JP5990763B2 - Adhesive composition and adhesive sheet - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet. More specifically, the present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet excellent in pressure-sensitive adhesive properties such as curved surface adhesion to a low polarity adherend and constant load peelability in a high temperature environment.

  Adhesives are used in various industrial fields because they can join materials easily and in a short time. Depending on the application, higher performances such as high adhesion reliability not caught by the adherend, peeling resistance, adhesion to a curved substrate, and adhesion reliability under severe environmental conditions tend to be required.

  Among them, polyolefin materials typified by polyethylene and polypropylene have been used in recent years, mainly in the automotive field, but have a property that the adhesive is difficult to adhere because of its low polarity. In particular, the adhesion to a curved low-polarity adherend is susceptible to stress due to deformation, and therefore, there is a problem that peeling at the end portion and floating of the concave portion are likely to occur.

  Furthermore, as a more severe environmental condition, for example, in automobiles and the like, it is used in a high temperature environment in summer and in a low temperature environment in winter. Even when the environment changes, adhesion reliability and constant load peeling performance that does not cause floating or peeling are required. However, conventional pressure-sensitive adhesives have a problem of insufficient heat resistance such as insufficient cohesion when peeled off when used in a high temperature environment.

  Up to now, as a technique for improving curved surface adhesion, constant load peelability, and heat resistance of an adhesive to an adherend, an acrylic adhesive composition, a rosin resin, a terpene resin, an aliphatic (C5 system) A method of adding a tackifier such as an aromatic (C9), an alicyclic (hydrogenated product), a styrene resin, a phenol resin, or a xylene resin is known.

  However, the addition of these tackifiers improves curved surface adhesion, constant load peelability, and heat resistance to low polarity adherends, but its performance is not sufficient, especially curved surfaces in high temperature environments. There was a problem that adhesion and constant load peelability were insufficient. (Patent Documents 1 to 4).

JP-A-7-228851 JP 2000-265138 A JP 2007-091918 A JP 2014-189656 A

  It is an object of the present invention to provide a pressure-sensitive adhesive composition excellent in pressure-sensitive adhesive performance such as curved surface adhesion and constant load peelability to a low-polar adherend in a high-temperature environment, and a pressure-sensitive adhesive sheet using the same. To do.

The inventors of the present invention have reached 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 for automobile interior materials comprising an acrylic polymer (A), a polyfunctional isocyanate compound (B), and a compound (C) having a steroid skeleton,
The acrylic polymer (A) is an acrylic polymer having a hydroxyl group and / or a carboxyl group, and the compound (C) having a steroid skeleton is selected from a hydroxyl group, a hydroxyalkylcarbonyl group, a hydroxyalkylcarboxy group, and a hydroxyalkoxy group. The other substituents are alkyl groups, alkenyl groups, alkynyl groups, formyl groups, alkylcarbonyl groups, carboxyalkylcarbonyl groups, formate alkylcarbonyl groups, acetoxyalkylcarbonyl groups, alkylcarboxy groups, Carboxyalkylcarboxy group, formate alkylcarboxy group, acetoxyalkylcarboxy group, alkoxy group, carboxyalkoxy group, formate alkoxy group, acetoxyalkoxy group, benzoyloxy group, and below Equation [18] chosen group from (where the alkyl carboxy group, * - O-C (= O) a -R, * represents a bond), and acrylic polymer (A) 100 parts by mass of It is related with the adhesive composition for motor vehicle interior materials characterized by including 0.1-20 mass parts of compounds (C) which have a steroid frame | skeleton with respect to this.
Formula [18]

Moreover, this invention relates to the said adhesive composition for automotive interior materials whose compound (C) which has a steroid skeleton is a compound (C1-2) which has a steroid skeleton which has a secondary hydroxyl group.

Moreover, this invention relates to the adhesive sheet for automotive interior materials 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 has become possible to provide a pressure-sensitive adhesive composition excellent in pressure-sensitive adhesive properties such as curved surface adhesion and constant load peelability to a low polarity adherend in a high-temperature environment, and a pressure-sensitive adhesive sheet using the same. .

These are the schematic diagrams at the time of testing the constant load peelability of an adhesive sheet.

  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 a compound (C) having a steroid skeleton.

