JP2018127622A - Pressure sensitive adhesive and pressure sensitive adhesive sheet for polyvinyl chloride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensitive adhesive capable of forming a pressure sensitive adhesive sheet which has adhesion suitable for bonding a polyvinyl chloride and is excellent in not only heat resistance but also moist heat resistance.SOLUTION: A pressure sensitive adhesive for a polyvinyl chloride comprises an acrylic polymer being a copolymerization product of a monomer mixture including an alkyl (meth)acrylate ester monomer with an alkyl group having 4 carbon atoms, an alkyl (meth)acrylate ester monomer with an alkyl group having 1-2 carbon atoms and a carboxyl group-containing monomer; and at least one curative selected from isocyanate compounds, epoxy compounds and metal chelates. A pressure sensitive adhesive layer formed from the pressure sensitive adhesive has a storage modulus of 0.05-1 MPa at 70°C and the frequency of 1 Hz.SELECTED DRAWING: None

Description

  The present invention relates to an adhesive for polyvinyl chloride and an adhesive sheet that can be suitably used for bonding polyvinyl chloride.

A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive is easy to handle, and is used in a wide range of fields as a label or an adhesive application. Among them, acrylic adhesives are widely used because they are excellent in weather resistance, durability, heat resistance, transparency, and the like. For example, it is common to use an acrylic pressure-sensitive adhesive sheet as a label for plastic or the like, but when the plastic material is polyvinyl chloride, the plasticizer contained in the polyvinyl chloride is the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet. By moving to the surface, there was a problem that the adhesive strength was reduced and the label was easily peeled off.
Also, in the case of a pressure-sensitive adhesive sheet in which an acrylic pressure-sensitive adhesive is applied or laminated to a polyvinyl chloride base material such as a decorative sheet, the adhesive force decreases due to the migration of the plasticizer from the polyvinyl chloride base material, and peeling occurs. There was a problem.
Furthermore, the pressure-sensitive adhesive sheet used for bonding polyvinyl chloride used in agricultural films, bathroom flooring, etc., has a moisture resistance that can maintain the adhesive strength of the pressure-sensitive adhesive sheet even when exposed to high-temperature and high-humidity environments. Thermal properties were required.

  Patent Document 1 includes 5 to 20% by mass of vinyl acetate, 5 to 10% by mass of (meth) acrylonitrile, 10 to 30% by mass of (meth) acrylic acid ester having 1 or 2 alkyl groups, ethylenic unsaturated A pressure-sensitive adhesive in which a plasticizer is blended with an acrylic copolymer composed of (meth) acrylic acid ester having 3 to 6% by mass of carboxylic acid and 4 or more carbon atoms of the remaining alkyl group is disclosed.

  Patent Document 2 discloses that 50 to 99.95% by mass of an alkyl alkyl ester having 1 to 10 carbon atoms in an alkyl group, 0.05 to 20% by mass of an unsaturated monomer having a polar group, An adhesive containing less than 5 parts by mass of nitrified cotton is disclosed with respect to 100 parts by mass of a copolymer composed of 0 to 30% by mass of a polymerizable vinyl monomer.

JP-A-5-43863 Japanese Patent Laid-Open No. 63-230783

  However, although the adhesives of Patent Documents 1 and 2 can retain the adhesive strength after the heat treatment to some extent, the cohesive force is insufficient due to the addition of the plasticizer and nitrified cotton, and the holding force is insufficient. It was. Moreover, there existed a problem that heat-and-moisture resistance was inferior.

  The problem to be solved by the present invention is to provide a pressure-sensitive adhesive that has a pressure-sensitive adhesive force suitable for bonding polyvinyl chloride and can form a pressure-sensitive adhesive sheet that is excellent not only in heat resistance but also in heat and moisture resistance. .

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the following pressure-sensitive adhesive for polyvinyl chloride, and have completed the present invention.
That is, the present invention provides a monomer mixture comprising a (meth) acrylic acid alkyl ester monomer having an alkyl group having 4 carbon atoms, a (meth) acrylic acid alkyl ester monomer having an alkyl group having 1 to 2 carbon atoms, and a carboxyl group-containing monomer. An adhesive for polyvinyl chloride, comprising an acrylic polymer that is a copolymer of the above, and at least one curing agent selected from an isocyanate compound, an epoxy compound, and a metal chelate, wherein the adhesive is formed from the above-mentioned adhesive The storage elastic modulus at a frequency of 1 Hz and 70 ° C. of the agent layer is 0.05 to 1 MPa.
It is related with the adhesive for polyvinyl chloride characterized by these.

  Moreover, this invention relates to the said adhesive for polyvinyl chloride whose molecular weight dispersion degree of the said acrylic polymer is 5-10.

  Further, in the present invention, the content of the alkyl group (meth) acrylic acid alkyl ester monomer having 4 carbon atoms in the monomer mixture is 30 to 75% by mass, and the alkyl group has 1 to 2 carbon atoms (meth). (Meth) acrylic acid alkyl ester having an acrylic acid alkyl ester monomer content of 18 to 55% by mass and a carboxyl group-containing monomer content of 3 to 10% by mass, and the monomer mixture further having 8 alkyl groups. It is related with the said adhesive for polyvinyl chloride containing 0-15 mass% of monomers.

