JP2016180019A - Adhesive composition and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition and an adhesive sheet having excellent adhesive force and adhesiveness to a cured surface with respect to a low polarity adherend, and having high transparency.SOLUTION: The adhesive composition comprises an acrylic polymer (A), a polyfunctional isocyanate compound (B) and alcohol (C), characterized in that: the acrylic polymer (A) is an acrylic polymer having a hydroxyl group and/or a carboxyl group; the alcohol (C) is a mono-alcohol having a molecular weight of 140 or more and 500 or less, one or more alicyclic hydrocarbon groups and one secondary hydroxyl group; and the adhesive composition contains the alcohol (C) by 0.5 to 15 parts by mass with respect to 100 parts by mass of the acrylic polymer (A).SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet using the same. More specifically, the present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet that have excellent adhesion and curved surface adhesion to a low-polar adherend and have high transparency.

  Acrylic adhesives have been used in various industrial fields because of their excellent adhesive properties such as adhesive strength and cohesive strength, and heat resistance, weather resistance and other aging resistance. There is a tendency to demand high performance that is not trapped by.

  Among them, polyolefin materials typified by polyethylene and polypropylene (hereinafter sometimes abbreviated as PP) have been used in an increasing trend mainly in the automotive field in recent years. There is a difficult nature. In particular, the curved surface adhesion to the low-polarity adherend is susceptible to stress due to deformation, so that there is a problem that peeling at the end and floating of the recess are likely to occur.

  As a method for improving the curved surface adhesion to these low-polar adherends, conventionally, a method of adding a rosin resin as a tackifier (tackifier) is known. Although the curved surface adhesion to the polar adherend is improved, the performance is not sufficient, and there are further problems such as a decrease in transparency due to coloring and a decrease in holding power at high temperatures.

  On the other hand, as a method for increasing the adhesion to a low polarity adherend, Patent Documents 1 and 2 disclose an adhesive composition composed of a polyester polyol, a monofunctional alcohol, and an isocyanate compound. Further, even when the described monofunctional alcohol is used for a general pressure-sensitive adhesive, curved surface adhesion to a low-polar adherend is not sufficient.

JP 2004-115681 A JP 2006-037037 A

  The problem to be solved by the present invention is to provide a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet that are excellent in adhesive strength and curved surface adhesion to a low-polar adherend and have high transparency.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems.
That is, the present invention is a pressure-sensitive adhesive composition comprising an acrylic polymer (A), a polyfunctional isocyanate compound (B) and an alcohol (C), wherein the acrylic polymer (A) is a hydroxyl group and / or a carboxyl group. An acrylic polymer having a group, the alcohol (C) is a monoalcohol having a molecular weight of 140 or more and 500 or less, one or more alicyclic hydrocarbon groups, and one secondary hydroxyl group, It is related with the adhesive composition characterized by including 0.5-15 mass parts of alcohol (C) with respect to 100 mass parts of polymers (A).

  In the pressure-sensitive adhesive composition according to the invention, the alcohol (C) is a monoalcohol having a molecular weight of 140 or more and 500 or less, two or more alicyclic hydrocarbon groups, and one secondary hydroxyl group. About.

  In the pressure-sensitive adhesive composition, the alcohol (C) is a monoalcohol having a molecular weight of 140 or more and 500 or less, having one or more condensed alicyclic hydrocarbon groups, and one secondary hydroxyl group. Related to things.

  Moreover, this invention relates to the adhesive sheet by which the adhesive layer formed from the said adhesive composition is laminated | stacked on the at least one surface of a sheet-like base material.

  According to the present invention, it is possible to provide a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet that are excellent in adhesive strength and curved surface adhesion to a low-polar adherend and have high transparency.

  Embodiments of the present invention will be described in detail below, but the following description is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents as long as the gist thereof is not exceeded.

<Adhesive composition>
The present invention is a pressure-sensitive adhesive composition containing an acrylic polymer (A), a polyfunctional isocyanate compound (B) and an alcohol (C). In addition, the adhesive physical property in this specification means various physical properties, such as adhesive force, curved surface adhesiveness, and holding power.

<Alcohol (C)>
Alcohol (C) refers to a monoalcohol having a molecular weight of 140 or more and 500 or less, one or more alicyclic hydrocarbon groups, and one secondary hydroxyl group. The alicyclic hydrocarbon group may be a saturated alicyclic hydrocarbon group or an unsaturated alicyclic hydrocarbon group, and further, a condensed alicyclic in which alicyclic hydrocarbon groups are condensed with each other. It may be a hydrocarbon group. As long as the hydroxyl group is secondary, the bonding position is not particularly limited, and examples thereof include a mode in which the hydroxyl group is directly bonded to the alicyclic hydrocarbon group and a mode in which the hydroxyl group is bonded to the side chain of the alicyclic hydrocarbon group. .

  The alcohol (C) is not particularly limited to the following examples. However, the compounds represented by the following formulas [1] to [8], isocamphylcyclohexanol, α-ambrinol, alicyclic hydrocarbon groups And cycloalkanol, alkylcycloalkanol, dialkylcycloalkanol, trialkylcycloalkanol, tetraalkylcycloalkanol and the like having 7 or more carbon atoms.

In the above formulas [1] to [8], R _{a1 to} R _a5 , R _{b1 to} R _b9 , R _{c1 to} R _c7 , R _{d1 to} R _d10 , R _{e1 to} R _e7 , R _{f1 to} R _f7 , R _g1 to R _g5 and R _{h1 to} R _h7 are each independently a hydrogen atom, alkyl group, alkenyl group, alkynyl group, formyl group, alkylcarbonyl group, carboxyalkylcarbonyl group, formatealkylcarbonyl group, acetoxyalkylcarbonyl group, Alkylcarbonylalkyl group, alkylcarboxy group, carboxyalkylcarboxy group, formate alkylcarboxy group, acetoxyalkylcarboxy group, alkylcarboxyalkyl group, alkoxy group, carboxyalkoxy group, formatealkoxy group, acetoxyalkoxy group, or phenyl group It is group represented by either.

