Silicone release polyester film and method for manufacturing the same

Abstract

The present invention provides a silicone release polyester film with excellent light-peelability properties, which can be suitably used as a carrier film in the manufacture of multilayer ceramic capacitors, and a method for manufacturing the same. [Solution] A silicone release polyester film having a coating layer formed by drying after being coated using a release coating composition comprising: silicone (A) having a number average molecular weight of 25,000 to 45,000 and containing 3 to 30 alkenyl groups in one molecule; silicone (B) having a number average molecular weight of 10,000 to 25,000 and having alkenyl groups only at both ends in one molecule; silicone (C) having a number average molecular weight of 2,000 to 10,000 and having hydrogen atoms directly bonded to Si atoms represented by Si-H groups; and a platinum-based catalyst.

Description

[Technical Field]

[0001] The present invention relates to a silicone release polyester film. More specifically, the present invention relates to a silicone release polyester film that has release properties and adhesion suitable for molding from light to heavy peeling, for example, in the molding of ceramic green sheets used in the manufacture of multilayer ceramic capacitors, and that can prevent tearing and deformation of the sheets, and a method for manufacturing the same. [Background technology]

[0002] In the manufacture of multilayer ceramic capacitors, release films are used as carrier films for molding ceramic green sheets. Polyester film is particularly used as the base material for the release film due to its dimensional stability and heat resistance. In recent years, while multilayer ceramic capacitors have become smaller and larger in capacitance, the need for high reliability for automotive applications has increased, leading to a growing demand for improved quality of ceramic green sheets.

[0003] With the thinning and increased reliability of ceramic green sheets, the thickness of the dried sheet is now in the range of a few micrometers or less. Therefore, the carrier film requires particularly easy release properties. As the thickness decreases, the rigidity of the ceramic green sheet decreases, and the peeling force of conventional release films causes tearing or deformation when peeling the green sheet, worsening the chip defect rate, thus requiring easy release properties.

[0004] Therefore, there is a need to reduce the peeling force of the release film, and a method has been proposed to adjust the peeling force by controlling the cross-linking structure of the silicone (for example, Patent Document 1). However, this method of controlling the cross-linking structure of the release layer has the problem of being costly, as it requires the design of new polymers or cross-linking agents with special structures, or requires stronger energy during ultraviolet irradiation or electron beam irradiation.

[0005] Furthermore, a release layer consisting of a silicone resin having a cross-linked structure and a silicone resin not having a cross-linked structure has been proposed (for example, Patent Document 2). However, this method has the problem that, because the solvent of the coating agent for forming the release layer is an organic solvent, the organic solvent treatment equipment during coating and drying becomes large-scale, and the running costs of treating the volatilized organic solvent are also incurred, resulting in high costs.

[0006] Furthermore, there are issues related to the working environment and safety concerns such as organic solvent explosions and fires. Although methods that do not use organic solvents have been proposed (for example, Patent Document 3), these methods have problems such as increased viscosity of the coating agent making handling difficult and making uniform coating difficult. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2006-7689 [Patent Document 2] Japanese Patent Publication No. 2008-254207 [Patent Document 3] Japanese Patent Publication No. 2003-192987 [Overview of the project] [Problems that the invention aims to solve]

[0008] In view of the above circumstances, the present invention aims to provide a silicone release polyester film with excellent easy-release properties that can be peeled off without tearing or other damage even when it is a very thin film, and a method for manufacturing the same, which can be suitably used as a carrier film in the manufacture of multilayer ceramic capacitors, for example. [Means for solving the problem]

[0009] As a result of intensive studies to solve the above problems, the inventors of the present invention have found that the above problems can be solved by using a specific polydimethylsilicone and maximizing the crosslink density in the process of forming the release layer, and have completed the present invention.

[0010] That is, the present invention provides the following silicone release polyester film (silicone release polyester film).

[0011] [1] An aqueous dispersion (1) of a silicone (A) having a number average molecular weight of 25,000 or more and containing three or more alkenyl groups in one molecule, An aqueous dispersion (2) of a silicone (B) having a number average molecular weight of 25,000 or less and having alkenyl groups only at both ends in one molecule, An aqueous dispersion (3) of a silicone (C) having a number average molecular weight of 10,000 or less and having a hydrogen atom directly bonded to a Si atom represented by a Si-H group, and A platinum-based catalyst, A silicone release polyester film having a coating layer formed using a release coating composition containing the same, When the total solid content of the silicone (A), the silicone (B), and the silicone (C) is 100 parts by mass, the silicone (A) is 80 parts by mass or more, the silicone (B) is 2 parts by mass or more and 20 parts by mass or less, and the silicone (C) is 2 parts by mass or more and 20 parts by mass or less, Silicone release polyester film.

[0012] [2] The silicone release polyester film according to [1], wherein the silicone (A) has alkenyl groups at both ends and side chains in one molecule.

[0013] [3] The silicone release polyester film according to [1] or [2], wherein the alkenyl group of the silicone (A) is a vinyl group.

[0014] [4] The silicone release polyester film according to any one of [1] to [3], wherein the alkenyl group of the above silicone (B) is a vinyl group.

[0015] [5] The silicone release polyester film according to any one of [1] to [4], wherein the alkenyl groups of the above silicone (A) and above silicone (B) are vinyl groups.

[0016] [6] The content of the above platinum-based catalyst is 120 ppm or more relative to the total amount of the above silicone (A) and the above silicone (B), as described in any of [1] to [5].

[0017] [7] A silicone release polyester film according to any one of [1] to [6], used for molding ceramic green sheets in the manufacture of multilayer ceramic capacitors.

[0018] Furthermore, the present invention provides a method for manufacturing a silicone release polyester film.

[0019] [8] A method for manufacturing a silicone release polyester film, A water dispersion (1) of silicone (A) having a number average molecular weight of 25,000 or more and containing 3 or more alkenyl groups in one molecule, A water dispersion (2) of silicone (B) having a number average molecular weight of 25,000 or less and having alkenyl groups only at both ends of the molecule, A water dispersion (3) of silicone (C) having a number average molecular weight of 10,000 or less, and having hydrogen atoms directly bonded to Si atoms represented by Si-H groups, and platinum catalyst, The process includes forming a coating layer using a release coating composition containing the following: When the total solid content of the above silicones (A), (B), and (C) is 100 parts by mass, silicone (A) is contained in an amount of 80 parts by mass or more, silicone (B) in an amount of 2 parts by mass or more and 20 parts by mass or less, and silicone (C) in an amount of 2 parts by mass or more and 20 parts by mass or less. A method for manufacturing a silicone release polyester film.

[0020] [9] The above-mentioned silicone (A) has alkenyl groups at both ends and in the side chain in one molecule, according to the manufacturing method described in [8].

