JP6614383B1 - Solvent type adhesive composition and adhesive sheet - Google Patents

Abstract

The present invention provides a solvent-type pressure-sensitive adhesive composition having excellent adhesive strength and tackiness at low to normal temperatures (about -10 to 25 ° C) and excellent holding power and workability at high temperatures (40 ° C or higher). thing. A solvent-type pressure-sensitive adhesive composition comprising a copolymer, a curing agent, a tackifier resin, and an organic solvent, wherein the copolymer is a (meth) acrylic having an alkyl group having 8 to 12 carbon atoms. A pressure-sensitive adhesive which is a copolymer of a monomer mixture containing an acid ester monomer (A) and a monomer (B) having a carboxyl group, wherein the tackifying resin contains a terpene resin and is a cured product of a solvent-type pressure-sensitive adhesive composition This is solved by a solvent-type pressure-sensitive adhesive composition in which the content of the copolymer is 40% by mass or more in 100% by mass of the layer. [Selection figure] None

Description

  The present invention relates to a solvent-type pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet.

  A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition is easier to handle than an adhesive, and is therefore used in a wide range of fields as a display label and a fixing tape. Adhesive sheets are often used as labels to display the contents of containers such as plastic and metal, but there is a problem that the labels may float or peel off from the adherend, especially when the usage environment is low. It was.

Patent Document 1 mainly contains a functional monomer copolymerizable with one or more alkyl acrylates having 1 to 14 carbon atoms containing 20% by mass or more of n-octyl acrylate, and in a solvent. An acrylic solvent-type pressure-sensitive 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 causes a problem that the low temperature tack is developed but the processability is insufficient.
Patent Document 2 discloses that in a pressure-sensitive adhesive composition containing 100 parts by weight of a (meth) acrylic copolymer and 5 to 30 parts by weight of a tackifier resin, the tackifier resin is (A) viscous at 20 ° C. Containing at least one kind of tackifying resin that is a solid and (B) at least one kind of tackifying resin that is solid at 20 ° C., and the content of the component (A) and the content of the component (B) A pressure-sensitive adhesive composition having a mass ratio A / B of 0.1 to 9 is disclosed. However, there is a problem that tackiness does not sufficiently develop in a low temperature environment.

JP-A-10-67974 Japanese Patent Laid-Open No. 08-283683

  The problem to be solved by the present invention is a solvent type that is excellent in adhesion and tack at low temperature to normal temperature (about -10 to 25 ° C.) and excellent in holding power and workability at high temperature (40 ° C. or higher). It is to provide an adhesive composition.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above object can be achieved by the solvent-based pressure-sensitive adhesive composition shown below, and have completed the present invention.
That is, an embodiment of the present invention is a solvent-type pressure-sensitive adhesive composition containing a copolymer, a curing agent, a tackifier resin, and an organic solvent, wherein the copolymer has an alkyl group having 8 to 12 carbon atoms. (Meth) acrylic acid ester monomer (A) and a monomer mixture copolymer containing a carboxyl group-containing monomer (B), and the tackifying resin contains a terpene resin, and curing of the solvent-type pressure-sensitive adhesive composition It is a solvent-type adhesive composition whose content of the said copolymer is 40 mass% or more in the adhesive layer 100 mass% which is a thing.

  In the present invention, the tackifier resin may further comprise at least one tackifier resin selected from the group consisting of aliphatic petroleum resins, aromatic petroleum trees, aliphatic / aromatic petroleum resins, and rosin derivatives. It contains the said solvent-type adhesive composition containing.

  Moreover, this invention relates to the said solvent-type adhesive composition whose content of the said terpene resin is 50 mass% or more in the total 100 mass% of the said tackifying resin.

  Moreover, this invention relates to the said solvent-type adhesive composition whose said terpene resin is resin which consists only of terpene as a structural unit.

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

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

  The present invention also relates to the solvent-type 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 includes a (meth) acrylic acid ester monomer (C) having 1 to 3 carbon atoms of an alkyl group or a vinyl ester monomer (D) of a carboxylic acid having 1 to 3 carbon atoms. It is related with the said solvent-type adhesive composition.

  Moreover, this invention relates to the said solvent-type adhesive composition which contains 80-97 mass% of (meth) acrylic acid ester monomers (A) whose carbon number of the said alkyl group is 8-12 in 100 mass% of said monomer mixtures. .

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

  Moreover, the embodiment of this invention is an adhesive sheet provided with the adhesive layer which is a base material and the hardened | cured material of the said solvent-type adhesive composition.

