JP6849014B2 - Adhesives and adhesive sheets for films - Google Patents

Description

The present invention relates to a film pressure-sensitive adhesive.

Adhesive sheets having an adhesive layer formed from solvent-based adhesives are used in a wide range of fields as labels and adhesive sheets because they are easy to handle, and adhesive sheets suitable for the application are selected in various environments. ing. For example, adhesive sheets used in gas ranges around kitchens are required not to float or peel off even if cooking oil adheres to them, and adhesive sheets used for fixing automobile wiring and parts. However, there is a demand for an oil-resistant adhesive that is less likely to deteriorate due to various oils.

In general, an adhesive sheet is, for example, coated with an adhesive on a base material, dried to form an adhesive layer, laminated with a peelable sheet, wound into a roll, cured, and stored. Will be done. However, the adhesive sheet wound in a roll shape has dents (or indentations) due to the winding pressure because the adhesive layer immediately after coating is soft when foreign matter adheres to the surface of the adhesive sheet during winding. A phenomenon called may occur. Adhesive sheets with dents cannot be used because they spoil the appearance, especially in applications that require design and transparency, such as label films and optical films, and have the problem of low yield and poor productivity. It was.
In addition, from the viewpoint of energy saving, in order to reduce the thermal energy that volatilizes the organic solvent when applying the adhesive, efforts are being made to reduce the amount of the organic solvent used and to increase the coating speed. However, simply reducing the amount of the organic solvent and making it highly non-volatile causes the pressure-sensitive adhesive to have a high viscosity, which causes a problem of coatability.

Therefore, Patent Document 1 contains an aqueous dispersion type polymer and inorganic particles in terms of oil resistance, and the content ratio of the inorganic particles is 3 to 90 mass by mass with respect to 100 parts by mass of the aqueous dispersion type polymer. A water-dispersible pressure-sensitive adhesive, which is characterized by being a part, is disclosed.

Further, Patent Document 2 describes an adhesive containing a (meth) acrylic copolymer, 0.005 to 10 parts by mass of a curing agent, and 5 parts by mass or more and less than 50 parts by mass of metal-containing nanoparticles in terms of improving the yield. The agent is disclosed.

Further, Patent Document 3 describes an acrylic copolymer having a weight average molecular weight of 50,000 to 300,000 and an organic solvent having a chain transfer constant of vinyl acetate to an organic solvent at 60 ° C. of 250 or more in terms of highly non-volatile differentiation. A pressure-sensitive adhesive containing 60% or more of a non-volatile content is disclosed.

Japanese Unexamined Patent Publication No. 2012-117053 Japanese Unexamined Patent Publication No. 2013-216725 Japanese Unexamined Patent Publication No. 2011-246700

However, the pressure-sensitive adhesive of Patent Document 1 has a problem that when inorganic particles are used to impart oil resistance, it causes separation of the water-dispersed polymer and the inorganic particles, and the solution stability of the pressure-sensitive adhesive is lowered. .. Further, the pressure-sensitive adhesive of Patent Document 2 was able to improve the dents, but since the non-volatile content of the pressure-sensitive adhesive was as low as about 17%, it was necessary to suppress the coating speed from the viewpoint of dryness when producing the pressure-sensitive adhesive sheet. There was a problem of low productivity. Further, Patent Document 3 has a problem that the cohesive force is low and dents are likely to occur because the molecular weight of the acrylic copolymer is suppressed by using an organic solvent having a high chain transfer effect.

An object of the present invention is to provide an adhesive and an adhesive sheet capable of forming an adhesive sheet having good oil resistance and less likely to cause dents.

The adhesive for film of the present invention contains an acrylic copolymer obtained by copolymerizing a monomer mixture containing an acrylic acid alkyl ester, a methacrylate alkyl ester, and a hydrogen-binding monomer, a curing agent, and an organic solvent. , The hydrogen-binding monomer contains a carboxyl group-containing monomer in an amount of 3 to 15% by weight in 100% by weight of the monomer mixture.

According to the above invention, the oil resistance could be improved by using an acrylic acid alkyl ester, a methacrylic acid alkyl ester, and a hydrogen bonding monomer as the monomers. Further, the cohesive force of the acrylic copolymer itself could be enhanced by polymerizing a monomer mixture containing 2 to 15% by weight of a carboxyl group-containing monomer as a hydrogen-bonding monomer. As a result, the pressure-sensitive adhesive of the present invention has a cohesive force that can withstand the winding pressure when the pressure-sensitive adhesive sheet is wound immediately after coating, in which the cross-linking reaction between the curing agent and the acrylic copolymer has hardly progressed. Therefore, the effect of making dents less likely to occur was obtained.

INDUSTRIAL APPLICABILITY According to the present invention, the present invention can provide an adhesive and an adhesive sheet capable of forming an adhesive sheet having good oil resistance and less likely to cause dents.

Before explaining the present invention in detail, terms are defined. First, sheet, film and tape are synonyms. (Meta) acrylic acid includes acrylic acid and methacrylic acid. (Meta) acrylates include acrylates and methacrylates. The monomer is an ethylenically unsaturated double bond-containing monomer. A hydrogen-bonding monomer is a monomer having a hydrogen-bonding hydrogen atom in the molecule. The adherend is the other party to which the adhesive sheet is attached. The number of functional groups is the average number.

