Release sheet

Abstract

This release sheet comprises 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) an alicyclic epoxy group-containing cyclic siloxane compound, (B) a carbinol-modified polyorganosiloxane, and (C) an acid catalyst; and the blending amount of the carbinol-modified polyorganosiloxane (B) with respect to 100 parts by mass of the alicyclic epoxy group-containing cyclic siloxane compound (A) is 3-15 parts by mass. According to said release sheet, a silicone component hardly migrates from the release agent layer, and the release force can be set low.

Description

Peel-off sheet

[0001] The present invention relates to a release sheet that can be used, for example, for adhesive sheets, in the production process of ceramic green sheets, etc.

[0002] Release sheets have conventionally been used in the production of pressure-sensitive adhesive sheets, and are also widely used, for example, as release films for producing ceramic green sheets, processing films for producing resin sheets, and processing films for producing synthetic leather.

[0003] The release sheet as described above generally comprises a substrate such as paper, a plastic film, polyethylene-laminated paper, etc., and a release agent layer provided on the substrate. The release agent layer is usually formed by applying a curable release agent composition containing a release component onto the substrate and curing the composition.

[0004] In such release sheets, the release agent layer often contains polyorganosiloxane (a silicone component) in order to reduce the release force. However, when the release agent layer contains a silicone component, there is a problem in that the silicone component is likely to migrate toward the layer laminated on the release agent layer.

[0005] For example, the pressure-sensitive adhesive sheet may be attached to an object to which polyorganosiloxane or the silicon atoms constituting the polyorganosiloxane are repellent, such as a semiconductor material or semiconductor component. The release agent layer of the release sheet laminated on the pressure-sensitive adhesive layer of such a pressure-sensitive adhesive sheet needs to be one that does not easily allow the silicone component to migrate.

[0006] In addition, the ceramic green sheets are punched to a predetermined size together with the release sheet, and then peeled off from the release sheet and laminated. If the silicone component migrates to the surface of the ceramic green sheet that was in contact with the release agent layer during this process, the adhesive strength between the ceramic green sheets will decrease, resulting in a problem of reduced yield. Therefore, the release agent layer of the release sheet for producing ceramic green sheets must also be made to be resistant to silicone component migration.

[0007] In order to solve the above problems, Patent Document 1 discloses a silicone-coated sheet having a substrate on which a release agent layer is provided, the release agent layer being formed by curing a release agent composition containing a silicone resin, a cyclic siloxane compound containing an alicyclic epoxy group, and a photocationic catalyst. Also, Patent Document 2 discloses a release film for pressure-sensitive adhesive sheets having a substrate on which a release agent layer is provided, the release agent layer being formed from a release agent composition containing a melamine resin and a carbinol-modified polyorganosiloxane.

[0008] JP 2016-79349 A JP 2018-168303 A

[0009] The present invention has been made in consideration of the above-described circumstances, and aims to provide a release sheet that is less susceptible to migration of silicone components from the release agent layer and that allows the release force to be set low.

[0010] In order to achieve the above object, first, the present invention provides 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 formed from a release agent composition containing an alicyclic epoxy group-containing cyclic siloxane compound (A), a carbinol-modified polyorganosiloxane (B), and an acid catalyst (C), and the amount of the carbinol-modified polyorganosiloxane (B) is 3 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the alicyclic epoxy group-containing cyclic siloxane compound (A) (Invention 1).

[0011] It is believed that the release agent layer in the above invention (Invention 1) forms a structure in which the cured product of the alicyclic epoxy group-containing cyclic siloxane compound (A) and the carbinol-modified polyorganosiloxane (B) are integrated together due to the action of the acid catalyst (C) when formed from the release agent composition. This structure makes it difficult for the silicone component to migrate from the release agent layer, and allows the release force to be set low. In particular, by blending the carbinol-modified polyorganosiloxane (B) in the above-mentioned amount relative to the alicyclic epoxy group-containing cyclic siloxane compound (A), the surface free energy of the release surface of the resulting release agent layer is effectively reduced, thereby reducing the release force. Furthermore, by blending the carbinol-modified polyorganosiloxane (B) in the above-mentioned amount relative to the alicyclic epoxy group-containing cyclic siloxane compound (A), migration of the silicone component from the release agent layer can be effectively suppressed.

[0012] In the above invention (Invention 1), the alicyclic epoxy group-containing cyclic siloxane compound (A) is represented by the following formula (a1): (In the formula, R １ is an alkyl group.) (Invention 2).