  According to the present invention, a solvent-type pressure-sensitive adhesive composition having excellent adhesive strength and tackiness at low to normal temperatures (about −10 to 25 ° C.) and excellent holding power and workability at high temperatures (over 40 ° C.) is provided. I was able to do that.

  Terms will be defined before the description of the present invention. In this specification, the “adherent” refers to an object to which an adhesive sheet is attached. “Tape”, “film”, and “sheet” are synonymous. The “(meth) acrylic acid ester monomer” represents an acrylic acid ester monomer and a methacrylic acid ester monomer, and may be simply referred to as a monomer. In the present specification, unless otherwise specified, “molecular weight” means weight average molecular weight (Mw).

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

<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 8 to 12 carbon atoms in the alkyl group and a monomer (B) having a carboxyl group. it can. As a polymerization method of the copolymer, solution polymerization is preferable from the viewpoint of coexistence of adhesive strength in a low temperature environment, tackiness, workability, and holding power. In this specification, the solution polymerization includes a polymerization method in which water is not contained in a solvent such as ultraviolet polymerization or bulk polymerization.

In the present invention, a copolymer of a monomer mixture containing a (meth) acrylic acid ester monomer (A) having 8 to 12 carbon atoms in an alkyl group and a monomer (B) having a carboxyl group, a curing agent, and a terpene resin are used in combination. As a result, it was possible to achieve both cohesion and tackiness in a low-temperature environment, workability in a heating environment, and retention. In general, a pressure-sensitive adhesive sheet using a solvent-type pressure-sensitive adhesive composition containing an acrylic copolymer mainly composed of a (meth) acrylic acid alkyl ester monomer has a carbon number of an alkyl group in order to impart adhesive strength under a low temperature environment. By using a long monomer, a technique for lowering the glass transition temperature of the copolymer and a technique for adding a tackifying resin are used.
However, the use of a monomer having a long alkyl carbon number results in insufficient cohesive force, and the problem of deterioration in processability and the addition of a tackifier resin results in a problem that tackiness is lowered. Therefore, in the present invention, the deterioration of workability in a heating environment is suppressed by using together a (meth) acrylic acid ester monomer (A) having 8 to 12 carbon atoms in the alkyl group and a monomer (B) having a carboxyl group. Sufficient holding power was expressed. Moreover, by selecting a terpene resin as the tackifier resin, it was possible to obtain good adhesive force and tackiness even in a low temperature environment.

[(Meth) acrylic acid ester monomer having 8 to 12 carbon atoms in alkyl chain]
In the present invention, the (meth) acrylic acid ester monomer (A) having 8 to 12 carbon atoms in the alkyl chain can lower the glass transition temperature of the copolymer because it is in the range of 8 to 12 carbon atoms. Good adhesive strength and tackiness can be obtained in a low temperature environment. Specific examples include octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, and the like. 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 its 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 8 to 12 carbon atoms in the alkyl group preferably contains 70 to 97% by mass, and 80 to 97% by mass in 100% by mass of the monomer mixture used for copolymerization. Is more preferable, and 90 to 97% by mass is particularly preferable. If it is 70 mass% or more, good adhesive force and tackiness can be easily obtained in a low temperature environment. If it is 97 mass% or less, the workability and holding force in a heating environment will become favorable.

[Monomer having carboxyl group (B)]
When the monomer (B) having a carboxyl group contains a carboxyl group, a copolymer having an excellent balance of adhesive strength, tackiness, and processability can be obtained.
Specifically, for example, (meth) acrylic acid, 2-carboxyethyl (meth) acrylate, 2-succinoyloxyethyl (meth) acrylate, maleic acid, monoethylmaleic acid, itaconic acid, citraconic acid, fumarate An acid etc. are mentioned. Of these, (meth) acrylic acid and 2-carboxyethyl (meth) acrylate are preferred from the viewpoint of copolymerization.
These monomers can be used alone or in combination of two or more, and it is particularly preferable from the viewpoint of tackiness to contain 2-carboxyethyl (meth) acrylate.

  The ratio of 2-carboxyethyl (meth) acrylate is preferably 50% by mass or more, more preferably 50 to 90% by mass, and even more preferably, in a total of 100% by mass 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 tack at a low temperature become better.

