JP6679985B2 - Adhesive and adhesive sheet using the same - Google Patents

Description

  The present invention relates to an adhesive, an adhesive sheet, a polarizing plate adhesive sheet, and a liquid crystal cell member. More specifically, the present invention relates to a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, a polarizing plate pressure-sensitive adhesive sheet and a liquid crystal cell member that can be suitably used for a substrate such as plastic or glass.

  Display devices such as liquid crystal displays, which are used in various devices such as electronic calculators, electronic clocks, mobile phones, televisions, and other household and commercial appliances, are becoming larger in size, and particularly liquid crystal televisions and plasma televisions. Is significantly larger. Further, in recent years, touch panel type liquid crystal displays such as smartphones and tablets have been rapidly spread, 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 so that they can be used in harsh vehicle environments such as high temperature and high humidity environments. Further, liquid crystal displays use polarizing plates and retardation plates having various optical functions, and these are used for adherends such as liquid crystal cells using glass or transparent plastic through an adhesive. Attached.

  The polarizing plate is generally a laminated body in which a polyvinyl alcohol film is sandwiched between triacetyl cellulose film and cycloolefin film. Since these films have different mechanical characteristics, the dimensional change rate at the time of heating is different. Therefore, when placed in a high-temperature atmosphere, the laminate often warps.

  Here, for example, when a liquid crystal cell member of polarizing plate / adhesive layer / glass (glass is a surface member of a liquid crystal cell) is left in a high temperature atmosphere, warpage occurs due to the dimensional change rate between the constituent members of the polarizing plate. In some cases, problems may occur such as bubbles (foaming) occurring at the bonding interface between the pressure-sensitive adhesive layer and the glass, and the polarizing plate floating and peeling from the glass. Further, the stress distribution of the liquid crystal cell member becomes non-uniform due to the warp, and the stress concentrates on the peripheral end portions of the liquid crystal cell member, so that light leaks from the four corners and the peripheral end portions of the liquid crystal cell member. A problem called "light leakage phenomenon" may occur. The above problem similarly 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, if the bonding position is misaligned, the polarizing plate should be mounted after a certain time has elapsed after bonding. Peeling and reuse of an expensive liquid crystal cell are performed. Therefore, the pressure-sensitive adhesive is required to have the property (reworkability) that the polarizing plate can be re-peeled from the liquid crystal cell after a certain time has passed from the application.

  In order to solve these problems, in Patent Document 1, in order to impart removability, the acid value is high and the weight average molecular weight of 0.2 to 10% with respect to a high molecular weight acrylic polymer having a weight average molecular weight of 500,000 or more. A technique for blending 100,000 low molecular weight acrylic polymers is disclosed. However, the pressure-sensitive adhesive described in Patent Document 2 has removability, but has a problem of poor light leakage and long-term durability.

  Further, in Patent Document 2, a hydroxy group- and alkylene oxide group-containing acrylic copolymer and a polyfunctional isocyanate-based curing agent are used to construct an interpenetrating network structure in a cured state, thereby causing the separation in a high-temperature and high-humidity environment. A technique for suppressing the above is disclosed. However, the pressure-sensitive adhesive described in Patent Document 5 has a problem that when left in a high-temperature and high-humidity environment for a long period of time, the alkylene oxide group is decomposed to cause floating and peeling.

  On the other hand, in Patent Document 3, depolarization including an acrylic copolymer having a glass transition temperature of −55 ° C. or higher and lower than 0 ° C. and an acrylic copolymer having a glass transition temperature of 0 ° C. or higher and 180 ° C. or lower is performed. A water-dispersible pressure-sensitive adhesive that is hard to cause is disclosed. However, the pressure-sensitive adhesive described in Patent Document 4 has a problem that the adherend such as glass is contaminated by various additives used for the pressure-sensitive adhesive.

  Further, Patent Document 4 discloses a technique in which the durability and removability of the pressure-sensitive adhesive are compatible by using a polyether-modified silicone and a silane coupling agent in combination. However, the pressure-sensitive adhesive described in Patent Document 6 has high transparency immediately after being processed into a pressure-sensitive adhesive sheet and attached to a substrate, and can be peeled off again, but the compatibility between the polyether-modified silicone and the acrylic polymer is poor. There has been a problem that after a long period of time since application, phase separation occurs in the pressure-sensitive adhesive layer, and transparency and removability deteriorate.

JP, 2010-100170, A JP, 2014-055299, A JP, 2014-1365, A JP, 2010-159346, A

  The problems to be solved by the present invention are, in order to solve the above problems, excellent removability when used in a pressure-sensitive adhesive sheet, and after being exposed to a high temperature environment or a high temperature and high humidity environment, an adherend It is an object of the present invention to provide a pressure-sensitive adhesive that is unlikely to be lifted or peeled off from the body and a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive. Furthermore, when it is used for fixing a polarizing plate, light leakage is extremely small, and it has good adhesive strength capable of maintaining high transparency even when exposed to a high temperature and high humidity environment. An object of the present invention is to provide a pressure-sensitive adhesive having good removability that does not contaminate water and a pressure-sensitive adhesive sheet using the same.

  The present inventors arrived at the present invention as a result of extensive studies to solve the above problems. That is, the present invention is a pressure-sensitive adhesive containing an acrylic copolymer (A), an acrylic copolymer (B), and a crosslinking agent (C), wherein the acrylic copolymer (A) is used. However, in 100 parts by mass of the acrylic copolymer (A), 0.1 to 5 parts by mass of the hydroxyl group-containing monomer (a-1) unit and the homopolymer have a glass transition temperature of 0 to 100 ° C. (meth) acryl. 10 to 50 parts by mass of the acid alkyl ester monomer (a-2) unit, and other monomer (a-3) unit copolymerizable with the above (a-1) and (a-2) (provided that (a-3) Is an acrylic copolymer having a weight average molecular weight of 800,000 to 2,000,000 and containing 45 to 89.9 parts by mass (excluding (a-1) and (a-2)). The polymer (B) is fluorine in 100 parts by mass of the acrylic copolymer (B). 0.01 to 5 parts by mass of a monomer-containing (b-1) unit or a silicon-containing monomer (b-2) unit, and a (meth) acrylic acid alkyl ester monomer unit (b) in which the homopolymer has a glass transition temperature of less than 0 ° C. -3) A pressure-sensitive adhesive characterized in that it is an acrylic copolymer containing 95 to 99.99 parts by mass and having a weight average molecular weight of 5,000 to 200,000.

