JP2023085061A - Peelable sheet - Google Patents

Abstract

To provide a peelable sheet that has excellent peelability and is less prone to warpage.SOLUTION: A peelable sheet includes a substrate, and a peeling agent layer provided on at least one side of the substrate. The peeling agent layer is composed of a peeling agent composition that contains a silicone-modified acrylic resin, a methylated melamine resin, and an epoxy group-containing component.SELECTED DRAWING: None

Description

The present invention relates to release sheets.

In general, a release sheet (sometimes referred to as a "process film") has a substrate such as paper, plastic film, polyethylene-laminated paper, etc., and a release agent layer provided on the substrate. The release agent layer is formed by applying a release agent composition onto a substrate and drying or curing the resulting coating film.

The release sheet is widely used as, for example, a protective sheet for the adhesive layer of an adhesive sheet or the like, a process film for producing a resin sheet, a process film for forming a ceramic green sheet, a process film for producing synthetic leather, etc. (e.g. , see Patent Document 1).

The release sheet will be peeled off from the object after the purpose of protecting the object or manufacturing the object is completed. At this time, peelability is required so that the film can be easily peeled without requiring excessive force.

JP 2019-171617 A

By the way, during production of the release sheet, the release sheet may be warped as the coating film of the release agent composition is dried and cured. If such warping occurs, when the release sheet is used as a protective sheet, the release sheet does not adhere sufficiently to the object to be protected, and unintended peeling easily occurs. Moreover, when a release sheet is used as a process film, the warp of the release sheet is reflected in the object formed on the release sheet.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a release sheet that exhibits excellent releasability and suppresses the occurrence of warping.

In order to achieve the above object, the first aspect of the present invention is a release sheet comprising a substrate and a release agent layer provided on at least one side of the substrate, wherein the release agent layer is A release sheet characterized by being formed from a release agent composition containing a silicone-modified acrylic resin, a methylated melamine resin, and an epoxy group-containing component having an epoxy group (Invention 1).

The release sheet according to the above invention (Invention 1) exhibits excellent release properties and suppresses the occurrence of warping because the release agent layer is formed from the above-described release agent composition.

In the above invention (invention 1), the release agent composition preferably contains a filler (invention 2).

In the above invention (invention), the release agent composition preferably contains polyorganosiloxane (invention 3).

In the above invention (invention), the release agent composition preferably contains an acid catalyst (invention 4).

The release sheet according to the present invention has excellent releasability and suppresses the occurrence of warping.

Embodiments of the present invention will be described below.
A release sheet according to one embodiment of the present invention comprises a substrate and a release agent layer provided on one side of the substrate.

In the release sheet according to the present embodiment, the release agent layer is formed from a release agent composition containing a silicone-modified acrylic resin, a methylated melamine resin, and an epoxy group-containing component having an epoxy group. It's becoming

In the release sheet according to the present embodiment, since the release agent layer is formed from the above release agent composition, it is possible to satisfactorily suppress the occurrence of warpage while achieving excellent release properties. In particular, since the release agent layer is mainly composed of a silicone-modified acrylic resin and a methylated melamine resin, the release agent layer has the desired surface free energy and is sufficiently hardened to achieve excellent release properties. In addition, since the epoxy group-containing component is used, shrinkage during formation of the release agent layer is suppressed, making it difficult for the release sheet to warp.

1. Substrate The substrate in the release sheet according to the present embodiment is not particularly limited, and any substrate can be appropriately selected and used from conventionally known substrates. As such a substrate, for example, a plastic film, paper, or the like can be used. Examples of the plastic film include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene and polymethylpentene, and plastic films such as polycarbonate and polyvinyl acetate. These plastic films may be a single layer or a multilayer of two or more layers of the same or different types. Among these, a polyester film is preferable, and a polyethylene terephthalate film is particularly preferable. Polyethylene terephthalate film is less likely to generate dust during processing, use, etc., and thus can effectively prevent coating failures due to dust, etc., for example. Examples of the paper include fine paper, glassine paper, impregnated paper, coated paper, and the like.

