Adhesive composition for decorative sheets, decorative sheet, decorative structure and method for producing the same

Abstract

To provide an adhesive composition for a decorative sheet which conforms a complicated shape having an uneven part in decoration of molded articles, and is excellent in adhesion to a low-polarity adherend, transparency, and durability that enables molded articles to maintain excellent appearance even under high-temperature or high-temperature / high-humidity environments, and to provide a decorative sheet, a decorative structure, and a method for producing the same.SOLUTION: An adhesive composition for a decorative sheet comprises a (meth)acrylate ester copolymer (A), a curing agent (B) and a polyolefin (C), wherein the polyolefin (C) is contained in an amount of 0.01 pt.mass or more and less than 10 pts.mass based on 100 pts.mass of the (meth)acrylate ester copolymer (A).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an adhesive composition for a decorative sheet, a decorative sheet, a decorative structure, and a method for manufacturing the same.

Background Art

[0002] As a means of improving the appearance quality of molded products such as automotive interior and exterior parts, keyboards, home appliances, smartphones, housing building materials, furniture, musical instruments, and the walls of Shinkansen window frames, the exterior surface of the molded product is decorated with a decorative film (decorative sheet). As methods for decorating a molded product having a three-dimensional shape using a decorative sheet, an insert molding method, an in-mold molding method, a vacuum molding method, a vacuum-pressure air molding method, and the like are known.

[0003] The insert molding method is a method of producing a decorated molded product in which a decorative sheet is pre-shaped into a predetermined shape and inserted into a mold, then a heat-melted resin is pressurized and poured into the mold for injection molding, cooled and solidified, and the decorative sheet and the molded product are integrated. In addition, the in-mold molding method is a method of producing a decorated molded product by setting a film with a design print in a mold through a release layer, injecting and molding a heat-melted resin, cooling and solidifying it, and then peeling off this film to transfer the design. As described above, in the insert molding method and the in-mold molding method, the molded product is decorated simultaneously with the molding of the molded product, and a design is formed on the exterior surface of the molded product.

[0004] On the other hand, the vacuum molding method is a method of heating the decorative sheet to soften it, creating a state close to a vacuum by evacuating the air between the decorative sheet and the molded product from the molded product side, and adhering the decorative sheet to the molded product. In addition, the vacuum-pressure air molding method is a method of creating a state close to a vacuum in the same way, and further applying air pressure from the decorative sheet side above the molded product to adhere the decorative sheet to the molded product. Thus, the vacuum forming method and the vacuum-pressure air forming method are methods of decorating a molded product by laminating a decorative sheet at room temperature and heating it after the molded product is completed. That is, in a separate operation from the molding of the molded product, the decorative sheet is attached to the outer surface of the molded product, so that the decorative sheet can be attached to molded products of various shapes with a single device. In addition, in the vacuum forming method and the vacuum-pressure air forming method, continuous coating from the front surface to the back surface at the end of the molded product, that is, wrap-around coating, which is difficult in the in-mold molding method, etc., is also possible, so it is widely used.

[0005] Compared with acrylonitrile-butadiene-styrene resin (hereinafter also referred to as ABS resin), which is generally widely used as the material of the adherend, polypropylene resin (hereinafter also referred to as PP resin) has a low specific gravity and excellent thermoformability. For this reason, in recent years, the use of PP resin as an adherend for weight reduction and improvement of processability has been increasing. An adhesive is used for sticking the decorative sheet to the adherend, and the need for an adhesive capable of laminating the decorative sheet to a low-polarity material such as PP resin is increasing.

[0006] Patent Document 1 discloses a molded body obtained by thermocompression bonding an adhesive film having an adhesive layer containing a (meth)acrylic polymer containing a carboxyl group at a specific ratio and having a glass transition temperature of 25°C or lower, and a (meth)acrylic polymer containing an amino group at a specific ratio and having a glass transition temperature of 75°C or higher.

[0007] Patent Document 2 discloses a copolymer of methyl acrylate and an alkyl acrylate containing an alkoxy group having 4 carbon atoms, and a (meth)acrylic acid alkyl ester having a glass transition temperature of 115°C or lower and a weight average molecular weight of 5,000 to 100,000, and a decorative molding film containing an adhesive layer characterized by containing 1 to 40 parts by weight of the (meth)acrylic acid alkyl ester with respect to 100 parts by weight of the copolymer.

Prior Art Documents

Patent Documents

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-035588 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-132205 [Summary of the Invention] [Problems to be Solved by the Invention]

[0009] Generally, when attaching a decorative sheet to a molded article by a vacuum forming method or a vacuum-pressure air forming method, the decorative molded article is assumed to be used in various environments. Therefore, it is important to follow a complicated shape having uneven portions and to have durability that does not cause appearance defects such as floating or peeling at the adhesive interface with the adhesive layer even in a high-temperature or high-temperature and high-humidity environment. In addition, since the PP resin is a low-polarity material, it is difficult to adhere, which has been a problem. Furthermore, from the viewpoint of design, the importance of high transparency has increased, and there is a demand for an adhesive composition for a decorative sheet that can satisfy such various performances in a well-balanced manner.

[0010] As a result of investigations by the inventors, the adhesive compositions described in Patent Document 1 and Patent Document 2 did not exhibit satisfactory performance with respect to the PP resin, which is a low-polarity adherend.

[0011] That is, in the decoration of a molded article, an adhesive composition for a decorative sheet that follows a complicated shape having uneven portions, has excellent adhesiveness to a low-polarity adherend, transparency, and durability capable of imparting an excellent appearance to the molded article even in a high-temperature or high-temperature and high-humidity environment has not been developed so far. [Means for Solving the Problems]

[0012] As a result of intensive investigations to solve the above problems, the inventors have arrived at the present invention. That is, it contains a (meth)acrylic acid ester copolymer (A), a curing agent (B), and a polyolefin (C), and is characterized in that it contains 0.01 part by mass or more and less than 10 parts by mass of the polyolefin (C) with respect to 100 parts by mass of the (meth)acrylic acid ester copolymer (A). [Advantages of the Invention]

[0013] According to the present invention, in the decoration of molded articles, it is possible to follow a complicated shape having uneven portions, and to provide an adhesive composition for a decorative sheet, a decorative sheet, a decorative structure, and a method for manufacturing the same, which have excellent durability capable of imparting excellent adhesion to a low-polarity adherend, transparency, and appearance to the molded article even under high-temperature or high-temperature and high-humidity environments. [Embodiments for Carrying Out the Invention]

[0014] The adhesive composition for a decorative sheet, the decorative sheet, the decorative structure, and the method for manufacturing the decorative structure according to the present invention have the following configurations [1] to [8].

