like.

The (meth) acrylic monomer containing a hydroxyl group used in the urethanization reaction may be, for example, a (meth) acrylate monomer containing a hydroxyl group, and specific examples thereof include (meth) acrylic acid 2-hydroxyethyl ester, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, bis (methyl) Glyceryl acrylate, trimethylolpropane di (meth) acrylate, neopentaerythritol tri (meth) acrylate, and dipentaerythritol penta (meth) acrylate. Specific examples other than the hydroxyl-containing (meth) acrylate monomer include N-hydroxyalkyl groups such as N-hydroxyethyl (meth) acrylamidonium, N-hydroxymethyl (meth) acrylamidoamine ( Methacrylamide monomer.

Polyisocyanates that can be reacted with urethanes of (meth) acrylate monomers containing hydroxyl groups include hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, and bicyclic Hexylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, diisocyanates obtained by hydrogenating aromatic isocyanates in these diisocyanates Cyanates (for example, hydrogenated toluene diisocyanate, hydrogenated xylene diisocyanate, etc.), di- or tri-isocyanates such as triphenylmethane triisocyanate, diphenylmethylbenzene triisocyanate, and the above-mentioned diisocyanate are polymerized. The obtained polyisocyanate and the like.

In addition, as a polyol used to form a urethane compound having an isocyanate group at its terminal by reaction with a polyisocyanate, a polyester polyol can be used in addition to the aromatic, aliphatic, or alicyclic polyol. Alcohols, polyether polyols, etc. Examples of the aliphatic and alicyclic polyols include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and neopentyl glycol. , Trimethylolethane, trimethylolpropane, bis (trimethylolpropane), neopentaerythritol, dipentaerythritol, dimethylol heptane, dimethylolpropionic acid, dihydroxyl Methyl butyric acid, glycerol, hydrogenated bisphenol A, etc.

The polyester polyol is obtained by the dehydration condensation reaction of the above-mentioned polyol and a polycarboxylic acid or its anhydride. Examples of polybasic carboxylic acids or their anhydrides are those with an "(anhydride)" if they can be acid anhydrides: succinic acid (anhydride), adipic acid, maleic acid (anhydride), and itaconic acid (anhydride ), Trimellitic acid (anhydride), pyromellitic acid (anhydride), phthalic acid (anhydride), isophthalic acid, terephthalic acid, hexahydrophthalic acid (anhydride) and the like.

Polyether polyols other than polyalkylene glycols may be polyoxyalkylene-modified polyols obtained by reacting the above-mentioned polyols or dihydroxybenzenes with alkylene oxides.

The polyester (meth) acrylic oligomer refers to a compound having an ester bond in the molecule and at least two (meth) acrylfluorenyl groups (typically (meth) acrylfluorenyloxy). Specifically, by using (meth) acrylic acid, A polycarboxylic acid or its anhydride and a polyhydric alcohol are obtained by performing a dehydration condensation reaction. Examples of polycarboxylic acids or their anhydrides that can be used in the dehydration condensation reaction. If "(anhydride)" is attached to those that can be acid anhydrides, there are: succinic acid (anhydride), adipic acid, and maleic acid (anhydride ), Iconic acid (anhydride), trimellitic acid (anhydride), pyromellitic acid (anhydride), hexahydrophthalic acid (anhydride), phthalic acid (anhydride), isophthalic acid, terephthalic acid Wait. Polyols that can be used in the dehydration condensation reaction include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and new Pentylene glycol, trimethylolethane, trimethylolpropane, bis (trimethylolpropane), neopentaerythritol, dinepentaerythritol, dimethylol heptane, dimethylolpropionic acid , Dimethylol butyric acid, glycerol, hydrogenated bisphenol A, etc.

The epoxy (meth) acrylic acid oligomer can be obtained, for example, by the addition reaction of polyglycidyl ether and (meth) acrylic acid, and has at least two (meth) acryloxy groups in the molecule. Examples of the polyglycidyl ether that can be used in the addition reaction include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, Bisphenol A diglycidyl ether and the like.

The radical polymerization type adhesive may be active energy ray-curable or heat-curable, but is more preferably active energy ray-curable. When imparting active energy ray-hardenability to a radically polymerizable adhesive containing a radically polymerizable compound, a photoradical polymerization initiator is preferably added to the adhesive. Photo-radical polymerization initiators are those who initiate polymerization of radical-curable compounds by irradiation of active energy rays such as visible light, ultraviolet rays, X-rays, or electron rays. Photoradical polymerization The initiator may be used alone or in combination of two or more.

Specific examples of the photoradical polymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethylketal, and 1- (4-isopropylphenyl) -2-hydroxy- 2-methylpropane-1-one, 2-methyl-1- [4- (methylthio) phenyl-2-morpholinylpropane-1-one, 2-hydroxy-2-methyl-1 -Acetophenone-based initiators such as phenylpropane-1-one; benzophenone-based initiators such as benzophenone, 4-chlorobenzophenone, 4,4'-diaminobenzophenone Agents; benzoin ether-based initiators such as benzoin propyl ether, benzoin ethyl ether; oxetanthone-based initiators such as 4-isopropyloxanthanone; others, oxygen Heteranthrone, fluorenone, camphorquinone, benzaldehyde, anthraquinone.

