JP2012188620A - Adhesive composition and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition that can obtain an adhesive, an adhesive layer, an adhesive sheet and the like, which are excellent in coating stability, high in transparency, and excellent in long-term weatherability and adhesive properties.SOLUTION: The adhesive composition contains a graft-modified (meth)acryl polymer obtained by graft-polymerizing a monomer component, wherein a (meth)acryl polymer contains as the monomer component, at least a hindered amine monomer and/or a benzotriazole monomer.

Description

  The present invention is a pressure-sensitive adhesive containing a graft-modified (meth) acrylic polymer obtained by graft polymerization of a monomer having at least an ultraviolet absorption function and / or a radical scavenging function to a (meth) acrylic polymer as a main chain. The present invention relates to an agent composition and an adhesive sheet.

  Conventionally, attempts have been made to improve the weather resistance of a pressure-sensitive adhesive composition to which a light stabilizer such as an ultraviolet absorber or a radical scavenger is added together with a pressure-sensitive adhesive polymer (see Patent Documents 1 to 3).

  However, since the light stabilizer is usually a low molecular weight compound, satisfactory compatibility with the adhesive polymer cannot be obtained, and the light stabilizer becomes bleed-out when used as an adhesive sheet or the like. The loss or contamination of the light stabilizer component is a problem.

  Therefore, attempts have been made to use a light stabilizer as a monomer and a copolymer component of an adhesive polymer (Patent Documents 4 to 7).

  However, in this case, when a hindered amine monomer or a monomer having an ultraviolet absorbing function is copolymerized with the monomer constituting the adhesive polymer as a light stabilizer, the amino group, amide group, hydroxyl group, etc. of the light stabilizer as the monomer component Due to the chemical structure, undesired reactions, hydrogen bonds occur, excessive gelation and viscosity increase occur, causing problems in the coating time when producing adhesive sheets, etc. There is a limit to the amount of compounding agent.

Patent 4406152 JP 2002-30264 A JP 2009-227851 A JP-A-6-299132 JP 2000-123621 A JP-A-2005-187762 JP 2007-138117 A

  Therefore, the present invention provides a pressure-sensitive adhesive composition that has excellent coating stability, high transparency, long-term weather resistance and pressure-sensitive adhesive properties, a pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet, and the like. The purpose is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have found the following pressure-sensitive adhesive composition and have completed the present invention.

  That is, the pressure-sensitive adhesive composition of the present invention contains at least a hindered amine monomer and / or a benzotriazole monomer as a monomer component in a (meth) acrylic polymer, and is graft-modified by graft polymerization of the monomer component ( It contains a (meth) acrylic polymer. The (meth) acrylic polymer means an acrylic polymer and / or a methacrylic polymer. The same applies to the monomer.

  In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer is preferably obtained by polymerizing 0.1 to 10% by weight of a hydroxyl group-containing monomer as a monomer unit.

In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer has a general formula CH ₂ ═C (R ₁ ) COOR ₂ (wherein R ₁ is hydrogen or a methyl group, and R ₂ is the number of carbon atoms). It is preferably obtained by polymerizing a (meth) acrylic monomer represented by 1 to 14 alkyl groups).

  The pressure-sensitive adhesive composition of the present invention further contains a crosslinking agent, and the crosslinking agent is at least one selected from the group consisting of an organic peroxide crosslinking agent, an isocyanate crosslinking agent, and an epoxy crosslinking agent. Preferably it is a seed.

  Moreover, it is preferable that the adhesive sheet of this invention has an adhesive layer formed from the said adhesive composition in the at least single side | surface of a support body.

  The pressure-sensitive adhesive composition of the present invention comprises, as a monomer component, at least a monomer having an ultraviolet absorption function and / or a radical scavenging function, and graft polymerization of the monomer component to a (meth) acrylic polymer as a main chain. By including a graft-modified (meth) acrylic polymer, an adhesive, an adhesive layer, an adhesive sheet, etc. using the adhesive composition (adhesive film, adhesive tape, double-sided adhesive tape) High transparency, long-term weather resistance and adhesive properties, and protection of materials exposed to ultraviolet rays, such as glass protection, plastic protection, and metal plate protection, and long-term heat resistance are required. It can be used for a wide range of applications such as applications and is useful.

  The pressure-sensitive adhesive composition of the present invention comprises a graft modification (meta-chain) formed by graft polymerization (side chain formation) of at least a hindered amine monomer and / or a benzotriazole monomer on a (meth) acrylic polymer (main chain). ) Acrylic polymer is contained. The (meth) acrylic polymer in the present invention means to include a homopolymer or a copolymer (including a random copolymer or a block copolymer), and the copolymer includes an alkyl acrylate copolymer and / or an alkyl methacrylate copolymer. In addition, the alkyl group refers to a group having a linear or branched alkyl group, and excludes those having an aromatic ring or the like in the structure.

<Preparation of (meth) acrylic polymer (main chain)>
The pressure-sensitive adhesive composition of the present invention contains a graft-modified (meth) acrylic polymer, and the graft-modified (meth) acrylic polymer has a (meth) acrylic polymer as a main chain.

The (meth) as a monomer unit constituting the acrylic polymer (main chain) is not particularly limited, for example, the general formula _{CH 2 = C (R 1)} COOR 2 ( provided that, _{R 1} is hydrogen or a methyl radical, R ₂ is an alkyl group having 1 to 14 carbon atoms) and is preferably obtained by polymerizing a (meth) acrylic monomer.

Examples of the monomer represented by the general formula CH ₂ ═C (R ₁ ) COOR ₂ include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and s-butyl (meth) acrylate. , T-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, isoamyl (meth) acrylate, 2- Ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n- Dodecyl (Meth) acrylate, isomyristyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, and the like. It is preferable to use (meth) acrylate, 2-ethylhexyl (meth) acrylate, or the like. These monomers can be used alone or in combination.

In the present invention, the monomer represented by the general formula CH ₂ ═C (R ₁ ) COOR ₂ is preferably 50% by weight or more, and preferably 60 to 99% by weight with respect to the total monomer components of the (meth) acrylic polymer. Is more preferable, and 70 to 98% by weight is still more preferable. When the amount of the monomer is less than 50% by weight, the tackiness (adhesion) becomes poor, which is not preferable.

