JP6531452B2 - Pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet - Google Patents

Description

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

  Acrylic-based pressure-sensitive adhesives are conventionally used in various industrial fields because they are excellent in adhesion properties such as adhesion and cohesion, heat resistance, aging resistance such as weather resistance, and, depending on the application, adherends There is a tendency to demand high performance that is not confined to

  Among them, polyolefin materials typified by polyethylene and polypropylene (hereinafter sometimes abbreviated as PP) tend to increase in recent years mainly in the automotive field, but due to their low polarity, adhesives adhere There is a difficult nature. In particular, the adhesion on a curved surface to a low polarity adherend is susceptible to stress due to deformation, and therefore, there has been a problem that peeling at the end portion or floating of a recess is likely to occur.

  As a method of enhancing the curved surface adhesion to these low polar adherends, a method of adding a rosin resin as a tackifier (tackifier) is known in the past, but when a rosin resin is added, it is low. Although the adhesion to a curved surface to a polar adherend is improved, the performance is not sufficient, and further, there are 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 of enhancing 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, but curved surface adhesion No mention was made of the sex, and further, even when the monofunctional alcohol described above was used for a general adhesive, the curved surface adhesion to the low polar adherend was not sufficient.

JP 2004-115681 A Japanese Patent Application Laid-Open No. 2006-037037

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

The present inventors reached the present invention as a result of earnestly examining in order to solve the above-mentioned problem.
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. And 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 acryl. The present invention relates to a pressure-sensitive adhesive composition comprising 0.5 to 15 parts by mass of alcohol (C) relative to 100 parts by mass of polymer (A).

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

  The present invention also relates to a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition is laminated on at least one surface of a sheet-like substrate.

  ADVANTAGE OF THE INVENTION By this invention, it became possible to provide the adhesive composition and adhesive sheet which are excellent in the adhesive force and curved-surface adhesiveness with respect to a low polar to-be-adhered body, and have high transparency.

  The embodiment of the present invention will be described in detail below, but the following description is an example (representative example) of the embodiment of the present invention, and the present invention is not limited to these contents unless the gist is 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 adhesion physical property in this specification means various physical properties, such as adhesive force, curved surface adhesiveness, and retention strength.

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

  The alcohol (C) is not particularly limited to the following examples, but compounds represented by the following formulas [1] to [8], isocamphorcyclohexanol, α-ambrinol, alicyclic hydrocarbon group Of 7 or more carbon atoms, and includes cycloalkanols, alkyl cycloalkanols, dialkyl cycloalkanols, trialkyl cycloalkanols, tetraalkyl cycloalkanols and the like.

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 each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, a carboxyalkylcarbonyl group, a formate alkylcarbonyl group, an acetoxyalkylcarbonyl group, Alkyl carbonyl alkyl group, alkyl carboxy group, carboxy alkyl carboxy group, formate alkyl carboxy group, acetoxy alkyl carboxy group, alkyl carboxy alkyl group, alkoxy group, carboxy alkoxy group, format alkoxy group, acetoxy alkoxy group, or phenyl group Is a group represented by any of the following.

  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 ethynyl group and prop-2-yn-1-yl group. In addition, "format" 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 cohesion can be obtained, and the curved surface adhesion to a low polarity adherend can be improved. When the molecular weight is 500 or less, it is possible to suppress the decrease in adhesive strength and the whitening of the pressure-sensitive adhesive sheet due to excessive cohesive force.

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

  Further, the alicyclic hydrocarbon group of the alcohol (C) is not particularly limited, but is preferably a saturated alicyclic hydrocarbon group. By the alicyclic hydrocarbon group being saturated, it is possible to suppress a decrease in transparency accompanying coloring over time.

  Furthermore, the alicyclic hydrocarbon group of the alcohol (C) is not particularly limited, but is preferably a fused alicyclic hydrocarbon group in which alicyclic hydrocarbon groups are condensed. When one or more alicyclic hydrocarbon groups have a condensed ring structure, sufficient cohesion 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 it is preferably in the form of being directly bonded to an alicyclic hydrocarbon group. When the hydroxyl group is directly bonded to the alicyclic hydrocarbon group, adjustment of the amount incorporated in the crosslinking reaction becomes easy from the viewpoint of the reactivity of the hydroxyl group.

