KR20210036404A - Release film for ceramic green sheet manufacturing - Google Patents

Abstract

The present invention provides a release film for manufacturing a ceramic green sheet having excellent peelability by controlling the deterioration of the surface roughness due to agglomeration during drying of the release layer and having high smoothness, and by adjusting the amount of the silicon-based component on the surface of the release layer. It is to do.
In the present invention, a polyester film is used as a substrate, the substrate has a surface layer A that does not contain substantially particles on at least one side, and is directly or another layer on the surface of the surface layer A on at least one side. A release film in which a release layer is laminated through a release layer, wherein the release layer is formed by curing a composition containing a binder component and a silicone release agent, and the Si element ratio on the surface of the release layer is 2.0 at% or more and 10.0 at% or less. It is a release film for producing a ceramic green sheet having a maximum protrusion height P of the layer surface of 50 nm or less and a region average roughness Sa of 1.5 nm or less.

Description

Release film for ceramic green sheet manufacturing

The present invention relates to a release film for manufacturing a ceramic green sheet, and in particular, an ultra-thin layer ceramic capable of manufacturing a material in which the occurrence of process defects due to pinholes and thickness unevenness is suppressed during the production of an ultra-thin layer ceramic green sheet. It relates to a release film for manufacturing a green sheet.

In recent years, with the miniaturization and increase in capacity of multilayer multilayer ceramic capacitors (abbreviated as MLCCs), a thin film of ceramic green sheets has been demanded. The multilayer multilayer ceramic capacitor forms a ceramic green sheet by coating and drying a slurry containing a ceramic component such as barium titanate and a binder resin on a release film, and then printing electrodes on the obtained ceramic green sheet. It is produced by peeling from the release film, laminating and pressing a ceramic green sheet, and applying an external electrode after degreasing and firing.

In order to increase the size and capacity of the MLCC, it is necessary to thin the ceramic green sheet, the thickness of which is 1.0 µm or less, and furthermore, it has become a thin film of 0.6 µm or less, and further thinning is proceeding. However, when the ceramic green sheet is thinned, there is a problem that defects such as pinholes and cracks are liable to occur due to extremely minute protrusions on the release film or the force when peeling from the release film.

In order to solve these problems, as a release film used for molding a ceramic green sheet, a film in which a release layer is provided on a polyester film and the surface of the release layer is highly smooth has been proposed. In Patent Document 1, it is disclosed that a smoothing layer is provided on the surface of a polyester film, and then a release layer is provided on the smoothing layer. Further, Patent Document 2 discloses that a release layer composed of a (meth)acrylic acid ester and a silicone component is formed to have a thickness of 0.3 µm or more. According to the description of Patent Document 1 and Patent Document 2, it is disclosed that the arithmetic mean roughness (Ra) of the surface of the release layer can be 8 nm or less and the maximum protrusion height Rp can be 50 nm or less.

However, according to the techniques described in Patent Documents 1 and 2, since the thickness of the resin layer (release layer and smoothing layer) laminated on the polyester film is thick, it takes time to cure and the amount of organic solvent to be used increases. There have been problems such as a large environmental load. Moreover, since the film thickness of a release layer is thick, curling of the obtained release film etc. may also become a subject in some cases. Further, in the techniques described in these documents, the amount of the silicone component contained in the release layer is large, so that the elastic modulus of the surface of the release layer is low, and there is a concern that peeling becomes unstable.

In addition, as a release layer of a release film for forming a ceramic green sheet, the following proposals have also been made. In Patent Document 3, a non-silicone-based mold release layer in which silicon is not contained in the mold release layer is proposed. In Patent Document 4, a film in which a silicone resin is used as a release layer is proposed. However, in the case of a non-silicon-based release layer as in the technique described in Patent Document 3, the peeling force when peeling off the ceramic green sheet increases, and there is a problem in that the ceramic green sheet formed into a thin film suffers damage. In addition, in the release layer of a silicone-based resin as described in Patent Document 4, the peeling force when peeling the ceramic green sheet is small, but since the glass transition temperature of the silicone resin is generally room temperature or lower, the elastic modulus is low and peeling When the release layer is deformed, there is a problem that the peeling force becomes unstable.

In addition, in Patent Document 5, a release layer containing an alkyd resin, an amino resin, and a modified silicone resin is proposed. In addition, in Patent Document 6, a release layer containing a melamine resin and a polyorganosiloxane is proposed. It has been proposed that a crosslinked product such as melamine resin is mainly contained as a binder for the release layer, and a silicone resin is added as a release component to increase the elastic modulus of the release layer and make both deformability and releasability compatible.

However, as described in Patent Documents 5 and 6, if a release layer containing a binder resin and a silicone resin, the solubility of the binder resin and the silicone resin in an organic solvent and the surface tension of the solution are greatly different, so that during drying The compatibility deteriorates, and each resin aggregates and becomes a projection, and there existed the subject which worsens the surface roughness of the surface of a release layer. In the case of forming a ceramic green sheet having a thickness of 1.0 µm or less, and furthermore, 0.6 µm or less, pinholes, etc., are generated even with such a deterioration of the fine surface roughness, which deteriorates the defect rate of the obtained multilayer ceramic capacitor. Smoothness was required.

Japanese Unexamined Publication No. 2014-177093 International Publication No. 2013/145864 Japanese Unexamined Patent Publication No. 2010-144046 Japanese Unexamined Patent Publication No. 2012-207126 Japanese Unexamined Patent Application Publication No. Hei 9-239913 Japanese Unexamined Publication No. 2017-7226

In view of the above circumstances, the present invention is a release layer of a release film for producing a ceramic green sheet, even if it is a release layer formed by curing a composition containing at least a binder component and a silicone release agent, the surface roughness due to agglomeration during drying of the component. It is intended to provide a release film for producing a ceramic green sheet having excellent peelability by suppressing deterioration of the material, having high smoothness, and adjusting the amount of the silicon-based component on the surface of the release layer.

That is, the present invention has the following configuration.

1. A polyester film is used as a substrate, the substrate has a surface layer A that is substantially free of particles on at least one side, and directly or another layer on the surface of the surface layer A on at least one side It is a release film in which a release layer is laminated therebetween, and the release layer is formed by curing a composition containing a binder component and a silicone release agent, and the Si element ratio on the surface of the release layer is 2.0 at% or more and 10.0 at% or less, and the release layer A release film for manufacturing a ceramic green sheet having a maximum protrusion height (P) of the surface of 50 nm or less and a region average roughness (Sa) of 1.5 nm or less.

2. The release film for producing a ceramic green sheet according to the first item, wherein the silicone release agent is a silicone resin having a polyether moiety or a carboxyl group.

3. The release film for producing a ceramic green sheet according to the first or second above, wherein the component derived from the silicone release agent is contained in the release layer from 1 to 15 mg/m 2.

4. The release film for producing a ceramic green sheet according to any one of the first to third described above, wherein the binder component contains a resin having a long-chain alkyl group and/or a silicone skeleton.

5. A method for manufacturing a ceramic green sheet in which a ceramic green sheet is formed using the release film for producing a ceramic green sheet according to any one of the above 1 to 4, wherein the formed ceramic green sheet has a thickness of 0.2 µm to 1.0 µm. Method of manufacturing a ceramic green sheet having.

6. A method for manufacturing a ceramic capacitor employing the method for manufacturing a ceramic green sheet according to the fifth above.

According to the present invention, even if the release layer contains at least a binder component and a silicone release agent, it has high smoothness by suppressing deterioration of the surface roughness due to agglomeration during drying of the component, and also adjusts the amount of the silicone component on the surface of the release layer. By doing so, it becomes possible to provide a release film for ceramic green sheet production, which has good peelability and can reduce defects such as pinholes, even in production of an ultra-thin ceramic green sheet having a film thickness of 0.2 to 1.0 µm having excellent peelability.

In order to solve the above problems, the present inventors have carefully studied and optimized the drying conditions after coating the release layer and the content of the silicone-based compound in the release layer, thereby making a polyester film having a surface layer A that does not contain substantially particles on at least one side. A release film formed by laminating a release layer directly or through another layer on at least one surface layer A of the release layer, wherein the release layer is made by curing a composition containing a binder component and a silicone release agent, and the maximum protrusion height on the surface of the release layer A release film for ceramic green sheet production having a (P) of 50 nm or less, a region average roughness (Sa) of 1.5 nm or less, and a Si element ratio of 2.0 at% or more and 10.0 at% or less on the outermost surface of the release layer, has a film thickness of 0.2 to 1.0 When forming a ceramic green sheet having an ultrathin thickness of µm, it was found that the peelability was excellent and defects such as pinholes were reduced. Hereinafter, the present invention will be described in detail.

(Polyester film)

In the present invention, the polyester constituting the polyester film used as the base material is not particularly limited, and a film-molded polyester generally used as the base material for a release film may be used. It is preferable that it is a crystalline linear saturated polyester composed of a base acid component and a diol component, for example, polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, or Copolymers containing the constituent components of these resins as a main component are more suitable, and among them, polyester films formed from polyethylene terephthalate are 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 be copolymerized, but from the viewpoint of cost, terephthalic acid And ethylene glycol is preferred. Further, well-known additives such as antioxidants, light stabilizers, ultraviolet absorbers, crystallizers, and the like may be added within a range that does not impair the effect of the film of the present invention. It is preferable that a polyester film is a biaxially oriented polyester film from reasons, such as high elasticity modulus in a bidirectional direction.

