WO2015068859A1

WO2015068859A1 - Curable organopolysiloxane composition and release film for use with dielectric ceramic layer-forming material using same

Info

Publication number: WO2015068859A1
Application number: PCT/JP2014/080285
Authority: WO
Inventors: Shuji Endo
Original assignee: Dow Corning Toray Co Ltd
Current assignee: DuPont Toray Specialty Materials KK
Priority date: 2013-11-11
Filing date: 2014-11-11
Publication date: 2015-05-14
Anticipated expiration: 2016-05-11
Also published as: KR20160085864A; TWI651376B; CN105899616B; JP6469122B2; KR102348902B1; TW201522540A; JP2017503903A; CN105899616A

Abstract

A curable organopolysiloxane composition comprising: (A) an organopolysiloxane having a form of anywhere from a liquid having a viscosity of 20 mPa⋅s or greater to a gum that exhibits plasticity,containing the following components a1) and a2) at a mass ratio of 100:0 to 50:50: a1) organopolysiloxane comprising an alkenyl group having 4 to 12 carbon atoms, the alkenyl group having a vinyl moiety content of 0.5 to 3.0 mass%, and a2) organopolysiloxane with an alkenyl group having 2 to 3 carbon atoms, the alkenyl group having a vinyl moiety content of 0.5 to 3.0 mass%; (B) an organopolysiloxane having a form from a liquid having a viscosity of 1,000,000 mPas or greater to a gum that exhibits plasticity, the organopolysiloxane optionally comprising an alkenyl group having 2 to 12 carbon atoms, the alkenyl group having a vinyl moiety content of less than 0.100 mass%; (C) an organohydrogen polysiloxane comprising at least two silicon-bonded hydrogen atoms within its molecule; (D) a hydrosilylation catalyst; and (E) as desired, an organic solvent; the mass ratio of components (A) and (B) being in a range from 90:10 to 99:1.

Description

DESCRIPTION

CURABLE ORGANOPOLYSILOXANE COMPOSITION AND RELEASE FILM FOR USE WITH DIELECTRIC CERAMIC LAYER-FORMING MATERIAL USING SAME

Field of the Invention

[0001] The present invention relates to a curable organopolysiloxane composition and a release film for use with a dielectric ceramic layer-forming material using the same, especially to a release film for forming a ceramic green sheet.

Background

[0002] Conventionally, when manufacturing multilayered ceramic products such as multilayer ceramic capacitors, multilayer inductors, and multilayer ceramic circuit boards, especially multilayer ceramic electrical components, a method in which an unfired ceramic material is mixed, as necessary, with a binder and solvent or the like to form a paste-like mixture, which is applied to a plastic carrier film and dried to form a dielectric ceramic layer- forming material, generally a sheet known as a "ceramic green sheet", after which an internal electrode material having a form of a paste is printed upon the ceramic green sheet to form an internal electrode, a plurality of ceramic green sheets and stacked with so that their electrode patterns are aligned, and the sheets are compressed into a single piece and fired to manufacture a multilayer ceramic product, especially a multilayer ceramic electronic component, is known.

[0003] A ceramic green sheet can be produced, for example, by applying a ceramic slurry containing a ceramic material such as barium titanate or titanium oxide, a dispersion medium, and the like to a release film, then drying the slurry. The ceramic green sheet obtained by applying the ceramic slurry to the release film, also referred to as a "carrier film", and drying the slurry is separated from the release film in a subsequent step no later than before firing the ceramic. An example of a typical release film is one in which the surface of a base film of polyethylene terephthalate or the like is treated with a silicone- based compound such as a polysiloxane so that the film is capable of separating from ceramic green sheets (patent documents 1-8). Such release films must have release properties such that the thin ceramic green sheet formed upon the release film can be removed from the release film without breaking.

[0004] As electronic devices have become more compact in size and capable of higher performance, multilayer ceramic capacitors and multilayer ceramic boards have likewise become more compact in size and composed of greater numbers of layers, with a concurrent reduction in the thickness of ceramic green sheets.

[0005] The inventors have already proposed, as a material capable of imparting a substrate film with a level of releasability suitable for use as a carrier film for a ceramic green sheet, an easy-to-handle curable organopolysiloxane composition that is capable of forming a cured layer on the surface of a substrate and imparting the surface of a substrate with satisfactory releasability with respect to tacky substances and a cured layer of slick smoothness, the composition containing (A) 100 parts by mass of at least one type of organopolysiloxane having a viscosity at 25°C of 20 to 500 mPa-s and containing 1.0 to 5.0 mass% of higher alkenyl groups comprising 4 to 12 carbon atoms, (B) 0.5 to 15 parts by mass of a liquid or gumlike organopolysiloxane having a viscosity at 25°C of at least 1 ,000,000 mPa-s and comprising 0.005 to 0.100 mass% of alkenyl groups comprising 2 to 12 carbon atoms, (C) an amount of an organohydrogen polysiloxane comprising at least two silicon-bonded hydrogen atoms (Si-H) within its molecule such that the molar ratio of SiH groups in C to alkenyl groups in (A) and (B) is 0.5 to 5, and (D) a catalytic amount of a platinum catalyst (JP 2011-026582 A).

Prior Art Documents

1. Unexamined Japanese Patent Application Publication No. 2002-011710

2. Unexamined Japanese Patent Application Publication No. 2004-182836

3. Unexamined Japanese Patent Application Publication No. 2004-216613

4. Unexamined Japanese Patent Application Publication No. 2008-254207

5. Unexamined Japanese Patent Application Publication No. 2009-034947

6. Unexamined Japanese Patent Application Publication No. 2009-215428

7. Unexamined Japanese Patent Application Publication No. 2009-227976

8. Unexamined Japanese Patent Application Publication No. 2009-227977

9. Unexamined Japanese Patent Application Publication No. 2011-026582

Summary of the Invention

Problem to be Solved by the Invention

[0006] As discussed above, it is necessary to reduce the thickness of layers constituted by dielectric ceramic layer-forming materials in order to reduce the size of and/or increase the number of layers in a multilayer ceramic capacitor or multilayer ceramic board. However, if the post-drying thickness of a ceramic slurry applied to a substrate film when producing a thin ceramic green sheet is 3 μηι or less, the edges of the applied ceramic slurry may contract after the ceramic slurry has been applied and dried, leading to the problems of edge contraction, in which the edges of the applied sheet are thicker than the inner parts, pinhole formation, and/or uneven application. Addition problems include tearing of the sheet or the like arising as the result of reductions in the strength of the ceramic green sheet when the ceramic green sheet is separated from the substrate film, i.e., the release film, due to the thinness of the sheet.

[0007] In addition, electronic materials and components manufactured using ceramic green sheets will use different types of inorganic ceramic materials, binder resins, dispersing agents, organic solvents, and the like according to purpose; thus, the ease with which a ceramic slurry can be applied to a release film varies depending on the type of ceramic slurry being applied to the release film. There remains, therefore, a demand for a release film that yields both satisfactory ease of ceramic slurry application and satisfactory ceramic green sheet releasability, regardless of the type of ceramic slurry used.

[0008] Meanwhile, as discussed above, the curable organopolysiloxane composition already disclosed by the inventors in JP 2011 -026582 A as a material for imparting the surface of a substrate film with releasability is a substantially solvent-free, i.e., non-solvent- containing, curable organopolysiloxane composition, and is useful as a material for display screen protective sheets or the like, but is not suitable as disclosed for use as a material for release films for ceramic green sheets.

[0009] The present invention was conceived in view of the circumstances described above, and has an object of providing a release film, i.e., a carrier film, for use in forming a ceramic green sheet, the film offering superior ease in applying ceramic slurry to the surface thereof and superior releasability from a ceramic green sheet formed on the surface thereof, as well as a release agent composition suitable for manufacturing said film.

Means for Solving the Problem

[0010] The inventors discovered that a release film obtained by coating a sheet-like substrate, such as a substrate film, with the below-described curable organopolysiloxane composition as a release agent composition for modifying the surface properties of a substrate for use as a release film for use with a dielectric ceramic layer-forming material, especially as a release film for forming a ceramic green sheet, followed by curing the composition, exhibits superior properties when used as a release film for use in forming a dielectric ceramic layer-forming material, especially a release film for use in forming a ceramic green sheet, thereby arriving at the present invention. To wit, the curable organopolysiloxane composition according to the present invention contains the following components (A) to (E):

(A) an organopolysiloxane or organopolysiloxane mixture having a form of anywhere

from a liquid having a viscosity of 20 mPa-s or greater at 25°C to a gum that exhibits plasticity at 25°C, the organopolysiloxane or organopolysiloxane mixture containing the following components a1 ) and a2) at a mass ratio of 100:0 to 50:50:

a1 ) at least one type of organopolysiloxane comprising an alkenyl group having 4 to 12 carbon atoms, the alkenyl group having a vinyl (CH2=CH-) moiety content of 0.5 to 3.0 mass%, and

a2) at least one type of organopolysiloxane comprising an alkenyl group having 2 to 3 carbon atoms, the alkenyl group having a vinyl (CH2=CH-) moiety content of 0.5 to 3.0 mass%;

(B) an organopolysiloxane having a form of anywhere from a liquid having a viscosity at 25°C of 1 ,000,000 mPa-s or greater to a gum that exhibits plasticity at 25°C, the organopolysiloxane comprising an alkenyl group having 2 to 12 carbon atoms, the alkenyl group having a vinyl (CH2=CH-) moiety content of at least 0.005 mass% and less than 0.100 mass%;

(C) an organohydrogen polysiloxane comprising at least two silicon-bonded hydrogen atoms (Si-H) within its molecule;

(D) a hydrosilylation catalyst; and

(E) an organic solvent as desired;

the mass ratio of components (A) and (B) being in a range from 90: 10 to 99:1 . In the context of the present invention, "plasticity" refers to plasticity as measured using a plastometer according to the method of JIS K 6249; specifically, the value (in mm) yielded when a 1 kgf load is placed upon a 4.2 g spherical sample at 25°C for three minutes. The organic solvent is an optional component of the composition, which may acceptably either contain or not contain an organic solvent. In particular, the composition according to the present invention may be in a desired form containing a desired organic solvent, such as a solution or a suspension, with a solution being especially preferable.