The blending amount of the photo radical polymerization initiator is usually 0.5 to 20 parts by weight, and preferably 1 to 6 parts by weight, based on 100 parts by weight of the radical polymerizable compound. By blending the photoradical polymerization initiator with 0.5 parts by weight or more, the radical polymerizable compound can be sufficiently hardened, and the obtained polarizer can be given high mechanical strength and adhesion strength. On the other hand, if the blending amount is too large, the durability of the polarizing plate may be reduced.

(4-3) Additives

The adhesive that forms the first adhesive layer 15 and / or the second adhesive layer 25 may contain other additives as necessary. Specific examples of the additives include ion trapping agents, antioxidants, chain transfer agents, polymerization accelerators (polyols, etc.), sensitizers, sensitizers, light stabilizers, tackifiers, thermoplastic resins, fillers, and flow agents. Regulators, plasticizers, defoamers, leveling agents, silane coupling agents, pigments, antistatic agents, ultraviolet absorbers, thermal polymerization initiators. When preparing a thermosetting adhesive, a thermal polymerization initiator may be used instead of the photopolymerization initiator. A photopolymerization initiator and a thermal polymerization initiator may be used in combination. Examples of the ion trapping agent include powdery inorganic compounds such as bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based and mixed systems thereof; and antioxidants include hindered phenol-based antioxidants.

(4-4) Glass transition temperature of adhesive

The glass transition temperature of the first adhesive layer 15 is preferably -15 ° C or more and less than 60 ° C, more preferably -10 ° C or more and less than 55 ° C, more preferably -5 ° C or more and less than 50 ° C and more It is more preferable to be above 0 ° C and less than 45 ° C. The glass transition temperature of the second adhesive layer 25 is preferably 60 ° C or higher, more preferably 70 ° C to 200 ° C, even more preferably 80 ° C to 180 ° C, and even more preferably 90 ° C to 160 ° C. When the glass transition temperature of the first adhesive layer 15 and the second adhesive layer 25 is within this range, it is beneficial to improve the processability and cold and hot shock resistance of the polarizing plate, and to improve the warpage resistance in a high temperature environment. Warpage resistance means that warping (warping) of the polarizing plate is not easily caused.

From the viewpoint of both good processability, cold and hot stamping resistance, and warpage resistance, the difference between the glass transition temperature of the second adhesive layer 25 and the glass transition temperature of the first adhesive layer 15 is 10 to 100 ° C is preferred, and more preferably 20 to 90 ° C (e.g. 50 to 80 ° C).

The Tg of the adhesive layer is measured by a differential scanning calorimeter (DSC), and can be measured by the following method, for example. For example, as long as it is an active energy ray-curable adhesive, two thermoplastic resin films are prepared, and the corona treatment is not performed so that the cured film thickness is 2 μm. The adhesive is coated on the surface of a thermoplastic resin film without corona treatment, and another thermoplastic resin film is superposed on the coated surface. Thus, one side of the thermoplastic resin film of the bonded product is irradiated with active energy rays to harden the adhesive. Next, the thermoplastic resin film carrying this cured product was peeled off, and 5 mg of this cured product was collected, put into an aluminum gland container, pressed and sealed, and a sample for measurement was produced. Next, the container into which the above-mentioned measurement sample is placed is set in a differential scanning calorimeter (DSC) [for example, SII. In the "EXSTAR-6000 DSC6220" sold by Nano Technology (Co., Ltd.), while sweeping with nitrogen, the temperature was lowered from 20 ° C to -60 ° C, and it was maintained at -60 ° C for one minute, and then at 10 ° C / minute. The temperature rising rate is raised from -60 ° C to 150 ° C, and when it reaches 150 ° C, the temperature is immediately reduced to 20 ° C. Then, from the DSC curve when the temperature was raised from -60 ° C to 150 ° C, the intermediate point transition temperature specified by JIS K 7121-1987 "Method for Measuring the Transition Temperature of Plastics" was determined, and this was set to be formed by the adhesive to be measured. The glass transition temperature of the adhesive layer.

(4-5) Application of adhesive, and adhesion of polarizing film and protective film

The first protective film 10 is laminated on one side of the polarizing film 30 via the first adhesive layer 15, and the second protective film 20 is laminated on the other side of the polarizing film 30 via the second adhesive layer 25, thereby obtaining the present invention. Polarizer. The first protective film 10 and the second protective film 20 (hereinafter, simply referred to as "protective film" hereinafter) can be laminated on one side in a stepwise manner, and can also be formed on both sides in one step. Laminate then.

Adhesion of the polarizing film 30 and the protective film can be specifically performed by: attaching the polarizing film 30 and / or the protective film The adhesive is coated on the bonding surface, and the two films are overlapped via the coating layer of the adhesive. For example, after the bonding is performed by pressing the bonding roller up and down, the adhesive layer is dried (for example, when it is an aqueous adhesive), and the active energy is irradiated. The adhesive layer is hardened by radiation (in the case of an active energy ray-curable adhesive) or heated to harden the adhesive layer (in the case of a thermosetting adhesive). Even when an active energy ray-curable adhesive is used, heat treatment may be performed while the active energy ray is irradiated, or heat treatment may be performed after the active energy ray is irradiated. Before forming the coating layer of the adhesive, one or both of the bonding surfaces of the polarizing film 30 and the protective film may be subjected to, for example, saponification treatment, corona discharge treatment, plasma treatment, flame treatment, and primer treatment. Easy to follow for anchor coating treatment.