[0015] [1] An adhesive composition for a decorative sheet containing a (meth)acrylic acid ester copolymer (A), a curing agent (B), and a polyolefin (C), and containing 0.01 part by mass or more and less than 10 parts by mass of the polyolefin (C) with respect to 100 parts by mass of the (meth)acrylic acid ester copolymer (A).

[0016] [2] The (meth)acrylic acid ester copolymer (A) is a copolymer of a monomer mixture containing any two or more selected from the group consisting of the following (a1), (a2), and (a3), and the total content rate of (a1), (a2), and (a3) is 75% by mass or more in 100% by mass of the monomer mixture. The adhesive composition for a decorative sheet. The total content rate of (a1), (a2), and (a3) is 75% by mass or more in 100% by mass of the monomer mixture. The adhesive composition for a decorative sheet. (a1): A (meth)acrylic acid alkyl ester monomer in which the glass transition temperature of the homopolymer is 0°C or lower and the carbon number of the alkyl group is 4 to 8. (a2): A (meth)acrylic acid alkyl ester monomer in which the carbon number of the alkyl group is 1 to 3. (a3): A vinyl ester monomer of a carboxylic acid having an alkyl group with 1 to 3 carbon atoms.

[0017] [3] The adhesive composition for a decorative sheet, wherein the polyolefin (C) is a chlorinated polyolefin (C1).

[0018] [4] The pressure-sensitive adhesive composition wherein the degree of chlorination of the polyolefin (C1) is 20% by mass or more and less than 45% by mass.

[0019] [5] The pressure-sensitive adhesive composition for a decorative sheet used for attachment to an adherend by a vacuum forming method or a vacuum-pressure air forming method.

[0020] [6] A decorative sheet including a base material and an adhesive layer made of the pressure-sensitive adhesive composition for a decorative sheet.

[0021] [7] A decorative structure including an adherend and the decorative sheet, wherein the adherend is any one of interior and exterior automotive parts, parts for household appliances, and parts for building materials.

[0022] [8] A method for manufacturing a decorative structure, characterized by forming the decorative structure in which the adherend and the decorative sheet are integrated by a vacuum forming method or a vacuum-pressure air forming method.

[0023] Hereinafter, the present invention will be described in detail. Needless to say, other embodiments are also included in the scope of the present invention as long as they conform to the gist of the present invention.

[0024] In the present invention, the "sheet" means a flexible laminate, and also includes a thin laminate called a "film".

[0025] In the present invention, "(meth)acryl" means either or both of "acryl" and "methacryl", and "(meth)acrylate" means either or both of "acrylate" and "methacrylate".

[0026] In the present invention, the numerical range specified using "~" includes the numerical values described before and after "~" as the range of the lower limit value and the upper limit value.

[0027] In this specification, "Mw" is the weight-average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC) measurement. These weight-average molecular weights can be measured by the method described in the section of [Examples].

[0028] In addition, the embodiments of the present invention will be described in detail below. However, the following description is an example (representative example) of the embodiments of the present invention, and the present invention is not limited to these contents unless it exceeds the gist thereof.

[0029] <Adhesive Composition> The adhesive composition of the present invention contains a (meth)acrylate copolymer (A), a curing agent (B), and a polyolefin (C), and contains 0.01 part by mass or more and less than 10 parts by mass of the polyolefin (C) with respect to 100 parts by mass of the (meth)acrylate copolymer (A). It is characterized by this.

[0030] <(Meth)acrylate Copolymer (A)> The (meth)acrylate copolymer (A) (hereinafter also referred to as copolymer (A)) is a copolymer obtained by polymerizing all or part of a monomer mixture containing a (meth)acrylate, and a monomer having a functional group and other monomers are used as necessary.

[0031] The (meth)acrylate copolymer (A) is preferably a copolymer of a monomer mixture containing any two or more selected from the group consisting of the following (a1), (a2), and (a3). The total content rate of (a1), (a2), and (a3) is preferably 75% by mass or more, more preferably 82% by mass or more, and particularly preferably 90% by mass or more in 100% by mass of the monomer mixture. By being in the above range, adhesiveness to a low-polarity adherend and unevenness followability can be ensured. The upper limit of the total content rate of (a1), (a2), and (a3) is preferably less than 100% by mass, more preferably 98% by mass or less, from the viewpoint of achieving both adhesiveness and durability. (a1): A (meth)acrylic acid alkyl ester monomer in which the glass transition temperature of the homopolymer is 0 °C or lower and the number of carbon atoms of the alkyl group is 4 to 8 (a2): A (meth)acrylic acid alkyl ester monomer in which the number of carbon atoms of the alkyl group is 1 to 3 (a3): A vinyl ester monomer of a carboxylic acid having an alkyl group with 1 to 3 carbon atoms

[0032] The monomer mixture constituting the (meth)acrylic acid ester copolymer (A) more preferably contains (a1), and particularly preferably contains both (a1) and (a2). By containing both (a1) and (a2), it is possible to achieve both high adhesion and durability at a high level.

