JP7306560B1 - PSA COMPOSITION FOR DECORATION SHEET, DECORATION SHEET USING THE SAME, DECORATION STRUCTURE CONTAINING THE DECORATION SHEET, AND MANUFACTURING METHOD THEREOF - Google Patents

Abstract

[Problem] To provide a pressure-sensitive adhesive composition for a decorative sheet, a decorative sheet, a decorative structure, and a method for producing the same, which can give a molded article excellent re-stickability before heating, durability at high temperatures, and an excellent appearance in the decoration of a molded article, and also has excellent water-resistant adhesion retention to a curved surface. A pressure-sensitive adhesive composition for a decorative sheet, comprising a (meth)acrylic ester copolymer (A) and a curing agent (B), wherein the (meth)acrylic ester copolymer (A) is a copolymer of a monomer mixture, and the content of a linear alkyl (meth)acrylate (a) having an alkyl group having 8 to 18 carbon atoms is 10 to 95% by mass in 100% by mass of the monomer mixture. and a decorative sheet, a decorative structure, and a method for producing a decorative structure using the same. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a decorative sheet pressure-sensitive adhesive composition, a decorative sheet using the same, a decorative structure, and a method for producing the same.

Adhesives (also referred to as pressure-sensitive adhesives) are processed into forms such as tapes and labels, and are used in a wide variety of applications such as daily necessities, packaging materials, optical members, automobiles, building materials, and medical applications.

On the other hand, when decorating the surface of automobile interior and exterior parts, home appliance parts, building material parts, etc., the conventional method is to apply paint to the surface of the molded product by spray painting, etc., and then dry and heat harden it. It was done. However, in addition to the deterioration of the work environment due to the emission of volatile organic solvents, this method requires work processes and production equipment for each molded product, and the paint yield is poor because it requires multiple coats of paint. , there was a problem of low productivity.

In recent years, there has been a shift from conventional spray painting to film decoration methods for the purpose of further reducing environmental impact and improving design. A pressure-sensitive adhesive is used to attach the decorative sheet to the molded body, and the decoration method using the decorative sheet can also decorate the surface of the molded body having three-dimensional unevenness. It is attracting attention for various applications including fields.

Known methods for decorating molded articles having a three-dimensional shape, such as automotive interior and exterior parts, using decorative sheets include, for example, insert molding, in-mold molding, vacuum molding, and vacuum pressure molding. .

Insert molding and in-mold molding are characterized in that the parts are decorated at the same time as they are molded, and the parts are firmly integrated. On the other hand, vacuum forming and vacuum/compressive air forming are methods of decorating parts by pasting them together at normal temperature and molding them by heating after completion of the parts. In other words, since the decorative sheet is attached to the exterior surface of the molded product in a separate operation from the molding of the molded product, a single device can be used to attach the decorative sheet to molded products of various shapes. can be done. In addition, the vacuum molding method and the vacuum pressure molding method are often used because they can continuously coat the ends of the molded product from the front surface to the back surface, that is, roll coating, which is difficult with the in-mold molding method. .

In Patent Document 1, by using a pressure-sensitive adhesive composition containing two types of (meth)acrylic polymers having a glass transition temperature in a specific range in a specific ratio, tack is low and repositionability is excellent, and the coating film It is disclosed that a pressure-sensitive adhesive layer having an excellent appearance can be formed.

Patent Document 2 describes a pressure-sensitive adhesive composition containing a vinyl polymer having a glass transition temperature of 30° C. or more and 200° C. or less and a number average molecular weight of 500 to 10,000 and an acrylic adhesive polymer in a specific ratio. If the pressure-sensitive adhesive layer obtained by cross-linking with a cross-linking agent satisfies specific glass transition temperature conditions, it is possible to have excellent adhesion under high temperature and high humidity, coating appearance, and adhesion to curved surfaces and irregularities. disclosed.

WO2021/049480 Japanese Patent Application Laid-Open No. 2018-2891

Usually, when a decorative sheet is attached to a molded product by a vacuum molding method or a vacuum pressure molding method, it is often reattached before molding because it cannot be reattached after heat molding. For this reason, it is required that it can be easily reattached. In addition, since it is assumed that automobile interior and exterior parts will be used in various environments, it is superior in that it does not cause external defects such as floating or peeling even when exposed to high temperatures or water. Durability and adhesion are also important.

The pressure-sensitive adhesive composition of Patent Document 1 is excellent in re-tensionability and removability, but does not mention durability in a high-temperature environment, etc., and is not sufficient in terms of practical performance.

Although the decorative film described in Patent Literature 2 maintains durability at 120° C. for 24 hours, there are concerns about durability in higher temperature environments (for example, 150° C.) and for long periods of time. Moreover, when the sample bonded to the curved surface is exposed to water, the pressure-sensitive adhesive sheet floats or peels off, resulting in poor appearance.

In other words, in the decoration of molded products using the vacuum forming method or vacuum pressure forming method, it is possible to impart reattachability before heating, durability at high temperatures, excellent appearance to the molded product, and water-resistant adhesion to curved surfaces. No pressure-sensitive adhesive composition has been developed so far.

In order to solve the above problems, the present inventors made intensive studies, and as a result, arrived at the present invention.
That is, it contains a (meth)acrylic ester copolymer (A) and a curing agent (B), the (meth)acrylic ester copolymer (A) is a copolymer of a monomer mixture, and 100 mass of the monomer mixture %, the content of linear alkyl (meth)acrylate (a) having an alkyl group of 8 to 18 carbon atoms is 10 to 95% by mass. .

INDUSTRIAL APPLICABILITY According to the present invention, in the decoration of a molded product using a vacuum forming method or a vacuum pressure forming method, it is possible to impart reattachability before heating, durability at high temperatures, and an excellent appearance to the molded product, as well as water resistance to curved surfaces. It is possible to provide a pressure-sensitive adhesive composition for a decorative sheet, a decorative sheet, a decorative structure, and a method for producing the same, all of which have excellent adhesiveness. When forming a pressure-sensitive adhesive layer with a pressure-sensitive adhesive composition containing a (meth)acrylic acid ester copolymer (A) containing a predetermined (meth)acrylate and a curing agent (B), its moderate hydrophobicity and The inventors have learned that, due to the flexibility, it is possible to improve the ability to retain water-resistant adhesion to curved surfaces while at the same time achieving a high level of other performance.

