JP6776785B2 - Active energy ray-curable adhesive composition, polarizing plate adhesive composition, polarizing plate adhesive, and polarizing plate using the same. - Google Patents

Description

The present invention relates to an active energy ray-curable adhesive composition, a polarizing plate adhesive composition, a polarizing plate adhesive, and a polarizing plate using the same. More specifically, the present invention is used for a liquid crystal display device or the like. It relates to an active energy ray-curable adhesive composition suitable for bonding a polarizing element constituting a polarizing plate and a protective film.

Liquid crystal display devices are widely used as image display devices for liquid crystal televisions, computer displays, mobile phones, digital cameras, and the like. Such a liquid crystal display device has a configuration in which polarizing plates are laminated on both sides of a glass substrate in which a liquid crystal is enclosed, and various optical functional films such as a retardation plate are laminated on the polarizing plates as needed.

Conventionally, a polarizing plate has been used as a configuration in which a protective film is bonded to at least one surface, preferably both surfaces of a polarizing element made of a polyvinyl alcohol-based film. Here, as the polarizer, a polyvinyl alcohol-based resin having a high degree of cross-linking (hereinafter, polyvinyl alcohol is abbreviated as "PVA") is used to form a film, and the PVA-based film is bicolorized with iodine or the like. A uniaxially stretched PVA-based film in which the material is dispersed and adsorbed and preferably further crosslinked with a cross-linking agent such as boric acid is widely used. Since such a polarizer is a uniaxially stretched PVA-based film, it easily shrinks under high humidity. Therefore, a protective film is attached to the polarizer for the purpose of supplementing moisture resistance and strength.

As such a protective film, thermoplastic resins such as cellulose resin, polycarbonate resin, cyclic polyolefin resin, (meth) acrylic resin, and polyester resin are transparent, mechanical strength, thermal stability, moisture-blocking property, isotropic property, and the like. Although it has been used because of its excellent properties, a protective film made of a triacetyl cellulose (TAC) resin has been widely used.

These protective films are bonded to the polarizer by an adhesive, and the adhesive is similar to a PVA-based resin aqueous solution, particularly a polarizer, from the viewpoint of adhesiveness to a polarizer having a hydrophilic surface. A PVA-based resin aqueous solution mainly composed of a PVA-based resin having a high degree of saponification is preferably used.

By the way, in recent years, there has been a demand for thinner polarizing plates, and instead of the triacetyl cellulose (TAC) film, which has been most commonly used as a protective film, an acrylic film or a cyclic olefin resin (COP) has been required. ) Film has come to be used. However, these protective films that replace the triacetyl cellulose (TAC) film have problems that it is difficult to firmly bond them to the polarizer with conventional PVA-based adhesives and that the obtained polarizing plate has a poor appearance. was there. This is because the acrylic film and the cyclic olefin resin (COP) film are more hydrophobic than the triacetyl cellulose (TAC) film, and the water permeability is low, so that the water cannot be sufficiently dried. Therefore, as an alternative to PVA-based adhesives, various adhesives suitable for bonding protective films such as acrylic films and cyclic olefin resin (COP) films have been developed.

For example, Patent Document 1 proposes a photocurable adhesive composition containing an oxetane compound and an epoxy compound in a specific ratio, and an aliphatic epoxy compound or an aromatic epoxy compound is used as the epoxy compound. Has been done. Since the photocurable adhesive composition is cured by cationic polymerization by irradiation with active energy rays, even when a resin film having low moisture permeability is used as a protective film, the adhesive strength is sufficient and the appearance is poor. It is described that it is possible to provide a polarizing plate in which a protective film is bonded to one side or both sides of a polarizing element without causing the problem of the above.

Japanese Unexamined Patent Publication No. 2010-209126

However, the adhesive composition of Patent Document 1 is not sufficiently satisfactory in terms of adhesive strength and durability depending on the diversification of the usage environment in recent years, the type of protective film, and the like, and further improvement is desired. It was.

Therefore, in the present invention, under such a background, it is an adhesive having excellent adhesive strength, is suitable for bonding various protective films for polarizing plates and a polarizer, and has durability such as thermal shock resistance. An excellent active energy ray-curable adhesive composition, a polarizing plate adhesive composition, a polarizing plate adhesive, and a polarizing plate using the same are provided.

However, as a result of diligent research in view of such circumstances, the present inventors have, in the active energy ray-curable adhesive composition, together with the specific oxetane compound (A), instead of the conventionally used epoxy compound. By using a specific triazine skeleton-containing epoxy compound (B) as an essential component at a specific content weight ratio, an adhesive layer having an excellent balance between durability and adhesiveness can be obtained due to the polarity of the triazine skeleton. I found that I could get it.

<Gist of the invention>
The present invention is an active energy ray-curable adhesive composition containing an oxetane compound (A) and a triazine skeleton-containing epoxy compound (B) , wherein the oxetane compound (A) and the triazine skeleton-containing epoxy compound ( The content weight ratio of B) is (A) / (B) = 5/1 to 1/1, and the epoxy compound (A) is an epoxy compound having two oxetanyl groups in the molecule and contains a triazine skeleton. Epoxy compounds (B) are tris (2,3-epoxypropyl) -isocyanurate, tris (3,4-epoxybutyl) -isocyanurate, tris (4,5-epoxypentyl) -isocyanurate, tris- (5). , 6-Epoxyhexyl) -Isocyanurate, Tris (6,7-Epoxyheptyl) -Isocyanurate and Tris (7,8-Epoxyoctyl) -Isocyanurate, at least one active energy ray-curable adhesive. The composition is the first gist.

