Release sheet

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

[Technical Field]

[0001] This invention relates to a release sheet. [Background technology]

[0002] Generally, a release sheet (sometimes called a "process film") has a base material such as paper, plastic film, or polyethylene laminated paper, and a release agent layer provided on the base material. The release agent layer is formed by applying a release agent composition to the base material and drying or curing the resulting coating.

[0003] Release sheets are widely used, for example, as protective sheets for the adhesive layer of adhesive sheets, process films for resin sheet manufacturing, process films for ceramic green sheet film formation, and process films for synthetic leather manufacturing (see, for example, Patent Document 1).

[0004] Release sheets are removed from an object after its purpose, such as protection or manufacturing, has been fulfilled. Therefore, they must be easily removable without requiring excessive force. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-171617 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, during the manufacturing of release sheets, warping may occur in the release sheet as the coating of the release agent composition dries and hardens. When such warping occurs, if the release sheet is used as a protective sheet, it may not adhere sufficiently to the object being protected, making unintended peeling more likely. Also, if the release sheet is used as a process film, the warping of the release sheet will be reflected in the object formed on the release sheet.

[0007] This invention has been made in view of the above circumstances, and aims to provide a release sheet that has excellent release properties and suppresses the occurrence of warping. [Means for solving the problem]

[0008] To achieve the above objective, firstly, the present invention provides a release sheet comprising a base material and a release agent layer provided on at least one side of the base material, 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 epoxy groups (Invention 1).

[0009] The release sheet according to the above invention (Invention 1) exhibits excellent release properties and suppresses warping because the release agent layer is formed from the above-described release agent composition.

[0010] In the above invention (Invention 1), it is preferable that the release agent composition contains a filler (Invention 2).

[0011] In the above invention, it is preferable that the release agent composition contains a polyorganosiloxane (Invention 3).

[0012] In the above invention, it is preferable that the stripping agent composition contains an acid catalyst (Invention 4). [Effects of the Invention]

[0013] The release sheet according to the present invention has excellent release properties and suppresses the occurrence of warping. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below. A release sheet according to one embodiment of the present invention comprises a base material and a release agent layer provided on one side of the base material.

[0015] Furthermore, in the release sheet according to this 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 epoxy groups.

[0016] The release sheet according to this embodiment achieves excellent release properties while effectively suppressing warping, as the release agent layer is formed from the above-mentioned release agent composition. In particular, because it is mainly formed from a silicone-modified acrylic resin and a methylated melamine resin, the release agent layer has the desired surface free energy and becomes sufficiently cured, resulting in excellent release properties. Furthermore, the use of epoxy group-containing components suppresses shrinkage during the formation of the release agent layer, making the release sheet less prone to warping.

[0017] 1. Base material In the release sheet according to this embodiment, the base material is not particularly limited, and any one can be appropriately selected from conventionally known ones and used. As such a base material, for example, a plastic film, paper, or the like can be used. As the plastic film, for example, polyester such as polyethylene terephthalate and polyethylene naphthalate, polyolefin such as polypropylene and polymethylpentene, polycarbonate, polyvinyl acetate, and other plastic films can be mentioned. These plastic films may be single-layer or multilayer of two or more layers of the same or different types. Among these, a polyester film is preferred, and a polyethylene terephthalate film is particularly preferred. Since the polyethylene terephthalate film is less likely to generate dust during processing, use, etc., for example, it can effectively prevent coating defects due to dust or the like. Examples of the paper include high-quality paper, glassine paper, impregnated paper, coated paper, and the like.

[0018] In addition, in this base material, for the purpose of improving the adhesion to the release agent layer provided on its surface, if desired, surface treatment such as oxidation method or roughening method, or primer treatment can be performed on one side or both sides. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, ultraviolet irradiation treatment, etc. Examples of the roughening method include sandblast method, thermal spraying treatment method, etc. These surface treatment methods are appropriately selected according to the type of the base material, but generally the corona discharge treatment method is preferably used in terms of effect and operability.

