Silicone release polyester film and method of making same

Abstract

Provided are: a silicone mold-release polyester film which can be suitably used as a carrier film or the like during the production of a laminated ceramic capacitor, can be peeled off even if the film is very thin, and has excellent light peeling properties, which is suitable for example, and which does not cause breakage such as breakage; a method for producing the silicone mold-release polyester film; a silicone mold release polyester film having a coating layer formed using a mold release coating composition containing: an aqueous dispersion (1) of a silicone (A) having a number average molecular weight of 25000 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 25000 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 that is represented by an Si-H group and that is directly bonded to an Si atom; and a platinum-based catalyst, and when the total solid content of the silicone (A), the silicone (B), and the silicone (C) is taken as 100 parts by mass, the composition contains 80 parts by mass or more of the silicone (A), 2-20 parts by mass (inclusive) of the silicone (B), and 2-20 parts by mass (inclusive) of the silicone (C).

Description

Technical Field

[0001] The present invention relates to a silicone release polyester film, and more particularly to a silicone release polyester film having peelability and adhesion suitable for molding from light peeling to heavy peeling, which can prevent the occurrence of cracks and deformation of the ceramic green sheet used in the manufacture of a laminated ceramic capacitor, and a method for manufacturing the same. Background Art

[0002] In the manufacture of multilayer ceramic capacitors, release films are used as carrier films for molding ceramic green sheets. In particular, polyester films are used as the base material of the release films in terms of dimensional stability and heat resistance. In recent years, the miniaturization and high capacity of multilayer ceramic capacitors have been promoted, while on the other hand, the need for high reliability for automotive use has gradually increased the demand for improved quality of ceramic green sheets.

[0003] As ceramic green sheets become thinner and more reliable, the thickness of the dried sheets is in the region of several μm or less. Therefore, carrier films are particularly required to have easy peeling properties. Thinning reduces the rigidity of ceramic green sheets, and when the green sheets are peeled off by the peeling force of existing release films, cracks and deformations may occur, and the defective rate of small sheets may increase. Therefore, easy peeling properties are required.

[0004] Therefore, it is required to reduce the peeling force of the release film, and for example, a method of adjusting the peeling force by controlling the crosslinking structure of silicone has been proposed (for example, Patent Document 1). However, in such a method of controlling the crosslinking structure of the release layer, a polymer with a special structure or a new design of a crosslinking agent is required, or stronger energy is required during ultraviolet irradiation, electron beam irradiation, etc., and therefore, there is a problem of increased cost.

[0005] In addition, a release layer formed 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, in this method, the solvent of the coating agent used to form the release layer is an organic solvent, so the organic solvent processing equipment during coating and drying becomes huge, and the running cost of processing the volatilized organic solvent is also consumed, resulting in a problem of high cost.

[0006] Furthermore, there are problems in the working environment, safety issues such as fires caused by organic solvents, etc. In addition, a method without using an organic solvent has been proposed (e.g., Patent Document 3), but in this method, the viscosity of the coating increases, which makes the operation complicated and makes it difficult to apply uniformly.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2006-7689

[0010] Patent Document 2: Japanese Patent Application Publication No. 2008-254207

[0011] Patent Document 3: Japanese Patent Application Publication No. 2003-192987 Summary of the invention

[0012] Problem that the invention aims to solve

[0013] In view of the above situation, the present invention aims to provide: a silicone release polyester film with excellent light peelability, which can be used as a carrier film in the manufacture of laminated ceramic capacitors, and can be peeled off even a very thin film without damage such as cracks, and a method for manufacturing the same.

[0014] Solutions for solving problems

[0015] The present inventors have conducted intensive studies to solve the above problems and have found that the above problems can be solved by maximizing the crosslinking density during the formation of the release layer using a certain type of polydimethyl silicone, thereby completing the present invention.

[0016] That is, the present invention provides the following silicone release polyester film (silicone release polyester film). [1]

[0018] A silicone release polyester film having a coating layer formed using a release coating composition,

[0019] The demoulding coating composition comprises:

[0020] An aqueous dispersion (1) of an organosilicon (A) having a number average molecular weight of 25,000 or more and containing three or more alkenyl groups in one molecule;

[0021] A water dispersion (2) of an organosilicon (B) having a number average molecular weight of 25,000 or less and having alkenyl groups only at both ends in one molecule;

[0022] an aqueous dispersion (3) of an organosilicon (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

[0023] Platinum catalysts,

[0024] When the total solid content of the above-mentioned silicone (A), the above-mentioned silicone (B) and the above-mentioned silicone (C) is set to 100 parts by mass, it contains: 80 parts by mass or more of the above-mentioned silicone (A), 2 parts by mass or more and 20 parts by mass or less of the above-mentioned silicone (B), and 2 parts by mass or more and 20 parts by mass or less of the above-mentioned silicone (C). [2]

[0026] The silicone release polyester film according to [1], wherein the silicone (A) has alkenyl groups at both terminals and in a side chain in one molecule. [3]

[0028] The silicone release polyester film according to [1] or [2], wherein the alkenyl group of the silicone (A) is a vinyl group. [4]

[0030] The silicone release polyester film according to any one of [1] to [3], wherein the alkenyl group of the silicone (B) is a vinyl group. [5]

[0032] The silicone release polyester film according to any one of [1] to [4], wherein the alkenyl groups of the silicone (A) and the silicone (B) are vinyl groups. [6]

[0034] The silicone release polyester film according to any one of [1] to [5], wherein the content of the platinum-based catalyst is 120 ppm or more based on the total amount of the silicone (A) and the silicone (B). [7]

[0036] The silicone release polyester film according to any one of [1] to [6], which is used for molding ceramic green sheets in the production of laminated ceramic capacitors.

[0037] Furthermore, the present invention provides the following method for producing a silicone release polyester film. [8]

[0039] A method for producing a silicone release polyester film, comprising the steps of: forming a coating layer using a release coating composition,

[0040] The demoulding coating composition comprises:

[0041] An aqueous dispersion (1) of an organosilicon (A) having a number average molecular weight of 25,000 or more and containing three or more alkenyl groups in one molecule;

[0042] A water dispersion (2) of an organosilicon (B) having a number average molecular weight of 25,000 or less and having alkenyl groups only at both ends in one molecule;

[0043] an aqueous dispersion (3) of an organosilicon (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

[0044] Platinum catalysts,

[0045] When the total solid content of the above-mentioned silicone (A), the above-mentioned silicone (B) and the above-mentioned silicone (C) is set to 100 parts by mass, the silicone (A) contains 80 parts by mass or more, the silicone (B) contains 2 parts by mass or more and 20 parts by mass or less, and the silicone (C) contains 2 parts by mass or more and 20 parts by mass or less. [9]

[0047] The production method according to [8], wherein the organosilicon (A) has alkenyl groups at both terminals and in a side chain in one molecule.

