JP2016180018A - Adhesive and adhesive sheet using the same - Google Patents

Abstract

An object of the present invention is excellent in removability, and is not easily lifted or peeled off from an adherend, for example, glass or plastics after being exposed to a high-temperature environment or high-temperature and high-humidity environment. To provide a pressure-sensitive adhesive capable of producing a pressure-sensitive adhesive sheet capable of maintaining high transparency that hardly causes indentation in a material layer.
SOLUTION: An acrylic copolymer, an isocyanate curing agent, and a silane coupling agent, the acrylic copolymer comprising a hydroxyl group-containing monomer (A), an amide group-containing monomer (B), and a homopolymer. A polymer obtained by polymerizing a monomer mixture containing a monomer (C) having a glass transition temperature of 0 to 50 ° C., a monomer (D) having a glass transition temperature of 60 to 150 ° C. of a homopolymer, and other monomers (E).
[Selection figure] None

Description

  The present invention relates to an adhesive that can be used for members such as plastic and glass.

Display devices such as liquid crystal displays used in various devices such as home and commercial appliances such as electronic calculators, electronic watches, mobile phones, and televisions are becoming larger, especially liquid crystal televisions and plasma televisions. The increase in size is remarkable. In recent years, touch panel type liquid crystal displays such as smartphones and tablets are rapidly spreading, and a large market expansion is expected in the future. On the other hand, liquid crystal displays are also used in in-vehicle devices such as car navigation systems, and are required to have durability that can be used in harsh interior environments such as high-temperature and high-humidity atmospheres.
The liquid crystal display uses polarizing plates and retardation plates having various optical functions, and these are attached to an adherend such as a liquid crystal cell using glass or transparent plastic via an adhesive. Affixed.

  The polarizing plate is a laminate having a configuration in which a polyvinyl alcohol film is generally sandwiched between triacetyl cellulose films and cycloolefin films. These films have different mechanical properties and therefore have different dimensional change rates during heating. Therefore, when placed in a high temperature atmosphere, the laminate often warps.

  Here, for example, if a liquid crystal cell member of a polarizing plate / adhesive layer / glass (glass is a surface member of a liquid crystal cell) is left in a high temperature atmosphere, warpage due to the dimensional change rate between the constituent members of the polarizing plate occurs. Or bubbles (foaming) may occur at the adhesive interface between the pressure-sensitive adhesive layer and the glass, or the polarizing plate may float from the glass and peel off. Further, the stress distribution of the liquid crystal cell member becomes non-uniform due to warpage, and the stress concentrates on the peripheral edge of the liquid crystal cell member. As a result, light leaks from the four corners and the peripheral edge of the liquid crystal cell member. The problem of “light leakage phenomenon” may occur. The above problem also occurs in a high temperature and high humidity atmosphere.

  On the other hand, in the manufacturing process of liquid crystal displays, etc., when a polarizing plate is bonded to an optical component such as a liquid crystal cell, the polarizing plate is attached after a certain period of time has elapsed since the bonding position has shifted. Peeling and reusing an expensive liquid crystal cell is performed. For this reason, the pressure-sensitive adhesive is required to have a property (reworkability) capable of re-peeling the polarizing plate from the liquid crystal cell after a predetermined time has elapsed since sticking.

  In order to solve these problems, Patent Document 1 discloses a technique of adding a plasticizer or the like to the pressure-sensitive adhesive to moderately soften the pressure-sensitive adhesive layer to impart stress relaxation and prevent light leakage. Yes. However, when a plasticizer is added, it causes bleed-out that contaminates the adherend when the polarizing plate is peeled off, and reduces cohesive force. There was a problem that floating and peeling were likely to occur, and the addition of an excessive amount of plasticizer caused whitening of the coating film.

  Patent Document 2 discloses a technique for improving stress relaxation and preventing light leakage by including an acrylic copolymer using an aromatic ring-containing monomer. However, the pressure-sensitive adhesive using the aromatic ring-containing monomer described in Patent Document 2 has a problem that white spots are generated and optical characteristics are inferior in light leakage evaluation.

  On the other hand, in Patent Document 3, in order to impart removability, a high molecular weight acrylic polymer having a weight average molecular weight of 500,000 or more has a high acid value and a low molecular weight having a weight average molecular weight of 0.2 to 100,000. Techniques for blending acrylic polymers are disclosed. However, the pressure-sensitive adhesive described in Patent Document 3 has a problem that the drying conditions of the pressure-sensitive adhesive are limited.

  Furthermore, in patent document 4, the technique which improves stress relaxation property by using together the acrylic polymer with a weight average molecular weight of 700,000 or more which has a carboxyl group, and the acrylic polymer with a weight average molecular weight of 800-50,000. Is disclosed. However, the pressure-sensitive adhesive described in Patent Document 4 has a problem that the cohesive force is significantly reduced.

  Patent Document 5 discloses a technique for improving durability and adhesive properties under heating and humidification conditions by using a block polymer using two or more kinds of monomers. However, the pressure-sensitive adhesive described in Patent Document 5 has a problem in that the transmittance under heating and humidification conditions decreases.

  Moreover, in patent document 6, water-dispersion-type adhesion | attachment containing the acrylic copolymer whose glass transition temperature is -55 degreeC or more and less than 0 degreeC, and the acrylic copolymer whose glass transition temperature is 0 degreeC or more and 180 degrees C or less. A technology that makes it difficult to depolarize by an agent and imparts reworkability and recyclability is disclosed. However, the pressure-sensitive adhesive described in Patent Document 6 has a problem of contaminating an adherend such as glass with various additives used in the pressure-sensitive adhesive.

Japanese Patent Laid-Open No. 9-87593 JP 2007-169329 A JP 2010-1000071 A Japanese Patent Laid-Open No. 2004-69975 JP 2013-82774 A JP 2014-1365 A

  The problem to be solved by the present invention is to solve the above-mentioned problems, and when used in an adhesive film, is excellent in releasability, and after being exposed to a high temperature environment or a high temperature and high humidity environment, from an adherend. It is an object of the present invention to provide a pressure-sensitive adhesive that does not easily float or peel off, and a pressure-sensitive adhesive sheet using the same. Further, when used for fixing a polarizing plate, the light leakage evaluation is good, and it has a good adhesive force that can maintain high transparency even when exposed to a high temperature and high humidity environment. It is an object of the present invention to provide a pressure-sensitive adhesive that does not contaminate a body and a pressure-sensitive adhesive sheet using the same.

As a result of intensive studies to solve the above problems, the present inventors have reached the present invention.
That is, the present invention includes an acrylic copolymer, an isocyanate curing agent, and a silane coupling agent, and the acrylic copolymer includes a hydroxyl group-containing monomer (A) and an amide group-containing monomer (B) ( However, the monomer (A) is excluded), the homopolymer has a glass transition temperature of 0 to 50 ° C. (C) (except the monomer (A) and the monomer (B)), and the homopolymer glass transition temperature. Relates to a pressure-sensitive adhesive obtained by polymerizing a monomer mixture containing a monomer (D) (excluding the monomer (A) and the monomer (B)) at 60 to 150 ° C. and the other monomer (E).

