KR102394679B1 - Polarizer - Google Patents

Abstract

[Problem] Even if the ultraviolet light transmittance of the thermoplastic resin film bonded to both surfaces of the polarizing film is low, the adhesive layer interposed between the polarizing film and the thermoplastic resin film is sufficiently cured, so that the adhesion between the films is excellent, and the problem of coloring is eliminated A polarizing plate that is difficult to produce is provided.
[Solutions] A first thermoplastic resin film, a first adhesive layer, a polarizing film, a second adhesive layer, and a second thermoplastic resin film, wherein at least one of the first and second adhesive layers is cationic polymerization with a cation-curable component It is a cured product layer of an ultraviolet curable adhesive containing an initiator, wherein the cation-curable component contains 30 to 70% by weight of an epoxy compound and 30 to 70% by weight of an oxetane compound, and the content of the sensitizer is 100 parts by weight of the cation-curable component It is 0 to 0.01 parts by weight, and the first and second thermoplastic resin films have light transmittance of 0.5 to 5% and 0 to 5%, respectively, at the absorption maximum wavelength in the ultraviolet region of the cationic polymerization initiator.

Description

Polarizer

The present invention relates to a polarizing plate.

Generally, a polarizing plate has the structure which bonded together the protective film which consists of a thermoplastic resin on one side or both surfaces of a polarizing film with the adhesive agent. Patent document 1 describes using the ultraviolet curable adhesive agent containing an epoxy resin, a photocationic polymerization initiator, and an anthracene type photosensitizer as an adhesive agent.

Patent Document 1: Japanese Patent Laid-Open No. 2008-257199

As a thermoplastic resin film joined to both surfaces of a polarizing film, in order to harden an ultraviolet curable adhesive agent, the low transmittance|permeability of the light irradiated may be used for all. In this case, even if it irradiates an ultraviolet-ray through a thermoplastic resin film, it is difficult to fully harden the adhesive bond layer interposed between a polarizing film and a thermoplastic resin film. For this reason, in order to harden an ultraviolet curable adhesive favorably and to improve the adhesiveness between the films to be joined, it is effective means to make an ultraviolet curable adhesive contain a photosensitizer like patent document 1 was carried out.

Anthracene-type photosensitizers are known as a photosensitizer. However, in order to sufficiently express the above effect, it is necessary to use a relatively large amount of anthracene-based photosensitizers. Since the anthracene-based photosensitizer exhibits maximum absorption in light of a wavelength exceeding 380 nm, there was a problem that the cured adhesive layer and furthermore the polarizing plate were colored when the compounding amount was increased.

An object of the present invention is an adhesive layer interposed between a polarizing film and a thermoplastic resin film, even when using a thermoplastic resin film bonded on both surfaces of a polarizing film that has a low transmittance of irradiated light in order to cure an ultraviolet curable adhesive. This is fully hardened|cured, it is excellent in the adhesiveness between films, and it exists in providing the polarizing plate which does not produce the problem of coloring easily.

The present invention provides a polarizing plate described below.

[1] comprising a first thermoplastic resin film, a first adhesive layer, a polarizing film, a second adhesive layer, and a second thermoplastic resin film in this order,

At least one of the first adhesive layer and the second adhesive layer is a cured product layer of an ultraviolet curable adhesive,

The ultraviolet curable adhesive comprises a cation-curable component (A) and a cationic polymerization initiator (B),

The cationically curable component (A) contains 30 to 70 wt% of an epoxy compound (A1) and 30 to 70 wt% of an oxetane compound (A2) when the total amount is 100 wt%,

The content of the sensitizer (C) in the ultraviolet curable adhesive is 0 to 0.01 parts by weight with respect to 100 parts by weight of the cation-curable component (A),

In the first thermoplastic resin film, the transmittance of light at the absorption maximum wavelength in the ultraviolet region of the cationic polymerization initiator is 0.5 to 5%,

The said 2nd thermoplastic resin film is a polarizing plate whose transmittance|permeability of the light in the absorption maximum wavelength in the ultraviolet region of the said cationic polymerization initiator is 0 to 5%.

[2] The cation-curable component (A) contains 40 to 70 wt% of an epoxy compound (A1) and 30 to 60 wt% of an oxetane compound (A2) when the total amount is 100 wt% The polarizing plate according to [1].

[3] The first thermoplastic resin film and the second thermoplastic resin film are a thermoplastic resin selected from the group consisting of a polyester-based resin, a polycarbonate-based resin, a polyolefin-based resin, a (meth)acrylic resin, and a cellulose ester-based resin. The polarizing plate according to [1] or [2], which consists of.

[4] The polarizing plate according to [3], wherein the first thermoplastic resin film is composed of a polyolefin-based resin or cellulose ester-based resin, and the second thermoplastic resin film is composed of a (meth)acrylic resin.

[5] The polarizing plate according to any one of [1] to [4], wherein at least one of the first thermoplastic resin film and the second thermoplastic resin film is a retardation film.

According to the present invention, as the thermoplastic resin film bonded on both surfaces of the polarizing film, even when a film having a low transmittance of irradiated light to cure the ultraviolet curable adhesive is used, the adhesive layer interposed between the polarizing film and the thermoplastic resin film This sufficiently hardened|cured, it is excellent in the adhesiveness between films, and the polarizing plate which does not produce the problem of coloring easily can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows an example of the polarizing plate which concerns on this invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment is shown and this invention is demonstrated in detail.

(1) Configuration of polarizing plate

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows an example of the polarizing plate which concerns on this invention. As shown in FIG. 1 , the polarizing plate according to the present invention includes a first thermoplastic resin film 21 , a first adhesive layer 15 , a polarizing film 10 , a second adhesive layer 25 , and a second thermoplastic resin film. (22) is included in this order. The polarizing plate may consist of the 1st thermoplastic resin film 21, the 1st adhesive bond layer 15, the polarizing film 10, the 2nd adhesive bond layer 25, and the 2nd thermoplastic resin film 22.

Usually, the first thermoplastic resin film 21 is laminated in contact with the surface of the first adhesive layer 15 , and the first adhesive layer 15 is laminated in contact with the surface of the polarizing film 10 . In addition, usually, the second thermoplastic resin film 22 is laminated in contact with the surface of the second adhesive layer 25 , and the second adhesive layer 25 is laminated in contact with the surface of the polarizing film 10 .

The polarizing plate may further be equipped with the other layer laminated|stacked on the 1st thermoplastic resin film 21 or the 2nd thermoplastic resin film 22. Examples of the other layer include a retardation plate, a reflective layer, a transflective layer, a light diffusion layer, a light collecting plate, a brightness improving film, an adhesive layer, and the like. The polarizing plate may be provided with two or more other layers. The other layer may be laminated on the first thermoplastic resin film 21 or the second thermoplastic resin film 22 using an adhesive or an adhesive. Another layer may serve as the first thermoplastic resin film 21 or the second thermoplastic resin film 22 .

What makes a (meth)acrylic-type polymer, a silicone-type polymer, polyester, polyurethane, polyether etc. a base polymer can be used for the adhesive which comprises an adhesive layer. Among them, it has excellent optical transparency like a (meth)acrylic pressure-sensitive adhesive, maintains appropriate wettability and cohesive force, has excellent adhesion to a substrate, and furthermore has weather resistance and heat resistance, etc., and floats or peels off under heating or humidification conditions. It is preferable to select and use one that does not cause such problems. In the (meth)acrylic pressure-sensitive adhesive, an alkyl ester of (meth)acrylic acid having an alkyl group having 20 or less carbon atoms, such as a methyl group, an ethyl group, a butyl group, and a functional group such as (meth)acrylic acid or (meth)acrylic acid hydroxyethyl containing (meth)acrylic acid (meth) ) A (meth)acrylic copolymer having a weight average molecular weight of 100,000 or more, in which an acrylic monomer is blended so as to have a glass transition temperature of preferably 25° C. or less, and more preferably 0° C. or less, is useful as a base polymer. In this specification, "(meth)acryl" means at least one chosen from acryl and methacryl. The same applies to "(meth)acrylate".

Forming the pressure-sensitive adhesive layer on a polarizing plate or the like is, for example, a method of dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a coating solution, and coating this directly on a polarizing plate, or a method of applying the pressure-sensitive adhesive layer on a release film in advance It can form by the method etc. which form and transfer it on a polarizing plate. The thickness of the pressure-sensitive adhesive layer is determined depending on the adhesive strength and the like, but a range of about 1 to 50 µm is suitable.

In the pressure-sensitive adhesive layer, if necessary, a filler made of glass fibers, glass beads, resin beads, metal powder or other inorganic powder, a pigment, a colorant, an antioxidant, an ultraviolet absorber, or the like may be blended. Examples of the ultraviolet absorber include a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, and a nickel complex salt compound.

