KR102314397B1 - Release film for manufacturing ceramic green sheet - Google Patents

Abstract

[Problem] To provide an excellent release film for manufacturing a ceramic green sheet that can achieve both good winding performance and prevention of pinholes and partial thickness fluctuations, even when the ceramic green sheet is thinned. [Solutions] A polyester film substantially free of particles is used as a base material, and a release coating layer is provided on one surface of the base material, and a release coating layer containing particles is provided on the other surface, , a release film for manufacturing a ceramic green sheet having an average surface roughness (Sa) of 1 nm or more and 25 nm or less, a maximum protrusion height (P) of 60 nm or more and 500 nm or less, and an average length (RSm) of the roughness curve element of 10 µm or less of the lubricating coating layer .

Description

Release film for manufacturing ceramic green sheet

The present invention relates to a release film for manufacturing a ceramic green sheet. More specifically, it relates to a release film for manufacturing a ceramic green sheet capable of achieving both good winding properties and prevention of pinholes and partial thickness fluctuations, even when the ceramic green sheet is made into a thin film.

Conventionally, when the release film for ceramic green sheet production is stored in a wound state by relatively roughening the surface roughness of the surface (rear surface) opposite to the surface on which the release agent layer is provided, the front and back sides of the release film for ceramic green sheet production adhere A technique for solving problems such as becoming (blocking) is disclosed (for example, refer to Patent Document 1). However, since this prior art has a large protrusion, there is a problem that a pin hole or partial thickness variation occurs.

Therefore, in order to reduce the height of the projections, there is disclosed a technique for preventing the occurrence of pinholes or partial thickness variations in the ceramic green sheet by embedding the projections on the back surface with an application layer (for example, Patent Document 2) Reference). However, according to this prior art, since the protrusion height is low but the protrusion density is low, the pressure applied to the protrusion is high, and when the ceramic green sheet is further thinned, there is a problem that pinholes are generated.

Japanese Patent Laid-Open No. 2003-203822 Japanese Patent Laid-Open No. 2014-144636

This invention was made|formed against the subject of such prior art. That is, an object of the present invention is to provide an excellent release film for manufacturing a ceramic green sheet that can achieve both good winding properties and prevention of pinholes and partial thickness fluctuations, even when the ceramic green sheet is thinned.

MEANS TO SOLVE THE PROBLEM This inventor came to completion of this invention, as a result of earnestly examining in order to achieve this objective. That is, this invention includes the following structures.

1. Using a polyester film substantially free of particles as a substrate, having a release coating layer on one surface of the substrate, and a lubrication coating layer containing particles on the other surface, For producing a ceramic green sheet, characterized in that the area surface average roughness (Sa) of the coating layer is 1 nm or more and 25 nm or less, the maximum projection height (P) is 60 nm or more and 500 nm or less, and the average length (RSm) of the roughness curve element is 10 µm or less release film.

2. The release film for producing a ceramic green sheet according to the first aspect, wherein the region surface average roughness (Sa) of the release coating layer is 5 nm or less, and the maximum projection height (P) is 30 nm or less.

3. The release film for manufacturing a ceramic green sheet according to the first or second above, characterized in that the thickness of the lubricating coating layer is 0.001 µm or more and 2 µm or less.

4. A method for producing a ceramic green sheet, wherein the release film for producing a ceramic green sheet according to any one of the first to third is used.

5. The method for producing a ceramic green sheet according to the fourth aspect, wherein the thickness of the ceramic green sheet to be manufactured is 0.2 µm or more and 2 µm or less.

6. The manufacturing method of a ceramic capacitor characterized by employ|adopting the manufacturing method of the ceramic green sheet of said 4th or 5th.

ADVANTAGE OF THE INVENTION According to this invention, even when a ceramic green sheet is thinned, it becomes possible to provide the release film for ceramic green sheet manufacture which can achieve both good winding property, prevention of pinholes, partial thickness fluctuations, etc. compatible.

Hereinafter, the present invention will be described in detail.

The release film for manufacturing a ceramic green sheet of the present invention (hereinafter sometimes simply referred to as a release film) has a release coating layer on one side of a biaxially oriented polyester film, which is a base film, and a release coating layer containing particles on the other side. is a release film having

(base film)

The film preferably used as the substrate in the present invention is a film composed of a polyester resin, and mainly contains at least one selected from polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. A polyester film is preferred. Moreover, as a part of the dicarboxylic acid component or diol component of the above polyester, the film containing the polyester in which the 3rd component monomer was copolymerized may be sufficient. Among these polyester films, a polyethylene terephthalate film is the most preferable from the viewpoint of the balance between physical properties and cost.

In addition, the said polyester film may be a single layer or a multilayer may be sufficient as it. Moreover, as long as it exists in the range which exhibits the effect of this invention, each of these layers can be made to contain various additives in a polyester resin as needed. As an additive, antioxidant, a light resistance agent, antigelling agent, an organic wetting agent, an antistatic agent, a ultraviolet absorber, etc. are mentioned, for example.

(Easy coating layer)

The release film of this invention has a release coating layer on one surface of the above-mentioned polyester base film. It is preferable that the binder resin and particle|grains are contained in the lubricating coating layer at least.

(Binder resin in the lubricating coating layer)

The binder resin constituting the lubricity coating layer is not particularly limited, and specific examples of the polymer include polyester resins, acrylic resins, urethane resins, polyvinyl resins (such as polyvinyl alcohol), polyalkylene glycols, polyalkyleneimines, Methylcellulose, hydroxycellulose, starch, etc. are mentioned. Among these, it is preferable to use a polyester resin, an acrylic resin, and a urethane resin from a viewpoint of the holding|maintenance of particle|grains and adhesiveness. Moreover, when familiarity with a polyester film is considered, a polyester resin is especially preferable. In order to achieve the solubility to a solvent, dispersibility, and also adhesiveness with a base film and another layer, it is preferable that polyester of a binder is co-polyester. In addition, polyurethane-modified|denatured polyester resin may be carried out. Moreover, as another preferable binder resin which comprises the lubricity coating layer on a polyester base film, a urethane resin is mentioned. Polycarbonate polyurethane resin is mentioned as a urethane resin. Moreover, a polyester resin and a polyurethane resin may be used together and may use together said other binder resin.