The intrinsic viscosity of the polyethylene terephthalate film is preferably 0.50 to 0.70 dl/g, more preferably 0.52 to 0.62 dl/g. When the intrinsic viscosity is 0.50 dl/g or more, it is preferable because fracture does not occur much in the stretching process. On the contrary, if it is 0.70 dl/g or less, it is preferable because it has good cutting properties when cutting to a predetermined product width, and dimensional defects do not occur. Moreover, it is preferable to sufficiently vacuum-dry the raw material pellets.

The method for producing the polyester film in the present invention is not particularly limited, and a method generally used in the past can be used. For example, the polyester is melted with an extruder, extruded into a film, and cooled with a rotary cooling drum to obtain an unstretched film, which can be obtained by biaxially stretching the unstretched film. . The biaxially stretched film is a method of sequentially biaxially stretching a uniaxially stretched film in a vertical direction or a horizontal direction in a horizontal direction or a vertical direction, or a method of simultaneously biaxially stretching an unstretched film in a vertical direction and a horizontal direction You can get it.

In the present invention, the stretching temperature at the time of stretching the polyester film is preferably equal to or higher than the secondary transition point (Tg) of the polyester. It is preferable to elongate 1 to 8 times, particularly 2 to 6 times, in each of the vertical and transverse directions.

The polyester film preferably has a thickness of 12 to 50 µm, more preferably 15 to 38 µm, and still more preferably 19 µm to 33 µm. When the thickness of the film is 12 µm or more, it is preferable because there is no fear of deformation due to heat during film production, processing of a release layer, or molding of a ceramic green sheet. On the other hand, when the thickness of the film is 50 µm or less, the amount of the film to be discarded after use is not extremely large, and it is preferable in reducing the environmental load.

The biaxially oriented polyester film base material may be a single layer or a multilayer of two or more layers, but it is preferable to have a surface layer A substantially free of particles on at least one side. In the case of a laminated polyester film having a multilayer structure of two or more layers, it is preferable to have a surface layer B capable of containing particles or the like on the opposite surface of the surface layer A that does not contain particles substantially. In the lamination structure, if the layer on the side to which the release layer is applied is the surface layer A, the layer on the opposite side is the surface layer B, and the other deep layer is the layer C, the layer structure in the thickness direction is the release layer/A. A laminated structure, such as /B or a release layer/A/C/B, is mentioned. Naturally, the layer C may be composed of a plurality of layers. Further, the surface layer B may not contain particles. In that case, it is preferable to provide a coat layer containing particles and a binder on the surface layer B in order to impart a slip property for winding the film into a roll shape.

In the polyester film base material in the present invention, it is preferable that the surface layer A forming the surface to which the release layer is applied substantially does not contain particles. At this time, the area surface average roughness (Sa) of the surface layer A is preferably 7 nm or less. When Sa is 7 nm or less, it is preferable that pinholes or the like are less likely to occur during molding of the super-thin ceramic green sheet to be laminated. It can be said that the smaller the area surface average roughness (Sa) of the surface layer A is, the more preferable it is, but it may be 0.1 nm or more. Here, in the case of providing an anchor coat layer or the like described later on the surface layer A, it is preferable that particles are not substantially included in the coat layer, and the area surface average roughness (Sa) after lamination of the coat layer satisfies the above range. It is desirable. In the present invention, "substantially free of particles" means, for example, in the case of inorganic particles, when the inorganic elements are quantified by fluorescence X-ray analysis, 50 ppm or less, preferably 10 ppm or less, most preferably detection. It means the content which falls below the limit. This is because even if particles are not actively added to the film, contaminants derived from foreign substances and dirt adhered to the line or device in the manufacturing process of the raw material resin or film may be peeled off and mixed into the film.

In the polyester film base material of the present invention, the surface layer B forming the opposite surface to the surface to which the release layer is applied is preferably containing particles from the viewpoint of the sliding property of the film and the easiness of removing air, and in particular It is preferred to use silica particles and/or calcium carbonate particles. The content of the particles to be contained is preferably 5000 to 15000 ppm in total of the particles in the surface layer B. At this time, the region surface average roughness (Sa) of the film of the surface layer B is preferably in the range of 1 to 40 nm. More preferably, it is a range of 5 to 35 nm. When the total of silica particles and/or calcium carbonate particles is 5000 ppm or more and Sa is 1 nm or more, air can be evenly released when the film is rolled up, resulting in a good rolled shape and good planarity. This makes it suitable for manufacturing an ultra-thin ceramic green sheet. In addition, when the total of silica particles and/or calcium carbonate particles is 15000 ppm or less and Sa is 40 nm or less, agglomeration of the lubricant is difficult to occur and coarse projections do not occur. It is preferable because the quality is stable during sheet manufacturing.

As the particles contained in the surface layer B, inert inorganic particles and/or heat-resistant organic particles other than silica and/or calcium carbonate may be used. Although it is more preferable to use silica particles and/or calcium carbonate particles from the viewpoint of transparency and cost, examples of other inorganic particles that can be used include alumina-silica composite oxide particles, hydroxyapatite particles, and the like. Further, examples of the heat-resistant organic particles include crosslinked polyacrylic particles, crosslinked polystyrene particles, benzoguanamine particles, and the like. Further, when using silica particles, porous colloidal silica is preferable, and when using calcium carbonate particles, hard calcium carbonate subjected to a surface treatment with a polyacrylic acid-based polymer compound is preferable from the viewpoint of preventing the lubricant from falling off.

The average particle diameter of the particles added to the surface layer B is preferably 0.1 µm or more and 2.0 µm or less, and particularly preferably 0.5 µm or more and 1.0 µm or less. When the average particle diameter of the particles is 0.1 µm or more, the sliding property of the mold release film is good, which is preferable. Moreover, when the average particle diameter is 2.0 micrometers or less, there is no possibility that pinholes are generated in the ceramic green sheet by coarse particles on the surface of the release layer, and it is preferable.

The surface layer B may contain two or more types of particles of different materials. Moreover, you may contain particles of the same type and having different average particle diameters.

In the case where the surface layer B does not contain particles, it is preferable to provide easy activity with a coat layer containing particles on the surface layer B. Although this coat layer is not specifically limited, It is preferable to provide so-called in-line coat to be applied during film-forming of a polyester film. When the surface layer B does not contain particles and has a coating layer containing particles on the surface layer B, the surface of the coating layer is the same as the area surface average roughness (Sa) of the surface layer B described above. It is preferable that the average roughness (Sa) is in the range of 1 to 40 nm. More preferably, it is a range of 5 to 35 nm.

In the surface layer A, which is a layer on the side where the release layer is provided, it is preferable not to use a recycled raw material or the like in order to prevent mixing of particles such as a lubricant from the viewpoint of reducing pinholes.

It is preferable that the thickness ratio of the surface layer A, which is the layer on the side where the release layer is provided, is 20% or more and 50% or less of the total thickness of the base film. If it is 20% or more, it is difficult to receive the influence of the particles contained in the surface layer B or the like from the inside of the film, and it is preferable that the area surface average roughness Sa satisfies the above range easily. If it is 50% or less of the thickness of all the layers of the base film, the use ratio of the recycled raw material in the surface layer B can be increased, and the environmental load is reduced, which is preferable.

Further, from the viewpoint of economical efficiency, 50 to 90 mass% of film scrap or recycled raw materials for PET bottles can be used for the layers other than the surface layer A (surface layer B or the intermediate layer C described above). Also in this case, it is preferable that the type and amount of the lubricant contained in the surface layer B, the particle diameter, and the area surface average roughness Sa satisfy the above range.

In addition, a coat 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 forming process on the surface of the surface layer A and/or surface layer B in order to improve the adhesion of the release layer to be applied later or to prevent charging. , Corona treatment, etc. can also be performed. When providing a coat layer on the surface layer A, it is preferable that the said coat layer does not contain a particle substantially.

(Release layer)

It is preferable that the release layer in the present invention is formed by curing a composition containing at least a binder component and a silicone release agent. In addition to the resin or compound, other components may be added to the extent that the effects of the present invention are not impaired.

(Binder ingredient)

The binder component contained in the composition for forming a release layer of the present invention is not particularly limited, but a component capable of crosslinking is crosslinked in order to increase the crosslinking density of the release layer and improve durability and solvent resistance of the release layer. It is desirable. Therefore, it is preferable that a resin having a reactive functional group and a crosslinking agent are reacted with the binder component. Moreover, it is also preferable to perform self-crosslinking of either a reactive functional group or a crosslinking agent alone. However, in the present invention, the embodiment in which the binder component consists only of a resin or a crosslinking agent having a reactive functional group is not excluded.

Although it does not specifically limit as resin which has a reactive functional group, A polyester resin, a poly(meth)acrylic resin, a polyurethane resin, a polyolefin resin, etc. can be used suitably. It is preferable that these resins have at least one or more selected from a carboxyl group, a hydroxyl group, an epoxy, an amino group and the like as a reactive functional group.

It is preferable that the resin having a reactive functional group has a long-chain alkyl group and/or a silicone skeleton in a part of the resin skeleton. By having a portion of the resin skeleton with a low surface free energy portion such as a long-chain alkyl group and/or a silicone skeleton, the compatibility between the silicone-based releasing agent and the binder component described later increases, making it difficult to agglomerate during drying, thereby improving smoothness. Do.