[0019] The thickness of the base material is preferably 10 μm or more, particularly preferably 15 μm or more, and even more preferably 20 μm or more. Also, the thickness is preferably 300 μm or less, particularly preferably 200 μm or less, and even more preferably 125 μm or less.

[0020] 2. Release agent layer 2-1. Each component 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 in particular, from the viewpoint of improving releasability, it is also preferable to contain a polyorganosiloxane. Further, from the viewpoint of promoting the reaction between methylated melamine resins or between a methylated melamine resin and other components and facilitating the formation of a well-cured release agent layer, it is also preferable for the release agent composition to contain an acid catalyst. Furthermore, from the viewpoint of imparting desired properties such as forming surface irregularities to impart matting properties, it is also preferable to contain a filler.

[0021] (1) Silicone-modified acrylic resin The silicone-modified acrylic resin in the present embodiment is not particularly limited as long as the acrylic resin is silicone-modified. For example, it may be obtained by modifying an acrylic resin with a silicone modifier. Examples of methods for modifying an acrylic resin with a silicone modifier include, for example, a method of reacting an acrylic resin having a functional group with a silicone modifier having a functional group. The 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. The silicone modifier having a functional group is a silicone modifier having a functional group capable of reacting with the functional group of the acrylic resin at its terminal end.

[0022] Examples of monomers constituting the acrylic resin 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 alone or in combination of two or more. The 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".

[0023] Examples of the above-mentioned silicone modifiers include organopolysiloxanes having organic groups such as dimethylpolysiloxane. Examples of such organic groups include phenyl groups, methyl groups, ethyl groups, isopropyl groups, hexyl groups, cyclohexyl groups, vinyl groups, etc. These may be used individually or in combination of two or more.

[0024] Examples of the above-mentioned functional groups in acrylic resins and silicone modifiers include hydroxyl groups, amino groups, carboxyl groups, thiol groups, isocyanate groups, epoxy groups, hydrosilyl groups, ethynyl groups, ammonium groups, amide groups, imino groups, alkoxysilyl groups, ether groups, sulfonic acid groups, and nitrile groups.

[0025] Furthermore, examples of reactions between the functional groups of acrylic resins and the functional groups of silicone modifiers include reactions between active hydrogen groups such as hydroxyl groups, primary amino groups, secondary amino groups, carboxyl groups, and thiol groups and isocyanate groups or epoxy groups; esterification reactions between hydroxyl groups and carboxyl groups; and hydrosilylation reactions between hydrosilyl groups and ethynyl groups.

[0026] Furthermore, silicone-modified acrylic resin can also be obtained by polymerizing a mixture of acrylic resin monomers and a silicone modifier having acrylate functional groups.

[0027] Furthermore, the silicone-modified acrylic resin may have functional groups of its own. That is, the silicone-modified acrylic resin may have functional groups other than those used in the reaction between the acrylic resin and the silicone modifier. These functional groups may be functional groups that are available for use in the reaction between the acrylic resin and the silicone modifier but remain unused in the reaction, or they may be functional groups that do not contribute to the above reaction. Examples of functional groups that the silicone-modified acrylic resin may have include reactive functional groups such as hydroxyl groups, carboxyl groups, and mercapto groups, with hydroxyl groups being preferred as they can react efficiently with methylated melamine resin. The silicone-modified acrylic resin may have one type of functional group or multiple types. Also, the functional groups that the silicone-modified acrylic resin may be located at either the terminal or side chain of the silicone-modified acrylic resin, or they may be located at either the terminal or side chain.

[0028] Some commercially available silicone-modified acrylic resins already contain melamine resin or the like as a curing agent for curing the silicone-modified acrylic resin. When using such a commercially available product, the melamine resin or the like added as a curing agent may be treated as the methylated melamine resin according to this embodiment, and the remaining net amount may be treated as the silicone-modified acrylic resin according to this embodiment.