Further, the second gist of the present invention is an adhesive composition for a polarizing plate using the above-mentioned active energy ray-curable adhesive composition. The third gist is an adhesive for a polarizing plate, which is a cured product of the adhesive composition for a polarizing plate. The fourth gist is a polarizing plate in which a polarizing element and a protective film are bonded to each other via the polarizing plate adhesive.

The active energy ray-curable adhesive composition of the present invention contains a specific oxetane compound (A) and a specific triazine skeleton-containing epoxy compound (B) in a specific content weight ratio . Therefore, various protective films for polarizing plates and a polarizer can be sufficiently adhered to each other, and a polarizing plate having excellent durability can be obtained.

Furthermore, since the oxetane compound (A) and a triazine skeleton-containing epoxy compound containing a weight ratio of (B) is A / B = 5 / 1~1 / 1, together with the adhesive strength and durability is further improved, the curability It will be improved.

When the epoxy compound (C) other than the triazine skeleton-containing epoxy compound (B) is contained, the adhesive strength and durability are improved, and the coatability is improved.

When the content weight ratio of the triazine skeleton-containing epoxy compound (B) to the epoxy compound (C) is B / C = 1/9 to 9/1, the adhesive strength and durability are further improved.

The adhesive composition for a polarizing plate using the above-mentioned active energy ray-curable adhesive composition does not require a drying step, so that a polarizing plate having high production efficiency of the polarizing plate and excellent adhesive strength and durability can be obtained. Obtainable.

Hereinafter, the present invention will be described in detail, and these are examples of desirable embodiments.

The active energy ray-curable adhesive composition of the present invention (hereinafter, may be abbreviated as an adhesive composition) contains an oxetane compound (A) and a triazine skeleton-containing epoxy compound (B). Is. Hereinafter, each component of the adhesive composition will be described in order.

In the present invention, (meth) acrylic means acrylic or methacrylic, (meth) acryloyl means acryloyl or methacryloyl, and (meth) acrylate means acrylate or methacrylate.

<Oxetane compound (A)>
Oxetane compound (A) used in the present invention, the Ru compound der to two chromatic oxetanyl groups in the molecule.
Is an oxetane compound, for example, 3-ethyl-3-hydroxymethyl oxetane, 3-ethyl-3 - [(2-ethylhexyl oxy methyl) oxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3 -Oxetanyl groups in molecules such as ethyl-3- (cyclohexyloxymethyl) oxetane, 3-ethyl-3- (oxylanylmethoxy) oxetane, and (meth) acrylate (3-ethyloxetane-3-yl) methyl. One oxetane compound, 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, Examples thereof include oxetane compounds having two or more oxetane group in the molecule such as 4,4'-bis [(3-ethyl-3-oxetanyl) methoxymethyl] biphenyl, etc., but in the present invention, the oxetane group is contained in the molecule. It always contains two oxetane compounds . These oxetane compounds (A) can be used alone or in combination of two or more.

Among them, 3-ethyl-3-hydroxymethyloxetane and 1,4-bis [(3-ethyl-3-oxetanyl) are easy to obtain, dilute (low viscosity), and have excellent compatibility. ) Ethylmethyl] benzene, 3-ethyl-3-[(2-ethylhexyloxymethyl)] oxetane, 3-ethyl-3- (oxylanylmethoxy) oxetane, (meth) acrylic acid (3-ethyloxetane-3-3) Il) methyl, 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane and the like are preferably used.

Further, from the viewpoint of coatability and adhesiveness, a liquid having a molecular weight of 500 or less at room temperature is preferable, and from the viewpoint of excellent curability and durability, an oxetane compound containing two or more oxetane groups in the molecule or the like. Oxetane compounds containing one oxetaneyl group and one (meth) acryloyl group or one epoxy group in the molecule are preferred, in particular 3-ethyl-3 {[(3-ethyloxetane-3-yl). ) Methyl} oxetane, 3-ethyl-3- (oxylanylmethoxy) oxetane, and (meth) acrylic acid (3-ethyloxetane-3-yl) methyl are preferably used.

Specific examples of the oxetane compound (A) include commercially available products such as Aron Oxetane OXT-101, Aron Oxetane OXT-121, Aron Oxetane OXT-411, Aron Oxetane OXT-212, Aron Oxetane OXT-213, and Aron Oxetane OXT. -221 (both manufactured by Toagosei Co., Ltd.) can be used. In particular, Aron Oxetane OXT-101 and Aron Oxetane OXT-221 are preferable.

<Triazine skeleton-containing epoxy compound (B)>
The triazine skeleton-containing epoxy compound (B) contains one or more epoxy groups and a triazine skeleton in the molecule, and specifically , tris (2,3-epoxypropyl) -isocyanurate, tris ( 3,4-Epoxybutyl) -isocyanurate, tris (4,5-epoxypentyl) -isocyanurate, tris- (5,6-epoxyhexyl) -isocyanurate, tris (6,7-epoxyheptyl) -isocyanurate , tris (7,8-epoxy-octyl) - Ru isocyanurate der. These can be used alone or in combination of two or more.

The triazine skeleton-containing epoxy compound (B) preferably has an epoxy equivalent of 120 g / eq or more, particularly preferably 120 to 300 g / eq, and further preferably 120 to 250 g / eq, from the viewpoint of adhesiveness and durability. Is.

As the triazine skeleton-containing epoxy compound (B), specifically, commercially available TEPIC series (TEPIC-G, TEPIC-S, TEPIC-SS, TEPIC-HP, TEPIC-L, TEPIC-" manufactured by Nissan Chemical Industries, Ltd. PAS, TEPIC-VL, TEPIC-UC, TEPIC-FL, etc.) can be used. Of these, liquid epoxy compounds TEPIC-PAS, TEPIC-VL, TEPIC-UC, and TEPIC-FL are preferable from the viewpoint of compatibility.