  Examples of the alkyl group include a methyl group and an ethyl group. Examples of the alkenyl group include a vinyl group and an allyl group. Examples of the alkynyl group include an ethynyl group and a prop-2-yn-1-yl group. Note that “formate” means “—O—CH═O”.

  The molecular weight of the alcohol (C) is 140 or more and 500 or less, and more preferably 150 or more and 400 or less. When the molecular weight is 140 or more, sufficient cohesive force can be obtained, and curved surface adhesion to a low-polar adherend can be improved. When the molecular weight is 500 or less, it is possible to suppress a decrease in adhesive force due to excessive cohesive force and whitening of the adhesive sheet.

  The number of alicyclic hydrocarbon groups in the alcohol (C) is not particularly limited as long as it is 1 or more, but 2 or more is more preferable. By having one or more alicyclic hydrocarbon groups in one molecule, sufficient cohesive force can be obtained, and curved surface adhesion to a low-polar adherend can be improved.

  Moreover, the alicyclic hydrocarbon group of alcohol (C) is not particularly limited, but is preferably a saturated alicyclic hydrocarbon group. When the alicyclic hydrocarbon group is saturated, it is possible to suppress a decrease in transparency associated with coloring over time.

  Furthermore, the alicyclic hydrocarbon group of the alcohol (C) is not particularly limited, but is preferably a condensed alicyclic hydrocarbon group in which alicyclic hydrocarbon groups are condensed with each other. When one or more alicyclic hydrocarbon groups have a condensed ring structure, sufficient cohesive force can be obtained, and curved surface adhesion to a low-polar adherend can be improved.

  The bonding position of the hydroxyl group of the alcohol (C) is not particularly limited, but a mode in which it is directly bonded to the alicyclic hydrocarbon group is preferable. When the hydroxyl group is directly bonded to the alicyclic hydrocarbon group, the amount incorporated in the crosslinking reaction can be easily adjusted from the viewpoint of the reactivity of the hydroxyl group.

R _{a1 to} R _a5 , R _{b1 to} R _b9 , R _{c1 to} R _c7 , R _{d1 to} R _d10 , R _{e1 to} R _e7 , R _{f1 to} R which are substituents in the formulas [1] to [8]. _f7, R _g1 to R _g5, and as R _h1 to R _h7 is a hydrogen atom, an alkyl group, an alkenyl group, and / or, is preferably any one of the alkynyl group. When the substituent is any one of a hydrogen atom, an alkyl group, an alkenyl group, and / or an alkynyl group, the adhesion to the low-polar adherend can be improved, and the acrylic polymer (A) and When the adhesive sheet is made into a pressure-sensitive adhesive sheet, high transparency can be obtained.

  As a boiling point of alcohol (C), 170 degreeC or more is preferable and 200 degreeC or more is more preferable. When the boiling point is 170 ° C. or higher, the volatilization of alcohol when the pressure-sensitive adhesive composition is dried can be suppressed, and the adjustment of the amount incorporated in the crosslinking reaction is facilitated.

Specific examples of the alcohol (C) described above include 4-butylcyclohexanol, 4-pentylcyclohexanol, 4-hexylcyclohexanol, cyclodecanol, cyclododecanol, cyclopentadecanol, 4-isopropylcyclohexanol, 3,5,5-trimethylcyclohexanol, menthol, 4-tertiarybutyl-cyclohexanol, 2,6-bis-tertiarybutyl-4-methylcyclohexanol, 2-phenyl-1-cyclohexanol, isopulegol, dihydrocarbe Secondary monoalcohol having one alicyclic hydrocarbon group in one molecule such as all, 4-hydroxycyclohexanecarboxylic acid, 4- (methoxycarbonyl) cyclohexane-1-ol, 1-cyclohexyl-1-pentanol
Fat in one molecule such as dicyclohexylmethanol, decitol, 2-cyclohexylcyclohexanol, 4-cyclohexylcyclohexanol, 4- (4-propylcyclohexyl) cyclohexanol, 4- (4-pentylcyclohexyl) cyclohexanol, α-ambrinol, etc. A secondary monoalcohol having two or more cyclic hydrocarbon groups,
2-norbornanol, borneol, 1,3,3-trimethyl-2-norbornanol, hydroxydicyclopentadiene, 2,6,6-trimethylbicyclo [3.1.1] heptan-3-ol, isocamphylcyclohexanol, etc. A secondary monoalcohol having a condensed alicyclic hydrocarbon group in which two alicyclic hydrocarbon groups of
Examples include secondary monoalcohols having a condensed alicyclic hydrocarbon group in which three alicyclic hydrocarbon groups such as 2-adamantanol are condensed.

  These alcohols (C) may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the alcohol (C) in the pressure-sensitive adhesive composition preferably includes 0.5 to 15 parts by mass of the alcohol (C), more preferably 100 parts by mass of the acrylic polymer (A). It is 0.8-10 mass parts, More preferably, it is 1.0-5.0 mass parts. When the content of the alcohol (C) is in the above range, good curved surface adhesion to a low polarity adherend can be obtained.

<Acrylic polymer (A)>
The acrylic polymer (A) of the present invention means a polymer of a monomer having an ethylenically unsaturated bond containing at least a (meth) acrylic acid ester monomer, and has a hydroxyl group and / or a carboxyl group. Here, “(meth) acrylic acid ester monomer” refers to a generic term of “acrylic acid ester monomer” and “methacrylic acid ester monomer”.

  Examples of the (meth) acrylic acid ester monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl ( Examples include meth) acrylate, cyclohexyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, butyl acrylate and 2-ethylhexyl acrylate are particularly preferable because they can easily obtain appropriate adhesive properties and can easily produce an acrylic polymer having a relatively large weight average molecular weight.

  The acrylic polymer (A) has a hydroxyl group and / or a carboxyl group that can react with the isocyanato group of the polyfunctional isocyanate compound (B) described later. The method for introducing a hydroxyl group and / or carboxyl group is not particularly limited. For example, in addition to a (meth) acrylic acid ester monomer, a monomer having an ethylenically unsaturated bond having a hydroxyl group and / or an ethylenic group having a carboxyl group. An acrylic polymer (A) having a hydroxyl group and / or a carboxyl group can be obtained by copolymerizing a monomer having an ethylenically unsaturated bond having a reactive functional group such as a monomer having an unsaturated bond.