[0029] Examples of commercially available products containing silicone-modified acrylic resin and methylated melamine resin include "X-62-9088" and "X-62-9089" from Shin-Etsu Chemical Co., Ltd., and "TA31-291F" from Showa Denko Materials Co., Ltd.

[0030] The amount of silicone modification in the silicone-modified acrylic resin according to this embodiment is preferably 0.01 mmol / g or more, particularly preferably 0.03 mmol / g or more, and even more preferably 0.1 mmol / g or more. Furthermore, the amount of silicone modification is preferably 10 mmol / g or less, particularly preferably 5 mmol / g or less, and even more preferably 1 mmol / g or less. Having the amount of silicone modification within the above range makes it easier to exhibit excellent release properties. The amount of silicone modification refers to the amount of silyl groups (mmol) per gram of solid content of the silicone-modified acrylic resin.

[0031] In this embodiment, the amount of silicone modification in the silicone-modified acrylic resin may be adjusted using two or more types of silicone-modified acrylic resins (A).

[0032] The content of silicone-modified acrylic resin in the release agent composition is preferably 20% by mass or more, particularly preferably 30% by mass or more, and more preferably 40% by mass or more. Furthermore, the content is preferably 80% by mass or less, particularly preferably 70% by mass or less, and more preferably 60% by mass or less. By having the content of silicone-modified acrylic resin within these ranges, the release sheet according to this embodiment is more likely to exhibit the desired release properties.

[0033] (2) Methylated melamine resin The methylated melamine resin in this embodiment is not particularly limited as long as it is a melamine resin that has been methylated. In this specification, the term "melamine resin" means an aggregate of one type of melamine compound, or a mixture containing multiple types of melamine compounds and / or a polynuclear body formed by the condensation of such melamine compounds.

[0034] The melamine resin that forms the basis of the above-mentioned methylated melamine resin preferably contains a melamine compound represented by the following general formula (a), or a polynuclear body formed by the condensation of two or more such melamine compounds. [ka]

[0035] In formula (a), X preferably represents -H, -CH2-OH, or -CH2-OR, and R preferably represents an alkyl group having 1 to 8 carbon atoms. The number of carbon atoms is preferably 1 to 6, and particularly preferably 1 to 3. Examples of alkyl groups having 1 to 8 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, and octyl groups, with methyl being particularly preferred. In this embodiment, the methylated melamine resin has at least one X that is -CH2-OR, and at least one R that is a methyl group.

[0036] In general, melamine compounds include full ether type where all X are -CH2-OR, imino-methylol type where at least one X is -CH2-OH and at least one X is H, methylol type where at least one X is -CH2-OH and no H X is present, and imino type where at least one X is H and no -CH2-OH X is present. The methylated melamine resin according to this embodiment may be based on any of these types of melamine compounds, but a full ether type methylated melamine resin is particularly preferred from the viewpoint of easily exhibiting the desired release properties.

[0037] In this embodiment, the weight-average molecular weight of the methylated melamine resin is preferably 150 or more, particularly preferably 300 or more, and even more preferably 500 or more. The weight-average molecular weight is preferably 10,000 or less, particularly preferably 5,000 or less, and even more preferably 4,000 or less. A weight-average molecular weight of 150 or more stabilizes the reaction rate between methylated melamine resins and between methylated melamine resins and other components, allowing for the formation of a smoother release surface. Furthermore, a weight-average molecular weight of 10,000 or less results in a moderately low viscosity of the release agent composition, making it easier to apply the release agent composition to the substrate.

[0038] The content of methylated melamine resin in the release agent composition is preferably 20% by mass or more, particularly preferably 30% by mass or more, and more preferably 40% by mass or more. Furthermore, the content is preferably 80% by mass or less, particularly preferably 70% by mass or less, and more preferably 60% by mass or less. By having the content of methylated melamine resin within these ranges, the release sheet according to this embodiment is more likely to exhibit the desired release properties.

[0039] (3) Epoxy group-containing component The epoxy group-containing component in this embodiment is not particularly limited as long as it has an epoxy group, but the use of an epoxy resin is particularly preferred. In this specification, "epoxy resin" refers to an epoxy resin that is curable, i.e., an uncured epoxy resin.