[0033] In the present invention, the glass transition temperature (Tg) of the copolymer (A) is a value calculated based on the following formula (1) (Fox formula). 1 / Tg = W1 / Tg1 + W2 / Tg2 + ··· + Wn / Tgn (Formula 1) [In Formula (1), Tg is the Tg of the acrylic polymer (A) (unit: K), Tgi (i = 1, 2, ··· n) is the Tg (unit: K) when the radical polymerizable monomer i forms a homopolymer, and Wi (i = 1, 2, ··· n) represents the mass fraction of the radical polymerizable monomer i in all monomer components. The Tg of the homopolymer uses published values such as literature values and catalog values.] The above formula (1) is a calculation formula when the copolymer (A) is composed of n types of monomer components of monomer 1, monomer 2, ···, monomer n.

[0034] The glass transition temperature of the homopolymer is 0 °C or lower and the number of carbon atoms in the alkyl group is 4 to 8. The (meth)acrylic acid alkyl ester monomer (a1) is not particularly limited, but specifically, butyl acrylate (Tg: -54 °C), isobutyl acrylate (Tg: -24 °C), 2-ethylhexyl acrylate (Tg: -70 °C), n-octyl acrylate (Tg: -65 °C), 2-octyl acrylate (Tg: -44 °C), etc. can be mentioned. From the viewpoints of compatibility with polyolefin and unevenness followability, 2-ethylhexyl acrylate and 2-octyl acrylate are preferred.

[0035] From the viewpoints of compatibility with polyolefin and unevenness followability, the content of (a1) in a total of 100% by mass of (a1), (a2) and (a3) is preferably 40% by mass or more and less than 95% by mass, and more preferably 50% by mass or more and less than 90% by mass.

[0036] The (meth)acrylic acid alkyl ester monomer (a2 ) in which the number of carbon atoms in the alkyl group is 1 to 3 includes methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, etc. From the viewpoint of durability after molding, methyl (meth)acrylate and ethyl (meth)acrylate are preferred. From the viewpoint of durability after molding, the content of (a2) in a total of 100% by mass of (a1), (a2) and (a3) is preferably 3% by mass or more and less than 58% by mass, and more preferably 5% by mass or more and less than 45% by mass.

[0037] Examples of the vinyl ester monomer (a3) of a carboxylic acid having an alkyl group with 1 to 3 carbon atoms include vinyl acetate, vinyl propionate, vinyl butyrate, etc. From the viewpoint of adhesive strength, vinyl acetate is preferred. From the viewpoint of adhesive strength, the content of (a3) in a total of 100% by mass of (a1), (a2) and (a3) is preferably less than 59% by mass.

[0038] The monomer mixture constituting the copolymer (A) preferably further contains a monomer having a functional group that forms a crosslinked structure with the curing agent (B). Examples of the functional group include a hydroxyl group, an acidic group, an unsaturated group (double bond group), an epoxy group, and the like. These may be used alone or in combination of two or more. From the viewpoints of substrate adhesion and durability after molding, the monomer mixture constituting the copolymer (A) particularly preferably contains a hydroxyl group-containing monomer and / or an acidic group-containing monomer, and more preferably contains an acidic group-containing monomer.

[0039] Examples of the acidic group-containing monomer include (meth)acrylic acid, 2-carboxyethyl acrylate, itaconic acid, maleic acid, styrene sulfonic acid, 2-(meth)acryloyloxyethyl-succinic acid, 2-(meth)acryloyloxyethyl-phthalic acid, 2-acryloyloxyethyl hexahydrophthalic acid, and the like. These may be used alone or in combination of two or more. Among them, (meth)acrylic acid and 2-carboxyethyl acrylate are preferable from the viewpoint of polymerizability.

[0040] The content of the acidic group-containing monomer in 100% by mass of the monomer mixture constituting the copolymer (A) is not particularly limited, but is preferably 0.1 to 10% by mass from the viewpoint of compatibility with polyolefin.

[0041] Examples of the hydroxyl group-containing monomer include (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 3-chloro-2-hydroxypropyl, (meth)acrylic acid 4-hydroxybutyl, (meth)acrylic acid 6-hydroxyhexyl, (meth)acrylic acid 8-hydroxyoctyl, and (meth)acrylate-based monomers having a hydroxyl group such as polyalkylene glycol mono(meth)acrylate, and allyl ether-based monomers having a hydroxyl group such as polyalkylene glycol allyl ether. From the viewpoints of copolymerizability and reactivity with the curing agent (B), (meth)acrylic acid 2-hydroxyethyl or (meth)acrylic acid 4-hydroxybutyl is preferable.

[0042] Furthermore, the monomer mixture constituting the copolymer (A) may contain (a1), (a2), (a3), and other monomers other than the monomer having a functional group. Examples of the other monomers include the following.

[0043] Nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (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, isostearyl (meth)acrylate, behenyl (meth)acrylate, eicosanyl (meth)acrylate, hexacosanyl (meth)acrylate Alkyl (meth)acrylate monomers having an alkyl group with 9 to 26 carbon atoms such as cyclohexyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and 3,3,5-trimethylcyclohexyl (meth)acrylate; (meth)acrylate ester monomers having an aliphatic ring (meth)acrylate ester monomers having an aromatic ring such as benzyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 2-(o-phenylphenoxy)ethyl (meth)acrylate, and nonylphenoxypolyethylene glycol (meth)acrylate; (meth)acrylate ester monomers having an alkoxy group such as 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 4-ethoxybutyl (meth)acrylate; (Meth)acrylic acid esters monomers having a polyether chain such as methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, ethoxypolypropylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, and phenoxypolypropylene glycol (meth)acrylate; N-vinyl cyclic amide monomers such as 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-3,5-morpholinedione; (Meth)acrylamide 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-dialkyl(meth)acrylamide monomers such as 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-di(t-butyl)(meth)acrylamide; N-hydroxyalkyl(meth)acrylamide monomers such as 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-methyl-N-2-hydroxyethyl(meth)acrylamide; N-alkoxyalkyl(meth)acrylamides such as N-methoxymethyl(meth)acrylamide and N-butoxymethyl(meth)acrylamide; Monomers having acidic groups excluding carboxyl groups such as 2-(meth)acryloyloxyethyl acid phosphate and 2-methacryloyloxyethyl acid phosphate; These may or may not be included in the monomer mixture constituting the copolymer (A) as required.

