JP6108023B1 - Adhesive and adhesive sheet - Google Patents

Abstract

An object of the present invention is to provide a pressure-sensitive adhesive that can be used as a one-component curable type that has a high nonvolatile content, pot life, and coating property, and has good heat resistance, and a pressure-sensitive adhesive sheet. An acrylic polymer (A) which is a polymer of a monomer mixture containing 6 to 18% by weight of an acid group-containing monomer (a1) and 15 to 94% by weight of 2-ethylhexyl acrylate, a chelate type curing agent ( B) and organic solvent (C) (excluding alcohol (D)), and at least one of alcohol (D) and keto-enol tautomer-forming compound (E), having a non-volatile concentration of 55 to 75 The pressure-sensitive adhesive is mass%. [Selection figure] None

Description

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

  Adhesives are widely used for use in adhesive labels and adhesive sheets. As the pressure-sensitive adhesive, a solvent-type pressure-sensitive adhesive and a water-based pressure-sensitive adhesive are generally used, and among them, there is an increasing demand for a water-based pressure-sensitive adhesive having a low price and a low solvent discharge. On the other hand, solvent-based pressure-sensitive adhesives are widely used in applications where performance is insufficient with water-based pressure-sensitive adhesives such as water resistance and heat resistance. However, there was a strong demand for solvent adhesives from the market to reduce costs and reduce environmental impact. Therefore, by increasing the non-volatile content of the solvent-type pressure-sensitive adhesive, the method of reducing the amount of solvent that volatilizes when applying and drying the pressure-sensitive adhesive and suppressing the thermal energy of drying, and general solvent-type pressure-sensitive adhesives are: Because of the problem of pot life, there are many two-component curing types that contain a curing agent immediately before coating, and by making the adhesive a pot life with a long pot life (hereinafter referred to as a one-component curing type), A method of reducing the cost of the pressure-sensitive adhesive sheet and reducing the environmental load is being performed by a method of reducing the blending process at the coating site.

  However, simply reducing the amount of the organic solvent contained in the solvent-type pressure-sensitive adhesive increases the viscosity of the pressure-sensitive adhesive because the resin concentration becomes relatively high. As a result, the fluidity of the pressure-sensitive adhesive is lowered, and the adhesive layer surface of the pressure-sensitive adhesive sheet becomes non-uniform at the time of coating, resulting in a problem that the adhesion with the adherend is lowered.

  Therefore, Patent Document 1 discloses a solid content containing an acrylic polymer having a weight average molecular weight of 50,000 to 300,000 and an organic solvent (B) in which the chain transfer constant of vinyl acetate to an organic solvent at 60 ° C. is 250 or more. An adhesive having a concentration of 60% or more and a viscosity of 20,000 mPa · s / 25 ° C. or less is disclosed.

JP 2011-246700 A

  However, the conventional pressure-sensitive adhesive has a low coating smoothness such as a pressure-sensitive adhesive layer having a low surface smoothness, and since the weight average molecular weight is set too low, when a pressure-sensitive adhesive sheet is used in a high-temperature atmosphere, There was a heat resistance problem that the pressure-sensitive adhesive layer peeled off due to cohesive failure of the pressure-sensitive adhesive layer.

  An object of the present invention is to provide a pressure-sensitive adhesive that can be used as a one-component curable type that has high non-volatile content, pot life, and coatability and that has good heat resistance, and a pressure-sensitive adhesive sheet.

  The pressure-sensitive adhesive of the present invention is an acrylic polymer (A) that is a polymer of a monomer mixture containing 6 to 18% by mass of an acid group-containing monomer (a1) and 15 to 94% by weight of 2-ethylhexyl acrylate, a chelate type A non-volatile content concentration containing a curing agent (B) and an organic solvent (C) (excluding alcohol (D)) and at least one of alcohol (D) and keto-enol tautomer-forming compound (E) It is 55-75 mass%.

  According to the present invention, the molecular weight distribution of the acrylic polymer (A) is broadened by using an appropriate amount of 2-ethylhexyl acrylate having a relatively low reaction rate, and the chelate-type curing agent (B) and alcohol ( By using any one of D) and the keto-enol tautomer forming compound (E), it was possible to improve the high non-volatile content, pot life, and coatability. Moreover, the heat resistance of the pressure-sensitive adhesive could be improved by using an appropriate amount of the acidic group-containing monomer (a1) and the combination of the chelate type curing agent (B).

  According to the present invention, it is possible to provide an adhesive and an adhesive sheet that can be used as a one-component curable type having good heat resistance while satisfying high non-volatile content, pot life, and coatability.

  Prior to describing the present invention in detail, terms will be defined. Sheet, film and tape are synonymous. (Meth) acrylic acid includes acrylic acid and methacrylic acid. (Meth) acrylate includes acrylate and methacrylate. The monomer is an ethylenically unsaturated double bond-containing monomer. The adherend refers to the other party to which the adhesive sheet is attached.

  The pressure-sensitive adhesive of the present invention is an acrylic polymer (A) that is a polymer of a monomer mixture containing 6 to 18% by mass of an acid group-containing monomer (a1) and 15 to 94% by weight of 2-ethylhexyl acrylate, a chelate type A non-volatile content concentration containing a curing agent (B) and an organic solvent (C) (excluding alcohol (D)) and at least one of alcohol (D) and keto-enol tautomer-forming compound (E) It should be 55 to 75% by mass.