The substituents 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 above formulas [1] to [8] _{Each of f7} , R _{g1 to} R _g5 and R _{h1 to} R _h7 is preferably a hydrogen atom, an alkyl group, an alkenyl group, and / or an 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 a low polarity adherend can be improved, and further, an acrylic polymer (A) and When the composition is made into an 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. By setting the boiling point to 170 ° C. or more, the volatilization of alcohol when drying the pressure-sensitive adhesive composition can be suppressed, and adjustment of the amount incorporated in the crosslinking reaction becomes easy.

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-tert-butyl-cyclohexanol, 2,6-bis-tert-butyl-4-methylcyclohexanol, 2-phenyl-1-cyclohexanol, isopulegol, dihydrocarbe Secondary monoalcohol having one alicyclic hydrocarbon group in one molecule such as ol, 4-hydroxycyclohexanecarboxylic acid, 4- (methoxycarbonyl) cyclohexan-1-ol, 1-cyclohexyl-1-pentanol
Oil in one molecule such as dicyclohexylmethanol, decatol, 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-Norbornenol, borneol, 1,3,3-trimethyl-2-norbornanol, hydroxydicyclopentadiene, 2,6,6-trimethylbicyclo [3.1.1] heptane-3-ol, isocampyl cyclohexanol, etc. And a secondary monoalcohol having a fused alicyclic hydrocarbon group in which two alicyclic hydrocarbon groups are condensed with each other,
The secondary monoalcohol etc. which have the condensed alicyclic hydrocarbon group which three alicyclic hydrocarbon groups, such as 2-adamantanol, condensed are mentioned.

  One of these alcohols (C) may be used alone, or two or more thereof may be used in combination.

  The content of alcohol (C) in the pressure-sensitive adhesive composition is preferably 0.5 to 15 parts by mass of alcohol (C) with respect to 100 parts by mass of acrylic polymer (A), and more preferably 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 polar 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 (meth) acrylic acid ester monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate and hexyl ( Examples include meta) 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 in that they can easily obtain appropriate adhesion 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 capable of reacting with the isocyanate group of the polyfunctional isocyanate compound (B) described later. Although there is no restriction | limiting in particular as a introduction method of a hydroxyl group and / or a carboxyl group, For example, in addition to a (meth) acrylic acid ester monomer, the monomer which has an ethylenically unsaturated bond which has a hydroxyl group, and / or ethylenic which has a carboxyl group By copolymerizing a monomer having an ethylenically unsaturated bond having a reactive functional group such as a monomer having an unsaturated bond, an acrylic polymer (A) having a hydroxyl group and / or a carboxyl group can be obtained.

  As a monomer having an ethylenically unsaturated bond having a hydroxyl group, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) Acrylate, hydroxyalkyl (meth) acrylates, such as 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. are mentioned.

  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, etc. And carboxylic acids 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 adhesion property is not impaired. As such a monomer, for example, a monomer having an ethylenic unsaturated bond having an epoxy group, a monomer having an ethylenic unsaturated bond having an amino group, a monomer having an ethylenic unsaturated bond having an isocyanato group, etc. are listed. be able to.

  As a monomer having an ethylenically unsaturated bond having an epoxy group, for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 6-methyl-3,4- Epoxycyclohexylmethyl (meth) acrylate and the like can be mentioned.

  As a monomer having an ethylenically unsaturated bond having an amino group, for example, monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate And monoalkylamino ester (meth) acrylates and the like.

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

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

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

  The proportion of the monomer having an ethylenic 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). And 0.5 to 10% by mass. When the amount is 0.1% by mass or more, sufficient crosslinking is formed, and high cohesion and good adhesive physical properties can be obtained. The increase of a glass transition temperature can be suppressed as it is 20 mass% or less, and a favorable adhesion physical property can be obtained.