  Moreover, this invention relates to the said adhesive for polyvinyl chloride in which the said monomer mixture contains 0.01-0.5 mass% of hydroxyl-containing monomers further.

  Moreover, this invention relates to the said adhesive for polyvinyl chloride whose carboxyl group-containing monomer content rate in the said monomer mixture is 5-10 mass%.

  Moreover, this invention relates to the said adhesive for polyvinyl chloride whose weight average molecular weights of the said acrylic polymer are 950,000-1,700,000.

  Moreover, this invention relates to the adhesive sheet provided with the adhesive layer formed from the base material and the said adhesive for polyvinyl chloride.

According to the present invention, when polyvinyl chloride is used for a substrate and / or an adherend, it is possible to provide an adhesive capable of forming an adhesive sheet having good adhesive strength and excellent heat resistance as well as heat and moisture resistance. It was.

  Prior to describing the present invention in detail, terms will be defined. First, a sheet, a film, and a tape are synonymous. (Meth) acrylic acid means acrylic acid and methacrylic acid. The monomer means an ethylenically unsaturated double bond-containing monomer. An adherend refers to the other party which affixes an adhesive sheet.

<Adhesive for polyvinyl chloride>
The pressure-sensitive adhesive for polyvinyl chloride of the present invention (simply abbreviated as “pressure-sensitive adhesive”) includes at least one selected from an acrylic polymer, an isocyanate curing agent, an epoxy curing agent, and a metal chelate curing agent, The frequency of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive is 1 Hz.
The storage elastic modulus at 70 ° C. is 0.05 to 1 MPa.

  The storage elastic modulus of the pressure-sensitive adhesive layer is more preferably 0.07 to 0.4 MPa. When the storage elastic modulus at a frequency of 1 Hz and 70 ° C. of the pressure-sensitive adhesive layer is 0.05 to 1 MPa, during the heat and moisture resistance test when polyvinyl chloride is used for the substrate and / or the adherend. It becomes possible to suppress the plasticizer in the polyvinyl chloride from moving to the pressure-sensitive adhesive layer. If the pressure is less than 0.05 MPa, the plasticizer tends to move to the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive force tends to decrease. If the pressure is larger than 1 MPa, the pressure-sensitive adhesive layer is too hard and the pressure-sensitive adhesive force becomes insufficient.

<Acrylic polymer>
The acrylic polymer used in the present invention is a (meth) acrylic acid alkyl ester monomer having an alkyl group having 4 carbon atoms, a (meth) acrylic acid alkyl ester monomer having an alkyl group having 1 to 2 carbon atoms, and a carboxyl group-containing monomer. Is a copolymer of a monomer mixture containing

  The alkyl group (meth) acrylic acid alkyl ester monomer having an alkyl group having 4 carbon atoms is used for imparting adhesive strength and cohesive strength to an acrylic polymer. When the alkyl group has a linear structure, it is good for imparting adhesive strength. In addition, when the alkyl group has a branched structure, it is good for imparting cohesive force, and by using a linear structure and a branched structure in combination, the adhesive force and the cohesive force may be highly compatible. As for content, it is preferable to use 30-75 mass% in 100 mass% of monomer mixtures, and 35-70 mass% is more preferable. Use of 30 to 75% by mass makes it easy to achieve both cohesion and cohesion.

  Examples of the alkyl group (meth) acrylic acid alkyl ester monomer having 4 alkyl groups include butyl acrylate, isobutyl acrylate, t-butyl acrylate, butyl methacrylate, isobutyl methacrylate, and t-butyl methacrylate. . Among these, butyl acrylate and isobutyl acrylate are good for imparting adhesive strength and cohesive strength.

  A (meth) acrylic acid alkyl ester monomer having an alkyl group having 1 to 2 carbon atoms gives a cohesive force to the acrylic polymer to increase the storage elastic modulus of the pressure-sensitive adhesive layer, thereby improving heat resistance and heat and humidity resistance. Have As for content, it is preferable to use 18-55 mass% in 100 mass% of monomer mixtures, and 28-50 mass% is more preferable. Use of 18 to 55% by mass makes it easy to maintain the adhesive force while improving the storage elastic modulus of the adhesive layer.

  Examples of the (meth) acrylic acid alkyl ester monomer having 1 to 2 carbon atoms of the alkyl group include methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate. Among these, methyl acrylate and ethyl acrylate are preferable, and both heat resistance and wet heat resistance are easily achieved.