  Examples of the monomer having an ethylenically unsaturated bond having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth). Examples thereof include hydroxyalkyl (meth) acrylates such as acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate.

  Examples of the monomer having an ethylenically unsaturated bond having a carboxyl group include (meth) acrylic acid, 2-carboxyethyl (meth) acrylate, crotonic acid, maleic acid, itaconic acid, fumaric acid, citraconic acid, mesaconic acid and the like. Carboxylic acid having an unsaturated bond of

  In addition to the above, a monomer having an ethylenically unsaturated bond having a functional group other than a hydroxyl group and / or a carboxyl group can be used as long as the physical properties of the adhesive are not impaired. Examples of such a monomer include a monomer having an ethylenically unsaturated bond having an epoxy group, a monomer having an ethylenically unsaturated bond having an amino group, and a monomer having an ethylenically unsaturated bond having an isocyanato group. be able to.

  Examples of the monomer having an ethylenically unsaturated bond having an epoxy group include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 6-methyl-3,4- An epoxy cyclohexyl methyl (meth) acrylate etc. are mentioned.

  Examples of the monomer having an ethylenically unsaturated bond having an amino group include monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, and monoethylaminopropyl (meth) acrylate. Monoalkylamino ester (meth) acrylate, etc. are mentioned.

  As a monomer which has an ethylenically unsaturated bond which has an isocyanato group, 2-isocyanatoethyl (meth) acrylate etc. are mentioned, for example.

  Moreover, as a monomer which has an ethylenically unsaturated bond other than the above, (meth) acrylamides, such as (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, vinyl acetate, crotonic acid, for example Vinyl, styrene, acrylonitrile and the like can also be used.

  One of the above-mentioned monomers having an ethylenically unsaturated bond may be used alone, or two or more thereof may be used in combination.

  The proportion of the monomer having an ethylenically unsaturated bond having a hydroxyl group and / or a carboxyl group is preferably in the range of 0.1 to 20% by mass in 100% by mass of all monomers constituting the acrylic polymer (A). 0.5 to 10% by mass is more preferable. When the content is 0.1% by mass or more, sufficient crosslinking is formed, and high cohesive force and good adhesive properties can be obtained. When the content is 20% by mass or less, an increase in the glass transition temperature can be suppressed, and good adhesive properties can be obtained.

  The weight average molecular weight of the acrylic polymer (A) is a standard polystyrene conversion value by gel permeation chromatography (GPC), preferably 300,000 to 1,500,000, and more preferably 400,000 to 1,000,000. When the weight average molecular weight is 300,000 or more, sufficient cohesive force and durability can be obtained. When the weight average molecular weight is 1,500,000 or less, an increase in viscosity can be suppressed and good coating suitability can be obtained.

  The glass transition temperature of the acrylic polymer (A) is preferably -60 to 0 ° C, more preferably -50 to -10 ° C. When the glass transition temperature is −60 ° C. or higher, sufficient cohesive force can be obtained, and the adhesive strength and durability can be enhanced. When the glass transition temperature is 0 ° C. or lower, sufficient wettability can be obtained and the adhesive strength can be increased.

  There is no restriction | limiting in particular as a manufacturing method of an acrylic polymer (A), For example, it can obtain by polymerizing the monomer which has said ethylenically unsaturated bond by well-known radical polymerization reaction. Although the reaction may be carried out in the absence of a solvent, it is preferable to use a solvent from the viewpoint of synthesis stability and handling. From the viewpoint of molecular weight control, it is preferable to use a radical polymerization initiator (hereinafter sometimes abbreviated as “polymerization initiator”). In addition, you may use well-known additives, such as a chain transfer agent.

  Examples of the solvent include acetone, methyl acetate, ethyl acetate, propyl acetate, toluene, xylene, anisole, methyl ethyl ketone, cyclohexanone, isopropanol, and the like. These solvents are not particularly limited, but one type may be used alone, or two or more types may be used in combination.

Examples of the polymerization initiator include benzoyl peroxide, tert-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxydicarbonate. Tert-butylperoxy-2-ethylhexanoate, tert-butylperoxyneodecanoate, tert-butylperoxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, Organic peroxides such as diacetyl peroxide,
2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2,2′-azobis (2, 4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate), 4,4′-azobis ( Azo compounds such as 4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis [2- (2-imidazolin-2-yl) propane] Can be mentioned.
These polymerization initiators may be used individually by 1 type, and may be used in combination of 2 or more type.

  Furthermore, a chain transfer agent may be used for the purpose of adjusting the molecular weight of the acrylic polymer (A). Examples of the chain transfer agent include alkyl mercaptans such as octyl mercaptan, nonyl mercaptan, decyl mercaptan, dodecyl mercaptan, thioglycolic acid esters such as octyl thioglycolate, nonyl thioglycolate, and 2-ethylhexyl thioglycolate, Examples include 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene, α-pinene, β-pinene, and the like. In particular, polymers obtained from thioglycolic acid esters, 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene, α-pinene, β-pinene, etc. This is preferable in terms of low odor. It is preferable that the usage-amount of a chain transfer agent is 3 mass% or less in 100 mass% of all the monomers which comprise an acrylic polymer (A).

<Polyfunctional isocyanate compound (B)>
The polyfunctional isocyanate compound (B) forms a network-like crosslinked structure by crosslinking reaction with the hydroxyl group and / or carboxyl group in the acrylic polymer (A) and the hydroxyl group in the alcohol (C), and an adhesive. It is used for the purpose of imparting high elasticity for use as a base material and adhesion to a substrate. The polyfunctional isocyanate compound (B) is not particularly limited as long as it can form a crosslinked structure with the hydroxyl group and / or carboxyl group of the acrylic polymer (A) and the hydroxyl group in the alcohol (C). Examples thereof include aliphatic isocyanates, aliphatic isocyanates, alicyclic isocyanates, and bifunctional or higher functional isocyanate compounds such as burettes, nurates, and adducts.