  The present invention also relates to the above pressure-sensitive adhesive, wherein the silicon-containing monomer (b-2) is a silicon-containing monomer having a structure represented by the following formula [1].

(In the formula, n is an integer representing a repeating unit, and 1 ≦ n ≦ 150.)

  Further, in the present invention, the pressure-sensitive adhesive wherein the ratio of the acrylic polymer (A) and the acrylic polymer (B) is (A) / (B) = 95/5 to 50/50 by mass ratio. Regarding agents.

  The present invention also relates to the above pressure-sensitive adhesive, wherein the crosslinking agent (C) is an isocyanate compound.

  The present invention also relates to a pressure-sensitive adhesive sheet including a base material and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive.

  The present invention also relates to a polarizing plate pressure-sensitive adhesive sheet comprising a polarizing plate and a pressure-sensitive adhesive layer formed from the above pressure-sensitive adhesive.

  The present invention also relates to a liquid crystal cell member including a glass plate, a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive, and an optical member.

  According to the present invention, a pressure-sensitive adhesive sheet having excellent removability, which is unlikely to float or peel off from an adherend such as glass or plastics after being exposed to a high temperature environment or a high temperature and high humidity environment, and is unlikely to cause light leakage. We are now able to provide an adhesive that can create

  Hereinafter, the present invention will be described in detail. In addition, in this specification, a (meth) acrylic acid ester means the generic name of acrylic acid ester and methacrylic acid ester.

<Adhesive>
The pressure-sensitive adhesive of the present invention is characterized by containing the acrylic copolymer (A), the acrylic copolymer (B) and the crosslinking agent (C).

<Acrylic copolymer (A)>
The acrylic copolymer (A) is a (meth) acrylic acid alkyl ester having a hydroxyl group-containing monomer (a-1) unit as a monomer unit constituting the copolymer and a homopolymer glass transition temperature of 0 to 100 ° C. A copolymer containing a monomer unit (a-2) and another monomer (a-3) copolymerizable with the above-mentioned (a-1) and (a-2), and obtained by copolymerizing these monomers. You can

  The acrylic copolymer (A) contains a hydroxyl group-containing monomer (a-1). The hydroxyl group-containing monomer (a-1) means a monomer having a hydroxyl group (hereinafter, may be abbreviated as monomer (a-1)). The monomer (a-1) forms a polymer network through a cross-linking reaction with a cross-linking agent and forms a hydrogen bond with the surface of an adherend, thereby contributing to suppression of floating and peeling and suppression of light leakage.

  Specific examples of the monomer (a-1) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) acrylic acid 2 (Meth) acrylic acid such as -hydroxybutyl, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxyoctyl (meth) acrylate Glycol mono (meth) acrylic acid esters such as hydroxyalkyl ester, polyethylene glycol mono (meth) acrylic acid ester, polypropylene glycol mono (meth) acrylic acid ester, and 1,4-cyclohexanedimethanol mono (meth) acrylic acid ester, Caprolactone modified (meta Acrylic acid esters. These may be used alone or in combination of two or more.

  Among these monomers (a-1), 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate are preferable from the viewpoint of cohesive strength of the pressure-sensitive adhesive.

  The monomer (a-1) is contained as a monomer unit constituting the acrylic copolymer (A) in an amount of 0.1 to 5 parts by mass, preferably 0.1 to 2 parts by mass. When the content is 0.1 parts by mass or more, the cohesive force is further improved. Further, when the content is 5% by mass or less, it becomes easy to achieve both cohesive force and stress relaxation property.

  The acrylic copolymer (A) contains a (meth) acrylic acid alkyl ester monomer unit (a-2) having a homopolymer glass transition temperature of 0 to 100 ° C. (hereinafter, referred to as a monomer (a-2)). May be abbreviated). By using the monomer (a-2), the cohesive force of the pressure-sensitive adhesive is improved and a tough pressure-sensitive adhesive layer is obtained, which suppresses floating and peeling when exposed to a high temperature atmosphere or a high temperature and high humidity atmosphere. can do.

  Specific examples of the monomer (a-2) include methyl acrylate, tert-butyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, benzyl acrylate, butyl methacrylate, isobutyl methacrylate, and methacrylic acid. Examples include sec-butyl, stearyl methacrylate, isobornyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, phenyl methacrylate.

  Of these monomers (a-2), methyl acrylate, butyl methacrylate, and methyl methacrylate are preferable from the viewpoint of flexibility of the pressure-sensitive adhesive.

  The monomer (a-2) is contained as a monomer unit constituting the acrylic copolymer (A) in an amount of 10 to 50 parts by mass, preferably 15 to 40 parts by mass. When the content is 15 parts by mass or more, the cohesive force is further improved. Further, when the content is 45% by mass or less, it becomes easy to achieve both cohesive force and stress relaxation property.

  The acrylic copolymer (A) in the present specification is the other monomer (a-3) copolymerizable with the above-mentioned (a-1) and (a-2) (however, the monomer (a-3) is (Excluding (a-1) and (a-2)) (hereinafter sometimes abbreviated as monomer (a-3)). The monomer (a-3) improves flexibility of the pressure-sensitive adhesive and contributes to suppression of floating and peeling and suppression of light leakage.

  Examples of the monomer (a-3) include (meth) acrylic acid alkyl ester monomers having a homopolymer glass transition temperature of lower than 0 ° C., and other vinyl-based monomers.