  In the present specification, the adhesive physical property means various physical properties such as adhesive strength to low polarity adherend, re-peelability, holding power, curved surface adhesion, constant load peelability, and in particular to low polar adherend. The curved surface adhesion means physical properties at room temperature and heat resistance.

When the pressure-sensitive adhesive composition of the present invention is used as a pressure-sensitive adhesive sheet, it exhibits good adhesion to each adherend, and is used for applications such as label seals, double-sided tapes, cast tapes, masking tapes, foam tapes, etc. can do.
The curved surface adhesion tends to be regarded as important in any application, whereas the constant load peelability tends to be regarded as important particularly in automobile applications. Adhesives used for automobiles are processed into double-sided tapes and cast tapes, and then applied to interior materials and then used on automobiles, or as foam tapes based on interior materials. Can be used by sticking to the car. This interior material includes not only interior materials used in automobiles but also sound absorbing materials used in engine rooms, cushioning materials, and carpets, and means members widely used in automobiles.

<Compound (C) having steroid skeleton>
The compound (C) having a steroid skeleton is a compound having a cyclopentano-perhydrophenanthrene nucleus (synonymous with a steroid nucleus) as a basic skeleton, and generally contains many hormones, but has various structures depending on substituents. There are many that exist in plants.

  Examples of the compound (C) having a steroid skeleton include a skeleton having a cyclopentano-perhydrophenanthrene nucleus and / or a structure having a substituent at a specific site of the skeleton having an analogous structure. Examples include compounds represented by the following formulas [1] to [11], saponins, and the like.

Formula [1]

Formula [2]

Formula [3]

Formula [4]

Formula [5]

Formula [6]

Formula [7]

Formula [8]

Formula [9]

Formula [10]

Formula [11]

  Further, the structure of the alicyclic moiety of the above formulas [1] to [11] includes an alicyclic structure composed of a cyclopentano-perhydrophenanthrene nucleus as shown in the following formulas [12] to [17], and the alicyclic structure. A structure in which a part of is an unsaturated double bond is mentioned.

Formula [12]

Formula [13]

Formula [14]

Formula [15]

Formula [16]

Formula [17]

In the above formulas [1] to [11], R _{a1 to} R _a9 , R _{b1 to} R _b9 , R _{c1 to} R _c7 , R _{d1 to} R _d8 , R _{e1 to} R _e9 , R _{f1 to} R _f8 , R _g1 to R _g6 , R _{h1 to} R _h7 , R _{i1 to} R _i5 , R _{j1 to} R _j7 and R _{k1 to} R _k7 are each independently
Hydrogen atom, alkyl group, alkenyl group, alkynyl group, hydroxyl group, formyl group,
Alkylcarbonyl group, hydroxyalkylcarbonyl group, carboxyalkylcarbonyl group, formate alkylcarbonyl group, acetoxyalkylcarbonyl group,
Alkylcarboxy group, hydroxyalkylcarboxy group, carboxyalkylcarboxy group, formate alkylcarboxy group, acetoxyalkylcarboxy group,
Alkoxy group, hydroxyalkoxy group, carboxyalkoxy group, formate alkoxy group, acetoxyalkoxy group,
A benzoyloxy group or a group represented by the following formula [18].
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.
(“Formate” means “—O—CH═O”. In the following formula, | * | indicates a bond.)

Formula [18]

  Saponin has a structure in which a saccharide is bonded to a steroid nucleus, and examples thereof include solanine represented by the following formula [19]. Examples of the sugar include D-glucose, D-galactose, L-arabinose, D-rhamnose and the like.

Formula [19]

  Among these, the compound (C1) having a steroid skeleton having a hydroxyl group is preferable among the compounds (C) having a steroid skeleton, and the compound (C1-2) having a steroid skeleton having a secondary hydroxyl group is more preferable. By having a hydroxyl group, it is partially incorporated into the cross-linking reaction between the acrylic polymer (A) and the polyfunctional isocyanate compound (B), thereby improving the curved surface adhesion and the constant load peelability to the low polarity adherend. Can do. In particular, when it has a secondary hydroxyl group, it is preferable because the amount incorporated in the crosslinking reaction can be easily adjusted.

  The number of hydroxyl groups in the compound (C) having a steroid skeleton is not particularly limited, but may be one from the viewpoint of adhesion to a low-polar adherend and compatibility with the acrylic polymer (A). preferable.