  The pressure-sensitive adhesive of the present invention is preferably used by forming a pressure-sensitive adhesive layer by coating and processing it into a pressure-sensitive adhesive sheet provided with a substrate. The pressure-sensitive adhesive of the present invention does not preclude the use of the liquid as it is, as well as the pressure-sensitive adhesive sheet, as in the so-called “glue”. Moreover, it can be used also as what is called a cast adhesive sheet comprised only from the adhesive layer, without using a base material.

  In the present invention, the acrylic polymer (A) is a polymer obtained by solution polymerization of a monomer mixture. A known polymerization method can be used for the solution polymerization.

  The monomer mixture contains 6 to 18% by mass of the acid group-containing monomer (a1) and 15 to 94% by weight of 2-ethylhexyl acrylate as essential monomers, and includes monomers other than these monomers as optional monomers.

The acidic group-containing monomer (a1) contributes to the crosslinking of the curing reaction between the acrylic polymer (A) and the chelate-type curing agent (B), and the cohesive force of the pressure-sensitive adhesive layer is improved by this crosslinking.
Examples of the acidic group-containing monomer (a1) include (meth) acrylic acid, 2-carboxyethyl (meth) acrylate, (meth) acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, Glutaconic acid, itaconic acid, acrylamide N-glycolic acid, cinnamic acid, 2- (meth) acryloyloxyethyl hexahydrophthalate, 2- (meth) acryloyloxyethyl phthalate, 2- (meth) acryloyloxyethyl succinate, etc. Can be mentioned. Among these, (meth) acrylic acid is preferable.

  The acidic group-containing monomer (a1) is preferably contained in 6 to 18% by weight, more preferably 8 to 16% by weight, and further preferably 10 to 15% by weight in 100% by weight of the monomer mixture. When the acid group-containing monomer (a1) is contained in an amount of 6% by weight or more, good heat resistance can be obtained. Further, when it is contained in an amount of 18% by weight or less, good coating properties and good pot life can be obtained.

  2-Ethylhexyl acrylate has a relatively low polymerization rate in the radical polymerization reaction, and tends to broaden the molecular weight distribution of the acrylic polymer (A). Thereby, since the viscosity of an adhesive can be suppressed, when the non volatile matter density | concentration of an adhesive is set high, favorable coating property is obtained.

2-ethylhexyl acrylate is preferably contained in 15 to 94% by weight in 100% by weight of the monomer mixture, more preferably 30 to 90% by weight, still more preferably 40 to 80% by weight, and particularly preferably 45 to 60% by weight.
When an appropriate amount of 2-ethylhexyl acrylate is contained, heat resistance and coatability are improved.

  In the present invention, optional monomers include (meth) acrylate monomers other than 2-ethylhexyl acrylate, amide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, aromatic ring-containing monomers, alicyclic hydrocarbon group-containing monomers, vinyl esters. , (Meth) acrylic acid alkoxy ester, hydroxyl group-containing monomer and the like are preferable.

  Examples of the (meth) acrylate monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2 -Ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n -Dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, etc. are mentioned. Among these, (meth) acrylate (methyl (meth) acrylate, ethyl (meth) acrylate), n-butyl acrylate, 2-ethylhexyl acrylate and the like having an alkyl chain having 1 to 2 carbon atoms may be mentioned. The (meth) acrylic monomer does not contain (meth) acrylic acid alkoxyester.

Examples of the amide group-containing monomer include (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N′-methylenebisacrylamide, N-methylol (meth) acrylamide, N-ethylol (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-vinylpyrrolidone, diacetone acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, (meth) acryloyl And morpholine.

  Examples of the amino group-containing monomer include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and the like.

  Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether.

  Examples of the aromatic ring-containing monomer include phenyl acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, biphenyl (meth) acrylate, styrene, vinyltoluene, α-methylstyrene, and the like.

  Examples of the alicyclic hydrocarbon group-containing monomer include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, isobornyl (meth) acrylate, and the like.

  Examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl laurate, and the like.

  Examples of (meth) acrylic acid alkoxyesters include, for example, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxypropyl (meth) acrylate, and 3-methoxypropyl (meth) acrylate. , (Meth) acrylic acid 2-methoxybutyl, (meth) acrylic acid 4-methoxybutyl and the like.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxyoctyl (meth). Acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether etc. are mentioned.
Among the optional monomers, use of a hydroxyl group-containing monomer is preferable because the cohesive force of the pressure-sensitive adhesive layer is increased and heat resistance is improved. The hydroxyl group-containing monomer is more preferably 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate.

The hydroxyl group-containing monomer is preferably contained in an amount of 0.05 to 3% by weight, more preferably 0.1 to 2% by weight, and further preferably 0.2 to 1.5% by weight in 100% by weight of the monomer mixture.
Arbitrary monomers can be used alone or in combination of two or more.

For the solution polymerization, a polymerization initiator capable of radical polymerization is used. The polymerization initiator is preferably an azo compound or a peroxide. Examples of the azo compound include 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobisisobutyronitrile, and the like. Peroxides are t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, di-t-butyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethyl. Cyclohexane and the like are preferable.
The polymerization initiators can be used alone or in combination of two or more.

