JP2023073503A - Solvent type pressure sensitive adhesive composition and pressure sensitive adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solvent type pressure sensitive adhesive composition which is excellent in pressure sensitive adhesive force and tackiness at low to normal temperatures (about -10 to 25°C) and also excellent in retention and processability at high temperatures (40°C or more).

SOLUTION: A solvent type pressure sensitive adhesive composition comprises a copolymer, a curative, a tackifier resin, and an organic solvent. The copolymer is a copolymer of a monomer mixture containing a (meth)acrylic ester monomer (A) whose alkyl group has 8-12 carbon atoms, and a monomer (B) having a carboxyl group. The tackifier resin contains a terpene resin. The content of the copolymer is 40 mass% or more in 100 mass% of a pressure sensitive adhesive layer produced by curing the solvent type pressure sensitive adhesive composition.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a solvent-type adhesive composition and an adhesive sheet.

A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition is used in a wide range of fields as a display label or a fixing tape because it is easier to handle than an adhesive. Adhesive sheets are often used as labels to indicate the contents of containers made of plastic, metal, etc. However, especially in low-temperature environments, there is a problem that the label may float or peel off from the adherend. rice field.

In Patent Document 1, one or more alkyl acrylates having an alkyl group having 1 to 14 carbon atoms containing 20% by mass or more of n-octyl acrylate and a functional monomer copolymerizable as a main component, in a solvent An acrylic solvent-based adhesive obtained by copolymerization is disclosed. However, the tackifier used in combination with the acrylic copolymer described in the Examples is a liquid rosin, which exhibits low-temperature tack but has the problem of insufficient workability.
Further, in Patent Document 2, in a pressure-sensitive adhesive composition containing 100 parts by mass of a (meth)acrylic copolymer and 5 to 30 parts by mass of a tackifying resin, the tackifying resin is (A) viscous at 20°C. It contains at least one tackifying resin that is a viscous body and (B) at least one tackifying resin that is solid at 20°C, and the content of the component (A) and the content of the component (B) are the same. A pressure sensitive adhesive composition is disclosed which is characterized by a weight ratio A/B of 0.1-9. However, there is a problem that sufficient tackiness is not exhibited in a low-temperature environment.

JP-A-10-67974 JP-A-08-283683

The problem to be solved by the present invention is a solvent-based adhesive that has excellent adhesive strength and tackiness at low temperatures to room temperature (about -10 to 25 ° C.) and excellent holding power and processability at high temperatures (40 ° C. or higher). It is to provide an adhesive composition.

The present inventors have made intensive studies to solve the above problems, and as a result, have found that the above objects can be achieved with the following solvent-based pressure-sensitive adhesive composition, and have completed the present invention.
That is, an embodiment of the present invention is a solvent-based pressure-sensitive adhesive composition comprising a copolymer, a curing agent, a tackifying resin, and an organic solvent, wherein the copolymer has an alkyl group with 8 to 12 carbon atoms. is a copolymer of a monomer mixture containing a (meth)acrylic acid ester monomer (A) and a monomer (B) having a carboxyl group, the tackifying resin contains a terpene resin, and the solvent-based pressure-sensitive adhesive composition is cured It is a solvent-type adhesive composition in which the content of the copolymer is 40% by mass or more in 100% by mass of the adhesive layer that is the product.

Further, in the present invention, the tackifying resin further comprises at least one tackifying resin selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, aliphatic/aromatic petroleum resins and rosin derivatives. It relates to the solvent-based pressure-sensitive adhesive composition containing.

The present invention also relates to the solvent-based pressure-sensitive adhesive composition, wherein the content of the terpene resin is 50% by mass or more in the total 100% by mass of the tackifying resin.

The present invention also relates to the solvent-based pressure-sensitive adhesive composition, wherein the terpene resin is a resin consisting only of terpene as a structural unit.

The present invention also relates to the solvent-based pressure-sensitive adhesive composition, wherein the organic solvent is a hydrocarbon solvent.

The present invention also relates to the solvent-based pressure-sensitive adhesive composition, wherein the monomer (B) having a carboxyl group contains 2-carboxyethyl (meth)acrylate.

The present invention also relates to the solvent-based pressure-sensitive adhesive composition, wherein the content of the 2-carboxyethyl (meth)acrylate is 50% by mass or more in the total 100% by mass of the monomer (B) having a carboxyl group. .

The present invention also relates to the solvent-based pressure-sensitive adhesive composition, wherein the monomer (B) having a carboxyl group contains (meth)acrylic acid and 2-carboxyethyl (meth)acrylate.

In the present invention, the monomer mixture further contains a (meth)acrylic acid ester monomer (C) having an alkyl group having 1 to 3 carbon atoms or a vinyl ester monomer (D) of a carboxylic acid having 1 to 3 carbon atoms. It relates to the solvent-based pressure-sensitive adhesive composition.

The present invention also relates to the solvent-based pressure-sensitive adhesive composition, which contains 80 to 97% by mass of a (meth)acrylic acid ester monomer (A) having an alkyl group having 8 to 12 carbon atoms in 100% by mass of the monomer mixture. .

The present invention also relates to a pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer that is a cured product of the solvent-based pressure-sensitive adhesive composition.

Further, an embodiment of the present invention is a pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer that is a cured product of the solvent-based pressure-sensitive adhesive composition.

ADVANTAGE OF THE INVENTION The present invention provides a solvent-based pressure-sensitive adhesive composition that is excellent in adhesive strength and tackiness at low temperature to normal temperature (approximately -10 to 25°C) and excellent in holding power and workability at high temperature (40°C or higher). It became possible.

Terms are defined prior to describing the present invention. As used herein, the term "adherend" refers to an object to which the pressure-sensitive adhesive sheet is attached. "Tape", "film" and "sheet" are synonymous. In addition, "(meth)acrylic acid ester monomer" represents an acrylic acid ester monomer and a methacrylic acid ester monomer, and may be simply described as a monomer. In this specification, unless otherwise specified, "molecular weight" means weight average molecular weight (Mw).