The adhesive for film of the present invention contains an acrylic copolymer obtained by copolymerizing a monomer mixture containing an acrylic acid alkyl ester, a methacrylate alkyl ester, and a hydrogen-binding monomer, a curing agent, and an organic solvent. , The hydrogen-binding monomer contains a carboxyl group-containing monomer in an amount of 3 to 15% by weight in 100% by weight of the monomer mixture.

Further, the film pressure-sensitive adhesive of the present invention can be coated even when the non-volatile content is set to 50% by weight or more by the above configuration, so that productivity and cost reduction can be improved.
The film pressure-sensitive adhesive of the present invention is preferably used as a pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer formed by coating. In addition, "for film" means using a plastic film as a base material.

In the present invention, the acrylic copolymer is a polymer obtained by copolymerizing a monomer mixture containing an acrylic acid alkyl ester, a methacrylate alkyl ester, and a hydrogen-bonding monomer by solution polymerization. As the polymerization method of copolymerization, solution polymerization is preferable from the viewpoint of excellent transparency and easy molecular weight adjustment. In addition, in this specification, solution polymerization includes a polymerization method which does not use water as a solvent such as ultraviolet polymerization and bulk polymerization.

The acrylic acid alkyl ester preferably uses 50 to 85% by weight, more preferably 60 to 80% by weight, in 100% by weight of the monomer mixture. When an acrylic acid alkyl ester is used, it becomes easy to achieve both adhesive strength and cohesive strength.

Acrylic acid alkyl esters include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, pentyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, acrylic. 2-Ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, n-decyl acrylate, isodecyl acrylate, dodecyl acrylate, tetradecyl acrylate, hexadecyl acrylate, n-octadecyl acrylate, isooctadecyl acrylate, and acrylic Examples thereof include isobornyl acid acid. The structure of the alkyl chain may have any of a linear structure, a branched structure, and a cyclic structure. Among these, an alkyl chain having a linear structure or a branched structure is preferable, and n-butyl acrylate is particularly preferable because it is easy to obtain a sticky physical property having a good balance between adhesive force and cohesive force.
Acrylic acid alkyl esters can be used alone or in combination of two or more.

The methacrylic acid alkyl ester has a higher glass transition temperature (hereinafter, also referred to as Tg) of the homopolymer as compared with the acrylic acid alkyl ester, and has a function of increasing the Tg of the acrylic copolymer. Since the cohesive force of the polymer itself is improved, it contributes to the suppression of dents. As the methacrylic acid alkyl ester, 5 to 25% by weight is preferably used in 100% by weight of the monomer mixture, and 10 to 20% by weight is more preferable. Adhesive strength and cohesive strength are improved in a well-balanced manner by using in the range of 5 to 25% by weight.
The Tg of the homopolymer of the methacrylic acid alkyl ester is preferably 10 ° C to 200 ° C. The cohesive force is further improved when the Tg is 10 ° C. to 200 ° C.
The Tg of the homopolymer uses the literature value.

The alkyl methacrylate ester is, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, pentyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, methacrylic. 2-Ethylhexyl acid acid, n-octyl methacrylate, isooctyl methacrylate, n-decyl methacrylate, isodecyl methacrylate, dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, n-octadecyl methacrylate, isooctadecyl methacrylate, and methacrylic. Examples thereof include isobornyl acid acid. The structure of the alkyl chain may have any of a linear structure, a branched structure, and a cyclic structure. Among these, methyl methacrylate (Tg: 105 ° C.), ethyl methacrylate (Tg: 65 ° C.), propyl methacrylate (Tg: 35 ° C.), n-methacrylate having a homopolymer Tg of 10 ° C. to 200 ° C. Butyl (Tg: 20 ° C), isobutyl methacrylate (Tg: 53 ° C), t-butyl methacrylate (Tg: 118 ° C), cyclohexyl methacrylate (Tg: 83 ° C), isobornyl methacrylate (Tg: 180 ° C) Preferably, an alkyl methacrylate ester having an alkyl chain having a linear structure or a branched structure is more preferable.
The Tg values of the monomers other than these are the values described in the 3rd edition of the Polymer Handbook.
The methacrylic acid alkyl ester may be used alone or in combination of two or more.

Further, the methacrylic acid alkyl ester can achieve both adhesive strength and cohesive strength more highly by using a monomer having an alkyl group having 1 to 2 carbon atoms and a monomer having an alkyl group having 3 to 10 carbon atoms in combination. .. Specifically, 3 to 20% by weight of a monomer having an alkyl group having 1 to 2 carbon atoms and 2 to 20% by weight of a monomer having an alkyl group having 3 to 10 carbon atoms in 100% by weight of the monomer mixture. It is preferable to contain 5 to 15% by weight of a monomer having an alkyl group having 1 to 2 carbon atoms, and more preferably 5 to 15% by weight of a monomer having an alkyl group having 3 to 10 carbon atoms. ..