[10]

[0049] The production method according to [8] or [9], wherein the alkenyl group of the organosilicon (A) and the organosilicon (B) is a vinyl group.

[0050] Effects of the Invention

[0051] The silicone release polyester film of the present invention has the above-mentioned structure, and thus can provide a release polyester film for sheet molding, which can be peeled off without damage such as cracks even when it is a very thin film, has a moderately low peel strength, and has excellent uniformity of the release layer. The release polyester film of the present invention having such characteristics can be used as a carrier film suitable for molding into a ceramic green sheet used in a ceramic laminate capacitor, for example.

[0052] Furthermore, the method for producing the silicone release polyester film of the present invention can efficiently and simply produce the silicone release polyester film having the above-mentioned properties. DETAILED DESCRIPTION

[0053] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0054] <Silicone release polyester film>

[0055] The silicone release polyester film of the present invention has a coating layer formed using a release coating composition, wherein the release coating composition comprises:

[0056] A water dispersion (1) of an organosilicon (A) having a number average molecular weight of 25,000 or more and containing three or more alkenyl groups in one molecule;

[0057] A water dispersion (2) of an organosilicon (B) having a number average molecular weight of 25,000 or less and having alkenyl groups only at both ends in one molecule;

[0058] an aqueous dispersion (3) of an organosilicon (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

[0059] Platinum catalysts,

[0060] When the total solid content of the above-mentioned silicone (A), the above-mentioned silicone (B) and the above-mentioned silicone (C) is set to 100 parts by mass, the above-mentioned silicone (A) contains 80 parts by mass or more, the above-mentioned silicone (B) contains 2 parts by mass or more and 20 parts by mass or less, and the above-mentioned silicone (C) contains 2 parts by mass or more and 20 parts by mass or less.

[0061] 〔Polyester film〕

[0062] For the polyester film of the present invention, known polyesters can be suitably used, and for example, the following polyesters can be suitably used.

[0063] (Polyester)

[0064] The polyester constituting the polyester film used as the substrate film in the present invention (hereinafter sometimes referred to as "substrate") is not particularly limited, and a film formed by molding a polyester commonly used as a substrate for a release film can be used. Preferably, it is a crystalline linear saturated polyester formed by an aromatic dibasic acid component and a diol component, for example, further suitable are polyethylene terephthalate, polyethylene isophthalate, polyethylene 2,6-naphthalate, polybutylene terephthalate, poly(1,4-cyclohexylene dimethylene terephthalate), polytrimethylene terephthalate or a copolymer with the constituent components of these resins as the main components. Among them, a polyester film formed by polyethylene terephthalate is particularly suitable. In polyethylene terephthalate, the repeating unit of ethylene terephthalate is preferably 90 mol% or more, more preferably 95 mol% or more, and a small amount of other dicarboxylic acid components and diol components may also be copolymerized. For example, from the aspect of cost, it is preferred to produce only from terephthalic acid and ethylene glycol.

[0065] Furthermore, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, crystallizing agents, etc. may be added within the range not impairing the effects of the release film of the present invention. The polyester film is preferably a biaxially oriented polyester film because of its high elastic modulus in both directions.

[0066] The intrinsic viscosity of the polyester film is preferably 0.50 dl / g or more and 0.70 dl / g or less, 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, a large amount of breakage does not occur during the stretching process, which is preferred. On the contrary, when it is 0.70 dl / g or less, the cutting property when cutting into a predetermined product width is good, and no dimensional defects occur, which is preferred. In addition, the raw material pellets are preferably fully vacuum dried.

[0067] In addition, in this specification, when abbreviated as "polyester film", it means the polyester film which has (laminated) the surface layer A and the surface layer B.

[0068] The method for producing the polyester film of the present invention is not particularly limited, and a conventionally commonly used method can be used. For example, the polyester is melted in an extruder, extruded into a film, cooled on a rotating cooling drum, thereby obtaining an unstretched film, and the unstretched film is biaxially stretched to obtain the film. The biaxially stretched film can be obtained by a method in which a uniaxially stretched film in the longitudinal or transverse direction is biaxially stretched in sequence in the transverse direction or longitudinal direction, or by a method in which an unstretched film is biaxially stretched in the longitudinal and transverse directions simultaneously.

[0069] In the present invention, the stretching temperature during stretching of the polyester film is preferably set to be equal to or higher than the secondary transition point (Tg) of the polyester. The film is preferably stretched by 1 to 8 times, particularly 2 to 6 times, in each of the longitudinal and transverse directions.

[0070] The thickness of the polyester film is preferably 12 μm or more and 100 μm or less, more preferably 16 μm or more and 50 μm or less, and more preferably 19 μm or more and 33 μm or less. If the thickness of the film is 12 μm or more, there is no worry of deformation due to heat during film production, processing, and molding, and it is preferred. On the other hand, if the thickness of the film is 100 μm or less, the amount of film discarded after use does not increase extremely, which is preferred in reducing environmental load.

[0071] The polyester film substrate 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 substantially free of particles having a particle size of 1.0 μm or more and a surface layer B containing particles. Preferably, the surface layer A substantially does not contain inorganic particles having a particle size of 1.0 μm or more.

[0072] In this embodiment, particles having a particle size of 1 nm or more and less than 1.0 μm may be present in the surface layer A. Since the surface layer A does not substantially contain particles having a particle size of 1.0 μm or more, such as inorganic particles, the particle shape in the substrate can be transferred to the resin sheet to reduce the occurrence of defects.

[0073] In one embodiment, the surface layer A does not contain particles having a particle diameter of less than 1.0 μm, and thus can more effectively suppress the transfer of particle shapes in the substrate to the resin sheet to cause problems.

[0074] In one embodiment, the polyester film substrate is preferably a laminated film having a surface layer A substantially free of inorganic particles on at least one surface. This can more effectively prevent the particle shape in the substrate from being transferred to the resin sheet and causing problems.