[0011] In addition, in the curable organopolysiloxane composition described above, the component (A) is preferably an organopolysiloxane or organopolysiloxane mixture having a form of anywhere from a liquid having a viscosity of 1 ,000,000 mPa-s or greater at 25°C to a gum that exhibits plasticity at 25°C.

[0012] A preferred component (A) of the present invention is thus a "high-polymer" organopolysiloxane or organopolysiloxane mixture, with physical properties that continuously range, as the degree of polymerization increases, from a high-viscosity liquid region to a plastic gum region. To wit, if the degree of polymerization of the

organopolysiloxane increases to the point that the viscosity at 25°C exceeds 15,000,000 mPa-s, viscosity generally becomes difficult to measure, and the organopolysiloxane transitions from a high-viscosity region (i.e., liquid) to a region in which the physical properties thereof are defined in terms of plasticity (i.e., gum). In other words, the component (A) of the present invention encompasses organopolysiloxane and

organopolysiloxane mixtures ranging from those having a degree of polymerization such that the organopolysiloxane or organopolysiloxane mixture is a liquid having a viscosity of 1 ,000,000 mPa-s or greater that can be measured at 25°C to those having higher degrees of polymerization such that the organopolysiloxane or organopolysiloxane mixture is a gum the viscosity of which cannot be easily measured at 25°C, and whose physical properties are better defined in terms of plasticity. In particular, the component (A) is preferably an organopolysiloxane or organopolysiloxane mixture having a form of anywhere from a liquid having a viscosity of 1 ,000,000 mPa-s or greater at 25°C to a gum that exhibits a plasticity of 3.0 mm or less at 25°C. Most preferably, the component (A) is an organopolysiloxane or organopolysiloxane mixture having a plasticity of 0.5 to 3.0 mm at 25°C.

[0013] In addition, it is preferable, in the component (A), that:

• component a1 ) be a1-1 ) an organopolysiloxane comprising a hexenyl group as an alkenyl group having 4 to 12 carbon atoms, the hexenyl group having a vinyl (CH2=CH-) moiety content of 0.5 to 3.0 mass%; and

• component a2) be a2-1 ) an organopolysiloxane comprising a vinyl group as an

alkenyl group having 2 to 3 carbon atoms, the vinyl group content being in a range from 0.5 to 3.0 mass%.

[0014] It is especially preferable that the alkenyl group of the component a1 -1 ) be a hexenyl group, and the alkenyl group of the component a2-1 ) be a vinyl group.

[0015] It is also preferable that the component (B) of the curable organopolysiloxane composition according to the present invention be dimethylpolysiloxane capped at both ends with dimethyl vinyl siloxy groups. The physical properties of the component (B), as in the case of the component (A), continuously range from a liquid range exhibiting high viscosity at 25°C to a gum range exhibiting plasticity, depending on the degree of polymerization. Specifically, a preferred component (B) of the present invention may be a dimethylpolysiloxane having the form of a high-viscosity liquid, or a dimethylpolysiloxane having the form of a plastic gum. It is especially preferable that the component (B) be dimethylpolysiloxane capped at both ends by dimethyl vinyl siloxy groups having a form anywhere from a liquid having a viscosity of 1 ,000,000 mPa-s or greater at 25°C to a gum having a plasticity of 3.0 mm or less. Most preferably, the component (B) is a

dimethylpolysiloxane capped at both ends with dimethyl vinyl siloxy groups having a form of a gum having a plasticity of 0.5 to 3.0 mm at 25°C.

[0016] The curable organopolysiloxane composition according to the present invention may also contain (G) a photopolymerization initiator, which allows for not only thermal curing but also curing using energy radiation (also referred to as chemically active radiation), such as UV radiation or an electron beam.

[0017] It is also preferable that the curable organopolysiloxane composition according to the present invention have an overall composition viscosity of 100 to 50,000 mPa-s.

The present invention also provides a sheet-like article comprising a cured layer formed by curing the solvent-containing curable organopolysiloxane composition described above, and a sheet-like substrate.

[0018] The cured layer of the sheet-like article may be obtained by applying 0.01 to 0.5 g/m2 of any of the solvent-containing curable organopolysiloxane compositions described above to the sheet-like substrate, then curing the applied composition using heat or a combination of heat and energy radiation.

[0019] The sheet-like substrate is preferably plastic film.

[0020] The present invention also provides a release film for use with a dielectric ceramic layer-forming material, especially a release film for forming a ceramic green sheet, constituted by the sheet-like article.

[0021] The present invention also provides a method of manufacturing a dielectric ceramic layer-forming material, especially a ceramic green sheet, the method comprising a step of using the release film for use with a dielectric ceramic layer-forming material or release film for forming a ceramic green sheet as a carrier film, applying a ceramic slurry onto the cured organopolysiloxane layer on the film, and drying the applied slurry.

Effect of the Invention

[0022] A release sheet or release film for use with a dielectric ceramic layer-forming material or release film for forming a ceramic green sheet according to the present invention obtained using a release agent composition constituted by the curable polyorganosiloxane composition according to the present invention allows for superior ease of application of a ceramic slurry onto the film. Specifically, applying ceramic slurry to the surface of a cured layer obtained by curing the release agent composition constituted by the curable polyorganosiloxane composition according to the present invention, followed by curing the slurry, allows for the minimization of edge contraction, in which the edges of the applied ceramic slurry contract, causing the edges to be thicker than the inner parts. In addition, a release film or release film for use with a dielectric ceramic layer-forming material or release film for forming a ceramic green sheet according to the according to the present invention obtained using the release agent composition according to the present invention exhibits superior releasability from a ceramic green sheet formed thereupon, allowing the ceramic green sheet to be removed from the release agent layer of the film, i.e., carrier film, with little peeling force.^'

Best Mode for Carrying out the Invention

[0023] As discussed above, the present invention provides a release sheet for use in forming a ceramic green sheet that allows for superior ease of release of a dielectric ceramic layer-forming material, especially a ceramic green sheet, from a release film, and superior ease of applying a ceramic slurry to the film, as well as a curable

organopolysiloxane composition suitable for manufacturing the release sheet. The curable organopolysiloxane composition according to the present invention is characterized in containing the components (A) to (D) listed above, as well as the optional component (E) if desired. An especially preferable embodiment contains the component (E). The various components of the curable organopolysiloxane composition, the sheet-like article manufactured using the composition according to the present invention, and the release sheet for use in forming a ceramic green sheet will now be described in detail.

[0024] In the context of the present specification, the viscosity of the organopolysiloxane at 25°C is the value measured using a rotational viscometer. "Plasticity" refers to plasticity as measured using a plastometer according to the method of JIS K 6249; specifically, the value (in mm) yielded when a 1 kgf load is placed upon a 4.2 g spherical sample at 25°C for three minutes.

Component A

[0025] The component (A) of the curable organopolysiloxane composition according to the present invention is an organopolysiloxane or organopolysiloxane mixture having a form of anywhere from a liquid having a viscosity of 20 mPa-s or greater at 25°C to a gum that exhibits plasticity at 25°C and containing the following components a1 ) and a2) at a mass ratio of 100:0 to 50:50.

a1 ) At least one type of organopolysiloxane comprising an alkenyl group having 4 to 12 carbon atoms, the alkenyl group having a vinyl (CH2=CH-) moiety content of 0.5 to 3.0 mass%.

a2) At least one type of organopolysiloxane comprising an alkenyl group having 2 to 3 carbon atoms, the alkenyl group having a vinyl (CH2=CH-) moiety content of 0.5 to 3.0 mass%.

[0026] Thus, the component (A) either is constituted only by the component a1 ) or is a mixture of components a1 ) and a2), and is therefore constituted by one or more types of organopolysiloxane.

Component a1

[0027] The component a1 ) forming part of the component (A) can be selected from straight-chain organopolysiloxanes, branched-chain organopolysiloxanes, and straight- chained and branched-chain having a partial ring structure; from an industrial perspective, a straight-chain organopolysiloxane represented by the following chemical formula (1 ) is preferable.

Formula 1

[0028] In the formula, each R11 independently represents an unsubstituted or halogen- substituted alkyl group (such as a methyl group) having from 1 to 20 carbon atoms, an aryl group (such as a phenyl group) having from 6 to 22 carbon atoms, an alkenyl group (a vinyl group or allyl group) having 2 or 3 carbon atoms, or a hydroxyl group. Ra is an alkenyl group having from 4 to 12 carbon atoms. R is a group represented by R11 or Ra. m is a number equal to 0 or greater, and n is a number equal to 1 or greater. The values of m, n, and R are such that the vinyl (CH2=CH-) moiety content of the alkenyl groups having 4 from to 12 carbon atoms in the molecule of the organopoiysiloxane represented by formula 1 above is from 0.5 to 3.0 mass%.