The present invention also relates to the pressure-sensitive adhesive, wherein the monomer (C) is an acrylic acid alkyl ester or an acrylic acid cycloalkyl ester having an alkyl group having 1 to 3 carbon atoms.

The present invention also relates to the pressure-sensitive adhesive, wherein the monomer (D) is a (meth) acrylic acid alkyl ester or a (meth) acrylic acid cycloalkyl ester having an alkyl group having 1 to 3 carbon atoms.

Moreover, this invention relates to the said adhesive whose molecular weight distribution of the said acrylic copolymer is 10-40.

Further, in the present invention, in the total amount of the monomer mixture, the hydroxyl group-containing monomer (A) is 0.05 to 5 parts by weight, the amide group-containing monomer (B) is 0.1 to 5 parts by weight, and the glass transition temperature of the homopolymer is 0 to 0. 4-40 parts by weight of the monomer (C) at 50 ° C., 2-30 parts by weight of the monomer (D) having a glass transition temperature of 60-150 ° C., and 20-93.85 parts by weight of the other monomer (E). It relates to an adhesive.

Moreover, this invention relates to the adhesive sheet provided with a base material and the adhesive layer formed from the said adhesive.

Moreover, this invention relates to the polarizing plate adhesive sheet provided with the polarizing plate and the adhesive layer formed from the said adhesive.

Moreover, this invention relates to the liquid crystal cell member provided with the glass plate, the adhesive layer formed from the said adhesive, and an optical member.

  According to the present invention configured as described above, in the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive, the acrylic copolymer and the isocyanate curing agent undergo a crosslinking reaction to form a resin network. Since the pressure-sensitive adhesive layer does not impair the cohesive force and is excellent in stress relaxation, even when exposed to a high-temperature atmosphere or a high-temperature and high-humidity atmosphere, the pressure-sensitive adhesive layer has an effect that it is unlikely to float and peel off and light leakage hardly occurs. . Further, the pressure-sensitive adhesive layer has high transparency, and has an effect that high transparency can be maintained even when exposed to a high temperature and high humidity environment. Furthermore, since bleeding out of low molecular weight and oligomer components does not occur, there is an effect that adherend contamination can be reduced.

  The pressure-sensitive adhesive sheet is excellent in removability according to the present invention and, after being exposed to a high-temperature environment or a high-temperature and high-humidity environment, for example, glass or plastics are unlikely to float or peel off from the adherend, and does not easily leak light. We were able to provide an adhesive that could be made.

The pressure-sensitive adhesive of the present invention includes an acrylic copolymer, an isocyanate curing agent, and a silane coupling agent, and the acrylic copolymer includes a hydroxyl group-containing monomer (A) and an amide group-containing monomer (B). (Excluding the monomer (A)), a monomer (C) having a glass transition temperature of 0 to 50 ° C. (excluding the monomer (A) and the monomer (B)), and a glass transition of the homopolymer It is characterized by polymerizing a monomer mixture containing a monomer (D) having a temperature of 60 to 150 ° C. (excluding the monomer (A) and monomer (B)) and the other monomer (E).
The pressure-sensitive adhesive of the present invention is preferably used as a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer formed by coating and drying. The pressure-sensitive adhesive tape is preferably used for an optical member, particularly for bonding a liquid crystal display member.

  In the present invention, the acrylic copolymer contains a hydroxyl group-containing monomer (A). The acrylic copolymer containing the hydroxyl group-containing monomer (A) has the effect of suppressing floating and peeling and light leakage by forming a polymer network through a crosslinking reaction with an isocyanate curing agent. In the present invention, (meth) acrylic acid ester includes acrylic acid ester and methacrylic acid ester.

  Specifically, the hydroxyl group-containing monomer (A) in the present invention is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth). Such as 2-hydroxybutyl acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, etc. ) Glycolic mono (meth) acrylic such as hydroxyalkyl acrylate, polyethylene glycol mono (meth) acrylic ester, polypropylene glycol mono (meth) acrylic ester, 1,4-cyclohexanedimethanol mono (meth) acrylic ester Acid ester, cap Lactone-modified (meth) acrylic acid ester, and the like. These may be used alone or in combination of two or more.

  The hydroxyl group-containing monomer (A) is preferably contained in 0.05 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, in 100 parts by weight of the monomer mixture. When the content is 0.05 parts by weight or more, the cohesive force is further improved. Moreover, it becomes easy to make cohesion force and stress relaxation property compatible because content will be 5 weight% or less.

  In the present invention, the acrylic copolymer contains an amide group-containing monomer (B). As used herein, “amide group” means a carbamoyl group in which a hydrogen atom on a nitrogen atom may be substituted with a substituent such as an alkyl group, a hydroxyalkyl group, or an alkoxyalkyl group. May combine with each other to form a ring. In a general acrylic copolymer, durability may be lowered by bleeding out of an oligomer generated at the end of polymerization. In the present invention, the amide group-containing monomer (B) has a low polymerization rate and starts to be polymerized at the end of the polymerization. Since the oligomer containing an amide group has a slight polarity, it does not easily bleed out, and an effect of suppressing a decrease in durability can be obtained.

  Specific examples of the amide group-containing monomer (B) in the present invention include (meth) acrylamide, N-methylacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N -Containing heterocycles such as (meth) acrylamide compounds such as dimethylaminopropyl (meth) acrylamide, diacetone acrylamide, N- (butoxymethyl) acrylamide, N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, etc. Examples thereof include compounds, N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide and the like. These may be used alone or in combination of two or more.

  The amide group-containing monomer (B) is preferably contained in 0.1 to 5 parts by weight, more preferably 0.2 to 3 parts by weight, in 100 parts by weight of the monomer mixture. When the content is 0.1 parts by weight or more, the cohesive force is further improved. Moreover, it becomes easy to make cohesion force and stress relaxation property compatible because content will be 5 weight% or less.

  In the present invention, the acrylic copolymer contains a monomer (C) having a homopolymer glass transition temperature of 0 to 50 ° C. In general acrylic copolymers, the glass transition temperature of the homopolymer is less than 0 ° C. in order to obtain a high molecular weight for the purpose of suppressing foaming when exposed to a high temperature atmosphere or a high temperature and high humidity atmosphere. Consists of monomers. However, although foaming can be suppressed, since the resulting adhesive layer has insufficient elasticity, high adhesive strength cannot be obtained, and floating or peeling may occur when exposed to a high temperature atmosphere for a long period of time. . In the present invention, since the acrylic copolymer contains a monomer (C) having a glass transition temperature of 0-50 ° C. of the homopolymer, sufficient elasticity can be obtained, and high adhesive strength can be obtained. When exposed to a high temperature atmosphere for a long period of time, the effect of suppressing foaming, floating and peeling can be obtained.