The content weight ratio of the oxetane compound (A) and the triazine skeleton-containing epoxy compound (B) is ( A) / (B) = 5/1 to 1/1. When the ratio of the triazine skeleton-containing epoxy compound (B) is too high, or decreases the adhesive composition thickened coating properties, it decreases the curing rate. Further, the ratio of the triazine skeleton-containing epoxy compound (B) is too low, or the adhesive strength is lowered, it reduced durability.

<Epoxy compound (C)>
In the present invention, in addition to the oxetane compound (A) and the triazine skeleton-containing epoxy compound (B), an epoxy compound (C) other than the triazine skeleton-containing epoxy compound (B) for the purpose of further improving the adhesiveness (hereinafter referred to as , Epoxy compound (C) is abbreviated) can be used.

As the epoxy compound (C), various epoxy compounds other than the triazine skeleton-containing epoxy compound (B), that is, epoxy compounds having no triazine skeleton in the compounds can be used. Examples of the epoxy compound (C) include an aliphatic epoxy compound, an epoxy compound having at least one aromatic ring in the molecule (aromatic epoxy compound), and an alicyclic skeleton having at least one in the molecule. Examples thereof include an epoxy compound (alicyclic epoxy compound). These can be used alone or in combination of two or more.

Examples of the aliphatic epoxy compound include one epoxy group in a molecule such as butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, glycidol, alcohol glycidyl ether having 11 to 15 carbon atoms, and lauryl alcohol glycidyl ether. Poliable aliphatic epoxy compounds, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, ethylene Glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, polybutadiene diglycidyl ether, sorbitol polyglycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl Examples thereof include bifunctional or higher aliphatic epoxy compounds having two or more epoxy groups in a molecule such as ether. These aliphatic epoxy compounds can be used alone or in combination of two or more.

Examples of the aromatic epoxy compound include an epoxy group in the molecule of phenylglycidyl ether, p-tert-butylphenylglycidyl ether, p-sec-butylphenylglycidyl ether, dibromophenylglycidyl ether, resorcin diglycidyl ether and the like. Aromatic epoxy compound with one, phthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, hydroquinone diglycidyl ether, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bromobisphenol A diglycidyl ether, phenol novolac type epoxy resin , Cresol novolac type epoxy resin, novolac type epoxy resin, biphenyl type epoxy resin and the like, aromatic epoxy compounds having two or more epoxy groups in the molecule, and the like. These aromatic epoxy compounds can be used alone or in combination of two or more.

Examples of the alicyclic epoxy compound include dicyclopentadiene oxide, limonendioxide, 4-vinylcyclohexendioxide, 3', 4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and ε-caprolactone modification. Epoxy with hydrogenated aromatic rings such as 3', 4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexylmethyl) adipate, hydrided bisphenol A diglycidyl ether Examples thereof include compounds, cyclohexanedimethanol diglycidyl ether and the like. These alicyclic epoxy compounds can be used alone or in combination of two or more.

Among the above epoxy compounds (C), from the viewpoint of adhesiveness, it is preferable to use at least one of an aliphatic epoxy compound and an aromatic epoxy compound, and further, it is preferable to use an aliphatic epoxy compound. In particular, it is preferable to use an aliphatic epoxy compound having two or more functions.

The content weight ratio of the triazine skeleton-containing epoxy compound (B) to the epoxy compound (C) is preferably (B) / (C) = 1/9 to 9/1, and further (B) / ( C) = 1.5 / 8.5-8.5 / 1.5, particularly preferably (B) / (C) = 2/8 to 8/2. If the content ratio of the epoxy compound (C) is too small, the adhesive strength tends to decrease, and if the content ratio of the epoxy compound (C) is too large, the durability tends to decrease.

<Unsaturated compound (D) having an ethylenically unsaturated group>
In the present invention, in addition to the above (A) to (C), an unsaturated compound having at least one ethylenically unsaturated group in the molecule as a radical polymerization component (hereinafter, may be abbreviated as an ethylenically unsaturated compound). Yes) (D) can be used. By using the ethylenically unsaturated compound (D), the curing rate can be adjusted and the curability is improved. When the ethylenically unsaturated compound (D) is used as a radical polymerization component, it is preferable to use a photoradical polymerization initiator (F) described later.

As the ethylenically unsaturated compound (D), for example, a (meth) acrylic compound having at least one (meth) acryloyl group in the molecule can be mentioned.

Examples of the (meth) acrylic compound include (meth) acrylates, (meth) acrylamides, (meth) acrylic acid, (meth) acryloyl morpholine, and (meth) acrylic aldehyde.

Examples of the (meth) acrylates having one (meth) acryloyl group in the molecule include the following compounds.

Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, Alkyl (meth) acrylates such as isooctyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate;
Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate;
Cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, 1,4-cyclohexanedimethylolmono (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) Alicyclic (meth) acrylates such as acrylates;
Benzyl (meth) acrylate, p-cumylphenol alkylene oxide adduct (meth) acrylate, o-phenylphenol alkylene oxide adduct (meth) acrylate, phenol alkylene oxide adduct (meth) acrylate and nonylphenol alkylene oxide adduct addition (Meta) acrylates having an aromatic ring, such as (meth) acrylates of an adduct (here, examples of alkylene oxides include ethylene oxide and propylene oxide);
Alkoxyalkyl (meth) acrylates such as 2-methoxyethyl (meth) acrylates, ethoxymethyl (meth) acrylates, and (meth) acrylates of alkylene oxide adducts of 2-ethylhexyl alcohols;
Dihydric alcohol mono (meth) acrylates such as ethylene glycol mono (meth) acrylate, propylene glycol mono (meth) acrylate, pentanediol mono (meth) acrylate, and hexanediol mono (meth) acrylate;
Diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, dipropylene glycol mono (meth) acrylate, tripropylene glycol Mono (meth) acrylates of polyalkylene glycol, such as mono (meth) acrylate of polypropylene glycol;
Glycidyl (meth) acrylate;
Tetrahydrofurfuryl (meth) acrylate;
Tetrahydrofurfuryl (meth) acrylates, such as caprolactone-modified tetrahydrofurfuryl (meth) acrylates;
3,4-Epoxycyclohexylmethyl (meth) acrylate;
N, N-dimethylaminoethyl (meth) acrylate;
2- (Meta) acryloyloxyethyl isocyanate and the like.

Further, examples of the (meth) acrylates having two or more (meth) acryloyl groups in the molecule include the following compounds.

Alicyclics such as tricyclodecanedimethylol di (meth) acrylate, 1,4-cyclohexanedimethylol di (meth) acrylate, norbornane dimethylol di (meth) acrylate, and di (meth) acrylate of hydrogenated bisphenol A. Di (meth) acrylates with rings;
Di (meth) acrylate of bisphenol A ethylene oxide adduct, di (meth) acrylate of bisphenol A alkylene oxide adduct containing di (meth) acrylate of bisphenol A propylene oxide adduct, and di (meth) acrylate of bisphenol A diglycidyl ether. Di (meth) acrylates having an aromatic ring, such as meta) acrylates;
Di (meth) acrylates of alkylene glycol such as ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, pentanediol di (meth) acrylate, and hexanediol di (meth) acrylate;
Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate , And di (meth) acrylates of polyalkylene glycol, such as polypropylene glycol di (meth) acrylate;
Di or tri (meth) acrylates of glycerins, such as di or tri (meth) acrylates of glycerin, and di or tri (meth) acrylates of diglycerin;
Di or tri (meth) acrylates of glycerin alkylene oxide adducts;
Di (meth) acrylates of bisphenol alkylene oxide adducts, such as di (meth) acrylates of bisphenol A alkylene oxide adducts and di (meth) acrylates of bisphenol F alkylene oxide adducts;
Trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, dimethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) Polypoly (meth) acrylates such as acrylates and dipentaerythritol hexa (meth) acrylates;
Poly (meth) acrylates of alkylene oxide adducts of these polyols;
Di or tri (meth) acrylates of isocyanuric acid alkylene oxide adduct;
1,3,5-tri (meth) acryloylhexahydro-s-triazine and the like.

Examples of (meth) acrylamides include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-methylol (meth) acrylamide, and N- (3-N, N-). Examples thereof include dimethylaminopropyl) (meth) acrylamide, methylenebis (meth) acrylamide, and ethylenebis (meth) acrylamide.

In addition, oligomers such as urethane (meth) acrylate, polyester (meth) acrylate and epoxy (meth) acrylate can also be used as the (meth) acrylic compound.

Furthermore, compounds having an ethylenically unsaturated bond other than the (meth) acryloyl group can also be used as the (meth) acrylic compound, and specific examples thereof include allyl (meth) acrylate and N, N-diallyl (meth). Examples include acrylamide.

In addition to the above (meth) acrylic compounds, the ethylenically unsaturated compound (D) includes vinyl compounds such as N-vinyl-2-pyrrolidone, divinyl adipate, and divinyl sebacate; triallyl isothia. Allyl compounds such as nurate, triallylamine, tetraallylpyromeritate, N, N, N', N'-tetraallyl-1,4-diaminobutane, tetraallylammonium salt, and allylamine; such as maleic acid and itaconic acid. , Unsaturated carboxylic acid and the like can also be used.

As the ethylenically unsaturated compound (D), it is preferable to use a (meth) acrylic compound having one (meth) acryloyl group in the molecule from the viewpoint of low curing shrinkage and excellent adhesive strength. Is preferably (meth) acrylates having one (meth) acryloyl group in the molecule. Among the (meth) acrylates, hydroxyalkyl (meth) acrylates and alicyclic (meth) acrylates are preferably used from the viewpoint of reactivity with the epoxy group, and in particular, hydroxyalkyl (meth) acrylates. Is preferable, and in particular, hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferably used.

The content of the ethylenically unsaturated compound (D) is preferably 2 to 100 parts by weight, more preferably 2 to 100 parts by weight, based on 100 parts by weight of the total of the oxetane compound (A) and the triazine skeleton-containing epoxy compound (B). Is 5 to 50 parts by weight, more preferably 10 to 30 parts by weight. If the content of the ethylenically unsaturated compound (D) is too large, the curing shrinkage tends to be large and the adhesive strength tends to decrease. Further, if the content of the ethylenically unsaturated compound (D) is too small, the curing rate tends to decrease.

<Photocationic polymerization initiator (E)>
In the present invention, it is preferable that the adhesive composition further contains the photocationic polymerization initiator (E). By using the photocationic polymerization initiator (E), the adhesive composition can be cured at room temperature, and the protective film can be adhered well. The photocationic polymerization initiator (E) is a compound that produces a cationic species or Lewis acid by irradiation with active energy rays, and is, for example, an onium salt such as an aromatic diazonium salt, an aromatic iodonium salt, or an aromatic sulfonium salt. , Iron-allene complex and the like.