  Examples of the aromatic isocyanate include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6 -Tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 ', 4 ″ -triphenylmethane triisocyanate, ω, ω′-diisocyanate-1,3-dimethylbenzene (also known as XDI, m-xylylene diisocyanate), ω, ω′-diisocyanate-1,4-dimethylbenzene : P-xylylene diisocyanate), omega, omega .'- diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethyl xylylene diisocyanate.

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

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

  Examples of the burette include hexamethylene diisocyanate burette (product name “Sumijour N-75”, manufactured by Sumika Bayer Urethane Co., Ltd .; product name “Duranate 24A-90CX”, manufactured by Asahi Kasei Chemicals).

  Examples of nurate bodies include hexamethylene diisocyanate nurate (product name “Sumijour N-3300”, manufactured by Sumika Bayer Urethane Co., Ltd.), isophorone diisocyanate nurate (product name “Desmodur Z-4370”, Sumika). Bayer Urethane Co., Ltd.), tolylene diisocyanate nurate (product name “Coronate 2030”, manufactured by Nippon Polyurethane Co., Ltd.) and the like.

  Examples of the adduct include a bifunctional or higher functional isocyanate compound obtained by reacting the aromatic isocyanate, aliphatic isocyanate, and / or alicyclic isocyanate with a bifunctional or lower molecular active hydrogen-containing compound. For example, trimethylolpropane hexamethylene diisocyanate adduct (product name “Takenate D-160N”, manufactured by Mitsui Chemicals), trimethylolpropane tolylene diisocyanate adduct (product name “Coronate L”, manufactured by Nippon Polyurethane Co., Ltd.) Product name “Takenate D-102” (manufactured by Mitsui Chemicals), trimethylolpropane xylylene diisocyanate adduct (product name “Takenate D-110N”, manufactured by Mitsui Chemicals), trimethylolpropane isophorone diisocyanate adduct ( Product "Takenate D-140N", and the like is manufactured by Mitsui Chemicals, Inc.), and the like.

Examples of the bifunctional or higher functional low molecular active hydrogen-containing compound include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, and 3,3 ′. -Dimethylol heptane, 2-methyl-1,8-octanediol, 3,3'-dimethylol heptane, 2-butyl-2-ethyl-1,3-propanediol, polyoxyethylene glycol (added mole number of 10 or less ), Polyoxypropylene glycol (added mole number of 10 or less), 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neo Pentyl glycol, butyl ethyl pentane diol, 2-ethyl-1,3- Hexanediol, cyclohexanediol, cyclohexanedimethanol, tricyclodecanedimethanol, cyclopentadiene engine methanol, aliphatic or alicyclic diols and dimer diol;
1,3-bis (2-hydroxyethoxy) benzene, 1,2-bis (2-hydroxyethoxy) benzene, 1,4-bis (2-hydroxyethoxy) benzene, 4,4′-methylenediphenol, 4, 4 ′-(2-norbornylidene) diphenol, 4,4′-dihydroxybiphenol, o-, m-, and p-dihydroxybenzene, 4,4′-isopropylidenephenol, or bisphenols such as bisphenol A and bisphenol F Aromatic diols such as bisphenols obtained by adding alkylene oxide such as ethylene oxide and propylene oxide to
1,1,1-trimethylolpropane, 1,1,1-trimethylolbutane, 1,1,1-trimethylolpentane, 1,1,1-trimethylolhexane, 1,1,1-trimethylolheptane, 1,1,1-trimethyloloctane, 1,1,1-trimethylol nonane, 1,1,1-trimethyloldecane, 1,1,1-trimethylolundecane, 1,1,1-trimethyloldodecane, 1,1,1-trimethylol tridecane, 1,1,1-trimethylol tetradecane, 1,1,1-trimethylol pentadecane, 1,1,1-trimethylol hexadecane, 1,1,1-trimethylol hepta Decane, 1,1,1-trimethylol octadecane, 1,1,1-trimethylol nanodecane, 1,1,1-trimethylol-sec Butane, 1,1,1-trimethylol-tert-pentane, 1,1,1-trimethylol-tert-nonane, 1,1,1-trimethylol-tert-tridecane, 1,1,1-trimethylol- tert-heptadecane, 1,1,1-trimethylol-2-methyl-hexane, 1,1,1-trimethylol-3-methyl-hexane, 1,1,1-trimethylol-2-ethyl-hexane, Trimethylol branched alkanes such as 1,1,1-trimethylol-3-ethyl-hexane, 1,1,1-trimethylolisoheptadecane;
Trimethylol butene, trimethylol heptene, trimethylol pentene, trimethylol hexene, trimethylol heptene, trimethylol octene, trimethylol decene, trimethylol dodecene, trimethylol tridecene, trimethylol pentadecene, trimethylol hexadecene, tri Trifunctional polyols such as metrolheptadecene, trimethyloloctadecene, 1,2,6-butanetriol, 1,2,4-butanetriol, glycerin;
Tetrafunctional or higher functional polyols such as pentaerythritol, dipentaerythritol, sorbitol, xylitol;
Examples thereof include aliphatic polyamines such as triethylenetetramine, diethylenetriamine, and triaminopropane. These bifunctional or more low molecular active hydrogen-containing compounds may be used singly or in combination of two or more.

  These polyfunctional isocyanate compounds (B) may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among the polyfunctional isocyanate compounds (B), in view of adhesion, heat resistance, compatibility, etc., it is preferable to use a trifunctional isocyanate compound, a trimethylolpropane adduct of tolylene diisocyanate, a trimethylolpropane of hexamethylene diisocyanate. More preferred are adduct, trimethylolpropane adduct of isophorone diisocyanate, trimethylolpropane adduct of xylylene diisocyanate, isocyanurate of tolylene diisocyanate, isocyanurate of hexamethylene diisocyanate, isocyanurate of isophorone diisocyanate. The trimethylolpropane adduct of isocyanate and the trimethylolpropane adduct of xylylene diisocyanate are Preferred.