(2) Thermoplastic resin film

Both the first thermoplastic resin film 21 and the second thermoplastic resin film 22 have low transmittance of ultraviolet light. Specifically, as for the 1st thermoplastic resin film 21, the light transmittance in the absorption maximum wavelength in the ultraviolet region of the cationic polymerization initiator (B) contained in the ultraviolet curable adhesive agent mentioned later is 0.5 to 5 %. Moreover, as for the 2nd thermoplastic resin film 22, the transmittance|permeability of the light in the absorption maximum wavelength in the ultraviolet region of the cationic polymerization initiator (B) contained in an ultraviolet curable adhesive is 0-5 %. The transmittance of the first thermoplastic resin film 21 may be 0.5 to 3%, and the transmittance of the second thermoplastic resin film 22 may be 0 to 3%.

The method of measuring the transmittance of the first thermoplastic resin film 21 and the second thermoplastic resin film 22 is according to the description of the embodiment section to be described later.

In manufacture of a polarizing plate, in order to harden the adhesive bond layer interposed between the polarizing film 10 and the 1st and 2nd thermoplastic resin films 21 and 22, the 1st and/or 2nd thermoplastic resin film 21, 22 ) through which ultraviolet rays are irradiated. Accordingly, at least one of the first and second thermoplastic resin films 21 and 22 has the above-mentioned transmittance exceeding zero.

The means for achieving the above-described transmittance values in the first and second thermoplastic resin films 21 and 22 is not particularly limited. For example, the transmittance value described above may be achieved by containing an ultraviolet absorber in the film, may be achieved by providing a layer having ultraviolet absorption ability such as a layer containing a ultraviolet absorber, or may be achieved by constructing the film with a resin having ultraviolet absorption ability. Examples of the ultraviolet absorber include a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, and a nickel complex salt compound.

The thickness of the 1st thermoplastic resin film 21 and the 2nd thermoplastic resin film 22 is 1-200 micrometers, for example. From a viewpoint of thin film formation of a polarizing plate, etc., the thickness of these thermoplastic resin films becomes like this. Preferably it is 150 micrometers or less, More preferably, it is 120 micrometers or less, More preferably, it is 100 micrometers or less. From a viewpoint of the mechanical strength of a polarizing plate, etc., Preferably the thickness of these thermoplastic resin films is 10 micrometers or more, More preferably, it is 20 micrometers or more, More preferably, it is 40 micrometers or more. The thickness of the 1st thermoplastic resin film 21 and the thickness of the 2nd thermoplastic resin film 22 may be same or different.

The thermoplastic resin constituting the first thermoplastic resin film 21 and the second thermoplastic resin film 22 is, for example, a chain polyolefin-based resin (polypropylene-based resin or the like) or a cyclic polyolefin-based resin (such as a norbornene-based resin). polyolefin resin; Cellulose ester-based resins such as triacetyl cellulose and diacetyl cellulose; polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate-based resin; (meth)acrylic resins such as methyl methacrylate-based resins; polystyrene-based resin; polyvinyl chloride-based resin; acrylonitrile-butadiene-styrene resin; acrylonitrile-styrene-based resin; polyvinyl acetate-based resin; polyvinylidene chloride-based resin; polyamide-based resin; polyacetal-based resin; modified polyphenylene ether-based resin; polysulfone-based resin; polyether sulfone-based resin; polyarylate-based resin; polyamideimide-based resins; It may be a polyimide-based resin or the like.

The thermoplastic resin constituting the first thermoplastic resin film 21 and the second thermoplastic resin film 22 is preferably a polyester resin, a polycarbonate resin, a polyolefin resin, a (meth)acrylic resin, and a cellulose ester, respectively. It is a thermoplastic resin selected from the group which consists of a system resin. The first thermoplastic resin film 21 and the second thermoplastic resin film 22 may be films of a single layer structure each containing one or more thermoplastic resins selected from the above group, and different thermoplastic resins or the same thermoplastic resin It may be a film of a multilayer structure consisting of two or more layers composed of

Polyester-type resin is resin other than the said cellulose-ester-type resin which has an ester bond, and what consists of a polycondensate of polyhydric carboxylic acid or its derivative(s), and polyhydric alcohol is common. As the polyvalent carboxylic acid or its derivative, divalent dicarboxylic acid or its derivative can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylic acid. As the polyhydric alcohol, divalent diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. Examples of suitable polyester-based resins include polyethylene terephthalate.

The polycarbonate-based resin is an engineering plastic composed of a polymer to which a monomer unit is bonded through a carbonate group, and is a resin having high impact resistance, heat resistance, flame retardancy, and transparency. The polycarbonate-based resin may be a resin called a modified polycarbonate in which the polymer skeleton is modified in order to lower the photoelastic coefficient, or a copolymerized polycarbonate having improved wavelength dependence.

As chain polyolefin resin, the copolymer which consists of 2 or more types of chain olefin other than the homopolymer of a chain olefin like a polyethylene resin and a polypropylene resin is mentioned. More specific examples include polypropylene resins (polypropylene resins, which are homopolymers of propylene, or copolymers mainly composed of propylene), and polyethylene-based resins (polyethylene resins which are homopolymers of ethylene, or copolymers mainly composed of ethylene). do.

Cyclic polyolefin-type resin is a generic name of resin superposed|polymerized using cyclic olefin as a polymerization unit. Specific examples of the cyclic polyolefin resin include a ring-opened (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a copolymer of a cyclic olefin and a chain olefin such as ethylene and propylene (typically a random copolymer) and unsaturated Graft polymers modified with carboxylic acids or derivatives thereof, and hydrides thereof. Among them, norbornene-based resins using norbornene-based monomers such as norbornene and polycyclic norbornene-based monomers are preferably used as cyclic olefins.

Although (meth)acrylic-type resin is not specifically limited, Generally, it is a polymer which uses methacrylic acid ester as a main monomer, It is preferable that it is a copolymer in which a small amount of other comonomer components are copolymerized. This copolymer can usually be obtained by polymerization of a monofunctional monomer composition containing (meth)acrylic ester such as methyl methacrylate and methyl acrylate in the presence of a radical polymerization initiator and a chain transfer agent. Moreover, a 3rd monofunctional monomer can also be copolymerized with (meth)acrylic-type resin.

Examples of the third monofunctional monomer include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate and 2-hydroxyethyl methacrylate. methacrylic acid esters other than methyl methacrylate; acrylic acid esters such as ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate; hydroxyalkyl acrylic acid esters such as 2-(hydroxymethyl)methyl acrylate, 2-(1-hydroxyethyl)methyl acrylate, 2-(hydroxymethyl)ethyl acrylate, and 2-(hydroxymethyl)butyl acrylate; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene; substituted styrenes such as vinyltoluene and α-methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; Unsaturated imides, such as phenyl maleimide and cyclohexyl maleimide, are mentioned. A 3rd monofunctional monomer may be used individually by 1 type, and may use other multiple types together.

You may copolymerize a polyfunctional monomer with (meth)acrylic-type resin. Examples of the polyfunctional monomer include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di( What esterified the hydroxyl groups at both terminals of ethylene glycol or its oligomer, such as meth)acrylate and tetradecaethylene glycol di(meth)acrylate with acrylic acid or methacrylic acid; What esterified the hydroxyl groups at both ends of propylene glycol or its oligomer with acrylic acid or methacrylic acid; What esterified the hydroxyl group of dihydric alcohol, such as neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, and butanediol di(meth)acrylate with acrylic acid or methacrylic acid; What esterified the hydroxyl groups at both terminals of bisphenol A, the alkylene oxide adduct of bisphenol A, or these halogen-substituted products with acrylic acid or methacrylic acid; those obtained by esterification of polyhydric alcohols such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid, and those obtained by ring-opening addition of glycidyl acrylate or glycidyl methacrylate epoxy groups to these terminal hydroxyl groups; dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, and halogen-substituted products thereof and those obtained by ring-opening addition of an epoxy group of glycidyl acrylate or glycidyl methacrylate to an alkylene oxide adduct thereof; aryl (meth) acrylate; Aromatic divinyl compounds, such as divinylbenzene, are mentioned. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

The (meth)acrylic resin may also be modified by a reaction between the functional groups of the copolymer. Examples of the reaction include a demethanol condensation reaction within a polymer chain between a methyl ester group of methyl acrylate and a hydroxyl group of 2-(hydroxymethyl)methyl acrylate, a polymer between a carboxyl group of acrylic acid and a hydroxyl group of 2-(hydroxymethyl)methyl acrylate Intrachain dehydration condensation reaction, etc. are mentioned.

