WO2017199774A1

WO2017199774A1 - Release film for producing ceramic green sheet

Info

Publication number: WO2017199774A1
Application number: PCT/JP2017/017354
Authority: WO
Inventors: 悠介柴田; 賢二吉野; 諒堀川
Original assignee: 東洋紡株式会社
Priority date: 2016-05-16
Filing date: 2017-05-08
Publication date: 2017-11-23
Also published as: JP2018052117A; JP6237964B1; KR20210060671A; KR20240074885A; JP2020111052A; TWI717515B; KR102666579B1; TW201808568A; JP7017183B2; JP2021088192A; CN109070383A; KR20240074884A; CN109070383B; JP2021098369A; JP6841355B2; JP7017184B2; JPWO2017199774A1; KR20190008201A; KR102314397B1; JP6852644B2

Abstract

[Problem] To provide an excellent release film for producing a ceramic green sheet, the release film being capable of attaining both satisfactorily suitability for winding and prevention of pinholes, local thickness unevenness, etc., even when forming a ceramic green sheet having a reduced thickness. [Solution] A release film for producing a ceramic green sheet, the release film comprising a substrate that is a polyester film containing substantially no particles, a release coating layer formed on one surface of the substrate, and an easy-to-slip coating layer formed on the other surface and containing particles, wherein the easy-to-slip coating layer has an average surface region roughness (Sa) of 1-25 nm, a maximum projection height (P) of 60-500 nm, and an average roughness-curve-element length (RSm) of 10 µm or less.

Description

Release film for manufacturing ceramic green sheets

The present invention relates to a release film for producing ceramic green sheets. More specifically, the present invention relates to a release film for producing a ceramic green sheet that can achieve both good winding properties and prevention of pinholes and partial thickness variations even when the ceramic green sheet is thinned.

Conventionally, the release film for producing ceramic green sheets is stored in a rolled state by making the surface roughness of the surface (back surface) opposite to the surface provided with the release agent layer of the base film relatively rough. A technique is disclosed that eliminates problems such as sticking (blocking) of the release film for producing a ceramic green sheet when it is applied (see, for example, Patent Document 1). However, such a conventional technique has a problem that pinholes and partial thickness variations occur due to large protrusions.

In order to reduce the height of the protrusion, a technique for preventing the pinhole and the partial thickness variation from occurring in the ceramic green sheet by filling the protrusion on the back surface with the coating layer is disclosed (for example, , See Patent Document 2). However, according to such a conventional technique, although the protrusion height is low, the protrusion density is low, so the pressure applied to the protrusion is large, and when the ceramic green sheet is further thinned, pinholes are generated. there were.

JP 2003-203822 A JP 2014-144636 A

The present invention has been made against the background of the problems of the prior art. That is, the object of the present invention is to produce an excellent ceramic green sheet that can achieve both good winding properties and prevention of pinholes and partial thickness variations even when the ceramic green sheet is thinned. It is to provide a release film.

As a result of intensive studies to achieve the above object, the present inventors have completed the present invention. That is, the present invention has the following configuration.
1. A polyester film substantially free of particles is used as a base material, a release coating layer is provided on one surface of the base material, and a slippery coating layer containing particles is provided on the other surface. Having an average surface roughness (Sa) of 1 nm to 25 nm, a maximum protrusion height (P) of 60 nm to 500 nm, and an average length (RSm) of the roughness curve element of 10 μm or less. A release film for producing a ceramic green sheet, characterized in that
2. 2. The release film for producing a ceramic green sheet according to the first aspect, wherein the area average surface roughness (Sa) of the release coating layer is 5 nm or less and the maximum protrusion height (P) is 30 nm or less.
3. The release film for producing a ceramic green sheet as described in the above item 1 or 2, wherein the easy-slip coating layer has a thickness of 0.001 µm to 2 µm.
4). A method for producing a ceramic green sheet, comprising using the release film for producing a ceramic green sheet according to any one of the first to third aspects.
5). The method for producing a ceramic green sheet according to the fourth aspect, wherein the thickness of the ceramic green sheet to be produced is 0.2 μm or more and 2 μm or less.
6). A method for producing a ceramic capacitor, wherein the method for producing a ceramic green sheet according to the fourth or fifth aspect is adopted.

ADVANTAGE OF THE INVENTION According to this invention, even when a ceramic green sheet is made into a thin film, it is possible to provide a release film for producing a ceramic green sheet that can achieve both good winding properties and prevention of pinholes and partial thickness variations. Is possible.

Hereinafter, the present invention will be described in detail.
The release film for producing 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 as a base film, and particles on the other side. A release film having an easy-to-slip coating layer.

