Peelable film

Abstract

To provide a releasable film having a surface layer on a substrate layer in which a component of the releasable film hardly migrates into an object and the release power before and after heating is small.SOLUTION: There is provided a releasable film having a surface layer on a substrate layer, in which the main component forming the surface layer is a resin component, the resin component comprises a modified acrylic resin (A) having an alkyl component and a crosslinkable functional group, a resin (B) different from the modified acrylic resin (A) and a cross-linking agent (D), the modified acrylic resin (A) contains at least a structural unit represented by the following general formula (I): (R1 represents a methyl group or a hydrogen atom; and R2 represents an alkyl group having 10 to 18 carbon atoms) and the cross-linking agent (D) is a melamine compound having a structure in which all hydrogen atoms of an amino group are substituted with at least one of an alkoxy alkyl group and an alkanol group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a peelable film and a method for producing the same. [Background technology]

[0002] BACKGROUND ART Peelable films are used in industrial fields such as manufacturing processes for electronic components and electronic substrates, and manufacturing processes for thermosetting resin members such as fiber-reinforced plastics, as well as in the medical field such as for compresses and adhesive plasters.

[0003] Various types of release films are known, including those used as surface protection films or adhesive tapes, release liners or separator films, separators used in the manufacturing processes of semiconductor products (dicing, die bonding, back grinding, etc.), carriers for forming unfired sheets in the manufacture of ceramic capacitors, carriers in the manufacture of composite materials, and protective separator films.

[0004] For example, silicone-based release films have excellent weather resistance, heat resistance, cold resistance, chemical resistance, and electrical insulation, and are widely used as release films. However, when using silicone-based release films, silicone may transfer (migrate) to the article to which the film is attached (this problem is also called the silicone migration problem). Therefore, efforts have been made to improve the silicone composition in silicone-based release films, minimize the amount of silicone used, or even to eliminate silicone altogether. For example, Patent Document 1 proposes a release film using a hydroxyl group-containing long-chain alkyl polymer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-030795 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the release film described in Patent Document 1 has insufficient heat resistance due to a large difference in peel strength before and after heating. As an example, we will explain the use of a release film as a carrier for forming an unsintered sheet during the production of ceramic capacitors. To produce the unsintered sheet, a coating layer is formed on the release film and then dried. If the heat resistance is insufficient due to a large difference in peel strength before and after heating, the unsintered sheet will be difficult to peel off unexpectedly from the release film after drying due to the heat of the drying process. Depending on the release film, the unsintered sheet may not only be difficult to peel off unexpectedly from the release film, but may also peel off unexpectedly from the release film. Due to these problems, this release film is difficult to use as a replacement for silicone-based release films.

[0007] Furthermore, similar to the problem of silicone migration caused by silicone-based release films, there is a problem in that if the components of the release film migrate to the surface of an article and remain on the surface of the article after the release film is peeled off from the article, the surface of the article will be contaminated. The remaining components on the surface of the article not only contaminate the surface of the article, but also lead to contamination of the surfaces of other articles that come into contact with the article thereafter. Therefore, release films used in the manufacturing processes of precision equipment such as electronic components and electronic substrates are particularly required to have the ability to prevent the components of the release film from migrating to the article.

[0008] Under these circumstances, a main object of the present invention is to provide a release film in which components of the release film are unlikely to migrate to an article and in which the difference in release force before and after heating is small. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result, have discovered a peelable film having a surface layer on a substrate layer, wherein the main component forming the surface layer is a resin component, and the resin component includes a modified acrylic resin (A) having an alkyl component and a crosslinkable functional group, a resin (B) different from the modified acrylic resin (A), and a crosslinking agent (D), wherein the modified acrylic resin (A) is at least a compound represented by the following general formula (I): [ka] (In the general formula (I), R 1 represents a methyl group or a hydrogen atom, and R 2 represents an alkyl group having 10 to 18 carbon atoms. and the crosslinking agent (D) is a melamine compound having a structure in which all of the hydrogen atoms of the amino groups are substituted with at least one of an alkoxyalkyl group and an alkanol group, the components of the release film are less likely to migrate to the article, and the difference in release force before and after heating is small. The present invention was completed through further investigation based on this finding.

[0010] That is, the present invention includes the following. [1] A peelable film having a surface layer on a substrate layer, the main component forming the surface layer is a resin component, the resin component includes a modified acrylic resin (A) having an alkyl component and a crosslinkable functional group, a resin (B) different from the modified acrylic resin (A), and a crosslinking agent (D); The modified acrylic resin (A) is at least a compound represented by the following general formula (I): [ka] (In the general formula (I), R 1 represents a methyl group or a hydrogen atom, and R 2 represents an alkyl group having 10 to 18 carbon atoms. It contains a constitutional unit represented by The peelable film, wherein the crosslinking agent (D) is a melamine compound having a structure in which all hydrogen atoms of amino groups are substituted with at least one of an alkoxyalkyl group and an alkanol group. [2] The modified acrylic resin (A) is represented by the following general formula (II): [ka] [In the general formula (II), R a represents a methyl group or a hydrogen atom, and R b represents -CH2CH2OH, -CH2-CHOH-CH3, -CH2CH2CH2OH, -CH2-CHOH-CH2CH3, -CH2CH2-CHOH-CH3, or -CH2CH2CH2CH2OH.] Item 2. The peelable film according to item 1, comprising a structural unit represented by the formula: [3] The weight average molecular weight of the modified acrylic resin (A) is 5 × 10 4 ~15×10 4 Item 3. The peelable film according to item 1 or 2, [4] The peelable film according to any one of items 1 to 3, wherein the content of the resin (B) in the surface layer is 2 parts by mass or more, relative to 100 parts by mass of the total of the modified acrylic resin (A) and the resin (B) constituting the surface layer. [5] The peelable film according to any one of items 1 to 4, wherein the content of the resin (B) in the surface layer is less than 50 parts by mass, relative to 100 parts by mass of the total of the modified acrylic resin (A) and the resin (B) constituting the surface layer. [6] The peelable film according to any one of items 1 to 5, wherein the alkoxyalkyl group has 2 to 5 carbon atoms and the alkanol group has 1 to 3 carbon atoms. [7] The peelable film according to any one of items 1 to 6, wherein the resin (B) different from the modified acrylic resin (A) is at least one selected from the group consisting of polyester resins and acrylic resins. [8] A method for producing a peelable film having a surface layer on a substrate layer, comprising: forming the surface layer on the base layer, the main component forming the surface layer is a resin component, the resin component includes a modified acrylic resin (A) having an alkyl component and a crosslinkable functional group, a resin (B) different from the modified acrylic resin (A), and a crosslinking agent (D); The modified acrylic resin (A) is at least a compound represented by the following general formula (I): [ka] (In the general formula (I), R 1 represents a methyl group or a hydrogen atom, and R 2 represents an alkyl group having 10 to 18 carbon atoms. It contains a constitutional unit represented by The method for producing a release film, wherein the crosslinking agent (D) is a melamine compound having a structure in which all hydrogen atoms of amino groups are substituted with at least one of an alkoxyalkyl group and an alkanol group. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a peelable film having a surface layer on a substrate layer, in which components of the peelable film are less likely to migrate to an article and the difference in peel strength before and after heating is small. DETAILED DESCRIPTION OF THE INVENTION

[0012] The release film according to this embodiment is a release film having a surface layer on a base layer, and the main component forming the surface layer is a resin component, and the resin component includes a modified acrylic resin (A) having an alkyl component and a crosslinkable functional group, a resin (B) different from the modified acrylic resin (A), and a crosslinking agent (D), and the modified acrylic resin (A) is at least a compound represented by the following general formula (I): [ka] (In the general formula (I), R 1 represents a methyl group or a hydrogen atom, and R 2represents an alkyl group having 10 to 18 carbon atoms.) and the crosslinking agent (D) is a melamine compound having a structure in which all of the hydrogen atoms of the amino groups are substituted with at least one of an alkoxyalkyl group and an alkanol group.

[0013] The release film according to the present embodiment, having such a configuration, exhibits the following characteristics: components of the release film are less likely to migrate to an article, and the difference in release strength between before and after heating is small. More specifically, (1) when an object (adherend) is attached to the surface layer of the release film and then peeled away from the surface layer, components contained in the surface layer of the release film are less likely to migrate to the surface of the object; and (2) the release film also exhibits the following characteristics: the difference in release strength between before and after heating to high temperatures, such as 90 to 160°C. Because of these properties, the release film according to the present embodiment can be particularly suitable for use in the manufacturing processes for electronic components and electronic substrates, the manufacturing processes for thermosetting resin components such as fiber-reinforced plastics, and in the medical field, such as for compresses and adhesive bandages. In addition to the above properties, the release film according to the present embodiment can be even more suitable for use in the aforementioned fields when it has a low release strength at room temperature (the release strength before heating to the aforementioned high temperature) and / or an excellent residual adhesion rate.

[0014] The release film according to this embodiment will be described in detail below. In this specification, the "to" in a numerical range means "greater than or equal to" or "less than or equal to." That is, the notation "α to β" means "greater than or equal to α and less than or equal to β," or "greater than or equal to β and less than or equal to α," and includes both α and β as a range. Furthermore, "(meth)acrylic" means "acrylic or methacrylic," and similar terms have similar meanings.

[0015] The peelable film according to this embodiment is a laminated film having a base layer and a surface layer on at least one side of the base layer.