Specific examples of the reactive functional group-containing resin having a long-chain alkyl group in the resin skeleton include alkyd resins or (meth)acrylic resins having a long-chain alkyl group in the side chain. As the long-chain alkyl group to be used, a straight-chain alkyl group having 6 to 20 carbon atoms is suitable. By having the aforementioned carbon number, the surface free energy of the obtained resin can be reduced, and the compatibility with the silicone-based mold release agent is improved, which is preferable.

In the case of an alkyd resin having a long chain alkyl group in the side chain, an acid having a long chain alkyl group (e.g., octylic acid or stearylic acid, etc.) is mixed with a polybasic acid such as phthalic acid, and a polyhydric alcohol component (pentaerythritol or diethylene glycol) is mixed. Etc.), and can be obtained by a dehydration condensation reaction.

The (meth)acrylic resin having a long-chain alkyl group in the side chain is preferably obtained by copolymerizing two or more types of (meth)acrylic monomers. As a monomer to be copolymerized, it is preferable to contain a monomer having a long-chain alkyl group (e.g., lauryl (meth)acrylate, stearyl (meth)acrylate, isodecyl (meth)acrylate, etc.), and a reactive functional group moiety As examples, it is preferable to include a monomer having a hydroxy group (eg, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, etc.). In addition to the above, other bases such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexanediol dimethacrylate, butanediol diacrylate, etc., in order to impart Tg adjustment, crosslinkability, reactivity, and the like of the obtained polymer ( A monomer of knowledge) may also be included.

It is preferable that content of the monomer which has a long-chain alkyl group which comprises the obtained acrylic resin is 1 mol% or more and 50 mol% or less with respect to all the monomers which comprise an acrylic resin. If it is 1 mol% or more, since it has the effect of lowering the surface free energy, it is preferable. If it is 50 mol% or less, since the monomer having a reactive functional group is relatively high, the crosslinking density of the resin is increased, which is preferable.

Specific examples of the reactive functional group-containing resin having a silicone skeleton in the resin skeleton include alkyd resins or acrylic resins having a polydimethylsiloxane skeleton in the side chain. Specific examples of commercially available products include Cymac (registered trademark) US350, US352 (manufactured by Doa Gosei, reactive functional group: carboxyl group), and Cymac (registered trademark) US270 (manufactured by Doa Gosei, reactive functional group: hydroxyl group). have.

(Crosslinking agent)

It is also preferable to contain a crosslinking agent in a binder component. Although it does not specifically limit as a crosslinking agent, A melamine-type, isocyanate-type, carbodiimide-type, oxazoline-type, epoxy-type crosslinking agent etc. can be used, and even if it is 1 type, you may use it in combination of 2 or more types. Particularly preferably, a crosslinking agent that reacts with the reactive functional group introduced into the binder component is preferred.

As the crosslinking agent used in the present invention, a melamine-based compound is preferable from the viewpoint of reactivity. The use of a melamine-based compound is preferable because even a thin film having a coating amount of 0.2 g/m 2 or less after curing the release layer can be rapidly cured and the crosslinking density is increased.

As the melamine-based compound used in the present invention, a general one can be used and is not particularly limited, but it is obtained by condensing melamine and formaldehyde, and is obtained by condensing melamine and formaldehyde, and each of a triazine ring and a methylol group and/or an alkoxymethyl group in one molecule It is desirable to have more than one. Specifically, a methylol melamine derivative obtained by condensing melamine and formaldehyde is preferably a compound obtained by dehydrating condensation reaction of methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, or the like as a lower alcohol, and the like. Examples of methylolated melamine derivatives include monomethylol melamine, dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, and hexamethylol melamine. Even if one type is used, two or more types may also be used.

As the melamine-based compound, since the crosslinking density of the binder component can be increased, it is preferable to use hexamethylol melamine, hexamethoxymethylol melamine, or the like having many crosslinking points in one molecule. In the case of using an ether compound subjected to a dehydration condensation reaction using an alcohol for a methylol melamine derivative, hexamethoxymethylmethylol melamine obtained by dehydration condensation with methyl alcohol is particularly preferred from the viewpoint of reactivity.

The amount of the crosslinking agent contained in the binder component in the present invention is preferably 15% by mass or more, more preferably 30% by mass or more, and still more preferably 50% by mass with respect to the resin having a reactive functional group. In addition, when the crosslinking agent can self-condensate to form a resin film, the binder component may be constituted only by the crosslinking agent. By containing 15 mass% or more of a crosslinking agent, since the crosslinking density of a mold release layer can be raised and a solvent resistance and an elastic modulus can be improved, it is preferable.

(catalyst)

The composition for forming a release layer in the present invention may contain a catalyst in order to cure the crosslinking agent. In the case of using a melamine-based compound, it is preferable to use an acid catalyst, and although it is not particularly limited, a carboxylic acid-based, metal salt-based, phosphoric acid ester-based, or sulfonic acid-based one can be suitably used. In addition, a block-type catalyst in which an acid moiety is blocked can also be used. In particular, from the viewpoint of reactivity, paratoluenesulfonic acid can be suitably used. When an isocyanate-based compound is used, a general one can be used, and an organic tin, an amine compound, a trialkylphosphine compound, or the like can be suitably used.

The content of the catalyst is preferably 0.1 to 40% by mass based on the crosslinking agent contained in the composition for forming a release layer. More preferably, it is 0.5 to 30 mass %. More preferably, it is 0.5-20 mass %. When it is 0.1 mass% or more, it is easy to advance a hardening reaction, and is preferable. On the other hand, when it is 40 mass% or less, there is no possibility that an acid catalyst will migrate to the ceramic green sheet to be molded, and it is preferable from the point that there is no possibility of exerting an adverse effect.

(Silicone release agent)

The silicone-based release agent used for the release layer in the present invention is a compound having a silicone structure in the molecule, and is not particularly limited as long as the effect of the present invention can be obtained, but polyorganosiloxane or the like can be suitably used. Among the polyorganosiloxanes, polydimethylsiloxane (abbreviated as PDMS) can be suitably used, and it is preferable that a part of the polydimethylsiloxane has a functional group. Having a functional group is preferable because molecular interactions such as a binder resin and a hydrogen bond are easily expressed, and it becomes difficult to transfer to a ceramic green sheet.

The functional group to be introduced into the polydimethylsiloxane is not particularly limited, but may be a reactive functional group or a non-reactive functional group. In addition, the functional group may be introduced at one end of the polydimethylsiloxane, and may be both ends or side chains. Moreover, the position to be introduced may be one or a plurality of positions.

Examples of the reactive functional group introduced into the polydimethylsiloxane include an amino group, an epoxy group, a hydroxyl group, a mercapto group, a carboxyl group, a methacrylic group, and an acrylic group. As the non-reactive functional group, a polyether group, an aralkyl group, a fluoroalkyl group, a long-chain alkyl group, an ester group, an amide group, a phenyl group, and the like can be used. Although not particularly bound by theory, among the above, it is preferable to have an epoxy group, a carboxyl group, a polyether group, a methacrylic group, an acrylic group, and an ester group.

It is more preferable that the functional group introduced into the polydimethylsiloxane does not react with the binder component. For example, polydimethylsiloxane modified with a hydroxyl group that reacts with a melamine resin reacts with melamine in the drying process, so it is difficult to orientate to the surface of the release layer, so that the ratio of Si elements on the surface of the release layer decreases, resulting in releasability. There are cases where it is difficult. Therefore, it is necessary to increase the amount of addition in order to have sufficient releasability, but in that case, the elastic modulus of the release layer is lowered, and there is a concern that deformation of the release layer is likely to occur.

As the functional group introduced into the polydimethylsiloxane, a polyether group and an ester group are particularly preferred as a functional group that does not react with the binder resin for the above-described reason, is easily oriented on the surface of the release layer, and has little transferability to the ceramic green sheet. And a polyether group is particularly preferred. Even if it reacts with the binder resin, a carboxyl group is mentioned as a functional group which relatively increases the ratio of the Si element on the surface of the release layer.

It is preferable that the molecular weight of the silicone-type mold release agent used in this invention is 40000 or less. More preferably, it is 30000 or less. When the molecular weight is 40000 or less, the silicone-based release agent tends to segregate on the surface of the release layer, and the peelability is good, which is preferable.

It is preferable that the content of the component derived from the silicone release agent contained in the mold release layer after curing in the present invention is 1 mg/m 2 or more and 15 mg/m 2 or less. 1 mg/m 2 or more and 10 mg/m 2 or less are more preferable. If it is 1 mg/m 2 or more, since the silicon component can sufficiently precipitate on the outermost layer of the release layer and the peelability of the ceramic green sheet is stabilized, it is preferable. If it is 15 mg/m 2 or less, since there are few silicone components having a relatively low elastic modulus in the release layer, the elastic modulus of the release layer is not too low, and the peelability of the ceramic sheet is stabilized, so it is preferable. Here, the silicone-based release agent may be present in the same structure without changing its chemical structure even in the cured release layer, or if the chemical structure is changed due to causing a chemical reaction between the binder component, etc. There is also. Therefore, the mass of the substance derived from the silicone-based release agent in the composition before curing and present per unit area of the release layer after curing is described as the content of the component derived from the silicone-based release agent. The content of the component derived from the silicone release agent can be calculated from the ratio (mass%) of the silicone release agent present in the solid content of the coating liquid containing the composition and the applied amount (g/m2) of the solid content of the release layer after curing.