[0044] The content of other monomers in 100% by mass of the monomer mixture constituting the copolymer (A) is not particularly limited, but is preferably 10% by mass or less from the viewpoint of adhesion.

[0045] (Meth)acrylic acid ester copolymer (A) is not particularly limited in its polymerization form. That is, the copolymer (A) may be any of alternating copolymers, random copolymers, block copolymers, and graft copolymers containing (meth)acrylic acid alkyl esters and other monomers. For example, the block copolymer may be a diblock or a triblock. Any of alternating copolymers, random copolymers, block copolymers, and graft copolymers such as those containing (meth)acrylic acid alkyl esters and other monomers may be used. For example, the block copolymer may be a diblock or a triblock.

[0046] For the synthesis of the copolymer (A), conventionally known methods can be used. For example, it can be produced by known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization, and suspension polymerization. Also, for the synthesis of the copolymer (A), known polymerization methods such as living radical polymerization and active energy ray polymerization can be appropriately used. In that case, the monomer mixture for synthesizing the copolymer (A) can contain a photoinitiator and conventionally known additives. As the active energy ray, ultraviolet rays, visible light, X-rays, gamma rays, or electron beams can be used. Also, for the irradiation of ultraviolet rays, 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.

[0047] The blending ratio of each structural unit (monomer component) of the copolymer (A) can be specified using various instruments such as nuclear magnetic resonance analysis (NMR) and gas chromatography (GC).

[0048] The weight average molecular weight (Mw) of the (meth)acrylic acid ester copolymer (A) is preferably more than 300,000, more preferably 500,000 or more, and even more preferably 600,000 or more. Also, the weight average molecular weight of the copolymer (A) is preferably 1,500,000 or less, more preferably 1,300,000 or less, and even more preferably 1,200,000 or less. When the Mw of the copolymer (A) is within the above range, it is easy to ensure a viscosity suitable for coating, and after decorating the molded product, it is possible to easily prevent the decorative sheet part from shifting and the appearance of the decorated molded product from deteriorating.

[0049] <Hardener (B)> The pressure-sensitive adhesive composition of the present invention contains a hardener (B). By introducing a crosslinking group into the (meth)acrylic acid ester copolymer (A) and crosslinking it with the hardener (B), the cohesive force, adhesive force, and durability after molding of the pressure-sensitive adhesive layer can be enhanced.

[0050] Examples of the hardener (B) include isocyanate-based hardeners, epoxy-based hardeners, aziridine-based hardeners, metal chelate-based hardeners, amine-based hardeners, and acrylate-based hardeners. Among these, isocyanate-based hardeners, epoxy-based hardeners, and metal chelate-based hardeners are preferred, epoxy-based hardeners and metal chelate-based hardeners are more preferred from the viewpoint of re-stickability, and epoxy-based hardeners are particularly preferred from the viewpoint of durability in a high-temperature environment. The hardener is preferably used alone.

[0051] Examples of the isocyanate curing agent include adducts of diisocyanates such as 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 with polyol compounds such as trimethylolpropane, as well as their burette bodies, isocyanurate bodies, and adducts of the above diisocyanates with any of polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, and polyisoprene polyols, etc., which are compounds having three or more isocyanate groups in the molecule; tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene di diisocyanates such as isocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, and polymethylene polyphenyl isocyanate, and compounds having two isocyanate groups in the molecule such as the allophanate body of hexamethylene diisocyanate; etc. Among these, the trimethylolpropane adduct of tolylene diisocyanate is preferable because the adhesive physical properties can be easily adjusted. The number of isocyanate groups is the average number.

[0052] Examples of epoxy curing agents include bisphenol A-epichlorohydrin type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidylaminophenylmethane. From the viewpoints of curability and durability, N,N,N',N'-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane are particularly preferred.

[0053] Examples of aziridine curing agents include β-aziridinyl propionate, trimethylolpropane tris(β-aziridinyl propionate), etc. Also, in terms of commercially available products, for example, "TAZO", "TAZM" manufactured by Sogo Yakuhin Kogyo Co., Ltd., "Chemite PZ-33" manufactured by Nippon Shokubai Co., Ltd., etc. can be mentioned.

[0054] 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 with acetylacetone or ethyl acetoacetate.

[0055] Examples of amine curing agents include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, amino resins, and methylene resins.

[0056] Examples of acrylate curing agents include polyfunctional acrylates such as 1,6-hexanediol diacrylate.

[0057] 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 viewpoints of adhesiveness, re-stickability, and durability at high temperatures, 0.01 to 3 parts by mass, more preferably 0.015 to 1 part by mass, still more preferably 0.018 to 0.5 part by mass, and particularly preferably 0.02 to 0.06 part by mass, are preferred with respect to 100 parts by mass of the copolymer (A). 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.

[0058] The degree of crosslinking of the pressure-sensitive adhesive composition of the present invention is represented by the gel fraction, and the measurement method is as shown in the examples. Since the higher the gel fraction, the better the re-stickability and durability after molding, the gel fraction after crosslinking of the pressure-sensitive adhesive composition in the present invention is preferably 50% or more. The gel fraction may be 100%. The degree of crosslinking of the pressure-sensitive adhesive composition can be appropriately adjusted by changing the blending amount of the curing agent (B) and the like. The gel fraction of the present invention is a numerical value calculated by the following formula (2) after peeling off the release sheet from the adhesive sheet to expose the adhesive layer, attaching it to SUS200 mesh (aperture: 0.077 mm, wire diameter: 0.05 mm), immersing it in ethyl acetate, extracting it at 50 °C for 24 hours, drying it at 100 °C for 30 minutes. Formula (2) Gel fraction (mass%) = (G2 / G1) × 100 G1: Mass of the adhesive layer before extraction with ethyl acetate G2: Mass of the adhesive layer after extraction and drying with ethyl acetate

[0059] <Polyolefin (C)> The polyolefin (C) has a high affinity for a low-polarity adherend such as polypropylene and can effectively improve the adhesiveness. Furthermore, due to the polarity difference from the acrylic polymer (A), the polyolefin (C) is likely to be oriented at the interface of the pressure-sensitive adhesive coating film, and the adhesiveness to a low-polarity adherend such as a PP resin can also be improved.