[0029] For example, if R at both ends of formula (1 ) is an alkenyl group (Ra), the vinyl (CH2=CH-) moiety of these alkenyl groups is represented by the following formula:

{(molecular weight of vinyl moieties in Ra: approx. 27) χ (m + 2)}/overall molecular weight * 100 (mass%) and, in formula (1), the component a1 ) is an organopoiysiloxane in which the vinyl (CH2=CH-) moiety content of the alkenyl group having 4 to 12 carbon atoms is in a range from 0.5 to 3.0 mass%, more preferably from 1.0 to 2.0 mass%. It is also preferable that, in the component a1 ), the sum of m + n in formula (1 ) be a number in a range such that the viscosity of the organopoiysiloxane represented by formula (1) at 25°C is 20 mPa-s or greater, especially a number such that the organopoiysiloxane has the form of anywhere from a liquid having a viscosity at 25°C of 1 ,000,000 mPa-s or greater to a gum having a plasticity of 0.5 to 3.0 mm at 25°C.

[0030] The component a1 ) is especially preferably an organopoiysiloxane comprising hexenyl groups at both ends and on a side chain represented by the following chemical formula (2).

Formula 2

(In formula (2), ml is a number equal to 0 or greater and n1 is a positive integer, ml being a number such that the vinyl (CH2=CH-) moiety content of the hexenyl groups (- (CH2)4CH=CH2) in the molecule shown in formula (2) is in a range from 0.5 to 3.0 mass%, more preferably in a range from 1.0 to 2.0 mass%. The sum of ml + n1 is a number in a range such that the organopolysiloxane represented by formula (2) has a viscosity at 25°C of 20 mPa-s or greater, more preferably anywhere from a viscosity of 1 ,000,000 mPa-s or greater to a gum having a plasticity at 25°C of 0.5 to 3.0 mm. )

[0031] The viscosity at 25°C of the component a1 ) is 20 mPa-s or greater. If the viscosity is less than this, there may be difficulty in achieving an alkenyl group having from 4 to 12 carbon atoms content in the range set forth above. On the other hand, if the viscosity exceeds 20 mPa-s, the component a1 ) may be a liquid or a gum (ordinarily, a semi-solid highly polymerized, plastic silicone polymer having a viscosity of 10,000,000 mPa-s or greater) at 25°C. As discussed above, a preferred component (A) of the present invention is a "high-polymer" organopolysiloxane or organopolysiloxane mixture, with physical properties that continuously range, as the degree of polymerization increases, from a high- viscosity liquid region to a plastic gum region. To wit, if the degree of polymerization of the organopolysiloxane increases to the point that the viscosity at 25°C exceeds 15,000,000 mPa-s, viscosity generally becomes difficult to measure, and the organopolysiloxane transitions from a high-viscosity region (i.e., liquid) to a region in which the physical properties thereof are defined in terms of plasticity (i.e., gum).

[0032] In order to obtain satisfactory ease of application of the curable organopolysiloxane composition according to the present invention to a sheet-like substrate, the viscosity at 25°C of the component a1 ) is preferably 10,000,000 mPa s or greater. There is no upper limit on the viscosity at 25°C of the component a1 ), but, in order to ensure ease of handling, anywhere from a liquid having a viscosity at 25°C of 1 ,000,000 mPa-s or greater to a gum having a plasticity at 25°C of 3.0 mm or less is preferable.

[0033] The component a1 ) may be a mixture of two or more types of component a1 ) of different viscosities. An organopolysiloxane having the form of a gum having a plasticity exceeding 3.0 mm may be favourably used if mixed with a low-viscosity liquid

organopolysiloxane, and such a form is encompassed by the present invention.

Component a2

[0034] The component a2) forming part of the component (A) can be selected from straight-chain organopolysiloxanes, branched-chain organopolysiloxanes, and straight- chain or branched-chain organopolysiloxanes having a partial ring structure; from an industrial perspective, a straight-chain organopolysiloxane represented by the following chemical formula (1 ) is preferable.

Formula 3

[0035] In the formula, each R11 independently represents an unsubstituted or halogen- substituted alkyl group (such as a methyl group) having from 1 to 20 carbon atoms, an aryl group (such as a phenyl group) having from 6 to 22 carbon atoms, an alkenyl group (a vinyl group or allyl group) having 2 or 3 carbon atoms, or a hydroxyl group. Ra' is an alkenyl group (vinyl group or allyl group) having 2 or 3 carbon atoms. R is a group represented by R11 or Ra'. m is a number equal to 0 or greater, and n is a number equal to 1 or greater. The values of m, n, and R are such that the vinyl (CH2=CH-) moiety content of the alkenyl groups having 2 or 3 carbon atoms in the molecule of the organopolysiloxane represented by formula 1 above is from 0.5 to 3.0 mass%, more preferably from 1.0 to 2.0 mass%.

[0036] For example, if R at both ends is an alkenyl group having 2 or 3 carbon atoms (Ra), the alkenyl group content is represented by the following formula:

(total molecular weight of vinyl (CH2=CH-) moieties in alkenyl groups having 2 or 3 carbon atoms present in the molecule)/overall molecular weight ^χ 100 (mass%)

and, in formula (1 ), the component a2) is an organopolysiloxane in which the vinyl

(CH2=CH-) moiety content of the alkenyl group having 2 or 3 carbon atoms is from 0.5 to 3.0 mass%, more preferably from 1.0 to 2.0 mass%. It is also preferable that, in the component a2), the sum of m + n in formula (1) is a number in a range such that the viscosity of the organopolysiloxane represented by formula (1 ) at 25°C is 20 mPa-s or greater, preferably a number such that viscosity is 1 ,000,000 mPa s or greater, especially preferably a number yielding anywhere from a liquid having a viscosity at 25°C of

1 ,000,000 mPa-s or greater to a gum having a plasticity at 25°C of 3.0 mm or less.

In order to obtain satisfactory ease of application of the curable organopolysiloxane composition to a sheet-like substrate, the component a2) preferably has anywhere from a viscosity at 25°C of 10,000,000 mPa-s or greater to a gum-like form having a plasticity at 25°C of 3.0 mm or less.

[0037] The component a2) may be a mixture of two or more types of component a2) of different viscosities. An organopolysiloxane having the form of a gum having a plasticity exceeding 3.0 mm may be favourably used if mixed with a low-viscosity liquid

organopolysiloxane, and such an instance is encompassed by the present invention.

[0038] The component (A) contains components a1 ) and a2) at a mass ratio of 100:0 to 50:50, preferably 100:0 to 70:30, more preferably 100:0 to 90:10. In other words, the component (A) is constituted only by the component a1 ), or is a combination of components a1 ) and a2). If the component (A) is a mixture of components a1 ) and a2), it is preferably a plastic, semi-solid (gum-like), highly polymerized organopolysiloxane or organopolysiloxane mixture; both combinations of organopolysiloxanes in which one of components a1 ) and a2) exhibits plasticity and combinations of organopolysiloxanes in which both components exhibit plasticity are possible. Especially preferably is a gum-like form in which the organopolysiloxane or organopolysiloxane mixture has a plasticity at 25°C of 0.5 to 10.0 mm.

[0039] A desired combination of the organopolysiloxanes described above can be used for components a1 ) and a2). An especially preferable combination contains a1-1 ) at least one type of organopolysiloxane comprising a hexenyl group as an alkenyl group having 4 to 12 carbon atoms, the hexenyl group having a vinyl (CH2=CH-) moiety content of 0.5 to 3.0 mass%, preferably 1 .0 to 2.0 mass%, as the component a1 ), and a2-1 ) at least one type of organopolysiloxane comprising a vinyl group as an alkenyl group having 2 or 3 carbon atoms, the vinyl group content being 0.5 to 3.0 mass%, preferably 1 .0 to 2.0 mass%, as the component a2). The alkenyl groups having 4 to 12 carbon atoms of the component a1-1 are especially preferably all hexenyl groups. The alkenyl groups having 2 or 3 carbon atoms of the component a2-1 ) are especially preferably all vinyl groups.

[0040] If component (A) is a mixture of two or more types of organopolysiloxanes, the mixture having an overall gum-like form, the plasticity (i.e., plasticity as measured using a plastometer according to the method specified by JIS K 6249: value obtained by placing a 1 kgf load upon a 4.2 g spherical sample at 25°C for 3 minutes) is preferably in a range from 0.5 to 10.0 mm, especially preferably in a range 0.9 to 3.0 mm.

Component B

[0041] Component (B) is an additive for imparting a release film with superior ease of application with respect to a ceramic slurry; using the component (B) allows the obtained release film to be imparted with satisfactory ease of application with respect to the ceramic slurry. More specifically, it is presumed that the release film can be imparted with satisfactory ease of ceramic slurry application via modification of the surface properties of the release film effected by the effective bleeding out of the component (B) on the surface of the high-crosslink-density cured organopolysiloxane layer obtained using the component (A).

[0042] The component (B) is an organopolysiloxane optionally comprising alkenyl group and in which the alkenyl groups having 2 to 12 carbon atoms have a vinyl (CH2=CH-) moiety content of less than 0.100 mass%, preferably at least 0.005 mass %, preferably from 0.010 to 0.050 mass%. Examples of non-alkenyl groups bonded to the silicon atoms of the organopolysiloxane include alkyl groups such as methyl group, ethyl groups, and propyl groups; aryl groups such as phenyl groups; haloalkyl groups such as 3,3,3- trifluoropropyl groups and nonafluorohexyl groups; and silanol groups. The non-alkenyl groups are selected from these groups. There is no particular limitation upon the alkenyl group having 2 to 12 carbon atoms of the component (B); examples include vinyl, allyl, butenyl, pentenyl, hexenyl, octenyl, decenyl, and dodecenyl groups, with a vinyl, allyl, or hexenyl group being preferable, a vinyl and/or hexenyl group being more preferable, and a vinyl group being especially preferable.

