KR102496513B1 - Actinicraycurable adhesive composition, adhesive composition for polarizer, adhesive for polarizer, and polarizer obtained using same - Google Patents

Abstract

It is excellent in adhesive strength and is very suitable for bonding with various protective films for polarizing plates and polarizers, and also has excellent durability such as curability and thermal shock resistance. ), an ethylenically unsaturated compound (C) and an active energy ray-curable adhesive composition containing a photopolymerization initiator (D), wherein the epoxy compound (B) contains an aliphatic epoxy compound (B1), and the epoxy compound (B) An active energy ray-curable adhesive composition having a content ratio of 40 to 80% by weight relative to the total amount of the oxetane compound (A), the epoxy compound (B) and the ethylenically unsaturated compound (C) is provided.

Description

Active energy ray-curable adhesive composition, adhesive composition for polarizer, adhesive for polarizer, and polarizer using the same

The present invention relates to an active energy ray-curable adhesive composition, an adhesive composition for polarizing plates, an adhesive for polarizing plates, and a polarizing plate using the same, and more particularly, an active energy ray-curable adhesive composition suitable for bonding a polarizer constituting a polarizing plate used in a liquid crystal display and a protective film It relates to an energy ray curable adhesive composition.

The liquid crystal display device is widely used as an image display device such as a liquid crystal TV, a computer display, a mobile phone or a digital camera. Such a liquid crystal display device has a structure in which polarizing plates are laminated on both sides of a glass substrate encapsulated with liquid crystal, and various optical function films such as retardation plates are laminated thereon as necessary.

Conventionally, a polarizing plate has a structure in which a protective film is bonded to at least one surface, preferably both surfaces, of a polarizer made of a polyvinyl alcohol-based film (hereinafter, polyvinyl alcohol is abbreviated as "PVA"). Here, as the polarizer, a dichroic material such as iodine is dispersed and adsorbed in a PVA-based film formed by forming a film using a PVA-based resin having a high saponification degree, preferably further crosslinked with a crosslinking agent such as boric acid, uniaxially stretched PVA based films are widely used. Since such a polarizer is a uniaxially stretched PVA-based 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 resins, polycarbonate resins, cyclic polyolefin resins, (meth)acrylic resins, and polyester resins are excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc. However, in particular, a protective film made of triacetyl cellulose (TAC) resin has been widely used.

Then, these protective films are bonded to the polarizer with an adhesive, but as such an adhesive, from the viewpoint of adhesiveness to the polarizer having a hydrophilic surface, a PVA-based resin aqueous solution, especially a PVA-based PVA-based resin having a high saponification degree such as a polarizer An aqueous resin solution is preferably used.

However, in recent years, thinning of the polarizing plate has been demanded, and an acrylic film or a cyclic olefin resin (COP) film has been used instead of the TAC film, which has been most commonly used as a protective film so far. However, protective films that replace these TAC films have problems in that it is difficult to bond firmly to a polarizer with conventional PVA-based adhesives, or that the obtained polarizing plate has poor appearance. This is due to the fact that the acrylic film or the COP film is hydrophobic compared to the TAC film and cannot sufficiently dry water because the water vapor permeability is low. For this reason, development of various adhesives suitable also for pasting of protective films, such as an acrylic film and a COP film, as a substitute for the PVA-type adhesive agent is performed.

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

Further, in Patent Document 2, a specific oxetane compound having two or more oxetanyl groups, aromatic glycidyl ether, and cationic polymerization as an adhesive capable of maintaining excellent state adhesive strength for a long period of time regardless of the influence of heat or light. Cationic polymerizable adhesives containing an initiator have been proposed.

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

Patent Document 1 WO2012/144261A Patent Document 2 JP 2010-229392A Patent Document 3 JP 2015-40283A

However, in Patent Documents 1 and 2, a lot of epoxy groups having a ring structure, such as an alicyclic epoxy group or an aromatic epoxy group, are used, and the adhesive itself tends to be too hard, so depending on the type of protective film to be adhered, sufficient In some cases, adhesive strength and durability could not be obtained, and further improvements have been demanded.

In addition, in Patent Document 3, when diversification of use environments and high durability are required in recent years, sufficient adhesive force and durability become a problem, and there is still room for improvement.

Therefore, in the present invention, under such a background, it is an adhesive excellent in adhesive strength, particularly suitable for bonding with various protective films for polarizing plates and polarizers, and also excellent in durability such as curability, water resistance, and thermal shock resistance. An adhesive can be obtained. It is to provide an active energy ray-curable adhesive composition, and an adhesive composition for polarizing plates using the same, an adhesive for polarizing plates, and a polarizing plate.

That is, the inventors of the present invention have studied intensively in view of such circumstances, and as a result, in an active energy ray curable adhesive composition in which cationic polymerization and radical polymerization are used in combination, an oxetane compound (A), an epoxy compound (B), ethylene By containing a sexually unsaturated compound (C) and a photopolymerization initiator (D), containing an aliphatic epoxy compound (B1) as the epoxy compound (B), and containing more epoxy compound (B) than before, thermal shock resistance, etc. It has been found that an adhesive capable of forming an adhesive layer having an excellent balance of durability, 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), wherein the epoxy compound (B) Contains an aliphatic epoxy compound (B1), and the content ratio of the epoxy compound (B) is 40 to 80 weight relative to the total amount of the oxetane compound (A), the epoxy compound (B) and the ethylenically unsaturated compound (C) The active energy ray-curable adhesive composition of % is made into a 1st summary.

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

In the case of using photocationic polymerization and photoradical polymerization together, the present invention is to contain a large amount of the epoxy compound (B). Usually, when photo-radical polymerization is used in combination for the purpose of increasing productivity by increasing the curing rate, when a large amount of epoxy compound is contained, a sufficient curing rate cannot be obtained, resulting in insufficient curing of the epoxy compound, resulting in a durability problem. Since it is considered that it is, the content ratio of the epoxy compound is not high, but in the present invention, an adhesive composition capable of obtaining an adhesive having excellent curability, adhesiveness and durability is found without causing such a problem.