<<Solvent type adhesive composition>>
The solvent-based pressure-sensitive adhesive composition of the present invention is a solvent-based pressure-sensitive adhesive composition containing a copolymer, a curing agent, a tackifying resin, and an organic solvent, wherein the copolymer has an alkyl group having 8 carbon atoms. ~ 12 (meth) acrylic acid ester monomer (A), and a monomer having a carboxyl group (B
), the tackifying resin contains a terpene resin, and the content of the copolymer is 40 in 100% by mass of the adhesive layer that is a cured product of a solvent-based adhesive composition. % by mass or more.

<Copolymer>
The copolymer used in the present invention can be obtained by polymerizing a monomer mixture containing a (meth)acrylic acid ester monomer (A) having an alkyl group with 8 to 12 carbon atoms and a monomer (B) having a carboxyl group. can. Solution polymerization is preferable as the method for polymerizing the copolymer in terms of coexistence of adhesive strength, tackiness, workability and holding power in a low-temperature environment. The term "solution polymerization" as used herein includes polymerization methods such as ultraviolet polymerization and bulk polymerization in which the solvent does not contain water.

In the present invention, a copolymer of a monomer mixture containing a (meth)acrylic acid ester monomer (A) having an alkyl group with 8 to 12 carbon atoms and a monomer (B) having a carboxyl group, a curing agent, and a terpene resin are used in combination. As a result, we were able to achieve both adhesive strength and tackiness in a low temperature environment and workability and holding power in a heated environment. In general, pressure-sensitive adhesive sheets using a solvent-based pressure-sensitive adhesive composition containing an acrylic copolymer whose main component is a (meth)acrylic acid alkyl ester monomer have an alkyl group with a carbon number of A method of lowering the glass transition temperature of the copolymer by using a long monomer and a method of adding a tackifying resin are used.
However, the use of a monomer with a large alkyl group having a large number of carbon atoms results in insufficient cohesive force, resulting in deterioration of processability and the addition of a tackifying resin causes a problem of reduced tackiness. Therefore, in the present invention, a (meth)acrylic acid ester monomer (A) having an alkyl group with 8 to 12 carbon atoms and a monomer (B) having a carboxyl group are used in combination to suppress the deterioration of workability in a heating environment. , developed sufficient holding power. In addition, by selecting a terpene resin as the tackifying resin, it was possible to obtain good adhesion and tackiness even in a low-temperature environment.

[(Meth)acrylic acid ester monomer having an alkyl chain with 8 to 12 carbon atoms]
In the present invention, the (meth)acrylic acid ester monomer (A) having an alkyl chain with 8 to 12 carbon atoms can lower the glass transition temperature of the copolymer when the carbon number is in the range of 8 to 12. , Good adhesion and tackiness can be obtained in low temperature environments. Specific examples include octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. The structure of the alkyl group may have either a linear structure or a branched structure. Furthermore, among these, octyl (meth)acrylate, particularly octyl acrylate having a branched structure, is more preferable because of excellent adhesive strength and tackiness in a low-temperature environment. These monomers can be used alone or in combination of two or more.

The (meth)acrylic acid ester monomer (A) having an alkyl group having 8 to 12 carbon atoms preferably contains 70 to 97% by mass in 100% by mass of the monomer mixture used for copolymerization, and 80 to 97% by mass. is more preferred, and 90 to 97% by mass is particularly preferred. If it is 70% by mass or more, good adhesive strength and tackiness can be easily obtained in a low-temperature environment. If it is 97% by mass or less, workability and holding power in a heating environment will be good.

[Carboxyl group-containing monomer (B)]
The monomer (B) having a carboxyl group can obtain a copolymer having an excellent balance of adhesive strength, tackiness and workability by containing a carboxyl group.
Specifically, for example, (meth)acrylic acid, 2-carboxyethyl (meth)acrylate, 2-succinoyloxyethyl (meth)acrylate, maleic acid, monoethylmaleic acid, itaconic acid, citraconic acid, fumaric acid acid and the like. Furthermore, among these, (meth)acrylic acid and 2-carboxyethyl (meth)acrylate are preferable in terms of copolymerizability.
These monomers can be used alone or in combination of two or more, and 2-carboxyethyl (meth)acrylate is particularly preferred in view of tackiness.

The ratio of 2-carboxyethyl (meth)acrylate is preferably 50% by mass or more, more preferably 50 to 90% by mass, more preferably 100% by mass in total of the monomer (B) having a carboxyl group. is 60 to 90% by weight. By including 50% by mass or more, the adhesive strength and tackiness at low temperatures are improved.

The monomer (B) having a carboxyl group is contained in 100% by mass of the monomer mixture used for polymerization, preferably 0.5 to 10% by mass, more preferably 1 to 8% by mass, and further 1.5 to 6% by mass. 2 to 5% by weight is particularly preferred. If it is 0.5% by mass or more, sufficient workability and holding power can be obtained in a heated environment, and if it is 10% by mass or less, it is possible to maintain adhesive strength and tackiness in a low temperature environment.

[Alkyl group having 1 to 3 carbon atoms (meth) acrylic acid ester monomer (C)
and a vinyl ester monomer (D) of a carboxylic acid having 1 to 3 carbon atoms]
In the present invention, the (meth)acrylic acid ester monomer (C) having an alkyl group having 1 to 3 carbon atoms and the carboxylic acid vinyl ester monomer (D) having 1 to 3 carbon atoms have a carbon number in the range of 1 to 3. By being in, cohesion can be imparted to the copolymer, and good processability can be obtained in a heated environment.
Specifically, the (meth)acrylic acid ester monomer (C) having an alkyl group having 1 to 3 carbon atoms includes, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and the like. is mentioned. Examples of vinyl carboxylate monomers (D) having 1 to 3 carbon atoms include vinyl acetate, vinyl propionate and vinyl butyrate.
The structure of the alkyl group of the vinyl ester monomer (D) of a carboxylic acid having 1 to 3 carbon atoms may have either a linear structure or a branched structure. Furthermore, among these, methyl (meth)acrylate, ethyl (meth)acrylate, and vinyl acetate are more preferable because they can impart high cohesive strength.
These monomers can be used alone or in combination of two or more.

