JP6740897B2 - Active energy ray-curable adhesive composition, polarizing plate adhesive composition, polarizing plate adhesive and polarizing plate using the same - Google Patents

Description

The present invention relates to an active energy ray-curable adhesive composition, a polarizing plate adhesive composition, a polarizing plate adhesive and a polarizing plate using the same, and more specifically, a polarizing plate used in a liquid crystal display device or the like. 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, which are suitable for laminating a constituent polarizer and a protective film.

Liquid crystal display devices are widely used as image display devices for liquid crystal televisions, computer displays, mobile phones, digital cameras, and the like. Such a liquid crystal display device has a structure 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 on this as required.

Conventionally, a polarizing plate has a constitution in which a protective film is attached to at least one surface, preferably both surfaces, of a polarizer made of a polyvinyl alcohol film (hereinafter, polyvinyl alcohol is abbreviated as “PVA”). There is. Here, as the polarizer, a dichroic material such as iodine is dispersed and adsorbed in a PVA-based film formed by using a PVA-based resin having a high saponification degree, and preferably, cross-linking such as boric acid is further performed. A uniaxially stretched PVA-based film cross-linked with an agent is widely used. Since such a polarizer is a uniaxially stretched PVA-based film, it tends to shrink under high humidity. Therefore, a protective film is attached to the polarizer for the purpose of supplementing moisture resistance and strength.

As such a protective film, a thermoplastic resin such as a cellulose resin, a polycarbonate resin, a cyclic polyolefin resin, a (meth)acrylic resin, and a polyester resin may be used for the transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, and the like. Although it is used because of its excellent properties, 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, and as such an adhesive, from the viewpoint of adhesiveness to the polarizer having a hydrophilic surface, a PVA-based resin aqueous solution, particularly the same as the polarizer is used. A PVA-based resin aqueous solution (PVA-based adhesive) containing a high-saponification PVA-based resin as a main component is preferably used.

By the way, in recent years, there has been a demand for a thinner polarizing plate, and in place of a triacetyl cellulose (TAC) film which has been most commonly used as a protective film, an acrylic film or a cyclic polyolefin resin (COP) has been replaced. ) Films have come to be used, however, in the protective film which replaces these triacetyl cellulose (TAC) films, it is impossible to firmly bond with a polarizer using a conventional PVA-based adhesive. .. Therefore, as an alternative to the PVA adhesive, various adhesives suitable for bonding protective films such as acrylic films and cyclic polyolefin resin (COP) films have been developed.

For example, in Patent Document 1, an oligomer having at least one α,β-unsaturated double bond group in the molecule and an α,β-unsaturation having a ring structure containing one or more nitrogen atoms in the molecule. Saturated double bond group-containing compounds (excluding those corresponding to the above oligomer) and α,β-unsaturated double bond group containing compounds having a ring structure containing no heteroatom in the molecule (however, the above oligomer (Excluding those corresponding to the above) and an active energy ray-polymerizable resin composition as an essential component. And, it is described that, by using an active energy ray-polymerizable adhesive containing the active energy ray-polymerizable resin composition, regardless of the type of various optical films, adhesion and adhesion can be performed easily and firmly. ..

JP, 2015-4047, A

However, the active energy ray-polymerizable resin composition disclosed in Patent Document 1 is not sufficiently satisfactory in terms of adhesive strength and durability depending on the recent diversification of use environment and the type of protective film. , Further improvement was desired.

The present invention has been made in view of such circumstances, and is suitable for laminating a polarizer with a protective film for various polarizing plates such as a cyclic olefin resin (COP) film other than triacetyl cellulose (TAC). And an active energy ray-curable adhesive composition capable of obtaining an adhesive having excellent adhesive strength, a polarizing plate adhesive composition, a polarizing plate adhesive, and a polarizing plate using the same. is there.

However, as a result of intensive studies conducted by the present inventors in view of such circumstances, in the active energy ray-curable adhesive composition, the unsaturated compound having one ethylenically unsaturated group is mainly used as the photopolymerizable compound. It has been found that by adding polyurethane as a component, it is possible to obtain an adhesive having an excellent adhesive force as compared with the conventional one. This is because the presence of polyurethane, which is a high molecular weight component that does not participate in the curing reaction, reduces the crosslink density after curing, suppresses curing shrinkage, and also prevents the urethane bond or terminal hydroxyl group of the polyurethane from the base material or It is presumed that this is because hydrogen bonds with the hydroxyl groups of the polarizer occur.

That is, the present invention is a reaction product of an unsaturated compound (A) having one ethylenically unsaturated group , a polyvalent isocyanate compound (b1) and a polyol compound (b2), having a weight average molecular weight of The first gist is an active energy ray-curable adhesive composition containing 3,000 to 40,000 polyurethane (B).

Further, the second aspect of the present invention is a polarizing plate adhesive composition containing the above active energy ray-curable adhesive composition. A third aspect of the present invention is a polarizing plate adhesive which is a cured product of the polarizing plate adhesive composition. A fourth aspect is a polarizing plate in which a polarizer and a protective film are attached to each other via the polarizing plate adhesive.

The active energy ray-curable adhesive composition of the present invention is a reaction product of an unsaturated compound (A) having one ethylenically unsaturated group , a polyvalent isocyanate compound (b1) and a polyol compound (b2). Since it contains the polyurethane (B) having a weight average molecular weight of 3,000 to 40,000, which is a product, it is possible to firmly adhere various protective films for polarizing plates and polarizers.

Moreover, when the content of the polyurethane (B) is 5 to 60 parts by weight with respect to 100 parts by weight of the unsaturated compound (A) having one ethylenically unsaturated group, various protective films for polarizing plates. And the polarizer can be bonded more firmly.

When the unsaturated compound (A) having one ethylenically unsaturated group contains the hydroxyl group-containing (meth)acrylate compound (A1), various protective films for polarizing plates and the polarizer are more firmly bonded. be able to.

