JP7192265B2 - peelable film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a peelable film and a method for producing the same. In particular, the present invention relates to a release film or the like used in the medical and industrial fields, for example, in the process of manufacturing electronic components or electronic substrates, or in the process of manufacturing thermosetting resin members such as fiber-reinforced plastics. More specifically, the present invention provides a release film, release liner or separator film used for surface protection films and adhesive tapes, etc., separators for process (dicing, die bonding, back grinding) tapes used in the manufacture of semiconductor products, and ceramic capacitors. The present invention relates to a peelable film that is particularly useful as a carrier for forming an unbaked sheet during production, a carrier during production of composite materials, a separator film for a protective material, and the like.

Releasable films are used in industrial fields such as manufacturing processes of electronic components and electronic substrates, manufacturing processes of thermosetting resin members such as fiber-reinforced plastics, and medical fields such as poultices and plasters.

Such peelable films include, for example, those used as surface protection films and adhesive tapes, those used as release liners and separator films, semiconductor product manufacturing processes (dicing, die bonding, back grinding, etc.). etc.), a carrier for forming an unfired sheet when manufacturing a ceramic capacitor, a carrier for manufacturing a composite material, and a separator film as a protective material.

Silicone-based release films are excellent in weather resistance, heat resistance, cold resistance, chemical resistance, and electrical insulation, and are widely used as release films. However, when a silicone-based peelable film is used, silicone may transfer (migrate) to an article to which the film is attached (this problem is also referred to as the problem of silicone migration). Therefore, studies have been made to improve the composition of silicone in the silicone release film, minimize the amount of silicone used, or eliminate the use of silicone. For example, Patent Document 1 proposes a release film using a hydroxy group-containing long-chain alkyl polymer.

JP 2015-030795 A

However, the release film described in Patent Document 1 has a large release force and insufficient heat resistance. As an example, a case where the release film is used as a carrier for forming an unfired sheet in manufacturing a ceramic capacitor will be described. In order to produce the unbaked sheet, a coating layer is provided on the release film and dried. If the heat resistance is insufficient, the unbaked sheet may become difficult to peel off unexpectedly from the release film due to the heat of the drying after the drying. Due to such problems, it is difficult to use the release film as a substitute for the silicone-based release film. Therefore, there is still a demand for a release film that has good release properties such as light release force and excellent heat resistance (maintains the above-mentioned good release properties even after being heat-treated).

SUMMARY OF THE INVENTION An object of the present invention is to provide a peelable film that has good peelability, i.e., a light peeling force, and that is excellent in heat resistance.

The present inventors have made extensive studies to solve the above problems. As a result, in a peelable film having a surface layer on a substrate layer, the amount of carbon relative to the content of all elements present at a depth of 5 nm vertically from the outermost surface of the surface layer toward the substrate layer was found. It has been found that a peelable film having a content ratio M _C5 (atomic %) of 98 or more has good peelability (that is, light peeling force) and excellent heat resistance. The present invention has been completed through further studies based on these findings.

That is, the present invention includes the following.
Section 1. A peelable film having a surface layer on a substrate layer,
A peelable film, wherein the carbon content ratio M _C5 (atomic %) to the content of all elements existing at a depth of 5 nm vertically from the outermost surface of the surface layer toward the substrate layer is 98 or more.
Section 2. 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) has at least the following general formula (I):

（前記一般式（Ｉ）において、Ｒ¹は、メチル基又は水素原子を示し、Ｒ²は、炭素数１０～１８のアルキル基を示す。）
で表される構成単位を含む、項１に記載の剥離性フィルム。
項３． 前記表面層中の前記樹脂（Ｂ）の含有量は、前記表面層を構成する前記変性アクリル系樹脂（Ａ）と前記樹脂（Ｂ）の合計を１００質量部として、２質量部以上である、項２に記載の剥離性フィルム。
項４． 前記表面層中の前記樹脂（Ｂ）の含有量は、前記表面層を構成する前記変性アクリル系樹脂（Ａ）と前記樹脂（Ｂ）の合計を１００質量部として、５０質量未満である、項２又は３に記載の剥離性フィルム。
項５． 前記Ｍ_C5と、前記表面層中の最表面から基材層に向けて垂直に深さ４０ｎｍの位置に存在する全元素含有量に対する炭素の含有量比Ｍ_C40（ａｔｏｍｉｃ％）との比率Ｍ_C5／Ｍ_C40が、１．０１≦Ｍ_C5／Ｍ_C40≦１．１０である、項１～４のいずれかに記載の剥離性フィルム。
項６． 前記変性アクリル系樹脂（Ａ）とは異なる樹脂（Ｂ）は、ポリエステル樹脂及びアクリル樹脂からなる群から選ばれた少なくとも１種である、項１～５のいずれか１項に記載の剥離性フィルム。

(In general formula (I) above, R ¹ represents a methyl group or a hydrogen atom, and R ² represents an alkyl group having 10 to 18 carbon atoms.)
Item 1. The peelable film according to Item 1, comprising a structural unit represented by.
Item 3. The content of the resin (B) in the surface layer is 2 parts by mass or more, with the total of the modified acrylic resin (A) and the resin (B) constituting the surface layer being 100 parts by mass. Item 3. The peelable film according to item 2.
Section 4. The content of the resin (B) in the surface layer is less than 50 parts by mass when the total of the modified acrylic resin (A) and the resin (B) constituting the surface layer is 100 parts by mass. 4. The peelable film according to 2 or 3.
Item 5. The ratio M _C5 between the M _C5 and the carbon content ratio M _C40 (atomic%) with respect to the total element content existing at a depth of 40 nm vertically from the outermost surface of the surface layer toward the base layer Item 5. The peelable film according to any one of Items 1 to 4, wherein /M _C40 is 1.01≦M _C5 /M _C40 ≦1.10.
Item 6. Item 6. The peelable film according to any one of Items 1 to 5, 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. .

ADVANTAGE OF THE INVENTION According to this invention, while having favorable peelability that peeling force is light, the peelable film which is excellent also in heat resistance can be provided. Therefore, it is particularly suitable as a release film or the like used in the manufacturing process of electronic components or electronic substrates, or in the manufacturing process of thermosetting resin members such as fiber-reinforced plastics.

The peelable film according to the present embodiment is a peelable film having a surface layer on a substrate layer, and is present at a depth of 5 nm vertically from the outermost surface of the surface layer toward the substrate layer. It is characterized in that the carbon content ratio M _C5 (atomic %) to the total element content is 98 or more.

Since the peelable film according to the present embodiment has such a configuration,
(1) Good peelability at room temperature (that is, when an object (adherend) is attached to the surface layer of the peelable film and then peeled off between the surface layer and the object, the Along with the effect of having a low peeling force (also called a light peeling force) while having a peeling force between the surface layer and the object,
(2) Excellent heat resistance, that is, the above-mentioned good peelability can be maintained even after exposure to high temperatures (for example, about 90 to 160 ° C.).
It also has the effect of

In particular, the above effect (1) is as good as the peelability of ordinary silicone-based peelable films. Since the peelable film of the present invention has the effects of (1) to (2) above, the peelable film can be used in the manufacturing process of electronic parts or electronic substrates (for example, for forming an unfired sheet when manufacturing a ceramic capacitor). use as a carrier), the manufacturing process of thermosetting resin members such as fiber-reinforced plastics, and the medical field such as poultices and adhesive plasters. In addition to the above properties, the peelable film according to the present embodiment has a small difference in peel strength before and after being heated to a high temperature of about 90 to 160 ° C., and / or a large residual adhesion rate, which will be described later. , can be used more preferably in each of the above fields.

The peelable film according to this embodiment will be described in detail below. In the present specification, "-" in a numerical range means above and below. That is, the notation α to β means from α to β, or from β to α, and includes α and β as a range. In addition, "(meth)acryl" means "acryl or methacryl", and other similar terms have the same meaning.

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

[Base material layer]
As the substrate layer, a thin sheet such as paper, non-woven fabric, metal foil, etc. can be used in addition to a layer containing a resin (eg, resin film). When the substrate layer is a layer containing a resin, for example, the resin includes polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene terephthalate, polypropylene naphthalate, polytrimethylene terephthalate, and polybutylene terephthalate. Polyolefin resins such as polyethylene and polypropylene; Polystyrene resins; Acetyl cellulose resins such as triacetyl cellulose; Acrylic resins such as polymethyl methacrylate; Polyurethane resins; Polycarbonate resins; It is a layer containing

When the substrate layer is a layer containing a resin, it may contain only one type of the above resins, or may contain two or more types in combination. The substrate layer in the peelable film of the present embodiment is a layer containing at least one selected from the group consisting of polyester-based resins, polyolefin-based resins, and polystyrene-based resins as a main component, from the viewpoint of processability of the surface layer. From the viewpoint of adhesion with the surface layer (when another layer is interposed between the surface layer and the base layer, adhesion with the other layer), polyester resins and polyolefins It is more preferable that the layer contains at least one selected from the group consisting of system resins as a main component.