(Meth)acrylic acid ester monomer (C) having an alkyl group having 1 to 3 carbon atoms and carboxylic acid vinyl ester monomer (D) having 1 to 3 carbon atoms are included in 100% by mass of the monomer mixture used for copolymerization. , in total is preferably 1 to 40% by mass, more preferably 2 to 20% by mass, still more preferably 2 to 15% by mass, and particularly preferably 2 to 10% by mass. By containing 1% by mass or more, cohesive force can be imparted to the copolymer, and by containing 40% by mass or less, it is possible to maintain adhesive strength and tackiness in a low-temperature environment.

[Other monomers]
Other monomers can be used in the synthesis of the copolymer in the present invention. Other monomers include (meth)acrylic acid ester monomer (A) having an alkyl group with 8 to 12 carbon atoms, monomer (B) having a carboxyl group, and (meth)acrylic acid having an alkyl group with 1 to 3 carbon atoms. It refers to a copolymerizable monomer other than the ester monomer (C) or the vinyl ester monomer (D) of a carboxylic acid having 1 to 3 carbon atoms.

Specifically, a reactive functional group-containing monomer, a (meth)acrylic acid alkyl ester monomer having an alkyl group having 4 to 20 carbon atoms (however, a (meth)acrylic acid ester monomer having an alkyl group having 8 to 12 carbon atoms (A)), aromatic ring-containing monomers, alkoxy(poly)alkylene oxide-containing monomers and other vinyl monomers are preferred.
Examples of reactive functional group-containing monomers include hydroxyl group-containing monomers, amide bond-containing monomers,
Epoxy group-containing monomers, amino group-containing monomers, and the like are preferred.

Examples of the (meth)acrylic acid alkyl ester monomer having an alkyl group having 4 to 20 carbon atoms (excluding the (meth)acrylic acid ester monomer (A) having an alkyl group having 8 to 12 carbon atoms) include ( meth)butyl acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, stearyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, stearyl (meth)acrylate, (meth)acrylate ) and eicosyl acrylate.

A (meth)acrylic acid alkyl ester monomer having an alkyl group having 4 to 20 carbon atoms (excluding (meth)acrylic acid ester monomer (A) having an alkyl group having 8 to 12 carbon atoms) is a monomer mixture of 100 masses. %, preferably 1 to 15 parts by mass.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and (meth)acrylic acid. (Meth)acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acid, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and polyethylene glycol mono Glycol mono(meth)acrylates such as (meth)acrylates, polypropylene glycol mono(meth)acrylates, 1,4-cyclohexanedimethanol mono(meth)acrylates, caprolactone-modified (meth)acrylates , hydroxyethyl acrylamide, and the like. Among these, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred.

The hydroxyl group-containing monomer preferably contains 0.1 to 8% by mass, more preferably 0.2 to 6% by mass, based on 100% by mass of the monomer mixture. By containing 0.1 to 8% by mass, it becomes easy to adjust the crosslink density with the curing agent to an appropriate range.

Amide bond-containing monomers include (meth)acrylamide, N-methylacrylamide, N-isopropylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N,N-dimethylaminopropyl (meth)acrylamide, diacetone (meth)acrylamide compounds such as acrylamide, N-(hydroxymethyl)acrylamide, and N-(butoxymethyl)acrylamide; compounds containing heterocycles such as N-vinylpyrrolidone, N-vinylcaprolactam, and acryloylmorpholine; -vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide and the like.

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

Examples of amino group-containing monomers include (meth) acrylics such as monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, and monoethylaminopropyl (meth)acrylate. and acid monoalkylamino esters.

The amide bond-containing monomer, the epoxy group-containing monomer and the amino group-containing monomer are preferably contained in an amount of 0.1 to 15% by mass each in 100% by mass of the monomer mixture. The reactive functional group-containing monomer can be used alone or in combination of two or more.

Examples of aromatic ring-containing monomers include phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, ethylene oxide-modified nonylphenol (meth)acrylate, (meth) biphenyl acrylate, styrene, vinyltoluene, α-methylstyrene, and the like. The aromatic ring-containing monomer is preferably contained in an amount of 1 to 15% by mass in 100% by mass of the monomer mixture.

Alkoxy(poly)alkylene oxide-containing monomers include 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-phenoxyethyl acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylic acid. ester, methoxypolypropylene glycol (meth)acrylate, ethoxypolypropyleneglycol (meth)acrylate, phenoxypolyethyleneglycol (meth)acrylate, phenoxypolypropyleneglycol (meth)acrylate and the like. The alkoxy(poly)alkylene oxide-containing monomer is preferably contained in an amount of 1 to 15% by mass in 100% by mass of the monomer mixture.

Other vinyl monomers include styrene and acrylonitrile. Copolymerizable monomers other than these can be appropriately selected. Other vinyl monomers are preferably contained in an amount of 1 to 15% by mass in 100% by mass of the monomer mixture.

[Method for producing copolymer]
A copolymer can be produced by adding a polymerization initiator to a monomer mixture and appropriately selecting known production methods such as solution polymerization, bulk polymerization, and various radical polymerizations. Among these, solution polymerization is preferable because the weight average molecular weight of the copolymer can be easily adjusted.

Solvents that can be used in solution polymerization include methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, toluene, xylene, hexane, cyclohexane, methylcyclohexane, heptane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, propanol, and isopropanol. is preferred. These can be selected individually or in combination of two or more. The solvent preferably contains hydrocarbon solvents such as toluene, xylene, hexane, cyclohexane, methylcyclohexane, and heptane. Among hydrocarbon solvents, hydrocarbon solvents having no aromatic ring, such as hexane and heptane, are particularly preferred from the viewpoint of environmental regulations.