[0021]

[10] The manufacturing method according to [8] or [9], wherein the alkenyl groups of the above silicone (A) and above silicone (B) are vinyl groups. [Effects of the Invention]

[0022] The silicone release polyester film of the present invention, having the above configuration, can provide a release polyester film with moderately low peel strength that allows even very thin films to be peeled off without tearing or other damage, and with excellent uniformity of the release layer, making it suitable as a release film for sheet molding. The release polyester film of the present invention, possessing such characteristics, can be suitably used, for example, as a carrier film for molding ceramic green sheets used in ceramic multilayer capacitors.

[0023] Furthermore, the method for producing a silicone release polyester film according to the present invention makes it possible to efficiently and easily obtain a silicone release polyester film having the above-mentioned characteristics. [Modes for carrying out the invention]

[0024] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments.

[0025] <Silicone release polyester film> The silicone release polyester film of the present invention A water dispersion (1) of silicone (A) having a number average molecular weight of 25,000 or more and containing 3 or more alkenyl groups in one molecule, A water dispersion (2) of silicone (B) having a number average molecular weight of 25,000 or less and having alkenyl groups only at both ends of the molecule, A water dispersion (3) of silicone (C) having a number average molecular weight of 10,000 or less, and having hydrogen atoms directly bonded to Si atoms represented by Si-H groups, and platinum catalyst, A silicone release polyester film having a coating layer formed using a release coating composition containing, When the total solid content of silicone (A), silicone (B), and silicone (C) is 100 parts by mass, silicone (A) is contained in an amount of 80 parts by mass or more, silicone (B) in an amount of 2 parts by mass or more and 20 parts by mass or less, and silicone (C) in an amount of 2 parts by mass or more and 20 parts by mass or less.

[0026] [Polyester film] The polyester film of the present invention can use any known polyester, but for example, the following can be preferably used.

[0027] (polyester) The polyester constituting the polyester film used as the base film (hereinafter sometimes referred to as "base") in the present invention is not particularly limited, and a polyester film formed from polyester commonly used as a base material for release films can be used. Preferably, it is a crystalline linear saturated polyester consisting of an aromatic dibasic acid component and a diol component, and more preferably, polyethylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, poly(1,4-cyclohexylenedimethylene terephthalate), polytrimethylene terephthalate, or copolymers mainly composed of these resin components. Among these, a polyester film formed from polyethylene terephthalate is particularly preferred. The polyethylene terephthalate preferably has a repeating unit of ethylene terephthalate of 90 mol% or more, more preferably 95 mol% or more, and may also have small amounts of other dicarboxylic acid components and diol components copolymerized. For example, from the viewpoint of cost, it is preferable to have one produced only from terephthalic acid and ethylene glycol.

[0028] Furthermore, known additives, such as antioxidants, light stabilizers, ultraviolet absorbers, and crystallizers, may be added within a range that does not impair the effect of the release film of the present invention. The polyester film is preferably a biaxially oriented polyester film due to reasons such as its high bidirectional modulus of elasticity.

[0029] The intrinsic viscosity of the polyester film described above is preferably 0.50 dl / g or more and 0.70 dl / g or less, and more preferably 0.52 dl / g or more and 0.65 dl / g or less. When the intrinsic viscosity is 0.50 dl / g or more, it is preferable because breakage does not occur frequently during the stretching process. Conversely, when it is 0.70 dl / g or less, it is preferable because the cutability is good when cutting to a predetermined product width and dimensional defects do not occur. In addition, it is preferable that the raw material pellets are thoroughly vacuum dried.

[0030] In this specification, when the term "polyester film" is used, it refers to a polyester film having surface layer A and surface layer B (a laminated film).

[0031] The method for producing the polyester film in the present invention is not particularly limited, and conventional methods can be used. For example, the polyester can be melted in an extruder, extruded into a film, and cooled in a rotating cooling drum to obtain an unstretched film, which can then be obtained by biaxial stretching. The biaxially oriented film can be obtained by sequentially biaxially stretching a uniaxially oriented film in the longitudinal or transverse direction in the transverse or longitudinal direction, or by simultaneously biaxially stretching an unstretched film in the longitudinal and transverse directions.

[0032] In the present invention, it is preferable that the stretching temperature during stretching of the polyester film be above the secondary transition temperature (Tg) of the polyester. It is also preferable to stretch the film by 1 to 8 times, and particularly by 2 to 6 times, in both the longitudinal and transverse directions.

[0033] The polyester film described above preferably has a thickness of 12 μm to 100 μm, more preferably 16 μm to 50 μm, and more preferably 19 μm to 33 μm. A film thickness of 12 μm or more is preferable because it does not risk deformation due to heat during film production, processing, or molding. On the other hand, a film thickness of 100 μm or less is preferable because it does not result in an excessively large amount of film being discarded after use, thus reducing the environmental burden.

[0034] The polyester film substrate described above may be a single layer or a multilayer of two or more layers. For example, the substrate film may be a polyester film having a surface layer A that substantially does not contain particles with a particle size of 1.0 μm or larger, and a surface layer B that contains particles. Preferably, surface layer A substantially does not contain inorganic particles with a particle size of 1.0 μm or larger.

[0035] In this embodiment, the surface layer A may contain particles with a particle size of less than 1.0 μm and 1 nm or larger. By substantially excluding particles with a particle size of 1.0 μm or larger, such as inorganic particles, from the surface layer A, it is possible to reduce the transfer of the particle shape in the substrate to the resin sheet, which can cause defects.

[0036] In one embodiment, by not including particles with a particle size of less than 1.0 μm in the surface layer A, it is possible to more effectively suppress defects caused by the transfer of the particle shape in the substrate to the resin sheet.

[0037] In one embodiment, the polyester film substrate is preferably a laminated film having a surface layer A that is substantially free of inorganic particles on at least one side. This makes it possible to more effectively suppress defects caused by the transfer of the particle shape in the substrate to the resin sheet.

[0038] For example, a surface layer A that substantially does not contain particles with a particle size of less than 1.0 μm is preferably also substantially free of particles with a particle size of 1.0 μm or larger.

[0039] In this invention, "substantially free of particles" means, for example, in the case of inorganic particles smaller than 1.0 μm, that the content of inorganic elements is 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit when quantified by fluorescence X-ray analysis. This is because even without actively adding particles to the film, contaminants originating from foreign substances, or dirt adhering to the raw material resin or the lines and equipment in the film manufacturing process, may peel off and become mixed into the film. Furthermore, "substantially free of particles with a particle size of 1.0 μm or larger" means that the film actively does not contain particles with a particle size of 1.0 μm or larger.