[0060] The polyolefin (C) is classified into a chlorinated polyolefin (C1) and a non-chlorinated polyolefin (C2). Examples of the chlorinated polyolefin (C1) include chlorinated polypropylene, acid-modified chlorinated polypropylene, acrylic-modified chlorinated polypropylene, chlorinated polyethylene, chlorinated ethylene-vinyl acetate copolymer, and the like. Among these, chlorinated polypropylene, acid-modified chlorinated polypropylene, and acrylic-modified chlorinated polypropylene are preferred because of their excellent solubility and high effect of improving adhesion to low-polarity adherends, and chlorinated polypropylene is more preferred. The chlorinated polyolefin (C1) may be used alone or in combination of two or more.

[0061] The chlorine content of the chlorinated polyolefin (C) is preferably 20% by mass or more and less than 45% by mass, more preferably 30 to 40% by mass. When the chlorine content is 20% by mass or more and less than 45% by mass, the compatibility with the acrylic polymer (A) is enhanced, and a sufficient effect of improving adhesion to low-polarity adherends can be obtained. The chlorine content refers to the content of chlorine in the total mass of the chlorinated polyolefin.

[0062] Examples of the non-chlorinated polyolefin (C2) include polyethylene, polypropylene, α-olefin-propylene copolymer, ethylene-vinyl acetate copolymer, polybutene, maleated polybutene, polybutadiene and its hydride, polyisoprene and its hydride, maleated polybutadiene, maleated polyisoprene, polybutadiene polyol and its hydride, polyisoprene polyol and its hydride, lubricating oils such as process oil and liquid paraffin. Among these, α-olefin-polypropylene copolymer, polybutene, and lubricating oil are preferred because of their excellent solubility and high adhesive strength to low-polarity adherends. As the lubricating oil, paraffinic lubricating oil, naphthenic lubricating oil, etc. are preferred.

[0063] As the polyolefin (C) used in the adhesive of the present invention, it is preferable to contain a chlorinated polyolefin (C1) because a high effect of improving adhesion to low-polarity adherends such as polypropylene can be obtained.

[0064] The weight average molecular weight of the polyolefin (C) is not particularly limited, but is preferably from 2,000 to 150,000, more preferably from 5,000 to 100,000, and still more preferably from 8,000 to 70,000. If the weight average molecular weight is 2,000 or more, the cohesive force increases and a high adhesive force improving effect can be obtained. If the weight average molecular weight is 150,000 or less, the compatibility with the acrylic polymer (A) increases and a sufficient adhesive force improving effect on a low-polarity adherend can be obtained.

[0065] The polyolefin (C) is contained in an amount of 0.01 part by mass or more and less than 10 parts by mass with respect to 100 parts by mass of the copolymer (A). When the content of the polyolefin (C) is 0.01 part by mass or more, a sufficient adhesive force improving effect can be obtained with respect to a low-polarity adherend such as polyolefin. If it is less than 10 parts by mass, a decrease in heat resistance and initial crosslinkability due to excessive addition can be suppressed. 0.1 to 5 parts by mass is preferable, and 0.5 to 2 parts by mass is more preferable.

[0066] In addition to the copolymer (A), the curing agent (B) and the polyolefin (C), the pressure-sensitive adhesive composition of the present invention may optionally contain a solvent, a resin other than the copolymer (A), a tackifier resin, a plasticizer, a silane coupling agent, a leveling agent, inorganic and / or organic fine particles, an ultraviolet absorber, a light stabilizer, an antioxidant and other optional additives. The addition amounts of these additives can be appropriately selected within the range in which the effects of the present invention can be obtained.

[0067] Examples of the resin other than the (meth)acrylic ester copolymer (A) include known thermoplastic resins, such as thermoplastic elastomers such as ester-based elastomers, styrene-based elastomers, and polyurethane-based elastomers, as well as thermoplastic polyesters, and polyamide-based resins such as polyamide-based copolymers, polyurethanes, polystyrene-based resins, cellophane, polyacrylonitrile, and polyvinyl chloride-based resins such as vinyl chloride-vinyl acetate copolymers. These resins may be used alone or in combination of two or more. The content of these other resins is preferably less than 10% by mass in 100% by mass of the solid content of the pressure-sensitive adhesive composition of the present invention. If the content of these resins is less than 10% by mass, good compatibility can be easily obtained, and appropriate adhesive force can be easily obtained.

[0068] When applying the pressure-sensitive adhesive composition of the present invention to an adherend, the solvent during the polymerization of the (meth)acrylic ester copolymer (A) may be used as it is, or a solvent may be further added, and any solvent can be appropriately used.

[0069] Examples of the solvent include methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, xylene, hexane, cyclohexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, n-propanol, isopropanol, isophorone, and the like. These organic solvents may be used alone or in combination of two or more. By adding these organic solvents, the viscosity of the pressure-sensitive adhesive composition can be adjusted, or the pressure-sensitive adhesive composition can be heated to lower the viscosity. From the viewpoints of solubility and drying property, it is preferable to use a solvent having an SP value of 9 or more. Examples of the organic solvent 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 lowering the viscosity of the pressure-sensitive adhesive composition, it is preferable to use a solvent having an SP value of less than 9. Examples of the organic solvent having an SP value of less than 9 include hexane, cyclohexane, heptane, octane, and the like.

