WO2018147247A1 - Actinic-ray-curable adhesive composition, adhesive composition for polarizer, adhesive for polarizer, and polarizer obtained using same - Google Patents

Abstract

Provided is an actinic-ray-curable adhesive composition which has excellent adhesive force, is suitable for use in laminating any of various protective films for polarizers to a polarizing element, and is excellent in terms of curability and durability including thermal shock resistance. The actinic-ray-curable adhesive composition comprises an oxcetane compound (A), an epoxy compound (B), an ethylenically unsaturated compound (C), and a photopolymerization initiator (D), wherein the epoxy compound (B) comprises an aliphatic epoxy compound (B1) and is contained in an amount of 40-80 wt% with respect to the total amount of the oxcetane compound (A), the epoxy compound (B), and the ethylenically unsaturated compound (C).

Description

Active energy ray-curable adhesive composition, polarizing plate adhesive composition, polarizing plate adhesive, and polarizing plate using the same

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, and more specifically, for use in a liquid crystal display device and the like. The present invention relates to an active energy ray-curable adhesive composition suitable for bonding a polarizer and a protective film constituting a polarizing plate.

The liquid crystal display device is widely used as an image display device 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 liquid crystal is sealed, and various optical functional films such as a retardation plate are laminated thereon as necessary.

Conventionally, a polarizing plate has a configuration in which a protective film is bonded to at least one surface, preferably both surfaces, of a polarizer made of a polyvinyl alcohol film (hereinafter, polyvinyl alcohol is abbreviated as “PVA”). ing. Here, as the polarizer, a dichroic material such as iodine is dispersed and adsorbed in a PVA film formed using a PVA resin having a high saponification degree. A uniaxially stretched PVA film cross-linked with an agent is widely used. Since such a polarizer is a uniaxially stretched PVA film, it is easy to shrink under high humidity, and a protective film is bonded 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 barrier property, isotropic property, etc. In particular, 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 as such an adhesive, from the viewpoint of adhesiveness to a polarizer having a hydrophilic surface, it is the same as the PVA resin aqueous solution, particularly the polarizer. A PVA resin aqueous solution mainly composed of a high saponification degree PVA resin is preferably used.

By the way, in recent years, there has been a demand for thinner polarizing plates, and acrylic films and cyclic olefin resin (COP) films have been used in place of TAC films that have been most commonly used as protective films. It has come to be. However, these protective films instead of the TAC film have a problem that conventional PVA adhesives are difficult to be firmly bonded to a polarizer, and the resulting polarizing plate has poor appearance. This is because the acrylic film and the COP film are more hydrophobic than the TAC film, and the moisture permeability is low, so that the water cannot be sufficiently dried. Therefore, various adhesives suitable for laminating protective films such as acrylic films and COP films have been developed as alternatives to PVA adhesives.

For example, in Patent Document 1, as an adhesive for a polarizing plate excellent in adhesiveness and water resistance, an aromatic glycidyl ether, a specific amount of an oxetane compound having a molecular weight of 100 to 800 having two or more oxetanyl groups, and a specific A cationic polymerizable adhesive containing a silane coupling agent having an amount of an alicyclic epoxy group and a cationic polymerization initiator has been proposed.

In Patent Document 2, a specific oxetane compound having two or more oxetanyl groups and an aromatic glycidyl ether as an adhesive capable of maintaining excellent normal adhesive strength for a long period of time regardless of the influence of heat, light, or the like. And a cationically polymerizable adhesive containing a cationic polymerization initiator has been proposed.

Furthermore, in Patent Document 3, for the purpose of curability and durability as an adhesive, a photocurable adhesive containing a specific poly (meth) acrylate, a specific polyglycidyl ether, an oxetane compound, a photocationic polymerization initiator, and the like. Agent compositions have been proposed.

International Publication No. 2012/144261 JP 2010-229392 A Japanese Patent Laying-Open No. 2015-40283

However, in Patent Documents 1 and 2, many epoxy groups having a ring structure such as an alicyclic epoxy group and an aromatic epoxy group are used, and the adhesive itself tends to be too hard and is an object to be bonded. Depending on the type of the protective film, sufficient adhesive strength and durability may not be obtained, and further improvements have been demanded.
Moreover, in the above-mentioned Patent Document 3, when diversification of usage environments and high durability are required in recent years, sufficient adhesive strength and durability become problems, and there is still room for improvement. Met.

Therefore, in the present invention, under such a background, the adhesive is excellent in adhesive strength, and is particularly suitable for bonding various protective films for polarizing plates and polarizers, and also has curability, water resistance, heat resistance. An active energy ray-curable adhesive composition capable of obtaining an adhesive having excellent durability such as impact resistance, and an adhesive composition for polarizing plate, an adhesive for polarizing plate, and a polarizing plate using the same It is to provide.

That is, the present inventors have made extensive studies in view of such circumstances, and as a result, in an active energy ray-curable adhesive composition that combines cationic polymerization and radical polymerization, an oxetane compound (A) and an epoxy compound (B). , An ethylenically unsaturated compound (C) and a photopolymerization initiator (D), an epoxy compound (B), an aliphatic epoxy compound (B1), and an epoxy compound (B) than before. It has been found that by containing a large amount, an adhesive capable of forming an adhesive layer excellent in the balance between durability such as thermal shock resistance and curability and adhesiveness can be obtained.

That is, the present invention is an active energy ray-curable adhesive composition containing an oxetane compound (A), an epoxy compound (B), an ethylenically unsaturated compound (C) and a photopolymerization initiator (D), The said epoxy compound (B) contains an aliphatic epoxy compound (B1), and the content rate of the said epoxy compound (B) is the said oxetane compound (A), an epoxy compound (B), an ethylenically unsaturated compound ( A first gist of the active energy ray-curable adhesive composition is 40 to 80% by weight based on the total amount of C).

Furthermore, this invention makes the 2nd summary the adhesive composition for polarizing plates which consists of the active energy ray-curable adhesive composition of the said 1st summary. Moreover, let the adhesive agent for polarizing plates which is the hardened | cured material of the adhesive composition for polarizing plates of the said 2nd summary be a 3rd summary. And let the polarizing plate by which the polarizer and the protective film are bonded together with the adhesive agent for polarizing plates of the said 3rd summary be a 4th summary.

The present invention contains a large amount of the epoxy compound (B) in the case where photocationic polymerization and photoradical polymerization are used in combination. Usually, when using radical photopolymerization for the purpose of increasing the curing speed and improving the productivity, if a large amount of the epoxy compound is contained, a sufficient curing speed cannot be obtained and the curing of the epoxy compound becomes insufficient. Therefore, since it is considered that the problem of durability occurs, the content ratio of the epoxy compound is not increased, but in the present invention, such a problem does not occur, and the curability, adhesion, and durability are improved. The present inventors have found an adhesive composition capable of obtaining an excellent adhesive.