The hydrocarbon solvent is preferably contained in an amount of 10 to 200 parts by mass with respect to 100 parts by mass of the monomer mixture used for copolymerization. By including 10 to 200 parts by mass, the compatibility between the copolymer and the terpene resin can be improved.

In solution polymerization, it is preferable to use 0.001 to 1 part by mass of a polymerization initiator with respect to a total of 100 parts by mass of the monomer mixture. Generally, the polymerization reaction can be carried out at a temperature of about 50° C. to 90° C. for 6 hours to 20 hours under nitrogen stream. Moreover, the weight average molecular weight of the copolymer can be appropriately adjusted by using a chain transfer agent in the polymerization reaction.

In the present invention, the weight average molecular weight of the copolymer is preferably 200,000 to 1,200,000, more preferably 400,000 to 1,000,000, still more preferably 500,000 to 900,000, and particularly preferably 500,000 to 800,000. By setting the weight average molecular weight in the range of 200,000 to 1,200,000, it is possible to achieve a balance between adhesive physical properties and coatability.

Chain transfer agents are, for example, n-dodecylmercaptan, mercaptoisobutyl alcohol, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, glycidylmercaptan, α-methyl Styrene dimer, carbon tetrachloride, chloroform, hydroquinone and the like.

Polymerization initiators are generally azo compounds and organic peroxides. Azo compounds include, for example, 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(4-cyanovaleric acid), 2,2′-azobis(2-hydroxymethylpropionitrile), 2,2′-azobis(2-(2-imidazolin-2-yl)propane) etc.

Organic peroxides include, for example, benzoyl peroxide, t-butylperbenzoate, cumene hydroperoxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, di(2-ethoxyethyl)peroxydicarbonate, carbonate, t-butylperoxyneodecanoate, t-butylperoxybivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionylperoxide, diacetylperoxide and the like. These polymerization initiators can be used alone or in combination of two or more.

The content of the copolymer is 40% by mass or more in 100% by mass of the pressure-sensitive adhesive layer, which is a cured product of the solvent-based pressure-sensitive adhesive composition. Moreover, it is preferable that it is less than 100 mass %. The content of the copolymer is more preferably 60 to 99% by mass, particularly preferably 70 to 99% by mass. When the content is within this range, it is possible to exhibit better tackiness and workability and to obtain a transparent coating film, which is preferable.

<Curing agent>
In the present invention, the curing agent is preferably an isocyanate-based compound, an epoxy-based compound, an ethyleneimine-based compound, a metal chelate-based compound, an amine-based compound, etc., and an epoxy-based compound is particularly preferable from the viewpoint of workability in a heated environment.

Isocyanate compounds include, for example, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, Adducts, burettes or isocyanurates of isocyanate monomers such as polymethylene polyphenyl isocyanate and polyol compounds such as trimethylolpropane, and these isocyanate monomers and known polyether polyols or polyester polyols, acrylic polyols, polybutadiene polyols, poly Compounds having 3 or more isocyanate groups in the molecule such as adducts with isoprene polyol etc., tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate , isocyanate monomers such as tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, allophanate forms of hexamethylene diisocyanate (Coronate 2770: manufactured by Nippon Polyurethane Industry Co., Ltd.), etc. A compound having an isocyanate group and the like are included. Among them, a trimethylolpropane adduct of tolylene diisocyanate is preferable because the adhesive properties can be easily adjusted. In addition, the number of isocyanate groups is the average number.

Epoxy compounds include, for example, bisphenol A-epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether. , trimethylolpropane triglycidyl ether, diglycidylaniline, N,N,N′,N′-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N′-diglycidylaminomethyl)cyclohexane, N , N,N',N'-tetraglycidylaminophenylmethane and the like.

Ethyleneimine compounds include, for example, N,N'-diphenylmethane-4,4'-bis(1
-aziridine carboxysite), N,N'-toluene-2,4-bis(1-aziridine carboxysite), bisisophthaloyl-1-(2-methylaziridine), tri-1-aziridinylphosphine oxide, N,N'-hexamethylene-1,6-bis(1-aziridinecarboxysite), 2,2'-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate], trimethylolpropane tri-β- aziridinyl propionate, tetramethylolmethane tri-β-aziridinyl propionate, tris-2,4,6-(1-aziridinyl)-1,3,5-triazine and the like.

Examples of metal chelate compounds include coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium with acetylacetone or ethyl acetoacetate. be done.

Amine compounds include, for example, hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resins and methylene resins.
These curing agents can be used alone or in combination of two or more.

The curing agent preferably contains 0.005 to 15 parts by mass, more preferably 0.01 to 10 parts by mass, even more preferably 0.02 to 5 parts by mass, with respect to 100 parts by mass of the copolymer. 0.03 to 3 parts by weight is particularly preferred. When 0.005 to 15 parts by mass is included, it becomes easy to balance the cohesive strength and adhesive strength of the pressure-sensitive adhesive layer.

<Tackifying resin>
The solvent-based pressure-sensitive adhesive composition of the present invention contains a terpene resin as a tackifying resin.
Moreover, you may use together tackifying resins other than terpene resin. By including other tackifying resins, the adhesive force can be further improved.
When the tackifying resin is a terpene resin and other tackifying resins, the content of the terpene resin is preferably 50% by mass or more, more preferably 60 to 98% by mass, based on the total 100% by mass of the tackifying resin. , 70 to 98% by weight are particularly preferred. When the amount is 50% by mass or more, the adhesive strength to polyolefin at low temperature becomes better.
The pressure-sensitive adhesive composition of the present invention contains a terpene resin and other tackifying resins, so that it has excellent adhesion to highly polar polyolefins. Even polyethylene, for which it is difficult to increase the strength, is preferable because it has the effect of maintaining a high adhesive strength.

[Terpene resin]
By adding a terpene resin in the present invention, both adhesiveness and tackiness under a low temperature environment and workability under a heating environment can be achieved. A terpene resin means a tackifying resin having isoprene as a structural unit. From the viewpoint of tackiness, polyterpene, which has isoprene as a structural unit and is a resin composed only of terpene, is preferable. That is, terpene resins other than terpene resins having structural units other than terpene, such as aromatic modified terpene resins, terpene phenol resins, and hydrogenated terpene phenol resins, are preferred.