The polymerization initiator is preferably used in an amount of 0.03 to 1.5 parts by weight, more preferably 0.1 to 1 part by weight, based on 100 parts by weight of the monomer mixture. When an appropriate amount of the polymerization initiator is used, it becomes easy to adjust the polymerization average molecular weight, and the adhesive properties can be adjusted.
Although the temperature of solution polymerization can be adjusted suitably, it is generally about 70-100 degreeC.

  In solution polymerization, a chain transfer agent can be used to adjust the molecular weight and molecular weight dispersity. The chain transfer agent is preferably a compound having a chain transfer constant with respect to vinyl acetate at 60 ° C. of 250 or more (hereinafter also referred to as a chain transfer compound). When a chain transfer agent is used, an acrylic polymer having a high molecular weight and low viscosity can be easily obtained, so that the coating property of the pressure-sensitive adhesive is further improved. The chain transfer constant is more preferably 300 or more, and further preferably 400 or more. On the other hand, the upper limit of the chain transfer constant is about 1000 although it is not necessary to limit the molecular weight because the molecular weight can be adjusted with a small amount by reducing the amount used. The molecular weight is a weight average molecular weight unless otherwise specified.

The chain transfer compound is preferably a ketone, thiol, tackifying resin or the like.
Examples of the ketone include acetone, methyl ethyl ketone, hexanone, cyclohexanone methyl ethyl ketone, and the like. Among these, methyl ethyl ketone (MEK) is preferable. The chain transfer constant for vinyl acetate at 60 ° C. is 738 for methyl ethyl ketone, 208.9 for toluene, 117 for acetone, and 33 for ethyl acetate. These figures are given in J. brandrup, E .; H. Immergut "Polymer Handbook", p. It is a numerical value based on II-91, Interscience (1975).

  Examples of the thiol include mercaptoethanol, thioglycerol, thioglycolic acid, 3-mercaptopropionic acid, thiomalic acid, 2-mercaptoethanesulfonic acid, butanethiol, octanethiol, decanethiol, dodecanethiol, hexadecanethiol, octadecanethiol, cyclohexyl Examples include mercaptan, thiophenol, octyl thioglycolate, and octyl 3-mercaptopropionate. Of these, octyl thioglycolate is preferred.

  The weight average molecular weight of the acrylic polymer (A) used in the present invention can be arbitrarily set as long as the above-described problems can be solved, but is preferably 300,000 to 900,000, more preferably 400,000 to 800,000, and 50 10,000 to 700,000 are more preferable. When the weight average molecular weight is set within an appropriate range, it becomes easy to achieve both heat resistance and coating property. In addition, a weight average molecular weight is a molecular weight of polystyrene conversion measured using gel permeation chromatography (GPC).

  The acrylic polymer (A) preferably has a molecular weight dispersity (meaning a molecular weight distribution) of 3 to 12, more preferably 3 to 10, and still more preferably 3 to 8. By setting the molecular weight dispersity to 3 to 12, the viscosity of the acrylic polymer (A) is lowered, so that it is easy to achieve both coatability and heat resistance. The molecular weight dispersity is a value obtained by dividing the weight average molecular weight by the number average molecular weight.

  The pressure-sensitive adhesive of the present invention comprises a chelate-type curing agent (B), alcohol (D) and / or keto-enol tautomer-forming compound (in addition to the above-mentioned acrylic polymer (A) and organic solvent (C). E). Addition of alcohol (D) or compound (E) having a reaction delay effect to chelate type curing agent (B) that reacts with acrylic polymer (A) prevents curing reaction in solution A good pot life can be maintained, and further, the alcohol and the compound (E) volatilize during drying, whereby the curing reaction proceeds in the pressure-sensitive adhesive after coating and drying, and good heat resistance is exhibited.

In the present invention, the chelate-type curing agent (B) is a compound composed of a polyvalent metal and a ligand. Examples of the polyvalent metal include nickel, aluminum, chromium, iron, titanium, zinc, cobalt, manganese, and zirconium. Examples of the ligand include acetylacetone and acetoacetate.
The chelate-type curing agent (B) can use a compound part in which a polyvalent metal and a ligand are arbitrarily combined, and a compound in which the polyvalent metal is combined with aluminum and the ligand is combined with acetylacetone or acetoacetate. preferable.
The chelate type curing agent (B) can be used alone or in combination of two or more.

The chelate-type curing agent (B) is preferably added in an amount of 0.1 to 1.5 parts by weight, more preferably 0.2 to 1.2 parts by weight, based on 100 parts by weight of the acrylic polymer (A). 0.3 to 1.0 part by weight is more preferable. When 0.1 parts by weight or more of the chelate-type curing agent (B) is blended, the cohesive force and heat resistance are further improved. Moreover, when 1.5 weight part or less is used, the adhesiveness of a base material and an adhesive layer improves more.
The pressure-sensitive adhesive of the present invention can be used in combination with another curing agent. The other curing agent is preferably, for example, an isocyanate curing agent, an epoxy curing agent or an aziridine curing agent.