  The amount of the polyfunctional isocyanate compound (B) used in the present invention is the isocyanate group in the polyfunctional isocyanate compound (B), the hydroxyl group and / or carboxyl group in the acrylic polymer (A), and the alcohol (C). The ratio of the total number of moles of hydroxyl groups (isocyanato group / (hydroxyl group and / or carboxyl group)) is preferably 0.05 to 1.5, more preferably 0.1 to 0.8. . If it is 0.05 or more, sufficient crosslinking is formed, and high cohesive force and good constant load peelability and heat resistance can be obtained. If it is 1.5 or less, the degree of crosslinking is excessively high. It is possible to suppress the cohesive force and to obtain good adhesion to the adherend.

  The pressure-sensitive adhesive composition of the present invention further includes known tackifiers, catalysts, antioxidants, ultraviolet absorbers, hydrolysis inhibitors, antifungal agents, thickeners, plasticizers, fillers, antifoaming agents and the like. These additives can be blended as necessary.

  Tackifiers include terpene resins, aliphatic petroleum resins, aromatic petroleum resins, coumarone-indene resins, phenol resins, terpene-phenol resins, rosin resins (rosins, polymerized rosins, hydrogenated rosins, and their Known products such as esterified products with polyhydric alcohols such as glycerin and pentaerythritol, resin acid dimers, etc.) and acrylic resins can be used. As a usage-amount of a tackifier, it is preferable that 0-60 mass parts of tackifiers are included with respect to 100 mass parts of acrylic polymers (A), More preferably, it is 10-30 mass parts. Sufficient adhesion can be obtained when the content of the tackifier is in the above range.

  The acrylic resin that can be used as a tackifier is not particularly limited as long as it is other than the acrylic polymer (A), but from the viewpoint of compatibility with the acrylic polymer (A), a (meth) acrylic acid ester monomer is used. An acrylic resin having a weight average molecular weight of 50,000 or less, obtained by polymerizing a monomer having an ethylenically unsaturated bond is preferred.

The catalyst is used for the purpose of adjusting the curing time of the pressure-sensitive adhesive composition, but is not particularly limited, and examples thereof include known tertiary amines and organometallic compounds.
Examples of the tertiary amine include triethylamine, tributylamine, dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, N-cyclohexylmorpholine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetramethylbutanediamine or N, N, N ′, N′-tetramethylhexanediamine, pentamethyldiethylenetriamine, bis (dimethylaminopropyl) urea, 1,4, -dimethylpiperazine, 1,2-dimethylimidazole, 1-azobicyclo [3.3.0] octane, 1,4-diazobicyclo [2.2.2] octane, alkanolamine compound, triethanolamine, triisopropanolamine, N-methyldiethanolamine N-ethyldiethanolamine , Dimethylethanolamine and the like.
Examples of the organometallic compound include tin (II) acetate, tin (II) octoate, tin (II) ethylhexanoate, tin (II) carboxylic acid tin (II) salt, dibutyltin diacetate, dibutyltin, etc. Dialkyltin (IV) salts of organic carboxylic acids such as dilaurate, dibutyltin malate, dioctyltin diacetate, dioctyltin laurate, titanium tetraisopropoxide, titanium tetranormal butoxide, titanium butoxide dimer, titanium tetra-2-ethylhexoxy Alkoxide organic titanium compounds such as titanium, titanium diisopropoxybis (acetylacetonate), titanium tetraacetylacetonate, titanium di-2-ethylhexoxybis (2-ethyl-3-hydroxyhexoxide), titanium diiso Propoxybis Ethylacetoacetate) solvent system chelated organotitanium compounds such as titanium diisopropoxy bis (triethanolaminate), titanium lactate ammonium salt, titanium lactate, an aqueous chelated organotitanium compounds such as titanium lactate and the like.

  When a catalyst is used in the pressure-sensitive adhesive composition of the present invention, a known catalytic action inhibitor such as acetylacetone can be used for the purpose of improving the pot life of the pressure-sensitive adhesive composition.

<Adhesive sheet>
Using the pressure-sensitive adhesive composition of the present invention, a laminate in which a pressure-sensitive adhesive layer is laminated on a substrate (hereinafter referred to as “pressure-sensitive adhesive sheet”) can be obtained.

  As the base material of the pressure-sensitive adhesive sheet, a known base material for pressure-sensitive adhesive sheets can be used, for example, a film-like base material such as paper, metal film, cellophane, various plastic films, and those film-like base materials. Examples thereof include a peelable film substrate whose surface is peeled with a silicone compound or a fluorine compound. The base material of these pressure-sensitive adhesive sheets may be a single layer or a multilayer formed by laminating a plurality of base materials.

  Examples of the various plastic films include polyhydroxyethene films, triacetyl cellulose films, films of polyolefin resins such as polypropylene, polyethylene, polycycloolefin, and ethylene-vinyl acetate copolymers, and polyesters such as polyethene terephthalate and polybutene terephthalate. Resin film, polycarbonate resin film, polynorbornene resin film, polyarylate resin film, propenoic acid resin film, polyphenylene sulfide resin film, polyethenylbenzene resin film, vinyl resin film Polyamide resin film, polyimide resin film, oxirane resin film, and the like.

  As a laminated structure of the pressure-sensitive adhesive sheet, for example, a single-sided pressure-sensitive adhesive sheet such as a film-like base material / pressure-sensitive adhesive layer / releasable film base, or a peelable film base / pressure-sensitive adhesive layer / releasable film base or peeling Double-sided pressure-sensitive adhesive sheet such as adhesive film substrate / adhesive layer / film-like substrate / adhesive layer / releasable film substrate, and one or both sides of the peelable film substrate are peeled off during use. The agent layer is affixed to the adherend.

  The pressure-sensitive adhesive sheet is prepared by applying a pressure-sensitive adhesive composition to a peelable film substrate by a known lamination method. When the pressure-sensitive adhesive composition contains a volatile liquid such as an organic solvent or water, the volatile liquid is removed by a method such as heating. On the other hand, when the pressure-sensitive adhesive composition does not contain a volatile liquid, the pressure-sensitive adhesive composition in a molten state is applied to the substrate, and then cooled and solidified to form a pressure-sensitive adhesive layer on the substrate. be able to.