[0043] In order to achieve the object of the present invention, the component (B) is preferably a low-reactivity organopolysiloxane in which the vinyl (CH2=CH-) moiety content of the alkenyl groups having 2 to 12 carbon atoms is less than 0.100 mass%, preferably 0.005 to 0.100 or preferably 0.010 to 0.050 mass%, and 90% or more, preferably all, of the non-alkenyl groups bonded to the silicon atoms are preferably non- reactive alkyl groups or aryl groups. Non-reactive alkyl groups and aryl groups are unsubstituted alkyl groups or aryl groups, examples including the alkyl groups and aryl groups listed above, with especially preferable groups being selected from methyl groups and phenyl groups.

[0044] If the alkenyl group content of the component (B) is less than the minimum set forth above, curing reactivity will be drastically reduced, increasing the amount of silicone polymer that migrates to the ceramic sheet. Using such a ceramic sheet to manufacture a multilayer ceramic capacitor may result in a problematic reduction in performance in the obtained capacitor. On the other hand, if the alkenyl group content exceeds the maximum set forth above, the component (B) will become incorporated into the layer of cured polyorganosiloxane (i.e., silicone) via an addition reaction, potentially resulting in insufficient expression of the effect of the present invention of imparting the surface of a release film with satisfactory ease of ceramic slurry application thanks to the component (B) bleeding out from the cured silicone layer onto the surface of the release film. On the other hand, although alkenyl group is optionally functional group in the component (B), if the alkenyl group content is more than the minimum set forth above, curing reactivity will be increased with drastically decreasing the amount of silicone polymer that migrates to the ceramic sheet. By using the component (B) having the vinyl (CH2=CH-) moiety content of 0.010 to 0.050 mass%, the performance of obtained ceramic sheet to manufacture a multilayer ceramic capacitor may be further improved, compared with using component (B) having no alkenyl group in the molecule

[0045] The component (B) preferably has a form of anywhere from a liquid to a plastic gum at 25°C, preferably with a viscosity at 25°C of 1 ,000,000 mPa-s or greater, more preferably 10,000,000 mPa-s or greater, in the case of a liquid. There is no particular limit on the maximum viscosity, but, for the sake of satisfactory ease in applying the curable organopolysiloxane composition and ease in handling when adding to the composition, the component (B) is preferably in the form of a plastic gum having a plasticity at 25°C of 10.0 mm or less. If component (B) is in the form of a gum, the plasticity (i.e., plasticity as measured using a plastometer according to the method specified by JIS K6249: value obtained by placing a 1 kgf load upon a 4.2 g spherical sample at 25°C for 3 minutes) is preferably in a range from 0.5 to 10.0 mm, especially preferably in a range 0.9 to 3.0 mm.

[0046] Specific examples of component (B) include organopolysiloxanes constituted by polydimethylsiloxane, a dimethylsiloxane/phenylmethylsiloxane copolymer, or a dimethylsiloxane/diphenylsiloxane copolymer and having the alkenyl group content set forth above, the ends of the molecule in any of these cases being capped with identical or different groups selected from the group consisting of an alkyl group, an alkenyl group, an aryl group, a haloalkyl group, or a silanol group bonded to a silicon atom. An especially preferable component (B) is a straight- or branched-chain dimethylpolysiloxane optionally having the alkenyl group content set forth above, the ends of the molecule being capped with identical or different groups selected from the group consisting of trimethylsiloxy groups, silanol groups, and vinyl groups. The component (B) may also be a mixture of two or more types of organopolysiloxanes, such as a mixture of polydimethyl siloxanes of different degrees of polymerization.

[0047] Most preferably, the component (B) is polydimethyl siloxane the molecule of which is capped at both ends with dimethyl vinyl siloxy groups, with polydimethyl siloxane in the form of a gum being especially preferable.

Proportions of component (A) and component (B)

[0048] The molar ratio of component (A) and component (B) in the curable

organopolysiloxane composition according to the present invention is in a range from 90:10 to 99: , more preferably 97:3 to 94:6, still more preferably 95.5:4.5 to 94.5:5.5, and especially preferably 95:5. Having the molar ratio of component (A) and component (B) be in the range set forth above allows the release film to be imparted with satisfactory ease of ceramic slurry application. If the proportion of component (B) exceeds the maximum value of the range set forth above, the curability of the obtained curable organopolysiloxane composition may be reduced, potentially lowering the releasability of the ceramic green sheet formed on the release film from the release film.

Component (C¾

[0049] The component (C) is an organohydrogen polysiloxane comprising at least two silicon-bonded hydrogen atoms (Si-H) within its molecule, and is a crosslinking agent for component (A). The component (C) preferably comprises at least three silicon atom- bonded hydrogen atoms within its molecule, there being no particular limitation upon the positions at which the hydrogen atoms are bonded within the molecule. The silicon atom- bonded hydrogen atom content is preferably an amount equal to 0.1 to 2.0 mass%, more preferably 0.5 to 1.8 mass%, of the overall mass of the curable organopolysiloxane composition. Examples of organic groups bonded to the silicon atoms of the component (C) apart from hydrogen atoms include alkyl groups such as methyl groups, ethyl groups, propyl groups, butyl groups, and octyl groups, with methyl groups being preferable.

Examples of the molecular structure of the organohydrogen polysiloxane of component (C) include straight-chained, branch-chained, branch-ringed, and a combination of one or more of the above. The number of silicon-bonded hydrogen atoms in the molecule is the average value for the entire molecule.

[0050] The viscosity at 25°C of the component (Q is 1 to 1 ,000 mPa s, preferably 5 to 500 mPa s. If the component (C) has a viscosity at 25°C of less than 1 mPa-s, the component (C) will more readily evaporate from within the curable organopolysiloxane composition of which it is a part; and if the viscosity exceeds 1 ,000 mPa-s, the curing time of the curable organopolysiloxane composition containing the component (C) will be increased. There is no particular limitation upon the component (C); examples include a

dimethylsiloxane/methyl hydrogen siloxane copolymer capped at both ends with trimethylsiloxy groups, a dimethylsiloxane/methyl hydrogen siloxane copolymer capped at both ends with dimethylhydrogen siloxy groups, dimethylpolysiloxane capped at both ends with dimethylhydrogen siloxy groups, methyl hydrogen polysiloxane capped at both ends with trimethylsiloxy groups, a cyclic methyl hydrogen polysiloxane, and a cyclic

methylhydrogen siloxane/dimethylsiloxane copolymer. Two or more types of

organohydrogen polysiloxane can be used together for the component (C).

[0051] More preferably, the component (C) is one or a mixture of two or more

organohydrogen polysiloxanes represented by the following general formula (2), and is capable of forming a cured organopolysiloxane layer through an addition reaction

(hydrosilylation) with the silicon atom-bonded alkenyl groups contained in components (A) and (B).

[0052] In^'formula (2), R12 is a substituted or unsubstituted alkyl group or aryl group, preferably an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, or a phenyl group. RH is the group represented by R12 or a hydrogen atom (H) bonded to a silicon atom; if q = 0, RH is a hydrogen atom (H) bonded to a silicon atom, p and q are numbers greater than or equal to 0 that satisfy the relationship 10≤ (p + q)≤ 200. If (p + q) is less than the minimum value set forth above, the component (C) may evaporate from the curable organopolysiloxane composition, depending on the curing conditions, potentially resulting in insufficient composition curing. If (p + q) exceeds the maximum limit set forth above, a gel may form prior to application to the film. Defining r as the number of hydrogen atoms (H) bonded to a silicon atom in the component (C), p and q preferably satisfy the relationship 0.01≤ r/(p + q)≤ 1 , more preferably the relationship 0.2 ≤ r/(p + q)≤ 1 , especially preferably the relationship 0.4≤ r/(p + q)≤ 1. I r/(p + q) is less than the minimum value set forth above, the curable organopolysiloxane composition according to the present invention may not cure sufficiently, r is the sum of q and the number RH of hydrogen atoms (H) bonded to a silicon atom, r is, for example, q + 2 if RH at both ends is a hydrogen atom (H) bonded to a silicon atom.

[0053] The amount of component (C) in the curable organopolysiloxane composition according to the present invention is such that the molar ratio of SiH groups in component (C) to the total molar number of alkenyl groups in component (A) and component (B) is 0.5 to 5, preferably 1 to 3. If the molar ratio is less than the minimum value set forth above, the curability of the obtained curable composition will be reduced, and if it exceeds the maximum value set forth above, the resistance of the dielectric ceramic layer-forming material, especially a ceramic green sheet, to peeling from the release sheet will increase, potentially preventing a practical level of releasability from being obtained.

Component (D)

[0054] Component (D) is a hydrosilylation catalyst that promote an addition reaction (hydrosilylation) between the silicon atom-bonded alkenyl groups and the silicon atom- bonded hydrogen atoms present in the curable organopolysiloxane composition. A preferred hydrosilylation catalyst is a hydrosilylation catalyst containing a platinum-based metal, with specific examples including chloroplatinic acid, alcohol-modified chloroplatinic acid, an olefin complex of chloroplatinic acid, a chloroplatinic acid-ketone complex, a chloroplatinic acid-vinylsiloxane complex, platinum (IV) chloride, finely powdered platinum, solid platinum carried on a carrier of alumina or silica, platinum black, a platinum-olefin complex, a platinum-alkenylsiloxane complex, a platinum-carbonyl complex, a methyl methacrylate resin, or a powdered thermoplastic organic resin, such as a polycarbonate resin, polystyrene resin, or silicone resin, containing these platinum-based catalysts. A platinum alkenyl siloxane complex, such as a chloroplatinic acid-divinyl tetramethyl disiloxane complex, a chloroplatinic acid-tetramethyl tetravinyl cyclotetrasiloxane complex, a platinum divinyl tetramethyl disiloxane complex, or a platinum tetramethyl tetravinyl cyclotetrasiloxane complex, is especially preferable.