[0040] In the case of a laminated polyester film consisting of two or more layers, it is preferable that the surface opposite to surface layer A, which substantially does not contain inorganic particles, has a surface layer B that may contain inorganic particles.

[0041] In terms of the lamination structure, if the layer on the side to which the release layer is applied is designated as layer A, the layer on the opposite side as layer B, and the remaining core layer as layer C, then the layer configuration in the thickness direction can be a laminated structure such as release layer / A / B or release layer / A / C / B. Naturally, layer C may consist of multiple layers. Furthermore, the surface layer B does not need to contain inorganic particles. In that case, it is preferable to provide a coating layer containing at least inorganic particles and a binder on the surface layer B in order to provide slipperiness for winding the film into a roll.

[0042] In the polyester film substrate of the present invention, the surface layer B that forms the opposite side of the surface to which the release layer is applied preferably contains inorganic particles from the viewpoint of the film's slipperiness and ease of air release, and it is particularly preferable to use silica particles and / or calcium carbonate particles. The inorganic particle content is preferably 5,000 ppm to 15,000 ppm in total in the surface layer B.

[0043] In this case, the average surface roughness (Sa) of the surface layer B film is preferably in the range of 1 nm to 40 nm. More preferably, it is in the range of 5 nm to 35 nm. When the total amount of silica particles and / or calcium carbonate particles is 5000 ppm or more and Sa is 1 nm or more, when the film is wound into a roll, air can be released uniformly, resulting in a good winding shape and good flatness, making it suitable for the manufacture of ultrathin ceramic green sheets. Furthermore, when the total amount of silica particles and / or calcium carbonate particles is 15000 ppm or less and Sa is 40 nm or less, lubricant aggregation is less likely to occur and no coarse protrusions are formed, resulting in stable quality during the manufacture of ultrathin ceramic green sheets, which is preferable.

[0044] In addition to silica and / or calcium carbonate, other inert inorganic particles and / or heat-resistant organic particles can be used as particles in the above-mentioned B layer, but silica particles and / or calcium carbonate particles are more preferable from the viewpoint of transparency and cost. Other inorganic particles that can be used include alumina-silica composite oxide particles and hydroxyapatite particles. Heat-resistant organic particles include cross-linked polyacrylic particles, cross-linked polystyrene particles, and benzoguanamine particles. When silica particles are used, porous colloidal silica is preferred, and when calcium carbonate particles are used, light calcium carbonate surface-treated with a polyacrylic acid-based polymer compound is preferred from the viewpoint of preventing lubricant detachment.

[0045] The average particle size of the inorganic particles added to the surface layer B is preferably 0.1 μm or more and 2.0 μm or less, and particularly preferably 0.3 μm or more and 1.0 μm or less. An average particle size of 0.1 μm or more is preferable because it provides good slipperiness for the release film. Furthermore, an average particle size of 2.0 μm or less is preferable because it does not adversely affect the smoothness of the surface of the release layer, thus preventing the formation of pinholes in the ceramic green sheet.

[0046] Furthermore, a coating layer may be applied to the surface of surface layer A and / or surface layer B before stretching or after uniaxial stretching during the film-forming process in order to improve the adhesion of release layers and the like that to be applied later, or to prevent static electricity, and corona treatment may also be applied.

[0047] In the present invention, the ceramic sheet release properties of the silicone release polyester film can be measured, for example, as follows: The prepared slurry is uniformly coated onto the coating layer of the release polyester film so that the thickness after drying is 2 μm or the like, and then dried to form a ceramic sheet. Next, the release polyester film on which the ceramic sheet has been formed is cut to a size such as 25 mm × 150 mm, and adhesive tape is attached to the ceramic sheet side to prepare a test piece.

[0048] The obtained test specimens are conditioned for 24 hours under conditions of, for example, 23°C and 50% humidity. Then, the ceramic sheet (adhesive tape side) is peeled off using a tensile testing machine at a peel angle of 90° and a peel speed of 10 m / min, and the peel strength is measured. Regarding the peel strength of the ceramic sheet, for example, under the conditions of the example, a peel strength of less than 0.60 N / mm is preferred, and a peel strength of 0.55 or less is considered more preferred.

[0049] [Release Coating Composition] The release coating composition of the present invention is A water dispersion (1) of silicone (A) having a number average molecular weight of 25,000 or more and containing 3 or more alkenyl groups in one molecule, A water dispersion (2) of silicone (B) having a number average molecular weight of 25,000 or less and having alkenyl groups only at both ends of the molecule, A water dispersion (3) of silicone (C) having a number average molecular weight of 10,000 or less, and having hydrogen atoms directly bonded to Si atoms represented by Si-H groups, and platinum catalyst, Includes.

[0050] The alkenyl group-containing silicone component in the present invention is composed of at least two components with different molecular weights.

[0051] (Alkenyl group-containing silicone (A)) In the present invention, a silicone (A) having a number average molecular weight of 25,000 or more and containing three or more alkenyl groups in one molecule (hereinafter sometimes referred to as "silicone (A)" or "alkenyl group-containing silicone (A)") is used.

[0052] The above alkenyl group-containing silicone (A) preferably has alkenyl groups at both ends and in the side chains within one molecule.

[0053] In addition, the alkenyl group-containing silicone (A) contains at least 3 or more alkenyl groups in one molecule, and for example, it may be 4 or more, 5 or more, 6 or more, etc. Also, the upper limit of the number of alkenyl groups in the alkenyl group-containing silicone (A) may be any as long as the effects of the present invention can be achieved, and for example, it can be 30 or less, 20 or less, 15 or less, 10 or less, etc. If the alkenyl group-containing silicone (A) has 2 or less alkenyl groups in one molecule, the crosslinking reactivity decreases, and the peeling of the ceramic sheet becomes difficult.

[0054] Examples of the alkenyl group-containing silicone (A) include organopolysiloxanes having a structure represented by the following general formula (I). R 1 a R 2 b SiO (4-a-b) / 2 ···(I) (In formula (I), R 1 is an alkenyl group having 2 to 8 carbon atoms, R 2 is a monovalent saturated hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl group or an aryl group, a is 0 to 3, b is 0 to 2, and a + b ≤ 3, respectively representing integers that satisfy this condition.)

[0055] The alkenyl group-containing silicone (A) may have any of a linear structure, a branched-chain structure, a structure having a partial crosslink, or a mixture thereof.

[0056] R 1 Examples of the alkenyl group having 2 to 8 carbon atoms represented by include vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, etc. Among these, the vinyl group is particularly preferable.

[0057] In addition, examples of the alkyl group represented by R 2 include methyl group, ethyl group, propyl group, butyl group, etc., and examples of the aryl group include phenyl group, tolyl group, etc. Among them, it is preferable that 80 mol% or more of the substituents of R 2 are methyl groups in terms of easy peeling property.

