JP2007191671A - Resin composition, adhesive for optical member, and method for producing adhesive for optical member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive for an optical member for producing a liquid crystal display board which is excellent in durability and releasability, and is excellent in adhesivity between the optical member and a glass base plate even under an environment where the temperature variation in a range from a low temperature region to a high temperature region is repeated, or under conditions of high temperature and high humidity, and is free from the occurrence of foaming or peeling and moreover, is suppressed in the occurrence of white spots due to the shrinkage of the optical member. <P>SOLUTION: This adhesive for an optical member is obtained by irradiating an active energy ray to an acrylic resin (A) containing no unsaturated group or to a resin composition mainly comprising an acrylic resin (A) containing no unsaturated group. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention adheres an adhesive for bonding an optical member and a substrate such as glass, in particular, a polarizing plate covered with a polarizing film with a protective film such as a cellulose triacetate film and a glass substrate of a liquid crystal cell. It is related with the adhesive for polarizing plates useful for making it. More specifically, when used as a pressure-sensitive adhesive for polarizing plates, it has excellent adhesion between the polarizing plate and the glass substrate even under high temperature and high humidity conditions, and foaming or peeling between the pressure-sensitive adhesive and the glass substrate. The present invention relates to a pressure-sensitive adhesive that does not occur and that can suppress a white spot phenomenon caused by contraction of an optical member such as a polarizing film and can provide a liquid crystal display panel having excellent durability.

  Conventionally, a polarizing plate in which both sides of an optical member, for example, a polyvinyl alcohol film provided with polarization properties, are coated with a cellulose film, for example, a cellulose triacetate film, is aligned between two glass plates. Lamination is carried out on the surface of the sandwiched liquid crystal cell to form a liquid crystal display panel, and this lamination to the liquid crystal cell surface is performed by contacting the cell surface with an adhesive layer provided on the polarizing plate surface, It is usually done by pressing.

The liquid crystal display panels obtained in this way are widely used as display devices for personal computers, liquid crystal televisions, car navigation systems, etc., and the use environment has become very harsh, and in such harsh environments. It is required to withstand even the use of
For example, in a severe environment such as high temperature and high humidity, a phenomenon such as foaming or peeling between the pressure-sensitive adhesive and the glass plate becomes a problem. In addition, the polarizing film shrinks in a high temperature and high humidity environment, whereas the pressure-sensitive adhesive layer cannot follow the shrinking of the polarizing film, and light leaks from the peripheral edge of the liquid crystal display panel. The so-called white spot phenomenon is a problem.

Further, when an optical member is attached, if a foreign matter bites into the attachment surface or the attachment position is misplaced, it is necessary to remove the optical member from the liquid crystal cell and attach it again. When peeling such an optical member from the liquid crystal cell, it is necessary to peel the optical member from the glass substrate without changing the gap of the liquid crystal cell so that the optical member is not broken. Is needed.
However, if the technique of simply increasing the adhesive strength is employed with an emphasis on the durability of the pressure-sensitive adhesive for optical members, the peelability is inferior, and it is not easy to achieve both durability and peelability.

  As a countermeasure, various studies have been made on the pressure-sensitive adhesive used in the polarizing plate. For example, 57 to 98.8 parts by weight of alkyl (meth) acrylate, 1 to 20 parts by weight of a functional group-containing monomer, and (meth) acryloyl. 0.2 to 3 parts by weight of a macromonomer having a group, a glass transition temperature of 40 ° C. or more, and a number average molecular weight in the range of 2000 to 20000, and at least the alkyl (meth) acrylate can be copolymerized A pressure-sensitive adhesive for liquid crystal elements, which is mainly composed of a copolymer of 0 to 20 parts by weight of another monomer and the weight average molecular weight of the copolymer is in the range of 500,000 to 2,000,000 (for example, patent documents) 1), (A) (meth) acrylic acid ester homopolymer or copolymer having a weight average molecular weight of 500,000 to 2,500,000, and (B) a weight average molecular weight of 5,000 to 500,000 (Meth) acrylic acid ester homopolymer or copolymer in a weight ratio of 100: 1 to 100: 50, and at least one of component (A) and component (B) is in the molecule A pressure-sensitive adhesive composition that is a (meth) acrylic acid ester copolymer having a nitrogen-containing functional group (see, for example, Patent Document 2), (A) a (meth) acrylic acid ester-based copolymer, and (B) poly A pressure-sensitive adhesive composition comprising a cross-linking agent having a weight ratio of 100: 0 to 10:90, which is an adduct of an isocyanate compound, and the content ratio of a bifunctional adduct and a trifunctional or higher functional adduct is 100: 0 to 10:90 (for example, ), (A) (meth) acrylic acid ester copolymer having a weight average molecular weight of 1,000,000 or more, and (B) weight average molecular weight of 1,000 to 10, per 100 parts by weight thereof. 000's A pressure-sensitive adhesive composition containing 5 to 100 parts by weight of a (meth) acrylate ester oligomer and 0.001 to 50 parts by weight of a crosslinking agent component containing (C) a bifunctional crosslinking agent (see, for example, Patent Document 4). Proposed.

Japanese Unexamined Patent Publication No. Hei 8-209090 JP 2001-89731 A JP 2001-262103 A JP 2001-335767 A

  However, in the disclosed technique of Patent Document 1, although foaming and peeling have been improved to some extent, the white spot phenomenon, which has been particularly emphasized in recent years, has not been considered, and is still satisfactory as a pressure-sensitive adhesive for polarizing plates. It wasn't going to be good.