For the formation of the coating layer of the adhesive, various coating methods such as a doctor blade, a wire rod, a die coater, a dot coater, and a gravure coater can be used. Further, a method may be adopted in which the adhesive is continuously supplied while the bonding surfaces of both the polarizing film 30 and the protective film are continuously provided inside, while the adhesive is spread therebetween.

From the viewpoint of coatability, the adhesives forming the first adhesive layer 15 and the second adhesive layer preferably have low viscosity. Specifically, the viscosity at 25 ° C is preferably 1,000 mPa · s or less, more preferably 500 mPa · s or less, and even more preferably 100 mPa · s or less. The adhesive may be a solventless type, but it may contain an organic solvent in order to adjust the viscosity to the coating method used.

In addition, in the step of forming the coating layer of the adhesive or the step of laminating the polarizing film 30 and the protective film, at least one of the protective film and the adhesive may be heated. Thereby, the polarizing film 30 and the protective film are improved The adhesion between the protective film and the adhesive layer is improved in particular. Specific examples of heating include heating of the protective film, heating of the adhesive, heating of the laminated body in which the polarizing film 30 and the protective film are laminated through the uncured or undried adhesive layer. The method of heating the protective film or the laminated body includes, for example, a method in which the elongated protective film and the laminated body are sequentially passed through a device that emits radiant heat such as an infrared heater, and the heated gas is blown to the elongated protection by a blower or the like Film, laminate, etc. The method of heating the adhesive includes, for example, a method of heating and holding the adhesive in a storage tank in advance, and supplying the heated adhesive to the coating device. The temperature for heating the protective film, the adhesive or the laminate is preferably 30 to 80 ° C, and more preferably 40 to 60 ° C. If the heating temperature exceeds 80 ° C., there is a concern that the protective film, the adhesive, or the laminate is deteriorated by heat. In addition, if the heating temperature does not reach 30 ° C., there is a tendency that the effect of improving the adhesion between the protective film and the polarizing film 30 is insufficient.

When the coating layer of the adhesive is formed on the protective film, the moisture content of the protective film according to the dry weight method is preferably 0.2 to 5% by weight. When the moisture content is in the above range, especially when the adhesive is a cationic polymerization type adhesive, the reactivity of the adhesive is improved, and the adhesiveness between the protective film and the polarizing film 30 tends to be improved.

The source of the active energy ray may be any one that generates, for example, ultraviolet rays, electron rays, X-rays, and the like. Active energy rays are preferably ultraviolet rays. The ultraviolet light source is preferably a light source with a light emission distribution below a wavelength of 400 nm. Examples include: low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, fluorescent lamps, black light lamps, and microwaves. Excite mercury lamps, metal halide lamps, etc.

Although the intensity of the active energy ray irradiation to the adhesive layer depends on each adhesive composition, the intensity of light irradiation in the wavelength region effective for activation of the photopolymerization initiator is 0.1 to 1000 mW / cm ² Better. If the light irradiation intensity is too small, the reaction time becomes too long. On the other hand, if the light irradiation intensity is too large, yellowing of the adhesive layer may occur due to the heat radiated by the lamp and the heat generated during the polymerization of the adhesive. Deterioration of the polarizing film 30 or defective surface of the protective film. In addition, the light irradiation time to the adhesive is also limited by each adhesive composition, but it is preferable to set the cumulative light amount expressed by the product of the light irradiation intensity and the light irradiation time to 10 to 5000 mJ / cm ² . If the accumulated light amount is too small, the generation of active species from the photopolymerization initiator may be insufficient, and the obtained adhesive layer may not be sufficiently hardened. On the other hand, when the accumulated light amount is too large, the light irradiation time may be insufficient. It becomes very long and easily becomes unfavorable for improving productivity.

The timing at which the protective film is laminated on the polarizing film 30 through the coating layer of the adhesive and the timing at which the coating layer is hardened or dried are not particularly limited. For example, a protective film can be laminated, and then the coating layer can be hardened or dried, and then another protective film can be laminated to harden or dry the coating layer. Alternatively, both protective films may be laminated sequentially or simultaneously, and then the two-sided coating layers may be simultaneously hardened or dried. In addition, irradiation with active energy rays can be performed on either side of the protective film. For example, when one protective film contains an ultraviolet absorbent and the other protective film does not contain an ultraviolet absorbent, it is preferable that active energy rays are irradiated from the protective film side without the ultraviolet absorbent. By such irradiation, the active energy rays irradiated can be effectively used, and the curing speed can be increased. degree.

The thickness of the first and second adhesive layers 15 and 25 after curing or drying is usually 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less. When the thicknesses of the first and second adhesive layers 15 and 25 are too large, the reaction rate of the adhesive layer decreases, and the moisture and heat resistance of the polarizing plate tends to deteriorate. The thickness of the first and second adhesive layers 15 and 25 is usually 0.01 μm or more, and preferably 0.1 μm or more. The thicknesses of the first adhesive layer 15 and the second adhesive layer 25 may be the same or different.