Examples of the aromatic diazonium salt include benzenediazonium / hexafluoroantimonate, benzenediazonium / hexafluorophosphate, benzenediazonium / hexafluoroborate and the like. These can be used alone or in combination of two or more.

Examples of the aromatic iodonium salt include diphenyliodonium / tetrakis (pentafluorophenyl) borate, diphenyliodonium / hexafluorophosphate, diphenyliodonium / hexafluoroantimonate, di (4-nonylphenyl) iodonium / hexafluorophosphate and the like. can give. These can be used alone or in combination of two or more.

Examples of the aromatic sulfonium salt include triphenylsulfonium / hexafluorophosphate, triphenylsulfonium / hexafluoroantimonate, triphenylsulfonium / tetrakis (pentafluorophenyl) borate, and diphenyl [4- (phenylthio) phenyl] sulfonium. Hexafluorophosphate, 4,4'-bis [diphenylsulfonio] diphenylsulfide bishexafluorophosphate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluoroantimonate, 4,4'-Bis [di (β-hydroxyethoxy) phenylsulfonium] diphenylsulfide bishexafluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [Di (p-Truyl) Sulfonio] -2-Isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate, 4- (p-tert-butyl) Phenylcarbonyl) -4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis (pentafluorophenyl) ) Volate etc. can be mentioned. These can be used alone or in combination of two or more.

Examples of the iron-allene complex include xylene-cyclopentadienyl iron (II) -hexafluoroantimonate, cumene-cyclopentadienyl iron (II) -hexafluorophosphate, and xylene-cyclopentadienyl iron (II). ) -Tris (trifluoromethylsulfonyl) metanide and the like. These can be used alone or in combination of two or more.

Of these, it is preferable to use an aromatic iodonium salt or an aromatic sulfonium salt because it reacts with high sensitivity to a long wavelength light source.

The content of the photocationic polymerization initiator (E) is the total amount of the oxetane compound (A) and the triazine skeleton-containing epoxy compound (B) (including the epoxy compound (C) when the epoxy compound (C) is contained). It is preferably 0.5 to 20 parts by weight, particularly 1.0 to 15 parts by weight, and more preferably 1.5 to 10 parts by weight with respect to 100 parts by weight. If the content of the photocationic polymerization initiator (E) is too large, the solubility tends to decrease or the durability tends to decrease. Further, if the content of the photocationic polymerization initiator (E) is too small, the curing tends to be insufficient, and the mechanical strength and the adhesive strength tend to decrease.

<Photoradical polymerization initiator (F)>
In the present invention, a photoradical polymerization initiator (F) can also be used. Examples of the photoradical polymerization initiator (F) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, and 4- (2-hydroxyethoxy) phenyl- ( 2-Hydroxy-2-propyl) ketone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4) -Acephenones such as morpholinophenyl) butanone, 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone oligomer; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin Benzoyls such as isobutyl ether; benzophenone, methyl o-benzoyl benzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenylsulfide, 3,3', 4,4'-tetra (t-butylperoxy) Carbonyl) benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxo-2-propenyloxy) ethyl] benzenemethanamineium bromide, (4-benzoyl) Benzoyls such as benzyl) trimethylammonium chloride; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino) -2-Hydroxy) -3,4-dimethyl-9H-thioxanthone-9-onemethochloride and other thioxanthones; 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,6-dimethoxybenzoyl) Acryphosphon oxides such as −2,4,4-trimethyl-pentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphin oxide; These photoradical polymerization initiators (F) can be used alone or in combination of two or more.

In addition, as these auxiliary agents, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethyl benzoic acid, 4-dimethylaminobenzoic acid Ethyl, 4-dimethylaminobenzoic acid (n-butoxy) ethyl, 4-dimethylaminobenzoate isoamyl, 4-dimethylaminobenzoate 2-ethylhexyl, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanson Etc. can be used together.

Among these photoradical polymerization initiators (F), it is preferable to use acylphosphine oxides, and in particular, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl)-. 2,4,4-trimethyl-pentylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide are preferable, and further 2,4,6-trimethylbenzoyl-phenylphosphine oxide and bis It is preferable to use (2,4,6-trimethylbenzoyl) -phenylphosphine oxide.

When the photoradical polymerization initiator (F) is contained, the content is preferably 20 parts by weight or less, particularly 0.1 to 20 parts by weight, based on 100 parts by weight of the ethylenically unsaturated compound (D). Parts, more preferably 0.5 to 10 parts by weight. If the content of the photoradical polymerization initiator (F) is too large, the solubility of the photoradical polymerization initiator tends to decrease and the durability of the adhesive layer tends to decrease. On the other hand, if the content of the photoradical polymerization initiator (F) is too small, the curing tends to be insufficient, and the adhesive strength and mechanical strength of the adhesive layer tend to decrease.

When the photoradical polymerization initiator (F) is used in combination with the photocationic polymerization initiator (E), the content weight ratio of the two is (E) / (F) = 20/1 from the viewpoint of compatibility and reactivity. It is preferably ~ 1/20, more preferably (E) / (F) = 15/1 to 1/10, and particularly preferably (E) / (F) = 10/1 to 1/5.

In particular, in terms of curing efficiency (which can be efficiently cured with a small amount of active energy rays), a preferable combination of the photocationic polymerization initiator (E) and the photoradical polymerization initiator (F) is a photocation. When an aromatic sulfonium salt or an aromatic iodonium salt is used as the polymerization initiator (E), it is a combination in which acylphosphine oxides are used as the photoradical polymerization initiator (F).