In the present invention, the hydrogen-bonding monomer contributes to the improvement of the cohesive force of the acrylic copolymer itself by forming a hydrogen bond in the acrylic copolymer or between the acrylic copolymers, and suppresses dents. Therefore, it is necessary to include a carboxyl group-containing monomer in an amount of 3 to 15% by weight in 100% by weight of the monomer mixture, which requires a certain amount or more of the monomer amount.
In addition to the carboxyl group-containing monomer, one or more hydrogen-bonding monomers selected from the group consisting of an amide group-containing monomer, a hydroxyl group-containing monomer, a urea bond-containing monomer, a urethane bond-containing monomer, and the like can be used in combination. In this case, the hydrogen-bonding monomer contains 7 to 25% by weight in 100% by weight of the monomer mixture, and the monomer mixture 100 contains one or more monomers selected from the group consisting of an amide group-containing monomer and a hydroxyl group-containing monomer. It is preferable to include 4 to 20% by weight in% by weight. With the above formulation, it is possible to increase the room for adjusting the physical properties while forming a desired hydrogen bond and suppressing dents. When the amide group-containing monomer and the hydrogen-bonding monomer are used, the polarity of the pressure-sensitive adhesive is increased and the oil resistance can be improved.

Carboxyl group-containing monomers include, for example, (meth) acrylic acid, monohydroxyethyl phthalic acid ester, p-carboxybenzyl acrylic acid ester, ethylene oxide-modified (EO addition molars: 2-18) phthalic acid acrylic acid ester, phthalate. Acid monohydroxypropyl acrylic acid ester, succinic acid monohydroxyethyl acrylic acid ester, acrylic acid β-carboxyethyl, acrylic acid 2- (4-benzoyl-3-hydroxyphenoxy) ethyl, maleic acid, monoethyl maleic acid, itaconic acid , Citraconic acid, fumaric acid and the like. Among these, (meth) acrylic acid is preferable.
The carboxyl group-containing monomer may be used alone or in combination of two or more.

The carboxyl group-containing monomer needs to contain 3 to 15% by weight out of 100% by weight of the monomer mixture, more preferably 4 to 12% by weight. When a hydrogen-bonding monomer other than the carboxyl group-containing monomer is used in combination, the carboxyl group-containing monomer preferably contains 4 to 12% by weight out of 100% by weight of the monomer mixture, more preferably 4 to 10% by weight. preferable. When the carboxyl group-containing monomer is contained in an amount of 3 to 15% by weight, characteristics such as suppression of dents, improvement of adhesive strength, and improvement of oil resistance can be obtained.

The amide group-containing monomer is a monomer having an amide group and having one or two hydrogen atoms bonded to a nitrogen atom, for example, (meth) acrylamide, N-methylacrylamide, N-isopropylacrylamide, and diacetone. Examples thereof include (meth) acrylamide such as acrylamide, N- (hydroxymethyl) acrylamide, and N- (butoxymethyl) acrylamide, N-vinylformamide, N-vinylacetamide and the like. Of these, (meth) acrylamide is preferred. The monomer having an amide group but not having a hydrogen atom bonded to a nitrogen atom and having no hydrogen bonding property is not included in the amide group-containing monomer of the present invention.

The hydroxyl group-containing monomers include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and (meth) acrylic. (Meta) Acrylic Acid Hydroxyalkyl Esters such as 3-Hydroxybutyl Acid, 4-Hydroxybutyl (Meta) Acrylic Acid, 6-Hydroxyhexyl (Meta) Acrylic Acid, 8-Hydroxyoctyl (Meta) Acrylic Acid;
Glycol mono (meth) acrylic acid esters such as polyethylene glycol mono (meth) acrylic acid ester, polypropylene glycol mono (meth) acrylic acid ester, 1,4-cyclohexanedimethanol mono (meth) acrylic acid ester;
Caprolactone-modified (meth) acrylic acid ester, hydroxyethyl acrylamide and the like can be mentioned. Of these, 2-hydroxyethyl (meth) acrylate is preferable.

Examples of the urea bond-containing monomer include a monomer obtained by reacting an amino group-containing monomer with a monofunctional isocyanate compound, a monomer obtained by reacting an isocyanate group-containing monomer with a monofunctional amine compound, and the like.

Examples of the urethane bond-containing monomer include a monomer obtained by reacting a hydroxyl group-containing monomer with a monofunctional isocyanate compound, a monomer obtained by reacting an isocyanate group-containing monomer with a monofunctional alcohol compound, and the like.
The hydrogen-bonding monomer may be used alone or in combination of two or more.

The monomers other than the acrylic acid alkyl ester, the methacrylate alkyl ester, and the hydrogen-bonding monomer used for the synthesis of the acrylic copolymer are an epoxy group-containing monomer, an amino group-containing monomer, an aromatic ring-containing monomer, and an alkoxy (poly) alkylene. Examples thereof include oxide-containing monomers and other vinyl monomers.

Epoxy group-containing monomers include, for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, and 6-methyl-3,4-epoxy (meth) acrylate. Cyclohexylmethyl and the like can be mentioned. The epoxy group-containing monomer preferably contains 0.01 to 5 parts by weight in 100% by weight of the monomer mixture.

Amino group-containing monomers include (meth) monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, and monoethylaminopropyl (meth) acrylate. Acrylic acid monoalkylamino ester can be mentioned. The amino group-containing monomer preferably contains 0.01 to 1 part by weight in 100% by weight of the monomer mixture.

The aromatic ring-containing monomer is, for example, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, ethylene oxide-modified nonylphenol (meth) acrylate, (meth). Examples thereof include biphenyl acrylate, styrene, vinyltoluene, and α-methylstyrene. The aromatic ring-containing monomer preferably contains 1 to 15 parts by weight in 100% by weight of the monomer mixture.