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), wherein the epoxy compound (B) is an aliphatic It contains an epoxy compound (B1), and the content ratio of the epoxy compound (B) is 40 to 80% by weight relative to the total amount of the oxetane compound (A), the epoxy compound (B) and the ethylenically unsaturated compound (C). . For this reason, an effect excellent in adhesive strength is exhibited, and in particular, various protective films for polarizing plates and polarizers can be sufficiently adhered, and a polarizing plate excellent in durability such as thermal shock resistance can be obtained.

In addition, especially in this invention, when the said epoxy compound (B) further contains an aromatic epoxy compound (B2), the balance of adhesiveness and durability, such as a thermal shock resistance, becomes more excellent.

In addition, especially in the present invention, when the content ratio (B1/B2) of the aliphatic epoxy compound (B1) to the aromatic epoxy compound (B2) is 10/90 to 90/10 in terms of weight ratio, adhesion and thermal shock resistance are higher. It becomes an excellent balance with the durability of the back.

And, especially in the present invention, 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 by weight If it is 95/5, it becomes what is further excellent in the balance with durability, such as adhesiveness and thermal shock resistance.

In addition, especially in the present invention, 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, adhesiveness, thermal shock resistance, etc. It becomes a durable thing.

And especially in this invention, when the said photoinitiator (D) contains a photocationic polymerization initiator (D1) and a photoradical polymerization initiator (D2), the adhesive composition will become excellent in curability.

Moreover, especially in this invention, when the content ratio (D1/D2) of the said photocationic polymerization initiator (D1) and radical photopolymerization initiator (D2) is 20/80 - 99/1 by weight ratio, the adhesive composition is more excellent in curability it becomes

Moreover, when the adhesive composition of this invention further contains a silane coupling agent (E), it becomes what is further excellent in adhesiveness.

Hereinafter, although this invention is demonstrated in detail, these show an example of a preferable embodiment.

The active energy ray-curable adhesive composition (hereinafter sometimes abbreviated as "adhesive composition") of the present invention includes an oxetane compound (A), an epoxy compound (B), an ethylenically unsaturated compound (C) and a photopolymerization initiator (D) It is made up of containing Hereinafter, each component of adhesive composition is demonstrated 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, respectively.

<Oxetane compound (A)>

The oxetane compound (A) used in the present invention may be a compound having one or more oxetanyl groups in its molecule.

Examples of the oxetane compound (A) include 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, and 3-ethyl-3-(phenoxetane). Cymethyl)oxetane, 3-ethyl-3-(cyclohexyloxymethyl)oxetane, 3-ethyl-3-(oxiranylmethoxy)oxetane, (meth)acrylic acid (3-ethyloxetan-3-yl ) An oxetane compound having one oxetanyl group in a molecule such as methyl, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, 1,4-bis[( 3-ethyl-3-oxetanyl) methoxymethyl] benzene, 4,4'-bis [(3-ethyl-3-oxetanyl) methoxy methyl] biphenyl with two oxetanyl groups in the molecule. The oxetane compound etc. which have the above are mentioned. These oxetane compounds (A) can be used alone or in combination of two or more.

Among them, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetane) are easily available, and from the viewpoint of excellent dilutability (low viscosity) and compatibility, etc. Cetanyl) methoxymethyl] benzene, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, 3-ethyl-3-(oxiranylmethoxy)oxetane, (meth)acrylic acid (3-ethyloxetane) Cetan-3-yl)methyl, 3-ethyl-3{[(3-ethyloxetan 3-yl)methoxy]methyl}oxetane, etc. are preferably used.

Moreover, from a viewpoint of coatability or adhesiveness, a molecular weight of 500 or less is preferable, and 100-500 are especially preferable. Further, from the viewpoint of being liquid at room temperature (25°C) and excellent in curability and durability, an oxetane compound containing two or more oxetanyl groups in a molecule or one oxetanyl group in a molecule and one (meth) An oxetane compound containing an acryloyl group or one epoxy group is preferred, particularly 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, 3-ethyl-3 -(oxiranylmethoxy)oxetane and (meth)acrylic acid (3-ethyloxetan-3-yl)methyl are preferably used.

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

As the oxetane compound (A), specifically, commercially available "Aronoxetane OXT-101", "Aronoxetane OXT-121", "Aronoxetane OXT-211", "Aronoxetane OXT-212" , "Aronoxetane OXT-213", "Aronoxetane OXT-221" (all manufactured by Toagosei Co., Ltd.), etc. can be used. In particular, "Aronoxetane OXT-101" and "Aronoxetane OXT-221" are preferable.

<Epoxy compound (B)>

The present invention is to use an epoxy compound (B) as a component for cationic polymerization. The epoxy compound (B) contains an aliphatic epoxy compound (B1) from the viewpoint of adhesiveness, and from the viewpoint of adhesiveness and durability, an aromatic epoxy compound (B2) is preferably used in combination.

Examples of the aliphatic epoxy compound (B1) include butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, glycidol, alcohol glycidyl ether having 11 to 15 carbon atoms, Aliphatic epoxy compounds having one epoxy group in the molecule such as lauryl alcohol glycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycy Dill ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol di Epoxy groups in molecules such as glycidyl ether, polytetramethylene glycol diglycidyl ether, polybutadiene diglycidyl ether, sorbitol polyglycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether The bifunctional or more than bifunctional aliphatic epoxy compound etc. which have 2 or more are mentioned. These aliphatic epoxy compounds (B1) can be used alone or in combination of two or more.

Among them, bifunctional or higher-functional aliphatic epoxy compounds having two or more epoxy groups in the molecule are preferred from the viewpoint of curability, adhesiveness, and durability, and 1,4-butanediol diglycidyl ether and 1,6-hexanedioldi It is preferable to use glycidyl ether and neopentyl glycol diglycidyl ether.

Examples of the aromatic epoxy compound (B2) include phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, p-sec-butylphenyl glycidyl ether, and dibromophenyl glycidyl ether. Aromatic epoxy compounds having one epoxy group in the molecule, such as 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 novolak type epoxy resin, cresol novolak type epoxy resin, novolak type epoxy resin, biphenyl type epoxy resin, etc. and aromatic epoxy compounds having two or more epoxy groups in the molecule of . These aromatic epoxy compounds (B2) can be used alone or in combination of two or more.

