WO2020261910A1

WO2020261910A1 - Release film for manufacturing ceramic green sheet

Info

Publication number: WO2020261910A1
Application number: PCT/JP2020/021988
Authority: WO
Inventors: 健斗重野; 悠介柴田; 充晴中谷
Original assignee: 東洋紡株式会社
Priority date: 2019-06-28
Filing date: 2020-06-03
Publication date: 2020-12-30
Also published as: JP7318693B2; KR20220031910A; TW202108378A; JP7318695B2; JP2022028771A; JP2022031701A; JP2022016503A; JP2022016504A; CN117325533A; JP7318694B2; JPWO2020261910A1; JP7385817B2; JP7095741B2; CN114025960A

Abstract

[Problem] To provide a release film for manufacturing a ceramic green sheet, with which it is possible to release even a super-thin ceramic green sheet having a thickness of 1 μm or less using low and uniform force, and with which there is no risk of defects caused by foreign matter adhered to the film by electrification. [Solution] A release film for manufacturing a ceramic green sheet, said release film being obtained by laminating a release layer directly upon a surface layer A or with another layer interposed therebetween, with a polyester film serving as a substrate, a layer formed on one surface of the substrate serving as the surface layer A, and a layer formed on the other surface of the substrate serving as a surface layer B, wherein the release layer and the surface layer B are brought into contact and held for 48 hours under a pressure of 10 kPa in an atmosphere of 50°C, after which the charge amount of the release layer when the release layer and the surface layer B are separated is ±5 kV or less.

Description

Release film for manufacturing ceramic green sheets

The present invention relates to a release film for manufacturing a ceramic green sheet, and more specifically, it is possible to suppress the occurrence of process defects such as flatness defects and peeling defects during the production of an ultrathin layer ceramic green sheet, and the release film is low. The present invention relates to an ultra-thin layer ceramic green sheet production release film capable of reducing the adhesion of foreign matter to the release film and suppressing the mixing of foreign matter into the ceramic green sheet by setting the amount of charge.

Conventionally, a release film using a polyester film as a base material and a release layer laminated on it is used for molding ceramic green sheets such as multilayer ceramic capacitors and ceramic substrates. In recent years, with the miniaturization and large capacity of multilayer ceramic capacitors, the thickness of the ceramic green sheet tends to be reduced. The ceramic green sheet is molded by applying a slurry containing a ceramic component such as barium titanate and a binder resin to a release film and drying it. A laminated ceramic capacitor is manufactured by printing an electrode on a molded ceramic green sheet, peeling it from a release film, laminating and pressing the ceramic green sheet, firing, and applying an external electrode. When a ceramic green sheet is molded on the surface of the release layer of a polyester film, there is a problem that minute protrusions on the surface of the release layer affect the molded ceramic green sheet, which tends to cause defects such as cissing and pinholes. there were. Therefore, various methods for realizing a release layer surface having excellent flatness have been developed (for example, Patent Document 1).

However, in recent years, further thinning of the ceramic green sheet has progressed, and a ceramic green sheet having a thickness of 1.0 μm or less, more specifically 0.2 μm to 1.0 μm, has been required. Therefore, the extremely slight unevenness existing on the surface of the release layer may be transferred to the molded ceramic green sheet, resulting in uneven thickness, which may lead to defects.

Therefore, in recent years, various methods for achieving smoothing of the release layer have been developed. For example, there is a method of improving the smoothness of the surface of the release layer by providing a smoothing layer between the release layer and the base material to fill the unevenness generated by the particles contained in the base material (for example, Patent Document 2). .. Further, it has been proposed to improve the smoothness of the surface of the release layer by making the surface of the base material on the side where the release layer is provided a layer that does not substantially contain particles (for example, Patent Document 3).

However, in the methods of Patent Documents 2 and 3, there is a problem that the release film becomes easily charged because the release layer becomes smooth. More specifically, when the film is wound into a roll, the contact area between the release layer and the surface (back surface) on the opposite side becomes large, so that the film may be tightened or vibrated during transportation. , The surface (back surface) opposite to the release layer was rubbed against each other, and tended to be more easily charged. When the release film is charged, extremely small environmental foreign substances in the process and film debris generated at the time of slitting tend to adhere to the ceramic green sheet due to static electricity, which may lead to defects.

As a method of suppressing the charge of the release film, a method of incorporating an antistatic agent in the release layer, an antistatic coating layer on the surface opposite to the release layer or an intermediate layer between the release layer and the base film (For example, Patent Documents 4 and 5). However, when an antistatic agent is contained in the release layer as in Patent Document 4, the antistatic agent having poor compatibility with the release component may aggregate to form coarse protrusions. Also. The surface properties and curability were adversely affected, and the peelability of the ultrathin ceramic green sheet was likely to be insufficient. Further, when an antistatic layer is provided on the surface opposite to the release layer or the intermediate layer between the release layer and the base film as in Patent Document 5, the number of processing steps is increased, and an antistatic agent is generally used. Since it is expensive, the cost is increased and there is a big economic problem.

Japanese Unexamined Patent Publication No. 2000-117899 JP-A-2009-208236 Japanese Unexamined Patent Publication No. 2015-033811 Japanese Unexamined Patent Publication No. 2014-189007 International Publication No. 2016/133092

The present invention has been made against the background of the problems of the prior art. That is, while maintaining high smoothness of the release layer surface of the release film, the release force is low and uniform, the charge amount of the release film is low, and there are few defects even in an ultrathin layer product having a thickness of 1 μm or less. It is an object of the present invention to provide a release film for producing a ceramic green sheet capable of molding a ceramic green sheet.

As a result of diligent studies to solve the above problems, the present inventors have used a polyester film and have a composition containing a specific release agent and a melamine-based compound directly on the surface layer A of the polyester film or via another layer. It has been found that by providing a release layer obtained by curing an object, it is possible to provide a release film for producing a ceramic green sheet, which is excellent in smoothness and peelability of the ceramic green sheet and has a small amount of charge.

That is, the present invention has the following configuration.
1. 1. When a layer using a polyester film as a base material and forming one surface of the base material is used as a surface layer A and a layer forming the other surface is used as a surface layer B, the layer directly on the surface layer A Alternatively, it is a release film in which a release layer is laminated via another layer, and the release layer and the surface layer B are brought into contact with each other and held in an atmosphere of 50 ° C. under a pressure of 10 kPa for 48 hours. A release film for producing a ceramic green sheet in which the charge amount of the release layer when the release layer and the surface layer B are peeled off is ± 5 kV or less.
2. 2. The release film for producing a ceramic green sheet according to the first aspect, wherein the static friction coefficient μs when the release layer and the surface layer B are superposed is less than 0.30.
3. 3. The ceramic green sheet for producing the first or second above, wherein the antistatic layer is not provided on the surfaces of the surface layer A and the surface layer B, and the surface layer A and the surface layer B do not contain an antistatic agent. Release film.
4. The release layer is formed by curing a composition containing at least a release agent and a melamine compound, and the release layer forming composition does not contain an antioxidant and the melamine compound. The weight average degree of polymerization of the first is 1.7 or less, and the content of the melamine compound in the release layer is 80% by mass or more with respect to the solid content of the release layer forming composition. The release film for manufacturing a ceramic green sheet according to any one of the third.
5. The release film for producing a ceramic green sheet according to any one of the above 1 to 4, wherein the release agent contained in the release layer forming composition is a polyorganosiloxane containing a carboxyl group.
6. The release film for producing a ceramic green sheet according to any one of the first to fifth above, wherein the surface layer A does not substantially contain inorganic particles.
7. The first to sixth surfaces, wherein the surface layer B contains particles, at least a part of the particles are silica particles and / or calcium carbonate particles, and the total content of the particles with respect to the mass of the surface layer B is 5000 to 15000 ppm. A release film for manufacturing a ceramic green sheet according to any one of.
8. A method for producing a ceramic green sheet by molding a ceramic green sheet using the release film for producing a ceramic green sheet according to any one of the above 1 to 7, wherein the molded ceramic green sheet is 0.2 μm or more. A method for producing a ceramic green sheet having a thickness of 1.0 μm.
9. A method for manufacturing a ceramic capacitor, which employs the method for manufacturing a ceramic green sheet according to the eighth item.

The release film for manufacturing an ultra-thin ceramic green sheet of the present invention has a small amount of charge, the surface of the release layer is smooth, and the ceramic green sheet has excellent peelability. Therefore, foreign matter is mixed into the ceramic green sheet. And the occurrence of defects can be suppressed, and an ultrathin layer ceramic green sheet having a thickness of 0.2 to 1.0 μm can be efficiently produced.

Hereinafter, the present invention will be described in detail.