The active energy ray-curable adhesive composition of the present invention contains an oxetane compound (A), an epoxy compound (B), an ethylenically unsaturated compound (C), and a photopolymerization initiator (D). B) contains an aliphatic epoxy compound (B1), and the content of the epoxy compound (B) is the sum of the oxetane compound (A), the epoxy compound (B) and the ethylenically unsaturated compound (C). 40 to 80% by weight with respect to the amount. Therefore, it has an effect of excellent adhesive strength, in particular, it can sufficiently bond various protective films for polarizing plates and polarizers, and also has excellent durability such as thermal shock resistance. Can be obtained.

In the present invention, in particular, when the epoxy compound (B) further contains an aromatic epoxy compound (B2), it is more excellent in balance between adhesion and durability such as thermal shock resistance. It becomes.

Furthermore, in the present invention, in particular, the content ratio (B1 / B2) of the aliphatic epoxy compound (B1) to the aromatic epoxy compound (B2) is 10/90 to 90/10 in weight ratio. Thus, the balance between the adhesiveness and the durability such as thermal shock resistance is excellent.

And especially in this invention, the content rate (AB / C) with respect to the said ethylenically unsaturated compound (C) of the total amount (AB) of the said oxetane compound (A) and an epoxy compound (B) is a weight ratio. When the ratio is 40/60 to 95/5, the balance between adhesion and durability such as thermal shock resistance is excellent.

Further, in the present invention, in particular, when the content ratio (A / B) of the oxetane compound (A) to the epoxy compound (B) is 10/90 to 60/40 in terms of weight ratio, more adhesion and heat resistance can be achieved. It has excellent durability such as impact.

And especially in the present invention, when the above-mentioned photoinitiator (D) contains a photocationic polymerization initiator (D1) and a radical photopolymerization initiator (D2), it is excellent in curability of an adhesive composition. It will be.

Further, in the present invention, in particular, the content ratio (D1 / D2) of the photocationic polymerization initiator (D1) to the photoradical polymerization initiator (D2) is 20/80 to 99/1 by weight. And more excellent curability of the adhesive composition.

Further, when the adhesive composition of the present invention further contains a silane coupling agent (E), the adhesive composition becomes more excellent in adhesiveness.

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

The active energy ray-curable adhesive composition of the present invention (hereinafter sometimes abbreviated as “adhesive composition”) includes an oxetane compound (A), an epoxy compound (B), and an ethylenically unsaturated compound (C). And a photopolymerization initiator (D). Hereinafter, each component of the adhesive composition will be described in order.

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

<Oxetane compound (A)>
The oxetane compound (A) used in the present invention may be a compound having one or more oxetanyl groups in the molecule.
Examples of the oxetane compound (A) include 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3- One oxetanyl group in the molecule such as ethyl-3- (cyclohexyloxymethyl) oxetane, 3-ethyl-3- (oxiranylmethoxy) oxetane, (meth) acrylic acid (3-ethyloxetane-3-yl) methyl, etc. One oxetane compound, 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 4, 4'-bis [(3-ethyl-3-oxetanyl) methoxymethyl] biphenyl and the like Examples thereof include oxetane compounds having two or more tanyl groups. These oxetane compounds (A) can be used alone or in combination of two or more.

Of these, 3-ethyl-3-hydroxymethyloxetane and 1,4-bis [(3-ethyl-3-oxetanyl) are easily available and have excellent dilutability (low viscosity) and excellent compatibility. ) Methoxymethyl] benzene, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3- (oxiranylmethoxy) oxetane, (meth) acrylic acid (3-ethyloxetane-3-yl) Methyl, 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane and the like are preferably used.

Further, from the viewpoint of coating properties and adhesiveness, the molecular weight is preferably 500 or less, particularly preferably 100 to 500. From the point of being preferably liquid at room temperature (25 ° C.) and having excellent curability and durability, an oxetane compound containing two or more oxetanyl groups in the molecule and one oxetanyl group in the molecule Oxetane compounds containing one (meth) acryloyl group or one epoxy group are preferred, especially 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, 3- Ethyl-3- (oxiranylmethoxy) oxetane and (meth) acrylic acid (3-ethyloxetane-3-yl) methyl are preferably used.

In addition, when an oxetane compound contains an epoxy group or a (meth) acryloyl group in the molecule, the oxetane compound is included in the oxetane compound (A), and the epoxy compound (B) or the ethylenically unsaturated compound (C) described later is included. Is not included.

Specific examples of the oxetane compound (A) include commercially available products “Aron Oxetane OXT-101”, “Aron Oxetane OXT-121”, “Aron Oxetane OXT-211”, “Aron Oxetane OXT-212”, “ Aron oxetane OXT-213 "," Aron oxetane OXT-221 "(both manufactured by Toagosei Co., Ltd.) and the like can be used. In particular, “Aron oxetane OXT-101” and “Aron oxetane OXT-221” are preferable.

<Epoxy compound (B)>
In the present invention, an epoxy compound (B) is used as a cationic polymerization component. Moreover, the said epoxy compound (B) contains an aliphatic epoxy compound (B1) from an adhesive point, and also from the point of balance of adhesiveness and durability, an aromatic epoxy compound (B2). It is preferable to use together.

Examples of the aliphatic epoxy compound (B1) include epoxy in the 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. Aliphatic epoxy compound having one group, 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 group Bifunctional or higher functional fat having two or more epoxy groups in the molecule, such as coal diglycidyl ether, polytetramethylene glycol diglycidyl ether, polybutadiene diglycidyl ether, sorbitol polyglycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether Group epoxy compounds and the like. These aliphatic epoxy compounds (B1) can be used alone or in combination of two or more.

Among these, from the viewpoint of curability, adhesion, and durability, a bifunctional or higher aliphatic epoxy compound having two or more epoxy groups in the molecule is preferable, and 1,4-butanediol diglycidyl ether, 1, It is preferable to use 6-hexanediol diglycidyl ether or neopentyl glycol diglycidyl ether.

Examples of the aromatic epoxy compound (B2) include one epoxy group in the molecule such as phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, p-sec-butylphenyl glycidyl ether, and dibromophenyl glycidyl ether. Aromatic epoxy compounds, phthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, resorcin diglycidyl ether, hydroquinone diglycidyl ether, bromobisphenol A diglycidyl ether, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, novolac type epoxy resin, biphenyl type epoxy resin, etc. Aromatic epoxy compounds and the like having two or more epoxy groups in the child. These aromatic epoxy compounds (B2) can be used alone or in combination of two or more.