  Further, in the disclosed technique of Patent Document 2, peeling is improved, and although an effect is also observed for the white spot phenomenon, it is a durability evaluation under an environment of 65 ° C., 95% RH, 100 hours. It is not satisfactory and further improvement in durability is required.

  Furthermore, in the disclosed technologies of Patent Documents 3 and 4, foaming and peeling are further improved in the durability evaluation under the environment of 100 ° C., 1000 hours and 60 ° C., 90% RH, 1000 hours, and white spots are further improved. However, in consideration of the actual usage situation of the liquid crystal display panel, even in an environment where the temperature change is repeated in the range of room temperature to high temperature, there is a demand for a product that does not cause foaming, peeling, or white spots. Then it was still not satisfactory.

Therefore, in the present invention, under such a background, even under high temperature and high humidity conditions, the optical member, in particular, excellent adhesion between the polarizing plate and the glass substrate, and foaming or peeling between the adhesive and the glass substrate. In addition, the pressure-sensitive adhesive for an optical member for obtaining a liquid crystal display panel and the like that can suppress a white spot phenomenon caused by contraction of the polarizing film, has excellent durability, and has excellent peelability, and optical It aims at providing the manufacturing method of the adhesive for members.
Moreover, an object of this invention is to provide the acrylic resin composition suitable for formation of the said adhesive for optical members.

  However, as a result of intensive studies in view of such circumstances, the inventor of the present invention has an acrylic resin (A) that does not contain an unsaturated group or an acrylic resin that mainly contains an acrylic resin (A) that does not contain an unsaturated group. By irradiating the resin composition with active energy rays, it is excellent in adhesiveness between the optical member, especially the polarizing plate and the glass substrate, even under high temperature and high humidity conditions, and foamed between the adhesive and the glass substrate. Further, the present inventors have found that a whitening phenomenon caused by shrinkage of the polarizing film can be suppressed and that a pressure-sensitive adhesive property having excellent durability and excellent peelability can be obtained.

  That is, the gist of the present invention is an adhesive for optical members obtained by irradiating an active resin to an acrylic resin (A) not containing an unsaturated group, and further an acrylic resin (A) containing no unsaturated group. It is related with the adhesive for optical members formed by irradiating an active resin to the acrylic resin composition which has as a main component.

  In addition, it is preferable that the acrylic resin composition of this invention is a composition formed by mix | blending a reactive crosslinking agent with acrylic resin (A) which does not contain an unsaturated group. When the acrylic resin composition contains a reactive crosslinking agent, the acrylic resin (A) that does not contain an unsaturated group is crosslinked by irradiation with active energy rays, and the acrylic resin that does not contain an unsaturated group by the reactive crosslinking agent. The functional group in the system resin (A) reacts and is crosslinked.

  In this invention, it is preferable at the point which can stabilize the reaction at the time of active energy ray irradiation from an acrylic resin composition containing a photoinitiator.

  Furthermore, the photopolymerization initiator is disadvantageous for curing due to oxygen hindrance on the surface, but is a self-cleaving photopolymerization initiator that is advantageous for internal crosslinking, and is less susceptible to oxygen hindrance and is suitable for curing on the surface. The use of both advantageous hydrogen abstraction type photopolymerization initiators is preferable in that a well-balanced crosslinking can be achieved as the whole coating film.

  In this invention, when the acrylic resin composition contains a silane compound, the adhesiveness of the pressure-sensitive adhesive to the glass is improved, which is preferable in terms of obtaining improved durability.

  The present invention also provides a method for producing an adhesive for an optical member, wherein the acrylic resin (A) that does not contain an unsaturated group applied to the release film or the optical member is irradiated with an active energy ray, the release film, or the optical member. A method for producing a pressure-sensitive adhesive for an optical member, which comprises irradiating an active energy ray to a resin composition mainly composed of an acrylic resin (A) that does not contain an unsaturated group applied to the substrate.

  The pressure-sensitive adhesive for optical members of the present invention is excellent in adhesiveness between the optical member and the glass substrate even under conditions of high temperature and high humidity, and no foaming or peeling occurs between the pressure-sensitive adhesive and the glass substrate. A white spot phenomenon caused by shrinkage of an optical member, particularly a polarizing film, can be suppressed, and a liquid crystal display panel having excellent durability can be obtained. .

The present invention is described in detail below.
The pressure-sensitive adhesive for optical members of the present invention irradiates an active energy ray to a resin composition mainly composed of an acrylic resin (A) containing no unsaturated group or an acrylic resin (A) containing no unsaturated group. It is made.

The acrylic resin (A) used in the present invention is not particularly limited as long as it does not contain an unsaturated group. Among them, (meth) acrylic acid alkyl ester (a1) is the main component, and if necessary, functional It is obtained by copolymerizing the group-containing monomer (a2) as a copolymerization component. Further, if necessary, another copolymerizable monomer (a3) can be used as a copolymerization component.
In addition, in the case of the acrylic resin composition containing the below-mentioned reactive crosslinking agent, it is preferable that the functional group-containing monomer (a2) is used from the viewpoint of effectively reacting the reactive crosslinking agent.

  Examples of the (meth) acrylic acid alkyl ester (a1) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and tert- Butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, isooctyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) Examples include aliphatic (meth) acrylic acid alkyl esters such as acrylate, aromatic (meth) acrylic acid alkyl esters such as benzyl (meth) acrylate, and dimethylaminoethyl (meth) acrylate. (Meth) acrylic acid alkyl ester having 1 to 12 carbon atoms of the alkyl group is preferable, and further, the alkyl group such as methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate has 1 to 1 carbon atoms. 4 (meth) acrylic acid alkyl ester is more preferable in terms of durability such as heat resistance and heat cycle resistance. These are used alone or in combination of two or more.