In the release film for producing a ceramic green sheet of the present invention, the release layer is laminated on the surface layer A of the polyester film as a base material directly or via another layer, and the surface layer A and the surface layer A are different from each other. It is preferable that the surface layer B on the opposite side is not provided with an antistatic layer. The release layer is preferably formed by curing a composition containing at least a melamine compound and polyorganosiloxane without containing an antistatic agent.

The release film for producing a ceramic green sheet of the present invention preferably has a release layer that is difficult to be charged. More specifically, in the release film manufacturing process, when the film is wound up after the release layer processing and stored in a roll shape, the charge increasing with time may become a problem. For example, when the amount of charge of the roll-shaped film is large, in the slitting process and the ceramic green sheet molding process, extremely minute environmental foreign substances in the process and film debris generated at the time of slitting tend to adhere to the film. A release film having a release layer that is difficult to be charged is preferable because these foreign substances adhering to the film may be mixed into the ceramic green sheet, which may lead to defects.

As an example of evaluating the difficulty of charging, it can be confirmed by evaluating the amount of charge of the release layer after the release layer and the surface layer B are brought into contact with each other and held for a certain period of time under a load. In this evaluation method, it is possible to modelly evaluate the amount of charge that increases with time when the film is stored in a roll shape. The detailed evaluation method will be described later.

The charge amount of the release layer measured by the evaluation method described later is preferably ± 5 kV or less, for example, ± 3.4 or less, more preferably ± 3 kV or less, and the smaller the absolute value, the more preferable. .. It is preferable that the charge amount of the release layer is ± 5 kV or less because the increase in the charge amount with time when the film is stored in a roll form is small and foreign matter is hard to adhere to the film. The smaller the charge amount of the release layer is, the more preferable it is, but it may be 0.1 kV or more, or 0.3 kV or more.

In the present invention, the antistatic agent is intended to impart conductivity to an ionic conductive polymer compound, a π-electron conjugated polymer compound, a conductive filler, a metal layer, a metal oxide layer, and the like. Means the substance used. Examples of the ionic conductive polymer compound include an ammonium group-containing compound, a polyether compound, a sulfonic acid compound, and a betaine compound. Examples thereof include π-electron conjugated polymer compounds polyacetylene, polyphenylene, polyaniline, polypyrrole, polyisotianaften, polythiophene and the like. Conductive fillers include metals such as gold, silver, copper, aluminum, nickel, titanium, iron, zinc, tin, fillers and fibers of these alloys, and metal oxide fillers (silica, titania, etc., exclusively slippery). (Excluding those used for purposes other than conductivity), metal-coated synthetic fibers, conductive carbon fibers such as carbon nanotubes, and the like. Further, in the present invention, the antistatic layer means a layer containing the above-mentioned antistatic agent and exerting an antistatic effect.

(Polyester film)
The polyester constituting the polyester film used as the base material in the present invention is not particularly limited, and a film-molded polyester usually generally used as a base material for a release film can be used, but preferably. It is preferable to use a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component, for example, polyethylene terephthalate, polyethylene − 2,6 − naphthalate, polybutylene terephthalate, polytrimethylene terephthalate. Alternatively, a copolymer containing the constituent components of these resins as a main component is more preferable, and a polyester film formed from polyethylene terephthalate is particularly preferable. The repeating unit of ethylene terephthalate is preferably 90 mol% or more, more preferably 95 mol% or more, and other dicarboxylic acid components and diol components may be copolymerized in a small amount, but from the viewpoint of cost. , Preferably made only from terephthalic acid and ethylene glycol. Further, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, crystallization agents and the like may be added as long as the effects of the film of the present invention are not impaired. The polyester film is preferably a biaxially oriented polyester film because of its high bidirectional elastic modulus and the like.

The intrinsic viscosity of the polyester 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 many breaks do not occur in the stretching step. On the contrary, when it is 0.70 dl / g or less, it is preferable because the cutability when cutting to a predetermined product width is good and dimensional defects do not occur. Further, it is preferable that the raw material pellets are sufficiently vacuum dried.

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 can be melted by an extruder, extruded into a film, cooled by a rotary cooling drum to obtain an unstretched film, and the unstretched film can be obtained by uniaxially or biaxially stretching. You can. The biaxially stretched film can be obtained by a method of sequentially biaxially stretching a longitudinally or laterally uniaxially stretched film in the lateral or longitudinal direction, or a method of simultaneously biaxially stretching an unstretched film in the longitudinal and horizontal directions. You can.

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

The thickness of the polyester film is preferably 12 to 50 μm, more preferably 15 to 38 μm, and even 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 possibility of deformation due to heat during film production, processing process of release layer, molding of ceramic green sheet and the like. On the other hand, when the thickness of the film is 50 μm or less, the amount of the film discarded after use does not become extremely large, which is preferable in reducing the environmental load.

The polyester film base material may be a single layer, but is preferably a multilayer of two or more layers. A mode in which a layer forming one surface of the polyester film base material is designated as a surface layer A, a layer forming the other surface is designated as a surface layer B, and a release layer is laminated on the surface layer A. Will be described below. It is preferable that the surface layer A does not substantially contain inorganic particles. On the other hand, the surface layer B preferably contains particles and the like. As for the laminated structure of the release film, if the layer to which the release layer is applied is the surface layer A, the layer on the opposite surface is the surface layer B, and the intermediate layers other than these are the layer C, the layer structure in the thickness direction is A laminated structure such as a release layer / A / B or a release layer / A / C / B can be mentioned. As a matter of course, the layer C may have a plurality of layer configurations.

The surface layer B may be a layer formed of polyester as the main constituent resin together with the surface layer A by a so-called coextrusion method, but is provided as a coating layer on the surface opposite to the surface layer A of the polyester film. It may be a thing. When the surface layer B is the coating layer, the surface layer B is preferably composed of a binder resin and particles. In this case, the surface layer B can be said to be an easy-slip coating layer.

In the polyester film base material of the present invention, it is preferable that the surface layer A forming the surface to which the release layer is applied does not substantially contain inorganic particles. At this time, the region surface average roughness (Sa) of the surface layer A is preferably 7 nm or less. When Sa is 7 nm or less, pinholes and the like are less likely to occur during molding of the ultra-thin ceramic green sheet to be laminated, which is preferable. It can be said that the smaller the region 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, when an anchor coat layer or the like described later is provided on the surface layer A, it is preferable that the coat layer does not substantially contain inorganic particles, and the region surface average roughness (Sa) after laminating the coat layer is in the above range. It is preferable to enter. In the present invention, "substantially free of inorganic particles" means a content of 50 ppm or less, preferably 10 ppm or less, and most preferably detection limit or less when the inorganic element is quantified by Keiko X-ray analysis. To do. This means that even if inorganic particles are not actively added to the film, contaminant components derived from foreign substances and stains attached to the raw material resin or the line or device in the film manufacturing process are peeled off and mixed into the film. This is because there are cases.

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 preferably contains particles from the viewpoint of the slipperiness of the film and the ease with which air can escape. It is preferable to use silica particles and / or calcium carbonate particles. The total amount of particles contained in the surface layer B is preferably 5000 to 15000 ppm. 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 in the range of 5 to 35 nm. When the total amount of silica particles and / or calcium carbonate particles is 5000 ppm or more and Sa is 1 nm or more, air can be released uniformly when the film is rolled up, and the rolled shape is good and the flatness is good. , Suitable for manufacturing ultra-thin ceramic green sheets. Further, when the total amount of silica particles and / or calcium carbonate particles is 15,000 ppm or less and Sa is 40 nm or less, the lubricant is less likely to aggregate and coarse protrusions cannot be formed, so that the quality is stable during the production of an ultrathin ceramic green sheet. It is preferable.

As the particles contained in the surface layer B, inactive inorganic particles and / or heat-resistant organic particles other than silica and / or calcium carbonate can be used. From the viewpoint of transparency and cost, it is more preferable to use silica particles and / or calcium carbonate particles, but other inorganic particles that can be used include alumina-silica composite oxide particles and hydroxyapatite particles. Examples of the heat-resistant organic particles include crosslinked polyacrylic particles, crosslinked polystyrene particles, and benzoguanamine particles. When silica particles are used, porous colloidal silica is preferable, and when calcium carbonate particles are used, light calcium carbonate surface-treated with a polyacrylic acid-based polymer compound is preferable from the viewpoint of preventing the lubricant from falling off. ..

The average particle size 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 size of the particles is 0.1 μm or more, the slipperiness of the release film is good, which is preferable. Further, when the average particle size is 2.0 μm or less, pinholes are not likely to occur in the ceramic green sheet due to the coarse particles on the surface of the release layer, which is preferable.