  The film thickness of the pressure-sensitive adhesive layer is preferably in the range of 1 μm to 120 μm after drying, and more preferably in the range of 1 μm to 50 μm.

  The method for applying the adhesive composition of the present invention to a peelable film substrate or the like is not particularly limited, and may be a Meyer bar, applicator, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, It can coat using various coating machines, such as a knife coater, a reverse coater, and a spin coater.

  When drying the coated adhesive composition, there is no restriction | limiting in particular in a drying method, The method by a hot air, infrared rays, pressure reduction, etc. are mentioned. As drying conditions, although depending on the crosslinked form of the pressure-sensitive adhesive composition, the film thickness, and the type of volatile liquid contained, a method using hot air of about 60 to 180 ° C. is usually preferable.

  Since the pressure-sensitive adhesive sheet obtained by the above method exhibits good adhesive strength to each adherend, it can be used for label seals, double-sided tapes, cast tapes, masking tapes, foam tapes and the like.

  Specific examples of the present invention will be described below together with comparative examples, but the present invention is not limited to the following examples. In the following examples and comparative examples, “part” and “%” represent “part by mass” and “% by mass”, respectively, unless otherwise specified.

<Measurement of non-volatile content>
About 1 g of the sample solution was weighed in a metal container, dried in an oven at 150 ° C. for 20 minutes, the residue was weighed, and the remaining rate was calculated to obtain a nonvolatile content (nonvolatile content concentration).

<Measurement of molecular weight (Mn, Mw)>
The number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured by gel permeation chromatography (GPC). As a measuring instrument, GPC "HPC-8020" manufactured by Tosoh Corporation was used. As the column, a Super HM-M and a Super HM-L manufactured by Tosoh Corporation were connected in series. Measurement was performed at 40 ° C. using tetrahydrofuran (THF) as a solvent (eluent). The number average molecular weight (Mn) and the weight average molecular weight (Mw) were both converted values using polystyrene as a standard.

<Measurement of glass transition temperature (Tg)>
The glass transition temperature (Tg) was determined by measurement with a differential scanning calorimeter (DSC). An “SSC5200 disk station” (manufactured by Seiko Instruments Inc.) was connected to a robot DSC (differential scanning calorimeter, “RDC220” manufactured by Seiko Instruments Inc.) and used for measurement. The acrylic polymer solution obtained in each synthesis example was coated and dried on a polyester peelable film substrate, and the dried one was used as a measurement sample. 10 mg of the measurement sample was set in the differential scanning calorimeter, held at a temperature of 100 ° C. for 5 minutes, and then rapidly cooled to −120 ° C. using liquid nitrogen. Thereafter, the temperature was increased at a rate of temperature increase of 10 ° C./min, and the temperature was increased to 200 ° C. to perform DSC measurement. The glass transition temperature (Tg) (unit: ° C.) was determined from the obtained DSC chart.

<Measurement of hydroxyl value (OHV)>
A sample (1 g) was accurately weighed in a stoppered Erlenmeyer flask, and 100 ml of pyridine was added and dissolved. Further, 5 ml of an acetylating agent (a solution in which 25 g of acetic anhydride was dissolved in pyridine to make a volume of 100 ml) was accurately added and stirred for 1 hour, followed by titration with a 0.5 N alcoholic potassium hydroxide solution. The hydroxyl value (unit: mgKOH / g) was determined by the following formula. The hydroxyl value was the value of the dried sample.
Hydroxyl value = [{(ba) × F × 28.05} / S] / (Non-volatile content concentration / 100) + D
S: Sample collection amount (g)
a: Consumption of 0.5N alcoholic potassium hydroxide solution (ml)
b: Consumption of the 0.5N alcoholic potassium hydroxide solution in the blank experiment (ml)
F: Factor of 0.5N-alcoholic potassium hydroxide solution
D: Acid value (mgKOH / g)

<Measurement of isocyanato number (NCO number)>
A sample 10 g was accurately weighed in a stoppered Erlenmeyer flask, 25 ml of orthodichlorobenzene, di-n-butylamine / o-dichlorobenzene (mass ratio: di-n-butylamine / o-dichlorobenzene = 1 / 24.8). 10 ml of the mixed solution was added and dissolved. To this solution, 80 g of methanol and bromophenol blue reagent were added as indicators and titrated with a 0.1N alcoholic hydrochloric acid solution. The end point was when the solution was yellowish green and held for 30 seconds or more. The NCO value (unit:%) was determined by the following formula.
NCO value = [0.42 × (BC) × F] / W
W: Amount of sample collected (g)
B: Consumption of 0.1N alcoholic hydrochloric acid solution required for sample titration (ml)
C: Consumption of 0.1N alcoholic hydrochloric acid solution required for titration of blank test (ml)
F: Factor of 0.1N alcoholic hydrochloric acid solution

  The materials and abbreviations used in Examples and Comparative Examples are described below.

<Monomer having an ethylenically unsaturated bond>
nBA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate Vac: vinyl acetate 2HEA: 2-hydroxyethyl acrylate AA: acrylic acid IBXA: isobornyl acrylate

<Chain transfer agent>
1-methyl-4-isopropylidene-1-cyclohexene thioglycolate-2-ethylhexyl

<Polymerization initiator>
tert-Butyl-2-ethylperoxyhexanoate (Product name "Perbutyl O", manufactured by NOF Corporation)
Benzoyl peroxide (product name “Nyper BW”, manufactured by NOF Corporation)
2,2′-azobisisobutyronitrile (product name “V-60”, manufactured by Wako Pure Chemical Industries, Ltd.)