Here, in the present invention and this specification, the main component means a component containing 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, and still more preferably It is 90% by mass or more, and particularly preferably 95% by mass or more. In addition, the ratio of the main component may be 100% by mass.

The base material layer may contain an additive like the surface layer described later. The types and components of the additive are the same as those explained in the item of the surface layer described later, and the explanation is omitted here.

The substrate layer may be a layer composed of any of a non-stretched film, a uniaxially stretched film, and a biaxially stretched film. From the viewpoint of workability, transparency and dimensional stability, the substrate layer is preferably a layer composed of a biaxially stretched film.

The thickness of the substrate layer is preferably 15 μm or more, more preferably 20 μm or more, from the viewpoint of workability. The thickness of the substrate layer is preferably 125 μm or less, more preferably 50 μm or less, from the viewpoint of handling properties when using the product. The thickness of the base layer is measured using a micrometer (JIS B-7502) in accordance with JIS C-2151, specifically by the method described in Examples.

For the purpose of enhancing the adhesion between the base layer and the surface layer described below, one or both sides of the base layer may be surface-treated, if desired. Examples of the surface treatment include roughening treatment such as sandblasting or solvent treatment, corona discharge treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, and surface oxidation treatment such as ozone/ultraviolet irradiation treatment. .

[Surface layer]
The peelable film of this embodiment has a surface layer on the substrate layer. The surface layer is a layer for imparting releasability to the releasable film. The surface layer may be formed on the base material layer via each layer such as an adhesive layer between the base material layer and the surface layer so that the main surface of the surface layer is in contact with the main surface of the base material layer. A surface layer is preferably formed.

In the peelable film according to the present embodiment, the carbon content ratio M _C5 (atomic%) with respect to the total element content existing at a depth of 5 nm vertically from the outermost surface of the surface layer toward the base layer is It is 98 or more (more specifically, 98.0 or more) (that is, 98≦M _C5 , and it can also be said that 98.0≦M _C5 ). If the above M _C5 is less than 98 atomic % (that is, M _C5 <98), the alkyl chains are not segregated on the outermost surface side of the surface layer, and there is a risk that sufficient releasability cannot be imparted. Although the upper limit of M _C5 is not limited, it is preferably M _C5 ≦99 (more specifically, M _C5 ≦99.0, and M _C5 is 99 or less, further 99.0 or less). Means for adjusting M _C5 include adjustment of the ratio of the modified acrylic resin (A) component described later, adjustment of the thickness of the layer, and the like.

<Relationship between _{MC5 and MC40 >}
The content ratio of carbon to the total element content present at a position of 5 nm in depth from the outermost surface of the surface layer to the base layer is defined as _MC5 (atomic%), and the outermost surface of the surface layer Let M _C40 (atomic%) be the content ratio of carbon to the total content of elements existing at a depth of 40 nm vertically from the substrate layer to the substrate layer, and the relationship between M _C5 and M _C40 is 1.01 ≤ It is preferred that M _C5 /M _C40 ≤1.10. When M _C5 /M _C40 is 1.01≦M _C5 /M _C40 ≦1.10, it indicates that more alkyl chains are segregated on the outermost surface side of the surface layer, and sufficient releasability is obtained.

In this embodiment, the relationship between M _C5 and M _C40 is preferably 1.03≦M _C5 /M _C40 ≦1.10, more preferably 1.04≦M _C5 /M _C40 ≦1.10. 04≦M _C5 /M _C40 ≦1.09 is more preferable. Each preferred aspect of the relationship between M _C5 and M _C40 is found from the viewpoint of good peelability.

Here, the technical significance of M _C5 /M _C40 will be explained. M _C5 /M _C40 indicates the degree of segregation of chains of alkyl groups on the outermost surface. A large M _C5 /M _C40 value indicates that the alkyl chains are more segregated to the outermost surface. Here, when 1.01≦M _C5 /M _C40 ≦1.10 in the surface layer, the alkyl chains segregate on the outermost surface of the surface layer, so that groups and components other than the alkyl chains do not interfere with the base layer or the base layer. It is believed to interact with other layers adjacent to the substrate layer. Due to such a mechanism, the peelable film of the present embodiment has the effect of good peelability due to the alkyl chain, and after being exposed to a high temperature, it has a good effect on the object attached to the surface layer. It is presumed that it also has the effect of maintaining the releasability.

Means for adjusting the values of M _C5 , M _C40 , and M _C5 /M _C40 include the type and content of the alkyl acrylate component in the modified acrylic resin (A) described later; the resin (B) described later; and its content; and the like. As an example, in the film according to the present embodiment, when the surface layer contains a modified acrylic resin (A) described later and a resin (B) described later, and the resin (B) is a polyester resin, the resin (B ), the M _C5 value tends to decrease and the M _C5 /M _C40 value tends to increase.

In the present invention and this specification, the values of M _C5 and M _C40 are each measured by the methods described in Examples, and the value of M _C5 /M _C40 is calculated from the above measured values.

The content ratio M _C5 (atomic%) of carbon to the total element content existing at a depth of 5 nm from the outermost surface of the surface layer of the peelable film toward the base layer was measured by Ar ion sputtering. This is a value obtained by performing XPS analysis while scraping the layer from the outermost surface side. Using an X-ray electron spectroscopy (XPS) measuring instrument ESCA LAB250 (manufactured by Thermo VG Scientific) as a measuring instrument, measurement mode: monochromator, X-ray source: Al, measurement area: 500 μmφ, measurement element: carbon (C). do. The sputtering conditions are irradiation ions: argon (Ar), current value: 2.5 (μA), voltage: 120 (V), sputtering rate: 0.1 (nm/sec).

The carbon content ratio M _C40 (atomic%) to the total element content existing at a depth of 40 nm vertically from the outermost surface of the surface layer of the peelable film toward the base layer is the same as M _C5 . These are values measured by performing XPS analysis while scraping the surface layer from the outermost surface side by Ar ion sputtering. In addition, regarding the measurement conditions of M _C40 (measuring instrument, measurement mode, X-ray source, measurement area, measurement element, etc.) and sputtering conditions (irradiated ions, current value, voltage, sputtering rate, etc.), the above M _C5 measurement Same as condition.

A 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). is preferred. That is, the surface layer comprises a modified acrylic resin (A) having an alkyl component and a crosslinkable functional group as resin components, a resin (B) different from the modified acrylic resin (A), and a crosslinking agent (D). It is preferably composed of a cured product of the resin composition containing the resin composition. In the peelable film of the present embodiment, 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, and the modified acrylic When the resin (B) different from the resin (A) and the cross-linking agent (D) are included, it is easier to obtain a peelable film having good peelability with light peeling force and excellent heat resistance. The modified acrylic resin (A), the resin (B) different from the modified acrylic resin (A), and the cross-linking agent (D) are described in detail below.

<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 with respect to the main chain acrylic resin. The modified acrylic resin (A) contains at least a structural unit represented by the following general formula (I) (formed by a monomer a described later).

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.

In general formula (I), the alkyl group R ² has 10 to 18 carbon atoms. When 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 increases and the peeling force becomes too high, resulting in poor peeling performance as a peelable film. Since the modified acrylic resin (A) has a long-chain alkyl group with 10 to 18 carbon atoms, the release performance is excellent. In order to improve the release performance, R ² in formula (I) is preferably a straight-chain alkyl group. The number of carbon atoms in R ² is preferably 12-18, more preferably 12-14. R ² is even more preferably a straight-chain alkyl group having 12 to 18 carbon atoms, particularly preferably a straight-chain alkyl group having 12 to 14 carbon atoms.

In the modified acrylic resin (A), the crosslinkable functional group (reactive functional group) includes, for example, 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, a hydrolyzable silyl group, and the like can be mentioned. The number of crosslinkable functional groups may be one, or two or more. Moreover, one type of crosslinkable functional group may be contained alone, or two or more types may be contained.

The modified acrylic resin (A) contains, as a monomer, at least a monomer a (in one molecule, a carbon-carbon unsaturated double bond and , an acrylic monomer having an alkyl group having 10 to 18 carbon atoms). The modified acrylic resin (A) includes, together with the monomer a, a monomer b described later (a monomer having a carbon-carbon unsaturated double bond and a crosslinkable functional group in one molecule), a monomer Polymer c (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 (monomers a, b , c, which is copolymerizable with at least one of monomers a, b, and c). It may be a copolymer obtained by polymerization. In particular, a copolymer obtained by copolymerizing at least the monomer a and the monomer b is preferable as the modified acrylic resin (A).