(crosslinking agent)

In the present invention, in order to form a crosslinked structure in the lubricity coating layer, the lubricity coating layer may be formed so as to contain a crosslinking agent. By containing a crosslinking agent, it becomes possible to further improve the adhesiveness under high temperature, high humidity. Specific examples of the crosslinking agent include urea-based, epoxy-based, melamine-based, isocyanate-based, oxazoline-based, carbodiimide-based and the like. Moreover, in order to accelerate|stimulate a crosslinking reaction, a catalyst etc. can be used suitably as needed.

(Particles in the lubricating coating layer)

The lubricating coating layer preferably contains lubricating agent particles in order to impart slidability to the surface. The particles may be inorganic particles or organic particles, and are not particularly limited, but (1) silica, kaolinite, talc, light calcium carbonate, ground calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, carbonate Inorganic particles such as zinc, zirconium oxide, titanium dioxide, satin white, aluminum silicate, diatomaceous earth, calcium silicate, aluminum hydroxide, hydrohaloysite, calcium carbonate, magnesium carbonate, calcium phosphate, magnesium hydroxide, barium sulfate, (2) acrylic or methacrylic, vinyl chloride, vinyl acetate, nylon, styrene/acrylic, styrene/butadiene, polystyrene/acrylic, polystyrene/isoprene, polystyrene/isoprene, methyl methacrylate/butyl methacrylate, melamine, Polycarbonate-based, urea-based, epoxy-based, urethane-based, phenol-based, diallyl phthalate-based organic particles, and polyester-based organic particles can be mentioned. used

It is preferable that the average particle diameter of particle|grains is 10 nm or more, More preferably, it is 20 nm or more, More preferably, it is 30 nm or more. If the average particle diameter of the particles is 10 nm or more, it is difficult to aggregate, and sliding properties can be ensured, which is preferable.

It is preferable that the average particle diameter of particle|grains is 1000 nm or less, More preferably, it is 800 nm or less, More preferably, it is 600 nm or less. Transparency is maintained as the average particle diameter of particle|grains is 1000 nm or less, and particle|grains do not fall off, and it is preferable.

In addition, for example, mixing small particles having an average particle diameter of about 10 to 200 nm and large particles having an average particle diameter of about 300 to 1000 nm also reduces the area surface average roughness (Sa) and the maximum protrusion height (P), which will be described later. It is preferable to reduce the average length (RSm) of the roughness curve elements while maintaining it, and to achieve both slidability and smoothness, particularly preferably small particles of 30 nm or more and 150 nm or less, and large particles having an average particle diameter of 350 to 600 nm. it will be combined When mixing small particles and large particles, it is preferable that the mass content of small particles is larger than the mass content of large particles with respect to the entire solid content of the coating layer.

The method of measuring the average particle size of the particles is a method of observing the cross-section particles of the film after processing with a transmission electron microscope or a scanning electron microscope, observing 100 particles that are not agglomerated, and taking the average value as the average particle size. was done.

The shape of particle|grains will not be specifically limited if the objective of this invention is satisfied, Spherical particle|grains and non-spherical particle|grains of amorphous form can be used. The particle diameter of amorphous particle|grains can be calculated as a circle equivalent diameter. The equivalent circle diameter is a value obtained by dividing the area of the observed particle by π, calculating the square root, and doubling it.

It is preferable that the ratio with respect to the total solid of the lubricating coating layer of particle|grains is 50 mass % or less, More preferably, it is 40 mass % or less, More preferably, it is 30 mass % or less. When the ratio of the particles to the total solid content of the lubricity coating layer is 50 mass% or less, transparency is maintained and the drop-off of the particles from the lubrication coating layer does not occur remarkably, which is preferable.

It is preferable that the ratio with respect to the total solid of the lubricating coating layer of particle|grains is 1 mass % or more, More preferably, it is 1.5 mass % or more, More preferably, it is 2 mass % or more. If the ratio of the particles to the total solid content of the lubricating coating layer is 1 mass % or more, sliding property can be ensured, and it is preferable.

As a method of measuring the content rate of the particle|grains contained in an lubricating coating layer, when resin of an organic component and inorganic particle are contained in an lubricating coating layer, the following method can be used, for example. First, the lubricity coating layer provided on the processed film is extracted from the processed film using a solvent or the like, and the lubricity coating layer is taken out by drying. Next, heat is applied to the obtained lubricating coating layer, and only an inorganic component can be obtained by burning and distilling the organic component contained in the lubricating coating layer with heat. By measuring the weight of the obtained inorganic component and the lubricating coating layer before combustion distillation, the mass % of the particle|grains contained in the lubricating coating layer can be measured. At this time, it can measure with high precision by using a commercially available differential thermal and thermogravimetric simultaneous measurement apparatus.

(Additive in the lubricating coating layer)

In order to provide other functionality to a lubricating coating layer, you may make it contain various additives in the range which does not impair the coating external appearance. As said additive, a fluorescent dye, a fluorescent whitening agent, a plasticizer, a ultraviolet absorber, a pigment dispersing agent, a foam suppressing agent, an antifoamer, antiseptic|preservative etc. are mentioned, for example.

The lubricating coating layer can also contain surfactant for the purpose of improving the leveling properties at the time of application and defoaming the coating liquid. The surfactant may be any of cationic, anionic, and nonionic surfactants, but silicone-based, acetylene glycol-based, or fluorine-based surfactants are preferable. It is preferable to make the application layer contain these surfactants in the range of the grade which does not generate|occur|produce abnormality of an application|coating external appearance by adding excessively.

As a coating method, both the so-called in-line coating method, which is applied at the same time as the polyester base film is formed, and the so-called off-line coating method, in which the polyester base film is applied with a separate coater after film formation can be applied, but the inline coating method is more efficient and more preferable do.

As a method for apply|coating a coating liquid to a polyethylene terephthalate (Hereinafter, it may abbreviate as PET) film as a coating method, well-known arbitrary methods can be used. For example, reverse roll coating method, gravure coating method, kiss coating method, die coater method, roll brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, impregnation coating method, curtain coating method and the like. These methods are applied alone or in combination.

In this invention, as a method of forming a lubricating coating layer on a polyester film, the method of apply|coating and drying the coating liquid containing a solvent, particle|grains and resin to a polyester film is mentioned. Examples of the solvent include an organic solvent such as toluene, water, or a mixed system of water and a water-soluble organic solvent, preferably water alone or a so-called aqueous solvent obtained by mixing water with a water-soluble organic solvent from the viewpoint of environmental problems. do.