  The (meth) acrylic acid alkyl ester monomer having a homopolymer glass transition temperature of lower than 0 ° C. has the same meaning as the monomer (b-3) described later, and specifically, ethyl acrylate, butyl acrylate, acrylic Examples thereof include acid pentyl, hexyl acrylate, heptyl acrylate, octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, and the like. Among these, butyl acrylate and 2-ethylhexyl acrylate are preferable from the viewpoint of easily obtaining good adhesive performance. These may be used alone or in combination of two or more.

  The monomer (a-3) is contained in an amount of 45 to 89.9% by mass, preferably 58 to 84.9% by mass, as a monomer unit constituting the acrylic copolymer (A). When the content is 45% by mass or more, the cohesive force is further improved. Further, when the content is 89.9% by mass or less, it becomes easy to achieve both cohesive force and stress relaxation property.

  The “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 the present specification, Tg is a value measured according to JIS K7121. Table 1 shows the measured glass transition temperatures of the homopolymers.

  Examples of the other vinyl monomers include amide bond-containing monomers, epoxy group-containing monomers, amino group-containing monomers, alkylene oxide unit-containing monomers, vinyl acetate, vinyl crotonic acid, styrene, and acrylonitrile. , As long as it is copolymerizable, it is not particularly limited thereto.

  Examples of the amide bond-containing monomer include (meth) acrylamide, N-methylacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-dimethylaminopropyl (meth) acrylamide, Contains a (meth) acrylamide-based compound such as diacetone acrylamide, N- (hydroxymethyl) acrylamide, N- (butoxymethyl) acrylamide, or a heterocycle such as N-vinylpyrrolidone, N-vinylcaprolactam, or acryloylmorpholine. Examples thereof include compounds, N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide and the like.

  Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, and 6-methyl-3,4 (meth) acrylate. -Epoxycyclohexylmethyl and the like.

  Examples of the amino group-containing monomer include (meth) acrylic acid monomethylaminoethyl, (meth) acrylic acid monoethylaminoethyl, (meth) acrylic acid monomethylaminopropyl, and (meth) acrylic acid monoethylaminopropyl. Examples thereof include (meth) acrylic acid monoalkylamino ester.

  The monomer having an alkylene oxide unit preferably has a unit such as ethylene oxide or propylene oxide. Specifically, for example, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-phenoxyethyl acrylate, methoxy polyethylene glycol (meth) acrylic acid ester, ethoxy polyethylene glycol (meth) acrylic acid ester, methoxy polypropylene. Examples thereof include glycol (meth) acrylic acid ester, ethoxy polypropylene glycol (meth) acrylic acid ester, phenoxy polyethylene glycol (meth) acrylic acid ester, and phenoxy polypropylene glycol (meth) acrylic acid ester.

  As other vinyl-based monomers, these monomers can be used alone or in combination of two or more kinds.

  The other vinyl-based monomer is preferably contained in the acrylic copolymer as a monomer unit constituting the copolymer in an amount of 0.1 to 10% by mass, more preferably 0.2 to 5% by mass. When the content is 0.1% by mass or more, the cohesive force is further improved. Further, when the content is 10% by mass or less, it becomes easy to achieve both cohesive force and stress relaxation property.

  The weight average molecular weight of the acrylic copolymer (A) is 800,000 to 2,000,000, and preferably 1,000,000 to 1,800,000. When the amount is in the range of 800,000 to 2,000,000, the cohesive force and the like are further improved, so that the floating and peeling can be further suppressed, and the stress relaxation property is further improved. The weight average molecular weight is a polystyrene equivalent value measured by gel permeation chromatography (GPC) method. Details of the GPC measurement method are described in Examples.

<Acrylic copolymer (B)>
The acrylic copolymer (B) is a glass of homopolymer and a monomer unit which is either a fluorine-containing monomer (b-1) unit or a silicon-containing monomer (b-2) unit as a monomer unit constituting the copolymer. It is a copolymer containing a (meth) acrylic acid alkyl ester monomer unit (b-3) having a transition temperature of less than 0 ° C., and can be obtained by copolymerizing these monomers.

  The fluorine-containing monomer (b-1) means a monomer having fluorine (hereinafter sometimes abbreviated as monomer (b-1)). The monomer (b-1) suppresses the progress of wetting of the pressure-sensitive adhesive on the surface of a polar adherend such as glass, and contributes to imparting reworkability. Further, by being copolymerized with another monomer, it is incorporated in the acrylic copolymer (B), so that the adherend can be prevented from being contaminated.

  Examples of the monomer (b-1) include trifluoromethane (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, ( Examples thereof include 1H, 1H, 5H-octafluoropentyl (meth) acrylic acid and 1H, 1H, 2H, 2H-tridecafluorooctyl (meth) acrylic acid. These may be used alone or in combination of two or more.

  Of these monomers (b-1), 2,2,2-trifluoroethyl acrylate and 2,2,3,3-tetrafluoropropyl acrylate are preferred from the viewpoint of imparting reworkability to the pressure-sensitive adhesive.

  The silicon-containing monomer (b-2) means a monomer having silicon (hereinafter, may be abbreviated as monomer (b-2)). The monomer (b-2) controls the progress of wetting of the pressure-sensitive adhesive onto the surface of a polar adherend such as glass, and contributes to imparting reworkability. Further, by being copolymerized with another monomer, it is incorporated in the acrylic copolymer (B), so that the adherend can be prevented from being contaminated.

As the monomer (b-2), a silicon-containing monomer having a structure represented by the formula [1] is preferable, and a monomer represented by the following formula [2] is more preferable.

In the above formula, R ₁ represents hydrogen or a methyl group. Of these, a methyl group is preferable. R ₂ represents an alkylene group having 1 to 6 carbon atoms. Of these, a propylene group is preferred. R ₃ represents an alkyl group having 1 to 6 carbon atoms. Of these, a butyl group is preferred. n is an integer representing a repeating unit and is an integer in the range of 1 ≦ n ≦ 150, preferably an integer in the range of 5 ≦ n ≦ 120, and more preferably an integer in the range of 10 ≦ n ≦ 80. preferable.