The isocyanate curing agent is preferably diisocyanate or polyisocyanate having a trifunctional or higher functional isocyanate group obtained by modifying diisocyanate.
The diisocyanate is preferably an aromatic diisocyanate, an aliphatic diisocyanate, or an alicyclic diisocyanate.
Aromatic diisocyanates include, for example, 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4,4′-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate and the like can be mentioned.
Examples of the aliphatic diisocyanate include butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, xylylene diisocyanate, m-tetramethylxylylene diene. Examples thereof include dimerized isocyanate obtained by converting an isocyanate and a carboxyl group of dimer acid into an isocyanate group.
Examples of the alicyclic diisocyanate include cyclohexane-1,4-diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, and the like. It is done.

The polyisocyanate is preferably a so-called adduct obtained by modifying diisocyanate with a trifunctional polyol component, a burette obtained by reacting diisocyanate with water, or a trimer having an isocyanurate ring formed from three molecules of diisocyanate (isocyanurate).
Examples of the polyisocyanate include a trimethylolpropane adduct of tolylene diisocyanate, a buret of hexamethylene diisocyanate, an allophanate of hexamethylene diisocyanate, an isocyanurate of isophorone diisocyanate, and the like.

Examples of the epoxy curing agent include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, Examples include 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

Examples of the aziridine curing agent include diphenylmethane-4,4′-bis (1-aziridinecarboxamide), trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethanetri-β-aziridinylpropionate. , Toluene-2,4-bis (1-aziridinecarboxamide), triethylenemelamine, bisisophthaloyl-1- (2-methylaziridine), tris-1- (2-methylaziridine) phosphine, trimethylolpropane And tri-β- (2-methylaziridine) propionate.

  Another hardening | curing agent can be mix | blended about 0.05-5.0 weight part with respect to 100 weight part of acrylic polymers (A).

  The organic solvent (C) is used as a solvent for solution polymerization or a dilution solvent for adjusting the viscosity of the pressure-sensitive adhesive. In addition, the organic solvent (C) can be selected from the viewpoints of leveling properties during coating, drying properties, environment, and influence on the human body. The organic solvent (C) is preferably an aliphatic hydrocarbon, alicyclic hydrocarbon, aromatic hydrocarbon, ester, ketone or the like. The organic solvent (C) of the present invention does not contain alcohol.

Examples of the aliphatic hydrocarbon include n-hexane and n-heptane.
Alicyclic hydrocarbons include, for example, cyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, ethylcyclohexane, diethylcyclohexane, decahydronaphthalene, bicycloheptane, tricyclodecane, hexahydroindenecyclohexane, cyclooctane, α-pinene. , Known compounds such as terpinolene and limonene.
Examples of the aromatic hydrocarbon include toluene, xylene, benzene, solvent naphtha and the like.

  Examples of the ester include ethyl acetate and butyl acetate.

  Examples of the ketone include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

  Among these, the organic solvent (C) is preferably ethyl acetate, methyl ethyl ketone, or toluene from the viewpoints of dryness, solubility, and chain transfer effect during solution polymerization.

  The pressure-sensitive adhesive of the present invention contains at least one of an alcohol (D) and a keto-enol tautomer-forming compound (E). When these compounds are blended, it acts on the chelate-type curing agent (B), and the pot life of the pressure-sensitive adhesive can be greatly prolonged.

  Alcohol (D) is, for example, methanol, ethanol, 1-propanol, isopropanol, 1-butanol, isobutanol, tert-butanol, 1-pentanol, isopentanol, 1-hexanol, 4-methyl-2-pentanol, 1-heptanol, 1-octanol, isooctanol, 2-ethylhexanol, 1-nonanol, isononanol, 1-decanol, 1-dodecanol, 1-myristyl alcohol, cetyl alcohol, 1-stearyl alcohol, isostearyl alcohol, 2-octyl Examples include decanol, 2-octyldodecanol, 2-hexyldecanol, behenyl alcohol, and oleyl alcohol. Among these, methanol, ethanol, 1-propanol, and isopropanol are preferable from the viewpoints of volatility during drying, compatibility with chelate-type curing agents, and pot life.

  The alcohol (D) is preferably contained in the pressure-sensitive adhesive in an amount of 2 to 40% by weight, and more preferably 5 to 30% by weight. Pot life is further improved by containing 2% by weight or more of alcohol (D). Moreover, by including 40 weight% or less, coating property improves more and adjustment of the molecular weight of an acrylic polymer (A) becomes easy. Alcohol (D) can also be used as a solvent during solution polymerization.

  The keto-enol tautomer forming compound (E) is a compound capable of forming a keto-enol tautomer, and acetylacetone, acetoacetate, malonate and the like are preferable.

  Examples of the acetoacetate include methyl acetoacetate, ethyl acetoacetate, and isopropyl acetoacetate. Examples include butyl acetoacetate, isobutyl acetoacetate, and tert-butyl acetoacetate.

Examples of malonic acid esters include dimethyl malonate, diethyl malonate, and dibutyl malonate.
Among these, the keto-enol tautomer-forming compound (E) is preferably acetylacetone because it easily volatilizes during drying.

  The keto-enol tautomer-forming compound (E) is preferably contained in the pressure-sensitive adhesive in an amount of 0.05 to 5% by weight, more preferably 0.1 to 3% by weight, and further 0.2 to 2% by weight. preferable. When the keto-enol tautomer-forming compound (E) is contained in an amount of 0.05% by weight or more, the pot life is further improved. Moreover, when it contains 5 weight% or less, the cohesion force of an adhesive layer improves more.