Of these, aromatic epoxy compounds having two or more epoxy groups in the molecule are preferable from the viewpoint of adhesion and durability, and bisphenol A type epoxy resins and bisphenol F type epoxy resins are particularly preferable from the viewpoint of excellent curability. It is preferable to use it.

In the epoxy compound (B), when the aliphatic epoxy compound (B1) and the aromatic epoxy compound (B2) are used in combination, the aliphatic epoxy compound (B1) with respect to the aromatic epoxy compound (B2). The content ratio (B1 / B2) is preferably 10/90 to 90/10 by weight, particularly 15/85 to 85/15, more preferably 20/80 to 80/20, especially 33 /. 67 to 75/25, 50/50 to 75/25, particularly 60/40 to 70/30.

If the content is too small (there is too much aromatic epoxy compound (B2)), the adhesive strength is reduced, the coating property is lowered due to the increase in viscosity, or the compatibility of the adhesive composition is lowered. If the content is too high (the amount of the aliphatic epoxy compound (B1) is too much), the durability tends to decrease.

Furthermore, the epoxy compound (B) used in the present invention may contain another epoxy compound (B3) in addition to the aliphatic epoxy compound (B1) and the aromatic epoxy compound (B2).

Examples of the other epoxy compounds (B3) include triazine skeleton-containing epoxy compounds, alicyclic epoxy compounds, alicyclic skeleton-containing epoxy compounds, and the like. These may be used alone or in combination of two or more.

The triazine skeleton-containing epoxy compound contains one or more epoxy groups in the molecule and a triazine skeleton. For example, 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 -Epoxyoctyl) -isocyanurate and the like. These may be used alone or in combination of two or more.
From the viewpoint of further improving durability (thermal shock resistance), it is also preferable to use a triazine skeleton-containing epoxy compound.

The above-mentioned triazine skeleton-containing epoxy compound preferably has an epoxy equivalent of 120 g / eq or more, particularly preferably 130 to 300 g / eq, more preferably 140 to 250 g / eq, from the viewpoints of adhesiveness and durability.

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

Examples of the alicyclic epoxy compound include dicyclopentadiene oxide, limonene dioxide, 4-vinylcyclohexene dioxide, 3 ′, 4′-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and ε-caprolactone modification. Examples thereof include 3 ′, 4′-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexylmethyl) adipate, and the like. These may be used alone or in combination of two or more.
As the alicyclic epoxy compound, specifically, commercially available products such as “Celoxide 2021P” and “Celoxide 2000” manufactured by Daicel Corporation can be used.

Examples of the alicyclic skeleton-containing epoxy compound include epoxy compounds in which an aromatic ring is hydrogenated, such as hydrogenated bisphenol A diglycidyl ether, and cyclohexanedimethanol diglycidyl ether. These may be used alone or in combination of two or more.
Specific examples of the alicyclic skeleton-containing epoxy compound include commercially available “Denacol EX-216L” manufactured by Nagase ChemteX Corporation.

The content of at least one of the alicyclic epoxy compound and the alicyclic skeleton-containing epoxy compound is preferably 30% by weight or less, more preferably based on the total amount of the oxetane compound (A) and the epoxy compound (B). It is 20% by weight or less, particularly preferably 15% by weight or less. If the content of at least one of the alicyclic epoxy compound and the alicyclic skeleton-containing epoxy compound is too large, the adhesive force tends to decrease.

The content of the other epoxy compound (B3) is preferably 30% by weight or less, more preferably 20% by weight or less, and particularly preferably 10% by weight or less based on the entire epoxy compound (B). When there is too much content of another epoxy compound (B3), there exists a tendency for adhesive force to fall.

<Ethylenic unsaturated compound (C)>
The ethylenically unsaturated compound (C) serves as a radical polymerization component and is an unsaturated compound having at least one ethylenically unsaturated group in the molecule. By containing the ethylenically unsaturated compound (C), the curing rate can be adjusted, and the curability is improved.

Examples of the ethylenically unsaturated compound (C) include (meth) acrylic compounds having at least one (meth) acryloyl group in the molecule.

The (meth) acrylic compound may be described as, for example, a (meth) acrylic compound having one (meth) acryloyl group in the molecule (hereinafter referred to as “monofunctional (meth) acrylic compound”). ), (Meth) acrylic compounds having two or more (meth) acryloyl groups in the molecule (hereinafter sometimes referred to as “polyfunctional (meth) acrylic compounds”).
These (meth) acrylic compounds can be used alone or in combination of two or more.

Examples of the monofunctional (meth) acrylic compound include alkyl (meth) acrylate compounds, polar group-containing (meth) acrylic compounds, alicyclic (meth) acrylate compounds, and aromatic (meth) acrylate compounds. And (meth) acrylic compounds having a reactive functional group other than (meth) acryloyl group and (meth) acryloyl group in the molecule.

As the alkyl (meth) acrylate compound, for example, an alkyl (meth) acrylate having an alkyl group having 1 to 20, particularly 1 to 15, more preferably 4 to 10 carbon atoms is preferable. ) Acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) ) Acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and the like.

Examples of the polar group-containing (meth) acrylic compound include a carboxyl group-containing (meth) acrylic compound, a hydroxyl group-containing (meth) acrylate compound, a nitrogen atom-containing (meth) acrylic compound, and an alkoxy group-containing (meth) acrylate. System compounds and the like.

Examples of the carboxyl group-containing (meth) acrylic compound include (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, acrylamide N-glycolic acid, cinnamic acid, (meth) Michael adducts of acrylic acid (eg, acrylic acid dimer, methacrylic acid dimer, acrylic acid trimer, methacrylic acid trimer, acrylic acid tetramer, methacrylic acid tetramer, etc.), 2- (meth) acryloyloxyethyl dicarboxylic acid monoester (eg, 2- (meth) acryloyloxyethyl succinic acid monoester, 2- (meth) acryloyloxyethyl phthalic acid monoester, 2- (meth) acryloyloxyethyl hexahydrophthalic acid monoester, etc.).

Examples of the hydroxyl group-containing (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, and 6-hydroxyhexyl (meth). Hydroxyalkyl (meth) acrylate compounds such as acrylates, caprolactone-modified (meth) acrylate compounds such as 2-hydroxyethyl (meth) acrylate, ethylene glycol mono (meth) acrylate, propylene glycol mono (meth) acrylate, pentane Mono (meth) acrylate compounds of dihydric alcohols such as diol mono (meth) acrylate and hexanediol mono (meth) acrylate, mono (meth) acrylate of diethylene glycol Triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, dipropylene glycol mono (meth) acrylate, tripropylene glycol mono (meth) acrylate , And mono (meth) acrylate compounds of polyalkylene glycols such as mono (meth) acrylate of polypropylene glycol, and other primary hydroxyl group-containing (meth) acrylates such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid Compounds based on secondary hydroxyl groups such as 2-hydroxypropyl (meth) acrylate and 2-hydroxybutyl (meth) acrylate; 2,2-dimethyl 2-hydroxyethyl (meth) ) 3 hydroxyl group (meth) acrylate compounds such as acrylate.
Of these hydroxyl group-containing (meth) acrylate compounds, primary hydroxyl group-containing (meth) acrylate compounds are preferred in terms of easy hydrogen bond formation with the substrate or polarizer and excellent reactivity. A (meth) acrylate compound and a poly (alkylene glycol) mono (meth) acrylate compound are preferred.