  The (meth) acrylic polymer of the present invention is preferably formed by polymerizing a hydroxyl group-containing monomer as a monomer unit. By using the hydroxyl group-containing monomer, when an organic peroxide is used as a cross-linking agent, one having excellent heat stability is obtained and useful. In addition, when a hydroxyl group-containing acrylic monomer is present in the (meth) acrylic polymer corresponding to the main chain, the position where hydrogen abstraction occurs during graft polymerization, or the graft polymer corresponding to the side chain, This has a favorable influence on the compatibility with the homopolymer obtained from the cyclic ether group-containing monomer produced in the above, and imparts better heat resistance.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth). Hydroxyalkyl (meth) acrylates such as acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate; hydroxyethyl (meth) acrylamide, and others (4-hydroxy Methylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, N-hydroxy (meth) acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydride Carboxybutyl ether, and diethylene glycol monovinyl ether. These monomers can be used alone or in combination.

  The hydroxyl group-containing monomer is preferably 0.1 to 10% by weight, more preferably 0.2 to 7% by weight, more preferably 0.5 to 5%, based on the total amount of monomer components forming the (meth) acrylic polymer. More preferred is weight percent. When the content of the hydroxyl group-containing monomer exceeds 10% by weight, gelation tends to occur when the (meth) acrylic polymer is polymerized. On the other hand, when the content is less than 0.1% by weight, the addition effect is difficult to obtain. It is not preferable.

  In the (meth) acrylic polymer of the present invention, a carboxyl group-containing monomer can be used as a monomer unit, and examples thereof include acrylic acid, methacrylic acid, itaconic acid, maleic acid and the like. Moreover, these anhydrides can be used. Of these, acrylic acid and methacrylic acid are particularly preferably used. These monomers can be used alone or in combination.

  In the (meth) acrylic polymer, the ratio of the carboxyl group-containing monomer is preferably 0.1 to 20% by weight, more preferably 0.2 to 10% by weight, and 0.5 to 7% by weight as a monomer unit. Is more preferable. If the content of the carboxyl group-containing monomer exceeds 20% by weight, the adhesion (adhesion) property may be lowered, the viscosity may be increased, and there is a risk of using it for productivity. On the other hand, less than 0.1% by weight If it is, there is a risk of foaming when the pressure-sensitive adhesive or the like is produced, or peeling off when it is applied, which is not preferable.

  As other copolymerizable monomers, vinyl compounds such as vinyl acetate and vinyl ether, and nitrogen-containing monomers such as amino group-containing monomers, amide group-containing monomers, and imide gas-containing monomers can be used as necessary. . These monomers can be used alone or in combination.

  Examples of the amide group-containing monomer include (meth) acrylamide, diethylacrylamide, N-vinylpyrrolidone, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, and N-methylol (meth) acrylamide. N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide and the like.

  Examples of the amino group-containing monomers include (dimethylaminoethyl methacrylate, t-butylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) ) Acrylate and the like.

  Examples of the imide group-containing monomer include N-cyclohexylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-hexylmaleimide, N-phenylmaleimide, and the like.

  Other nitrogen-containing monomers include (meth) acrylonitrile, N-vinyl-2-pyrrolidone, N- (meth) acryloylmorpholine and the like.

  In the (meth) acrylic polymer, the ratio of the nitrogen-containing monomer is preferably 0.1 to 20% by weight, more preferably 0.5 to 15% by weight, and still more preferably 2 to 10% by weight, as a monomer unit. . When the content of the nitrogen-containing monomer exceeds 20% by weight, the adhesion (adhesion) property is inferior. On the other hand, when the content is less than 0.1% by weight, peeling tends to occur under high humidity, which is not preferable.

  The weight average molecular weight of the (meth) acrylic polymer of the present invention is preferably 300,000 or more, more preferably 400,000 to 3,000,000, still more preferably 500,000 to 2,000,000. When the weight average molecular weight is less than 300,000, the durability of the pressure-sensitive adhesive layer becomes poor, or the cohesive force of the pressure-sensitive adhesive layer becomes small and adhesive residue tends to occur. On the other hand, if the weight average molecular weight is too large, the bonding property and the adhesive (adhesive) force are lowered, so that the workability is deteriorated. Furthermore, the pressure-sensitive adhesive composition may become too viscous in a solution system, and coating may be difficult. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

  The production of such a (meth) acrylic polymer can be appropriately selected from known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations. Further, the (meth) acrylic polymer obtained may be either a homopolymer or a copolymer (such as a random copolymer or a block copolymer).

  In solution polymerization, for example, ethyl acetate, toluene or the like is used as a polymerization solvent. As a specific example of solution polymerization, the reaction is performed under an inert gas stream such as nitrogen, and a polymerization initiator is added, and the reaction is usually performed at about 50 to 70 ° C. under reaction conditions of about 5 to 30 hours.

  The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited and can be appropriately selected and used. In addition, the weight average molecular weight of the said (meth) acrylic-type polymer can be controlled by the usage-amount of a polymerization initiator and a chain transfer agent, and reaction conditions, The usage-amount is suitably adjusted according to these kinds.

  Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [2- (5-methyl- 2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (N, N′-dimethyleneisobutylamidine), 2, Azo initiators such as 2'-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (VA-057, manufactured by Wako Pure Chemical Industries, Ltd.), persulfates such as potassium persulfate and ammonium persulfate Salt, di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butyl Ruperoxydicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3 , 3-tetramethylbutylperoxy-2-ethylhexanoate, di (4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexylperoxy) ) Peroxides such as cyclohexane, t-butyl hydroperoxide, hydrogen peroxide, peroxides and sodium bisulfite, peroxides and sodium ascorbate Redox initiators combined with The present invention is not limited.

  The polymerization initiator may be used alone or as a mixture of two or more, but the total content is 100% by weight of the total amount of monomers constituting the (meth) acrylic polymer. The amount is preferably about 0.005 to 1 part by weight, and more preferably about 0.02 to 0.5 part by weight.

  In order to produce the (meth) acrylic polymer having the weight average molecular weight using, for example, 2,2′-azobisisobutyronitrile as the polymerization initiator, the amount of the polymerization initiator used is: The amount is preferably about 0.06 to 0.3 parts by weight, more preferably about 0.08 to 0.2 parts by weight, based on 100 parts by weight of the total amount of monomer components.

  Examples of the chain transfer agent include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. The chain transfer agent may be used alone or in combination of two or more, but the total content is 0.1 parts by weight with respect to 100 parts by weight of the total amount of monomer components. Less than or equal to

  Examples of the emulsifier used in emulsion polymerization include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, ammonium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, and polyoxy Nonionic emulsifiers such as ethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, and polyoxyethylene-polyoxypropylene block polymer are listed. These emulsifiers may be used alone or in combination of two or more.