The surface layer B may contain two or more types of particles made of different materials. Further, particles of the same type having different average particle diameters may be contained.

When the above-mentioned easy-slip coating layer is provided as the surface layer B on the surface opposite to the surface layer A, it is preferably provided by an in-line coating that is applied during the film formation of the polyester film. Even when the easy-slip coating layer is provided, the region surface average roughness (Sa) of the surface layer B due to the easy-slip coating layer is in the range of 1 to 40 nm for the same reason as described above. Is preferable.

The film thickness of the surface layer B by the easy-slip coating layer is preferably 2 μm or less, more preferably 1 μm or less, further preferably 0.8 μm or less, and particularly preferably 0.5 μm or less. When the film thickness of the coating layer is 2 μm or less, blocking may not occur, which is preferable.

The binder resin constituting the slippery coating layer is not particularly limited, but specific examples of the polymer include polyester resin, acrylic resin, urethane resin, polyvinyl-based resin (polyvinyl alcohol, etc.), polyalkylene glycol, polyalkyleneimine, and methyl cellulose. , Hydroxycellulose, polymers and the like. Among these, it is preferable to use polyester resin, acrylic resin, or urethane resin from the viewpoint of particle retention and adhesion. Further, when considering the hardness of the easy-slip coating layer, an acrylic resin is particularly preferable. Further, as another preferable binder resin constituting the easy-slip coating layer on the polyester base film, polyester resin and urethane resin can be mentioned. The polyester resin is preferably a copolymerized polyester. The polyester resin may be modified with polyurethane. Examples of the urethane resin include polycarbonate polyurethane resin. Further, acrylic resin, polyester resin, and polyurethane resin may be used in combination, or other binder resins described above may be used in combination.

In the present invention, in order to form a crosslinked structure in the easy-slip coating layer forming the surface layer B, the easy-slip coating layer may be formed by containing a cross-linking agent. By containing a cross-linking agent, the hardness of the I Ching coating layer can be further improved. Specific examples of the cross-linking agent include urea-based, epoxy-based, melamine-based, isocyanate-based, oxazoline-based, and carbodiimide-based. In particular, oxazoline-based and carbodiimide-based cross-linking agents are particularly preferable in that the cross-linking density can be improved. Further, in order to promote the cross-linking reaction, a catalyst or the like can be appropriately used as needed.

The easy-to-slip coating layer forming the surface layer B preferably contains lubricant particles in order to impart slipperiness to the surface. The particles may be inorganic particles or organic particles, and are not particularly limited. (1) Silica, kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, Barium Sulfate, Carbon Black, Zinc Oxide, Zinc Sulfate, Zinc Carbonate, Zinc Oxide, Titanium Dioxide, Satin White, Aluminum Silate, Kaiso Soil, Calcium Sirate, Aluminum Hydroxide, Hydrate Halloysite, Calcium Carbonate, Magnesium Carbonate, Calcium Phosphate Inorganic particles such as magnesium and barium sulfate, (2) Acrylic or methacrylic, vinyl chloride, vinyl acetate, nylon, styrene / acrylic, styrene / butadiene, polystyrene / acrylic, polystyrene / isoprene, polystyrene / Organic particles such as isoprene-based, methyl methacrylate / butyl methacrylate-based, melamine-based, polycarbonate-based, urea-based, epoxy-based, urethane-based, phenol-based, diallyl phthalate-based, and polyester-based are examples, but are suitable for the coating layer. Silica is particularly preferably used to provide slipperiness.

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

The thickness ratio of the surface layer A, which is the layer on which the release layer is provided, is preferably 20% or more and 50% or less of the total thickness of the base film. If it is 20% or more, it is not easily affected by the particles contained in the surface layer B or the like from the inside of the film, and it is easy for the region surface average roughness Sa to satisfy the above range, which is preferable. When it is 50% or less of the thickness of all the layers of the base film, the ratio of the recycled raw material used in the surface layer B by coextrusion and the above-mentioned intermediate layer C can be increased, and the environmental load is reduced, which is preferable.

Further, from the viewpoint of economy, 50 to 90% by mass of film waste or recycled raw material for PET bottles can be used for the layers other than the surface layer A (surface layer B or the above-mentioned intermediate layer C). Even in this case, it is preferable that the type and amount of the lubricant contained in the surface layer B, the particle size, and the region surface average roughness (Sa) satisfy the above ranges.

Further, in order to improve the adhesion of the release layer to be applied later, a coat layer is provided on the surface of the surface layer A and / or the surface layer B on the film before or after stretching in the film forming process. It is also possible to apply corona treatment or the like.

However, it is preferable that the surface layer A and the surface layer B do not have an antistatic layer, and it is preferable that the surface layer A and the surface layer B do not contain an antistatic agent. When the intermediate layer C is provided, it is preferable that the intermediate layer C also does not contain an antistatic agent. By adopting a configuration that does not have an antistatic layer or an antistatic agent, it is possible to provide a release film having a small peeling force at low cost.

(Structure of release layer)
It is preferable that the release layer in the present invention does not contain an antistatic agent and is obtained by curing a composition containing at least a melamine compound and a polyorganosiloxane.

The release layer in the present invention preferably has a high crosslink density and a high elastic modulus in order to suppress deformation of the release layer that occurs during peeling and to make the peeling force low and uniform. Here, the elastic modulus of the release layer refers to the elastic modulus in the compression direction. Further, it is preferable to use a release layer having a high crosslink density and a high elastic modulus because an increase in the amount of charge over time when the film is stored in a roll form can be suppressed. Increasing the elastic modulus of the release layer improves the slipperiness of the surface layer B that comes into contact with the release layer during roll storage (it becomes easier to slip). When the release layer becomes slippery, the pressure applied in the direction perpendicular to the film surface easily escapes in the horizontal direction, so that the adhesion with the surface layer B when stored in a roll shape can be reduced, and charging can be performed. It is preferable because it can be suppressed.

It was also found that it is important to increase the crosslink density of the release layer in order to suppress the amount of charge. Increasing the crosslink density of the release layer facilitates electron transfer between the melamine resins existing in the release layer and makes it difficult to charge, which is preferable. In order to increase the crosslink density of the release layer, it is preferable to increase the reactivity of the melamine compound. The highly reactive melamine compound will be described in detail later.

As the melamine compound used for the release layer in the present invention, general compounds can be used and are not particularly limited, but are obtained by condensing melamine and formaldehyde, and a triazine ring, a methylol group and / or an alkoxy in one molecule. It is preferable that each has one or more methyl groups. Specifically, a compound obtained by subjecting a methylol melamine derivative obtained by condensing melamine and formaldehyde with a dehydration condensation reaction of methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol or the like as a lower alcohol to etherify is preferable. Examples of the methylolated melamine derivative include monomethylol melamine, dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, and hexamethylol melamine. One type may be used or two or more types may be used.

In order to increase the reactivity of the melamine compound and increase the elasticity of the release layer, it is preferable to use hexamethylol melamine or hexaalkoxymethyl melamine having more cross-linking points in one molecule, but the reactivity is more excellent. Hexaalkoxymethylmelamine is more preferable, and hexamethoxymethylmelamine is particularly preferable. In this, the hexamethylol melamine, is intended in the following formula (a), X is a methylol group _(-CH 2 -OH). The hexa-alkoxymethyl melamine, which was allowed to dehydration condensation reaction with an alcohol to methylol melamine derivative, X is (-CH 2 _{-OR, R} is an alkyl group having 1 to 4 carbon atoms) are those wherein. The hexamethoxymethylmelamine are those wherein X is _(-CH 2 -OMe).

The Xs in (a) above may be the same or different. Further, the above Rs may be the same or different. Further, X may be (−H).

The melamine-based compound used in the present invention is preferably not a single compound but a mixture of a plurality of compounds. From the structure of the compound that is the main component of the melamine compound, full ether type (X = -CH _2- OR, R is an alkyl group having 1 to 4 carbon atoms), methylol type (X = -CH _2- OH), It can be roughly divided into imino type (X = -H). From the viewpoint of reactivity, it is preferable to use a full ether type or a methylol type, more preferably a full ether type, and among the full ether types, hexamethoxymethylmelamine (CAS No. 3089-11-0) in which R is a methyl group is used. Most preferably used. The more the melamine-based compound having a high content of hexamethoxymethylmelamine is used, the more reactive and highly elastic the release layer can be.