Of these monomers (b-2), Silaplane FM-0711 (manufactured by JNC: in the above formula [2], R ₁ is a methyl group, R ₂ is a propylene group, R ₃ is a butyl group, and n = 11. .) And Silaplane FM-0721 (manufactured by JNC: in the above formula [2], R ₁ is a methyl group, R ₂ is a propylene group, R ₃ is a butyl group, and n = 65).

  The monomer (b-1) or the monomer (b-2) is contained as a monomer unit constituting the acrylic copolymer (B) in an amount of 0.01 to 5 parts by mass, and 0.1 to 3 parts by mass. Is preferred. When the content is 0.01 parts by mass or more, the cohesive force is further improved. Further, when the content is 5% by mass or less, it becomes easy to achieve both cohesive force and stress relaxation property.

  The acrylic copolymer (B) has a homopolymer glass transition temperature of less than 0 ° C. (meth) acrylic acid alkyl ester monomer unit (b-3) (hereinafter, abbreviated as a monomer (b-3). There is). The monomer (b-3) improves flexibility of the pressure-sensitive adhesive and contributes to suppression of floating and peeling and suppression of light leakage.

  Examples of the monomer (b-3) include (meth) acrylic acid alkyl ester monomers having a homopolymer glass transition temperature of lower than 0 ° C.

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

  The (meth) acrylic acid alkyl ester monomer whose homopolymer has a glass transition temperature of lower than 0 ° C. is contained in an amount of 95 to 99.99 mass% as a monomer unit constituting the acrylic copolymer (B). When the content is 95% by mass or more, the cohesive force is further improved. Further, when the content is 99.99 mass% or less, it becomes easy to achieve both cohesive force and stress relaxation property.

  The weight average molecular weight of the acrylic copolymer (B) is 5,000 to 200,000, and preferably 10,000 to 100,000. When it is in the range of 5,000 to 200,000, the cohesive force and the like are further improved, so that the floating and peeling can be further suppressed, and the stress relaxation property is further improved.

  The pressure-sensitive adhesive of the present invention contains the acrylic copolymer (A), which is a high molecular weight component, and the acrylic copolymer (B), which is a low molecular weight component. In addition to the cohesive force, the presence of the acrylic copolymer (B) makes it possible to form an adhesive layer having a stress relaxation property. Furthermore, the acrylic copolymer (A) contains a hydroxyl group-containing monomer (a-1) unit, and exhibits excellent durability by performing a crosslinking reaction with a crosslinking agent (C) described later. Moreover, since the acrylic copolymer (B) contains the fluorine-containing monomer (b-1) unit or the silicon-containing monomer (b-2) unit, it exhibits excellent removability.

  In the pressure-sensitive adhesive of the present invention, the mass ratio of the acrylic polymer (A) to the acrylic polymer (B) is (A) / (B) = 95/5 to 50/50. Is preferable, and (A) / (B) = 90/10 to 80/20 is more preferable. If the acrylic polymer (B) is not contained, the stress concentration caused by the contraction of the polarizing plate cannot be alleviated and a light leakage phenomenon occurs. On the other hand, when only the acrylic polymer (B) is contained, the cohesive force of the pressure-sensitive adhesive layer is insufficient, and foaming, floating and peeling easily occur. After being placed under severe conditions, the acrylic polymer (A) and the acrylic polymer (B) are contained in a ratio of (A) / (B) = 95/5 to 50/50. However, an adhesive layer having good reworkability can be obtained.

  The pressure-sensitive adhesive of the present invention can be obtained by various methods. For example, it is possible to separately obtain the acrylic polymer (A) and the acrylic polymer (B) and mix them to obtain a desired copolymer mixture.

  The acrylic copolymers (A) and (B) can be obtained by polymerizing a monomer mixture. As the polymerization, known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization and suspension polymerization can be used, but solution polymerization is preferable. The solvent used in the solution polymerization is preferably acetone, methyl acetate, ethyl acetate, toluene, xylene, anisole, methyl ethyl ketone, cyclohexanone and the like. The polymerization temperature is preferably 60 to 120 ° C., and the polymerization time is preferably 5 to 12 hours.

A radical polymerization initiator is preferable as the polymerization initiator used in the polymerization. The radical polymerization initiator is not particularly limited as long as it is a compound capable of generating radicals at the polymerization temperature, and known compounds such as peroxides and azo compounds can be used.
As the peroxide, for example, 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 and 2,5-dimethyl-2,5-di (benzoylperoxy) hexane;
Ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and 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, n-butyl-4,4-bis (t-butylperoxy) valate;
Hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide and 2,5-dimethylcyclohexane-2,5-dihydroperoxide;
Diacyl peroxides such as benzoyl peroxide, decanoyl peroxide, lauroyl peroxide and 2,4-dichlorobenzoyl peroxide;
Examples thereof include organic peroxides such as peroxydicarbonates such as bis (t-butylcyclohexyl) peroxydicarbonate, or a mixture thereof.

Examples of the azo compound include 2,2′-azobisisobutyronitrile (abbreviation: AIBN), 2,2′-azobis (2-methylbutyronitrile), and other 2,2′-azobisbutyronitriles. ;
2,2′-azobisvaleronitriles such as 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) and 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 initiator can be used alone or in combination of two or more kinds. The polymerization initiator is preferably used in an amount of 0.01 to 10 parts by mass, more preferably 0.1 to 2 parts by mass, based on 100 parts by mass of the monomer mixture.

<Crosslinking agent (C)>
Next, the crosslinking agent (C) will be described. The cross-linking agent cross-links with the acrylic polymer to form a resin network, which prevents floating and peeling, suppresses light leakage, and maintains high transparency even when exposed to high temperature and high humidity environments. The effect that can be obtained is obtained.