  Specific examples of the monomer (C) having a glass transition temperature of 0 to 50 ° C. in the present invention include methyl acrylate, tert-butyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, acrylic Examples include benzyl acid, butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, stearyl methacrylate, and the like. Among these, methyl acrylate and cyclohexyl acrylate are preferable from the viewpoint that good adhesive performance can be easily obtained. These can be used alone or in combination of two or more.

  The monomer (C) having a glass transition temperature of 0 to 50 ° C. of the homopolymer preferably includes 4 to 40 parts by weight, more preferably 10 to 30 parts by weight, per 100 parts by weight of the monomer mixture. When the content is 4 parts by weight or more, the cohesive force is further improved. Moreover, it becomes easy to make cohesion force and stress relaxation property compatible because content will be 40 weight% or less.

  In this invention, an acrylic copolymer contains the monomer (D) whose glass transition temperature of a homopolymer is 60-150 degreeC. In general acrylic copolymers, glass transition temperature of homopolymer is used to obtain high molecular weight for the purpose of suppressing shrinkage of the pressure-sensitive adhesive layer when exposed to high temperature atmosphere or high temperature and high humidity atmosphere. Is composed of a monomer of less than 0 ° C. However, although the shrinkage of the pressure-sensitive adhesive layer can be suppressed, since the resulting pressure-sensitive adhesive layer is not sufficiently elastic, high adhesive strength cannot be obtained, and when exposed to a high temperature atmosphere for a long time, it does not float or peel off. May occur. In the present invention, since the acrylic copolymer contains a monomer (D) having a homopolymer glass transition temperature of 60 to 150 ° C., sufficient film strength can be obtained. When exposed to a high-temperature and high-humidity atmosphere for a long period of time, an effect of suppressing shrinkage, lifting and peeling of the pressure-sensitive adhesive layer can be obtained.

  Specific examples of the monomer (D) having a glass transition temperature of 50 to 150 ° C. in the present invention include isobornyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, tert-butyl methacrylate, methacrylic acid. Examples include cyclohexyl acid, benzyl methacrylate, phenyl methacrylate, and the like. Among these, isobornyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, and cyclohexyl methacrylate are preferable from the viewpoint that good adhesive performance can be easily obtained. These can be used alone or in combination of two or more.

  The monomer (C) having a glass transition temperature of 60 to 150 ° C. of the homopolymer is preferably 2 to 30 parts by weight, more preferably 5 to 20 parts by weight, per 100 parts by weight of the monomer mixture. When the content is 2 parts by weight or more, the cohesive force is further improved. Moreover, it becomes easy to make cohesion force and stress relaxation property compatible because content will be 30 weight% or less.

  In the present invention, the acrylic copolymer contains other monomer (E). The other monomer (E) is used to obtain a high molecular weight body for the purpose of suppressing foaming and shrinkage of the pressure-sensitive adhesive layer when exposed to a high temperature atmosphere or a high temperature and high humidity atmosphere.

  The other monomer (E) in the present invention contains a (meth) acrylic acid alkyl ester whose homopolymer has a glass transition temperature of less than 0 ° C., a monomer containing a carboxyl group, a monomer containing an epoxy group, and an amino group. Monomers, monomers having an alkylene oxide unit, vinyl acetate, vinyl crotonic acid, styrene, acrylonitrile and the like.

  Specific examples of the (meth) acrylic acid alkyl ester having a homopolymer glass transition temperature of less than 0 ° C. include ethyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, and octyl acrylate. , Isooctyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, and the like. Among these, butyl acrylate and 2-ethylhexyl acrylate are preferable from the viewpoint that good adhesive performance is easily obtained. These can be used alone or in combination of two or more.

  Examples of the monomer containing a carboxyl group include (meth) acrylic acid, p-carboxybenzyl acrylate, ethylene oxide-modified (added mole number: 2 to 18) phthalic acid acrylate, and succinic acid monohydroxyethyl acrylate. , Β-carboxyethyl acrylate, 2- (4-benzoyl-3-hydroxyphenoxy) ethyl acrylate, maleic acid, monoethylmaleic acid, itaconic acid, citraconic acid, and fumaric acid.

  Examples of the monomer containing an epoxy group include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, and 6-methyl-3 (meth) acrylate. 4-epoxycyclohexylmethyl and the like can be mentioned.

  Examples of the monomer containing an amino group include monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, and the like. Examples include (meth) acrylic acid monoalkylamino esters.

  The monomer having an alkylene oxide unit preferably has units such as ethylene oxide and propylene oxide. Specifically, for example, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-phenoxyethyl acrylate, methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, methoxypolypropylene Examples include glycol (meth) acrylic acid ester, ethoxy polypropylene glycol (meth) acrylic acid ester, phenoxypolyethylene glycol (meth) acrylic acid ester, and phenoxypolypropylene glycol (meth) acrylic acid ester.

  It is preferable that the said other monomer (E) contains 20-93.85 weight part in 100 weight part of monomer mixtures, and 30-80 weight part is more preferable. When the content is 20 parts by weight or more, the cohesive force is further improved. Moreover, it becomes easy to make cohesion force and stress relaxation property compatible because content will be 93.85 weight% or less.

  “Glass transition temperature (Tg)” of a homopolymer means the temperature at which this state changes when the polymer melted by heating is cooled under certain conditions to become a glass state through a supercooled liquid. To do. Specifically in this specification, Tg is a value measured by JIS K7121. Table 1 shows the measured glass transition temperature of the homopolymer.

  In the pressure-sensitive adhesive of the present invention, the molecular weight distribution of the acrylic polymer (molecular weight distribution (Mw / Mn) representing the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn)) is preferably from 10 to 40. By being in the said range, it is hard to produce a float and peeling and adhesive force improves and improves. The weight average molecular weight of the acrylic polymer is preferably 500,000 to 2,000,000, more preferably 700,000 to 1,800,000. Since cohesion force etc. improve more because it exists in the range of 500,000-2 million, a float and peeling can be suppressed more and stress relaxation property improves more. In addition, the said weight average molecular weight and number average molecular weight are the values of polystyrene conversion measured by the gel permeation chromatography (GPC) method. Details of the GPC measurement method are described in the Examples.

  In the present invention, the acrylic polymer can be obtained by polymerizing a monomer mixture with a polymerization initiator. The polymerization may be a known polymerization method such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc., but solution polymerization is preferred in the present invention. Solvents that can be used in solution polymerization are preferably acetone, methyl acetate, ethyl acetate, toluene, xylene, anisole, methyl ethyl ketone, cyclohexanone, and the like. The polymerization temperature is preferably a boiling point reaction of 60 to 120 ° C., and the polymerization time is preferably 5 to 12 hours.