[0058] Furthermore, it is preferable, from the viewpoint of the curing speed and pot life of the composition, that the amount of silicon atoms having alkenyl groups in the alkenyl group-containing silicone (A) is in the range of 0.05 to 20 mol% relative to the total silicon atoms. If the proportion of silicon atoms having alkenyl groups is below the lower limit, the curing speed of the composition will decrease, and it may become difficult to efficiently form a cured silicone coating during film formation. Also, if the proportion of silicon atoms having alkenyl groups exceeds the upper limit, the pot life of the composition may be shortened.

[0059] Examples of the alkenyl group-containing silicone (A) mentioned above include the silicone represented by the following formula (1-1). [ka] (In equation (1-1), m is 2.5 and n is 400.)

[0060] The alkenyl group-containing silicone (A) described above can be produced by known methods. Furthermore, it is preferable that the alkenyl group-containing silicone in the present invention be included in the composition in the form of an aqueous dispersion (aqueous dispersion (1)).

[0061] When the above alkenyl group-containing silicone (A) is made into an aqueous dispersion (aqueous dispersion (1)), the content of the above alkenyl group-containing silicone (A) in 100 parts by mass of the above aqueous dispersion (1) can be, for example, 1 part by mass or more and 80 parts by mass or less, 3 parts by mass or more and 75 parts by mass or less, 5 parts by mass or more and 70 parts by mass or less, 10 parts by mass or more and 65 parts by mass or less, or 15 parts by mass or more and 60 parts by mass or less. If the content is 10 parts by mass or less, the long-term stability of the emulsion may deteriorate, and if it is 80 parts by mass or more, the viscosity may increase and the dispersibility may deteriorate.

[0062] The number-average molecular weight of the above alkenyl group-containing silicone (A) is 25,000 or more, and may be, for example, 26,000 or more, 27,000 or more, 28,000 or more, 30,000 or more, etc. The upper limit of the number-average molecular weight of the above alkenyl group-containing silicone (A) is sufficient to achieve the effects of the present invention, and may be, for example, 45,000 or less, 40,000 or less, etc. Furthermore, if it exceeds 50,000, the emulsion of the aqueous dispersion may become unstable.

[0063] The content of the alkenyl group-containing silicone (A) is preferably 80 parts by mass or more and 96 parts by mass or less, when the total solid content of the alkenyl group-containing silicone (A) and silicone (B) and Si-H group-containing silicone (C) is taken as 100 parts by mass. For example, it may be 85 parts by mass or more and 95 parts by mass or less, 88 parts by mass or more and 94 parts by mass or less, 90 parts by mass or more and 92 parts by mass or less, etc. If the content exceeds 96 parts by mass, the amount of high molecular weight silicone increases and the crosslinking density decreases. Also, if the content is 80 parts by mass or less, the crosslinking points between high molecular weight silicone and low molecular weight silicone decrease and the crosslinking density decreases.

[0064] (Alkenyl group-containing silicone (B)) A silicone (B) having a number-average molecular weight of 25,000 or less and containing alkenyl groups only at both ends of a single molecule (hereinafter sometimes referred to as "silicone (B)" or "alkenyl group-containing silicone (B)") is used.

[0065] The above alkenyl group-containing silicone (B) has alkenyl groups only at both ends of the molecule. It is presumed that the above low molecular weight alkenyl group-containing silicone (B) can perform a crosslinking reaction that complements the crosslinking network of the above high molecular weight alkenyl group-containing silicone (A), maximizing the crosslinking density as much as possible and enabling easy peeling from the ceramic sheet. However, the scope of the patent is not limited to the above mechanism only.

[0066] Examples of the alkenyl group-containing silicone (B) include organopolysiloxanes having the structure shown by the following general formula (I'). R 1’ a’ R 2’ b’ SiO (4-a’-b’) / 2 ...(I') (In formula (I'), R 1’ R is an alkenyl group having 2 to 8 carbon atoms. 2’ (where a' is a monovalent saturated hydrocarbon group having 1 to 16 carbon atoms, selected from alkyl or aryl groups, and a' is an integer between 0 and 1, b' is an integer between 0 and 2, and a' + b' ≤ 3.)

[0067] The alkenyl group-containing silicone (B) may have a linear structure, a branched structure, partially cross-linked structures, or a mixture thereof.

[0068] R 1’ Examples of alkenyl groups having 2 to 8 carbon atoms, represented by , include vinyl groups, allyl groups, butenyl groups, pentenyl groups, and hexenyl groups. Among these, vinyl groups are particularly preferred. The above alkenyl group-containing silicone (B) has alkenyl groups only at both ends of the molecule.

[0069] Also, R 2’ Examples of alkyl groups represented by include methyl, ethyl, propyl, and butyl groups, and examples of aryl groups include phenyl and tolyl groups. Among these, R 2’ It is preferable in terms of easy peelability that 80 mol% or more of the substituents are methyl groups.

[0070] Furthermore, it is preferable, from the viewpoint of the curing speed and pot life of the composition, that the amount of silicon atoms having alkenyl groups in the alkenyl group-containing silicone (B) is in the range of 0.05 to 20 mol% relative to the total silicon atoms.

[0071] Examples of the alkenyl group-containing silicone (B) mentioned above include silicones represented by the following formula (1-2). [ka] (In equation (1-2), n is 200.)

[0072] The alkenyl group-containing silicone (B) described above can be produced by known methods. Furthermore, it is preferable that the alkenyl group-containing silicone in the present invention be included in the composition in the form of an aqueous dispersion (aqueous dispersion (2)).

[0073] The number-average molecular weight of the above alkenyl group-containing silicone (B) is 25,000 or less, and may be, for example, 24,000 or less, 23,000 or less, 22,000 or less, 21,000 or less, 20,000, 19,000 or less, 18,000 or less, 17,000 or less, etc. The lower limit of the number-average molecular weight of the above alkenyl group-containing silicone (B) is as long as it provides the effects of the present invention, and may be, for example, 10,000 or more, 11,000 or more, 12,000 or more, etc. If the molecular weight is 25,000 or more, it is almost the same as that of silicone A, so the crosslinking density is not improved, on the other hand, if the molecular weight is too small, it becomes difficult to form a crosslinking network between silicone A.

[0074] The above alkenyl group-containing silicone (B) can be manufactured by known methods. Furthermore, it is preferable that the above alkenyl group-containing silicone (B) is included in the composition in the form of an aqueous dispersion (aqueous dispersion (2)).