[0013] In the above inventions (Inventions 1 and 2), the carbinol-modified polyorganosiloxane (B) contains an organic group represented by the following general formula (b1): (In general formula (b1), R ２ is an alkylene group having 1 to 6 carbon atoms, or an organic group represented by the following general formula (b2): (In general formula (b2), R ３ is an alkylene group having 1 to 6 carbon atoms, and R ４ is an alkylene group having 2 to 3 carbon atoms.) at both ends, one end, or in a side chain (Invention 3).

[0014] In the above inventions (Inventions 1 to 3), the weight average molecular weight of the carbinol-modified polyorganosiloxane (B) is preferably 1,000 or more and 10,000 or less (Invention 4).

[0015] The release sheets according to the above inventions (Inventions 1 to 4) are preferably used in the ceramic green sheet manufacturing process (Invention 5) or for adhesive sheets (Invention 6).

[0016] The release sheet of the present invention is less susceptible to migration of the silicone component from the release agent layer, and the release force can be set low.

[0017] Hereinafter, an embodiment of the present invention will be described. The release sheet according to this embodiment is configured to include a substrate and a release agent layer provided on at least one side of the substrate. The release agent layer may be laminated directly on the substrate, or may be laminated on the substrate via another layer. Furthermore, the release agent layer may be provided on both sides of the substrate.

[0018] 1. Components Constituting the Release Sheet (1) Substrate The substrate of the release sheet according to this embodiment is not particularly limited as long as it can be laminated with a release agent layer. Examples of such substrates include sheet materials made of polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene and polymethylpentene, plastics such as polycarbonate and polyvinyl acetate, and papers such as fine paper, coated paper, glassine paper, kraft paper, and polyethylene-laminated paper. These sheet materials may be single-layered or multi-layered, consisting of two or more layers of the same or different materials.

[0019] When forming a pressure-sensitive adhesive layer with high thickness precision on the release surface of a release sheet (the surface of the release agent layer opposite the substrate) or when forming a ceramic green sheet, it is preferable to use a plastic film as the substrate. Among these, polyester film is preferred, and polyethylene terephthalate film is particularly preferred, with biaxially oriented polyethylene terephthalate film being even more preferred. Polyethylene terephthalate film is less likely to generate dust during processing, use, etc., and can effectively prevent, for example, coating defects caused by dust, etc. Furthermore, by subjecting polyethylene terephthalate film to an antistatic treatment, the effect of preventing coating defects, etc. can be enhanced.

[0020] Furthermore, when a plastic film is used as the substrate, one or both sides of the film may be subjected to a surface treatment such as an oxidation method or a roughening method, or a primer treatment, if desired, in order to improve adhesion to a release agent layer provided on the surface. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone treatment, and ultraviolet irradiation treatment, and examples of the roughening method include sandblasting and thermal spray treatment. These surface treatment methods are appropriately selected depending on the type of plastic film, but corona discharge treatment is generally preferred in terms of effectiveness and operability.

[0021] The thickness of the substrate can be appropriately set depending on the use of the release sheet. Generally, from the viewpoint of handling, it is preferably 10 μm or more, particularly preferably 15 μm or more, and more preferably 20 μm or more. From the same viewpoint, the thickness of the substrate is preferably 300 μm or less, particularly preferably 200 μm or less, and more preferably 125 μm or less.

[0022] (2) Release Agent Layer In this embodiment, the release agent layer is formed from a release agent composition containing an alicyclic epoxy group-containing cyclic siloxane compound (A), a carbinol-modified polyorganosiloxane (B), and an acid catalyst (C). In this release agent composition, the amount of the carbinol-modified polyorganosiloxane (B) blended per 100 parts by mass of the alicyclic epoxy group-containing cyclic siloxane compound (A) is 3 parts by mass or more and 15 parts by mass or less.

[0023] In the release agent layer, when the release agent composition is used to form the layer, the alicyclic epoxy group-containing cyclic siloxane compound (A) undergoes a condensation reaction under the action of the acid catalyst (C), and the epoxy groups of the alicyclic epoxy group-containing cyclic siloxane compound (A) react with the hydroxyl groups of the carbinol-modified polyorganosiloxane (B). This is thought to result in the formation of a structure in which the cured product of the alicyclic epoxy group-containing cyclic siloxane compound (A) and the carbinol-modified polyorganosiloxane (B) are integrated. This structure makes it difficult for the silicone component to migrate from the release agent layer, and allows the release force to be set low. In particular, by blending the carbinol-modified polyorganosiloxane (B) in the above-mentioned amount with the alicyclic epoxy group-containing cyclic siloxane compound (A), the surface free energy of the release surface of the resulting release agent layer is effectively reduced, thereby reducing the release force. Furthermore, by adjusting the blending amount of the carbinol-modified polyorganosiloxane (B) relative to the alicyclic epoxy group-containing cyclic siloxane compound (A) to the above-mentioned amount or less, migration of the silicone component from the release agent layer can be effectively suppressed.