The melamine compound used for the release layer in the present invention preferably has a weight average molecular weight of 250 or more and 1000 or less. More preferably, the weight average molecular weight is 300 or more and 900 or less, and further preferably 400 or more and 800 or less. When the weight average molecular weight is 1000 or less, the cross-linking reaction easily proceeds, a film having a higher cross-linking density can be formed, and a release layer having a light peeling and a low charge amount is obtained, which is preferable. When the weight average molecular weight is 250 or more, the crosslink density does not become excessively large and the curl does not deteriorate, which is preferable. The weight average molecular weight in the present specification is a standard polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method.

The weight average molecular weight of the melamine compound is 250 to 1000, which means that the melamine compound used in the present invention contains a large amount of mononuclear compounds. Since the mononuclear body has more cross-linking points and is excellent in reactivity than the polynuclear body formed by condensing two or more melamine derivatives, it can be a release layer having a high cross-linking density and excellent peelability. The higher the content of mononuclear bodies, the more preferable, and it is most preferable to use a melamine-based compound consisting of only mononuclear bodies.

The weight average molecular weight can also be expressed by the weight average degree of polymerization. The weight average degree of polymerization of the melamine-based compound used is preferably 1.7 or less, more preferably 1.5 or less, further preferably 1.3 or less, and the smaller the degree, the more preferably it can be used. .. When the weight average degree of polymerization is 1.7 or less, the content of the mononuclear compound contained in the melamine compound increases, so that the release layer has excellent reactivity, excellent peelability, and is hard to be charged. It is preferable because it can be done. The weight average degree of polymerization in the present specification is a value calculated based on the weight average molecular weight obtained by gel permeation chromatography in terms of standard polystyrene.

Melamine compounds may contain imino groups (-NH _2- ) or polynuclear compounds in the process of their synthesis. Even if these melamine derivatives are mixed, if the weight average molecular weight (that is, the weight average degree of polymerization) of the melamine compound is within the above range, the reactivity is excellent and each of them can be preferably used.

The release layer in the present invention preferably contains a melamine compound in an amount of 80% by mass or more and 99.9% by mass or less, more preferably 90% by mass or more, based on the solid content of the release layer forming composition. It is 99.9% by mass or less, more preferably 95% by mass or more and 99.9% by mass or less. By containing 80% by mass or more of the melamine compound, the release layer can obtain a high cross-linking density by self-crosslinking of the melamine compound, and the release layer has a high elastic modulus, which is preferable. At this time, the solid content of the release layer forming composition is substantially the total value of the solid content of the melamine compound and the release agent because the solvent and the acid catalyst partially evaporate during the drying process. You can consider it as.

It is preferable to add an acid catalyst to the release layer in the present invention in order to promote the cross-linking reaction of the melamine compound, and it is possible to add an acid catalyst to the release layer forming composition, apply it, and cure it. preferable. As the acid catalyst to be used, it is preferable to use a sulfonic acid-based catalyst.

As the sulfonic acid-based catalyst, for example, p-toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, trifluoromethanesulfonic acid and the like can be preferably used, but the reaction From the viewpoint of properties, p-toluenesulfonic acid can be particularly preferably used.

As the sulfonic acid-based catalyst used in the present invention, a commercially available catalyst can also be used. Examples of commercially available products include dryer (registered trademark) 900 (p-toluenesulfonic acid, manufactured by Hitachi Kasei), NACURE (registered trademark) DNNDSA series (dinonylnaphthalenedisulfonic acid, manufactured by Kusumoto Kasei), and DNNSA series (registered trademark). Dinonylnaphthalene (mono) sulfonic acid, manufactured by Kusumoto Kasei Co., Ltd.), DDBSA series (dodecylbenzene sulfonic acid, manufactured by Kusumoto Kasei Co., Ltd.), p-TSA series (p-toluenesulfonic acid, manufactured by Kusumoto Kasei Co., Ltd.), etc. Be done.

Since the sulfonic acid-based catalyst has higher acidity and excellent reactivity than other acid catalysts such as carboxylic acid-based catalysts, the release layer can be processed at a lower temperature. Therefore, it is preferable because it is possible to suppress deterioration of the flatness of the film due to heat during processing and deterioration of the rolled appearance.

The amount of the acid catalyst added is preferably 0.1 to 10% by mass with respect to the melamine compound contained in the release layer. More preferably, it is 0.5 to 8% by mass. More preferably, it is 0.5 to 5% by mass. When it is 0.1% by mass or more, the curing reaction easily proceeds, which is preferable. On the other hand, when it is 10% by mass or less, there is no possibility that the acid catalyst is transferred to the ceramic green sheet to be molded, and there is no possibility of adversely affecting it, which is preferable.

As the release agent used for the release layer (additive for improving the release property of the release layer) in the present invention, general ones can be used without particular limitation, but carboxyl group, hydroxyl group, amino group and thiol can be used. It is preferable to use a polyorganosiloxane having a functional group capable of reacting with a melamine-based compound such as a group. Among them, it is more preferable to use a polyorganosiloxane having a hydroxyl group and a carboxyl group, and it is most preferable to use a polyorganosiloxane containing a carboxyl group from the viewpoint of peelability and antistatic. Among the polyorganosiloxane structures, those having a polydimethylsiloxane structure (abbreviation, PDMS) can be preferably used.

Since the release agent polyorganosiloxane contains a carboxyl group, the release agent does not show a strong interaction with the melamine compound in the drying process, and easily orients on the surface of the release layer, resulting in good release. can get. Therefore, it is preferable to use a polyorganosiloxane containing a carboxyl group because the release property can be satisfied even if the amount of the release agent added is small. Further, it is preferable that the release layer surface is easily oriented so that the release layer surface is more slippery and less likely to be charged.

The carboxyl group may be introduced at one end of the polyorganosiloxane, or may be both ends or a side chain. Further, the number of positions to be introduced may be one or a plurality.

The carboxyl group-modified polyorganosiloxane may have a carboxyl group directly bonded to the silicon atom of the polyorganosiloxane, but a carboxyl group bonded to the polyorganosiloxane via an alkyl group or an aryl group. There may be. However, those in which a carboxyl group is bonded to polyorganosiloxane via an organic group having a repeating structure such as polyether, polyester, or polyurethane are not so preferable.

As the functional group to be introduced into the polyorganosiloxane which is a release agent, one molecule may have another functional group other than the carboxyl group, but only the carboxyl group is preferable. If a functional group other than the carboxyl group is contained, the intermolecular interaction with the melamine compound may be increased more than necessary and it may be difficult to orient the release layer on the surface, which is not preferable.

Polyorganosiloxane modified with a hydroxyl group that shows a strong interaction with the melamine compound reacts rapidly with the melamine compound in the drying process, so it is difficult to align with the release layer surface and the releasability is difficult to develop. There is. 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 releasing layer may decrease and the peeling force may increase. Further, when the amount of polyorganosiloxane added is increased, the coatability at the time of molding the ceramic green sheet may be deteriorated, which is not preferable.

The carboxyl group-containing polyorganosiloxane used in the present invention preferably has a weight average molecular weight of 40,000 or less. More preferably, it is 30,000 or less. When the weight average molecular weight is 40,000 or less, the polyorganosiloxane containing a carboxyl group is likely to segregate on the surface of the release layer, which is preferable from the viewpoint of peelability and charge amount.

As described above, the carboxyl group-containing polyorganosiloxane is more preferably a carboxyl group-containing polydimethylsiloxane. Examples of the polydimethylsiloxane containing a carboxyl group include X22-3701E (side chain carboxyl-modified polydimethylsiloxane, manufactured by Shinetsu Chemical Industry Co., Ltd.), X22-3710 (one-terminal carboxyl-modified polydimethylsiloxane, manufactured by Shinetsu Chemical Industry Co., Ltd.), and X22. -162C (both-terminal carboxyl-modified polydimethylsiloxane, manufactured by Shinetsu Chemical Industry Co., Ltd.), BY16-750 (both-terminal carboxyl-modified polydimethylsiloxane, manufactured by Toray Corning), BY16-880 (side chain carboxyl-modified polydimethylsiloxane, manufactured by Toray) Dow Corning Co., Ltd.), Magnasoft 800L (both-terminal carboxyl-modified polydimethylsiloxane, Momentive Co., Ltd.) and the like can be used.

The carboxyl group-containing polydimethylsiloxane in the present invention may be an acrylic resin in which polydimethylsiloxane is introduced into the side chain of the carboxyl group-containing acrylic main chain. As the acrylic resin in which polydimethylsiloxane is introduced into the side chain of the acrylic main chain containing a carboxyl group, Cymac (registered trademark) US-350, US-352, US-380 (all manufactured by Toagosei Co., Ltd.) and the like are used. Can be used. Further, an acrylic resin in which polydimethylsiloxane is introduced into a side chain of an acrylic main chain containing a carboxyl group and a hydroxyl group in one molecule may be used. Acrylic resins in which polydimethylsiloxane is introduced into the side chain of an acrylic main chain containing a carboxyl group and a hydroxyl group in one molecule include Cymac (registered trademark) US-450 and US-480 (all manufactured by Toagosei Co., Ltd.). ) Etc. can be used.