In addition, for the purpose of improving adhesion to the release agent layer provided on the surface of the base material, one or both sides of the base material may optionally be subjected to a surface treatment such as an oxidation method or roughening method, or a primer treatment. can be done. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, and ultraviolet irradiation treatment. A thermal spraying method and the like can be mentioned. These surface treatment methods are appropriately selected according to the type of substrate, but generally corona discharge treatment is preferably used from the viewpoint of effectiveness and operability.

The thickness of the substrate is preferably 10 μm or more, particularly preferably 15 μm or more, and more preferably 20 μm or more. Also, the thickness is preferably 300 μm or less, particularly preferably 200 μm or less, further preferably 125 μm or less.

2. Release agent layer 2-1. Components As described above, the release agent layer of the present embodiment is formed from a release agent composition containing a silicone-modified acrylic resin, a methylated melamine resin, and an epoxy group-containing component having an epoxy group. The release agent composition may contain other components, and it is particularly preferable to contain polyorganosiloxane from the viewpoint of improving the peelability. In addition, the release agent composition contains an acid catalyst from the viewpoint of facilitating the formation of a well-cured release agent layer by promoting the reaction between the methylated melamine resins and between the methylated melamine resin and other components. is also preferred. Furthermore, it is also preferable to contain a filler from the viewpoint of imparting desired performance such as imparting matte properties by forming surface unevenness.

(1) Silicone-modified acrylic resin The silicone-modified acrylic resin in the present embodiment is not particularly limited as long as it is an acrylic resin modified with silicone. For example, it is obtained by modifying an acrylic resin with a silicone modifier. It's okay. Examples of the method of modifying an acrylic resin with a silicone modifier include a method of reacting an acrylic resin having a functional group with a silicone modifier having a functional group. The above acrylic resin having a functional group is an acrylic resin having a functional group capable of reacting with the terminal functional group of the silicone modifier. Moreover, the silicone modifier having a functional group is a silicone modifier having a terminal functional group capable of reacting with the functional group of the acrylic resin.

Examples of monomers constituting acrylic resins include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, glycidyl (meth)acrylate, 2 -hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate and the like. These may be used individually by 1 type, and may use 2 or more types together. An acrylic resin can be obtained by polymerizing these monomers by a known method. In this specification, "(meth)acrylic acid" is a concept including both "acrylic acid" and "methacrylic acid".

Examples of the silicone modifier include organopolysiloxane having an organic group such as dimethylpolysiloxane. Examples of the organic group include phenyl group, methyl group, ethyl group, isopropyl group, hexyl group, cyclohexyl group, vinyl group and the like. These may be used individually by 1 type, and may use 2 or more types together.

Examples of the above functional groups in acrylic resins and silicone modifiers include hydroxy, amino, carboxyl, thiol, isocyanate, epoxy, hydrosilyl, ethynyl, ammonium, amide, imino, and alkoxysilyl groups. groups, ether groups, sulfonic acid groups, nitrile groups, and the like.

Examples of the reaction between the functional group of the acrylic resin and the functional group of the silicone modifier include an active hydrogen group such as a hydroxy group, a primary amino group, a secondary amino group, a carboxyl group, and a thiol group, and an isocyanate group or reaction with an epoxy group; esterification reaction between a hydroxy group and a carboxy group; and hydrosilylation reaction between a hydrosilyl group and an ethynyl group.

The silicone-modified acrylic resin can also be obtained by polymerizing a mixture of an acrylic resin monomer and a silicone modifier having an acrylate functional group.

Moreover, the silicone-modified acrylic resin itself may have a functional group. That is, the silicone-modified acrylic resin may have a functional group in addition to the above functional groups used for the reaction between the acrylic resin and the silicone modifier. The functional group may be a functional group that can be used for the reaction between the acrylic resin and the silicone modifier but remains without being used in the reaction, or a functional group that does not contribute to the reaction. There may be. Examples of functional groups possessed by silicone-modified acrylic resins include reactive functional groups such as hydroxy groups, carboxy groups, and mercapto groups. Among them, hydroxy groups, which can efficiently react with methylated melamine resins, are preferred. The functional group possessed by the silicone-modified acrylic resin may be of one type or of plural types. Moreover, the functional groups possessed by the silicone-modified acrylic resin may be present at either the terminal or the side chain of the silicone-modified acrylic resin, or may be present at both the terminal and the side chain.