[0024] (2-1) Components (2-1-1) Alicyclic Epoxy Group-Containing Cyclic Siloxane Compound (A) The alicyclic epoxy group-containing cyclic siloxane compound (A) has a cyclic siloxane skeleton in which a plurality of siloxane units (—Si—O) form a cyclic structure. The number of siloxane units in the cyclic siloxane skeleton is preferably 4 to 6, more preferably 4 to 5, and most preferably 4.

[0025] In the alicyclic epoxy group-containing cyclic siloxane compound (A), an alicyclic epoxy group is directly or indirectly bonded to a silicon atom of the cyclic siloxane skeleton. Examples of the alicyclic epoxy group include a 2,3-epoxycyclobutyl group, a 2,3-epoxycyclopentyl group, a 3,4-epoxycyclohexyl group, a 5,6-epoxy-tricyclo[5,2,1,0 ２,６ ] decan-8-yl group, 2,3-epoxy-tricyclo[4,2,1,0 ２,５]nonan-7-yl group, 3-(3,4-epoxycyclohexyl)-9-hydroxy-1,5-dioxaspiro[5,5]undecan-8-yl group, 3-(3,4-epoxycyclohexyl)-9-hydroxy-2,4-dioxaspiro[5,5]undecan-8-yl group, etc. Among the above, the 3,4-epoxycyclohexyl group is particularly preferred.

[0026] When an alicyclic epoxy group is indirectly bonded to a silicon atom of a cyclic siloxane skeleton, it is preferably bonded via an alkyl chain, in which case the alkyl chain preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms.

[0027] The alicyclic epoxy group-containing cyclic siloxane compound (A) is particularly a compound represented by the following formula (a1): (In the formula, R １ is an alkyl group.) By using this compound, the above-mentioned effects, i.e., the effect of reducing the release force and the effect of inhibiting the migration of the silicone component, are more excellent.

[0028] R in the above formula (a1) １ is preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

[0029] In the release agent composition of this embodiment, the alicyclic epoxy group-containing cyclic siloxane compound (A) is preferably the main component. The specific content of the alicyclic epoxy group-containing cyclic siloxane compound (A) in the release agent composition is preferably 85% by mass or more, more preferably 88% by mass or more. The upper limit of this content is the amount that allows the carbinol-modified polyorganosiloxane (B) and the acid catalyst (C) to be blended, and is preferably 97% by mass or less, more preferably 95% by mass or less.

[0030] (2-1-2) Carbinol-modified polyorganosiloxane (B) The carbinol-modified polyorganosiloxane (B) is a —CH ２ an organic group represented by —OH, or —CH ２The carbinol-modified polyorganosiloxane (B) in this embodiment is a polyorganosiloxane having an organic group having an —OH structure in part of the molecule. Or, an organic group represented by the following general formula (b2): In particular, from the viewpoint of effectively suppressing the migration of the polyorganosiloxane from the release agent layer, it is preferable that the carbinol-modified polyorganosiloxane (B) has an organic group represented by the general formula (b1) or general formula (b2) at both ends or on a side chain, and from the viewpoint of achieving a smaller release force, it is preferable that the carbinol-modified polyorganosiloxane (B) has an organic group represented by the general formula (b1) or general formula (b2) at both ends.

[0031] In the above general formula (b1), R ２ is an alkylene group having 1 to 6 carbon atoms. When a plurality of organic groups represented by the general formula (b1) are present in one molecule of the carbinol-modified polyorganosiloxane (B), the plurality of R ２ are each independently an alkylene group having 1 to 6 carbon atoms.

[0032] In the above general formula (b2), R ３ is an alkylene group having 1 to 6 carbon atoms, and R ４ is an alkylene group having 2 to 3 carbon atoms. When a plurality of organic groups represented by general formula (b2) are present in one molecule of the carbinol-modified polyorganosiloxane (B), the plurality of R ３ are each independently an alkylene group having 1 to 6 carbon atoms, and a plurality of R ４ are each independently an alkylene group having 2 to 3 carbon atoms.

[0033] The carbinol-modified polyorganosiloxane (B) preferably has an overall structure represented by the following general formula (b3):

[0034] In formula (b3), n is an integer of 1 or more. ５ ~R１２ At least one of the groups is preferably an organic group represented by the above general formula (b1) or an organic group represented by the above general formula (b2).