The polymerization initiator is not particularly limited as long as it is a compound capable of initiating polymerization, and known compounds such as peroxides and azo compounds can be used.
Examples of the peroxide include di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide, α, α′-bis (t-butylperoxy-m-isopropyl) benzene, 2,5- Dialkyl peroxides such as di (t-butylperoxy) hexyne-3;
peroxyesters such as t-butylperoxybenzoate, t-butylperoxyacetate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane;
Ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide;
2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t- Peroxyketals such as butylperoxy) cyclohexane and n-butyl-4,4-bis (t-butylperoxy) valate;
Hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylcyclohexane-2,5-dihydroperoxide;
Diacyl peroxides such as benzoyl peroxide, decanoyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide;
Examples thereof include organic peroxides such as peroxydicarbonates such as bis (t-butylcyclohexyl) peroxydicarbonate, and mixtures thereof.

Examples of the azo compounds include 2,2′-azobisbutyronitriles such as 2,2′-azobisisobutyronitrile (abbreviation: AIBN) and 2,2′-azobis (2-methylbutyronitrile). ;
2,2′-azobisvaleronitriles such as 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile);
2,2′-azobispropionitriles such as 2,2′-azobis (2-hydroxymethylpropionitrile);
1,1′-azobis-1-alkanenitriles such as 1,1′-azobis (cyclohexane-1-carbonitrile) can be used.

  The polymerization initiators can be used alone or in combination of two or more.

  The polymerization initiator is preferably used in an amount of 0.01 to 10 parts by weight, more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the monomer mixture.

  In the present invention, as the acrylic copolymer, one type of copolymer may be used alone, or two or more types of copolymers may be used in combination. When one type of copolymer is used alone, the copolymer to be used can be obtained by the above synthesis method (hereinafter referred to as “synthesis method 1”). Two or more kinds of acrylic copolymers (hereinafter referred to as “a mixture of acrylic copolymers”) can be obtained by various methods. For example, it is possible to obtain two kinds of acrylic copolymers separately, and to obtain a mixture of acrylic copolymers by mixing the two (hereinafter referred to as “synthesis method 2”, The mixing method is called “adjustment of acrylic copolymer”). Moreover, after obtaining a copolymer, a monomer is further polymerized in the presence of the obtained copolymer to obtain a mixture of acrylic copolymers as a composition containing two or more types of copolymers. (Hereinafter referred to as “synthesis method 3”). Further, in “Synthesis Method 3”, all the monomer raw materials to be used are charged, a polymerization reaction is performed to obtain a copolymer, and then a polymerization reaction is further performed to obtain a mixture of acrylic copolymers (hereinafter, “ Synthetic method 3-1 ”) and a part of the monomer raw material to be used, a polymerization reaction to obtain a copolymer, and then the remaining monomer raw material is again charged to carry out the polymerization reaction, thereby carrying out the acrylic copolymer. There is a method of obtaining a mixture of (hereinafter referred to as “synthesis method 3-2”).

  The pressure-sensitive adhesive of the present invention contains an isocyanate curing agent. Isocyanate-based curing agent crosslinks with acrylic polymer to form a resin network, thereby suppressing floating and peeling, light leakage, and high transparency even when exposed to high-temperature and high-humidity environments. The effect that can be maintained is obtained.

  In the present invention, the isocyanate curing agent is specifically an isocyanate monomer having two or more isocyanate groups, specifically an aromatic polyisocyanate, an aliphatic polyisocyanate, an araliphatic polyisocyanate, an alicyclic polyisocyanate. Preferred are isocyanate monomers such as burette, nurate and adducts.

  Examples of the aromatic polyisocyanate include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6 -Tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 ', Examples thereof include 4 "-triphenylmethane triisocyanate.

  Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HMDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, and 1,3-butylene diisocyanate. , Dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate and the like.

  Examples of the araliphatic polyisocyanate include ω, ω′-diisocyanate-1,3-dimethylbenzene, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω, ω′-diisocyanate-1,4-diethylbenzene. 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, and the like.

  Examples of the alicyclic polyisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (also known as IPDI, isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1, Examples include 4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanate methyl) cyclohexane, and the like. .

  The burette body refers to a self-condensate having a burette bond in which the isocyanate monomer is self-condensed. Specific examples include a burette of hexamethylene diisocyanate.

  The nurate body refers to a trimer of the isocyanate monomer, and examples thereof include a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, and a trimer of tolylene diisocyanate.

  The adduct body is a bifunctional or higher functional isocyanate compound obtained by reacting the isocyanate monomer with a bifunctional or higher molecular weight active hydrogen-containing compound. For example, a compound obtained by reacting trimethylolpropane and hexamethylene diisocyanate (trimethylolpropane). A compound obtained by reacting trimethylol propane with xylylene diisocyanate, a compound obtained by reacting trimethylol propane with xylylene diisocyanate, a compound obtained by reacting trimethylol propane with isophorone diisocyanate, 1,6-hexanediol and hexamethylene diisocyanate. Examples thereof include reacted compounds.