[monomer a]
Examples of the monomer a include (meth)acrylic acid esters in which the ester portion is a long-chain alkyl group having 10 to 18 carbon atoms. Specifically, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate (also known as lauryl (meth) acrylate), tridecyl (meth) acrylate, tetradecyl (meth) acrylate (also known as myristyl (meth) acrylate) ), pentadecyl (meth)acrylate, hexadecyl (meth)acrylate (also referred to as palmityl (meth)acrylate), stearyl (meth)acrylate, and the like.

The content ratio of the structural unit derived from the monomer a in the modified acrylic resin (A) is, from the viewpoint of lightening the peeling force and further improving the heat resistance, the content of the structural unit contained in the modified acrylic resin (A). With a total of 100 parts by mass, preferably about 50 to 99.99 parts by mass, more preferably about 70 to 99.9 parts by mass, more preferably about 85 to 99.8 parts by mass, still more preferably 85 to 99.5 parts by mass part by mass. Only one kind of the monomer a may be used, or two or more kinds thereof may be mixed and used.

[monomer b]
Monomer b is a monomer having a carbon-carbon unsaturated double bond and a crosslinkable functional group in one molecule. Since the monomer b has a crosslinkable functional group, it preferably bonds with a resin (B) different from the modified acrylic resin (A) via a crosslinker (D) described later, The release force can be reduced and the heat resistance can be improved.

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, hydrolyzable silyl groups, and the like. are mentioned. Only one type of monomer b may be used, or two or more types may be mixed and used. Moreover, in the monomer b, the number of crosslinkable functional groups may be one, or two or more. Moreover, one type of crosslinkable functional group may be contained alone, or two or more types may be contained.

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. Moreover, a carboxyl group-containing (meth)acrylate can also be mentioned as the monomer b having a carboxyl group. Carboxyl group-containing (meth)acrylates include 1,4-di(meth)acryloxyethylpyromellitic acid, 4-(meth)acryloxyethyltrimellitic acid, 2-(meth)acryloyloxybenzoic acid and the like. .

Examples of the isocyano group-containing monomer b include (meth)acryloyloxyethyl isocyanate, (meth)acryloyloxypropyl isocyanate, and hydroxy (meth)acrylates (e.g., 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc.) with polyisocyanate (eg, toluene diisocyanate, isophorone diisocyanate, etc.).

Examples of the epoxy group-containing monomer b include glycidyl methacrylate, glycidyl cinnamate, glycidyl allyl ether, glycidyl vinyl ether, vinylcyclohexane monoepoxide and 1,3-butadiene monoepoxide.

Examples of the monomer b having an N-methylol group or an N-alkoxymethyl group include N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-propoxymethyl ( meth)acrylamide, (meth)acrylamide having N-monoalkoxymethyl group such as N-butoxymethyl(meth)acrylamide, N,N-dimethylol(meth)acrylamide, N,N-di(methoxymethyl)(meth)acrylamide , N,N-di(ethoxymethyl)(meth)acrylamide, N,N-di(propoxymethyl)(meth)acrylamide, N,N-dialkoxy such as N,N-di(butoxymethyl)(meth)acrylamide A (meth)acrylamide having a methyl group can be mentioned.

As the monomer b having a hydroxy group, hydroxy group-containing (meth)acrylates are mainly mentioned. Hydroxy group-containing (meth)acrylates 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, polytetramethylene glycol mono(meth)acrylate and the like. In addition, hydroxystyrene etc. are mentioned as the monomer b which has a hydroxy group.

Monomer b having an amino group includes primary or secondary amino group-containing (meth)acrylates. Primary or secondary amino group-containing (meth)acrylates include aminoethyl (meth)acrylate, ethylaminoethyl (meth)acrylate, aminopropyl (meth)acrylate, ethylaminopropyl (meth)acrylate and the like. .

Examples of the thiol group-containing monomer b include thiol group-containing (meth)acrylates. Thiol group-containing (meth)acrylates include 2-(methylthio)ethyl methacrylate.

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

Monomer b is preferably 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 at least selected from the group consisting of hydroxystyrene 1, more preferably 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl ( It is at least one selected from the group consisting of meth)acrylate and 4-hydroxybutyl (meth)acrylate.

monomer b is 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 general formula (I), and at least It contains a structural unit represented by the following general formula (II).

In general formula (II), R ^a represents a methyl group or a hydrogen atom, R ^b represents -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.

When the modified acrylic resin (A) contains a structural unit derived from the monomer b, the content of the structural unit derived from the monomer b in the modified acrylic resin (A) reduces the peel force, From the viewpoint of further improving heat resistance, it is preferably about 0.01 to 20 parts by mass, preferably about 0.1 to 10 parts by mass, with the total of the structural units contained in the modified acrylic resin (A) being 100 parts by mass. More preferably, it is more preferably about 0.2 to 5 parts by mass, more preferably about 0.5 to 3 parts by mass, and about 0.8 to 1.5 parts by mass. Especially preferred. When the modified acrylic resin (A) contains not only structural units derived from the monomer a but also structural units derived from the monomer b, even if the primary structure is a random copolymer, It may be a block copolymer.

[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. The monomer c can be used, for example, to adjust the concentration of alkyl groups contained in the surface layer, and as a result, the release force can be reduced and the heat resistance can be improved.

(Meth)acrylic acid derivatives are suitable as the monomer c. As the (meth)acrylic acid derivative, a monomer from which a structural unit represented by the following general formula (III) is derived is preferable.

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

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, ) acrylates, (meth)acrylates, (meth)acrylonitrile and the like. Only one type of the monomer c may be used, or two or more types may be mixed and used.

When the modified acrylic resin (A) contains structural units derived from the monomer c, the content of the structural units derived from the monomer c in the modified acrylic resin (A) reduces the peel force, From the viewpoint of further improving heat resistance, it is preferably about 0.01 to 20 parts by mass, preferably 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). It is more preferable to be a degree.

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

Specific examples of monomer d include (i′) aromatic vinyl monomers, (ii′) olefinic hydrocarbon monomers, (iii′) vinyl ester monomers, (iv′) vinyl Examples thereof include halide monomers, (v') vinyl ether monomers, and the like. Only one type of the monomer d may be used, or two or more types may be mixed and used. Monomer d can be used, for example, to adjust the concentration of various functional groups contained in the surface layer, and can reduce the peeling force of the peelable film and improve heat resistance.

Examples of aromatic vinyl monomers include styrene, methylstyrene, ethylstyrene, chlorostyrene, and styrenes in which some hydrogen atoms are substituted with fluorine (for example, monofluoromethylstyrene, difluoromethylstyrene, trifluoromethylstyrene, etc.). is mentioned.

Examples of olefinic hydrocarbon monomers include ethylene, propylene, butadiene, isobutylene, isoprene, 1,4-pentadiene and the like.

Examples of vinyl ester monomers include vinyl acetate.

Vinyl halide monomers include vinyl chloride, vinylidene chloride, monofluoroethylene, difluoroethylene, trifluoroethylene and the like.

A vinyl methyl ether etc. are mentioned as a vinyl ether monomer.

When the modified acrylic resin (A) contains a structural unit derived from the monomer d, the content of the structural unit derived from the monomer d in the modified acrylic resin (A) reduces the peel force, From the viewpoint of further improving heat resistance, it is preferably about 0.01 to 20 parts by mass, preferably 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). It is more preferable to be a degree.

From the viewpoint of lightening the peeling force and improving the heat resistance, the modified acrylic resin (A) preferably has a weight average molecular weight of 5×10 ⁴ to 15×10 ⁴ , more preferably 6×10 ⁴ to 15×10 4 . It is 14×10 ⁴ , more preferably 8×10 ⁴ to 12×10 ⁴ .