<Isocyanate compound (B)>
XDI-TMP: trimethylolpropane adduct of m-xylylene diisocyanate, number of isocyanato groups = 3, NCO value = 7.7%, nonvolatile content = 50%
TDI-TMP: Trimethylolpropane adduct of tolylene diisocyanate, number of isocyanato groups = 3, NCO value = 6.5%, nonvolatile content = 37.5%

<Alcohol (C)>
Menthol (molecular weight 156.3, boiling point 210 ° C.)
4-cyclohexylcyclohexanol (molecular weight 182.3)
Borneol (molecular weight 154.3)
2-adamantanol (molecular weight 152.2)

<Alcohol having an alicyclic hydrocarbon group other than (C)>
Cyclohexanol (molecular weight 100.16, boiling point 161 ° C)
2-norbornanol (molecular weight 112.17, boiling point 177 ° C.)
Rubixanthin (molecular weight 552.85)
(−)-Mirtanol (molecular weight 154.3)
4,4'-bicyclohexanol (molecular weight 198.3)

<Synthesis of acrylic polymer (A)>
(Synthesis Example 1)
A polymerization reaction apparatus equipped with a reaction tank, a stirrer, a thermometer, a reflux condenser, a dropping tank, and a nitrogen introduction tube was prepared. A monomer mixture consisting of the monomer, solvent and polymerization initiator shown below was charged into the reaction tank and dropping tank at the following ratios, and the air in the reaction tank was replaced with nitrogen gas, and then stirred under a nitrogen atmosphere with stirring. The temperature was raised to ° C. Next, the monomer mixture in the dropping tank was dropped over 1 hour. After completion of dropping, the mixture was reacted for 3 hours with stirring. Further, a polymerization initiator was added later and reacted for 3 hours. After the reaction, the following dilution solvent was added and cooled to room temperature to obtain a solution containing the acrylic polymer (A). The resulting acrylic polymer had a weight average molecular weight (Mw) of 470,000, a glass transition temperature of −33 ° C., and a nonvolatile content of 50%.

[Reaction tank]
<Monomer having an ethylenically unsaturated bond>
((Meth) acrylic acid ester monomer)
nBA 38.0 parts MMA 5.0 parts (monomer having an ethylenically unsaturated bond having a hydroxyl group)
0.35 parts of 2HEA (monomer having an ethylenically unsaturated bond other than the above)
Vac 4.0 parts <Solvent>
Ethyl acetate 33.8 parts Toluene 0.9 parts <Polymerization initiator>
tert-Butyl-2-ethylperoxyhexanoate 0.071 part [drip tank]
<Monomer having an ethylenically unsaturated bond>
(Acrylic acid ester monomer)
nBA 52.1 parts (monomer having an ethylenically unsaturated bond having a hydroxyl group)
0.35 parts of 2HEA <solvent>
Ethyl acetate 39.7 parts Toluene 1.1 parts <Polymerization initiator>
tert-Butyl-2-ethylperoxyhexanoate 0.071 parts [post-addition]
<Polymerization initiator>
tert-Butyl-2-ethylperoxyhexanoate 0.12 parts [diluted solvent]
Ethyl acetate 21.5 parts Toluene 2.9 parts

(Synthesis Example 2)
A solution containing the acrylic polymer (A) was obtained in the same manner as in Synthesis Example 1 except that the types and blending amounts of the monomer, solvent, and polymerization initiator were changed as follows. The resulting acrylic polymer had a weight average molecular weight (Mw) of 520,000, a glass transition temperature of −43 ° C., and a nonvolatile content of 45%.

[Reaction tank]
<Monomer having an ethylenically unsaturated bond>
((Meth) acrylic acid ester monomer)
nBA 25.5 parts 2EHA 6.6 parts (monomer having an ethylenically unsaturated bond having a hydroxyl group)
2HEA 0.03 part (monomer having an ethylenically unsaturated bond having a carboxyl group)
AA 1.0 part <solvent>
Ethyl acetate 37.3 parts <Chain transfer agent>
1-methyl-4-isopropylidene-1-cyclohexene 0.025 part <polymerization initiator>
Benzoyl peroxide 0.088 parts [drip tank]
<Monomer having an ethylenically unsaturated bond>
(Acrylic acid ester monomer)
nBA 51.0 parts 2EHA 13.3 parts (monomer having an ethylenically unsaturated bond having a hydroxyl group)
2HEA 0.07 part (monomer having an ethylenically unsaturated bond having a carboxyl group)
AA 2.0 parts <solvent>
Ethyl acetate 44.4 parts <Chain transfer agent>
1-methyl-4-isopropylidene-1-cyclohexene 0.025 part <polymerization initiator>
Benzoyl peroxide 0.177 parts [post addition]
<Polymerization initiator>
Benzoyl peroxide 0.068 parts tert-butyl-2-ethylperoxyhexanoate 0.102 parts [diluent]
40.5 parts ethyl acetate

<Synthesis of tackifier>
(Synthesis Example 3)
A polymerization reaction apparatus equipped with a reaction tank, a stirrer, a thermometer, a reflux condenser, a dropping tank, and a nitrogen introduction tube was prepared. A monomer mixture consisting of the following monomers, solvent, chain transfer agent, and polymerization initiator is charged to the reaction tank and the dropping tank at the following ratio, and the air in the reaction tank is replaced with nitrogen gas, and then nitrogen is added while stirring. Under an atmosphere, the temperature was raised to 80 ° C., and the reaction was carried out for 3 hours with stirring. Further, a polymerization initiator was added later and reacted for 4 hours. After the reaction, a diluent solvent shown below was added and cooled to room temperature to obtain a solution containing a tackifier. The obtained tackifier had a weight average molecular weight (Mw) of 3,300, a glass transition temperature of 60 ° C., and a nonvolatile content of 70%.

[Reaction tank]
<Monomer having an ethylenically unsaturated bond>
((Meth) acrylic acid ester monomer)
IBXA 100 parts <solvent>
Ethyl acetate 27.7 parts <Chain transfer agent>
2-ethylhexyl thioglycolate 10.8 parts <polymerization initiator>
2,2'-azobis (isobutyronitrile) 0.12 parts [post-addition]
<Polymerization initiator>
2,2'-azobis (isobutyronitrile) 0.04 part [diluting solvent]
10.6 parts ethyl acetate

Example 1
<Manufacture of an adhesive composition>
For 100 parts of the acrylic polymer (A) obtained in Synthesis Example 1, 2.2 parts of XDI-TMP as the polyfunctional isocyanate compound (B), 3.0 parts of borneol as the alcohol (C), tackifier As a pressure-sensitive adhesive composition, 20 parts of the acrylic polymer obtained in Synthesis Example 3 was uniformly blended in terms of nonvolatile content.