The release layer in the present invention preferably contains a release agent in an amount of 0.05% by mass or more and 5% by mass or less with respect to the solid content of the release layer forming composition. More preferably, it is 0.1% by mass or more and 3% by mass or less, and further preferably 0.1% by mass or more and 1% by mass or less. When it is 0.05% by mass or more, not only the peelability is improved, but also the release layer becomes slippery and it becomes difficult to be charged, which is preferable. On the other hand, when it is 5% by mass or less, the elastic modulus of the entire release layer does not decrease too much, which is preferable. Further, when it is 5% by mass or less, it is preferable from the viewpoint that the coatability at the time of molding the ceramic green sheet is not deteriorated. At this time, the solid content of the release layer forming composition is substantially the total value of the solid content of the melamine compound and the release agent because the solvent and the acid catalyst partially evaporate during the drying process. You can consider it as.

The release layer in the present invention can contain particles having a particle size of 1 μm or less, but it is preferable not to contain particles or other particles that form protrusions from the viewpoint of pinhole generation.

Other additives may be added to the release layer in the present invention as long as the effects of the present invention are not impaired, but it is preferable that the release layer does not contain an antistatic agent. It is preferable to use a release layer that does not contain an antistatic agent because the compatibility with the release agent and the melamine compound is deteriorated, and there is no possibility that agglomerates are generated and the smoothness of the release layer is impaired. Further, it is preferable because the release layer can be formed more economically.

(Other characteristics)
In the present invention, the thickness of the release layer may be set according to the purpose of use and is not particularly limited, but preferably, the weight of the release coating layer after curing is in the range of 0.01 to 1.0 μm. It is better, more preferably 0.05 to 0.8 μm, still more preferably 0.1 to 0.6 μm, and even more preferably 0.1 to 0.4 μm. When the thickness of the release layer is 0.01 μm or more, peeling performance can be obtained, which is preferable. Further, when it is 1.0 μm or less, the curing time can be shortened, the flatness of the release film can be maintained, and uneven thickness of the ceramic green sheet can be suppressed, which is preferable. Further, the smaller the thickness of the release layer, the less likely it is to be charged, which is preferable.

The release layer surface of the release film of the present invention is preferably flat so as not to cause defects in the ceramic green sheet coated and molded on the release layer surface, and the region surface average roughness (Sa) is 7 nm or less and the maximum. The protrusion height (P) is preferably 100 nm or less. Further, it is more preferable that the region surface average roughness is 5 nm or less and the maximum protrusion height is 80 nm or less.
For example, the maximum protrusion height (P) may be 45 nm or less.
When the region surface roughness is 7 nm or less and the maximum protrusion height is 100 nm or less, defects such as pinholes do not occur when the ceramic green sheet is formed, and the yield is good, which is preferable. It can be said that the smaller the region surface average roughness (Sa) is, the more preferable it is, but it may be 0.1 nm or more, or 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 may be 1 nm or more, or 3 nm or more.

As the release film of the present invention, it is preferable to use a base film in which the surface layer A is highly flattened, and even if the thickness of the release layer is thinner than 0.5 μm and further thinner than 0.2 μm, the release film is released. The surface of the mold layer can be smoothed. Therefore, even in the release layer using a highly reactive melamine compound, the generation of curl can be suppressed. In addition, the amount of solvent and resin used can be reduced, which is environmentally friendly, and a release film for molding an ultrathin layer ceramic green sheet can be produced at low cost.

The release film of the present invention preferably has a peeling force of 0.5 mN / mm or more and 2.0 mN / mm or less when peeling the ceramic green sheet. More preferably, it is 0.5 mN / mm or more and 1.5 mN / mm or less. When the peeling force is 0.5 mN / mm or more, the peeling force is not too light and there is no possibility that the ceramic green sheet will be lifted during transportation, which is preferable. When the peeling force is 2.0 mN / mm or less, the ceramic green sheet is not likely to be damaged during peeling, which is preferable. For example, even when the required thickness of the ceramic green sheet is an ultrathin product of 0.2 to 1.0 μm, the release film of the present invention can satisfactorily peel off the ceramic green sheet.

The release film of the present invention preferably has a static friction coefficient of less than 0.30 when the release layer and the surface layer B are superposed, for example, 0.25 or less and less than 0.25. Is more preferable. If the coefficient of static friction is less than 0.30, the adhesion between the release layer and the surface layer B decreases, so that the film is charged due to tightening or vibration during transportation when the film is stored in a roll shape. Is preferable because it can suppress. The smaller the coefficient of static friction is, the more the charge can be suppressed, which is preferable. However, it is preferably 0.01 or more, and more preferably 0.03 or more.

The release film of the present invention preferably has a curl of 3 mm or less, more preferably 1 mm or less, after being heated at 80 ° C. for 5 minutes without applying tension. Of course, it is also preferable not to curl at all. It is preferable that the thickness is 3 mm or less because curling is small and printing accuracy can be improved when the ceramic green sheet is molded and the electrodes are printed.

In the present invention, the method for forming the release layer is not particularly limited, and a coating liquid in which a releaseable resin is dissolved or dispersed is developed by coating or the like on one surface of a polyester film of a base material, and a solvent or the like is formed. Is removed by drying, and then heat-dried and heat-cured. At this time, the drying temperatures during solvent drying and thermosetting are preferably 100 ° C. or higher and 180 ° C. or lower, more preferably 100 ° C. or higher and 160 ° C. or lower, and 100 ° C. or higher and 140 ° C. or lower. Is most preferable. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less. When the temperature is 180 ° C. or lower, the flatness of the film is maintained and the possibility of causing uneven thickness of the ceramic green sheet is small, which is preferable. When the temperature is 140 ° C. or lower, the film can be processed without impairing the flatness of the film, and the possibility of causing uneven thickness of the ceramic green sheet is further reduced, which is particularly preferable. If it is lower than 100 ° C., the curing reaction of melamine does not proceed sufficiently and the elastic modulus of the release layer decreases, which is not preferable.

In the present invention, the coating liquid for applying the release coating layer is not particularly limited, but it is preferable to add a solvent having a boiling point of 90 ° C. or higher. By adding a solvent having a boiling point of 90 ° C. or higher, bumping during drying can be prevented, the coating film can be leveled, and the smoothness of the coating film surface after drying can be improved. The amount to be added is preferably about 10 to 80% by mass with respect to the entire coating liquid.

Any known coating method can be applied as the coating method, 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, a spray coating method, or an air knife. Conventionally known methods such as the coating method can be used.

(Ceramic green sheet and ceramic capacitor)
Generally, 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 face of the ceramic body. A first external electrode is provided on the first end face. The first internal electrode is electrically connected to the first external electrode at the first end face. 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 at the second end face.

The release film for manufacturing a ceramic green sheet of the present invention is used for manufacturing 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 forming a ceramic element is applied and dried. An ultra-thin product having a thickness of 0.2 to 1.0 μm has been required for the ceramic green sheet. A conductive layer for forming the first or second internal electrode is printed on the coated and dried ceramic green sheet. A ceramic green sheet, a ceramic green sheet on which a conductive layer for forming a first internal electrode is printed, and a ceramic green sheet on which a conductive layer for forming a second internal electrode is printed are appropriately laminated and pressed. As a result, a mother laminate is obtained. The mother laminate is divided into a plurality of pieces to prepare a raw ceramic body. A ceramic body is obtained by firing a raw ceramic body. After that, the multilayer ceramic capacitor can be completed by forming the first and second external electrodes.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The characteristic values used in the present invention were evaluated using the following method.