The content of the modified acrylic resin (A) in the surface layer is not particularly limited. ) is 100 parts by mass, preferably more than 50 parts by mass, more preferably 52 parts by mass or more, and even more preferably 55 parts by mass or more. In addition, the content of the modified acrylic resin (A) in the surface layer is preferably 98 parts by mass or less with respect to a total of 100 parts by mass of the resin (A) and the resin (B) constituting the surface layer. It is more preferably 97 parts by mass or less, further 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 60 parts by mass or less. It is particularly preferable to have Here, the fact that the content of the resin (A) exceeds 50 parts by mass when the total of the resin (A) and the resin (B) is 100 parts by mass means that the mass part of the resin (A) is M _A is synonymous with 1<M _A /M _B where M _B is the mass part of the resin (B). Similarly, when the content of the resin (A) is 52 parts by mass or more, 1.083 ≤ M _A /M _B , and when it is 55 parts by mass or more, 1.222 ≤ M _A / Being M _B and being 97 parts by mass or less are synonymous with M _A /M _B ≦32.333. When the content of the resin (A) is more than 50 parts by mass when the total of the resin (A) and the resin (B) is 100 parts by mass, the peeling force can be reduced and the heat resistance can be improved. , The difference in peel strength after heating and before heating is very small, and the residual adhesion rate is also excellent.

From the viewpoint of lightening the peeling force and further improving heat resistance, the content (%) of the modified acrylic resin (A) in the surface layer is preferably 50% by mass or more, 60% by mass or more, 70 mass % or more, 80 mass % or more, 90 mass % or more, etc. are mentioned.

As a method for obtaining the modified acrylic resin (A), the aforementioned monomer a and, if necessary, monomer b, monomer c, and monomer d are subjected to radical polymerization, anionic polymerization, cationic polymerization, or the like. It can be obtained by polymerizing by a known polymerization method.

An initiator may be used during the polymerization. An azo compound, an organic peroxide, or the like can be used as the initiator. Among them, azo compounds are preferable, and azobisisobutyronitrile (AIBN) is more preferable, in terms of polymerization yield and ease of molecular weight control. The amount of the polymerizing agent used is preferably 0.01 to 3 parts by mass, with the total of the structural units contained in the modified acrylic resin (A) being 100 parts by mass, from the viewpoint of ease of yield and molecular weight control, and 0.05 parts by mass. ~2 parts by mass is preferable, and 0.1 to 1.5 parts by mass is more preferable.

Further, the modified acrylic resin (A) has an alkyl group with respect to a polymer obtained by polymerizing at least a monomer b (a monomer having a carbon-carbon unsaturated double bond and a crosslinkable functional group). may be obtained by graft polymerization. That is, a polymer having a structure in which an alkyl group is graft-polymerized to some or all of the crosslinkable functional groups of the structural units led by the monomer b (hereinafter referred to as a modified acrylic resin (A′)). , can be used alone or mixed with the modified acrylic resin (A) in the same manner as the modified acrylic resin (A).

In the modified acrylic resin (A'), the number of carbon atoms in the graft-polymerized alkyl group is preferably about 10-18, more preferably about 12-14. A method for introducing an alkyl group by graft polymerization is not particularly limited, and includes known introduction methods.

Also in the modified acrylic resin (A'), the same monomer b as exemplified for the modified acrylic resin (A) can be preferably used. The details of the monomer b are as described above.

The modified acrylic resin (A') may be a copolymer obtained by copolymerizing the monomer b and at least one of the monomer c and the monomer d.

Also in the modified acrylic resin (A'), the monomer c and the monomer d exemplified for the modified acrylic resin (A) can be preferably used. The details of monomer c and monomer d are as described above.

<Resin (B)>
The resin component forming the surface layer preferably contains a resin (B) different from the modified acrylic resin (A) together with the modified acrylic resin (A).

By containing the resin (B) in the surface layer, the alkyl groups of the modified acrylic resin (A) are easily segregated on the surface by utilizing the difference in compatibility with the modified acrylic resin (A), resulting in As a result, the peeling force is reduced and the heat resistance is improved.

The resin (B) is not particularly limited, but preferably includes at least one selected from the group consisting of polyester resins and acrylic resins. Among them, a polyester resin is more preferable as the resin (B). Moreover, as the polyester resin and the acrylic resin, it is possible to appropriately select and use from known polyester resins and acrylic resins. For example, as a polyester resin, (i) a resin obtained by a condensation reaction of a polyhydric alcohol and a polybasic acid, which is a condensate of a dibasic acid and a dihydric alcohol, or modified with a non-drying oil fatty acid, etc. and (ii) a convertible polyester resin which is a condensate of a dibasic acid and a trihydric or higher alcohol. In this embodiment, the polyester resin (B) may be used alone or in combination of two or more.

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

Specific examples of polybasic acids used as raw materials for polyester resins include aromatic polybasic acids, aliphatic saturated polybasic acids, aliphatic unsaturated polybasic acids, polybasic acids produced by Diels-Alder reaction, and the like. is mentioned. Examples of aromatic polybasic acids include phthalic anhydride, terephthalic acid, isophthalic acid, and trimetic anhydride. Examples of saturated aliphatic polybasic acids include succinic acid, adipic acid, and sebacic acid. Examples of aliphatic unsaturated polybasic acids include maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic anhydride and the like. Examples of polybasic acids produced by the Diels-Alder reaction include cyclopentadiene-maleic anhydride adducts, terpene-maleic anhydride adducts, rosin-maleic anhydride adducts, and the like. These polybasic acids may be used singly or in combination of two or more.

Specific examples of non-drying oil fatty acids as modifiers include octylic acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linoleic acid, eleostearic acid, ricinoleic acid, dehydrated ricinoleic acid, Alternatively, coconut oil, linseed oil, paulownia oil, castor oil, dehydrated castor oil, soybean oil, safflower oil, fatty acids thereof, and the like can be used. These may be used individually by 1 type, and may be used in combination of 2 or more types. Also, as the polyester resin, one type may be used alone, or two or more types may be used in combination.

Examples of acrylic resins include homopolymers of (meth)acrylic acid esters, copolymers of two or more different (meth)acrylic acid ester monomers, or mixtures of (meth)acrylic acid esters and other monomers. A copolymer is mentioned. As the (meth)acrylic resin, more specifically, polymethyl (meth)acrylate, polyethyl (meth)acrylate, polypropyl (meth)acrylate, polybutyl (meth)acrylate, (meth)acrylic acid Methyl - butyl (meth) acrylate copolymer, ethyl (meth) acrylate - butyl (meth) acrylate copolymer, ethylene - methyl (meth) acrylate copolymer, styrene - methyl (meth) acrylate copolymer Examples thereof include (meth)acrylic acid esters such as polymers. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

The resin (B) different from the modified acrylic resin (A) preferably has a reactive functional group in order to react with the cross-linking agent (D) described below. In particular, the reactive functional group is preferably at least one selected from the group consisting of carboxyl groups and hydroxy groups. 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 more preferably 10 to 100 mgKOH/g. 10 to 40 mgKOH/g is particularly preferred. When the hydroxyl value of the resin (B) is within each of the preferred ranges described above, the density of the network structure crosslinked by the crosslinking agent (D) described later becomes appropriate, resulting in a lighter release force. In particular, when the resin (B) is a polyester resin having a hydroxyl value within the above preferred ranges, the above tendency is strong.

The number average molecular weight of resin (B) is preferably about 500 to 30,000, more preferably about 1,000 to 20,000. Since the resin (B) has a number average molecular weight within the above range, the network structure tends to be dense when the surface layer is crosslinked with the crosslinking agent (D), and the modified acrylic resin having an alkyl component and a crosslinkable functional group Segregation of the system resin (A) to the peeled surface is likely to occur.

The resin (B) in the surface layer preferably has a glass transition temperature (Tg) of 55° C. or higher. Further, the glass transition temperature is more preferably 58°C or higher. When the glass transition temperature of the resin (B) in the surface layer is within the above preferred ranges, the peeling force becomes lighter and the heat resistance is improved. In particular, when the resin (B) is a polyester resin having a glass transition temperature within the above preferred range, the above tendency is strong. The glass transition temperature of the resin (B) in the surface layer is preferably 100° C. or lower, more preferably 90° C. or lower, still more preferably 80° C. or lower, and particularly preferably 70° C. or lower.

The content of the resin (B) in the surface layer is not limited, but from the viewpoint of lightening the peeling force and improving heat resistance, the total amount of the resin (A) and the resin (B) constituting the surface layer is As 100 parts by mass, it is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more. It is particularly preferably at least 40 parts by mass, particularly preferably at least 40 parts by mass. From the same point of view, the total of the resin (A) and the resin (B) constituting the surface layer is preferably less than 50 parts by mass, more preferably 48 parts by mass or less, and 45 parts by mass or less, when the total is 100 parts by mass. is more preferred. Here, the fact that the content of the resin (B) is less than 50 parts by mass when the total of the resin (A) and the resin (B) is 100 parts by mass means that the mass part of the resin (B) is M _A is synonymous with 1<M _A /M _B where M _B is the mass part of the resin (B). Similarly, if the content of the resin (B) is 48 parts by mass or less, 1.083 ≤ M _A /M _B , and if it is 45 parts by mass or less, 1.222 ≤ M _A / Being M _B and being 3 parts by mass or more are synonymous with M _A /M _B ≦32.333, respectively. When the content of the resin (B) is less than 50 parts by mass when the total of the resin (A) and the resin (B) is 100 parts by mass, the peeling force can be reduced and the heat resistance can be improved. , The difference in peel strength after heating and before heating is very small, and the residual adhesion rate is also excellent.