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

[(Meth) acrylic acid ester monomer (C) having 1 to 3 carbon atoms of alkyl group
And vinyl ester monomer (D) of carboxylic acid having 1 to 3 carbon atoms]
In the present invention, the (meth) acrylic acid ester monomer (C) having 1 to 3 carbon atoms of the alkyl group and the vinyl ester monomer (D) of carboxylic acid having 1 to 3 carbon atoms are in the range of 1 to 3 carbon atoms. Therefore, cohesive force can be imparted to the copolymer, and good processability can be obtained in a heating environment.
Specifically, the (meth) acrylic acid ester monomer (C) having 1 to 3 carbon atoms in the alkyl group is, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, or the like. Is mentioned. Examples of the C1-C3 carboxylate vinyl monomer (D) include vinyl acetate, vinyl propionate, and vinyl butyrate.
The structure of the alkyl group of the vinyl ester monomer (D) of 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 cohesion.
These monomers can be used alone or in combination of two or more.

  The (meth) acrylic acid ester monomer (C) having 1 to 3 carbon atoms of the alkyl group and the vinyl ester monomer (D) of carboxylic acid having 1 to 3 carbon atoms are contained in 100% by mass of the monomer mixture used for copolymerization. In addition, the total content is preferably 1 to 40% by mass, more preferably 2 to 20% by mass, further preferably 2 to 15% by mass, and particularly preferably 2 to 10% by mass. By containing 1% by mass or more, a cohesive force can be imparted to the copolymer, and by setting it to 40% by mass or less, adhesive strength and tackiness under a low temperature environment can be maintained.

[Other monomers]
In the present invention, other monomers can be used for the synthesis of the copolymer. Other monomers are (meth) acrylic acid ester monomer (A) having 8 to 12 carbon atoms in the alkyl group, monomer (B) having a carboxyl group, and (meth) acrylic acid having 1 to 3 carbon atoms in the alkyl group. This 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 4 to 20 carbon atoms in the alkyl group (however, a (meth) acrylic acid ester monomer having 8 to 12 carbon atoms in the alkyl group) (Excluding (A)), aromatic ring-containing monomers, alkoxy (poly) alkylene oxide-containing monomers and other vinyl monomers are preferred.
As the reactive functional group-containing monomer, a hydroxyl group-containing monomer, an amide bond-containing monomer, an epoxy group-containing monomer, an amino group-containing monomer, and the like are preferable.

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

  The (meth) acrylic acid alkyl ester monomer having 4 to 20 carbon atoms in the alkyl group (excluding the (meth) acrylic acid ester monomer (A) having 8 to 12 carbon atoms in the alkyl group) is 100 masses of the monomer mixture. It is preferable to contain 1-15 mass parts in%.

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

  The hydroxyl group-containing monomer preferably contains 0.1 to 8% by mass, more preferably 0.2 to 6% by mass, in 100% by mass of the monomer mixture. It becomes easy to adjust a crosslinking density with a hardening | curing agent to an appropriate range by containing 0.1-8 mass%.

  As amide bond-containing monomers, (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, N- (butoxymethyl) acrylamide, etc., compounds containing a heterocyclic ring such as N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, N -Vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide and the like.

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

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

  The amide bond-containing monomer, the epoxy group-containing monomer and the amino group-containing monomer are each preferably contained in an amount of 0.1 to 15% by mass 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.

  As aromatic ring-containing monomers, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, (meth) acrylate ethylene oxide modified nonylphenol, (meth) Examples include biphenyl acrylate, styrene, vinyl toluene, and α-methyl styrene. It is preferable that 1-15 mass% of aromatic ring containing monomers are contained in 100 mass% of monomer mixtures.

  Examples of the alkoxy (poly) alkylene oxide-containing monomer include 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-phenoxyethyl acrylate, methoxypolyethylene glycol (meth) acrylate, and ethoxypolyethylene glycol (meth) acrylic acid. Examples include esters, methoxypolypropylene glycol (meth) acrylic acid esters, ethoxypolypropylene glycol (meth) acrylic acid esters, phenoxypolyethylene glycol (meth) acrylic acid esters, and phenoxypolypropylene glycol (meth) acrylic acid esters. It is preferable that 1-15 mass% of alkoxy (poly) alkylene oxide containing monomers are contained in 100 mass% of monomer mixtures.

  Other vinyl monomers include styrene and acrylonitrile. A copolymerizable monomer other than these can be appropriately selected. It is preferable that 1-15 mass% of other vinyl monomers are contained in 100 mass% of monomer mixtures.

[Method for producing copolymer]
The copolymer can be obtained by adding a polymerization initiator to the monomer mixture and appropriately selecting a known production method such as solution polymerization, bulk polymerization, and various radical polymerizations. Among these, solution polymerization is preferable because it is easy to adjust the weight average molecular weight of the copolymer.