[0055] It is sufficient to add a catalytic amount of component (D) to the curable

organopolysiloxane composition; ordinarily, an amount such that the amount of platinum- based metal in the component (D) is 1 to 1 ,000 ppm, more preferably 5 to 500 ppm, with respect to the total mass of the curable organopolysiloxane composition according to the present invention is preferable.

Curable organopolysiloxane composition

[0056] The curable organopolysiloxane composition according to the present invention may, if desired, contain (E) an organic solvent. In particular, it is preferable, due to the large amount of component (B) contained in the curable organopolysiloxane composition according to the present invention, to disperse or dissolve a composition containing components (A) to (D) in a known (E) organic solvent for the sake of satisfactory ease of handling and application. However, it is also possible disperse or dissolve components (A) to (D) in a low-viscosity liquid organopolysiloxane (such as a chain-shaped or cyclic organopolysiloxane having a low viscosity of roughly 0.5 to 10 mPa-s at 25°C) other than a desired organic solvent to the extent that the object of the present invention is not impeded. Examples of organic solvents include: aromatic hydrocarbon solvents such as toluene and xylene; aliphatic hydrocarbon solvents such as hexane, octane, and isoparaffin; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester solvents such as ethyl acetate and isobutyl acetate; ether solvents such as diisopropyl ether and 1 ,4-dioxane; cyclic polysiloxanes having polymerization levels of 3 to 6 such as hexamethyl cyclotrisiloxane, octamethyl cyclotetrasiloxane, and decamethyl cyclopentasiloxane; and halogenated hydrocarbons such as trichloroethylene, perchloroethylene, trifluoromethyl benzene, 1 ,3-bis(trifluoromethyl) benzene, methyl pentafluorobenzene. If a thin layer of the curable organopolysiloxane composition according to the present invention is applied to a sheet-like substrate of polyolefin of the like having low heat resistance, an aromatic hydrocarbon solvent such as toluene or xylene is preferable, as these will have little effect upon the curability of the composition.

[0057] Apart from components (A) to (D) and the optional component (E), the curable organopolysiloxane composition according to the present invention preferably also contains (F) a hydrosilyiation inhibitor that minimizes gelling and curing at normal temperature, increasing storage stability, and imparts curability when heated. Examples of hydrosilyiation inhibitors include acetylene compounds, enyne compounds, organic nitrogen compounds, organic phosphorus compounds, and oxime compounds. Examples of specific compounds include: alkyne alcohols such as 2-methyl-3-butyne-2-ol, 3,5-dimethyl-1-hexyne-3-ol, 3- methyl-1 -pentyne-3-ol, 2-phenyl-3-butyne-2-ol, and 1 -ethynyl-1 -cyclohexanol (ETCH); enyne compounds such as 3-methyl-3-trimethyl siloxy-1 -butyne, 3-methyl-3-trimethyl siloxy-1 -pentyne, 3,5-dimethyl-3-trimethyl siloxy-1 -hexyne, 3-methyl-3-pentene-1-ene, and 3,5-dimethyl-3-hexene-1-ene; and alkenyl siloxanes such as 1-ethynyl-1-trimethyl siloxycyclohexane, bis(2,2-dimethyl-3-butynoxy) dimethyl silane, 1 ,3,5,7-tetramethyl- 1 ,3,5,7-tetravinyl cyclotetrasiloxane, and 1 ,3,5,7-tetramethyl-1 ,3,5,7-tetrahexenyl cyclotetrasiloxane. The amount of (F) hydrosilylation inhibitor added to the curable organopolysiloxane composition will ordinarily be in a range of 0.001 to 5 parts by mass component (F) per 100 parts by mass component (A); a preferable amount of added component (F) can easily be determined according to the type of component (F), the physical properties and amount of the hydrosilylation catalyst used, the C4 to C12 alkenyl group content of the component (A), the amount of silicon atom-bonded hydrogen atoms in the component (C), and the desired length of usable time and usage environment of the curable composition.

[0058] The curable organopolysiloxane composition according to the present invention contains the components (A), (B), (C), and (D) described above, as well as the optional component (E), as, if desired, the optional component (F). The curable composition according to the present invention is suitable for use as a solvent-containing solution-type curable organopolysiloxane composition. In particular, the overall viscosity at 25°C of the curable organopolysiloxane composition according to the present invention is preferably in a range from 100 to 100,000 mPa-s, more preferably from 100 to 50,000 mPa s, in order for the composition to exhibit satisfactory sheet-like substrate-coating properties.

[0059] Other optional components in addition to those described above may be added to the curable organopolysiloxane composition according to the present invention. Examples of other optional components include: adhesion promoters constituted by alkoxysilane compounds such as 3-glycydoxypropyl trimethoxysilane and 3-methacryloxypropyl trimethoxysilane; phenol-, quinone-, amine-, phosphorus-, phosphite-, sulfur-, and thioether-based antioxidants; triazole- and benzophenone-based light stabilizers;

phosphate ester-based, halogen-based, phosphorus-based, and antimony-based flame retardants; one or more type of surfactant selected from cationic surfactants, anionic surfactants, and non-ionic surfactants; and known additives such as antistatic agents, heat resistance agents, dyes, and pigments. One or a combination of two or more of these components can be added to the curable organopolysiloxane composition according to the present invention. [0060] The curable organopolysiloxane composition according to the present invention contains the components (A) to (D) described above, the optional component (E) if desired, and the optional component (F) if desired, and is capable of forming a cured coating of superior release properties through an addition reaction performed at room temperature or at a temperature of 50 to 200°C in the presence of a platinum-based catalyst (component (D)). In addition, because of the superior physical properties and releasability of the obtained cured coating, the curable organopolysiloxane composition according to the present invention is preferably cured using energy radiation (also referred to as chemically active radiation), such as UV radiation or an electron beam, especially UV irradiation. In such cases, UV curing can be performed singly or in combination with heat curing. The curing time of the curable composition can be adjusted, as appropriate, according to the curing conditions used. In order to impart the curable organopolysiloxane composition according to the present invention with satisfactory UV curability, a (G) photopolymerization initiator is preferably further included in the composition. The component (G) will be described in detail hereafter.

[0061] The (G) photopolymerization initiator, imparts the curable organopolysiloxane composition according to the present invention with UV curability; the combined used of addition reaction-induced heat curing and UV curing reduced heat damage to plastic film substrates of low heat resistance, yielding an advantageous improvement in the strength of the bond between the cured product of the present invention and a plastic film. There is also the advantage that the migration of silicone components from the surface of the cured coating formed by the curable composition according to the present invention to the ceramic sheet, contaminating the ceramic sheet with silicone components (so-called "silicone migration"), can be prevented, further reducing silicone migration. A known compound that generates radicals under UV irradiation, such as an organic peroxide, a carbonyl compound, an organic sulfur compound, or an azo compound, can be selected as appropriate for use as the component (G). Specific compounds include acetophenone, propiophenone, benzophenone, xantol, fluorein, benzaldehyde, anthraquinone, triphenylamine, 4-methyl acetophenone, 3-pentyl acetophenone, 4-methoxyacetophenone, 3-bromoacetophenone, 4-allyl acetophenone, p-diacetyl benzene, 3-methoxy

benzophenone, 4-methyl benzophenone, 4-chlorobenzophenone, 4,4-dimethoxy benzophenone, 4-chloro-4-benzyl benzophenone, 3-chloroxanthone, 3,9-dichloroxanthone, 3-chloro-8-nonyl xanthone, benzoin, benzoin methyl ether, benzoin butyl ether, bis(4- dimethyl aminophenyl) ketone, benzyl methoxy ketal, 2-chlorothioxanthone, diethyl acetophenone, 1 -hydroxy cyclohexyl phenyl ketone, 2-methyl [4-(methyl thio)phenyl] 2- morpholino-1 -propanone, 2,2-dimethoxy-2-phenyl acetophenone, and diethoxy acetophenone. If the composition according to the present invention is cured using UV radiation, the component (G) is preferably benzophenone, 4-methoxyacetophenone, 4- methyl benzophenone, diethoxyacetophenone, or 1-hydroxycyclohexyl phenyl ketone. Especially preferable as component (G) are diethoxy acetophenone and 1- hydroxycyclohexyl phenyl ketone.

[0062] One or a combination of two or more types of (G) photopolymerization initiator may be used. There is no particular limitation upon the amount thereof, but said amount will be in a range of 0.01 to 10 parts by mass, preferably 0.01 to 2.5 parts by mass, per 100 parts by mass component (A). If the amount of component (G) is in the range set forth above, the releasable cured coating obtained by curing the composition according to the present invention will exhibit improvement in terms of silicone migration, and will have superior strength and other physical properties.

[0063] The composition according to the present invention can be produced by uniformly mixing the abovementioned components (A) to (D), the optional component (E), the optional component (F) if desired, and any other optional components. There is no particular limitation upon the order in which the various components are added, but if the obtained composition will not be used immediately after mixing, it is preferable to separately store the component (D) and a mixture of components (A), (B), and (C), and mix the two together immediately before use. In the case of a composition containing components (A) to (D), the optional component (E), and component (F), the amount of component (F) is preferably adjusted to yield a composition that does not form crosslinks at normal temperature, but does form crosslinks and cure when heated.