[0070] <Decorative sheet> The pressure-sensitive adhesive composition of the present invention can be preferably used for a decorative sheet. The decorative sheet according to the present invention (hereinafter also referred to as the present decorative sheet) includes a base material and a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive composition of the present invention. If necessary, the exposed surface of the pressure-sensitive adhesive layer can be covered with a release sheet. Note that the release sheet is peeled off when the pressure-sensitive adhesive sheet is attached to an adherend. The base material is not particularly limited, and examples thereof include resin sheets, paper, and metal foils. The base material may be a laminated sheet in which one or more arbitrary layers are laminated on at least one surface of these base materials. On the surface of the base material on the side where any pressure-sensitive adhesive layer is to be formed, an adhesion-promoting treatment such as corona discharge treatment and anchor coat agent application may be performed as necessary. The release sheet is not particularly limited, and a known release sheet obtained by subjecting a base material sheet such as a resin sheet or paper to a known release treatment such as applying a release agent can be used.

[0071] Regarding the method for manufacturing the present decorative sheet having a pressure-sensitive adhesive layer, a conventionally known method can be appropriately used and is not particularly limited. For example, on a sheet on which a surface layer and a decorative layer are formed, if necessary The present composition diluted with a solvent is coated by knife coating, bar coating, blade coating, doctor coating, roll coating, cast coating, etc. to form a coating film. Next, if necessary, by heating and drying or curing, a pressure-sensitive adhesive layer (solidified product) can be formed on the sheet. When the copolymer (A) contained in the present composition requires crosslinking by active energy rays, after applying the present composition on the sheet, by irradiating with active energy rays, a pressure-sensitive adhesive layer (crosslinked product) can be formed on the sheet. At that time, for example, using a belt conveyor type ultraviolet irradiation device, ultraviolet irradiation can be performed on the pressure-sensitive adhesive composition applied on the sheet to obtain a pressure-sensitive adhesive layer. The ultraviolet irradiation amount can be, for example, 500 mJ / cm 2 or more and 5000 mJ / cm 2 or less. This decorative sheet has appropriate adhesiveness at normal temperature (e.g., 25 °C), excellent adhesiveness during adhesion at high temperature (e.g., 100 - 130 °C), and can maintain its properties at high temperature for a long period (e.g., 7 days at 100 °C). Therefore, this decorative sheet can be applied to the decoration of, for example, aircraft, automobiles, interior and exterior finishes of building materials, the fields of care and medicine, electrical appliances, electronic components, smartphones, furniture, musical instruments, and the walls of bullet train window frames by three-dimensional surface decoration (Three dimension Overlay Method: TOM molding), which is a type of vacuum pressure air molding. In particular, it can be preferably used for pasting on automobile interior and exterior parts, parts for household appliances, and parts for building materials.

[0072] <Decorative structure and its manufacturing method> The decorative structure according to the present invention (hereinafter also referred to as the present structure) can be formed by pasting a decorative sheet on an adherend using the adhesive composition of the present invention. The shape of the adherend is not particularly limited, and various shaped objects to be pasted (e.g., three-dimensional shaped molded products) can be used. The material of the adherend is not particularly limited, but a low-polarity adherend such as a polypropylene resin is preferred. The decorative sheet using the adhesive composition of the present invention is used for pasting on an adherend by a vacuum molding method and a vacuum pressure air molding method. Conventional well-known methods can be appropriately applied to the vacuum molding method and the vacuum pressure air molding method.

[0073] More specifically, this decorative structure can include, for example, a surface layer, a decorative layer, and an adhesive layer in this order. The surface layer is the layer that becomes the surface of the decorated molded product, and those conventionally known in the field of decorative sheets can be appropriately used. The surface layer can be composed of various resins such as, for example, acrylic resin, polyurethane, fluororesin, and polyvinyl chloride. Also, embossing may be applied to the exposed surface of the surface layer. The decorative layer is for decorating the object to be decorated, and various materials can be used according to the intended use. The decorative layer can include, for example, at least one resin selected from the group consisting of olefin resins, styrene resins, and vinyl chloride resins. Further, 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, arrangement, thickness, etc. of each layer can be appropriately selected and are not particularly limited. The adhesive layer is a layer for attaching the decorative sheet to the adherend (for example, a molded article formed into a three-dimensional shape), and can be formed by drying an adhesive composition (for example, after applying it on a substrate) or crosslinking it by irradiating ultraviolet rays or the like.

Examples

[0074] Next, examples will be shown for further detailed explanation, but the present invention is not limited by these examples. In the examples, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass". Also, the compounding amounts in the tables are in parts by mass.

[0075] <Measurement of weight average molecular weight (Mw)> (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 separation and quantification by the difference in its molecular size to specify Mw. As the measuring apparatus, the LC-GPC system "Prominence" (trade name) of GPC manufactured by Shimadzu Corporation was used. The determination of the weight average molecular weight was carried out in terms of polystyrene conversion. Four columns of "GMHXL" (trade name) manufactured by Tosoh Corporation and one column of "HXL-H" (trade name) manufactured by Tosoh Corporation were connected in series, the flow rate was set to 1.0 ml / min, and the measurement was carried out at a column temperature of 40°C.

[0076] [Production Example of (Meth)acrylate Copolymer (A)] <Synthesis Example 1> A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, and a nitrogen inlet tube (hereinafter sometimes simply referred to as "reaction vessel") was charged with 42.5 parts of 2-ethylhexyl acrylate, 3.5 parts of butyl acrylate, 1.5 parts of methyl acrylate, 2.0 parts of vinyl acetate, 1.5 parts of acrylic acid, 60 parts of acetone, and 0.01 part of 2,2'-azobisisobutyronitrile (AIBN). After that, the air in the reaction vessel was replaced with nitrogen gas. Further, the dropping funnel was charged with 42.5 parts of 2-ethylhexyl acrylate, 3.5 parts of butyl acrylate, 1.5 parts of methyl acrylate, 1.5 parts of acrylic acid, 20 parts of ethyl acetate, and 0.01 part of 2,2'-azobisisobutyronitrile (AIBN). Then, while stirring the inside of the reaction vessel under a nitrogen atmosphere, it was heated to 80 °C, and after starting the reaction, the content of the dropping funnel was dropped over 1.5 hours, and a polymerization reaction was carried out at the reflux temperature for 5 hours under a nitrogen atmosphere. After completion of the reaction, it was cooled, ethyl acetate was added for dilution, and a (meth)acrylate copolymer solution having a non-volatile content of 40% was obtained. The weight average molecular weight (Mw) of the (meth)acrylate copolymer was 9.8 million.