[0075] When the above alkenyl group-containing silicone (B) is made into an aqueous dispersion (aqueous dispersion (2)), the content of the above alkenyl group-containing silicone (B) in 100 parts by mass of the above aqueous dispersion (2) can be, for example, 1 part by mass or more and 80 parts by mass or less, 3 parts by mass or more and 70 parts by mass or less, 5 parts by mass or more and 65 parts by mass or less, 10 parts by mass or more and 60 parts by mass or less, or 15 parts by mass or more and 55 parts by mass or less. If the content is 10 parts by mass or less, the long-term stability of the emulsion may deteriorate, and if it is 80 parts by mass or more, the viscosity may increase and the dispersibility may deteriorate.

[0076] The content of the alkenyl group-containing silicone (B) is preferably 2 parts by mass or more and 20 parts by mass or less, when the total solid content of the alkenyl group-containing silicone (A) and silicone (B) and the Si-H group-containing silicone (C) is 100 parts by mass. For example, it may be 3 parts by mass or more and 18 parts by mass or less, 4 parts by mass or more and 15 parts by mass or less, 5 parts by mass or more and 10 parts by mass or less, etc.

[0077] (Si-H group-containing silicone (C)) In the present invention, an example of a silicone(C) having a hydrogen atom directly bonded to a Si atom represented by a Si-H group (hereinafter sometimes referred to as "silicone(C)" or "Si-H group-containing silicone(C)") is an organohydrogenpolysiloxane having the structure shown by the following general formula (II). R 3 c H d SiO (4-c-d) / 2 ...(II) (In formula (II), R 3 (where c is a monovalent saturated hydrocarbon group having 1 to 16 carbon atoms, selected from alkyl or aryl groups, and c is an integer between 0 and 2, and d is an integer between 1 and 3, satisfying c + d ≤ 3.)

[0078] The above Si-H group-containing silicone (C) may have either a linear or branched chain structure.

[0079] R 3Examples of alkyl groups represented by include methyl, ethyl, propyl, and butyl groups, and examples of aryl groups include phenyl and tolyl groups. Among these, R 3 It is preferable in terms of easy peelability that 50 mol% or more of the substituents are methyl groups.

[0080] From the viewpoint of curing properties, the above Si-H group-containing silicone (C) preferably has at least 3, and more preferably 5 or more, hydrogen atoms bonded to Si atoms in one silicone molecule.

[0081] Examples of the above-mentioned Si-H group-containing silicone (C) include silicone represented by the following formula (2). [ka] (In equation (2), o is 30 and p is 35.)

[0082] The above-mentioned Si-H group-containing silicone (C) can be manufactured by known methods. Furthermore, it is preferable that the Si-H group-containing silicone (C) in the present invention be included in the above composition in the form of an aqueous dispersion (aqueous dispersion (3)).

[0083] When the above Si-H group-containing silicone (C) is made into an aqueous dispersion (aqueous dispersion (3)), the content of the above alkenyl group-containing silicone (B) in 100 parts by mass of the above aqueous dispersion (3) can be, for example, 1 part by mass or more and 80 parts by mass or less, 3 parts by mass or more and 70 parts by mass or less, 5 parts by mass or more and 60 parts by mass or less, 8 parts by mass or more and 55 parts by mass or less, or 10 parts by mass or more and 50 parts by mass or less. If the content is 10 parts by mass or less, the long-term stability of the emulsion may deteriorate, and if it is 80 parts by mass or more, the viscosity may increase and the dispersibility may deteriorate.

[0084] The number-average molecular weight of the Si-H group-containing silicone (C) is 10,000 or less, and may be, for example, 8,000 or less, 7,000 or less, 6,000 or less, etc. If the number-average molecular weight is 10,000 or more, the function as a crosslinking agent becomes insufficient and the crosslinking density decreases. Furthermore, the lower limit of the number-average molecular weight of the Si-H group-containing silicone (C) is not particularly limited as long as the effects of the present invention are achieved, but may be, for example, 300 or more, 500 or more, 1,000 or more, 2,000 or more, etc.

[0085] The content of the Si-H group-containing silicone (C) is preferably 2 parts by mass or more and 20 parts by mass or less, when the total solid content of the alkenyl group-containing silicone (A) and silicone (B) and the Si-H group-containing silicone (C) is 100 parts by mass. For example, it may be 3 parts by mass or more and 18 parts by mass or less, 4 parts by mass or more and 15 parts by mass or less, 5 parts by mass or more and 10 parts by mass or less, etc. If the content is less than 2 parts by mass, the curing reaction will not proceed easily, and sufficient coating hardness may not be obtained. If the content exceeds 20 parts by mass, excessive Si-H will precipitate on the surface and adhere strongly to the green sheet, which may result in severe peeling.

[0086] (Ratio of Si-H groups to alkenyl groups) In the present invention, the ratio of the number of Si-H groups to the number of alkenyl groups (number of alkenyl groups in silicone (A) and silicone (B)) in the release coating composition (number of Si-H groups / number of alkenyl groups) is preferably in the range of 1.0 to 2.0. If the above ratio is below the lower limit, excess alkenyl groups will remain in the coated layer, which can easily change the peel strength over time and reduce the crosslinking density, potentially decreasing the uniformity of the peel force and the residual adhesion rate. Furthermore, if the above ratio exceeds the upper limit, highly reactive Si-H groups will remain in the coated layer, which can cause an increase in the peel force.

[0087] (Silicone content) In the release coating composition of the present invention, the total amount of alkenyl group-containing silicone solids (total amount of silicone (A) and silicone (B) solids) and Si-H group-containing silicone (C) solids is preferably 70% by mass or more, based on the solid mass of the composition. Furthermore, the more preferable content of each silicone solid is 80% by mass or more and 97% by mass or less. Here, silicone solids refer to the amount excluding the aqueous solvent, and the solid mass of the composition refers to the total amount of solids of each additive. If the total amount of silicone solids is less than the lower limit, the area covered by silicone on the film surface on which the coating film is formed will be reduced, which may result in increased peeling force and uneven peeling force.

[0088] (Aqueous solvent) Water is preferably used as the aqueous solvent for forming each of the silicone aqueous dispersions of the present invention. By using an aqueous solvent, a silicone release layer can be formed without using explosion-proof equipment and organic solvent recovery equipment that are required when using organic solvents during the release film manufacturing process.

[0089] (emulsifier) Each aqueous dispersion is prepared using an emulsifier to improve its stability and shear resistance. A nonionic emulsifier that does not affect the curing reaction of the silicone is preferred. Ionic emulsifiers may affect the curing reaction of the silicone and may also localize within the coating, for example, by bleeding out to the surface and affecting release properties.