  The carboxyl group-containing monomer functions as a crosslinking point for the crosslinking reaction with the curing agent, and 3 to 10% by mass is preferably used in 100% by mass of the monomer mixture, and more preferably 5 to 10% by mass. By using 3 to 10% by mass, it is easy to obtain a desired crosslink density, and adhesion to polyvinyl chloride is improved.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, phthalic acid monohydroxyethyl acrylate ester, p-carboxybenzyl acrylate ester, ethylene oxide modified (ethylene oxide addition moles: (2-18) phthalic acid acrylate ester. , Succinic acid monohydroxyethyl acrylate, β-carboxyethyl acrylate, itaconic acid, etc. Among these, (meth) acrylic acid is preferable.

In the present invention, other monomers other than the (meth) acrylic acid alkyl ester monomer having 4 carbon atoms in the alkyl group, the (meth) acrylic acid alkyl ester monomer having 1 to 2 carbon atoms in the alkyl group, and the carboxyl group-containing monomer are used. It can also be used.
Other monomers may be monomers that do not impair the adhesive strength and cohesive strength of the adhesive. Specifically, for example, a monomer having a reactive functional group such as a hydroxyl group-containing monomer, an amide bond-containing monomer, an epoxy group-containing monomer, and an amino group-containing monomer; ) Acrylic acid alkyl ester monomers, aromatic ring-containing monomers, alkoxy (poly) alkylene oxide-containing monomers, and other vinyl monomers.

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

  It is preferable that a hydroxyl-containing monomer contains 0.01-0.5 mass% in 100 mass% of monomer mixtures, and 0.05-0.3 mass% is more preferable. By using an appropriate amount of a hydroxyl group-containing monomer, both adhesive strength and cohesive strength can be achieved to a higher degree.

  Examples of the amide bond-containing monomer include (meth) acrylamide, N-methyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, (Meth) acrylamide compounds such as N-dimethylaminopropyl (meth) acrylamide, diacetone (meth) acrylamide, N- (butoxymethyl) acrylamide; and heterocyclic rings such as N-vinylpyrrolidone, N-vinylcaprolactam, and acryloylmorpholine Compounds and the like.

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

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

  The amide bond-containing monomer, epoxy group-containing monomer, and amino group-containing monomer preferably each contain 0.1 to 1 part by mass in 100% by mass of the monomer mixture.

  (Meth) acrylic acid alkyl ester monomers other than alkyl groups having 1, 2 and 4 carbon atoms include, for example, propyl (meth) acrylate, isopropyl (meth) acrylate, pentyl (meth) acrylate, and hexyl (meth) acrylate. 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate, (meth) acrylic acid Examples include octadecyl and isooctadecyl (meth) acrylate. Among these, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, and isooctyl (meth) acrylate having 8 carbon atoms in the alkyl group are preferable.

  It is preferable that 0-15 mass% is used for the (meth) acrylic-acid alkylester monomer which is C8 of an alkyl group in 100 mass% of monomer mixtures, and 0-10 mass% is more preferable.

  Examples of the aromatic ring-containing monomer include phenoxyethyl acrylate, benzyl acrylate, phenoxydiethylene glycol (meth) acrylate, and (meth) acrylate ethylene oxide-modified nonylphenol.

  It is preferable that an aromatic ring containing monomer contains 0.1-10 mass parts in 100 mass% of monomer mixtures.

  Alkoxy (poly) alkylene oxide-containing monomers include, for example, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-phenoxyethyl acrylate, methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylic acid Examples include esters, methoxypolypropylene glycol (meth) acrylic acid esters, ethoxypolypropylene glycol (meth) acrylic acid esters, phenoxypolyethylene glycol (meth) acrylic acid esters, and phenoxypolypropylene glycol (meth) acrylic acid esters.

  It is preferable that an alkoxy (poly) alkylene oxide containing monomer contains 0.1-10 mass parts in 100 mass% of monomer mixtures.

  Other vinyl monomers include, but are not limited to, vinyl acetate and acrylonitrile.

  It is preferable that other vinyl monomers contain 0.1-10 mass parts in 100 mass% of monomer mixtures.

  The acrylic polymer can be obtained by adding a polymerization initiator to the monomer mixture and appropriately selecting a known production method such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations. Among these, solution polymerization is preferable from the viewpoint of easy adjustment of the weight average molecular weight and molecular weight dispersion of the acrylic polymer.

Examples of the solvent used for the solution polymerization include methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, xylene, hexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, n-propanol, and isopropanol. Is preferred, and ethyl acetate is more preferred.
Solvents can be used alone or in combination of two or more.

  The solution polymerization is preferably performed by adding about 0.001 to 1 part by mass of a polymerization initiator to 100 parts by mass of the monomer mixture. Usually, the polymerization can be performed under a nitrogen stream at a temperature of about 50 ° C. to 90 ° C. for 6 hours to 20 hours. Moreover, the weight average molecular weight of an acrylic polymer can be adjusted suitably using a chain transfer agent in the case of superposition | polymerization.

  In the present invention, the weight average molecular weight (hereinafter also referred to as Mw) of the acrylic polymer is preferably 950,000 to 1,700,000, and more preferably 1,050,000 to 1,500,000. By making Mw into the range of 950,000 to 1.7 million, it becomes easy to adjust the storage elastic modulus of the pressure-sensitive adhesive layer within a desired range, and it becomes easy to achieve both adhesive properties and coating properties. In the present invention, Mw is a value in terms of polystyrene measured by gel permeation chromatography (GPC).