  Furthermore, the molecular weight of the compound (C) having a steroid skeleton is preferably 250 to 800, and more preferably 300 to 500. When the molecular weight is 250 or more, sufficient cohesive force can be obtained, and curved surface adhesion to a low-polar adherend and constant load peelability can be improved. When the molecular weight is 800 or less, excessive cohesive force can be suppressed, and a decrease in adhesive force can be suppressed.

Other preferred embodiments include R _{a1 to} R _a9 , R _{b1 to} R _b9 , R _{c1 to} R _c7 , R _{d1 to} R _d8 , and R _e1 to R ₁ , which are substituents in the formulas [1] to [11]. R _e9 , R _{f1 to} R _f8 , R _{g1 to} R _g6 , R _{h1 to} R _h7 , R _{i1 to} R _i5 , R _{j1 to} R _j7, or R _{k1 to} R _k7 , an alkyl having 5 or more carbon atoms It is preferable to have one or more groups, alkenyl groups, and / or alkynyl groups. In the case of having an alkyl group, an alkenyl group and / or an alkynyl group having 5 or more carbon atoms as a substituent, adhesion to a low-polar adherend can be improved, and the acrylic polymer (A) The compatibility with is improved.

Specific examples of the compound (C) having a steroid skeleton described above include
A compound having a steroid skeleton having a primary monofunctional hydroxyl group, such as desoxycorticosterone 11-dehydrocorticosterone,
Cholesterol, β-sitosterol, campesterol, stigmasterol, brassicasterol, lanosterol, ergosterol, β-cholestanol, testosterone, estrone, digitoxigenin, dehydroepiandrosterone, coprostanol, pregnenolone, epicholestanol, 7-dehydrocholesterol , A compound having a steroid skeleton having a secondary monofunctional hydroxyl group such as estradiol benzoate, tigogenin, hecogenin, etc.
A compound having a steroid skeleton having a tertiary monofunctional hydroxyl group such as methanedienone, cortisone acetate, stenolone,
1,4-androstadien-3,17-dione, 4-androstene-3,17-dione, deoxycorticosterone acetate, cholesterol acetate, (22E) -stigmaster-5,22-dien-3β-ol Has hydroxyl groups such as acetate, progesterone, acetic acid 20-oxopregna-5,16-dien-3β-yl, 4-androstene-3,11,17-trione, 5α-androstane, cholestane, pregnane, estrane A compound having no steroid skeleton,
β-estradiol, α-estradiol, boranediol, methylandrostenediol, cortisone, prednisolone, corticosterone, aldosterone, 18-hydroxycorticosterone, 4-androstene-11α, 17β-diol-3-one, 4- Examples thereof include compounds having a steroid skeleton having a polyfunctional hydroxyl group such as androstene-16α, 17β-diol-3-one, hyodeoxycholic acid, and solanine.
Among these, cholesterol, β-sitosterol, campesterol, stigmasterol, brassicasterol, lanosterol, ergosterol, β-cholestanol, coprostanol, epicholestanol, 7-dehydrocholesterol, cholesterol acetate, (22E) -stigmaster -5,22-diene-3β-ol acetate, cholesterol, β-sitosterol, campesterol, stigmasterol, brassicasterol, lanosterol, ergosterol, β-cholestanol, coprostanol, epicholestanol, 7 -Dehydrocholesterol is more preferred, cholesterol, β-sitosterol, campesterol, stigmasterol, brassicasterol, lanosterol, ell Sterols, beta-cholestanol is particularly preferred.

These compounds (C) having a steroid skeleton may be used singly or in combination of two or more.
<< Embodiment 1 (Label Adhesive) >>

The content of the compound (C) having a steroid skeleton in the pressure-sensitive adhesive composition includes 0.5 to 20 parts by mass of the compound (C) having a steroid skeleton with respect to 100 parts by mass of the acrylic polymer (A). It is preferable that it is 0.8-10 mass parts, More preferably, it is 1.0-5.0 mass parts. When the content of the compound (C) having a steroid skeleton is in the above range, good curved surface adhesion to a low-polar adherend can be obtained.
Moreover, content of the compound (C) which has a steroid skeleton in an adhesive composition contains 0.2-13 mass parts of compounds (C) which have a steroid skeleton with respect to 100 mass parts of adhesive compositions. Is more preferable, 0.4 to 6.0 parts by mass, and still more preferably 0.6 to 4.0 parts by mass.