(5) Other components of polarizing plate (5-1) Optical functional film

The polarizing plate may be provided with an optical functional film other than the polarizing film 30 for imparting a desired optical function, and a suitable example thereof is a retardation film. As described above, the first protective film 10 and / or the second protective film 20 may also serve as a retardation film, but a retardation film different from the protective film may be separately laminated. In the latter case, the retardation film can be laminated on the outer surface of the first protective film 10 and / or the second protective film 20 via an adhesive layer and an adhesive layer.

Specific examples of the retardation film include a birefringent film made of a stretched film of a thermoplastic resin having translucency, a film in which disc liquid crystals or nematic liquid crystals are fixed and oriented, and a base film Those having the above-mentioned liquid crystal layer. The base film is usually a thermoplastic resin film. The thermoplastic resin is preferably a cellulose ester resin such as triethylfluorenyl cellulose.

The thermoplastic resin that forms a birefringent film can be used for those described in protective films. For example, if a cellulose ester resin is used as an example, a birefringent film can be obtained by a method in which a film is formed from a cellulose ester resin containing a compound having a phase difference adjustment function. A method, a method of coating a compound having a retardation adjustment function on the surface of a cellulose ester resin film, and a method of extending the cellulose ester resin toward one or two axes. As the thermoplastic resin forming the birefringent film, other thermoplastic resins such as polyvinyl alcohol-based resin, polystyrene-based resin, polyarylate-based resin, and polyamide-based resin can also be used.

For the purpose of controlling the optical characteristics such as wideband, the retardation film can be used in combination of two or more. Moreover, it is not limited to a film having optical anisotropy, and a zero retardation film that is substantially optically in the same direction may be used as the retardation film. The zero retardation film refers to a film in which the in-plane retardation value R _e and the thickness direction retardation value R _th are both -15 to 15 nm. The in-plane retardation value R _e and the thickness direction retardation value R _th herein are values at a wavelength of 590 nm.

The in-plane phase difference value R _e and the thickness direction phase difference value R _th are respectively defined as follows: R _e = (n _x -n _y ) × d

R _th = [(n _x + n _y ) / 2-n _z ] × d.

In the formula, n _x is the refractive index in the slow axis direction (x-axis direction) in the film plane, and n _y is the refractive index in the fast axis direction (y-axis direction perpendicularly intersecting the x-axis in the plane) in the film plane. n _z is the refractive index in the film thickness direction (the z-axis direction perpendicular to the film surface), and d is the thickness of the film.

On the zero retardation film, a thermoplastic resin described in a protective film or a birefringent film can be used. For example, a polyolefin resin containing a cellulose ester resin such as a chain polyolefin resin and a cyclic polyolefin resin can be used. Resin film of polyester resin based on polyethylene terephthalate. Among these, since it is easy to control a phase difference value and it is also easy to obtain, it is preferable to use a cellulose ester resin and a polyolefin resin.

Examples of other optically functional films (optical members) that can be included in a polarizing plate include a light collecting plate, a brightness enhancement film, a reflective layer (reflective film), a transflective reflective layer (transflective reflective film), and a light diffusion layer ( Light diffusing film), etc. These are generally the cases where the polarizing plate is a polarizing plate arranged on the back side (backlight side) of the liquid crystal cell.

The light collecting plate is used for the purpose of controlling the light path, and the user may be a prismatic array sheet, a lens array sheet, a dot attached sheet, or the like.

The brightness enhancement film is used to improve the brightness of a liquid crystal display device to which a polarizing plate is applied. Specifically, there are laminated thin film films having mutually different refractive index anisotropies, and reflective polarized separation films designed in such a manner that the reflectance is anisotropic, and alignment films of cholesterol-like liquid crystal polymers. A circularly polarized light separation sheet supported by the alignment liquid crystal layer of the alignment film on a substrate film.

The reflection layer, the transflective reflection layer, and the light diffusion layer are respectively provided so that the polarizing plate is a reflective, transflective, or diffused optical member. Reflective polarizers allow liquid crystal display devices of the type that reflect incident light from the viewing side to display, and can omit light sources such as backlights. Therefore, it is easy to reduce the thickness of the liquid crystal display device. A semi-transmissive polarizer can be used for a liquid crystal display device that is reflective in bright places and displays light from a backlight in dark places. In addition, a diffusion-type polarizing plate can be used for a liquid crystal display device that provides light diffusivity and suppresses display defects such as moire. The reflection layer, the transflective reflection layer, and the light diffusion layer can be formed by a known method.

(5-2) Adhesive layer

The polarizing plate of the present invention may include an adhesive layer for bonding the polarizing plate to an image display element such as a liquid crystal cell or other optical members. An adhesive layer can be laminated on the outside of the protective film. The adhesive layer may be laminated on the outside of the first protective film, or may be laminated on the outside of the second protective film.

As the adhesive that can be used for the adhesive layer, a (meth) acrylic resin, a silicone resin, a polyester resin, a polyurethane resin, a polyether resin, or the like can be used as a matrix polymer. Among them, from the viewpoints of transparency, adhesion, reliability, weather resistance, heat resistance, reworkability, etc., it is preferable to use a (meth) acrylic adhesive. In the (meth) acrylic adhesive, an alkane having a carbon number of 20 or less such as methyl, ethyl, or butyl is preferably blended so that the glass transition temperature is 25 ° C or lower, and more preferably 0 ° C or lower. (Meth) acrylic acid alkyl esters and (meth) acrylic monomers containing functional groups such as (meth) acrylic acid and hydroxyethyl (meth) acrylate have a weight average molecular weight of 100,000 or more Acrylic resin is used as a base polymer.