As terpene resins having structural units other than terpene, aromatic modified terpene resins, terpene phenol resins, and hydrogenated terpene phenol resins can be used. Specifically, terpene resins having only isoprene as a structural unit include, for example, YS Resin PX800, YS Resin PX1000, YS Resin PX1150 and YS Resin PX1250 manufactured by Yasuhara Chemical Co., Ltd.; and SYLVARES TR7125. Examples of aromatic modified terpene resins include YS Resin TO105 and YS Resin TO115 manufactured by Yasuhara Chemical Co., Ltd. Examples of terpene phenol resins include YS Polyster T100 and YS Polyster T115 manufactured by Yasuhara Chemical Co., Ltd. Examples include YS Polyster UH115 manufactured by Yasuhara Chemical Co., Ltd.

Further, the softening point of the terpene resin is more preferably within the range of 80 to 130°C. By adjusting the softening point to 80 to 130° C., it becomes easy to balance the cohesive force and the adhesive force of the adhesive layer in a low temperature environment and a heated environment.

The terpene resin preferably contains 2 to 50 parts by mass, more preferably 5 to 40 parts by mass, still more preferably 8 to 30 parts by mass, and particularly 10 to 28 parts by mass with respect to 100 parts by mass of the copolymer. preferable. When 2 to 50 parts by mass is contained, it becomes easy to balance the cohesive strength and adhesive strength of the pressure-sensitive adhesive layer. These can be selected individually or in combination of two or more.

[Other tackifying resins]
When the solvent-based pressure-sensitive adhesive composition of the present invention contains a tackifying resin in addition to the terpene resin, the pressure-sensitive adhesive strength can be further improved.
Other tackifying resins include, for example, aliphatic petroleum resins, aromatic petroleum resins, coumarone-indene resins, phenolic resins, rosin derivatives (rosin, polymerized rosin, hydrogenated rosin, and their glycerin, pentaerythritol, etc.). All existing materials such as esters, resin acid dimers, etc.) and acrylic resins can be used.
These can be used alone or in combination of two or more.

From the viewpoint of adhesion to non-polar adherends that are generally difficult to adhere such as polypropylene (PP) and polyethylene (PE), other tackifying resins include aliphatic petroleum resins, aromatic At least one tackifying resin selected from the group consisting of petroleum resins, aliphatic/aromatic petroleum resins and rosin derivatives is preferred.
More preferred are aliphatic petroleum resins, aromatic petroleum resins, and rosin derivatives.

Quinton B170 manufactured by Nippon Zeon Co., Ltd. as the aliphatic petroleum resin, Nisseki Neopolymer L-90 manufactured by JXTG (manufactured by JXTG) as the aromatic petroleum resin, and the aliphatic/aromatic petroleum resin as Examples of FTR6100 manufactured by Mitsui Chemicals, Inc., and rosin derivatives include Sylvatac RE85 manufactured by Arizona Chemical Co., Ltd., Super Ester A-75 manufactured by Arakawa Chemical Industries, Ltd., and the like.

Other tackifying resins are preferably added in an amount of 1 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the copolymer. Good adhesion to PP can be obtained by including 1 to 10 parts by mass.

<Organic solvent>
The solvent-based pressure-sensitive adhesive composition of the invention contains an organic solvent.
The organic solvent may be a reaction solvent for solution polymerization of the copolymer, a diluting solvent after copolymer synthesis, or may be added before coating the pressure-sensitive adhesive composition.

As the organic solvent, those described in the production method of the copolymer can be used.
In addition, before applying the solvent-type pressure-sensitive adhesive composition, for example, hydrocarbon solvents such as toluene, xylene, hexane, and heptane; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone and methyl ethyl ketone. Halogenated hydrocarbon solvents such as dichloromethane and chloroform; Diethyl ether, methoxytoluene, organic solvents such as ether solvents such as dioxane can also be added to adjust the viscosity, and these organic solvents can be used alone or Two or more types may be used.
Among them, it is preferable to contain a hydrocarbon-based solvent.
By including a hydrocarbon-based solvent in the pressure-sensitive adhesive composition, the compatibility of the terpene resin in solution is improved, and excellent stability over time can be exhibited over a wide temperature range. Among hydrocarbon-based solvents, hydrocarbon-based solvents having no aromatic ring, such as hexane and heptane, are particularly preferred from the viewpoint of environmental regulations.

The organic solvent preferably contains 10 to 500 parts by weight, more preferably 50 to 300 parts by weight, based on 100 parts by weight of the copolymer. Within this range, the handleability during synthesis and coating is superior.

<Silane coupling agent>
The solvent-based pressure-sensitive adhesive composition of the present invention may further contain a silane coupling agent. Silane coupling agents include, for example, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyltripropoxysilane, 3-(meth)acryloxysilane alkoxysilane compounds having a (meth)acryloxy group, such as roxypropyltributoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane;
alkoxysilane compounds having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane;
3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)- 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl) Alkoxysilane compounds having an amino group such as 3-aminopropylmethyldiethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercapto Alkoxysilane compounds having a mercapto group such as propyltripropoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane;
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropylmethyldimethoxysilane, Alkoxysilane compounds having an epoxy group such as 3-glycidoxypropylmethyldiethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane;
Tetraalkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane;
3-chloropropyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, styryltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyl Examples include triethoxysilane, hexamethyldisilazane, and silicone resins having alkoxysilyl groups in the molecule.

<Other ingredients>
The solvent-based pressure-sensitive adhesive composition of the present invention contains various resins, curing catalysts, oils, softening agents, dyes, pigments, antioxidants, ultraviolet absorbers, weather-resistant agents, and other optional components as long as the effects of the present invention are not impaired. Agents, plasticizers, fillers, anti-aging agents, antistatic agents, and the like may be added.