<< Embodiment 2 (Automobile Adhesive) >>
The content of the compound (C) having a steroid skeleton in the pressure-sensitive adhesive composition includes 0.5 to 20 parts by mass of the compound (C) having a steroid skeleton with respect to 100 parts by mass of the acrylic polymer (A). Preferably, it is 2.0 to 13 parts by mass. When the content of the compound (C) having a steroid skeleton is in the above range, a good constant load peelability for a low-polar adherend can be obtained.
Moreover, content of the compound (C) which has a steroid skeleton in an adhesive composition contains 0.2-13 mass parts of compounds (C) which have a steroid skeleton with respect to 100 mass parts of adhesive compositions. Is more preferable, and 1.0 to 8.0 parts by mass is more preferable.

<Acrylic polymer (A)>
As used herein, the acrylic polymer (A) means a polymer or copolymer 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. The acrylic polymer which has. Here, “(meth) acrylic acid ester monomer” refers to a generic term of “acrylic acid ester monomer” and “methacrylic acid ester monomer”.

  Specific 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. (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 in that 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 an isocyanato group contained in the polyfunctional isocyanate compound (B) described later. Therefore, in addition to the (meth) acrylic acid ester monomer, an ethylenically unsaturated group having a reactive functional group such as a monomer having an ethylenically unsaturated bond having a hydroxyl group and / or a monomer having an ethylenically unsaturated bond having a carboxyl group. An acrylic polymer (A) obtained by polymerizing monomers having a saturated bond together is used.

  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 another functional group can be used as long as the physical properties of the adhesive are not impaired. Examples of the monomer having an ethylenically unsaturated bond having another functional group include, for example, a monomer having an ethylenically unsaturated bond having an epoxy group, a monomer having an ethylenically unsaturated bond having an amino group, and an ethylene having an isocyanato group. And monomers having a ionic unsaturated bond.

  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. And monoalkylamino ester (meth) acrylate.

  Examples of the monomer having an ethylenically unsaturated bond having an isocyanato group include 2-isocyanatoethyl (meth) acrylate.

  Examples of monomers other than the above include (meth) acrylamides such as (meth) acrylamide, N-methyl (meth) acrylamide, and N-methylol (meth) acrylamide, vinyl acetate, vinyl crotonic acid, styrene, acrylonitrile, and the like. Can be used as a monomer having an ethylenically unsaturated bond.

  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.

  As for the monomer constituting the acrylic polymer (A), the ratio of the monomer having an ethylenically unsaturated bond having a hydroxyl group and / or a carboxyl group is 100% in 100% by mass of all monomers constituting the acrylic polymer (A). It is preferable that it is in the range of ˜20% by mass, and more preferably 0.5 to 10% by mass. 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.

  Further, the glass transition temperature of the acrylic polymer (A) is preferably −60 to 0 ° C. so that when the pressure-sensitive adhesive sheet is used, a well-balanced pressure-sensitive adhesive property (particularly, both tack and cohesive force) can be exhibited. -50 to -10 ° C is more preferable. When the glass transition temperature is −60 ° C. or higher, sufficient cohesive force can be obtained, and adhesive strength and durability can be improved. When the glass transition temperature is 0 ° C. or lower, sufficient wettability can be obtained and the adhesive strength can be increased.

The acrylic polymer (A) can be obtained by polymerizing the monomer having the ethylenically unsaturated bond. The polymerization can be performed by a known polymerization method, and the polymerization can be performed in a solution or in the absence of a solvent.
Examples of the solvent to be used 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.

  Furthermore, a chain transfer agent can 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, dodecyl mercaptan, thioglycolic acid esters such as octyl thioglycolate, nonyl thioglycolate, and 2-ethylhexyl thioglycolate, 2, 4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene, α-pinene, β-pinene and the like can be mentioned. 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).

Examples of the polymerization initiator used for polymerization include benzoyl peroxide, tert-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2- Ethoxyethyl) peroxydicarbonate, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxyneodecanoate, tert-butylperoxybivalate, (3,5,5-trimethylhexanoyl) Organic peroxides such as peroxide, dipropionyl peroxide, 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 are not particularly limited, but one kind may be used alone, or two or more kinds may be used in combination.