It is preferable that the glass transition temperature (Tg) of (meth)acrylic-type resin is the range of 80-120 degreeC. In order to adjust the Tg of the (meth)acrylic resin within the above range, usually, the polymerization ratio of the methacrylic acid ester-based monomer and the acrylic acid ester-based monomer, the carbon chain length of each ester group or the type of functional group it has, or the entire monomer A method of appropriately selecting the polymerization ratio of the polyfunctional monomer to

(meth)acrylic resin may contain a well-known additive as needed. Examples of known additives include lubricants, antiblocking agents, heat stabilizers, antioxidants, antistatic agents, light resistance agents, impact resistance improving agents, surfactants, and the like.

The (meth)acrylic resin may contain the acrylic rubber particle which is an impact modifier from viewpoints, such as film forming property to a film, and the impact resistance of a film. Acrylic rubber particles as used herein are particles containing an elastic polymer mainly composed of acrylic acid ester as an essential component, and those having a single-layer structure substantially composed of only this elastic polymer or having a multi-layer structure containing this elastic polymer as a single layer can be heard As an example of such an elastic polymer, the crosslinked elastic copolymer which has an alkyl acrylate as a main component and copolymerized this with other copolymerizable vinyl monomer and a crosslinkable monomer is mentioned. Examples of the alkyl acrylate used as the main component of the elastic polymer include those having an alkyl group having 1 to 8 carbon atoms, such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, and particularly, having 4 or more carbon atoms. An acrylate having an alkyl group is preferably used. Examples of other vinyl monomers copolymerizable with this alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule, and more specifically, methacrylic acid esters such as methyl methacrylate, styrene, and vinyl cyan compounds such as aromatic vinyl compounds and acrylonitrile. Examples of the crosslinkable monomer include a crosslinkable compound having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, ethylene glycol di(meth)acrylate and butanediol di(meth)acrylate and (meth)acrylates of the same polyhydric alcohol, alkenyl ester of (meth)acrylic acid like allyl (meth)acrylate, divinylbenzene, etc. are mentioned.

In addition, a laminate of a film made of a (meth)acrylic resin containing no rubber particles and a film made of a (meth)acrylic resin containing rubber particles is formed with the first thermoplastic resin film 21 and/or the second thermoplastic resin. It can also be set as the film 22.

Cellulose ester-type resin is resin by which at least one part of the hydroxyl group in a cellulose was acetic acid esterified, a part is acetic acid esterification, and the mixed ester in which one part is esterified with another acid may be sufficient. The cellulose ester-based resin is preferably an acetyl cellulose-based resin. Specific examples of the acetyl cellulose resin include triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate.

The protective film for protecting the polarizing film 10 may be sufficient as the 1st thermoplastic resin film 21 and/or the 2nd thermoplastic resin film 22, and the film which has optical functions, such as retardation film, may be sufficient as it. The film which is not extended|stretched may be sufficient as the 1st thermoplastic resin film 21 and/or the 2nd thermoplastic resin film 22, and the film extended|stretched uniaxially, biaxially, etc. may be sufficient as it. For example, the retardation film to which arbitrary retardation values are provided can be made by extending|stretching (uniaxial stretching or biaxial stretching, etc.) the thermoplastic resin film which consists of the said material, or forming a liquid crystal layer etc. on the said film. The first thermoplastic resin film 21 and/or the second thermoplastic resin film 22 may have a surface treatment layer (coating layer) on the surface opposite to the polarizing film 10 . Specific examples of the surface treatment layer include an antiglare layer, a hard coat layer, an antireflection layer, a light diffusion layer, an antifouling layer, and an antistatic layer.

The thermoplastic resin constituting the first thermoplastic resin film 21 and the thermoplastic resin constituting the second thermoplastic resin film 22 may be the same or different. As embodiment in the polarizing plate which concerns on this invention,

1) The thermoplastic resin constituting the first thermoplastic resin film 21 and the thermoplastic resin constituting the second thermoplastic resin film 22 are the same, and the thermoplastic resin is a polyester-based resin, a polycarbonate-based resin, or a polyolefin-based resin. , (meth) a polarizing plate selected from the group consisting of acrylic resins and cellulose ester-based resins,

2) A polarizing plate in which the first thermoplastic resin film 21 is composed of a polyolefin-based resin or cellulose ester-based resin, and the second thermoplastic resin film 22 is composed of a (meth)acrylic resin

can be heard A suitable example of embodiment of 1) is a polarizing plate in which both the 1st thermoplastic resin film 21 and the 2nd thermoplastic resin film 22 are comprised from (meth)acrylic-type resin.

(3) adhesive layer

The first adhesive layer 15 and the second adhesive layer 25 may be formed of an active energy ray-curable adhesive such as an ultraviolet curable adhesive, a thermosetting adhesive, or a water-based adhesive, but the first adhesive layer 15 and the second adhesive At least one of the layers 25 is formed of an ultraviolet curable adhesive, preferably both adhesive layers are formed of an ultraviolet curable adhesive. When formed of an ultraviolet curable adhesive, the first adhesive layer 15 and the second adhesive layer 25 are cured product layers of the ultraviolet curable adhesive. The first adhesive layer 15 and the second adhesive layer 25 may be formed of the same type of adhesive or different types of adhesive. The adhesive is responsible for bonding the first thermoplastic resin film 21 and the polarizing film 10 and bonding the second thermoplastic resin film 22 and the polarizing film 10 . In addition, an active energy ray-curable adhesive agent is an adhesive agent which hardens by irradiation of active energy rays, such as an ultraviolet-ray, visible light, an electron beam, and an X-ray.

Among the ultraviolet curable adhesives, at least one of the first adhesive layer 15 and the second adhesive layer 25 is formed of an ultraviolet curable adhesive (U) described later. An ultraviolet curable adhesive agent (U) is a cationic polymerization type adhesive agent which contains a cation-curable component (A) and a cationic polymerization initiator (B), and does not contain a sensitizer substantially. In spite of substantially not containing a sensitizer, by forming an adhesive layer with an ultraviolet curable adhesive (U), the first and low transmittance of light at the absorption maximum wavelength in the ultraviolet region of the cationic polymerization initiator (B) Even when the second thermoplastic resins 21 and 22 are used, the adhesive layer is cured satisfactorily, and a polarizing plate having excellent adhesion between the films can be provided. Moreover, since the sensitizer used as a cause of coloring is not included substantially by forming an adhesive bond layer with an ultraviolet curable adhesive agent (U), the polarizing plate in which the problem of coloring was reduced can be provided.

When hardening the adhesive bond layer which consists of an ultraviolet curable adhesive agent (U), the ultraviolet-ray which has an effective wavelength range for hardening an adhesive bond layer is irradiated over a thermoplastic resin film. The effective wavelength range for hardening an adhesive bond layer is a wavelength range containing the absorption maximal wavelength in the ultraviolet range of the cationic polymerization initiator (B) normally contained in an adhesive agent. In the case where both the first and second thermoplastic resins 21 and 22 have the transmittance above zero, the ultraviolet irradiation may be performed on either the thermoplastic resin film side (or both of them). It is a case where both the 1st and 2nd thermoplastic resins 21 and 22 have the said transmittance|permeability exceeding zero, and when there exists a difference in these transmittance|permeability, UV irradiation is normally performed on the side of the thermoplastic resin film with a higher transmittance|permeability. On the other hand, when the transmittance of the second thermoplastic resin film 22 is zero or substantially zero, ultraviolet irradiation is made from the first thermoplastic resin film 21 side.

When the adhesive layer is cured by irradiating ultraviolet rays through the thermoplastic resin film, it is difficult to sufficiently harden the adhesive layer disposed on the opposite side to the UV-irradiated side rather than the UV-irradiated adhesive layer based on the polarizing film 10 . . Therefore, it is useful to use an ultraviolet curable adhesive agent (U) for the adhesive bond layer arrange|positioned at least on the side opposite to the side to which ultraviolet-ray is irradiated. When the transmittance of the second thermoplastic resin film 22 is zero or substantially zero, the adhesive layer disposed on the opposite side to the UV-irradiated side is the second adhesive layer 25 .

Either one of the first adhesive layer 15 and the second adhesive layer 25 may be formed of an adhesive other than the ultraviolet curable adhesive (U). Examples of the adhesive other than the UV-curable adhesive (U) include UV-curable adhesives other than the UV-curable adhesive (U), active energy ray-curable adhesives other than the UV-curable adhesive, thermosetting adhesive, and water-based adhesive.

The thickness of the first adhesive layer 15 and the second adhesive layer 25 after curing is, for example, 0.01 to 20 μm. From the viewpoint of thinning the polarizing plate and adhesive strength, the thickness after curing of the first adhesive layer 15 and the second adhesive layer 25 is preferably 0.1 μm or more, more preferably 0.5 μm or more, and still more preferably Preferably it is 1 micrometer or more, More preferably, it is 15 micrometers or less, More preferably, it is 10 micrometers or less. The thickness of the first adhesive layer 15 and the thickness of the second adhesive layer 25 may be the same or different. When the thickness of an adhesive bond layer is made small too much, it will become easy to produce the bubble mixing to an adhesive bond layer, and the fall of adhesiveness and durability.