  The weight average molecular weight of the acrylic polymer (A) is preferably 300,000 to 1,500,000, and more preferably 400,000 to 1,000,000, in terms of standard polystyrene equivalent by gel permeation chromatography (GPC). When the weight average molecular weight is 300,000 or more, sufficient cohesion and durability can be obtained. When the weight average molecular weight is 1.5 million or less, an increase in viscosity can be suppressed, and good coating suitability can be obtained.

  Moreover, -60 to 0 degreeC is preferable and, as for the glass transition temperature of an acrylic polymer (A), -50 to -10 degreeC is more preferable. When the glass transition temperature is -60 ° C. or more, sufficient cohesion can be obtained, and adhesion and durability can be enhanced. When the glass transition temperature is 0 ° C. or less, sufficient wettability can be obtained and adhesion can be enhanced.

  There is no restriction | limiting in particular as a manufacturing method of acrylic polymer (A), For example, it can obtain by polymerizing the monomer which has said ethylenically unsaturated bond by well-known radical polymerization reaction. The reaction may be carried out without a solvent, but it is preferable to use a solvent from the viewpoint of synthesis stability and handling. Further, from the viewpoint of molecular weight control, it is preferable to use a radical polymerization initiator (hereinafter sometimes abbreviated as “polymerization initiator”). In addition, known additives such as chain transfer agents may be used.

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

As the polymerization initiator, for example, benzoyl peroxide, tert-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxy dicarbonate, di-n-propyl peroxy dicarbonate, di (2-ethoxyethyl) peroxy dicarbonate Tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxy neodecanoate, tert-butyl peroxy bivalate, (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 (2,2, 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] and the like It can be mentioned.
One of these polymerization initiators may be used alone, or two or more thereof may be used in combination.

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

<Multifunctional isocyanate compound (B)>
The polyfunctional isocyanate compound (B) crosslinks with the hydroxyl group and / or the carboxyl group in the acrylic polymer (A) and the hydroxyl group in the alcohol (C) to form a network-like crosslinked structure, and thereby the pressure-sensitive adhesive It is used for the purpose of imparting high elasticity 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). Group-based isocyanates, aliphatic isocyanates, alicyclic isocyanates, and biuret bodies, nurate bodies, and adducts of a bifunctional or higher functional isocyanate compound.

  Examples of aromatic isocyanates 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 (alias: XDI, m-xylylene diisocyanate), ω, ω′-diisocyanate-1,4-dimethylbenzene (another) : P-xylylene diisocyanate), omega, omega .'- diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethyl xylylene diisocyanate.

  Examples of aliphatic isocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (alias: HMDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, and 1,3-butylene diisocyanate. And dodecamethylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate.

  As an alicyclic isocyanate, for example, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (alias: IPDI, isophorone diisocyanate), 1,3-cyclopentadiisocyanate, 1,3-cyclohexane diisocyanate, 1, 4-cyclohexanediisocyanate, methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), 1,4-bis (isocyanatomethyl) cyclohexane and the like.

  As a burette body, for example, a burette body of hexamethylene diisocyanate (product name "Sumidur N-75", manufactured by Sumika Bayer Urethane Co., Ltd .; product name "Duranate 24A-90 CX", manufactured by Asahi Kasei Chemicals Corporation) and the like can be mentioned.

  Examples of the nurate body include a nurate body of hexamethylene diisocyanate (product name "Sumidur N-3300" manufactured by Sumika Bayer Urethane Co., Ltd.), a nurate body of isophorone diisocyanate (product name "Desmodur Z-4370", Sumika Bayer Urethane Co., Ltd., a nurate body of tolylene diisocyanate (product name "Corronate 2030", manufactured by Nippon Polyurethane Industry Co., Ltd.), and the like.