(Surface roughness)
It is a value measured under the following conditions using a non-contact surface shape measurement system (VertScan R550H-M100). For the region surface average roughness (Sa), the average value of 5 measurements was adopted, and for the maximum protrusion height (P), the maximum value of 5 times excluding the maximum value and the minimum value was used after measuring 7 times.
(Measurement condition)
・ Measurement mode: WAVE mode ・ Objective lens: 10x ・ 0.5 × Tube lens ・ Measurement area 936μm × 702μm
(Analysis conditions)
・ Surface correction: 4th order correction ・ Interpolation processing: Complete interpolation

(Evaluation of coating property of ceramic rally)
The slurry composition I made of the following materials was stirred and mixed for 10 minutes, and dispersed with zirconia beads having a diameter of 0.5 mm for 10 minutes using a bead mill to obtain a primary dispersion. After that, the slurry composition II composed of the following materials was added to the primary dispersion so as to have a ratio of (slurry composition I): (slurry composition II) = 3.4: 1.0, and the diameter was 0 using a bead mill. Secondary dispersion was performed with 5.5 mm zirconia beads for 10 minutes to obtain a ceramic slurry.
(Slurry Composition I)
Toluene 22.3 parts by mass Ethanol 18.3 parts by mass Barium titanate (average particle size 100 nm) 57.5 parts by mass Homogenol L-18 (manufactured by Kao Corporation) 1.9 parts by mass (slurry composition II)
Toluene 39.6 parts by mass Ethanol 39.6 parts by mass Dioctyl phthalate 3.3 parts by mass Polyvinyl butyral (Sekisui Chemical Co., Ltd. Eslek BM-S) 16.3 parts by mass
1-Ethyl-3-methylimidazolium ethyl sulfate 0.5 parts by mass Next, the release surface of the obtained release film sample was coated with an applicator so that the slurry after drying was 1.0 μm at 60 ° C. After drying for 1 minute, the coatability was evaluated according to the following criteria.
◯: There is no repellent and the entire surface can be coated.
X: Sheet defects such as repellent are observed.

(Pinhole evaluation of ceramic green sheet)
A ceramic green sheet having a thickness of 1 μm was molded on the release surface of the release film in the same manner as in the evaluation of the coatability of the ceramic slurry. Next, the release film was peeled off from the molded release film with a ceramic green sheet to obtain a ceramic green sheet. In the central region of the obtained ceramic green sheet in the film width direction, shine light from the opposite surface of the coated surface of the ceramic slurry within a range of 25 cm ² , observe the occurrence of pinholes through which light appears, and use the following criteria. It was judged visually.
◯: No pinholes occur △: Almost no pinholes occur ×: Many pinholes occur

(Evaluation of peelability of ceramic green sheet)
The slurry composition I made of the following materials was stirred and mixed for 10 minutes, and dispersed with zirconia beads having a diameter of 0.5 mm for 10 minutes using a bead mill to obtain a primary dispersion. After that, the slurry composition II composed of the following materials was added to the primary dispersion so as to have a ratio of (slurry composition I): (slurry composition II) = 3.4: 1.0, and the diameter was 0 using a bead mill. Secondary dispersion was performed with 5.5 mm zirconia beads for 10 minutes to obtain a ceramic slurry.
(Slurry Composition I)
Toluene 22.3 parts by mass Ethanol 18.3 parts by mass Barium titanate (average particle size 100 nm) 57.5 parts by mass Homogenol L-18 (manufactured by Kao Corporation) 1.9 parts by mass (slurry composition II)
Toluene 39.6 parts by mass Ethanol 39.6 parts by mass Dioctyl phthalate 3.3 parts by mass Polyvinyl butyral (Sekisui Chemical Co., Ltd. Eslek BM-S) 16.3 parts by mass
1-Ethyl-3-methylimidazolium ethyl sulfate 0.5 parts by mass

Next, the release surface of the obtained release film sample was coated with an applicator so that the dried slurry had a thickness of 1.0 μm, dried at 60 ° C. for 1 minute, and a ceramic green sheet was molded on the release film. did. After removing static electricity from the obtained release film with ceramic green sheet using an electric eliminator (Keyence, SJ-F020), a peeling tester (Kyowa Interface Science, VPA-3, load cell load 0.1N) was used. The peeling angle was 90 degrees, the peeling temperature was 25 ° C., and the peeling speed was 10 m / min. As for the direction of peeling, a double-sided adhesive tape (Nitto Denko Co., Ltd., No. 535A) is attached on the SUS plate attached to the peeling tester, and the ceramic green sheet side is bonded to the double-sided tape on the release film. Was fixed and peeled off by pulling the release film side. Among the obtained measured values, the average value of the peeling force having a peeling distance of 20 mm to 70 mm was calculated, and that value was used as the peeling force. The measurement was carried out a total of 5 times, and the value of the average value of the peeling force was adopted and evaluated. Judgment was made based on the following criteria from the obtained numerical values of peeling force.
⊚: 0.5 mN / mm or more, 1.5 mN / mm or less ○: Larger than 1.5 mN / mm, 2.0 mN / mm or less ×: Less than 0.5 mN / mm, larger than 2.0 mN / mm

(Curl evaluation of release film)
The release film sample was cut into a size of 10 cm × 10 cm, and heat-treated at 80 ° C. for 5 minutes in a hot air oven so that tension was not applied to the release film. Then, after taking out from the oven and cooling to room temperature, the release film sample was placed on the glass plate so that the release surface was facing up, and the heights of the portions floating from the glass plates at the four corners were measured. The average value of the floating amounts of the four corners measured at this time was taken as the curl amount. The curl property was evaluated according to the following criteria.
⊚: The curl was 1 mm or less and hardly curled. ◯: The curl was larger than 1 mm and 3 mm or less, and a little curl was observed.
X: The curl was larger than 3 mm, and curl was observed.

(Measuring method of weight average degree of polymerization)
Analytical conditions 16 mg of the sample was weighed and dissolved in 8 ml of chloroform. The sample solution was filtered through a 0.2 μm membrane filter, and GPC analysis of the obtained sample solution was performed under the following conditions.
Equipment: TOSOH HLC-8320GPC
Column: K-G + K-802 (exclusion limit molecular weight 5 × 10 ³ ) + K-801 (exclusion limit molecular weight 1.5 × 10 ³ ) (Shodex),
Solvent: 100% chloroform
Flow velocity: 1.0 ml / min
Concentration: 0.2%
Injection volume: 50 μL
Temperature: 40 ℃
Detector: RI

The weight average molecular weight was calculated in terms of polystyrene, and the weight average degree of polymerization was calculated based on that value. For polystyrene, PStQuick C (TOSOH) of the PStQuick series was used. Among the polystyrenes added to PStQuickC (TOSOH), polystyrenes Mw2110000, 427000, and 37900, which greatly exceed the exclusion limit molecular weight of the column, were excluded from the calibration curve preparation.

(Charging amount)
Two evaluation samples were prepared by cutting the release film into 10 cm × 10 cm. Two evaluation samples were statically removed using an electric eliminator (SJ-F020 manufactured by KEYENCE CORPORATION), and after confirming that the voltage was 0 kV, the release layer and the surface layer B were separated with the release layer facing upward. Made contact. The two contacted samples were sandwiched between medicine wrapping papers, a load of 10.2 kg (pressure 10 kPa) was applied from above, and the samples were held at 50 ° C. for 48 hours. After 48 hours, after returning the temperature to room temperature (25 ° C.), the two evaluation samples that were in contact with each other were peeled off, and the charge amount of the release layer that was in contact with the surface layer B was measured by a digital electrostatic potential measuring instrument. (KSD-1000, manufactured by Kasuga Electric Works Ltd.) was used for measurement. The amount of charge measured at this time was evaluated according to the following criteria.
⊚: Absolute value of charge amount is less than 3 kV ○: Absolute value of charge amount is 3 kV or more and 5 kV or less ×: Absolute value of charge amount exceeds 5 kV

(Static friction coefficient)
A sample film was prepared by cutting out from a release film roll into an area of 8 cm × 5 cm. This was fixed to the bottom surface of a metal rectangular parallelepiped having a size of 6 cm × 5 cm and a weight of 4.4 kg so that the surface layer B appeared on the surface. At this time, the 5 cm width direction of the sample film and the 5 cm width direction of the metal rectangular parallelepiped were aligned, one side of the sample film in the longitudinal direction was bent, and the sample film was fixed to the side surface of the metal rectangular parallelepiped with adhesive tape.

Next, a sample film was cut out from the same release film roll into an area of 20 cm × 10 cm, and the longitudinal end was fixed with adhesive tape on a flat metal plate so that the surface of the release layer was exposed. The measurement surface of the metal rectangular parallelepiped to which the sample film was attached was placed in contact with the measurement surface, and the measurement was performed under the conditions of a tensile speed of 100 mm / min, 23 ° C., and 65% RH. The measurement was performed three times, and the average value was adopted as the static friction coefficient (μs). The measurement was performed using a Tencilon universal testing machine RTG-1210 manufactured by A & D Company.