The decorative sheet pressure-sensitive adhesive composition, the decorative sheet, the decorative structure, and the method for producing the decorative structure according to the present disclosure have the following configurations [1] to [8].
[1] A (meth)acrylic acid ester copolymer (A) and a curing agent (B) are included, the (meth)acrylic acid ester copolymer (A) is a copolymer of a monomer mixture, and the monomer mixture 100 A pressure-sensitive adhesive composition for a decorative sheet, wherein the content of linear alkyl (meth)acrylate (a) having an alkyl group of 8 to 18 carbon atoms is 10 to 95% by mass.
[2] the monomer mixture constituting the (meth)acrylic acid ester copolymer (A) further contains an alkyl (meth)acrylate (b) in which the alkyl group has 1 to 4 carbon atoms,
The pressure-sensitive adhesive composition for a decorative sheet, wherein the content of the alkyl (meth)acrylate (b) is 1 to 50% by mass in 100% by mass of the monomer mixture.
[3] The pressure-sensitive adhesive composition for decorative sheet, wherein the gel fraction after cross-linking is 50% or more.
[4] The pressure-sensitive adhesive composition for a decorative sheet, which is used for attaching the decorative sheet to an adherend by a vacuum forming method or a vacuum pressure forming method.
[5] A decorative sheet comprising a substrate and an adhesive layer made of the adhesive composition for a decorative sheet.
[6] A decorative structure comprising an adherend and the decorative sheet.
[7] A method for manufacturing a decorative structure, wherein the decorative sheet is integrated with an adherend by a vacuum forming method or a vacuum pressure forming method to form the decorative structure.

The present disclosure will be described in detail below. It goes without saying that other embodiments are also included in the scope of the present disclosure as long as they match the gist of the present disclosure.

In the present disclosure, "sheet" means a laminate having flexibility, and includes a thin laminate called "film".

In the present disclosure, "(meth)acrylic" means either one or both of "acrylic" and "methacrylic", and "(meth)acrylate" means either "acrylate" or "methacrylate". or both.

In the present disclosure, the numerical range specified using "-" shall include the numerical values described before and after "-" as the range of lower and upper values.

In this specification, the decorative sheet pressure-sensitive adhesive composition may be abbreviated as "pressure-sensitive adhesive composition".

In the present specification, "Mw" is a polystyrene-equivalent weight-average molecular weight obtained by gel permeation chromatography (GPC) measurement. "Mn" is the polystyrene-equivalent number-average molecular weight determined by GPC measurement.
These weight average molecular weight and number average molecular weight can be measured by the method described in the section [Examples].

Further, the embodiments of the present invention will be described in detail below, but the following description is an example (representative example) of the embodiments of the present invention, and the present invention is limited to these contents unless it exceeds the gist thereof. not.

<Adhesive composition for decorative sheet>
The adhesive composition for a decorative sheet of the present invention comprises a (meth)acrylic ester copolymer (A) and a curing agent (B), and the (meth)acrylic ester copolymer (A) is a monomer mixture. wherein the content of linear alkyl (meth)acrylate (a) having 8 to 18 carbon atoms in the alkyl group is 10 to 95% by mass in 100% by mass of the monomer mixture. .

<(Meth) acrylic acid ester copolymer (A)>
The (meth)acrylic acid ester copolymer (A) (hereinafter also referred to as copolymer (A)) contained in the pressure-sensitive adhesive composition of the present invention is a mixture of all monomers containing a (meth)acrylic acid alkyl ester or It is a copolymer obtained by partially polymerizing.

The content of (meth)acrylate (a) having a straight-chain alkyl group with 8 to 18 carbon atoms is 10 to 95% by mass in 100% by mass of the monomer mixture. 30 to 85% by mass is more preferable. Within the above range, it is possible to achieve a high level of adhesive strength, durability at high temperatures, and water-resistant adhesion retention to curved surfaces.

Examples of the (meth)acrylate (a) having a linear alkyl group having 8 to 18 carbon atoms include n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, Lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate and the like.

Depending on the purpose of adjusting compatibility with other components, dispersibility of other components, adhesion to substrates and adherends, and crosslinkability, the synthesis of the copolymer (A) includes 8 to 8 carbon atoms. Other monomers than (meth)acrylate (a) with 18 linear alkyl groups can also be used.
More specifically, it is preferred that the monomer mixture constituting the copolymer (A) further contains a (meth)acrylate (b) having 1 to 4 carbon atoms. These may be used alone or in combination of two or more.

Examples of (meth)acrylates (b) having 1 to 4 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, and isobutyl (meth)acrylate. acrylates and the like.

The content of the (meth)acrylate (b) having 1 to 4 carbon atoms in 100% by mass of the monomer mixture is preferably 1 to 50% by mass, more preferably 5 to 40% by mass. Within the above range, it is possible to achieve a high level of adhesive strength, durability at high temperatures, and water-resistant adhesion to curved surfaces.

It is preferable that the monomer mixture constituting the copolymer (A) further contains a monomer having a functional group that forms a crosslinked structure with the crosslinkable group (B). Examples of functional groups include hydroxyl groups, acidic groups, unsaturated double bond groups, and epoxy groups. These may be used alone or in combination of two or more.
From the viewpoint of adhesion to substrates and durability at high temperatures, it is particularly preferable to use hydroxyl group-containing monomers and acidic group-containing monomers, and more preferably to use acidic group-containing monomers.

Examples of acidic group-containing monomers include (meth)acrylic acid, 2-carboxyethyl acrylate, itaconic acid, maleic acid, styrenesulfonic acid, 2-(meth)acryloyloxyethyl-succinic acid, 2-(meth)acrylic acid, vinyl-based monomers having acidic groups such as royloxyethyl-phthalic acid, 2-acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl acid phosphate, and 2-methacryloyloxyethyl acid phosphate; be done.