[0090] Nonionic emulsifiers are preferably those with an HLB value in the range of 8 to 18. Examples include at least one selected from alkylene oxide adducts of higher alcohols or higher fatty acids, esters of alkylene oxide adducts of higher fatty acids and alcohols, alkylene oxide adducts of alkanolamides, alkylene oxide adducts of sorbitan esters, and alkylene oxide adducts of higher fatty acid glycerides. These may be used individually or in combination of two or more. Here, the HLB value is calculated using Griffin's formula.

[0091] Examples of alkylene oxides include ethylene oxide, propylene oxide, and butylene oxide, and one or more of these may be used. When multiple are used, the addition method can be block or random, but the HLB value is preferably in the range of 8 to 18, and more preferably in the range of 10 to 15. Among these nonionic emulsifiers, polyoxyethylene lauryl ether and polyoxyethylene tridecyl ether are preferred. If a nonionic emulsifier with an HLB value outside the above range is used as an emulsifier for a silicone aqueous dispersion, the emulsifying and dispersing power and the stability of the aqueous dispersion may decrease. The nonionic emulsifier is preferably used in an amount of 0.1% to 20% by mass relative to the total solids, more preferably in the range of 0.2% to 15% by mass, and even more preferably in the range of 0.5% to 10% by mass. Below this range, emulsification tends to be unsuccessful, and above this range, severe delamination may occur.

[0092] (catalyst) In the release coating composition constituting the coating layer of the present invention, it is preferable to use a catalyst to carry out an addition reaction between the above-mentioned silicone (A) and / or the above-mentioned silicone (B) and the above-mentioned silicone (C), and a platinum-based catalyst is particularly preferred.

[0093] (Platinum catalyst) Known platinum-based catalysts can be used, such as platinum chloride and chloroplatinic acid. Considering dispersibility in silicone, a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex (Karstedt catalyst) may also be used. By dispersing it simultaneously with the emulsification of the silicone, uniform dispersibility can be ensured. These catalysts may be used individually or in combination of two or more.

[0094] Preferably, the amount of platinum-based catalyst is such that the mass of platinum is in the range of 120 ppm to 800 ppm relative to the total mass of the aqueous dispersion (1) of silicone (A), the aqueous dispersion (2) of silicone (B), and the aqueous dispersion (3) of silicone (C). By keeping the amount within this range, sufficient curing of the silicone can be achieved. Furthermore, the generation of silicone aggregates can be suppressed, and a release polyester film with excellent surface properties can be obtained. If the mass ratio of platinum exceeds the upper limit, the addition reaction between the alkenyl group and the Si-H group is accelerated, and there is a tendency for silicone aggregates to be generated. From this viewpoint, the amount of platinum-based catalyst is, for example, 600 ppm or less, 500 ppm or less, 300 ppm or less, 250 ppm or less, etc. Also, if the mass ratio of platinum falls below the lower limit, the addition reaction does not proceed, and there is a tendency for poor curing of the silicone to occur. From the above perspective, the amount of platinum catalyst is, for example, 130 ppm or more, 140 ppm or more, 150 ppm or more, 200 ppm or more, etc.

[0095] (Crosslinking reaction inhibitor) To suppress the activity of platinum-based catalysts at room temperature, it is preferable that the aqueous coating composition contains a crosslinking reaction inhibitor. The crosslinking reaction inhibitor is preferably a crosslinking reaction inhibitor having an alkynyl group. The crosslinking reaction inhibitor having an alkynyl group is not particularly limited as long as it has an alkynyl group, but specific examples include 1-ethynyl-1-cyclohexanol, 4-ethyl-1-octin-3-ol, 3-methyl-1-dodecine-3-ol, 3,7,11-trimethyl-1-dodecine-3-ol, 1,1-diphenyl-2-propyne-3-ol, 3-ethyl-6-ethyl-1-nonine-3-ol, 3-methyl-1-pentadesine-3-ol, 2,5-dimethyl-3-hexyne-2,5-diol, and 3-phenyl-1-butyne-3-ol. As the alkynyl group, for example, an ethynyl group can be given as a preference. These may be used alone or in combination of two or more. Since the present invention employs an aqueous emulsion coating composition, it is preferable to use a crosslinking reaction inhibitor having an exemplified alkynyl group and a hydroxyl group, considering the balance between affinity and solubility in water, coordination ability to platinum, and boiling point.

[0096] The crosslinking reaction inhibitor content is preferably 5 ppm to 1000 ppm, more preferably 10 ppm to 700 ppm, and even more preferably 20 ppm to 500 ppm, relative to the mass of the aqueous coating composition used to form the release layer. When the crosslinking reaction inhibitor content is above the lower limit, the pot life is extended, the addition curing reaction of the silicone is less likely to proceed at room temperature, and silicone aggregates tend to be less likely to form. Furthermore, when the crosslinking reaction inhibitor content is below the upper limit, the silicone is less likely to migrate to the mating material after the mating material is removed, and the amount of reaction inhibitor that volatilizes during heat treatment is reduced, thus reducing contamination inside the oven.

[0097] Furthermore, the content of the crosslinking reaction inhibitor relative to the mass of platinum element is preferably 6 times or less, more preferably 5 times or less, and particularly preferably 4 times or less.

[0098] While the crosslinking reaction inhibitor having an ethynyl group is not particularly limited as long as it has an ethynyl group, in this invention, since an aqueous coating composition is used, it is preferable to use a crosslinking reaction inhibitor having an ethynyl hydroxyl group, such as 1-ethynylcyclohexanol, due to the balance between solubility in water and coordination ability to platinum, as well as volatility.

[0099] (Other ingredients) The release coating composition of the present invention may further contain, to the extent that it does not impair the objectives of the present invention, for example, an adhesion-enhancing agent to the substrate, a colorant, an ultraviolet absorber, particles, an antistatic agent, and the like.

[0100] (Preparation of silicone aqueous dispersion) In preparing each of the silicone aqueous dispersions of the present invention, one method is to emulsify them using the above-mentioned silicone components, aqueous solvent, and emulsifier. Known methods can be used to emulsify these components; for example, a method can be used in which pre-prepared silicone, an emulsifier, and other components are mechanically emulsified in an aqueous medium using a stirring device such as a homogenizer, an adiohomomicker, or an ultraplanetary mixer.

[0101] Furthermore, the particle size of the aqueous dispersion can be adjusted by adjusting the size of the stirring blade, the stirring speed, and the stirring time. The average particle size of each silicone aqueous dispersion of the present invention is preferably 200 nm or less, and more preferably 100 nm or more and 200 nm or less.

[0102] [Coated layer] In the present invention, a coating layer (release layer) is formed on at least one surface of a polyester film using the release coating composition of the present invention. The coating layer (release layer) of the present invention is formed by applying the release coating composition to the polyester film and then drying it.