Examples of the bifunctional or higher functional low molecular active hydrogen-containing compound include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, and 3,3′-dimethylol. Heptane, 2-methyl-1,8-octanediol, 3,3′-dimethylolheptane, 2-butyl-2-ethyl-1,3-propanediol, polyoxyethylene glycol (additional number of moles of ethylene oxide of 10 or less ), Polyoxypropylene glycol (additional mole number of propylene oxide of 10 or less), 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonane Diol, neopentyl glycol, butyl ethyl penta Diol, 2-ethyl-1,3-hexanediol, cyclohexanediol, cyclohexanedimethanol, tricyclodecanedimethanol, cyclopentadiene engine methanol, aliphatic or alicyclic diols and dimer diol;
1,3-bis (2-hydroxyethoxy) benzene, 1,2-bis (2-hydroxyethoxy) benzene, 1,4-bis (2-hydroxyethoxy) benzene, 4,4′-methylenediphenol, 4, 4 ′-(2-norbornylidene) diphenol, 4,4′-dihydroxybiphenol, o-, m-, and p-dihydroxybenzene, 4,4′-isopropylidenephenol, or bisphenols such as bisphenol A and bisphenol F Aromatic diols such as bisphenols obtained by adding alkylene oxide such as ethylene oxide and propylene oxide to
1,1,1-trimethylolpropane, 1,1,1-trimethylolbutane, 1,1,1-trimethylolpentane, 1,1,1-trimethylolhexane, 1,1,1-trimethylolheptane, 1,1,1-trimethyloloctane, 1,1,1-trimethylol nonane, 1,1,1-trimethyloldecane, 1,1,1-trimethylolundecane, 1,1,1-trimethyloldodecane, 1,1,1-trimethylol tridecane, 1,1,1-trimethylol tetradecane, 1,1,1-trimethylol pentadecane, 1,1,1-trimethylol hexadecane, 1,1,1-trimethylol hepta Decane, 1,1,1-trimethylol octadecane, 1,1,1-trimethylol nanodecane, 1,1,1-trimethylol-sec Butane, 1,1,1-trimethylol-tert-pentane, 1,1,1-trimethylol-tert-nonane, 1,1,1-trimethylol-tert-tridecane, 1,1,1-trimethylol- tert-heptadecane, 1,1,1-trimethylol-2-methyl-hexane, 1,1,1-trimethylol-3-methyl-hexane, 1,1,1-trimethylol-2-ethyl-hexane, , 1,1-trimethylol-3-ethyl-hexane, trimethylol branched alkanes such as 1,1,1-trimethylolisoheptadecane, trimethylolbutene, trimethylolheptene, trimethylolpentene, trimethylolhexene, Trimethylol heptene, trimethylol octene, trimethylol decene, trimethylol dode , Trimethylol tridecene, trimethylol pentadecene, trimethylol hexadecene, trimetroleheptadecene, trimethylol octadecene, 1,2,6-butanetriol, 1,2,4-butanetriol, glycerin, etc. Kind;
Tetrafunctional or higher functional polyols such as pentaerythritol, dipentaerythritol, sorbitol, xylitol;
Ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, hexylenediamine, heptylenediamine, octylenediamine, nonylenediamine, diaminodicyclohexylmethane, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 1, Aliphatic polyamines such as 3-bis (aminomethyl) cyclohexane, triethylenetetramine, diethylenetriamine, triaminopropane;
Aromatic polyamines such as phenylenediamine, tolylenediamine, diaminodiphenylmethane, diaminodiphenyl ether;
Ethylenedithiol, propylenedithiol, butylenedithiol, pentylenedithiol, hexylenedithiol, heptylenedithiol, octylenedithiol, nonylenedithiol, dimercaptodicyclohexylmethane, 3-mercaptomethyl-3,5,5-trimethylcyclohexylthiol, Examples include polythiols such as 1,3-bis (mercaptomethyl) cyclohexane, 1,4-bis (3-mercaptobutyryloxy) butane, and pentaerythritol tetrakis (3-mercaptobutyrate).

  These polyfunctional low molecular active hydrogen-containing compounds can be used alone or in combination of two or more.

  From the viewpoint of forming a sufficient cross-linked structure, the isocyanate curing agent is preferably a trifunctional isocyanate compound, and more preferably an adduct that is a reaction product of an isocyanate monomer and a trifunctional low molecular active hydrogen-containing compound. Specifically, a trimethylolpropane adduct of hexamethylene diisocyanate, a trimethylolpropane adduct of tolylene diisocyanate, a trimethylolpropane adduct of isophorone diisocyanate, a nurate of isophorone diisocyanate, and a trimethylolpropane adduct of xylylene diisocyanate are preferred. Furthermore, araliphatic polyisocyanate compounds such as a trimethylolpropane adduct of tolylene diisocyanate and a trimethylolpropane adduct of xylylene diisocyanate are preferred. These polyisocyanate compounds can be used alone or in combination of two or more.

  The isocyanate-based curing agent is preferably contained in 0.05 parts by weight to 20 parts by weight or less in 100 parts by weight of the acrylic copolymer, and more than 0.1 parts by weight to 15 parts by weight or less. Is more preferable. When the content is 0.05 parts by weight or more, the cohesive force is further improved. When the content is 20 parts by weight or less, it becomes easy to achieve both cohesion and stress relaxation properties.

  In the pressure-sensitive adhesive of the present invention, other curing agents can be used in combination as long as the effects of the present invention are not impaired. Specific examples include an epoxy compound, an aziridine compound, an acid anhydride group-containing compound, a carbodiimide compound, an N-methylol group-containing compound, and a metal chelate compound.

  Examples of the epoxy compound include bisphenol A-epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, and 1,6-hexanediol diglycidyl ether. , Trimethylolpropane triglycidyl ether, diglycidyl aniline, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N , N, N ′, N′-tetraglycidylaminophenylmethane and the like.

  Examples of the aziridine compound include N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxite), N, N′-toluene-2,4-bis (1-aziridinecarboxite), and bisisophthalo. Yl-1- (2-methylaziridine), tri-1-aziridinylphosphine oxide, N, N′-hexamethylene-1,6-bis (1-aziridinecarboxite), 2,2′-bishydroxymethyl Butanol-tris [3- (1-aziridinyl) propionate], trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethanetri-β-aziridinylpropionate, tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, 4,4′-bis (ethyleneiminocarbonylamino) diph Nirumetan, and the like.

  Examples of the carbodiimide compound include a high molecular weight polycarbodiimide produced by decarboxylation condensation reaction of a diisocyanate compound in the presence of a carbodiimidization catalyst. Examples of such high molecular weight polycarbodiimides include Nisshinbo's Carbodilite series. Among these, Carbodilite V-01, 03, 05, 07, and 09 are preferable because of excellent compatibility with organic solvents.

  The acid anhydride group-containing compound is a compound having two or more carboxylic acid anhydride groups and is not particularly limited, but includes tetracarboxylic dianhydride, hexacarboxylic dianhydride, hexacarboxylic dianhydride. And a maleic anhydride copolymer resin. In addition, polycarboxylic acid, polycarboxylic acid ester, polycarboxylic acid half ester, and the like that can be converted into an anhydride via a dehydration reaction during the reaction are included in the “acid anhydride group-containing compound” of the present invention.

  Examples of the tetracarboxylic dianhydride include pyromellitic anhydride, benzophenonetetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, oxydiphthalic dianhydride, diphenylsulfonetetracarboxylic dianhydride, diphenylsulfidetetracarboxylic Examples thereof include acid dianhydride, butanetetracarboxylic dianhydride, perylenetetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride and the like.

  Examples of the metal chelate compounds include coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium, and acetylacetone or ethyl acetoacetate. It is done. Specific examples include aluminum ethyl acetoacetate / diisopropylate, aluminum trisacetylacetonate, aluminum bisethylacetoacetate / monoacetylacetonate, and aluminum alkylacetoacetate / diisopropylate.

  These other curing agents can be used alone or in combination of two or more.

  The pressure-sensitive adhesive of the present invention contains a silane coupling agent. By using the silane coupling agent, floating and peeling when exposed to a high temperature atmosphere or a high temperature and high humidity atmosphere can be suppressed.

Examples of the silane coupling agent include 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropyltripropoxysilane, and 3- (meth). An alkoxysilane compound having a (meth) acryloxy group such as acryloxypropyltributoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxypropylmethyldiethoxysilane;
Alkoxysilane compounds having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane;
3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N- (2-aminoethyl)- 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) Alkoxysilane compounds having an amino group, such as -3-aminopropylmethyldiethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane;
Alkoxysilane compounds having a mercapto group such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane;
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropylmethyldimethoxysilane, Alkoxysilane compounds having an epoxy group such as 3-glycidoxypropylmethyldiethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane;
Tetraalkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane;
3-chloropropyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, styryltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, 1,3,5-tris (3-trimethoxysilylpropyl) isocyanurate, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyl Examples thereof include triethoxysilane, hexamethyldisilazane, and a silicone resin having an alkoxysilyl group in the molecule.