Hereinafter, an ultraviolet curable adhesive agent (U) is demonstrated. The ultraviolet curable adhesive (U) contains a cation-curable component (A) and a cationic polymerization initiator (B). A cation-curable component (A) is a component which can raise|generate and harden|cure cationic polymerization by irradiation of an ultraviolet-ray. Adhesive force is expressed by polymerization hardening of a cation-curable component (A).

(3-1) Cationic curable component (A)

The cationically curable component (A) contains an epoxy compound (A1). An epoxy compound means the compound which has 1 or 2 or more epoxy groups in a molecule|numerator. The cationically curable component (A) may contain 1 type or 2 or more types of epoxy compounds (A1).

Examples of the epoxy compound (A1) include an aromatic epoxy compound (A1-1), an aliphatic diglycidyl compound (A1-2), an epoxy group-containing polymer (A1-3), and a monofunctional aliphatic epoxy compound (A1-4). can The epoxy compound (A1) is an aromatic epoxy compound (A1-1), an aliphatic diglycidyl compound (A1-2), an epoxy group-containing polymer (A1-3), and a monofunctional aliphatic epoxy compound (A1-4) from the group consisting of It may include two or more selected epoxy compounds.

In addition, the compound in which X and/or Y in the example of the epoxy group containing polymer (A1-3) mentioned later has "aromatic ring and an epoxy group" is not included in the aromatic epoxy compound (A1-1) here. Similarly, the compound in which X and/or Y in an epoxy group-containing polymer (A1-3) mentioned later has an "epoxy group" is not included in the monofunctional aliphatic epoxy compound (A1-4) here.

The said aromatic epoxy compound (A1-1) is an epoxy compound which has an aromatic ring. The epoxy compound (A1) may include one or more aromatic epoxy compounds (A1-1). Specific examples of the aromatic epoxy compound (A1-1) include monohydric phenols such as phenol, cresol and butylphenol, bisphenol derivatives such as bisphenol A and bisphenol F, or mono- or polyglycidyl ethers of these alkylene oxide adducts freight; Epoxy novolac resin (novolak-type epoxy resin); Mono or polyglycidyl ether products of aromatic compounds having two or more phenolic hydroxyl groups, such as resorcinol, hydroquinone, and catechol; glycidyl ether products of aromatic compounds having two or more alcoholic hydroxyl groups, such as benzenedimethanol, benzenediethanol, and benzenedibutanol; glycidyl esters of polybasic acid aromatic compounds having two or more carboxyl groups, such as phthalic acid, terephthalic acid and trimellitic acid; glycidyl ester of benzoic acid, toluic acid, glycidyl ester of naphthoic acid, etc.; Styrene oxides, such as an epoxide of styrene oxide, alkylated styrene oxide, and vinyl naphthalene, or diepoxy of divinylbenzene, etc. are mentioned.

Especially, from a viewpoint of sclerosis|hardenability and adhesiveness, it is preferable that an aromatic epoxy compound (A1-1) contains a polyfunctional aromatic epoxy compound, and it is more preferable that it contains a trifunctional or more than trifunctional aromatic epoxy compound. Moreover, it is preferable that the epoxy equivalent of an aromatic epoxy compound (A1-1) is 80-500 from a viewpoint of sclerosis|hardenability and adhesiveness.

The epoxy compound (A1) may include one or two or more aliphatic diglycidyl compounds (A1-2). The inclusion of the aliphatic diglycidyl compound (A1-2) is advantageous in terms of reducing the viscosity of the ultraviolet curable adhesive. Moreover, it is advantageous also from a viewpoint of improving the sclerosis|hardenability of an adhesive bond layer, and adhesiveness between films to contain an aliphatic diglycidyl compound (A1-2). As the aliphatic diglycidyl compound (A1-2), the following formula (I):

It is more preferable to include a compound represented by In the formula (I), Z represents a linear or branched alkylene group having 1 to 9 carbon atoms or a divalent alicyclic hydrocarbon group, and the methylene group in the alkylene group is an oxygen atom, -CO-O-, -O-CO- , -SO ₂ -, -SO-, and -CO- may be substituted with a divalent group selected from. Typical examples of the divalent alicyclic hydrocarbon group include a cyclopentylene group and a cyclohexylene group.

In the formula (I), the compound wherein Z is an alkylene group is diglycidyl ether of alkylene glycol, and specific examples thereof include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and 1,3-propane. diol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and the like. Among them, the compound in which Z is an alkylene group in the formula (I) is propylene glycol diglycidyl ether from the viewpoint of reducing the viscosity of the ultraviolet curable adhesive, and improving the curability of the adhesive layer and the adhesion between the films. , a compound in which Z in the formula (I) is a branched alkylene group having 3 to 10 carbon atoms, such as neopentyl glycol diglycidyl ether, is preferable.

The epoxy compound (A1) may include one or two or more epoxy group-containing polymers (A1-3). The inclusion of the epoxy group-containing polymer (A1-3) is advantageous in improving the curability of the adhesive layer and the adhesion between the films. The epoxy group-containing polymer (A1-3) has the following formula (II):

A monomer represented by (II), and the following formula (III):

It is a polymer which has an epoxy group contained in X and/or Y which consists of a structural unit derived from 1 or more types of monomers selected from the group which consists of a monomer (III) represented by. Specifically,

1) a homopolymer formed by polymerizing one type of monomer (II);

2) a copolymer obtained by polymerizing two or more types of monomer (II);

3) a homopolymer formed by polymerizing one type of monomer (III);

4) a copolymer formed by polymerizing two or more types of monomer (III);

5) a copolymer obtained by polymerizing at least one type of monomer (II) and at least one type of monomer (III);

6) a mixture of two or more of these

can be exemplified.

In the polymers of 1) and 2), X of 1 type, or 2 or more types of monomer (II) contains an epoxy group. In the polymers of 3) and 4), Y of 1 type or 2 or more types of monomer (III) contains an epoxy group. In the polymer of 5), X of monomer (II) and/or Y of monomer (III) contains an epoxy group.

X in the formula (II) is a hydrogen atom or an alkyl group having 1 to 7 carbon atoms which may be partially substituted with one or more functional groups selected from the group consisting of an epoxy group, an oxetanyl group, a hydroxyl group and a carboxyl group; of an alkoxy group, an aryl group having 6 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, or an alicyclic hydrocarbon group having 6 to 10 carbon atoms.

Examples of the alkyl group having 1 to 7 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, tert-butyl group, i-butyl group, n-amyl group, i-ah group Myl group, tert-amyl group, n-hexyl group, 2-hexyl group, 3-hexyl group, cyclohexyl group, 4-methylcyclohexyl group, n-heptyl group, 2-heptyl group, 3-heptyl group, i- A heptyl group, a tert-heptyl group, etc. are mentioned. Among them, from the viewpoint of curability of the adhesive layer, etc., when X is an alkyl group substituted with an epoxy group or an alkyl group substituted with an oxetanyl group, this epoxy group or oxetanyl group and a carbon atom (C) to which X is bonded Since it is easy to become a thing with a high storage elastic modulus as a result of reducing the distance between them, it is preferable that carbon number of this alkyl group is C1-C4.

Examples of the alkoxy group having 1 to 7 carbon atoms include a methoxy group, an ethoxy group, n-propyloxy group, i-propyloxy group, n-butyloxy group, sec-butyloxy group, tert-butyloxy group, i-butyloxy group , n-amyloxy group, i-amyloxy group, tert-amyloxy group, n-hexyloxy group, 2-hexyloxy group, 3-hexyloxy group, cyclohexyloxy group, 4-methylcyclohexyloxy group, n-heptyloxy group, 2-heptyloxy group, 3-heptyloxy group, i-heptyloxy group, tert-heptyloxy group, etc. are mentioned. Among them, when X is an alkoxy group substituted with an epoxy group or an alkoxy group substituted with an oxetanyl group from the viewpoint of curability of the adhesive layer, etc., this epoxy group or oxetanyl group and the carbon atom to which X is bonded (C ) decreases, and as a result, it tends to have a high storage elastic modulus, so that the alkoxy group preferably has 1 to 4 carbon atoms.

A phenyl group, a methylphenyl group, a naphthyl group etc. are mentioned as a C6-C12 aryl group. The carbon number is preferably 6 to 10.

A phenyloxy group, a methylphenyloxy group, a naphthyloxy group, etc. are mentioned as a C6-C12 aryloxy group. The carbon number is preferably 6 to 10.

Examples of the alicyclic hydrocarbon group having 6 to 10 carbon atoms include a cyclohexyl group, a methylcyclohexyl group, a norbornyl group, a bicyclopentyl group, a bicyclooctyl group, a trimethylbicycloheptyl group, a tricyclooctyl group, a tricyclodecanyl group, A spirooctyl group, a spirobicyclopentyl group, an adamantyl group, an isobornyl group, etc. are mentioned.