Among them, aromatic epoxy compounds having two or more epoxy groups in the molecule are preferable from the viewpoint of adhesiveness and durability, and bisphenol A type epoxy resin and bisphenol F type epoxy resin are particularly preferable from the viewpoint of excellent curability.

In the epoxy compound (B), when the aliphatic epoxy compound (B1) and the aromatic epoxy compound (B2) are used together, the content ratio of the aliphatic epoxy compound (B1) to the aromatic epoxy compound (B2) (B1 /B2) is a weight ratio, preferably 10/90 to 90/10, particularly 15/85 to 85/15, further 20/80 to 80/20, particularly 33/67 to 75/25, more preferably 50/ 50 to 75/25, particularly 60/40 to 70/30.

If the content ratio is too small (the amount of the aromatic epoxy compound (B2) is too large), there is a tendency for adhesive strength to decrease or coating property to deteriorate due to an increase in viscosity or compatibility of the adhesive composition to deteriorate, and if the content ratio is too large, (Too much aliphatic epoxy compound (B1)) There is a tendency for durability to decrease.

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

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

The triazine skeleton-containing epoxy compound contains at least one epoxy group and a triazine skeleton in a molecule, and examples thereof include tris(2,3-epoxypropyl)-isocyanurate and tris(3,4- Epoxybutyl)-isocyanurate, tris(4,5-epoxypentyl)-isocyanurate, tris(5,6-epoxyhexyl)-isocyanurate, tris(6,7-epoxyheptyl)-iso cyanurate, 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 triazine skeleton-containing epoxy compound preferably has an epoxy equivalent of 120 g/eq or more, particularly preferably 130 to 300 g/eq, and still more preferably 140 to 250 g/eq, from the viewpoint of adhesiveness and durability.

Specifically, as the triazine skeleton-containing epoxy compound, commercially available TEPIC series manufactured by Nissan Kagaku Kogyo Co., Ltd. ("TEPIC-G", "TEPIC-S", "TEPIC-SS", "TEPIC-HP", " "TEPIC-L", "TEPIC-PAS", "TEPIC-VL", "TEPIC-UC", "TEPIC-FL", etc.) can be used. Especially, from a compatible viewpoint, "TEPIC-PAS", "TEPIC-VL", "TEPIC-UC", and "TEPIC-FL" which are liquid epoxy compounds are preferable.

Examples of the alicyclic epoxy compound include dicyclopentadiene oxide, limonene dioxide, 4-vinylcyclohexene dioxide, 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, ε- caprolactone-modified 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 said alicyclic epoxy compound, "celloxide 2021P", "celloxide 2000", etc. made by Daicell Co., Ltd. can be used for all commercially available products specifically,.

Examples of the alicyclic skeleton-containing epoxy compound include an epoxy compound in which an aromatic ring such as hydrogenated bisphenol A diglycidyl ether is hydrogenated, cyclohexanedimethanol diglycidyl ether, and the like. These may be used alone or in combination of two or more.

Specifically as said alicyclic backbone containing epoxy compound, "Denacol EX-216L" by Nagase ChemteX Co., Ltd. of a commercial item etc. can be used.

The content of at least one of the alicyclic epoxy compound and the alicyclic backbone-containing epoxy compound is preferably 30% by weight or less, more preferably 20% by weight or less, particularly based on the total amount of the oxetane compound (A) and the epoxy compound (B). Preferably it is 15 weight% or less. When the content of at least one of the alicyclic epoxy compound and the alicyclic backbone-containing epoxy compound is too large, the adhesive strength 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 with respect to the total amount of the epoxy compound (B). When the content of the other epoxy compound (B3) is too large, the adhesive strength tends to decrease.

<ethylenically unsaturated compound (C)>

The said ethylenically unsaturated compound (C) is an unsaturated compound which becomes a radical polymerization component and has at least 1 ethylenically unsaturated group in a molecule|numerator. By containing the ethylenically unsaturated compound (C), the curing rate can be adjusted and the curing properties are improved.

As said ethylenically unsaturated compound (C), the (meth)acrylic compound which has at least 1 (meth)acryloyl group in a molecule|numerator is mentioned, for example.

Examples of the (meth)acrylic compound include a (meth)acrylic compound having one (meth)acryloyl group in a molecule (hereinafter sometimes referred to as a “monofunctional (meth)acrylic compound”), and two (meth)acrylic compounds in a molecule. (meth)acrylic compounds (hereinafter sometimes referred to as “polyfunctional (meth)acrylic compounds”) having two or more (meth)acryloyl groups are exemplified.

These (meth)acrylic compounds can be used alone or in combination of two or more.

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

As the alkyl (meth)acrylate-based compound, for example, an alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms, particularly 1 to 15, and further 4 to 10 carbon atoms is preferable, and specifically, methyl (meth) Acrylates, 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, etc. are mentioned.

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 compound. etc. can be mentioned.

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, and Michael addition of (meth)acrylic acid. Water (eg, acrylic acid dimer, methacrylic acid dimer, acrylic acid trimer, methacrylic acid trimer, acrylic acid tetramer, methacrylic acid tetramer, etc.), 2-(meth)acryloyloxyethyldicarboxylic acid monoester ( For example, 2-(meth)acryloyloxyethyl succinic acid monoester, 2-(meth)acryloyloxyethyl phthalic acid monoester, 2-(meth)acryloyloxyethyl hexahydrophthalic acid monoester, etc. ) and the like.