Examples of the alkoxy (poly) alkylene oxide-containing monomer include 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-phenoxyethyl acrylate, methoxypolyethylene glycol (meth) acrylic acid ester, and ethoxypolyethylene glycol (meth) acrylic acid. Examples thereof include esters, methoxypolypropylene glycol (meth) acrylic acid esters, ethoxypolypropylene glycol (meth) acrylic acid esters, phenoxypolyethylene glycol (meth) acrylic acid esters, and phenoxypolyethylene glycol (meth) acrylic acid esters. The alkoxy (poly) alkylene oxide-containing monomer preferably contains 1 to 15 parts by weight in 100% by weight of the monomer mixture.

Examples of other vinyl monomers include vinyl acetate and acrylonitrile. The other vinyl monomer preferably contains 1 to 15 parts by weight in 100% by weight of the monomer mixture.

The acrylic copolymer of the present invention is obtained by solution-polymerizing a monomer mixture using a radical polymerization initiator. Solution polymerization can be carried out by radical polymerization using 0.001 to 1 part by weight of a radical polymerization initiator with respect to 100 parts by weight of the monomer mixture in the presence of an organic solvent. Usually, radical polymerization can be carried out under a nitrogen stream at a temperature of about 50 ° C. to 90 ° C. for 6 hours to 20 hours. Further, in the case of radical polymerization, the weight average molecular weight of the acrylic copolymer can be appropriately adjusted by using a chain transfer agent.

Chain transfer agents include, for example, n-dodecyl mercaptan, mercaptoisobutyl alcohol, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglucolate, 2,3-dimercapto-1-propanol, glycidyl mercaptan, α-methylstyrene. Dimer, carbon tetrachloride, chloroform, hydroquinone and the like can be mentioned.

The radical 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 (cyclohexane1-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), and 2,2'-azobis (2- (2- (2-)
Imidazoline-2-yl) propane) and the like.

Organic peroxides include, for example, benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxy dicarbonate, di-n-propyl peroxy dicarbonate, di (2-ethoxyethyl) peroxy dicarbonate. , T-Butylperoxyneodecanoate, t-Butylperoxyvivarate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.
The radical polymerization initiator may be used alone or in combination of two or more.

In the present invention, the weight average molecular weight of the acrylic copolymer is preferably 150,000 to 400,000, more preferably 200,000 to 400,000. By setting the weight average molecular weight in the range of 150,000 to 400,000, it is possible to achieve both adhesive physical properties and coatability at a high level. In the present invention, the weight average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

In the present invention, the acrylic copolymer preferably has a viscosity at 25 ° C. of 1,000 to 20,000 mPa · s when the non-volatile content is adjusted to 50 to 65% by weight with an organic solvent, and the viscosity is 1, More preferably, it is 500 to 15,000 mPa · s. By setting these non-volatile components and viscosities, it is possible to reduce the amount of organic solvent used as compared with conventional adhesives and further shorten the drying time while ensuring coatability. The viscosity is the viscosity measured 1 minute after the start of rotation at 30 rpm with a # 4 rotor using a B-type viscometer in an atmosphere of 25 ° C.

The film pressure-sensitive adhesive of the present invention has a high cohesive force of the pressure-sensitive adhesive layer immediately after coating in which curing has hardly progressed and can suppress dents, so that the yield of the pressure-sensitive adhesive sheet is high and the productivity is excellent. Specifically, an adhesive sheet having an adhesive layer thickness of 25 μm obtained by blending, coating, and drying a curing agent is applied within 10 minutes after coating, with an area of 25 × 25 cm ² , and 1 kg at 23 ° C. and 50% relative humidity. It can be evaluated by the holding force when the load of 1 hour is applied (hereinafter referred to as the holding force immediately after coating), and the deviation of the adhesive sheet of the holding force immediately after coating is preferably 10 mm or less, preferably 3 mm or less. Is more preferable. By making the deviation of the holding force immediately after coating 10 mm or less, it is possible to reduce the dents when producing the adhesive sheet.

In the present invention, the curing agent is preferably one or more selected from the group consisting of isocyanate compounds, epoxy compounds, ethyleneimine compounds, metal chelate compounds, and amine compounds, and is more preferable than epoxy compounds and metal chelate compounds. By using an epoxy compound or a metal chelate compound, an appropriate crosslink density can be obtained when an alcohol solvent is used as the organic solvent in order to increase the non-volatile content concentration of the pressure-sensitive adhesive.

Examples of the epoxy compound include bisphenol A-epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, and the like. Trimethylol Propane triglycidyl ether, diglycidyl aniline, N, N, N', N'-tetraglycidyl-m-xylylene diamine, 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane, and N , N, N', N'-tetraglycidylaminophenylmethane and the like.

The ethyleneimine compound is, for example, N, N'-diphenylmethane-4,4'-bis (1-
Aziridine carboxite), N, N'-toluene-2,4-bis (1-aziridine carboxite), bisisophthaloyl-1- (2-methylaziridine), tri-1-aziridinylphosphine oxide, N , N'-hexamethylene-1,6-bis (1-aziridinecarbokisite), 2,2'-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], trimethylolpropane tri-β-azinate Examples thereof include lysinyl propionate, tetramethylolmethanetri-β-aziridinyl propionate, and tris-2,4,6- (1-aziridinyl) -1,3,5-triazine.