  Examples of the cross-linking agent (C) include isocyanate compounds, epoxy compounds, aziridine compounds, acid anhydride group-containing compounds, carbodiimide compounds, N-methylol group-containing compounds, and metal chelate compounds.

  The above-mentioned isocyanate-based compound is specifically an isocyanate monomer having two or more isocyanate groups, specifically, an isocyanate such as an aromatic polyisocyanate, an aliphatic polyisocyanate, an araliphatic polyisocyanate, or an alicyclic polyisocyanate. Monomers and burettes, nurates and adducts are preferred.

  Aromatic polyisocyanates include, for example, 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 ', 4 “-Triphenylmethane triisocyanate and the like can be mentioned.

  Aliphatic polyisocyanates include, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HMDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, Dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate and the like can be mentioned.

  The araliphatic polyisocyanate is, for example, ω, ω′-diisocyanate-1,3-dimethylbenzene, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω, ω′-diisocyanate-1,4-diethylbenzene, Examples thereof include 1,4-tetramethylxylylene diisocyanate and 1,3-tetramethylxylylene diisocyanate.

  Examples of the alicyclic polyisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (also known as IPDI and isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, and 1,4. -Cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), 1,4-bis (isocyanatomethyl) cyclohexane and the like can be mentioned.

  The burette body refers to a self-condensate having a burette bond in which an isocyanate monomer self-condenses. Specifically, for example, a burette of hexamethylene diisocyanate and the like can be mentioned.

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

  The adduct is a bifunctional or higher functional isocyanate compound obtained by reacting an isocyanate monomer with a bifunctional or higher functional low-molecular-weight active hydrogen-containing compound. For example, a compound obtained by reacting trimethylolpropane and hexamethylene diisocyanate (trimethylolpropane and trifunctional). Compound reacted with diisocyanate, compound reacted with trimethylolpropane and xylylenediisocyanate, compound reacted with trimethylolpropane and isophorone diisocyanate, reacted with 1,6-hexanediol and hexamethylene diisocyanate And other compounds.

Examples of the bifunctional or higher functional low-molecular-weight active hydrogen-containing compound include, for example, ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane. , 2-methyl-1,8-octanediol, 3,3'-dimethylolheptane, 2-butyl-2-ethyl-1,3-propanediol, polyoxyethylene glycol (addition mole number of ethylene oxide of 10 or less) , Polyoxypropylene glycol (the number of moles of propylene oxide added is 10 or less), 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol. , Neopentyl glycol, butyl ethyl pentane di Lumpur, 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 oxides 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-trimethylol octane, 1,1,1-trimethylol nonane, 1,1,1-trimethylol decane, 1,1,1-trimethylol undecane, 1,1,1-trimethylol dodecane, 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 , 1,1-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 Trifunctional polyols such as benzene, trimethylol tridecene, trimethylol pentadecene, trimethylol hexadecene, trimethylol heptadecene, trimethylol octadecene, 1,2,6-butanetriol, 1,2,4-butanetriol and glycerin. Kind;
Tetra- 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 and 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 thereof include polythiols such as 1,3-bis (mercaptomethyl) cyclohexane, 1,4-bis (3-mercaptobutyryloxy) butane, and pentaerythritol tetrakis (3-mercaptobutyrate). These polyfunctional low molecular weight active hydrogen-containing compounds can be used alone or in combination of two or more kinds.

  From the viewpoint of forming a sufficient crosslinked structure, the isocyanate compound is preferably a trifunctional isocyanate compound, and more preferably an adduct which is a reaction product of an isocyanate monomer and a trifunctional low molecular weight active hydrogen-containing compound. Specifically, hexamethylene diisocyanate trimethylol propane adduct, tolylene diisocyanate trimethylol propane adduct, isophorone diisocyanate trimethylol propane adduct, isophorone diisocyanate nurate, xylylene diisocyanate trimethylol propane adduct. Further, araliphatic polyisocyanate compounds such as trimethylolpropane adduct of tolylene diisocyanate and trimethylolpropane adduct of xylylene diisocyanate are preferable. These polyisocyanate compounds may be used alone or in combination of two or more.

  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, 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'-tetraglycidyl aminophenyl methane etc. are mentioned.

  Examples of the aziridine compound include N, N'-diphenylmethane-4,4'-bis (1-aziridinecarboxite), N, N'-toluene-2,4-bis (1-aziridinecarboxite), and bisisophthaloyl. -1- (2-methylaziridine), tri-1-aziridinylphosphine oxide, N, N'-hexamethylene-1,6-bis (1-aziridinecarboxite), 2,2'-bishydroxymethylbutanol -Tris [3- (1-aziridinyl) propionate], trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethane tri-β-aziridinylpropionate, Tris-2,4,6- ( 1-aziridinyl) -1,3,5-triazine, 4,4′-bis (ethyleneiminocarbonylamino) dipheni Methane, and the like.

  Examples of the carbodiimide compound include a high molecular weight polycarbodiimide produced by a decarboxylation condensation reaction of a diisocyanate compound in the presence of a carbodiimidization catalyst. Examples of such a high molecular weight polycarbodiimide include the carbodilite series manufactured by Nisshinbo Industries. Among them, carbodilite V-01, 03, 05, 07, 09 is preferable because it has excellent compatibility with an organic solvent.

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

  The tetracarboxylic dianhydride is, for example, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, oxydiphthalic dianhydride, diphenylsulfone tetracarboxylic dianhydride, diphenyl sulfide tetracarboxylic acid. Examples thereof include dianhydride, butanetetracarboxylic dianhydride, perylenetetracarboxylic dianhydride, and naphthalenetetracarboxylic dianhydride.

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

  The cross-linking agent (C) can be used alone or in combination of two or more kinds. Among these crosslinking agents (C), a polyisocyanate-based compound is preferable, and a polyisocyanate-based compound is more preferable, from the viewpoint of achieving both substrate adhesion and removability.