As said hydroxyl-containing (meth)acrylate type compound, for example, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6 -Hydroxyalkyl (meth)acrylate-based compounds such as hydroxyhexyl (meth)acrylate, caprolactone-modified (meth)acrylate-based compounds such as caprolactone-modified 2-hydroxyethyl (meth)acrylate, and ethylene glycol mono(meth)acrylate-based compounds of dihydric alcohols such as mono(meth)acrylate, propylene glycol mono(meth)acrylate, pentanediol mono(meth)acrylate, and hexanediol mono(meth)acrylate; Mono(meth)acrylate of ethylene glycol, mono(meth)acrylate of triethylene glycol, mono(meth)acrylate of tetraethylene glycol, mono(meth)acrylate of polyethylene glycol, mono(meth)acrylate of dipropylene glycol Polyalkylene glycol mono(meth)acrylate compounds such as acrylate, tripropylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate, and others, 2-acryloyloxy Primary hydroxyl-containing (meth)acrylate-based compounds such as ethyl-2-hydroxyethylphthalic acid; Secondary hydroxyl groups such as 2-hydroxypropyl (meth)acrylate and 2-hydroxybutyl (meth)acrylate Containing (meth)acrylate-based compounds; Tertiary hydroxyl group-containing (meth)acrylate-based compounds such as 2,2-dimethyl-2-hydroxyethyl (meth)acrylate; and the like.

Among such hydroxyl group-containing (meth)acrylate-based compounds, primary hydroxyl-containing (meth)acrylate-based compounds are preferable from the viewpoint of easily generating hydrogen bonds with substrates or polarizers or from the viewpoint of excellent reactivity, and in particular, hydroxyalkyl (meth ) Preferred are acrylate-based compounds and polyalkylene glycol mono(meth)acrylate-based compounds.

Examples of the nitrogen atom-containing (meth)acrylic compound include an amide group-containing (meth)acrylic compound, an amino group-containing (meth)acrylic compound, and other nitrogen atom-containing (meth)acrylic compounds.

Examples of the amide group-containing (meth)acrylic compound include (meth)acrylamide; N,N-dialkyl such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide; (meth)acrylamide; N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-propoxymethyl (meth)acrylamide, N-isopropoxymethyl (meth)acrylamide , N-alkoxyalkyl (meth)acrylamides such as N-n-butoxymethyl (meth)acrylamide and N-isobutoxymethyl (meth)acrylamide; containing hydroxyl groups such as N-(hydroxymethyl)(meth)acrylamide Acrylamide; N-(3-N,N-dimethylaminopropyl) (meth)acrylamide, methylenebis(meth)acrylamide, ethylenebis(meth)acrylamide, etc. are mentioned. Examples of the amino group-containing (meth)acrylic compound include primary amino group-containing (meth)acrylates such as aminomethyl (meth)acrylate, aminoethyl (meth)acrylate, and aminoalkyl (meth)acrylates; - Secondary amino group-containing (meth)acrylates such as butylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc. , tertiary amino group-containing (meth)acrylates such as dialkylaminoalkyl (meth)acrylates, and heterocyclic amine monomers such as acryloylmorpholine.

Examples of the alkoxy group-containing (meth)acrylate-based compound include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, Alkoxyalkyl (meth)acrylate compounds such as 2-butoxyethyl (meth)acrylate, 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, lau and polyether chain-containing (meth)acrylate-based compounds such as oxypolyethylene glycol mono(meth)acrylate and stearoxypolyethylene glycol mono(meth)acrylate.

Examples of the alicyclic (meth)acrylate-based compound include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, 1,4-cyclohexanedimethylol mono(meth)acrylate, dicyclopentanyl ( meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 2-adamantyl (meth)acrylate and the like.

Examples of the aromatic (meth)acrylate-based compound include phenyl (meth)acrylate; benzyl (meth)acrylate; phenoxyalkyl such as phenoxyethyl (meth)acrylate and phenoxypropyl (meth)acrylate; (Meth)acrylate; Phenoxydialkylene glycol (meth)acrylates such as phenoxydiethylene glycol (meth)acrylate and phenoxydipropylene glycol (meth)acrylate; Phenoxypolyethylene glycol (meth)acrylate; Phenoxy Polyethylene glycol-polypropylene glycol-(meth)acrylate; (meth)acrylate of p-cumylphenolalkylene oxide adduct, (meth)acrylate of o-phenylphenolalkylene oxide adduct, phenolalkylene oxide adduct ( meth)acrylates and (meth)acrylates of nonylphenol alkylene oxide adducts; and the like.

Examples of the (meth)acrylic compound having a (meth)acryloyl group and a reactive functional group other than a (meth)acryloyl group in the molecule include glycidyl methacrylate and 4-hydroxybutyl acrylate glycidyl ether , Epoxy group-containing (meth)acrylate compounds such as 3,4-epoxycyclohexylmethyl (meth)acrylate, vinyl group-containing (meth)acrylate compounds such as 2-(2-vinyoxyethoxy)ethyl (meth)acrylate and isocyanate group-containing (meth)acrylate-based compounds such as acrylate-based compounds and 2-(meth)acryloyloxyethyl isocyanate.

In addition, when an ethylenically unsaturated compound is an epoxy group-containing (meth)acrylate type compound, it is included in an ethylenically unsaturated compound (C) and is not included in an epoxy compound (B).

In addition, (meth)acrylate-type compounds having a cyclic ether structure, such as tetrahydrofurfuryl (meth)acrylate and caprolactone-modified tetrahydrofurfuryl (meth)acrylate, are also included.

Moreover, as a polyfunctional (meth)acrylic-type compound, a bifunctional (meth)acrylic-type compound and a trifunctional or more than trifunctional (meth)acrylic-type compound are mentioned.

Examples of the bifunctional (meth)acrylic compound include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. Rate, 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 )Acrylate, neopentylglycoldi(meth)acrylate, 1,4-butanedioldi(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, glycerine di(meth)acrylate, pentaeryth Lithol di(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, hydroxypivaric acid modified neopentyl glycol di(meth) Di(meth)acrylate having a long chain or branched chain structure such as acrylate; Cyclohexanedimethanol di(meth)acrylate, dimethylol dicyclopentane di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate di(meth)acrylates having an alicyclic structure such as ethylene oxide-modified cyclohexanedimethanol di(meth)acrylate; ethylene oxide-modified bisphenol A-type di(meth)acrylate; propylene oxide-modified bisphenol A-type di(meth)acrylate; ) Aromatic rings such as alkylene oxide-modified bisphenol A di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, phthalic acid diglycidyl ester di(meth)acrylate, etc. Di(meth)acrylate having; di(meth)acrylate having ring structure, such as isocyanuric acid ethylene oxide-modified di(meth)acrylate, etc. are mentioned.