[0075] For example, it is preferable that the surface layer A substantially does not contain particles having a particle size of less than 1.0 μm and substantially does not contain particles having a particle size of 1.0 μm or more.

[0076] Here, in the present invention, "substantially free of particles" means, for example, in the case of inorganic particles smaller than 1.0 μm, when the inorganic elements are quantitatively analyzed by fluorescent X-ray analysis, the content is 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit. This is because even if particles are not actively added to the film, there are cases where contamination components from foreign matter, dirt attached to production lines and devices in the raw resin or film manufacturing process are peeled off and mixed into the film. In addition, "substantially free of particles with a particle size of 1.0 μm or more" means that particles with a particle size of 1.0 μm or more are not actively included.

[0077] In the case of a laminated polyester film having a multilayer structure of two or more layers, it is preferred that a surface layer B which may contain inorganic particles and the like is provided on the opposite side of a surface layer A which does not substantially contain inorganic particles.

[0078] As a laminated structure, when the layer on one side of the release layer is set as the A layer, the layer on the opposite side is set as the B layer, and the core layer other than these is set as the C layer, the layer structure in the thickness direction can cite a laminated structure such as release layer / A / B or release layer / A / C / B. Of course, the C layer can be a multilayer structure. In addition, the surface layer B may not contain inorganic particles. In this case, in order to impart the slippage for winding the film into a roll, it is preferred that a coating layer containing at least inorganic particles and a binder is provided on the surface layer B.

[0079] In the polyester film substrate of the present invention, from the viewpoint of the slipperiness of the film and the ease of air removal, the surface layer B on the opposite side of the surface to which the release layer is applied preferably contains inorganic particles, and silica particles and / or calcium carbonate particles are particularly preferably used. The content of the inorganic particles contained in the surface layer B is preferably 5000 ppm or more and 15000 ppm or less based on the total amount of the inorganic particles.

[0080] At this time, the regional surface average roughness (Sa) of the film of surface layer B is preferably in the range of more than 1nm and less than 40nm. More preferably, the range is more than 5nm and less than 35nm. When the total amount of silicon dioxide particles and / or calcium carbonate particles is more than 5000ppm and Sa is more than 1nm, when the film is rolled into a roll, air can be released evenly, and the winding form is good and the planarity is good, thus, it becomes suitable for manufacturing ultra-thin layer ceramic green sheets. In addition, when the total amount of silicon dioxide particles and / or calcium carbonate particles is less than 15000ppm and Sa is less than 40nm, it is not easy to produce the aggregation of lubricants, and no coarse protrusions are produced, so the quality of ultra-thin layer ceramic green sheets is stable and preferred during manufacturing.

[0081] As the particles contained in the above-mentioned B layer, inactive inorganic particles and / or heat-resistant organic particles can also be used in addition to silicon dioxide and / or calcium carbonate, but from the viewpoint of transparency and cost, silicon dioxide particles and / or calcium carbonate particles are more preferably used. In addition, as inorganic particles that can be used in addition, aluminum oxide-silicon dioxide composite oxide particles, hydroxyapatite particles, etc. can be cited. In addition, as heat-resistant organic particles, cross-linked polyacrylic acid particles, cross-linked polystyrene particles, benzoguanamine particles, etc. can be cited. In addition, when using silicon dioxide particles, porous colloidal silica is preferred, and when using calcium carbonate particles, from the viewpoint of preventing the lubricant from falling off, it is preferred that light calcium carbonate surface-treated with a high molecular compound of a polyacrylic acid system is used.

[0082] 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. If the average particle size of the inorganic particles is 0.1 μm or more, the slip property of the release film is good and thus it is preferred. In addition, if the average particle size is 2.0 μm or less, there is no concern about adversely affecting the smoothness of the release layer surface, and therefore, there is no concern about the generation of pinholes in the ceramic green sheet and thus it is preferred.

[0083] In addition, in order to improve the adhesion of a release layer to be applied later, or to prevent static electricity, a coating layer may be provided on the surface of the surface layer A and / or the surface layer B before stretching or after uniaxial stretching in the film-making process, or a corona treatment may be performed.

[0084] In the present invention, the ceramic sheet releasability of the above-mentioned silicone release polyester film can be measured, for example, as follows. The prepared slurry is evenly applied to the coating layer of the release polyester film in a manner such that the thickness after drying becomes 2 μm, and then dried to form a ceramic sheet. Next, the release polyester film formed with the ceramic sheet is cut into a size of 25 mm×150 mm, and the adhesive tape is attached to the ceramic sheet side to prepare a test piece.

[0085] The obtained test piece is subjected to humidity conditioning for 24 hours at 23°C and 50% humidity, and then the ceramic sheet (adhesive tape side) is peeled off at a peeling angle of 90° and a peeling speed of 10 m / min using a tensile tester to measure the peel strength. For the peel strength of the ceramic sheet, for example, under the conditions of the embodiment, the peel strength of less than 0.60 N / mm can be evaluated as preferred, and the peel strength of less than 0.55 can be evaluated as more preferred.

[0086] [Mold release coating composition]

[0087] The mold release coating composition of the present invention comprises:

[0088] An aqueous dispersion (1) of an organosilicon (A) having a number average molecular weight of 25,000 or more and containing three or more alkenyl groups in one molecule;

[0089] A water dispersion (2) of an organosilicon (B) having a number average molecular weight of 25,000 or less and having alkenyl groups only at both ends in one molecule;

[0090] an aqueous dispersion (3) of an organosilicon (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

[0091] Platinum catalysts.

[0092] The alkenyl group-containing organosilicon component in the present invention is composed of at least two components having different molecular weights.

[0093] (containing olefinic silicone (A))

[0094] In the present invention, 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.

[0095] The alkenyl group-containing silicone (A) preferably has alkenyl groups at both terminals and in a side chain in one molecule.

[0096] In addition, the alkenyl group of the alkenyl group-containing organosilicon (A) contains at least 3 alkenyl groups in one molecule, but may be 4 or more, 5 or more, 6 or more, etc. In addition, the upper limit of the number of alkenyl groups in the alkenyl group-containing organosilicon (A) may be set as long as the effect of the present invention is exerted, and may be, for example, 30 or less, 20 or less, 15 or less, 10 or less, etc. When the alkenyl group of the alkenyl group-containing organosilicon (A) is 2 or less in one molecule, the crosslinking reactivity is reduced, and the peeling of the ceramic sheet becomes more serious.