In the present invention, in addition to the above components, as long as the effects of the present invention are not impaired, photosensitizers, polyols, silane coupling agents, antistatic agents, other adhesives, acrylic resins, urethane resins, etc. Adhesive agents such as rosin, rosin ester, hydrogenated rosin ester, phenol resin, aromatic-modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, styrene resin, xylene resin, plasticizer, colorant , Fillers, antistatic agents, UV absorbers, functional pigments and other additives, and compounds that cause color development or discoloration by UV or irradiation can be blended. The blending amount of these additives is appropriately set for each additive, but for example, it is preferably 30% by weight or less, and particularly preferably 20% by weight or less of the entire adhesive composition.
In addition to the above additives, a small amount of impurities and the like contained in the raw materials for producing the constituent components of the adhesive composition may be contained.

By using the photosensitizer, the reactivity can be improved, and the mechanical strength and the adhesive strength of the cured product can be improved. Examples of the photosensitizer include anthracene derivatives such as 9,10-dibutoxyanthracene; benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4- Benzophenone derivatives such as dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis (diethylamino) benzophenone; anthracene derivatives such as 2-chloroanthraquinone and 2-methylanthraquinone. Carbonyl compounds such as; organic sulfur compounds such as thioxanthone derivatives such as 2-chlorothioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthene-9-one, etc .; persulfides, redox compounds, azo and diazo compounds, Examples include halogen compounds and photoreducing dyes. These can be used alone or in combination of two or more. Of these, it is preferable to use an anthracene derivative and a thioxanthone derivative.
The photosensitizer is preferably contained in the range of 0.01 to 20 parts by weight when the total amount of the photocationic polymerization initiator (E) and the photoradical polymerization initiator (F) is 100 parts by weight. .. If the content of the photosensitizer is too large, the composition and the obtained adhesive layer tend to be colored, and if it is too small, the reactivity tends to decrease and the sensitizing effect tends not to be obtained.

The silane coupling agent is usually an organosilicon compound containing at least one reactive functional group and one or more silicon atom-bonded alkoxy groups in the structure, and can improve the adhesiveness between the adhesive layer and the protective film. it can.

Examples of the reactive functional group of the silane coupling agent include an epoxy group, a (meth) acryloyl group, a mercapto group, a vinyl group, a hydroxyl group, a carboxyl group, an amino group, an amide group, an isocyanate group and the like. It preferably contains a cationically polymerizable functional group such as an epoxy group, a vinyl group and a radical group. The silane coupling agent may have an organic functional group other than the reactive functional group and the alkoxy group, for example, an alkyl group, a phenyl group and the like.

Specific examples of the silane coupling agent include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glyci. Epoxy group-containing silane coupling agents such as sidoxypropyltriethoxysilane, 3- (meth) acryloxipropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3- (meth) acryloxipropylmethyldiethoxysilane, (Meta) acryloyl group-containing silane coupling agent such as 3- (meth) acryloxypropyltriethoxysilane, vinyl group-containing silane coupling agent such as vinyltrimethoxysilane and vinyltriethoxysilane, N-2- (aminoethyl) ) -3-Aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxy Amino group-containing silane coupling agent such as silane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane , 3-Mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane and other mercapto group-containing silane coupling agents, tris- (trimethoxysilylpropyl) isocyanurate and other isocyanurate group-containing silane coupling agents, 3-isocyanate Examples thereof include isocyanate group-containing silane coupling agents such as propyltriethoxysilane. These can be used alone or in combination of two or more. Among them, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) from the viewpoint of adhesive strength. ) Acryloxipropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane are preferably used.

Further, as the silane coupling agent, the above-mentioned monomer type silane compound may be used, or an oligomer type silane compound which is partially hydrolyzed and polycondensed may be used.

The content of the silane coupling agent is usually 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the adhesive composition.

The adhesive composition of the present invention can be obtained by blending and mixing each of the above components in a predetermined ratio.

In this way, the active energy ray-curable adhesive composition of the present invention is obtained. The adhesive composition of the present invention functions as an adhesive by being cured by irradiation with active energy rays, and can be suitably used as an adhesive for a polarizing plate for adhering a polarizer and a protective film. It is a thing.

<Polarizer>
The polarizing plate of the present invention is obtained by bonding a polarizing element and a protective film via a polarizing plate adhesive. Specifically, the polarizing plate of the present invention is used on at least one surface, preferably both sides of the polarizing element. Protective films are bonded together using an adhesive, and usually, a liquid polarizing plate adhesive composition is uniformly applied to the polarizer surface, the protective film surface, or both surfaces, and then both are bonded. A polarizing plate is formed by combining, crimping, and irradiating with active energy rays.

The above-mentioned polarizer is usually an aqueous solution of iodine-potassium iodide using a film made of a polyvinyl alcohol-based resin having an average degree of polymerization of 1,500 to 10,000 and a saponification degree of 85 to 100 mol% as a raw film. Alternatively, a uniaxially stretched film dyed with a dichroic dye (usually a stretch ratio of 2 to 10 times, preferably about 3 to 7 times) is used.

The polyvinyl alcohol-based resin is usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate, but a small amount of unsaturated carboxylic acids (including salts, esters, amides, nitriles, etc.), olefins, vinyl ethers, etc. , Unsaturated sulfonate, and other components copolymerizable with vinyl acetate may be contained. Further, examples thereof include so-called polyvinyl acetal resins such as polyvinyl butyral resin and polyvinyl formal resin and polyvinyl alcohol derivatives obtained by reacting polyvinyl alcohol with aldehydes in the presence of acid.