  Further, as the emulsifier, a reactive emulsifier into which a radical polymerizable functional group such as a propenyl group or an allyl ether group is introduced may be used. Specifically, as the reactive emulsifier, for example, Aqualon HS-10 HS-20, KH-10, BC-05, BC-10, BC-20 (all of which are manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adeka Soap SE10N (manufactured by Adeka), and the like. Reactive emulsifiers are preferable because they are incorporated into the polymer chain after polymerization and thus have improved water resistance. The amount of the emulsifier used is more preferably 0.3 to 5 parts by weight and 0.5 to 1 part by weight from the viewpoint of polymerization stability and mechanical stability with respect to 100 parts by weight of the total amount of monomer components.

<Preparation of side chain>
The pressure-sensitive adhesive composition of the present invention includes, as a monomer component, at least a hindered amine monomer having a radical scavenging function and / or a benzotriazole monomer having an ultraviolet absorption function in the (meth) acrylic polymer. It contains a graft-modified (meth) acrylic polymer obtained by graft polymerization.

  The hindered amine monomer is not particularly limited as long as it is a polymerizable monomer component (monomer unit) having a radical scavenging function. For example, a hindered amine monomer having the following structural formula can be used. These hindered amine monomers may be used alone or in combination of two or more.

（化学式１は、アデカ社製、アデカスタブＬＡ８７。）

(Chemical Formula 1 is Adeka Stab LA87 manufactured by Adeka Company.)

（化学式２は、アデカ社製、アデカスタブＬＡ８２。）

(Chemical Formula 2 is Adeka Sab LA82 manufactured by Adeka Corporation.)

  Further, the benzotriazole-based monomer is not particularly limited as long as it is a polymerizable monomer component (monomer unit) having an ultraviolet absorption function, but for example, a benzotriazole-based monomer having the following structural formula may be used. it can. In addition, these benzotriazoles may be used independently and may use 2 or more types together.

（化学式３のＲ_１は、水素または炭素数１〜８のアルキル基、Ｒ_２は、炭素数１〜６のアルキル基、Ｒ_３は、水素又はメチル基を示す。）

(R _{1 in} Chemical Formula 3 represents hydrogen or an alkyl group having 1 to 8 carbon atoms, R ₂ represents an alkyl group having 1 to 6 carbon atoms, and R ₃ represents hydrogen or a methyl group.)

（化学式４は、大塚化学社製、ＲＵＶＡ−９３。）

(Chemical formula 4 is RUVA-93 manufactured by Otsuka Chemical Co., Ltd.)

  The blending amount of the hindered amine monomer and / or the benzotriazole monomer is preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer (main chain). Part by weight is more preferable, and 1 to 8 parts by weight is still more preferable. When the blending amount of the monomer is less than 0.5 parts by weight, the weather resistance is not sufficiently exhibited. On the other hand, when it exceeds 20 parts by weight, problems may occur in transparency such as coating property and pressure-sensitive adhesive. Yes, not preferred.

Other copolymerizable monomers that can be used in addition to the hindered amine monomers and benzotriazole monomers that constitute the side chain are not particularly limited, but include, for example, the general formula CH ₂ = C (R ₁ ) COOR ₂ (however, R ₁ is hydrogen or a methyl group, and R ₂ is an alkyl group having 1 to 9 carbon atoms). Examples of the monomer represented by the general formula CH ₂ ═C (R ₁ ) COOR ₂ include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and s-butyl (meth) acrylate. , T-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, isoamyl (meth) acrylate, 2- Examples include ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate and the like. Examples of other copolymerizable monomers include alicyclic (meth) acrylates such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, and particularly n-butyl (meth) acrylate. Is preferably used. These monomers can be used alone or in combination.

In the present invention, the monomer represented by the general formula CH ₂ ═C (R ₁ ) COOR ₂ , alicyclic (meth) acrylate, and the like are 30 to 30% based on the total amount of the monomer components constituting the side chain. 80 weight% is preferable and 40 to 70 weight% is more preferable. When the amount of the monomer is less than 30% by weight, the tackiness (adhesion) becomes poor. On the other hand, when the amount exceeds 80% by weight, weather resistance cannot be improved, which is not preferable.

  As other copolymerizable monomers constituting the side chain, for example, a hydroxyl group-containing monomer can be mentioned.

  As the hydroxyl group-containing monomer, those used as the monomer component of the (meth) acrylic polymer can be used. Among these, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and the like are particularly preferable. By using the hydroxyl group-containing monomer, hindered amine monomers and benzotriazole monomers are easily grafted, which is effective.

  The hydroxyl group-containing monomer is preferably 3 to 20% by weight, more preferably 5 to 15% by weight, based on the total amount of monomer components constituting the side chain. When the content of the hydroxyl group-containing monomer exceeds 20% by weight, gelation tends to occur during graft polymerization. On the other hand, when the content is less than 3% by weight, the effect of addition becomes difficult to obtain, which is not preferable.

  The weight ratio (blending ratio) of the hindered amine monomer and / or benzotriazole monomer and other copolymerizable monomers (for example, a hydroxyl group-containing monomer) in the total amount of monomer components constituting the side chain is 99: 1 to 1:99 are preferred, and 98: 2 to 2:98 are more preferred. It is possible to change the weight ratio according to transparency, coatability, and adhesion (adhesion) characteristics. The reason is not clear by polymerizing other copolymerizable monomers together with the hindered amine monomer or benzotriazole monomer, but the formation of the polymer by the hindered amine monomer or benzotriazole monomer is inhibited. Therefore, the obtained graft-modified (meth) acrylic polymer is presumed to have improved transparency and coatability.

<Preparation of graft-modified (meth) acrylic polymer>
As a method for preparing a graft-modified (meth) acrylic polymer by graft-polymerizing monomer components such as the hindered amine monomer and benzotriazole monomer to the (meth) acrylic polymer (main chain), those skilled in the art The method is not particularly limited as long as it is a known method.For example, solution polymerization or emulsion polymerization can be used.In the case of solution polymerization, in particular, the solution of the (meth) acrylic polymer constituting the main chain (solid (100 parts by weight), a monomer for graft polymerization and a solvent for adjusting viscosity are added, and after nitrogen substitution, an azo polymerization such as 2,2′-azobisisobutyronitrile is used as a polymerization initiator. The initiator can be added by adding 0.02 to 5 parts by weight and heated at 50 to 80 ° C. for 4 to 15 hours. If the amount of the polymerization initiator is less than 0.02 parts by weight, it takes too much time to obtain a graft-modified (meth) acrylic polymer, and if it exceeds 5 parts by weight, the hindered amine monomer or benzoic acid is added. This is not preferable because a large amount of a polymer composed of a triazole-based monomer is produced and the ratio of non-grafting may increase.