[0097] Examples of the alkenyl group-containing organosilicon (A) include organopolysiloxanes having a structure represented by the following general formula (I).

[0098] R 1 a R 2 b SiO (4-a-b) / 2 ···(I)

[0099] (In formula (I), R 1 is an alkenyl group having 2 to 8 carbon atoms, R 2 It is a monovalent saturated hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl group or an aryl group, and a is 0 to 3, b is 0 to 2, and represents an integer satisfying a+b≤3.

[0100] The alkenyl group-containing organosilicon (A) may have a linear structure or a branched structure, may partially have a cross-coupling, or may be a mixture thereof.

[0101] As R 1 Examples of the alkenyl group having 2 to 8 carbon atoms include vinyl, allyl, butenyl, pentenyl, hexenyl and the like. Among these, vinyl is particularly preferred.

[0102] In addition, as R 2 Examples of the alkyl group include methyl, ethyl, propyl, and butyl groups, and examples of the aryl group include phenyl and tolyl groups. 2 80 mol % or more of the substituents are methyl groups.

[0103] In addition, when the proportion of silicon atoms having alkenyl groups is, for example, in the range of 0.05 to 20 mol% relative to all silicon atoms in the alkenyl-containing organosilicon (A), it is preferred from the perspective of the curing speed and pot life of the composition. When the proportion of silicon atoms having alkenyl groups does not reach the lower limit, the curing speed of the composition decreases, and it sometimes becomes difficult to efficiently form a cured organosilicon film during film formation. In addition, when the proportion of silicon atoms having alkenyl groups exceeds the upper limit, the pot life of the composition sometimes becomes shorter.

[0104] Examples of the alkenyl group-containing silicone (A) include silicone represented by the following formula (1-1).

[0105]

[0106] (In formula (1-1), m is 2.5 and n is 400.)

[0107] The alkenyl group-containing silicone (A) can be produced by a known method. In addition, the alkenyl group-containing silicone in the present invention is preferably contained in the composition in the form of an aqueous dispersion (aqueous dispersion (1)).

[0108] When the alkenyl group-containing organosilicon (A) is formed into an aqueous dispersion (aqueous dispersion (1)), the content of the alkenyl group-containing organosilicon (A) in 100 parts by mass of the aqueous dispersion (1) may 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. When the content is 10 parts by mass or less, the long-term stability of the emulsion may be deteriorated, and when it is 80 parts by mass or more, the viscosity becomes high and the dispersibility may be deteriorated.

[0109] The number average molecular weight of the alkenyl group-containing organosilicon (A) is 25,000 or more, 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 alkenyl group-containing organosilicon (A) may be 45,000 or less, 40,000 or less, etc. as long as the effect of the present invention is exerted. In addition, if the number average molecular weight is 50,000 or more, the emulsion of the aqueous dispersion may become unstable.

[0110] The content of the alkenyl-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-containing silicone (A), silicone (B) and Si-H-containing silicone (C) is set to 100 parts by mass. For example, it can 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 more, 90 parts by mass or more and 92 parts by mass or less. If the above content is 96 parts by mass or more, the polymer silicone increases and the crosslinking density decreases. In addition, if the above content is 80 parts by mass or less, the crosslinking sites between the polymer silicone and the low molecular silicone decrease and the crosslinking density decreases.

[0111] (containing olefinic silicone (B))

[0112] Silicone (B) having a number average molecular weight of 25,000 or less and having alkenyl groups only at both ends in one molecule (hereinafter sometimes referred to as "silicone (B)" or "alkenyl group-containing silicone (B)") is used.

[0113] The alkenyl group-containing organosilicon (B) has alkenyl groups only at both ends in one molecule. It is presumed that the low molecular weight alkenyl group-containing organosilicon (B) can undergo a crosslinking reaction to supplement the crosslinking network of the high molecular weight alkenyl group-containing organosilicon (A), maximizing the crosslinking density as much as possible, and making it possible to easily peel off the ceramic sheet, but the scope of protection is not limited to the above mechanism.

[0114] Examples of the alkenyl group-containing organosilicon (B) include organopolysiloxanes having a structure represented by the following general formula (I′).

[0115] R 1’ a’ R 2’ b’ SiO (4-a’-b’) / 2 ···(I')

[0116] (In formula (I'), R 1’ is an alkenyl group having 2 to 8 carbon atoms, R 2’ It is a monovalent saturated hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl group or an aryl group, and a' is 0 to 1, b' is 0 to 2, and an integer satisfying a'+b'≤3.

[0117] The alkenyl group-containing organosilicon (B) may have a linear structure or a branched structure, may partially have a cross-coupling, or may be a mixture thereof.

[0118] As R 1’ Examples of the alkenyl group having 2 to 8 carbon atoms include vinyl, allyl, butenyl, pentenyl, and hexenyl. Among these, vinyl is particularly preferred. The alkenyl-containing organosilicon (B) has alkenyl groups only at both ends in one molecule.

[0119] In addition, as R 2’ Examples of the alkyl group include methyl, ethyl, propyl, and butyl groups, and examples of the aryl group include phenyl and tolyl groups. 2’ 80 mol % or more of the substituents are methyl groups.

[0120] In addition, it is preferred that the content of silicon atoms having alkenyl groups is, for example, 0.05 to 20 mol % relative to all silicon atoms in the alkenyl group-containing organosilicon (B) in terms of the curing rate and pot life of the composition.

[0121] Examples of the alkenyl group-containing silicone (B) include silicone represented by the following formula (1-2).

[0122]

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

[0124] The alkenyl group-containing silicone (B) can be produced by a known method. In addition, the alkenyl group-containing silicone in the present invention is preferably contained in the composition in the form of a water dispersion (water dispersion (2)).

[0125] The number average molecular weight of the alkenyl group-containing silicone (B) is 25,000 or less, for example, 24,000 or less, 23,000 or less, 22,000 or less, 21,000 or less, 20,000 or less, 19,000 or less, 18,000 or less, 17,000 or less, etc. The lower limit of the number average molecular weight of the alkenyl group-containing silicone (B) may be any value as long as the effect of the present invention is exerted, for example, it may be 10,000 or more, 11,000 or more, 12,000 or more, etc. When the molecular weight is 25,000 or more, it is substantially the same as silicone A, and therefore the crosslinking density is not improved. On the other hand, when the molecular weight is too small, it becomes difficult to form a crosslinking network between silicones A.