The solvent-based pressure-sensitive adhesive composition of the present invention is suitable for affixing non-polar adherends, as well as general labels and stickers, adhesive optical films, paints, elastic wall materials, waterproof coating materials, flooring materials, Laminated structures, sealing agents, molding materials, coating agents for surface modification, binders (magnetic recording media, ink binders, casting binders, fired brick binders, graft materials, microcapsules, glass fiber sizing, etc.), urethane foams (hard , semi-rigid, soft), urethane RIM, UV/EB curing resin, high solid paint, thermosetting elastomer, microcellular, fiber processing agent, plasticizer, sound absorbing material, damping material, surfactant, gel coating agent, artificial Marble resins, impact resistance agents for artificial marble, ink resins, films (laminating adhesives, protective films, etc.), resins for laminated glass, reactive diluents, various molding materials, elastic fibers, artificial leather, synthetic leather etc., and also as various resin additives and their raw materials.

≪Adhesive sheet≫
The pressure-sensitive adhesive sheet of the present invention preferably comprises a substrate and a pressure-sensitive adhesive layer formed from the solvent-based pressure-sensitive adhesive composition of the present invention. As another aspect, a double-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive layers on both sides of a core material, or a cast pressure-sensitive adhesive sheet having only a pressure-sensitive adhesive layer without a base material and a core material is also preferable. The pressure-sensitive adhesive layer can be formed by applying a pressure-sensitive adhesive onto a substrate and drying it. Alternatively, it can be formed by coating a release sheet with an adhesive, drying it to form an adhesive layer, and then laminating a substrate. Needless to say, a release sheet is attached to the surface of the pressure-sensitive adhesive layer that does not come into contact with the substrate.

Preferred substrates include, for example, cellophane, plastic, rubber, foam, fabric, rubberized fabric, resin-impregnated fabric, glass, and wood. The shape of the base material can be selected from a plate shape and a film shape, but a film is preferable because it is easy to handle. A single substrate or a laminate of two or more substrates can be used.

Plastics include, for example, polyvinyl alcohol, triacetyl cellulose, polypropylene, polyethylene, polycycloolefin, polyolefins such as ethylene-vinyl acetate copolymer, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polycarbonate, polynorbornene, Polyarylate, polyacryl, polyphenylene sulfide, polystyrene, polyamide, polyimide film, epoxy, and the like.

The method of applying the solvent-based pressure-sensitive adhesive composition is not particularly limited, and Meyer bar, applicator, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, knife coater, reverse coater, spin coater, etc. is mentioned. There are no particular restrictions on the drying method, and examples include hot air drying, infrared rays, and depressurization. As the drying conditions, hot air heating at about 60 to 160° C. can be usually performed depending on the type of curing agent, the thickness of the pressure-sensitive adhesive layer, or the type of solvent.

The thickness of the adhesive layer is preferably 0.1-300 μm, more preferably 1-100 μm. When the thickness is in the range of 0.1 to 300 μm, the adhesive physical properties can be adjusted to an appropriate range.

The pressure-sensitive adhesive sheet of the present invention can be used in various applications regardless of adherends, from high polarity to low polarity, such as plastics such as polyolefins, glass, cardboard, and metals. Specifically, it can be preferably used for labeling foodstuffs stored in a frozen or refrigerated environment or for labels used in cold districts.

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

(Synthesis example 1)
In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen introduction tube (hereinafter simply referred to as "reaction vessel"), under a nitrogen atmosphere, 90.4 parts of 2-ethylhexyl acrylate, acrylic 1.2 parts of acid, 2.4 parts of 2-carboxyethyl acrylate, 6 parts of methyl acrylate, 60 parts of ethyl acetate, 2,2'-azobisisobutyronitrile (hereinafter referred to as "AIBN") 0 .03 parts were charged. The mixture was heated while stirring, and after confirming the initiation of the polymerization reaction, the reaction was carried out at the reflux temperature for 2 hours. Then, 0.03 part of AIBN was added to the reaction solution and the reaction was continued for 6 hours. After that, the reactor was cooled and 25 parts of ethyl acetate and 25 parts of hexane were added to obtain a copolymer 1 solution having a weight average molecular weight of 870,000.

(Synthesis Examples 2 to 21)
Copolymers 2 to 21 solutions of Synthesis Examples 2 to 21 were obtained in the same manner as in Synthesis Example 1 except that the types and blending amounts of the monomers were as described in Table 1. The weight average molecular weight of the obtained copolymer solution was determined according to the following method. Table 1 shows the results.

(Synthesis Examples 22-25)
Solutions of copolymers 2 to 25 of Synthesis Examples 22 to 25 were obtained in the same manner as in Synthesis Example 1 except that the types and blending amounts of the monomers were as described in Table 2. The weight average molecular weight of the obtained copolymer solution was determined according to the following method. Table 2 shows the results.

In the table, "β-CEA/(B)" is the content (% by mass) of β-CEA (2-carboxyethyl acrylate) in 100% by mass of the monomer (B) having a carboxyl group.
"(A)/copolymer" is the content (% by mass) of (meth)acrylate monomer (A) having an alkyl group with 8 to 12 carbon atoms in 100% by mass of the monomer mixture.