The content of the acidic group-containing monomer in the monomer mixture that constitutes the copolymer (A) is 2 in 100% by mass of the monomer mixture from the viewpoint of reattachability, durability at high temperatures, and water-resistant adhesion retention to curved surfaces. ~25% by mass is preferable, and 5 to 20% by mass is more preferable.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6 -Hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, and polyalkylene glycol mono (meth) acrylate having a hydroxyl group (meth) acrylic acid ester monomers, and polyalkylene glycol allyl ether and other hydroxyl groups and an allyl ether-based monomer having

The content of the hydroxyl group-containing monomer in the monomer mixture that constitutes the copolymer (A) is from 0.01 to 0.01 in 100% by mass of the monomer mixture, from the viewpoint of restickability, durability at high temperatures, and adhesion to curved surfaces. 5% by mass is preferred, and 0.1 to 3% by mass is more preferred.

Furthermore, examples of other monomers that can be included in the monomer mixture that constitutes the copolymer (A) include the following.

Vinyl monomers such as vinyl acetate, vinyl propionate, styrene, vinyl laurate, vinyl caprate, vinyl caprylate, and vinyl nonanoate;
pentyl (meth)acrylate, isopentyl (meth)acrylate, 2-methylbutyl (meth)acrylate, hexyl (meth)acrylate, 4-methyl-2-pentyl (meth)acrylate, heptyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, isostearyl (meth)acrylate, behenyl acrylate, eicosanyl (meth)acrylate, hexacosanyl (meth)acrylate, etc. (meth)acrylates having a chain or branched alkyl group (excluding linear alkyl (meth)acrylates (a) having 8 to 18 carbon atoms);
cyclohexyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate dicyclopentanyl (meth)acrylate, and (Meth)acrylic acid ester-based monomers having an aliphatic ring such as 3,3,5-trimethylcyclohexyl acrylate;
(Meth)acrylic acid ester monomers having an aromatic ring such as benzyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 2-(o-phenylphenoxy)ethyl (meth)acrylate, and nonylphenoxypolyethylene glycol acrylate ;
2-methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxymethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl ( meth) acrylate, 4-methoxybutyl (meth) acrylate, and (meth) acrylic acid ester monomers having an alkoxy group such as 4-ethoxybutyl (meth) acrylate;
Methoxypolyethylene glycol (meth)acrylate, ethoxypolyethyleneglycol (meth)acrylate, methoxypolypropyleneglycol (meth)acrylate, ethoxypolypropyleneglycol (meth)acrylate, phenoxypolyethyleneglycol (meth)acrylate, and phenoxypolypropyleneglycol (meth)acrylate, etc. (Meth)acrylic acid ester-based monomer having a polyether chain;
N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl -N-vinyl cyclic amide-based monomers such as 3,5-morpholinedione;
(meth)acrylamide-based monomers such as (meth)acrylamide, N-alkyl(meth)acrylamide, N,N-dialkyl(meth)acrylamide, N-hydroxyalkyl(meth)acrylamide, and N-alkoxyalkyl(meth)acrylamide;
N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl) (meth)acrylamide and N,N-dialkyl(meth)acrylamide-based monomers such as N,N-di(t-butyl)(meth)acrylamide;
N-methylol(meth)acrylamide, N-(2)-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N- (3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, and N-hydroxyalkyl (meth)acrylamide-based monomers such as N-methyl-N-2-hydroxyethyl (meth)acrylamide;
and N-alkoxyalkyl(meth)acrylamides such as N-methoxymethyl(meth)acrylamide and N-butoxymethyl(meth)acrylamide.
These may or may not contain the monomer mixture constituting the copolymer (A) as necessary, but when they are contained in the monomer mixture, vinyl acetate is used from the viewpoint of the coating properties of the pressure-sensitive adhesive composition. is more preferable.

The content of other monomers in the monomer mixture constituting the copolymer (A) is preferably 40% by mass or less, more preferably 30% by mass or less, based on 100% by mass of the monomer mixture. By setting the content within the above range, it is possible to achieve a high level of both adhesive strength, durability at high temperatures, and water-resistant adhesion retention.

The polymerization form of the (meth)acrylate copolymer (A) is not particularly limited. That is, the copolymer (A) may be any of alternating copolymers, random copolymers, block copolymers, graft copolymers, etc. of monomers containing (meth)acrylic acid alkyl esters. For example, block copolymers may be diblock or triblock.

A conventionally known method can be used for the synthesis of the copolymer (A). For example, it can be produced by a known polymerization method such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc. . Moreover, well-known polymerization methods such as living radical polymerization method and active energy ray polymerization method can be appropriately used for synthesis of the copolymer (A). At that time, the monomer mixture for synthesizing the copolymer (A) can contain a photopolymerization initiator and conventionally known additives. As active energy rays, ultraviolet rays, visible rays, X-rays, gamma rays, electron beams, or the like can be used. In addition, light sources such as low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, metal halide lamps, electrodeless lamps, and LEDs can be used for irradiation with ultraviolet rays.

The content of each structural unit (monomer component) of the copolymer (A) can be specified using various instruments such as nuclear magnetic resonance spectroscopy (NMR) and gas chromatography (GC).

The weight average molecular weight (Mw) of the (meth)acrylate copolymer (A) is preferably greater than 300,000, more preferably 500,000 or more, and preferably 700,000 or more. More preferred. Further, the weight average molecular weight of the copolymer (A) is preferably 1,500,000 or less, more preferably 1,300,000 or less, and further preferably 1,200,000 or less. preferable.
When the Mw of the copolymer (A) satisfies the above lower limit conditions, it is easy to ensure a viscosity suitable for coating, and after decorating the molded product, the decorative sheet portion is displaced, and the appearance of the decorated molded product Deterioration can be easily prevented.