  In the present invention, the molecular weight dispersion of the acrylic polymer is a value (Mw / Mn) obtained by dividing Mw by a number average molecular weight (hereinafter also referred to as Mn), and is preferably 5 to 10. By setting the molecular weight dispersity to 5 to 10, it becomes easy to achieve both the physical properties of the adhesive and the coating properties. In the present invention, Mn is a value in terms of polystyrene measured by gel permeation chromatography (GPC).

Examples of the chain transfer agent include n-dodecyl mercaptan, mercaptoisobutyl alcohol, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, glycidyl mercaptan, α-methyl Examples include styrene dimer, carbon tetrachloride, chloroform, and hydroquinone.
A chain transfer agent can use about 0.01-1 mass part with respect to 100 mass parts of monomer mixtures.

  The polymerization initiator is generally an azo compound or an organic peroxide.

Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2,2 '-Azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), 4 , 4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), and 2,2′-azobis (2- (2-
Imidazolin-2-yl) propane) and the like.

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate. , T-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.
The polymerization initiators can be used alone or in combination of two or more.

<Curing agent>
In the present invention, it is important to use an isocyanate compound, an epoxy compound, or a metal chelate as the curing agent, and an isocyanate compound is more preferable. A hardening | curing agent can be used individually or in combination of 2 or more types.

Isocyanate compounds are, for example, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, And adducts of diisocyanates such as polymethylene polyphenyl isocyanate and polyol compounds such as trimethylol propane, burettes thereof, isocyanurates thereof, and the diisocyanates, polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols , Compounds having 3 or more isocyanate groups in the molecule, such as an adduct with any of the polyols of such fine polyisoprene polyol;
Tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, and polymethylene polyphenyl isocyanate And the like, and compounds having two isocyanate groups in the molecule such as allophanate of hexamethylene diisocyanate. Among these, a trimethylolpropane adduct body of tolylene diisocyanate and an isocyanurate body of isophorone diisocyanate are preferable because the adhesive properties can be easily adjusted. In addition, the number of isocyanate groups is an average number.

  It is preferable that an isocyanate compound contains 0.5-15 mass parts with respect to 100 mass parts of acrylic polymers, and 1-10 mass parts is more preferable. When 0.5 to 15 parts by mass are included, it becomes easy to balance the cohesive force and adhesive force of the adhesive layer. An isocyanate compound can be used alone or in combination of two or more.

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

  It is preferable that an epoxy compound contains 0.01-1 mass part with respect to 100 mass parts of acrylic polymers. When 0.01 to 1 part by mass is included, it becomes easy to balance the cohesive force and adhesive force of the adhesive layer. Epoxy compounds can be used alone or in combination of two or more.

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

  It is preferable that a metal chelate contains 0.1-5 mass parts with respect to 100 mass parts of acrylic polymers. When it contains 0.1 to 5 parts by mass, it becomes easy to balance the cohesive force and adhesive force of the adhesive layer. The metal chelates can be used alone or in combination of two or more.

  In addition, you may contain tackifying resin in the range which can solve the subject of this invention. For example, rosin resin, terpene resin, alicyclic hydrocarbon resin, aliphatic petroleum resin, aromatic petroleum resin, alkylphenol formaldehyde resin (oil-based phenol resin) and the like are preferable. The tackifier resins can be used alone or in combination of two or more. When the pressure-sensitive adhesive contains a tackifying resin, the adhesive strength to polyvinyl chloride may be further improved.

  The tackifying resin is preferably blended in an amount of 10 to 30 parts by mass with respect to 100 parts by mass of the acrylic polymer.

  The softening point of the tackifying resin is preferably 80 to 140 ° C. When the softening point is 80 to 140 ° C., it becomes easy to achieve both adhesive force and cohesive force.

  The pressure-sensitive adhesive of the present invention is a resin, curing catalyst, silane coupling agent, oil, softening agent, dye, pigment, antioxidant, ultraviolet absorber, weather resistance stability as optional components within the range that can solve the problems of the present invention. You may mix | blend an agent, a filler, anti-aging agent, an antistatic agent, etc.

  The pressure-sensitive adhesive of the present invention is suitable as a pressure-sensitive adhesive for bonding polyvinyl chloride, general labels and seals, adhesive optical films, paints, elastic wall materials, waterproof coating materials, floor materials, and tackifiers. , Adhesives, adhesives for laminated structures, sealing agents, molding materials, coating agents for surface modification, binders (magnetic recording media, ink binders, casting binders, fired brick binders, graft materials, microcapsules, glass fiber sizing, etc. ), Urethane foam (hard, semi-rigid, soft), urethane RIM, UV / EB cured resin, high solid paint, thermosetting elastomer, microcellular, textile processing agent, plasticizer, sound absorbing material, vibration damping material, surface activity Agent, gel coat agent, resin for artificial marble, impact resistance agent for artificial marble, resin for ink, film (laminate viscosity Agents, protective films, etc.), laminated glass resins, reactive diluents, various molding materials, elastic fibers, artificial leather, synthetic leather, etc., and also useful as various resin additives and their raw materials. .

<Adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention preferably includes a base material and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive of the present invention. Moreover, as another aspect, the double-sided adhesive sheet which has an adhesive layer on both surfaces of a core material, or the cast adhesive sheet which did not have a base material and a core material but was comprised only by the adhesive layer is also preferable. The pressure-sensitive adhesive layer can be formed by applying a pressure-sensitive adhesive on a substrate and drying it. Alternatively, it can be formed by applying a pressure-sensitive adhesive on a peelable sheet, drying to form a pressure-sensitive adhesive layer, and then bonding the base materials together.

  When the adhesive is applied, the viscosity can be adjusted by adding the solvent described in the solution polymerization.

  In addition to polyvinyl chloride, the substrate is preferably, for example, cellophane, other plastics, rubber, foam, cloth, rubber cloth, resin-impregnated cloth, glass, wood, etc. Thus, the effects of the present invention can be exhibited. The shape of the substrate can be selected from a plate shape and a film shape, but a film shape that is easy to handle is preferable. The substrate can be used alone or in combination of two or more.

  Examples of the other plastic include polyolefins such as polyvinyl alcohol, triacetyl cellulose, polypropylene, polyethylene, polycycloolefin, and ethylene-vinyl acetate copolymer; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polycarbonate, poly Examples thereof include norbornene, polyarylate, polyacryl, polyphenylene sulfide, polystyrene, polyamide, and polyimide.

  The method of applying the adhesive is not particularly limited, and examples thereof include Mayer bar, applicator, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, knife coater, reverse coater, and spin coater. It is done. It is preferable to perform a drying process at the time of coating. The drying device is not particularly limited, and examples thereof include a hot air dryer, an infrared heater, and a pressure reduction method. The drying temperature is usually about 60 to 160 ° C.

  1-300 micrometers is preferable and, as for the thickness of an adhesive layer, 5-100 micrometers is more preferable. By being in the range of 1 to 300 μm, the adhesive physical properties can be adjusted to an appropriate range.

  EXAMPLES Next, although an Example of this invention is shown and it demonstrates still in detail, this invention is not limited by these. In the examples, “part” means “part by mass”, and “%” means “% by mass”.

[Synthesis of acrylic polymer]
(Synthesis Example 1)
In a reaction vessel (hereinafter simply referred to as “reaction vessel”) equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, under a nitrogen atmosphere, 75 parts of butyl acrylate and 20 parts of ethyl acrylate , 5 parts acrylic acid, 85 parts ethyl acetate, 2,2′-azobisisobutyronitrile (
Hereinafter, it is described as “AIBN”. ) 0.02 part was charged. The mixture was heated with stirring to confirm the start of the polymerization reaction, and reacted at reflux temperature for 2 hours. Next, 0.02 part of AIBN was added to the reaction solution and reacted for 2 hours, and 0.02 part of AIBN was further added to the reaction solution, and the reaction was continued for 4 hours. Thereafter, the reaction vessel was cooled and 150 parts of ethyl acetate was added to obtain an acrylic polymer solution having a weight average molecular weight of 1.13 million.

(Synthesis Examples 2-19, 23-26)
Acrylic polymer solutions of Synthesis Examples 2-19 and 23-26 were obtained by carrying out in the same manner as Synthesis Example 1 except that the types and blending amounts of the monomers were as described in Table 1.

(Synthesis Example 20)
In a nitrogen atmosphere, 75 parts of butyl acrylate, 20 parts of ethyl acrylate, 5 parts of acrylic acid, 160 parts of ethyl acetate, and 0.02 part of AIBN were charged in a reaction vessel. The mixture was heated with stirring to confirm the start of the polymerization reaction, and reacted at reflux temperature for 2 hours. Next, 0.02 part of AIBN was added to the reaction solution and reacted for 2 hours, and 0.02 part of AIBN was further added to the reaction solution, and the reaction was continued for 4 hours. Thereafter, the reaction vessel was cooled and 75 parts of ethyl acetate was added to obtain an acrylic polymer solution having a weight average molecular weight of 700,000.

(Synthesis Example 21)
In a nitrogen atmosphere, 75 parts of butyl acrylate, 20 parts of ethyl acrylate, 5 parts of acrylic acid, 60 parts of ethyl acetate, 60 parts of acetone, and 0.02 part of AIBN were charged in a reaction vessel. The mixture was heated with stirring to confirm the start of the polymerization reaction, and reacted at reflux temperature for 2 hours. Next, 0.02 part of AIBN was added to the reaction solution and reacted for 2 hours, and 0.02 part of AIBN was further added to the reaction solution, and the reaction was continued for 4 hours. Thereafter, the reaction vessel was cooled and 115 parts of ethyl acetate was added to obtain an acrylic polymer solution having a weight average molecular weight of 1,670,000.