The release layer in the present invention may contain particles or the like having a particle diameter of 1 µm or less, but from the viewpoint of suppressing pinholes of the ceramic green sheet, it is preferable not to contain particles or other protrusions.

Additives, such as an adhesion improver and an antistatic agent, may be added to the release layer in the present invention as long as the effect of the present invention is not impaired. In addition, in order to improve the adhesion to the substrate, it is also preferable to perform pretreatment such as anchor coat, corona treatment, plasma treatment, atmospheric pressure plasma treatment, etc. on the surface of the polyester film before the release coating layer is provided.

In the present invention, the amount of the release layer applied after curing is not particularly limited, but is preferably 1.0 g/m 2 or less. It is more preferably 0.01 to 0.5 g/m 2, more preferably 0.02 to 0.20 g/m 2, and more preferably 0.02 to 0.09 g/m 2. When the coating amount of the release layer is 0.01 g/m 2 or more, peeling performance is easily obtained and is preferable. If it is 0.2 g/m 2 or less, since the curing time of the release layer can be shortened, the flatness of the release film is maintained and the thickness unevenness of the ceramic green sheet can be suppressed, which is preferable. In addition, if it is 0.2 g/m 2 or less, the curl of the obtained film is also reduced, and thus the molding accuracy is improved during the ceramic green sheet molding, which is preferable.

It is preferable that the surface free energy of the surface of the release layer of the release film of the present invention is 18 mJ/m 2 or more and 35 mJ/m 2 or less. More preferably, they are 20 mJ/m 2 or more and 30 mJ/m 2 or less, and still more preferably 21 mJ/m 2 or more and 28 mJ/m 2 or less. If it is 18 mJ/m 2 or more, cissing is less likely to occur when the ceramic slurry is coated, and thus uniform coating can be performed, which is preferable. Moreover, if it is 35 mJ/m 2 or less, there is no fear that the releasability of the ceramic green sheet will be lowered, which is preferable. By setting it as the above range, it is possible to provide a release film that is excellent in releasability and no seaming at the time of coating.

It is preferable that the release film of the present invention has a peeling force of 0.5 mN/mm2 or more and 3mN/mm2 or less when the ceramic green sheet is peeled off. More preferably, it is 0.8mN/mm2 or more and 2.5mN/mm2 or less. More preferably, it is 1.0mN/mm2 or more and 1.8mN/mm2 or less. If the peeling force is 0.5mN/mm2 or more, the peeling force is not too light, and there is no fear that the ceramic green sheet may float during transportation, which is preferable. If the peeling force is 3mN/mm2 or less, there is no fear that the ceramic green sheet will be damaged during peeling, which is preferable.

It is preferable that the release film of this invention has few curls. Specifically, the curl after heating at 100°C for 15 minutes without applying tension to the film is preferably 2 mm or less, and more preferably 1 mm or less. Of course, it is also desirable to have no curls at all. When the thickness is 2 mm or less, it is preferable to form a ceramic green sheet and to increase the printing accuracy due to less curl when printing the electrode.

It is preferable that a component derived from a silicone-based releasing agent contained in the releasing layer is sufficiently precipitated on the surface of the releasing layer of the releasing film of the present invention. As an index indicating the precipitation amount of the component derived from the silicon-based releasing agent, the ratio of the Si element on the surface of the releasing layer can be used. The Si element ratio on the surface of the release layer can be evaluated by ESCA that can measure only the surface of the release layer. In addition, the Si element ratio in the present invention is the ratio (at%) of Si in the five elements C, S, Si, O, and N as shown in the following equation.

Si element ratio (at%) = {Si/(C+O+N+S+Si)}×100... expression

It is preferable that the ratio of the Si element on the outermost surface of the release layer of the release film of the present invention is 2.0 at% or more. It is more preferably 2.5 at% or more, even more preferably 3.0 at% or more, and even more preferably 3.5 at% or more. If it is 2.0 at% or more, the silicon-based releasing agent can sufficiently cover the surface of the releasing layer, and the peeling force is stabilized when peeling off the ceramic green sheet of the thin film, which is preferable. The upper limit of the Si element ratio is preferably 10 at% or less, more preferably 9 at% or less, and even more preferably 8 at% or less. If it is 10 at% or less, since the elastic modulus of the surface of the release layer is not lowered and peeling is stabilized, it is preferable.

In order to achieve the Si element ratio of the outermost surface of the release layer of the release film of the present invention, the content of the component derived from the silicone release agent contained in the release layer after curing described above and the passage time of the initial drying step after coating the release layer described later are optimized. It is desirable.

The surface of the release layer of the release film of the present invention is preferably flat, and the area surface average roughness (Sa) is preferably 1.5 nm or less, more preferably, in order not to cause defects in the ceramic green sheet applied and molded thereon. It is preferably 1.2 nm or less, and even more preferably 1.0 nm or less. Moreover, it is preferable that the maximum protrusion height (P) on the surface of the release layer is 50 nm or less, more preferably 40 nm or less, and even more preferably 30 nm or less. When the area surface average roughness (Sa) is 1.5 nm or less and the maximum protrusion height (P) is 50 nm or less, defects such as pinholes do not occur at the time of forming the ceramic green sheet, and the yield is good, which is preferable. It can be said that the smaller the area surface average roughness Sa is, the more preferable it is, but it does not matter if it is 0.1 nm or more, and it does not matter even if it is 0.3 nm or more. It can be said that the smaller the maximum protrusion height P is, the more preferable it is, but it does not matter if it is 1 nm or more, and it does not matter if it is 3 nm or more.

Since the release film of the present invention uses a highly flattened base film, it is preferable that the application amount of the release layer is 0.2 g/m 2 or less, and further, even if it is thinner than 0.09 g/m 2, the surface of the release layer can be smoothed. Therefore, it is environmentally friendly because the amount of solvent and resin to be used can be reduced, and a release film for molding an ultra-thin ceramic green sheet can be prepared at low cost.

In order to make the maximum protrusion height (P) on the surface of the release layer of the release film of the present invention to be 50 nm or less and the area average roughness (Sa) to be 1.5 nm or less, apply the coating solution of the release layer and the silicone release agent or binder component until dry. It is preferable to suppress the aggregation of. Therefore, as described in the manufacturing method described later, the target ultra-high smooth surface of the release layer can be obtained by performing the time from coating to drying under certain conditions.

(Manufacturing method of release film)

The method for producing the release film of the present invention is not particularly limited, but a coating step in which a coating solution obtained by dissolving or dispersing at least a binder component and a silicone release agent in a solvent is laminated on at least one side of the polyester film of the base material, and application. After that, it is preferable to use a method in which a release layer is laminated through an initial drying step of mainly removing a solvent and a heat curing step of curing a binder resin or the like. It is preferable that the surface of the polyester film on the side where the release layer is provided is a surface layer A that does not contain particles substantially, and another coat layer may exist between the surface layer A and the release layer.

(Application process)

Although it does not specifically limit as a solvent for dissolving or dispersing a binder resin and a silicone type release agent, it is preferable to use an organic solvent. Since the surface tension of the coating solution can be lowered by using an organic solvent, it is difficult to generate seaming or the like after application, and it is preferable because the smoothness of the surface of the release layer can be maintained high.

The organic solvent used in the method for producing a release film of the present invention is not particularly limited, and an existing one can be used. As the solvent, usually, aromatic hydrocarbons such as benzene, toluene and xylene, fatty acid hydrocarbons such as cyclohexane, n-hexane, and n-heptane, halogenated hydrocarbons such as perchloroethylene, ethyl acetate, and methyl ethyl ketone, And methyl isobutyl ketone. Considering the applicability in the case of applying to the surface of the base film, it is not limited, but in practical use, it is preferably a mixed solvent of toluene and methyl ethyl ketone.

In the present invention, the coating liquid used for coating for forming a release layer is not particularly limited, but it is preferable to contain two or more kinds of organic solvents having different boiling points. It is preferable that at least one type of organic solvent has a boiling point of 100°C or higher. By adding a solvent having a boiling point of 100°C or higher, it is possible to prevent swelling during drying, to level the coating film, and to improve the smoothness of the surface of the coating film after drying. As the addition amount, it is preferable to add about 10 to 50 mass% with respect to the entire coating liquid. Examples of the solvent having a boiling point of 100°C or higher include toluene, xylene, heoctane, cyclohexanone, methyl isobutyl ketone, and n-propyl acetate.

In the present invention, the surface tension (20°C) of the coating solution when the coating solution for forming a release layer is applied is not particularly limited, but is preferably 30 mN/m or less. By making the surface tension as described above, the wettability after coating is improved, and irregularities on the surface of the coating film after drying can be reduced. In order to lower the surface tension of the coating solution, it is preferable to use the organic solvent forming the coating solution having a low surface tension. It is preferable that the surface tension (20 degreeC) of at least one type of organic solvent is 26 mN/m or less, More preferably, it is 23 mN/m or less. By including an organic solvent having a surface tension (20°C) of 26mN/m or less, it is preferable to reduce appearance defects such as sishing during application. It is preferable to add 20 mass% or more with respect to the whole coating liquid as the addition amount.