  Moreover, the low molecular weight ultraviolet absorber normally used, a light stabilizer, an anti-aging agent, etc. can also be used as needed. In particular, it is preferable to use a benzotriazole ultraviolet absorber having an ultraviolet absorbing function or a hindered amine light stabilizer having a radical scavenging function.

  Specific examples of the ultraviolet absorber include those having a low molecular weight. Specific examples include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, and 2,2-dihydroxy. -4,4-dimethoxybenzophenone, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2-hydroxy-5-t-octylphenyl) benzotriazole, 2- (3,5-di -T-pentyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (2-hydroxy-5-t-octylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5 ' -Methylphenyl) -5-chlorobenzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzen) ) Phenyl] -2H- benzotriazole, and 2,2'-methylenebis [4- (1,1,3,3-tetrabutyl)-6-(2H-benzotriazole)] and the like. These ultraviolet absorbers may be used alone or in combination of two or more.

  Among the above ultraviolet absorbers, it is preferable to use a benzotriazole ultraviolet absorber. In the case of using a benzotriazole-based ultraviolet absorber, weather resistance can be further improved, so that it is possible to further prevent the adhesive (adhesive) force from being reduced by bleeding of the ultraviolet absorber. As a result, the adhesive sheet of the present invention can be sufficiently retained even if it is stored for a long time after being adhered to an adherend, and therefore peeled off due to a decrease in adhesive force. Can be sufficiently prevented. Moreover, the adhesive residue after long-term storage can be sufficiently prevented.

  Conventionally known light stabilizers can be used as the light stabilizer. For example, known light stabilizers such as hindered amine light stabilizers and benzoate light stabilizers can be appropriately used. Among these, in particular, when a hindered amine light stabilizer is used, weather resistance can be further improved, and therefore, it is possible to further prevent the adhesive force from being reduced by bleeding of the light stabilizer. And as a result, the adhesive sheet of the present invention can be sufficiently retained even when it is stored for a long time after being attached to an adherend, and therefore, by reducing the adhesive force, It is possible to sufficiently prevent peeling. Moreover, the adhesive residue after long-term storage can be sufficiently prevented.

  Examples of the hindered amine light stabilizer include a low molecular weight type, and specifically, bis (2,2,6,6-tetramethyl-1 (octyloxy) -4-biperidinyl) decanedioate. Reaction product of ester, 1,1-dimethylethyl hydroperoxide and octane (molecular weight: 737) (commercial product with 70% of this and 30% of polypropylene as a mixture: “TINUVIN 123S”), bis (1,2 , 2,6,6-pentamethyl-4-piperidinyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate (molecular weight: 685) (commercial product: "TINUVIN 144"), bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and methyl 1,2,2,6,6-pe Tamethyl-4-biperidinyl sebacate mixture (molecular weight: 509) (commercial product: “TINUVIN 765”), bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate (molecular weight: 481) (commercially available products: “TINUVIN 770”, “TINUVIN 770DF”, “TINUVIN 770FL”) and the like. All of the above commercial products are manufactured by Ciba Specialty Chemicals Co., Ltd. Further, commercial products such as Adeka Stub LA-52 and Adeka Stub LA-62 manufactured by Adeka Corporation are also exemplified, but the present invention is not limited thereto. Moreover, these light stabilizers may be used independently and may use 2 or more types together.

  The pressure-sensitive adhesive composition of the present invention may further contain a crosslinking agent, and the crosslinking agent is selected from the group consisting of organic peroxide crosslinking agents, isocyanate crosslinking agents, and epoxy crosslinking agents. It is preferable that it is at least one kind. The amount of the crosslinking agent is preferably 0.01 to 2 parts by weight based on 100 parts by weight of the graft-modified (meth) acrylic polymer. 1.5 parts by weight is more preferable, and 0.02 to 1.0 part by weight is still more preferable. If the amount is less than 0.01 part by weight, crosslinking may be insufficient and heat resistance may be inferior, and adhesive may remain at the time of peeling. On the other hand, if it exceeds 2 parts by weight, the amount of crosslinking may be excessive and adhesive (adhesive) force may be reduced. Yes, not preferred.

  The isocyanate-based crosslinking agent refers to a compound having two or more isocyanate groups in one molecule (including isocyanate-regenerating functional groups in which isocyanate groups are temporarily protected by blocking agents or quantification).

  Examples of the isocyanate-based crosslinking agent include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate. Furthermore, adducts of various polyols of these isocyanate compounds, diisocyanate isocyanurates, burettes, and the like can also be used. These isocyanate type crosslinking agents may be used individually by 1 type, and may mix and use 2 or more types. In addition, due to the ease of coloring during storage or when exposed to light (transparency is difficult to obtain), considerations such as reducing the amount of blending are required when using aromatic isocyanate crosslinking agents It is.

  More specifically, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate, 2,4-tolylene diisocyanate, Aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, polymethylene polyphenyl isocyanate, trimethylolpropane / tolylene diisocyanate trimer adduct (trade name Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.), tri Methylolpropane / hexamethylene diisocyanate trimer adduct (product name: Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd.), hexamethylene diiso Isocyanurate of anate (product name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.), polyether polyisocyanate, polyester polyisocyanate, and adducts of these with various polyols, isocyanurate bond, burette bond And polyisocyanates polyfunctionalized with allophanate bonds. Among these, it is preferable to use an aliphatic isocyanate because the reaction rate is high.

  The isocyanate-based crosslinking agent may be used alone or in combination of two or more, but the isocyanate-based crosslinking agent is used with respect to 100 parts by weight of the graft-modified (meth) acrylic polymer. Is preferably contained in an amount of 0.01 parts by weight or more, more preferably 0.02 to 2 parts by weight, and even more preferably 0.05 to 1.5 parts by weight. If it is in the said range, it will be excellent in heat resistance, and it will become a preferable aspect, without remaining adhesive at the time of peeling. Further, it can be appropriately contained in consideration of crosslinking stability, processability, handling properties, and the like.

  The organic peroxide-based crosslinking agent can be used as appropriate as long as it generates radical active species by heating to advance the crosslinking of the base polymer of the pressure-sensitive adhesive composition, but considering workability and stability. Thus, it is preferable to use a peroxide having a half-life temperature of 80 ° C. to 160 ° C. for 1 minute, and it is more preferable to use a peroxide having a temperature of 90 ° C. to 140 ° C. When the 1-minute half-life temperature is less than 80 ° C., the reaction proceeds during storage before coating and drying, the viscosity increases, and the coating itself cannot be performed, while when it exceeds 160 ° C. Since the temperature during the cross-linking reaction becomes high, side reactions occur, and there is a possibility that the cross-linking reaction proceeds in the state where a large amount of unreacted organic peroxide remains, such being undesirable.