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

In addition, as a low molecular weight active hydrogen-containing compound having two or more functions, for example, ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3 ′ -Dimethylolheptane, 2-methyl-1,8-octanediol, 3,3'-dimethylolheptane, 2-butyl-2-ethyl-1,3-propanediol, polyoxyethylene glycol (additional mole number is 10 or less) ), Polyoxypropylene glycol (additional mole number: 10 or less), 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neo Pentyl glycol, butylethyl pentanediol, 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, Bisphenols such as 4 '-(2-norbornylidene) diphenol, 4,4'-dihydroxybiphenol, o-, m-, and p-dihydroxybenzene, 4,4'-isopropylidenephenol, or bisphenol A or bisphenol F Aromatic diols such as bisphenols formed by adding an alkylene oxide such as ethylene oxide or propylene oxide to the
1,1,1-trimethylolpropane, 1,1,1-trimethylolbutane, 1,1,1-trimethylolpentane, 1,1,1-trimethylolhexane, 1,1,1-trimethylolheptane, 1,1,1-trimethylol octane, 1,1,1-trimethylol nonane, 1,1,1-trimethylol decane, 1,1,1-trimethylol undecane, 1,1,1-trimethylol dodecane, 1,1,1-trimethylol tridecane, 1,1,1-trimethylol tetradecane, 1,1,1-trimethylol pentadecane, 1,1,1-trimethylol hexadecane, 1,1,1-trimethylol hepta Decane, 1,1,1-trimethylol octadecane, 1,1,1-trimethylol nanodecane, 1,1,1-trimethylol-sec Butane, 1,1,1-trimethylol-tert-pentane, 1,1,1-trimethylol-tert-nonane, 1,1,1-trimethylol-tert-tridecane, 1,1,1-trimethylol- tert-Heptadecane, 1,1,1-trimethylol-2-methyl-hexane, 1,1,1-trimethylol-3-methyl-hexane, 1,1,1-trimethylol-2-ethyl-hexane, 1 And trimethylol branched alkanes such as 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, trimethylol hexadecene Trifunctional polyols such as metrolol heptadecene, trimethyloloctadecene, 1,2,6-butanetriol, 1,2,4-butanetriol, glycerin and the like;
Tetrafunctional or higher functional polyols such as pentaerythritol, dipentaerythritol, sorbitol, xylitol;
Aliphatic polyamines such as triethylenetetramine, diethylenetriamine and triaminopropane can be mentioned. The low molecular weight active hydrogen-containing compound having two or more functions may be used alone or in combination of two or more.

  One of these polyfunctional isocyanate compounds (B) may be used alone, or two or more thereof may be used in combination.

  Among the polyfunctional isocyanate compounds (B), in view of adhesion, heat resistance, compatibility and the like, the use of trifunctional isocyanate compounds is preferred, and trimethylolpropane adduct of tolylene diisocyanate, and trimethylolpropane of hexamethylene diisocyanate. An adduct, a trimethylolpropane adduct of isophorone diisocyanate, a trimethylolpropane adduct of xylylene diisocyanate, an isocyanurate of tolylene diisocyanate, an isocyanurate of hexamethylene diisocyanate, an isocyanurate of isophorone diisocyanate is more preferable, and tolylene is more preferable. Trimethylolpropane adduct of isocyanate and trimethylolpropane adduct of xylylene diisocyanate Preferred.

  The amount of the polyfunctional isocyanate compound (B) used in the present invention is the isocyanato group in the polyfunctional isocyanate compound (B), the hydroxyl group and / or the carboxyl group in the acrylic polymer (A), and the alcohol (C) The ratio of the total number of moles of hydroxyl groups (isocyanate group / (hydroxy group and / or carboxyl group)) is preferably 0.05 to 1.5, more preferably 0.1 to 0.8 . When it is 0.05 or more, sufficient crosslinking is formed, high cohesion and good constant load releasability and heat resistance can be obtained, and when it is 1.5 or less, the degree of crosslinking becomes excessively high. Cohesion can be suppressed, and good adhesion to the adherend can be obtained.

  The pressure-sensitive adhesive composition of the present invention is further known as a tackifier, a catalyst, an antioxidant, an ultraviolet absorber, a hydrolysis inhibitor, an antifungal agent, a thickener, a plasticizer, a filler, an antifoamer, etc. The additives of the above can be blended as required.