The solid content concentration of the mold release agent contained in the coating solution is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.2% by mass or more and 8% by mass or less. When the solid content concentration is 0.1% by mass or more, drying after application is quick, so aggregation of the components in the mold release agent is difficult to occur, which is preferable. On the other hand, when the solid content concentration is 10% by mass or less, the viscosity of the coating liquid is low, and the leveling property is good, so that the planarity after coating can be improved, which is preferable. The viscosity of the coating liquid is preferably 1 mPa·s or more and 100 mPa·s or less from the viewpoint of coating appearance, and more preferably 2 mPa·s or more and 10 mPa·s or less. It is preferable to adjust solid content concentration, organic solvent, etc. so that it may become this range.

In the present invention, it is preferable to filter the coating liquid for forming a release layer before application. The filtration method is not particularly limited and an existing method can be used, but it is preferable to use a surface type, depth type, or adsorption type cartridge filter. The use of a cartridge-type filter is preferable because it can be used when the coating liquid is continuously fed from the tank to the coating portion, and thus the productivity is good and the filter can be efficiently filtered. As the filtration accuracy of the filter, it is preferable to use one that removes 99% or more of 1 µm size, and more preferably, one that can filter 99% or more of the 0.5 µm size. By using the above-described filtration precision, foreign matter mixed in the release agent can be removed, and foreign matter adhering to the release film of the mold release film for forming a ceramic green sheet of the present invention can be significantly reduced. Therefore, the defects of the ceramic green sheet molded using the release film of the present invention can be reduced, and thus the defective rate of the ceramic capacitor can be reduced.

As the coating method of the coating liquid, any known coating method can be applied, for example, a roll coating method such as a gravure coating method or a reverse coating method, a bar coating method such as a wire bar, a die coating method, and a spray coating method. Conventionally known methods, such as a method and an air knife coating method, can be used.

It is preferable that the coating film thickness (Wet amount) at the time of application is 1 g/m 2 or more and 10 g/m 2 or less. If it is thicker than 1 g/m2, the coating is stabilized, so it is preferable that defects such as seasing and stripes do not appear. Moreover, if it is 10 g/m 2 or less, it dries quickly, and the component contained in a release layer is hard to aggregate, and it is preferable.

(Drying process)

As a method of applying and drying the coating liquid on the base film, known hot air drying, heat drying using an infrared heater or the like can be exemplified, but hot air drying with a high drying speed is preferable. The drying furnace can be divided into a constant-rate drying process at the initial stage of drying (hereinafter, referred to as an initial drying process), and a process in which reduction-rate drying and curing of the resin proceed (hereinafter, referred to as a heat-curing process). The initial drying step and the heat curing step may be continuous or discontinuous, but the continuous one is preferable because the productivity is better. It is preferable to distinguish each process by dividing the zone of the drying furnace. If the number of zones in each process is 1 or more, any number may be sufficient.

In the method for producing a release film of the present invention, it is preferable to put it in a drying furnace within 1.5 seconds after application, more preferably within 1.0 second, and even more preferably within 0.8 seconds. It is preferable because it can be dried before the aggregation of the components contained in the release layer occurs by putting it in a drying furnace within 1.5 seconds after application, and deterioration of the smoothness of the surface of the release layer due to aggregation can be prevented. It is preferable that the time until put into the drying furnace after application|coating is short, and although a lower limit is not provided in particular, it does not matter if it is 0.05 second or more, and it does not matter even if it is 0.1 second or more.

The initial drying process is not particularly limited, and an existing drying furnace can be used. The drying furnace method may be either a roll support method or a floating method, but since the roll support method has a wide range to adjust the air volume during drying, it is preferable because the air volume etc. can be adjusted according to the type of release layer. Do.

The temperature of the initial drying step is preferably 60°C or more and 140°C or less, more preferably 70°C or more and 130°C or less, and even more preferably 80°C or more and 120°C or less. By setting the temperature to 60°C or higher and 140°C or lower, the amount of the organic solvent contained in the release layer after application can be effectively dried without poor planarity due to heat, which is preferable.

The time to pass through the initial drying step is preferably 1.0 second or more and 3.0 seconds or less, more preferably 1.0 second or more and 2.5 seconds or less, and even more preferably 1.2 seconds or more and 2.5 seconds or less. If it is 1.0 second or more, since the organic solvent contained in the release layer after application|coating can be fully dried, it is preferable. In addition, 1.0 second or longer is preferable because the component derived from the silicone-based releasing agent contained in the releasing layer can be effectively precipitated on the surface of the releasing layer. Moreover, if it is 3.0 seconds or less, it is difficult to cause aggregation of the components in a release layer, and is preferable. By adjusting the solid content concentration of the coating solution, the organic solvent type, and the like so that the coating solution can be dried in the above-described time, deterioration in smoothness due to aggregation can be suppressed even when a coating solution that is easily agglomerated is used.

The amount of the organic solvent contained in the release layer after passing through the initial drying step is preferably 5% by mass or less, and more preferably 2% by mass or less. When the amount of the organic solvent is 5% by mass or less, even when heated in the heating step, deterioration in appearance due to dolby or the like can be prevented, which is preferable. The amount of the organic solvent in the release layer can be measured by sampling the film after the initial drying step and measuring by gas chromatography or thermogravimetric analysis, but it is also possible to estimate using a simulation of drying. The one obtained from the simulation is preferable because it can be measured without stopping the process. The simulation is not particularly limited, but existing simulation software can be used.

(Heat curing process)

It is preferable that the release film of the present invention undergoes a heat curing process after an initial drying process. The heat curing step is not particularly limited, and an existing drying furnace can be used. As for the drying furnace method, either a roll support method or a floating method may be used. The heating curing step may be a continuous step or a discontinuous step from the initial drying step, but is preferably a continuous step from the viewpoint of productivity.

The temperature of the heat curing step is preferably 80°C or more and 180°C or less, more preferably 90°C or more and 160°C or less, and most preferably 90°C or more and 140°C or less. When the temperature is 180° C. or less, the flatness of the film is maintained, and there is little possibility of causing uneven thickness of the ceramic green sheet, which is preferable. If the temperature is 140° C. or less, processing can be performed without impairing the flatness of the film, and the fear of causing the thickness unevenness of the ceramic green sheet further decreases, which is particularly preferable. When the temperature is 80° C. or higher, since curing sufficiently proceeds in the case of a thermosetting resin, it is preferable.

The time to pass through the heat curing step is preferably 2 seconds or more and 30 seconds or less, and more preferably 2 seconds or more and 20 seconds or less. When the passage time is 2 seconds or more, curing of the thermosetting resin proceeds, which is preferable. Moreover, if it is 30 seconds or less, the flatness of a film by heat does not fall, and it is preferable.

At the end of the heat curing step, the hot air temperature is preferably set to be equal to or less than the glass transition temperature of the base film, and in a flat state, the room temperature of the base film is preferably set to be equal to or less than the glass transition temperature. In the case where the base film leaves the drying furnace while the room temperature is equal to or higher than the glass transition temperature, when it comes into contact with the roll surface, slipping becomes poor, and not only scratches, etc., but also curls may occur.

It is preferable to wind up the mold release film of this invention in a roll shape after passing through a heat hardening process. It is preferable to take 2 seconds or more, and, as for the time until winding up in a roll shape after passing through a heat hardening process, 3 seconds or more are more preferable. If it is 2 seconds or more, since the release film whose temperature has risen by a heat hardening process is cooled and wound up on a roll, there is no possibility that planarity is damaged, and it is preferable.

In the release film and its manufacturing method of the present invention, various treatments may be performed between the heat curing step and the roll-shaped winding, aging treatment, antistatic treatment, corona treatment, plasma treatment, ultraviolet irradiation treatment, electron beam irradiation treatment, etc. You can do it.

(Ceramic Green Sheet and Ceramic Capacitor)

In general, a multilayer ceramic capacitor has a rectangular parallelepiped ceramic element. Inside the ceramic body, first internal electrodes and second internal electrodes are alternately provided along the thickness direction. The first internal electrode is exposed on the first end surface of the ceramic element. A first external electrode is provided on the first end face. The first internal electrode is electrically connected to the first external electrode in the first cross section. The second internal electrode is exposed on the second end face of the ceramic element. A second external electrode is provided on the second end face. The second internal electrode is electrically connected to the second external electrode in the second cross section.

The release film for manufacturing a ceramic green sheet of the present invention is used to manufacture such a multilayer ceramic capacitor. For example, it is manufactured as follows. First, the release film of the present invention is used as a carrier film, and a ceramic slurry for constituting a ceramic body is applied and dried. On the coated and dried ceramic green sheet, a conductive layer for constituting the first or second internal electrode is printed. The ceramic green sheet, the ceramic green sheet on which the conductive layer for constituting the first internal electrode is printed, and the ceramic green sheet on which the conductive layer for constituting the second internal electrode is printed are appropriately laminated and pressed to obtain a mother laminate. . The mother laminated body is divided into plural parts to produce a raw ceramic body. A ceramic body is obtained by firing the green ceramic body. After that, the multilayer ceramic capacitor can be completed by forming the first and second external electrodes.

Example

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited at all by these examples. The characteristic values used in the present invention were evaluated using the following method.

(Average surface roughness of the area (Sa), maximum protrusion height (P))

It is a value measured under the following conditions using a non-contact surface shape measurement system (manufactured by Ryoka Systems, VertScan R550H-M100). As for the area surface average roughness (Sa), the average value of 5 measurements was adopted, and the maximum protrusion height (P) was measured 7 times, and the maximum value of 5 times was used excluding the maximum value and the minimum value.