In addition, as a (meth) acrylic-acid alkylester (a1), even if it is a case where the (meth) acrylic-acid alkylester whose carbon number of an alkyl group is 1-4 is mainly used, carbon number of an alkyl group is 5 or more ( A meth) acrylic acid alkyl ester can be used in combination as appropriate.

  Examples of the functional group-containing monomer (a2) include a carboxyl group-containing monomer, a hydroxyl group-containing monomer, an amino group-containing monomer, an acetoacetyl group-containing monomer, and the like. In particular, a carboxyl group-containing monomer and a hydroxyl group-containing monomer are suitable. is there.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamide N-glycolic acid, and cinnamic acid. Among them, (meth) acrylic acid is preferably used.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, and tetrahydrofur Furyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, diethylene glycol (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, N-methylol (meth) acrylamide, ethyl Carbitol acrylate, tripropylene glycol (meth) acrylate, 1,4-butylene glycol mono (meth) acrylate, glycerol mono (meth) acrylate 2-hydroxyethyl acryloyl phosphate, 4-butylhydroxy acrylate, caprolactone-modified 2-hydroxyethyl acrylate, 2-acryloyloxyethyl succinic acid, allyl alcohol, and the like, among which 2-hydroxyethyl (meth) acrylate, 2- A (meth) acrylate having a C1-C4 hydroxyalkyl group such as hydroxypropyl (meth) acrylate and 4-hydroxybutyl acrylate is preferably used.

  The amino group-containing monomer is preferably a primary or secondary amino group-containing monomer, and examples thereof include t-butylaminoethyl (meth) acrylate and ethylaminoethyl (meth) acrylate.

Examples of the acetoacetyl group-containing monomer include 2- (acetoacetoxy) ethyl (meth) acrylate and allyl acetoacetate.
These functional group-containing monomers (a2) are used alone or in combination of two or more.

  Furthermore, as other copolymerizable monomer (a3), for example, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, dimethylaminoethyl (meth) ) Acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, acrylamide, methacrylamide, glycidyl (meth) acrylate, allyl glycidyl Ether, diacetone acrylamide, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, itaconic acid dialkyl ester, fumaric acid dialkyl ester, allyl alcohol, alcohol Rirukuroraido, include monomers such as methyl vinyl ketone.

  For the purpose of increasing the molecular weight, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) ) Polyfunctional monomers such as acrylate and divinylbenzene can be used in combination.

  In acrylic resin (A) that does not contain unsaturated groups, (meth) acrylic acid alkyl ester (a1), functional group-containing monomer (a2), and other copolymerizable monomer (a3) are contained in the entire copolymerizable monomer. The proportions of the (meth) acrylic acid alkyl ester (a1) are 50 to 100% by weight, the functional group-containing monomer (a2) is 0 to 20% by weight, and the other copolymerizable monomer (a3) is 0 to 30% by weight. More preferably, the (meth) acrylic acid alkyl ester (a1) is 70 to 99% by weight, the functional group-containing monomer (a2) is 1 to 15% by weight, and the other copolymerizable monomer (a3) is 0 to 20%. % By weight.

  When the (meth) acrylic acid alkyl ester (a1) is less than the lower limit, the adhesive strength tends to be insufficient. When the functional group-containing monomer (a2) exceeds the upper limit, the viscosity tends to increase or the stability of the resin tends to deteriorate. If the other copolymerizable monomer (a3) exceeds 30% by weight, it is difficult to obtain the effects of the present invention.

  In addition, when using a reactive crosslinking agent together, it is preferable that especially the content rate with respect to the whole copolymerizable monomer of a functional group containing monomer (a2) is 1 to 20 weight%, More preferably, it is 1 to 15 weight%. It is. By setting it as this content rate, it is preferable at the point from which efficient reaction with acrylic resin (A) which does not contain stability and viscosity of a resin, and also a reactive crosslinking agent and an unsaturated group is carried out, and also a bridge | crosslinking. This is preferable in that an appropriate crosslinked structure is formed in the subsequent pressure-sensitive adhesive.

  In producing the acrylic resin (A), although not particularly limited, the (meth) acrylic acid alkyl ester (a1), the functional group-containing monomer (a2), and the other copolymerizable monomer (a3) are used as an organic solvent. It is prepared by methods well known to those skilled in the art, such as radical copolymerization therein.

  In particular, a low molecular weight component can be produced, for example, by separately charging a charged monomer or additionally charging an organic solvent. By introducing such a low molecular weight component, it is possible to impart stress relaxation capability and suppress white spots. Moreover, in order to give stress relaxation ability, it is also possible to blend the low molecular weight component prepared separately as needed.

  Examples of the organic solvent used for the polymerization include aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and methyl acetate, aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol, acetone, methyl ethyl ketone, and methyl. Examples thereof include ketones such as isobutyl ketone and cyclohexanone.

  Polymerization catalysts used for such radical copolymerization include azobisisobutyronitrile, azobisdimethylvaleronitrile, benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, cumene hydro hydride, which are ordinary radical polymerization catalysts. Specific examples include peroxide.

  The weight average molecular weight of the acrylic resin (A) containing no unsaturated group thus obtained is not specified, but is preferably 1 million or more, particularly preferably 1 million to 3 million, more preferably 1.2 million to 2.5 million, and the weight average molecular weight. If it is less than the lower limit, the durability tends to be insufficient when it is used by being bonded to a polarizing plate, which is not preferable. In addition, since it is necessary to use a dilution solvent in large quantities when it exceeds 3 million, there exists a possibility that it may become a problem in terms of coating property or cost.