<Crosslinking agent (D)>
The resin component forming the surface layer preferably contains a cross-linking agent (D) together with the modified acrylic resin (A) and resin (B). The cross-linking agent (D) has a function of cross-linking the modified acrylic resins (A) together, the resins (B) together, or the modified acrylic resins (A) and the resin (B). The cross-linking agent (D) can be used alone or in combination of two or more.

In the present embodiment, the cross-linking agent (D) is not limited, but for example, polyfunctional amino compounds, isocyanate compounds (including monoisocyanates, diisocyanates, polyfunctional isocyanates, etc.), polyfunctional epoxy compounds, polyfunctional metals Compounds or dialdehydes are preferred. In the present embodiment, the cross-linking agent (D) is preferably a polyfunctional amino compound, more preferably a melamine compound. The melamine compound is particularly preferably 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. It can be said that the particularly preferable melamine compound has at least one selected from the group consisting of alkoxyalkyl groups and alkanol groups as a substituent of the amino group. Further, the particularly preferred melamine compound has a structural unit in which three amino groups are bonded to a triazine ring, and in the present embodiment, a total of six substituents bonded to the three amino groups are alkoxy It can be said that it contains only at least one selected from the group consisting of an alkyl group and an alkanol group, and does not have other substituents such as hydrogen atoms.

More specifically, the particularly preferred melamine compound can be represented by the following general formula (IV).

In general formula (IV), the total of six substituents R possessed by the three amino groups bonded to the triazine ring are groups in which the hydrogen atoms of the amino groups are substituted. Each of the six substituents R is independently an alkoxyalkyl group or an alkanol group. In addition, n is a number of 1 or more and indicates the average n amount of the melamine compound.

An alkoxyalkyl group means, for example, a C1-6 alkyloxy C1-6 alkyl group such as a methoxymethyl group and a 1-ethoxyethyl group. The alkanol group includes, for example, a hydroxymethyl group, a 2-hydroxyethyl group, a 3-hydroxypropyl group, a 2-hydroxy-n-propyl group (--CH.sub.2--CHOH--CH.sub.3) _, a ₂ -hydroxy-1- It means a group such as a methylethyl group in which a hydrogen atom on a terminal methyl group of a linear or branched alkyl group is substituted with a hydroxy group. Here, C1-6 means having 1 to 6 carbon atoms.

In the present embodiment, from the viewpoint of lightening the peeling force and further improving heat resistance, the particularly preferable melamine compound has the general formula (IV), wherein at least one of the six substituents R is an alkoxyalkyl groups, more preferably three or more are alkoxyalkyl groups, and most preferably all six are alkoxyalkyl groups. In general formula (IV), among the six substituents R, the number of alkanol groups is preferably 5 or less, more preferably 3 or less, and still more preferably 0. That is, in the melamine compound, all of the three substituents R of the amino groups (substituents R of the six amino groups) bonded to each structural unit are either a methoxymethyl group or a methylol group, and A melamine compound in which at least one of the substituents R is a methylol group is a preferred embodiment.

In the particularly preferred melamine compound, the alkoxyalkyl group preferably has 2 to 5 carbon atoms, more preferably 2 carbon atoms. Preferred specific examples of the alkoxyalkyl group include a propoxymethyl group, an ethoxymethyl group, a methoxymethyl group, etc. Among these, a methoxymethyl group is particularly preferred. The number of carbon atoms in the alkanol group is preferably 1-3, more preferably 1. Preferred specific examples of the alkanol group include a propanol group (3-hydroxypropyl group), an ethylol group (2-hydroxyethyl group), a methylol group (hydroxymethyl group), etc. Among these, the methylol group is particularly preferred.

The average n amount of the melamine compound is preferably about 1.0 to 3.0, more preferably about 1.1 to 2.0, still more preferably about 1.2 to 1.5. Only one type of the crosslinking agent (D) may be used, or two or more types may be mixed and used.

In the present embodiment, the melamine compound is particularly preferably a compound represented by general formula (V) from the viewpoint of lightening the peeling force and improving heat resistance.

［ここでＭｅはメチル基を示す。］

[Here, Me represents a methyl group. ]

In general formula (V), the average n amount of the melamine compound is within the above range.

In this embodiment, the resin component forming the surface layer may contain a cross-linking agent other than the particularly preferred melamine compound as the cross-linking agent (D).
The cross-linking agent contained in the resin component is preferably only the melamine compound which is particularly preferred as the cross-linking agent (D).

Examples of other cross-linking agents include, but are not limited to, polyfunctional amino compounds different from the particularly preferred melamine compounds, isocyanate compounds (including monoisocyanates, diisocyanates, polyfunctional isocyanates, etc.), polyfunctional Examples include epoxy compounds, polyfunctional metal compounds, dialdehydes, and the like.

Examples of polyfunctional amino compounds different from the particularly preferred melamine compounds include urea compounds, benzoguanamine compounds, and diamines. Urea compounds include alkylated urea compounds (for example, Nikalac MX-270 manufactured by Nippon Carbide Industry Co., Ltd.). Benzoguanamine compounds include benzoguanamine, methylated benzoguanamine, and the like. Diamines include ethylenediamine, tetramethylenediamine, hexamethylenediamine, N,N'-diphenylethylenediamine, p-xylylenediamine and the like.

Polyfunctional isocyanate compounds include, for example, 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, TMP adduct XDI and the like.

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

Examples of polyfunctional metal compounds include aluminum chelate compounds, titanium chelate compounds, and trimethoxyaluminum. Examples of aluminum chelate compounds include aluminum trisacetylacetonate and aluminum ethylacetoacetate.diisopropylate. Titanium chelate compounds include titanium tetraacetylacetonate, titanium acetylacetonate, titanium octylene glycolate, tetraisopropoxytitanium, tetramethoxytitanium, and the like.

In the surface layer, the content of the cross-linking agent (D) is the modified acrylic resin (A) and a resin (B ) 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, based on a total of 100 parts by mass. Also, from the same point of view, it is preferably 30 parts by mass or less with respect to a total of 100 parts by mass of the modified acrylic resin (A) and the resin (B) different from the modified acrylic resin (A), and 20 parts by mass. It is more preferably 10 parts by mass or less, more preferably 10 parts by mass or less.

<Other ingredients>
[Additive]
Each of the surface layer and the substrate layer may further contain at least one additive, in addition to the resin component that is the main component, if necessary. Additives include, for example, acid catalysts, antioxidants, chlorine absorbers, stabilizers such as ultraviolet absorbers, lubricants, plasticizers, flame retardants, antistatic agents, colorants, antiblocking agents, and the like. . 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 either the substrate layer or the surface layer, or may be contained in all layers of the substrate layer and the surface layer. Also, the base layer and the surface layer may contain the same or different additives.

The "acid catalyst" improves the denseness of the coating film through a cross-linking reaction, and can suppress the precipitation of oligomers. As an acid catalyst for this cross-linking reaction, an acid catalyst such as p-toluenesulfonic acid, methyl p-toluenesulfonate, ethyl p-toluenesulfonate, n-butyl p-toluenesulfonate, benzenesulfonic acid, sulfonic acid, methanesulfonic acid, etc. is preferably used. Available. Acid catalysts can be used singly or in combination of two or more. 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 more preferably 0.5 parts by mass with respect to 100 parts by mass of the resin component constituting the surface layer. It is more preferable that it is above. The amount of the acid catalyst used is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and 1.5 parts by mass or less with respect to 100 parts by mass of the resin component constituting the surface layer. It is even more preferable to have

The antioxidant is not particularly limited, but for example, 2,6-di-tert-butyl-p-cresol (common name: BHT), phenol, hindered amine, phosphite, lactone and tocopherol Antioxidants are included. Specifically, 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.

Examples of the "chlorine absorbent" include, but are not particularly limited to, metal soaps such as calcium stearate.

Examples of the "ultraviolet absorber" include, but are not limited to, benzotriazole (such as Tinuvin328 manufactured by BASF), benzophenone (such as Cysorb UV-531 manufactured by Cytec) and hydroxybenzoate (UV-CHEK-AM-340 manufactured by Ferro), and the like. are mentioned.

Examples of the "plasticizer" include, but are not limited to, citric acid esters, dibutyl phthalate, polyethylene glycols, propylene glycols, glycerin and the like.