Although the solid content concentration of the lubricating coating liquid varies depending on the kind of binder resin, the kind of solvent, etc., it is preferable that it is 0.5 mass % or more, and it is more preferable that it is 1 mass % or more. It is preferable that solid content concentration of a coating liquid is 35 mass % or less, More preferably, it is 20 mass % or less.

The drying temperature after application also varies depending on the type of binder resin, the type of solvent, the presence or absence of a crosslinking agent, the solid content concentration, etc., but is preferably 70°C or higher, and preferably 250°C or lower.

(Production of polyester film)

In this invention, the polyester film used as a base film can be manufactured according to the manufacturing method of a general polyester film. For example, the polyester resin is melted and the unoriented polyester extruded into a sheet is stretched in the longitudinal direction at a temperature above the glass transition temperature using the speed difference of the roll, and then stretched in the transverse direction by a tenter. and a method of performing heat treatment. Moreover, the method of biaxially extending|stretching longitudinally and horizontally simultaneously in a tenter is also mentioned.

In this invention, although the polyester film used as a base film may be a uniaxially stretched film or a biaxially stretched film, it is preferable that it is a biaxially stretched film.

It is preferable that the thickness of a polyester film base material is 5 micrometers or more, More preferably, it is 10 micrometers or more, More preferably, it is 15 micrometers or more. If thickness is 5 micrometers or more, it is difficult to enter wrinkles at the time of conveyance of a film, and it is preferable.

It is preferable that the thickness of a polyester film base material is 50 micrometers or less, More preferably, it is 45 micrometers or less, More preferably, it is 40 micrometers or less. Since the cost per unit area falls that thickness is 40 micrometers or less, it is preferable.

In the case of inline coating, you may apply to the unstretched film before extending|stretching in the longitudinal direction, or you may coat to the uniaxially-stretched film before extending|stretching in the transverse direction after extending|stretching in the longitudinal direction. When coating before extending|stretching in a longitudinal direction, it is preferable to provide a drying process before roll extending|stretching. When coating to the uniaxially stretched film before extending|stretching in a lateral direction, since it can serve also as a drying process in the film heating process in a tenter, it is not necessarily necessary to provide a drying process separately. Moreover, it is the same also when carrying out simultaneous biaxial stretching.

It is preferable that the film thickness of a lubricating coating layer is 0.001 micrometer or more, More preferably, it is 0.01 micrometer or more, More preferably, it is 0.02 micrometer or more, Especially preferably, it is 0.03 micrometer or more. Since the film-forming property of a coating film is maintained as the film thickness of an application layer is 0.001 micrometer or more, and a uniform coating film is obtained, it is preferable.

It is preferable that the film thickness of a lubricating coating layer is 2 micrometers or less, More preferably, it is 1 micrometer or less, More preferably, it is 0.8 micrometer or less, Especially preferably, it is 0.5 micrometer or less. If the film thickness of the application layer is 2 µm or less, there is no fear of blocking, which is preferable.

A ceramic green sheet to be coated and molded on a release coating layer to be described later is wound up into a roll together with a release film after coating and molding. At this time, the ceramic green sheet is wound while the surface of the ceramic green sheet is in contact with the lubricating coating layer of the release film. In order not to generate defects on the surface of the ceramic green sheet, the outer surface of the lubricating coating layer (the surface of the lubricating coating layer of the entire coating film not in contact with the polyester film) must be suitably flat, and the area surface average roughness (Sa) ) is preferably 1 nm or more and 25 nm or less, and the maximum protrusion height (P) is 60 nm or more and 500 nm or less.

If the area average roughness (Sa) of the outer surface of the lubricating layer is 1 nm or more and the maximum projection height (P) is 60 nm or more, the lubricating surface does not become too smooth and moderate slidability can be maintained, which is preferable. If the area surface average roughness (Sa) is 25 nm or less and the maximum projection height (P) is 500 nm or less, it is preferable that the lubricating surface does not become too rough and defects of the ceramic green sheet due to projections do not occur.

In the present invention, in addition to making the region surface average roughness Sa and the maximum protrusion height P within the above ranges, it is preferable that the average length RSm of the roughness curve elements is 10 µm or less. By controlling the average length RSm of the roughness curve element to be 10 µm or less, the number of protrusions per unit area is increased. When the number of protrusions increases, the pressure applied per one protrusion is dispersed and small, so that generation of pinholes can be effectively suppressed, which is preferable. The average length (RSm) of the roughness curve elements is more preferably 5 µm or less, and still more preferably 3 µm or less. However, if the average length (RSm) of the roughness curve element is too small, the area surface average roughness (Sa) increases, or the maximum protrusion height (P) becomes large, in relation to the content of particles in the lubricating coating layer being too large. Since it is also related to a thing, it is preferable that it is 0.1 micrometer or more, 0.5 micrometer or more may be sufficient, and 1 micrometer or more may be sufficient.

In the present invention, in order to make the average length (RSm) of the roughness curve elements within a predetermined range, it is preferable that the average particle diameter of the particles contained in the lubricating coating layer is 1000 nm or less. More preferably, it is 800 nm or less, More preferably, it is 600 nm or less. When the particle diameter is 1000 nm or less, the distance between particles does not become too large, and RSm is preferably adjusted within a predetermined range.

(Releasable coating layer)

The resin constituting the release coating layer in the present invention is not particularly limited, and silicone resins, fluororesins, alkyd resins, various waxes, aliphatic olefins, etc. can be used, and each resin can be used alone or in combination of two or more. .

As the release coating layer of the present invention, for example, a silicone resin is a resin having a silicone structure in a molecule, and includes curable silicone, silicone graft resin, and modified silicone resin such as alkyl modification, from the viewpoint of transferability and the like. It is preferable to use a reactive cured silicone resin. As the reactive cured silicone resin, an addition-reaction-based one, a condensation-reactive-based one, or an ultraviolet or electron beam curing-based resin can be used. More preferably, those of a low-temperature curable addition reaction system capable of being processed at a low temperature, and those of an ultraviolet or electron beam curing system are good. By using these things, it can process at low temperature at the time of the coating process to a polyester film. Therefore, there is little heat damage to the polyester film during processing, and a polyester film with high planarity is obtained, and defects such as pinholes can be reduced even when manufacturing an ultra-thin ceramic green sheet having a thickness of 0.2 to 2 μm. have.