Some commercially available silicone-modified acrylic resins contain a melamine resin or the like as a curing agent for curing the silicone-modified acrylic resin. When using such a commercial product, the melamine resin or the like blended as a curing agent in the commercial product is treated as the methylated melamine resin according to the present embodiment, and the remaining net content is the silicone-modified resin according to the present embodiment. It can be treated as an acrylic resin.

Examples of commercially available products containing silicone-modified acrylic resin and methylated melamine resin include "X-62-9088" and "X-62-9089" manufactured by Shin-Etsu Chemical Co., Ltd., and "X-62-9089" manufactured by Showa Denko Materials. "TA31-291F" and the like.

The amount of silicone modification of the silicone-modified acrylic resin according to the present embodiment is preferably 0.01 mmol/g or more, particularly preferably 0.03 mmol/g or more, further preferably 0.1 mmol/g or more. is preferred. The amount of silicone modification is preferably 10 mmol/g or less, particularly preferably 5 mmol/g or less, and further preferably 1 mmol/g or less. When the amount of silicone modification is within the above range, excellent releasability can be easily exhibited. The amount of silicone modification is the amount (mmol) of silyl groups per 1 g of the solid content of the silicone-modified acrylic resin.

In the present embodiment, the silicone-modified amount of the silicone-modified acrylic resin may be adjusted using two or more silicone-modified acrylic resins (A).

The content of the silicone-modified acrylic resin in the release agent composition is preferably 20% by mass or more, particularly preferably 30% by mass or more, further preferably 40% by mass or more. Also, the content is preferably 80% by mass or less, particularly preferably 70% by mass or less, and further preferably 60% by mass or less. When the content of the silicone-modified acrylic resin is within these ranges, the release sheet according to the present embodiment can easily exhibit desired release properties.

(2) Methylated Melamine Resin The methylated melamine resin in the present embodiment is not particularly limited as long as it is a methylated melamine resin. As used herein, the term "melamine resin" means an aggregate of one type of melamine compound, or a mixture containing multiple types of melamine compounds and/or polynuclear compounds formed by condensation of the melamine compounds. do.

The melamine resin that is the base of the methylated melamine resin specifically contains a melamine compound represented by the following general formula (a), or a polynuclear compound obtained by condensing two or more of the melamine compounds. preferable.

In formula (a), X preferably represents —H, —CH ₂ —OH, or —CH ₂ —OR, and R preferably represents an alkyl group having 1 to 8 carbon atoms. The number of carbon atoms is preferably 1 to 6, particularly preferably 1 to 3. Examples of alkyl groups having 1 to 8 carbon atoms include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group and the like, with methyl group being particularly preferred. In the methylated melamine resin of this embodiment, at least one X is --CH ₂ --OR and at least one R is a methyl group.

Note that melamine compounds generally include full ether type compounds in which all Xs are —CH ₂ —OR, imino compounds in which at least one X is —CH ₂ —OH and at least one X is H. Methylol forms, absent methylol forms where at least one X is —CH ₂ —OH and H and where X is present, and where X is present where at least one X is H and —CH ₂ —OH There is a type such as an imino type that does not. The methylated melamine resin according to the present embodiment may be based on any of these types of melamine compounds, but in particular, from the viewpoint of easily exhibiting the desired peelability, full-ether type methylated melamine resin is preferred.

The weight average molecular weight of the methylated melamine resin in the present embodiment is preferably 150 or more, particularly preferably 300 or more, further preferably 500 or more. The weight average molecular weight is preferably 10,000 or less, particularly preferably 5,000 or less, and further preferably 4,000 or less. When the weight-average molecular weight is 150 or more, the reaction rate between the methylated melamine resin and between the methylated melamine resin and other components is stabilized, and a smoother release surface can be formed. Further, when the weight average molecular weight is 10,000 or less, the viscosity of the release agent composition is moderately low, and the coating liquid of the release agent composition can be easily applied onto the substrate.

The content of the methylated melamine resin in the release agent composition is preferably 20% by mass or more, particularly preferably 30% by mass or more, further preferably 40% by mass or more. Also, the content is preferably 80% by mass or less, particularly preferably 70% by mass or less, and further preferably 60% by mass or less. When the content of the methylated melamine resin is within these ranges, the release sheet according to the present embodiment can easily exhibit desired release properties.