The adhesive layer is formed on the polarizing plate. For example, the adhesive composition can be dissolved or dispersed in an organic solvent such as toluene or ethyl acetate. A method of preparing a solution of 10 to 40% by weight, and directly coating the solution on the object surface of the polarizing plate to form an adhesive layer; forming the adhesive layer into a thin sheet on a separation film subjected to a release treatment, This is performed by a method such as moving it to the target surface of the polarizing plate. The thickness of the adhesive layer is determined depending on its adhesive force and the like, but a range of about 1 to 50 μm is appropriate, and a range of 2 to 40 μm is preferable.

The polarizing plate may contain the above-mentioned separation film. The separation membrane may be a film composed of a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate, and the like. Among them, stretch film of polyethylene terephthalate is preferred.

In the adhesive layer, it can also be blended as required: fillers containing glass fiber, glass particles, resin particles, metal powder and other inorganic powders, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents, etc.

Examples of the antistatic agent include ionic compounds, conductive fine particles, and conductive polymers. The use of ionic compounds is preferred. The cation component constituting the ionic compound may be an inorganic cation or an organic cation. From the viewpoint of compatibility with a (meth) acrylic resin, an organic cation is preferred. Examples of the organic cation include a pyridinium cation, an imidazolium cation, an ammonium cation, a sulfonium cation, and a sulfonium cation. On the other hand, the anionic component constituting the ionic compound may be an inorganic anion or an organic anion, but it is preferably an anionic component containing a fluorine atom in order to impart excellent antistatic properties to the ionic compound. Fluorine atom-containing anion component may include: hexafluorophosphate anion [(PF ₆ ^-)], bis (trifluoromethane sulfonic acyl) acyl imide anion _{[(CF 3 SO 2) 2} N -], bis (sulfo-fluoro-acyl) acyl imide anion ^{_{[(FSO 2) 2 N -}} ] and the like.

(5-3) Protective film

The polarizing plate of the present invention may contain a protective film for temporarily protecting the surface (protective film surface). The protective film is formed by, for example, laminating a polarizing plate on an image display element or another optical member, and then peeling and removing the adhesive layer.

The protective film is composed of a base film and an adhesive layer laminated thereon. The adhesive layer refers to the above description. The resin constituting the base film may be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate and polyethylene naphthalate. Resin, thermoplastic resin such as polycarbonate resin. Polyester resins such as polyethylene terephthalate are preferred.

The polarizing plate of the present invention can be bonded to an image display element such as a liquid crystal cell via an adhesive layer. Examples of the liquid crystal cell include an IPS type and a VA type.

[Example]

Hereinafter, the present invention will be described more specifically by showing examples and comparative examples, but the present invention is not limited to these examples. In the following examples, the radical polymerizable compound, the photo radical polymerization initiator, and the additives constituting the adhesive are the following.

(Radical Polymerizable Compound)

[1] hardenable compound 1: dicyclopentenyl acrylate (trade name "FA-513AS" obtained from Hitachi Chemical Co., Ltd.), [2] hardenable compound 2: 4-hydroxybutyl acrylate (from "4HBA" trade name obtained by Osaka Organic Industry Co., Ltd.), [3] hardenable compound 3: N, N-dimethylacrylamide (trade name obtained from KJ Chemicals Co., Ltd. " DMAA "), [4] hardenable compound 4: N- (2-hydroxyethyl) acrylamide (trade name" HEAA "obtained from KJ Chemicals Co., Ltd.), [5] hardenable compound 5 : Trimethylolpropane triacrylate (trade name "A-TMPT" obtained from Shin Nakamura Chemical Industry Co., Ltd.), [6] hardenable compound 6: polyethylene glycol # 600 diacrylate (from Trade name "A-600" obtained by Shin Nakamura Chemical Industry Co., Ltd.), [7] hardenable compound 7: dipentaerythritol hexaacrylate (product obtained from Shin Nakamura Chemical Industry Co., Ltd.) (Named "A-DPH"), [8] hardenable compound 8: UV-curable urethane acrylate resin (from Nippon Synthetic Chemical Industry Co., Ltd. Co., Ltd.), trade name "UV-3700B"), [9] Curable compound 9: UV-curable urethane acrylate resin (trade name "UV" obtained from Japan Synthetic Chemical Industry Co., Ltd.) -3000B "), [10] hardenable compound 10: 1,4-cyclohexanedimethanol monoacrylate (trade name" CHDMMA "obtained from Nippon Kasei Co., Ltd.).

The above-mentioned UV-curable urethane acrylate resin (trade name "UV-3700B") is mainly composed of urethane acrylate The UV-curable resin has a viscosity of 30,000 to 60,000 mPa · s / 60 ° C, a molecular weight (Mw) of 38,000, and the number of functional groups of the oligomer is 2.

In addition, the above-mentioned UV-curable urethane acrylate resin (trade name "UV-3000B") is a UV-curable resin mainly composed of urethane acrylate, and has a viscosity of 45,000 to 65000 mPa‧ s / 60 ° C, molecular weight (Mw) is 18000, and the number of functional groups of the oligomer is 2.

(Photo radical polymerization initiator)

[11] Starter 1: 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinylpropane-1-one (trade name "Irgacure 907" obtained from BASF Corporation) ).