  Examples of the organic peroxide crosslinking agent include di (2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature: 90.6 ° C.), di (4-t-butylcyclohexyl) peroxydicarbonate ( 1 minute half-life temperature: 92.1 ° C.), di-sec-butyl peroxydicarbonate (1 minute half-life temperature: 92.4 ° C.), t-butyl peroxyneodecanoate (1 minute half-life temperature: 103.5 ° C.), t-hexyl peroxypivalate (half-life temperature for 1 minute: 109.1 ° C.), t-butyl peroxypivalate (half-life temperature for 1 minute: 110.3 ° C.), dilauroyl peroxide (1 minute half-life temperature: 116.4 ° C), di-n-octanoyl peroxide (1 minute half-life temperature: 117.4 ° C), 1,1,3,3-tetramethylbutylper Xyl-2-ethylhexanoate (1 minute half-life temperature: 124.3 ° C), di (4-methylbenzoyl) peroxide (1 minute half-life temperature: 128.2 ° C), dibenzoyl peroxide (half-minute for 1 minute) Period temperature: 130.0 ° C.), t-butyl peroxyisobutyrate (1 minute half-life temperature: 136.1 ° C.), 1,1-di (t-hexylperoxy) cyclohexane (1 minute half-life temperature: 149.2 ° C.). Especially, since the crosslinking reaction efficiency is excellent, di (4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1 ° C.), dilauroyl peroxide (1 minute half-life temperature: 116. 4 ° C), dibenzoyl peroxide (1 minute half-life temperature: 130.0 ° C) and the like are preferably used.

  The half-life of the organic peroxide crosslinking agent is an index representing the decomposition rate of peroxide, and means the time until the remaining amount of peroxide is reduced to half. The decomposition temperature for obtaining a half-life at an arbitrary time and the half-life time at an arbitrary temperature are described in the manufacturer catalog, for example, “Organic peroxide catalog 9th edition by Nippon Oil & Fats Co., Ltd.” (May 2003) ".

  The organic peroxide crosslinking agent may be used alone, or may be used in combination of two or more, but with respect to 100 parts by weight of the graft-modified (meth) acrylic polymer, The organic peroxide is preferably contained in an amount of 0.02 to 2 parts by weight, more preferably 0.05 to 1 part by weight, and still more preferably 0.08 to 0.6 parts by weight. If it is less than 0.02 parts by weight, the crosslinking reaction may be inadequate and the durability may be inferior. On the other hand, if it exceeds 2 parts by weight, the crosslinking may be excessive and adhesion (adhesion) may be inferior. It is not preferable. Further, it can be appropriately contained in consideration of crosslinking stability, processability, handling properties, and the like.

  In addition, as a measuring method of the peroxide decomposition amount which remained after the reaction process, it can measure by HPLC (high performance liquid chromatography), for example.

  More specifically, for example, about 0.2 g of the pressure-sensitive adhesive composition after the reaction treatment is taken out, immersed in 10 ml of ethyl acetate, extracted by shaking at 25 ° C. and 120 rpm for 3 hours with a shaker, and then at room temperature. Leave for 3 days. Next, 10 ml of acetonitrile was added, shaken at 120 rpm at 25 ° C. for 30 minutes, and about 10 μl of the extract obtained by filtration through a membrane filter (0.45 μm) was injected into the HPLC for analysis. The amount of peroxide can be set.

  The epoxy-based crosslinking agent refers to a compound having two or more epoxy groups in one molecule, such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, terephthalic acid diglycidyl ester acrylate, spiroglycol diglycidyl ether, and the like. Can be given.

  The epoxy-based crosslinking agent may be used alone or as a mixture of two or more, but the epoxy-based crosslinking agent is used with respect to 100 parts by weight of the graft-modified (meth) acrylic polymer. It is preferable to contain 0.01-2 weight part, 0.02-1.5 weight part is more preferable, 0.02-1.0 weight part is still more preferable. If it is in the said range, it will be excellent in heat resistance, and it will become a preferable aspect, without remaining adhesive at the time of peeling. Further, it can be appropriately contained in consideration of crosslinking stability, processability, handling properties, and the like.

  In addition, a polyfunctional metal chelate or the like can be used as a crosslinking agent. The polyfunctional metal chelate is one in which a polyvalent metal and an organic compound are covalently bonded or coordinated. Examples of the polyvalent metal atom include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. Can be given. Examples of the atom in the organic compound that is covalently or coordinately bonded include an oxygen atom, and the organic compound includes an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, a ketone compound, and the like.

  In the present invention, it is also possible to add an oxazoline-based crosslinking agent or the like as a crosslinking agent. As the oxazoline-based crosslinking agent, those having an oxazoline group in the molecule can be used without particular limitation. The oxazoline group may be any of a 2-oxazoline group, a 3-oxazoline group, and a 4-oxazoline group. As the oxazoline-based cross-linking agent, a polymer obtained by copolymerizing an unsaturated monomer with an addition-polymerizable oxazoline is preferable, and a compound using 2-isopropenyl-2-oxazoline as the addition-polymerizable oxazoline is particularly preferable. As an example, trade name “Epocross WS-500” manufactured by Nippon Shokubai Co., Ltd. can be cited.

  The crosslinking agent (polyfunctional metal chelate, oxazoline crosslinking agent, etc.) is at least one selected from the group consisting of the organic peroxide crosslinking agent, isocyanate crosslinking agent, and epoxy crosslinking agent. At the same time, it can be used in consideration of the blending amount as long as the characteristics of the present invention are not impaired.

  Moreover, in manufacture of the said adhesive (layer), it is preferable to prepare so that the gel fraction of the bridge | crosslinked adhesive layer may be 20-95 weight%, and 40-90 weight% is more preferable. The gel fraction can be determined by appropriately considering the amount of the crosslinking agent and the conditions such as the crosslinking treatment temperature and time.

  Furthermore, when applying the pressure-sensitive adhesive composition or pressure-sensitive adhesive sheet of the present invention to a hydrophilic adherend such as glass, in order to increase the adhesion with the interface and increase the durability, A silane coupling agent can be used.

  Examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3,4 epoxycyclohexyl) ethyltri. Epoxy group-containing silane coupling agents such as methoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3- (Meth) such as dimethylbutylidene) propylamine, amino group-containing silane coupling agents such as N-phenyl-γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, etc. Acrylic group-containing silane Coupling agent, such as an isocyanate group-containing silane coupling agents such as 3-isocyanate propyl triethoxysilane and the like.

  The silane coupling agent may be used alone or as a mixture of two or more, but the total content is the total amount of monomers constituting the graft-modified (meth) acrylic polymer. It is preferable to contain 0.01-1 weight part with respect to 100 weight part, It is more preferable to contain 0.02-0.6 weight part, It is still more preferable to contain 0.05-0.3 weight part. If it is less than 0.01 part by weight, it is difficult to improve water resistance (durability). If it exceeds 1 part by weight, the adhesion (adhesion) force to the glass will increase and the removability will tend to be inferior. Yes, not preferred.

  Furthermore, the pressure-sensitive adhesive composition of the present invention may contain other known additives, such as powders such as colorants and pigments, dyes, surfactants, plasticizers, tackifiers, Add surface lubricant, leveling agent, softener, antioxidant, anti-aging agent, polymerization inhibitor, inorganic or organic filler, metal powder, particles, foil, etc. as appropriate depending on the application. Can do. In addition, when these additives use the said adhesive composition and form an adhesive layer, it is necessary to prepare a compounding quantity to such an extent that the elasticity modulus of the said adhesive layer is not changed remarkably.

  Examples of the solvent used in the present invention include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, methanol, ethanol, n-propanol, isopropanol, water and the like. . These solvents may be used independently and may mix 2 or more types.

<Preparation of adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention preferably has a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition on at least one surface of the support.

  The method for forming the pressure-sensitive adhesive layer is not particularly limited. For example, the pressure-sensitive adhesive composition (solution) is applied to a release-treated separator, and the polymerization solvent is dried and removed. A method in which a pressure-sensitive adhesive composition is bonded to a support after forming a layer, or a method in which the pressure-sensitive adhesive composition is applied onto a support, a polymerization solvent and the like are removed by drying, and a pressure-sensitive adhesive layer is formed on the support by crosslinking. It is produced by. Thereafter, an aging treatment may be performed for the purpose of adjusting the crosslinking reaction of the pressure-sensitive adhesive layer. In addition, one or more solvents (solvents) other than the polymerization solvent may be added as appropriate so that the pressure-sensitive adhesive composition can be uniformly applied.

  As the release-treated separator, a silicone release liner is preferably used. In the step of applying the pressure-sensitive adhesive composition of the present invention on such a liner and drying to form the pressure-sensitive adhesive layer, as a method of drying the pressure-sensitive adhesive, an appropriate method is appropriately employed depending on the purpose. obtain. Preferably, a method of heating and drying the coating film is used. The heat drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and particularly preferably 70 ° C to 170 ° C. By setting the heating temperature within the above range, a pressure-sensitive adhesive having excellent pressure-sensitive adhesive properties can be obtained.

  As the drying time, an appropriate time can be adopted as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

  Examples of the support include a polyolefin (polyethylene, polypropylene, ethylene-propylene copolymer, etc.) film, a polyester (polyethylene terephthalate, etc.) film, a vinyl chloride resin film, a vinyl acetate resin film, and a polyimide film. Plastic films such as resin films, polyamide resin films, fluororesin films, and other cellophanes; papers such as Japanese paper, kraft paper, glassine paper, fine paper, synthetic paper, top coat paper; various fibers Individual materials (natural fibers, semi-synthetic fibers or synthetic fibers, such as cotton fibers, sufu, manila hemp, pulp, rayon, acetate fibers, polyester fibers, polyvinyl alcohol fibers, polyamide fibers, polyolefin fibers, etc.) alone Or by blending etc. Fabrics such as woven fabrics and non-woven fabrics; rubber sheets made of natural rubber, butyl rubber, etc .; foam sheets made of foams such as foamed polyurethane and foamed polychloroprene rubber; metal foils such as aluminum foil and copper foil; Complex; etc. can be used. The plastic films may be a non-stretch type or a stretch type (uniaxial stretch type or biaxial stretch type).

  The support is optionally filled with a filler (inorganic filler, organic filler, etc.), anti-aging agent, antioxidant, ultraviolet absorber, light stabilizer, antistatic agent, lubricant, plasticizer, and coloring. Various additives such as agents (pigments, dyes, etc.) may be blended. The surface of the support (particularly the surface on which the pressure-sensitive adhesive layer is provided) may be subjected to known or conventional surface treatments such as corona discharge treatment, plasma treatment, and application of a primer. Such surface treatment can be, for example, a treatment for improving the support throwing property of the pressure-sensitive adhesive layer. Moreover, you may perform an easily bonding process on the surface of an adhesive layer.

  The thickness in particular of the said support body is not restrict | limited, For example, about 10 micrometers-about 500 micrometers are preferable, and about 10 micrometers-about 200 micrometers are more preferable.

  Various methods are used as a method of forming the pressure-sensitive adhesive layer. Specifically, for example, by roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

  The thickness of the pressure-sensitive adhesive layer is not particularly limited, and is preferably about 1 to 100 μm, more preferably about 2 to 50 μm, still more preferably about 2 to 40 μm, and particularly preferably about 5 to 35 μm.

  When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a sheet (separator) that has been subjected to a release treatment until practical use.

  Examples of the constituent material of the separator include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. Although an appropriate thin leaf body etc. can be mention | raise | lifted, a plastic film is used suitably from the point which is excellent in surface smoothness.

  The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as. In particular, when the surface of the separator is appropriately subjected to a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment, the peelability from the pressure-sensitive adhesive layer can be further improved.

  The pressure-sensitive adhesive sheet of the present invention is useful because it can be used for protecting members exposed to light (ultraviolet rays) such as glass protection, plastic protection, and metal plate protection, and for applications that require long-term heat resistance.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The room temperature conditions not specifically defined below are all 23 ° C. and 65% RH (1 hour or 1 week). Evaluation items in Examples and the like were measured as follows.

[Example 1]
(Preparation of (meth) acrylic polymer A1)
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a condenser, 67 parts by weight of n-butyl acrylate, 30 parts by weight of methyl acrylate, 3 parts by weight of 4-hydroxybutyl acrylate, 2 as a polymerization initiator , 2'-azobisisobutyronitrile (0.1 part by weight) was charged with 200 parts by weight of ethyl acetate and 30 parts by weight of toluene. After gently stirring, nitrogen gas was introduced and the atmosphere was replaced with nitrogen for 1 hour. The polymerization temperature was maintained at around 55 ° C. for 10 hours, and a (meth) acrylic polymer A1 solution corresponding to a main chain having a weight average molecular weight of 910,000 was prepared.