When the unsaturated compound (A) having one ethylenically unsaturated group contains the alicyclic structure-containing (meth)acrylate compound (A2), various protective films for polarizing plates and polarizers are further strengthened. It can be bonded and the durability of the adhesive is improved.

When the content weight ratio of the hydroxyl group-containing (meth)acrylate compound (A1) to the alicyclic structure-containing (meth)acrylate compound (A2) is (A1)/(A2)=0.5 to 20, Various protective films for polarizing plates and polarizers can be bonded more firmly.

Since the weight average molecular weight of the polyurethane (B) it is 3,000 to 40,000, can be bonded to the polarizer various protective film for a polarizing plate even more firmly.

When the polyol compound (b2) is at least one of a polyether polyol and a polyester polyol, various protective films for a polarizing plate and a polarizer can be bonded more firmly.

When the polyether-based polyol is a polyether polyol having an oxyalkylene group having 4 to 7 carbon atoms, various protective films for polarizing plates and polarizers can be more firmly bonded.

The adhesive composition for a polarizing plate containing the active energy ray-curable adhesive composition has a high polarizing plate production efficiency because it does not require a drying step, and is excellent in the adhesive force between the polarizer and the protective film. A polarizing plate can be obtained.

Next, modes for carrying out the present invention will be specifically described, but the present invention is not limited thereto.

The active energy ray-curable adhesive composition of the present invention (hereinafter sometimes abbreviated as “adhesive composition”) contains an unsaturated compound (A) having one ethylenically unsaturated group as a main component, Further, it contains polyurethane (B). Hereinafter, each component of the adhesive composition will be described in order.

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

<Unsaturated compound (A) having one ethylenically unsaturated group>
The unsaturated compound (A) having one ethylenically unsaturated group (hereinafter, may be abbreviated as “monofunctional monomer (A)”) has one (meth)acryloyl group in the molecule. It is preferable to use a (meth)acrylic compound.

Examples of the (meth)acrylic compound having one (meth)acryloyl group in the molecule include alkyl (meth)acrylate compounds, polar group-containing (meth)acrylic compounds, and alicyclic structure-containing (meth) compounds. Examples thereof include an acrylate compound (A2), an aromatic ring-containing (meth)acrylate compound, and a (meth)acrylic compound having a reactive functional group other than a (meth)acryloyl group and a (meth)acryloyl group in the molecule. These (meth)acrylic compounds can be used alone or in combination of two or more.

Examples of the alkyl (meth)acrylate compound include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, 2- Examples thereof include ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate.

Examples of the polar group-containing (meth)acrylic compound include a carboxyl group-containing (meth)acrylic compound, a hydroxyl group-containing (meth)acrylate compound (A1), a nitrogen atom-containing (meth)acrylic compound, and an alkoxy group-containing ( Examples thereof include (meth)acrylate compounds.

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 adduct of acrylic acid (for example, 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 (for example, 2-acryloyloxyethyl succinic acid monoester, 2-methacryloyloxyethyl succinic acid monoester, 2-acryloyloxyethyl phthalic acid monoester, 2-methacryloyloxyethyl phthalic acid monoester, 2-acryloyloxyethyl hexahydrophthalic acid monoester Ester, 2-methacryloyloxyethyl hexahydrophthalic acid monoester, etc.) and the like.

Examples of the hydroxyl group-containing (meth)acrylate compound (A1) include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, and 6-hydroxyhexyl. Hydroxyalkyl (meth)acrylate such as (meth)acrylate,
Caprolactone-modified (meth)acrylate compounds such as caprolactone-modified 2-hydroxyethyl (meth)acrylate, ethylene glycol mono(meth)acrylate, propylene glycol mono(meth)acrylate, pentanediol mono(meth)acrylate, and hexanediol mono( Mono(meth)acrylate compounds of dihydric alcohols such as (meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, polyethylene glycol mono( (Meth)acrylate, mono(meth)acrylate of dipropylene glycol, mono(meth)acrylate of tripropylene glycol, and mono(meth)acrylate compound of polyalkylene glycol such as mono(meth)acrylate of polypropylene glycol,
In addition, a primary hydroxyl group-containing (meth)acrylate compound such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid;
Secondary hydroxyl group-containing (meth)acrylate compounds such as 2-hydroxypropyl (meth)acrylate and 2-hydroxybutyl (meth)acrylate;
Tertiary hydroxyl group (meth)acrylate compounds such as 2,2-dimethyl2-hydroxyethyl (meth)acrylate;
Etc.
Among these hydroxyl group-containing (meth)acrylate compounds (A1), primary hydroxyl group-containing (meth)acrylate compounds are preferable because they easily form hydrogen bonds with the substrate or the polarizer, and hydroxyalkyl (meth)acrylate is particularly preferable. Compounds and mono(meth)acrylate compounds of polyalkylene glycol are preferred.

Examples of the nitrogen atom-containing (meth)acrylic compounds 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)acrylamides such as N,N-dimethyl(meth)acrylamide, 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 group-containing acrylamide such as N-(hydroxymethyl)(meth)acrylamide;
Examples thereof include N-(3-N,N-dimethylaminopropyl)(meth)acrylamide, methylenebis(meth)acrylamide, ethylenebis(meth)acrylamide and the like.
Examples of amino group-containing (meth)acrylic compounds include primary amino group-containing (meth)acrylates such as aminomethyl (meth)acrylate, aminoethyl (meth)acrylate, aminoalkyl (meth)acrylate, and t-butyl. Secondary amino group-containing (meth)acrylate such as aminoethyl (meth)acrylate, ethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc., dialkylaminoalkyl (meth)acrylate, etc. And heterocyclic amine monomers such as tertiary amino group-containing (meth)acrylate and 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. An alkoxyalkyl (meth)acrylate compound 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, octo Polyether chain-containing (meth)acrylate compounds such as xypolyethylene glycol-polypropylene glycol-mono(meth)acrylate, lauroxy polyethylene glycol mono(meth)acrylate, stearoxypolyethylene glycol mono(meth)acrylate,
Etc.