Examples of the metal chelate compound include a coordination compound of a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium with acetylacetone and ethyl acetoacetate. ..

Examples of the amine compound include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resin and methylene resin.

As the isocyanate compound, a bullet form, a nurate form, an adduct form and the like obtained by modifying an isocyanate monomer such as an aromatic diisocyanate, an aliphatic diisocyanate, an aromatic aliphatic diisocyanate and an alicyclic diisocyanate having two isocyanate groups are preferable.
The aromatic diisocyanate is, for example, 1,3-phenylenediisocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylenediocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate. Examples thereof include isocyanate, 4,4'-toluidine diisocyanate, dianisidine diisocyanate, and 4,4'-diphenyl ether diisocyanate.
Aliphatic diisocyanates include, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2, Examples thereof include 4,4-trimethylhexamethylene diisocyanate.
Examples of the aromatic aliphatic diisocyanate include xylylene diisocyanate, ω, ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate.
The alicyclic diisocyanate is, for example, 3-isocyanate methyl-3,5,5-trimethylcyclohexylisocyanate (also known as IPDI, isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexanediisocyanate, 1,4-cyclohexane. Examples thereof include diisocyanate, methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4′-methylenebis (cyclohexylisocyanate), and 1,4-bis (isocyanatemethyl) cyclohexane.

The burette body is a self-condensate having a burette bond formed by self-condensation of an isocyanate monomer, and examples thereof include a burette body of hexamethylene diisocyanate.
The nurate form is a trimer of an isocyanate monomer, and examples thereof include a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, and a trimer of tolylene diisocyanate.
The adduct is a trifunctional or higher functional isocyanate compound obtained by reacting the above isocyanate monomer with a trifunctional or higher low molecular weight active hydrogen-containing compound. For example, a compound obtained by reacting trimethylolpropane with hexamethylene diisocyanate. , A compound obtained by reacting trimethylolpropane and tolylene diisocyanate, a compound obtained by reacting trimethylolpropane and xylylene diisocyanate, a compound obtained by reacting trimethylolpropane and isophorone diisocyanate, and the like.

The film pressure-sensitive adhesive of the present invention preferably contains 0.01 to 5 parts by weight of a curing agent, more preferably 0.01 to 3 parts by weight, based on 100 parts by weight of the acrylic copolymer. When the content of the curing agent is 0.01 to 5 parts by weight, adhesion to the adherend and sufficient cohesive force can be obtained.

In the present invention, the organic solvent is used as a reaction solvent for solution polymerization of the acrylic copolymer and a diluting solvent after the synthesis of the acrylic copolymer. The organic solvent preferably has a boiling point of 150 ° C. or lower at 25 ° C. and 1 atm. When the temperature is 150 ° C. or lower, the organic solvent volatilizes when the adhesive is applied and dried, and it becomes easy to remove it. Examples of the organic solvent include ester solvents such as methyl acetate, ethyl acetate, n-butyl acetate and isobutyl acetate, hydrocarbon solvents such as toluene, xylene and hexane, and ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone. Examples thereof include alcohol solvents such as methanol, ethanol, n-propanol and isopropanol. Among these, as the reaction solvent, it is preferable to use ethyl acetate as a main component and to use an alcohol solvent in combination because it is easy to adjust the molecular weight to an appropriate level. As the diluting solvent, an alcohol solvent is preferable because it can suppress an increase in the viscosity of the pressure-sensitive adhesive, and a primary alcohol solvent is more preferable. Examples of the primary alcohol solvent include methanol and ethanol. Since the alcohol-based solvent hydrogen-bonds to functional groups such as carboxyl groups, hydroxyl groups, and amide groups of the acrylic-based copolymer, hydrogen bonds between the acrylic-based copolymers can be appropriately suppressed, so that the viscosity of the film pressure-sensitive adhesive is high. Decreases. On the other hand, since the alcohol solvent is removed when the pressure-sensitive adhesive is applied and dried, it does not suppress hydrogen bonds between the acrylic copolymers in the pressure-sensitive adhesive layer. Therefore, since the cohesive force of the pressure-sensitive adhesive layer immediately after coating can be maintained, it does not affect the suppression of dents.

The organic solvent preferably contains 40 to 150 parts by weight with respect to 100 parts by weight of the acrylic copolymer, and more preferably 55 to 100 parts by weight. As the organic solvent, a single solvent or two or more kinds can be appropriately selected.

The pressure-sensitive adhesive of the present invention may further contain a pressure-imparting resin. Adhesive strength is further improved by including the adhesive resin.

As the tackifier resin, for example, a rosin derivative, a polyterpene resin, an aliphatic hydrocarbon resin, an aliphatic petroleum resin, an aromatic petroleum resin, an alkylphenol formaldehyde resin (oil-based phenol resin) and the like are preferable. The tackifier resin may be used alone or in combination of two or more.

The tackifier resin is preferably blended in an amount of 5 to 30 parts by weight, more preferably 5 to 20 parts by weight, based on 100 parts by weight of the acrylic copolymer.

The pressure-sensitive adhesive of the present invention may further contain a silane coupling agent.