As an addition-reaction type silicone resin, polydimethylsiloxane and hydrogensiloxane which introduce|transduced the vinyl group into the terminal or side chain are made to react using a platinum catalyst, and hardening is mentioned, for example. At this time, it is more preferable to use a resin that can be cured at 120°C within 30 seconds because it can be processed at a low temperature. For example, Toray Dow Corning's low temperature addition curing type (LTC1006L, LTC1056L, LTC300B, LTC303E, LTC310, LTC314, LTC350G, LTC450A, LTC371G, LTC750A, LTC755, LTC760A, etc.) and thermal UV curing type (LTC851, BY24-510, BY24-510, etc.) 561, BY24-562, etc.), Shin-Etsu Chemical Co., Ltd. solvent addition + UV curing type (X62-5040, X62-5065, X62-5072T, KS5508, etc.), dual cure curing type (X62-2835, X62-2834, X62- 1980, etc.) and the like.

As the silicone resin of the condensation reaction system, for example, polydimethylsiloxane having an OH group at the terminal and polydimethylsiloxane having an H group at the terminal are subjected to a condensation reaction using an organotin catalyst to form a three-dimensional crosslinked structure.

As the ultraviolet curing silicone resin, for example, as the most basic type, using a radical reaction such as a normal silicone rubber crosslinking, photocuring by introducing an unsaturated group, decomposing an onium salt in ultraviolet rays to generate a strong acid, Crosslinking by cleaving an epoxy group, crosslinking by addition reaction of thiol to vinylsiloxane, etc. are mentioned. In addition, an electron beam can also be used instead of the said ultraviolet-ray. The electron beam has a stronger energy than ultraviolet rays, and in the case of ultraviolet curing, it is possible to conduct a crosslinking reaction by radicals without using an initiator. Examples of the resin to be used include UV-curable silicones manufactured by Shin-Etsu Chemical (X62-7028A/B, X62-7052, X62-7205, X62-7622, X62-7629, X62-7660, etc.), Momentive Performance UV curing silicone (TPR6502, TPR6501, TPR6500, UV9300, UV9315, XS56-A2982, UV9430, etc.) manufactured by Materials, UV curing silicone manufactured by Arakawa Chemical (silicorice UV POLY200, POLY215, POLY201, KF-) UV265AM, etc.).

As said ultraviolet curing silicone resin, acrylate-modified, glycidoxy-modified polydimethylsiloxane, etc. can also be used. Good mold release performance can be obtained also by mixing these modified polydimethylsiloxane with a polyfunctional acrylate resin, an epoxy resin, etc., and using it in the presence of an initiator.

As other examples of the resin to be used, alkyd resins, acrylic resins or methylated melamines, alkyd resins and acrylic resins obtained by reaction of stearyl-modified, lauryl-modified or the like are also suitable.

As aminoalkyd resin obtained by the reaction of said methylated melamine, etc., Tespine 303, Tespine 305, Tespine 314 manufactured by Hitachi Chemical can be mentioned. As aminoacrylic resin obtained by reaction of a methylated melamine, etc., the Hitachi Chemical Co., Ltd. Tespine 322 etc. are mentioned.

When using the said resin for the mold release coating layer of this invention, you may use by 1 type, and may mix and use 2 or more types. Moreover, in order to adjust peeling force, it is also possible to mix additives, such as a light peeling additive and a heavy peeling additive.

Although the release coating layer of the present invention may contain particles having a particle size of 1 µm or less, it is preferable not to substantially contain particles or the like that form protrusions such as particles from the viewpoint of pinhole generation.

You may add additives, such as a close_contact|adherence improving agent and an antistatic agent, to the release coating layer of this invention. Moreover, in order to improve adhesiveness with a base material, it is also preferable to perform pre-processing, such as anchor coating, corona treatment, plasma treatment, atmospheric pressure plasma treatment, on the surface of a polyester film before forming a release coating layer.

In the present invention, the thickness of the release coating layer may be set according to the intended use, and is not particularly limited, but preferably the thickness of the release coating layer after curing is within a range of 0.005 to 2 µm. If the thickness of a mold release coating layer is 0.005 micrometer or more, peeling performance is maintained and it is preferable. In addition, if the thickness of the release coating layer is 2 µm or less, the curing time does not become too long and there is no fear of occurrence of uneven thickness of the ceramic green sheet due to a decrease in the planarity of the release film, which is preferable. Further, since the curing time does not become too long, the resin constituting the release coating layer does not have a risk of aggregation and there is no fear of forming projections, which is preferable because pinhole defects of the ceramic green sheet do not easily occur.

The outer surface of the film on which the release coating layer is formed (the surface of the release coating layer of the entire coated film that is not in contact with the polyester film) is preferably flat in order not to cause defects in the ceramic green sheet to be coated and molded thereon; It is preferable that the area|region surface average roughness (Sa) is 5 nm or less, and the maximum processus|protrusion height (P) is 30 nm or less. Furthermore, 5 nm or less of area|region surface average roughness Sa, and 20 nm or less of maximum processus|protrusion height P are more preferable. Particularly preferably, the area surface average roughness Sa is 3 nm or less, and the maximum protrusion height P is 17 nm or less. When the area surface roughness Sa is 5 nm or less and the maximum protrusion height P is 30 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. Although it can be said that it is so preferable that the area|region surface average roughness Sa is small, 0.1 nm or more may be sufficient and 0.3 nm or more may be sufficient as it. Although it can be said that it is so preferable that the maximum processus|protrusion height P is also small, 1 nm or more may be sufficient and 3 nm or more may be sufficient as it.

In the present invention, in order to adjust the surface of the film on which the release coating layer is formed to a predetermined roughness range, it is preferable that the PET film contains substantially no particles. In addition, in the present invention, "substantially not containing particles" means quantitative analysis of elements derived from particles by fluorescence X-ray analysis for both the base film and the release coating layer, for example, in the case of inorganic particles. It is defined as below 50 ppm, preferably below 10 ppm, and most preferably below the detection limit. This is because, even if the particles are not actively added to the base film, contaminants derived from foreign matter or contaminants adhering to lines and devices in the raw material resin or film manufacturing process may peel off and mix in the film. .

In the present invention, the method for forming the release coating layer is not particularly limited, and a coating solution in which a resin having a release property is dissolved or dispersed is applied to one side of the polyester film of the substrate or the like, and the solvent is dried by drying. After removal, a method of heat drying, heat curing or UV curing is used. At this time, as for the drying temperature at the time of solvent drying and thermosetting, it is preferable that it is 180 degrees C or less, It is more preferable that it is 150 degrees C or less, It is most preferable that it is 120 degrees C or less. 30 second or less is preferable and, as for the heating time, 20 second or less is more preferable. In the case of 180 degrees C or less, the planarity of a film is maintained and there is little possibility of raising the thickness non-uniformity of a ceramic green sheet, and it is preferable. If it is 120 degrees C or less, it can process without impairing the flatness of a film, and since the fear of raising the thickness nonuniformity of a ceramic green sheet further falls, it is especially preferable.