Examples of the nitrogen atom-containing (meth) acrylic compound include amide group-containing (meth) acrylic compounds, amino group-containing (meth) acrylic compounds, and other nitrogen atom-containing (meth) acrylic compounds.
Examples of the amide group-containing (meth) acrylic compound include (meth) acrylamide; N, N-dialkyl (meth) acrylamide such as N, N-dimethyl (meth) acrylamide and N, N-diethyl (meth) acrylamide; N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N-propoxymethyl (meth) acrylamide, N-isopropoxymethyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N- N-alkoxyalkyl (meth) acrylamides such as isobutoxymethyl (meth) acrylamide; hydroxyl-containing acrylamides such as N- (hydroxymethyl) (meth) acrylamide; N- (3-N, N-dimethylaminopropyl) (meth) Acrylamide, methyle Bis (meth) acrylamide, ethylenebis (meth) acrylamide and the like.
Examples of amino group-containing (meth) acrylic compounds include aminomethyl (meth) acrylate and aminoethyl (meth) acrylate, primary amino group-containing (meth) acrylates such as aminoalkyl (meth) acrylate, and tert-butyl. Secondary amino group-containing (meth) acrylate such as aminoethyl (meth) acrylate, ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dialkylaminoalkyl (meth) acrylate, etc. And tertiary amine group-containing (meth) acrylates and heterocyclic amine monomers such as acryloylmorpholine.

Examples of the alkoxy group-containing (meth) acrylate compound include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, and 2-butoxyethyl (meth) acrylate. Alkoxyalkyl (meth) acrylate compounds such as 2-butoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) Acrylate, methoxypolyethylene glycol (meth) acrylate, octoxypolyethylene glycol-polypropylene glycol-mono (meth) acrylate Over DOO, lauroxypolyethylene glycol mono (meth) acrylate, polyether chains containing such stearoxy polyethylene glycol mono (meth) acrylate (meth) acrylate compounds, and the like.

Examples of the alicyclic (meth) acrylate compounds include cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, 1,4-cyclohexanedimethylol mono (meth) acrylate, dicyclopentanyl (meth) acrylate, and dicyclohexane. Examples thereof include pentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, 2-adamantyl (meth) acrylate and the like.

Examples of the aromatic (meth) acrylate compound include phenyl (meth) acrylate; benzyl (meth) acrylate; phenoxyalkyl (meth) acrylate such as phenoxyethyl (meth) acrylate and phenoxypropyl (meth) acrylate; phenoxydiethylene glycol ( Phenoxydialkylene glycol (meth) acrylates such as meth) acrylate and phenoxydipropylene glycol (meth) acrylate; phenoxypolyethylene glycol (meth) acrylate; phenoxypolyethylene glycol-polypropylene glycol- (meth) acrylate; p-cumylphenol alkylene oxide Adduct (meth) acrylate, o-phenylphenol alkylene oxide adduct (meth) acrylic Over DOO, (meth) acrylate of phenol alkylene oxide adduct (meth) acrylate and nonylphenol alkylene oxide adduct thereof.

Examples of (meth) acrylic compounds having a (meth) acryloyl group and a reactive functional group other than (meth) acryloyl group in the molecule include glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, and 3,4-epoxycyclohexyl. Epoxy group-containing (meth) acrylate compounds such as methyl (meth) acrylate, vinyl group-containing (meth) acrylate compounds such as 2- (2-vinyloxyethoxy) ethyl (meth) acrylate, 2- (meth) acryloyloxy Examples include isocyanate group-containing (meth) acrylate compounds such as ethyl isocyanate.
When the ethylenically unsaturated compound is an epoxy group-containing (meth) acrylate compound, it is included in the ethylenically unsaturated compound (C) and not included in the epoxy compound (B).

Other examples include (meth) acrylate compounds having a cyclic ether structure such as tetrahydrofurfuryl (meth) acrylate and caprolactone-modified tetrahydrofurfuryl (meth) acrylate.

Also, examples of the polyfunctional (meth) acrylic compound include a bifunctional (meth) acrylic compound and a trifunctional or higher (meth) acrylic compound.

Examples of the bifunctional (meth) acrylic compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di ( (Meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) Di (meth) acrylates having a long or branched chain structure such as acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, hydroxypivalic acid-modified neopentyl glycol di (meth) acrylate ; Having an alicyclic structure such as cyclohexanedimethanol di (meth) acrylate, dimethylol dicyclopentanedi (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, ethylene oxide-modified cyclohexanedimethanol di (meth) acrylate, etc. Di (meth) acrylate; ethylene oxide modified bisphenol A type di (meth) acrylate, propylene oxide modified bisphenol A type di (meth) acrylate, etc. Di (meth) acrylates having an aromatic ring such as ruxylene oxide-modified bisphenol A type di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, phthalic acid diglycidyl ester di (meth) acrylate; isocyanuric acid ethylene oxide Examples thereof include di (meth) acrylate having a ring structure such as modified di (meth) acrylate.

Examples of the trifunctional or higher functional (meth) acrylic compound include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and di Pentaerythritol hexa (meth) acrylate, polyglycerin poly (meth) acrylate; caprolactone-modified dipentaerythritol penta (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, caprolactone-modified pentaerythritol tri (meth) acrylate, caprolactone-modified Pentaerythritol tetra (meth) acrylate, ethylene oxide modified dipentaerythritol penta (meth) acrylate Rate, ethylene oxide modified dipentaerythritol hexa (meth) acrylate, ethylene oxide modified pentaerythritol tri (meth) acrylate, ethylene oxide modified pentaerythritol tetra (meth) acrylate, ethylene oxide modified glycerol tri (meth) acrylate, etc. A tri- or higher-functional (meth) acrylate having a long-chain or branched-chain structure such as a tri- or higher-functional (meth) acrylate having a structure; a tri (meth) acrylate having a ring structure such as an isocyanuric acid ethylene oxide-modified triacrylate Can be given.