<Measurement of weight average molecular weight>
A GPC "LC-GPC system" manufactured by Shimadzu Corporation was used to measure the weight average molecular weight (Mw). GPC is liquid chromatography for separating and quantifying a substance dissolved in a solvent (THF; tetrahydrofuran) based on the difference in molecular size, and the weight average molecular weight was determined in terms of polystyrene.
Apparatus name: Shimadzu Corporation, LC-GPC system "Prominence"
Column: 4 GMHXL manufactured by Tosoh Corporation and 1 HXL-H manufactured by Tosoh Corporation were connected in series.
Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 ml/min Column temperature: 40°C

Abbreviations in Tables 1 and 2 are listed below.
2EHA: 2-ethylhexyl acrylate 2EHMA: 2-ethylhexyl methacrylate LMA: lauryl methacrylate MA: methyl acrylate MMA: methyl methacrylate EA: ethyl acrylate AA: acrylic acid HEA: 2-hydroxyethyl acrylate β-CEA: 2-carboxyethyl acrylate BA: butyl acrylate VAc: vinyl acetate

(Example 1)
For 100 parts of the copolymer in the copolymer solution obtained in Synthesis Example 1, TETRAD-X (N,N,N',N'-tetraglycidyl-m-xylylenediamine, Mitsubishi Gas Kagaku Co., Ltd.) 0.03 parts (nonvolatile content conversion), YS resin PX1250 (Yasuhara Chemical Co., Ltd.) 10 parts (nonvolatile content conversion) as a terpene resin, Sylvatac RE85 (Arizona Chemical Co.) 5 parts as a rosin derivative (in terms of non-volatile content) was blended, and hexane was added as a solvent to adjust the non-volatile content to 35% to obtain an adhesive solution.
The pressure-sensitive adhesive solution is coated on a release sheet (made of polyethylene terephthalate (PET)) with a thickness of 38 μm with a comma coater so that the thickness after drying is 50 μm, and dried at 100 ° C. for 2 minutes. to form an adhesive layer. Next, a 50 μm thick base material (made of polyethylene terephthalate, hereinafter referred to as a PET sheet) is attached to this adhesive layer, and aged for 1 week at a temperature of 23° C. and a relative humidity of 50% to form a “releasable sheet/ An adhesive sheet having a structure of "adhesive layer/PET sheet" was obtained.

(Examples 2 to 39, Comparative Examples 1 to 4)
Adhesive solutions and adhesive sheets of Examples 2 to 39 and Comparative Examples 1 to 4 were obtained in the same manner as in Example 1 except that the materials and formulations were changed to those shown in Table 3.
However, Examples 15 to 39 are reference examples.

(Examples 40-58)
Adhesive solutions and adhesive sheets of Examples 40 to 58 were obtained in the same manner as in Example 1, except that the materials and formulations were changed to those shown in Table 4.

In the table, "terpene resin / tackifying resin" is the content (% by mass) of the terpene resin in the total 100% by mass of the tackifying resin, and "copolymer / adhesive layer" is the adhesive. It is the content (% by mass) of the copolymer in 100% by mass of the layer.

Abbreviations in Tables 3 and 4 are listed below.
TETRAD-X: N,N,N',N'-tetraglycidyl-m-xylylenediamine (manufactured by Mitsubishi Gas Chemical Company, Inc.)
TDI/TMP: Trimethylolpropane adduct of tolylene diisocyanate PZ-33: 2,2'-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate] (manufactured by Nippon Shokubai Co., Ltd.)
PX1250: Resin having isoprene as a structural unit and consisting only of terpene (manufactured by Yasuhara Chemical Co., Ltd.)
PX800: A resin having isoprene as a structural unit and consisting only of terpene (manufactured by Yasuhara Chemical Co., Ltd.)
TO125: aromatic modified terpene resin (manufactured by Yasuhara Chemical Co., Ltd.)
RE85: Rosin derivative (manufactured by Arizona Chemical Co.)
FTR6100: Aliphatic/aromatic petroleum resin (manufactured by Mitsui Chemicals, Inc.)

The pressure-sensitive adhesive sheets obtained were evaluated by the following methods. Tables 3 and 4 show the results.
(1) Adhesive strength The obtained adhesive sheet was prepared in a size of 25 mm in width and 150 mm in length. At 5 ° C. or 23 ° C., in an atmosphere of 50% relative humidity, peel off the release sheet from the adhesive sheet and paste it on a stainless steel (SUS) plate. Adhesion was measured in a 180° peel test in which the film was peeled off at a speed of 300 mm/min in the direction of degrees. Adhesion to a polypropylene (PP) plate and a polyethylene (PE) plate was measured in the same manner as above.

Evaluation standard SUS (23°C)
A: "Adhesive strength is 36 N/25 mm or more. Very good."
○: "Adhesive strength is 30 N/25 mm or more and less than 36 N/25 mm. Good."
△: "Adhesive strength is 24 N/25 mm or more and less than 30 N/25 mm. Practical level."
x: "Adhesive strength is less than 24 N/25 mm. Not practical."
SUS (5°C)
A: "Adhesive strength is 16 N/25 mm or more. Very good."
○: "Adhesive strength is 13 N/25 mm or more and less than 16 N/25 mm. Good."
△: "Adhesive strength is 10 N/25 mm or more and less than 13 N/25 mm. Practical level."
×: "Adhesive strength is less than 10 N/25 mm. Not practical."
PP (23°C)
A: "Adhesive strength is 17 N/25 mm or more. Very good."
○: "Adhesive strength is 14 N/25 mm or more and less than 17 N/25 mm. Good."
△: "Adhesive strength is 11 N/25 mm or more and less than 14 N/25 mm. Practical level."
×: "Adhesive strength is less than 11 N/25 mm. Not practical."
PP (5°C)
A: "Adhesive strength is 16 N/25 mm or more. Very good."
○: "Adhesive strength is 13 N/25 mm or more and less than 16 N/25 mm. Good."
△: "Adhesive strength is 10 N/25 mm or more and less than 13 N/25 mm. Practical level."
×: "Adhesive strength is less than 10 N/25 mm. Not practical."
PE (23°C)
A: "Adhesive strength is 9 N/25 mm or more. Very good."
○: "Adhesive strength is 7 N/25 mm or more and less than 9 N/25 mm. Good."
△: "Adhesive strength is 5 N/25 mm or more and less than 7 N/25 mm. Practical level."
×: "Adhesive strength is less than 5 N/25 mm. Not practical."
PE (5°C)
A: "Adhesive strength is 8 N/25 mm or more. Very good."
○: "Adhesive strength is 6 N/25 mm or more and less than 8 N/25 mm. Good."
△: "Adhesive strength is 4 N/25 mm or more and less than 6 N/25 mm. Practical level."
×: "Adhesive strength is less than 4 N/25 mm. Not practical."