(Synthesis Example 22)
In a nitrogen atmosphere, 75 parts of butyl acrylate, 20 parts of ethyl acrylate, 5 parts of acrylic acid, 120 parts of acetone, and 0.02 part of AIBN were charged in a reaction vessel. The mixture was heated with stirring to confirm the start of the polymerization reaction, and reacted at reflux temperature for 2 hours. Further, 0.02 part of AIBN was added to the reaction solution, and the reaction was continued for 4 hours. Thereafter, the reaction vessel was cooled and 115 parts of ethyl acetate was added to obtain an acrylic polymer solution having a weight average molecular weight of 2,100,000.

  About the obtained copolymer solution, Mw, Mw / Mn, and the external appearance of the solution were calculated | required in accordance with the following method. The results are shown in Table 1.

<Appearance of solution>
The appearance of the obtained acrylic polymer solution was visually evaluated.

<Measurement of Mw and Mw / Mn>
GPC was used for the measurement of Mw and Mw / Mn. GPC is a liquid chromatography that separates and quantifies substances dissolved in a solvent (THF; tetrahydrofuran) based on the difference in molecular size, and Mw and Mw / Mn are determined in terms of polystyrene.
Device name: LC-GPC system “Prominence” manufactured by Shimadzu Corporation
Column: Four GTHXL manufactured by Tosoh Corporation and one HXL-H manufactured by Tosoh Corporation were connected in series.
Mobile phase solvent: Tetrahydrofuran flow rate: 1.0 ml / min Column temperature: 40 ° C

Abbreviations in Table 1 are listed below.
<(Meth) acrylic acid alkyl ester monomer having 4 carbon atoms in the alkyl group>
BA: butyl acrylate IBA: isobutyl acrylate <(meth) acrylic acid alkyl ester monomer having 8 alkyl groups>
2EHA: 2-ethylhexyl acrylate <(meth) acrylic acid alkyl ester monomer having 1 to 2 carbon atoms of alkyl group>
MA: methyl acrylate EA: ethyl acrylate MMA: methyl methacrylate <carboxyl group-containing monomer>
AA: Acrylic acid MAA: Methacrylic acid <Hydroxyl group-containing monomer>
HEA: 2-hydroxyethyl acrylate HEMA: 2-hydroxyethyl methacrylate

Example 1
To 100 parts of the acrylic polymer in the polymer solution obtained in Synthesis Example 1 (nonvolatile content), 2 parts of trimethylolpropane adduct of tolylene diisocyanate (nonvolatile content) is blended as an isocyanate curing agent, and as a solvent. Ethyl acetate was added to adjust the nonvolatile content to 20% to obtain an adhesive for polyvinyl chloride. The pressure-sensitive adhesive is coated on a 38 μm-thick peelable sheet (polyethylene terephthalate) with a comma coater so that the thickness after drying is 25 μm, and dried at 100 ° C. for 2 minutes. A layer was formed. Next, a base material having a thickness of 80 μm (polyvinyl chloride base material containing 36% dioctyl phthalate as a plasticizer (hereinafter referred to as a PVC sheet)) was bonded to the pressure-sensitive adhesive layer, and the temperature was 23 ° C. and the relative humidity was 50 % Of the adhesive sheet 1 having a structure of “peelable sheet / adhesive layer / PVC sheet” was obtained. In addition, a 50 μm-thick base material (polyethylene terephthalate base material (hereinafter referred to as PET sheet)) is bonded to the adhesive layer after coating and drying, and the temperature is 23 ° C. and the relative humidity is 50%. By aging for a week, an adhesive sheet 2 having a configuration of “peelable sheet / adhesive layer / PET sheet” was obtained.

(Examples 2 to 26, Comparative Examples 1 to 4)
Except having changed material according to the mixing | blending of Table 2, 3, it carries out similarly to Example 1, By the adhesive for polyvinyl chloride of Examples 2-26 and Comparative Examples 1-4, the adhesive sheet 1, the adhesive sheet 2 Respectively.

The obtained adhesive sheet was evaluated by the following methods. The results are shown in Table 2 and Table 3.
Abbreviations in Table 2 and Table 3 are described below.
<Isocyanate compound>
TDI / TMP: trimethylolpropane adduct of tolylene diisocyanate IPDI / nurate: isocyanurate of isophorone diisocyanate <epoxy compound>
TETRAD X: N, N, N ′, N′-tetraglycidyl-m-xylylenediamine (manufactured by Mitsubishi Gas Chemical Company)
<Metal chelate>
Aluminum chelate A: Aluminum trisacetylacetonate (manufactured by Kawaken Fine Chemical Co., Ltd.)