<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 has high elasticity for use as an adhesive, Used for the purpose of imparting substrate adhesion. 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), but is not limited to aromatic isocyanate, aliphatic isocyanate and Examples include at least one compound selected from alicyclic isocyanates, and modified products of these compounds.

  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, and 1,3-tetramethylxylylene 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.

  Among the isocyanate compounds, a trifunctional or higher functional isocyanate compound is preferable because it forms a sufficient cross-linked structure. Specifically, the isocyanate is a burette body, a nurate body, and an adduct body. Compound etc. are mentioned.

  The burette body refers to a self-condensate having a burette bond formed by self-condensation of a polyisocyanate monomer having two or more isocyanato groups in one molecule. For example, a burette body of hexamethylene diisocyanate (Sumidule N- 75, manufactured by Sumika Bayer Urethane Co., Ltd .; Duranate 24A-90CX, manufactured by Asahi Kasei Chemicals Corporation).

  The nurate body means a trimer of a polyisocyanate monomer having two or more isocyanato groups in one molecule, for example, hexamethylene diisocyanate trimer (Sumijour N-3300, manufactured by Sumika Bayer Urethane Co., Ltd.). , Isophorone diisocyanate trimer (Desmodur Z-4370, manufactured by Sumika Bayer Urethane Co., Ltd.), tolylene diisocyanate trimer (Coronate 2030, manufactured by Nippon Polyurethane Co., Ltd.), and the like.

  An adduct is a general term for a bifunctional or higher functional isocyanate compound obtained by reacting a polyisocyanate monomer having two or more isocyanato groups in one molecule with a bifunctional or higher molecular weight active hydrogen-containing compound. , A compound obtained by reacting trimethylolpropane and hexamethylene diisocyanate (Takenate D-160N, manufactured by Mitsui Chemicals), a compound obtained by reacting trimethylolpropane and tolylene diisocyanate (Coronate L, manufactured by Nippon Polyurethane; Takenate D) -102, manufactured by Mitsui Chemicals), a compound obtained by reacting trimethylolpropane and xylylene diisocyanate (Takenate D-110N, manufactured by Mitsui Chemicals), a compound obtained by reacting trimethylolpropane and isophorone diisocyanate (Takenate D- 140N, Ikagaku Co., Ltd.), 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′-di- Methylol 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 10 or less), 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol , Butylethylpentanediol, 2-ethyl-1,3-hexane Aliphatic or cycloaliphatic diols such as all, cyclohexanediol, cyclohexanedimethanol, tricyclodecanedimethanol, cyclopentadienedimethanol, 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′-dihydroxy Bisphenol obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to bisphenols such as biphenol, o-, m-, and p-dihydroxybenzene, 4,4′-isopropylidenephenol, or bisphenol A and bisphenol F Aromatic diols such as class;
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; trimethylolbutene, trimethylolheptene, trimethylolpentene, trimethylolhexene, Trimethylol heptene, trimethylol octene, trimethylol decene, trimethylol dode , Trimethylol tridecene, trimethylol pentadecene, trimethylol hexadecene, trimetroleheptadecene, trimethylol octadecene, 1,2,6-butanetriol, 1,2,4-butanetriol, glycerin, etc. And the like; tetrafunctional or higher functional polyols such as pentaerythritol, dipentaerythritol, sorbitol, and xylitol; and aliphatic polyamines such as triethylenetetramine, diethylenetriamine, and triaminopropane. These bifunctional or more low molecular active hydrogen-containing compounds may be used alone 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., trifunctional isocyanate compounds are preferable, and trimethylolpropane adducts of tolylene diisocyanate and trimethylolpropane adducts of hexamethylene diisocyanate. More preferred are trimethylolpropane adduct of isophorone diisocyanate, trimethylolpropane adduct of xylylene diisocyanate, isocyanurate of tolylene diisocyanate, isocyanurate of hexamethylene diisocyanate, isocyanurate of isophorone diisocyanate. A trimethylol propane adduct of diisocyanate and a trimethylol propane adduct of xylylene diisocyanate Masui.