In this invention, although the surface tension of the coating liquid at the time of apply|coating a mold release coating layer is not specifically limited, It is preferable that it is 30 mN/m or less. By carrying out surface tension as mentioned above, the applicability|paintability after coating improves, and the unevenness|corrugation of the coating-film surface after drying can be reduced.

In this invention, although it does not specifically limit to the coating liquid at the time of apply|coating a mold release coating layer, It is preferable to add the solvent of 90 degreeC or more of boiling points. By adding the solvent with a boiling point of 90 degreeC or more, the bump at the time of drying can be prevented, a coating film can be leveled, and the smoothness of the coating-film surface after drying can be improved. As the addition amount, it is preferable to add about 10-80 mass % with respect to the whole coating liquid.

As the coating method of the coating solution, any known coating method can be applied, and 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 , a conventionally known method such as an air knife coating method can be used.

(Ceramic Green Sheet and Ceramic Capacitor)

In general, a multilayer ceramic capacitor has a rectangular parallelepiped ceramic body. 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 body. A first external electrode is provided on the first end surface. The first internal electrode is electrically connected to the first external electrode on the first end surface. The second internal electrode is exposed on the second end surface of the ceramic body. A second external electrode is provided on the second end face. The second internal electrode is electrically connected to the second external electrode on the second end surface.

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 manufactures 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. A mother laminate is obtained by appropriately laminating and pressing a ceramic green sheet, a ceramic green sheet on which a conductive layer for constituting the first internal electrode is printed, and a ceramic green sheet on which a conductive layer for constituting the second internal electrode is printed. . The mother laminate is divided into a plurality of parts, and a green ceramic body is produced. A ceramic body is obtained by firing a raw ceramic body. Thereafter, the multilayer ceramic capacitor can be completed by forming the first and second external electrodes.

Example

Next, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to a following example of course. In addition, the evaluation method used by this invention is as follows.

(1) Surface properties of the coated film

It is a value measured under the following conditions using the non-contact surface shape measurement system (VertScan R550H-M100). The average value of the area surface average roughness (Sa) and the average length of the roughness curve element (RSm) was taken as an average value of 5 measurements, and the maximum projection height (P) was the maximum value of 5 measurements.

(Measuring conditions)

・Measurement mode: WAVE mode

·Objective lens: 50x

·0.5×Tube lens

・Measurement area 187×139㎛ (Sa, P measurement)

・Measurement length (Lr: reference length): 187㎛ (RSm measurement)

(2) Evaluation of pinhole and thickness variation of ceramic green sheet

The composition containing the following materials was stirred and mixed, and it disperse|distributed for 2 hours using the paint shaker which uses 2.0 mm of glass beads as a dispersion medium, and the ceramic slurry was obtained.

Toluene 22.5% by mass

Ethanol 22.5% by mass

50% by mass of barium titanate (HPBT-1 manufactured by Fuji Titanium)

Polyvinyl butyral (Sekisui Chemical Co., Ltd. S-Rec BH-3) 5% by mass

Then, using an applicator, apply the dried slurry to the release surface of the release film sample to a thickness of 0.5 μm, and after drying at 90° C. for 1 minute, overlap the slurry surface and the smoothing coated layer surface for 10 minutes, 1 kg/cm 2 weight After adding, the release film was peeled off to obtain a ceramic green sheet.

In the central region in the film width direction of the obtained ceramic green sheet, light was struck from the opposite surface of the coated surface of the ceramic slurry in a range of 25 cm 2 , the state of occurrence of pinholes visible through the light was observed, and visually judged according to the following criteria did.

○: No pinhole generation, no problem in thickness fluctuation

×: The occurrence of pinholes is slightly and/or the thickness fluctuation is slightly noticeable.

X X: There is little occurrence of pinholes, and the thickness fluctuation is slightly conspicuous.

× × ×: There are many occurrences of pinholes, and the thickness fluctuation is very conspicuous.

(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 device, a decompressor, a raw material inlet and a product outlet was used. TPA (terephthalic acid) is 2 tons/hour, EG (ethylene glycol) is 2 moles per 1 mole of TPA, and antimony trioxide is used in an amount such that the Sb atom is 160 ppm with respect to the produced PET, and the slurry is subjected to an esterification reaction apparatus. was continuously supplied to the first esterification reaction can of Next, the reaction product in the first esterification reaction can is continuously taken out of the system, supplied to the second esterification reaction can, and EG distilled off from the first esterification can in the second esterification reaction can is produced in PET. EG solution containing magnesium acetate tetrahydrate in an amount such that the Mg atom is 65 ppm with respect to the produced PET, and TMPA (trimethyl phosphate) in an amount of 40 ppm with respect to the produced PET. An EG solution was added, and the reaction was carried out at 260°C with an average residence time of 1 hour at atmospheric pressure. Next, the reaction product of the second esterification reaction can is continuously taken out of the system, supplied to the third esterification reaction can, and averaged at a pressure of 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 diameter of 0.9 μm after dispersing treatment for 5 passes, and 0.4 mass % of synthetic calcium carbonate having an average particle diameter of 0.6 μm in which 1 mass % of an ammonium salt of polyacrylic acid is adhered per calcium carbonate; Each was added as a 10% EG slurry, and the reaction was carried out at 260°C with an average residence time of 0.5 hours at normal pressure. The esterification reaction product produced in the third esterification reaction can is continuously supplied to a three-stage continuous polycondensation reaction unit to perform polycondensation, and is filtered through a filter obtained by sintering stainless steel fibers with a 95% cut diameter of 20 µm. after performing ultrafiltration, extruding in water, and cutting into chips after cooling 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 mass%.

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

On the other hand, in the production of the PET chip, a PET chip having an intrinsic viscosity of 0.62 dl/g not completely containing particles such as calcium carbonate and silica was obtained (hereinafter, abbreviated as PET(II)).