[0035] In formula (b3), R ５ ~R １２ Of these, groups other than the above-mentioned groups are preferably alkyl groups having 1 to 8 carbon atoms. Examples of alkyl groups having 1 to 8 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, and hexyl groups, with methyl being particularly preferred.

[0036] R ５ ~R １２ may be the same or different. ５ If there are multiple R ５ may be the same or different, R ６ If there are multiple R ６ may be the same or different.

[0037] The weight average molecular weight of the carbinol-modified polyorganosiloxane (B) is preferably 1,000 or more, particularly preferably 3,000 or more, and even more preferably 5,000 or more. This makes it easier to lower the surface free energy on the release surface of the release agent layer, making it easier to achieve a small release force. Furthermore, the weight average molecular weight is preferably 10,000 or less, particularly preferably 9,000 or less, and even more preferably 8,000 or less. This makes it possible to prevent the carbinol-modified polyorganosiloxane (B) component from migrating to the ceramic green sheet or the adhesive layer. Note that the weight average molecular weight in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0038] The amount of carbinol-modified polyorganosiloxane (B) per 100 parts by mass of alicyclic epoxy group-containing cyclic siloxane compound (A) is 3 parts by mass or more, preferably 4 parts by mass or more. This allows the action of the carbinol-modified polyorganosiloxane (B) to be effectively exerted, making it easier to lower the surface free energy on the release surface of the release agent layer and making it easier to achieve a small release force. Furthermore, the amount of carbinol-modified polyorganosiloxane (B) per 100 parts by mass of alicyclic epoxy group-containing cyclic siloxane compound (A) is 15 parts by mass or less, preferably 13 parts by mass or less, and particularly preferably 11 parts by mass or less. This prevents the release agent layer from containing excessive amounts of components derived from the carbinol-modified polyorganosiloxane (B) and can effectively suppress the migration of silicone components from the release agent layer.

[0039] (2-1-3) Acid Catalyst In this embodiment, the acid catalyst (C) contributes to efficient progress of the condensation reaction of the alicyclic epoxy group-containing cyclic siloxane compound (A) and the reaction between the epoxy groups of the alicyclic epoxy group-containing cyclic siloxane compound (A) and the hydroxyl groups of the carbinol-modified polyorganosiloxane (B).

[0040] The acid catalyst (C) is preferably a photocation catalyst (photoacid generator) that generates cationic species upon irradiation with light (ultraviolet light). The photocation catalyst allows the above reaction to proceed efficiently upon irradiation with light.

[0041] Examples of photocationic catalysts include onium salts such as iodonium salts, sulfonium salts, phosphonium salts, diazonium salts, ammonium salts, and pyridinium salts; metallocene compounds such as iron arene complexes; sulfone compounds such as β-ketoesters, β-sulfonyl sulfones, and their α-diazo compounds; sulfonate esters such as alkylsulfonate esters, haloalkylsulfonate esters, arylsulfonate esters, and iminosulfonates; sulfonimide compounds; and diazomethane compounds, and these may be used singly or in combination of two or more.

[0042] Among the above, onium salts such as iodonium salts, sulfonium salts, phosphonium salts, diazonium salts, ammonium salts, and pyridinium salts are preferred, and iodonium salts are particularly preferred, as these easily generate cationic species upon irradiation with light (ultraviolet light), allowing the above reaction to proceed very efficiently.

[0043] The content of the acid catalyst (C) in the release agent composition in this embodiment is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and even more preferably 0.8% by mass or more, and is preferably 5% by mass or less, particularly preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0044] (2-1-4) Other Components In addition to the above components, the release agent composition may contain a crosslinking agent, a reaction inhibitor, an adhesion improver, a slipping agent, and the like.

[0045] (2-2) Thickness of Release Agent Layer The thickness of the release agent layer is preferably 0.01 μm or more, more preferably 0.02 μm or more, particularly preferably 0.03 μm or more, and even more preferably 0.04 μm or more. This allows for good releasability. The thickness of the release agent layer is also preferably 3 μm or less, more preferably 2 μm or less, particularly preferably 1 μm or less, and even more preferably 0.05 μm or less. This effectively prevents blocking from occurring when the release sheet is wound into a roll.