The amount of polyfunctional isocyanate compound (B) used in the present invention is as follows:
In the case of the pressure-sensitive adhesive for labels, the total of the isocyanate group in the polyfunctional isocyanate compound (B), the hydroxyl group and / or carboxyl group in the acrylic polymer (A), and the hydroxyl group in the compound (C) having a steroid skeleton The molar ratio (isocyanato group / hydroxyl group and carboxyl group) is preferably 0.05 to 1.5, more preferably 0.1 to 0.8. If it is 0.05 or more, sufficient cross-linking is formed, and high cohesive force and good adhesive force and heat resistance can be obtained. If it is 1.5 or less, excessive cohesion due to excessively high degree of cross-linking. The force can be suppressed, and good adhesion to the adherend can be obtained.
In the case of a pressure-sensitive adhesive for automobiles, an isocyanato group in the polyfunctional isocyanate compound (B), a hydroxyl group and / or a carboxyl group in the acrylic polymer (A), a hydroxyl group in the compound (C) having a steroid skeleton, and The ratio of the total number of moles of hydroxyl groups in the tackifier described later (isocyanato group / (hydroxyl group and / or carboxyl group)) is preferably 0.05 to 3.0, more preferably 0.3 to 2.0. 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 3.0 or less, the degree of crosslinking becomes 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 addition of a tackifier, a catalyst, an antioxidant, an ultraviolet absorber, a hydrolysis inhibitor, a fungicide, a thickener, a plasticizer, a filler, an antifoaming agent, and the like. An agent can be blended as necessary.

  Examples of tackifiers include terpene resins, aliphatic petroleum resins, aromatic petroleum resins, coumarone-indene resins, phenol resins, terpene-phenol resins, rosin derivatives (rosin, polymerized rosin, hydrogenated rosin, and glycerin thereof. All existing ones such as esters with 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 as long as it is a known one, and examples thereof include tertiary amines and organometallic compounds.
As the tertiary amine, for example, 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, and alkanolamine compounds, triethanolamine, triisopropanolamine, N-methyl Diethanolamine, N-ethyldiethanol Min, dimethyl ethanolamine.
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, and the like aqueous chelated organotitanium compounds such as titanium lactate.

  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 in order to improve 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, a woven fabric made of cotton, hemp, rayon, or a blend of polyester and cotton, hemp or rayon, leather, foam and the like. 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 copolymer, 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 foam, various plastic foams such as polyethylene foam, polypropylene foam, polyvinyl chloride foam, polyurethane foam, natural rubber foam, styrene-butadiene rubber foam, proloprene rubber foam, acrylonitrile-butadiene rubber foam Examples include various rubber foams such as bodies.

  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 in the case of a pressure-sensitive adhesive for labels, more preferably in the range of 1 μm to 50 μm. Is more preferably in the range of 10 μm to 90 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, Coating can be performed by 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, and pressure reduction is 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 to be 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, “parts” and “%” represent “parts by mass” and “mass%”, respectively.

<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 acid value (AV)>
1 g of a sample is accurately weighed in a stoppered Erlenmeyer flask, dissolved by adding 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution, and then added to a 0.1 N alcoholic potassium hydroxide solution. And titrated. The acid value (unit: mgKOH / g) was determined by the following formula. In addition, the acid value was made into the numerical value of the dried sample.
Acid value = {(5.61 × a × F) / S} / (Nonvolatile content concentration / 100)
S: Sample collection amount (g)
a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml)
F: Factor of 0.1N alcoholic potassium hydroxide solution

<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′-azobis (isobutyronitrile): 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%

<Tackifier>
S-100: Disproportionated rosin ester (Arakawa Chemical Industries, Ltd. product name: Superester S-100, hydroxyl value 5.0)
YS Polystar T100: Terpene phenol resin (manufactured by Yasuhara Chemical Co., Ltd .: product name YS Polystar T100)
KE-359: hydrogenated rosin ester (manufactured by Arakawa Chemical Industries, Ltd .: product name Pine Crystal KE-359, hydroxyl value 43.9)
D-125: Polymerized rosin ester (Arakawa Chemical Industries, Ltd. product name: Pencel D-125, hydroxyl value 32.5)

<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 ratio, and after the air in the reaction tank was replaced with nitrogen gas, the mixture was stirred under a nitrogen atmosphere under a nitrogen atmosphere. 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 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