(3) Epoxy Group-Containing Component The epoxy group-containing component in the present embodiment is not particularly limited as long as it has an epoxy group, and it is particularly preferable to use an epoxy resin. As used herein, the term "epoxy resin" refers to a curable epoxy resin, that is, an uncured epoxy resin.

Known epoxy resins can be used, for example, polyfunctional epoxy resins, biphenyl compounds, bisphenol A diglycidyl ether and hydrogenated products thereof, o-cresol novolak type epoxy resins, dicyclopentadiene type epoxy resins, and biphenyl type epoxy resins. Bifunctional or more functional epoxy compounds such as epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenylene skeleton type epoxy resin, and the like are included. These may be used alone or in combination of two or more.

The epoxy equivalent weight (gram equivalent: g/eq) of the epoxy group-containing component is preferably 50 or more, particularly preferably 70 or more, further preferably 90 or more. Moreover, the epoxy equivalent is preferably 1000 or less, particularly preferably 600 or less, and further preferably 300 or less. When the epoxy equivalent is within these ranges, the release sheet can be easily suppressed from warping.

The content of the epoxy group-containing component in the release agent composition is preferably 3% by mass or more, particularly preferably 5% by mass or more. Moreover, the content is preferably 30% by mass or less, and particularly preferably 20% by mass or less. When the content of the epoxy group-containing component is within these ranges, it becomes easier to suppress warping of the release sheet.

(4) Polyorganosiloxane When the release agent composition in the present embodiment contains polyorganosiloxane, the polyorganosiloxane is not particularly limited as long as it can impart desired release properties to the release agent layer. . A polymer of a silicon-containing compound represented by the following general formula (b) can be preferably used as the polyorganosiloxane.

In formula (b), m is an integer of 1 or more. In formula (b), R ¹ to R ⁸ are preferably alkyl groups, aryl groups or alkenyl groups. R ¹ to R ⁸ may be the same or different. In addition, when multiple R ¹ and R ² are present, R ¹ and R ² may be the same or different between repeating units.

The alkyl group is preferably an alkyl group having 1 to 8 carbon atoms, and examples thereof include methyl, ethyl, propyl, butyl, pentyl, hexyl and octyl groups. Among these, the alkyl group is preferably a methyl group.

The aryl group is preferably an aryl group having 6 to 8 carbon atoms, such as a phenyl group and a methylphenyl group. In particular, the polyorganosiloxane in the present embodiment preferably has a phenyl group as the aryl group from the viewpoint of easily achieving the desired peelability.

Preferred examples of the alkenyl group include vinyl group, allyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group and octenyl group. Among these, the alkenyl group is preferably a vinyl group.

In the above formula (b), at least one of R ¹ to R ⁸ may be an organic group. The term "organic group" as used herein refers to a group that does not contain the aforementioned alkyl group, aryl group and alkenyl group. Examples of such organic groups include organic groups having repeating structures such as polyethers, polyesters, polyurethanes, and other resins. In such an organic group, one terminal atom of each polyether, polyester, polyurethane, etc. is bonded to the terminal of polyorganosiloxane or the silicon atom in the chain.

The weight average molecular weight of the polyorganosiloxane is preferably 100 or more, particularly preferably 500 or more, further preferably 1000 or more. When the weight-average molecular weight is 100 or more, the polyorganosiloxane easily lowers the surface free energy on the release surface of the release agent layer, and the desired release property can be easily achieved. Also, the weight average molecular weight is preferably 100,000 or less, particularly preferably 50,000 or less, further preferably 30,000 or less. When the weight-average molecular weight is 100,000 or more, the compatibility between the polyorganosiloxane and other components is improved, and a release agent layer having an excellent surface condition can be easily formed.

When the release agent composition contains polyorganosiloxane, the content of polyorganosiloxane in the release agent composition is preferably 3% by mass or more, particularly preferably 5% by mass or more. Moreover, the content is preferably 30% by mass or less, and particularly preferably 20% by mass or less. When the content of the polyorganosiloxane is within these ranges, the release sheet according to the present embodiment can easily exhibit desired release properties.