  Solvents that can be used in solution polymerization are 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 used alone or in combination of two or more. The solvent preferably contains a hydrocarbon solvent such as toluene, xylene, hexane, cyclohexane, methylcyclohexane, and heptane. Of the hydrocarbon solvents, hydrocarbon solvents having no aromatic ring such as hexane and heptane are particularly preferable 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 containing 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 100 parts by mass in total of the monomer mixture. Usually, the polymerization reaction can be carried out at a temperature of about 50 ° C. to 90 ° C. for 6 hours to 20 hours under a nitrogen stream. Moreover, the weight average molecular weight of a copolymer can be suitably adjusted using a chain transfer agent for a 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, further preferably 500,000 to 900,000, and particularly preferably 500,000 to 800,000. By making the weight average molecular weight in the range of 200,000 to 1,200,000, it is possible to achieve both a balance between adhesive physical properties and coating properties.

  Examples of the chain transfer agent include n-dodecyl mercaptan, mercaptoisobutyl alcohol, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, glycidyl mercaptan, α-methyl Examples include styrene dimer, carbon tetrachloride, chloroform, hydroquinone and the like.

  The polymerization initiator is generally an azo compound or an organic peroxide. Examples of the azo compound include 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 ) And the like.

  Organic peroxides include, for example, benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxydi. Examples include carbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide 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 adhesive layer, which is a cured product of the solvent-type 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, and particularly preferably 70 to 99% by mass. It is preferable for the content to be in this range because better tackiness and processability can be expressed and a transparent coating film can be obtained.

<Curing agent>
In the present invention, the curing agent is preferably an isocyanate compound, an epoxy compound, an ethyleneimine compound, a metal chelate compound, an amine compound, and the like, and an epoxy compound is particularly preferable from the viewpoint of processability in a heating 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, Compounds having 3 or more isocyanate groups in the molecule such as adducts with prene polyols, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate , Tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate and other isocyanate monomers, hexamethylene diisocyanate allophanate (coronate 2770: manufactured by Nippon Polyurethane Industry Co., Ltd.) Examples include compounds having an isocyanate group. Among these, a trimethylolpropane adduct of tolylene diisocyanate is preferable because the adhesive properties can be easily adjusted. In addition, the number of isocyanate groups is an average number.

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

  Examples of the ethyleneimine compounds include N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxite), N, N′-toluene-2,4-bis (1-aziridinecarboxite), bisiso Phthaloyl-1- (2-methylaziridine), tri-1-aziridinylphosphine oxide, N, N′-hexamethylene-1,6-bis (1-aziridinecarboxite), 2,2′-bishydroxy Methylbutanol-tris [3- (1-aziridinyl) propionate], trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethane tri-β-aziridinylpropionate, tris-2,4,6 -(1-aziridinyl) -1,3,5-triazine and the like.

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

Examples of the amine compound include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resin, and methylene resin.
These curing agents can be used alone or in combination of two or more.

  It is preferable that a hardening | curing agent contains 0.005-15 mass parts with respect to 100 mass parts of copolymers, 0.01-10 mass parts is more preferable, 0.02-5 mass parts is still more preferable, 0 0.03 to 3 parts by mass is particularly preferable. When 0.005 to 15 parts by mass are included, it becomes easy to balance the cohesive force and adhesive force of the adhesive layer.

<Tackifying resin>
The solvent-type pressure-sensitive adhesive composition of the present invention contains a terpene resin as a tackifier resin.
Moreover, you may use together tackifying resin other than a terpene resin. By including other tackifying resin, 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 in the total 100% by mass of the tackifying resin. 70 to 98% by mass is particularly preferable. By being 50 mass% or more, the adhesive force with respect to polyolefin at the time of low temperature becomes more favorable.
The pressure-sensitive adhesive composition of the present invention is excellent in adhesiveness to highly polar polyolefins by containing a terpene resin and other tackifying resins. Particularly, when the content is the above, not only polypropylene but also more adhesive. Even polyethylene that is difficult to increase in strength is preferable because it can have an effect of maintaining high adhesive strength.

[Terpene resin]
In the present invention, by adding a terpene resin, it is possible to achieve both adhesiveness and tackiness in a low temperature environment and processability in a heating environment. A terpene resin means a tackifier resin having isoprene as a structural unit. From the viewpoint of tackiness, polyterpene, which is a resin having isoprene as a structural unit and consisting only of terpene, is preferred. That is, a terpene resin other than a terpene resin having a structural unit other than a terpene such as an aromatic modified terpene resin, a terpene phenol resin, or a hydrogenated terpene phenol resin is preferable.