[0046] 2. Physical Properties of the Release Sheet (1) Peel Strength from Adhesive Tape In the release sheet according to this embodiment, the adhesive surface of an adhesive tape (manufactured by Nitto Denko Corporation, product name "31B Tape") is applied to the release surface of the release agent layer, and the peel strength when the adhesive tape is peeled from the release sheet after 30 minutes is preferably less than 400 mN / 20 mm, more preferably less than 300 mN / 20 mm. This reduces the occurrence of peel failures when peeling the release sheet from a thin film material (e.g., an adhesive layer, a ceramic green sheet, etc.) laminated on the release agent layer of the release sheet according to this embodiment. The release sheet according to this embodiment can easily achieve the low peel strength described above. Meanwhile, in consideration of handleability, the peel strength is preferably 10 mN / 20 mm or more, and particularly preferably 20 mN / 20 mm or more. Details of the method for measuring the peel strength from an adhesive tape in this specification are as described in the test examples below.

[0047] (2) Peel Strength from Ceramic Green Sheets In the release sheet according to this embodiment, the peel force required to peel the release sheet from the ceramic green sheet formed on its release surface is preferably less than 20 mN / 40 mm, and more preferably less than 18 mN / 40 mm. This allows the release sheet to be peeled from the ceramic green sheet without any problems. The release sheet according to this embodiment can easily achieve the low peel force described above. On the other hand, in consideration of handling, the peel force is preferably 1 mN / 40 mm or more, and particularly preferably 2 mN / 40 mm or more. This makes it easier to prevent the ceramic green sheet from unintentionally detaching from the release sheet. Details of the method for measuring the peel force from ceramic green sheets in this specification are as described in the test examples below.

[0048] (3) Silicone Migration Amount In the release sheet according to this embodiment, after forming a polyvinyl butyral resin layer on the release agent layer, when the polyvinyl butyral resin layer is peeled off from the release agent layer, the silicon atom ratio as the amount of silicone migration on the surface of the polyvinyl butyral resin layer that was in contact with the release agent layer is preferably less than 0.2 atomic %, more preferably 0.1 atomic % or less, even more preferably less than 0.1 atomic %, and most preferably 0 atomic %. The silicon atom ratio is calculated using the following formula based on the amounts (XPS counts) of silicon atoms (Si), carbon atoms (C), and oxygen atoms (O). A specific method for measuring the silicon atom ratio is as shown in the test examples described below. Silicon atom ratio (atomic %) = [(Si element amount) / {(C element amount) + (O element amount) + (Si element amount)}] × 100

[0049] In most cases, the polyvinyl butyral resin layer itself contains no detectable silicon by XPS, and therefore the silicon atom ratio can be used as an evaluation standard for the amount of migration of the silicone-based compound, which is the release-imparting component of the release agent layer.

[0050] By ensuring that the silicon atom ratio of the surface of the polyvinyl butyral resin layer that was in contact with the release agent layer is within the above range, when a ceramic green sheet is formed on the release agent layer, it is possible to suppress the migration of silicone contained in the release agent layer to the ceramic green sheet. The release sheet according to this embodiment can easily achieve the low amount of silicone migration described above.

[0051] 3. Method for Producing Release Sheet The release sheet according to this embodiment can be obtained by applying a coating liquid containing the release agent composition described above and, if desired, an organic solvent to one side of a substrate, drying the coating, and curing the coating by irradiation with light (ultraviolet light) to form a release agent layer. Examples of coating methods that can be used include gravure coating, bar coating, spray coating, spin coating, knife coating, roll coating, and die coating.

[0052] The organic solvent is not particularly limited, and various solvents 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, cyclohexanone, and mixtures thereof can be used. In particular, it is preferable to use a mixed solvent of isopropyl alcohol, methyl ethyl ketone, and cyclohexanone.

[0053] The ultraviolet irradiation device used for ultraviolet irradiation is not particularly limited, but examples thereof include an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED lamp, and a black light.

[0054] The ultraviolet irradiance is 1 to 3000 mW / cm ２ is preferred, and in particular 200 to 2000 mW / cm ２ and more preferably 800 to 1800 mW / cm ２ The amount of ultraviolet light is preferably 10 to 1000 mJ / cm. ２ is preferred, and in particular 20 to 600 mJ / cm ２ and more preferably 40 to 300 mJ / cm ２ When the illuminance and light amount of the ultraviolet light are within the above ranges, the release agent composition is cured well, and the resulting release agent layer exhibits good releasability.

[0055] 4. Uses of Release Sheet The release sheet according to this embodiment can be used for the same purposes as general release sheets.