[0064] When the curable organopolysiloxane composition according to the present invention described above is evenly applied to a sheet-like substrate and heated, irradiated with energy (such as UV radiation or an electron beam), or subjected to a combination of both under conditions suitable to induce hydrosilylation of component (A) and component (B) and form crosslinks, a sheet-like article comprising a silicone coating (i.e., a cured organopolysiloxane coating) on the surface of the sheet-like substrate is obtained. The sheet-like article according to the present invention is characterized in offering satisfactory ease of applying a ceramic slurry to the cured silicone coating, and in that the dielectric ceramic layer-forming material, especially a ceramic green sheet, obtained after drying the slurry is easy to remove from the substrate. In other words, the sheet-like article according to the present invention so obtained can be used as a release film for use with a dielectric ceramic layer-forming material, especially as a release film for forming a ceramic green sheet. In addition, the cured layer obtained by curing the curable composition according to the present invention has superior flexibility, thus yielding the advantages of satisfactory substrate conformation and little envelopment of air pockets when the layer is applied to a non-flat object. As a result, the article can be very advantageously used in applications requiring both cured layer releasability and close bonding of the cured layer to an object to be protected, as in the case of a protective film for optical displays and glass surfaces.

[0065] There is no particular limitation upon the sheet-like substrate to which the curable polyorganosiloxane composition according to the present invention is applied; a desired known material can be selected for use, as appropriate. Examples of such substrate materials include films of polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene and polymethyl pentene, polycarbonates, and plastics such as polyvinyl acetate. A single layer of film may be used, or two or more layers of identical or different types of plastic may be used. A plastic film, especially a polyester film, and particularly a polyethylene terephthalate film, is preferable as the sheetlike substrate, especially a release film for use with a dielectric ceramic layer-forming material, particularly a release film for forming a ceramic green sheet, according to the present invention. In particular, a biaxially oriented polyethylene terephthalate film is preferably used as the sheet-like substrate. A polyethylene terephthalate film will not readily generate dust when being machined or use. This allows for defects in applying the ceramic slurry to the sheet-like substrate caused by the presence of dust or the like to be effectively prevented. Using a polyethylene terephthalate film that has been subjected to an anti-static treatment as the sheet-like substrate is also effective in preventing defects in the application of the ceramic slurry to the sheet-like substrate.

[0066] It is also possible to surface treat one or both sides of the sheet-like substrate, as desired, via oxidation or roughening or with a primer in order to improve the bond between the surface of the sheet-like substrate and the curable organopolysiloxane according to the present invention after the same has been applied to the surface of the sheet-like substrate and dried. Methods of oxidation include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet method), flame treatment, hot air treatment, ozone treatment, and UV irradiation treatment. Methods of roughening include sand blasting and thermal spraying. These various surface treatment methods can be selected as appropriate according to the type of sheet-like substrate used; however, corona discharge treatment is preferable as this will yield high levels of the effects desired from surface treating the sheet-like substrate and is easy to perform.

[0067] The thickness of the sheet-like substrate will generally be 10 to 300 pm, preferably 15 to 200 pm, especially preferably 20 to 125 pm.

[0068] A desired known method can be used to apply the curable organopolysiloxane composition according to the present invention to the sheet-like substrate; examples include gravure coating, bar coating, spray coating, spin coating, knife coating, roll coating, and die coating.

[0069] When applying the curable organopolysiloxane composition according to the present invention to a sheet-like substrate and curing the composition, there is no particular limitation upon the thickness of the layer of cured organopolysiloxane composition, but a thickness of 0.01 to 3 \im is preferable, and 0.03 to 1 m more preferable. If the thickness of the layer of cured organopolysiloxane composition on the sheet-like substrate is less than 0.01 μιτι, the layer may not sufficiently function as a release layer when using as a release sheet for use in forming a ceramic green sheet. On the other hand, if the thickness of the layer of cured organopolysiloxane composition on the sheet-like substrate exceeds 3 μηι, blocking may occur when the obtained sheet-like article is wrapped up into a roll. The antistatic layer described above, as well as other desired layers, may be provided on the surface of the sheet-like substrate opposite the side on which the layer of cured organopolysiloxane composition is formed, or between the sheet-like substrate and the layer of organopolysiloxane composition.

[0070] The sheet-like article comprising the sheet-like substrate and the cured layer obtained by applying the curable organopolysiloxane composition according to the present invention to the substrate and curing the composition is suitable for use as a release film for use with a dielectric ceramic layer-forming material, especially as a release film for forming a ceramic green sheet. A ceramic green sheet can be produced using a method comprising a step of applying a ceramic slurry to the release film for forming a ceramic green sheet according to the present invention, that is, to that surface upon which the cured polyorganosiloxane composition is present, and drying the slurry. More specifically, the ceramic slurry is applied to the surface of the layer of cured organopolysiloxane composition formed on the release film for forming a ceramic green sheet according to the present invention using a desired application method, such as via slot die coating or using a doctor blade, then dried to form a ceramic green sheet. Using a release film for use with a dielectric ceramic layer-forming material, especially a release film for forming a ceramic green sheet, on which a release layer has been formed using the curable

organopolysiloxane composition according to the present invention for this process minimizes the phenomenon of edge contraction, in which the edges of the applied ceramic slurry contract, causing the edges to be thicker than the inner parts of the ceramic slurry, and minimizes the formation of pinholes in the surface of the applied ceramic slurry and inconsistencies in the application of the ceramic slurry. If the release film for forming a ceramic green sheet according to the present invention is used, the satisfactory

releasability exhibited by the surface formed by the cured organopolysiloxane composition allows the ceramic green sheet to be separated from the layer of cured organopolysiloxane there beneath with little peeling force without cracking or tearing of the ceramic green sheet, even if a thin ceramic green sheet of low strength is formed on the film. In this way, the release film for use in forming a ceramic green sheet according to the present invention offers superior ease of ceramic slurry application and superior releasability of the subsequently formed ceramic green sheet.

[0071] As discussed above, the curable organopolysiloxane composition according to the present invention is suitable for use with a release film for use with a dielectric ceramic layer-forming material, especially a release film for forming a ceramic green sheet, but is not limited to such uses, and can be used to treat the surfaces of a variety of films and sheets. In particular, a sheet-like article comprising a cured layer constituted by the composition according to the present invention can be used as a surface-protective film for protecting the surfaces of optical components such as LCD panels, plasma displays, polarizing plates, and phase contrast plates, and electrical and electronic components such as printed circuit boards, integrated circuits, transistors, and capacitors; in such cases, an antistatic agent is preferably added to the composition according to the present invention.

[0072] A known ionic or nonionic antistatic agent can be used without particular limitation; examples of methods include adding a silicone oil a main component of which comprises a hydrophilic group (Unexamined Japanese Patent Application Publication S52-103499), adding a sulfonate salt (Examined Japanese Patent Application H03-059096), adding a fluorine-containing silicone oil (Unexamined Japanese Patent Application Publications H01 - 083085, H01-083086, H01 -121390), adding a surfactant-containing silicone oil

(Unexamined Japanese Patent Application Publication H01 -294099), and adding an electroconductive powder (Unexamined Japanese Patent Application Publication H02- 069763, H03-292180, H04-086765). In particular, it is preferable to use an antistatic agent constituted by a lithium salt or a polyether-modified polysiloxane for the sake of

compatibility with the curable organopolysiloxane composition according to the present invention. The ionic antistatic agents and polyether-modified polysiloxanes disclosed, for example, in Unexamined Japanese Patent Application Publications 2009-030028, 2012- 157978, and 2011 -178828 can be used without particular limitation. For the sake of static prevention, treatment may also be performed using a surfactant, silicone, organic boron, electroconductive polymer, metallic oxide, vapor-deposited metal, or other type of antistatic agent instead of only adding one of the aforementioned antistatic agents as an additive.

Working examples

[0073] The present invention will now be described in greater detail with the aid of working examples and comparative examples, but the present invention is not limited to the working examples described below. In the following examples, "parts" means parts by mass when used to indicate amount, "Hex" indicates a hexenyl group, "Vi" indicates a vinyl group, and "Me" indicates a methyl group. "Vinyl (CH2=CH-) moiety" refers to that portion of the silicon atom-bonded alkenyl groups constituted by vinyl (CH2=CH-) groups, and is indicated in terms of the mass% vinyl content with respect to overall molecular weight; if the alkenyl groups are vinyl groups, "vinyl group content" will be used. Viscosity and plasticity values were measured at 25°C. Plasticity was measured as described above, and viscosity was measured using a Vismetron VDA2 digital display type-B rotational viscometer from Shibaura Systems. The peeling resistance value (peel force) of the cured layer formed by the curable organopolysiloxane composition was measured according to the following method.

Method of forming cured layer

[0074] The curable organopolysiloxane composition was applied to the surface of a biaxially oriented polyester film (38 pm thick; Mitsubishi Plastics) using a Mayer bar in an amount equivalent to 0.15 g/m2 solid weight less solvent. Following application, the substrate to which the composition was applied was heat-treated in a hot air circulation oven at 130°C for 30 seconds to form a cured layer of organopolysiloxane on the surface of the polyester film substrate.

Evaluating ease of ceramic binder resin application

[0075] 55 parts by mass toluene was added to 3 parts by mass polyvinyl butyral (S-LEC B, K, BM-1 ; Sekisui Chemical) and mixed to a uniform consistency, after which 33 parts by mass methanol and 9 parts by mass n-butanol were added to the mixture and the whole was stirred to a uniform consistency to prepare a ceramic binder resin solution.

[0076] After producing the cured layers of the working examples and comparative examples, the ceramic binder resin solution described above was uniformly applied using a Mayer bar to the surface of the cured layer, after the latter had been stored for 24 hours at 25°C and 60% humidity, so that the post-drying thickness was 2 pm, and cured according to the method set forth for the working examples and comparative examples. In this way, ceramic binder resin-comprising release film sheets were produced.