Examples of the alicyclic structure-containing (meth)acrylate compound (A2) include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, dicyclopentanyl (meth). Examples thereof include acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and 2-adamantyl (meth)acrylate.

Examples of the aromatic ring-containing (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)acrylate such as (meth)acrylate and phenoxydipropylene glycol (meth)acrylate; phenoxypolyethylene glycol (meth)acrylate; phenoxypolyethylene glycol-polypropylene glycol-(meth)acrylate;
(Meth)acrylate of p-cumylphenol alkylene oxide adduct, (meth)acrylate of o-phenylphenol alkylene oxide adduct, (meth)acrylate of phenol alkylene oxide adduct and (meth)acrylate of nonylphenol alkylene oxide adduct Etc.

Examples of the (meth)acryl-based compound having a (meth)acryloyl group and a reactive functional group other than the (meth)acryloyl group in the molecule include glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, and 3,4-epoxycyclohexyl. An epoxy group-containing (meth)acrylate compound such as methyl (meth)acrylate,
Vinyl group-containing (meth)acrylate compounds such as 2-(2-vinyloxyethoxy)ethyl (meth)acrylate,
An isocyanate group-containing (meth)acrylate compound such as 2-(meth)acryloyloxyethyl isocyanate
Etc.

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

Among these (meth)acryl-based compounds having one (meth)acryloyl group in the molecule, hydrogen bonding with the substrate (protective film) occurs, and the polar group-containing (meth ) It is preferable to use an acrylic compound, particularly preferably a hydroxyl group-containing (meth)acrylate compound (A1), and further, a hydroxyalkyl (meth)acrylate compound or a polyalkylene glycol mono(meth)acrylate compound. It is preferable to use a compound, particularly preferably a hydroxyalkyl (meth)acrylate compound, and particularly preferably 4-hydroxybutyl (meth)acrylate.

The content ratio of the hydroxyl group-containing (meth)acrylate compound (A1) in the whole monofunctional monomer (A) is preferably 30 to 90% by weight, particularly preferably 40 to 85% by weight, and further preferably 70 to It is 85% by weight. If the content ratio is too high, the durability when the adhesive composition is used as an adhesive tends to decrease, and if it is too low, the adhesion to the substrate tends to decrease.

Further, in the present invention, it is preferable to use the alicyclic structure-containing (meth)acrylate compound (A2) from the viewpoint of the durability of the adhesive and the adhesiveness to the substrate, and dicyclopentanyl (meth) is used. Acrylate is particularly preferred.

When the above-mentioned alicyclic structure-containing (meth)acrylate compound (A2) is used, the content ratio with respect to the entire monofunctional monomer (A) is usually 1 to 50% by weight, preferably 5 to 30% by weight, particularly preferably It is 10 to 25% by weight. If the content ratio is too high, the adhesiveness to the polarizer tends to decrease, and if it is too low, the durability tends to decrease.

When the above-mentioned hydroxyl group-containing (meth)acrylate compound (A1) and alicyclic structure-containing (meth)acrylate compound (A2) are used in combination, the alicyclic structure-containing (meth) of the hydroxyl group-containing (meth)acrylate compound (A1) ) The content weight ratio with respect to the acrylate compound (A2) is preferably (A1)/(A2)=0.5 to 20, particularly preferably 1 to 10, and further preferably 2 to 5.

In the present invention, the content of the monofunctional monomer (A) in the entire adhesive composition is preferably 30 to 98% by weight, more preferably 40 to 95% by weight, particularly preferably 50 to 90% by weight. is there. If the content is too large, the durability tends to decrease, and if it is too small, the viscosity of the composition tends to be high and the coatability tends to deteriorate.

The adhesive composition of the present invention is characterized by containing the monofunctional monomer (A) and the polyurethane (B).

<Polyurethane (B)>
The polyurethane (B) can be obtained by reacting the polyvalent isocyanate compound (b1) and the polyol compound (b2). In the present invention, polyurethane (B) does not include a urethane (meth)acrylate compound.

Examples of the polyvalent isocyanate compound (b1) include aromatic compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate. System polyisocyanate;
Aliphatic polyisocyanates such as pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, lysine triisocyanate;
Alicyclic polyisocyanates such as hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane 4,4′-diisocyanate;
Alternatively, a trimer compound or multimer compound of these polyisocyanates, an allophanate type polyisocyanate, a burette type polyisocyanate, a water dispersion type polyisocyanate and the like can be mentioned.

Among these, from the viewpoint of stability during urethanization reaction, diisocyanate compounds are preferable, in particular, aliphatic diisocyanates and alicyclic diisocyanates are preferably used, and more preferably isophorone diisocyanate in that curing shrinkage is small, Hydrogenated xylylene diisocyanate, norbornene diisocyanate and dicyclohexylmethane 4,4′-diisocyanate are used, and particularly preferably dicyclohexylmethane 4,4′-diisocyanate and isophorone diisocyanate are used because of their excellent reactivity and versatility.

Examples of the polyol-based compound (b2) include polyether-based polyols, polyester-based polyols, polycarbonate-based polyols, polyolefin-based polyols, polybutadiene-based polyols, (meth)acrylic-based polyols, polysiloxane-based polyols, and the like.

Examples of the polyether polyol include alkylene structure-containing polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol and polyhexamethylene glycol, and random or block copolymerization of these polyalkylene glycols. It can be united.

Examples of the polyester-based polyols include three types of components: a condensation polymerization product of a polyhydric alcohol and a polycarboxylic acid, a ring-opening polymerization product of a cyclic ester (lactone), a polyhydric alcohol, a polycarboxylic acid and a cyclic ester. And the like.

Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylene diol, 1,3-tetramethylene diol, 2-methyl-1,3-trimethylene. Methylene diol, 1,5-pentamethylene diol, neopentyl glycol, 1,6-hexamethylene diol, 3-methyl-1,5-pentamethylene diol, 2,4-diethyl-1,5-pentamethylene diol, glycerin , Trimethylolpropane, trimethylolethane, cyclohexanediols (1,4-cyclohexanediol, etc.), bisphenols (bisphenol A, etc.), sugar alcohols (xylitol, sorbitol, etc.) and the like.

Examples of the polycarboxylic acid include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid and dodecanedioic acid, 1,4 Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, and aromatic dicarboxylic acids such as trimellitic acid.

Examples of the cyclic ester include propiolactone, β-methyl-δ-valerolactone, ε-caprolactone and the like.

Examples of the polycarbonate-based polyol include a reaction product of a polyhydric alcohol and phosgene, a ring-opening polymer of a cyclic carbonic acid ester (alkylene carbonate, etc.), and the like.

Examples of the polyhydric alcohol include the polyhydric alcohols exemplified in the description of the polyester-based polyol, and examples of the alkylene carbonate include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, hexamethylene carbonate and the like. To be

The polycarbonate-based polyol may be a compound having a carbonate bond in the molecule and a hydroxyl group at the terminal, and may have an ester bond as well as the carbonate bond.

Examples of the polyolefin-based polyol include those having a homopolymer or copolymer of ethylene, propylene, butene or the like as a saturated hydrocarbon skeleton, and having a hydroxyl group at the molecular end thereof.

Examples of the polybutadiene-based polyol include those having a copolymer of butadiene as a hydrocarbon skeleton and having a hydroxyl group at its molecular end.
The polybutadiene-based polyol may be a hydrogenated polybutadiene polyol in which all or part of the ethylenically unsaturated groups contained in its structure are hydrogenated.

Examples of the (meth)acrylic polyol include those having at least two hydroxyl groups in the molecule of the polymer or copolymer of (meth)acrylic acid ester. As such (meth)acrylic acid ester, Is, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, (meth)acrylic Examples thereof include alkyl (meth)acrylates such as 2-ethylhexyl acid, decyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate.

Examples of the polysiloxane-based polyol include dimethylpolysiloxane polyol and methylphenylpolysiloxane polyol.

Among these, polyester-based polyols and polyether-based polyols are preferred from the viewpoint of adhesiveness, particularly preferred are polyether-based polyols, and particularly preferred are polyethers having an oxyalkylene group with 4 to 7 carbon atoms, Among them, polytetramethylene glycol is most preferable.

In the present invention, the number average molecular weight of the polyol compound (b2) is preferably 100 to 15,000, more preferably 150 to 10,000, and further preferably 200 to 4,000. If the number average molecular weight is too large, the viscosity of the polyurethane tends to be too high, and if it is too small, the polyurethane becomes hard and sufficient adhesive force tends not to be obtained.

In the present invention, the polyurethane (B) can be produced by reacting the polyvalent isocyanate compound (b1) with the polyol compound (b2), and a known reaction means can be used for the reaction. .. The number of functional groups of the polyvalent isocyanate compound (b1) and the number of functional groups of the polyol compound (b2) are not particularly limited as long as they are bifunctional or more.

The reaction molar ratio between the polyvalent isocyanate compound (b1) and the polyol compound (b2) is, for example, two isocyanate groups in the polyvalent isocyanate compound (b1) and two hydroxyl groups in the polyol compound (b2). When the number is one, the polyisocyanate compound (b1):polyol compound (b2) is about 1:1 to 1:2. In this addition reaction, the polyurethane (B) is obtained by terminating the reaction when the residual isocyanate group content of the reaction system becomes 0.5% by weight or less.

In the reaction between the polyvalent isocyanate compound (b1) and the polyol compound (b2), it is also preferable to use a catalyst for the purpose of promoting the reaction. Examples of the catalyst include dibutyltin dilaurate and trimethyltin hydroxy. , Organo-metal compounds such as tetra-n-butyltin, zinc octenoate, tin octenoate, cobalt naphthenate, stannous chloride, stannic chloride, and other metal salts, triethylamine, benzyldiethylamine, 1,4-diazabicyclo Amines such as [2,2,2]octane, 1,8-diazabicyclo[5,4,0]undecene, N,N,N′,N′-tetramethyl-1,3-butanediamine, and N-ethylmorpholine. -Based catalysts, bismuth nitrate, bismuth bromide, bismuth iodide, bismuth sulfide, etc., organic bismuth compounds such as dibutyl bismuth dilaurate, dioctyl bismuth dilaurate, 2-ethylhexanoic acid bismuth salt, naphthenic acid bismuth salt, bismuth isodecanoate Salt, bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate, bismuth acetate, bismuth ribis neodecanoate, bismuth disalicylate, di gallic acid Organic acid such as acid bismuth salt Bismuth-based catalyst such as bismuth salt, inorganic zirconium, organic zirconium, zirconium-based catalyst such as zirconium simple substance, two or more kinds of catalysts such as zinc 2-ethylhexanoate/zirconium tetraacetylacetonate Among them, dibutyltin dilaurate and 1,8-diazabicyclo[5,4,0]undecene are preferable. These catalysts can be used alone or in combination of two or more.

In the present invention, the above reaction is preferably carried out without a solvent, but an organic solvent having no functional group that reacts with an isocyanate group, for example, ethyl acetate, esters such as butyl acetate, methyl ethyl ketone, methyl isobutyl. Organic solvents such as ketones such as ketones and aromatics such as toluene and xylene may be used. Further, a monomer containing no hydroxyl group may be used as the diluting monomer.

The monomer containing no hydroxyl group is not particularly limited as long as it has no functional group that inhibits the urethanization reaction, and examples thereof include 2-ethylhexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate and dicyclopenta. Examples thereof include nyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, 1,6-hexanediol di(meth)acrylate and tricyclodecane dimethanol di(meth)acrylate.