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

The polyester film may be a single layer or a multilayer. Moreover, as long as it exists in the range with the effect of this invention, each of these layers can contain various additives in a polyester resin as needed. Examples of the additive include an antioxidant, a light-resistant agent, an anti-gelling agent, an organic wetting agent, an antistatic agent, and an ultraviolet absorber.

(Easy-slip coating layer)
The release film of the present invention has an easy-slip coating layer on one surface of a polyester base film as described above. The easy-slip coating layer preferably contains at least a binder resin and particles.

(Binder resin in the easy-to-slip coating layer)
Although it does not specifically limit as binder resin which comprises an easy-slip coating layer, As a specific example of a polymer, polyester resin, acrylic resin, urethane resin, polyvinyl resin (polyvinyl alcohol etc.), polyalkylene glycol, polyalkylene imine, methylcellulose , Hydroxycellulose, starches and the like. Among these, it is preferable to use a polyester resin, an acrylic resin, or a urethane resin from the viewpoint of particle retention and adhesion. In consideration of familiarity with the polyester film, a polyester resin is particularly preferable. In order to achieve solubility in a solvent, dispersibility, and adhesion to a base film and other layers, the polyester of the binder is preferably a copolyester. The polyester resin may be modified with polyurethane. Moreover, urethane resin is mentioned as another preferable binder resin which comprises the easy-slip coating layer on a polyester base film. Examples of the urethane resin include polycarbonate polyurethane resin. Furthermore, a polyester resin and a polyurethane resin may be used in combination, or other binder resins described above may be used in combination.

(Crosslinking agent)
In the present invention, in order to form a crosslinked structure in the slippery coating layer, the slippery coating layer may be formed to contain a crosslinking agent. By containing a crosslinking agent, it becomes possible to further improve the adhesion under high temperature and high humidity. Specific examples of the crosslinking agent include urea, epoxy, melamine, isocyanate, oxazoline, and carbodiimide. Moreover, in order to promote a crosslinking reaction, a catalyst etc. can be used suitably as needed.

(Particles in the easy-to-slip coating layer)
The slippery coating layer 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, zirconium oxide, titanium dioxide, satin white, aluminum silicate, diatomaceous earth, calcium silicate, aluminum hydroxide, hydrous halloysite, calcium carbonate, magnesium carbonate, calcium phosphate, hydroxide 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 / Iso Organic particles such as len, methyl methacrylate / butyl methacrylate, melamine, polycarbonate, urea, epoxy, urethane, phenol, diallyl phthalate, polyester, etc. Silica is particularly preferably used for providing slipperiness.

The average particle diameter of the particles is preferably 10 nm or more, more preferably 20 nm or more, and further preferably 30 nm or more. When the average particle size of the particles is 10 nm or more, it is preferable that aggregation is difficult and slipperiness can be secured.

The average particle size of the particles is preferably 1000 nm or less, more preferably 800 nm or less, and even more preferably 600 nm or less. It is preferable that the average particle diameter of the particles is 1000 nm or less because transparency is maintained and the particles do not fall off.

In addition, for example, a mixture of small particles having an average particle size of about 10 to 200 nm and large particles having an average particle size of about 300 to 1000 nm can also be described as the region surface average roughness (Sa) and the maximum protrusion height (described later). While keeping P) small, it is preferable to make the average length (RSm) of the roughness curve element small so as to achieve both slipperiness and smoothness, and particularly preferably small particles of 30 nm to 150 nm and average particles A large particle having a diameter of 350 to 600 nm is used in combination. When mixing small particles and large particles, it is preferable that the mass content of the small particles is larger than the mass content of the large particles with respect to the entire solid content of the coating layer.

The average particle size of the particles is measured by observing particles in the cross section of the processed film with a transmission electron microscope or a scanning electron microscope, observing 100 non-aggregated particles, and using the average value for the average particle size. It was performed by the method of diameter.

The shape of the particles is not particularly limited as long as the object of the present invention is satisfied, and spherical particles and irregular non-spherical particles can be used. The particle diameter of the irregular shaped particles can be calculated as the equivalent circle diameter. The equivalent circle diameter is a value obtained by dividing the observed area of the particle by π and calculating the square root to double.

The ratio of the particles to the total solid content of the easy-coating layer is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less. When the ratio of the particles to the total solid content of the easy-to-slip coating layer is 50% by mass or less, transparency is maintained, and the particles are not easily dropped from the easy-slip coating layer, which is preferable.

The ratio of the particles to the total solid content of the easy-coating layer is preferably 1% by mass or more, more preferably 1.5% by mass or more, and further preferably 2% by mass or more. If the ratio of the particles to the total solid content of the slippery coating layer is 1% by mass or more, the slipperiness can be secured, which is preferable.