(Preparation of graft-modified (meth) acrylic polymer B1)
The (meth) acrylic polymer A1 solution (solid content: 100 parts by weight) is placed in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler, and a benzotriazole monomer (manufactured by Otsuka Chemical Co., Ltd.). , RUVA-93) 5 parts by weight, 1 part by weight of 4-hydroxybutyl acrylate, 0.1 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator, and nitrogen gas was introduced while gently stirring. After purging with nitrogen for 1 hour, the temperature of the liquid in the flask was kept at around 65 ° C., and a polymerization reaction was carried out for 2 hours and then at 70 ° C. for 4 hours to prepare a graft-modified (meth) acrylic polymer B1 solution.

(Preparation of adhesive sheet C1)
0.3 parts by weight of trimethylolpropane adduct of xylylene diisocyanate (D-110N, manufactured by Mitsui Chemicals) as a crosslinking agent for the graft-modified (meth) acrylic polymer B1 solution (solid content: 100 parts by weight) Were mixed to prepare an adhesive composition solution. Next, the pressure-sensitive adhesive composition solution is placed on one side of a 38 μm-thick polyethylene terephthalate (PET) film (Tetron HB3-50, manufactured by Teijin DuPont) so that the thickness of the pressure-sensitive adhesive layer after drying is 25 μm. It apply | coated and dried at 110 degreeC for 3 minute (s), the adhesive layer was formed, and the adhesive sheet C1 was produced.

[Example 2]
(Preparation of adhesive sheet C2)
With respect to the graft-modified (meth) acrylic polymer B1 solution obtained in Example 1 (solid content: 100 parts by weight), as a cross-linking agent, 0.3 part by weight of benzoyl peroxide and trimethylolpropane adduct of hexamethylene diisocyanate The body (Mitsui Chemicals make, D-160N) 0.07 weight part was mix | blended, and the adhesive composition solution was prepared. Next, the pressure-sensitive adhesive composition solution is placed on one side of a 38 μm-thick polyethylene terephthalate (PET) film (Tetron HB3-50, manufactured by Teijin DuPont) so that the thickness of the pressure-sensitive adhesive layer after drying is 25 μm. It apply | coated and dried for 3 minutes at 140 degreeC, the adhesive layer was formed, and the adhesive sheet C2 was produced.

[Example 3]
(Preparation of (meth) acrylic polymer A3)
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a condenser, 50 parts by weight of n-butyl acrylate, 47 parts by weight of isobutyl acrylate, 3 parts by weight of 4-hydroxybutyl acrylate, 2 as a polymerization initiator , 2'-azobisisobutyronitrile (0.1 part by weight) was charged with 200 parts by weight of ethyl acetate and 30 parts by weight of toluene. After gently stirring, nitrogen gas was introduced and the atmosphere was replaced with nitrogen for 1 hour. The polymerization temperature was kept at around 55 ° C. for 10 hours, and a (meth) acrylic polymer A3 solution corresponding to a main chain having a weight average molecular weight of 980,000 was prepared.

(Preparation of graft-modified (meth) acrylic polymer B3)
The (meth) acrylic polymer A3 solution (solid content: 100 parts by weight) is put into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler, and a hindered amine monomer (Adeka Co., Ltd., Adacas stub). LA-82) 5 parts by weight, 1 part by weight of 4-hydroxybutyl acrylate and 0.1 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator were charged, and nitrogen gas was introduced while gently stirring. After replacing with nitrogen for 1 hour, the temperature of the liquid in the flask was kept at around 65 ° C., and a polymerization reaction was carried out for 3 hours and then at 70 ° C. for 3 hours to prepare a graft-modified (meth) acrylic polymer B3 solution.

(Preparation of adhesive sheet C3)
To the graft-modified (meth) acrylic polymer B3 solution (solid content: 100 parts by weight), 0.03 part by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., Tetrad C) is blended and adhered. An agent composition solution was prepared. Next, the pressure-sensitive adhesive composition solution is placed on one side of a 38 μm-thick polyethylene terephthalate (PET) film (Tetron HB3-50, manufactured by Teijin DuPont) so that the thickness of the pressure-sensitive adhesive layer after drying is 25 μm. It apply | coated and dried at 110 degreeC for 3 minute (s), the adhesive layer was formed, and the adhesive sheet C3 was produced.

[Example 4]
(Preparation of graft-modified (meth) acrylic polymer B4)
The (meth) acrylic polymer A3 solution (solid content: 100 parts by weight) is put into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler, and a benzotriazole monomer (manufactured by Otsuka Chemical Co., Ltd.). , RUVA-93) 3 parts by weight, 1 part by weight of a hindered amine-based monomer (manufactured by Adeka, Adakas Tab LA-87), 1 part by weight of 4-hydroxybutyl acrylate, 10 parts by weight of butyl acrylate, 2,2′- as a polymerization initiator After charging 0.1 parts by weight of azobisisobutyronitrile, introducing nitrogen gas with gentle stirring and replacing with nitrogen for 1 hour, keeping the liquid temperature in the flask at around 65 ° C. for 3 hours, then 70 ° C. The polymerization reaction was carried out for 4 hours to prepare a graft-modified (meth) acrylic polymer B4 solution.

(Preparation of adhesive sheet C4)
0.7 parts by weight of a trimethylolpropane adduct of hexamethylene diisocyanate (D-160N, manufactured by Mitsui Chemicals) as a crosslinking agent for the graft-modified (meth) acrylic polymer B4 solution (solid content: 100 parts by weight) Were mixed to prepare an adhesive composition solution. Next, the pressure-sensitive adhesive composition solution is placed on one side of a 38 μm-thick polyethylene terephthalate (PET) film (Tetron HB3-50, manufactured by Teijin DuPont) so that the thickness of the pressure-sensitive adhesive layer after drying is 25 μm. It apply | coated and dried at 110 degreeC for 3 minute (s), the adhesive layer was formed, and the adhesive sheet C4 was produced.

[Comparative Example 1]
A pressure-sensitive adhesive sheet of Comparative Example 1 was obtained in the same manner as in Example 1 except that no benzotriazole monomer was added.