  Since both the alcohol (D) and the keto-enol tautomer-forming compound (E) suppress the reaction of the chelate-type curing agent (B), they can be used alone or in combination. In addition, when using together, a compounding quantity can be suppressed rather than using each independently.

  The pressure-sensitive adhesive of the present invention can further contain a polyolefin. By including the polyolefin, the pressure-sensitive adhesive can further improve the cohesive force, and can improve the pressure-sensitive adhesive force on the low-polar adherend made of polyolefin.

Polyolefins are classified into chlorinated polyolefins (hereinafter referred to as chlorinated polyolefins) and non-chlorinated polyolefins (hereinafter referred to as non-chlorinated polyolefins). Examples of the chlorinated polyolefin include chlorinated polypropylene, acid-modified chlorinated polypropylene, acrylic-modified chlorinated polypropylene, chlorinated polyethylene, and chlorinated ethylene vinyl acetate copolymer. Among these, chlorinated polypropylene, acid-modified chlorinated polypropylene, and acrylic-modified chlorinated polypropylene are preferable, and chlorinated polypropylene is more preferable from the viewpoint that it has excellent solubility and high adhesion to a polyolefin adherend.

The chlorine content of the chlorinated polyolefin is preferably from 20% to 45%, more preferably from 28% to 45%, from the viewpoint that the effect of improving the adhesion to a low polarity adherend made of polyolefin is high.
Examples of the non-chlorinated polyolefin include polyethylene, polypropylene, α-olefin-propylene copolymer, ethylene-vinyl acetate copolymer, polybutene, maleated polybutene, polybutadiene and its hydride, polyisoprene and its hydride, maleated polybutadiene, Examples thereof include maleated polyisoprene, polybutadiene polyol and its hydride, polyisoprene polyol and its hydride, and lubricating oils such as process oil and liquid paraffin. Among these, α-olefin-polypropylene copolymer, polybutene, and lubricating oil are preferable from the viewpoint of excellent solubility and high adhesion to polyolefin adherends. As the lubricating oil, paraffinic lubricating oil, naphthenic lubricating oil and the like are preferable.

  The polyolefin used in the pressure-sensitive adhesive of the present invention is preferably a non-chlorinated polyolefin from the viewpoint that the pressure-sensitive adhesive is excellent, and among them, polybutene and lubricating oil are preferable.

  The weight average molecular weight of the polyolefin is preferably 100,000 or less and more preferably 50,000 or less in order to maintain compatibility with the acrylic polymer (A). The lower limit of the weight average molecular weight of the polyolefin is not particularly limited, but is preferably 200 or more.

  The pressure-sensitive adhesive of the present invention can further contain a tackifier resin. The tackifying resin can be used by any method such as a method used in solution polymerization or a method of blending with an acrylic polymer (A). When used in the solution polymerization, the tackifying resin acts as a chain transfer agent and makes it easy to adjust the molecular weight of the acrylic polymer (A). Moreover, when it mix | blends with an acrylic polymer (A), adhesive force can be improved more.

  The softening point of the tackifying resin is preferably 80 ° C. or higher, more preferably 90 ° C. or higher, and further preferably 100 ° C. or higher. Further, the upper limit of the softening point is preferably 170 ° C, more preferably 160 ° C, and further preferably 155 ° C. When the softening point of the tackifying resin is 80 to 170 ° C., it becomes easy to achieve both the adhesive strength and the heat resistance at a high level. The softening point is a softening temperature measured according to a dry bulb method defined in JIS K5902.

Tackifying resins include, for example, rosin resins, polymerized rosin resins, rosin ester resins, polymerized rosin ester resins, terpene resins, terpene phenol resins, coumarone resins, coumarone indene resins, styrene resins, Examples include xylene resins, phenol resins, and petroleum resins. Among these, rosin resins, polymerized rosin resins, rosin ester resins, and polymerized rosin ester resins are preferred because they have good compatibility with acrylic polymers and can improve adhesion performance, and rosin ester resins and polymers. A rosin ester resin is more preferable.
The tackifying resins can be used alone or in combination of two or more.

  The tackifying resin is preferably used in an amount of 10 to 40 parts by weight, more preferably 15 to 35 parts by weight, based on 100 parts by weight of the acrylic polymer (A). When 10 to 40 parts by weight of the tackifying resin is used, the adhesive strength and the cohesive force can be compatible at a high level, so that heat resistance is easily obtained.

  The pressure-sensitive adhesive of the present invention further includes, as optional components, a flame retardant aid, a heat resistance stabilizer, a weather resistance stabilizer, an anti-aging agent, an ultraviolet absorber, a leveling agent, an antistatic agent, a slip agent, an antiblocking agent, an antifogging agent, Lubricants, dyes, waxes, emulsions, magnetic materials, and dielectric property modifiers can be included.

  The pressure-sensitive adhesive of the present invention has a nonvolatile content concentration of 52 to 75% by weight, preferably 55 to 70% by weight, and more preferably 55 to 65% by weight. Since the content of the organic solvent (C) can be relatively suppressed by setting the non-volatile content concentration of the pressure-sensitive adhesive high, it is possible to suppress the drying cost during coating and to suppress the load on the environment and the human body.