  Further, the glass transition temperature of the acrylic resin (A) is not specified, but is −20 ° C. or less, particularly −25 to −70 ° C., more preferably −40 to −60 ° C., and the glass transition temperature is −20 ° C. If it exceeds, tack tends to be insufficient.

In addition, said weight average molecular weight is a weight average molecular weight by standard polystyrene molecular weight conversion, and it is a column in high performance liquid chromatography (The Japan Waters company "Waters 2695 (main body)" and "Waters 2414 (detector)"). : Shodex GPC KF-806L (exclusion limit 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 The particle size is 10 μm), and the degree of dispersion is determined from the weight average molecular weight and the number average molecular weight. The glass transition temperature is calculated from the Fox equation.

The present invention also provides an acrylic resin composition mainly composed of the acrylic resin (A) containing no unsaturated group obtained as described above. Here, “being as a main component” means that the acrylic resin (A) is a main component of the resin composition, and preferably the content of the acrylic resin (A) component in the resin composition is 60. % By weight or more, more preferably 70% by weight or more. The resin component of the acrylic resin composition of the present invention preferably consists essentially of an acrylic resin (A) that does not contain an unsaturated group. Here, “the resin component is substantially composed only of an acrylic resin (A) not containing an unsaturated group” means that 95% by weight or more of the resin component does not contain an unsaturated group (A). This means that 97-100% by weight of the acrylic resin (A) does not contain an unsaturated group. Moreover, it is preferable that resin components other than acrylic resin (A) which does not contain an unsaturated group also do not contain an unsaturated group. Furthermore, the acrylic resin composition of the present invention is characterized by not containing a polymerizable monomer or polymerizable oligomer.
Moreover, a reactive crosslinking agent is mix | blended with acrylic resin (A) which does not contain an unsaturated group, and it is set as the resin composition formed by containing acrylic resin (A) and unsaturated crosslinking agent which do not contain an unsaturated group. It is also preferable.

  The reactive crosslinking agent is not particularly limited as long as it can react with the acrylic resin (A). For example,

Bisphenol A / epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol poly Epoxy compounds such as glycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether,

Tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxamide) Aziridine compounds such as N, N′-hexamethylene-1,6-bis (1-aziridinecarboxamide),

Melamine compounds such as hexamethoxymethyl melamine, hexaethoxymethyl melamine, hexapropoxymethyl melamine, hexaptoxymethyl melamine, hexapentyloxymethyl melamine, hexahexyloxymethyl melamine,

2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1 , 3-bis (isocyanatomethyl) cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, tolylene diisocyanate adduct of trimethylolpropane, xylylene diisocyanate adduct of trimethylolpropane, triphenylmethane triisocyanate, Isocyanate compounds such as methylenebis (4-phenylmethane) triisocyanate

Etc. These can be used alone or in combination of two or more.

  In the present invention, the content of the reactive crosslinking agent is preferably 0.005 to 5 parts by weight with respect to 100 parts by weight of the acrylic resin (A) not containing an unsaturated group, in particular 0.1. -4 parts by weight, more preferably 0.5-3 parts by weight. When the content is less than the lower limit, the effect of adding the reactive crosslinking agent cannot be obtained, and when the content exceeds the upper limit, the adhesive strength tends to be too low.

  In addition, the acrylic resin composition of the present invention may contain a photopolymerization initiator for stabilizing the reaction during irradiation with active energy rays and a silane compound for improving adhesion to a glass substrate. preferable.

  The photopolymerization initiator is not particularly limited as long as it generates radicals by the action of light, and an intramolecular self-cleavage photopolymerization initiator or a hydrogen abstraction photopolymerization initiator is used.

  Examples of the intramolecular self-cleaving photopolymerization initiator include 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one 1- (4-Isopropylenephenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 4- (2 -Hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, benzoin, Benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether , Benzoin isobutyl ether, benzyldimethyl ketal, α-acyloxime ester, acylphosphine oxide, methylphenylglyoxylate, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 4-benzoyl -4'-methyldiphenyl sulfide and the like. Among them, 2-hydroxy-2-methyl-1-phenylpropan-1-one and 1-hydroxycyclohexyl phenyl ketone are preferable.

  Examples of the hydrogen abstraction type photopolymerization initiator include benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 3,3′-dimethyl-4-methoxybenzophenone, 2,4,4, 6-trimethylbenzophenone, 4-methylbenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, camphorquinone, dibenzosuberone, 2-ethylanthra Examples include quinone, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, benzyl, 9,10-phenanthrenequinone, among which benzophenone, methylbenzophenone, 2,4,6- Trimethylben Phenone is preferred.

  Particularly in the present invention, using both a self-cleavage type photopolymerization initiator and a hydrogen abstraction type photopolymerization initiator improves the balance between photocrosslinking of the surface portion of the pressure-sensitive adhesive layer and internal photocrosslinking, This is further advantageous against white spots.

  The combination of the self-cleaving type photopolymerization initiator and the hydrogen abstraction type photopolymerization initiator includes self-cleaving type 1-hydroxycyclohexyl phenyl ketone and hydrogen abstraction type benzophenone, methylbenzophenone, or 2,4,6-trimethyl. A combination of benzophenones is preferred.