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

As the ethylenically unsaturated compound (C), it is preferable to use a bifunctional or higher functional (meth) acrylic compound from the viewpoint of improving the curability of the adhesive composition and enhancing the durability. In particular, a bifunctional or higher functional (meth) acrylic compound having an alicyclic ring or an aromatic ring, or a (meth) acrylic compound having a linear or branched structure not having a polyalkylene oxide skeleton is preferred. A (meth) acrylic compound having a branched chain structure having no polyalkylene oxide skeleton is preferred.

<Photopolymerization initiator (D)>
The adhesive composition of the present invention exhibits adhesiveness by reacting the oxetane compound (A), the epoxy compound (B), and the ethylenically unsaturated compound (C) by irradiating active energy rays. In this reaction, a photopolymerization initiator (D) is contained.
As such a photopolymerization initiator (D), it is preferable to contain a photocationic polymerization initiator (D1), and it is particularly sufficient to contain a photocationic polymerization initiator (D1) and a photoradical polymerization initiator (D2). It is preferable at the point which acquires sclerosis | hardenability.

By using the said photocationic polymerization initiator (D1), hardening | curing at normal temperature (25 degreeC +/- 10 degreeC) of an adhesive composition is attained, and a protective film and a polarizer can be adhere | attached favorably.
The photocationic polymerization initiator (D1) is a compound that generates a cationic species or a Lewis acid upon irradiation with active energy rays. For example, an onium salt such as an aromatic diazonium salt, an aromatic iodonium salt, or an aromatic sulfonium salt, Examples thereof include iron-allene complexes.

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

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

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

Examples of the iron-allene complex include xylene-cyclopentadienyl iron (II) -hexafluoroantimonate, cumene-cyclopentadienyl iron (II) -hexafluorophosphate, xylene-cyclopentadienyl iron (II ) -Tris (trifluoromethylsulfonyl) methanide.

Among such photocationic polymerization initiators (D1), aromatic iodonium salts and aromatic sulfonium salts are preferably used because they react with high sensitivity to a long wavelength light source.
The above cationic photopolymerization initiators (D1) can be used alone or in combination of two or more.

The photo radical polymerization initiator (D2) generates radicals by irradiation with active energy rays and reacts with the ethylenically unsaturated compound (C). Examples of the photo radical polymerization initiator (D2) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 4- (2-hydroxyethoxy) phenyl- ( 2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2- Methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone, 2-hydroxy-2-methyl-1- [4- Acetophenones such as (1-methylvinyl) phenyl] propanone oligomer; benzoin, benzoin Benzoins such as chill ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether; benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4′-methyl-diphenyl sulfide, 3,3 ′, 4 , 4'-Tetra (t-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxo-2-propenyloxy) ethyl Benzophenones such as benzenemethananium bromide and (4-benzoylbenzyl) trimethylammonium chloride; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-di Thioxanthones such as rolothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino-2-hydroxy) -3,4-dimethyl-9H-thioxanthone-9-one mesochloride; 2, 4, 6 -Trimethylbenzoyl-diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, etc. Acylphosphine oxides: 1,2-octanedione, 1- [4- (phenylthio) phenyl-, 2- (O-benzoyloxime)], ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) ) -9H-carbazol-3-yl]-, 1- (O-acetylo Oxime esters such as oxime).

Among the above photo radical polymerization initiators (D2), acylphosphine oxides are preferably used, and in particular, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) ) -2,4,4-trimethyl-pentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide is preferable, and 2,4,6-trimethylbenzoyl-phenylphosphine oxide is more preferable. Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide is preferably used.

These auxiliary agents include triethanolamine, triisopropanolamine, 4,4′-dimethylaminobenzophenone (Michler ketone), 4,4′-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4-dimethylaminobenzoic acid. Ethyl, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone Etc. can be used in combination.

In the present invention, the content of the photopolymerization initiator (D) is the sum of the oxetane compound (A), the epoxy compound (B), and the ethylenically unsaturated compound (C) in that sufficient curability is obtained. The amount is preferably 0.5 to 20 parts by weight, particularly 0.5 to 15 parts by weight, and more preferably 1.0 to 10 parts by weight with respect to 100 parts by weight.
If the content is too small, the curability tends to decrease and the mechanical strength and adhesive strength tend to decrease. If the content is too large, the solubility of the photopolymerization initiator (D) itself in the composition tends to decrease.

When the photocationic polymerization initiator (D1) and the photoradical polymerization initiator (D2) are used in combination, the content ratio of the photocationic polymerization initiator (D1) and the photoradical polymerization initiator (D2) (D1 / D2) (weight ratio) is preferably 20/80 to 99/1, particularly 40/60 to 95/5, and more preferably 50/50 to 90/10, from the viewpoint of obtaining sufficient curability. If the content is too small, the curing of the cationic curing component tends not to proceed sufficiently, while if too large, the curing of the radical curing component tends not to proceed.

Further, the content of the photocationic polymerization initiator (D1) is preferably 0.5 to 20 parts by weight, particularly 100 parts by weight of the total amount of the oxetane compound (A) and the epoxy compound (B). Is preferably 1 to 15 parts by weight, more preferably 1.5 to 10 parts by weight. When there is too much content of a photocationic polymerization initiator (D1), there exists a tendency for solubility to fall or durability to fall, and when too small, curability will fall and there exists a tendency for mechanical strength and adhesive strength to fall. is there.

The content of the radical photopolymerization initiator (D2) is preferably 15 parts by weight or less, particularly 10 parts by weight or less, more preferably 5 parts by weight with respect to 100 parts by weight of the ethylenically unsaturated compound (C). The following is preferred. When there is too much content of radical photopolymerization initiator (D2), there exists a tendency for the solubility of radical photopolymerization initiator (D2) to fall, or the durability of an adhesive bond layer to fall. The lower limit is usually 0.1 parts by weight, and if it is too small, the curability tends to decrease, and the adhesive strength and mechanical strength of the adhesive layer tend to decrease.

In particular, from the viewpoint of curing efficiency (that can be cured efficiently with a small amount of active energy ray irradiation), the preferred combination of the photocation polymerization initiator (D1) and the photoradical polymerization initiator (D2) is a photocation. In this combination, an aromatic sulfonium salt or aromatic iodonium salt is used as the polymerization initiator (D1), and an acylphosphine oxide is used as the photoradical polymerization initiator (D2).

The adhesive composition of the present invention contains the above oxetane compound (A), epoxy compound (B), ethylenically unsaturated compound (C), and photopolymerization initiator (D). The greatest feature of is that the content of the epoxy compound (B) is 40 to 80% by weight based on the total amount of the oxetane compound (A), the epoxy compound (B) and the ethylenically unsaturated compound (C), The amount is preferably 42 to 70% by weight, more preferably 45 to 65% by weight. If the content ratio of the epoxy compound (B) is too small, the adhesive strength is lowered. If the content is too large, the curing rate is lowered, the mechanical strength is lowered, or the durability is lowered.