As a trifunctional or more than trifunctional (meth)acrylic compound, for example, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaeryth Ritolpenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, polyglycerin poly(meth)acrylate; caprolactone-modified dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaene Lythritol 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 glycerin tri Tri- or higher-functional (meth)acrylates having long-chain or branched-chain structures, such as tri- or higher-functional (meth)acrylates having an alkyl-modified structure such as (meth)acrylate; isocyanuric acid ethylene oxide-modified triacrylate; Tri(meth)acrylate etc. which have ring structure are mentioned.

Moreover, oligomers, such as urethane (meth)acrylate, polyester (meth)acrylate, and epoxy (meth)acrylate, can also be used as a (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 and durability of the adhesive composition. In particular, a bifunctional (meth)acrylic compound having an alicyclic ring or an aromatic ring and a (meth)acrylic compound having a linear or branched chain structure without a polyalkylene oxide skeleton are preferable, and a polyalkylene oxide skeleton A (meth)acrylic compound having a branched chain structure without having is preferred.

<Photoinitiator (D)>

The adhesive composition of the present invention is irradiated with active energy rays, and the oxetane compound (A), epoxy compound (B), and ethylenically unsaturated compound (C) react to exhibit adhesiveness. A photopolymerization initiator (D) is contained therein.

It is preferable to contain a photocationic polymerization initiator (D1) as such a photoinitiator (D), and it is preferable to contain a photocationic polymerization initiator (D1) and a photoradical polymerization initiator (D2) in particular from the viewpoint of obtaining sufficient curability. do.

By using the said photocationic polymerization initiator (D1), hardening at normal temperature (25 degreeC±10 degreeC) of 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, and examples thereof include aromatic diazonium salts, aromatic iodonium salts, and onium salts such as aromatic sulfonium salts, iron- Allen complex etc. are mentioned.

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

Examples of the aromatic iodonium salt include diphenyliodonium tetraquis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di(4 -Nonylphenyl)iodonium hexafluorophosphate, etc. are mentioned.

As the aromatic sulfonium salt, for example, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetraquis (pentafluorophenyl) borate, 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)phenylsulfonio]diphenylsulfide- Bishexafluorophosphate, 7-[di(p-tolyl)sulfonio]-2-isopropylthioxanthone hexafluoroantimonate, 7-[di(p-tolyl)sulfonio]-2 -Isopropylthioxanthone/tetraquis(pentafluorophenyl)borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide/hexafluorophosphate, 4-(p-tert-butyl) Phenylcarbonyl)-4'-diphenylsulfonyldiphenylsulfide hexafluoroantimonate, 4-(p-tert-butylphenylcarbonyl)-4'-diphenyl-tolyl)sulfonio-di Phenylsulfide tetraquis (pentafluorophenyl) borate etc. are mentioned.

Examples of the iron-alene complex include xylenecyclopentadienyl iron(II)-hexafluoroantimonate, cumenecyclopentadienyl iron(II)-hexafluorophosphate, and xylenecyclopentadienyl. Iron(II)-tris(trifluoromethylsulfonyl)methanide etc. are mentioned.

Among such photocationic polymerization initiators (D1), it is preferable to use aromatic iodonium salts and aromatic sulfonium salts from the viewpoint of reacting with high sensitivity to long-wavelength light sources.

The photocationic polymerization initiator (D1) may be used alone or in combination of two or more.

In addition, the photoradical polymerization initiator (D2) generates radicals by irradiation with active energy rays and causes the ethylenically unsaturated compound (C) to react. Examples of the photoradical polymerization initiator (D2) include diethoxyacephenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, and 4-(2-hydroxyethoxy). ) Phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenylketone, 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 , Acetphenones such as 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer; Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether , Benzoins such as benzoin isobutyl ether; Benzophenone, o-methyl 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 benzenemetanamium bromide and (4-benzoylbenzyl)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-one mesochloride Thioxanthones such as; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, bis(2,4 Acylphosphine oxides such as ,6-trimethylbenzoyl)-phenylphosphine oxide; 1,2-octanedione, 1-[4-(phenylthio)phenyl-,2-(O-benzoyloxime)], ethanone , 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, and oxime esters such as 1-(O-acetyloxime).

Among the above radical photopolymerization initiators (D2), it is preferable to use acylphosphine oxides, and particularly 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 preferred, and 2,4,6-trimethylbenzoyl-phenylphosphine oxide and bis It is preferred to use (2,4,6-trimethylbenzoyl)-diphenylphosphine oxide.

Moreover, as these preparations, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Mihiraketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4-dimethylaminobenzoic acid Ethyl, 4-dimethylaminobenzoate (n-butoxy)ethyl, 4-dimethylaminobenzoate isoamyl, 4-dimethylaminobenzoate-2-ethylhexyl, 2,4-diethylthioxanthone, 2,4-di It is also possible to use isopropyl thioxanthone etc. together.

In the present invention, the content of the photopolymerization initiator (D) is, from the viewpoint of obtaining sufficient curability, based on 100 parts by weight of the total amount of the oxetane compound (A), the epoxy compound (B), and the ethylenically unsaturated compound (C), It is preferably 0.5 to 20 parts by weight, particularly preferably 0.5 to 15 parts by weight, and more preferably 1.0 to 10 parts by weight. When such a content is too small, curability tends to decrease and mechanical strength and adhesive strength tend to decrease, and when too large, solubility of the photopolymerization initiator (D) itself in the composition tends to decrease.

In the case of using the photocationic polymerization initiator (D1) and the photoradical polymerization initiator (D2) together, the content ratio (D1/D2) (weight ratio) of the photocationic polymerization initiator (D1) and the photoradical polymerization initiator (D2) is From the viewpoint of obtaining sufficient curability, it is preferably 20/80 to 99/1, particularly 40/60 to 95/5, and more preferably 50/50 to 90/10. If such a content ratio is too small, curing of the cationic curing component tends not to proceed sufficiently, and if it is too large, curing of the radical curing component tends not to proceed conversely.