(Preparation of laminated film Z)

After drying these PET chips, they are melted at 285°C, melted at 290°C by a separate melt extruder, and a filter obtained by sintering stainless steel fibers having a 95% cut diameter of 15 µm, and a 95% cut diameter of 15 µm Two stages of filtration of a filter in which phosphorus stainless steel particles are sintered is performed, merged in a feed block, PET(I) is laminated so as to be a semi-release side layer, and PET(II) is a release side layer, and a sheet shape is 45 m. It was extruded (cast) at a speed of /min and electrostatically adhered and cooled on a casting drum at 30°C by an electrostatic adhesion method to obtain an unstretched polyethylene terephthalate sheet having an intrinsic viscosity of 0.59 dl/g. The layer ratio was adjusted so that it might become PET(I)/PET(II)=60%/40% by the discharge amount calculation of each extruder. Next, after heating this unstretched sheet with an infrared heater, it extended|stretched 3.5 times in the longitudinal direction by the speed difference between rolls at the roll temperature of 80 degreeC. Then, it guide|induced to a tenter, and it extended|stretched 4.2 times in the transverse direction at 140 degreeC. Then, in the heat setting zone, it heat-processed at 210 degreeC. Then, 2.3% of relaxation processing was performed at 170 degreeC in the transverse direction, and the 31-micrometer-thick biaxially stretched polyethylene terephthalate film Z was obtained. Sa of the release surface side layer of the obtained laminated|multilayer film Z was 2 nm, and Sa of the semi-release surface side layer was 28 nm.

(Polymerization of polyester resin A-1)

To a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial reflux cooler, 194.2 parts by mass of dimethyl terephthalate, 184.5 parts by mass of dimethyl isophthalate, 14.8 parts by mass of dimethyl-5-sodium sulfoisophthalate, 185.1 parts by mass of ethylene glycol , 185.1 parts by mass of neopentyl glycol and 0.2 parts by mass of tetra-n-butyl titanate were charged, and transesterification was carried out at a temperature of 160°C to 220°C for 4 hours. Then, it heated up to 255 degreeC and pressure-reduced the reaction system gradually, it was made to react under reduced pressure of 30 Pa for 1 hour and 30 minutes, and the copolymerized polyester resin (A-1) was obtained. The obtained co-polyester resin (A-1) was pale yellow and transparent. It was 0.60 dl/g when the reduced viscosity of co-polyester resin (A-1) was measured. The glass transition temperature by DSC was 65°C.

(Preparation of polyester aqueous dispersion Aw-1)

In a reactor equipped with a stirrer, a thermometer and a reflux device, 30 parts by mass of the polyester resin (A-1) and 15 parts by mass of ethylene glycol-n-butyl ether were put, and the resin was dissolved by heating and stirring at 110°C. After resin melt|dissolved completely, it added gradually, stirring 55 mass parts of water to the polyester solution. After addition, it cooled to room temperature, stirring a liquid, and produced the milky white polyester aqueous dispersion (Aw-1) of 30 mass % of solid content.

(Polymerization of polyester resin A-2)

To a stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux cooler, 163 parts by mass of dimethyl terephthalate, 163 parts by mass of dimethyl isophthalate, 169 parts by mass of 1,4-butanediol, 324 parts by mass of ethylene glycol and tetra-n- 0.5 mass parts of butyl titanate was thrown in, and the transesterification reaction was performed from 160 degreeC to 220 degreeC over 4 hours.

Next, 14 mass parts of fumaric acids and 203 mass parts of sebacic acids were added, it heated up from 200 degreeC to 220 degreeC over 1 hour, and esterification was performed. Subsequently, the temperature was raised to 255°C and the reaction system was gradually reduced in pressure, and then reacted under reduced pressure of 29 Pa for 1 hour and 30 minutes to obtain a hydrophobic copolymerized polyester resin (A-2). The obtained hydrophobic copolymerized polyester resin (A-2) was pale yellow and transparent.

(Preparation of polyester aqueous dispersion Aw-2)

Next, 60 parts by mass of this copolymerized polyester resin (A-2), 45 parts by mass of methyl ethyl ketone, and 15 parts by mass of isopropyl alcohol were put into a reactor equipped with a production stirrer, thermometer, reflux device and quantitative dropping device for the production of graft resin. , the resin was dissolved by heating and stirring at 65°C. After resin melt|dissolved completely, 24 mass parts of maleic anhydride was added to the polyester solution.

Then, the solution which melt|dissolved 16 mass parts of styrene and 1.5 mass parts of azobisdimethylvaleronitriles in 19 mass parts of methyl ethyl ketone was dripped at 0.1 ml/min in the polyester solution, and stirring was continued for further 2 hours. After sampling for analysis from the reaction solution, 8 mass parts of methanol was added. Next, 300 mass parts of water and 24 mass parts of triethylamine were added to the reaction solution, and it stirred for 1 hour.

Thereafter, the internal temperature of the reactor was raised to 100° C., methyl ethyl ketone, isopropyl alcohol, and excess triethylamine were distilled off by distillation to obtain a pale yellow transparent polyester resin, uniformly having a solid content concentration of 25% by mass. A water-dispersible polyester-based graft copolymer dispersion (Aw-2) was prepared. The glass transition temperature of the obtained polyester graft copolymer was 68 degreeC.

(Preparation of polyurethane aqueous dispersion Aw-3)

To a four-neck flask equipped with a stirrer, a Dimroth condenser, a nitrogen inlet tube, a silica gel drying tube and a thermometer, 43.75 parts by mass of 4,4-dicyclohexylmethane diisocyanate, 12.85 parts by mass of dimethylolbutanoic acid, a number average molecular weight of 2000 poly 153.41 parts by mass of hexamethylene carbonate diol, 0.03 parts by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent were added, and stirred under a nitrogen atmosphere at 75° C. for 3 hours, until the reaction solution reached a predetermined amine equivalent. confirmed that. Then, after temperature-falling this reaction liquid to 40 degreeC, 8.77 mass parts of triethylamines were added, and the polyurethane prepolymer solution was obtained. Then, 450 g of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring, adjusted to 25° C., ^{and stirred and mixed at 2000 min −1} , while a polyurethane prepolymer solution was added and dispersed in water. Then, water-soluble polyurethane resin solution Aw-3 with a solid content of 37 mass % was manufactured by removing a part of acetone and water under reduced pressure. The glass transition point temperature of the obtained polyurethane resin was -30 degreeC.