  As tackifiers, terpene resins, aliphatic petroleum resins, aromatic petroleum resins, coumarone-indene resins, phenol resins, terpene-phenol resins, rosin resins (rosin, polymerized rosin, hydrogenated rosin, and those) Well-known things, such as esterified thing with polyhydric alcohols, such as glycerol and pentaerythritol, resin acid dimer etc., acrylic resin, etc. 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 polymer (A), More preferably, it is 10-30 mass parts. When the content of the tackifier is in the above range, sufficient tackiness can be obtained.

  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), (meth) acrylic acid ester monomers It is preferable that it is an acrylic resin having a weight average molecular weight of 50,000 or less obtained by polymerizing a monomer having an ethylenically unsaturated bond.

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 organic metal compounds.
Examples of tertiary amines include triethylamine, tributylamine, dimethylbenzylamine, N-methyl morpholine, N-ethyl morpholine, N-cyclohexyl morpholine, N, N, N ', N'- tetramethyl ethylene diamine, N, N, N ', N'- tetramethylbutanediamine or N, N, N', N'- tetramethylhexanediamine, pentamethyldiethylenetriamine, bis (dimethylaminopropyl) urea, 1,4, 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-ethyl diethanol amine , Dimethylethanolamine and the like.
Examples of organic metal compounds include tin (II) acetate, tin (II) octoate, tin (II) ethylhexanoate, organic carboxylic acid tin (II) salts such as tin (II) laurate, dibutyltin diacetate, dibutyltin Organic carboxylic acid dialkyltin (IV) salts 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 diisopropoxy bis (acetyl acetonate), titanium tetra acetyl acetonate, titanium di-2-ethylhexoxy bis (2-ethyl 3-hydroxy hexoxide), 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 catalyst inhibitor such as acetylacetone can be used for the purpose of improving the pot life of the pressure-sensitive adhesive composition.

<Adhesive sheet>
The pressure-sensitive adhesive composition of the present invention can be used to obtain a laminate in which a pressure-sensitive adhesive layer is laminated on a substrate (hereinafter referred to as "pressure-sensitive adhesive sheet").

  As a substrate of the pressure-sensitive adhesive sheet, known substrates for pressure-sensitive adhesive sheets can be used. For example, film-like substrates such as paper, metal film, cellophane, various plastic films, and film-like substrates thereof The peelable film base material which carried out the peeling process of the surface with the silicone compound or the fluorine compound is mentioned. The substrate of the pressure-sensitive adhesive sheet may be a single layer, or may be a multilayer of a plurality of laminated substrates.

  As various plastic films, for example, films of polyolefin resins such as polyhydroxy ethene film and triacetyl cellulose film, polypropylene, polyethylene, polycycloolefin, ethylene-vinyl acetate copolymer and the like, polyesters such as polyethene terephthalate and polybutene terephthalate Film of polycarbonate resin, film of polycarbonate resin, film of polynorbornene resin, film of polyarylate resin, film of propenoic resin, film of polyphenylene sulfide resin, film of polyethenyl benzene resin, film of vinyl resin And films of polyamide resins, films of polyimide resins, films of oxirane resins, and the like.

  The laminated structure of the pressure-sensitive adhesive sheet is, for example, a single-sided pressure-sensitive adhesive sheet such as a film-like substrate / pressure-sensitive adhesive layer / release film substrate, or a release film substrate / pressure-sensitive adhesive layer / release film substrate, Adhesive film base / adhesive layer / film-like base material / pressure-sensitive adhesive layer / peelable film base material, and when used, the peelable film base material on one side or both sides is peeled off, The agent layer is attached to the adherend.

  The pressure-sensitive adhesive sheet is prepared by applying the 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 a substrate, and then cooled and solidified to form a pressure-sensitive adhesive layer on the substrate. be able to.

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

  There is no restriction | limiting in particular as a method of coating the adhesive composition of this invention to a peelable film base material etc. Meyer bar, an applicator, a brush, a spray, a roller, a gravure coater, a die coater, a lip coater, a comma coater, Coating can be performed using various coating machines such as a knife coater, reverse coater, spin coater and the like.

  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. The drying conditions depend on the crosslinking form of the pressure-sensitive adhesive composition, the film thickness, and the type of volatile liquid contained, but a method using hot air at about 60 to about 180 ° C. is generally preferable.