[0056] For example, the release sheet according to this embodiment can be used in the manufacture of a pressure-sensitive adhesive sheet. In this case, a coating liquid of a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is applied to the release surface of the release sheet according to this embodiment, and then dried to form a pressure-sensitive adhesive layer. A pressure-sensitive adhesive sheet with a release sheet attached can then be manufactured by laminating a substrate for the pressure-sensitive adhesive sheet on the side of the pressure-sensitive adhesive layer opposite the release sheet. Alternatively, a double-sided pressure-sensitive adhesive sheet consisting of two release sheets and a pressure-sensitive adhesive layer laminated therebetween can be manufactured by laminating another release sheet, preferably the release surface of the release sheet according to this embodiment, to the side of the pressure-sensitive adhesive layer formed as described above opposite the release sheet. Furthermore, the manufactured pressure-sensitive adhesive sheet can be stored with the release sheet attached, thereby protecting the adhesive surface of the pressure-sensitive adhesive sheet with the release sheet attached.

[0057] The release sheet according to this embodiment can also be used to produce a ceramic green sheet. For example, a ceramic slurry containing a ceramic material such as barium titanate or titanium oxide can be applied to the release surface of the release sheet, and then the ceramic slurry can be dried to form a ceramic green sheet on the release surface of the release sheet.

[0058] Furthermore, the release sheet according to the present embodiment can also be used as a process sheet when manufacturing sheet materials such as various resin sheets, synthetic leather, various composite materials, etc. For example, it can be used as a process sheet used in a process of forming a sheet material by casting or applying a resin or the like onto the release surface of the release sheet.

[0059] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, 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.

[0060] For example, other layers such as an antistatic layer may be provided on the surface of the substrate of the release sheet opposite to the release agent layer, or between the substrate and the release agent layer.

[0061] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0062] Examples 1 to 5 and Comparative Examples 1 to 4 The alicyclic epoxy group-containing cyclic siloxane compound (A) has the structure of the above-described formula (a1), and R １ is CH ３ A 3,4-epoxycyclohexyl group-containing silane oligomer (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KR-470") was prepared.

[0063] Further, as the carbinol-modified polyorganosiloxane (B), both terminal carbinol-modified polydimethylsiloxane (B1; manufactured by Shin-Etsu Chemical Co., Ltd., product name "KF-6001"), both terminal carbinol-modified polydimethylsiloxane (B2; manufactured by Shin-Etsu Chemical Co., Ltd., product name "KF-6002"), and both terminal carbinol-modified polydimethylsiloxane (B3; manufactured by Shin-Etsu Chemical Co., Ltd., product name "KF-6003") were prepared.

[0064] The weight average molecular weights of the above "KF-6001," "KF-6002," and "KF-6003" were measured using a GPC device (manufactured by Tosoh Corporation, product name "HLC-8320GPC"), and the results were as follows: "KF-6001"...2,400 "KF-6002"...4,600 "KF-6003"...8,000

[0065] To 100 parts by mass (solids content equivalent; the same applies hereinafter) of the alicyclic epoxy group-containing cyclic siloxane compound (A), 1 to 20 parts by mass of the carbinol-modified polyorganosiloxane (B) shown in Table 1 was added. The solution was then diluted with an isopropyl alcohol / methyl ethyl ketone / cyclohexanone mixed solvent (mass ratio 7 / 2 / 1) to a solids concentration of 1 mass%. Next, 1 part by mass of an iodonium salt photocationic catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., product name "CAT-7605") serving as the acid catalyst (C) was added to this solution, thereby obtaining a coating solution of a release agent composition.

[0066] The obtained coating solution of the release agent composition was uniformly applied to a biaxially stretched polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name "Diafoil T100-38", thickness 38 μm) as a substrate using a bar coater. Then, after heating and drying at 80°C for 30 seconds, the film was irradiated with ultraviolet light (integrated light amount 60 mJ / m ２ , illuminance 1500mW / cm ２ ) to cure the release agent composition, thereby obtaining a release sheet having a release agent layer of 0.05 μm (50 nm) formed on the substrate.

[0067] The thickness of the release agent layer was measured using a spectroscopic ellipsometer (manufactured by J.A. Woollam Japan, product name "M-2000").

[0068] Comparative Example 5 A coating solution of a release agent composition was prepared in the same manner as in Example 1, except that the carbinol-modified polyorganosiloxane (B) was changed to an epoxy-modified polydimethylsiloxane (B4; product name "X-62-7622" manufactured by Shin-Etsu Chemical Co., Ltd.) (amount blended: 10 parts by mass). Note that although the epoxy-modified polydimethylsiloxane is not the carbinol-modified polyorganosiloxane (B), for the sake of convenience, the blending amount is shown in the column for carbinol-modified polyorganosiloxane (B) in Table 1.

[0069] A release sheet was produced in the same manner as in Example 1 using the obtained coating liquid of the release agent composition.