(additive)

[12] Additive 1: Polysiloxane leveling agent (trade name "SH710" obtained from Toray‧Dowcorning (Co., Ltd.)).

<Production Examples 1 to 5: Preparation of UV-curable Adhesive>

The above-mentioned radically polymerizable compound, photo-radical polymerization initiator, and additives were mixed into a 20 mL conical sample tube at a blending ratio (the numerical value in Table 1 represents weight parts) described in Table 1 and mixed / desorbed. After foaming, liquid ultraviolet-curable adhesives A to E were prepared.

<Manufacturing Examples 6 to 9: Preparation of UV-curable adhesive>

The above-mentioned radically polymerizable compound, photo-radical polymerization initiator, and additives were prepared at the mixing ratios shown in Table 2 (the values in Table 2 indicate parts by weight), and the mixture was measured into a 20 mL spiral-mouth sample tube and mixed. Defoaming and preparing liquid ultraviolet-curable adhesives F to I, respectively.

<Manufacturing Example 10: Production of (meth) acrylic resin film>

A (meth) acrylic resin in which a copolymer of methyl methacrylate and methyl acrylate was copolymerized at a weight ratio of 96: 4 was prepared. In addition, acrylic rubber particles are prepared, which are elastomer particles having a three-layer structure, in which the innermost layer contains a hard polymer, which is formed by polymerizing methyl methacrylate with a small amount of allyl methacrylate Hard polymer; the middle layer contains a soft elastomer, which is mainly composed of butyl acrylate, and is further polymerized using styrene and a small amount of allyl methacrylate; the outermost layer contains a hard polymer, which is a hard polymer The system is polymerized with methyl methacrylate using a small amount of ethyl acrylate.

The above-mentioned (meth) acrylic resin and the above-mentioned acrylic rubber particles were prepared in a weight ratio of 70:30, and the benzotriazole-based ultraviolet absorber particles were added and melted in a biaxial extruder. While kneading, 0.05 parts by weight of stearic acid as a lubricant was added to 100 parts by weight of the particles, and the mixture was mixed to obtain particles of a (meth) acrylic resin composition. Put this particle into 65mm A one-axis extruder was extruded through a T-shaped die set at a temperature of 275 ° C, and the two sides of the extruded film-shaped molten resin were sandwiched by two polishing rollers set at 45 ° C with a mirror surface and cooled, A (meth) acrylic resin film having a thickness of 80 μm was produced. The transmittance of the obtained (meth) acrylic resin film at a wavelength of 380 nm was 25% or less.

<Examples 1 to 3, Comparative Examples 1 to 3> (1) Fabrication of polarizing plate

Corona discharge treatment was applied to one side of the (meth) acrylic resin film (first protective film) produced in Production Example 10, and a bar coater was used on the corona discharge treated surface so that the thickness after curing became The adhesive described in Table 3 was applied as a first adhesive (adhesive for forming the first adhesive layer) to a thickness of about 2.5 μm. Next, a 25-micrometer-thick polyvinyl alcohol (PVA) -iodine-type polarizing film was stuck on the coating surface. Next, an in-plane retardation value R at a wavelength of 590 nm was formed on a 50 μm-thick retardation film [trade name “ZEONOR” manufactured by ZEON (Japan) Co., Ltd.] containing a cyclic polyolefin resin (norzene resin). _e : 52nm] (second protective film) is subjected to a corona discharge treatment on one side, and a bar coater is applied to the corona discharge treated surface so that the thickness after curing becomes about 2.5 μm as a second adhesive. The adhesives are also described in Table 3 for the adhesives. The polarizing film with the (meth) acrylic resin film produced above was laminated on the polarizing film side on this coating surface, and it pressed and bonded using the bonding roller, and the laminated body was obtained. For this laminated body, an ultraviolet irradiation device using an attached conveyor from the side of the cyclic polyolefin resin film [the lamp is a "D Bulb" manufactured by Fusion UV systems] was used to accumulate a light amount of 1500 mJ / cm ² (UVB) method to irradiate ultraviolet rays to harden the adhesive layer on both sides to produce a polarizing plate.

(2) Determination of storage elastic modulus of adhesive layer at 80 ° C (for adhesive A)

A polarizing film surface of a polarizing plate having a thickness of 25 μm of a triethyl cellulose film on a single-area layer of a polarizing film having a thickness of 25 μm is coated with a coating machine [rod coating machine, manufactured by Daiichi Chemical Co., Ltd.] to An ultraviolet curable adhesive (Adhesive A) prepared in Production Example 1 was applied so that the thickness after curing was about 2.5 μm, and then a cyclic polyolefin resin film having an area layer thickness of 50 μm was applied. Next, by using a "D lamp" manufactured by Fusion UV Systems, ultraviolet rays were irradiated from the side of the cyclic polyolefin resin film so that the accumulated light amount became 1500 mJ / cm ² (UVB), and the adhesive layer was hardened. Next, the cyclic polyolefin resin film was peeled off, and a laminated body in which an adhesive layer was laminated and cured on a polarizing plate was prepared, and this was used as a measurement sample.