(Preparation of polyethylene terephthalate pellets (PET (I)))
As the esterification reaction device, a continuous esterification reaction device consisting of a stirrer, a splitter, a raw material charging port, and a three-stage complete mixing tank having a raw material charging port and a product outlet was used. TPA (terephthalic acid) was set to 2 tons / hour, EG (ethylene glycol) was set to 2 mol per 1 mol of TPA, antimony trioxide was set to an amount of 160 ppm of Sb atoms with respect to the PET produced, and these slurries were esterified. It was continuously supplied to the first esterification reaction can of the chemical reaction apparatus and reacted at normal pressure for an average residence time of 4 hours and 255 ° C. Next, the reaction product in the first esterification reaction can is continuously taken out of the system and supplied to the second esterification reaction can, and distilled off from the first esterification reaction can in the second esterification reaction can. EG is supplied in an amount of 8% by mass with respect to the produced PET, and an EG solution containing an amount of magnesium tetrahydrate having an amount of Mg atoms of 65 ppm with respect to the produced PET and 40 ppm of P atoms with respect to the produced PET. An EG solution containing an amount of TMPA (trimethyl phosphate) was added, and the reaction was carried out at normal pressure for an average residence time of 1 hour and 260 ° C. Next, the reaction product of the second esterification reaction can is continuously taken out of the system and supplied to the third esterification reaction can, and 39 MPa (400 kg / cm ² ) using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.). 0.2 mass% of porous colloidal silica having an average particle size of 0.9 μm and 1 mass% of ammonium salt of polyacrylic acid attached per calcium carbonate after dispersion treatment with an average number of treatments of 5 passes under the pressure of 0.4% by mass of synthetic calcium carbonate having a diameter of 0.6 μm was added as an EG slurry of 10% each, and the reaction was carried out at normal pressure for an average residence time of 0.5 hours and at 260 ° C. The esterification reaction product produced in the third esterification reaction can was continuously supplied to a three-stage continuous polycondensation reaction apparatus to carry out polycondensation, and a stainless steel fiber having a 95% cut diameter of 20 μm was sintered. After filtering with a filter, ultrafiltration was performed, the mixture was extruded into water, cooled, and then cut into chips to obtain 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)))
On the other hand, in the production of the PET (I) chip, a PET chip having an intrinsic viscosity of 0.62 dl / g containing no particles such as calcium carbonate and silica was obtained (hereinafter, abbreviated as PET (II)).

(Manufacturing of laminated film X1)
After drying these PET chips, they were melted at 285 ° C., melted at 290 ° C. by a separate melt extruder extruder, and a filter obtained by sintering stainless steel fibers having a 95% cut diameter of 15 μm and a 95% cut diameter were obtained. Two-stage filtration of a filter obtained by sintering 15 μm stainless steel particles is performed, and the filters merge in the feed block, and PET (I) is surface layer B (extrusion type surface side layer) and PET (II) is surface. It is laminated so as to be layer A (separation surface side layer), extruded (casting) into a sheet at a speed of 45 m / min, and electrostatically adhered and cooled on a casting drum at 30 ° C. by the electrostatic adhesion method. An unstretched polyethylene terephthalate sheet having an intrinsic viscosity of 0.59 dl / g was obtained. The layer ratio was adjusted so that PET (I) / (II) = 60% by mass / 40% by mass in the discharge amount calculation of each extruder. Next, the unstretched sheet was heated with an infrared heater and then stretched 3.5 times in the vertical direction at a roll temperature of 80 ° C. due to the speed difference between the rolls. Then, it was guided to a tenter and stretched 4.2 times in the lateral direction at 140 ° C. Then, in the heat fixing zone, heat treatment was performed at 210 ° C. Then, a 2.3% relaxation treatment was carried out in the transverse direction at 170 ° C. to obtain a biaxially stretched polyethylene terephthalate film X1 having a thickness of 31 μm. The Sa of the surface layer A of the obtained film X1 was 1 nm, and the Sa of the surface layer B was 28 nm.

(Manufacturing of laminated film X2)
As the laminated film X2, E5101 (Toyobo ester (registered trademark) film, manufactured by Toyobo Co., Ltd.) having a thickness of 25 μm was used. E5101 has a structure in which particles are contained in the surface layer A and the surface layer B. The Sa of the surface layer A of the laminated film X2 was 24 nm, and the Sa of the surface layer B was 24 nm.

(Manufacturing of laminated film X3)
As a film raw material polymer, PET resin pellets (PETII) having an intrinsic viscosity (solvent: phenol / tetrachloroethane = 60/40) of 0.62 dl / g and substantially free of inorganic particles are subjected to a reduced pressure of 133 Pa. , 135 ° C. for 6 hours. Then, it was supplied to an extruder, melt-extruded into a sheet at about 280 ° C., and rapidly cooled and solidified on a rotary cooled metal roll maintained at a surface temperature of 20 ° C. to obtain an unstretched PET sheet.

This unstretched PET sheet was heated to 100 ° C. with a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction with a roll group having a difference in peripheral speed to obtain a uniaxially stretched PET film.

Next, the I Ching coating liquid having the composition shown below was applied to one side of the PET film with a bar coater, and then dried at 80 ° C. for 15 seconds. The coating amount after final stretching and drying was adjusted to 0.1 μm. Subsequently, with a tenter, the film was stretched 4.0 times in the width direction at 150 ° C., and with the length of the film fixed in the width direction, heated at 230 ° C. for 0.5 seconds, and further at 230 ° C. for 10 seconds 3 The relaxation treatment in the width direction of% was carried out to obtain a laminated film X3 having a thickness of 31 μm. The laminated film X3 has a structure in which the surface layer A does not substantially contain inorganic particles and has an easy-to-slip coating layer on the surface opposite to the surface layer A. The slippery coating layer is the surface layer B. The Sa of the surface layer A was 1 nm, and the Sa of the surface layer B was 2 nm.

(Composition of I Ching coating liquid)
Water 41.86 parts by mass Isopropyl alcohol 35.00 parts by mass Acrylic polyol resin (solid content concentration 20% by mass) 16.57 parts by mass Oxazoline-based cross-linking agent (solid content concentration 25% by mass) 5.68 parts by mass Colloidal silica 0. 59 parts by mass (manufactured by Nissan Chemical Co., Ltd., trade name MP2040, average particle size 200 nm, solid content concentration 40% by mass)
Fluorine-based surfactant (solid content concentration 10% by mass) 0.30 parts by mass

(Manufacturing of the acrylic polyol resin)
77 parts by mass of methyl methacrylate (MMA), 100 parts by mass of hydroxyethyl methacrylate (HEMA), 33 parts by mass of methacrylic acid (MAA) in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube. And 490 parts by mass of isopropyl alcohol (IPA) were charged, and the temperature inside the flask was raised to 80 ° C. with stirring. The inside of the flask was maintained at 80 ° C. for 3 hours, and then 2,2-azobis-2-methyl-N-2-hydroxyethylpropionamide was added to the flask by 0.5 parts by mass. After nitrogen substitution was performed while raising the temperature in the flask to 120 ° C., the mixture was stirred at 120 ° C. for 2 hours.
Then, a reduced pressure operation of 1.5 kPa was performed at 120 ° C. to remove unreacted raw materials and solvent to obtain an acrylic polyol. The inside of the flask was returned to atmospheric pressure and cooled to room temperature, and 840 parts by mass of an IPA aqueous solution (water content 50% by mass) was added and mixed. Then, while stirring, triethylamine was added using a dropping funnel, and the acrylic polyol was neutralized until the pH of the solution was in the range of 5.5 to 7.5, and the acrylic polyol having a solid content concentration of 20% by mass was treated. Got

(Production of the above oxazoline-based cross-linking agent)
A flask equipped with a stirrer, a reflux condenser, a nitrogen introduction tube and a thermometer was charged with 460.6 parts of isopropyl alcohol and heated to 80 ° C. while gently flowing nitrogen gas. A monomer mixture consisting of 126 parts of methyl methacrylate, 210 parts of 2-isopropenyl-2-oxazoline and 84 parts of methoxypolyethylene glycol acrylate prepared in advance, and 2,2'-azobis as a polymerization initiator. An initiator solution consisting of 21 parts (2-methylbutyronitrile) (“ABN-E” manufactured by Nippon Hydrazin Industries, Ltd.) and 189 parts of isopropyl alcohol was added dropwise from a dropping funnel over 2 hours to react and then added dropwise. After the completion, the reaction was continued for 5 hours. During the reaction, nitrogen gas was continuously flowed to keep the temperature inside the flask at 80 ± 1 ° C. Then, the reaction solution was cooled to obtain a resin having an oxazoline group having a solid content concentration of 25%. The obtained resin having an oxazoline group had an oxazoline group amount of 4.3 mmol / g, and the number average molecular weight measured by GPC (gel permeation chromatography) was 20000.