(5) Acid catalyst When the release agent composition of the present embodiment contains an acid catalyst, the acid catalyst can promote the condensation reaction between methylated melamine resins and the reaction between methylated melamine resin and other components. It is not particularly limited as long as it is

As examples of the acid catalyst, it is preferable to use at least one of a sulfonic acid-based catalyst and a phosphoric acid-based catalyst. Examples of sulfonic acid catalysts include p-toluenesulfonic acid, methanesulfonic acid, dodecylbenzenesulfonic acid, etc. Among these, p-toluenesulfonic acid is preferred. Examples of phosphoric acid-based catalysts include phosphoric acid and phosphorous acid. Examples of acid catalysts other than those mentioned above include hydrochloric acid, sulfuric acid, nitric acid, and the like. These may be used alone or in combination of two or more. Among these, it is preferable to use p-toluenesulfonic acid.

When the release agent composition contains an acid catalyst, the content of the acid catalyst in the release agent composition is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more. . Moreover, the content is preferably 5.0% by mass or less, and particularly preferably 3.0% by mass or less. When the content of the acid catalyst is within these ranges, the condensation reaction between the methylated melamine resins and the reaction between the methylated melamine resin and other components are effectively promoted, and a well-cured release agent layer can be obtained. It becomes easy to form.

(6) Filler When a filler is added to the release agent composition of the present embodiment, a desired filler can be used depending on the purpose. For example, the filler may be either an organic filler or an inorganic filler, or may be used in combination.

Examples of organic fillers include cross-linked polymethyl methacrylate particles, cross-linked methyl methacrylate-styrene copolymer particles, cross-linked polystyrene particles, cross-linked methyl methacrylate-methyl acrylate copolymer particles, cross-linked alkyl acrylate-styrene copolymer particles, cross-linked Examples thereof include resin particles such as alkyl methacrylate-styrene copolymer particles, melamine/formaldehyde resin particles, benzoguanamine/formaldehyde resin particles, and polyacrylonitrile resin particles. These may be used individually by 1 type, and may use 2 or more types together.

Examples of inorganic fillers include boron nitride particles and silica particles. These may be used individually by 1 type, and may use 2 or more types together.

The average particle size of the filler is not particularly limited, and is preferably 0.1 μm or more, particularly preferably 0.5 μm or more, from the viewpoint of imparting matte properties and preventing particle dropout. From the same point of view, the thickness is preferably 20 μm or less, particularly preferably 15 μm or less. The average particle size can be measured by observing 100 fillers in the cross section of the release sheet with a scanning electron microscope, and taking the average value as the average particle size.

The shape of the filler is not particularly limited, and may be spherical or non-spherical and irregular.

When the release agent composition contains a filler, the content of the filler in the release agent composition is preferably 10% by mass or more, particularly preferably 15% by mass or more, and further preferably 20% by mass. It is preferable that it is above. Also, the content is preferably 70% by mass or less, particularly preferably 65% by mass or less, and further preferably 60% by mass or less.

(7) Other Components In addition to the components described above, the release agent composition may contain dispersants, cross-linking agents, antistatic agents, reaction inhibitors, adhesion improvers, lubricants, and the like.

2-2. Manufacture of release agent composition The release agent composition is prepared by mixing the above acrylic resin, methylated melamine resin, epoxy group-containing component, and optionally polyorganosiloxane, acid catalyst, filler or other components. can be manufactured in The resulting release agent composition may be diluted with a diluting solvent as necessary to prepare a coating liquid.

Examples of the diluent solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; , alcohols such as 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone, propylene glycol monomethyl ether acetate, ethyl acetate, esters such as butyl acetate, cellosolve solvents such as ethyl cellosolve, Alternatively, a mixture thereof or the like is used.

The concentration/viscosity of the coating liquid thus prepared is not particularly limited as long as it is within a range that allows coating, and can be appropriately selected according to the situation. For example, the concentration of the release agent composition is diluted to 3% by mass or more and 60% by mass or less. When obtaining the coating liquid, the addition of a diluent solvent or the like is not a necessary condition, and the diluent solvent may not be added as long as the release agent composition has a viscosity that allows coating.