The reaction temperature in the production of polyurethane (B) is generally 30 to 150°C, preferably 40 to 100°C, and the reaction time is generally 2 to 10 hours, preferably 3 to 8 hours.

Thus, the polyurethane (B) used in the present invention is obtained.
The weight average molecular weight of the polyurethane (B) is usually 3,000 to 40,000 , preferably 4,000 to 40,000 , and particularly preferably 5,000 to 40,000 . If the weight average molecular weight is too large, the viscosity of the polyurethane tends to be too high, or the compatibility tends to be low, and if it is too small, sufficient adhesive force tends not to be obtained.

The above-mentioned weight average molecular weight is a weight average molecular weight in terms of standard polystyrene molecular weight, and a column: Shodex GPC KF-806L (excluded) in a high performance liquid chromatograph (Showa Denko KK, "Shodex GPC system-11 type"). Limiting molecular weight: 2×10 ⁷ , separation range: 100 to 2×10 ⁷ , theoretical plate number: 10,000 plates/piece, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm) It is measured by using a series.

Regarding the viscosity of the polyurethane (B), the viscosity at 60° C. is preferably 1,000 to 200,000 mPa·s, particularly 2,000 to 100,000 mPa·s, and further 4,000 to It is preferably 60,000 mPa·s. If the viscosity is too high, a large amount of diluent must be used, and the workability tends to decrease. If it is too low, the adhesiveness tends to decrease.
The viscosity is measured by an E-type viscometer.

In the present invention, the content of the polyurethane (B) is preferably 5 to 60 parts by weight, particularly preferably 10 to 50 parts by weight, further preferably 15 parts by weight based on 100 parts by weight of the monofunctional monomer (A). ~45 parts by weight. If the content is too large, the curability tends to decrease, and if it is too small, sufficient adhesive force tends not to be obtained.

The content of polyurethane (B) in the entire adhesive composition is preferably 1 to 60% by weight, particularly preferably 5 to 50% by weight, and further preferably 10 to 40% by weight. If the content is too large, the viscosity of the adhesive tends to be too high, or the compatibility tends to be low, and if it is too small, sufficient adhesive force may not be obtained.

<Other ethylenically unsaturated compound (C)>
The adhesive composition of the present invention may further contain other ethylenically unsaturated compound (C). Examples of the other ethylenically unsaturated compounds include, for example, ethylenically unsaturated compounds having two or more ethylenically unsaturated groups (hereinafter sometimes referred to as “polyfunctional monomer”). Moreover, as a polyfunctional monomer, what has two ethylenically unsaturated groups (henceforth "bifunctional monomer" may be described.), and what has three or more ethylenically unsaturated groups (henceforth " Sometimes referred to as "trifunctional or higher functional monomer").

Examples of the bifunctional monomer 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, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth ) Acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, hydroxypivalic acid modified neopentyl glycol di(meth) Di(meth)acrylate having a long-chain or branched-chain structure such as acrylate;
A di(meth)acrylate having an alicyclic structure such as cyclohexanedimethanol di(meth)acrylate, dimethylol dicyclopentane di(meth)acrylate, and tricyclodecane dimethanol di(meth)acrylate;
Di(meth)acrylate having an aromatic ring such as phthalic acid diglycidyl ester di(meth)acrylate;
Alkyl modification of 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, isocyanuric acid ethylene oxide modified di(meth)acrylate, etc. Having a ring structure and having a ring structure, such as a di(meth)acrylate having a ring structure;
Etc.

Examples of trifunctional or higher functional monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meta). ) 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 Alkyl such as (meth)acrylate, 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(meth)acrylate Trifunctional or higher functional (meth)acrylate having a modified structure, trifunctional or higher functional (meth)acrylate having a long-chain or branched chain structure;
Tri(meth)acrylate having a ring structure such as isocyanuric acid ethylene oxide-modified triacrylate;
Etc.

In the present invention, the content of the other ethylenically unsaturated compound (C) is preferably 40% by weight or less, and particularly preferably 1 to 30% by weight based on the whole adhesive composition. If the content is too large, the adhesiveness tends to decrease.

<Photoradical polymerization initiator (D)>
In the present invention, it is preferable to further use the photo radical polymerization initiator (D). Examples of the photoradical polymerization initiator (D) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 4-(2-hydroxyethoxy)phenyl-(. 2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4 Acetophenones such as -morpholinophenyl)butanone and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin Benzoins such as isobutyl ether; benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4′-methyl-diphenyl sulfide, 3,3′,4,4′-tetra(t-butylperoxy) Carbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminium bromide, (4-benzoyl Benzyl)trimethylammonium chloride and other benzophenones; 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 thioxanthones such as mesochloride; 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,6-dimethoxybenzoyl) Examples include acylphosphine oxides such as -2,4,4-trimethyl-pentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; In addition, these radical photopolymerization initiators (D) can be used alone or in combination of two or more kinds.

Among these radical photopolymerization initiators (D), it is preferable to use acylphosphine oxides, particularly 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,6-dimethoxybenzoyl). -2,4,4-trimethyl-pentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide are preferable, and further 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is preferable. Is preferably used.

Further, as these auxiliaries, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler's ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4-dimethylaminobenzoic acid Ethyl, 4-(n-butoxy)ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone It is also possible to use the above together.

The content of the photoradical polymerization initiator (D) is preferably 20 parts by weight or less based on 100 parts by weight of the monofunctional monomer (A), particularly 0.1 to 20 parts by weight, and further 0.1. 5 to 10 parts by weight is preferable. If the content of the photoradical polymerization initiator (D) is too large, the solubility of the photoradical polymerization initiator may decrease, or the durability of the adhesive layer may decrease. If the content of the photo-radical polymerization initiator (D) is too small, curing will be insufficient and the adhesive strength and mechanical strength of the adhesive layer will tend to be reduced.