  Further, the pressure-sensitive adhesive of the present invention preferably has a viscosity at 25 ° C. of 2000 to 20000 mPa · s, more preferably 2000 to 15000 mPa · s, and still more preferably 2000 to 10,000 mPa · s. By making the viscosity of the pressure-sensitive adhesive within an appropriate range, the coating property is improved, and a pressure-sensitive adhesive layer having a smooth surface is easily obtained. The viscosity is a viscosity measured using a BL type viscometer in an atmosphere of 25 ° C., with a # 3 rotor and a rotation speed of 12 rpm, one minute after the start of rotation.

The pressure-sensitive adhesive sheet of the present invention preferably includes a base material and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive.
The pressure-sensitive adhesive layer is formed by applying a pressure-sensitive adhesive on a substrate. Or the method of transferring the adhesive layer formed by applying an adhesive on a peeling sheet to a base material is common. In addition, it is normal to stick a release sheet on the surface which does not contact the base material of an adhesive layer, and to store it.

The substrate is preferably paper, plastic, or cloth. Moreover, the form of a base material has a preferable sheet form, plate shape, and a foam.
The material of the base material is, for example, polyolefin such as polyethylene and polypropylene (PP), polyester such as polyethylene terephthalate (PET), plastic such as polystyrene, polyvinyl chloride, polycarbonate and cellophane, fine paper, kraft paper, crepe paper, glassine Examples thereof include paper such as paper, cloth such as woven fabric and non-woven fabric, elastomer such as ethylene propylene diene rubber, chloroprene rubber and isoprene rubber, and skin.
The thickness of a base material is about 25-10000 micrometers normally.

  Examples of the adhesive coating method include known coating methods such as spin coating, spray coating, bar coating, knife coating, roll coating, roll knife coating, blade coating, die coating, and gravure coating. You can use the method. Moreover, it is also preferable to perform a drying process at the time of coating. For the drying step, a known device such as a hot air oven, an electric oven, an infrared heater or the like can be used.

  The thickness of the pressure-sensitive adhesive layer is usually about 20 to 300 μm, more preferably about 20 to 100 μm, considering the balance between cost and pressure-sensitive adhesive performance.

  The adhesive sheet of the present invention is used, for example, for fixing a vehicle top plate, floor, interior / exterior panel, masking for vehicle painting and surface treatment, product protection at the time of shipment, interior / exterior member fixing for buildings, curing concrete It can be used for various purposes such as protection, fixing of home appliance components, vending machine advertisement stickers, LCD speaker nets, bezels, decorative plate fixing, packaging, binding, temporary fixing, and the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples. In the examples, “parts” means “parts by weight” and “%” means “% by weight”.

"Example 1"
Using a polymerization apparatus equipped with a stirrer, a thermometer, a dropping tube, and a reflux condenser, 66 parts of butyl acrylate, 20 parts of 2-ethylhexyl acrylate, 5.0 parts of methyl acrylate, 3.0 parts of methyl methacrylate, acrylic acid 6. Half of the raw material mixture containing 0 part, 5 parts of methyl ethyl ketone, 65 parts of ethyl acetate and 0.1 part of benzoyl peroxide was charged into the reaction vessel under a nitrogen atmosphere. Separately, the remaining half of the raw material mixture was charged into the dropping layer. The reactor was then heated. After confirming the start of the polymerization reaction, the raw material mixture was dropped from the dropping tube over 1 hour. After completion of the dropwise addition, solution polymerization was further continued for 7 hours under reflux. After completion of the reaction, the reaction mixture was cooled to obtain an acrylic polymer solution having a nonvolatile content of 58.8%. The resulting acrylic polymer solution had a weight average molecular weight of 1,000,000 and a molecular weight dispersity of 3.8. Furthermore, 20.0 parts of tackifier resin (Arakawa Chemical Co., Ltd. Pencel D-125) with respect to 100 parts of the nonvolatile content of the acrylic polymer solution, 5.0 parts of isopropyl alcohol, 10.0 parts of ethyl acetate, ketoeenol as a diluent solvent 0.5 parts of acetylacetone as a tautomer-forming compound and 0.4 parts of aluminum trisacetylacetonate as a chelate-type curing agent were added, and after sufficient stirring, an adhesive was obtained. The adhesive had a non-volatile content of 58.5% and a viscosity of 22000 mPa · s.

"Examples 2 to 18"
Except having changed the raw material and compounding quantity of Example 1 as shown in Table 1 and Table 2, it carried out similarly to Example 1 and obtained the adhesive of Examples 2-18, respectively.

“Comparative Example 1”
Using a polymerization apparatus equipped with a stirrer, thermometer, dropping tube and reflux condenser, 45 parts of butyl acrylate, 10 parts of 2-ethylhexyl acrylate, 10 parts of isobutyl acrylate, 10 parts of ethyl acrylate, 25 parts of acrylic acid, 20 parts of methyl ethyl ketone Then, half of the raw material mixture containing 80 parts of ethyl acetate and 0.1 part of benzoyl peroxide was charged into the reaction vessel under a nitrogen atmosphere. Separately, the remaining half of the raw material mixture was charged into the dropping layer. Then, heating of the reaction vessel was started. After confirming the start of the polymerization reaction, the raw material mixture was dropped from the dropping tube over 1 hour. After completion of the dropwise addition, solution polymerization was further continued for 7 hours under reflux. After completion of the reaction, the reaction mixture was cooled to obtain an acrylic polymer solution having a nonvolatile content of 50%. The resulting acrylic polymer solution had a weight average molecular weight of 880,000 and a molecular weight dispersity of 9.5. 20.0 parts of tackifier resin (Pencel D-125) with respect to 100 parts of the nonvolatile content of the acrylic polymer solution, 20 parts of methanol as a diluting solvent, 20 parts of methyl ethyl ketone, 0.5% of acetylacetone as a ketoeenol tautomer forming compound In addition, 0.4 part of aluminum trisacetylacetonate was added as a chelate type curing agent, and after sufficient stirring, an adhesive was obtained. This adhesive had a non-volatile content of 46.1% and a viscosity of 8000 mPa · s.