  As the terpene resin having a structural unit other than the terpene, an aromatic-modified terpene resin, a terpene phenol resin, or a hydrogenated terpene phenol resin can be used. Specifically, the terpene resin having only isoprene as a structural unit is, for example, YS Resin PX800, YS Resin PX1000, YS Resin PX1150, YS Resin PX1250 manufactured by Yasuhara Chemical Co., Ltd. And SYLVARES TR7125. As the aromatic modified terpene resin, YS Resin TO105, YS Resin TO115 manufactured by Yasuhara Chemical Co., Ltd., as the terpene phenol resin, YS Polystar T100, YS Polystar T115 manufactured by Yashara Chemical Co., Ltd., as hydrogenated terpene phenol resin, YS Polystar UH115 manufactured by Yasuhara Chemical Co., Ltd., and the like can be mentioned.

  The softening point of the terpene resin is more preferably in the range of 80 to 130 ° C. By setting the softening point to 80 to 130 ° C., it becomes easy to balance the cohesive strength and adhesive strength of the pressure-sensitive adhesive layer under a low temperature environment and a heating 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 preferably 10 to 28 parts by mass with respect to 100 parts by mass of the copolymer. preferable. When 2-50 mass parts is contained, it will become easy to balance the cohesive force and adhesive force of an adhesive layer. These can be used alone or in combination of two or more.

[Other tackifying resins]
If the solvent-type pressure-sensitive adhesive composition of the present invention contains other tackifier resin in addition to the terpene resin, the adhesive force can be further improved.
Other tackifying resins include, for example, aliphatic petroleum resins, aromatic petroleum resins, coumarone-indene resins, phenol resins, rosin derivatives (rosin, polymerized rosin, hydrogenated rosin, and their glycerin, pentaerythritol, etc. All existing ones 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 and aromatic resins. Preference is given to at least one tackifying resin selected from the group consisting of petroleum resins, aliphatic / aromatic petroleum resins and rosin derivatives.
More preferred are aliphatic petroleum resins, aromatic petroleum resins, or rosin derivatives.

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

  The other tackifying resin is preferably blended in an amount of 1 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the copolymer. By including 1 to 10 parts by mass, it is possible to obtain good adhesive strength to PP.

<Organic solvent>
The solvent-type pressure-sensitive adhesive composition of the present invention contains an organic solvent.
The organic solvent may be a reaction solvent for solution polymerization of the copolymer or a diluted solvent after the copolymer synthesis, and may be added before the pressure-sensitive adhesive composition is applied.

As the organic solvent, those described in the method for producing a copolymer can be used.
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 A halogenated hydrocarbon solvent such as dichloromethane or chloroform; an organic solvent such as an ether solvent such as diethyl ether, methoxytoluene, or dioxane can be added to adjust the viscosity. These organic solvents can be used alone or Two or more types may be used.
Especially, it is preferable that a hydrocarbon type solvent is included.
By including a hydrocarbon solvent in the pressure-sensitive adhesive composition, the compatibility of the terpene resin at the time of solution can be improved, and excellent temporal stability can be expressed in a wide temperature range. Among the hydrocarbon solvents, hydrocarbon solvents having no aromatic ring such as hexane and heptane are particularly preferable from the viewpoint of environmental regulations.

  It is preferable that an organic solvent contains 10-500 mass parts with respect to 100 weight part of copolymers, and 50-300 mass parts is more preferable. By being in this range, it is excellent in handling at the time of synthesis and coating.

<Silane coupling agent>
The solvent-type pressure-sensitive adhesive composition of the present invention can further contain a silane coupling agent. Silane coupling agents include, for example, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropyltripropoxysilane, 3- (meth) acrylic. Alkoxysilane compounds having a (meth) acryloxy group, such as loxypropyltributoxysilane, 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;
Alkoxysilane compounds having a mercapto group such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 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 thereof include triethoxysilane, hexamethyldisilazane, and a silicone resin having an alkoxysilyl group in the molecule.

<Other ingredients>
The solvent-type pressure-sensitive adhesive composition of the present invention includes various resins, curing catalysts, oils, softeners, dyes, pigments, antioxidants, ultraviolet absorbers, weather resistance stability, as long as the effects of the present invention are not impaired. You may mix | blend an agent, a plasticizer, a filler, anti-aging agent, an antistatic agent, etc.

  The solvent-type pressure-sensitive adhesive composition of the present invention is suitable for affixing nonpolar adherends, general labels and seals, adhesive optical films, paints, elastic wall materials, waterproof coating materials, flooring materials, For 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 foam (hard , Semi-rigid, soft), urethane RIM, UV / EB cured resin, high solid paint, thermosetting elastomer, microcellular, textile processing agent, plasticizer, sound absorbing material, vibration damping material, surfactant, gel coat agent, artificial Marble resin, impact resistance imparting agent for artificial marble, resin for ink, film (laminate adhesive, protective film, etc.), combined Glass resin, reactive diluent, various molding materials, elastic fiber, artificial leather, as a raw material for synthetic leather, can also very effectively used as various resin additives and a raw material thereof or the like.