[0016] [Base material layer] The substrate layer may be a layer containing a resin (e.g., a resin film), or a thin sheet of paper, nonwoven fabric, metal foil, etc. When the substrate layer is a layer containing a resin, for example, the resin may be a layer containing a polyester-based resin such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene terephthalate, polypropylene naphthalate, polytrimethylene terephthalate, or polybutylene terephthalate; a polyolefin-based resin such as polyethylene or polypropylene; a polystyrene-based resin; an acetylcellulose-based resin such as triacetyl cellulose; an acrylic resin such as polymethyl methacrylate; a polyurethane resin; a polycarbonate resin; a polyamide-based resin; or a polyvinyl chloride-based resin.

[0017] When the base layer is a layer containing a resin, it may contain only one type of the above resin, or may contain two or more types in combination. From the viewpoint of processability of the surface layer, the base layer in the release film of this embodiment is preferably a layer containing at least one selected from the group consisting of polyester resins, polyolefin resins, and polystyrene resins as a main component, and from the viewpoint of adhesion to the surface layer (and adhesion to another layer if another layer is interposed between the surface layer and the base layer), it is more preferably a layer containing at least one selected from the group consisting of polyester resins and polyolefin resins as a main component.

[0018] In the present invention and this specification, the term "main component" means a component that is contained in an amount of 50% by mass or more, and the proportion of the main component is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The proportion of the main component may be 100% by mass.

[0019] The base layer may contain additives, similar to the surface layer described later. The types and components of the additives are the same as those described in the surface layer section below, and therefore will not be described here.

[0020] The substrate layer may be a layer formed of any of an unstretched film, a uniaxially stretched film, and a biaxially stretched film. From the viewpoints of processability, transparency, and dimensional stability, the substrate layer is preferably a layer formed of a biaxially stretched film.

[0021] The thickness of the substrate layer is preferably 15 μm or more, more preferably 20 μm or more, from the viewpoint of processability. The thickness of the substrate layer is preferably 125 μm or less, more preferably 50 μm or less, from the viewpoint of handleability during product use. The thickness of the substrate layer is measured using a micrometer (JIS B-7502) in accordance with JIS C-2151, specifically by the method described in the examples.

[0022] To enhance the adhesion between the substrate layer and the surface layer described below, one or both surfaces of the substrate layer may be subjected to a surface treatment, as desired. Examples of the surface treatment include roughening treatments such as sandblasting or solvent treatment, corona discharge treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, and surface oxidation treatments such as ozone or ultraviolet irradiation treatment.

[0023] [Surface layer] The release film of this embodiment has a surface layer on a base layer. The surface layer is a layer for imparting release properties to the release film. The surface layer may be formed on the base layer with various layers, such as an adhesive layer, interposed between the surface layer and the base layer, but it is preferable that the surface layer is formed so that the main surface of the surface layer is in contact with the main surface of the base layer.

[0024] The main component forming the surface layer is a resin component. The resin component includes a modified acrylic resin (A) having an alkyl component and a crosslinkable functional group, a resin (B) different from the modified acrylic resin (A), and a crosslinking agent (D). That is, the surface layer is composed of a cured product of a resin composition including the modified acrylic resin (A) having an alkyl component and a crosslinkable functional group, the resin (B) different from the modified acrylic resin (A), and the crosslinking agent (D). The modified acrylic resin (A), the resin (B) different from the modified acrylic resin (A), and the crosslinking agent (D) are described in detail below.

[0025] <Modified acrylic resin (A)> The modified acrylic resin (A) having an alkyl component and a crosslinkable functional group is a resin having an alkyl group as a side chain on an acrylic resin main chain. The modified acrylic resin (A) contains at least a structural unit represented by the following general formula (I) (formed from a monomer a described below): [ka]

[0026] In general formula (I), R 1 represents a methyl group or a hydrogen atom, and R 2 represents an alkyl group having 10 to 18 carbon atoms.

[0027] In the general formula (I), the alkyl group R 2 The number of carbon atoms is 10 to 18. If the number of carbon atoms is less than 9, it is generally difficult to make the modified acrylic resin (A) exhibit releasability. On the other hand, if the number of carbon atoms exceeds 18, the crystallinity becomes high, and the peeling force becomes too high, resulting in poor release performance as a release film. When the modified acrylic resin (A) has a long-chain alkyl group having 10 to 18 carbon atoms, the release performance becomes excellent. In order to improve the release performance, 2 is preferably a linear alkyl group. 2 The number of carbon atoms in R is preferably 12 to 18, and more preferably 12 to 14. 2has 12 to 1 carbon atoms Straight chain alkyl groups having 8 carbon atoms are even more preferred, and straight chain alkyl groups having 12 to 14 carbon atoms are particularly preferred.

[0028] In the modified acrylic resin (A), examples of the crosslinkable functional group (reactive functional group) include a carboxyl group, an isocyano group, an epoxy group, an N-methylol group, an N-alkoxymethyl group, a hydroxy group, an amino group, a thiol group, and a hydrolyzable silyl group. The number of crosslinkable functional groups may be one or two or more. Furthermore, one type of crosslinkable functional group may be contained alone, or two or more types may be contained.

[0029] The modified acrylic resin (A) is a polymer obtained by polymerizing at least a monomer a (an acrylic monomer having a carbon-carbon unsaturated double bond and an alkyl group having 10 to 18 carbon atoms in one molecule) that forms the structural unit represented by the general formula (I). The modified acrylic resin (A) may be a copolymer obtained by copolymerizing the monomer a with at least one monomer selected from the group consisting of the below-described monomer b (a monomer having a carbon-carbon unsaturated double bond and a crosslinkable functional group in one molecule), monomer c (an acrylic monomer having a carbon-carbon unsaturated double bond and an alkyl group having 1 to 9 or 19 or more carbon atoms in one molecule), and monomer d (a monomer different from the monomers a, b, and c that is copolymerizable with at least one of the monomers a, b, and c). In particular, a copolymer obtained by copolymerizing at least the monomer a and the monomer b is preferred as the modified acrylic resin (A).

[0030] [Monomer a] Examples of the monomer a include (meth)acrylic acid esters in which the ester moiety is a long-chain alkyl group having 10 to 18 carbon atoms. Specific examples include isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (also called lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate (also called myristyl (meth)acrylate), pentadecyl (meth)acrylate, hexadecyl (meth)acrylate (also called palmityl (meth)acrylate), and stearyl (meth)acrylate.

[0031] From the viewpoints of reducing the difference in peel strength before and after heating and further making it difficult for the components of the surface layer to migrate to the article, the content of the structural units derived from the monomer a in the modified acrylic resin (A) is preferably about 50 to 99.99 parts by mass, more preferably about 70 to 99.9 parts by mass, even more preferably about 85 to 99.8 parts by mass, and still more preferably about 85 to 99.5 parts by mass, per 100 parts by mass of the total structural units contained in the modified acrylic resin (A). Only one type of monomer a may be used, or two or more types may be mixed and used.

[0032] [Monomer b] Monomer b is a monomer having a carbon-carbon unsaturated double bond and a crosslinkable functional group in one molecule. Because monomer b has a crosslinkable functional group, it can be suitably bonded to a resin (B) different from the modified acrylic resin (A) via a crosslinking agent (D) described below, thereby reducing the difference in peel strength between before and after heating of the release film and further suppressing the migration of surface layer components to the article.

[0033] Examples of crosslinkable functional groups (reactive functional groups) include carboxyl groups, isocyano groups, epoxy groups, N-methylol groups, N-alkoxymethyl groups, hydroxy groups, amino groups, thiol groups, and hydrolyzable silyl groups. Monomer b may be used alone or in combination of two or more types. Furthermore, the number of crosslinkable functional groups in monomer b may be one or two or more. Furthermore, one type of crosslinkable functional group may be contained alone, or two or more types may be contained.

[0034] Examples of the monomer b having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and styrenesulfonic acid. Examples of the monomer b having a carboxyl group include N-(meth)acryloyl-p-aminobenzoic acid and N-(meth)acryloyl-5-aminosalicylic acid. Examples of the monomer b having a carboxyl group include carboxyl group-containing (meth)acrylates. Examples of the carboxyl group-containing (meth)acrylates include 1,4-di(meth)acryloxyethylpyromellitic acid, 4-(meth)acryloxyethyltrimellitic acid, and 2-(meth)acryloyloxybenzoic acid.

[0035] Examples of the monomer b having an isocyano group include (meth)acryloyloxyethyl isocyanate and (meth)acryloyloxypropyl isocyanate, and also include those obtained by reacting a hydroxy(meth)acrylate (e.g., 2-hydroxyethyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, etc.) with a polyisocyanate (e.g., toluene diisocyanate, isophorone diisocyanate, etc.).

[0036] Examples of the monomer b having an epoxy group include glycidyl methacrylate, glycidyl cinnamate, glycidyl allyl ether, glycidyl vinyl ether, vinylcyclohexane monoepoxide, and 1,3-butadiene monoepoxide.

[0037] Examples of the monomer b having an N-methylol group or an N-alkoxymethyl group include (meth)acrylamides having an N-monoalkoxymethyl group, such as N-methylol(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-ethoxymethyl(meth)acrylamide, N-propoxymethyl(meth)acrylamide, and N-butoxymethyl(meth)acrylamide, and (meth)acrylamides having an N,N-dialkoxymethyl group, such as N,N-dimethylol(meth)acrylamide, N,N-di(methoxymethyl)(meth)acrylamide, N,N-di(ethoxymethyl)(meth)acrylamide, N,N-di(propoxymethyl)(meth)acrylamide, and N,N-di(butoxymethyl)(meth)acrylamide.