[0126] The alkenyl group-containing organosilicon (B) can be produced by a known method. The alkenyl group-containing organosilicon (B) is preferably contained in the composition in the form of an aqueous dispersion (aqueous dispersion (2)).

[0127] When the alkenyl group-containing organosilicon (B) is formed into an aqueous dispersion (aqueous dispersion (2)), the content of the alkenyl group-containing organosilicon (B) in 100 parts by mass of the aqueous dispersion (2) may 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. When the content is 10 parts by mass or less, the long-term stability of the emulsion may be deteriorated, and when it is 80 parts by mass or more, the viscosity becomes high and the dispersibility may be deteriorated.

[0128] The content of the alkenyl-containing silicone (B) is preferably 2 parts by mass or more and 20 parts by mass or less, and may be, for example, 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., when the total solid content of the alkenyl-containing silicone (A), the silicone (B) and the Si-H group-containing silicone (C) is set to 100 parts by mass.

[0129] (Containing Si-H-based silicone (C))

[0130] As the organosilicon (C) having a hydrogen atom directly bonded to a Si atom represented by a Si—H group (hereinafter sometimes referred to as “organosilicon (C)” or “Si—H group-containing organosilicon (C)”) in the present invention, an organohydrogenpolysiloxane having a structure represented by the following general formula (II) is exemplified.

[0131] R 3 c H d SiO (4-c-d) / 2 ···(II)

[0132] (In formula (II), R 3 It is a monovalent saturated hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl group or an aryl group, and c is 0 to 2, d is 1 to 3, and an integer satisfying c+d≤3.

[0133] The Si—H group-containing organosilicon (C) may have a linear structure or a branched structure.

[0134] As R 3 Examples of the alkyl groups include methyl, ethyl, propyl, and butyl groups, and examples of the aryl groups include phenyl and tolyl groups. 350 mol % or more of the substituents are methyl groups.

[0135] From the viewpoint of curing properties, the Si—H group-containing silicone (C) preferably has at least 3, preferably 5 or more hydrogen atoms bonded to Si atoms in one silicone molecule.

[0136] Examples of the Si-H group-containing organosilicon (C) include organosilicon represented by the following formula (2).

[0137]

[0138] (In formula (2), o is 30 and p is 35)

[0139] The Si-H group-containing silicone (C) can be produced by a known method. In addition, the Si-H group-containing silicone (C) in the present invention is preferably contained in the composition in the form of a water dispersion (water dispersion (3)).

[0140] When the Si-H group-containing organosilicon (C) is formed into an aqueous dispersion (aqueous dispersion (3)), the content of the alkenyl group-containing organosilicon (B) in 100 parts by mass of the aqueous dispersion (3) may 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. When the content is 10 parts by mass or less, the long-term stability of the emulsion may be deteriorated, and when it is 80 parts by mass or more, the viscosity becomes high and the dispersibility may be deteriorated.

[0141] The number average molecular weight of the Si-H group-containing silicone (C) is 10,000 or less, for example, 8,000 or less, 7,000 or less, 6,000 or less, etc. When the number average molecular weight is 10,000 or more, the function as a crosslinking agent becomes insufficient, and the crosslinking density is reduced. In addition, 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 effect of the present invention is exerted, and for example, it can be 300 or more, 500 or more, 1,000 or more, 2,000 or more, etc.

[0142] 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 silicone (A) containing alkenyl groups, the silicone (B) and the Si-H group-containing silicone (C) is 100 parts by mass, and may be, for example, 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 more, 5 parts by mass or more and 10 parts by mass or less, etc. When the content is less than 2 parts by mass, the curing reaction is not easy to proceed, and therefore, sufficient coating hardness may not be obtained. When the content exceeds 20 parts by mass, Si-H is excessively precipitated on the surface and strongly adheres to the raw sheet, and therefore, heavy peeling may be caused as a result.

[0143] (Ratio of Si-H groups to olefin groups)

[0144] The ratio of the number of Si-H groups to the number of alkenyl groups (the number of alkenyl groups in silicone (A) and silicone (B)) in the release coating composition of the present invention (number of Si-H groups / number of alkenyl groups) is preferably in the range of 1.0 to 2.0. If the above ratio does not reach the lower limit, it will remain in the coating layer formed with excessive alkenyl groups, so that the peel strength is likely to change over time. In addition, the crosslinking density is reduced, thereby sometimes reducing the uniformity of the peel force and the residual adhesion rate. In addition, if the above ratio exceeds the upper limit, it will remain in the coating layer formed with highly reactive Si-H groups, sometimes causing an increase in the peel force.

[0145] (Silicone content)

[0146] In the demoulding coating composition of the present invention, the solid content mass of the above composition is used as a reference, and the total amount of alkenyl-containing silicone solid components (the total amount of the solid components of silicone (A) and silicone (B)) and Si-H-containing silicone (C) solid components is preferably 70% by mass or more. In addition, the more preferred content of each silicone solid component is 80% by mass or more and 97% by mass or less. Here, the silicone solid component refers to the amount excluding the aqueous solvent, and the solid content mass of the composition refers to the total amount of the solid components of each additive. If the total amount of the above silicone solid components is less than the lower limit, the area covered by silicone on the surface of the film formed with the coating becomes smaller, the peeling force becomes heavier, and sometimes the peeling force becomes uneven.

[0147] (Water-based solvent)

[0148] As the aqueous solvent for forming each of the silicone aqueous dispersions of the present invention, water is preferably used. By using an aqueous solvent, the silicone release layer can be formed in the release film production process without using explosion-proof equipment and organic solvent recovery equipment required for organic solvents.

[0149] (Emulsifier)

[0150] Each aqueous dispersion is prepared using an emulsifier to improve the stability and shear resistance of the aqueous dispersion. As an emulsifier, a nonionic emulsifier that does not affect the curing reaction of silicone is preferred. Ionic emulsifiers may affect the curing reaction of silicone, and may be locally present in the coating film, such as seeping out on the surface, which may affect the release properties.