<< Embodiment 1 (Label Adhesive) >>

In this specification, the examples of Embodiment 1 (adhesives for labels) are reference examples.
(Example 1-1)
<Manufacture of an adhesive composition>
For 100 parts of the acrylic polymer (A) obtained in Synthesis Example 1, 1.0 part of XDI-TMP is used as the polyfunctional isocyanate compound (B), and 2.0 parts of cholesterol is used as the compound (C) having a steroid skeleton. Further, 20 parts of S-100 as a tackifier were uniformly blended in terms of nonvolatile content to obtain a pressure-sensitive adhesive composition.

<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 1-2 to 1-12)
Except for changing the acrylic polymer (A), the polyfunctional isocyanate compound (B), the compound having a steroid skeleton (C), and the tackifier to those shown in Table 1, the same method as in Example 1-1 was used. The pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet were obtained, respectively.

(Comparative Examples 1-1 to 1-5)
Except that the acrylic polymer (A), the polyfunctional isocyanate compound (B), the compound having a steroid skeleton (C), and the tackifier were changed to those shown in Table 2, the same method as in Example 1-1 was used. The pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet were obtained, respectively.

<< Embodiment 2 (Automobile Adhesive) >>

In this specification, Examples 2-7 to 2-9 are reference examples.
(Example 2-1)
<Manufacture of an adhesive composition>
For 100 parts of the acrylic polymer (A) obtained in Synthesis Example 2, 7.3 parts of TDI-TMP as the polyfunctional isocyanate compound (B) and 3.0 parts of cholesterol as the compound (C) having a steroid skeleton As a tackifier, 10 parts of KE-359 and 15 parts of D-125 were blended in terms of nonvolatile content to obtain a pressure-sensitive adhesive composition.

<Manufacture of adhesive sheet>
The obtained pressure-sensitive adhesive composition has a thickness of 65 μm after drying with a comma coater on the release-treated surface of a 38 μm-thick polyethylene terephthalate peelable film substrate [“SP-PET 382050” manufactured by Lintec Corporation]. After coating at a speed of 2 m / min as described above, the coating 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 2-2 to 2-14)
Except that the acrylic polymer (A), the polyfunctional isocyanate compound (B), the compound having a steroid skeleton (C), and the tackifier were changed to those shown in Table 3, the same method as in Example 2-1. The pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet were obtained, respectively.

(Comparative Examples 2-1 to 2-4)
Except for changing the acrylic polymer (A), the polyfunctional isocyanate compound (B), the compound having a steroid skeleton (C), and the tackifier to those shown in Table 4, the same method as in Example 2-1. The pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet were obtained, respectively.

<Evaluation>
About the adhesive composition and adhesive sheet obtained by the said Example and comparative example, it evaluated by the following method. The results are shown in Tables 1-4.
<< Embodiment 1 (Label Adhesive) >>

(PP adhesive strength)
The adhesive strength was measured according to JIS Z 0237. The obtained pressure-sensitive adhesive sheet was cut to a width of 25 mm, and the peelable film substrate was peeled off and adhered to a polypropylene plate (“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 reciprocating once with a 2kg roll and leaving it to stand in the same environment for 24 hours, in that environment, using a tensile tester ("Tensilon" manufactured by Orientec Co., Ltd.), 180 degree direction at a pulling speed of 300mm / min The peel strength when peeled was measured.
Exceeding 14 N / 25 mm: Excellent in practical use.
10N-14N / 25mm: Practical range.
Less than 10 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 having a diameter of 10 mm in an environment of a temperature of 23 ° C. and a relative humidity of 50% (“Kobe Poly Sheet PP” manufactured by Yamasousha) ) After sticking and sticking to the rod of), the test piece end floats and peels off after being left in the same environment for 3 days, and the test piece end lifts and peels off after standing at a temperature of 80 ° C. for 1 day. Were measured and evaluated in three stages.
○: The test piece does not float or peel off, or the float is less than 1 mm. Excellent in practical use.
(Triangle | delta): A float is 1 mm-3 mm. Practical area.
X: The float exceeds 3 mm or the whole has peeled off. Not practical.