Examples of the "flame retardant" include, but are not particularly limited to, halogen compounds, aluminum hydroxide, magnesium hydroxide, phosphates, borates, antimony oxides, and the like.

Examples of the "antistatic agent" include, but are not particularly limited to, glycerin monoesters (glycerin monostearate, etc.), ethoxylated secondary amines, and the like.

The "colorant" includes various colored dyes, colored pigments, and fluorescent dyes.

The "anti-blocking agent" is added to prevent blocking and is not particularly limited as long as it does not exhibit an effect as a nucleating agent. Examples of antiblocking agents include inorganic particles such as silica, alumina, (synthetic) zeolite, calcium carbonate, kaolin, talc, mica, zinc oxide, magnesium oxide, quartz, magnesium carbonate, pallium sulfate and titanium dioxide, and polystyrene particles. , polyacrylic particles, polymethyl methacrylate (PMMA) particles, crosslinked polyethylene particles, polyester particles, polyamide particles, polycarbonate particles, polyether particles, polyether sulfone particles, polyetherimide particles, polyphenylene sulfide particles, polyether ether ketone Particles, polyamideimide particles, (crosslinked) melamine resin particles, benzoguanamine resin particles, urea resin particles, amino resin particles, furan resin particles, epoxy resin particles, phenol resin particles, unsaturated polyester resin particles, vinyl ester resin particles, diallyl phthalate Organic particles such as resin particles, polyimide resin particles, fatty acid amide particles, and fatty acid glycerin ester compound particles are included. The anti-blocking agent is preferably particles having a particle size of 0.1 μm to 10 μm, and PMMA and silica particles are more preferable because they are excellent in anti-blocking property and slipperiness. For example, by including such particles in the substrate layer described above, the slipperiness of the front and back surfaces of the substrate layer is improved, and blocking can be suppressed.

Moreover, in the present embodiment, it is preferable that the surface layer does not substantially contain a silicone compound so as not to adversely affect electrical parts and the like. Note that "substantially free of silicone compound" means that the amount of silicone compound is preferably 500 μg/g or less, more preferably 100 μg/g or less.

The thickness of the surface layer is preferably 0.01 µm or more, more preferably 0.05 µm or more, still more preferably 0.1 µm or more, and particularly preferably 0.18 µm, from the viewpoint of easily improving the peelability. be. 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 type" manufactured by Hitachi High-Technologies Corporation), and specifically measured by the method described in Examples.

[Method for preparing surface layer]
The surface layer can be formed by laminating a resin component forming the surface layer on the substrate layer. As a preferred embodiment of the surface layer preparation method, a modified acrylic resin (A), a resin (B) different from the modified acrylic resin (A), a cross-linking agent (D), and, if necessary, other components etc. and at least one solvent is applied onto the base material layer, the resin (A) and the resin (B) are crosslinked, and obtained by the coating It is formed by removing the solvent from the coated layer.

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 viewpoints of easy handling of the coating solution and easy production efficiency of the peelable film. Only one type of solvent may be used, or two or more types may be mixed and used.

The concentration of components other than the solvent in the coating liquid (so-called concentration of solid components remaining in the surface layer after removing the solvent, for example, modified acrylic resin (A), modified acrylic resin (A) The total concentration of the different resin (B), the cross-linking agent (D), and other components to be blended as necessary) is not limited, but from the viewpoint of the stability and coatability of the coating solution , It is preferably 1 to 24% by mass, more preferably 1 to 19% by mass, more preferably 2 to 14% by mass, with respect to the total amount of the coating liquid, 2 to 10% by mass Especially preferred. The coating method is not particularly limited, and examples thereof include methods using a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, a curtain coater, or a printing machine. be done.

A method for cross-linking the resin (A) and the resin (B) in the coating layer includes heating the coating layer in the presence of the cross-linking agent (D). For example, a method of applying hot air to the coating layer to heat it, and a method of heating the coating layer with electromagnetic waves such as infrared rays can be used.
A method for removing the solvent from the coating layer is not particularly limited as long as the solvent can be volatilized. In addition, removing the solvent does not mean only removing the solvent completely, but also includes removing the solvent to the extent that a layer is formed. Examples of the method for removing the solvent include a method of blowing the coating layer to dry it, a method of drying the coating layer by heating, and the like.
From the viewpoint of facilitating both removal of the solvent and acceleration of the cross-linking reaction, the drying temperature or heating temperature by wind 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, even more preferably 20 to 50 seconds.

The peelable film of the present embodiment may or may not be stretched, but the surface layer is preferably unstretched from the viewpoint of easily obtaining good light peelability.

[Roughening of peelable film surface]
In the present embodiment, the surface of the peelable film may be provided with a fine surface roughness that improves winding aptitude within a range that does not interfere with lamination or the like when used as a peelable film. As a method for providing fine unevenness on the peelable film surface, an embossing method, an etching method, etc., and various known roughening methods can be employed.

The peelable film of the present embodiment has a very light (very low) T-peel peel strength. From the viewpoint of easily increasing the adhesion of the peelable film to the adherend, the T-peel peel strength of the peelable film of the present embodiment is preferably 0.01 N/25 mm or more, more preferably 0.02 N/25 mm or more. More preferably, it is 0.05 N/25 mm or more. In addition, the T-peel peel force of the peelable film of the present embodiment is preferably 0.40 N/25 mm or less, more preferably 0.30 N/25 mm or less, and still more preferably, from the viewpoint of easily improving the peelability. is 0.25 N/25 mm or less, particularly preferably 0.22 N/25 mm or less. The T-peel peel strength of the peelable film is measured by the following method. The preferred ranges of the T-peel release force after heating of the peelable film of the present embodiment after heating are the same as the respective preferred ranges of the T-peel release force before heating.

[T-peel release force]
In a room temperature (25 ° C.) environment, a 50 mm wide x 200 mm long polyester adhesive tape (NO. It is attached by reciprocating the roller twice. The obtained film is heat-treated at 160° C. for 90 seconds, and then allowed to stand still for 20 hours in an environment of 70° C. temperature and 50% humidity. Next, in a room temperature environment (25 ° C.), a sample cut into a width of 25 mm from the obtained film is used as a measurement sample, and a tensile tester (for example, Minebea Co., Ltd. universal tensile tester Technograph TGI-1kN) is used. T-peel separation is performed at a speed of 1000 mm/min, and the peel force at that time is measured. Let the value measured in this way be T-shaped peel strength (pre-heating T-shaped peel strength).

In addition, the T-peel release force after heating of the release film of the present embodiment is preferably less different from the T-peel release force before heating. The value of peel strength) is preferably -0.20 to +0.20, more preferably -0.10 to +0.10, further preferably -0.08 to +0.05, and -0.04 to +0. 02 is particularly preferred. The post-heating T-peel peel strength of the peelable film is measured by the following method.

[T-peel release force after heating]
In a room temperature (25 ° C.) environment, a 50 mm wide x 200 mm long polyester adhesive tape (Nitto Denko No. 31B tape, acrylic adhesive) is applied to the surface layer side of the peelable film, and a 2 kg roller is applied. is reciprocated twice to obtain a pre-processed pasted product. Then, the patch is heat-treated at 160° C. for 90 seconds. Note that a hot air dryer is used in 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 is placed on the patch so as to give a load of 5 KPa, and the patch is allowed 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 into a width of 25 mm from the obtained film is used as a measurement sample, and a tensile tester (for example, Minebea Co., Ltd. universal tensile tester Technograph TGI-1kN) is used. T-peel separation is performed at a speed of 1000 mm/min, and the peel force at that time is measured. Let the value measured in this way be T-peel exfoliation force after a heating.

[Thickness of peelable film]
The thickness of the peelable film is preferably 18 μm or more, more preferably 20 μm or more, from the viewpoint of handling properties as a peelable film. The thickness of the peelable film is preferably 100 μm or less, more preferably 50 μm or less, from the viewpoint of handling properties as a peelable film. The thickness of the peelable film of this embodiment is measured according to JIS C-2151 using a micrometer (JIS B-7502).