Further, the content ratio (AB / C) of the total amount (AB) of the oxetane compound (A) and the epoxy compound (B) to the ethylenically unsaturated compound (C) is 40/60 to 95/5 by weight. Is preferable from the viewpoint of the balance between adhesive strength and durability, and is particularly preferably 50/50 to 90/10, and more preferably 60/40 to 85/15. When the content is too small ((AB) is too small), curing shrinkage tends to increase and the adhesive force tends to decrease, and when it is too large (when (AB) is too much), the curing rate tends to decrease. .

In addition, the content ratio (A / B) of the oxetane compound (A) to the epoxy compound (B) is preferably 10/90 to 60/40 in terms of weight ratio in terms of adhesive strength and durability. / 88 to 50/50, more preferably 15/85 to 40/60. If the content is too small (when (A) is too small), the curing of the epoxy compound (B) does not proceed sufficiently and the durability tends to decrease, and the adhesive strength is too large (too much (A)). Tends to decrease.

<Silane coupling agent (E)>
In the adhesive composition of this invention, it is preferable to contain a silane coupling agent (E) further from the point of the adhesive improvement.

The silane coupling agent (E) is usually an organosilicon compound containing at least one reactive functional group and one silicon-bonded alkoxy group in the structure, and improves the adhesion between the adhesive layer and the protective film. Can be made.

Examples of the silane coupling agent (E) include an epoxy group-containing silane coupling agent, a mercapto group-containing silane coupling agent, a (meth) acryloyl group-containing silane coupling agent, an amino group-containing silane coupling agent, and an isocyanate group. Examples thereof include a containing silane coupling agent, a vinyl group-containing silane coupling agent, a hydroxyl group-containing silane coupling agent, a carboxyl group-containing silane coupling agent, and an amide group-containing silane coupling agent. These may be used alone or in combination of two or more.

Examples of the epoxy group-containing silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyl. Monomeric types such as glycidyloxy group (aliphatic epoxy group) -containing silane coupling agents such as methyldimethoxysilane, and alicyclic epoxy group-containing silane coupling agents such as 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane Epoxy group-containing silane coupling agents, and some of the above silane compounds undergo hydrolysis condensation polymerization, or the above silane compounds and alkyl groups such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. Condensed silane compound Such oligomeric form a silane coupling agent. These may be used alone or in combination of two or more.
In addition, when a silane coupling agent contains an epoxy group, it shall be included in a silane coupling agent (E), and is not included in an epoxy compound (B).

Examples of the mercapto group-containing silane coupling agent include monomer-type mercapto such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, and 3-mercaptopropylmethyldimethoxysilane. A group-containing silane coupling agent or a part of the silane compound undergoes hydrolytic condensation polymerization, or the silane compound and alkyl group such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, etc. Examples thereof include oligomer type silane coupling agents in which a silane compound is co-condensed. These may be used alone or in combination of two or more.

Examples of the (meth) acryloyl group-containing silane coupling agent include 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltri Examples thereof include ethoxysilane and 3-acryloxypropyltrimethoxysilane. These may be used alone or in combination of two or more.
In addition, when a silane coupling agent contains a (meth) acryloyl group, it shall be included in a silane coupling agent (E) and not included in an ethylenically unsaturated compound (C).

Examples of the amino group-containing silane coupling agent include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and 3-amino. Examples thereof include propyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane and the like. These may be used alone or in combination of two or more.

Examples of the isocyanate group-containing silane coupling agent include 3-isocyanatopropyltriethoxysilane. These may be used alone or in combination of two or more.

Examples of the vinyl group-containing silane coupling agent include vinyltrimethoxysilane and vinyltriethoxysilane. These may be used alone or in combination of two or more.
In addition, when a silane coupling agent contains a vinyl group, it shall be included in a silane coupling agent (E), and is not included in an ethylenically unsaturated compound (C).

Among the above silane coupling agents (E), epoxy group-containing silane couplings are excellent in reactivity with cationic polymerization components (oxetane compounds (A) and epoxy compounds (B)) and radical polymerization components (C). It is preferable to use an agent, a vinyl group-containing silane coupling agent, and a (meth) acryloyl group-containing silane coupling agent, particularly preferably an epoxy group-containing silane coupling agent and a (meth) acryloyl group-containing silane coupling agent. In addition, as the silane coupling agent (E), a monomer type silane coupling agent or an oligomer type silane coupling agent partially hydrolyzed and polycondensed may be used. From the viewpoint of compatibility and adhesiveness, It is preferable to use a monomer type silane coupling agent.

The content of the silane coupling agent (E) is 2 to 50 parts by weight with respect to 100 parts by weight of the total amount of the oxetane compound (A), the epoxy compound (B) and the ethylenically unsaturated compound (C). The amount is preferably 3 to 40 parts by weight, more preferably 5 to 30 parts by weight. If the content of the silane coupling agent (E) is too large, the liquid stability tends to decrease or the durability after curing (thermal shock resistance) tends to decrease. If the content is too small, the effect of improving the adhesion is further improved. Tends to be insufficient.

In the adhesive composition of the present invention, in addition to the above components, the photosensitizer, polyols, antistatic agent, other adhesives, acrylic resins, urethane resins, as long as the effects of the present invention are not impaired. Rosin, rosin ester, hydrogenated rosin ester, phenol resin, aromatic modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, styrene resin, xylene resin, etc. tackifier, plasticizer, colorant Other additives such as fillers, anti-aging agents, ultraviolet absorbers and functional dyes, and compounds that cause coloration or discoloration upon irradiation with ultraviolet rays or radiation can be blended. Although the compounding quantity of these additives is suitably set for every additive, it is preferable that it is 30 weight% or less of the whole adhesive composition, for example, Most preferably, it is 20 weight% or less.
In addition to the above additives, a small amount of impurities contained in the raw materials for producing the constituent components of the adhesive composition may be contained.

By using this photosensitizer, the reactivity is improved and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include anthracene derivatives such as 9,10-dibutoxyanthracene and 9,10-diethoxyanthracene; benzoins such as benzoin methyl ether, benzoin isopropyl ether and α, α-dimethoxy-α-phenylacetophenone Derivatives; benzophenone derivatives such as benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone; 2-chloroanthraquinone, Carbonyl compounds such as anthraquinone derivatives such as 2-methylanthraquinone; organic sulfurs such as thioxanthone derivatives such as 2-chlorothioxanthone, 2-isopropylthioxanthone and 2,4-diethylthioxanthen-9-one Compounds; persulfate, redox compounds, azo and diazo compounds, halogen compounds, photoreductive dyes and the like. These may be used alone or in combination of two or more. Of these, anthracene derivatives and thioxanthone derivatives are preferably used.