  The silane coupling agent is preferably used in an amount of 0.01 to 2 parts by weight, more preferably 0.05 to 1 part by weight, based on 100 parts by weight of the acrylic copolymer (A).

  In the pressure-sensitive adhesive of the present invention, various resins, oils, softeners, dyes, pigments, antioxidants, ultraviolet absorbers, weathering stabilizers, plasticizers, and the like as long as the effects of the present invention are not impaired. You may mix | blend a filler, anti-aging agent, an antistatic agent, etc.

  The pressure-sensitive adhesive of the present invention is suitable as a pressure-sensitive adhesive for optical members, as well as various plastic sheets, general labels and seals, paints, elastic wall materials, waterproof coating materials, flooring materials, tackifiers, pressure-sensitive adhesives, and laminates. Structural adhesives, sealing agents, molding materials, surface modification coating agents, binders (magnetic recording media, ink binders, casting binders, fired brick binders, graft materials, microcapsules, glass fiber sizing, etc.), urethane foam ( (Hard, semi-rigid, soft), urethane RIM, UV / EB curable resin, high solid paint, thermosetting elastomer, microcellular, textile processing agent, plasticizer, sound absorbing material, vibration damping material, surfactant, gel coat agent, Resin for artificial marble, impact modifier for artificial marble, resin for ink, film (laminate adhesive, protective film) Beam, etc.), laminated glass resin, reactive diluent, various molding materials, elastic fiber, artificial leather, as a raw material for synthetic leather, can also very effectively used as various resin additives and a raw material thereof or the like.

  The pressure-sensitive adhesive sheet of the present invention includes a base material and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive of the present invention. The pressure-sensitive adhesive sheet can be obtained, for example, by forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive to a substrate and drying it. Moreover, an adhesive is applied to the peelable sheet and dried to form an adhesive layer, and the substrate is bonded. In addition, the adhesive layer should just be provided in the at least one surface of the base material. In the present invention, a sheet, a film and a tape are synonymous. Needless to say, the peelable sheet is bonded to the surface of the pressure-sensitive adhesive layer that is not in contact with the base material.

  When applying the adhesive, a suitable liquid medium, for example, a hydrocarbon solvent such as toluene, xylene, hexane, heptane; an ester solvent such as ethyl acetate or butyl acetate; a ketone solvent such as acetone or methyl ethyl ketone; The viscosity can be adjusted by adding halogenated hydrocarbon solvents such as dichloromethane and chloroform; ether solvents such as diethyl ether, methoxytoluene and dioxane, and other hydrocarbon solvents. The pressure-sensitive adhesive can be heated to reduce the viscosity. However, since water, alcohol, etc. inhibit the crosslinking reaction of an acrylic copolymer (B) and a polyisocyanate compound, it is preferable to avoid use.

  Examples of the substrate include cellophane, plastic, rubber, foam, cloth, rubber cloth, resin-impregnated cloth, glass plate, and wood. The substrate may be plate-shaped or film-shaped. Moreover, the structure which laminated | stacked the base material independently or several base materials is also preferable.

  Examples of the plastic include polyolefin resins such as polyvinyl alcohol, triacetyl cellulose, polypropylene, polyethylene, polycycloolefin, and ethylene-vinyl acetate copolymer, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Polycarbonate resin, polynorbornene resin, polyarylate resin (PAR: copolymer resin of bisphenol A and phthalic acid), polyacrylic resin, polyphenylene sulfide resin, polystyrene resin, polyamide resin, polyimide resin, epoxy resin Examples thereof include resins (resins obtained by reacting epoxy group-containing resins with polyamines or carboxylic anhydrides).

  In the present invention, the pressure-sensitive adhesive can be applied by a known method. For example, Mayer bar, applicator, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, knife coater, reverse coater, spin coater and the like can be mentioned. There is no restriction | limiting in particular in a drying method, The thing using hot air drying, infrared rays, and the pressure reduction method is mentioned. The drying condition may be hot air heating of about 60 to 160 ° C.

  0.1-300 micrometers is preferable and, as for the thickness of an adhesive layer, 1-100 micrometers is more preferable. When the thickness is less than 0.1 μm, sufficient adhesive strength may not be obtained, and even when the thickness exceeds 300 μm, the performance such as adhesive strength is often not improved.

  The pressure-sensitive adhesive sheet of the present invention can be suitably used for laminating optical members. That is, it is preferable to use an optical member for the substrate. Specific examples of the optical member include a polarizing plate, a retardation film, an elliptically polarizing film, an antireflection film, and a brightness enhancement film.

  It is also preferable that the pressure-sensitive adhesive sheet of the present invention using an optical member as a base material is attached to a glass member of a liquid crystal cell and used as a liquid crystal cell member. When the optical member is a polarizing plate, even when left in a high-temperature atmosphere and a high-temperature and high-humidity atmosphere, the pressure-sensitive adhesive layer has good stress relaxation properties, so that light leakage due to warping of the polarizing plate can be suppressed.

  The pressure-sensitive adhesive sheet of the present invention can be preferably used for various electronics-related members such as liquid crystal displays, plasma displays, touch panels, and electrode peripheral members, protective films, building materials, glass members such as vehicle window glass, polyolefin, ABS, acrylic, etc. It can also be used for metals such as plastic, cardboard, wood, plywood, stainless steel and aluminum.

  EXAMPLES Next, although an Example of this invention is shown and it demonstrates still in detail, this invention is not limited by these. In the examples, “part” means “part by weight”, and “%” means “% by weight”.

[Synthesis Method 1]
A method for obtaining one kind of acrylic copolymer.
<Synthesis Example 1: Acrylic copolymer>
In a reaction vessel (hereinafter simply referred to as “reaction vessel”) equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 1.0 part of 2-hydroxyethyl acrylate, 1.0 part of acrylamide Part, methyl acrylate 15 parts, methyl methacrylate 5, butyl acrylate 78 parts, acetone 100 parts, 2,2′-azobisisobutyronitrile (hereinafter referred to as AIBN) 0.025 parts, and this reaction vessel The air inside was replaced with nitrogen gas. Then, it heated to 80 degreeC, stirring under nitrogen atmosphere, and reaction was started. Thereafter, the reaction solution was reacted at reflux temperature for 7 hours. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain a copolymer solution having a nonvolatile content of 30% and a viscosity of 8000 mPa · s. Moreover, when the weight average molecule | numerator (Mw) of the acrylic copolymer was measured using GPC, the weight average molecular weight was 1.5 million and molecular weight distribution (Mw / Mn) 15. The obtained copolymer is referred to as “acrylic copolymer (A-1)”.