  The cross-linking agent is preferably contained in an amount of 0.05 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, based on 100 parts by mass of the acrylic copolymer. When the content is 0.05 parts by mass or more, the cohesive force is further improved. When the content is 20 parts by mass or less, it becomes easy to achieve both cohesive force and stress relaxation property.

  The pressure-sensitive adhesive of the present invention may contain a silane coupling agent. By using the silane coupling agent, it is possible to further suppress the floating and peeling when exposed to a high temperature atmosphere or a high temperature and high humidity atmosphere.

The silane coupling agent is, for example, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropyltripropoxysilane, 3- (meth). Alkoxysilane compounds having a (meth) acryloxy group such as acryloxypropyltributoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, and 3- (meth) acryloxypropylmethyldiethoxysilane;
Alkoxysilane compounds having vinyl groups such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane and 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) An alkoxysilane compound 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 and 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 silicone resin having an alkoxysilyl group in the molecule.

  Among the above silane coupling agents, an alkoxysilane compound having an epoxy group is preferable, and 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane are more preferable.

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

  The adhesive of the present invention, as long as the effect of the present invention is not impaired, various resins, oils, softeners, dyes, pigments, antioxidants, ultraviolet absorbers, weathering stabilizers, plasticizers, as optional components. You may mix a filler, an antiaging 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, floor materials, tackifiers, pressure-sensitive adhesives, and laminates. Adhesives for structures, sealing agents, molding materials, coating agents for surface modification, binders (magnetic recording media, ink binders, casting binders, baked brick binders, graft materials, microcapsules, glass fiber sizing, etc.), urethane foam ( (Hard, semi-hard, soft), urethane RIM, UV / EB curable resin, high solid paint, thermosetting elastomer, microcellular, fiber processing agent, plasticizer, sound absorbing material, vibration damping material, surfactant, gel coating agent, Resin for artificial marble, impact resistance additive for artificial marble, resin for ink, film (laminate adhesive, protective film) 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.

<Adhesive sheet>
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 base material and drying. Further, it can be obtained by applying a pressure-sensitive adhesive to a peelable sheet and drying it to form a pressure-sensitive adhesive layer, and by bonding a base material. The pressure-sensitive adhesive layer may be provided on at least one surface of the base material. Also, sheets, films and tapes are synonymous in the present invention. It goes without saying that a peelable sheet is attached to the surface of the pressure-sensitive adhesive layer that is not in contact with the base material.

  When applying the pressure-sensitive 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 a halogenated hydrocarbon solvent such as dichloromethane or chloroform; an ether solvent such as diethyl ether, methoxytoluene or dioxane, or an organic solvent such as a hydrocarbon solvent. It is also possible to heat the adhesive to reduce the viscosity. However, it is preferable to avoid the use of water, alcohol, etc. because they inhibit the crosslinking reaction between the acrylic copolymer (B) and the polyisocyanate compound.

  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. The base material is also preferably a single base material or a structure in which a plurality of base materials are laminated.

  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, and polycarbonate. Resins, polynorbornene resins, polyarylate resins (PAR: copolymer resin of bisphenol A and phthalic acid), polyacrylic resins, polyphenylene sulfide resins, polystyrene resins, polyamide resins, polyimide resins, epoxy resins (A resin obtained by reacting an epoxy group-containing resin with a polyamine or carboxylic acid anhydride).

  In the present invention, the adhesive can be applied by a known method. Examples include Meyer bar, applicator, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, knife coater, reverse coater, spin coater and the like. The drying method is not particularly limited, and examples thereof include hot air drying, infrared rays, and a method using a reduced pressure method. The drying conditions may be heating with hot air at about 60 to 160 ° C.

  The thickness of the pressure-sensitive adhesive layer is preferably 0.1 to 300 μm, more preferably 1 to 100 μm. If the thickness is less than 0.1 μm, sufficient adhesive force may not be obtained, and even if the thickness exceeds 300 μm, the performance such as the adhesive force may not be further improved in many cases.

  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 as the base material. 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.

  The pressure-sensitive adhesive sheet of the present invention in which an optical member is used as a substrate is preferably used as a liquid crystal cell member by being attached to a glass member of a liquid crystal cell. When the optical member is a polarizing plate, the pressure-sensitive adhesive layer has a good stress relaxation property even when it is left in a high temperature atmosphere and a high temperature and high humidity atmosphere, and thus light leakage due to the warp of the polarizing plate can be suppressed.

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

  Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In the examples, "part" means "part by mass" and "%" means "% by mass", respectively.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) was measured by gel permeation chromatography (GPC) according to the following apparatus and measurement conditions. The weight average molecular weight (Mw) was determined by conversion using polystyrene as a standard substance.
Device name: LC-GPC system "Prominence" manufactured by Shimadzu Corporation
Column: Four Tohso GMHXL and one Tosoh HXL-H were connected in series.
Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 ml / min Column temperature: 40 ° C

<Synthesis Example 1: Acrylic copolymer (A)>
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, 79.9 parts by mass of butyl acrylate (BA) and acrylic acid 20 parts by mass of methyl (MA), 0.1 parts by mass of 2-hydroxyethyl acrylate (HEA), 100 parts of acetone, and 0.02 parts of 2,2′-azobisisobutyronitrile (hereinafter referred to as AIBN) are charged. The air in the reaction vessel was replaced with nitrogen gas. Then, the mixture was heated to 80 ° C. with stirring under a nitrogen atmosphere to start the reaction. Then, the reaction solution was reacted at the reflux temperature for 7 hours. After completion of the reaction, it was cooled and diluted with ethyl acetate to obtain a copolymer solution having a nonvolatile content of 20 parts by mass and a viscosity of 1500 mPa · s. Mw was 1.5 million. The obtained copolymer is referred to as a copolymer (A-1).