(Silica Particles B-1)

Colloidal silica (manufactured by Nissan Chemical, trade name Snowtex OL, average particle size 40 nm, solid content concentration 20% by mass)

(Silica Particle B-2)

Colloidal silica (manufactured by Nissan Chemical, trade name Snowtex ZL, average particle size of 100 nm, solid content concentration of 40% by mass)

(Silica particles B-3)

Colloidal silica (manufactured by Nissan Chemical, trade name MP2040, average particle size 200 nm, solid content concentration 40 mass%)

(Silica Particles B-4)

Colloidal silica (manufactured by Nissan Chemical, trade name MP4540M, average particle size of 450 nm, solid content concentration of 40% by mass)

(Acrylic Particles B-5)

Acrylic particle aqueous dispersion (made by Nippon Shokubai, trade name MX100W, average particle diameter 150 nm, solid content concentration 10% by mass)

(Release agent solution X-1)

100 parts by mass of a UV curable silicone resin (UV9300 manufactured by Momentive, 100% by mass of solid content) and 1 part by mass of curing catalyst bis(alkylphenyl)iodonium hexafluoroantimonate, toluene/methylethylketone/heptane (=3 :5:2) solution, and the mold release agent solution of 2 mass % of solid content was prepared.

(Release agent solution X-2)

100 parts by mass of a thermosetting aminoalkyd resin (Tespine 314 manufactured by Hitachi Chemical Corporation, solid content 60% by mass) and 1.2 parts by mass of p-toluenesulfonic acid (made by Hitachi Chemical Co., Ltd., dryer 900, solid content 50% by mass) as a curing catalyst, 1.2 parts by mass; It diluted with a toluene/methyl ethyl ketone/heptane (=3:5:2) solution, and the mold release agent solution of 2 mass % of solid content was prepared.

(Back smoothing coating liquid Y)

94 parts by mass of dipentaerythritol hexaacrylate [solid content: 100% by mass] as an active energy ray compound, and polydimethylsiloxane [Bic Chemie Japan Co., Ltd.] which has a polyether-modified acryloyl group as polyorganosiloxane , brand name "BYK-3500", solid content 100 mass %] 1 mass part, and alpha-aminoalkylphenone type photoinitiator [the BASF company make, brand name "IRGACURE907", 2-methyl-1[4-(methylthio) as a photoinitiator] )phenyl]-2-morpholinopropan-1-one, solid content 100% by mass] 5 parts by mass is diluted with an isopropyl alcohol/methylethyl ketone mixed solvent (mass ratio 3/1) to smooth the back surface with a solid content of 20 mass% A material for forming a coating layer was obtained.

(Example 1)

(Adjustment of lubricating coating solution 1)

The lubricating coating solution 1 of the following composition was adjusted.

(Moisture coating solution 1)

48.33 parts by mass of water

35.00 parts by mass of isopropyl alcohol

15.78 parts by mass of polyester aqueous dispersion Aw-1

(solid content concentration of 30% by mass)

0.59 mass parts of silica particle B-3

(Average particle diameter 200 nm, solid content concentration 40 mass %)

Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

(Production of polyester film)

As a film raw material polymer, PET resin pellets (PET(II)) having an intrinsic viscosity (solvent: phenol/tetrachloroethane=60/40) of 0.62 dl/g and substantially free of particles were prepared under a reduced pressure of 133 Pa. , and dried at 135 °C for 6 hours. Thereafter, it was supplied to an extruder, melt-extruded into a sheet at about 280°C, and quenched and solidified on a rotating cooling 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. by a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction in a roll group having a difference in peripheral speed to obtain a uniaxially stretched PET film.

Then, the lubricating coating solution was applied to one side of the PET film with a bar coater, and then dried at 80° C. for 15 seconds. Moreover, it adjusted so that the application amount after final extending|stretching and drying might be set to 0.1 micrometer. Then, in a tenter, it stretched 4.0 times in the width direction at 150 degreeC, and in the state which fixed the length of the width direction of the film, it heated at 230 degreeC for 0.5 second, and also 230 degreeC for 10 second 3% of width direction relaxation treatment to obtain an in-line coated polyester film having a thickness of 31 µm.

(Formation of release coating layer)

On the surface opposite to the lamination surface of the release coating layer of the in-line coated polyester film obtained above, the release agent solution X-1 was applied with a reverse gravure coater so that the thickness after drying was 0.1 μm, and then 30 with hot air at 90° C. After drying for a second, it was immediately irradiated with ultraviolet rays (300 mJ/cm 2 ) with an electrodeless lamp (H valve manufactured by Fusion Corporation) to form a release coating layer to obtain a release film for producing an ultra-thin ceramic green sheet. Moreover, it was excellent in process passability, handling property, such as winding property, without a problem in particular.

(Example 2)

The same as in Example 1 except that the lubricating coating solution 2 in which the silica particle B-3 in the lubricating coating liquid 1 used in Example 1 was changed to the silica particle B-4 (average particle diameter of 450 nm, solid content concentration of 40% by mass) was used. to obtain a release film for manufacturing an ultra-thin ceramic green sheet.

(Example 3)

Except having changed the lubricating coating liquid 1 to the following lubricating coating liquid 3, it carried out similarly to Example 1, and obtained the release film for ultra-thin ceramic green sheet manufacture.

(Moisture coating solution 3)

47.43 parts by mass of water

35.00 parts by mass of isopropyl alcohol

14.92 parts by mass of polyester aqueous dispersion Aw-1

(solid content concentration of 30% by mass)

2.24 parts by mass of silica particle B-1

(Average particle diameter of 40 nm, solid content concentration of 20 mass %)

Silica particle B-4 0.11 parts by mass

(Average particle size of 450 nm, solid content concentration of 40 mass%)

Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

(Example 4)

Except having changed the lubricating coating liquid 1 into the following lubricating coating liquid 4, it carried out similarly to Example 1, and obtained the polyester film.

(Moisture coating solution 4)

48.54 parts by mass of water

35.00 parts by mass of isopropyl alcohol

14.92 parts by mass of polyester aqueous dispersion Aw-1

(solid content concentration of 30% by mass)

1.12 parts by mass of silica particle B-2

(Average particle diameter of 100 nm, solid content concentration of 40 mass %)

Silica particle B-4 0.11 parts by mass

(Average particle size of 450 nm, solid content concentration of 40 mass%)

Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

(Example 5)

Except having changed the lubricating coating liquid 1 into the following lubricating coating liquid 5, it carried out similarly to Example 1, and obtained the polyester film.