<Synthesis Examples 2 to 10>
Various raw materials were charged according to the weight ratio in Table 2, and an acrylic copolymer was synthesized in the same manner as in Synthesis Example 1. Table 2 shows the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the resulting acrylic copolymer.

[Synthesis Method 2]
A method of obtaining a mixture of acrylic copolymers by separately obtaining two types of acrylic copolymers and mixing them.

<Synthesis Examples 11-15>
Various raw materials were charged according to the weight ratio in Table 2, and an acrylic copolymer was synthesized in the same manner as in Synthesis Example 1. Table 2 shows the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the resulting acrylic copolymer.

<Synthesis Examples 16-20>
Various raw materials were charged according to the weight ratios shown in Table 2, and 100 parts by weight of acetone in Synthesis Example 1 was changed to 100 parts by weight of methyl ethyl ketone. Table 2 shows the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the resulting acrylic copolymer.

[Preparation of acrylic copolymer]
<Adjustment Examples 1 to 10>
The acrylic copolymers in the copolymer solutions obtained in Synthesis Examples 11 to 20 were mixed at a weight ratio (in terms of non-volatile content) shown in Table 3, and acrylic copolymer mixtures (B-1) to (B -10) was obtained. Table 3 shows the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the resulting acrylic copolymer.

[Synthesis Method 3]
A method in which after obtaining a copolymer containing an acrylic copolymer, a monomer is polymerized in the presence of the obtained copolymer to obtain a mixture of the acrylic copolymer.

[Synthesis Method 3-1]
A method in which all of the monomers (A) to (E) are charged, a polymerization reaction is performed to obtain a copolymer, and then a polymerization reaction is further performed to obtain a mixture of acrylic copolymers.
<Synthesis Example 21>
In a reaction vessel (hereinafter simply referred to as “reaction vessel”) equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 0.5 part of 2-hydroxyethyl acrylate, 1.0 part of acrylamide Parts, 15 parts of methyl acrylate, 5 parts of methyl methacrylate, 78.5 parts of butyl acrylate, 130 parts by weight of acetone and 0.025 part of AIBN, and the air in the reaction vessel was replaced with nitrogen gas. Thereafter, this reaction solution was reacted at reflux temperature for 2 hours while stirring under a nitrogen atmosphere, and the copolymerization of the copolymer and monomer having a monomer conversion ratio of 45% and a weight average molecular weight of 1.6 million was performed. A solution was obtained. Next, 140 parts of methyl ethyl ketone and 0.2 part of V-65 (2,2′-azobis (2,4-dimethylvaleronitrile), hereinafter referred to as “V-65”) manufactured by Wako Pure Chemical Industries, Ltd. are added. The reaction was continued for 2 hours, 0.2 parts of V-65 was further added, and the reaction was further continued for 6 hours until the polymerization conversion of the monomer reached 90% or more. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain a solution of a copolymer (C-1) having a nonvolatile content of 20 parts by weight and a viscosity of 2500 mPa · s. Table 4 shows the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the resulting acrylic copolymer mixture.

<Synthesis Examples 22-25>
Acrylic copolymers were obtained by synthesizing in the same manner as in Synthesis Example 21, except that the monomers in Synthesis Example 21 and the blending amounts thereof were changed as described in Table 4. Table 4 shows the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the resulting acrylic copolymer mixture.

[Synthesis Method 3-2]
After the monomers (A), (C) and (E) are charged and a polymerization reaction is carried out to obtain a copolymer, the monomers (B) and (D) are charged, and the polymerization reaction is further carried out to obtain an acrylic copolymer. Method to obtain a mixture.

<Synthesis Example 26>
In a reaction vessel (hereinafter simply referred to as “reaction vessel”) equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 2.0 parts of 2-hydroxyethyl acrylate and 10 parts of cyclohexyl acrylate Then, 82.0 parts of butyl acrylate, 130 parts by weight of acetone, and 0.025 part of AIBN were charged, and the air in the reaction vessel was replaced with nitrogen gas. Thereafter, this reaction solution was reacted at reflux temperature for 2 hours while stirring under a nitrogen atmosphere, and the copolymerization of the copolymer and monomer having a monomer conversion ratio of 45% and a weight average molecular weight of 1.6 million was performed. A solution was obtained. Subsequently, 140 parts of methyl ethyl ketone, 1.0 part of diacetone acrylamide, methyl methacrylate 5, V-65 (2,2′-azobis (2,4-dimethylvaleronitrile) manufactured by Wako Pure Chemical Industries, Ltd., hereinafter “V-65” ) 0.2 part is added and allowed to react for 2 hours, and further 0.2 part of V-65 is added and further reacted for 6 hours until the polymerization conversion of the monomer reaches 90% or more. It was. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain a solution of a copolymer (C-1) having a nonvolatile content of 20 parts by weight and a viscosity of 2500 mPa · s. Table 4 shows the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the resulting mixture of acrylic copolymers.

<Synthesis Examples 27-30>
An acrylic copolymer was obtained by synthesizing in the same manner as in Synthesis Example 26, except that the monomer of Synthesis Example 26 and the blending amount thereof were changed as described in Table 4. Table 4 shows the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the resulting acrylic copolymer mixture.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) was measured using GPC “LC-GPC system” manufactured by Shimadzu Corporation. GPC is liquid chromatography in which a substance dissolved in a solvent (THF; tetrahydrofuran) is separated and quantified by the difference in molecular size, and the weight average molecular weight (Mw) is determined in terms of polystyrene.
Device name: LC-GPC system “Prominence” manufactured by Shimadzu Corporation
Column: Tosoh Co., Ltd. 4 GMHXL and Tosoh Co., Ltd. HXL-H 1 were connected.
Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 ml / min
Column temperature: 40 ° C

Example 1
100 parts of an acrylic copolymer (A-1) in the copolymer solution obtained in Synthesis Example 1, 0.5 part by weight of an adduct of tolylene diisocyanate trimethylolpropane as an isocyanate curing agent, silane coupling As an agent, 0.1 part by weight of 3-glycidoxypropyltrimethoxysilane was blended, and ethyl acetate was further added to adjust the nonvolatile content to 20% to obtain a pressure-sensitive adhesive.

  The pressure-sensitive adhesive was coated on a 38 μm-thick polyethylene terephthalate peelable sheet (Therapy MF: manufactured by Toray Film Processing Co., Ltd.) as a base material so that the thickness after drying was 25 μm. The pressure-sensitive adhesive layer was formed by hot-air drying for minutes. Next, a laminated structure in which both surfaces of a polyvinyl alcohol (PVA) polarizing plate (HLC2-5618: manufactured by SANRITZ) are sandwiched between the pressure-sensitive adhesive layers as optical members by a triacetyl cellulose film (hereinafter referred to as “TAC film”). A polarizing plate pressure-sensitive adhesive sheet having a structure of “peeling film / pressure-sensitive adhesive layer / TAC film / PVA / TAC film” is obtained by laminating one side of the polarizing plate and then aging for one week at a temperature of 35 ° C. and a relative humidity of 55%. Obtained.