  Although it does not specifically limit as content of a photoinitiator, 0.1-20 weight part with respect to 100 weight part of acrylic resin (A), Especially 0.2-10 weight part, Furthermore, 0.5 It is preferably ˜4 parts by weight, and if it is less than the lower limit value, it is not preferable because curing due to irradiation with active energy rays such as ultraviolet rays tends to be unfavorable, and if it exceeds the upper limit value, the crosslinking density is lowered and it is difficult to obtain the effect.

  In addition, as a photopolymerization initiator, when a self-cleaving photopolymerization initiator and a hydrogen abstraction photopolymerization initiator are used in combination, the ratio of the self-cleavage photopolymerization initiator and the hydrogen abstraction photopolymerization initiator Is preferably 70:30 to 1:99 (weight ratio), particularly preferably 55:45 to 5:95 (weight ratio), more preferably 45:55 to 10:90 (weight ratio). Outside this range, the whiteout resistance tends to be slightly inferior.

  Further, if necessary, as an auxiliary for the photopolymerization initiator, triethanolamine, triisopropanolamine, 4,4′-dimethylaminobenzophenone (Michler ketone), 2-dimethylaminoethylbenzoic acid, 4-dimethylaminobenzoic acid. Acid ethyl, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxan It is also possible to use Song etc. together. These can be used alone or in combination of two or more.

  Although it does not specifically limit as said silane type compound, Epoxy type silane, an acrylic type silane, a mercapto type silane, a hydroxyl group type silane, etc. are mentioned, Especially an epoxy type silane is used preferably. These can be used alone or in combination of two or more.

  Specific examples of the epoxy silane include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycidoxypropylmethyldimethoxy. Silane, methyltri (glycidyl) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and the like can be mentioned. Among them, γ-glycidoxy is preferable. Propyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane.

  In the present invention, the content of the silane compound is not particularly limited, but is 0.01 to 10 parts by weight, particularly 0.01 to 1 part by weight, more preferably 100 parts by weight of the acrylic resin (A). 0.03-0.5 weight part is preferable. If the content is less than the lower limit, the effect of adding the silane compound cannot be obtained, and if the content exceeds the upper limit, the compatibility with the acrylic resin (A) tends to be poor and adhesive force and cohesive force tend not to be obtained.

  Thus, in the present invention, the acrylic resin composition (A) containing no unsaturated group obtained above or an acrylic resin composition (preferably containing an acrylic resin (A) containing no unsaturated group) By irradiating active energy rays to a resin composition comprising an acrylic resin (A) containing no unsaturated group and a reactive crosslinking agent, photopolymerization initiator, silane compound, etc. alone or in combination. Adhesive performance can be obtained.

  When irradiating active energy rays, as active energy rays, rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, electromagnetic waves such as X rays and γ rays, electron beams, proton rays, neutron rays, etc. can be used. However, curing by ultraviolet irradiation is advantageous from the viewpoint of curing speed, availability of an irradiation device, price, and the like.

  For ultraviolet irradiation, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a chemical lamp, an electrodeless discharge lamp, or the like that emits light in a wavelength range of 150 to 450 nm can be used.

In the present invention, the exposure dose of the actinic energy ray is preferably from 100 to 2000 mJ / cm ^2, more 150~1500mJ / cm ^2, and particularly preferably from 180~1000mJ / cm ^2. And most preferably, it is 180-500 mj / cm < ² >. When the irradiation amount is less than the lower limit value, the cohesive force is insufficient due to insufficient crosslinking, and when the irradiation amount exceeds the upper limit value, the substrate and the release film tend to be deteriorated.

In the present invention, unlike the irradiation of active energy rays to an active energy ray-curable pressure-sensitive adhesive composition comprising a conventional polymerizable monomer or polymerizable oligomer, an acrylic resin (A) containing no unsaturated group, or an unsaturated resin. Since the active energy ray is irradiated to the resin composition mainly composed of the acrylic resin (A) not containing a saturated group, it is performed in an inert gas atmosphere in order to suppress polymerization inhibition by oxygen, or an adhesive composition. It is not necessary to coat a coating film made of an object with a cover film. In the present invention, the irradiation with the active energy ray is preferably performed in the presence of oxygen, and it is particularly preferable that the irradiation is performed in the atmosphere. In addition, as for the irradiation amount of the active energy ray, compared with the case where a polymerizable monomer or a polymerizable oligomer is used, since the reaction point is reduced if the polymer of the present invention is crosslinked, it is usually 500 mj / cm ² or less. An irradiation dose is sufficient.

  The pressure-sensitive adhesive for optical members after being cross-linked by irradiation with active energy rays preferably has a gel fraction of 40 to 100% by weight in terms of a good balance between durability and white spots, and particularly 50 to 50%. The content is preferably 95% by weight, more preferably 65 to 90% by weight, and if it is less than the lower limit, the durability tends to be insufficient due to insufficient cohesive force.

  When adjusting the gel fraction of the pressure-sensitive adhesive to the above range, in order to increase the gel fraction, increase the irradiation amount or irradiation intensity of the active energy ray, and change the photopolymerization initiator into a self-cleavage type and hydrogen. Using two types of photopolymerization initiators with different types of extraction molds together, when using two types of photopolymerization initiators, lowering the content of self-cleaving photopolymerization initiators and increasing the content of hydrogen extraction molds In addition, the addition amount of the photopolymerization initiator may be adjusted, and when the reactive crosslinking agent is added, the addition amount of the reactive crosslinking agent may be increased.