[0151] As the nonionic emulsifier, the HLB value is preferably in the range of 8 or more and 18 or less, and for example, at least one selected from alkylene oxide addition types such as alkylene oxide addition products of higher alcohols and higher fatty acids, esters of alkylene oxide addition products of higher fatty acids and alcohols, alkylene oxide addition products of alkanolamides, alkylene oxide addition products of sorbitan esters, and alkylene oxide addition products of higher fatty acid glycerides can be cited. These can be used alone or in combination of two or more. Here, the HLB value is a value calculated according to Griffin's calculation formula.

[0152] As alkylene oxide, for example, ethylene oxide, propylene oxide, and butylene oxide can be mentioned. One of these can also be used in combination. When using multiple types, regardless of block or random addition forms, the HLB value is preferably in the range of 8 or more and 18 or less, and more preferably in the range of 10 or more and 15 or less. Among these nonionic emulsifiers, for example, polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, etc. can be preferably mentioned. If a nonionic emulsifier whose HLB value deviates from the above range is used as an emulsifier for an organic silicone aqueous dispersion, the emulsification dispersion power and the stability of the aqueous dispersion are sometimes reduced. The nonionic emulsifier is preferably used in the range of 0.1% by mass or more and 20% by mass or less relative to the total solid content, more preferably in the range of 0.2% by mass or more and 15% by mass or less, and more preferably in the range of 0.5% by mass or more and 10% by mass or less. If it is lower than this range, there is a tendency to be poor at emulsification, and if it is higher than it, it sometimes causes heavy peeling.

[0153] (catalyst)

[0154] In the mold release coating composition constituting the coating layer of the present invention, a catalyst is preferably used to perform an addition reaction between the organosilicon (A) and / or the organosilicon (B) and the organosilicon (C), and a platinum-based catalyst is particularly preferred.

[0155] (Platinum catalyst)

[0156] As the platinum catalyst, known ones can be used, for example, platinum chloride and chloroplatinic acid. For the above platinum catalyst, in consideration of the dispersibility of the organosilicon, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex (Karstedt catalyst) can be used to disperse the organosilicon at the same time when emulsifying it, thereby ensuring uniform dispersibility. They can be used alone or in combination of two or more.

[0157] For the amount of platinum-based catalyst, the mass of platinum element is preferably included in the range of 120 ppm or more and 800 ppm or less relative to the total mass of the water dispersion (1) of the above-mentioned silicone (A), the water dispersion (2) of the above-mentioned silicone (B), and the water dispersion (3) of the above-mentioned silicone (C). By setting it to the above range, the curing of silicone can be fully carried out. And 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 the platinum element exceeds the upper limit, the addition reaction of the olefin group and the Si-H group is accelerated, and there is a tendency to produce silicone aggregates. From the above viewpoint, the amount of platinum-based catalyst is, for example, less than 600 ppm, less than 500 ppm, less than 300 ppm, less than 250 ppm, etc. In addition, if the mass ratio of the platinum element is lower than the lower limit, the addition reaction does not proceed, and there is a tendency to cause poor curing of silicone. From the above viewpoint, the amount of platinum catalyst is, for example, more than 130 ppm, more than 140 ppm, more than 150 ppm, more than 200 ppm, etc.

[0158] (Cross-linking Reaction Inhibitor)

[0159] In order to suppress the activity of the platinum catalyst at room temperature, it is preferred that a crosslinking reaction inhibitor is contained in the aqueous coating composition. The above-mentioned crosslinking reaction inhibitor is preferably a crosslinking reaction inhibitor with an alkenyl group. As a crosslinking reaction inhibitor with an alkenyl group, as long as there is an alkenyl group, there is no particular limitation, specifically, examples 1-ethynyl-1-cyclohexanol, 4-ethyl-1-octyne-3-ol, 3-methyl-1-dodecyne-3-ol, 3,7,11-trimethyl-1-dodecyne-3-ol, 1,1-diphenyl-2-propyne-3-ol, 3-ethyl-6-ethyl-1-nonyne-3-ol, 3-methyl-1-pentadecane-3-ol, 2,5-dimethyl-3-hexyne-2,5-diol, 3-phenyl-1-butyne-3-ol. As the above-mentioned alkynyl group, for example, ethynyl can be cited as a preferred example. They can be used alone, and in addition, two or more kinds can also be combined and used. In the present invention, an aqueous emulsion coating composition is used, and therefore, the crosslinking reaction inhibitor having an olefin group and a hydroxyl group as exemplified is preferably used in terms of the balance between affinity solubility for water and coordination ability for platinum and boiling point.

[0160] The content of the cross-linking reaction inhibitor is preferably 5 ppm or more and 1000 ppm or less, more preferably 10 ppm or more and 700 ppm or less, and further preferably 20 ppm or more and 500 ppm or less, relative to the mass of the aqueous coating composition used in the formation of the release layer. When the content of the cross-linking reaction inhibitor is above the lower limit, the pot life becomes longer, the addition curing reaction of the organosilicon at room temperature is not easy to proceed, and there is a tendency that it becomes difficult to produce organosilicon aggregates. In addition, if the content of the cross-linking reaction inhibitor is below the upper limit, the organosilicon becomes difficult to migrate to the object material after the object material is peeled off, and the amount of the reaction inhibitor volatilized during the heat treatment is reduced, so it is not easy to cause contamination inside the oven.

[0161] The content of the cross-linking reaction inhibitor relative to the mass of the platinum element is, for example, preferably 6 times or less, more preferably 5 times or less, and particularly preferably 4 times or less, relative to the mass of the platinum element.

[0162] The cross-linking reaction inhibitor having an acetylene group is not particularly limited as long as it has an acetylene group. In the present invention, an aqueous coating composition is used. Therefore, due to the balance between the solubility in water and the coordination ability for platinum and volatility, a cross-linking reaction inhibitor having an acetylene hydroxyl group represented by 1-ethynylcyclohexanol is preferably used.

[0163] (Other ingredients)

[0164] The mold release coating composition of the present invention may further contain, for example, an adhesiveness-imparting agent to a substrate, a colorant, an ultraviolet absorber, particles, an antistatic agent, and the like, within a range not impairing the subject matter of the present invention.

[0165] (Preparation of Silicone Aqueous Dispersion)

[0166] When preparing each of the organosilicon aqueous dispersions of the present invention, a method of emulsifying the above-mentioned organosilicon component, aqueous solvent and emulsifier can be cited. These components can be emulsified by a known method, for example, a method of mechanically emulsifying the pre-prepared organosilicon, emulsifier and other components as required in an aqueous medium using a stirring device such as a homogenizer, a vacuum emulsifier, a super planetary mixer, etc.