[0038] The monomer b having a hydroxy group mainly includes a hydroxy group-containing (meth)acrylate. Examples of the hydroxy group-containing (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 1-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and polytetramethylene glycol mono(meth)acrylate. Other examples of the monomer b having a hydroxy group include hydroxystyrene.

[0039] Examples of the amino group-containing monomer b include primary or secondary amino group-containing (meth)acrylates, such as aminoethyl (meth)acrylate, ethylaminoethyl (meth)acrylate, aminopropyl (meth)acrylate, and ethylaminopropyl (meth)acrylate.

[0040] The monomer b having a thiol group includes a thiol group-containing (meth)acrylate, such as 2-(methylthio)ethyl methacrylate.

[0041] Examples of the monomer b having a hydrolyzable silyl group include (meth)acryloxyalkylalkoxysilanes such as γ-(meth)acryloxypropyltrimethoxysilane and γ-(meth)acryloxypropylmethyldimethoxysilane, (meth)acryloxyalkylalkoxyalkylsilanes, trimethoxyvinylsilane, dimethoxyethylsilane, triethoxyvinylsilane, triethoxyallylsilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, and vinyltris(2-methoxyethoxy)silane.

[0042] Monomer b is preferably at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, and hydroxystyrene, and more preferably at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0043] When the monomer b is at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, the modified acrylic resin (A) contains at least a structural unit represented by the above general formula (I) and also contains at least a structural unit represented by the following general formula (II): [ka]

[0044] In general formula (II), R a represents a methyl group or a hydrogen atom, and R b represents -CH2CH2OH, -CH2-CHOH-CH3, -CH2CH2CH2OH, -CH2-CHOH-CH2CH3, -CH2CH2-CHOH-CH3, or -CH2CH2CH2CH2OH.

[0045] When the modified acrylic resin (A) contains a structural unit derived from monomer b, the content of the structural unit derived from monomer b in the modified acrylic resin (A) is preferably about 0.01 to 20 parts by mass, more preferably about 0.1 to 10 parts by mass, even more preferably about 0.2 to 5 parts by mass, even more preferably about 0.5 to 3 parts by mass, and particularly preferably about 0.8 to 1.5 parts by mass, based on 100 parts by mass of the total structural units contained in the modified acrylic resin (A), from the viewpoints of reducing the difference in peel strength before and after heating and further reducing the likelihood of migration of surface layer components into the article. When the modified acrylic resin (A) contains not only structural units derived from monomer a but also structural units derived from monomer b, its primary structure may be either a random copolymer or a block copolymer.

[0046] [Monomer c] Monomer c is an acrylic monomer having a carbon-carbon unsaturated double bond and an alkyl group having 1 to 9 or 19 or more carbon atoms in one molecule. Monomer c can be used, for example, to adjust the concentration of the alkyl group contained in the surface layer, reduce the difference in peel strength between before and after heating of the release film, and further contribute to suppressing the migration of surface layer components to the article.

[0047] Suitable examples of the monomer c include (meth)acrylic acid derivatives. As the (meth)acrylic acid derivative, a monomer from which a constitutional unit represented by the following general formula (III) can be derived is preferred. [ka]

[0048] In general formula (III), R 1 represents a methyl group or a hydrogen atom, and R 3 represents an alkyl group having 1 to 9 carbon atoms or 19 or more carbon atoms, and the alkyl group may be a modified alkyl group containing a fluorine atom, oxygen atom, nitrogen atom, sulfur atom, chlorine atom, bromine atom, silicon atom, or the like.

[0049] Specific examples of the monomer c include methyl (meth)acrylate, butyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate stearyl (meth)acrylate, ethylhexyl (meth)acrylate, benzyl (meth)acrylate, (meth)acrylate salts, (meth)acrylonitrile, etc. Only one type of monomer c may be used, or two or more types may be mixed and used.

[0050] When the modified acrylic resin (A) contains a structural unit derived from monomer c, the content of the structural unit derived from monomer c in the modified acrylic resin (A) is preferably about 0.01 to 20 parts by mass, and more preferably about 0.1 to 10 parts by mass, based on 100 parts by mass of the total structural units contained in the modified acrylic resin (A), from the viewpoints of reducing the difference in peel strength before and after heating and further making it difficult for the components of the surface layer to migrate to the article.

[0051] [monomer d] Monomer d is a monomer different from monomers a, b, and c, and is a monomer copolymerizable with at least one of monomers a, b, and c.

[0052] Specific examples of monomer d include (i') aromatic vinyl monomers, (ii') olefinic hydrocarbon monomers, (iii') vinyl ester monomers, (iv') vinyl halide monomers, and (v') vinyl ether monomers. Monomer d may be used alone or in combination of two or more. Monomer d can be used, for example, to adjust the concentration of various functional groups contained in the surface layer, thereby reducing the difference in peel strength between before and after heating of the release film and further contributing to the prevention of migration of surface layer components to the article.

[0053] Examples of aromatic vinyl monomers include styrene, methylstyrene, ethylstyrene, chlorostyrene, and styrenes in which some hydrogen atoms have been substituted with fluorine atoms (for example, monofluoromethylstyrene, difluoromethylstyrene, trifluoromethylstyrene, etc.).

[0054] Examples of the olefinic hydrocarbon monomer include ethylene, propylene, butadiene, isobutylene, isoprene, and 1,4-pentadiene.

[0055] Examples of the vinyl ester monomer include vinyl acetate.

[0056] Examples of the vinyl halide monomer include vinyl chloride, vinylidene chloride, monofluoroethylene, difluoroethylene, and trifluoroethylene.

[0057] Examples of the vinyl ether monomer include vinyl methyl ether.

[0058] When the modified acrylic resin (A) contains a structural unit derived from monomer d, the content of the structural unit derived from monomer d in the modified acrylic resin (A) is preferably about 0.01 to 20 parts by mass, and more preferably about 0.1 to 10 parts by mass, based on 100 parts by mass of the total structural units contained in the modified acrylic resin (A), from the viewpoint of reducing the difference in peel strength before and after heating and further making it difficult for the components of the surface layer to migrate to the article.

[0059] From the viewpoint of reducing the difference in peel strength before and after heating and further making it difficult for the components of the surface layer to migrate to the article, the weight average molecular weight of the modified acrylic resin (A) is preferably 5 × 10 4 ~15×1 0 4 and more preferably 6×10 4 ~14×10 4 and more preferably 8 × 10 4 ~12×10 4 is.

[0060] The content of the modified acrylic resin (A) in the surface layer is not particularly limited, but from the viewpoint of reducing the difference in peel strength before and after heating and further preventing the components of the surface layer from migrating to the article, it is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, even more preferably more than 50 parts by mass, and particularly preferably 55 parts by mass or more, relative to 100 parts by mass of the total of the resins (A) and (B) constituting the surface layer. Furthermore, the content of the modified acrylic resin (A) in the surface layer is preferably 98 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 80 parts by mass or less, particularly preferably 70 parts by mass or less, and particularly preferably 60 parts by mass or less, relative to 100 parts by mass of the total of the resins (A) and (B) constituting the surface layer.

[0061] The modified acrylic resin (A) can be obtained by polymerizing the above-mentioned monomer a and, if necessary, monomer b, monomer c, and monomer d by a known polymerization method such as radical polymerization, anionic polymerization, or cationic polymerization.

[0062] An initiator may be used during polymerization. Examples of initiators that can be used include azo compounds, organic peroxides, etc. Among these, azo compounds are preferred in terms of the polymerization yield and ease of molecular weight control, and azobisisobutyronitrile (AIBN) is more preferred. The amount of polymerization agent used is determined based on the yield. In terms of ease of molecular weight control, the amount is preferably 0.01 to 3 parts by mass, more preferably 0.05 to 2 parts by mass, and more preferably 0.1 to 1.5 parts by mass, based on 100 parts by mass of the total of the structural units contained in the modified acrylic resin (A).

[0063] The modified acrylic resin (A) may also be obtained by graft polymerizing an alkyl group onto a polymer obtained by polymerizing at least monomer b (a monomer having a carbon-carbon unsaturated double bond and a crosslinkable functional group). That is, a polymer having a structure in which alkyl groups are graft polymerized onto some or all of the crosslinkable functional groups of the structural units derived from monomer b (hereinafter referred to as modified acrylic resin (A')) can be used alone or in a mixture with the modified acrylic resin (A), just like the modified acrylic resin (A).

[0064] In the modified acrylic resin (A'), the number of carbon atoms in the graft-polymerized alkyl group is preferably about 10 to 18, and more preferably about 12 to 14. The method for introducing the alkyl group by graft polymerization is not limited, and known methods for introduction can be used.

[0065] The same monomer b as exemplified for the modified acrylic resin (A) can also be preferably used for the modified acrylic resin (A'). Details of the monomer b are as described above.

[0066] The modified acrylic resin (A') may be a copolymer in which at least one of the monomers c and d is copolymerized with the monomer b.

[0067] The modified acrylic resin (A') can also preferably use the monomers c and d exemplified for the modified acrylic resin (A). Details of the monomers c and d are as described above.

[0068] <Resin (B)> The resin component forming the surface layer contains a modified acrylic resin (A) and a resin (B) different from the modified acrylic resin (A).

[0069] By including the resin (B) in the surface layer, the alkyl groups of the modified acrylic resin (A) can be easily segregated to the surface by taking advantage of the difference in compatibility with the modified acrylic resin (A), thereby reducing the difference in peel strength before and after heating and making it difficult for the components of the surface layer to migrate to the article.