The content of the photocationic polymerization initiator (D1) is preferably 0.5 to 20 parts by weight, particularly 1 to 15 parts by weight, more preferably 1.5 parts by weight to 100 parts by weight of the total amount of the oxetane compound (A) and the epoxy compound (B). -10 parts by weight is preferred. When the content of the photocationic polymerization initiator (D1) is too large, the solubility or durability tends to decrease, and when the content is too small, the curability decreases and mechanical strength or adhesive strength tends to decrease.

The content of the photoradical polymerization initiator (D2) is preferably 15 parts by weight or less, particularly preferably 10 parts by weight or less, and more preferably 5 parts by weight or less with respect to 100 parts by weight of the ethylenically unsaturated compound (C). When the content of the photo-radical polymerization initiator (D2) is too large, the solubility of the photo-radical polymerization initiator (D2) tends to decrease or the durability of the adhesive layer tends to decrease. In addition, the lower limit is usually 0.1 part by weight, and when too small, the curability or the adhesive strength or mechanical strength of the adhesive layer tends to decrease.

In particular, from the viewpoint of curing efficiency (can be efficiently cured with a small amount of active energy ray irradiation), a preferable combination of the photocationic polymerization initiator (D1) and the photoradical polymerization initiator (D2) is a photocationic polymerization initiator (D1 ) as a combination of using an aromatic sulfonium salt and an aromatic iodonium salt, and using acylphosphine oxides as an optical radical 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), and the greatest feature of the present invention is, The content of the epoxy compound (B) is 40 to 80% by weight, preferably 42 to 70% by weight, based on the total amount of the oxetane compound (A), the epoxy compound (B) and the ethylenically unsaturated compound (C). Preferably it is 45 to 65 weight%. When the content ratio of such an epoxy compound (B) is too small, adhesive strength decreases, and when too large, the curing rate decreases, mechanical strength decreases, and durability decreases.

In addition, 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 in terms of weight ratio It is preferable from a viewpoint of durable balance, and it is especially preferable that it is 50/50 - 90/10, and also 60/40 - 85/15. When such a content ratio is too small (too little (AB)), curing shrinkage tends to increase and the adhesive strength tends to decrease, and when it is too large (too much (AB)), the curing speed tends to decrease.

Further, the content ratio (A/B) of the oxetane compound (A) to the epoxy compound (B) is preferably 10/90 to 60/40 in weight ratio from the viewpoint of adhesive strength and durability, particularly 12/88 to 60/40. It is 50/50, and preferably 15/85 to 40/60. If such a content ratio is too small (if (A) is too small), curing of the epoxy compound (B) will not sufficiently proceed and durability tends to decrease, and if it is too large ((A) is too large), adhesive strength will decrease. tend to become

<Silane coupling agent (E)>

In the adhesive composition of the present invention, it is preferable to further contain a silane coupling agent (E) from the viewpoint of improving adhesiveness.

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

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-containing silane coupling agent. , vinyl group-containing silane coupling agents, hydroxyl group-containing silane coupling agents, carboxyl group-containing silane coupling agents, amide group-containing silane coupling agents, and the like. 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-glycidoxy. Monomeric epoxy groups such as silane coupling agents containing glycidyloxy groups (aliphatic epoxy groups) such as propylmethyldimethoxysilane and silane coupling agents containing alicyclic epoxy groups such as 2-(3,4-epoxycyclohexyl)ethylpropyloxysilane A containing silane coupling agent or a part of the silane compound undergoes a hydrolytic polycondensation reaction, or the silane compound and an alkyl group-containing silane compound such as methyltriethoxysilane, ethyltriethoxysilane, methylpropyloxysilane, ethylpropyloxysilane, etc. Co-condensed oligomer type silane coupling agents etc. are mentioned. 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 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, and 3-mercaptopropylmethyl. A monomeric mercapto group-containing silane coupling agent such as dimethoxysilane, a hydrolysis polycondensation reaction of a part of the silane compound, or the silane compound with methyltriethoxysilane, ethyltriethoxysilane, methylpropyloxysilane, and oligomer type silane coupling agents obtained by co-condensation of alkyl group-containing silane compounds such as ethylpropyloxysilane. 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-methacryloxypropyltrimethoxysilane. -Methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, etc. are mentioned. 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 is included in a silane coupling agent (E), and is 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-aminopropyltrimethoxysilane. Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxy Silane etc. are mentioned. These may be used alone or in combination of two or more.

As said isocyanate group containing silane coupling agent, 3-isocyanate propyl triethoxysilane etc. are mentioned, for example. 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 is included in a silane coupling agent (E), and is not included in an ethylenically unsaturated compound (C).

Among the above silane coupling agents (E), from the viewpoint of excellent reactivity with cationic polymerization components (oxetane compound (A) and epoxy compound (B)) and radical polymerization component (C), an epoxy group-containing silane coupling agent and a vinyl group-containing agent It is preferable to use a silane coupling agent and a (meth)acryloyl group-containing silane coupling agent, and an epoxy group-containing silane coupling agent and a (meth)acryloyl group-containing silane coupling agent are particularly preferable. Further, as the silane coupling agent (E), even a monomeric silane coupling agent may be an oligomeric silane coupling agent partially hydrolyzed and polycondensed. it is desirable

The content of the silane coupling agent (E) is preferably 2 to 50 parts by weight based on 100 parts by weight of the total amount of the oxetane compound (A), the epoxy compound (B) and the ethylenically unsaturated compound (C), particularly preferably is 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 or durability after curing (thermal shock resistance) tends to decrease, and if the content is too small, the adhesiveness improving effect tends not to be sufficiently obtained.

In the adhesive composition of the present invention, in addition to the above components, photosensitizers, polyols, antistatic agents, other adhesives, acrylic resins, urethane resins, rosin, rosin esters, hydrogenated rosin esters, Other additives such as tackifiers such as phenolic resins, aromatic modified terpene resins, aliphatic petroleum resins, alicyclic petroleum resins, styrene resins and xylene resins, plasticizers, colorants, fillers, anti-aging agents, ultraviolet absorbers, and functional colors , a compound that causes coloration or discoloration by irradiation with ultraviolet rays or radiation can be formulated. The compounding amount of these additives is appropriately set for each additive, but, for example, it is preferably 30% by weight or less, 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 manufacturing raw materials of the constituent components of the adhesive composition may be contained.