The photosensitizer is preferably contained in the range of 0.01 to 20 parts by weight when the photopolymerization initiator (D) is 100 parts by weight. When there is too much content of a photosensitizer, there exists a tendency for a composition and the adhesive bond layer obtained to color, and when too small, there exists a tendency for the reactivity to fall and for a sensitizing effect not to be acquired.

<Adhesive composition>
The adhesive composition of this invention is obtained by mix | blending and mixing in the predetermined ratio using said each component.

Thus, the active energy ray-curable adhesive composition of the present invention is obtained.
The active energy ray-curable adhesive composition of the present invention becomes an adhesive when cured by irradiation with active energy rays, and in particular, an adhesive for a polarizing plate for adhering a polarizer and a protective film. Can be suitably used.

<Polarizing plate>
The polarizing plate of the present invention is obtained by bonding a polarizer and a protective film through an adhesive for polarizing plates. Specifically, a protective film is bonded to at least one surface, preferably both surfaces, of the polarizer using the polarizing plate adhesive of the present invention, and usually a liquid polarizing plate adhesive composition is used. A polarizing plate can be obtained by uniformly applying to the polarizer surface, the protective film surface, or both surfaces, and then laminating and pressure-bonding both surfaces and irradiating with active energy rays.

As the polarizer, a film made of PVA resin having an average polymerization degree of 1,500 to 10,000 and a saponification degree of 85 to 100 mol%, preferably 95 to 100 mol% is used as a raw film. A uniaxially stretched film dyed with an iodine-potassium iodide aqueous solution or a dichroic dye (usually a stretch ratio of about 2 to 10 times, preferably about 3 to 7 times) is used.

The PVA resin is usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate, but a small amount of unsaturated carboxylic acid (including salt, ester, amide, nitrile, etc.), olefins, vinyl ethers, It may contain a component copolymerizable with vinyl acetate, such as an unsaturated sulfonate. The PVA-based resin also includes so-called polyvinyl acetal resins and PVA derivatives such as polybutyral resins and polyvinyl formal resins obtained by reacting PVA with aldehydes in the presence of an acid.

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

In coating the adhesive composition of the present invention on 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, Coating can be performed using a rod coater or the like, or a dipping method.

In the above bonding and pressure bonding, 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.

For the active energy rays, rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, electromagnetic waves such as X rays and γ rays, as well as electron rays, proton rays, neutron rays, etc. can be used. From the viewpoint of easy availability and price, ultraviolet rays are preferable.

A high pressure mercury lamp, an electrodeless lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp, a black light, an LED lamp, or the like is used as a light source for the ultraviolet irradiation.
The ultraviolet radiation is generally ² ~ 3000mJ / cm 2, preferably carried out at a 10 ~ 2000mJ / cm ^2, more preferably 20 ~ 1000mJ / cm ² conditions.

Especially in the case of the high-pressure mercury lamp, for example, usually 5 ~ 3000mJ / cm ^2, preferably at a 50 ~ 2000mJ / cm ² conditions.
In the case of the electrodeless lamp, for example, it is usually performed under conditions 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 coating surface, the coating thickness, and other conditions, but it may usually be several seconds to several tens of seconds, and in some cases, may be a fraction of a second.

On the other hand, in the case of the electron beam irradiation, for example, an electron beam having an energy in the range of 50 to 1000 keV is used, and the irradiation amount is preferably 2 to 50 Mrad.

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

The thickness of the adhesive layer in the polarizing plate of the present invention obtained as described above is usually 0.1 to 10 μm, preferably 0.2 to 5 μm, particularly preferably 0.3 to 3 μm, more preferably 0.5 to 2 μm. is there. If the thickness is too thin, the cohesive force of the adhesive force itself cannot be obtained, and the adhesive strength tends to be not obtained. If the thickness is too thick, the workability of the polarizing plate tends to deteriorate due to cracking during punching.

The active energy ray-curable adhesive composition of the present invention can be used for various adhesive applications, and is particularly suitable for laminating various polarizing plate protective films and polarizers. Excellent adhesion is exhibited.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, “part” means a weight basis.

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 oxetanyl groups in the molecule: “Aronoxetane OXT-221 manufactured by Toagosei Co., Ltd.” ")

[Epoxy compound (B)]
[Aliphatic epoxy compound (B1)]
(B1-1) Neopentyl glycol diglycidyl ether (“EX-211” manufactured by Nagase ChemteX Corporation)

[Aromatic epoxy compound (B2)]
(B2-1) Bisphenol F type epoxy resin (“jER806” manufactured by Mitsubishi Chemical Corporation)

[Ethylenically unsaturated compound (C)]
(C-1) Neopentyl glycol diacrylate (“Light acrylate NP-A” manufactured by Kyoeisha Chemical Co., Ltd.)

[Photocationic polymerization initiator (D1)]
(D1-1) Diphenyl [4- (phenylthio) phenyl] sulfonium hexafluorophosphate (aromatic sulfonium salt: “CPI-100P” manufactured by San Apro)

[Photoradical polymerization initiator (D2)]
(D2-1) 2,4,6-Trimethylbenzoyl-phenylphosphine oxide (“Irgacure TPO” manufactured by BASF)

[Silane coupling agent (E)]
(E-1) Epoxy group-containing silane coupling agent (“KBM-403 (3-glycidoxypropyltrimethoxysilane)” manufactured by Shin-Etsu Chemical Co., Ltd.)
(E-2) Acrylic group-containing silane coupling agent (“KBM-5103 (3-acryloxypropyltrimethoxysilane)” manufactured by Shin-Etsu Chemical Co., Ltd.)

[Examples 1 to 10, Comparative Examples 1 to 7]
<Preparation of active energy ray-curable adhesive composition>
An active energy ray-curable adhesive composition was prepared by blending the above-described blending components at a ratio shown in Table 1 below and mixing them.
The obtained active energy ray-curable adhesive composition was used as an adhesive composition for polarizing plates and evaluated as follows.

<Production of polarizer>
First, a PVA film having a thickness of 60 μm was stretched 1.5 times while being immersed in a water bath having a water temperature of 30 ° C. Next, the film was stretched 1.3 times while being immersed for 240 seconds in a dyeing tank (30 ° C.) composed of 0.2 g / L of iodine and 15 g / L of potassium iodide. Furthermore, it was immersed in a boric acid treatment tank (50 ° C.) having a composition of boric acid 50 g / L and potassium iodide 30 g / L, and simultaneously subjected to boric acid treatment for 5 minutes while being uniaxially stretched 3.08 times. Then, it dried at 90 degreeC and manufactured the polarizer of the total draw ratio 6 times.