<Manufacture of adhesive sheet>
A comma coater was applied to the release treatment surface of a 38 μm-thick polyethylene terephthalate peelable film substrate [“SP-PET 382050” manufactured by Lintec Corporation, hereinafter referred to as “release film substrate”] having a thickness of 38 μm. After coating at a speed of 2 m / min so that the thickness after drying was 25 μm, it was dried at 100 ° C. for 2 minutes to form an adhesive layer. This pressure-sensitive adhesive layer surface and a 50 μm-thick polyester film (“E5100” manufactured by Toyobo Co., Ltd.) were laminated to form a pressure-sensitive adhesive sheet. The obtained pressure-sensitive adhesive sheet was aged for 1 week in an environment of a temperature of 23 ° C. and a relative humidity of 50% to obtain a pressure-sensitive adhesive sheet.

(Examples 2 to 8)
A pressure-sensitive adhesive composition in the same manner as in Example 1 except that the acrylic polymer (A), polyfunctional isocyanate compound (B), alcohol (C), and tackifier were changed to those shown in Table 1. And obtained an adhesive sheet.

(Comparative Examples 1-7)
A pressure-sensitive adhesive composition in the same manner as in Example 1 except that the acrylic polymer (A), the polyfunctional isocyanate compound (B), the alcohol (C), and the tackifier were changed to those shown in Table 2. And obtained an adhesive sheet.

<Evaluation>
The pressure sensitive adhesive compositions and pressure sensitive adhesive sheets obtained in Examples 1 to 8 and Comparative Examples 1 to 7 were evaluated by the following methods. The results are shown in Tables 1 and 2.

(PP adhesive strength)
The adhesive strength was measured according to JIS Z 0237. The obtained pressure-sensitive adhesive sheet is cut to a width of 25 mm, and the peelable film base material is peeled off and pasted on a polypropylene plate (product name “Kobe Poly Sheet PP”, manufactured by Yamaso Co., Ltd.) in an atmosphere at a temperature of 23 ° C. and a relative humidity of 50%. After wearing and reciprocating once with a 2 kg roll, and letting it stand in the same environment for 24 hours, in the same environment, using a tensile tester (product name “Tensilon”, manufactured by Orientec Co., Ltd.), a pulling speed of 300 mm The peel strength when peeled in the direction of 180 degrees per minute was measured.
14 N / 25 mm or more: Excellent in practical use.
9 N / 25 mm or more and less than 14 N / 25 mm: practical range.
Less than 9 N / 25 mm: not practical.

(PP curved surface adhesion)
The obtained adhesive sheet was cut into a 25 mm × 25 mm test piece, the peelable film substrate was peeled off, and a polypropylene plate with a diameter of 10 mm in an environment of a temperature of 23 ° C. and a relative humidity of 50% (product name “Kobe Poly Sheet PP”, After sticking to a stick of Yamasosha) and press-bonding, the floating and peeling of the end of the test piece after standing for 1 day in an environment at a temperature of 60 ° C. were measured and evaluated in three stages.
Lift is 2 mm or less: Excellent in practical use.
Float is 2 mm to 5 mm: practical range.
Floating exceeds 5 mm: impractical.

(Appearance of coating film)
The obtained adhesive sheet was allowed to stand for 7 days in an atmosphere at a temperature of 40 ° C., and the appearance of the coating film was visually observed and evaluated in three stages.
○: Colorless and transparent. Excellent in practical use.
Δ: Slightly colored but transparent. Practical area.
X: A cloudiness or yellowing or many aggregates are recognized. Not practical.

(Holding power)
The holding power was measured according to JIS Z 0237. The obtained adhesive sheet was cut to 25 mm in width and 100 mm in length, and the peelable film base material was peeled off and attached to one end of a stainless steel plate (SUS304) in which portions of 25 mm in length and 25 mm in width were polished with sandpaper (# 280). A test piece was prepared by pasting with an area of 25 mm × 25 mm. The stainless steel plate of this test piece was suspended vertically in a constant temperature bath at 40 ° C., and a 1 kg weight was suspended at the other end of the sheet piece and left for 72000 seconds. When the sheet piece fell within 72,000 seconds, the time until the sheet piece was dropped was measured, and for the held sheet piece, the length of deviation from the initial sticking portion was measured and evaluated in three stages.
◯: There was no deviation because it was held. Excellent in practical use.
(Triangle | delta): It is what was hold | maintained and the shift | offset | difference is less than 1 mm. Practical area.
X: What was held and the deviation exceeded 1 mm or dropped. Not practical.

Claims (4)

  An adhesive composition comprising an acrylic polymer (A), a polyfunctional isocyanate compound (B) and an alcohol (C), wherein the acrylic polymer (A) has a hydroxyl group and / or a carboxyl group The alcohol (C) is a monoalcohol having a molecular weight of 140 or more and 500 or less, one or more alicyclic hydrocarbon groups, and one secondary hydroxyl group, and an acrylic polymer (A) 100 An adhesive composition comprising 0.5 to 15 parts by mass of alcohol (C) with respect to parts by mass.   The pressure-sensitive adhesive according to claim 1, wherein the alcohol (C) is a monoalcohol having a molecular weight of 140 to 500, two or more alicyclic hydrocarbon groups, and one secondary hydroxyl group. Agent composition.   The alcohol (C) is a monoalcohol having a molecular weight of 140 or more and 500 or less, having one or more condensed alicyclic hydrocarbon groups, and one secondary hydroxyl group. The pressure-sensitive adhesive composition described.   The adhesive sheet by which the adhesive layer formed from the adhesive composition in any one of Claims 1-3 is laminated | stacked on the at least one surface of a sheet-like base material.