(Measuring conditions)

Measurement mode: WAVE mode

·Objective lens: 10 times

0.5×Tube lens

·Measurement area 936㎛×702㎛

(Interpretation conditions)

Face correction: 4th correction

Interpolation processing: full interpolation

Filter treatment: Gaussian cutoff value 50㎛

(Amount of release layer applied)

The applied amount of the release layer after curing of the release film of the present invention was measured using a gravimetric method. The release film was sampled at a size of 15 cm x 15 cm, and after static electricity elimination was performed using a static eliminator, the weight was measured using a precision balance (AUW120D manufactured by Shimadzu Seisakusho). The release layer of the measured release film was wiped off with methyl ethyl ketone, and after drying at 80° C. for 1 minute with a hot air dryer, the mass was again measured using a precision balance. The release layer coating amount (g/m 2) was calculated by dividing the difference in the weight of the film after wiping from the weight of the film before wiping the release layer by the film area (15 cm x 15 cm). In addition, the measurement was performed 5 times using a film sampled from another location, and the average value of 3 times was used excluding the maximum and minimum values.

(Ratio of Si element on the outermost surface of the release layer)

The ratio of the Si element on the outermost surface of the mold release layer of the mold release film of the present invention was measured by ESCA. K-Alpha ⁺ (manufactured by Thermo Fisher Scientific) was used for the device. The details of the measurement conditions are shown below. Using this apparatus, a narrow scan was performed on the five elements C, O, N, S, and Si on the surface of the release layer, and the Si element ratio (at%) was calculated from this by the following equation. In the invention, the Si element ratio is the ratio (at%) of Si in the five elements C, O, N, S, and Si.)

Si element ratio (at%) = {Si/(C+O+N+S+Si)}×100... expression

In addition, during the analysis, the background was removed by the shirley method. Moreover, the surface Si element ratio was made into the average value of the measurement results of three or more places.

·Measuring conditions

Excitation X-ray: Monochromated Al Ka ray

X-ray output: 12 kV, 6mA

Photoelectron escape angle: 90°

Spot size: 400 mm f (degree)

Pass energy: 50 eV

Step: 0.1 eV

(Surface free energy)

Water (droplet amount 1.8 μL) and diiodo on the release surface of the release film using a contact angle meter (manufactured by Kyowa Kaimen Chemical Co., Ltd.: fully automatic contact angle meter DM-701) under the conditions of 25°C and 50% RH. Droplets of methane (droplet volume 0.9 µL) and ethylene glycol (droplet volume 0.9 µL) were prepared, and the contact angle was measured. As the contact angle, the contact angle 10 seconds after dropping each liquid onto the release film was adopted. The contact angle data of water, diiodomethane, and ethylene glycol obtained by the above method were calculated using the "Kitazaki-Hatta" theory to obtain the dispersion component γsd of the surface free energy of the release film, the polar component γsp, and the hydrogen bonding component γsh, The sum of the components was taken as the surface free energy γs. This calculation was performed using the calculation software in the present contact angle meter software (FAMAS).

(Surface tension of coating solution)

The surface tension of the coating solution was measured by the Wilhelmy method using a surface tension meter (manufactured by Kyowa Gaimen Chemical Co., Ltd.: high-performance surface tension meter DY-500) under the condition of 20°C using a platinum plate. It measured 3 times and adopted the average value.

(Viscosity of coating solution)

The viscosity of the coating solution was measured under 20°C conditions using a rotary viscometer (TVB-15M, manufactured by Toki Sangyo Co., Ltd.). When measuring a low viscosity liquid of 10 mPa·s or less, measurement was performed using an optional low viscosity adapter. The measurement was performed three times and the average value was adopted.

(Evaluation of coating property of ceramic slurry)

The composition of the following material was stirred and mixed, and dispersed for 60 minutes with zirconia beads having a diameter of 0.5 mm using a bead mill to obtain a ceramic slurry.

toluene 76.3 parts by mass

ethanol 76.3 parts by mass

Barium titanate (HPBT-1 manufactured by Fuji Titanium) 35.0 parts by mass

Polyvinyl butyral 3.5 parts by mass (S-REC (registered trademark) BM-S manufactured by Sekisui Chemical)

DOP (dioctyl phthalate) 1.8 parts by mass

Subsequently, coating was applied to the release surface of the obtained release film sample so that the dried slurry became 1 µm using an applicator, and after drying at 90° C. for 1 minute, coatability was evaluated according to the following criteria.

○: It is coated on the entire surface without siding or the like.

△: There is a little sishing at the end of the coating, but it is coated almost on the entire surface.

×: There is a lot of seething, and it is not coated.

(Pin hole evaluation of ceramic green sheet)

In the same manner as in the evaluation of the coating property of the ceramic slurry, a ceramic green sheet having a thickness of 1 µm was formed on the release surface of the release film.

Subsequently, the resulting mold release film sample was applied to the mold release surface of the sample so that the dried slurry had a thickness of 1 μm using an applicator, and after drying at 90° C. for 1 minute, the mold release film was peeled to obtain a ceramic green sheet.

In the center region of the film width direction of the obtained ceramic green sheet, light was irradiated from the opposite surface of the coated surface of the ceramic slurry in the range of 25 cm 2, the state of occurrence of pinholes visible through the light was observed, and visually determined based on the following criteria.

○: No pinhole occurrence

△: almost no occurrence of pinholes

×: There are many occurrences of pinholes

(Evaluation of peelability of ceramic green sheet)

The composition of the following material was stirred and mixed, and dispersed for 60 minutes with zirconia beads having a diameter of 0.5 mm using a bead mill to obtain a ceramic slurry.

toluene 38.3 parts by mass

ethanol 38.3 parts by mass

Barium titanate (HPBT-1 manufactured by Fuji Titanium) 64.8 parts by mass

Polyvinyl butyral 6.5 parts by mass (S-REC (registered trademark) BM-S manufactured by Sekisui Chemical)

DOP (dioctyl phthalate) 3.3 parts by mass

Subsequently, the resulting mold release film sample was applied to the mold release surface of the molded release film sample so that the dried slurry had a thickness of 10 mu m using an applicator, and dried at 90 DEG C for 1 minute to form a ceramic green sheet on the mold release film. The obtained release film with a ceramic green sheet was subjected to static elimination using a static eliminator (manufactured by Keyence Corporation, SJ-F020), and then peeled off at a peeling angle of 90 degrees and a peeling rate of 10 m/min with a width of 30 mm. The stress applied at the time of peeling was measured and made into the peeling force.

(Evaluation of peeling stability of ceramic green sheet)

The evaluation of peelability was performed 10 times in the same manner as the evaluation of peelability of the ceramic green sheet described above. The unevenness of the peeling force for 10 times was evaluated according to the following criteria, and the peeling stability was evaluated.

(Circle): The difference between the maximum value and the minimum value when measured 10 times was smaller than 0.5 mN/m<2>.

(Triangle|delta): The difference between the maximum value and minimum value when measured 10 times was 0.5 mN/m<2> or more and less than 1.0 N/m<2>.

X: The difference between the maximum value and the minimum value when measured 10 times was smaller than 1.0 mN/m 2.

(Curl evaluation of release film)

The mold release film sample was cut into a size of 10 cm x 10 cm, and heat treatment was performed in a hot air oven at 100° C. for 15 minutes to prevent tension from being applied to the release film. Thereafter, after taking out from the oven and cooling to room temperature, a release film sample was placed on the glass plate so that the release surface was above, and the height of the portion floating from the glass plate was measured. At this time, the height of the largest floating part from the glass plate was taken as the measurement value. Curling property was evaluated based on the following criteria.

(Circle): The curl is 1 mm or less, and it is hardly curled.

(Triangle|delta): The curl was larger than 1 mm, and it was 2 mm or less, and curls were seen a little.

X: The curl was curled larger than 2 mm.

(Preparation of polyethylene terephthalate pellets (PET(I)))

As the esterification reaction apparatus, a continuous esterification reaction apparatus consisting of a three-stage complete mixing tank having a stirring apparatus, a condenser, a raw material input port, and a product discharge port was used. TPA (terephthalic acid) is 2 tons/hour, EG (ethylene glycol) is 2 moles per 1 mole of TPA, and antimony trioxide is formed in an amount such that Sb atoms are 160 ppm relative to PET, and these slurries are esterified. It was continuously supplied to the 1st esterification reaction tube of, and was made to react at 255 degreeC with an average residence time of 4 hours at normal pressure. Subsequently, the reaction product in the first esterification reaction tube is continuously taken out of the system and supplied to the second esterification reaction tube, and distilled off from the first esterification reaction tube in the second esterification reaction tube. 8% by mass of EG to be produced is supplied to the produced PET, and in addition, an EG solution containing magnesium acetate tetrahydrate in an amount of 65 ppm of Mg atoms to the produced PET, and P for the produced PET. An EG solution containing TMPA (trimethyl phosphate) in an amount of 40 ppm of atoms was added, followed by reaction at 260°C with an average residence time of 1 hour at normal pressure. Subsequently, the reaction product from the second esterification reaction tube was continuously taken out of the system and supplied to the third esterification reaction tube, and averaged at a pressure of 39 MPa (400 kg/cm2) using a high-pressure disperser (manufactured by Nippon Seiki). 0.2% by mass of porous colloidal silica having an average particle diameter of 0.9 μm subjected to dispersion treatment of 5 passes of the number of treatments, and 0.4% by mass of synthetic calcium carbonate having an average particle diameter of 0.6 μm obtained by adhering 1% by mass of an ammonium salt of polyacrylic acid per calcium carbonate The reaction was carried out at 260°C for an average residence time of 0.5 hours at normal pressure while adding each as a 10% EG slurry. The esterification reaction product produced in the third esterification reaction tube is continuously supplied to a three-stage continuous polycondensation reactor for polycondensation, and a 95% cut diameter of 20 μm stainless steel fiber is filtered through a sintered filter. After performing ultrafiltration, it was extruded in water, cut into chips after cooling, and obtained PET chips having an intrinsic viscosity of 0.60 dl/g (hereinafter, abbreviated as PET(I)). The lubricant content in the PET chip was 0.6% by mass.