In the present invention, in addition to the above components, in the range that does not impair the effects of the present invention, photosensitizers, polyols, silane coupling agents, antistatic agents, other adhesives, acrylic resins, urethane resins, 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 a filler, an antiaging agent, an ultraviolet absorber and a functional dye, and a compound that causes coloration or discoloration upon irradiation with ultraviolet rays or radiation can be added. The blending amount of these additives is appropriately set for each additive, but for example, it is preferably 30% by weight or less, and particularly preferably 20% by weight or less based on the whole adhesive composition.
Further, in addition to the above additives, a small amount of impurities and the like contained in the raw materials for manufacturing the constituent components of the adhesive composition may be contained.

By using the photosensitizer, the reactivity can be 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; benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, α,α-dimethoxy-α-phenylacetophenone; benzophenone and 4-methylbenzophenone. , 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4′-bis(dimethylamino)benzophenone, 4,4′-bis(diethylamino)benzophenone and other benzophenone derivatives; 2-chloroanthraquinone, 2-methyl Carbonyl compounds such as anthraquinone derivatives such as anthraquinone; organic sulfur compounds such as thioxanthone derivatives such as 2-chlorothioxanthone, 2-isopropylthioxanthone, and 2,4-diethylthioxanthen-9-one; persulfides, redox compounds, azo And diazo compounds, halogen compounds, photo-reducing dyes and the like. These may be used alone or in combination of two or more. Among them, anthracene derivatives and thioxanthone derivatives are preferably used.
The photosensitizer is preferably contained in the range of 0.01 to 20 parts by weight with respect to 100 parts by weight of the radical photopolymerization initiator (D). If the content of the photosensitizer is too high, the composition and the adhesive layer obtained tend to be colored, and if it is too low, the reactivity is lowered and the sensitizing effect tends to be difficult to obtain.

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

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

Examples of the silane coupling agent include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyl. Epoxy group-containing silane coupling agent such as triethoxysilane; 3-(meth)acryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 3-( (Meth)acryloxypropyltriethoxysilane and other (meth)acryloyl group-containing silane coupling agents; vinyltrimethoxysilane, vinyltriethoxysilane and other vinyl group-containing silane coupling agents; N-2-(aminoethyl)-3 -Aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3 -Aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane and other amino group-containing silane coupling agents; 3- Mercapto group-containing silane coupling agents such as mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane; isocyanurate group-containing silane coupling agents such as tris-(trimethoxysilylpropyl)isocyanurate; 3-isocyanatopropyltriethoxy Isocyanate group-containing silane coupling agents such as silane; and the like. These may be used alone or in combination of two or more. Among them, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth ) It is preferable to use acryloxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, vinyltrimethoxysilane, or vinyltriethoxysilane.

As the silane coupling agent, the monomer type silane compound as described above may be used, or an oligomer type silane compound partially hydrolyzed and polycondensed may be used.

The content of the silane coupling agent is preferably 0.1 to 10 parts by weight, and particularly preferably 0.1 to 10 parts by weight based on 100 parts by weight of the total amount of the monofunctional monomer (A) and the polyurethane (B). 5 parts by weight.

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

Further, the adhesive composition of the present invention may contain a solvent, or may be used as a solventless composition, it is possible to omit the step of drying the solvent in the adhesive, Since there is no residual solvent, it is preferable to use the composition as a solvent-free composition because the resulting adhesive has excellent durability.

The adhesive composition of the present invention is one that is cured by irradiation with active energy rays and functions as an adhesive, and can be suitably used as an adhesive for polarizing plates for adhering a polarizer and a protective film. is there.

<Polarizing plate>
The polarizing plate of the present invention is one in which a polarizer and a protective film are bonded together via a polarizing plate adhesive, and specifically, at least one surface, preferably both surfaces of the polarizer is used for the polarizing plate of the present invention. A protective film is adhered using an adhesive, and usually, a liquid-phase polarizing plate adhesive composition is uniformly applied to a polarizer surface or a protective film surface, or both surfaces, and then both are adhered to each other. A polarizing plate is formed by laminating, press-bonding, heating and drying if necessary, and then irradiating with active energy rays.

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

The PVA-based 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. In addition, examples include so-called polyvinyl acetal resins such as polybutyral resins and polyvinyl formal resins, and polyvinyl alcohol derivatives obtained by reacting PVA-based resins 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. The adhesive composition of the present invention is a TAC film. It is preferably used for any protective film selected from a film, an acrylic film, a cycloolefin film, a polyethylene terephthalate (PET) film and the like.

In applying the adhesive composition of the present invention onto a polarizer or a protective film, for example, a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, The coating can be performed by using a rod coater or the like, or by a dipping method.

A roll laminator or the like can be used in the above-mentioned bonding and pressure bonding, and the pressure is usually selected from the range of 0.1 to 10 MPa.

As the active energy rays, light rays such as deep ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, etc., electromagnetic waves such as X-rays, γ-rays, electron rays, proton rays, neutron rays, etc. can be used. Curing by ultraviolet irradiation is advantageous in terms of availability and price.

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 when performing the ultraviolet irradiation.
The ultraviolet irradiation is usually carried out under the conditions of ^{2 to} 3000 mJ/cm ² , preferably 10 to 2000 mJ/cm ² .

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

The irradiation time varies depending on the type of the light source, the distance between the light source and the coating surface, the coating thickness, and other conditions, but it is usually 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 of 2 to 50 Mrad is preferable.

The active energy ray (ultraviolet ray, electron beam, etc.) can be emitted from any appropriate direction, but it is preferable to irradiate from the transparent protective film side from the viewpoint of preventing deterioration of the polarizer.