The storage elastic modulus of the adhesive layer was measured by a torsional shear method using a rotary viscoelasticity measuring device "Physica MCR 301" sold by Anton Paar (Co., Ltd.). Specifically, the above-mentioned measurement sample is set in a device as a sample stage / polarizing plate / adhesive layer / measurement system, and after a load of 1 N is applied, the frequency is 1 Hz and the deviation is 1% at 10 ° C / min. The temperature was raised from 10 ° C to 85 ° C, and the value of the storage elastic modulus at 80 ° C was read. The results are shown in Table 3.

(3) Determination of storage elastic modulus of the adhesive layer at 80 ° C (for adhesives B to E)

Using a coater [rod coater, manufactured by Daiichi Chemical Co., Ltd.], one side of a cyclic polyolefin resin film having a thickness of 50 μm was applied to the ultraviolet curable adhesive prepared in Production Examples 2 to 5 ( Any of the adhesives B to E), and a cyclic polyolefin resin film having a thickness of 50 μm is further laminated on the coating surface. Next, the "D lamp" manufactured by Fusion UV Systems Co., Ltd. was irradiated with ultraviolet rays so that the accumulated light amount became 1500 mJ / cm ² (UVB), and the adhesive layer was hardened. This was cut into a size of 5 mm × 30 mm, and the cyclic polyolefin resin film was peeled to obtain a cured film of the adhesive. A dynamic viscoelasticity measuring device "DVA-220" manufactured by IT Measurement Corporation was used to make the long side of the cured film the stretching direction, and the film was held at a 2 cm interval between the grippers, and The frequency of stretching and shrinking was set to 10 Hz, and the rate of temperature increase was set to 10 ° C / minute, and the storage elastic modulus at a temperature of 80 ° C was determined. The results are shown in Table 3.

(4) Evaluation of workability of polarizing plate

Using a 800 mm × 800 mm blade made by Dumbbell, punching was performed from the first protective film side of the polarizing plate, and the state of floating and peeling of the end of the polarizing plate was visually observed, and processability was evaluated according to the following criteria. The evaluation results are shown in Table 3.

A: There is no floating or peeling at the end of the polarizing plate, B: There is floating or peeling at the end of the polarizing plate.

(5) Formation of adhesive layer

(Meth) acrylic acid obtained by adding an isocyanate-based crosslinking agent, a silane coupling agent, and an antistatic agent to a (meth) acrylic resin of butyl acrylate, methyl acrylate, and a copolymer of acrylic acid and hydroxyethyl acrylate. The organic solvent solution of the adhesive is applied to a 38 μm-thick separation membrane containing polyethylene terephthalate through a mold coater in a thickness of 20 μm after drying [from Lintec ( Co., Ltd.) obtained the release treatment surface under the trade name "SP-PLR 382052"] to make a thin film with a separation membrane Sheet adhesive. Next, the cyclic polyolefin-based resin film surface of the polarizing plate prepared in the above (1) was bonded to the surface (adhesive surface) on the opposite side of the release film of the sheet-shaped adhesive obtained above by a laminator. Thereafter, it was aged for 7 days under conditions of a temperature of 23 ° C. and a relative humidity of 65 to obtain a polarizing plate having an adhesive layer.

(6) Evaluation of cold and hot shock resistance of polarizing plate

A sheet having a size of 200 mm × 150 mm was cut out from the polarizing plate having an adhesive layer prepared in the above (5), and an alkali-free glass was bonded to the side of the adhesive layer [trade name "EAGLE XG" manufactured by Corning Corporation. ], As a measurement sample for the hot and cold shock test (Heat Shock test). For each of the polarizing plate sheet systems, four measurement samples were prepared. The cold and hot shock test was performed by holding the temperature at -40 ° C for 30 minutes, and then heating to 70 ° C for 30 minutes as a cycle. This cycle was repeated for a total of 100 cycles. The cold and hot shock test was performed on four measurement samples, and the cold and hot shock resistance was evaluated from the ratio of cracks or ruptures observed from the polarizing film after the test to the total number of samples (4). The evaluation results are shown in Table 3.

<Examples 4 to 6> (1) Production of polarizing plate (Example 4)

Corona discharge treatment was applied to one side of the (meth) acrylic resin film (first protective film) produced in Production Example 10, and the corona discharge treated surface was treated with a bar coater to obtain a thickness after curing. The adhesive described in Table 4 as the first adhesive (adhesive for forming the first adhesive layer) was applied so as to be about 2.5 μm. Next, a polyvinyl alcohol (PVA) -iodine-based polarizing film having a thickness of 25 μm was laminated on the coated surface. Next, a corona discharge treatment was applied to one side of a 40 μm-thick retardation film (trade name “KC4CR” manufactured by Konica Minolta (Co., Ltd.)) (second protective film) containing an ethyl cellulose resin, The corona discharge treated surface was coated with a bar coater so that the thickness after curing was about 2.5 μm. The second adhesive (adhesive for forming the second adhesive layer) was also described in Table 4. Agent. On the coating surface, the polarizing film with the (meth) acrylic resin film produced as described above was superposed on the polarizing film side, and pressed and bonded with a bonding roller to obtain a laminated body. This laminated body was irradiated with ultraviolet rays from an ethyl cellulose resin film side using an attached conveyor [the lamp is a "D lamp" manufactured by Fusion UV Systems] so that the accumulated light amount would be 1500 mJ / cm ² (UVB) method to harden the adhesive layer on both sides to produce a polarizing plate.