(Preparation of polyethylene terephthalate pellets (PET(II)))

Meanwhile, in the manufacture of the PET chip, a PET chip having an intrinsic viscosity of 0.62 dl/g containing no particles such as calcium carbonate or silica was obtained (hereinafter, abbreviated as PET(II)).

(Preparation of polyethylene terephthalate pellets (PET(III)))

PET(I) is similar to PET(I), except that the type and content of the particles of PET(I) are changed to 0.75% by mass of synthetic calcium carbonate having an average particle diameter of 0.9 μm in which an ammonium salt of polyacrylic acid is adhered at 1% by mass per calcium carbonate. A chip was obtained (hereinafter, abbreviated as PET(III)). The lubricant content in the PET chip was 0.75% by mass.

(Production of laminated film X1)

After drying these PET chips, they were melted at 285°C, melted at 290°C by a separate melt extruder, and a filter in which stainless steel fibers having a 95% cut diameter of 15 μm were sintered, and a 95% cut diameter of 15 μm. Filtering in two stages of a filter obtained by sintering stainless steel particles, merged in the feed block, PET(I) as a surface layer B (anti-release side layer), and PET(II) as a surface layer A (release side layer) ), extruded (casting) into a sheet at a speed of 45 m/min, electrostatically adhered and cooled on a casting drum at 30°C by an electrostatic bonding method, and undrawn polyethylene having an intrinsic viscosity of 0.59 dl/g A terephthalate sheet was obtained. The layer ratio was adjusted to be PET(I)/PET(II)=60%/40% by calculating the discharge amount of each extruder. Next, after heating this unstretched sheet with an infrared heater, it stretched 3.5 times in the longitudinal direction by the speed difference between rolls at a roll temperature of 80 degreeC. Thereafter, it was guided by a tenter, and stretching was performed 4.2 times in the transverse direction at 140°C. Subsequently, heat treatment was performed at 210°C in the heat setting zone. Thereafter, a relaxation treatment of 2.3% was performed at 170°C in the transverse direction to obtain a biaxially stretched polyethylene terephthalate film X1 having a thickness of 31 μm. Sa of the surface layer A of the obtained film X1 was 2 nm, and Sa of the surface layer B was 28 nm.

(Production of laminated film X2)

The thickness was adjusted by changing the speed at the time of casting without changing the layer structure and the stretching conditions similar to those of the laminated film X1 to obtain a biaxially stretched polyethylene terephthalate film X2 having a thickness of 25 µm. Sa of the surface layer A of the obtained film X2 was 3 nm, and Sa of the surface layer B was 29 nm.

(Laminated film X3)

As the laminated film X3, A4100 (Cosmo Shine (registered trademark), manufactured by Toyobo) having a thickness of 25 µm was used. A4100 has a configuration in which the film contains substantially no particles, and a coating layer containing particles is provided on the surface layer B side by in-line coating. Sa of the surface layer A of the laminated film X3 was 1 nm, and Sa of the surface layer B was 2 nm.

(Laminated Film X4)

As the laminated film X4, E5101 (Toyobo Ester (registered trademark) film, manufactured by Toyobo Corporation) having a thickness of 25 µm was used. E5101 has a structure in which particles are contained in the surface layers A and B of the film. Sa of the surface layer A of the laminated film X4 was 24 nm, and Sa of the surface layer B was 24 nm.

(Production of laminated film X5)

PET(III) was laminated so that the surface layer B (half-release side layer) and PET(II) became the surface layer A (release side layer), and the layer ratio was calculated by calculating the discharge amount of each extruder, PET(III)/(II)=80. A 31 µm-thick biaxially-stretched polyethylene terephthalate film X5 was obtained by the same method as that of the laminated film X1 except that it was %/20%. Sa of the surface layer A of the obtained film X5 was 2 nm, and Sa of the surface layer B was 30 nm.

(Resin Solution A) Acrylic Polyol Containing Long-chain Alkyl Group

Mix so that the ratio of 20 mol% stearyl (meth)acrylate, 40 mol% hydroxyethyl (meth)acrylate, and 40 mol% methyl (meth)acrylate, and dilute with toluene so that the solid content concentration is 40% by mass. And 0.5 mol% of azobisisobutyronitrile was added and copolymerized under a nitrogen stream to obtain a resin solution A. The weight average molecular weight of the polymer obtained at this time was 30000.

(Example 1)

After passing the coating solution 1 of the following composition on the surface layer A of the laminated film X1 and passing through a filter capable of removing 99% or more of foreign matters of 0.5 μm or more, the coating film thickness (wet amount) of 5 g/m 2 was changed using reverse gravure. It was adjusted to enter the initial drying furnace in 0.5 seconds after coating as much as possible. After drying at 100° C. for 2 seconds in an initial drying furnace, it was continuously heated at 130° C. for 7 seconds after entering the heat curing step. After the heat curing step, 8 seconds later, it was wound up in a roll shape to obtain a release film for producing an ultrathin ceramic green sheet. Table 1 shows the results of measuring the film thickness, surface roughness, surface free energy, curl, and the like of the obtained release film. Moreover, when a ceramic slurry was applied to the obtained mold release film and the coatability, peelability, and pinhole were evaluated, favorable evaluation results were obtained.

(Paint 1) 1.0 mass% of solid content, surface tension: 27 mN/m, viscosity 5 mPa·s

Methyl ethyl ketone 57.93 parts by mass

toluene 40.00 parts by mass

Resin solution A 1.75 parts by mass (Acrylic polyol containing long-chain alkyl group, solid content 40%)

Crosslinking agent 0.25 parts by mass (Hexamethoxymethylol melamine, solid content 100%)

Silicone release agent 0.05 parts by mass (Polyether modified polydimethylsiloxane, TSF4446, solid content 100%, manufactured by Momentive)

Acid catalyst (paratoluenesulfonic acid) 0.02 parts by mass

(Examples 2 to 4, Comparative Examples 1 and 7)

Except having changed the composition of coating liquid 1 so that it might become the ratio shown in Table 1, it carried out similarly to Example 1, and produced the release film for ultra-thin ceramic green sheet production. When the obtained release film was evaluated, the peeling force was good and good results were obtained for the Example containing the silicone release agent, but the peeling force was increased in Comparative Example 1 not containing the silicone release agent, so that the ceramic green sheet could be peeled from the release film. At this time, it became a result that defects such as pinholes were liable to occur. Further, Comparative Example 7 in which the amount of the silicon-based releasing agent was small and the ratio of the Si element on the surface of the releasing layer was low also deteriorated in-plane peeling uniformity.

(Examples 5 to 7, Comparative Example 2)

The resin ratio of coating solution 1 was changed as it is, as shown in Table 2, and except having changed the coating amount (solid content) of the release layer, it carried out similarly to Example 1, and produced the release film for ultra-thin layer ceramic green sheet production.

When the obtained release film was evaluated, there was no curl for the example in which the applied amount of the release layer was 0.2 g/m 2 or less, and the result was good, but for Comparative Example 2 in which the applied amount of the release layer was 0.75 g/m 2, the curl was significantly deteriorated. . Further, in Comparative Example 2, the content of the silicon-based release agent contained in the release layer was large, and the ratio of the Si element on the outermost surface of the release layer was increased, and the peeling stability tended to deteriorate.

(Example 8)

Except having changed coating liquid 1 to coating liquid 8, it carried out similarly to Example 1, and produced the release film for ultra-thin ceramic green sheet production.

(Paint 8)

Methyl ethyl ketone 57.35 parts by mass

toluene 40.00 parts by mass

Cymac (registered trademark) US270 2.33 parts by mass (Silicone-containing acrylic polyol, manufactured by Toa Kosei, 30% solid content)

Crosslinking agent 0.25 parts by mass

(Hexamethoxymethylol melamine, solid content 100%)

Silicone release agent 0.05 parts by mass (Polyether modified polydimethylsiloxane, TSF4446, solid content 100%, manufactured by Momentive)

Acid catalyst (paratoluenesulfonic acid) 0.02 parts by mass

(Example 9)

Except having changed coating solution 1 to coating solution 9, it carried out similarly to Example 1, and produced the release film for ultra-thin layer ceramic green sheet production.