[0077] (Synthesis Examples 2 to 12) A (meth)acrylate copolymer solution was obtained in the same manner as in Synthesis Example 1 except that the composition described in Table 1 was changed.

[0078]

Table 1

[0079] The abbreviations in Table 1 are described below. 2EHA: 2-ethylhexyl acrylate 2OA: 2-octyl acrylate BA: butyl acrylate MMA: methyl methacrylate MA: methyl acrylate VAc: vinyl acetate AA: acrylic acid

[0080] (Example 1) To 100 parts of the copolymer (Synthesis Example 1) obtained in the above synthesis example, 0.05 part (in terms of non-volatile content) of TETRAD-X (manufactured by Mitsubishi Gas Chemical Company, Inc.) as the curing agent (B) was blended. Further, 1 part (in terms of non-volatile content) of Auroren 200S as the polyolefin (C) was blended, and ethyl acetate was added to adjust the non-volatile content to 25%, thereby obtaining the pressure-sensitive adhesive composition of Example 1. The obtained pressure-sensitive adhesive composition was evaluated according to the measurement methods and evaluation methods shown below.

[0081] (Examples 2 to 25, Comparative Examples 1 to 3) A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that the copolymer (A), the curing agent (B), and the polyolefin (C) were changed to those described in Table 2. The obtained pressure-sensitive adhesive composition was evaluated according to the measurement methods and evaluation methods shown below.

[0082] >[Method for producing a decorative sheet] The obtained pressure-sensitive adhesive composition was applied onto the release-treated surface of a polyethylene terephthalate (PET) film (thickness: 38 μm) having a release treatment on one side so that the thickness after drying would be 25 μm. Subsequently, after drying at 105°C for 2 minutes, the coating film was laminated onto a commercially available vinyl chloride film and cured in an atmosphere of 23°C and 50% relative humidity (hereinafter 50% RH) for 7 days to prepare a decorative sheet.

[0083] (Adhesion to SUS) After curing in an atmosphere of 23°C - 50% RH for 5 hours, a test piece having a width of 25 mm and a length of 150 mm was cut out from the decorative sheet. The PET film was peeled off from the cut-out decorative sheet, and the exposed pressure-sensitive adhesive layer was attached to the surface of a stainless steel plate (SUS304) and crimped with a 2 kg roll for one round trip. Then, it was left in an atmosphere of 23°C - 50% RH for 24 hours. Next, in accordance with JIS Z0237, using a tensile tester (Tensilon: manufactured by Orientec Co., Ltd.), the adhesive strength (adhesive strength before heating) was measured under the conditions of a peeling rate of 300 mm / min and a peeling angle of 180°. The evaluation criteria are as follows. [Evaluation criteria] ◎: 13 N / 25 mm or more, excellent. ○: 8 N / 25 mm or more and less than 13 N / 25 mm, good. △: 1N / 25mm or more but less than 8N / 25mm, usable. ×: Less than 1N / 25mm, not practical.

[0084] (PP adhesive strength) After curing for 5 hours under an atmosphere of 23°C-50% RH, a test piece with a width of 25 mm and a length of 150 mm was cut out from the decorative sheet. The PET film was peeled off from the cut decorative sheet, and the exposed adhesive layer was attached to the surface of a polypropylene plate and pressed with a 2 kg roll once. The sheet was then left for 24 hours under an atmosphere of 23°C-50% RH. Next, the adhesive strength (adhesive strength before heating) was measured using a tensile tester (Tensilon: manufactured by Orientec Co., Ltd.) in accordance with JIS Z0237 at a peel speed of 300 mm / min and a peel angle of 180°. The evaluation criteria are as follows. [Evaluation Criteria] ◎: 10N / 25mm or more, excellent. ◎○8N / 25mm or more and less than 10N / 25mm, very good. ○: 7N / 25mm or more but less than 8N / 25mm, good. △: 3N / 25mm or more but less than 7N / 25mm, usable. ×: Less than 3N / 25mm, not practical.

[0085] <Conformity to uneven surfaces> The decorative sheet obtained above was attached to the frame of a TOM molding machine (NGF molding machine, manufactured by Fuse Vacuum Co., Ltd.), and then a melamine plate with a width of 7 cm and a length of 15 cm was set inside the frame, and a square pyramid-shaped PP resin with a top side of 20 mm, a bottom side of 40 mm, and a height of 15 mm was set on top of the melamine plate. The melamine plate and the PP resin were then molded to cover the decorative sheet, and a decorative structure was obtained. The surface condition after molding was evaluated based on the following evaluation criteria. (Evaluation Criteria) : No lifting or peeling was observed on any surface. Very good. ○: No lifting is observed on the uneven surface, but some peeling occurs at the edge. Good. △: Some lifting was observed on uneven surfaces, and peeling occurred at the edges. Practical use is possible. ×: Lifting occurs on all uneven surfaces, and peeling occurs across the entire surface. Not practical for use.

[0086] <Durability after molding> After leaving the decorative structure obtained from the unevenness followability test in an atmosphere of 23°C - 50%RH for 24 hours, a 5 cm long cut was made crosswise on the surface of the molded article, and after leaving it in a high-temperature or high-temperature and high-humidity environment (60°C / 100°C / 80°C - 95%RH) for 168 hours respectively, lifting, peeling, and displacement were evaluated based on the following evaluation criteria. (Evaluation criteria) ◎: No lifting or peeling, and no displacement, or no lifting or peeling but displacement less than 0.5 mm occurs. Excellent. ◎○: No lifting or peeling, but displacement of 0.5 mm or more and less than 1 mm occurs. Very good ○: No lifting or peeling, but displacement of 1 mm or more and less than 3 mm occurs. Good. △: No lifting or peeling, but displacement of 3 mm or more and less than 10 mm occurs. Practical for use. ×: Lifting or peeling occurs. Or no lifting or peeling, but displacement of 10 mm or more occurs. Not practical for use.