"Comparative Examples 2-6"
Except having changed the raw material and compounding quantity of Comparative Example 1 as shown in Table 2, it carried out similarly to Comparative Example 1, and obtained the adhesive of Comparative Examples 2-6, respectively.

<Nonvolatile content>
The nonvolatile content was determined from the weight ratio before and after drying at 150 ° C. for 20 minutes in an electric oven.

<Viscosity>
The viscosity is a value measured 1 minute after the start of rotation at 12 rpm using a # 3 rotor at 25 ° C. with a BL type viscometer.

<Weight average molecular weight>
The weight average molecular weight (Mw) was determined under the following conditions using GPC.
GPC device: SHIMADZU Prominence Model number LC-20AD (manufactured by Shimadzu Corporation)
Column: Two TOSOH TSK-GEL α-M 7.8 * 300 (manufactured by Tosoh Corporation) Solvent: 10 mM LiBr (lithium bromide) dimethylformamide Solution flow rate: 0.5 ml / min
Temperature: 40 ° C
Sample concentration: 0.2 wt%
Sample injection volume: 100 μl
Detector: Refractive Index (wavelength 254 nm), model number RID-10A

<Pot life>
After the obtained adhesive was stored at 50 ° C. for 1 month, the viscosity was measured and the rate of increase in viscosity was calculated.
Viscosity increase rate (%) = (viscosity after 1 month at 50 ° C./viscosity immediately after blending) × 100
A: Viscosity increase rate is less than 10%. Excellent ○: Viscosity increase rate is 10% or more and less than 20%. Good Δ: Viscosity increase rate is 20% or more and less than 30%. Can be used practically.
X: Viscosity increase rate is 30% or more. Not practical.
<Coating property>
The surface of the pressure-sensitive adhesive layer formed by coating the obtained pressure-sensitive adhesive with a comma coater so that the coating speed is 30 m / min and the dry thickness is 50 μm is evaluated by coating. did. The evaluation criteria are as follows.
A: A coated surface having a smooth surface was obtained. Good.
Δ: The coated surface is not smooth. Can be used practically.
X: Roll streaks and repelling occurred on the coated surface. Not practical.

[Create adhesive sheet]
The obtained pressure-sensitive adhesive was applied to a commercially available release sheet using a comma coater so that the dry thickness was 50 μm, dried in an electric oven at 100 ° C. for 2 minutes, and after removing the solvent, the pressure-sensitive adhesive layer was thickened. A pressure-sensitive adhesive sheet was obtained by laminating a polyethylene terephthalate (PET) film having a thickness of 50 μm. This was cured for 7 days in a constant temperature and humidity chamber of 23 ° C.-50% RH atmosphere to complete the curing, and the following physical properties were evaluated.

<Adhesive strength>
The obtained adhesive sheet was cut into a size of 25 mm in width and 100 mm in length to prepare a sample. Next, in a 23 ° C.-50% RH atmosphere, in accordance with JIS Z 0237, the release sheet was peeled off from the sample, and the exposed adhesive layer was attached to a polished stainless steel (SUS) plate, followed by one reciprocating pressure with a 2 kg roll. Thereafter, the adhesive strength (N / 25 mm) was measured using a tensile tester under conditions of a peeling speed of 300 mm / min and a peeling angle of 180 ° 24 hours after sticking. Similarly, the adhesive strength was measured for a polypropylene plate.
"Vs. SUS board"
○: Adhesive strength is 20 N / 25 mm or more. Good Δ: Adhesive strength is 15 N / 25 mm or more and less than 20 N / 25 mm. Can be used practically.
X: Less than 15N / 25mm. Not practical.
"For PP board"
A: Adhesive strength is 10 N / 25 mm or more. excellence.
○: Adhesive strength is 5 N / 25 mm or more and less than 10 N / 25 mm. Good Δ: Adhesive strength is 3 N / 25 mm or more and less than 5 N / 25 mm. Can be used practically.
X: Less than 3N / 25mm. Not practical.