Silane coupling agents include, for example, 3- (meth) acryloxipropyltrimethoxysilane, 3- (meth) acryloxipropyltriethoxysilane, 3- (meth) acryloxipropyltripropoxysilane, 3- (meth) acryloxi. An alkoxysilane compound having a (meth) acryloxy group, such as propyltributoxysilane, 3- (meth) acryloxipropylmethyldimethoxysilane, and 3- (meth) acryloxipropylmethyldiethoxysilane;
Alkoxysilane compounds having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, and 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) An alkoxysilane compound having an amino group such as -3-aminopropylmethyldiethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane;
An alkoxysilane compound 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, An alkoxysilane compound having an epoxy group such as 3-glycidoxypropylmethyldiethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane;
Tetraalkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and 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-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyl Examples thereof include triethoxysilane, hexamethyldisilazane, and silicone resins having an alkoxysilyl group in the molecule.
The silane coupling agent can contain 0.001 to 3 parts by weight with respect to 100 parts by weight of the acrylic copolymer.

The film pressure-sensitive adhesive of the present invention has various resins, curing catalysts, oils, softeners, dyes, pigments, antioxidants, ultraviolet absorbers, weather-resistant stabilizers, and plasticizers as optional components as long as the problems can be solved. , Filler, anti-aging agent, anti-static agent and the like may be blended.

The pressure-sensitive adhesive sheet of the present invention includes a base material and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive for a film of the present invention. As another aspect, a double-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive layers on both sides of the core material, or a cast pressure-sensitive adhesive sheet having no base material and core material and composed only of the pressure-sensitive adhesive layer is also preferable. The pressure-sensitive adhesive layer can be formed by applying a pressure-sensitive adhesive onto a substrate and drying it. Alternatively, the pressure-sensitive adhesive can be applied onto a peelable sheet, dried to form a pressure-sensitive adhesive layer, and then the base materials are bonded together. It is usual to attach a peelable sheet to the surface of the pressure-sensitive adhesive layer that does not come into contact with the base material or core material and store it.

The base material is preferably cellophane, plastic, rubber, foam or the like. The shape of the base material can be selected from a plate shape and a film shape, but a film that is easy to handle is preferable. As the base material, a single material or a laminated body of two or more types can be used.

The core material is preferably non-woven fabric or plastic.

The peelable sheet has a peeling treatment on the surface of paper, plastic, or the like. For the peeling treatment, a silicone-based release agent or a fluorine-based release agent is usually used.

The plastic is a polyolefin such as polyvinyl alcohol, triacetyl cellulose, polypropylene, polyethylene, polycycloolefin, ethylene-vinyl acetate copolymer;
Examples thereof include polyester polycarbonate such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polynorbornene, polyarylate, polyacrylic, polyphenylene sulfide, polystyrene, polyamide, polyimide and epoxy.

The method of applying the adhesive is not particularly limited, and known coating methods such as Meyer bar, applicator, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, knife coater, reverse coater, spin coater, etc. Construction equipment can be used. The drying method is not particularly limited, and a known drying device such as hot air drying, infrared ray, or decompression method can be used. The drying temperature is usually about 60 to 160 ° C.

The thickness of the pressure-sensitive adhesive layer is usually about 1 to 300 μm, preferably 1 to 100 μm. The adhesive physical properties can be adjusted to an appropriate range by being in the range of 1 to 300 μm.

The adhesive strength of the pressure-sensitive adhesive sheet of the present invention is preferably 15 N / 25 mm or more, and more preferably 18 N / 25 mm or more with respect to the stainless steel (SUS) plate of the adherend. Since the adhesive strength is 15 N / 25 mm or more, it is unlikely to come off from the adherend. The higher the adhesive strength, the better, so there is no need for an upper limit, but if it is strongly mentioned, it will be about 30 N / 25 mm.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention preferably has a gel fraction of 40 to 75% by weight, more preferably 45 to 70% by weight. When the gel fraction is 40 to 75% by weight, both adhesion and cohesive force can be achieved at a higher level. In the present invention, the gel fraction is 50 by attaching an adhesive sheet of a predetermined size to a SUS200 mesh (approx. Opening: 0.077 mm, wire diameter: about 0.05 mm) and then immersing it in ethyl acetate. It is a numerical value calculated by the following formula (1) after extraction at ° C. for 24 hours and then drying at 100 ° C. for 30 minutes.
Formula (1) Gel fraction (% by weight) = (G2 / G1) x 100
G1: Weight of pressure-sensitive adhesive layer before extraction with ethyl acetate
G2: Weight of adhesive layer after extraction and drying with ethyl acetate

The adhesive of the present invention is suitable as an adhesive for sticking around kitchens and automobiles where oil resistance is required, as well as general labels / seals, adhesive optical films, paints, elastic wall materials, coating waterproof materials, etc. Flooring materials, adhesives, adhesives, adhesives for laminated structures, sealants, 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-hard, soft), urethane RIM, UV / EB curable resin, high solid paint, heat-curable elastomer, microcellular, fiber processing agent, plasticizer, sound absorbing material , Anti-vibration material, surfactant, gel coating agent, resin for artificial marble, impact resistance imparting agent for artificial marble, resin for ink, film (laminate adhesive, protective film, etc.), resin for laminated glass, reactive diluent It can be very usefully used as a raw material for various molding materials, elastic fibers, artificial leathers, synthetic leathers, etc., and also as various resin additives and raw materials thereof.