  The pressure-sensitive adhesive sheet obtained by the above-mentioned method exhibits good adhesion to each adherend, and thus can be used for applications such as label sealing, double-sided tape, cast tape, masking tape, foam tape and the like.

  Hereinafter, specific examples of the present invention will be described together with comparative examples, but the present invention is not limited to the following examples. Further, in the following Examples and Comparative Examples, "parts" and "%" respectively represent "parts by mass" and "% by mass" unless otherwise noted.

<Measurement of non-volatile content>
About 1 g of the sample solution was weighed in a metal container and dried in a 150 ° C. oven for 20 minutes, and the residue was weighed to calculate the percentage of residue, and it was defined as a non-volatile content (non-volatile 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. The column used was a series of two Tosoh Super HM-M and Super HM-L connected in series. It was measured at 40 ° C. using tetrahydrofuran (THF) as a solvent (eluent). In addition, the number average molecular weight (Mn) and the weight average molecular weight (Mw) were all converted values with 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). “SSC 5200 disc station” (manufactured by Seiko Instruments Inc.) was connected to a robot DSC (differential scanning calorimeter, “RDC 220” manufactured by Seiko Instruments Inc.) and used for measurement. The solution of the acrylic polymer obtained in each of the synthesis examples was coated on a polyester peelable film substrate and dried, and the dried one was used as a measurement sample. The measurement sample of 10 mg was set in the differential scanning calorimeter, and maintained at a temperature of 100 ° C. for 5 minutes, and then quenched to -120 ° C. using liquid nitrogen. Thereafter, the temperature was raised at a temperature rising rate of 10 ° C./min, and the temperature was raised 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)>
One gram of the sample was accurately weighed in a stoppered Erlenmeyer flask, and 100 ml of pyridine was added to dissolve it. Furthermore, exactly 5 ml of an acetylating agent (a solution obtained by dissolving 25 g of acetic anhydride in pyridine to make a volume of 100 ml) was added and stirred for 1 hour, and then titrated with a 0.5 N alcoholic potassium hydroxide solution. The hydroxyl value (unit: mg KOH / g) was determined by the following equation. The hydroxyl value is the value of the dried sample.
Hydroxyl value = [{(b−a) × F × 28.05} / S] / (nonvolatile content concentration / 100) + D
S: Amount of sample collected (g)
a: Consumption of 0.5 N-alcoholic potassium hydroxide solution (ml)
b: Consumption (ml) of 0.5 N alcoholic potassium hydroxide solution in blank experiment
F: Factor of 0.5 N-alcoholic potassium hydroxide solution
D: Acid value (mg KOH / g)

<Measurement of isocyanato value (NCO value)>
In a stoppered Erlenmeyer flask, accurately measure 10 g of a sample, 25 ml of ortho-dichlorobenzene, di-n-butylamine / o-dichlorobenzene (mass ratio: di-n-butylamine / o-dichlorobenzene = 1 / 24.8) 10 ml of the mixture was added and dissolved. To this solution, 80 g of methanol and bromphenol blue reagent were added as an indicator, and the solution was titrated with 0.1 N alcoholic hydrochloric acid solution. When the solution turned yellowish green and was kept for 30 seconds or more, the end point was taken. The NCO value (unit:%) was determined by the following equation.
NCO value = [0.42 × (B−C) × F] / W
W: amount of sample collected (g)
B: Consumption of 0.1 N alcoholic hydrochloric acid solution required for sample titration (ml)
C: Consumption of 0.1 N alcoholic hydrochloric acid solution required for titration of blank test (ml)
F: Factor of 0.1 N 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 2 EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate Vac: vinyl acetate 2 HEA: 2-hydroxyethyl acrylate AA: acrylic acid IBXA: isobornyl acrylate