Ease of application test

[0077] The obtained ceramic binder resin-comprising release film sheet was visually observed to confirm the presence or lack of edge contraction (in which the edges of the applied ceramic binder resin are thicker than the inner parts). Cases in which edge contraction did not occur were rated o, cases in which slight edge contraction occurred were rated Δ, and cases in which prominent edge contraction occurred were rated *.

Ceramic binder resin peel force evaluation [0078] 50 parts by mass toluene was added to 8 parts by mass polyvinyl butyral (S-LEC B, K, BH-3; Sekisui Chemical) and mixed to a uniform consistency, after which 33 parts by mass methanol and 9 parts by mass n-butanol were added thereto and the whole was stirred to a uniform consistency to prepare a ceramic binder resin solution.

[0079] After producing the cured layers of the working examples and comparative examples, the ceramic binder resin solution described above was uniformly applied using an applicator to the surface of the release layer, after the latter had been stored for 24 hours at 25°C and 60% humidity, so that the post-drying thickness was 10 pm, and dried in a hot air circulation oven at 100°C for one minute. The ceramic binder resin-comprising release film sheet so obtained was cut to a width of 5 cm to create a test strip, a load of 20 g/cm2 was applied thereto, and the whole was left to stand at 25°C and 60% humidity for 24 hours. An A&D all-purpose Tensilon tensile tester was used to elongate the ceramic binder resin layer at a angle of 90° and a peel rate of 0.3 m/min, and the required peel force (mN/50 mm) was measured. Release properties were rated satisfactory if the peel force as measured according to this method was 20 mN/50 mm or less, and unsatisfactory if the peel force was 20 mN/50 mm or greater.

Working example 1 - Composition 1

[0080] (A) 30.0 parts polydimethyl siloxane having hexenyl groups at both ends and on a side chain (plasticity: 1 .15; hexenyl group vinyl (CH2=CH-) moiety content: 0.80 mass%), (B) 1.5 parts dimethylsiloxane capped by vinyl groups at the ends of the molecule

(plasticity: 1.20; vinyl group content: 0.02 mass%), (C) 1.3 parts 25 mPa-s viscosity dimethyl methylhydrogen polysiloxane so that the SiH/Vi ratio of the composition as a whole was 1 .5, (E) 66.2 parts toluene, and (F) 1 .0 part 3-methyl-1 -butyne-3-ol were mixed to a uniform consistency to obtain a solvent-containing curable organopolysiloxane composition (composition 1 ). Next, the obtained organopolysiloxane composition was diluted with (E) a 50:50 weight% mixture of toluene and hexane to adjust the solids concentration to 3.0 mass%, and (D) a chloroplatinic acid/1 , 3-divinyl-1 ,1 , 3, 3-tetramethyl disiloxane complex (metallic platinum content: 0.6 mass%) was added in an amount such that the metallic platinum content of the composition as a whole was 120 ppm, and the composition was applied to the surface of a biaxially oriented polyester film (thickness: 38 pm; Mitsubishi Plastics) in an amount equivalent to 0.15 g/m2 and cured at 120°C for 30 seconds to yield a cured layer. The ease of applying a ceramic binder resin to the cured layer so obtained and the peel force required to peel the ceramic binder resin from the cured layer were measured. Results are shown in table 1.

Working example 2 - Composition 2

[0081] A composition 2 was obtained in a manner similar to working example 1 , except that the amount of the component (B) used in working example 1 was changed to 0.4 parts. Using this composition, the ease of applying a ceramic binder resin to the cured layer and the peel force required to peel the ceramic binder resin from the cured layer were measured. Results are shown in table 1.

Working example 3 - Composition 3

[0082] A composition 3 was obtained in a manner similar to working example 1 , except that the amount of the component (B) used in working example 1 was changed to 3.0 parts. Using this composition, the ease of applying a ceramic binder resin to the cured layer and the peel force required to peel the ceramic binder resin from the cured layer were measured. Results are shown in table 1 .

Working example 4 - Composition 4

[0083] (A) a1 ) 15.0 parts polydimethyl siloxane having hexenyl groups at both ends of the molecule and on a side chain (plasticity: 1 .15; hexenyl group vinyl (CH2=CH-) moiety content: 0.80 mass%), a2) 15.0 parts polydimethyl siloxane capped at the ends of the molecule with silanol groups and having a vinyl group on a side chain (plasticity: 1.20; vinyl group content: 0.90 mass%), (B) 1.5 parts dimethylsiloxane capped at the ends of the molecule by vinyl groups (plasticity: 1 .20; vinyl group content: 0.02 mass%), (C) 1 .5 parts 25 mPa-s viscosity dimethyl methylhydrogen polysiloxane capped by trimethyl siloxy groups at both ends of the molecule so that the SiH/Vi ratio of the composition as a whole is 1 .5, (E) 66.1 parts toluene, and (F) 1.0 parts 3-methyl-1 -butyne-3-ol were mixed to a uniform consistency to obtain a solvent-containing curable organopolysiioxane composition (composition 4). The obtained organopolysiioxane composition was then diluted with (E) a 50:50 weight% mixture of toluene and hexane to a solids concentration of 3.0 mass%, and a chloroplatinic acid/1 , 3-divinyl-1 ,1 , 3, 3-tetramethyl disiloxane complex (metallic platinum content: 0.6 mass%) was added to the composition in an amount such that the metallic platinum content was 120 ppm, after which the composition was applied to the surface of a biaxially oriented polyester film (thickness: 38 pm; Mitsubishi Plastics) in an amount equivalent to 0.15 g/m2 according to the method described above, then cured at 120°C for 30 seconds to obtain a cured layer, after which the ease of applying a ceramic binder resin to the cured layer and the peel force required to remove the ceramic binder resin from the cured layer were measured. Results are shown in table 1.

Working example 5 - Composition 5

[0084] 0.04 parts diethoxyacetophenone was further added to the composition 1 of working example 1 as a component (G) to obtain a solvent-containing curable organopolysiioxane composition (composition 5). Next, the obtained organopolysiioxane composition was diluted with (E) a 50:50 weight% mixture of toluene and hexane to adjust the solids concentration to 3.0 mass%, and (D) a chloroplatinic acid/1 ,3-divinyl-1 ,1 ,3,3-tetramethyl disiloxane complex (metallic platinum content: 0.6 mass%) was mixed in in an amount such that the metallic platinum content of the composition as a whole was 120 ppm, and the composition was applied to the surface of a biaxially oriented polyester film (thickness: 38 μιη; Mitsubishi Plastics) according to the method described above in an amount equivalent to 0.15 g/m2. After the curable organopolysiloxane composition had been applied, the substrate was heat-treated at 130°C for 30 seconds using a hot air circulation oven, then UV irradiated using an Eye Graphics Eye Grandage curing apparatus (total irradiation energy: 110 mJ/cm2) to form a layer of cured organopolysiloxane on the surface of the polyester film. The ease of applying a ceramic binder resin to the layer of cured organopolysiloxane and the peel force required to separate the ceramic binder resin from the cured layer were measured. Results are shown in table 1.

Working example 6 - Composition 6

[0085] 0.04 parts diethoxyacetophenone was added to the composition 4 of working example 4 as a component (G) to obtain a solvent-containing curable organopolysiloxane composition (composition 6). Next, the obtained organopolysiloxane composition was diluted with (E) a 50:50 weight% mixture of toluene and hexane to adjust the solids concentration to 3.0 mass%, and (D) a chloroplatinic acid/1 , 3-divinyl-1 ,1 , 3, 3-tetramethyl disiloxane complex (metallic platinum content: 0.6 mass%) was mixed in in an amount such that the metallic platinum content of the composition as a whole was 120 ppm, and the composition was applied to the surface of a biaxially oriented polyester film (thickness: 38 μηη; Mitsubishi Plastics) according to the method described above in an amount equivalent to 0.15 g/m2. After the curable organopolysiloxane composition had been applied, the polyester film was heat-treated at 130°C for 30 seconds using a hot air circulation oven, then UV irradiated using an Eye Graphics Eye Grandage curing apparatus (total irradiation energy: 110 mJ/cm2) to form a layer of cured organopolysiloxane on the surface of the polyester film. The ease of applying a ceramic binder resin to the layer of cured organopolysiloxane and the peel force required to separate the ceramic binder resin from the cured layer were measured. Results are shown in table 1.

Working example 7 - Composition 7

[0086] A composition 7 was obtained in a manner similar to working example 3, except that the type of the component (B) used in working example 3 was changed to dimethylsiioxane capped at the ends of the molecule with silanol groups (plasticity: 1 .43). Using this composition, the ease of applying a ceramic binder resin to the cured layer and the peel force required to peel the ceramic binder resin from the cured layer were measured.

Results are shown in table 1 . A little amount of silicone migration was observed on the film after peeling test.

Working example 8 - Composition 8

[0087] A composition 8 was obtained in a manner similar to working example 3, except that the type of the component (B) used in working example 3 was changed to dimethylsiloxane capped at the ends of the molecule with trimethylsilyl group (plasticity: 1 .29). Using this composition, the ease of applying a ceramic binder resin to the cured layer and the peel force required to peel the ceramic binder resin from the cured layer were measured.

Results are shown in table 1. A little amount of silicone migration was observed on the film after peeling test.

Comparative example 1 - Comparative composition 1

[0088] A comparative composition 1 was obtained in a manner similar to working example 1 , except that the component (B) of working example 1 was omitted. Using this

composition, the ease of applying a ceramic binder resin to the cured organopolysiloxane layer and the peel force required to peel the ceramic binder resin from the cured layer were measured. Results are shown in table 1 .

Comparative example 2 - Comparative composition 2

[0089] A comparative composition 2 was obtained in a manner similar to working example 1 , except that the amount of the component (B) used in working example 1 was changed to 5.0 parts. Using this composition, the ease of applying a ceramic binder resin to the cured organopolysiloxane layer and the peel force required to peel the ceramic binder resin from the cured layer were measured. Results are shown in table 1 .