<Synthesis examples 2 to 11>
Acrylic copolymers were obtained by synthesizing in the same manner as in Synthesis Example 1 except that the monomers used in Synthesis Example 1 and the compounding amounts thereof were changed as described in Table 2. Table 2 shows the Mw of the obtained acrylic copolymer. The acrylic copolymers obtained in Synthesis Examples 2 to 5 were acrylic copolymers (A), and the acrylic copolymers obtained in Synthesis Examples 6 to 11 were acrylic copolymers (A). ) Is not an acrylic copolymer.

<Synthesis Example 12: Acrylic copolymer (B)>
99 parts of butyl acrylate (BA), acrylic acid 2,2 1 part of 2-trifluoroethyl (biscoat 3F, trade name: biscoat 3F, manufactured by Osaka Organic Chemical Industry Co., Ltd.), 100 parts of methyl ethyl ketone and 0.02 part of AIBN were charged, and the air in the reaction vessel was replaced with nitrogen gas. Then, the mixture was heated to 80 ° C. with stirring under a nitrogen atmosphere to start the reaction. Then, the reaction solution was reacted at the 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 20 parts by mass and a viscosity of 100 mPa · s. Mw was 5000. The obtained copolymer is referred to as a copolymer (B-1).

<Synthesis examples 13 to 19>
Acrylic copolymers were obtained by synthesizing in the same manner as in Synthesis Example 12 except that the monomers used in Synthesis Example 12 and the compounding amounts thereof were changed as described in Table 2. Table 2 shows the Mw of the obtained acrylic copolymer. The acrylic copolymers obtained in Synthesis Examples 13 to 16 are acrylic copolymers (B), and the acrylic copolymers obtained in Synthesis Examples 17 to 19 are acrylic copolymers (B). ) Is not an acrylic copolymer.

[Preparation of copolymer mixture]
<Adjustment example 1>
The copolymer (A-1) as the acrylic copolymer (A) and the copolymer (B-1) as the acrylic copolymer (B) are prepared as follows: (A) / (B) = 90/10 Mixing was carried out at a mass ratio (calculated as nonvolatile content) to obtain a solution of the copolymer mixture. The obtained copolymer mixture was designated as a copolymer mixture (1).

<Adjustment examples 2 to 19>
Copolymers obtained by mixing in the same manner as in Preparation Example 1 except that the acrylic copolymer (A) and the acrylic copolymer (B) used in Preparation Example 1 were changed as described in Table 3. A solution of the mixture was obtained.

(Example 1)
1 part of trimethylolpropane adduct of tolylene diisocyanate (C-1) as a cross-linking agent (C) and KBM as a silane coupling agent, based on a solution of the copolymer mixture (1) having a nonvolatile content of 100 parts. -403 (S-1,3-glycidoxypropyltrimethoxysilane: manufactured by Shin-Etsu Silicone Co., Ltd.) was added in an amount of 0.1 part, and further, ethyl acetate was added in an amount such that the nonvolatile content was 20% to give an adhesive. Obtained.

  The pressure-sensitive adhesive is applied onto a polyethylene terephthalate-releasing sheet having a thickness of 38 μm (Cerapeal MF: manufactured by Toray Film Co., Ltd.) so that the thickness after drying is 25 μm, and dried at 100 ° C. for 2 minutes. Thus, the pressure-sensitive adhesive layer was formed. Next, in this pressure-sensitive adhesive layer, a polarizing plate (HLC2-5618: manufactured by SANRITZ) having a laminated structure in which both sides of a polyvinyl alcohol (PVA) -based polarizer are sandwiched by triacetyl cellulose-based films (hereinafter, referred to as “TAC films”) One side of the above was bonded to obtain a pressure-sensitive adhesive sheet having a constitution of "release film / pressure-sensitive adhesive layer / TAC film / PVA / TAC film". Next, the obtained pressure-sensitive adhesive sheet was aged for 1 week under the conditions of a temperature of 35 ° C. and a relative humidity of 55% to obtain a laminate.

(Examples 2 to 20, Comparative Examples 1 to 10)
A pressure-sensitive adhesive was prepared in the same manner as in Example 1 except that the material copolymer mixture and the cross-linking agent (C) used in Example 1 were changed to the materials and blending amounts shown in Tables 4 and 5, respectively. Respectively obtained. Further, a pressure-sensitive adhesive sheet and a laminate were obtained in the same manner as in Example 1. The cross-linking agent (C) used in Examples and Comparative Examples is shown in Tables 4 and 5.

The obtained laminated body was evaluated by the following methods.
(1) Evaluation of Heat Resistance and Moisture and Heat Resistance The laminate obtained above was cut into a size of 160 mm in width and 120 mm in length. Then, the peelable sheet was peeled off from the cut out laminate, and the laminate was attached to a non-alkali glass plate using a laminator. Subsequently, the glass plate to which the laminate was attached was held in an autoclave under the conditions of 50 ° C. and 5 atm for 20 minutes to bring the respective members into close contact with each other to obtain a measurement sample. The heat resistance of this measurement sample was evaluated as resistance evaluation in a high temperature atmosphere. That is, after the measurement sample was left at 85 ° C. for 500 hours, the presence or absence of foaming, floating, and peeling was visually observed.
Further, the measurement sample was evaluated for wet heat resistance as resistance evaluation in a high temperature and high humidity atmosphere. That is, after the measurement sample was left at 60 ° C. and 95% relative humidity for 500 hours, the presence or absence of foaming, floating, and peeling was visually observed. Both heat resistance and moist heat resistance were evaluated based on the following criteria.
⊚: Good, no foaming, floating, or peeling was observed.
◯: Foaming, floating, or peeling of 0.5 mm or less is recognized, but there is no problem in practical use.
X: There is foaming, floating, and peeling on the whole surface, and it cannot be used.