≪Adhesive sheet≫
The pressure-sensitive adhesive sheet of the present invention preferably includes a base material and a pressure-sensitive adhesive layer formed from the solvent-based pressure-sensitive adhesive composition of the present invention. Moreover, as another aspect, the double-sided adhesive sheet which has an adhesive layer on both surfaces of a core material, or the cast adhesive sheet which did not have a base material and a core material but was comprised only by the adhesive layer is also preferable. The pressure-sensitive adhesive layer can be formed by applying a pressure-sensitive adhesive on a substrate and drying it. Or it can form by sticking a base material, after apply | coating an adhesive on a peelable sheet and drying and forming an adhesive layer. Needless to say, the peelable sheet is bonded to the surface of the pressure-sensitive adhesive layer that does not contact the base material.

  As the substrate, for example, cellophane, plastic, rubber, foam, cloth, rubber cloth, resin-impregnated cloth, glass, wood and the like are preferable. The shape of the substrate can be selected from a plate shape and a film shape, but a film that is easy to handle is preferred. The substrate can be used alone or in combination of two or more.

  Plastics include, for example, polyvinyl alcohol, triacetyl cellulose, polypropylene, polyethylene, polycycloolefin, polyolefin such as ethylene-vinyl acetate copolymer, polyester such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polynorbornene, Examples include polyarylate, polyacryl, polyphenylene sulfide, polystyrene, polyamide, polyimide film, and epoxy.

  The method for applying the solvent-type pressure-sensitive adhesive composition is not particularly limited, and may be a Mayer bar, applicator, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, knife coater, reverse coater, spin coater, etc. Is mentioned. There is no restriction | limiting in particular in a drying method, The thing using hot air drying, infrared rays, and the pressure reduction method is mentioned. As drying conditions, hot air heating of about 60 to 160 ° C. is usually possible depending on the curing agent type, the thickness of the pressure-sensitive adhesive layer, or the solvent type.

  0.1-300 micrometers is preferable and, as for the thickness of an adhesive layer, 1-100 micrometers is more preferable. The adhesive physical property can be adjusted to an appropriate range by being in the range of 0.1 to 300 μm.

  The pressure-sensitive adhesive sheet of the present invention can be used for various applications from high polarity to low polarity, such as polyolefin, plastic, glass, cardboard, metal and the like. Specifically, it can be preferably used in labels for food labels stored in a frozen or refrigerated environment, labels used in cold regions, and the like.

  Next, although an example of the present invention is shown and explained in detail, the present invention is not limited to these. In the examples, “part” means “part by mass”, and “%” means “% by mass”.

(Synthesis Example 1)
90.4 parts of 2-ethylhexyl acrylate, acrylic, in a nitrogen atmosphere in a reaction vessel (hereinafter simply referred to as “reaction vessel”) equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen introduction tube 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 copies were charged. The mixture was heated with stirring to confirm the start of the polymerization reaction, and reacted at reflux temperature for 2 hours. Next, 0.03 part of AIBN was added to the reaction solution, and the reaction was continued for 6 hours. Thereafter, the reaction vessel 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)
The copolymer 2-21 solution of the synthesis examples 2-21 was obtained by carrying out similarly to the synthesis example 1 except having followed the kind and compounding quantity of the monomer according to description of Table 1. About the obtained copolymer solution, the weight average molecular weight was calculated | required in accordance with the following method. The results are shown in Table 1.

(Synthesis Examples 22-25)
The copolymer 2-25 solution of the synthesis examples 22-25 was obtained by carrying out similarly to the synthesis example 1 except having followed the kind and compounding quantity of the monomer according to description of Table 2. About the obtained copolymer solution, the weight average molecular weight was calculated | required in accordance with the following method. The results are shown in Table 2.

“Β-CEA / (B)” in the table is the content (mass%) of β-CEA (2-carboxyethyl acrylate) in 100 mass% of the monomer (B) having a carboxyl group,
“(A) / Copolymer” is the content (% by mass) of the (meth) acrylic acid ester monomer (A) having 8 to 12 carbon atoms in the alkyl group in 100% by mass of the monomer mixture.