[0040] Known epoxy resins can be used, such as polyfunctional epoxy resins, biphenyl compounds, bisphenol A diglycidyl ether and its hydrogenated products, o-cresol novolac type epoxy resins, dicyclopentadiene type epoxy resins, biphenyl type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenylene skeleton type epoxy resins, and bifunctional or more epoxy compounds. These may be used individually or in combination of two or more types.

[0041] The epoxy equivalent (gram equivalent: g / eq) of the epoxy group-containing component is preferably 50 or more, particularly preferably 70 or more, and even more preferably 90 or more. Furthermore, the epoxy equivalent is preferably 1000 or less, particularly preferably 600 or less, and even more preferably 300 or less. Having the epoxy equivalent within these ranges makes it easier to suppress warping of the release sheet.

[0042] The content of epoxy group-containing components in the release agent composition is preferably 3% by mass or more, and more preferably 5% by mass or more. Furthermore, the content is preferably 30% by mass or less, and more preferably 20% by mass or less. Having the epoxy group-containing component content within these ranges makes it easier to suppress warping of the release sheet more effectively.

[0043] (4) Polyorganosiloxane In this embodiment, if the release agent composition contains a polyorganosiloxane, the polyorganosiloxane is not particularly limited as long as it can impart the desired release properties to the release agent layer. A polymer of a silicon-containing compound represented by the following general formula (b) can be suitably used as the polyorganosiloxane. [ka]

[0044] In formula (b), m is an integer of 1 or more. Further, in formula (b), R 1 ~R 8 is preferably an alkyl group, an aryl group or an alkenyl group. Note that R 1 ~R 8 may be the same or different. Also, when there are a plurality of R 1 and R 2 , R 1 and R 2 may be the same or different between repeating units.

[0045] The above alkyl group is preferably an alkyl group having 1 to 8 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group and the like. Among these, the alkyl group is preferably a methyl group.

[0046] The above aryl group is preferably an aryl group having 6 to 8 carbon atoms, and examples thereof include a phenyl group, a methylphenyl group and the like. In particular, in the polyorganosiloxane of the present embodiment, from the viewpoint of easily achieving desired peelability, it is preferable to have a phenyl group as the above aryl group.

[0047] Preferred examples of the above alkenyl group include a vinyl group, an allyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group and the like. Among these, the alkenyl group is preferably a vinyl group.

[0048] Further, in the above formula (b), R 1 ~R 8At least one of these may be an organic group. In this specification, "organic group" refers to a group that does not include the alkyl, aryl, and alkenyl groups mentioned above. Examples of such organic groups include organic groups with repeating structures such as polyethers, polyesters, polyurethanes, and other resins. In such organic groups, the atoms at each end of the polyether, polyester, polyurethane, etc., are bonded to silicon atoms at the end or in the chain of the polyorganosiloxane.

[0049] The weight-average molecular weight of the polyorganosiloxane is preferably 100 or more, particularly preferably 500 or more, and even more preferably 1000 or more. A weight-average molecular weight of 100 or more makes it easier for the polyorganosiloxane to reduce the surface free energy at the release surface of the release agent layer, thus facilitating the achievement of the desired release properties. Furthermore, the weight-average molecular weight is preferably 100,000 or less, particularly preferably 50,000 or less, and even more preferably 30,000 or less. A weight-average molecular weight of 100,000 or more results in better compatibility between the polyorganosiloxane and other components, facilitating the formation of a release agent layer with a superior surface condition.

[0050] When the release agent composition contains polyorganosiloxane, the polyorganosiloxane content in the release agent composition is preferably 3% by mass or more, and particularly preferably 5% by mass or more. Furthermore, the content is preferably 30% by mass or less, and particularly preferably 20% by mass or less. By having the polyorganosiloxane content within these ranges, the release sheet according to this embodiment is more likely to exhibit the desired release properties.