The thickness of the adhesive layer in the polarizing plate of the present invention obtained as described above is usually 0.01 to 70 μm, preferably 0.1 to 30 μm, particularly preferably 0.2 to 20 μm, and further preferably 0.5 to 10 μm. Is. If the thickness is too thin, the cohesive force of the adhesive force itself cannot be obtained and the adhesive strength tends to be unobtainable, and if it is too thick, the workability of the polarizing plate tends to be deteriorated due to cracking during punching.

The adhesive composition of the present invention is suitable for laminating various protective films for polarizing plates and polarizers, and exhibits extremely excellent adhesiveness.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, "part" and "%" mean weight basis.
The weight average molecular weight of the polyurethane (B) in the following examples was measured according to the method described above.
The following components were prepared prior to the examples.
<Unsaturated compound (A) having one ethylenically unsaturated group>
(A1-1) 4-hydroxybutyl acrylate (“4-HBA” manufactured by Osaka Organic Chemical Co., Ltd.)
(A2-1) Dicyclopentanyl acrylate ("FA-513AS" manufactured by Hitachi Chemical Co., Ltd.)
(A-1) 2-ethylhexyl acrylate ("2-ethylhexyl acrylate" manufactured by Mitsubishi Chemical Corporation)
(A-2) Benzyl acrylate (“Viscoat #160” manufactured by Osaka Organic Chemical Co., Ltd.)
(A-3) Tetrahydrofurfuryl acrylate (“Viscoat #150” manufactured by Osaka Organic Chemical Co., Ltd.)

<Polyurethane (B)>
[Production of polyurethane (B-1)]
In a four-necked flask equipped with a thermometer, a stirrer, a water-cooled condenser, and a nitrogen gas blowing port, 10.1 g (0.045 mol) of isophorone diisocyanate (b1-1) and a bifunctional polyester polyol having a number average molecular weight of 2,000. (Hydroxyl value 57 mgKOH/g) (b2-1) 89.9 g (0.045 mol), and 0.01 g of dibutyltin dilaurate as a reaction catalyst were charged and reacted at 60° C., and the residual isocyanate group became 0.1%. At that point, the reaction was terminated to obtain polyurethane (B-1) (weight average molecular weight: 36,000).

[Production of polyurethane (B-2)]
In the method for producing polyurethane (B-1), 21.8 g (0.098 mol) of isophorone diisocyanate (b1-1) is used, and instead of the bifunctional polyester polyol having a number average molecular weight of 2,000, a trifunctional compound having a number average molecular weight of 600 is used. Polyurethane (B-2) (weight average molecular weight: 25,000) was obtained in the same manner except that 78.2 g (0.122 mol) of polyester polyol (hydroxyl value 264 mgKOH/g) (b2-2) was used. ..

[Production of polyurethane (B-3)]
In the method for producing polyurethane (B-1), 38.7 g (0.174 mol) of isophorone diisocyanate (b1-1) is used, and instead of the bifunctional polyester polyol having a number average molecular weight of 2,000, a polytetraene having a number average molecular weight of 250 is used. Polyurethane (B-3) (weight average molecular weight; 4) was used in the same manner except that 61.3 g (0.232 mol) of methylene ether glycol (polyether polyol) (hydroxyl value 425 mgKOH/g) (b2-3) was used. , 400) was obtained.

[Production of polyurethane (B-4)]
In the method for producing polyurethane (B-3), 39.8 g (0.152 mol) of dicyclohexylmethane 4,4′-diisocyanate (b1-2) is used instead of isophorone diisocyanate, and polytetramethylene ether glycol having a number average molecular weight of 250 is used. (Polyether polyol) (hydroxyl value 425 mg KOH/g) (b2-3) was used in the same manner except that 60.2 g (0.228 mol) was used, and polyurethane (B-4) (weight average molecular weight: 5,800) was used. Got

[Production of polyurethane (B-5)]
In the method for producing polyurethane (B-4), 23.4 g (0.089 mol) of dicyclohexylmethane 4,4′-diisocyanate (b1-2) is used instead of polytetramethylene ether glycol having a number average molecular weight of 250. Polytetramethylene ether glycol (polyether polyol) having a molecular weight of 650 (hydroxyl value 163 mgKOH/g) (b2-4) was used in the same manner except that 76.6 g (0.111 mol) was used, and polyurethane (B-5) ( Weight average molecular weight; 17,000) was obtained.

[Production of polyurethane (B-6)]
In the method for producing polyurethane (B-5), 16.3 g (0.097 mol) of hexamethylene diisocyanate (b1-3) is used instead of dicyclohexylmethane 4,4′-diisocyanate, and polytetramethylene ether having a number average molecular weight of 650. Polyurethane (B-6) (weight average molecular weight; 14,000) was similarly used except that 83.7 g (0.121 mol) of glycol (polyether polyol) (hydroxyl value 163 mg KOH/g) (b2-4) was used. ) Got.

[Production of polyurethane (B-7)]
In the polyurethane (B-5), 20.5 g (0.09 mol) of isophorone diisocyanate in place of dicyclohexylmethane 4,4′-diisocyanate, polytetramethylene ether glycol (polyether polyol) having a number average molecular weight of 650 (hydroxyl value) Polyurethane (B-7) (weight average molecular weight; 14,000) was obtained in the same manner except that 79.5 g (0.12 mol) of 163 mg KOH/g) (b2-4) was used.

The composition and weight average molecular weight of each polyurethane (B) produced above are shown in Table 1 below.

[Production of Urethane Acrylate (U-1)]
In a four-necked flask equipped with a thermometer, a stirrer, a water-cooled condenser, and a nitrogen gas inlet, 17 g (0.076 mol) of isophorone diisocyanate (b1-1) and a bifunctional polyester polyol having a number average molecular weight of 2,000 ( Hydroxyl value 57 mg KOH/g) (b2-1) 74 g (0.037 mol), hydroquinone methyl ether 0.02 g as a polymerization inhibitor, and dibutyltin dilaurate 0.02 g as a reaction catalyst were charged and reacted at 60° C. for 2 hours, Furthermore, 9 g (0.076 mol) of 2-hydroxyethyl acrylate was charged and reacted at 60° C. for 3 hours, and when the residual isocyanate group was 0.3% or less, the reaction was terminated, and urethane acrylate (U-1) (Weight average molecular weight: 15,000) was obtained.