[0070] Comparative Example 6 94 parts by mass of dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-DPH") as the active energy ray-curable compound, 1 part by mass of polyether-modified acryloyl group-containing polydimethylsiloxane (manufactured by BYK Japan, product name "BYK-3500") as the polyorganosiloxane, and 5 parts by mass of an α-aminoalkylphenone photopolymerization initiator (manufactured by IGM Resin B.V., product name "Omnirad 907", 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one) as the photopolymerization initiator were diluted with an isopropyl alcohol / methyl ethyl ketone mixed solvent (mass ratio 3 / 1) to obtain a coating liquid of a release agent composition (UV-curable acrylate release agent) with a solids content of 20% by mass.

[0071] The obtained coating solution of the release agent composition was uniformly applied to a biaxially stretched polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name "Diafoil T100-38", thickness 38 μm) as a substrate using a bar coater. Then, after heating and drying at 80°C for 1 minute, the film was irradiated with ultraviolet light (cumulative light amount 250 mJ / m ２ , illuminance 1500mW / cm ２ ) to cure the release agent composition, thereby obtaining a release sheet having a release agent layer of 1.2 μm (1200 nm) formed on the substrate.

[0072] Comparative Example 7 A mixture of 90 parts by mass (solid content equivalent, the same applies hereinafter) of a methylated melamine resin (manufactured by Sanwa Chemical Co., Ltd., product name "MW-30MLF", weight average molecular weight: 714) as the melamine resin, 10 parts by mass of polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., product name "PEG-400", weight average molecular weight: 401) as the polyalkylene glycol, and 10 parts by mass of a polyether-modified hydroxyl group-containing polydimethylsiloxane (manufactured by BYK Japan KK, product name "BYK-377", number average molecular weight: 100%) as the polyorganosiloxane was used. 5 parts by mass of a melamine resin-based release agent (Mn: 5078, weight average molecular weight (Mw): 5993, molecular weight distribution (Mw / Mn): 1.18), 5.0 parts by mass of a modified acrylic block copolymer (manufactured by BYK Japan, product name "DISPERBYK-2025", wetting dispersant) as a dispersant, and 5 parts by mass of p-toluenesulfonic acid as a catalyst were mixed in an isopropyl alcohol / methyl ethyl ketone mixed solvent (mass ratio 5 / 5) to obtain a coating liquid of a release agent composition (thermosetting melamine resin-based release agent) with a solids content of 3% by mass.

[0073] The obtained coating solution was uniformly applied using a bar coater onto one side of a biaxially stretched polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name "Diafoil T100-38", thickness 38 μm) as a substrate. The obtained coating film was then dried and cured by heating at 135°C for 1 minute, yielding a release sheet in which a release agent layer having a thickness of 1.0 μm (1000 nm) was formed on the substrate.

[0074] The details of the abbreviations and the like in Table 1 are as follows: [Carbinol-modified polyorganosiloxanes (B)] B1: Polydimethylsiloxane modified at both ends with carbinol (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KF-6001") B2: Polydimethylsiloxane modified at both ends with carbinol (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KF-6002") B3: Polydimethylsiloxane modified at both ends with carbinol (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KF-6003") B4: Epoxy-modified polydimethylsiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "X-62-7622")

[0075] Test Example 1 (Measurement of Peel Force from Adhesive Tape) A 20 mm wide adhesive tape (manufactured by Nitto Denko Corporation, product name "No. 31B") was attached to the release surface of the release sheets produced in the Examples and Comparative Examples using a 2 kg roller to prepare a sample for measuring peel force. After storing at 23°C for 30 minutes, the sample was fixed to a universal tensile tester (manufactured by Shimadzu Corporation, product name "Autograph AGS-20NX"), and the peel force (mN / 20 mm) of the release sheet was measured by peeling the adhesive tape from the release agent layer in a 180° direction at a tensile speed of 0.3 m / min in accordance with JIS K6854:1999. The results are shown in Table 1.

[0076] Based on the results of the peel strength measurements, the peel strength of the adhesive tape was evaluated according to the following criteria. The results are shown in Table 1. ⊚: peel strength less than 300 mN / 20 mm; ◯: peel strength 300 mN / 20 mm or more but less than 400 mN / 20 mm; ×: peel strength 400 mN / 20 mm or more.

[0077] [Test Example 2] (Measurement of peel strength from ceramic green sheet) Barium titanate powder (BaTiO ３ A ceramic slurry was prepared by adding 135 parts by mass of a mixed liquid of glycol monomethyl ether and toluene (mass ratio 50:50), and mixing and dispersing the mixture in a ball mill, to 100 parts by mass of a polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd., product name "S-LEC B.K BM-2") as a binder, 8 parts by mass of a polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd., product name "Dioctyl Phthalate Grade 1") as a plasticizer.