[0103] In this invention, the thickness of the coating layer is preferably 5 nm to 70 nm after drying. If the thickness of the coating layer is less than the lower limit, the release properties may be insufficient, and if it exceeds the upper limit, the peel strength increases, and it becomes difficult to apply because it is necessary to increase the concentration of the coating solution or the amount of coating applied.

[0104] When applying the release coating composition of the present invention onto a polyester film, an aqueous coating solution containing the above composition is prepared, and the solid content concentration of the aqueous coating solution is preferably 20% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, based on the mass of the coating solution. If the solid content concentration in the aqueous coating solution is below the lower limit, the wettability to the polyester film may be insufficient. If the solid content concentration exceeds the upper limit, the stability of the coating solution and the appearance of the coating layer may deteriorate. Water is preferably used as the aqueous solvent to adjust the solid content concentration.

[0105] The aqueous coating solution can be applied to the polyester film at any stage, but it is preferable to apply it during the polyester film manufacturing process, and even more preferably to the polyester film before orientation crystallization is complete.

[0106] Here, the polyester film before crystal orientation is completed includes unstretched film, uniaxially oriented film in which the unstretched film is oriented in either the longitudinal direction (hereinafter sometimes referred to as the continuous film formation direction, longitudinal direction, or MD direction) or the transverse direction (hereinafter sometimes referred to as the direction perpendicular to the longitudinal direction, width direction, or TD direction), and even film that has been low-magnification stretched and oriented in both the longitudinal and transverse directions (biaxially oriented film before final re-stretching in the longitudinal or transverse direction to complete orientation crystallization). Among these, so-called in-line coating is preferred, in which an aqueous coating solution of the above composition is applied to the unstretched film or a uniaxially oriented film oriented in one direction, and then longitudinal stretching and / or transverse stretching and heat fixing are performed as is. The coating layer may be dried by the stretching process or heat fixing treatment after coating, and a drying process may be added as needed. Furthermore, when curing the composition using a catalyst to obtain a cured film, curing can be performed by the stretching process or heat fixing treatment, but a curing process may be added as needed.

[0107] When applying an aqueous coating solution to a polyester film, it is preferable to perform a physical treatment on the film surface, such as corona surface treatment, flame treatment, or plasma treatment, as a preliminary treatment to improve the coating properties, or to use the aforementioned emulsifier as a wetting agent together with the composition.

[0108] Any known coating method can be applied. For example, roll coating, gravure coating, roll brushing, spray coating, air knife coating, impregnation, curtain coating, etc., can be used individually or in combination.

[0109] <Method for manufacturing silicone release polyester film> The present invention provides a method for producing a silicone release polyester film. A water dispersion (1) of silicone (A) having a number average molecular weight of 25,000 or more and containing 3 or more alkenyl groups in one molecule, A water dispersion (2) of silicone (B) having a number average molecular weight of 25,000 or less and having alkenyl groups only at both ends of the molecule, A water dispersion (3) of silicone (C) having a number average molecular weight of 10,000 or less, and having hydrogen atoms directly bonded to Si atoms represented by Si-H groups, and platinum catalyst, The process includes forming a coating layer using a release coating composition containing the following: When the total solid content of silicone (A), silicone (B), and silicone (C) is 100 parts by mass, silicone (A) is contained in an amount of 80 parts by mass or more, silicone (B) in an amount of 2 parts by mass or more and 20 parts by mass or less, and silicone (C) in an amount of 2 parts by mass or more and 20 parts by mass or less.

[0110] The method for producing a silicone release polyester film according to the present invention makes it possible to efficiently and simply obtain a silicone release polyester film having the above-mentioned properties. The manufacturing method shown herein is merely an example, and the present invention is not limited thereto.

[0111] In the above manufacturing method, the descriptions relating to the silicone release polyester film, etc., in this specification may be applied mutatis mutandis as appropriate to each component.

[0112] In the above manufacturing method, any known method can be used as the step of forming a coating layer using an aqueous dispersion release coating composition, as long as it is a method of forming a coating layer on a film using an aqueous dispersion release coating composition. [Examples]

[0113] The present invention will be specifically described by examples, but the present invention is not limited to the following examples. The physical properties and characteristics in the examples were measured or evaluated by the methods described below. Furthermore, the notation "parts" refers to "parts by mass."

[0114] The measurements and evaluations in the examples were carried out as follows.

[0115] Ceramic sheet release properties 100 parts by mass of barium titanate (BaTiO3), 7 parts by mass of polyvinyl butyral, and 3 parts by mass of dioctyl phthalate were added to a mixed solvent of toluene and ethanol in a 1:1 volume ratio, and dispersed using a ball mill to prepare a slurry.

[0116] The obtained slurry was uniformly coated onto a release polyester film coating layer to a thickness of 2 μm after drying, and then dried to form a ceramic sheet. The release polyester film with the ceramic sheet formed on it was cut to 25 mm x 150 mm, and adhesive tape (manufactured by Nitto Denko Corporation, product name "31B Tape") was attached to the ceramic sheet side to prepare a test specimen.

[0117] The obtained test specimens were conditioned for 24 hours at 23°C and 50% humidity. Then, the ceramic sheet (31B tape side) was peeled off using a tensile testing machine at a peel angle of 90° and a peel speed of 10 m / min, and the peel strength was measured. The peel strength of the ceramic sheet was evaluated based on the following indicators. ○: Peel strength less than 0.60 N / mm ×: Peel strength of 0.60 N / mm or higher

[0118] [Examples 1-2, Comparative Examples 1-5] Molten polyethylene terephthalate ([η]=0.64 dl / g, Tg=78℃) containing 0.1% by mass of calcium carbonate particles with an average particle size of 0.7 μm was extruded from a die and cooled in a cooling drum by conventional methods to obtain an unstretched film. Then, it was stretched 3.6 times in the longitudinal direction, and an aqueous coating solution (aqueous dispersion with a solid content of 3% by mass), prepared by mixing each component to achieve the solid content ratio shown in Table 1, was uniformly applied to the surface of the film using a roll coater.

[0119] Next, this coated film was dried at 115°C for approximately 5 seconds, stretched 4.5 times laterally at 145°C, and then heat-set at 230°C for approximately 5 seconds to obtain a 25 μm biaxially oriented polyester film having the coated layer shown in Table 1.

[0120] (Aqueous dispersion of alkenyl group-containing silicone (1) (A)) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 98% by mass of an alkenyl group-containing silicone (number average molecular weight: 28,000) represented by the following formula (1-1) and 2% by mass of polyoxyethylene lauryl ether (product name "Emulgen 109P" manufactured by Kao Corporation) as a surfactant was mechanically emulsified in an aqueous medium to obtain an alkenyl group-containing silicone aqueous dispersion with a solid content of 20% by mass. Furthermore, the emulsion particle size was adjusted by adjusting the stirring speed and stirring time during emulsification.