In the above formula (II), when a part of X is substituted with an epoxy group or an oxetanyl group, the monomer (II) is, for example, represented by the following formulas (IIa), (IIb) and (IIc) and monomers.

(In the formula, R ⁴ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and m represents an integer of 1 to 6).

(In the formula, R ⁵ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 1 to 6).

(In the formula, R ⁶ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and s represents an integer of 1 to 6).

R ¹ in the formula (III) represents a hydrogen atom, a methyl group or a halogen atom. Y is an alkyl group having 1 to 7 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alicyclic hydrocarbon group having 6 to 10 carbon atoms which may be substituted with one or more functional groups selected from the group consisting of an epoxy group, an oxetanyl group, a hydroxyl group and a carboxyl group. indicates.

Examples of the halogen atom include fluorine, chlorine, bromine, and iodine. Specific examples of the alkyl group having 1 to 7 carbon atoms, the aryl group having 6 to 12 carbon atoms and the alicyclic hydrocarbon group having 6 to 10 carbon atoms are the same as those of X in the formula (II).

In the above formula (III), when a part of Y is substituted with an epoxy group or an oxetanyl group, the monomer (III) is, for example, represented by the following formulas (IIIa), (IIIb) and (IIIc) and monomers.

(Wherein, R ¹ is the same as in the formula (III), R ⁷ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and t represents an integer of 1 to 6).

(Wherein, R ¹ is the same as in Formula (III), R ⁸ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and p represents an integer of 1 to 6).

(Wherein, R ¹ is the same as in Formula (III), R ⁹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and q represents an integer of 1 to 6).

Epoxy group-containing polymer (A1-3) has a weight average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC) of 5000 to It is preferable that it is 500000, and it is more preferable that it is 6000-100000.

The epoxy compound (A1) may include one or two or more monofunctional aliphatic epoxy compounds (A1-4). Examples of the monofunctional aliphatic epoxy compound (A1-4) include glycidyl ether products of aliphatic alcohols, glycidyl esters of alkyl carboxylic acids, and the like, and specific examples thereof include allyl glycidyl ether, butyl glycidyl ether, sec-butylphenyl glycidyl ether, 2-ethylhexyl glycidyl ether, mixed alkyl glycidyl ether having 12 and 13 carbon atoms, glycidyl ether of alcohol, monoglycidyl ether of aliphatic higher alcohol, glycidyl of higher fatty acid cydyl esters and the like.

The epoxy compound (A1) may contain the cation-curable epoxy compound which does not belong to any of said (A1-1)-(A1-4).

Among them, from the viewpoint of enhancing the adhesiveness of the adhesive layer and the adhesion between the films, the epoxy compound (A1) contains an aliphatic diglycidyl compound (A1-2) and/or an epoxy group-containing polymer (A1-3). It is preferable, and it is preferable to contain an aliphatic diglycidyl compound (A1-2) and an epoxy group containing polymer (A1-3). The total content of the aliphatic diglycidyl compound (A1-2) and the epoxy group-containing polymer (A1-3) in the epoxy compound (A1) is preferably 40 to 100 parts by weight in 100 parts by weight of the epoxy compound (A1). parts, more preferably 50 to 100 parts by weight, and still more preferably 60 to 100 parts by weight.

The cationically curable component (A) contains an oxetane compound (A2). The cation-curable component (A) may contain 1 type or 2 or more types of oxetane compound (A2). In addition, the compound in which X and/or Y in the example of the said epoxy group containing polymer (A1-3) has "oxetanyl group" is not included in the oxetane compound (A2) here.

The oxetane compound (A2) is a compound having an oxetanyl group, and specific examples thereof include 3,7-bis(3-oxetanyl)-5-oxa-nonane, 1,4-bis[(3-ethyl-3). -oxetanylmethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane, 1,3-bis[(3-ethyl-3-oxetanylmethoxy) Methyl] propane, ethylene glycol bis (3-ethyl-3-oxetanyl methyl) ether, triethylene glycol bis (3-ethyl-3-oxetanyl methyl) ether, tetraethylene glycol bis (3-ethyl-3- Oxetanylmethyl)ether, 1,4-bis(3-ethyl-3-oxetanylmethoxy)butane, 1,6-bis(3-ethyl-3-oxetanylmethoxy)hexane, 3-ethyl-3 -[(phenoxy)methyl]oxetane, 3-ethyl-3-(hexyloxymethyl)oxetane, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, 3-ethyl-3-(hydro oxymethyl)oxetane, 3-ethyl-3-(chloromethyl)oxetane, and the like.

A cation-curable component (A) contains 30 to 70 weight% of an epoxy compound (A1) and 30 to 70 weight% of an oxetane compound (A2), when the total amount is 100 weight%. By forming the adhesive layer with the ultraviolet curable adhesive (U) having such a composition, the absorption maximum wavelength in the ultraviolet region of the cationic polymerization initiator (B) even though the ultraviolet curable adhesive (U) does not contain a sensitizer substantially Even when the first and second thermoplastic resins 21 and 22 having low light transmittance are used, the adhesive layer is well cured and a polarizing plate having excellent adhesion between the films can be provided. The content of the epoxy compound (A1) is preferably 40 to 70% by weight, more preferably 45 to 65% by weight, and the content of the oxetane compound (A2) is preferably 30 to 60% by weight, more preferably It is preferably 35 to 55% by weight.

The cation-curable component (A) can contain 1 type(s) or 2 or more types of other cation-curable components other than an epoxy compound (A1) and an oxetane compound (A2). As another cation-curable component, a vinyl ether compound (A3), a cyclic lactone compound (A4), a cyclic acetal compound (A5), a cyclic thioether compound (A6), a spiro ortho ester compound (A7), etc. are mentioned.

Examples of the vinyl ether compound (A3) include aliphatic or alicyclic vinyl ether compounds, and specific examples thereof include n-amyl vinyl ether, i-amyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, 2- vinyl ethers of alkyl or alkenyl alcohol having 5 to 20 carbon atoms, such as ethylhexyl vinyl ether, n-dodecyl vinyl ether, stearyl vinyl ether, and oleyl vinyl ether; hydroxyl group-containing vinyl ethers such as 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, and 4-hydroxybutyl vinyl ether; vinyl ethers of monoalcohols having an aliphatic ring or an aromatic ring, such as cyclohexyl vinyl ether, 2-methylcyclohexyl vinyl ether, cyclohexylmethyl vinyl ether, and benzyl vinyl ether; Glycerol monovinyl ether, 1,4-butanediol divinyl ether, 1,6-hexanediol divinyl ether, neopentyl glycol divinyl ether, pentaerythritol divinyl ether, pentaerythritol tetravinyl ether, trimethylolpropane divinyl ether, Trimethylolpropane trivinyl ether, 1,4-dihydroxycyclohexane monovinyl ether, 1,4-dihydroxycyclohexane divinyl ether, 1,4-dihydroxymethylcyclohexane monovinyl ether, 1,4 - Mono or polyvinyl ethers of polyhydric alcohols, such as dihydroxymethylcyclohexane divinyl ether; polyalkylene glycol mono or divinyl ethers such as diethylene glycol divinyl ether, triethylene glycol divinyl ether, and diethylene glycol monobutyl monovinyl ether; and other vinyl ethers such as glycidyl vinyl ether and ethylene glycol vinyl ether methacrylate.

(3-2) Cationic polymerization initiator (B)

The ultraviolet curable adhesive (U) contains a cationic polymerization initiator (B). Thereby, an adhesive bond layer can be formed by hardening|curing a cationically curable component (A) by cationic polymerization by irradiation of an active energy ray. A cationic polymerization initiator (B) generates a cationic species or a Lewis acid by irradiation of an ultraviolet-ray, and initiates the polymerization reaction of a cationically curable component (A). Since the cationic polymerization initiator (B) acts catalytically with light, it is excellent in storage stability and workability even when mixed with the cationically curable component (A). As a compound which produces a cationic species and a Lewis acid by irradiation of an active energy ray which can be used as a cationic polymerization initiator (B), For example, an aromatic diazonium salt; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; An iron-arene complex etc. are mentioned.