<Measurement of weight average molecular weight>
The weight average molecular weight (Mw) was measured using GPC “LC-GPC system” manufactured by Shimadzu Corporation. GPC is liquid chromatography in which a substance dissolved in a solvent (THF; tetrahydrofuran) is separated and quantified by the difference in molecular size, and the weight average molecular weight was determined in terms of polystyrene.
Device name: LC-GPC system “Prominence” manufactured by Shimadzu Corporation
Column: Four Tosoh Co., Ltd. GMHXL and one Tosoh Co., Ltd. HXL-H were connected in series.
Mobile phase solvent: Tetrahydrofuran flow rate: 1.0 ml / min Column temperature: 40 ° C

The 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 as a curing agent) Chemical Co., Ltd.) 0.03 part (nonvolatile content conversion), terpene resin YS Resin PX1250 (Yashara Chemical Co., Ltd.) 10 parts (nonvolatile content conversion), rosin derivative Sylvatac RE85 (Arizona Chemical Co., Ltd.) 5 parts (Nonvolatile content conversion) was added, and hexane was further added as a solvent to adjust the nonvolatile content to 35% to obtain a pressure-sensitive adhesive solution.
Apply the adhesive solution to a 38 μm thick peelable sheet (polyethylene terephthalate (PET)) with a comma coater so that the thickness after drying is 50 μm, and dry at 100 ° C. for 2 minutes. A pressure-sensitive adhesive layer was formed. Subsequently, a base material (made of polyethylene terephthalate, hereinafter referred to as a PET sheet) having a thickness of 50 μm was bonded to the pressure-sensitive adhesive layer and aged for 1 week under the condition of a temperature of 23 ° C. and a relative humidity of 50%. A pressure-sensitive adhesive sheet having a configuration of “pressure-sensitive adhesive layer / PET sheet” was obtained.

(Examples 2-39, Comparative Examples 1-4)
Except having changed into the material and mixing | blending of Table 3, it carried out similarly to Example 1, and obtained the adhesive solution and adhesive sheet of Examples 2-39 and Comparative Examples 1-4, respectively.
However, Examples 15 to 39 and 55 to 58 are reference examples.

(Examples 40 to 58)
Except having changed into the material and mixing | blending of Table 4, it carried out similarly to Example 1, and obtained the adhesive solution and adhesive sheet of Examples 40-58, respectively.

  The “terpene resin / tackifier resin” in the table is the content (% by mass) of the terpene resin in the total 100% by mass of the tackifier resin, and the “copolymer / adhesive layer” is the adhesive. It is content (mass%) of the copolymer in 100 mass% of layers.

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

The obtained adhesive sheet was evaluated by the following methods. The results are shown in Tables 3 and 4.
(1) Adhesive strength The obtained adhesive sheet was prepared in a size of 25 mm in width and 150 mm in length. In an atmosphere of 5 ° C. or 23 ° C. and a relative humidity of 50%, the peelable sheet is peeled off from the adhesive sheet and attached to a stainless steel (SUS) plate. The adhesive strength was measured in a 180 ° peel test in which the film was peeled off at a speed of 300 mm / min. In the same manner as described above, the adhesion to a polypropylene (PP) plate and a polyethylene (PE) plate was measured.

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”
Δ: “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. Impractical.”
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”
Δ: “Adhesive strength of 10 N / 25 mm or more and less than 13 N / 25 mm. Practical level”
X: “Adhesive strength is less than 10 N / 25 mm. Impractical.”
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”
Δ: “Adhesive strength is 11 N / 25 mm or more and less than 14 N / 25 mm. Practical level”
X: “Adhesive strength is less than 11 N / 25 mm. Impractical.”
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”
Δ: “Adhesive strength of 10 N / 25 mm or more and less than 13 N / 25 mm. Practical level”
X: “Adhesive strength is less than 10 N / 25 mm. Impractical.”
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”
Δ: “Adhesive strength is 5 N / 25 mm or more and less than 7 N / 25 mm. Practical level”
X: “Adhesive strength is less than 5 N / 25 mm. Impractical.”
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”
Δ: “Adhesive strength is 4 N / 25 mm or more and less than 6 N / 25 mm. Practical level”
X: “Adhesive strength is less than 4 N / 25 mm. Impractical.”

(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 peeling the peelable sheet from the adhesive sheet and polishing it, a pressure sensitive adhesive layer is attached to the bottom 25 mm wide and 25 mm wide part of a stainless steel plate with a width of 30 mm and a length of 150 mm, and after reciprocating with a 2 kg roll, the atmosphere is 40 ° C. The holding force was measured by applying a load of 1 kg and leaving it for 70,000 seconds. Evaluation measured the length which the upper end part of the adhesive sheet sticking surface shifted | deviated below.