[0070] The resin (B) is not particularly limited, but preferably includes at least one selected from the group consisting of polyester resins and acrylic resins. The polyester resin and acrylic resin can be appropriately selected from known polyester resins and acrylic resins. For example, examples of polyester resins include (i) non-convertible polyester resins obtained by the condensation reaction of a polyhydric alcohol and a polybasic acid, which are condensates of dibasic acids and dihydric alcohols or modified with non-drying oil fatty acids, and (ii) convertible polyester resins, which are condensates of dibasic acids and trihydric or higher alcohols. In this embodiment, the polyester resin (B) may be used alone or in combination of two or more.

[0071] Specific examples of polyhydric alcohols used as raw materials for polyester resins include dihydric alcohols, trihydric alcohols, and tetrahydric or higher polyhydric alcohols. Examples of dihydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, and neopentyl glycol. Examples of trihydric alcohols include glycerin, trimethylolethane, and trimethylolpropane. Examples of tetrahydric or higher polyhydric alcohols include diglycerin, triglycerin, pentaerythritol, dipentaerythritol, mannitol, and sorbitol. These polyhydric alcohols may be used alone or in combination of two or more.

[0072] Specific examples of polybasic acids used as raw materials for polyester resins include aromatic polybasic acids, saturated aliphatic polybasic acids, unsaturated aliphatic polybasic acids, and polybasic acids obtained by Diels-Alder reaction. Examples of aromatic polybasic acids include phthalic anhydride, terephthalic acid, isophthalic acid, and trimellitic anhydride. Examples of saturated aliphatic polybasic acids include succinic acid, adipic acid, and sebacic acid. Examples of unsaturated aliphatic polybasic acids include maleic acid, maleic anhydride, fumaric acid, itaconic acid, and citraconic anhydride. Examples of polybasic acids obtained by Diels-Alder reaction include cyclopentadiene-maleic anhydride adduct, terpene-maleic anhydride adduct, and rosin-maleic anhydride adduct. These polybasic acids may be used alone or in combination.

[0073] Specific examples of non-drying oil fatty acids that serve as denaturants include octylic acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, eleostearic acid, ricinoleic acid, dehydrated ricinoleic acid, or coconut oil, linseed oil, tung oil, castor oil, dehydrated castor oil, soybean oil, safflower oil, and their fatty acids. These may be used alone or in combination of two or more. Furthermore, as polyester resins, they may be used alone or in combination of two or more.

[0074] Examples of acrylic resins include homopolymers of (meth)acrylic acid esters, copolymers of two or more different (meth)acrylic acid ester monomers, and copolymers of (meth)acrylic acid esters with other monomers. Specific examples of (meth)acrylic resins include (meth)acrylic acid esters such as polymethyl(meth)acrylate, polyethyl(meth)acrylate, polypropyl(meth)acrylate, polybutyl(meth)acrylate, methyl(meth)acrylate-butyl(meth)acrylate copolymers, ethyl(meth)acrylate-butyl(meth)acrylate copolymers, ethylene-methyl(meth)acrylate copolymers, and styrene-methyl(meth)acrylate copolymers. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

[0075] The resin (B) different from the modified acrylic resin (A) preferably has a reactive functional group to react with the crosslinking agent (D) described below. In particular, the reactive functional group is preferably at least one selected from the group consisting of a carboxyl group and a hydroxyl group. When the resin (B) has a hydroxyl group, the hydroxyl value of the resin (B) is preferably 5 to 500 mgKOH / g, more preferably 10 to 300 mgKOH / g, and even more preferably 15 to 100 mgKOH / g.

[0076] The number average molecular weight of the resin (B) is preferably about 500 to 30000, more preferably about 1000 to 20000. When the number average molecular weight of the resin (B) is within the above range, the network structure tends to become dense when the surface layer is crosslinked with the crosslinking agent (D), and segregation of the modified acrylic resin (A) having an alkyl component and a crosslinkable functional group to the peel surface tends to occur.

[0077] The content of resin (B) in the surface layer is not limited, but from the viewpoint of reducing the difference in peel strength before and after heating and further preventing the components of the surface layer from migrating to the article, it is preferably 2 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, particularly preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more, based on 100 parts by mass of the total of resins (A) and (B) constituting the surface layer. Also, from the same viewpoint, it is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 50 parts by mass or less, even more preferably less than 50 parts by mass, and particularly preferably 45 parts by mass or less, based on 100 parts by mass of the total of resins (A) and (B) constituting the surface layer.

[0078] <(D) Crosslinking Agent> The resin component forming the surface layer contains a modified acrylic resin (A) and a resin (B) as well as a crosslinking agent (D). The crosslinking agent (D) functions to crosslink between modified acrylic resins (A) together, between resins (B) together, or between the modified acrylic resin (A) and the resin (B).

[0079] In this embodiment, the crosslinking agent (D) is a melamine compound. The melamine compound has a structure in which all hydrogen atoms of the amino groups are substituted with at least one of an alkoxyalkyl group and an alkanol group. That is, the melamine compound can be said to have at least one type selected from the group consisting of an alkoxyalkyl group and an alkanol group as a substituent on the amino group. Furthermore, the melamine compound has a structural unit in which three amino groups are bonded to a triazine ring. In this embodiment, the total of six substituents bonded to the three amino groups are at least one type selected from the group consisting of an alkoxyalkyl group and an alkanol group, and it can be said that the melamine compound does not have any other substituents such as hydrogen atoms.

[0080] More specifically, the melamine compound can be represented by the following general formula (IV). [ka]

[0081] In general formula (IV), the six substituents R on the three amino groups bonded to the triazine ring are each a group in which a hydrogen atom of the amino group is substituted. Each of the six substituents R is independently an alkoxyalkyl group or an alkanol group. n is a number of 1 or more and indicates the average n-number of melamine compounds.

[0082] The term "alkoxyalkyl group" refers to a C1-6 alkyloxyC1-6 alkyl group such as a methoxymethyl group or a 1-ethoxyethyl group. The term "alkanol group" refers to a group in which the hydrogen atom on the terminal methyl group of a linear or branched alkyl group is substituted with a hydroxy group, such as a hydroxymethyl group, a 2-hydroxyethyl group, a 3-hydroxypropyl group, a 2-hydroxy-n-propyl group (-CH2-CHOH-CH3), or a 2-hydroxy-1-methylethyl group. Here, C1-6 refers to a group having 1 to 6 carbon atoms.

[0083] In this embodiment, from the viewpoint of reducing the difference in peel strength before and after heating and further preventing the components of the surface layer from migrating to the article, the melamine compound has six substituents R in general formula (IV), of which at least one is preferably an alkoxyalkyl group, more preferably three or more are alkoxyalkyl groups, and particularly preferably all six are alkoxyalkyl groups. Furthermore, of the six substituents R in general formula (IV), it is preferred that five or fewer, more preferably three or fewer, and even more preferably none, are alkanol groups. In the examples described below, all six substituents R in the Type F melamine compound are alkoxyalkyl groups.

[0084] In the melamine compound, the alkoxyalkyl group preferably has 2 to 5 carbon atoms, more preferably 2. Specific preferred examples of the alkoxyalkyl group include a propoxymethyl group, an ethoxymethyl group, and a methoxymethyl group, with a methoxymethyl group being particularly preferred among these. Furthermore, the alkanol group preferably has 1 to 3 carbon atoms, more preferably 1. Specific preferred examples of the alkanol group include a propanol group (3-hydroxypropyl group), an ethylol group (2-hydroxyethyl group), and a methylol group (hydroxymethyl group), with a methylol group being particularly preferred among these.

[0085] The average n number of the melamine compound is preferably about 1.0 to 3.0, more preferably about 1.1 to 2.0, and even more preferably about 1.2 to 1.5. The crosslinking agent (D) may be used alone or in combination of two or more.

[0086] In this embodiment, from the viewpoint of reducing the difference in peel strength before and after heating and further making it difficult for the components of the surface layer to migrate to the article, it is particularly preferable that the melamine compound is a compound represented by general formula (V). [ka] [Here, Me represents a methyl group.]

[0087] In the general formula (V), the average n amount of the melamine compound is in the above-mentioned range.

[0088] In this embodiment, the resin component forming the surface layer may contain a crosslinking agent other than the crosslinking agent (D), but it is preferable that the crosslinking agent contained in the resin component is only the crosslinking agent (D).

[0089] Examples of other crosslinking agents include, but are not limited to, polyfunctional amino compounds different from the melamine compounds, isocyanate compounds (including monoisocyanates, diisocyanates, polyfunctional isocyanates, etc.), polyfunctional epoxy compounds, polyfunctional metal compounds, and dialdehydes.

[0090] Examples of polyfunctional amino compounds other than the melamine compounds include urea compounds, benzoguanamine compounds, and diamines. Examples of urea compounds include alkylated urea compounds (e.g., Nikalac MX-270 manufactured by Nippon Carbide Industries Co., Ltd.). Examples of benzoguanamine compounds include benzoguanamine and methylated benzoguanamine. Examples of diamines include ethylenediamine, tetramethylenediamine, hexamethylenediamine, N,N'-diphenylethylenediamine, and p-xylylenediamine.

[0091] Examples of polyfunctional isocyanate compounds include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), xylene diisocyanate (XDI), naphthalene diisocyanate (NDI), trimethylolpropane (TMP) adduct TDI, TMP adduct HDI, TMP adduct IPDI, and TMP adduct XDI.

[0092] Examples of polyfunctional epoxy compounds include N,N,N',N'-tetraglycidylmetaxylenediamine and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

[0093] Examples of polyfunctional metal compounds include aluminum chelate compounds, titanium chelate compounds, trimethoxyaluminum, etc. Examples of aluminum chelate compounds include aluminum trisacetylacetonate and aluminum ethylacetoacetate diisopropylate. Examples of titanium chelate compounds include titanium tetraacetylacetonate, titanium acetylacetonate, titanium octylene glycolate, tetraisopropoxytitanium, and tetramethoxytitanium.