[0051] (5) Acid catalyst In this embodiment, if the release agent composition contains an acid catalyst, the acid catalyst is not particularly limited, as long as it can promote the condensation reaction between methylated melamine resins or the reaction between methylated melamine resins and other components.

[0052] As examples of the above acid catalysts, it is preferable to use at least one of a sulfonic acid-based catalyst and a phosphoric acid-based catalyst. Examples of sulfonic acid-based catalysts include p-toluenesulfonic acid, methanesulfonic acid, and dodecylbenzenesulfonic acid, and 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, and nitric acid. These may be used individually or in combination of two or more. Among these, p-toluenesulfonic acid is preferred.

[0053] 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, and particularly preferably 0.5% by mass or more. Furthermore, the content is preferably 5.0% by mass or less, and particularly preferably 3.0% by mass or less. When the acid catalyst content is within these ranges, the condensation reaction between methylated melamine resins and the reaction between methylated melamine resins and other components are effectively promoted, making it easier to form a well-cured release agent layer.

[0054] (6) Filler When a filler is added to the release agent composition in this embodiment, the filler can be any type desired depending on the purpose. For example, the filler may be either an organic filler or an inorganic filler, or they may be used in combination.

[0055] 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 alkyl methacrylate-styrene copolymer particles, melamine-formaldehyde resin particles, benzoguanamine-formaldehyde resin particles, polyacrylonitrile resin particles, and other resin particles. These may be used individually or in combination of two or more types.

[0056] Examples of inorganic fillers include boron nitride particles and silica particles. These may be used individually or in combination of two or more types.

[0057] There are no particular restrictions on the average particle size of the filler, but from the viewpoint of imparting matte properties and preventing particle shedding, it is preferably 0.1 μm or larger, and particularly preferably 0.5 μm or larger. Also, from the same viewpoint, it is preferably 20 μm or smaller, and particularly preferably 15 μm or smaller. The above average particle size can be measured by observing the filler in the cross-section of the release sheet with a scanning electron microscope, observing 100 fillers, and taking the average value.

[0058] There are no particular restrictions on the shape of the filler; it may be spherical or have an irregular shape that is not spherical.

[0059] If the release agent composition contains a filler, the filler content in the release agent composition is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. Furthermore, the content is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less.

[0060] (7) Other ingredients In addition to the components mentioned above, the release agent composition may also contain dispersants, crosslinking agents, antistatic agents, reaction inhibitors, adhesion enhancers, lubricants, and the like.

[0061] 2-2. Manufacture of the release agent composition The release agent composition can be prepared by mixing the above-mentioned acrylic resin, methylated melamine resin, epoxy group-containing component, and optionally polyorganosiloxane, acid catalyst, filler, or other component. The resulting release agent composition may be diluted with a diluent solvent as needed and used as a coating solution.

[0062] Examples of the diluent solvents used 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 methanol, ethanol, isopropyl alcohol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as propylene glycol monomethyl ether acetate, ethyl acetate, and butyl acetate; cellosolve solvents such as ethyl cellosolve; or mixtures thereof.

[0063] The concentration and viscosity of the coating solution prepared in this manner are not particularly limited, as long as they are within the range of coating, and can be appropriately selected depending on the situation. For example, the release agent composition may be diluted to a concentration of 3% by mass or more and 60% by mass or less. Note that the addition of a diluent is not a necessary condition when obtaining the coating solution; if the release agent composition has a viscosity suitable for coating, a diluent may be omitted.

[0064] 2-3. Thickness of the release agent layer In the release sheet according to this embodiment, the thickness of the release agent layer is preferably 100 nm or more, particularly preferably 500 nm or more, and even more preferably 1000 nm or more. Furthermore, the thickness is preferably 20 μm or less, particularly preferably 15 μm or less, and even more preferably 10 μm or less. Having the thickness of the release agent layer within these ranges makes it easier to suppress warping while exhibiting the desired release properties.