[Production of Urethane Acrylate (U-2)]
In the urethane acrylate (U-1), 36 g (0.14 mol) of dicyclohexylmethane 4,4′-diisocyanate (b1-2) was used instead of isophorone diisocyanate, instead of the bifunctional polyester polyol having a number average molecular weight of 2,000. Use 48 g (0.07 mol) of polytetramethylene ether glycol (polyether polyol) having a number average molecular weight of 650 (hydroxyl value 163 mg KOH/g) (b2-4) and 16 g (0.14 mol) of 2-hydroxyethyl acrylate. To obtain urethane acrylate (U-2) (weight average molecular weight: 4,000).

The composition and weight average molecular weight of each urethane (meth)acrylate compound (U) produced above are shown in Table 2 below.

<Photoradical polymerization initiator (D)>
(D-1) 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (acylphosphine oxides: Irgacure TPO, manufactured by BASF)

<Examples 1 to 13 , Comparative Examples 1 and 2>
[Preparation of active energy ray-curable adhesive composition]
A monofunctional monomer (A) and a polyurethane (B) were simultaneously charged into a preparation flask at a ratio shown in Tables 3 and 4 below, and while stirring them, the liquid temperature was heated to 60° C. to completely Mixing was continued for 1 hour until dissolved. Then, after cooling to room temperature (23° C.), 5 parts of a radical photopolymerization initiator (D) was charged and mixed to obtain an active energy ray-curable adhesive composition.
The active energy ray-curable adhesive composition thus obtained was used as a polarizing plate adhesive composition, and evaluated as follows. The results are shown in Tables 3 and 4.

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

<Production of polarizing plate test piece>
Triacetyl cellulose (TAC) film having a size of 200 mm×100 mm and a thickness of 60 μm (trade name “Fujitac” manufactured by Fuji Film Co., Ltd.) and a cyclic olefin resin (COP) film having a size of 200 mm×100 mm and a thickness of 50 μm (Zeon Corporation) The adhesive composition for a polarizing plate obtained above was applied to a commercially available product under the trade name "ZEONOR") with a bar coater so that the film thicknesses shown in Tables 3 and 4 below would be obtained. The film with each adhesive composition layer was laminated on both sides of the above-mentioned polarizer having a size of 180 mm×80 mm, and laminated with 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, UV irradiation was performed from the COP film side of the laminated film with an ultraviolet irradiation device equipped with a high-pressure mercury lamp at a peak illuminance of 130 mW/cm ² and an integrated exposure dose of 900 mJ/cm ² (365 nm), to obtain an adhesive composition. The cured product was used as a polarizing plate test piece.
Using the polarizing plate test piece obtained above, performance evaluation was performed as follows.

[Adhesiveness]
The polarizing plate test piece was cut into 120 mm×25 mm, and the adhesiveness between the TAC film and the polarizer and the COP film and the polarizer when a stress of 90° was applied was evaluated according to the following criteria.
(Evaluation criteria)
○: Strongly adhered △: Weakly adhered ×: Not adhered

From the above results, the adhesive compositions of Examples 1 to 13 containing the unsaturated compound (A) having one ethylenically unsaturated group and the polyurethane (B) firmly bond the polarizer and the protective film. I was able to.

On the other hand, the adhesive compositions of Comparative Examples 1 and 2 which did not contain polyurethane (B) but contained urethane acrylate instead could not be sufficiently bonded.

INDUSTRIAL APPLICABILITY The active energy ray-curable adhesive composition of the present invention is suitable for laminating various protective films for polarizing plates and polarizers, and exhibits extremely excellent adhesiveness. Therefore, it is useful as an adhesive for polarizing plates.

Claims (10)

A weight average molecular weight of 3,000 to 40, which is a reaction product of an unsaturated compound (A) having one ethylenically unsaturated group, a polyvalent isocyanate compound (b1) and a polyol compound (b2). 000 polyurethane (B) is contained, The active energy ray curable adhesive composition characterized by the above-mentioned. Content of the said polyurethane (B) is 5-60 weight part with respect to 100 weight part of unsaturated compounds (A) which has one ethylenically unsaturated group, The activity of Claim 1 characterized by the above-mentioned. Energy ray curable adhesive composition. The active energy ray-curable adhesive composition according to claim 1 or 2, wherein the unsaturated compound (A) having one ethylenically unsaturated group contains a hydroxyl group-containing (meth)acrylate compound (A1). Stuff. The unsaturated compound (A) having one ethylenically unsaturated group contains an alicyclic structure-containing (meth)acrylate compound (A2), according to any one of claims 1 to 3. Active energy ray curable adhesive composition. The content weight ratio of the hydroxyl group-containing (meth)acrylate compound (A1) to the alicyclic structure-containing (meth)acrylate compound (A2) is (A1)/(A2)=0.5 to 20. The active energy ray-curable adhesive composition according to claim 4. The active energy ray-curable adhesive composition according to any one of claims 1 to 5, wherein the polyol compound (b2) is at least one of a polyether polyol and a polyester polyol. The active energy ray-curable adhesive composition according to claim 6, wherein the polyether polyol is a polyether polyol having an oxyalkylene group having 4 to 7 carbon atoms. An adhesive composition for a polarizing plate, comprising the active energy ray-curable adhesive composition according to any one of claims 1 to 7. An adhesive for polarizing plates, which is a cured product of the adhesive composition for polarizing plates according to claim 8. A polarizing plate comprising a polarizer and a protective film bonded together via the polarizing plate adhesive according to claim 9.