  In order to reduce the gel fraction, the irradiation amount of the active energy ray is decreased, the content ratio of the hydrogen abstraction type photopolymerization initiator is reduced when two kinds of photopolymerization initiators are used in combination, and the self-cleavage type light is decreased. Use only the polymerization initiator, reduce the addition amount of photopolymerization initiator, increase it more than necessary, and reduce the addition amount when adding a reactive crosslinking agent. Just do it.

  It should be noted that the irradiation amount and irradiation intensity of the active energy ray, the composition ratio and addition amount of the photopolymerization initiator, and when a reactive crosslinking agent is added, the addition amount of the reactive crosslinking agent depends on the respective interactions, and the gel fraction Since they change, each must be balanced.

  The acrylic resin composition forming the optical pressure-sensitive adhesive of the present invention is once applied to a substrate such as a release film and irradiated with active energy rays. As a coating method, for example, the pressure-sensitive adhesive solution is used. An organic solvent such as toluene, ethyl acetate, methyl cellosolve, ethyl cellosolve or the like is applied alone or in a mixed solution to a solution of about 10 to 30% by weight as a resin solid content, and is applied and dried. The film thickness after drying is 10 to 40 μm, preferably 20 to 30 μm. In addition, it is applied to at least one surface of an optical member and irradiated with active energy rays, or once a resin composition solution for an adhesive is applied to a substrate such as a release film to form a coating film, and then polarized It is also useful to apply a transfer coating to the plate and irradiate with active energy rays.

  Although it will not specifically limit if it is a member used for an optical use as an optical member used by this invention, Especially, it is especially useful for a polarizing plate. Such a polarizing plate is obtained by laminating a protective film on at least one surface of a polarizing film. The polarizing film is made of a polyvinyl alcohol resin having an average polymerization degree of 1500 to 10,000 and a saponification degree of 85 to 100 mol%. A uniaxially stretched film (2 to 10 times, preferably a stretch ratio of about 3 to 7 times) dyed with an iodine-potassium iodide aqueous solution or a dichroic dye is used.

  Polyvinyl alcohol resins are usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate, but small amounts of unsaturated carboxylic acids (including salts, esters, amides, nitriles, etc.), olefins, vinyl ethers, A component copolymerizable with vinyl acetate, such as a saturated sulfonate, may be contained. Moreover, what is called polyvinyl acetal resin and polyvinyl alcohol derivatives, such as polybutyral resin, polyvinyl formal resin, etc. which reacted polyvinyl alcohol with aldehydes in presence of an acid is mentioned.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In the examples, “parts” and “%” mean weight basis unless otherwise specified.

[Preparation of acrylic resin (A)]
[Acrylic resin (A-1)]
A four-necked round bottom flask was equipped with a reflux condenser, a stirrer, a dropping funnel and a thermometer, and 94 parts of n-butyl acrylate (a1), 5 parts of methyl acrylate (a1), 1 part of acrylic acid (a2), and acetic acid. 80 parts of ethyl, 45 parts of acetone, and 0.03 part of azobisisobutyronitrile as a polymerization initiator were charged, and the temperature in the reaction vessel was raised to 70 ° C. and reacted for 2 hours. Then, 0.03 parts of azobisisobutyronitrile dissolved in 80 parts of ethyl acetate was added and reacted for 2 hours, and further 0.03 parts of azobisisobutyronitrile was dissolved in 80 parts of ethyl acetate. And reacted for 3 hours. After completion of the reaction, it is diluted with ethyl acetate and toluene (weight mixing ratio of ethyl acetate and toluene = 50: 50), so that the resin content is 19% and the weight average molecular weight is 150,000 (the ratio of each designated molecular weight is 1 million or more). 55%, 500,000 to 1,000,000 is 17%, 100,000 to 500,000 is 15%, 100,000 or less is 13%), dispersion degree 8, and acrylic resin (A-1) having a glass transition temperature of −50 ° C. It was.

[Acrylic resin (A-2)]
A four-necked round bottom flask was equipped with a reflux condenser, a stirrer, a dropping funnel and a thermometer, and 97 parts of n-butyl acrylate (a1), 3 parts of acrylic acid (a2), 70 parts of ethyl acetate, 50 parts of acetone, 0.015 part of azobisdimethylvaleronitrile was charged as a polymerization initiator, the temperature in the reaction vessel was raised to 65 ° C., and the reaction was carried out for 2 hours. Thereafter, a solution prepared by dissolving 0.015 part of azobisdimethylvaleronitrile in 80 parts of ethyl acetate was added and reacted for 2 hours. After completion of the reaction, the mixture is diluted with ethyl acetate and toluene (weight mixing ratio of ethyl acetate and toluene = 50: 50) to give a resin content of 16.5% and a weight average molecular weight of 2,050,000 (the ratio of each designated molecular weight is 1,000,000). The above is 65%, 500,000 to 1,000,000 is 12%, 100,000 to 500,000 is 12%, 100,000 or less is 11%), the degree of dispersion is 5, and the acrylic resin (A-2) has a glass transition temperature of −52 ° C. Got.