<Retention force>
The obtained adhesive sheet was cut into a size of 25 mm in width and 100 mm in length to prepare a sample. Next, in a 23 ° C.-50% RH atmosphere, in accordance with JIS Z 0237, the release sheet was peeled off from the sample, and the exposed adhesive layer was affixed to a polished stainless steel (SUS) plate having a tip width of 25 mm and a length of 25 mm. It was put on and reciprocally pressed with a 2 kg roll, and then a 1 kg load was applied in an 80 ° C. atmosphere and held for 70,000 seconds. Evaluation shows the number of seconds when a sample falls from a SUS board. In the case where the sample did not fall, the number of mm in which the adhesive tip portion of the pressure-sensitive adhesive layer and the SUS plate shifted downward due to the load is shown. The evaluation criteria are shown below.
◎: Sample deviation is less than 2 mm Excellent ○: Sample deviation is 2 mm or more and less than 5 mm Good Δ: Sample deviation is 5 mm or more and did not fall No problem in practical use ×: Sample fell

<Throwing property>
The adhesion between the pressure-sensitive adhesive layer and the foam base material was evaluated as anchorage. The obtained adhesive sheet was cut into a size of 25 mm in width and 100 mm in length to prepare a sample. Next, in a 23 ° C.-50% RH atmosphere, it was attached to a foam sheet (width 30 mm, length 130 mm, thickness 10 mm, ECS manufactured by INOAC) lined on a SUS plate with double-sided tape, and 1 reciprocating with a 2 kg roll. Then, using a tensile tester, the adhesive strength (N / 25 mm) was measured under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 ° after 24 hours of sticking.
A: Adhesive strength is 5 N / 25 mm or more. excellence. The substrate is broken.
○: Adhesive strength is 2 N / 25 mm or more and less than 5 N / 25 mm. With breakage of the substrate. Good Δ: Adhesive strength is 1 N / 25 mm or more and less than 2 N / 25 mm. Can be used practically.
X: Less than 1N / 25mm. Not practical.

<Transparency>
The transparency of the pressure-sensitive adhesive layer of the obtained pressure-sensitive adhesive sheet was visually evaluated. The evaluation criteria are shown below.
○: Colorless and transparent. Good.
Δ: Slight whitening and coloring. Can be used practically.
X: Severe whitening and aggregates. Not practical.

The meanings of the abbreviations in Tables 1 and 2 are as follows.
BA: butyl acrylate 2EHA: 2-ethylhexyl acrylate IBA: isobutyl acrylate IBMA: isobutyl methacrylate MA: methyl acrylate MMA: methyl methacrylate EA: ethyl acrylate Vac: vinyl acetate AA: acrylic acid MAA: methacrylic acid HEA: 2-hydroxyethyl acrylate 4HBA : 4-hydroxybutyl acrylate MEK: methyl ethyl ketone IPA: isopropyl alcohol pencel D-125: rosin ester tackifier resin pencel made by Arakawa Chemical Co. AZ: rosin ester tackifier resin superester made by Arakawa Chemical Co., Ltd. S-100: Arakawa Chemical Rosin ester tackifier resin Ultrasen 725: Tosoh ethylene-vinyl acetate copolymer Supercron 930: Japan Chlorinated polypropylene manufactured by this paper company Weight average molecular weight Approx. 70,000, chlorine content 21%
Super Clone 390: Chlorinated polypropylene manufactured by Nippon Paper Industries Co., Ltd. Weight average molecular weight 20,000, chlorine content 36%
Super Clone 370M: Chlorinated polypropylene manufactured by Nippon Paper Industries Co., Ltd. Weight average molecular weight: approx. 10,000, chlorine content: 30%
Super Clone 814B: Chlorinated polypropylene manufactured by Nippon Paper Industries Co., Ltd. Weight average molecular weight: approx. 15,000, chlorine content: 41%
PB300: Liquid polybutene manufactured by DAELIM, weight average molecular weight of about 300
Super Oil M32: Paraffin-based lubricating oil manufactured by JX Energy Ltd. Weight average molecular weight of about 400
Diana Process Oil NP-24: Idemitsu Kosan Co., Ltd. Naphthenic Lubricating Oil Weight average molecular weight about 300
Aluminum chelate A: Aluminum Tris (acetylacetonate) manufactured by Kawaken Finechem
TDI-TMP solution: Trimethylolpropane adduct of tolylene diisocyanate (nonvolatile content 37.5%)

  From the results of Table 3 and Table 4, the adhesives of Examples 1 to 18 all have a good pot life and are excellent in adhesion and heat resistance. The heat resistance was determined from the result of holding power.

Claims (7)

A monomer mixture containing acidic group-containing monomer (a1) 6-18% by mass and 2-ethylhexyl acrylate 15-94% by mass , and an acrylic polymer (A) which is a reaction product of a chain transfer compound , chelate type curing agent ( B), and the organic solvent (C) (provided that the alcohol (D) is excluded), and alcohol (D) and keto - see including at least one of the enol tautomer form compound (E),
The chain transfer compound is a pressure-sensitive adhesive having a nonvolatile content concentration of 52 to 75% by mass , including one selected from the group consisting of methyl ethyl ketone, thiol and tackifying resin .   The pressure-sensitive adhesive according to claim 1, wherein the monomer mixture further contains a hydroxyl group-containing monomer.   Furthermore, the adhesive of Claim 1 or 2 containing polyolefin.   The pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the acrylic polymer (A) has a weight average molecular weight of 300,000 to 900,000.   The pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the acrylic polymer (A) has a molecular weight dispersity of 3 to 12.   The adhesive of any one of Claims 1-5 whose viscosity in 25 degreeC of an adhesive is 2000-20000 mPa * s. The adhesive sheet provided with the base material and the adhesive layer which is a hardened | cured material of the adhesive of any one of Claims 1-6.