Evaluation criteria A: “No deviation was observed. Very good.”
○: “Displacement occurs, and the length of displacement is less than 2 mm. Good.”
Δ: “The shifted length is 2 mm or more and less than 5 mm. Practical level.”
X: “The shifted length is 5 mm or more. Impractical.”

(3) Ball tack The obtained pressure-sensitive adhesive sheet was prepared to have a width of 25 mm and a length of 250 mm. The peelable sheet was peeled off from the pressure-sensitive adhesive sheet and fixed to an inclined plate with an inclination angle of 30 degrees with the pressure-sensitive adhesive surface facing up. A steel film (1/32 to 32/32 inches) is rolled onto a sample with a 10 cm runner-up paste surface and a PET film for the runway pasted on the top, and the number of the diameter of the ball that stops near the center of the paste surface. Recorded. The measurement was carried out in an atmosphere of 5 ° C. or 23 ° C. and a relative humidity of 50%.

Evaluation criteria in an atmosphere at 5 ° C. A: “Ball diameter is 10 or more. Very good.”
○: “Ball diameter is 7 to 9. Good”
Δ: “Ball diameter is 4 to 6. Practical level”
X: “Ball diameter is 3 or less. Impractical.”
Evaluation Criteria at 23 ° C. and 50% Relative Humidity A: “Ball diameter is 19 or more. Very good.”
○: “Ball diameter is 15 to 18. Good”
Δ: “Ball diameter is 11 to 14. Practical level.”
X: “The ball diameter is 10 or less.

(4) Workability test The obtained pressure-sensitive adhesive sheet was prepared to have a width of 10 mm and a length of 10 mm. The peelable sheet is peeled off from the pressure-sensitive adhesive sheet, and the top and bottom are sandwiched between 38 μm thick peelable sheets (polyethylene terephthalate), and a pressure of 50 kg / cm ² is applied in a 40 ° C. environment using a press tester for 2 hours. I left it alone. After completion of the test, the sample was taken out and the width of the paste protruding from the end of the test piece was measured (maximum value).

Evaluation criteria A: “The protrusion is 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.”
Δ: “The protrusion is 0.6 or more and less than 0.8 mm. Practical level.”
×: “The protrusion is 0.8 mm or more. Impractical.”

(4) Appearance of coating film The obtained pressure-sensitive adhesive sheet 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.”
Δ: “Haze is 11 or more and less than 15. Practical level.”
X: “Haze is 15 or more. Impractical.”

  As shown in the examples in Tables 3 and 4, the solvent-type pressure-sensitive adhesive composition of the present invention has a low temperature, a normal pressure environment adhesive strength, a ball tack, a high temperature holding power, workability, and a coating film appearance. It became clear that it was excellent. On the other hand, in the comparative example, any item was defective, and it became clear that it was not practical.

Claims (7)

A solvent-type pressure-sensitive adhesive composition comprising a copolymer, a curing agent, a tackifier resin, and an organic solvent,
The copolymer is a copolymer of a monomer mixture containing a (meth) acrylic acid ester monomer (A) having 8 to 12 carbon atoms in an alkyl group and a monomer (B) having a carboxyl group,
In 100% by mass of the monomer mixture, the alkyl group contains 80 to 97% by mass of (meth) acrylic acid ester monomer (A) having 8 to 12 carbon atoms,
The tackifying resin includes a terpene resin and at least one selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, aliphatic / aromatic petroleum resins and rosin derivatives;
The content of the terpene resin is 50% by mass or more in a total of 100% by mass of the tackifying resin,
The solvent-type adhesive composition whose content of the said copolymer is 40 mass% or more in 100 mass% of adhesive layers which are the hardened | cured material of a solvent-type adhesive composition.   The solvent-type adhesive composition of Claim 1 whose said terpene resin is resin which consists only of terpene as a structural unit.   The solvent-type pressure-sensitive adhesive composition according to claim 1 or 2, wherein the organic solvent is a hydrocarbon solvent.   The solvent-type adhesive composition of any one of Claims 1-3 in which the monomer (B) which has the said carboxyl group contains (meth) acrylic-acid 2-carboxyethyl. 5. The solvent-based pressure-sensitive adhesive composition according to claim 4 , wherein the content of 2-carboxyethyl (meth) acrylate is 50% by mass or more in a total of 100% by mass of the monomer (B) having a carboxyl group.   The solvent-type adhesive composition of any one of Claims 1-5 in which the monomer (B) which has a carboxyl group contains (meth) acrylic acid and 2-carboxyethyl (meth) acrylate. A pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer that is a cured product of the solvent-type pressure-sensitive adhesive composition according to any one of claims 1 to 6 .