(Paint 9)

Methyl ethyl ketone 58.03 parts by mass

toluene 40.00 parts by mass

Thespine 305 1.90 parts by mass (Aminoalkyd resin containing long-chain alkyl group, manufactured by Hitachi Kasei, 50% solid content)

Silicone release agent 0.05 parts by mass (Polyether modified polydimethylsiloxane, TSF4446, solid content 100%, manufactured by Momentive)

Acid catalyst (paratoluenesulfonic acid) 0.02 parts by mass

(Example 10)

Except having changed coating solution 1 to coating solution 10, it carried out similarly to Example 1, and produced the release film for ultra-thin ceramic green sheet production.

(Paint 10)

Methyl ethyl ketone 57.55 parts by mass

toluene 40.00 parts by mass

Thespine 322 2.38 parts by mass (Aminoacrylic resin containing long-chain alkyl group, manufactured by Hitachi Kasei, solid content 40%)

Silicone release agent 0.05 parts by mass (Polyether modified polydimethylsiloxane, TSF4446, solid content 100%, manufactured by Momentive)

Acid catalyst (paratoluenesulfonic acid) 0.02 parts by mass

(Example 11)

A release film for ultra-thin ceramic green sheet production was prepared in the same manner as in Example 1, except for using the coating solution 11 in which the resin solution A of coating solution 1 was changed to 6AN-5000 (acrylic resin containing no long-chain alkyl group) of coating solution 10. .

(Paint 11)

Methyl ethyl ketone 57.93 parts by mass

toluene 40.00 parts by mass

6AN-5000 1.75 parts by mass (Acrylic polyol, manufactured by Daisei Fine Chemical, 40% solid content)

Crosslinking agent 0.25 parts by mass (Hexamethoxymethylol melamine, solid content 100%)

Silicone release agent 0.05 parts by mass (Polyether modified polydimethylsiloxane, TSF4446, solid content 100%, manufactured by Momentive)

Acid catalyst (paratoluenesulfonic acid) 0.02 parts by mass

(Example 12)

Except having changed coating solution 1 to coating solution 12, it carried out similarly to Example 1, and produced the release film for ultra-thin ceramic green sheet production.

(Paint 12)

Methyl ethyl ketone 58.95 parts by mass

toluene 40.00 parts by mass

Hexamethoxymethylol melamine 0.95 parts by mass (100% solid content)

Silicone release agent 0.05 parts by mass (Polyether modified polydimethylsiloxane, TSF4446, solid content 100%, manufactured by Momentive Performance Materials)

Acid catalyst (paratoluenesulfonic acid) 0.05 parts by mass

Even if the binder component was changed as in Examples 8 to 12, good results were obtained. Even if a resin containing a long-chain alkyl group or a silicone skeleton in the binder component was processed under the same conditions, the surface protrusion tended to be lower.

(Example 13)

Except having changed coating solution 1 to coating solution 13, it carried out similarly to Example 1, and produced the release film for ultra-thin ceramic green sheet production.

(Paint 13)

Methyl ethyl ketone 57.78 parts by mass

toluene 40.00 parts by mass

Resin solution A 1.75 parts by mass (Acrylic polyol containing long-chain alkyl group, solid content 40%)

Crosslinking agent 0.25 parts by mass (Hexamethoxymethylol melamine, solid content 100%)

Silicone release agent 0.08 parts by mass (Polyester-modified polydimethylsiloxane, BYK-310, solid content 25%, manufactured by Vicchemy Japan)

Acid catalyst (paratoluenesulfonic acid) 0.02 parts by mass

(Example 14)

Except having changed coating solution 1 to coating solution 14, it carried out similarly to Example 1, and produced the release film for ultra-thin ceramic green sheet production.

(Paint 14)

Methyl ethyl ketone 57.93 parts by mass

toluene 40.00 parts by mass

Resin solution A 1.75 parts by mass (Acrylic polyol containing long-chain alkyl group, solid content 40%)

Crosslinking agent 0.25 parts by mass (Hexamethoxymethylol melamine, solid content 100%)

Silicone release agent 0.02 parts by mass (Carboxyl-modified polydimethylsiloxane, X22-3710, solid content 100%, manufactured by Shin-Etsu Chemical Co., Ltd.)

Acid catalyst (paratoluenesulfonic acid) 0.02 parts by mass

(Example 15)

Except having changed coating solution 1 to coating solution 15, it carried out similarly to Example 1, and produced the release film for ultra-thin ceramic green sheet production.

(Paint 15)

Methyl ethyl ketone 57.78 parts by mass

toluene 40.00 parts by mass

Resin solution A 1.75 parts by mass (Acrylic polyol containing long-chain alkyl group, solid content 40%)

Crosslinking agent 0.25 parts by mass (Hexamethoxymethylol melamine, solid content 100%)

Silicone release agent 0.08 parts by mass (Polydimethylsiloxane containing polyester-modified hydroxyl group, BYK-370, solid content 25%, manufactured by Big Chemie Japan)

Acid catalyst (paratoluenesulfonic acid) 0.02 parts by mass

In Examples 13 to 15 in which the type of silicone release agent was changed, good evaluation results were obtained, but the one containing no hydroxyl group reacting with the crosslinking agent (melamine in this example) was the best in the release layer under the same conditions. There was a tendency for the peelability to improve due to the high proportion of the Si element on the surface.

(Examples 16 to 18, Comparative Example 3)

Except having changed the base film of Example 1 to the base film of Table 1, it carried out similarly to Example 1, and produced the release film for ultra-thin ceramic green sheet production.

When the obtained release film was evaluated, in Examples 1 to 15 and 16 to 18 using X1, X2, X3, and X5 which did not contain particles in the surface layer A of the base film, Sa and P on the surface of the release layer were low and pinhole evaluation. Compared to what was good, in Comparative Example 3, where X4 containing particles was used in the surface layer A of the base film, and the amount of application of the release layer was relatively small, in Comparative Example 3, both Sa and P on the surface of the release layer were high, and the pinhole evaluation was deteriorated. It was the result.

(Examples 19 to 22, Comparative Examples 4 and 5)

Regarding the manufacturing conditions of Example 1, an ultrathin layer ceramic was carried out in the same manner as in Example 1 except that the time from application to entering the initial drying furnace, or the temperature and passage time of the initial drying furnace were changed to the conditions described in Table 2. A release film for manufacturing a green sheet was prepared.

(Comparative Example 6)

Except having changed the manufacturing conditions of Example 11 to the conditions shown in Table 1, it carried out similarly to Example 11, and produced the release film for ultra-thin ceramic green sheet manufacturing.

(Comparative Example 8)

Except having changed the content of the silicone-based release agent to the one shown in Table 1, a release film for producing an ultrathin layer ceramic green sheet was produced in the same manner as in Comparative Example 4.

When the obtained film was evaluated, in the example in which the time until entering the initial drying furnace after application was 1.5 seconds or less, and the passing time through the initial drying furnace was 1.0 seconds or more and 3.0 seconds or less, the surface roughness (Sa) of the surface of the release layer or While the maximum protrusion height (P) was low and the pinhole evaluation was good, in the comparative example except for the above conditions, aggregation of the release layer was observed, resulting in an increase in the surface roughness (Sa) and the maximum protrusion height (P) of the release layer. . In addition, in Comparative Examples 4 and 8 in which the passing time of the initial drying step was shortened, precipitation of the silicon-based releasing agent on the surface of the releasing layer was small, and the proportion of the Si element on the outermost surface of the releasing layer tended to decrease. In particular, in Comparative Example 8, the ratio of the Si element on the outermost surface of the release layer was lowered, resulting in deterioration of the peel stability.

[Table 1]

[Table 2]

[Table 3]

Industrial applicability

According to the present invention, as a release layer of a release film for producing a ceramic green sheet, by curing a composition containing at least a binder component and a silicone release agent, deterioration of surface roughness due to agglomeration during drying of the component is suppressed. It has become possible to provide a release film that has smoothness and is excellent in peelability. According to the present invention, even in the production of an ultra-thin ceramic green sheet having a thickness of 0.2 to 1.0 µm, peelability is good, and defects such as pinholes of the ceramic green sheet can be reduced.

Claims (6)

A polyester film is used as a substrate, the substrate has a surface layer A that does not contain substantially particles on at least one side, and is directly on the surface of the surface layer A on at least one side or through another layer. As a release film in which a release layer is laminated, the release layer is formed by curing a composition containing a binder component and a silicone release agent, and the Si element ratio on the surface of the release layer is 2.0 at% or more and 10.0 at% or less. A release film for manufacturing a ceramic green sheet having a maximum protrusion height (P) of 50 nm or less and a region average roughness (Sa) of 1.5 nm or less. The method of claim 1,
A release film for producing a ceramic green sheet, wherein the silicone release agent is a silicone resin having a polyether moiety or a carboxyl group. The method according to claim 1 or 2,
A release film for producing a ceramic green sheet in which a component derived from a silicone release agent is contained in a release layer of 1 to 15 mg/m 2. The method according to any one of claims 1 to 3,
A release film for producing a ceramic green sheet, wherein the binder component includes a resin having a long-chain alkyl group and/or a silicone skeleton. A method for manufacturing a ceramic green sheet in which a ceramic green sheet is formed using the release film for manufacturing a ceramic green sheet according to any one of claims 1 to 4, wherein the formed ceramic green sheet has a thickness of 0.2 µm to 1.0 µm. Method of manufacturing a ceramic green sheet having. A method of manufacturing a ceramic capacitor employing the method of manufacturing a ceramic green sheet according to claim 5.