(Examples 2 to 30, Comparative Examples 1 to 10)
A pressure-sensitive adhesive was obtained in the same manner as in Example 1 according to the blending ratios in Tables 5 and 6. Further, a polarizing plate pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1.

The obtained polarizing plate adhesive sheet was evaluated by the following method.
(1) Evaluation of heat resistance and wet heat resistance The obtained polarizing plate pressure-sensitive adhesive sheet was prepared to have a width of 160 mm and a length of 120 mm. Next, the peelable sheet was peeled off and adhered to an alkali-free glass plate (1737: manufactured by Corning) using a laminator (VA-770A: Taisei Laminator Co., Ltd.) to obtain a liquid crystal cell member. Then, the said glass plate with which this polarizing plate adhesive sheet was affixed was hold | maintained for 20 minutes in the autoclave of conditions of 50 degreeC and 5 atmospheres, and the measurement sample was obtained by sticking each member closely. The measurement sample was evaluated for heat resistance as resistance evaluation in a high temperature atmosphere. That is, the measurement sample was allowed to stand at 85 ° C. for 500 hours and then visually observed for foaming, floating and peeling. In addition, the heat resistance of the measurement sample was evaluated as an evaluation of resistance in a high-temperature and high-humidity atmosphere. That is, the measurement sample was allowed to stand at 60 ° C. and a relative humidity of 95% for 500 hours and then visually observed for foaming, floating and peeling. Heat resistance and moist heat resistance were evaluated based on the following criteria.
A: “Foaming, floating and peeling are not recognized at all, and it is good”
○: “Bubbling, floating or peeling of 0.5 mm or less is recognized, but there is no practical problem”
X: “There is foaming, floating and peeling all over and cannot be used”

(2) Light Leakage Evaluation Two sheets of the obtained polarizing plate pressure-sensitive adhesive sheet having a width of 160 mm and a length of 120 mm were prepared. Next, the peelable sheet was peeled off, and two laminates were attached to both surfaces of the alkali-free glass plate using a laminator so that the absorption axes of the polarizing plates were orthogonal to each other. Subsequently, the pressure-bonded product was held in an autoclave at 50 ° C. and 5 atm for 20 minutes, and each member was brought into close contact with each other to obtain a measurement sample. The measurement sample was allowed to stand at 85 ° C. for 500 hours, and then light leakage when light was transmitted through the polarizing plate was visually observed. The light leakage was evaluated based on the following criteria.
A: “No white spots and good”
○: “There is a slight white spot, but there is no practical problem”
×: “There are white spots on the entire surface and cannot be used”

(3) Re-peelability (contamination) evaluation The obtained polarizing plate adhesive sheet was prepared for the width of 160 mm and the length of 120 mm. Next, the peelable sheet was peeled off and attached to a non-alkali glass plate using a laminator. Then, the measurement sample was obtained by making it hold | maintain for 20 minutes in the autoclave of conditions of 50 degreeC and 5 atmospheres, and closely_contact | adhering each member. After the measurement sample was left at 85 ° C. for 3 hours, a peeling test was performed in which the sample was pulled at a speed of 300 mm / min in the 180 ° direction using a tensile tester in an environment of 23 ° C. and 50% relative humidity. . Subsequently, the cloudiness of the glass surface after peeling was observed visually and evaluated based on the following criteria.
○: “Adhesive residue and cloudiness are not recognized and good”
×: “Adhesive residue, cloudiness is recognized and impractical”

(4) Adhesive strength evaluation The obtained polarizing plate adhesive sheet was prepared for the width | variety of 25 mm and the magnitude | size of length 100mm. Next, the peelable sheet was peeled off and attached to a non-alkali glass plate using a laminator. Then, the measurement sample was obtained by making it hold | maintain for 20 minutes in the autoclave of conditions of 50 degreeC and 5 atmospheres, and closely_contact | adhering each member. The measurement sample was allowed to stand at 23 ° C. for one day, and was then peeled at a peeling speed of 300 mm / min, peeling angle using a tensile tester (“Tensilon” manufactured by Orientec Co., Ltd.) in an environment of 23 ° C. and 50% relative humidity. The adhesive strength was measured under the condition of 180 ° (adhesive strength measurement one day after bonding). Moreover, after leaving the said measurement sample to stand at 23 degreeC for 14 days, adhesive force was measured by the same method (adhesion force measurement after 14 days of bonding).

  From the results of Tables 7 and 8, as shown in Examples 1 to 30, the pressure-sensitive adhesive of the present invention is excellent in durability in high temperature atmosphere and high temperature and high humidity atmosphere, stress relaxation property, and removability. On the other hand, Comparative Examples 1-10 were not able to satisfy | fill all the said characteristics.

Claims (8)

  The acrylic copolymer includes an acrylic copolymer, an isocyanate curing agent, and a silane coupling agent. The acrylic copolymer includes a hydroxyl group-containing monomer (A), an amide group-containing monomer (B) (provided that the monomer (A )), The monomer (C) having a glass transition temperature of 0-50 ° C. (except for the monomer (A) and the monomer (B)), and the glass transition temperature of the homopolymer being 60-150 ° C. A pressure-sensitive adhesive obtained by polymerizing a monomer mixture containing a monomer (D) (excluding the monomer (A) and the monomer (B)) and another monomer (E).   The pressure-sensitive adhesive according to claim 1, wherein the monomer (C) is an alkyl acrylate ester or an alkyl cycloalkyl ester having an alkyl group having 1 to 3 carbon atoms.   The pressure-sensitive adhesive according to claim 1 or 2, wherein the monomer (D) is a (meth) acrylic acid alkyl ester or a (meth) acrylic acid cycloalkyl ester having an alkyl group having 1 to 3 carbon atoms. Agent.   The pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the acrylic copolymer has a molecular weight distribution of 10 to 40.   Monomer (C) having a hydroxyl group-containing monomer (A) of 0.05 to 5 parts by weight, an amide group-containing monomer (B) of 0.1 to 5 parts by weight, and a homopolymer having a glass transition temperature of 0 to 50 ° C. ) 4 to 40 parts by weight, 2 to 30 parts by weight of monomer (D) having a glass transition temperature of 60 to 150 ° C., and 20 to 93.85 parts by weight of other monomer (E), Item 5. The pressure-sensitive adhesive according to any one of items 1 to 4.   The adhesive sheet provided with a base material and the adhesive layer formed from the adhesive of any one of Claims 1-5.   A polarizing plate pressure-sensitive adhesive sheet comprising a polarizing plate and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive according to claim 1.   A liquid crystal cell member comprising a glass plate, a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive according to claim 1, and an optical member.