<Chain transfer agent>
1-Methyl-4-isopropylidene-1-cyclohexene thioglycollate-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'-azobisisobutyro nitrile (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 matter = 50%
TDI-TMP: trimethylolpropane adduct of tolylene diisocyanate, number of isocyanato groups = 3, NCO value = 6.5%, non volatile matter = 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 reactor equipped with a reaction tank, a stirrer, a thermometer, a reflux condenser, a dropping tank, and a nitrogen introduction pipe was prepared. A monomer mixture consisting of the following monomers, a solvent, and a polymerization initiator is charged into the reaction tank and the dropping tank at the following ratio, air in the reaction tank is replaced with nitrogen gas, and then 80 under nitrogen atmosphere with stirring. It heated up to ° C. Next, the monomer mixture in the dropping tank was dropped over 1 hour. After completion of the dropwise addition, the reaction was carried out for 3 hours with stirring. Further, a polymerization initiator was post-added and allowed to react for 3 hours. After the reaction, the following dilution solvents were added, and the mixture was cooled to room temperature to obtain a solution containing an acrylic polymer (A). The weight average molecular weight (Mw) of the obtained acrylic polymer was 470,000, the glass transition temperature was -33.degree. C., and the nonvolatile content was 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 ethylenic unsaturated bond having a hydroxyl group)
2 HEA 0.35 parts (Monomers with other ethylenically unsaturated bonds)
Vac 4.0 parts <solvent>
Ethyl acetate 33.8 parts Toluene 0.9 parts <polymerization initiator>
0.071 parts of tert-butyl-2-ethylperoxyhexanoate [dropping tank]
<Monomer having an ethylenically unsaturated bond>
(Acrylate ester monomer)
52.1 parts of nBA (monomer having an ethylenic unsaturated bond having a hydroxyl group)
2 HEA 0.35 parts <solvent>
Ethyl acetate 39.7 parts Toluene 1.1 parts <polymerization initiator>
0.071 parts of tert-butyl-2-ethylperoxyhexanoate [post-added]
<Polymerization initiator>
tert-Butyl-2-ethylperoxyhexanoate 0.12 parts [diluted solvent]
Ethyl acetate 21.5 parts Toluene 2.9 parts

(Composition example 2)
A solution containing an acrylic polymer (A) was obtained in the same manner as in Synthesis Example 1 except that the types and blending amounts of the monomer, the solvent, and the polymerization initiator were changed to the following. The weight average molecular weight (Mw) of the obtained acrylic polymer was 520,000, the glass transition temperature was −43 ° C., and the nonvolatile matter was 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 ethylenic unsaturated bond having a hydroxyl group)
2 HEA 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 [dropping tank]
<Monomer having an ethylenically unsaturated bond>
(Acrylate ester monomer)
nBA 51.0 parts 2EHA 13.3 parts (monomers having an ethylenic unsaturated bond having a hydroxyl group)
2 HEA 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 [diluted solvent]
Ethyl acetate 40.5 parts

<Synthesis of Tackifier>
(Composition example 3)
A polymerization reactor equipped with a reaction tank, a stirrer, a thermometer, a reflux condenser, a dropping tank, and a nitrogen introduction pipe was prepared. A monomer mixture consisting of the following monomers, a solvent, a chain transfer agent, and a polymerization initiator is charged into the reaction tank and the dropping tank at the following ratio, air in the reaction tank is replaced with nitrogen gas, and then nitrogen is stirred The temperature was raised to 80 ° C. under an atmosphere, and reaction was performed for 3 hours while stirring. Furthermore, a polymerization initiator was post-added and allowed to react for 4 hours. After the reaction, the following dilution solvents were 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>
10.8 parts of 2-ethylhexyl thioglycolate <polymerization initiator>
0.12 parts of 2,2'-azobis (isobutyronitrile) [post-addition]
<Polymerization initiator>
2,2'-azobis (isobutyronitrile) 0.04 part [diluted solvent]
Ethyl acetate 10.6 parts

Example 1
<Production of Pressure-Sensitive Adhesive Composition>
To 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), and a tackifier 20 parts of the acrylic polymer obtained in Synthesis Example 3 was uniformly mixed in terms of non-volatile content to obtain a pressure-sensitive adhesive composition.

<Manufacture of adhesive sheet>
The obtained pressure-sensitive adhesive composition was coated on a release-treated surface of a 38 μm-thick polyethylene terephthalate peelable film substrate [Lintech Corporation “SP-PET 382050”, hereinafter referred to as “peelable film substrate”] The composition was coated at a speed of 2 m / min so that the thickness after drying was 25 μm, and then dried at 100 ° C. for 2 minutes to form a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer side 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 was prepared 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 1. And got an adhesive sheet.