As the aromatic diazonium salt, for example,

benzenediazonium hexafluoroantimonate,

benzenediazonium hexafluorophosphate,

Benzenediazonium Hexafluoroborate

can be

As the aromatic iodonium salt, for example,

diphenyliodonium tetrakis(pentafluorophenyl)borate;

diphenyliodonium hexafluorophosphate,

diphenyliodonium hexafluoroantimonate,

Di(4-nonylphenyl)iodonium hexafluorophosphate

can be heard

As the aromatic sulfonium salt, for example,

triphenylsulfonium hexafluorophosphate,

triphenylsulfonium hexafluoroantimonate,

triphenylsulfonium tetrakis(pentafluorophenyl)borate;

4,4'-bis[diphenylsulfonio]diphenylsulfide bishexafluorophosphate,

4,4'-bis[di(β-hydroxyethoxy)phenylsulfonio]diphenylsulfide bishexafluoroantimonate;

4,4'-bis[di(β-hydroxyethoxy)phenylsulfonio]diphenylsulfide bishexafluorophosphate;

7-[di(p-toluyl)sulfonio]-2-isopropylthioxanthone hexafluoroantimonate;

7-[di(p-toluyl)sulfonio]-2-isopropylthioxanthone tetrakis(pentafluorophenyl)borate;

4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate,

4-(p-tert-butylphenylcarbonyl)-4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate;

4-(p-tert-butylphenylcarbonyl)-4'-di(p-toluyl)sulfonio-diphenylsulfide tetrakis(pentafluorophenyl)borate

can be heard

As the iron-arene complex, for example,

xylene-cyclopentadienyl iron (II) hexafluoroantimonate;

cumene-cyclopentadienyl iron (II) hexafluorophosphate,

Xylene-cyclopentadienyl iron(II) tris(trifluoromethylsulfonyl)methanide

can be heard

The ultraviolet curable adhesive (U) may contain one or more cationic polymerization initiators (B). Among the above, aromatic sulfonium salts are particularly preferable because they have ultraviolet absorption properties even in a wavelength region of around 300 nm, so they are excellent in curability and can provide an adhesive layer having good adhesion between films.

Content of a cationic polymerization initiator (B) is 0.1-10 weight part normally with respect to 100 weight part of cation-curable components (A), Preferably it is 0.5-8 weight part, More preferably, it is 1-6 weight part . By containing 0.1 weight part or more of a cationic polymerization initiator (B), a cation-curable component (A) can fully be hardened|cured. On the other hand, when the amount is too large, the hygroscopicity of the cured product increases due to an increase in the ionic substance in the cured product, and there is a possibility that the durability performance of the polarizing plate is reduced. It is usually 10 parts by weight based on 100 parts by weight.

(3-3) sensitizer (C)

The ultraviolet curable adhesive (U) does not contain a sensitizer (C) substantially. Specifically, content of the sensitizer (C) in an ultraviolet curable adhesive agent (U) is 0-0.01 weight part with respect to 100 weight part of cation-curable components (A). According to the present invention using the ultraviolet curable adhesive (U), although substantially not containing a sensitizer, the first and Even when the second thermoplastic resins 21 and 22 are used, the adhesive layer is cured satisfactorily, and a polarizing plate having excellent adhesion between the films can be provided. Moreover, according to this invention using an ultraviolet curable adhesive agent (U), since the sensitizer used as a cause of coloring is not included substantially, the polarizing plate by which the problem of coloring was reduced can be provided.

Moreover, as a sensitizer (C), an anthracene type compound is used suitably. Specific examples of the anthracene-based compound include, for example,

9,10-dimethoxyanthracene,

9,10-diethoxyanthracene,

9,10-dipropoxyanthracene,

9,10-diisopropoxyanthracene,

9,10-dibutoxyanthracene,

9,10-dipentyloxyanthracene,

9,10-dihexyloxyanthracene,

9,10-bis(2-methoxyethoxy)anthracene;

9,10-bis(2-ethoxyethoxy)anthracene;

9,10-bis(2-butoxyethoxy)anthracene;

9,10-bis(3-butoxypropoxy)anthracene;

2-methyl or 2-ethyl-9,10-dimethoxyanthracene,

2-methyl or 2-ethyl-9,10-diethoxyanthracene,

2-methyl or 2-ethyl-9,10-dipropoxyanthracene,

2-methyl or 2-ethyl-9,10-diisopropoxyanthracene,

2-methyl or 2-ethyl-9,10-dibutoxyanthracene,

2-methyl or 2-ethyl-9,10-dipentyloxyanthracene,

2-methyl or 2-ethyl-9,10-dihexyloxyanthracene

can be heard

(3-4) Other ingredients

The ultraviolet curable adhesive (U) may contain components other than those described above. Examples of other components include thermal cationic polymerization initiators, polyols, ion trapping agents, antioxidants, light stabilizers, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, leveling agents, dyes, organic solvents, etc. can be heard

(4) Polarizing film

The polarizing film 10 may be a uniaxially stretched polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented. As a polyvinyl alcohol-type resin which comprises a polyvinyl alcohol-type resin film, what saponified polyvinyl acetate-type resin can be used. As polyvinyl acetate-type resin, the copolymer of vinyl acetate and other monomer copolymerizable to this other than polyvinyl acetate which is a homopolymer of vinyl acetate is illustrated. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin may be in the range of 80.0 to 100.0 mol%, but preferably in the range of 90.0 to 100.0 mol%, and more preferably in the range of 98.0 to 100.0 mol%. If the saponification degree is less than 80.0 mol%, the water resistance and/or heat-and-moisture resistance of the polarizing plate may decrease.

The degree of saponification refers to the ratio of the acetic acid group (acetoxy group: -OCOCH 3 ) contained in the polyvinyl acetate-based resin, which is a raw material of the polyvinyl alcohol-based resin, changed to a hydroxyl group by the saponification process in unit ratio (mol%), as shown below. ceremony:

Saponification degree (mol%) = 100 x (number of hydroxyl groups) / (number of hydroxyl groups + number of acetate groups)

is defined as Saponification degree can be calculated|required based on JISK6726 (1994).

The average degree of polymerization of the polyvinyl alcohol-based resin is preferably 100 to 10000, more preferably 1500 to 8000, and still more preferably 2000 to 5000. The average degree of polymerization of polyvinyl alcohol-type resin can also be calculated|required based on JISK6726 (1994). When the average degree of polymerization is less than 100, it is difficult to obtain desirable polarization performance, and when it exceeds 10000, solubility in a solvent deteriorates, and formation of a polyvinyl alcohol-based resin film may become difficult.

The dichroic dye contained in the polarizing film 10 (adsorption orientation) may be iodine or a dichroic organic dye. Specific examples of the dichroic organic dye include Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet. B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Direct Sky Blue , Direct First Orange S, and First Black. A dichroic dye may be used individually by 1 type, and may use 2 or more types together. The dichroic dye is preferably iodine.

The polarizing film 10 is a process of uniaxially stretching a polyvinyl alcohol-type resin film; The step of adsorbing a dichroic dye by dyeing a polyvinyl alcohol-type resin film with a dichroic dye; A step of crosslinking the polyvinyl alcohol-based resin film to which the dichroic dye is adsorbed; and washing with water after crosslinking treatment.

The polyvinyl alcohol-based resin film is formed by forming the above-described polyvinyl alcohol-based resin into a film. The film forming method is not particularly limited, and a known method such as a melt extrusion method and a solvent casting method can be employed.

Uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before, simultaneously with, or after dyeing the dichroic dye. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during the crosslinking treatment. Moreover, you may perform uniaxial stretching in these several steps.

In uniaxial stretching, you may extend|stretch uniaxially between rolls with different circumferential speeds, and you may extend|stretch uniaxially using a hot roll. 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 solution. The draw ratio is usually about 3 to 8 times.

As a method of dyeing a polyvinyl alcohol-type resin film with a dichroic dye, the method of immersing a polyvinyl alcohol-type resin film in the aqueous solution (dyeing solution) containing a dichroic dye is employ|adopted, for example. It is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water (swelling process) before a dyeing process.

When using an iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing normally iodine and potassium iodide is employ|adopted. The content of iodine in this aqueous dyeing solution is usually 0.01 to 1 part by weight per 100 parts by weight of water. Moreover, content of potassium iodide is 0.5-20 weight part normally per 100 weight part of water. The temperature of the dyeing aqueous solution is about 20-40 degreeC normally.

On the other hand, when using a dichroic organic dye as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the dyeing aqueous solution containing a water-soluble dichroic organic dye is usually adopted. Content of the dichroic organic dye in dyeing aqueous solution is 1x10 ^{-4 -} 10 weight part normally per 100 weight part of water, Preferably it is 1x10 ^{-3 -} 1 weight part. This aqueous dyeing solution may contain inorganic salts, such as sodium sulfate, as a dyeing aid. The temperature of the dyeing aqueous solution is usually about 20 to 80°C.

The crosslinking treatment after dyeing with a dichroic dye can be performed by immersing the dyed polyvinyl alcohol-type resin film in the crosslinking agent containing aqueous solution. A suitable example of the crosslinking agent is boric acid, but other crosslinking agents such as boron compounds such as borax, glyoxal, and glutaraldehyde may also be used. Only 1 type may be used for a crosslinking agent, and may use 2 or more types together.