[0065] 3. Physical properties of the release sheet, etc. In the release sheet according to this embodiment, the peeling force on the adhesive tape is preferably 1500 mN / 20 mm or less, particularly preferably 1200 mN / 20 mm or less, and even more preferably 1000 mN / 20 mm or less. In the release sheet according to this embodiment, the release agent layer is formed by the release agent composition described above, making it easier to reduce the above peeling force to 1500 mN / 20 mm or less. With a peeling force of 1500 mN / 20 mm or less, it becomes possible to easily peel it off from the target. Furthermore, the above peeling force is preferably 10 mN / 20 mm or more, particularly preferably 30 mN / 20 mm or more, and even more preferably 50 mN / 20 mm or more. With a peeling force of 10 mN / 20 mm or more, it is easier to suppress unintended peeling of the release sheet from the target. The method for measuring the above peeling force is as described in the test examples below.

[0066] 4. Method for manufacturing release sheets The method for manufacturing the release sheet in this embodiment is not particularly limited, as long as it includes forming a release agent layer from the release agent composition described above. For example, it is preferable to apply a coating solution containing the release agent composition described above and optionally an organic solvent to one side of a substrate, and then dry and heat the resulting coating film to cure the release agent composition and form a release agent layer, thereby obtaining a release sheet.

[0067] Specific coating methods mentioned above include, for example, gravure coating, bar coating, spray coating, spin coating, knife coating, roll coating, and die coating.

[0068] There are no particular restrictions on the organic solvents used, and a variety of them can be used. For example, hydrocarbon compounds such as toluene, hexane, and heptane, as well as isopropyl alcohol, isobutyl alcohol, acetone, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, and mixtures thereof can be used. In particular, it is preferable to use a mixture of methyl ethyl ketone and isopropyl alcohol.

[0069] The release agent composition coated as described above is preferably heat-cured. In this case, the heating temperature is preferably 100°C or higher, and particularly preferably 120°C or higher. Furthermore, the heating temperature is preferably 220°C or lower, and particularly preferably 200°C or lower. The heating time for heat curing is preferably 5 seconds or more, and particularly preferably 15 seconds or more. Furthermore, the heating time is preferably 120 seconds or less, and particularly preferably 90 seconds or less.

[0070] 5. How to use the release sheet The release sheet according to this embodiment can be used, for example, as a protective sheet for various adhesive materials such as adhesive sheets. It can also be used as a process film when manufacturing various resin sheets, ceramic green sheets, synthetic leather, various composite materials, etc. Furthermore, it can be used as a transfer sheet when manufacturing electromagnetic shielding films, etc.

[0071] When the release sheet according to this embodiment is used as a process film or transfer sheet, it is used in a process to peel off various sheet materials formed by applying an adhesive composition, resin, etc., to the release layer side of the release sheet from the release sheet.

[0072] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. Accordingly, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0073] For example, other layers, such as an antistatic layer, may be provided on the opposite side of the release agent layer on the substrate in the release sheet, or between the substrate and the release agent layer. [Examples]

[0074] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0075] [Example 1] (1) Preparation of the 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 to methylated melamine resin: silicone-modified acrylic resin / methylated melamine resin = 70 / 30, amount of silicone modification of silicone-modified acrylic resin: 0.4 mmol / g) is added to a mixed solvent of toluene and methyl ethyl ketone in a 1:1 mass ratio (solid content equivalent, the same applies below), and a different melamine resin is added. After adding 19.09 parts by mass of acrylic resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name "X-62-9089", mass ratio of silicone-modified acrylic resin to methylated melamine resin: silicone-modified acrylic resin / methylated melamine resin = 70 / 30, amount of silicone modification in silicone-modified acrylic resin: 0.08 mmol / g), boron nitride particles (manufactured by Showa Denko K.K., product name "UHP-S2", average particle size 0.7~10 μm) as a filler were added and dispersed using a disperser at 2,000 rpm for 20 minutes. At this time, the amount of the above mixed solvent was adjusted so that the solid content concentration of the mixture immediately after the addition of the filler was 20% by mass.