(2) Evaluation of Light Leakage The laminate obtained above was cut into a size of 160 mm in width and 120 mm in length. Then, the peelable sheet was peeled from the cut laminated body, and two laminated bodies were attached to both surfaces of the non-alkali glass plate using a laminator so that the absorption axes of the polarizing plates were orthogonal to each other to obtain a pressure-bonded product. Obtained. Subsequently, the pressure-bonded product was held in an autoclave under the conditions of 50 ° C. and 5 atm for 20 minutes to bring the respective members into close contact with each other to obtain a measurement sample. After leaving this measurement sample at 85 ° C. for 500 hours, light leakage was visually observed when light was transmitted through the polarizing plate. The light leak property was evaluated based on the following criteria.
A: Good with no white spots.
◯: White spots are observed in only a part, but no white spots are observed in all, and there is no problem in practical use.
X: There is a blank area on the whole surface and it cannot be used.

(3) Evaluation of Removable Appearance The laminate obtained above was cut into a size of 160 mm in width and 120 mm in length. Then, the peelable sheet was peeled from the cut-out laminated body and attached to a non-alkali glass plate using a laminator. Subsequently, a measurement sample was obtained by holding each member in an autoclave under conditions of 50 ° C. and 5 atm for 20 minutes to bring them into close contact. This measurement sample was left at 85 ° C. for 3 hours, then, in an environment of 23 ° C. and relative humidity of 50%, using a tensile tester (“Tensilon” manufactured by Orientec Co., Ltd.), 180 mm at 300 mm / min. A peel test was carried out by pulling at a speed. Then, the haze on the glass surface after peeling was visually observed and evaluated based on the following criteria.
◯: No adhesive residue or cloudiness is observed, and the result is good.
X: Adhesive residue and cloudiness were observed, which is not practical.

(4) Evaluation of Removable Adhesion Strength The obtained laminate was cut into a size of 25 mm in width and 100 mm in length. Then, the peelable sheet was peeled from the cut-out laminated body and attached to a non-alkali glass plate using a laminator. Subsequently, a measurement sample was obtained by holding each member in an autoclave under conditions of 50 ° C. and 5 atm for 20 minutes to bring them into close contact. After leaving this measurement sample at 23 ° C. for 1 day, at a temperature of 23 ° C. and a relative humidity of 50%, using a tensile tester (“Tensilon” manufactured by Orientec Co., Ltd.), a peeling speed of 300 mm / min, a peeling angle The adhesive strength was measured under the condition of 180 ° and evaluated based on the following criteria.
A: The adhesive strength is less than 5 N / 25 mm, which is good.
◯: Adhesive strength is 5 N or more and less than 10 N / 25 mm, and there is no practical problem.
X: Adhesive strength is 10 N / 25 mm or more, which is not practical.
(5) Contamination evaluation of adherend The laminate obtained above was cut into a size of 160 mm in width and 120 mm in length. Then, the peelable sheet was peeled from the cut-out laminated body and attached to a non-alkali glass plate using a laminator. Subsequently, a measurement sample was obtained by holding each member in an autoclave under conditions of 50 ° C. and 5 atm for 20 minutes to bring them into close contact. This measurement sample was left in an environment of 60 ° C. and a relative humidity of 95% for 500 hours, the laminate was peeled by hand, and the contamination on the glass surface was visually observed, and evaluated based on the following criteria.
⊚: Good, with no contamination of the glass surface.
◯: Slight contamination of the glass surface is recognized, but there is no practical problem.
X: Contamination of the glass surface was confirmed, which is not practical.

  From the results of Table 6 and Table 7, as shown in Examples 1 to 20, the pressure-sensitive adhesive of the present invention has excellent durability in a high temperature atmosphere and a high temperature and high humidity atmosphere, light leakage, and removability. On the other hand, Comparative Examples 1 to 10 could not satisfy all of the above characteristics.

Claims (6)

A pressure-sensitive adhesive containing an acrylic copolymer (A), an acrylic copolymer (B), and a crosslinking agent (C),
The acrylic copolymer (A) has 0.1 to 5 parts by mass of a hydroxyl group-containing monomer (a-1) unit in 100 parts by mass of the acrylic copolymer (A), and the homopolymer has a glass transition temperature of 0. 10 to 50 parts by mass of a (meth) acrylic acid alkyl ester monomer (a-2) unit having a temperature of -100 ° C, and another monomer (a-3) copolymerizable with the above-mentioned (a-1) and (a-2). Unit (however, (a-3) is excluding (a-1) and (a-2) above) 45 to 89.9 parts by mass and an acrylic copolymer having a weight average molecular weight of 800,000 to 2,000,000. Is a polymer,
The other monomer (a-3) is a (meth) acrylic acid alkyl ester monomer having a homopolymer glass transition temperature of less than 0 ° C.,
The acrylic copolymer (B) is 0.01 to 5 parts by mass in the fluorine-containing monomer (b-1) unit or the silicon-containing monomer (b-2) unit in 100 parts by mass of the acrylic copolymer (B). And a (meth) acrylic acid alkyl ester monomer unit (b-3) having a glass transition temperature of less than 0 ° C. of 95 to 99.99 parts by mass, the acrylic polymer having a weight average molecular weight of 5,000 to 200,000. copolymer der is,
A pressure-sensitive adhesive characterized in that the ratio of the acrylic polymer (A) to the acrylic polymer (B) is (A) / (B) = 95/5 to 50/50 in terms of mass ratio . The pressure-sensitive adhesive according to claim 1, wherein the silicon-containing monomer (b-2) is a silicon-containing monomer having a structure represented by the following formula [1].

(In the formula, n is an integer representing a repeating unit, and 1 ≦ n ≦ 150.) The crosslinking agent (C) is an adhesive according to claim 1 or 2, wherein the an isocyanate compound. A substrate, the pressure-sensitive adhesive sheet comprising a claim 1-3 pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive according to any one. Polarizing plate and a polarizing plate adhesive sheet comprising a claim 1-3 pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive according to any one. And the glass plate, according to claim 1 to 3 and one pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive according liquid crystal cell member made and an optical member.