<Preparation of polarizing plate test piece>
TAC film (product name “Fujitac”, manufactured by Fuji Film Co., Ltd.) having a size of 200 mm × 150 mm and thickness of 60 μm, and cyclic olefin resin (COP) film having a size of 200 mm × 150 mm, thickness of 50 μm (trade name, manufactured by Nippon Zeon Co., Ltd.) Each film of “ZEONOR”) was coated with the adhesive composition obtained above with a bar coater to a film thickness of 3 μm to obtain a film with an adhesive composition. And each film with each adhesive composition layer was overlap | superposed on both surfaces of the said polarizer of a magnitude | size 180 mm x 120 mm, respectively, and it bonded together by nip pressure 2MPa using the roll machine, and obtained the laminated film (layer of laminated film) Configuration: TAC film / polarizer / COP film).

Next, UV irradiation is performed from the COP film side of the laminated film with an ultraviolet irradiation device equipped with an electrodeless lamp at a peak illuminance of 400 mW / cm ² and an integrated exposure amount of 150 mJ / cm ² (wavelength 365 nm). The composition was cured to produce a polarizing plate test piece.
Performance evaluation was performed as follows using the polarizing plate test piece obtained above.

<Performance evaluation>
[Curing property]
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 with a finger (finger touch).
(Evaluation criteria)
○: No tackiness remained.
Δ: Tackiness did not remain, but slight finger marks were left.
X: Tackiness remained.

[Adhesive strength]
The polarizing plate test piece was cut into 120 mm × 25 mm, and the adhesion of the TAC film and the polarizer and the COP film and the polarizer when the stress in the 90 ° direction was applied was evaluated according to the following criteria.
(Evaluation criteria)
A: It was particularly firmly bonded.
○… It was firmly bonded.
Δ: Weakly bonded.
X: Not bonded.

[Durability (thermal shock resistance)]
A test piece was cut into 100 mm × 100 mm, left at −40 ° C. for 30 minutes, and then at 85 ° C. for 30 minutes, a thermal shock test was repeated 100 times. After the test, evaluation was performed according to the following criteria.
(Evaluation methods)
○: No appearance defect was confirmed.
Δ: Slightly poor appearance (short cracks occurred in the polarizer layer to the extent that the display is not affected) was confirmed.
X: Appearance defects (penetration cracks occurred in the polarizer layer) were confirmed.

From the above results, Examples 1 to 3 containing an oxetane compound (A) and an aliphatic epoxy compound (B1), preferably an aromatic epoxy compound (B2), and also containing an ethylenically unsaturated compound (C). It can be seen that the adhesive composition of No. 10 has good curability, is excellent in the adhesion between the polarizer and the protective film, and is excellent in durability. This shows that it is a thing suitable for practical use as an adhesive composition for polarizing plates excellent in balance in various performances.

On the other hand, the comparative example 1 which does not contain an aliphatic epoxy compound (B1) is inferior in adhesiveness, and the comparative example 2 which does not contain an oxetane compound (A) is both curable and adhesive. Since it is inferior and the comparative example 3 which does not contain an ethylenically unsaturated compound (C) is inferior to sclerosis | hardenability, none was used for practical use. Furthermore, in the comparative example 4, the comparative example 5 and the comparative example 6 that contain the oxetane compound (A), the epoxy compound (B), and the ethylenically unsaturated compound (C), the content ratio of the epoxy compound (B) is too low. The sufficient adhesiveness could not be obtained. Moreover, in the comparative example 7 with which the content rate of an epoxy compound (B) is too high, it was inferior to sclerosis | hardenability and durability. From these, it can be said that the adhesive composition of the comparative example cannot satisfy all the various performances and cannot be practically used as an adhesive composition for polarizing plates.
As mentioned above, it turns out that the adhesive composition of this invention is very excellent especially in the adhesive agent use for polarizing plates.

In the above embodiments, specific forms in the present invention have been described. However, the above embodiments are merely examples and are not construed as limiting. Various modifications apparent to those skilled in the art are contemplated to be within the scope of this invention.

The adhesive composition for polarizing plates comprising the adhesive composition of the present invention and further the above adhesive composition is excellent in adhesiveness between the polarizer and the protective film, and various protective films and polarizers for the polarizing plate. It is suitable for bonding. Furthermore, in addition to adhesiveness, it is excellent in balance with respect to all of curability, water resistance of the polarizing plate, durability, and particularly thermal shock resistance. Moreover, the adhesive composition of the present invention can be used for, for example, bonding various optical films or sheets, bonding electronic parts, precision equipment, packaging materials, display materials, etc. It can also be used.

Claims (11)

1. An active energy ray-curable adhesive composition containing an oxetane compound (A), an epoxy compound (B), an ethylenically unsaturated compound (C) and a photopolymerization initiator (D),
   The said epoxy compound (B) contains an aliphatic epoxy compound (B1), and the content rate of the said epoxy compound (B) is the said oxetane compound (A), an epoxy compound (B), and an ethylenically unsaturated compound ( An active energy ray-curable adhesive composition, which is 40 to 80% by weight based on the total amount of C).
2. The active energy ray-curable adhesive composition according to claim 1, wherein the epoxy compound (B) further contains an aromatic epoxy compound (B2).
3. 3. The activity according to claim 2, wherein the content ratio (B1 / B2) of the aliphatic epoxy compound (B1) to the aromatic epoxy compound (B2) is 10/90 to 90/10 by weight. Energy ray curable adhesive composition.
4. The content ratio (AB / C) of the total amount (AB) of the oxetane compound (A) and the epoxy compound (B) to the ethylenically unsaturated compound (C) is 40/60 to 95/5 by weight. The active energy ray-curable adhesive composition according to any one of claims 1 to 3, wherein
5. The content ratio (A / B) of the oxetane compound (A) with respect to the epoxy compound (B) is 10/90 to 60/40 by weight ratio. Active energy ray-curable adhesive composition.
6. The active energy according to any one of claims 1 to 5, wherein the photopolymerization initiator (D) contains a photocationic polymerization initiator (D1) and a photoradical polymerization initiator (D2). A linear curable adhesive composition.
7. The content ratio (D1 / D2) of the photocationic polymerization initiator (D1) and the photoradical polymerization initiator (D2) is 20/80 to 99/1 in weight ratio. An active energy ray-curable adhesive composition.
8. The active energy ray-curable adhesive composition according to any one of claims 1 to 7, further comprising a silane coupling agent (E).
9. An adhesive composition for polarizing plates, comprising the active energy ray-curable adhesive composition according to any one of claims 1 to 8.
10. An adhesive for polarizing plates, which is a cured product of the adhesive composition for polarizing plates according to claim 9.
11. It is a polarizing plate which has the adhesive agent for polarizing plates of Claim 10, a polarizer, and a protective film, Comprising: The said polarizer and protective film are bonded together by the said adhesive agent for polarizing plates. Polarizer.