[0094] In the surface layer, the content of the crosslinking agent (D) is preferably 3 parts by mass or more, more preferably 4 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the modified acrylic resin (A) and the resin (B) different from the modified acrylic resin (A), from the viewpoints of reducing the difference in peel strength before and after heating and further preventing the components of the surface layer from migrating to the article. Also, from the same viewpoint, the content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the modified acrylic resin (A) and the resin (B) different from the modified acrylic resin (A).

[0095] <Other ingredients> [Additives] In addition to the resin component as the main component, the surface layer and the substrate layer may each contain at least one additive, if necessary. Examples of additives include stabilizers such as acid catalysts, antioxidants, chlorine absorbers, and UV absorbers, as well as lubricants, plasticizers, flame retardants, antistatic agents, colorants, and antiblocking agents. Such additives may be added to the substrate layer and the surface layer within a range that does not impair the effects of the present invention. At least one additive may be contained in only one of the substrate layer and the surface layer, or in both the substrate layer and the surface layer. Furthermore, the substrate layer and the surface layer may contain the same or different additives.

[0096] The "acid catalyst" improves the density of the coating film through a crosslinking reaction and can suppress the precipitation of oligomers. Suitable acid catalysts for this crosslinking reaction include, for example, paratoluenesulfonic acid, methyl paratoluenesulfonate, ethyl paratoluenesulfonate, n-butyl paratoluenesulfonate, benzenesulfonic acid, sulfonic acid, and methanesulfonic acid. One or more acid catalysts can be used in combination. The amount of the acid catalyst used is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of the resin components constituting the surface layer. Furthermore, the amount of the acid catalyst used is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1.5 parts by mass or less, per 100 parts by mass of the resin components constituting the surface layer.

[0097] The antioxidant is not particularly limited, but examples thereof include 2,6-di-tert-butyl-p-cresol (common name: BHT), phenol-based, hindered amine-based, phosphite-based, lactone-based, and tocopherol-based antioxidants. Specific examples include dibutylhydroxytoluene, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4hydroxy)benzene, and tris(2,4-di-t-butylphenyl)phosphite.

[0098] The "chlorine absorbent" is not particularly limited, but examples thereof include metal soaps such as calcium stearate.

[0099] The "ultraviolet absorber" is not particularly limited, but examples thereof include benzotriazole (e.g., Tinuvin 328 manufactured by BASF), benzophenone (e.g., Cysorb UV-531 manufactured by Cytec), and hydroxybenzoate (e.g., UV-CHEK-AM-340 manufactured by Ferro).

[0100] The "plasticizer" is not particularly limited, but examples thereof include citrate esters, dibutyl phthalate, polyethylene glycols, propylene glycols, and glycerin.

[0101] The "flame retardant" is not particularly limited, but examples thereof include halogen compounds, aluminum hydroxide, magnesium hydroxide, phosphates, borates, and antimony oxides.

[0102] The "antistatic agent" is not particularly limited, but examples thereof include glycerin monoesters (such as glycerin monostearate), and ethoxylated secondary amines.

[0103] "Colorants" include various colored dyes, colored pigments, and fluorescent dyes.

[0104] The "antiblocking agent" is added to prevent blocking and is not particularly limited as long as it does not exhibit the effect of a nucleating agent. Examples of the antiblocking agent include inorganic pigments such as silica particles, alumina, (synthetic) zeolite, calcium carbonate, kaolin, talc, mica, zinc oxide, magnesium oxide, quartz, magnesium carbonate, barium sulfate, and titanium dioxide, as well as organic pigments such as polystyrene, polyacrylic particles, polymethyl methacrylate (PMMA) particles, crosslinked polyethylene particles, polyester, polyamide, polycarbonate, polyether, polyethersulfone, polyetherimide, polyphenylene sulfide, polyetheretherketone, polyamideimide, (crosslinked) melamine resin, benzoguanamine resin, urea resin, amino resin, furan resin, epoxy resin, phenolic resin, unsaturated polyester resin, vinyl ester resin, diallyl phthalate resin, polyimide resin, fatty acid amide, and fatty acid glycerin ester compound. The antiblocking agent is preferably a pigment having a particle size of 0.1 μm to 10 μm, and PMMA and silica particles are more preferred because they provide excellent blocking resistance and slippage. For example, by incorporating such a pigment into the aforementioned base layer, the slippage of the front and back surfaces of the base layer can be improved and blocking can be suppressed.

[0105] In this embodiment, it is preferable that the surface layer contains substantially no silicone compounds so as not to adversely affect electrical components, etc. Note that "substantially no silicone compounds" means that the amount of silicone compounds is preferably 500 μg / g or less, more preferably 100 μg / g or less.

[0106] The thickness of the surface layer is preferably 0.01 μm or more, more preferably 0.05 μm or more, and particularly preferably 0.1 μm or more, from the viewpoint of easily improving peelability. The thickness of the surface layer is preferably 3 μm or less, more preferably 1.5 μm or less, and more preferably 1 μm or less, from the viewpoint of migration of the polymer component to the base layer. The thickness of the surface layer is observed using a transmission electron microscope (TEM) (for example, "HT7700" manufactured by Hitachi High-Technologies Corporation), and specifically measured by the method described in the examples.

[0107] [Method for producing surface layer] The surface layer can be formed by laminating a resin component that forms the surface layer on the base layer. In a preferred embodiment of the method for producing the surface layer, a coating liquid containing a modified acrylic resin (A), a resin (B) different from the modified acrylic resin (A), a crosslinking agent (D), and optionally other components and at least one solvent is applied to the base layer, crosslinking the resin (A) and the resin (B), and then removing the solvent from the coating layer obtained by the coating.

[0108] The solvent is not particularly limited as long as it can dissolve and / or uniformly disperse components other than the solvent in the coating liquid. Examples of the solvent include ketone / ester organic solvents such as methyl ethyl ketone (MEK) and ethyl acetate, and organic solvents such as aliphatic hydrocarbons such as n-heptane and methylcyclohexane. The boiling point of the solvent is preferably 10 to 150°C, more preferably 20 to 120°C, from the viewpoint of easily improving the handleability of the coating liquid and the production efficiency of the peelable film. Only one type of solvent may be used, or two or more types may be mixed and used.

[0109] The concentration of components other than the solvent in the coating solution (i.e., the concentration of solid components remaining in the surface layer after the solvent is removed, e.g., the total concentration of the modified acrylic resin (A), the resin (B) different from the modified acrylic resin (A), and the crosslinking agent (D), as well as other components added as necessary) is not particularly limited, but from the viewpoint of the stability and coatability of the coating solution, it is preferably 1 to 24 mass% relative to the total amount of the coating solution, more preferably 1 to 19 mass%, even more preferably 2 to 14 mass%, and particularly preferably 2 to 10 mass%. The coating method is not particularly limited, and examples include methods using a blade coater, air knife coater, roll coater, bar coater, gravure coater, microgravure coater, rod blade coater, lip coater, die coater, curtain coater, or printing machine.

[0110] The resin (A) and the resin (B) in the coating layer can be crosslinked by heating the coating layer in the presence of the crosslinking agent (D), for example, by applying hot air to the coating layer or by heating the coating layer with electromagnetic waves such as infrared rays. The method for removing the solvent from the coating layer is not particularly limited as long as it can volatilize the solvent. Note that removing the solvent does not only mean completely removing the solvent, but also includes removing the solvent to the extent that a layer is formed. Examples of methods for removing the solvent include a method of drying the coating layer by blowing air on it, and a method of drying the coating layer by heating it. From the viewpoint of easily achieving both solvent removal and promotion of the crosslinking reaction, the temperature for drying by air or heating is preferably 70 to 170° C., more preferably 90 to 150° C. The drying time or heating time is preferably 10 to 300 seconds, more preferably 15 to 90 seconds, and even more preferably 20 to 50 seconds.

[0111] The peelable film of the present embodiment may or may not be stretched, but from the viewpoint of easily obtaining good and easy peelability, it is preferable that the surface layer is unstretched.

[0112] [Roughening of the surface of the release film] In this embodiment, the surface of the release film may be given a fine surface roughness to improve suitability for winding, as long as it does not interfere with lamination when used as a release film. Methods for giving fine irregularities to the surface of the release film include embossing, etching, and various known surface roughening methods.

[0113] The T-peel peel force of the release film of this embodiment can be set appropriately depending on the intended use, ranging from very light (very low) to moderately light (moderately low). From the viewpoint of easily improving the adhesion of the release film to the adherend, it is preferably 0.01 N / 25 mm or more, more preferably 0.02 N / 25 mm or more, and even more preferably 0.05 N / 25 mm or more. From the viewpoint of easily improving releasability, the T-peel peel force is preferably 2.00 N / 25 mm or less, more preferably 1.50 N / 25 mm or less, more preferably 1.00 N / 25 mm or less, more preferably 0.70 N / 25 mm or less, more preferably 0.50 N / 25 mm or less, more preferably 0.40 N / 25 mm or less, more preferably 0.30 N / 25 mm or less, more preferably 0.25 N / 25 mm or less, more preferably 0.22 N / 25 mm or less, and even more preferably 0.20 N / 25 mm or less. The T-peel strength of the release film is measured by the following method.