[0078] The ceramic slurry was applied to the release surface of the release sheets produced in the Examples and Comparative Examples over a width of 250 mm and a length of 10 m using a die coater, and then dried in a dryer at 80°C for 1 minute to form a ceramic green sheet with a thickness of 1 μm. The resulting ceramic green sheet with release sheet was left to stand for 24 hours in an atmosphere of 23°C and 50% RH. Next, the ceramic green sheet with release sheet was cut into a 40 mm width to serve as a measurement sample.

[0079] The release sheet side of the measurement sample was fixed to a flat plate, and the ceramic green sheet was peeled from the release agent layer of the release sheet at a peel angle of 90° and a peel rate of 0.3 m / min using a tensile tester (manufactured by Shimadzu Corporation, product name "AG-IS500N"), and the peel force (mN / 40 mm) at this time was measured. The results are shown in Table 1.

[0080] Based on the results of the peel force measurements, the peel force for the ceramic green sheet was evaluated according to the following criteria. The results are shown in Table 1. ⊚: peel force less than 18 mN / 40 mm; ◯: peel force 18 mN / 40 mm or more but less than 20 mN / 40 mm; ×: peel force 20 mN / 40 mm or more.

[0081] Test Example 3 (Measurement of Silicone Migration Amount) 240 parts by weight of toluene and 160 parts by weight of ethanol were added as a mixed solvent to 100 parts by weight of polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd., product name "S-LEC BL-S"; hereinafter referred to as "PVB"), and the mixture was stirred and mixed uniformly using a disper to prepare a PVB coating liquid. The PVB coating liquid was then applied to the release surface of the release sheets produced in the Examples and Comparative Examples using an applicator, and dried to form a PVB layer. The film thickness of the PVB layer after drying was 3 μm.

[0082] After the dried PVB layer was peeled off from the release sheet, the amount of silicone transferred to the PVB resin surface that had been in contact with the release surface of the release sheet was measured by X-ray photoelectron spectroscopy (XPS). Specifically, the silicon atom ratio (atomic %) was calculated using the following formula based on the amounts of silicon atoms (Si), carbon atoms (C), and oxygen atoms (O) (XPS count numbers). The results are shown in Table 1. Silicon atom ratio (atomic %) = [(Si element amount) / {(C element amount) + (O element amount) + (Si element amount)}] x 100

[0083] Based on the results of the silicon atom ratio measurement, silicone migration was evaluated according to the following criteria. The results are shown in Table 1. ⊚: silicon atom ratio less than 0.1 atomic % ◯: silicon atom ratio 0.1 atomic % or more but less than 0.2 atomic % ×: silicon atom ratio 0.2 atomic % or more

[0084]

[0085] As is clear from Table 1, the release sheets produced in the examples had low release strength and were less susceptible to migration of the silicone component from the release agent layer.

[0086] The release sheet of the present invention is suitably used, for example, as a release sheet onto which an adhesive layer of an adhesive sheet is laminated, or as a release sheet for producing a ceramic green sheet.

Claims

1. 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 formed from a release agent composition containing an alicyclic epoxy group-containing cyclic siloxane compound (A), a carbinol-modified polyorganosiloxane (B), and an acid catalyst (C), and the blending amount of the carbinol-modified polyorganosiloxane (B) with respect to 100 parts by mass of the alicyclic epoxy group-containing cyclic siloxane compound (A) is 3 parts by mass or more and 15 parts by mass or less. The release sheet is characterized by this.

2. The alicyclic epoxy group-containing cyclic siloxane compound (A) is represented by the following formula (a1): (In the formula, R １ is an alkyl group.) The release sheet according to claim 1, characterized in that it is a compound represented by the formula.

3. The carbino-modified polyorganosiloxane (B) has an organic group represented by the following general formula (b1): (In the general formula (b1), R ２ is an alkylene group having 1 to 6 carbon atoms.) or an organic group represented by the following general formula (b2): (In the general formula (b2), R ３ is an alkylene group having 1 to 6 carbon atoms, and R ４ is an alkylene group having 2 to 3 carbon atoms.) The release sheet according to claim 1, which is a polyorganosiloxane having the group at both ends, one end or a side chain.

4. The release sheet according to claim 1, wherein the weight average molecular weight of the carbinol-modified polyorganosiloxane (B) is 1000 or more and 10000 or less.

5. The release sheet according to claim 1, which is for a ceramic green sheet manufacturing process.

6. The release sheet according to claim 1, which is for an adhesive sheet.

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