(Oticulous coating solution 5)

45.18 parts by mass of water

35.00 parts by mass of isopropyl alcohol

Polyester aqueous dispersion Aw-2 18.93 mass parts

(Solid content concentration of 25% by mass)

0.59 mass parts of silica particle B-3

(Average particle diameter 200 nm, solid content concentration 40 mass %)

Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

(Example 6)

Except having changed the lubricating coating liquid 1 into the following lubricating coating liquid 6, it carried out similarly to Example 1, and obtained the polyester film.

(Moisture coating solution 6)

51.32 parts by mass of water

35.00 parts by mass of isopropyl alcohol

12.79 parts by mass of polyurethane resin aqueous dispersion Aw-3

(Solid content concentration 37% by mass)

0.59 mass parts of silica particle B-3

(Average particle diameter 200 nm, solid content concentration 40 mass %)

Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

(Example 7)

A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the release coating layer was formed as follows.

(Formation of release coating layer)

To the obtained inline coated polyester film, the release agent solution X-2 was applied to the surface layer (a) opposite to the lubrication coating layer with a reverse gravure coater so that the thickness after drying became 0.1 μm, and then dried with hot air at 130° C. for 30 seconds. By doing so, a release coating layer was formed and a release film for producing an ultra-thin ceramic green sheet was obtained.

(Example 8)

Except having changed the lubricating coating liquid 1 into the following lubricating coating liquid 8, it carried out similarly to Example 1, and obtained the polyester film.

(Moisture coating solution 8)

46.56 parts by mass of water

35.00 parts by mass of isopropyl alcohol

15.78 parts by mass of polyester aqueous dispersion Aw-1

(solid content concentration of 30% by mass)

Acrylic particle B-5 2.37 parts by mass

(Average particle diameter 150 nm, solid content concentration 10 mass %)

Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

(Comparative Example 1)

As a film for forming a release coating layer, instead of the inline coating film having a lubricity coating layer on one surface produced in Example 1, it was changed to E5000-25㎛ (made by Toyobo) and used, except that it was used in the same manner as in Example 1 A release film for manufacturing a ceramic green sheet was obtained by the method. E5000 contained particles inside the film, and the Sa on both surfaces was 0.031 µm.

(Comparative Example 2)

A release film for manufacturing a ceramic green sheet was obtained in the same manner as in Comparative Example 1 except that the application thickness of the release layer was changed to 1.0 µm.

(Comparative Example 3)

As a film for forming a release coating layer, instead of the in-line coating film having a lubricating coating layer on one surface produced in Example 1, it was changed to laminated film Z, and the film Z on the side not containing the lubricating agent A release film for manufacturing a ceramic green sheet was obtained in the same manner as in Example 1 except that a release coating layer was formed on the surface.

(Comparative Example 4)

On the surface opposite to the surface on which the release coating layer was formed of the release film for manufacturing a ceramic green sheet obtained in Comparative Example 3, the back smoothing coating solution Y was dried and then applied with a reverse gravure coater to a thickness of 0.5 μm, and then 90 After drying for 30 seconds with hot air at ° C., UV irradiation (300 mJ/cm 2 ) was immediately performed with an electrodeless lamp (H valve manufactured by Fusion Co., Ltd.) to form a back smoothing layer, thereby obtaining a release film for manufacturing ceramic green sheets.

(Comparative Example 5)

The release film for ceramic green sheet manufacture was obtained by the method similar to the comparative example 4 except having coated the back smoothing layer so that it might become 0.7 micrometer.

(Comparative Example 6)

The release film for ceramic green sheet manufacture was obtained by the method similar to the comparative example 4 except having coated the back smoothing layer so that it might become 1.0 micrometer.

Table 1 shows the evaluation results of each Example and Comparative Example. Moreover, process passability, handling property, such as winding property of each Example, were excellent without a problem in particular similarly to Example 1.

In Examples 1 to 8, since all parameters of Sa, P, and RSm on the surface of the lubricating coating layer were in appropriate ranges, ceramic green sheets without pinholes were obtained. In Comparative Examples 1 to 3, since all parameters of Sa, P, and RSm of the smooth surface were large, the occurrence of pinholes was observed. In Comparative Examples 4 to 6, by filling the unevenness of the smooth surface with a smoothing layer, Sa and P could be obtained in an appropriate range, but since RSm was large, it was insufficient to suppress the occurrence of pinholes. A large RSm means that the protrusion interval is wide and the number of protrusions per unit area is small, and it is considered that the pressure applied to each protrusion is large, and pinholes are generated.

ADVANTAGE OF THE INVENTION According to this invention, even when a ceramic green sheet is thinned, it becomes possible to provide the release film for ceramic green sheet manufacture which can achieve both good winding property, prevention of pinholes, partial thickness fluctuations, etc. compatible. Moreover, by using the release film for ceramic green sheet manufacture of this invention, an extremely thin ceramic green sheet can be obtained, and a micro ceramic capacitor can be manufactured efficiently.

Claims (8)

A polyester film substantially free of particles is used as a base material, and a release coating layer is provided on one surface of the base material, and a lubricity coating layer containing particles is provided on the other surface of the base material. A release film for manufacturing a ceramic green sheet, characterized in that the area surface average roughness (Sa) of 1 nm or more and 25 nm or less, the maximum protrusion height (P) is 60 nm or more and 500 nm or less, and the average length (RSm) of the roughness curve element is 5 µm or less . The release film for manufacturing a ceramic green sheet according to claim 1, wherein the area surface average roughness (Sa) of the release coating layer is 5 nm or less, and the maximum protrusion height (P) is 30 nm or less. The release film for manufacturing a ceramic green sheet according to claim 1 or 2, wherein the lubricating coating layer has a thickness of 0.001 μm or more and 2 μm or less. A method for manufacturing a ceramic green sheet, comprising using the release film for manufacturing a ceramic green sheet according to claim 1 or 2. The method for manufacturing a ceramic green sheet according to claim 4, wherein the thickness of the ceramic green sheet to be manufactured is 0.2 µm or more and 2 µm or less. A method for manufacturing a ceramic capacitor, wherein the method for manufacturing a ceramic green sheet according to claim 4 is adopted. The release film for manufacturing a ceramic green sheet according to claim 1 or 2, wherein the lubricating coating layer has lubricating particles and the average particle diameter of the particles is 1000 nm or less. The release film for manufacturing a ceramic green sheet according to claim 1 or 2, wherein the lubricating coating layer has two types of lubricating particles having different average particle diameters, and one of the lubricating particles having an average particle diameter of 300 nm or more and 1000 nm or less.