(2) Production of polarizing plate (Examples 5 to 6)

Corona discharge treatment was applied to one side of the (meth) acrylic resin film (first protective film) produced in Production Example 10, and the corona discharge treated surface was treated with a bar coater so that the thickness after hardening became The adhesive described in Table 4 was applied as a first adhesive (adhesive for forming a first adhesive layer) to a thickness of about 2.5 μm. Next, a 25-micrometer-thick polyvinyl alcohol (PVA) -iodine-type polarizing film was stuck on the coating surface. Next, an in-plane retardation value R at a wavelength of 590 nm was formed on a 50 μm-thick retardation film [trade name “ZEONOR” manufactured by ZEON (Japan) Co., Ltd.] containing a cyclic polyolefin resin (norzene resin). _e : 52nm] (second protective film) is subjected to a corona discharge treatment on one side, and a bar coater is applied to the corona discharge treated surface so that the thickness after curing becomes about 2.5 μm as a second adhesive. The adhesives (adhesives forming the second adhesive layer) are also described in Table 4 for the adhesives. On the coating surface, the polarizing film with the (meth) acrylic resin film produced as described above was laminated on the polarizing film side, and pressed and bonded using a bonding roller to obtain a laminated body. For this laminated body, an ultraviolet irradiation device using an attached conveyor was used from the cyclic polyolefin resin film side [the lamp is a "D lamp" manufactured by Fusion UV Systems] so that the accumulated light amount was 1500 mJ / cm ² ( UVB) is used to irradiate ultraviolet rays to harden the adhesive layer on both sides to produce a polarizing plate.

(3) Determination of storage elastic modulus of the adhesive layer at 80 ° C (for adhesives F to I)

Using a coater [rod coater, manufactured by Daiichi Chemical Co., Ltd.] on one side of a cyclic polyolefin resin film having a thickness of 50 μm, the ultraviolet curable adhesive prepared in Production Examples 6 to 9 was applied ( Adhesives F to I) are further laminated with a cyclic polyolefin-based resin film having a thickness of 50 μm on the coating surface. Next, the "D lamp" manufactured by Fusion UV Systems Co., Ltd. was irradiated with ultraviolet rays so that the accumulated light amount became 1500 mJ / cm ² (UVB), and the adhesive layer was hardened. This was cut into a size of 5 mm × 30 mm, and the cyclic polyolefin resin film was peeled to obtain a cured film of the adhesive. A dynamic viscoelasticity measuring device "DVA-220" manufactured by IT Measurement Corporation was used to make the long side of the film stretched. The hardened film was held at a distance of 2 cm between the grippers, and pulled. The frequency of stretching and contracting was set to 10 Hz, and the rate of temperature increase was set to 10 ° C / minute, and the storage elastic modulus at a temperature of 80 ° C was determined. The results are shown in Table 4.

(4) Evaluation of workability of polarizing plate

The processability of the polarizing plates obtained in Examples 4 to 6 was evaluated in the same manner as in (4) of <Examples 1 to 3 and Comparative Examples 1 to 3>. The evaluation results are shown in Table 4.

(5) Formation of adhesive layer

In the same manner as in (5) of <Examples 1 to 3 and Comparative Examples 1 to 3>, the polarizing plate obtained in Examples 4 to 6 was used to obtain a polarizing plate having an adhesive layer. The sheet-like adhesive is adhered to the surface of the cyclic polyolefin-based resin film or the surface of the acetocellulose-based resin film of the polarizing plate.

(6) Evaluation of cold and hot shock resistance of polarizing plate

In the same manner as in (4) of <Examples 1 to 3 and Comparative Examples 1 to 3>, the cold and hot shock resistance of the polarizing plates obtained in Examples 4 to 6 was evaluated. The evaluation results are shown in Table 4.

Claims (8)

A polarizing plate includes a first protective film, a first adhesive layer, a polarizing film, a second adhesive layer, and a second protective film in this order. The storage elastic modulus of the first adhesive layer at 80 ° C is 0.1 MPa. Above, it is less than 800 MPa, and the storage elastic modulus of the second adhesive layer at 80 ° C. is more than 800 MPa and less than 10,000 MPa. The polarizing plate according to item 1 in the scope of the patent application, wherein the difference between the storage elastic modulus of the first adhesive layer at 80 ° C and the storage elastic modulus of the second adhesive layer at 80 ° C is 100 MPa or more. The polarizing plate according to item 1 of the scope of patent application, wherein the storage elastic modulus of the second adhesive layer at 80 ° C. is 1,000 MPa or more. The polarizing plate according to item 1 of the scope of patent application, wherein at least one of the first adhesive layer and the second adhesive layer is a cured product layer of an active energy ray-curable adhesive. The polarizing plate according to item 4 of the scope of patent application, wherein the energy ray-curable adhesive contains a radical polymerizable compound. The polarizing plate according to item 1 of the scope of patent application, wherein the first protective film and the second protective film are selected from polyester resin, polycarbonate resin, polyolefin resin, and (meth) Acrylic resin and cellulose ester resin consist of resins in the group. The polarizing plate according to item 6 of the scope of patent application, wherein the first protective film is made of (meth) acrylic resin, and the second protective film is made of polyolefin resin or cellulose ester resin. . The polarizing plate according to item 1 of the scope of patent application, wherein at least one of the first protective film and the second protective film is a retardation film.