The amount of the crosslinking agent in the crosslinking agent-containing aqueous solution is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When using an iodine as a dichroic dye, it is preferable that this crosslinking agent containing aqueous solution contains potassium iodide. The amount of potassium iodide in the aqueous solution containing the crosslinking agent is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. The temperature of the aqueous solution containing a crosslinking agent is 50 degreeC or more normally, Preferably it is 50-85 degreeC.

The polyvinyl alcohol-based resin film after the crosslinking treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing the crosslinked polyvinyl alcohol-based resin film in water. The temperature of the water in a water washing process is about 1-40 degreeC normally.

After washing with water, it can dry-process and obtain the polarizing film 10. The drying treatment may be drying by a hot air dryer, drying by contact with a hot roll, drying by a far-infrared heater, or the like. The temperature of a drying process is about 30-100 degreeC normally, and 50-90 degreeC is preferable.

The thickness of the polarizing film 10 is 2-50 micrometers, for example. From a viewpoint of suppressing the crack of the polarizing film 10, the thickness becomes like this. Preferably it is 5 micrometers or more, More preferably, it is 10 micrometers or more, More preferably, it is 15 micrometers or more. From a viewpoint of thin film formation of a polarizing plate, etc., the thickness of the polarizing film 10 becomes like this. Preferably it is 40 micrometers or less, More preferably, it is 30 micrometers or less.

(5) Preparation of polarizing plate

Using the adhesive described above, the first thermoplastic resin film 21 is adhered to one side of the polarizing film 10, and the second thermoplastic resin film 22 is adhered to the other side of the polarizing film 10 as shown in FIG. A polarizing plate can be obtained.

For example, in the polarizing plate shown in FIG. 1, an adhesive coating layer is formed on the adhesive surface of the polarizing film 10 and/or the first and second thermoplastic resin films 21 and 22, and the polarizing film ( 10) After bonding the first and second thermoplastic resin films 21 and 22, if the adhesive is an ultraviolet curable adhesive, it can be produced by curing the coating layer of the uncured adhesive by irradiation with ultraviolet rays. Various coating methods, such as a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, can be used for formation of the application layer of an adhesive agent, for example. In addition, while continuously supplying the polarizing film 10 and the first and second thermoplastic resin films 21 and 22 so that the adhesive surfaces of both are on the inside, a method of casting the adhesive in between may be adopted. there is. The bonding of the 1st thermoplastic resin film 21 to the polarizing film 10 and the 2nd thermoplastic resin film 22 may be simultaneous, and may be sequential.

Prior to adhesion of the polarizing film 10 and the first and second thermoplastic resin films 21 and 22 , to the adhesive surface of the thermoplastic resin film and/or the adhesive surface of the polarizing film 10, saponification treatment, corona treatment, plasma Easy adhesion treatment such as treatment, priming treatment, anchor coating treatment, and flame treatment may be applied.

Ultraviolet rays irradiated to cure ultraviolet curable adhesives such as ultraviolet curable adhesives (U) are usually wavelengths including the absorption maximum wavelength in the ultraviolet region of polymerization initiators such as cationic polymerization initiators (B) contained in ultraviolet curable adhesives. It is an ultraviolet light having a luminescence distribution in the region. Examples of the light source capable of irradiating such ultraviolet rays include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, and a metal halide lamp.

Although ultraviolet irradiation intensity in particular is not restrict|limited, It is preferable that the irradiation intensity of the wavelength range effective for activation of polymerization initiators, such as a cationic polymerization initiator (B), is 0.1-3000 mW/cm<2>. If it is less than 0.1 mW/cm2, the reaction time becomes too long, and if it exceeds 3000 mW/cm2, the heat radiated from the lamp and heat generated during polymerization of the adhesive may cause yellowing of the adhesive or deterioration of the polarizing film 10 There is this.

Although the irradiation time of the ultraviolet rays is not particularly limited, it is preferably set so that the amount of accumulated light expressed as a product of the irradiation intensity and the irradiation time is 10 to 5000 mJ/cm 2 . When it is less than 10 mJ/cm 2 , the generation of active species derived from polymerization initiators such as cationic polymerization initiator (B) is not sufficient, and hardening of the resulting adhesive layer may become insufficient, while the amount of the integrated light is 5000 mJ/cm 2 When it exceeds, irradiation time becomes very long, and it becomes disadvantageous to productivity improvement.

Example

Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by these examples. Hereinafter, parts and % indicating the amount to be used or the content are based on weight unless otherwise specified.

In the following examples, the light transmittance (transmittance of light at the absorption maximum wavelength of the cationic polymerization initiator (B) in the ultraviolet region) of the thermoplastic resin film was measured using a spectrophotometer.

(Production Example 1: Preparation of UV-curable adhesive)

After mixing the cation-curable component (A) and the cationic polymerization initiator (B) shown in Table 1, it defoamed and prepared the adhesive agent 1-3 which are ultraviolet curable adhesives. The unit of the compounding quantity of each component in Table 1 is "part".

The details of each component shown in Table 1 are as follows.

[1] Epoxy compound A1-a: Mitsubishi Chemical Co., Ltd. special novolak-type epoxy resin "157S20";

[2] Epoxy compound A1-b: neopentyl glycol diglycidyl ether [the compound of Z=-CH2C(CH3)2CH2- in the above formula (I)];

[3] Epoxy compound A1-c: Epoxy group-containing polymer having a weight average molecular weight of 15000 obtained by radical polymerization of a monomer composition comprising 25 parts of glycidyl methacrylate (GMA) and 75 parts of methyl methacrylate (MMA) (GMA-MMA) copolymer),

[4] Epoxy compound A1-d: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane;

[5] Oxetane compound A2-a: Toagosei Co., Ltd. oxetane compound "OXT-221" (chemical name: 3-ethyl-3-[(3-ethyloxetan-3-yl)methoxymethyl] oxetane),

[6] Cationic polymerization initiator (B): "CPI-110P" manufactured by San Apro Co., Ltd. (chemical name: triarylsulfonium hexafluorophosphate, active ingredient: 100%, absorption maximum wavelength is 303 nm).

(Production Example 2: Preparation of polarizing film)

A polyvinyl alcohol film manufactured by Kuraray ("PE6000" manufactured by Kuraray Co., Ltd.) was continuously conveyed and immersed in a swelling bath made of pure water at 20°C for a residence time of 31 seconds (swelling step). Then, the film taken out from the swelling bath was immersed in the 30 degreeC dyeing bath containing iodine whose potassium iodide/water is 2/100 (weight ratio) with residence time 122 second (dyeing process). Next, the film taken out from the dyeing bath was immersed in a crosslinking bath at 56° C. of 12/4.1/100 (weight ratio) of potassium iodide/boric acid/water with a residence time of 70 seconds, and then potassium iodide/boric acid/water was mixed with 9/ It was immersed in a crosslinking bath of 2.9/100 (weight ratio) at 40°C with a residence time of 13 seconds (crosslinking step). In the dyeing step and the crosslinking step, longitudinal uniaxial stretching was performed by stretching between rolls in a bath. The total draw ratio based on the raw film was set to 5.5 times. Next, the film taken out from the crosslinking bath is immersed in a washing bath made of pure water at 5° C. for a residence time of 3 seconds (washing step), then introduced into a drying furnace at 80° C. with a residence time of 190 seconds and dried (drying step), polarized light got a film. The thickness of the polarizing film was 25 µm.

<Example 1: Preparation of Polarizing Plate 1>

Triacetyl cellulose resin film (retardation film "WVBZ4E4" manufactured by Fujifilm Co., Ltd., 38 μm in thickness, wavelength 303 nm, light transmittance 2%) and (meth)acrylic resin film (“WVBZ4E4” manufactured by Sumitomo Chemical Co., Ltd.) Technology S001", 80 m in thickness, containing a UV absorber, and 0% light transmittance at a wavelength of 303 nm) was prepared. On one side of the triacetylcellulose-based resin film, using an adhesive coating device, coating the adhesive 3 so that the thickness after curing becomes 2.5 μm to form an adhesive layer, and on one side of the (meth)acrylic resin film, Using an adhesive coating device, the adhesive 1 is coated so that the thickness after curing becomes 2.5 μm to form an adhesive layer, and through these adhesive layers, a triacetyl cellulose-based resin film is applied to one side of the polarizing film obtained in Production Example 2 was bonded, and a (meth)acrylic resin film was bonded to the other surface. Then, from the triacetyl cellulose-based resin film side, UVA is irradiated so that the accumulated light amount of UVA in the UV wavelength region becomes about 350 mJ/cm 2 (measurement instrument: measured by UV Power Puck II manufactured by Fusion UV) to cure the adhesive layer Polarizing plate 1 was obtained. The layer structure of the polarizing plate 1 is a triacetyl cellulose-based resin film (first thermoplastic resin film) / first adhesive layer consisting of adhesive 3 / polarizing film / second adhesive layer consisting of adhesive 1 / (meth) acrylic resin film (product 2 thermoplastic resin film).