[0114] [T-peel peeling force] At room temperature (25°C), a 50mm wide x 200mm long polyester adhesive tape (Nitto Denko Corporation No. 31B tape, acrylic adhesive) was applied to the surface of the surface layer of the release film by rolling a 2kg roller twice. The resulting film was heat-treated at 160°C for 90 seconds and then left to stand for 20 hours at a temperature of 70°C and humidity of 50%. Next, at room temperature (25°C), a 25mm wide sample was cut from the resulting film and used as the measurement sample. A T-peel test was performed at a speed of 1000mm / min using a tensile tester (e.g., Minebea Co., Ltd.'s Technograph TGI-1kN universal tensile tester), and the peel strength was measured. The value measured in this way was the T-peel peel strength (T-peel peel strength before heating).

[0115] Furthermore, it is preferable that the difference between the T-peel peel strength after heating and the T-peel peel strength before heating is small, and the value of (T-peel peel strength after heating) - (T-peel peel strength before heating) is preferably -0.20 to +0.20, more preferably -0.10 to +0.10, even more preferably -0.08 to +0.05, and particularly preferably -0.04 to +0.02. The T-peel peel strength after heating of the release film is measured by the following method.

[0116] [T-peel peeling force after heating] In a room temperature (25°C) environment, a 50mm wide x 200mm long polyester adhesive tape (Nitto Denko Corporation No. 31B tape, acrylic adhesive) is applied to the surface of the surface layer of the release film by rolling a 2kg roller back and forth twice to obtain a pre-treated adhesive product. The adhesive product is then heat-treated at 160°C for 90 seconds. Note that a hot air dryer is used for the heat treatment. Here, heat treatment at 160°C for 90 seconds means that the adhesive product is placed in a hot air dryer set at 160°C. Next, a weight is placed on the adhesive product so that a load of 5KPa is applied, and the product is left to stand for 20 hours in an environment of 70°C and 50% humidity. Next, in a room temperature environment (25°C), a sample cut to a width of 25 mm from the obtained film is used as a measurement sample, and a T-peel peel is performed at a speed of 1000 mm / min using a tensile tester (for example, a Technograph TGI-1kN universal tensile tester manufactured by Minebea Co., Ltd.), and the peel force at that time is measured. The value measured in this way is the T-peel peel force after heating.

[0117] [Thickness of peelable film] From the viewpoint of ease of handling as a release film, the thickness of the release film is preferably 18 μm or more, more preferably 20 μm or more. From the viewpoint of ease of handling as a release film, the thickness of the release film is preferably 100 μm or less, more preferably 50 μm or less. The thickness of the release film of this embodiment is measured using a micrometer (JIS B-7502) in accordance with JIS C-2151.

[0118] The release film of this embodiment has good releasability and maintains this good releasability even after heat treatment, making it an excellent release film. The release film of this embodiment can be widely used in industrial and medical fields, and is suitable for use as, for example, a release film used in surface protection films and adhesive tapes, a release liner or separator film, a separator film for process tapes (dicing, die bonding, backgrinding) used in semiconductor product manufacturing, a carrier for forming unfired sheets in ceramic capacitor manufacturing, a carrier for composite material manufacturing, a separator film for protective materials, etc. The release film of this embodiment is attached to an adherend such as a tape or sheet; a resin component for electrical equipment, electronic equipment, wearable equipment, medical equipment, and building materials; an intermediate component manufactured in the process of manufacturing the semiconductor products; various electrical components (hard disks, motors, connectors, switches, etc.); the object when used as the carrier; or a dry film resist. In addition, when the above-mentioned adherend has an adhesive layer (for example, a solvent-based, emulsion-based, or hot-melt pressure-sensitive adhesive layer), the release film of this embodiment may be attached to the adherend so that the surface layer of the release film of this embodiment is bonded to the adhesive layer. The method for attaching the release film of this embodiment to an object is not particularly limited. The release film of this embodiment may be attached to the object by, for example, cutting the release film appropriately according to the area to be attached, or if both the release film of this embodiment and the object to which it is attached are wound up in a roll, they may be attached by roll-to-roll bonding. [Example]

[0119] The present invention will be described in detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples. Unless otherwise specified, parts and % represent "parts by mass" and "% by mass", respectively.

[0120] [Measurement and evaluation methods] The various measurement and evaluation methods used in the examples and comparative examples are as follows.

[0121] [Surface layer thickness] After cutting the specimen, the surface was coated with Os and embedded in resin. Then, the specimen was trimmed and surface-ground using an ultramicrotome equipped with a diamond knife, and ultrathin sections were prepared. After that, the specimen was observed under a transmission electron microscope (TEM). Sectioning device: Ultramicrotome (Leica EM UC7) Knife: DIATOME ULTRADRY Observation device: TEM (HT7700 model, manufactured by Hitachi High-Technologies Corporation) Accelerating voltage: 100 kV Photo magnification: ×300,000

[0122] [Thickness of base layer and peelable film] The thickness of the release film and the substrate layer was measured using a micrometer (JIS B-7502) in accordance with JIS C-2151.

[0123] [T-peel peeling force] A 50 mm wide x 200 mm long polyester adhesive tape (No. 31B tape, acrylic adhesive, manufactured by Nitto Denko Corporation) was applied to the surface of the film on the surface layer side of the peelable film by rolling a 2 kg roller back and forth twice to obtain a pre-treated adhesive product. Next, a weight was placed on the patch so that a load of 5 KPa was applied, and the patch was left to stand in an environment of 70°C and 50% humidity for 20 hours. Next, at room temperature, each of the resulting treated adhesive films was cut into 25 mm wide samples to be used as measurement samples. A T-peel test was performed at a speed of 1000 mm / min using a peel tester (Minebea Co., Ltd., Technograph TGI-1kN universal tensile tester), and the peel strength was measured. Each measurement was performed three times, and the average value was used as the T-peel strength (T-peel strength before heating) of each release film. The results are shown in Table 1.

[0124] [T-peel peeling force after heating] A 50 mm wide x 200 mm long polyester adhesive tape (No. 31B tape, acrylic adhesive, manufactured by Nitto Denko Corporation) was applied to the surface of the film on the surface layer side of the peelable film by rolling a 2 kg roller back and forth twice to obtain a pre-treated adhesive product. The patch was then subjected to a heat treatment at 160°C for 90 seconds. A hot air dryer was used for the heat treatment. Here, the heat treatment at 160°C for 90 seconds means that the patch was placed in a hot air dryer set at 160°C. Next, a weight was placed on the patch to apply a load of 5 KPa, and the patch was left to stand for 20 hours in an environment of 70°C and 50% humidity. Next, the T-peel peel strength after heating was obtained using the same method as the measurement and calculation method for T-peel peel strength in the above section [T-peel peel strength]. The results are shown in Table 1.

[0125] [Evaluation of residual adhesion rate] The polyester adhesive tape used in measuring the T-peel peel strength of the surface layer side of each release film in the above [T-peel peel strength] (the polyester adhesive tape after peeling during the above measurement) was attached to a stainless steel plate (SUS plate) by rolling a 2 kg roller back and forth twice. Next, a T-peel peel test was performed on the attached product having the stainless steel plate obtained by the above attachment at a speed of 1000 mm / min, and the peel strength (X) at that time was measured. On the other hand, a T-peel test was carried out in the same manner as in the above [T-peel peel force], except that a polyester adhesive tape was attached to the surface of a Teflon sheet (skived tape MSF-100, 100 μm thick, manufactured by Chukoh Chemical Industry Co., Ltd.) instead of the film surface on the surface layer side of the release film, and the polyester adhesive tape after the peel test was attached to a stainless steel plate (SUS plate) by rolling a 2 kg roller back and forth twice. Next, a T-peel test was carried out on the attached product having the stainless steel plate obtained by the above attachment at a speed of 1000 mm / min, and the peel force (Y) at that time was measured. Next, the residual adhesion rate was calculated using the following formula. The smaller the residual adhesion rate, the more easily the components of the surface layer of the release film are evaluated to migrate to the polyester pressure-sensitive adhesive tape. A residual adhesion rate of 100% means that the components of the surface layer of the release film have not migrated to the polyester pressure-sensitive adhesive tape to the same extent as the components of the surface of the Teflon sheet have not migrated to the polyester pressure-sensitive adhesive tape, and is the most preferable release film according to this embodiment. The results are shown in Table 1. Residual adhesion rate (%)=(X) / (Y)×100

[0126] In the release film according to this embodiment, the residual adhesion rate is preferably 84% or more, more preferably 87% or more, even more preferably 90% or more, even more preferably 93% or more, and particularly preferably 97% or more. The residual adhesion rate may be 100%.