(Appearance of coating film)
About the adhesive sheet, the external appearance was observed visually and it evaluated based on the evaluation criteria of 3 steps | paragraphs.
○: Colorless and transparent. Excellent in practical use.
Δ: Slightly colored but transparent. Practical area.
X: It is cloudy or many agglomerates 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.

<< Embodiment 2 (Automobile Adhesive) >>

(PP adhesive strength)
The adhesive strength was measured according to JIS Z 0237. The obtained pressure-sensitive adhesive sheet was cut to a width of 25 mm, and the peelable film substrate was peeled off and adhered to a polypropylene plate (“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 reciprocating once with a 2 kg roll, after leaving for 24 hours in the same environment, in the same environment, using a tensile tester ("Tensilon" manufactured by Orientec Co., Ltd.), 180 degree direction at a pulling speed of 200 mm / min. The peel strength when peeled was measured.
Exceeding 13 N / 25 mm: Excellent in practical use 8 N to 13 N / 25 mm: Practical range Less than 8 N / 25 mm: Not practical

(Constant load peelability)
This will be described with reference to FIG. In an atmosphere of 23 ° C. (relative humidity 50%), the 80 mm long portion of the adhesive sheet (2) having a length of 100 mm and a width of 25 mm was replaced with a propylene plate (manufactured by Yamaso Co., Ltd. “ After being attached to Kobe poly sheet PP "), it was pressure-bonded twice with a 2 kg roll, and allowed to stand for 24 hours in an atmosphere of 23 ° C (relative humidity 50%). Thereafter, a 200 g weight (3) was attached to the non-sticking part of the pressure-sensitive adhesive sheet (2) in an atmosphere at 80 ° C., and a load was applied in a direction perpendicular to the surface of the adherend plate (1), and 24 hours passed. Later, the length of the pressure-sensitive adhesive sheet peeled off from the adherend was measured. When the length could not be measured due to complete peeling off, the time until dropping was measured. The length between A and B in FIG. 1 represents the peeled length. Those that do not fall are better than those that fall. Among those that do not fall, the shorter the peeled length, the better. Further, among those that have fallen, the longer the time it takes to drop, the better.

A: Start point side end portion of the adhesive sheet adhered to the adherend plate immediately after being attached to the adherend plate B: Start point of the adhesive sheet adhered to the adherend plate after the constant load peelability test Side end portion C: Length between end point side end portions AB of the pressure-sensitive adhesive sheet adhered to the adherend plate: Length between lengths AC where the pressure-sensitive adhesive sheet peeled off the adherend plate: Covered length Length (1): Adherent plate (2): Adhesive sheet (3): Weight immediately after adhering to the adherend plate

Claims (3)

A pressure-sensitive adhesive composition for automobile interior materials comprising an acrylic polymer (A), a polyfunctional isocyanate compound (B), and a compound (C) having a steroid skeleton,
The acrylic polymer (A) is an acrylic polymer having a hydroxyl group and / or a carboxyl group, and the compound (C) having a steroid skeleton is selected from a hydroxyl group, a hydroxyalkylcarbonyl group, a hydroxyalkylcarboxy group, and a hydroxyalkoxy group. The other substituents are alkyl groups, alkenyl groups, alkynyl groups, formyl groups, alkylcarbonyl groups, carboxyalkylcarbonyl groups, formate alkylcarbonyl groups, acetoxyalkylcarbonyl groups, alkylcarboxy groups, Carboxyalkylcarboxy group, formate alkylcarboxy group, acetoxyalkylcarboxy group, alkoxy group, carboxyalkoxy group, formate alkoxy group, acetoxyalkoxy group, benzoyloxy group, and below Equation [18] chosen group from (where the alkyl carboxy group, * - O-C (= O) a -R, * represents a bond), and acrylic polymer (A) 100 parts by mass of 0.1 to 20 parts by mass of the compound (C) having a steroid skeleton with respect to the pressure-sensitive adhesive composition for automobile interior materials .
Formula [18]

The pressure-sensitive adhesive composition for automobile interior materials according to claim 1, wherein the compound (C) having a steroid skeleton is a compound (C1-2) having a steroid skeleton having a secondary hydroxyl group. A pressure-sensitive adhesive sheet for automobile interior materials , wherein a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to claim 1 or 2 is laminated on at least one surface of a sheet-like substrate.