The peelable film of the present embodiment has good peelability and maintains the above-mentioned good peelability even after being heat-treated, so it is excellent as a film for peeling. The release film of the present embodiment can be widely used in the industrial and medical fields. (dicing, die bonding, back grinding) tape separator film, unfired sheet forming carrier in ceramic capacitor production, carrier in composite material production, protective material separator film, etc. The peelable film of the present embodiment includes tapes or sheets; resin members such as electric devices, electronic devices, wearable devices, medical devices, and building materials; intermediate members manufactured in the above semiconductor product manufacturing process; , motors, connectors, switches, etc.); the object when used as the carrier; the dry film resist; When the adherend described above has an adhesive layer (for example, a solvent-based, emulsion-based, or hot-melt pressure-sensitive adhesive layer), the surface layer of the peelable film of the present embodiment and the adhesive layer The peelable film of the present embodiment may be used by being attached to an adherend so that the two layers are attached to each other. A method for attaching the peelable film of the present embodiment to an object is not particularly limited. The peelable film of the present embodiment may be attached to an object by cutting the peelable film appropriately according to the area to be attached, for example, and the peelable film of the present embodiment and the object to which it is attached may be attached. When each of them is wound in a roll shape, they may be pasted together by roll-to-roll.

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. However, the present invention is not limited to the examples. In addition, unless otherwise specified, parts and % indicate "mass parts" and "mass%" respectively.

[Measurement method and evaluation method]
Various measurement methods and evaluation methods in Examples and Comparative Examples are as follows.

[Thickness of surface layer]
After cutting out the sample, the surface of the sample was coated with Os and embedded in resin. Next, after trimming and surfacing with an ultramicrotome equipped with a diamond knife and preparation of an ultra-thin section, observation with a transmission electron microscope (TEM) was performed.
Section preparation device: Ultramicrotome (LEICA EM UC7 manufactured by Leica Corporation)
Knife; ULTRADRY manufactured by DIATOME
Observation device: TEM (HT7700 type manufactured by Hitachi High-Technologies Corporation)
Accelerating voltage: 100 kV
Photo magnification: ×300,000

[Thickness of Base Layer and Peelable Film]
The thickness of the peelable film and base layer was measured using a micrometer (JIS B-7502) according to JIS C-2151.

[X-ray electron spectroscopy (XPS) analysis]
XPS analysis is performed while scraping the surface layer from the outermost surface side by Ar ion sputtering, and the content of all elements present at a depth of 5 nm vertically from the surface layer of the peelable film toward the base layer The content ratio M _c5 (atomic %) of carbon present in was measured under the following conditions.
Measuring device: X-ray electron spectroscopy (XPS) measuring device ESCA LAB250 (manufactured by Thermo VG scientific)
Measurement mode: monochromator, X-ray source: Al, measurement area: 500 μmφ
Element to be measured: Carbon (C)
Sputtering conditions were as follows.
Irradiation ions: argon (Ar), current value: 2.5 (μA), voltage: 120 (V), sputtering rate: 0.1 (nm/sec)

[XPS depth direction analysis]
XPS analysis is performed while scraping the surface layer from the outermost surface side by Ar ion sputtering, and the content of carbon with respect to the total element content present at a position of 40 nm in depth from the outermost surface in the surface layer to the base material layer. The quantitative ratio M _C40 (atomic %) was measured. The measurement conditions for XPS are the same as those for M _C5 described above.

[T-peel release force]
A polyester adhesive tape (No. 31B tape manufactured by Nitto Denko Corporation, acrylic adhesive) having a width of 50 mm and a length of 200 mm was pasted on the film surface of the surface layer side of the peelable film by reciprocating a 2 kg roller twice. , to obtain a patch before treatment.
Then, a weight was placed on the patch so as to give a load of 5 KPa, and the patch was allowed to stand in an environment of 70° C. and 50% humidity for 20 hours.
Next, in a room temperature environment, a sample cut into a width of 25 mm from each processed patch was used as each measurement sample, and a peel tester (manufactured by Minebea Co., Ltd. Universal tensile tester Technograph TGI-1kN) was used. Then, a T-peel peel test was performed at a speed of 1000 mm/min, and the peel force at that time was measured. Each measurement was performed three times, and the average value was defined as the T-peel release force (pre-heating T-peel release force) of each peelable film. Table 1 shows the results.

[T-shaped peel strength after heating (heat resistance evaluation)]
A polyester adhesive tape (No. 31B tape manufactured by Nitto Denko Corporation, acrylic adhesive) having a width of 50 mm and a length of 200 mm was pasted on the film surface of the surface layer side of the peelable film by reciprocating a 2 kg roller twice. , to obtain a patch before treatment.
Then, the patch was heat-treated at 160° C. for 90 seconds. Note that a hot air dryer was used in 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.
Then, a weight was placed on the patch so as to give a load of 5 KPa, and the patch was allowed to stand in an environment of 70° C. and 50% humidity for 20 hours. Next, the post-heating T-peel release force was obtained by the same method as the measurement method and calculation method of the T-peel release force in the above [T-peel release force]. Table 1 shows the results.

[Residual adhesion rate evaluation]
In the above [T-shaped peel strength], the polyester adhesive tape used when measuring the T-shaped peel strength on the surface layer side of each peelable film (polyester adhesive tape after peeling during the measurement) , respectively, was attached by reciprocating a 2 kg roller twice on a stainless steel plate (SUS plate). Next, a T-peel peeling test was performed at a rate of 1000 mm/min on the pasted article having the stainless steel plate obtained by pasting, and the peeling force (X) at that time was measured.
On the other hand, in the above [T-shaped peel strength], instead of the film surface on the surface layer side of the peelable film, a Teflon (registered trademark) sheet (Chuko Kasei Kogyo Co., Ltd. skived tape MSF-100 thickness 100 μm) A T-peel peeling test was performed in the same manner except that the polyester adhesive tape was attached to the surface, and the polyester adhesive tape after peeling by the peeling test was placed on a stainless steel plate (SUS plate) with a 2 kg roller. It was pasted by reciprocating twice. Next, a T-peel peeling test was performed at a rate of 1000 mm/min on the pasted article having the stainless steel plate obtained by pasting, and the peel strength (Y) at that time was measured.
Next, the residual adhesion rate was determined by the following formula. It is evaluated that the components of the surface layer of the peelable film are more likely to migrate to the polyester adhesive tape as the residual adhesion rate is smaller. When the residual adhesion rate is 100%, the components of the surface layer of the peelable film do not migrate to the polyester adhesive tape to the same extent as the components on the surface of the Teflon (registered trademark) sheet do not migrate to the polyester adhesive tape. means that
Table 1 shows the results.
Residual adhesion rate (%) = (X) / (Y) x 100
The residual adhesion rate is preferably 84% or higher, more preferably 87% or higher, still more preferably 90% or higher, even more preferably 93% or higher, and particularly preferably 97% or higher. The residual adhesion rate may be 100%.

<Example 1>
A 1-liter flask equipped with a stirrer, a nitrogen inlet tube, a thermometer and a cooling tube was charged with 99 parts by mass of lauryl acrylate (LA) as monomer a and 1 part by mass of 2-hydroxyethyl acrylate (HEA) as monomer b. , 0.2 parts by mass of azobisisobutyronitrile (AIBN), 100 parts by mass of toluene, and 100 parts by mass of ethyl acetate were added as polymerization initiators. Next, in the flask, a polymerization reaction is carried out at 80 ° C. for 2 hours under a nitrogen stream, and 0.2 parts by mass of azobisisobutyronitrile is added and polymerized for 2 hours, and the modified acrylic resin ( A) A containing solution (solid content: 30% by mass) was obtained. The weight average molecular weight of the obtained modified acrylic resin (A) was 10.5×10 ⁴ .
As a resin (B) different from the modified acrylic resin (A), a polyester resin α (Vylon (registered trademark) M802 (manufactured by Toyobo Co., Ltd., number average molecular weight (Mn): 3 × 10 ³ , hydroxyl value: 37 mg KOH/ g solid content 70% by mass, Tg = 60°C), all of the amino group substituents R (that is, six amino group substituents R) bonded to three per structural unit as the melamine cross-linking agent (D), Nikalac (registered trademark) MS-11 (manufactured by Nippon Carbide Industry Co., Ltd., average 1.0%), which is either a methoxymethyl group or a methylol group, and is a melamine compound in which one or more of the substituents R are methylol groups. 60% by mass of octamer) and Drier 900 (50% by mass of p-toluenesulfonic acid manufactured by Hitachi Chemical Co., Ltd.) as an acid catalyst (E) were prepared.
Next, a solution containing modified acrylic resin (A), a resin (B) different from modified acrylic resin (A), and a melamine cross-linking agent (D) were added to toluene: methyl ethyl ketone (MEK) = 30: 70 (mass ratio ) and stirred, and then mixed with the acid catalyst (E) and stirred. Here, the solution containing the modified acrylic resin (A), the resin (B) different from the modified acrylic resin (A), the melamine cross-linking agent (D), and the acid catalyst (E) are each converted to a solid content of 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 crosslinking agent, and 1.2 parts by mass of the acid catalyst (E) were mixed and stirred. As a result, a coating liquid 1 having a solid content concentration of 4.4% by mass and an acid catalyst concentration of 0.05% by mass was obtained.
Next, a 38 μm-thick biaxially oriented polyethylene terephthalate film (biaxially oriented PET film, “E5100” manufactured by Toyobo Co., Ltd.) was prepared as a substrate layer.
Then, using a Meyer bar (manufactured by Yasuda Seiki Seisakusho Co., Ltd., shaft diameter: 6.35 mmφ, ROD No. 4), the coating liquid 1 is applied on the base material layer, and 150 in an explosion-proof dryer. C. for 60 seconds. As a result, a peelable film of Example 1 having a substrate layer and a surface layer (thickness of surface layer: 0.2 μm) was obtained.