Next, examples of the present invention will be shown and further described in detail, but the present invention is not limited thereto. In the example, "part" means "part by weight" and "%" means "% by weight".

(Example 1)
[Synthesis of acrylic copolymer]
In a reaction vessel (hereinafter, simply referred to as “reaction vessel”) equipped with a stirrer, a thermometer, a reflux condenser, a dropping tube, and a nitrogen introduction tube, under a nitrogen atmosphere, 82 parts of n-butyl acrylate as a monomer and methacryl Methyl acid acid 10 parts, acrylic acid 8 parts, ethyl acetate 82 parts as a reaction solvent, 2,2'-azobisisobutyronitrile (hereinafter referred to as "AIBN") 0.0 as an initiator.
Half of the 7 parts of the raw material mixture was charged into the reaction vessel, and the other half was charged into the dropping tube. The reaction vessel was heated with stirring, and after confirming reflux, the raw material mixture in the dropping tube was added dropwise over 1 hour, and then the reaction was carried out at the reflux temperature for 2 hours. Then, 0.05 part of AIBN was added to the reaction solution, and the reaction was continued for another 5 hours. Then, the reaction vessel was cooled, and 15 parts of ethyl acetate was added as a diluting solvent to obtain an acrylic copolymer solution.

The non-volatile content, viscosity, and weight average molecular weight of the obtained acrylic copolymer solution were determined according to the following methods. The results are shown in Table 1.

<Measurement of non-volatile content>
The measurement of the non-volatile content was determined from the weight ratio before and after drying in an electric oven at 150 ° C. for 20 minutes.

<Measurement of viscosity>
The viscosity was measured at 25 ° C. with a B-type viscometer at 30 rpm using a # 4 rotor 1 minute after the start of rotation.

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

[Creation of adhesive sheet]
With respect to 100 parts of the acrylic copolymer in the obtained acrylic copolymer solution, 5 parts of the isocyanate compound Coronate L (trimethylol propane adduct of tolylene diisocyanate: manufactured by Nippon Polyurethane Industry Co., Ltd.) was added as a curing agent (made by Nippon Polyurethane Industry Co., Ltd.) A non-volatile component equivalent) was blended to obtain a pressure-sensitive adhesive.
The obtained adhesive is coated on a removable sheet (made of polyethylene terephthalate (PET)) having a thickness of 38 μm with an applicator so that the thickness after drying becomes 25 μm, and dried at 100 ° C. for 1 minute. This formed an adhesive layer. Next, a base material having a thickness of 50 μm (made of polyethylene terephthalate, hereinafter referred to as PET sheet) is attached to this pressure-sensitive adhesive layer and aged for one week under the condition of a temperature of 23 ° C. and a relative humidity of 50%. An adhesive sheet having a structure of "adhesive layer / PET sheet" was obtained.

The obtained adhesive sheet was evaluated for gel fraction, holding power immediately after coating, denting property, adhesive force, holding power, and oil resistance according to the following methods. The results are shown in Table 1.

(Examples 2 to 11)
Examples 2 to 11 and Comparative Examples 1 to 2, 4 were carried out in the same manner as in Example 1 except that the blending amounts of the monomer, the organic solvent (reaction solvent, diluting solvent) and the curing agent were in accordance with the description in Table 1. The polymer and the pressure-sensitive adhesive sheet of the above were obtained. In Comparative Example 3, since gelation occurred during the reaction, an acrylic copolymer could not be obtained.
However, Examples 1 to 4, 6, 8 to 11 are reference examples.

The abbreviations and compounds in Table 1 are listed below.
n-BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate n-BMA: n-butyl methacrylate 2EHMA: 2-ethylhexyl methacrylate (Tg = -10 ° C)
AA: AAm acrylate: Acrylamide 2HEA: 2-Hydroxyethyl acrylate Isocyanate compound: Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.)
Epoxy compound: TETRAD X (manufactured by Mitsubishi Gas Chemical Company)
Metal chelate compound: Aluminum chelate A (manufactured by Kawaken Fine Chemical Co., Ltd.)

(1) Holding force immediately after coating An adhesive sheet immediately after coating was prepared to a size of 25 mm in width and 150 mm in length. A stainless steel plate with a width of 30 mm and a length of 150 mm (stainless steel plate with a width of 30 mm and a length of 150 mm) by peeling the peelable sheet from the adhesive sheet within 10 minutes from coating under an atmosphere of 23 ° C. and 50% relative humidity in accordance with JIS Z0237: 2000. After sticking to the lower end of SUS) with a width of 25 mm and a length of 25 mm and crimping it back and forth with a 2 kg roll, apply a load of 1 kg in an atmosphere of 23 ° C and 50% relative humidity and leave it for 1 hour to increase the holding power. It was measured. The evaluation was carried out based on the following evaluation criteria by measuring the length at which the upper end of the adhesive sheet sticking surface was displaced downward.
⊚: “The misaligned length is less than 3 mm. Very good.”
◯: “The misaligned length is 3 mm or more and less than 10 mm. Good.”
X: "The misaligned length is 10 mm or more or the weight falls. It is not practical."