[0127] Example 1 A 1-liter flask equipped with a stirrer, nitrogen inlet tube, thermometer, and condenser was charged with 99 parts by weight of lauryl acrylate (LA) as monomer a, 1 part by weight of 2-hydroxyethyl acrylate (HEA) as monomer b, 0.2 parts by weight of azobisisobutyronitrile (AIBN) as a polymerization initiator, 100 parts by weight of toluene, and 100 parts by weight of ethyl acetate. Next, a polymerization reaction was carried out in the flask at 80°C for 2 hours under a nitrogen stream. An additional 1.0 part by weight of azobisisobutyronitrile was added and polymerization was continued for another 2 hours to obtain a solution (solids content 30% by weight) containing an alkyl acrylate-HEA copolymer (hereinafter referred to as "modified acrylic resin (A)"). The weight-average molecular weight of the resulting modified acrylic resin (A) was 10.5 x 10 4 It was. Furthermore, as the polyester resin α, which is the resin (B), Vylon M802 (manufactured by Toyobo Co., Ltd., number average molecular weight (Mn): 3 × 10 3, hydroxyl value: 37 mgKOH / g, solid content: 70% by mass), Nikalac MW-30MLF (manufactured by Nippon Carbide Industries Co., Ltd., average 1.3-mer 98% by mass) was prepared as the melamine crosslinking agent (D) (type F described below) represented by the above general formula (V), and Dryer 900 (manufactured by Hitachi Chemical Co., Ltd., paratoluenesulfonic acid 50% by mass) was prepared as the acid catalyst (E). Next, the modified acrylic resin (A)-containing solution, a resin (B) different from the modified acrylic resin (A), and a melamine crosslinker (D) were mixed and stirred in a toluene:methyl ethyl ketone (MEK) mixed solvent of 30:70 (mass ratio), and then the acid catalyst (E) was added and stirred. The modified acrylic resin (A)-containing solution, resin (B), melamine crosslinker (D), and acid catalyst (E) were mixed and stirred so that the solid content was 56 parts by mass of the modified acrylic resin (A), 44 parts by mass of the polyester resin, 6 parts by mass of the melamine crosslinker, and 0.7 parts by mass of the acid catalyst (E), respectively. This resulted in a coating solution 1 with a solid content concentration of 4.4% by mass and an acid catalyst concentration of 0.03% by mass. Next, a biaxially stretched polyethylene terephthalate film (biaxially stretched PET film, "E5100" manufactured by Toyobo Co., Ltd.) having a thickness of 38 μm was prepared as a substrate layer. Next, the coating liquid 1 was applied onto the substrate layer using a Mayer bar (manufactured by Yasuda Seiki Seisakusho Co., Ltd., shaft diameter: 6.35 mmφ, ROD No. 4), and dried in an explosion-proof dryer at 140°C for 30 seconds, thereby obtaining a peelable film of Example 1 having a substrate layer and a surface layer (surface layer thickness: 0.2 µm).

[0128] <Example 2> The modified acrylic resin (A)-containing solution, resin (B), melamine crosslinking agent (D), and acid catalyst (E) were mixed and stirred so that the modified acrylic resin (A) was 56 parts by mass, the polyester resin was 44 parts by mass, the melamine crosslinking agent was 6 parts by mass, and the acid catalyst (E) was 1.1 parts by mass, respectively, in terms of solid content, to obtain coating liquid 2 (solid content concentration 2.8% by mass, acid catalyst concentration 0.03% by mass). Furthermore, the coating liquid 2 was coated on the substrate layer so that the thickness after drying was 0.1 μm. The peelable film of Example 2 was obtained by performing the same operations as in Example 1 except for the above.

[0129] Example 3 The modified acrylic resin (A)-containing solution, resin (B), melamine crosslinking agent (D), and acid catalyst (E) were mixed and stirred so that the solid content was 75 parts by mass of the modified acrylic resin (A), 25 parts by mass of the polyester resin, 6 parts by mass of the melamine crosslinking agent, and 0.7 parts by mass of the acid catalyst (E), respectively, to obtain a coating solution 3 (solid content concentration 4.4% by mass, acid catalyst concentration 0.03% by mass). The other operations were the same as in Example 1, to obtain a peelable film of Example 3.

[0130] Example 4 The modified acrylic resin (A)-containing solution, resin (B), melamine crosslinking agent (D), and acid catalyst (E) were mixed and stirred so that the solid content was 95 parts by mass of the modified acrylic resin (A), 5 parts by mass of the polyester resin, 6 parts by mass of the melamine crosslinking agent, and 0.7 parts by mass of the acid catalyst (E), respectively, to obtain a coating solution 4 (solid content concentration 4.4% by mass, acid catalyst concentration 0.03% by mass). The other operations were the same as in Example 1, to obtain a peelable film of Example 4.

[0131] <Example 5> The modified acrylic resin (A)-containing solution, resin (B), melamine crosslinking agent (D), and acid catalyst (E) were mixed and stirred so that the solid content was 32 parts by mass of the modified acrylic resin (A), 68 parts by mass of the polyester resin, 6 parts by mass of the melamine crosslinking agent, and 0.7 parts by mass of the acid catalyst (E), respectively, to obtain a coating solution 5 (solid content concentration 4.4% by mass, acid catalyst concentration 0.03% by mass). The other operations were the same as in Example 1, to obtain a peelable film of Example 5.

[0132] Example 6 The weight average molecular weight of the modified acrylic resin (A) is 8.1 × 10 4 The amount of azobisisobutyronitrile (AIBN) used and the temperature during the polymerization reaction were changed so that the following results were obtained: The other operations were the same as those in Example 1, thereby obtaining a peelable film of Example 6.

[0133] Example 7 The weight average molecular weight of the modified acrylic resin (A) is 5.8 × 10 4 The amount of azobisisobutyronitrile (AIBN) used and the temperature during the polymerization reaction were changed so that the following results were obtained: The other operations were the same as those in Example 1, thereby obtaining a peelable film of Example 7.

[0134] Example 8 The weight average molecular weight of the modified acrylic resin (A) is 13.0 × 10 4 The amount of azobisisobutyronitrile (AIBN) used and the temperature during the polymerization reaction were changed so that the following results were obtained: The other operations were the same as those in Example 1, thereby obtaining a peelable film of Example 8.

[0135] Example 9 A 1-liter flask equipped with a stirrer, nitrogen inlet tube, thermometer, and condenser was charged with 99.5 parts by weight of lauryl acrylate (LA) as monomer a, 0.5 parts by weight of 2-hydroxyethyl acrylate (HEA) as monomer b, 0.2 parts by weight of azobisisobutyronitrile (AIBN) as an initiator, 100 parts by weight of toluene, and 100 parts by weight of ethyl acetate. Next, a polymerization reaction was carried out in the flask at 80°C for 2 hours under a nitrogen stream. An additional 1.0 part by weight of azobisisobutyronitrile was added and polymerization was continued for another 2 hours to obtain a solution containing a modified acrylic resin (A) (solids content 30% by weight). The weight-average molecular weight of the resulting modified acrylic resin (A) was 6.8 x 10 4 The other operations were the same as in Example 1, and a peelable film of Example 9 was obtained.

[0136] Example 10 A 1-liter flask equipped with a stirrer, nitrogen inlet tube, thermometer, and condenser was charged with 98.0 parts by weight of lauryl acrylate (LA) as monomer a, 2.0 parts by weight of 2-hydroxyethyl acrylate (HEA) as monomer b, 0.2 parts by weight of azobisisobutyronitrile (AIBN) as an initiator, 100 parts by weight of toluene, and 100 parts by weight of ethyl acetate. Next, a polymerization reaction was carried out in the flask at 80°C for 2 hours under a nitrogen stream. An additional 1.0 part by weight of azobisisobutyronitrile was added and polymerization was continued for another 2 hours to obtain a solution containing a modified acrylic resin (A) (solids content 30% by weight). The weight-average molecular weight of the resulting modified acrylic resin (A) was 10.3 x 10 4 The other operations were the same as in Example 1, and a peelable film of Example 10 was obtained.

[0137] Example 11 A 1-liter flask equipped with a stirrer, nitrogen inlet tube, thermometer, and condenser was charged with 99.0 parts by weight of isodecyl acrylate (IDAA) as monomer a, 1.0 part by weight of 2-hydroxyethyl acrylate (HEA) as monomer b, 0.2 parts by weight of azobisisobutyronitrile (AIBN) as an initiator, 100 parts by weight of toluene, and 100 parts by weight of ethyl acetate. Next, a polymerization reaction was carried out in the flask at 80°C for 2 hours under a nitrogen stream. An additional 1.0 part by weight of azobisisobutyronitrile was added and polymerization was continued for 2 hours to obtain a solution containing a modified acrylic resin (A) (solids content 30% by weight). The weight-average molecular weight of the resulting modified acrylic resin (A) was 10.9 x 10 4 The other operations were the same as in Example 1, and a peelable film of Example 11 was obtained.

[0138] Example 12 A 1-liter flask equipped with a stirrer, nitrogen inlet tube, thermometer, and condenser was charged with 99.0 parts by mass of stearyl acrylate (STA) as monomer a, 1.0 part by mass of 2-hydroxyethyl acrylate (HEA) as monomer b, 0.2 parts by mass of azobisisobutyronitrile (AIBN) as an initiator, 100 parts by mass of toluene, and 100 parts by mass of ethyl acetate. Next, a polymerization reaction was carried out in the flask at 80°C for 2 hours under a nitrogen stream. An additional 1.0 part by mass of azobisisobutyronitrile was added and polymerization was continued for 2 hours to obtain a solution containing a modified acrylic resin (A) (solids content 30% by mass). The weight-average molecular weight of the resulting modified acrylic resin (A) was 7.3 x 10 4 Other operations were the same as in Example 1, and a peelable film of Example 12 was obtained.

[0139] Example 13 The peelable film of Example 13 was obtained in the same manner as in Example 1, except that an acrylic resin (Acrydic WMG-521, manufactured by DIC Corporation, Tg = 30°C, acid value: 6.5 mg KOH / g, solid content 60 mass%) was used instead of a polyester resin as resin (B).

[0140] Example 14 As the polyester resin (B), polyester resin β (Vylon 20SS (manufactured by Toyobo Co., Ltd., number average molecular weight (Mn): 17 × 10)) was used instead of polyester resin α (Vylon M802). 3 A release film of Example 14 was obtained in the same manner as in Example 1, except that a release agent having a hydroxyl value of 6 mg KOH / g and a solid content of 30% by mass was used.