By using the 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; benzoinmethyl ether, benzoin isopropyl ether, and α,α-dimethoxy-α-phenyl. Benzoin derivatives such as acetphenone; benzophenone, 2,4-dichlorobenzophenone, o-methyl benzoylbenzoate, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzo Benzophenone derivatives such as phenone; Carbonyl compounds such as anthraquinone derivatives such as 2-chloroanthraquinone and 2-methylanthraquinone; 2-chlorothioxanthone, 2-isopropylthioxanthone, and 2,4-diethyl organic sulfur compounds such as thioxanthone derivatives such as thioxanthen-9-one; persulfides, 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. Especially, it is preferable to use an anthracene derivative and a thioxanthone derivative.

It is preferable to contain the said photosensitizer in the range of 0.01-20 weight part, when it is set as 100 weight part of photoinitiator (D). If the content of the photosensitizer is too large, the composition or the resulting adhesive layer tends to be colored, and if too small, the reactivity tends to decrease and no effect can be obtained.

<Adhesive composition>

The adhesive composition of the present invention is obtained by blending and mixing the above components at a predetermined ratio.

In this way, the active energy ray-curable adhesive composition of the present invention is obtained.

The active energy ray-curable adhesive composition of the present invention is cured by active energy ray irradiation to become an adhesive, and can be particularly suitably used as an adhesive for polarizing plates for adhering a polarizer and a protective film.

<Polarizer>

In the polarizing plate of the present invention, a polarizer and a protective film are bonded through an adhesive for polarizing plates. In detail, a protective film was bonded using the adhesive for polarizing plates of the present invention to at least one surface of the polarizer, preferably both surfaces, and usually a liquid adhesive composition for polarizing plates was applied to the polarizer surface or the protective film surface, or both. After applying uniformly to a surface, a polarizing plate can be obtained by bonding and crimping both, and irradiating with an active energy ray.

As the polarizer, a film made of a PVA-based 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, and an aqueous solution of iodine-potassium iiodide or a dichroic solution is used. A uniaxially stretched film dyed with a sexual dye (usually at a stretch ratio of about 2 to 10 times, preferably about 3 to 7 times) is used.

The PVA-based resin is usually prepared 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, unsaturated sulfonic acid salts, etc. , and may contain a component copolymerizable with vinyl acetate. Further, the PVA-based resin includes so-called polyvinyl acetal resins and PVA derivatives such as polybutyral resins and polyvinyl promal resins obtained by reacting PVA with aldehydes in the presence of an acid.

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

When coating the adhesive composition of the present invention on a polarizer or protective film, for example, a reverse coater, a gravure coater (direct, reverse or offset), a reverse coater, a roll coater, a dicota, a bar coater, a rod coater, etc. It can be used or coated by a dipping method.

In the case of bonding and compression, 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 rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, electromagnetic waves such as X-rays and γ rays, electron beams, proton rays, neutron rays, etc. can be used, but the curing speed and availability of irradiation equipment Ultraviolet light is preferable from the viewpoint of ease of use, price, and the like.

A high-pressure mercury-vapor lamp, an electrodeless lamp, an ultra-high-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 performing the ultraviolet irradiation.

The ultraviolet irradiation is usually performed under conditions of 2 to 3000 mJ/cm 2 , preferably 10 to 2000 mJ/cm 2 , and more preferably 20 to 1000 mJ/cm 2 .

In particular, in the case of the high-pressure mercury lamp, it is usually 5 to 3000 mJ/cm 2 , for example, and preferably 50 to 2000 mJ/cm 2 .

Moreover, in the case of the electrodeless lamp, it is usually carried out under conditions of, for example, 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, and after coating 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 electron beam irradiation, it is preferable to use an electron beam having energy in the range of, for example, 50 to 1000 keV, and to set the irradiation amount to 2 to 50 Mrad.

Although the irradiation direction of the said active energy ray (ultraviolet ray, an electron beam, etc.) can be irradiated in arbitrary suitable directions, it is preferable to irradiate from the transparent protective film side from a viewpoint of preventing deterioration of a polarizer.

The thickness of the adhesive layer in the polarizing plate of the present invention obtained by the above is usually 0.1 to 10 μm, preferably 0.2 to 5 μm, particularly preferably 0.3 to 3 μm, and still more preferably 0.5 to 2 μm. If the thickness is too thin, the cohesive force of the adhesive itself may not be obtained, so that adhesive strength may not be obtained, and if the thickness is too thick, the workability of the polarizing plate tends to deteriorate due to cracks 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 bonding various protective films for polarizing plates and polarizers, and exhibits extremely excellent adhesiveness.

(Example)

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 addition, 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-ethyloxetan 3-yl)methoxy]methyl}oxetane (an oxetane compound having two oxetanyl groups in the molecule: manufactured by Toagosei "Aronoc Setan OXT-221")

[Epoxy compound (B)]

[Aliphatic Epoxy Compound (B1)]

(B1-1) Neopentyl glycol diglycidyl ether ("EX-211" manufactured by Nagase ChemteX Co., Ltd.)

[Aromatic Epoxy Compound (B2)]

(B2-1) Bisphenol F type epoxy resin ("jER806" manufactured by Mitsubishi Chemical Corporation)

[ethylenically unsaturated compound (C)]

(C-1) Neopentylglycol 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 Sun-Apro Co., Ltd.)

[Radical Photopolymerization Initiator (D2)]

(D2-1) 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (“IrgacureTPO” manufactured by BASF)

[Silane coupling agent (E)]

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

[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 and mixing each of the above ingredients in the ratio shown in Table 1 described later. The obtained active energy ray-curable adhesive composition was used as an adhesive composition for polarizing plates, and evaluated as follows.

<Manufacture of polarizer>

First, a PVA film having a thickness of 60 µm was stretched 1.5 times while being immersed in a water bath at a water temperature of 30°C. Subsequently, it was stretched 1.3 times while being immersed for 240 seconds in a dye bath (30°C) composed of 0.2 g/L of iodine and 15 g/L of potassium iodide. Further, while immersing 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, boric acid treatment was performed over 5 minutes while uniaxially stretching 3.08 times at the same time. Then, it dried at 90 degreeC and manufactured the polarizer of 6 times the total draw ratio.