<Curing agent (B)>
The adhesive composition of the present invention contains a curing agent (B). By giving the (meth)acrylic acid ester copolymer (A) a cross-linking group and cross-linking it with the curing agent (B), the cohesion and adhesive strength of the adhesive layer, durability at high temperatures, and water resistance are improved. can be enhanced.

Examples of the curing agent contained in the pressure-sensitive adhesive composition of the present invention include isocyanate compounds, epoxy compounds, aziridine compounds, metal chelates, amine compounds, acrylate compounds and the like. Among these, isocyanate compounds, epoxy compounds, and metal chelates are more preferable from the viewpoint of adhesive strength and solution stability, and epoxy compounds are more preferable from the viewpoint of durability in high-temperature environments.

Examples of isocyanate curing agents include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, Isocyanate, adducts of diisocyanates such as polymethylene polyphenyl isocyanate and polyol compounds such as trimethylolpropane, burettes thereof, isocyanurates thereof, and the diisocyanates, polyether polyols, polyester polyols, acrylic polyols, Compounds having 3 or more isocyanate groups in the molecule, such as adducts with polybutadiene polyols and polyisoprene polyols; tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, water Diisocyanates such as added xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, and polymethylene polyphenyl isocyanate, and allophanate forms of hexamethylene diisocyanate, etc. compounds having two isocyanate groups; and the like. Among these, the trimethylolpropane adduct of tolylene diisocyanate is preferable because the adhesive properties can be easily adjusted. In addition, the number of isocyanate groups is the average number.

Examples of epoxy curing agents include bisphenol A-epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diol. glycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane , and N,N,N′,N′-tetraglycidylaminophenylmethane.

Examples of metal chelate curing agents 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. is mentioned.

Examples of aziridine compounds include N,N'-hexamethylenebis(1-aziridinecarbamide), methylenebis[N-(1-aziridinylcarbonyl)-4-aniline], tetramethylolmethanetris (β-aziridinyl propionate), trimethylolpropane tris (β-aziridinylpropionate), and the like. In terms of commercial products, for example, "TAZO", "TAZM" manufactured by Sogo Pharmaceutical Co., Ltd., and "Chemitite PZ-33" manufactured by Nippon Shokubai Co., Ltd. can be mentioned.

Examples of amine compounds include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resins and methylene resins.

Examples of acrylate compounds include polyfunctional acrylates such as 1,6-hexanediol acrylate.

The content of the curing agent (B) may be appropriately changed according to the desired physical properties such as the type and degree of crosslinking of the copolymer (A). From the point of view, 0.01 to 30 parts by mass is preferable, 0.02 to 10 parts by mass is more preferable, 0.03 to 5 parts by mass is still more preferable, and 0.01 to 30 parts by mass is preferable with respect to 100 parts by mass of the copolymer (A). 05 to 3 parts by weight is particularly preferred. Among them, by setting the content of the epoxy compound as the curing agent within the above range, it is possible to highly achieve both adhesion and heat resistance in a high temperature environment up to 150°C.

The degree of cross-linking of the pressure-sensitive adhesive composition of the present invention is indicated by the gel fraction, and its measuring method is as shown in Examples. Since the higher the gel fraction, the better the restickability and the durability in a high-temperature environment, the gel fraction after cross-linking of the pressure-sensitive adhesive composition in the invention is preferably 50% or more. The gel fraction may be 100%. The degree of cross-linking of the pressure-sensitive adhesive composition can be appropriately adjusted by changing the blending amount of the curing agent (B).

In addition to the copolymer (A) and the curing agent (B), the pressure-sensitive adhesive composition of the present invention optionally contains a solvent, a tackifier, a resin other than the copolymer (A), a plasticizer, and a silane. Optional additives such as coupling agents, leveling agents, inorganic and/or organic fine particles, UV absorbers, light stabilizers, and antioxidants may also be included. The amount of these additives to be added can be appropriately selected within the range in which the effects of the present disclosure can be obtained. For example, it is preferable to appropriately set the content of the copolymer (A) within the above range.

Examples of resins other than the (meth) acrylic acid ester copolymer (A) include known thermoplastic resins, such as low density polyethylene, ultra-low density polyethylene, low crystal (amorphous) polypropylene, ionomer resin, ethylene- Ethylene copolymers such as vinyl acetate copolymers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester-maleic anhydride copolymers, ethylene-glycidyl methacrylate copolymers, and Olefin-based copolymers such as polyolefin-modified polymers, thermoplastic elastomers such as butadiene-based elastomers, ester-based elastomers, styrene-based elastomers, styrene-butadiene-based elastomers, styrene-isoprene-based elastomers, and polyurethane-based elastomers, and thermoplastics Examples include polyester, polyamide resins such as polyamide copolymers, polyurethane, polystyrene resins, cellophane, polyacrylonitrile, polyvinyl chloride-vinyl acetate copolymers and the like. These resins may be used singly or in combination of two or more. The content of these other resins is preferably less than 10% by mass based on 100% by mass of the solid content of the pressure-sensitive adhesive composition. If the content of these resins is less than 10% by mass, good compatibility can easily be obtained, and appropriate adhesive strength can be easily obtained.

When the pressure-sensitive adhesive composition of the present invention is applied to an object to be adhered, the solvent used in the polymerization of the (meth)acrylic acid ester copolymer (A) may be used as it is, or a solvent may be added. and any solvent can be used as appropriate.

Examples of solvents 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. These organic solvents may be used alone or in combination of two or more. These organic solvents can be added to adjust the viscosity of the pressure-sensitive adhesive composition, or the pressure-sensitive adhesive composition can be heated to lower the viscosity.
From the viewpoint of solubility and drying property, it is preferable to use a solvent with an SP value of 9 or more. Organic solvents having an SP value of 9 or more include ethyl acetate, butyl acetate, methyl ethyl ketone, isopropanol, and the like. Among these, it is preferable to use ethyl acetate.
On the other hand, from the viewpoint of reducing the viscosity of the pressure-sensitive adhesive composition, it is preferable to use a solvent with an SP value of less than 9. Examples of organic solvents having an SP value of less than 9 include hexane, heptane and octane.