As the protective film for the polarizing plate, in addition to the conventional TAC film, an acrylic film, a polyethylene film, a polypropylene film, a cycloolefin film and the like can be used, and the pressure-sensitive adhesive composition of the present invention is a TAC film. It is suitably used for any protective film selected from films, acrylic films, cycloolefin films, polyethylene terephthalate (PET) films and the like.

When the adhesive composition of the present invention is applied onto a polarizer or a protective film, for example, a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, etc. A rod coater or the like can be used, or coating can be performed by a dipping method.

At the time of bonding and crimping, for example, a roll laminator or the like can be used, and the pressure is usually selected from the range of 0.1 to 10 MPa.

As the active energy rays, in addition to far ultraviolet rays, ultraviolet rays, near ultraviolet rays, rays such as infrared rays, electromagnetic waves such as X-rays and γ-rays, electron beams, proton rays, neutron rays and the like can be used. Curing by ultraviolet irradiation is advantageous because of its availability and price.

As the light source for irradiating the ultraviolet rays, a high-pressure mercury lamp, an electrodeless lamp, an ultra-high pressure mercury lamp carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp, a black light, an LED lamp and the like are used.
The above-mentioned ultraviolet irradiation is usually carried out under the condition of ^{2 to} 3000 mJ / cm ² , preferably 10 to 2000 mJ / cm ² .

Especially in the case of the high-pressure mercury lamp, for example, usually 5~3000mJ / cm ^2, preferably at the conditions of 50~2000mJ / cm ^2.
Further, in the case of the electrodeless lamp, for example, it is usually carried out under the condition of ^{2 to} 2000 mJ / cm ² , preferably 10 to 1000 mJ / cm ² .

The irradiation time varies depending on the type of light source, the distance between the light source and the coated surface, the coating thickness, and other conditions, but is usually several seconds to several tens of seconds, and in some cases, a fraction of a second. On the other hand, in the case of the above-mentioned electron beam irradiation, for example, it is preferable to use an electron beam having an energy in the range of 50 to 1000 keV and set the irradiation amount to 2 to 50 Mrad.

The irradiation direction of the active energy rays (ultraviolet rays, electron beams, etc.) can be any suitable direction, but it is preferable to irradiate from the transparent protective film side in terms of preventing deterioration of the polarizer.

The thickness of the adhesive layer in the polarizing plate of the present invention obtained as described above is usually 0.01 to 10 μm, preferably 0.01 to 5 μm, particularly preferably 0.01 to 2 μm, and further preferably 0.01 to 1 μm. Is. If the thickness is too thin, the cohesive force of the adhesive force itself cannot be obtained, and the adhesive strength tends not to be obtained. If the thickness is too thick, the processability of the polarizing plate tends to decrease due to cracking during punching.

The adhesive composition of the present invention becomes an adhesive having excellent adhesive strength at the initial stage and over time, and can be used for various purposes, but is particularly suitable for bonding various protective films for polarizing plates and a polarizer. It shows good adhesiveness. In addition, the durability of the adhesive layer is also excellent.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the example, the terms "part" and "%" mean the weight standard.

Prior to Examples and Comparative Examples, each component of the adhesive composition shown below was prepared.

[Oxetane compound (A)]
(A-1) 3-Ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane (oxetane compound having two oxetane group in the molecule: Aron oxetane OXT-221 manufactured by Toagosei Co., Ltd. )

[Triazine skeleton-containing epoxy compound (B)]
(B-1) Tris (2,3-epoxypropyl) -isocyanurate (manufactured by Nissan Chemical Industries, Ltd., TEPIC-VL, epoxy equivalent 125-145 g / eq)

[Epoxy compound (C)]
(C-1) 1,6-Hexanediol diglycidyl ether (aliphatic epoxy compound: manufactured by Nagase ChemteX Corporation, EX-212)
(C-2) Bisphenol A type epoxy resin (aromatic epoxy compound: manufactured by Mitsubishi Chemical Corporation, JER828)

[Unsaturated compound (D) having an ethylenically unsaturated group]
(D-1) 4-Hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., 4HBA)

[Photocationic polymerization initiator (E)]
(E-1) Diphenyl [4- (Phenylthio) phenyl] Sulfonium hexafluorophosphate (aromatic sulfonium salt: manufactured by San-Apro, CPI-100P)

[Photoradical polymerization initiator (F)]
(F-1) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (acylphosphine oxides: IRGACURE TPO manufactured by BASF)

[Examples 1 to 4, Comparative Examples 1 to 2]
<Preparation of adhesive composition>
An adhesive composition was prepared by blending each of the above-mentioned compounding components in the ratio shown in Table 1 below and mixing them.

<Making a polarizer>
First, a 60 μm PVA film was stretched 1.5 times while being immersed in a water tank having a water temperature of 30 ° C. Next, it was stretched 1.3 times while being immersed in a dyeing tank (30 ° C.) composed of 0.2 g / L of iodine and 15 g / L of potassium iodide for 240 seconds. Further, it was immersed in a boric acid treatment tank (50 ° C.) having a composition of 50 g / L of boric acid and 30 g / L of potassium iodide, and at the same time, boric acid treatment was carried out for 5 minutes while uniaxially stretching 3.08 times. Then, it was dried at 90 degreeC to produce a polarizer having a total draw ratio of 6 times. The water content of the polarizer was 1%.

<Preparation of polarizing plate test piece>
TAC film with a size of 200 mm x 150 mm and a thickness of 60 μm (manufactured by Fuji Film Co., Ltd., trade name "Fujitac") and cyclic olefin resin (COP) film with a size of 200 mm x 150 mm and a thickness of 50 μm (manufactured by Nippon Zeon Co., Ltd., trade name) Each film of "ZEONOR") was coated with the adhesive composition obtained above with a bar coater so as to have a film thickness of 3 μm to obtain a film with an adhesive composition. Then, each film with an adhesive composition layer was laminated on both sides of the above-mentioned polarizing element having a size of 180 mm × 120 mm, and bonded at a nip pressure of 2 MPa using a roll machine to obtain a laminated film.