[0141] Example 15 A 1-liter flask equipped with a stirrer, nitrogen inlet tube, thermometer, and condenser was charged with 99 parts by weight of lauryl acrylate (LA) as monomer a, 1 part by weight of 2-hydroxyethyl acrylate (HEA) as monomer b, 0.2 parts by weight of azobisisobutyronitrile (AIBN) as an initiator, 100 parts by weight of toluene, and 100 parts by weight of ethyl acetate. Next, a polymerization reaction was carried out in the flask at 80°C for 2 hours under a nitrogen stream. An additional 1.0 part by weight of azobisisobutyronitrile was added and polymerization was continued for 2 hours to obtain a solution containing a modified acrylic resin (A) (solids content 30% by weight). The weight-average molecular weight of the resulting modified acrylic resin (A) was 10.5 x 10 4 It was. In addition, polyester resin α (Vylon M802 (manufactured by Toyobo Co., Ltd., number average molecular weight (Mn): 3 × 10)) was used as a resin (B) different from the modified acrylic resin (A). 3 , hydroxyl value: 37 mg KOH / g, solid content: 70% by mass), Nikalac MS-11 (manufactured by Nippon Carbide Industries Co., Ltd., average 1.8-mer, 60% by mass) of Type M (a melamine compound in which all of the substituents R on three amino groups bonded per structural unit are either methoxymethyl groups or methylol groups, and at least one of the substituents R is a methylol group) as the melamine crosslinking agent (D), which will be described later, and Dryer 900 (manufactured by Hitachi Chemical Co., Ltd., p-toluenesulfonic acid 50% by mass) as the acid catalyst (E) were prepared. Next, the modified acrylic resin (A)-containing solution, the resin (B) different from the modified acrylic resin (A), and the melamine crosslinker (D) were mixed and stirred in a toluene:methyl ethyl ketone (MEK) mixed solvent of 30:70 (mass ratio), and then the acid catalyst (E) was added and stirred. The modified acrylic resin (A)-containing solution, the resin (B) different from the modified acrylic resin (A), the melamine crosslinker (D), and the acid catalyst (E) were mixed and stirred so that the solid content was 56 parts by mass of the modified acrylic resin (A), 44 parts by mass of the polyester resin, 6 parts by mass of the melamine crosslinker, and 1.2 parts by mass of the acid catalyst (E), respectively. This resulted in a coating solution 6 with a solid content concentration of 2.8% by mass and an acid catalyst concentration of 0.05% by mass. Next, a biaxially stretched polyethylene terephthalate film (biaxially stretched PET film, "E5100" manufactured by Toyobo Co., Ltd.) having a thickness of 38 μm was prepared as a substrate layer. Next, the coating liquid 6 was applied onto the substrate layer using a Mayer bar (manufactured by Yasuda Seiki Seisakusho Co., Ltd., shaft diameter: 6.35 mmφ, ROD No. 4), and dried in an explosion-proof dryer at 150°C for 60 seconds, thereby obtaining a peelable film of Example 15 having a substrate layer and a surface layer (surface layer thickness: 0.1 µm).

[0142] <Comparative Example 1> As the melamine crosslinking agent (D), Nikalac MX-750 (manufactured by Nippon Carbide Industries Co., Ltd., average dimer 80% by mass), which is a type IM melamine compound (a melamine compound in which all of the substituents R on the three amino groups bonded per structural unit are either methoxymethyl groups, methylol groups, or hydrogen atoms, and at least one of the substituents R is a methylol group and at least one of the substituents R is a hydrogen atom), was used. Other operations were the same as in Example 1, and a peelable film of Comparative Example 1 was obtained.

[0143] <Comparative Example 2> As the melamine crosslinking agent (D), Nikalac MS-001 (manufactured by Nippon Carbide Industries Co., Ltd., average 5.7-mer, 60 mass%), which is Type IM described below, was used. The other operations were the same as in Example 1, to obtain a release film of Comparative Example 2.

[0144] <Comparative Example 3> Nikalac MX-750 was used in place of the melamine crosslinking agent (D).Other operations were the same as in Example 15, to obtain a release film of Comparative Example 4.

[0145] <Comparative Example 4> Nikalac MS-001 was used instead of the melamine crosslinking agent (D). The other procedures were the same as in Example 15, to obtain a peelable film of Comparative Example 5.

[0146] <Comparative Example 5> The modified acrylic resin (A)-containing solution, the resin (B) different from the modified acrylic resin (A), the melamine crosslinking agent (D), and the acid catalyst (E) were mixed and stirred so that the solid content was 32 parts by mass of the modified acrylic resin (A), 68 parts by mass of the polyester resin, 6 parts by mass of the melamine crosslinking agent, and 0.7 parts by mass of the acid catalyst (E), respectively, to obtain Coating Solution 7 (solid content concentration 4.4% by mass, acid catalyst concentration 0.03% by mass). The other operations were the same as in Example 15, and a peelable film of Comparative Example 5 was obtained.

[0147] [Table 1]

[0148] In Table 1, the symbols for the modified acrylic resin (A) have the following meanings: LA: Lauryl acrylate HEA: 2-hydroxyethyl acrylate IDAA: Isodecyl acrylate STA: Stearyl acrylate

[0149] In Table 1, the amino group substitution type for the melamine compound used as crosslinking agent D is as follows: "Substituent of amino group" described below means a group in which a hydrogen atom in the amino group is substituted, and refers to R in the above formula (IV). The group R is a group that is directly bonded to the nitrogen atom in the amino group. · Type F A melamine compound (a melamine compound represented by general formula (V)) in which all of the substituents R of the three amino groups bonded per structural unit (six substituents R in total for the three amino groups) are methoxymethyl groups. · Type M A melamine compound in which all of the substituents R of the three amino groups bonded per structural unit are either methoxymethyl groups or methylol groups, and at least one of the substituents R is a methylol group. · Type IM A melamine compound in which all of the substituents R of the three amino groups bonded per structural unit are either a methoxymethyl group, a methylol group, or a hydrogen atom, and at least one of the substituents R is a methylol group and at least one of the substituents R is a hydrogen atom.

Claims

1. A peelable film having a surface layer on a substrate layer, the main component forming the surface layer is a resin component, the resin component includes a modified acrylic resin (A) having an alkyl component and a crosslinkable functional group, a resin (B) different from the modified acrylic resin (A), and a crosslinking agent (D); The modified acrylic resin (A) is at least a compound represented by the following general formula (I): 【Chemical 1】 (In the general formula (I), R 1 represents a methyl group or a hydrogen atom, and R 2 represents an alkyl group having 10 to 18 carbon atoms. It contains a constitutional unit represented by The resin (B) is an acrylic resin, The resin (B) has a hydroxy group, The hydroxyl value of the resin (B) is 5 to 500 mgKOH / g, The crosslinking agent (D) is a melamine compound having a structure in which all hydrogen atoms of amino groups are substituted with at least one of an alkoxyalkyl group and an alkanol group, The melamine compound is represented by the following general formula (IV): 【Chemistry 2】 [In general formula (IV), all of the substituents R are alkoxyalkyl groups, and n is a number of 1 or more.] A peelable film represented by the formula:

2. The modified acrylic resin (A) is represented by the following general formula (II): 【Chemistry 3】 [In the general formula (II), R a represents a methyl group or a hydrogen atom, and R b is -CH 2 CH 2 OH, -CH 2 -CHOH-CH 3 , -CH 2 CH 2 CH 2 OH, -CH 2 -CHOH-CH 2 CH 3 , -CH 2 CH 2 -CHOH-CH 3 , or -CH 2 CH 2 CH 2 CH 2 OH.] 2. The peelable film according to claim 1, comprising a structural unit represented by the formula:

3. The weight average molecular weight of the modified acrylic resin (A) is 5×10 4 ~15 x 10 4 3. The peelable film according to claim 1 or 2, wherein

4. The peelable film according to any one of claims 1 to 3, wherein the content of the resin (B) in the surface layer is 2 parts by mass or more, relative to 100 parts by mass of the total of the modified acrylic resin (A) and the resin (B) constituting the surface layer.

5. The peelable film according to any one of claims 1 to 4, wherein the content of the resin (B) in the surface layer is less than 50 parts by mass, relative to 100 parts by mass of the total of the modified acrylic resin (A) and the resin (B) constituting the surface layer.

6. 6. The peelable film according to claim 1, wherein the alkoxyalkyl group has 2 to 5 carbon atoms, and the alkanol group has 1 to 3 carbon atoms.

7. The peelable film according to any one of claims 1 to 6, wherein the resin (B) has a hydroxyl value of 10 to 300 mgKOH / g.

8. A method for producing a peelable film having a surface layer on a substrate layer, comprising: forming the surface layer on the base layer, the main component forming the surface layer is a resin component, the resin component includes a modified acrylic resin (A) having an alkyl component and a crosslinkable functional group, a resin (B) different from the modified acrylic resin (A), and a crosslinking agent (D); The modified acrylic resin (A) is at least a compound represented by the following general formula (I): 【Chemistry 4】 (In the general formula (I), R 1 represents a methyl group or a hydrogen atom, and R 2 represents an alkyl group having 10 to 18 carbon atoms. It contains a constitutional unit represented by The resin (B) is an acrylic resin, The resin (B) has a hydroxy group, The hydroxyl value of the resin (B) is 5 to 500 mgKOH / g, The crosslinking agent (D) is a melamine compound having a structure in which all hydrogen atoms of amino groups are substituted with at least one of an alkoxyalkyl group and an alkanol group, The melamine compound is represented by the following general formula (IV): 【Chemistry 5】 [In general formula (IV), all of the substituents R are alkoxyalkyl groups, and n is a number of 1 or more.] A method for producing a release film represented by the formula:

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