[0076] Next, to the above-mentioned mixture, 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, 9.09 parts by mass of epoxy resin (manufactured by Mitsubishi Chemical Corporation, "jER-828", BisA type, epoxy equivalent: 184-194) as an epoxy group-containing component, and 9.09 parts by mass of terminally hydroxy-modified polyorganosiloxane (manufactured by BYK Chemie, product name "BYKSiliclean3700") as a polyorganosiloxane were added, and the mixture was stirred at 1,500 rpm for 5 minutes using a disperser to prepare a coating solution for the release agent composition.

[0077] (2) Preparation of release sheets The obtained release agent composition was applied to one side of a 50 μm thick polyethylene terephthalate (PET) film (Mitsubishi Chemical Corporation, 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 approximately 5 μm thick. This resulted in a release sheet in which the substrate and the release agent layer were laminated.

[0078] [Examples 2-6 and Comparative Examples 1-3] Release sheets were manufactured 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, epoxy group-containing components were not used.

[0079] [Test Example 1] (Measurement of peeling force) The release sheets obtained in the examples and comparative examples were stored at 23°C and 50%RH for at least one day. Then, a 2kg roller was passed back and forth once to bring the release agent layer side of the release sheet into contact with the adhesive layer side of the adhesive tape (manufactured by Nitto Denko Corporation, "31B Tape"), and the sheets were left to stand at 23°C and 50%RH for 30 minutes.

[0080] The resulting sample was then tested in accordance with JIS-Z0237:2009. The peel strength of the adhesive tape was measured using a tensile testing machine when the tape side of the tape was peeled off at a peeling speed of 300 mm / min in a 180-degree direction. The peel strength was expressed as the peel force (mN / 20mm). The results are shown in Table 1.

[0081] [Test Example 2] (Measurement of Warpage) The release sheets for the examples and comparative examples, cut into B4-sized sheets, were placed on a flat table with the base layer side down. Then, under an atmosphere of 23°C and 50% RH, the vertical distance (mm) from the table surface at each of the four corners of the release sheet was measured, and the average value was taken as the amount of warping (mm). The results are shown in Table 1.

[0082] Furthermore, based on the results of Test Example 1 and Test Example 2, an overall evaluation was determined based on the following criteria. The results are shown in Table 1. ○: Both conditions were met: peeling force of 250 mN / 20 mm or less, and warpage of 10.0 mm or less. ×: At least one of the following conditions was not met: peeling force of 250 mN / 20 mm or less, and warpage of 10.0 mm or less.

[0083] The details of the abbreviations and other terms listed 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", polyfunctional type, epoxy equivalent: 98) 604: Epoxy resin (manufactured by Mitsubishi Chemical Corporation, "jER-604", polyfunctional type, epoxy equivalent: 120) 614B: Sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, "Denacol EX-614B", polyfunctional type, epoxy equivalent: 173)

[0084] [Table 1]

[0085] As is clear from Table 1, the release sheets obtained in the examples showed excellent release properties and good suppression of warping. [Industrial applicability]

[0086] The release sheet of the present invention is suitably used as a protective sheet or a process film.

Claims

1. A release sheet comprising a base material and a release agent layer provided on at least one side of the base material, 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 epoxy groups. The epoxy group-containing component is at least one selected from polyfunctional epoxy resins, bisphenol A diglycidyl ether and its hydrogenated products, o-cresol novolac type epoxy resins, dicyclopentadiene type epoxy resins, biphenyl type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, and phenylene skeleton type epoxy resins. The amount of silicone modification in the silicone-modified acrylic resin is 0.01 mmol / g or more and 10 mmol / g or less. A release sheet characterized by the following features.

2. The release sheet according to claim 1, characterized in that the release agent composition contains a filler.

3. The release sheet according to claim 1 or 2, characterized in that the release agent composition contains a polyorganosiloxane.

4. The release sheet according to any one of claims 1 to 3, characterized in that the release agent composition contains an acid catalyst.

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