[0167] 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, more preferably 100 nm or more and 200 nm or less.

[0168] 〔Coating layer〕

[0169] 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 as follows: the release coating composition is applied to the polyester film and then dried to form a coating layer.

[0170] In the present invention, the coating layer thickness is preferably 5 nm or more and 70 nm or less in terms of thickness after drying. If the coating layer thickness does not reach the lower limit, the demoulding property may become insufficient. If it exceeds the upper limit, the peel strength increases. In addition, the coating liquid must be made into a high concentration or the coating amount must be increased, so there is a tendency to become difficult to coat.

[0171] When applying the demoulding coating composition of the present invention on a polyester film, an aqueous coating liquid comprising the above-mentioned composition is prepared, and the mass of the above-mentioned coating liquid is used as a benchmark, and the solid content concentration of the aqueous coating liquid is preferably below 20% by mass, more preferably above 1% by mass and below 10% by mass. If the solid content concentration in the aqueous coating liquid does not reach the lower limit, the coating property of the polyester film is sometimes insufficient. In addition, if the solid content concentration exceeds the upper limit, the stability of the coating liquid and the appearance of the coating layer are sometimes deteriorated. As an aqueous solvent for adjusting the solid content concentration, water is preferably used.

[0172] The aqueous coating liquid may be applied to the polyester film at any stage, but is preferably applied during the production process of the polyester film, and more preferably applied to the polyester film before the orientation crystallization is completed.

[0173] Here, the polyester film before the crystal orientation is completed includes: unstretched film; uniaxially oriented film oriented in any one of the longitudinal direction (hereinafter, sometimes referred to as the film continuous film forming direction, length direction, MD direction) or transverse direction (hereinafter, sometimes referred to as the direction orthogonal to the longitudinal direction, width direction, TD direction); further oriented by low-ratio stretching in both longitudinal and transverse directions (finally, biaxially stretched film before the orientation crystallization is completed by re-stretching in the longitudinal direction or transverse direction); etc. Among them, it is preferred to apply the aqueous coating liquid of the above-mentioned composition on the unstretched film or the uniaxially stretched film oriented in one direction, and directly perform longitudinal stretching and / or transverse stretching and heat setting, so-called online coating. The coating layer can be dried by the stretching process or heat setting treatment after coating, and a drying process can be further applied as needed. In addition, when the composition is cured with a catalyst to obtain a cured coating, it can be cured by a stretching process or heat setting treatment, but a curing process can be further applied as needed.

[0174] When the aqueous coating liquid is applied to a polyester film, for example, as a pretreatment for improving coating properties, it is preferred to subject the film surface to a physical treatment such as corona surface treatment, flame treatment, or plasma treatment, or to use the above-mentioned emulsifier together with the composition as a wetting agent.

[0175] As the coating method, any known coating method can be applied, for example, roll coating, gravure coating, roll brush coating, spray coating, air knife coating, impregnation, curtain coating, etc. can be used alone or in combination.

[0176] <Method for producing silicone release polyester film>

[0177] The method for producing a silicone release polyester film of the present invention comprises the steps of forming a coating layer using a release coating composition,

[0178] The demoulding coating composition comprises:

[0179] An aqueous dispersion (1) of an organosilicon (A) having a number average molecular weight of 25,000 or more and containing three or more alkenyl groups in one molecule;

[0180] A water dispersion (2) of an organosilicon (B) having a number average molecular weight of 25,000 or less and having alkenyl groups only at both ends in one molecule;

[0181] an aqueous dispersion (3) of an organosilicon (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

[0182] Platinum catalysts,

[0183] When the total solid content of the above-mentioned silicone (A), the above-mentioned silicone (B) and the above-mentioned silicone (C) is 100 parts by mass, the silicone (A) contains 80 parts by mass or more, the silicone (B) contains 2 parts by mass or more and 20 parts by mass or less, and the silicone (C) contains 2 parts by mass or more and 20 parts by mass or less.

[0184] The method for producing the silicone release polyester film of the present invention can efficiently and simply produce a silicone release polyester film having the above-mentioned properties. It should be noted that the production method shown here is an example, and the present invention is not limited thereto.

[0185] In the above-mentioned production method, the description concerning the above-mentioned silicone release polyester film and the like in this specification can be appropriately applied to each structure.

[0186] As the step of forming a coating layer using the aqueous release coating composition in the above production method, any known method can be appropriately used as long as it is a method of forming a coating layer on a film using the aqueous release coating composition.

[0187] Example

[0188] The present invention is specifically described according to the examples, but the present invention is not limited to the following examples. It should be noted that the physical properties and characteristics in the examples are measured or evaluated by the following methods. In addition, when expressing "parts", it means "parts by mass".

[0189] Each measurement / evaluation in the examples was performed as follows.

[0190] Ceramic sheet peeling

[0191] 100 parts by mass of barium titanate (BaTiO 3 ), 7 parts by mass of polyvinyl butyral, and 3 parts by mass of dioctyl phthalate were added to a mixed solvent of toluene:ethanol=1:1 (volume ratio), and dispersed in a ball mill to prepare a slurry.

[0192] The obtained slurry was evenly coated on the coating layer of the release polyester film in a manner to have a thickness of 2 μm after drying, and then dried to form a ceramic sheet. The release polyester film formed with the ceramic sheet was cut into 25 mm × 150 mm pieces, and an adhesive tape (manufactured by Nitto Denko Corporation, trade name "31B tape") was attached to the ceramic sheet side to prepare a test piece.

[0193] The obtained test piece was conditioned at 23°C and 50% humidity for 24 hours, and then the ceramic sheet (31B tape side) was peeled off at a peeling angle of 90° and a peeling speed of 10 m / min using a tensile tester to measure the peel strength. The peel strength of the ceramic sheet was evaluated based on the following indicators.