<Comparative Example 1: Preparation of Polarizing Plate 2>

A polarizing plate 2 was manufactured in the same manner as in Example 1 except that the adhesive 2 was used as an adhesive for forming the second adhesive layer. Ultraviolet rays were irradiated from the triacetyl cellulose-based resin film side. The layer structure of the polarizing plate 2 is a triacetyl cellulose-based resin film (first thermoplastic resin film) / first adhesive layer consisting of adhesive 3 / polarizing film / second adhesive layer consisting of adhesive 2 / (meth) acrylic resin film (product 2 thermoplastic resin film).

<Reference Example 1: Preparation of Polarizing Plate 3>

As the first thermoplastic resin film, a cyclic polyolefin-based resin film (retardation film “ZEONOR” manufactured by Nippon Zeon Co., Ltd., 50 μm thick, wavelength 303 nm light transmittance 90%) was used instead of a triacetyl cellulose resin film Except for that, in the same manner as in Example 1, a polarizing plate 3 was produced. Ultraviolet rays were irradiated from the cyclic polyolefin resin film side. The layer structure of the polarizing plate 3 is a cyclic polyolefin resin film (first thermoplastic resin film) / first adhesive layer consisting of adhesive 3 / polarizing film / second adhesive layer consisting of adhesive 1 / (meth)acrylic resin film (second thermoplastic resin film).

<Reference Example 2: Preparation of Polarizing Plate 4>

As the first thermoplastic resin film, a cyclic polyolefin-based resin film (retardation film “ZEONOR” manufactured by Nippon Zeon Co., Ltd., 50 μm thick, wavelength 303 nm light transmittance 90%) was used instead of a triacetyl cellulose resin film Except for that, in the same manner as in Comparative Example 1, a polarizing plate 4 was produced. Ultraviolet rays were irradiated from the cyclic polyolefin resin film side. The layer structure of the polarizing plate 4 is a cyclic polyolefin resin film (first thermoplastic resin film) / first adhesive layer consisting of adhesive 3 / polarizing film / second adhesive layer consisting of adhesive 2 / (meth) acrylic resin film (second thermoplastic resin film).

(Evaluation of adhesion)

The following method evaluated the adhesiveness between the (meth)acrylic-type resin film (2nd thermoplastic resin film) and a polarizing film. After cutting out a length of 200 mm × width of 25 mm from the polarizing plate, an adhesive layer was formed on the (meth)acrylic resin film side, and a test piece for measuring the peel strength between the (meth)acrylic resin film and the polarizing film was obtained. The test piece was attached to a glass plate using the pressure-sensitive adhesive layer, a cutter blade was put between the polarizing film and the (meth)acrylic resin film, and 30 mm was peeled off from the tip in the longitudinal direction, and the peeled portion was held by the grip part of the testing machine. For the test piece in this state, a 90 degree peel test was performed at a grip moving speed of 50 mm/min in an atmosphere of a temperature of 23° C. and a relative humidity of 55%, and the average peel force over a length of 170 mm excluding 30 mm of the grip part was obtained. It calculated|required and made this into the peeling strength between a (meth)acrylic-type resin film and a polarizing film. In addition, the measurement timing of peeling strength is 24 hours after producing a polarizing plate. A result is shown in Table 2. "Peeling impossibility" in Table 2 means that the (meth)acrylic-type resin film and the polarizing film were not able to peel on the said conditions. "Uncured" means that hardening of the adhesive bond layer was insufficient. The non-cured thing was evaluated as "uncured" when the tackiness was recognized by the presence or absence of tackiness (sticky feeling) when the adhesive layer after peeling off the (meth)acrylic resin film was touched with a finger.

(Production Example 3: Preparation of UV-curable adhesive)

After mixing the cationic curable component (A) and the cationic polymerization initiator (B) shown in Table 3, it defoamed and prepared the adhesive agent 4-6 which are ultraviolet curable adhesives. The unit of the compounding quantity of each component in Table 3 is "part".

The details of each component shown in Table 3 are as follows.

[1] Epoxy compound A1-b: neopentyl glycol diglycidyl ether [compound of Z = -CH2C(CH3)2CH2- in the above formula (I)];

[2] Epoxy compound A1-c: Epoxy group-containing polymer having a weight average molecular weight of 15000 obtained by radical polymerization of a monomer composition comprising 25 parts of glycidyl methacrylate (GMA) and 75 parts of methyl methacrylate (MMA) (GMA-MMA) copolymer),

[3] Oxetane compound A2-a: Toagosei Co., Ltd. oxetane compound "OXT-221" (chemical name: 3-ethyl-3-[(3-ethyloxetan-3-yl)methoxymethyl] oxetane),

[4] Cationic polymerization initiator (B): "CPI-110P" manufactured by San Apro Co., Ltd. (chemical name: triarylsulfonium hexafluorophosphate, active ingredient: 100%, absorption maximum wavelength is 303 nm).

<Example 2: Preparation of Polarizing Plate 5>

A polarizing plate 5 was produced in the same manner as in Example 1 except that the adhesive 4 was used as an adhesive for forming the second adhesive layer. Ultraviolet rays were irradiated from the triacetyl cellulose-based resin film side. The layer structure of the polarizing plate 5 is a triacetyl cellulose-based resin film (first thermoplastic resin film) / first adhesive layer consisting of adhesive 3 / polarizing film / second adhesive layer consisting of adhesive 4 / (meth) acrylic resin film (product 2 thermoplastic resin film).

<Example 3: Preparation of polarizing plate 6>

A polarizing plate 6 was manufactured in the same manner as in Example 1 except that the adhesive 5 was used as the adhesive for forming the second adhesive layer. Ultraviolet rays were irradiated from the triacetyl cellulose-based resin film side. The layer structure of the polarizing plate 6 is a triacetyl cellulose-based resin film (first thermoplastic resin film) / first adhesive layer consisting of adhesive 3 / polarizing film / second adhesive layer consisting of adhesive 5 / (meth) acrylic resin film (product 2 thermoplastic resin film).

<Example 4: Preparation of polarizing plate 7>

A polarizing plate 7 was manufactured in the same manner as in Example 1 except that the adhesive 6 was used as the adhesive for forming the second adhesive layer. Ultraviolet rays were irradiated from the triacetyl cellulose-based resin film side. The layer structure of the polarizing plate 7 is a triacetyl cellulose-based resin film (first thermoplastic resin film) / first adhesive layer consisting of adhesive 3 / polarizing film / second adhesive layer consisting of adhesive 6 / (meth) acrylic resin film (product 2 thermoplastic resin film).

The above method evaluated the adhesiveness of the polarizing plates 5-7. A result is shown in Table 4.

10: polarizing film, 15: 1st adhesive bond layer, 21: 1st thermoplastic resin film, 22: 2nd thermoplastic resin film, 25: 2nd adhesive bond layer.

Claims (5)

a first thermoplastic resin film, a first adhesive layer, a polarizing film, a second adhesive layer, and a second thermoplastic resin film in this order;
At least one of the first adhesive layer and the second adhesive layer is a cured product layer of an ultraviolet curable adhesive,
The ultraviolet curable adhesive comprises a cation-curable component (A) and a cationic polymerization initiator (B),
The cationically curable component (A) contains 30 to 70 wt% of an epoxy compound (A1) and 30 to 70 wt% of an oxetane compound (A2) when the total amount is 100 wt%,
The epoxy compound (A1) includes an aliphatic diglycidyl compound (A1-2),
The content of the sensitizer (C) in the ultraviolet curable adhesive is 0 to 0.01 parts by weight with respect to 100 parts by weight of the cation-curable component (A),
The first thermoplastic resin film has a light transmittance of 0.5 to 5% at an absorption maximum wavelength in the ultraviolet region of the cationic polymerization initiator,
The said 2nd thermoplastic resin film is a polarizing plate whose transmittance|permeability of the light in the absorption maximum wavelength in the ultraviolet region of the said cationic polymerization initiator is 0 to 5%. The cation-curable component (A) according to claim 1, wherein, when the total amount thereof is 100 wt%, 40 to 70 wt% of the epoxy compound (A1) and 30 to 60 wt% of the oxetane compound (A2) A polarizing plate comprising a. The method according to claim 1 or 2, wherein the first thermoplastic resin film and the second thermoplastic resin film are made of a polyester-based resin, a polycarbonate-based resin, a polyolefin-based resin, a (meth)acrylic resin, and a cellulose ester-based resin. A polarizing plate comprising a thermoplastic resin selected from the group consisting of. The polarizing plate according to claim 3, wherein the first thermoplastic resin film is composed of a polyolefin-based resin or a cellulose ester-based resin, and the second thermoplastic resin film is composed of a (meth)acrylic resin. The polarizing plate according to claim 1, wherein at least one of the first thermoplastic resin film and the second thermoplastic resin film is a retardation film.

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