(1) Storage elastic modulus For Examples and Comparative Examples, coating was performed with a comma coater on a peelable sheet having a thickness of 38 μm according to the procedure of the pressure-sensitive adhesive sheet 1 so that the thickness after drying was 25 μm. The pressure-sensitive adhesive layer was formed by drying at 0 ° C. for 2 minutes. Next, another 75 μm thick peelable sheet (made of polyethylene terephthalate) was bonded in place of the base material, and aged for one week under the condition of a temperature of 23 ° C. and a relative humidity of 50%, “peelable sheet / adhesive layer / peeling” A pressure-sensitive adhesive layer sandwiched between two releasable sheets having a configuration of “adhesive sheet” was prepared. Subsequently, one peelable sheet was peeled off, and lamination was repeated so that the pressure-sensitive adhesive layers overlapped to obtain a pressure-sensitive adhesive layer having a thickness of 1 mm. After removing air bubbles with an autoclave, the sample was cut into a cylinder with a diameter of 8 mm to prepare a sample for measuring storage elastic modulus. The peelable sheets on both sides were peeled off, and the sample was measured by the torsional shearing method under the following conditions.

Measuring device: Dynamic viscoelasticity measuring device “DYNAMIC ANALYZER RDA III” manufactured by TA Instruments Japan
Frequency: 1Hz
Measurement temperature: Measured from −50 ° C. to 150 ° C., and the storage elastic modulus at 70 ° C. was read.
Temperature increase rate: 10 ° C / min

(2-1) Adhesive strength 1
The obtained pressure-sensitive adhesive sheet 1 was cut into a size of 25 mm in width and 150 mm in length. In a 23 ° C., 50% relative humidity atmosphere, the peelable adhesive sheet 1 was peeled off from the cut adhesive sheet 1 and the exposed adhesive layer was attached to a stainless steel (SUS) plate, reciprocated once with a 2 kg roll, and allowed to stand for 24 hours after pressure bonding. A sample was prepared. The adhesive strength was measured by a 180 ° peel test in which the sample was peeled off at a speed of 300 mm / min in the direction of 180 ° using a tensile tester, and evaluation was performed based on the following evaluation criteria. (Conforms to JIS Z0237: 2000)
A: “Adhesive strength is 15 N / 25 mm or more and very good”
○: “Adhesive strength is 10 N / 25 mm or more and less than 15 N / 25 mm, which is good”
Δ: “Adhesive strength is 5 N / 25 mm or more and less than 10 N / 25 mm and is practical”
×: “Adhesive strength is less than 5 N / 25 mm or cohesive failure, impractical”

(2-2) Adhesive strength 2
The above “adhesive strength” except that the adhesive sheet 2 was used instead of the adhesive sheet 1 and a 1.0 mm thick polyvinyl chloride (PVC) plate containing 48% dioctyl phthalate as a plasticizer was used instead of the SUS plate. The adhesive strength was measured in the same manner as in “1”, and the evaluation was performed based on the following evaluation criteria.
A: “Adhesive strength is 20 N / 25 mm or more and very good”
○: “Adhesive strength is 15 N / 25 mm or more and less than 20 N / 25 mm, which is good”
Δ: “Adhesive strength is 10 N / 25 mm or more and less than 15 N / 25 mm and is practical”
×: “Adhesive strength is less than 10 N / 25 mm, impractical”

(3) Holding power The obtained pressure-sensitive adhesive sheet 1 was cut into a size of 25 mm in width and 150 mm in length. The pressure-sensitive adhesive layer exposed by peeling off the peelable sheet 1 from the cut-out pressure-sensitive adhesive sheet 1 is attached to a polished bottom portion of a stainless plate having a width of 30 mm and a length of 150 mm and a width of 25 mm and a length of 25 mm. After reciprocating and pressing, a 1 kg load was applied to the lower end of the pressure-sensitive adhesive sheet in an atmosphere of 70 ° C., and the holding power was measured by leaving it to stand for 70,000 seconds (conforming to JIS Z0237: 2000).
Evaluation measured the length which the upper end part of the sticking surface of the adhesive sheet 1 shifted | deviated below from the original position.
Evaluation criteria A: “The shifted length is less than 0.1 mm, which is very good.”
○: “The shifted length is 0.1 mm or more and less than 0.5 mm, which is good”
Δ: “The shifted length is 0.5 mm or more and less than 2.0 mm, and is practical.”
X: “The shifted length is 2.0 mm or more and is not practical.”

(4-1) Heat resistance 1
The obtained pressure-sensitive adhesive sheet 1 was allowed to stand for 5 days at 70 ° C. and 5% relative humidity, and then left for 24 hours in an atmosphere at 23 ° C. and 50% relative humidity. Thereafter, the adhesive strength (adhesive strength after heat resistance 1) was measured in the same manner as the adhesive strength 1, and evaluation was performed based on the following evaluation criteria.
Retention rate = (Adhesive strength 1 / Adhesive strength after heat resistance 1) × 100
A: “Retention rate is 90 or more and very good.”
○: “Retention rate is 75 or more and less than 90 and good”
Δ: “Retention rate is 50 or more and less than 75 and is practical”
X: “Retention rate is less than 50 or cannot be calculated due to cohesive failure, impractical”