[0121] [ka] (In equation (1-1), m is 2.5 and n is 400.)

[0122] (Aqueous dispersion of alkenyl group-containing silicone (B) (2)) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 98% by mass of an alkenyl group-containing silicone (number average molecular weight: 14000) represented by the following formula (1-2) and 2% by mass of polyoxyethylene lauryl ether (product name "Emulgen 109P" manufactured by Kao Corporation) as a surfactant was mechanically emulsified in an aqueous medium to obtain an alkenyl group-containing silicone aqueous dispersion with a solid content of 20% by mass. Furthermore, the emulsion particle size was adjusted by adjusting the stirring speed and stirring time during emulsification.

[0123] [ka] (In equation (1-2), n is 200.)

[0124] (Aqueous dispersion of silicone (C) having Si-H groups (3)) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 98% by mass of hydrogen-containing silicone (number average molecular weight: 5000) represented by the following formula (2) and 2% by mass of polyoxyethylene lauryl ether (manufactured by Kao Corporation, product name "Emulgen 109P") as a surfactant was mechanically emulsified in an aqueous medium to obtain a Si-H group-containing silicone aqueous dispersion with a solid content of 10% by mass. Furthermore, the emulsion particle size was adjusted by adjusting the stirring speed and stirring time during emulsification.

[0125] [ka] (In equation (2), o is 30 and p is 35.)

[0126] (Platinum catalyst) • A platinum-based catalyst containing a reaction inhibitor was prepared using an isopropyl alcohol solution of chloroplatinic acid (in this composition, the amount of platinum metal is 500 ppm by mass), 99.75% by mass of polyoxyethylene lauryl ether (manufactured by Kao Corporation, trade name "Emulgen 109P") as a surfactant, 0.2% by mass of a crosslinking reaction inhibitor (1-ethynylcyclohexanol), and pure water to create an aqueous dispersion with a solid content of 10% by mass. Because the crosslinking reaction inhibitor is preferentially coordinated in this platinum-based catalyst, the catalytic effect can be delayed until the reaction inhibitor volatilizes.

[0127] (Adjustment of silicone coating solution) As a release coating composition, a composition consisting of an alkenyl group-containing silicone aqueous dispersion / Si-H group-containing silicone aqueous dispersion / platinum-based catalyst was used according to the formulation shown in Table 1. The composition was diluted with water to a solid content concentration of 10% so that the coating solution would have a layer thickness of 50 nm.

[0128] The above formulation and results are shown in Table 1. Note that the values ​​for each silicone represent the parts by mass of solids.

[0129] [Table 1]

[0130] As can be seen from Table 1, the films of the embodiments of the present invention exhibited excellent peelability even on very thin ceramic sheets of 2 μm. This is presumed to be because films with excellent peelability were obtained by using specific compositions containing predetermined crosslinkable high molecular weight silicone, low molecular weight silicone, and Si-H group-containing silicone. On the other hand, in Comparative Examples 1 to 7, insufficient crosslinking resulted in uncured films, or appropriate easy peelability could not be obtained.

Claims

1. Silicone (A) having a number average molecular weight of 25,000 or more and 45,000 or less, and containing 3 to 30 alkenyl groups in one molecule. Silicone (B) having a number average molecular weight of 10,000 or more and 25,000 or less, and having alkenyl groups only at both ends of a single molecule. A silicone (C) having a number average molecular weight of 2000 or more and 10000 or less, and having hydrogen atoms directly bonded to Si atoms represented by Si-H groups, and platinum catalyst, A silicone release polyester film having a coating layer formed by drying after being applied with a release coating composition containing the following: When the total solid content of the silicone (A), silicone (B), and silicone (C) is 100 parts by mass, the silicone (A) is contained in an amount of 80 parts by mass or more and 96 parts by mass or less, the silicone (B) in an amount of 2 parts by mass or more and 20 parts by mass or less, and the silicone (C) in an amount of 2 parts by mass or more and 20 parts by mass or less. The thickness of the coating layer is 5 nm to 70 nm after drying. The amount of the platinum-based catalyst is such that the mass of the platinum element is 120 ppm or more and 800 ppm or less relative to the total mass of the silicone (A), the silicone (B), and the silicone (C). Silicone release polyester film.

2. The silicone release polyester film according to claim 1, wherein the Si-H group-containing silicone (C) has 5 to 30 hydrogen atoms bonded to Si atoms in one silicone molecule.

3. The silicone release polyester film according to claim 1 or 2, wherein the silicone (A) has alkenyl groups at both ends and in the side chains in one molecule.

4. The silicone release polyester film according to claim 1 or 2, wherein the alkenyl group of the silicone (A) is a vinyl group.

5. The silicone release polyester film according to claim 1 or 2, wherein the alkenyl group of the silicone (B) is a vinyl group.

6. The silicone release polyester film according to claim 1 or 2, wherein the alkenyl groups of the silicone (A) and the silicone (B) are vinyl groups.

7. A silicone release polyester film according to claim 1 or 2, used for molding ceramic green sheets in the manufacture of multilayer ceramic capacitors.

8. A method for manufacturing a silicone release polyester film, Silicone (A) having a number average molecular weight of 25,000 or more and 45,000 or less, and containing 3 to 30 alkenyl groups in one molecule. Silicone (B) having a number average molecular weight of 10,000 or more and 25,000 or less, and having alkenyl groups only at both ends of a single molecule. A silicone (C) having a number average molecular weight of 2000 or more and 10000 or less, and having hydrogen atoms directly bonded to Si atoms represented by Si-H groups, and platinum catalyst, The process includes applying a release coating composition containing the above, followed by a step of forming a coated layer by drying, When the total solid content of silicone (A), silicone (B), and silicone (C) is 100 parts by mass, silicone (A) is contained in an amount of 80 parts by mass or more and 96 parts by mass or less, silicone (B) in an amount of 2 parts by mass or more and 20 parts by mass or less, and silicone (C) in an amount of 2 parts by mass or more and 20 parts by mass or less. The thickness of the coating layer is 5 nm to 70 nm after drying. The amount of the platinum-based catalyst is such that the mass of the platinum element is 120 ppm or more and 800 ppm or less relative to the total mass of the silicone (A), the silicone (B), and the silicone (C). A method for manufacturing a silicone release polyester film.

9. The manufacturing method according to claim 8, wherein the silicone (A) has alkenyl groups at both ends and in the side chains in one molecule.

10. The manufacturing method according to claim 8 or 9, wherein the alkenyl groups of the silicone (A) and the silicone (B) are vinyl groups.

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