Then, from the COP film side of the laminated film, ultraviolet irradiation was performed with an ultraviolet irradiation device equipped with a high-pressure mercury lamp at a peak illuminance of 130 mW / cm ² and an integrated exposure amount of 300 mJ / cm ² (wavelength 365 nm). The composition was cured to prepare a polarizing plate test piece.
Using the polarizing plate test piece obtained above, the performance was evaluated as follows.

<Performance evaluation>
[Curability]
The interface between the polarizer and the TAC film was peeled off with a cutter knife, and the tackiness of the peeled portion was confirmed (touched by a finger).
(Evaluation criteria)
○… There was a tack.
× ... There was no tack.

[Adhesive strength]
The degree of adhesion (adhesive strength) between the TAC film and the polarizing element, and the COP film and the polarizing element when the polarizing plate test piece is cut into 120 mm × 25 mm and stressed in the 90 ° direction is measured by the measuring device: Autograph. Was measured. Then, based on the above measured values, evaluation was performed according to the following criteria.
(Evaluation criteria)
○… All were firmly adhered.
△… All were weakly adhered.
×… None of them were glued.

〔water resistant〕
The polarizing plate test piece was cut into 50 mm × 50 mm, immersed in warm water at 60 ° C., and the appearance of the polarizing plate test piece after 24 hours was observed and evaluated according to the following criteria.
(Evaluation criteria)
○… There was no peeling from the end of the test piece.
Δ: There was peeling within a range of less than 5 mm from the end of the test piece.
X: There was peeling in a range of 5 mm or more from the end of the test piece.

〔durability〕
A thermal shock test was carried out in which the test piece was cut into 100 mm × 100 mm, left at −40 ° C. for 30 minutes, and then left at 85 ° C. for 30 minutes, repeating a cycle of 100 times. After the test, it was evaluated according to the following criteria.
(Evaluation methods)
○… No appearance defects were confirmed.
×: Poor appearance (cracks occurred in the polarizer layer) was confirmed.

The results, the adhesive composition of the specific oxetane compound (A) and a specific triazine skeleton-containing epoxy compound (B) Ru specific chromatic weight ratio der containing Examples 1-4, have good curability In addition to being able to bond the polarizer and the protective film with high adhesive strength, excellent results were also obtained in terms of water resistance and durability. From this, it was suitable for practical use as an adhesive composition for a polarizing plate having an excellent balance.

On the other hand, Comparative Examples 1 and 2 which do not contain the triazine skeleton-containing epoxy compound (B) as the epoxy compound together with the oxetane compound (A) but contain only the aliphatic epoxy compound and the aromatic epoxy compound. In the adhesive composition of No. 1, good results were obtained in terms of curability and water resistance, but inferior results were obtained in terms of adhesive strength or durability. From this, it can be said that it cannot be put into practical use as an adhesive composition for a polarizing plate. Therefore, it was found that the adhesive composition of the present invention is very excellent particularly in the use of an adhesive for polarizing plates.

The adhesive composition of the present invention and the adhesive composition for a polarizing plate composed of the above-mentioned adhesive composition have excellent adhesiveness between a polarizing element and a protective film, and various protective films for a polarizing plate and a polarizing element. Suitable for bonding with. Further, the durability of the polarizing plate, particularly the thermal shock resistance, is also excellent. In addition to the above-mentioned adhesive applications for polarizing plates, the adhesive composition of the present invention can be used for, for example, bonding various optical films or sheets, or bonding electronic parts, precision instruments, packaging materials, display materials, and the like. It can also be used for.

Claims (6)

An active energy ray-curable adhesive composition containing an oxetane compound (A) and a triazine skeleton-containing epoxy compound (B) .
The content weight ratio of the oxetane compound (A) and the triazine skeleton-containing epoxy compound (B) is (A) / (B) = 5/1 to 1/1.
The oxetane compound (A) is an oxetane compound having two oxetanyl groups in the molecule.
The triazine skeleton-containing epoxy compound (B) is tris (2,3-epoxypropyl) -isocyanurate, tris (3,4-epoxybutyl) -isocyanurate, tris (4,5-epoxypentyl) -isocyanurate, tris. -(5,6-epoxyhexyl) -isocyanurate, tris (6,7-epoxyheptyl) -isocyanurate and tris (7,8-epoxyoctyl) -isocyanurate. Active energy ray-curable adhesive composition. At least an aliphatic epoxy compound and an aromatic epoxy compound containing an epoxy compound (C) other than the triazine skeleton-containing epoxy compound (B) and the epoxy compound (C) has two or more epoxy groups in the molecule. Meanwhile claim 1 Symbol placement active energy ray-curable adhesive composition, characterized in der Rukoto. The active energy ray according to claim 2 , wherein the content weight ratio of the triazine skeleton-containing epoxy compound (B) and the epoxy compound (C) is (B) / (C) = 1/9 to 9/1. Curable adhesive composition. An adhesive composition for a polarizing plate, which comprises using the active energy ray-curable adhesive composition according to any one of claims 1 to 3 . An adhesive for a polarizing plate, which comprises a cured product of the adhesive composition for a polarizing plate according to claim 4 . A polarizing plate characterized in that a polarizing element and a protective film are bonded to each other via the polarizing plate adhesive according to claim 5 .