(4-2) Heat resistance 2
The obtained pressure-sensitive adhesive sheet 2 was attached and pressure-bonded in the same manner as the pressure-sensitive adhesive force 2, and allowed to stand at 70 ° C. and 5% relative humidity for 5 days, and then left at 23 ° C. and 50% relative humidity for 24 hours. Thereafter, the adhesive strength (adhesive strength 2 after heat resistance) was measured in the same manner as the adhesive strength 2, and the evaluation was performed based on the following evaluation criteria.
Retention rate = (Adhesive strength 2 / Adhesive strength 2 after heat resistance) × 100
A: “Retention rate is 90 or more and very good.”
○: “Retention rate is 75 or more and less than 90 and good”
Δ: “Retention rate is 50 or more and less than 75 and is practical”
X: “Retention rate is less than 50 or cannot be calculated due to cohesive failure, impractical”

(5-1) Moist heat resistance 1
The obtained pressure-sensitive adhesive sheet 1 was allowed to stand at 70 ° C. and a relative humidity of 60% for 3 days, and then left at 23 ° C. and a relative humidity of 50% for 24 hours. Thereafter, the adhesive strength (adhesive strength 1 after wet heat resistance) was measured in the same manner as the adhesive strength 1, and the evaluation was performed based on the following evaluation criteria.
Retention rate = (Adhesive strength 1 / Adhesive strength after heat and humidity resistance 1) × 100
A: “Retention rate is 90 or more and very good.”
○: “Retention rate is 75 or more and less than 90 and good”
Δ: “Retention rate is 50 or more and less than 75 and is practical”
X: “Retention rate is less than 50 or cannot be calculated due to cohesive failure, impractical”

(5-2) Moist heat resistance 2
The obtained pressure-sensitive adhesive sheet 2 was pasted and pressure-bonded in the same manner as the pressure-sensitive adhesive force 2, and allowed to stand at 70 ° C. and a relative humidity of 60% for 3 days, and then left at 23 ° C. and a relative humidity of 50% for 24 hours. Thereafter, the adhesive strength (adhesive strength 2 after wet heat resistance) was measured in the same manner as the adhesive strength 2, and the evaluation was performed based on the following evaluation criteria.
Retention rate = (Adhesive strength 2 / Adhesive strength 2 after heat and humidity resistance) × 100
A: “Retention rate is 90 or more and very good.”
○: “Retention rate is 75 or more and less than 90 and good”
Δ: “Retention rate is 50 or more and less than 75 and is practical”
X: “Retention rate is less than 50 or cannot be calculated due to cohesive failure, impractical”

  As shown in Examples 1 to 26 in Tables 2 and 3, the pressure-sensitive adhesive of the present invention is excellent in adhesive strength, holding power, heat resistance, and moisture and heat resistance even when polyvinyl chloride is used for a substrate or an adherend. I understand that On the other hand, in Comparative Examples 1 to 4 in Table 3, it can be seen that any item is defective and is not practical.

  The pressure-sensitive adhesive of the present invention is particularly useful as a pressure-sensitive adhesive for polyvinyl chloride because it has plasticizer transfer resistance suitable for bonding of polyvinyl chloride and is excellent not only in heat resistance but also in heat and moisture resistance. .

Claims (7)

It is a copolymer of a monomer mixture containing a (meth) acrylic acid alkyl ester monomer having 4 carbon atoms in the alkyl group, a (meth) acrylic acid alkyl ester monomer having 1 to 2 carbon atoms in the alkyl group, and a carboxyl group-containing monomer. An adhesive for polyvinyl chloride comprising an acrylic polymer and at least one curing agent selected from an isocyanate compound, an epoxy compound and a metal chelate, wherein the frequency of the adhesive layer formed from the adhesive is 1 Hz; A pressure-sensitive adhesive for polyvinyl chloride having a storage elastic modulus at 70 ° C of 0.05 to 1 MPa.   The pressure-sensitive adhesive for polyvinyl chloride according to claim 1, wherein the acrylic polymer has a molecular weight dispersity of 5 to 10.   (Meth) acrylic acid alkyl ester monomer content of 4 to 4 carbon atoms of alkyl group in the monomer mixture, (meth) acrylic acid alkyl ester monomer content of 1 to 2 carbon atoms of alkyl group The amount of the monomer is 18 to 55% by mass, the content of the carboxyl group-containing monomer is 3 to 10% by mass, and the monomer mixture further contains 0 to 15 mass of (meth) acrylic acid alkyl ester monomer having 8 alkyl groups. The pressure-sensitive adhesive for polyvinyl chloride according to claim 1, comprising%.   The pressure-sensitive adhesive for polyvinyl chloride according to any one of claims 1 to 3, wherein the monomer mixture further contains 0.01 to 0.5 mass% of a hydroxyl group-containing monomer.   The pressure-sensitive adhesive for polyvinyl chloride according to claim 1, wherein the content of the carboxyl group-containing monomer in the monomer mixture is 5 to 10% by mass.   The pressure-sensitive adhesive for polyvinyl chloride according to any one of claims 1 to 5, wherein the acrylic polymer has a weight average molecular weight of 950,000 to 1.7 million. A pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive for polyvinyl chloride according to any one of claims 1 to 6.