[Comparative Example 2]
For the (meth) acrylic polymer A1 solution obtained in Example 1 (solid content: 100 parts by weight), 5 parts by weight of a benzotriazole monomer (manufactured by Otsuka Chemical Co., Ltd., RUVA-93), and xylylene diene as a crosslinking agent. 0.3 parts by weight of an isocyanate trimethylolpropane adduct (D-110N, manufactured by Mitsui Chemicals, Inc.) was blended to prepare an adhesive composition solution. Next, the pressure-sensitive adhesive composition solution is placed on one side of a 38 μm-thick polyethylene terephthalate (PET) film (Tetron HB3-50, manufactured by Teijin DuPont) so that the thickness of the pressure-sensitive adhesive layer after drying is 25 μm. It apply | coated and dried at 110 degreeC for 3 minute (s), the adhesive layer was formed, and the adhesive sheet was produced.

[Comparative Example 3]
For the (meth) acrylic polymer A1 solution (solid content 100 parts by weight) obtained in Example 1, 5 parts by weight of a high molecular weight type hindered amine (manufactured by BASF, Uvinul 5050H), as a crosslinking agent, xylylene diisocyanate An adhesive composition solution was prepared by blending 0.3 parts by weight of a trimethylolpropane adduct (D-110N, manufactured by Mitsui Chemicals). Next, the pressure-sensitive adhesive composition solution is placed on one side of a 38 μm-thick polyethylene terephthalate (PET) film (Tetron HB3-50, manufactured by Teijin DuPont) so that the thickness of the pressure-sensitive adhesive layer after drying is 25 μm. It apply | coated and dried at 110 degreeC for 3 minute (s), the adhesive layer was formed, and the adhesive sheet was produced.

[Comparative Example 4]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a condenser, 67 parts by weight of n-butyl acrylate, 30 parts by weight of methyl methacrylate, 3 parts by weight of 4-hydroxybutyl acrylate, a benzotriazole monomer ( RUKA-93) manufactured by Otsuka Chemical Co., Ltd. 5 parts by weight, 0.1 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator was added together with 200 parts by weight of ethyl acetate and 30 parts by weight of toluene. After introducing nitrogen gas with stirring and substituting with nitrogen for 1 hour, the temperature of the liquid in the flask was kept at around 55 ° C., and the polymerization reaction was started. As a result, it was not possible to obtain a coatable (meth) acrylic polymer.

[Comparative Example 5]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a condenser, 67 parts by weight of n-butyl acrylate, 30 parts by weight of methyl methacrylate, 3 parts by weight of 4-hydroxybutyl acrylate, hindered amine monomer (ADEKA 5 parts by weight, manufactured by Adacasta LA-82), 0.1 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator was added together with 200 parts by weight of ethyl acetate and 30 parts by weight of toluene. After introducing nitrogen gas with stirring and replacing with nitrogen for 1 hour, the temperature of the liquid in the flask was kept at around 55 ° C. to start the polymerization reaction. Due to the progress, a coatable (meth) acrylic polymer could not be obtained.

  The following evaluation was performed about the adhesive sheet obtained by the said Example and comparative example. The evaluation results are shown in Table 1.

<Measurement of weight average molecular weight>
The weight average molecular weight of the obtained (meth) acrylic polymer was measured by GPC (gel permeation chromatography). The sample used was a filtrate obtained by dissolving the sample in tetrahydrofuran to make a 0.1 wt% solution, which was allowed to stand overnight, and then filtered through a 0.45 μm membrane filter.
・ Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
Column: manufactured by Tosoh Corporation, G7000H _XL + GMH _XL + GMH _XL
・ Column size: 7.8mmφ × 30cm each 90cm in total
・ Eluent: Tetrahydrofuran (concentration 0.1% by weight)
・ Flow rate: 0.8ml / min
・ Detector: Differential refractometer (RI)
-Column temperature: 40 ° C
・ Injection volume: 100 μl
・ Eluent: Tetrahydrofuran ・ Detector: Differential refractometer ・ Standard sample: Polystyrene

<Transparency>
The state of the adhesive sheet was visually observed and evaluated according to the following criteria.
○: Transparent ×: Cloudiness

<Peeling force>
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into a width of 20 mm and a length of about 50 mm, and a 2 kg roll was reciprocated on a glass plate (manufactured by Matsunami) having a thickness of 1.5 mm. Paste, and then put into a xenon weather meter (Xe25, manufactured by Suga Test Instruments Co., Ltd.) whose irradiance is set to about 50 (w / m ² ) for 700 hours, and after sticking the adhesive sheet to the adherend glass, The peeling force (N / 20 mm) was measured at a peeling angle of 180 ° and a peeling speed of 300 mm / min under the conditions of 23 ± 2 ° C. and humidity of about 50% RH. In addition, as said peeling force, it is preferable that it is 0.5-25N / 20mm, It is more preferable that it is 2-20N / 20mm, It is still more preferable that it is 5-15N / 20mm. When it is within the above range, it is preferable that it is not peeled off during use and can be easily peeled off after use when used for protecting glass or metal plates.

<Contamination>
The adherend surface after the peel strength evaluation test was visually observed and evaluated according to the following criteria.
○: No adhesive residue on the adherend glass surface ×: Adhesive residue on the adherend glass surface

From the results in Table 1, the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive composition of the present invention has at least a monomer component having an ultraviolet absorption function and / or a radical scavenging function in the (meth) acrylic polymer as the main chain. By containing a graft-modified (meth) acrylic polymer formed by graft polymerization, the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive composition is excellent in coating stability, has high transparency, and has long-term weather resistance (peeling power). It was confirmed that it had excellent adhesive properties (no adhesive residue) and could be used in a wide range of applications.

Claims (5)

To (meth) acrylic polymer,
A pressure-sensitive adhesive composition comprising at least a hindered amine monomer and / or a benzotriazole monomer as a monomer component, and a graft-modified (meth) acrylic polymer obtained by graft polymerization of the monomer component.   The pressure-sensitive adhesive composition according to claim 1, wherein the (meth) acrylic polymer is obtained by polymerizing 0.1 to 10% by weight of a hydroxyl group-containing monomer as a monomer unit. The (meth) acrylic polymer, as a monomer unit of the general formula _{CH 2 = C (R 1)} COOR 2 ( provided that, _{R 1} is hydrogen or a methyl group, _{R 2} is an alkyl group having 1 to 14 carbon atoms) The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive composition is obtained by polymerizing a (meth) acrylic monomer represented by the formula: Furthermore, it contains a crosslinking agent,
The said crosslinking agent is at least 1 sort (s) selected from the group which consists of an organic peroxide type crosslinking agent, an isocyanate type crosslinking agent, and an epoxy-type crosslinking agent in any one of Claims 1-3 characterized by the above-mentioned. The pressure-sensitive adhesive composition described. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to claim 1 on at least one side of a support.