(2) Holding power The obtained pressure-sensitive adhesive sheet was prepared in a size of 25 mm in width and 150 mm in length. After removing the release sheet from the adhesive sheet and polishing, a pressure-sensitive adhesive layer was attached to the lower end portion of a stainless steel plate with a width of 30 mm and a length of 150 mm and a width of 25 mm and a width of 25 mm. A load of 1 kg was applied at , and the holding force was measured by leaving it for 70,000 seconds. For evaluation, the length by which the upper end of the adhesive sheet pasting surface shifted downward was measured.

Evaluation Criteria ⊚: "No shift was observed. Very good."
◯: "Deviation occurs and the length of deviation is less than 2 mm. Good."
△: "The shift length is 2 mm or more and less than 5 mm. Practical level."
x: "The deviation length is 5 mm or more. Not practical."

(3) Ball tack The obtained adhesive sheet was prepared in a size of 25 mm in width and 250 mm in length. The release sheet was peeled off from the adhesive sheet and fixed to an inclined plate having an inclination angle of 30 degrees with the adhesive surface facing up. A steel ball (1/32 to 32/32 inch) is rolled on the sample with a PET film for the runway pasted on the top, and the runway 10cm and the glue surface 10cm, and the diameter number of the ball that stops near the center of the glue surface. Recorded. The measurements were carried out at 5°C or 23°C and a relative humidity of 50%.

Evaluation criteria in an atmosphere of 5°C ◎: "Ball diameter is 10 or more. Very good."
○: "Ball diameter is 7 to 9. Good."
△: "Ball diameter is 4 to 6. Practical level."
×: "The ball diameter is 3 or less. Not practical."
Evaluation criteria under atmosphere of 23°C and relative humidity of 50% ◎: "Ball diameter is 19 or more. Very good."
○: "Ball diameter is 15 to 18. Good."
△: "Ball diameter is 11 to 14. Practical level."
x: "The ball diameter is 10 or less. Not practical."

(4) Workability Test The obtained pressure-sensitive adhesive sheet was prepared in a size of 10 mm in width and 10 mm in length. The release sheet was peeled off from the adhesive sheet, sandwiched between release sheets (made of polyethylene terephthalate) with a thickness of 38 μm, and a pressure of 50 kg/cm ² was applied in a 40° C. environment using a press tester for 2 hours. I left it. After the test was completed, the sample was taken out and the width (maximum value) of the paste protruding from the edge of the test piece was measured.

Evaluation Criteria ⊚: "Extension of 0 or more and less than 0.4 mm. Very good."
◯: "The protrusion is 0.4 or more and less than 0.6 mm. Good."
△: "Protrusion is 0.6 or more and less than 0.8 mm. Practical level."
x: "Protrusion is 0.8 mm or more. Not practical."

(4) Appearance of coating film The pressure-sensitive adhesive sheet obtained was attached to a slide glass and measured with a haze meter (NDH 5000 manufactured by Nippon Denshoku Industries Co., Ltd.).

Evaluation Criteria A: "Haze is less than 7. Very good."
○: "Haze is 7 or more and less than 11. Good."
△: "Haze is 11 or more and less than 15. Practical level."
x: "Haze is 15 or more. Not practical."

As shown in Examples in Tables 3 and 4, the solvent-based pressure-sensitive adhesive composition of the present invention has excellent adhesive strength under low-temperature and normal-temperature environments, ball tack, holding power under high temperatures, workability, and coating film appearance. It turned out to be excellent. On the other hand, in the comparative example, one of the items was defective, and it became clear that the practical use was impossible.

Claims (11)

A solvent-based adhesive composition comprising a copolymer, a curing agent, a tackifying resin, and an organic solvent,
The copolymer is a copolymer of a monomer mixture containing a (meth)acrylic acid ester monomer (A) having an alkyl group with 8 to 12 carbon atoms and a monomer (B) having a carboxyl group,
the tackifying resin comprises a terpene resin;
A solvent-based pressure-sensitive adhesive composition, wherein the content of the copolymer is 40% by mass or more in 100% by mass of the pressure-sensitive adhesive layer, which is a cured product of the solvent-based pressure-sensitive adhesive composition. Claim 1, wherein the tackifying resin further comprises at least one tackifying resin selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, aliphatic/aromatic petroleum resins and rosin derivatives. The solvent-based pressure-sensitive adhesive composition described. The solvent-based pressure-sensitive adhesive composition according to claim 1 or 2, wherein the content of said terpene resin is 50% by mass or more in a total of 100% by mass of said tackifying resin. The solvent-based pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the terpene resin is a resin consisting only of terpene as a structural unit. The solvent-based pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the organic solvent is a hydrocarbon solvent. The solvent-based pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the monomer (B) having a carboxyl group comprises 2-carboxyethyl (meth)acrylate. The content of the 2-carboxyethyl (meth)acrylate is 50% by mass or more in the total 100% by mass of the monomer (B) having a carboxyl group, the solvent-based solvent-based according to any one of claims 1 to 6. Adhesive composition. 8. The solvent-based pressure-sensitive adhesive composition according to any one of claims 1 to 7, wherein the monomer (B) having a carboxyl group comprises (meth)acrylic acid and 2-carboxyethyl (meth)acrylate. Claims 1 to 3, wherein the monomer mixture further comprises a (meth)acrylic acid ester monomer (C) having an alkyl group having 1 to 3 carbon atoms or a carboxylic acid vinyl ester monomer (D) having 1 to 3 carbon atoms. 8. The solvent-based pressure-sensitive adhesive composition according to any one of items 8. The solvent type according to any one of claims 1 to 9, wherein the monomer mixture contains 80 to 97 mass% of (meth)acrylic acid ester monomer (A) having 8 to 12 carbon atoms in the alkyl group in 100 mass% of the monomer mixture. Adhesive composition. A pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer that is a cured product of the solvent-based pressure-sensitive adhesive composition according to any one of claims 1 to 10.