<Production of polarizing plate test piece>

A TAC film (manufactured by Fujifilm, trade name “Fujitac”) with a size of 200 mm × 150 mm and a thickness of 60 μm, and a cyclic olefin resin (COP) film with a size of 200 mm × 150 mm and a thickness of 50 μm (manufactured by Nippon Zeon Corporation, trade name “ ZEONOR”), the adhesive composition obtained above was coated with a bar coater to a film thickness of 3 μm to obtain an adhesive composition film. Then, each adhesive composition layer film was laminated on both sides of the polarizer having a size of 180 mm × 120 mm, respectively, and bonded at a nip pressure of 2 MPa using a roll machine to obtain a laminated film (layer structure of laminated film: TAC film / polarizer / COP film). ).

Next, from the COP film side of the laminated film, UV irradiation was performed 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), and the adhesive composition was cured to cure the polarizing plate. produced a test piece.

Performance evaluation was performed as follows using the polarizing plate test piece obtained above.

<Performance evaluation>

[curability]

The interface between the polarizer and the TAC film was peeled with a cutter knife, and the tackiness of the peeled portion was confirmed with a finger (touch).

(Evaluation standard)

○… There was no choice left.

△… It doesn't leave tackiness, but there are some finger marks.

×… Tackiness remained.

[adhesion strength]

A polarizing plate test piece was cut into 120 mm × 25 mm, and the adhesion state between the TAC film and the polarizer and the COP film and the polarizer when stress was applied in the 90° direction was evaluated according to the following criteria.

(Evaluation standard)

◎... It adhered particularly strongly.

○… It was firmly attached.

△… was weakly attached.

×… did not stick

[Durability (thermal shock resistance)]

A test piece was cut into 100 mm x 100 mm, and subjected to a thermal shock test in which a cycle of leaving it at -40°C for 30 minutes and then leaving it at 85°C for 30 minutes was repeated 100 times. After the test, evaluation was made according to the following criteria.

(Assessment Methods)

○… No defects were observed at all.

△… A slight appearance defect (a short crack occurred in the polarizer layer to the extent that the display was not affected) was confirmed.

×… A defect in appearance (a penetration crack occurred in the polarizer layer) was confirmed.

From the above results, Examples 1 to 10 containing an oxetane compound (A), 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 has good curability, has excellent adhesion between the polarizer and the protective film, and is also excellent in durability. From this, it turns out that it is suitable for practical use as an adhesive composition for polarizing plates excellent in balance in various performances.

In contrast, Comparative Example 1 containing no aliphatic epoxy compound (B1) was inferior in adhesiveness, and Comparative Example 2 containing no oxetane compound (A) was inferior in both curability and adhesiveness. Comparative Example 3, which is poor and does not contain an ethylenically unsaturated compound (C), is inferior in curability and was not used for practical use at all. Further, in Comparative Example 4, Comparative Example 5, and Comparative Example 6, which contain the oxetane compound (A), the epoxy compound (B), and the ethylenically unsaturated compound (C), but the content of the epoxy compound (B) is too low, Sufficient adhesiveness could not be obtained. Moreover, in Comparative Example 7 in which the content of the epoxy compound (B) was too high, curability and durability were poor. From these things, it can be said that the adhesive composition of a comparative example fails to satisfy all of various performances, and cannot provide for practical use as an adhesive composition for polarizing plates, etc.

From the above, it can be seen that the adhesive composition of the present invention is very excellent especially for adhesive applications for polarizing plates.

About the said Example, although it showed about the specific form in this invention, the said Example is only a mere illustration and is not interpreted limitedly. Various modifications obvious to those skilled in the art are intended to fall within the scope of the present invention.

The adhesive composition of this invention and the adhesive composition for polarizing plates which consist of the said adhesive composition are excellent in the adhesiveness of a polarizer and a protective film, and are very suitable for bonding of various protective films for polarizing plates and polarizers. In addition, in addition to adhesiveness, it is excellent in well-balanced curability, water resistance of a polarizing plate, durability, and especially thermal shock resistance. Moreover, the adhesive composition of this invention can also be used for bonding of various optical films or sheets, electronic parts, precision instruments, packaging materials, display materials, etc. other than the said adhesive use for polarizing plates, for example.

Claims (9)

In the 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 epoxy compound (B) contains an aliphatic epoxy compound (B1) and an aromatic epoxy compound (B2),
The content ratio (B1/B2) of the aliphatic epoxy compound (B1) to the aromatic epoxy compound (B2) is 33/67 to 90/10 in weight ratio,
An active energy ray-curable adhesive, characterized in that the content of the epoxy compound (B) is 40 to 80% by weight relative to the total amount of the oxetane compound (A), the epoxy compound (B) and the ethylenically unsaturated compound (C) composition. The method of claim 1,
Characterized in that 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 in weight ratio An active energy ray-curable adhesive composition. The method of claim 1,
An active energy ray-curable adhesive composition characterized in that the content ratio (A/B) of the oxetane compound (A) to the epoxy compound (B) is 10/90 to 60/40 in weight ratio. According to claim 1 or 2,
The active energy ray-curable adhesive composition characterized in that the photopolymerization initiator (D) contains a photocationic polymerization initiator (D1) and a photoradical polymerization initiator (D2). The method of claim 4,
Active energy ray-curable adhesive composition, characterized in that 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. According to claim 1 or 2,
An active energy ray-curable adhesive composition characterized by further containing a silane coupling agent (E). An adhesive composition for polarizing plates characterized by comprising the active energy ray-curable adhesive composition according to claim 1 or 2. The adhesive for polarizing plates characterized by being a hardened|cured material of the adhesive composition for polarizing plates of Claim 7. In the polarizing plate having the adhesive for polarizing plates according to claim 8, the polarizer and the protective film, the polarizing plate characterized in that the polarizing plate and the protective film are bonded together with the adhesive for polarizing plates.