Comparative example 3 - Comparative composition 3

[0090] 0.04 parts diethoxyacetophenone was added to the comparative composition 1 of comparative example 1 as a component (G) to obtain a solvent-containing curable organopolysiloxane composition (comparative composition 3). Next, the obtained organopolysiloxane composition was diluted with (E) a 50:50 weight% mixture of toluene and hexane to adjust the solids concentration to 3.0 mass%, and (D) a chloroplatinic acid/1 , 3-divinyl-1 ,1 , 3, 3-tetramethyl disiloxane complex (metallic platinum content: 0.6 mass%) was mixed in in an amount such that the metallic platinum content of the composition as a whole was 120 ppm, and the composition was applied to the surface of a biaxially oriented polyester film (thickness: 38 μιη; Mitsubishi Plastics) according to the method described above in an amount equivalent to 0. 5 g/m2. After the curable organopolysiloxane composition had been applied, the polyester film was heat-treated at 130°C for 30 seconds using a hot air circulation oven, then UV irradiated using an Eye Graphics Eye Grandage curing apparatus (total irradiation energy: 110 mJ/cm2) to form a layer of cured organopolysiloxane on the surface of the polyester film substrate. The ease of applying a ceramic binder resin to the layer of cured organopolysiloxane and the peel force required to separate the ceramic binder resin from the cured layer were measured. Results are shown in table 1 .

Comparative example 4 - Comparative composition 4

[0091] 0.04 parts diethoxyacetophenone was added to the comparative composition 2 of comparative example 2 as a component (G) to obtain a solvent-containing curable organopolysiloxane composition (comparative composition 4). Next, the obtained organopolysiloxane composition was diluted with (E) a 50:50 weight% mixture of toluene and hexane to adjust the solids concentration to 3.0 mass%, (D) a chloroplatinic acid/1 ,3- divinyl-1 , 1 ,3,3-tetramethyl disiloxane complex (metallic platinum content: 0.6 mass%) was further mixed in in an amount such that the metallic platinum content of the composition as a whole was 120 ppm, and the composition was applied to the surface of a biaxially oriented polyester film (thickness: 38 pm; Mitsubishi Plastics) according to the method described above in an amount equivalent to 0.15 g/m2. After the curable

organopolysiloxane composition had been applied, the polyester film was heat-treated at 130°C for 30 seconds using a hot air circulation oven, then UV irradiated using an Eye Graphics Eye Grandage curing apparatus (total irradiation energy: 110 mJ/cm2) to form a layer of cured organopolysiloxane on the surface of the polyester film substrate. The ease of applying a ceramic binder resin to the layer of cured organopolysiloxane and the peel force required to separate the ceramic binder resin from the cured layer were measured. Results are shown in table 1.

Comparative example 5 - Composition 5

[0092] (A) a1 ) 12.0 parts polydimethyl siloxane having hexenyl groups at both ends of the molecule and on a side chain (plasticity: 1 .15; hexenyl group vinyl (CH2=CH-) moiety content: 0.80 mass%), a2) 18.0 parts polydimethyl siloxane capped at both ends of the molecule with silanol groups and having a vinyl group on a side chain (plasticity: 1 .20; vinyl group content: 0.90 mass%), (B) 1.5 parts 1 .20 plasticity dimethylsiloxane capped at the ends of the molecule by vinyl groups (vinyl group content: 0.02 mass%), (C) 1.4 parts 25 mPa-s viscosity dimethyl methylhydrogen polysiloxane capped by trimethyl siloxy groups at both ends of the molecule (yielding a SiH Vi ratio for the composition as a whole of 1.5), (E) 66.1 parts toluene, and (F) 1.0 parts 3-methyl-1-butyne-3-ol were mixed to a uniform consistency to obtain a solvent-containing curable organopolysiloxane composition (composition 4). The obtained organopolysiloxane composition was then diluted with (E) a 50:50 weight% mixture of toluene and hexane to a solids concentration of 3.0 mass%, and a chloroplatinic acid/1 , 3-divinyl-1 , 1 , 3, 3-tetramethyl disiloxane complex (metallic platinum content: 0.6 mass%) was added to the composition in an amount such that the metallic platinum content was 120 ppm to obtain a curable composition. The composition was applied to the surface of a biaxially oriented polyester film (thickness: 38 μητι; Mitsubishi Plastics) in an amount equivalent to 015 g/m2 according to the method described above, then cured at 120°C for 30 seconds to obtain a cured layer, after which the ease of applying a ceramic binder resin to the cured layer and the peel force required to remove the ceramic binder resin from the cured layer were measured. Results are shown in table 1.

Table 1

^*a little amount of silicone migration was observed on the film after peeling test.

[0093] As is apparent from the results shown in table 1 , the cured polyorganosiloxane layers of the release films obtained in working examples 1 to 8 polyorganosiloxane exhibited superior ease of ceramic binder resin application, and the ceramic binder resin could be separated from the cured polyorganosiloxane layer with little peel force, indicating superior ceramic binder resin releasability. Meanwhile, the cured polyorganosiloxane layers obtained using comparative examples 1 to 5 were unsatisfactory in terms either of ease of ceramic binder resin application or releasability.

Claims

1. A curable organopolysiloxane composition containing:

(A) an organopolysiloxane or organopolysiloxane mixture having a form of anywhere from a liquid having a viscosity of 20 mPa-s or greater at 25°C to a gum that exhibits plasticity at 25°C, the organopolysiloxane or organopolysiloxane mixture containing the following components a1 ) and a2) at a mass ratio of 100:0 to 50:50: a1 ) at least one type of organopolysiloxane comprising an alkenyl group having 4 to 12 carbon atoms, the alkenyl group having a vinyl

(CH2=CH-) moiety content of 0.5 to 3.0 mass%, and

(B) an organopolysiloxane having a form of anywhere from a liquid having a viscosity of 1 ,000,000 mPa-s or greater at 25°C to a gum that exhibits plasticity at 25°C, the organopolysiloxane optionally comprising an alkenyl group having 2 to 12 carbon atoms, the alkenyl group having a vinyl (CH2=CH-) moiety content of less than 0.100 mass%; preferably at least 0.005 mass %;

(D) a hydrosilylation catalyst; and

(E) if necessary, any selected organic solvent;

the mass ratio of components (A) and (B) being in a range from 90:10 to 99:1.

2. The curable organopolysiloxane composition according to claim 1 , further containing an organic solvent.

3. The curable organopolysiloxane composition according to claim 1 or 2, wherein the

hydrosilylation catalyst is a platinum-based catalyst.

4. The curable organopolysiloxane composition according to any one of claims 1 to 3,

wherein the component (A) is an organopolysiloxane or organopolysiloxane mixture having a form of anywhere from a liquid having a viscosity of 1 ,000,000 mPa-s or greater at 25°C to a gum that exhibits plasticity at 25°C.

5. The curable organopolysiloxane composition according to any one of claims 1 to 4,

wherein the component a1 ) is a1-1 ) an organopolysiloxane comprising a hexenyl group having 4 to 12 carbon atoms as an alkenyl group.

6. The curable organopolysiloxane composition according to any one of claims 1 to 5,

wherein the component a2) is a2-1 ) an organopolysiloxane comprising a vinyl group having 2 to 3 carbon atoms as an alkenyl group.

7. The curable organopolysiloxane composition according to any one of claims 1 to 6, wherein the component (B) is a Dimethylpolysiloxane comprising an alkenyl group having 2 to 12 carbon atoms, the alkenyl group having a vinyl (CH2=CH-) moiety content of at least 0.005 mass% and less than 0.100 mass%

8. The curable organopolysiloxane composition according to any one of claims 1 to 6, wherein the component (B) is a dimethylpolysiloxane capped at both ends with dimethyl vinyl siloxy groups.

9. The solvent-containing curable organopolysiloxane composition according to any one of claims 1 to 8, further containing (G) a photopolymerization initiator.

10. The curable organopolysiloxane composition according to any one of claims 1 to 9,

wherein the composition has an overall viscosity at 25°C of 100 to 50,00 mPa-s.

11. A sheet-like article comprising a cured layer formed by curing the curable

organopolysiloxane composition according to any one of claims 1 to 10 and a sheet-like substrate.

12. The sheet-like article according to claim 11 , obtained by applying the curable

organopolysiloxane composition according to any one of claims 1 to 11 to the sheet-like substrate, following by curing the applied composition.

13. The sheet-like article according to claim 11 or 12, wherein the cured layer is obtained by applying 0.01 to 0.5 g/m2 of the curable organopolysiloxane composition according to any one of claims 1 to 10 to the sheet-like substrate, followed by curing the applied composition.

14. The sheet-like article according to any one of claims 11 to 13, wherein curing is performed using heat, energy radiation, or a combination of heat and energy radiation.

15. The sheet-like article according to any one of claims 11 to 14, wherein the sheet-like substrate is a plastic film.

16. A release film for use with a dielectric ceramic layer-forming material, the film being

constituted by the sheet-like article according to any one of claims 11 to 15.

17. A release film for use in forming a ceramic green sheet, the film being constituted by the sheet-like article according to any one of claims 11 to 15.

18. A method of manufacturing a dielectric ceramic layer-forming material or a ceramic green sheet, the method comprising a step of using the release film for use with a dielectric ceramic layer-forming material according to claim 16 or the release film for forming a ceramic green sheet according to claim 17, applying a ceramic slurry onto the cured organopolysiloxane layer on the film, and drying the applied ceramic slurry.

19. The manufacturing method according to claim 18, the method being a method of

manufacturing a ceramic green sheet.