[Acrylic resin (A-3)]
Attach a reflux condenser, stirrer, dropping funnel and thermometer to a four-necked round bottom flask, 91.9 parts of n-butyl acrylate (a1), 5 parts of methyl acrylate (a1), 3 parts of acrylic acid (a2), 0.1 part of 2-hydroxyethyl acrylate (a2), 75 parts of ethyl acetate, 45 parts of acetone, and 0.025 part of azobisisobutyronitrile as a polymerization initiator were added, and the temperature in the reaction vessel was raised to 70 ° C. And reacted for 2 hours. Thereafter, 80 parts of ethyl acetate in which 0.025 part of azobisisobutyronitrile was dissolved was added and reacted for 2 hours. Further, 40 parts of ethyl acetate and 0.0125 part of azobisisobutyronitrile were added for 3 hours. Reacted. After completion of the reaction, the mixture is diluted with ethyl acetate and toluene (weight mixing ratio of ethyl acetate and toluene = 50: 50) to obtain a resin content of 17.5% and a weight average molecular weight of 1,700,000 (the ratio of each designated molecular weight is 1,000,000). The above is 60%, 500,000 to 1,000,000 is 15%, 100,000 to 500,000 is 11%, 100,000 or less is 13%), the degree of dispersion is 8, and the acrylic resin (A-3) has a glass transition temperature of −49 ° C. Got.

[Acrylic resin (A-4)]
A four-necked round bottom flask was equipped with a reflux condenser, a stirrer, a dropping funnel and a thermometer, and 92.9 parts of n-butyl acrylate (a1), 2.5 parts of methyl acrylate (a1), 2-ethylhexyl acrylate (A1) 2.5 parts, acrylic acid (a2) 2 parts, 2-hydroxyethyl acrylate (a2) 0.1 part, and ethyl acetate 75 parts, acetone 45 parts, azobisisobutyronitrile 0 as a polymerization initiator 0.025 part was charged, and the temperature in the reaction vessel was raised to 70 ° C. and reacted for 2 hours. Thereafter, 80 parts of toluene in which 0.025 part of azobisisobutyronitrile is dissolved is added and reacted for 2 hours. Further, 40 parts of toluene and 0.0125 part of azobisisobutyronitrile are added and reacted for 3 hours. It was. After completion of the reaction, the mixture is diluted with ethyl acetate and toluene (weight mixing ratio of ethyl acetate and toluene = 50: 50) to give a resin content of 20.0% and a weight average molecular weight of 1.3 million (the ratio of each designated molecular weight is 1,000,000). 40% for the above, 15% for 500,000 to 1,000,000, 20% for 100,000 to 500,000, 25% for 100,000 or less), an acrylic resin (A-4) having a dispersity of 13 and a glass transition temperature of −53 ° C. Got.

[Reactive cross-linking agent]
The following were prepared as crosslinking agents capable of reacting with the acrylic resin (A).
・ 55% ethyl acetate solution of trimethylolpropane tolylene diisocyanate adduct (manufactured by Nippon Polyurethane Co., Ltd., “Coronate L-55E”)

[Photopolymerization initiator]
The following were prepared as photopolymerization initiators.
<Self-cleavage photopolymerization initiator>
1-hydroxycyclohexyl phenyl ketone (“Irgacure 184” manufactured by Ciba Specialty Chemicals)
<Hydrogen extraction type photopolymerization initiator>
・ Benzophenone (manufactured by DK Fine)
・ Mixture of 4-methylbenzophenone and 2.4.6-trimethylbenzophenone ("ESACURE TZT" manufactured by Nippon Siebel Hegner)

[Silane compounds]
The following were prepared as silane compounds.
・ Γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBM403”)

Examples 1-15, Comparative Examples 1-2
Resin composition solutions were prepared with the blending compositions shown in Tables 1 and 2. The obtained resin composition solution was applied to a polyester release film so that the thickness after drying was 25 μm, dried at 90 ° C. for 3 minutes, and then irradiated with ultraviolet light with a high-pressure mercury lamp (the irradiation amount shown in Table 1). The pressure-sensitive adhesive layer side made of the resin composition is transferred onto a polarizing plate (thickness 190 μm), and further aged for 7 days under conditions of 23 ° C. and 50% RH to obtain a polarizing plate with a pressure-sensitive adhesive layer. It was.

  The polarizing plate was laminated with a cellulose triacetate film having a thickness of 80 μm on both sides of a 30 μm-thick polyvinyl alcohol polarizing film (average polymerization degree 1700, average saponification degree 99 mol%, iodine staining, 4-fold stretching). A polarizing plate (a polyvinyl alcohol polarizing film was cut at 233 mm × 309 mm by tilting the stretching axis direction by 45 degrees: equivalent to 15 inches) was used.

  Next, the release film of the obtained polarizing plate with the pressure-sensitive adhesive layer is peeled off, and the pressure-sensitive adhesive layer side is pressed against a non-alkali glass plate (“Corning 1737”, manufactured by Corning), and the polarizing plate and the glass plate And pasted. Thereafter, after autoclaving (50 ° C., 0.5 MPa, 20 minutes), foaming, peeling, and white spots in the following durability test were evaluated. The evaluation criteria are as follows. The evaluation results are shown in Tables 3 and 4.

[Measurement of gel fraction]
After applying the resin composition solution for pressure-sensitive adhesives obtained in the blending composition as shown in Table 1 and Table 2 to a polyester release film so that the thickness after drying is 25 μm, and drying at 90 ° C. for 3 minutes , UV irradiation with a high-pressure mercury lamp (irradiation amount shown in Table 1), pasted on a polyester film, and further aged for 7 days at 23 ° C. and 50% RH to obtain a sample for gel fraction measurement It was.
After cutting the obtained sample to 40 × 40 mm, the release sheet is peeled off and the pressure-sensitive adhesive layer side is bonded to a 50 × 100 mm SUS mesh sheet (200 mesh), and then to the longitudinal direction of the SUS mesh sheet. The sample was wrapped from the center and wrapped in a sample, and then the gel fraction was measured by the change in weight when immersed in a sealed container containing 250 g of toluene.