2-3. Thickness of Release Agent Layer In the release sheet according to the present embodiment, the thickness of the release agent layer is preferably 100 nm or more, particularly preferably 500 nm or more, further preferably 1000 nm or more. Moreover, the thickness is preferably 20 μm or less, particularly preferably 15 μm or less, further preferably 10 μm or less. When the thickness of the release agent layer is within these ranges, it becomes easy to satisfactorily suppress warpage while exhibiting desired release properties.

3. Physical properties of release sheet, etc. In the release sheet according to the present embodiment, the release force to the adhesive tape is preferably 1500 mN/20 mm or less, particularly preferably 1200 mN/20 mm or less, and further preferably 1000 mN/20 mm or less. is preferred. In the release sheet according to the present embodiment, the release agent layer is formed from the release agent composition described above, so that the release force can be easily reduced to 1500 mN/20 mm or less. When the peel force is 1500 mN/20 mm or less, the film can be easily peeled off from the object. The peel force is preferably 10 mN/20 mm or more, particularly preferably 30 mN/20 mm or more, and further preferably 50 mN/20 mm or more. When the peel force is 10 mN/20 mm or more, it becomes easy to suppress unintended peeling of the release sheet from the object. The method for measuring the peel strength is as described in the test examples described later.

4. Method for Manufacturing Release Sheet The method for manufacturing the release sheet in the present embodiment is not particularly limited as long as it includes forming a release agent layer from the release agent composition described above. For example, after coating one side of the substrate with a coating liquid containing the aforementioned release agent composition and optionally an organic solvent, the resulting coating film is dried and heated to cure the release agent composition. to form a release agent layer, thereby obtaining a release sheet.

Specific coating methods include, for example, gravure coating, bar coating, spray coating, spin coating, knife coating, roll coating, and die coating.

The organic solvent is not particularly limited, and various solvents can be used. Examples include hydrocarbon compounds such as toluene, hexane and heptane, isopropyl alcohol, isobutyl alcohol, acetone, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone and mixtures thereof. In particular, it is preferable to use a mixture of methyl ethyl ketone and isopropyl alcohol.

The release agent composition coated as described above is preferably heat-cured. The heating temperature in this case is preferably 100° C. or higher, particularly preferably 120° C. or higher. Moreover, the heating temperature is preferably 220° C. or lower, particularly preferably 200° C. or lower. The heating time for thermosetting is preferably 5 seconds or longer, and particularly preferably 15 seconds or longer. Also, the heating time is preferably 120 seconds or less, particularly preferably 90 seconds or less.

5. Usage of Release Sheet The release sheet according to the present embodiment can be used, for example, as a protective sheet for various adhesives such as adhesive sheets. It can also be used as a process film when producing various resin sheets, ceramic green sheets, synthetic leathers, various composite materials, and the like. Furthermore, it can also be used as a transfer sheet when producing an electromagnetic wave shielding film or the like.

When the release sheet according to the present embodiment is used as a process film or a transfer sheet, various sheet materials formed by applying an adhesive composition, resin, or the like to the release layer side surface of the release sheet are used as the release sheet. Used in the process of peeling from.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is meant to include all design changes and equivalents that fall within the technical scope of the present invention.

For example, another layer such as an antistatic layer may be provided on the side of the base material of the release sheet opposite to the release agent layer or between the base material and the release agent layer.

EXAMPLES The present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]
(1) Preparation of release agent composition A silicone-modified acrylic resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name “X-62- 9088", mass ratio of silicone-modified acrylic resin and methylated melamine resin: silicone-modified acrylic resin/methylated melamine resin = 70/30, silicone-modified amount of silicone-modified acrylic resin: 0.4 mmol/g) 28.64 mass part (solid content conversion value, hereinafter the same), and a silicone-modified acrylic resin containing a different melamine resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name “X-62-9089”, silicone-modified acrylic resin and methyl Mass ratio with methylated melamine resin: silicone-modified acrylic resin/methylated melamine resin = 70/30, amount of silicone-modified acrylic resin modified with silicone: 0.08 mmol/g) 19.09 parts by mass, as a filler of boron nitride particles (manufactured by Showa Denko KK, product name “UHP-S2”, average particle size 0.7 to 10 μm) was added and dispersed at 2,000 rpm for 20 minutes using a disper. At this time, the amount of the mixed solvent was adjusted so that the solid content concentration of the mixed liquid immediately after addition of the filler was 20% by mass.