The pressure-sensitive adhesive composition of the present invention may contain a tackifier (tackifier resin) for the purpose of adjusting the adhesive force. Examples of the tackifier include, but are not particularly limited to, rosin-based resins, terpene-based resins, synthetic hydrocarbon-based resins, and the like.

Examples of rosin-based resins include rosin ester, polymerized rosin, hydrogenated rosin, disproportionated rosin, maleic acid-modified rosin, fumaric acid-modified rosin, rosin phenolic resin, and natural rosin.

Terpene resins include, for example, α-pinene resin, β-pinene resin, dipentene resin, aromatic modified terpene resin, hydrogenated terpene resin, terpene phenol resin, acid modified terpene resin, styrenated terpene resin, and styrene-fat group hydrocarbon-based copolymer resins, and the like.

Synthetic hydrocarbon-based resins include, for example, coumarone-based resins, coumarone-indene-based resins, styrene-based resins, xylene-based resins, phenol-based resins, and petroleum-based resins.

From the viewpoint of obtaining good adhesion to the adherend, rosin-based resins and terpene-based resins are preferably used as tackifiers. You may use a tackifier individually by 1 type or in mixture of 2 or more types.

The content of the tackifier is preferably less than 30 parts by mass, more preferably 25 parts by mass or less, and 20 parts by mass or less with respect to 100 parts by mass of the acrylic acid ester copolymer (A). It is even more preferable to have When the content of the tackifier is less than 30 parts by mass, it is easy to obtain good compatibility, appropriate re-tensionability, and excellent external appearance of the molded product.

The pressure-sensitive adhesive composition of the present invention preferably contains the (meth)acrylate copolymer (A) as a main component. In addition, a main component means the component with the largest compounding quantity among all the components which an object (here, the adhesive composition of this invention) contains.
Specifically, the content of the (meth)acrylic acid ester copolymer (A) in 100% by mass of the solid content of the adhesive composition of the present invention is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, more preferably 90 to 99% by mass. If the (meth)acrylic acid ester copolymer (A) is contained in an amount of 70% by mass or more in 100% by mass of the solid content of the present pressure-sensitive adhesive composition, it can be reapplied at room temperature, and air bubbles are not included and foreign matter is not mixed. You can easily obtain a moderate adhesive strength.

The viscosity of the pressure-sensitive adhesive composition of the present invention is preferably 1,000 to 10,000 mPa·s, more preferably 1,000 to 8,000 mPa·s at 23° C. and a relative humidity of 50% (hereinafter referred to as 50% RH). , 1000 to 5000 mPa·s. Coatability can be easily ensured because the viscosity is within the above range. The method for measuring the viscosity is as shown in Examples.

<Decorative sheet>
The decorative sheet according to the present invention (hereinafter also referred to as the present decorative sheet) comprises a substrate and an adhesive layer made of a cured product of the adhesive composition of the present invention. If desired, the exposed surface of the adhesive layer can be covered with a release sheet. The release sheet is released when the pressure-sensitive adhesive sheet is attached to the adherend.
The base material is not particularly limited, and includes resin sheets, paper, metal foils, and the like. The substrate may be a laminated sheet in which any one or more layers are laminated on at least one surface of these substrates. The surface of the base material on which an arbitrary adhesive layer is to be formed may be subjected, if necessary, to an easy-adhesion treatment such as corona discharge treatment and application of an anchor coating agent.
The release sheet is not particularly limited, and a known release sheet obtained by applying a known release treatment such as coating of a release agent to the surface of a base sheet such as a resin sheet or paper can be used.

The method for producing the decorative sheet of the present invention having an adhesive layer is not particularly limited and conventionally known methods can be used as appropriate. For example, a sheet having a surface layer and a decorative layer formed thereon is coated with the present pressure-sensitive adhesive composition diluted with a solvent, if necessary, by knife coating, bar coating, blade coating, doctor coating, roll coating, cast coating, and the like. to form a coating film. Then, the adhesive layer (solidified product) can be formed on the sheet by heating and drying or curing as necessary.
In addition, when the copolymer (A) contained in the pressure-sensitive adhesive composition of the present invention requires cross-linking by active energy rays, after applying the present pressure-sensitive adhesive composition on a sheet, the active energy rays are irradiated. By doing so, an adhesive layer (crosslinked product) can be formed on the sheet. At that time, for example, the pressure-sensitive adhesive composition coated on the sheet can be irradiated with ultraviolet light using a belt conveyor type ultraviolet irradiation device to obtain the pressure-sensitive adhesive layer. The dose of ultraviolet irradiation can be, for example, 500 mJ/cm ² or more and 5000 mJ/cm ² or less.
The decorative sheet of the present invention has moderate adhesive strength at room temperature (eg, 25° C.), has excellent adhesiveness at high temperature (eg, 100 to 130° C.), and can be used at high temperature for a long period of time. (For example, 100° C., 7 days) can maintain properties. Therefore, the present decorative sheet can be applied, for example, to the decoration of aircraft, automobiles, interiors and exteriors of building materials, nursing care and medical fields, electric appliances, etc. by three-dimensional surface decoration (Three dimension Overlay Method: TOM molding).

<Decorative structure and its manufacturing method>
A decorative structure according to the present disclosure can be formed by attaching a decorative sheet to an adherend using the pressure-sensitive adhesive composition. The adherend is not particularly limited, and various shapes of adherends (for example, three-dimensional molded articles) can be used. Also, the pressure-sensitive adhesive composition of the present invention can be preferably used for attachment to adherends by vacuum forming and vacuum pressure forming. A conventionally known method can be appropriately applied to the vacuum forming method and the vacuum pressure forming method.