(2) Immediately after denting coating, two samples having a width of 100 mm and a length of 100 mm were prepared. One of the samples was allowed to stand on a glass plate at 23 ° C. and a relative humidity of 50% with the adhesive sheet facing up. Within 10 minutes from the coating, a columnar weight having a diameter of 4 cm and a weight of 100 g was placed near the center thereof and left for 24 hours. Then, the weight was removed and the dentability was evaluated by visually confirming the presence or absence of traces of the weight on the adhesive sheet. Also. The dentability was evaluated in the same manner as described above except that the other sample was replaced with a weight having a weight of 200 g.
⊚: No trace when the load is 200 g ○: No trace when the load is 100 g ×: There is a trace

(3) Adhesive strength The obtained adhesive sheet was prepared to have a width of 25 mm and a length of 150 mm. In accordance with JIS Z0237: 2000, in an atmosphere of 23 ° C. and 50% relative humidity, the peelable sheet was peeled off from the adhesive sheet, and the exposed adhesive layer was attached to a SUS plate having a width of 30 mm and a length of 150 mm. The adhesive strength was measured by a 180 ° peel test in which the material was reciprocally pressure-bonded, left to stand for 24 hours, and then peeled off at a speed of 300 mm / min in the 180 ° direction using a tensile tester, and evaluated based on the following evaluation criteria.
⊚: "Adhesive strength is 18N or more, which is very good."
◯: “Adhesive strength is 15N or more and less than 18N, which is good.”
X: "Adhesive strength is less than 15N, not practical."

(4) Holding power The obtained adhesive sheet was prepared to have a width of 25 mm and a length of 150 mm. JIS Z02
In accordance with 37: 2000, under an atmosphere of 23 ° C. and 50% relative humidity, the adhesive layer exposed by peeling the peelable sheet from the adhesive sheet is 30 mm wide and 150 mm long, and the lower end of the SUS plate is 25 mm wide and 25 mm long. An adhesive layer was attached to the portion, and after one reciprocating pressure bonding with a 2 kg roll, a load of 1 kg was applied in an atmosphere of 40 ° C., and the mixture was left for 70,000 seconds to measure the holding force. The evaluation was carried out based on the following evaluation criteria by measuring the length at which the upper end of the adhesive sheet sticking surface was displaced downward.
◯: “The misaligned length is less than 0.5 mm. Good.”
X: "The misaligned length is 0.5 mm or more. Practical use is not possible."

(5) Oil resistance The obtained adhesive sheet was prepared to have a width of 25 mm and a length of 50 mm. The peelable sheet was peeled off from the adhesive sheet under an atmosphere of 23 ° C. and a relative humidity of 50%, and the exposed adhesive layer was attached to a SUS plate having a width of 30 mm and a length of 60 mm, crimped once with a 2 kg roll, and left for 24 hours. The sample was immersed in Nissin salad oil (manufactured by Nissin Oillio Co., Ltd.) at 40 ° C. for 200 hours. Floating / peeling of the adhesive sheet and oil penetration after immersion were visually observed, and evaluation was performed based on the following evaluation criteria.
◯: “No floating / peeling or oil infiltration is seen. Good.”
×: "Floating / peeling and oil infiltration are seen. Not practical."

As shown in Examples 1 to 11 of Table 1, it can be seen that the pressure-sensitive adhesive of the present invention is excellent in adhesive strength, holding power immediately after coating, holding power, oil resistance, and dent resistance. On the other hand, in Comparative Examples 1 to 4, it can be seen that any of the items is defective and there is a problem in practical use or it is not practical.

Claims (6)

Acrylic acid alkyl esters, methacrylic acid alkyl esters, acrylic copolymer obtained by copolymerizing a monomer mixture containing a hydrogen bonding monomer, curing agent and an organic solvent A including adhesives,
The methacrylic acid alkyl ester contains a monomer having a homopolymer glass transition temperature of 10 ° C to 200 ° C.
The hydrogen-bonding monomer contains at least one selected from the group consisting of a carboxyl group-containing monomer, an amide group-containing monomer, a hydroxyl group-containing monomer, a urea bond-containing monomer, and a urethane bond-containing monomer.
Contains 7-25% by weight of hydrogen-bonding monomer in 100% by weight of the monomer mixture.
The hydrogen-bonding monomer contains a carboxyl group-containing monomer in an amount of 3 to 15% by weight in 100% by weight of the monomer mixture.
The curing agent contains at least one of an epoxy compound and a metal chelating compound.
The organic solvent, only containing an alcohol-based solvent,
The alcohol solvent is methanol, ethanol, n-propanol, or isopropanol.
The gel fraction of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive is 40 to 75% by weight.
Adhesive for film.
(However, this does not apply when the methacrylic acid alkyl ester is a film pressure-sensitive adhesive containing a monomer having an alkyl chain having 1 to 2 carbon atoms and a monomer having an alkyl chain having 3 to 10 carbon atoms.) It said containing 5 to 25 wt% methacrylic acid alkyl esters in the monomer mixture 100 wt%, film pressure-sensitive adhesive of claim 1 Symbol placement. The film pressure-sensitive adhesive according to claim 1 or 2 , wherein the acrylic copolymer has a weight average molecular weight of 150,000 to 400,000. The film pressure-sensitive adhesive according to any one of claims 1 to 3 , wherein the organic solvent contains ethyl acetate. The film adhesive according to any one of claims 1 to 4, which is used for sticking around a kitchen or a car. A pressure-sensitive adhesive sheet comprising a film base material and a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive for a film according to any one of claims 1 to 5.