[0087] <Yellowing of coating film> The obtained adhesive composition for decorative sheet was applied onto the release-treated surface of a polyethylene terephthalate (PET) film (thickness 38 μm) with release treatment on one side so that the dried thickness would be 25 μm. Subsequently, after drying at 105°C for 2 minutes, the coating film was laminated onto a glass plate. Next, the release liner of the adhesive sheet was peeled off and laminated onto the glass plate using a laminator. A test piece laminated in the order of glass plate / adhesive layer / glass plate was prepared by applying a pressure of 0.5 MPa in an atmosphere of 50°C and holding for 20 minutes, and it was left in an environment of 120°C for 1000 hours as a heat resistance test. After cooling it in an environment of 23°C - 50%RH (relative humidity) for 1 hour, the b* value was measured, and the difference Δb* from the b* value before the heat resistance test was calculated. The b* value was measured using a spectrocolorimeter SE6000 (trade name) manufactured by Nippon Denshoku Industries Co., Ltd. under the conditions of D65 light source and a viewing angle of 2°. The yellowing of the coating film (yellowing resistance) was evaluated based on the following evaluation criteria. (Evaluation criteria) ◎: Δb* is less than 0.8. Excellent. ○: Δb* is 0.8 or more and less than 1.5. Good. △: Δb* is 1.5 or more and less than 3.0. Practically acceptable. ×: Δb* is 3.0 or more. Practically unacceptable.

Table 2

[0088] The materials described in Table 2 are described below. <Hardener (B)> TETRAD-X: Epoxy crosslinking agent (N,N,N’,N’-tetraglycidyl-m-xylenediamine), manufactured by Mitsubishi Gas Chemical Company, Inc. TDI-TMP: Trimethylolpropane adduct of tolylene diisocyanate Aluminum chelate A: Aluminum tris(acetylacetonate), manufactured by Kawaken Fine Chemicals Co., Ltd. <Polyolefin (C)> Auroren 200S: Manufactured by Nippon Paper Industries Co., Ltd., (Chlorination rate: 0%) Super Kron 814HS: Manufactured by Nippon Paper Industries Co., Ltd., (Chlorination rate: 41%, Weight average molecular weight 15,000, Tg: about 62°C) Super Kron 360T: Manufactured by Nippon Paper Industries Co., Ltd., (Chlorination rate: 31%, Weight average molecular weight 9,000, Tg: about 35°C) Super Kron 390S: Manufactured by Nippon Paper Industries Co., Ltd., (Chlorination rate: 36%, Weight average molecular weight 26,000, Tg: about 55°C) Super Kron 2032S: Manufactured by Nippon Paper Industries Co., Ltd., (Chlorination rate: 32%, Weight average molecular weight 112,000, Tg: about 37°C) Hardlen M-28P: Manufactured by Toyobo Co., Ltd., (Chlorination rate 20%)

[0089]

Table 3

[0090] The present invention is not limited to the above-described embodiments and examples, and design changes can be appropriately made without departing from the spirit of the present invention.

[0091] As shown in Table 3, Examples 1 to 25 were excellent in adhesive strength, unevenness followability, durability after molding, and coating film appearance. On the other hand, Comparative Examples 1 to 3 in Table 3 could not satisfy all of the above-described physical properties. The present composition having excellent properties as described above can be suitably used, for example, for decoration in the fields of aircraft, automobiles, railways, interior and exterior building materials, care and medical fields, and electrical appliances, and its use applications are not particularly limited, but use for automobile interior and exterior parts, household electrical appliances, smartphones, and housing building materials is preferred, use for automobile interior and exterior parts and housing building materials is more preferred, and use for automobile interior and exterior parts is particularly preferred. Further, as methods of decorating using a decorative sheet, an insert molding method, an in-mold molding method, a vacuum molding method, a vacuum pressure molding method, etc. are known, and although not particularly limited, the methods of vacuum molding method and vacuum pressure molding method are particularly preferred.

Claims

1. An adhesive composition for a decorative sheet, comprising a (meth)acrylic acid ester copolymer (A), a curing agent (B), and a polyolefin (C), and containing 0.01 parts by mass or more and less than 10 parts by mass of the polyolefin (C) with respect to 100 parts by mass of the (meth)acrylic acid ester copolymer (A).

2. The (meth)acrylic acid ester copolymer (A) is a copolymer of a monomer mixture containing any two or more selected from the group consisting of the following (a1), (a2), and (a3). The adhesive composition for a decorative sheet according to Claim 1, wherein the total content ratio of (a1), (a2), and (a3) is 75% by mass or more in 100% by mass of the monomer mixture. (a1): A (meth)acrylic acid alkyl ester monomer in which the glass transition temperature of the homopolymer is 0°C or lower and the number of carbon atoms of the alkyl group is 4 to 8. (a2): A (meth)acrylic acid alkyl ester monomer in which the number of carbon atoms of the alkyl group is 1 to 3. (a3): A vinyl ester monomer of a carboxylic acid having an alkyl group with 1 to 3 carbon atoms.

3. The adhesive composition according to Claim 1, wherein the polyolefin (C) includes a chlorinated polyolefin (C1).

4. The adhesive composition according to Claim 3, wherein the chlorination degree of the chlorinated polyolefin (C1) is 20% by mass or more and less than 45% by mass.

5. The adhesive composition for a decorative sheet according to Claim 1, which is used for attachment to an adherend by a vacuum forming method or a vacuum pressure air forming method.

6. A decorative sheet, comprising a base material and an adhesive layer composed of the adhesive composition for a decorative sheet according to any one of Claims 1 to 5.

7. A decorative structure, comprising an adherend and the decorative sheet according to Claim 6, wherein the adherend is any one of automotive interior and exterior parts, parts for home appliances, and parts for building materials.

8. A method for manufacturing a decorative structure, characterized in that the decorative structure according to Claim 7, in which the adherend and the decorative sheet are integrated by a vacuum forming method or a vacuum pressure air forming method, is formed.

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