More specifically, the decorative structure of the present invention can include, for example, a surface layer, a decorative layer and an adhesive layer in this order.
The surface layer is a layer that becomes the surface of the decorative molded product, and conventionally known layers in the field of decorative sheets can be appropriately used. The surface layer can be made of various resins such as acrylic resin, polyurethane, fluororesin and polyvinyl chloride. Also, the exposed surface of the surface layer may be embossed.
The decorative layer is for decorating the object to be decorated, and various materials can be used depending on the intended use. The decorative layer can contain, for example, at least one resin selected from the group consisting of olefin resins, styrene resins and vinyl chloride resins. Moreover, the decorative layer may further include other layers such as a design layer, a bulk layer, and a bonding layer as optional elements. The number of layers of the decorative sheet, the type of each layer, the arrangement, the thickness, etc. can be appropriately selected and are not particularly limited.
The adhesive layer is a layer for attaching a decorative sheet to an adherend (e.g., a three-dimensional molded article), and the adhesive composition is dried (e.g., after being applied onto a substrate). Alternatively, it can be crosslinked by irradiating ultraviolet rays or the like.

EXAMPLES Next, the present disclosure is not limited by these examples, although examples will be shown and described in more detail. In the examples, "part" indicates "mass part" and "%" indicates "mass%" unless otherwise specified. In addition, the compounding amounts in the table are parts by mass.

<Measurement of weight average molecular weight (Mw)>
The Mw of the (meth)acrylate copolymer (A) was measured by the following method. The copolymer (A) dissolved in tetrahydrofuran (THF) was subjected to liquid chromatography (gel permeation chromatography) for separating and quantifying the difference in molecular size, and Mw was specified. An LC-GPC system "Prominence" (trade name) of GPC manufactured by Shimadzu Corporation was used as a measuring apparatus. Determination of the weight average molecular weight was performed in terms of polystyrene. As columns, 4 columns of GMHXL manufactured by Tosoh Corporation and 1 column of HXL-H manufactured by Tosoh Corporation were connected in series.

[Production example of (meth)acrylic acid ester copolymer (A)]
<Copolymer (A-1)>
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube (hereinafter simply referred to as "reaction vessel"), under a nitrogen atmosphere, 90 parts of n-octyl acrylate, 10 parts of acrylic acid, 65 parts of ethyl acetate, 20 parts of MEK and 0.03 part of 2,2'-azobisisobutyronitrile were charged. The mixture was heated while stirring, and after confirming the initiation of the polymerization reaction, the reaction was carried out at the reflux temperature for 2 hours. Then, 0.03 part of 2,2'-azobisisobutyronitrile was added to the reaction solution and the reaction was continued for 6 hours. Thereafter, the reaction vessel was cooled, and ethyl acetate was added to adjust the non-volatile content to 40%, thereby obtaining a copolymer (A-1) solution having a weight average molecular weight of 700,000.

<Copolymers (A-2) to (A-19), (A'-1) to (A'-6)>
In the production of the copolymers (A-2) to (A-19) and (A'-1) to (A'-6), the (meth)acrylates (a), ( Copolymers (A-2) to (A-19), (A'-1) to (A'-6) were obtained.

<Copolymer (A-20)>
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube (hereinafter simply referred to as the "reaction vessel") was charged with 60 parts of lauryl methacrylate, 30 parts of methacrylic acid, and acrylic acid under a nitrogen atmosphere. 10 parts, 30 parts of ethyl acetate, 55 parts of MEK, and 0.03 parts of 2,2'-azobisisobutyronitrile were charged. The mixture was heated while stirring, and after confirming the initiation of the polymerization reaction, the reaction was carried out at the reflux temperature for 2 hours. Then, 0.03 part of 2,2'-azobisisobutyronitrile was added to the reaction solution and the reaction was continued for 6 hours. Thereafter, the reaction vessel was cooled, and ethyl acetate was added to adjust the non-volatile content to 40% to obtain a copolymer (A-20) solution having a weight average molecular weight of 150,000.

<Copolymer (A-21)>
60 parts of lauryl methacrylate, 30 parts of methacrylic acid, 10 parts of acrylic acid, 40 parts of ethyl acetate, 45 parts of MEK, and 0.03 part of 2,2'-azobisisobutyronitrile was charged. The mixture was heated while stirring, and after confirming the initiation of the polymerization reaction, the reaction was carried out at the reflux temperature for 2 hours. Then, 0.03 part of 2,2'-azobisisobutyronitrile was added to the reaction solution and the reaction was continued for 6 hours. Thereafter, the reaction vessel was cooled, and ethyl acetate was added to adjust the non-volatile content to 40% to obtain a copolymer (A-21) solution having a weight average molecular weight of 300,000.

<Copolymer (A-22)>
60 parts of lauryl methacrylate, 30 parts of methacrylic acid, 10 parts of acrylic acid, 85 parts of ethyl acetate, 2,2 0.03 part of '-azobisisobutyronitrile was charged. The mixture was heated while stirring, and after confirming the initiation of the polymerization reaction, the reaction was carried out at the reflux temperature for 2 hours. Then, 0.03 part of 2,2'-azobisisobutyronitrile was added to the reaction solution and the reaction was continued for 6 hours. Thereafter, the reaction vessel was cooled, and ethyl acetate was added to adjust the non-volatile content to 40% to obtain a copolymer (A-22) solution having a weight average molecular weight of 1,300,000.

<Copolymer (A-23)>
60 parts of lauryl methacrylate, 30 parts of methacrylic acid, 10 parts of acrylic acid, 20 parts of acetone, 2,2′ were placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube under a nitrogen atmosphere. - 0.03 part of azobisisobutyronitrile was charged. The mixture was heated while stirring, and after confirming the initiation of the polymerization reaction, the reaction was carried out at the reflux temperature for 2 hours. Then, 0.03 part of 2,2'-azobisisobutyronitrile was added to the reaction solution and the reaction was continued for 6 hours. Thereafter, the reaction vessel was cooled, and ethyl acetate was added to adjust the non-volatile content to 40% to obtain a copolymer (A-23) solution having a weight average molecular weight of 1,500,000.