(Example 1)
A coating solution was prepared by mixing a release layer formation having the following composition (described in terms of solid content, the same applies hereinafter) with a mixed solvent of methyl ethyl ketone, toluene and isopropyl alcohol. This coating liquid is applied onto the surface layer A of the laminated film X1 using reverse gravure so that the release layer thickness after drying is 0.5 μm, and dried at 130 ° C. for 15 seconds to make it ultra-thin. A release film for producing a layered ceramic green sheet was obtained. With respect to the obtained release film, the charge amount, slipperiness, surface roughness, ceramic sheet peelability, ceramic sheet coatability, curl, and pinhole of the release layer were evaluated, and good evaluation results were obtained. ..
Melamine compound 99.7 parts by mass (full ether type methylated melamine, manufactured by Sanwa Chemical Co., Ltd., trade name: Nicarac MW-30M, weight average degree of polymerization 1.3, main component is hexamethoxymethylmelamine)
Release agent 0.3 parts by mass (one-ended carboxyl-modified PDMS, manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name: X22-3710, alkyl group intervenes between dimethylsiloxane and carboxyl group)
2.0 parts by mass of p-toluenesulfonic acid

(Examples 2 and 3)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the contents of the melamine compound and the one-terminal carboxyl-modified PDMS were changed to the amounts shown in Table 1.

(Example 4)
Ultra-thin as in Example 1 except that the release agent was changed to both-terminal carboxyl-modified PDMS (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name: X22-162C, an alkyl group was interposed between dimethylsiloxane and the carboxyl group). A release film for producing a layered ceramic green sheet was obtained.

(Example 5)
The content of the melamine compound is 99.9 parts by mass, and the release agent is a carboxyl-modified PDMS at both ends (manufactured by Shinetsu Chemical Industry Co., Ltd., trade name: X22-162C, an alkyl group is interposed between dimethylsiloxane and the carboxyl group). A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the amount was changed to 1 part by mass.

(Example 6)
Ultra-thin as in Example 1 except that the release agent was changed to side chain carboxyl-modified PDMS (manufactured by Shinetsu Chemical Industry Co., Ltd., trade name: X22-3701E, alkyl group intervened between dimethylsiloxane and carboxyl group). A release film for producing a layered ceramic green sheet was obtained.

(Example 7)
A release film for manufacturing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the release agent was changed to COOH-modified copolymer acrylic silicone (manufactured by Toagosei Co., Ltd., trade name: Cymac US-352). It was.

(Example 8)
Example 1 except that the melamine compound was changed to full ether type methylated melamine (manufactured by Sanwa Chemical Co., Ltd., trade name: Nicarac MW-30, weight average degree of polymerization 1.5, main component is hexamethoxymethylmelamine). In the same manner as above, a release film for producing an ultrathin ceramic green sheet was obtained.

(Example 9)
Example 1 and Example 1 except that the melamine compound was changed to full ether type methylated melamine (manufactured by Sanwa Chemical Co., Ltd., trade name: Nicarac MW-390, weight average degree of polymerization 1.0, main component is hexamethoxymethylmelamine). In the same manner, a release film for producing an ultrathin ceramic green sheet was obtained.

(Example 10)
Except for changing to full ether type methylated melamine (weight average degree of polymerization 1.1, main component is hexamethoxymethylmelamine) obtained by recrystallizing the melamine compound (MW-30M) of Example 1 in isopropanol. , A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1.

(Examples 11 and 12)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the film thickness of the release layer was changed to the film thickness shown in Table 1.

(Example 13)
A mold release film for manufacturing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the laminated film X2 was coated on the surface layer A.

(Example 14)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the laminated film X3 was coated on the surface layer A.

(Example 15)
A mold release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 under the conditions shown in Table 1B except that one-terminal hydroxyl group-modified PDMS was used as the mold release agent. The amount of charge of the obtained release film was 3.5 kV, the coefficient of static friction was 0.28, the amount of floating was 0.7, and the ceramic sheet was easily coated. In addition, the obtained release film showed the same peeling force as the release film obtained in Example 7, and almost no pinholes were generated.

(Example 16)
A mold release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 under the conditions shown in Table 1B except that one-terminal amino group-modified PDMS was used as the mold release agent. Under the conditions shown in Table 1B, a release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1. The amount of charge of the obtained release film was 3.9 kV, the coefficient of static friction was 0.26, and the amount of floating was 0.7, and it had good ceramic sheet coatability. In addition, the obtained release film showed the same peeling force as the release film obtained in Example 7, and almost no pinholes were generated.

(Comparative Example 1)
The melamine-based compound is an imino-type melamine resin (manufactured by Sanwa Chemical Co., Ltd., trade name: Nicarax MX-730, weight average degree of polymerization 2.4) 99.5 parts by mass, and the release agent is PDMS containing a polyether-modified hydroxyl group (Big Chemie. Made by Japan, trade name: BYK-377) Manufacture of ultra-thin ceramic green sheet in the same manner as in Example 1 except that it was changed to 0.5 parts by mass and coated so that the film thickness was 1.0 μm. A release film was obtained.

(Comparative Example 2)
Ultra-thin ceramic green sheet in the same manner as in Example 1 except that the melamine compound was changed to imino-type melamine resin (manufactured by Sanwa Chemical Co., Ltd., trade name: Nicarac MX-730, weight average degree of polymerization 2.4). A release film for production was obtained.

(Comparative Example 3)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the contents of the melamine compound and the one-terminal carboxyl-modified PDMS were changed to the amounts shown in Table 1.

(Comparative Example 4)
Ultra-thin layer ceramic green sheet in the same manner as in Example 1 except that the melamine compound was changed to a methylol-type melamine resin (manufactured by Sanwa Chemical Co., Ltd., trade name: Nicarac MS-11, weight average degree of polymerization 1.8). A release film for production was obtained.

(Comparative Example 5)
Ultra-thin ceramic in the same manner as in Example 1 except that the melamine-based compound was changed to imino-methylol type melamine resin (manufactured by Sanwa Chemical Co., Ltd., trade name: Nicarac MS-001, weight average degree of polymerization 5.7). A release film for producing a green sheet was obtained.

The amount of charge of all the release films obtained in the comparative examples was outside the range of the present invention. For this reason, there was a tendency for extremely small environmental foreign substances during the process to adhere to the release film.

According to the present invention, the surface of the release layer is highly smooth, the ceramic green sheet can be peeled off uniformly and with a low force, and the release layer is hard to be charged, so that foreign matter is hard to adhere to the film, and the thickness is 1 μm. The following ultra-thin ceramic green sheets can be manufactured without substantially causing defects caused by foreign substances.

Claims

When the polyester film is used as a base material, the layer forming one surface of the base material is used as the surface layer A, and the layer forming the other surface is used as the surface layer B, the surface layer A is used. A release film in which release layers are laminated directly or via another layer, after the release layer and the surface layer B are brought into contact with each other and held for 48 hours under an atmosphere of 50 ° C. and a pressure of 10 kPa. , A release film for producing a ceramic green sheet, wherein the charge amount of the release layer when the release layer and the surface layer B are peeled off is ± 5 kV or less.
The release film for manufacturing a ceramic green sheet according to claim 1, wherein the static friction coefficient μs when the release layer and the surface layer B are overlapped is less than 0.30.
The release for ceramic green sheet production according to claim 1 or 2, wherein the antistatic layer is not provided on the surfaces of the surface layer A and the surface layer B, and the surface layer A and the surface layer B do not contain an antistatic agent. Mold film.
The release layer is formed by curing a composition containing at least a release agent and a melamine compound, and the release layer forming composition does not contain an antioxidant and the melamine compound. 1. The weight average degree of polymerization of the above is 1.7 or less, and the content of the melamine compound in the release layer is 80% by mass or more with respect to the solid content of the release layer forming composition. The release film for producing a ceramic green sheet according to any one of 3 to 3.
The release film for producing a ceramic green sheet according to any one of claims 1 to 4, wherein the release agent contained in the release layer forming composition is a polyorganosiloxane containing a carboxyl group.
The release film for producing a ceramic green sheet according to any one of claims 1 to 5, wherein the surface layer A does not substantially contain inorganic particles.
Claims 1 to 6 wherein the surface layer B contains particles, at least a part of the particles are silica particles and / or calcium carbonate particles, and the total content of the particles with respect to the mass of the surface layer B is 5000 to 15000 ppm. A release film for manufacturing a ceramic green sheet according to any one.
A method for manufacturing a ceramic green sheet using the release film for manufacturing a ceramic green sheet according to any one of claims 1 to 7, wherein the molded ceramic green sheet is 0.2 μm to 1 A method for producing a ceramic green sheet having a thickness of 0.0 μm.
A method for manufacturing a ceramic capacitor, which employs the method for manufacturing a ceramic green sheet according to claim 8.