Subsequently, 1.36 parts by mass of p-toluenesulfonic acid (manufactured by Shin-Etsu Chemical Co., Ltd., product name “CAT-PS-80”) as an acid catalyst and an epoxy resin ( Mitsubishi Chemical Co., Ltd., "jER-828", BisA type, epoxy equivalent: 184 to 194) 9.09 parts by mass, and terminal hydroxy-modified polyorganosiloxane as polyorganosiloxane (BYK Chemie, product name "BYKSiliclean 3700") and stirred for 5 minutes at 1,500 rpm using a disper to prepare a coating liquid of the release agent composition.

(2) Preparation of release sheet The obtained coating liquid of the release agent composition was applied to a polyethylene terephthalate (PET) film having a thickness of 50 μm (Mitsubishi Chemical Co., product name “PET50T-100”) using a Meyer bar #4. to form a coating film. The coating film was cured by drying at 150° C. for 1 minute to form a release agent layer having a thickness of about 5 μm. As a result, a release sheet was obtained in which the substrate and the release agent layer were laminated.

[Examples 2 to 6 and Comparative Examples 1 to 3]
A release sheet was produced in the same manner as in Example 1, except that the composition of the release agent composition was changed as shown in Table 1. In Comparative Examples 1 to 3, no epoxy group-containing component was used.

[Test Example 1] (Measurement of peel strength)
The release sheets obtained in Examples and Comparative Examples were stored in an environment of 23° C. and 50% RH for 1 day or longer. After that, a 2 kg roller was reciprocated once so that the surface of the release sheet on the side of the release agent layer and the surface of the adhesive layer of the adhesive tape ("31B tape" manufactured by Nitto Denko Co., Ltd.) were in contact with each other. , 23° C. and 50% RH environment for 30 minutes.

For the measurement sample obtained by this, in accordance with JIS-Z0237: 2009, the tape side of the adhesive tape was peeled in a 180 degree direction using a tensile tester at a peel speed of 300 mm / min Peel strength when peeled. was measured as peel force (mN/20 mm). Table 1 shows the results.

[Test Example 2] (Measurement of warpage amount)
The release sheets of Examples and Comparative Examples cut into B4 size sheets were placed on a flat table with the base layer side down. Then, in an atmosphere of 23° C. and 50% RH, the vertical distance (mm) from the table surface at the four corners of the release sheet was measured, and the average value was taken as the amount of warpage (mm). Table 1 shows the results.

Furthermore, based on the results of Test Examples 1 and 2, a comprehensive evaluation was determined based on the following criteria. Table 1 shows the results.
O: Satisfied both the condition that the peel force is 250 mN/20 mm or less and the condition that the amount of warp is 10.0 mm or less.
x: At least one of the condition that the peel force is 250 mN/20 mm or less and the condition that the amount of warpage is 10.0 mm or less was not satisfied.

Here, details such as abbreviations in Table 1 are as follows.
[Epoxy group-containing component]
828: Epoxy resin (manufactured by Mitsubishi Chemical Corporation, "jER-828", BisA type, epoxy equivalent: 189)
630: Epoxy resin (manufactured by Mitsubishi Chemical Corporation, "jER-630", multifunctional type, epoxy equivalent: 98)
604: Epoxy resin (manufactured by Mitsubishi Chemical Corporation, "jER-604", multifunctional type, epoxy equivalent: 120)
614B: Sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, "Denacol EX-614B", multifunctional type, epoxy equivalent: 173)

As is clear from Table 1, the release sheets obtained in Examples exhibited excellent releasability and well suppressed warping.

The release sheet of the present invention is suitably used as a protective sheet or a process film.

Claims (4)

A release sheet comprising a substrate and a release agent layer provided on at least one side of the substrate,
A release sheet, wherein the release agent layer is formed from a release agent composition containing a silicone-modified acrylic resin, a methylated melamine resin, and an epoxy group-containing component having an epoxy group. The release sheet according to claim 1, wherein the release agent composition contains a filler. 3. The release sheet according to claim 1, wherein the release agent composition contains polyorganosiloxane. The release sheet according to any one of claims 1 to 3, wherein the release agent composition contains an acid catalyst.