<Copolymer (A-24)>
60 parts of lauryl methacrylate, 30 parts of methacrylic acid, 10 parts of acrylic acid, 55 parts of ethyl acetate, and 30 parts of acetone were placed in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen inlet tube under a nitrogen atmosphere. , 0.03 part of 2,2′-azobisisobutyronitrile was charged. The mixture was heated while stirring, and after confirming the initiation of the polymerization reaction, the reaction was carried out at the reflux temperature for 2 hours. Then, 0.03 part of 2,2'-azobisisobutyronitrile was added to the reaction solution and the reaction was continued for 6 hours. Thereafter, the reaction vessel was cooled, and ethyl acetate was added to adjust the non-volatile content to 40% to obtain a copolymer (A-24) solution having a weight average molecular weight of 1,800,000.

Exemplary compounds are specifically shown in Tables 1 and 2 below, but are not limited to these.

Abbreviations in Tables 1 and 2 are listed below.
[(meth)acrylate (a)]
NOA: n-octyl acrylate (8 carbon atoms in the alkyl group)
LA: Lauryl acrylate (alkyl group has 12 carbon atoms)
LMA: Lauryl methacrylate (alkyl group has 12 carbon atoms)
STA: stearyl acrylate (alkyl group has 18 carbon atoms)
[(meth)acrylate (b)]
MA: methyl acrylate (1 carbon number of alkyl group)
BA: butyl acrylate (alkyl group has 4 carbon atoms)
[Other monomers]
2EHA: 2-ethylhexyl acrylate VAc: vinyl acetate AA: acrylic acid HEA: hydroxyethyl acrylate ISTA: isostearyl acrylate BEA: behenyl acrylate (alkyl group has 21 carbon atoms)
CHA: cyclohexyl acrylate

(Example 1)
To 100 parts of the copolymer (A-1) obtained in the above production example, 0.1 part of TETRAD-X (Mitsubishi Gas Chemical Co., Ltd.) as a curing agent (B) (in terms of non-volatile content) is blended, Furthermore, ethyl acetate was added as a solvent to adjust the non-volatile content to 30%, thereby obtaining a pressure-sensitive adhesive composition of Example 1. The pressure-sensitive adhesive composition thus obtained was evaluated according to the measurement method and evaluation method described below.

<Gel fraction>
The pressure-sensitive adhesive composition thus obtained was applied onto the release-treated surface of a polyethylene terephthalate (PET) film (thickness: 38 μm), one side of which had been subjected to release treatment, so that the thickness after drying would be 25 μm. Subsequently, after drying at 105° C. for 2 minutes, the coating film was laminated on a base material (made of polyethylene terephthalate) having a thickness of 50 μm and aged at 23° C. and 50% RH for 7 days.
A test piece having a width of 3 mm and a length of 100 mm was cut out from the obtained pressure-sensitive adhesive sheet, and the weight thereof was measured. Peel off the release sheet from the test piece, attach the exposed adhesive layer to a 300-mesh stainless steel wire mesh, fold the wire mesh so that the test piece does not peel off, and add ethyl acetate as an extract solution while wrapping the test piece. It was immersed and allowed to stand at 50°C for 24 hours. After the immersion, the wire mesh was taken out, washed with a small amount of ethyl acetate, dried at 100° C. for 30 minutes, and weighed. The gel fraction was calculated by the following formula (1).
(Gel fraction) = {(W2-W0-W3)/(W1-W0-W3)} x 100 (Formula 1)
W0: weight of wire mesh W1: weight of wire mesh + test piece W2; weight of wire mesh + test piece after drying W3: weight of substrate of test piece

<Viscosity>
The viscosity of the resulting pressure-sensitive adhesive composition was measured at 60 rpm using a Brookfield viscometer in an atmosphere of 23° C.-50% RH.

<Method for making decorative sheet>
The pressure-sensitive adhesive composition thus obtained was applied onto the release-treated surface of a polyethylene terephthalate (PET) film (thickness: 38 μm), one side of which had been subjected to release treatment, so that the thickness after drying would be 25 μm. Subsequently, after drying at 105° C. for 2 minutes, the coating film was attached to a commercially available vinyl chloride film and aged for 7 days in an atmosphere of 23° C.-50% RH to prepare a decorative sheet.

<Coatability>
The coatability of the pressure-sensitive adhesive composition when obtaining a decorative sheet by the method described above was evaluated based on the following evaluation criteria.
(Evaluation criteria)
AA: When coated at coating speeds of 30 m/min and 50 m/min, the coated surface was smooth and no streaks occurred. Very good.
A: When coated at a coating speed of 30 m/min, the coated surface was smooth and no streaks occurred, and when coated at a coating speed of 50 m/min, one or two streaks occurred on the coated surface. . Good.
B: One or two streaks occurred on the coated surface when the coating was applied at a coating speed of 30 m/min. Practical.
C: Three or more streaks occurred on the coated surface when the coating was applied at a coating speed of 30 m/min. Not practical.

<Restickability>
The decorative sheet obtained by the above method was evaluated for reattachability to the ABS resin plate when attached to the mold of a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd., NGF molding machine) based on the following evaluation criteria. bottom.
(Evaluation criteria)
AA: No trace of peeling remained on the surface of the sample, and no peeling sound was heard. Very good.
A: There was no peeling mark on the sample surface, but there was a peeling sound. Good.
B: Peeling traces partially remained on the sample surface. Practical.
C: Traces of peeling remained on the entire surface of the sample. Not practical.

<Durability after molding>
After attaching the decorative sheet obtained by the above-described method to the mold of a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd., NGF molding machine), an ABS resin plate of 10 cm × 7 cm × thickness 5 mm was set in the frame. . After that, molding was performed at 130° C. so as to cover the ABS resin plate with a decorative sheet to obtain a molding. Then, after leaving the obtained molding in an atmosphere of 23° C.-50 RH% for 24 hours, a 5-cm-long incision was made in the surface of the molding, and left at high temperature (100° C. and 150° C.) for 168 hours. , Lifting and displacement were evaluated based on the following criteria.
(Evaluation criteria)
AA: There was no lifting or peeling, but a shift of less than 1 mm occurred. Very good.
A: Although there was no lift or peeling, deviation of 1 mm or more and less than 3 mm occurred. Good.
B: No lifting or peeling occurred, but deviation of 3 mm or more and less than 10 mm occurred. Practical.
C: Lifting and peeling occurred. Not practical.