〔An endurance test〕
(1) Heat resistance test 80 ° C., 1000 hour durability test (2) Moist heat resistance test 65 ° C., 95% RH, 1000 hour durability test (3) Temperature change repetition test After leaving at −20 ° C. for 1 hour, at 60 ° C. Endurance test for 500 cycles, with 1 hour of operation as a cycle

〔Evaluation criteria〕
(Foam)
○: No foaming is observed Δ: Foaming with a diameter of less than 100 μm is slightly observed ×: Foaming with a diameter of 100 μm or more is often observed (peeling)
○ ・ ・ ・ No peeling is observed △ ・ ・ ・ Peeling less than 1mm or floating streaks × ・ ・ ・ Peeling over 1mm (white spots)
○… No white spots are seen △… White spots are slightly generated × ・ ・ ・ White spots are largely generated on the four sides

[Measurement of adhesive strength]
About the polarizing plate with an adhesive layer prepared in Examples 1-9, Comparative Example 1, Examples 10-15, and Comparative Example 2, the sheet was cut to a width of 25 mm, the release film was peeled off, and the adhesive layer side was The polarizing plate and the glass plate were bonded together by pressing against an alkali-free glass plate (Corning, “Corning 1737”). Then, after performing an autoclave process (50 degreeC, 0.5 Mpa, 20 minutes), the 180 degreeC peeling test was done. In peelability, it is desired that the adhesive strength is small.

Note) The blending parts in the table are parts by weight as solid content.
IRG184: 1-hydroxycyclohexyl phenyl ketone (Ciba Specialty Chemicals, “Irgacure 184”)
・ BP: Benzophenone (manufactured by DK Fine)
ESATZT: ESACURE TZT (Nippon Siebel Hegner, mixed product of 4-methylbenzophenone and 2.4.6-trimethylbenzophenone)
KBM403: γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KB
M403 ")

Note) The blending parts in the table are parts by weight as solid content.
L-55E: 55% ethyl acetate solution of tolylene diisocyanate adduct of trimethylolpropane (manufactured by Nippon Polyurethane Co., Ltd., “Coronate L-55E”)
IRG184: 1-hydroxycyclohexyl phenyl ketone (Ciba Specialty Chemicals, “Irgacure 184”)
・ BF: Benzophenone (manufactured by DK Fine)
KBM403: γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., “KBM403”)

The pressure-sensitive adhesive for optical members of the present invention provides an active energy ray to an acrylic resin (A) containing no unsaturated group or a resin composition mainly comprising an acrylic resin (A) containing no unsaturated group. Because it is irradiated, it has excellent adhesiveness between the optical member and the glass substrate even under high-temperature and high-humidity conditions and in an environment where temperature changes in the range of low to high temperatures are repeated. In addition to no foaming or peeling between the substrate and the optical member, it is possible to suppress the white spot phenomenon caused by contraction of the optical member, to obtain a liquid crystal display panel with excellent durability, and further excellent reworkability, Since the liquid crystal cell can be reused even when the bonding operation fails, it is very useful.

Claims (14)

  A resin composition which does not contain a polymerizable monomer or polymerizable oligomer and contains a resin component and a photopolymerization initiator, and the resin component is substantially only an acrylic resin (A) which does not contain an unsaturated group. The resin composition which forms the adhesive for optical members with the active energy ray characterized by comprising.   An adhesive for optical members, which is obtained by irradiating an active resin to an acrylic resin (A) that does not contain an unsaturated group. An adhesive for optical members, which is obtained by irradiating an active resin to an acrylic resin composition mainly composed of an acrylic resin (A) not containing an unsaturated group.   The pressure-sensitive adhesive for optical members according to claim 3, wherein the acrylic resin composition further contains a reactive crosslinking agent.   Acrylic resin (A) containing no unsaturated group is (meth) acrylic acid alkyl ester (a1) 50-100% by weight, functional group-containing monomer (a2) 0-20% by weight, other copolymerizable monomers ( The pressure-sensitive adhesive for optical members according to any one of claims 2 to 4, which is a copolymer obtained by copolymerizing a3) 0 to 30% by weight.   The pressure-sensitive adhesive for optical members according to any one of claims 3 to 5, wherein the acrylic resin composition further contains a photopolymerization initiator.   The pressure-sensitive adhesive for optical members according to claim 6, wherein the photopolymerization initiator comprises a self-cleavage type photopolymerization initiator and a hydrogen abstraction type photopolymerization initiator.   The pressure-sensitive adhesive for optical members according to any one of claims 3 to 7, wherein the acrylic resin composition further contains a silane compound.   The pressure-sensitive adhesive for optical members according to any one of claims 2 to 8, wherein the acrylic resin (A) containing no unsaturated group has a weight average molecular weight of 1,000,000 or more. The irradiation amount of an active energy ray is 100-2000 mJ / cm < ² >, The adhesive for optical members in any one of Claims 2-9 characterized by the above-mentioned.   The pressure-sensitive adhesive for optical members according to any one of claims 2 to 10, wherein the gel fraction is 40 to 100% by weight.   The pressure-sensitive adhesive for optical members according to claim 2, wherein the optical member is a polarizing plate.   A method for producing a pressure-sensitive adhesive for optical members, which comprises irradiating an acrylic resin (A) applied to a release film or an optical member and containing no unsaturated group with active energy rays. An adhesive for optical members, wherein the acrylic resin composition mainly comprising an acrylic resin (A) containing no unsaturated group, applied to a release film or an optical member, is irradiated with active energy rays. Manufacturing method.