(Comparative Examples 1 to 7)
A pressure-sensitive adhesive composition was prepared 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 got an adhesive sheet.

<Evaluation>
The pressure-sensitive adhesive compositions and the 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 force)
The adhesion was measured according to JIS Z 0237. The obtained adhesive sheet is cut into a width of 25 mm, and the peelable film substrate is peeled off and attached to a polypropylene plate (product name "Kobe PolySheet PP", manufactured by Yamamune Corporation) under an atmosphere of temperature 23 ° C and relative humidity 50%. After putting on, 2 kg roll for 1 reciprocation, after pressure bonding, leaving under the same environment for 24 hours, under the same environment, using a tensile tester (product name "Tensilon", manufactured by ORIENTEC Co., Ltd.), tensile speed 300 mm Peeling strength at the time of peeling in the direction of 180 degrees was measured by 1 / min.
14N / 25 mm or more: Excellent practically.
9N / 25mm or more, less than 14N / 25mm: Practical area.
Less than 9N / 25mm: not practical.

(PP curved surface adhesion)
A test piece is cut into a piece of 25 mm x 25 mm, and the peelable film substrate is peeled off, and a polypropylene plate of 10 mm in diameter (product name: "Kobe poly sheet PP") under an environment of 23 ° C and a relative humidity of 50%. After bonding and pressure bonding to a stick made by Yamamune Co., Ltd., floating and peeling of the end portion of the test piece after leaving it for 1 day in an environment of a temperature of 60 ° C. were measured and evaluated in three steps.
The float is 2 mm or less: practically excellent.
Lift is 2 mm or more and 5 mm or less: practical range.
Lifting exceeds 5 mm: not practical.

(Coating film appearance)
The obtained pressure-sensitive adhesive sheet was left to stand for 7 days in an atmosphere at a temperature of 40 ° C., and the appearance of the coating was visually observed and evaluated in three steps.
○: colorless and transparent. Excellent for practical use.
Δ: Slightly colored but having transparency. Practical area.
X: Cloudy or yellowish, or many aggregates are observed. Not practical.

(Holding force)
The holding power was measured according to JIS Z 0237. The obtained adhesive sheet is cut 25 mm wide and 100 mm long, and the peelable film substrate is peeled off and attached to one end of a stainless steel plate (SUS 304) polished 25 mm long and 25 mm wide with a sandpaper (# 280) It stuck by area 25 mm x 25 mm, and created the test piece. The stainless steel plate of this test piece was vertically suspended in a 40 ° C. constant temperature bath, and a 1 kg weight was suspended at the other end of the sheet piece and left for 72000 seconds. In the case where the sheet piece fell within 72000 seconds, the time until it fell was measured, and for those that were held, the length of displacement from the initial adhering portion was measured and evaluated in three stages.
○: There is no gap in what was held. Excellent for practical use.
:: The displacement was within 1 mm because it was held. Practical area.
X: The one that was held and the deviation exceeded 1 mm or was dropped. Not practical.

Claims (4)

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 all monomers constituting the acrylic polymer (A). In 100% by mass, it has 0.1 to 20% by mass of a monomer having a hydroxyl group and / or a carboxyl group, alcohol (C) has a molecular weight of 140 or more and 500 or less, and has one or more alicyclic hydrocarbon groups. A pressure-sensitive adhesive composition comprising 0.5 to 15 parts by mass of alcohol (C) per 100 parts by mass of acrylic polymer (A). object.   The adhesive according to claim 1, wherein the alcohol (C) is a monoalcohol having a molecular weight of 140 or more and 500 or less, having two or more alicyclic hydrocarbon groups, and having 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 fused alicyclic hydrocarbon groups, and having one secondary hydroxyl group. The adhesive composition as described.   The adhesive sheet formed by laminating | stacking the adhesive layer formed from the adhesive composition in any one of Claims 1-3 on the at least one surface of a sheet-like base material.