<Example 2>
Regarding the solution containing the modified acrylic resin (A), the resin (B), the melamine cross-linking agent (D), and the acid catalyst (E), 75 parts by mass of the modified acrylic resin (A) in terms of solid content, 25 parts by mass of the polyester resin (B), 6 parts by mass of the melamine cross-linking agent (D), and 1.1 parts by mass of the acid catalyst (E) were mixed and stirred to prepare a coating solution 2 (solid concentration: 4.5 parts by mass). 4% by weight and acid catalyst concentration of 0.05% by weight). Other operations were performed in the same manner as in Example 1 to obtain a peelable film of Example 2.

<Example 3>
Regarding the modified acrylic resin (A)-containing solution, the resin (B), the melamine cross-linking agent (D), and the acid catalyst (E), 95 parts by mass of the modified acrylic resin (A), the above 5 parts by mass of the polyester resin (B), 6 parts by mass of the melamine cross-linking agent (D), and 1.2 parts by mass of the acid catalyst (E) were mixed and stirred to obtain a coating solution 3 (solid concentration: 4.5 parts by mass). 4% by weight and acid catalyst concentration of 0.05% by weight). Other operations were performed in the same manner as in Example 1 to obtain a peelable film of Example 3.

<Example 4>
Acrylic resin (Acrydic (registered trademark) WMG-521, manufactured by DIC Corporation, Tg = 30 ° C., acid value: 6.5 mg KOH / g in place of polyester resin (Vylon (registered trademark) M802) as resin (B) A peelable film of Example 4 was obtained in the same manner as in Example 1, except that the solid content was 60% by mass).

<Comparative Example 1>
Regarding the solution containing the modified acrylic resin (A), the resin (B), the melamine cross-linking agent (D), and the acid catalyst (E), 32 parts by mass of the modified acrylic resin (A) in terms of solid content, 68 parts by mass of the polyester resin (B), 6 parts by mass of the melamine cross-linking agent (D), and 1.2 parts by mass of the acid catalyst (E) were mixed and stirred to prepare a coating solution 4 (solid concentration: 4.5 parts by mass). 4% by weight and acid catalyst concentration of 0.05% by weight). Other operations were performed in the same manner as in Example 1 to obtain a peelable film of Comparative Example 1.

<Comparative Example 2>
The solution containing the modified acrylic resin (A), the resin (B), the melamine cross-linking agent (D), and the acid catalyst (E) are each converted to a solid content of 10 parts by mass of the modified acrylic resin (A), 90 parts by mass of the polyester resin (B), 6 parts by mass of the melamine cross-linking agent (D), and 1.2 parts by mass of the acid catalyst (E) were mixed and stirred to obtain a coating liquid 5 (solid concentration: 4.5 parts by mass). 4% by weight and acid catalyst concentration of 0.05% by weight). Other operations were performed in the same manner as in Example 1 to obtain a peelable film of Comparative Example 2.

<Comparative Example 3>
Regarding the modified acrylic resin (A)-containing solution, the resin (B), the melamine cross-linking agent (D), and the acid catalyst (E), the modified acrylic resin (A) is 0 parts by mass in terms of solid content, and the 100 parts by mass of the polyester resin (B), 6 parts by mass of the melamine cross-linking agent (D), and 1.2 parts by mass of the acid catalyst (E) were mixed and stirred to obtain a coating liquid 6 (solid concentration: 4.5 parts by mass). 4% by weight and acid catalyst concentration of 0.05% by weight). Other operations were performed in the same manner as in Example 1 to obtain a peelable film of Comparative Example 3.

<Comparative Example 4>
Regarding the modified acrylic resin (A)-containing solution, the resin (B), the melamine cross-linking agent (D), and the acid catalyst (E), 46 parts by mass of the modified acrylic resin (A) in terms of solid content, 54 parts by mass of the polyester resin (B), 6 parts by mass of the melamine cross-linking agent (D), and 1.2 parts by mass of the acid catalyst (E) were mixed and stirred to prepare a coating solution 7 (solid concentration: 4.5 parts by mass). 4% by weight and acid catalyst concentration of 0.05% by weight). Other operations were the same as in Example 1 to obtain a peelable film of Comparative Example 4.

Of the films obtained in Examples 1-4 and Comparative Examples 1-4,
(i) M _C5 /M _C40 (where M _C5 is the ratio of the content of carbon to the content of all elements present at a depth of 5 nm vertically from the outermost surface of the surface layer toward the substrate layer. M _C5 is also simply referred to as the carbon element ratio at a depth of 5 nm, and M _C40 is the carbon content of all elements present at a depth of 40 nm vertically from the outermost surface of the surface layer toward the substrate layer. shows the ratio of the content of M _C40 is also simply referred to as the carbon element ratio at a depth of 40 nm.)
(ii) M _A /M _B (where M _A is the mass part of the modified acrylic resin (A) containing the structural unit represented by the structural formula (I), contained in the surface layer; M _B is the mass part of the polyester resin (B) contained in the surface layer.Both M _A and M _B are in terms of solid content.)
(iii) T-peel release force,
(iv) Heat resistance evaluation (T-peel peel strength after heating)
(v) Peel force difference (T-peel peel force after heating - T-peel peel force before heating)
(vi) residual adhesion rate,
The results are shown in Table 1. In addition, the above (v) peel force difference is calculated by the difference between the above (iv) and the above (iii).

As described above, the peelable films of Examples 1 to 4 had a low T-peel strength (before heating) and a low T-peel strength after heating. Furthermore, it was found that the peelable films of Examples 1 to 4 had very little difference in peeling strength after heating and before heating, and were also excellent in residual adhesiveness. Therefore, the film according to the present embodiment, including Examples 1 to 4, is particularly a release film used in the manufacturing process of electronic components or electronic substrates, or the manufacturing process of thermosetting resin members such as fiber-reinforced plastics. etc. can be suitably used.

Claims (5)

A peelable film having a surface layer on a substrate layer,
The content ratio M _C5 (atomic%) of carbon to the content of all elements existing at a depth of 5 nm vertically from the outermost surface of the surface layer toward the base layer is 98 or more ,
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) has at least the following general formula (I):

(In general formula (I) above, R ¹ represents a methyl group or a hydrogen atom, and R ² represents an alkyl group having 10 to 18 carbon atoms.)
contains a structural unit represented by
The resin (B) is at least one selected from the group consisting of polyester resins and acrylic resins,
The content of the resin (B) in the surface layer is 2 parts by mass or more and 45 parts by mass, with the total of the modified acrylic resin (A) and the resin (B) constituting the surface layer being 100 parts by mass. A peelable film that is: A peelable film having a surface layer on a substrate layer,
The content ratio M _C5 (atomic%) of carbon to the content of all elements existing at a depth of 5 nm vertically from the outermost surface of the surface layer toward the base layer is 98 or more,
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) has at least the following general formula (I):

(In general formula (I) above, R ¹ represents a methyl group or a hydrogen atom, and R ² represents an alkyl group having 10 to 18 carbon atoms.)
contains a structural unit represented by
The release film , wherein the resin (B) is at least one selected from the group consisting of polyester resins and acrylic resins, and the polyester resin has a hydroxyl value of 10 to 40 mgKOH/g . The content of the resin (B) in the surface layer is 2 parts by mass or more, with the total of the modified acrylic resin (A) and the resin (B) constituting the surface layer being 100 parts by mass. The peelable film according to claim 2. The content of the resin (B) in the surface layer is less than 50 parts by mass when the total of the modified acrylic resin (A) and the resin (B) constituting the surface layer is 100 parts by mass. The peelable film according to claim 2 or 3. The ratio M _C5 between the M _C5 and the carbon content ratio M _C40 (atomic%) with respect to the total element content existing at a depth of 40 nm vertically from the outermost surface of the surface layer toward the base layer /M _C40 is 1.01≦M _C5 /M _C40 ≦1.10.