<Water resistant curved surface adhesion retention>
After attaching the decorative sheet obtained by the above-described method to the mold of a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd., NGF molding machine), an ABS resin plate of 10 cm × 7 cm × thickness 5 mm and a 50 mmφ A cylindrical polypropylene (PP) resin was set. Thereafter, the cylindrical polypropylene (PP) resin was molded at 130° C. so as to cover the circumferential direction of the cylindrical polypropylene (PP) resin with a decorative sheet to obtain a molding. After that, the resulting molded product was left in an atmosphere of 23 ° C.-50 RH% for 24 hours, a 4 cm long cut was made on the surface of the molded product in a cross shape, and the cut of the measurement sample was immersed in water at 40 ° C. for 24 hours. The state of the part was evaluated based on the following evaluation criteria.
(Evaluation criteria)
AA: No lifting or peeling. Very good.
A: Lifting and peeling are more than 0 mm in length and less than 3 mm. Good.
B: Lifting and peeling are 3 mm or more and less than 8 mm in length. Practical.
C: Lifting and peeling are 8 mm or more in length. Not practical.

<Appearance of coating film after molding>
After attaching the decorative sheet obtained by the above-described method to the mold of a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd., NGF molding machine), an ABS resin plate of 10 cm × 7 cm × thickness 5 mm was set in the frame. . After that, molding was performed at 130° C. so as to cover the ABS resin plate with a decorative sheet to obtain a molding. The surface condition after this molding was evaluated based on the following evaluation criteria.
(Evaluation criteria)
AA: No defect occurred. Very good.
A: Occurrence of 1 or more but less than 5 defects. Good.
B: 5 or more and 9 or less defects occurred. Practical.
C: 10 or more defects occurred. Not practical.

(Examples 2 to 32, Comparative Examples 1 to 7)
Contents described in Tables 3 and 4 for the (meth)acrylic acid ester copolymers (A) and (A'), the curing agent (B), and the types and amounts of the tackifiers contained in the pressure-sensitive adhesive composition PSA compositions and PSA sheets of Examples 2 to 32 and Comparative Examples 1 to 7 were obtained in the same manner as in Example 1, except for changing to . Exemplary compounds are specifically shown in Tables 3 and 4, but are not limited to these.

Abbreviations in Tables 3 and 4 are described below.
[Curing agent (B)]
TETRAD-X: epoxy-based cross-linking agent (manufactured by Mitsubishi Gas Chemical Company, N,N,N',N'-tetraglycidyl-m-xylylenediamine)
TETRAD-C: epoxy cross-linking agent (Mitsubishi Gas Chemical Co., Ltd., N,N,N',N'-tetraglycidyl-1,3-bisaminomethylcyclohexane)
TDI-TMP: trimethylolpropane adduct of tolylene diisocyanate
Aluminum chelate A: aluminum trisacetylacetonate (manufactured by Kawaken Fine Chemicals)
[Tackifier]
T-130: Terpene-based resin manufactured by Yasuhara Chemical Co., Ltd. D-125: Rosin-based resin manufactured by Arakawa Chemical Industries, Ltd. FTR6100: Aromatic hydrocarbon resin manufactured by Mitsui Chemicals, Inc.

The present invention is not limited to the above-described embodiments and examples, and design changes are possible as appropriate without departing from the gist of the present invention.

As shown in Examples 1 to 32 in Table 3, the pressure-sensitive adhesive composition of the present invention was excellent in coatability, re-tensionability, durability at high temperatures, water-resistant curved surface adhesion retention, and appearance of molded articles. . On the other hand, Comparative Examples 1 to 7 in Table 4 were found to be inferior in the above physical properties.
The present pressure-sensitive adhesive composition having excellent properties as described above can be suitably used for various processed pressure-sensitive adhesive products such as pressure-sensitive adhesive films, pressure-sensitive adhesive sheets, pressure-sensitive adhesive tapes and labels. Specific examples of adhesive processed products include adhesive sheets, adhesive films, adhesive tapes, pressure-sensitive tapes, surface protective films, surface protective tapes, masking tapes, electrical insulating tapes, laminates, and the like. Further, the composition of the present invention can be suitably used for decoration of, for example, aircraft, automobiles, railroads, interior and exterior building materials, nursing care and medical fields, electrical appliances, and the like, and its usage is not particularly limited.

Claims (6)

(Meth) acrylic acid ester copolymer (A) and a curing agent (B),
The (meth)acrylate copolymer (A) is a copolymer of a monomer mixture,
In 100% by mass of the monomer mixture, the content of linear alkyl (meth)acrylate (a) having an alkyl group with 8 to 18 carbon atoms is 10 to 95% by mass,
A decorative sheet pressure-sensitive adhesive composition for attaching a decorative sheet to an adherend by vacuum forming or vacuum pressure forming . The monomer mixture constituting the (meth)acrylic acid ester copolymer (A) further contains an alkyl (meth)acrylate (b) having an alkyl group with 1 to 4 carbon atoms,
2. The pressure-sensitive adhesive composition for decorative sheet according to claim 1, wherein the content of the alkyl (meth)acrylate (b) is 1 to 50% by mass in 100% by mass of the monomer mixture. 2. The pressure-sensitive adhesive composition for a decorative sheet according to claim 1, wherein the gel fraction after cross-linking is 50% or more. A decorative sheet comprising a substrate and an adhesive layer comprising the adhesive composition for decorative sheet according to any one of claims 1 to 3 . A decorative structure comprising an adherend and the decorative sheet according to claim 4 . 5. A method for producing a decorative structure, comprising forming a decorative structure in which the decorative sheet according to claim 4 is integrated with an adherend by a vacuum forming method or a vacuum pressure forming method.