[0194] ○: Peel strength less than 0.60N / mm

[0195] ×: Peel strength is 0.60 N / mm or more

[0196] [Examples 1 to 2, Comparative Examples 1 to 5]

[0197] A molten polyethylene terephthalate ([η]=0.64dl / g, Tg=78°C) containing 0.1% by mass of calcium carbonate particles with an average particle size of 0.7μm was extruded from a die and cooled on a cooling drum according to a conventional method to form an unstretched film. Subsequently, the film was stretched to 3.6 times in the longitudinal direction and then mixed with the components in a manner to obtain a solid content ratio as shown in Table 1 to prepare an aqueous coating solution (aqueous dispersion with a solid content concentration of 3% by mass). The obtained aqueous coating solution was evenly applied to the surface of the film using a roll coater.

[0198] Next, the coated film was dried at 115°C for about 5 seconds and stretched to 4.5 times in the transverse direction at 145°C, and further heat-set at 230°C for about 5 seconds to obtain a 25 μm biaxially stretched polyester film having a coating layer shown in Table 1.

[0199] (Aqueous dispersion (A) of alkenyl group-containing organosilicon (1))

[0200] A raw material containing 98% by mass of an organosilicon having an alkenyl group represented by the following formula (1-1) (number average molecular weight: 28,000) and 2% by mass of polyoxyethylene lauryl ether (trade name "EMULGEN 109P" manufactured by Kao Corporation) as a surfactant was mechanically emulsified in an aqueous medium using an emulsifying device capable of stirring the entire container (NPLabo Co., Ltd., device name "Super Planetary Mixer") to obtain an alkenyl group-containing organosilicon aqueous dispersion having a solid content of 20% by mass. In addition, the particle size of the emulsion was adjusted by adjusting the stirring speed and stirring time during emulsification.

[0201]

[0202] (In formula (1-1), m is 2.5 and n is 400.)

[0203] (Aqueous dispersion (2) of alkenyl-containing organosilicon (B))

[0204] A raw material containing 98% by mass of an organosilicon having an alkenyl group represented by the following formula (1-2) (number average molecular weight: 14000) and 2% by mass of polyoxyethylene lauryl ether (trade name "EMULGEN 109P" manufactured by Kao Corporation) as a surfactant was mechanically emulsified in an aqueous medium using an emulsifying device capable of stirring the entire container (NPLabo Co., Ltd., device name "Super Planetary Mixer") to obtain an alkenyl group-containing organosilicon aqueous dispersion having a solid content of 20% by mass. In addition, the particle size of the emulsion was adjusted by adjusting the stirring speed and stirring time during emulsification.

[0205]

[0206] (In formula (1-2), n is 200.)

[0207] (Aqueous dispersion (3) of organosilicon (C) having Si—H groups)

[0208] A raw material containing 98% by mass of a silicone having a hydrogen group represented by the following formula (2) (number average molecular weight: 5000) and 2% by mass of polyoxyethylene lauryl ether (Kao Corporation, trade name "EMULGEN 109P") as a surfactant was mechanically emulsified in an aqueous medium using an emulsifying device capable of stirring the entire container (NPLabo Co., Ltd., device name "Super Planetary Mixer") to obtain a Si-H group-containing silicone aqueous dispersion having a solid content of 10% by mass. The particle size of the emulsion was adjusted by adjusting the stirring speed and stirring time during emulsification.

[0209]

[0210] (In formula (2), o is 30 and p is 35)

[0211] (Platinum catalyst)

[0212] · Platinum-based catalyst containing a reaction terminator: An aqueous dispersion having a solid content of 10% by mass is prepared using an isopropanol 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. This platinum-based catalyst is preferentially coordinated to the crosslinking reaction terminator, and therefore the catalytic effect can be delayed until the reaction terminator volatilizes.

[0213] (Silicone coating liquid adjustment)

[0214] As a coating composition for mold release, a composition consisting of an alkenyl-containing silicone water dispersion / Si-H-containing silicone water dispersion / platinum-based catalyst was used according to the blending composition shown in Table 1, and the coating liquid was prepared by diluting it with water so that the solid content concentration of the coating liquid became 10% in a manner to give a layer thickness of 50 nm.

[0215] The above formulation and the above results are shown in Table 1. In addition, the numerical value of each silicone represents the mass part of the solid content.

[0216] [Table 1]

[0217]

[0218] As can be seen from Table 1, the films of the examples of the present invention also have excellent peelability for ceramic sheets as thin as 2 μm. This is presumably because a film with excellent peelability is obtained by using a specific composition including a high molecular weight silicone, a low molecular weight silicone, and a Si-H group-containing silicone that can be cross-linked. On the other hand, in Comparative Examples 1 to 7, the cross-linking is insufficient and the film is not cured, or appropriate light peelability is not obtained.

Claims

1. A silicone release polyester film having a coating layer formed using a release coating composition, The demoulding coating composition comprises: An aqueous dispersion (1) of an organosilicon (A) having a number average molecular weight of 25,000 or more and containing three or more alkenyl groups in one molecule; A water dispersion (2) of an organosilicon (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 an organosilicon (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 Platinum catalysts, When the total solid content of the silicone (A), the silicone (B) and the silicone (C) is set to 100 parts by mass, the silicone (A) contains 80 parts by mass or more, the silicone (B) contains 2 parts by mass or more and 20 parts by mass or less, and the silicone (C) contains 2 parts by mass or more and 20 parts by mass or less.

2. The silicone release polyester film according to claim 1, wherein The organosilicon (A) has alkenyl groups at both terminals and in a side chain in one molecule.

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

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

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

6. The silicone release polyester film according to claim 1 or 2, wherein: The content of the platinum-based catalyst is 120 ppm or more relative to the total amount of the organosilicon (A) and the organosilicon (B).

7. The silicone release polyester film according to 1 or 2, which is used for molding ceramic green sheets in the production of laminated ceramic capacitors.

8. A method for producing a silicone release polyester film, comprising the steps of: forming a coating layer using a release coating composition, The demoulding coating composition comprises: An aqueous dispersion (1) of an organosilicon (A) having a number average molecular weight of 25,000 or more and containing three or more alkenyl groups in one molecule; A water dispersion (2) of an organosilicon (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 an organosilicon (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 Platinum catalysts, When the total solid content of the silicone (A), the silicone (B) and the silicone (C) is 100 parts by mass, the silicone (A) contains 80 parts by mass or more, the silicone (B) contains 2 parts by mass or more and 20 parts by mass or less, and the silicone (C) contains 2 parts by mass or more and 20 parts by mass or less.

9. The manufacturing method according to claim 8, wherein: The organosilicon (A) has alkenyl groups at both terminals and in a side chain in one molecule.

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

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