As a method for measuring the content of the particles contained in the easy-slip coating layer, for example, when the easy-slip coating layer contains an organic resin and inorganic particles, the following method can be used. First, the slippery coating layer provided on the processed film is extracted from the processed film using a solvent or the like and dried to take out the slippery coating layer. Next, only the inorganic component can be obtained by applying heat to the resulting slippery coating layer and burning off the organic component contained in the slippery coating layer with heat. By measuring the weight of the resulting inorganic component and the easy-to-slip coating layer before burning off, the mass% of the particles contained in the easy-to-slip coating layer can be measured. At this time, measurement can be performed with high accuracy by using a commercially available differential heat / thermogravimetric simultaneous measurement device.

(Additive in easy-to-slip coating layer)
In order to impart other functionality to the slippery coating layer, various additives may be contained within a range that does not impair the coating appearance. Examples of the additive include fluorescent dyes, fluorescent brighteners, plasticizers, ultraviolet absorbers, pigment dispersants, foam suppressors, antifoaming agents, and preservatives.

The easy-slip coating layer may contain a surfactant for the purpose of improving leveling properties during coating and defoaming the coating solution. The surfactant may be any of cationic, anionic, and nonionic surfactants, but is preferably a silicone, acetylene glycol, or fluorine surfactant. These surfactants are preferably contained in the coating layer in such a range that the appearance of the coating does not become abnormal when added excessively.

As the coating method, both a so-called in-line coating method in which a polyester base film is simultaneously formed and a so-called off-line coating method in which a polyester base film is formed and then separately applied with a coater can be applied. Is more efficient and more preferable.

As a coating method, a known arbitrary method can be used as a method for coating the coating liquid on a polyethylene terephthalate (hereinafter sometimes abbreviated as PET) film. 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, etc. Can be mentioned. These methods are applied alone or in combination.

In the present invention, as a method of providing an easy-slip coating layer on a polyester film, a method of applying a coating solution containing a solvent, particles, and a resin to the polyester film and drying may be 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, from the viewpoint of environmental problems, water alone or a so-called aqueous system in which water is mixed with a water-soluble organic solvent. These solvents are preferred.

The concentration of the solid content of the easy-to-slip coating liquid is preferably 0.5% by mass or more, more preferably 1% by mass or more, although it depends on the type of binder resin and the type of solvent. The solid concentration of the coating solution is preferably 35% by mass or less, and more preferably 20% by mass or less.

The drying temperature after coating also depends 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.

(Manufacture 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 non-oriented polyester extruded and formed into a sheet shape is stretched in the longitudinal direction by utilizing the speed difference of the roll at a temperature equal to or higher than the glass transition temperature, and then stretched in the transverse direction by a tenter. The method of performing heat processing is mentioned. In addition, a method of biaxial stretching in the tenter at the same time in the vertical and horizontal directions is also mentioned.

In the present invention, the polyester film as the base film may be a uniaxially stretched film or a biaxially stretched film, but is preferably a biaxially stretched film.

The thickness of the polyester film substrate is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. When the thickness is 5 μm or more, it is preferable that wrinkles do not easily occur during conveyance of the film.

The thickness of the polyester film substrate is preferably 50 μm or less, more preferably 45 μm or less, and even more preferably 40 μm or less. A thickness of 40 μm or less is preferable because the cost per unit area is reduced.

In the case of in-line coating, it may be applied to an unstretched film before stretching in the machine direction or may be applied to a uniaxially stretched film after stretching in the machine direction and before stretching in the transverse direction. When coating is performed before stretching in the machine direction, it is preferable to provide a drying step before roll stretching. When coating on a uniaxially stretched film before stretching in the transverse direction, the film heating process in the tenter can also serve as the drying process, and therefore it is not always necessary to provide a separate drying process. The same applies to simultaneous biaxial stretching.

The film thickness of the easy-slip coating layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, still more preferably 0.02 μm or more, and particularly preferably 0.03 μm or more. It is preferable that the thickness of the coating layer is 0.001 μm or more because the film forming property of the coating film is maintained and a uniform coating film can be obtained.

The film thickness of the easy-slip coating layer is preferably 2 μm or less, more preferably 1 μm or less, still more preferably 0.8 μm or less, and particularly preferably 0.5 μm or less. It is preferable that the coating layer has a thickness of 2 μm or less because there is no risk of blocking.

The ceramic green sheet to be coated and molded on the mold release coating layer described later is wound into a roll together with the mold release film after coating and molding. At this time, it winds up in the state which the slipperiness application layer of the release film contacted the ceramic green sheet surface. In order not to generate defects on the surface of the ceramic green sheet, the outer surface of the easy-to-slip coating layer (the surface of the easy-to-slip coating layer of the entire coating film not in contact with the polyester film) needs to be reasonably flat. The surface average roughness (Sa) is preferably 1 nm to 25 nm and the maximum protrusion height (P) is preferably 60 nm to 500 nm.

If the average surface roughness (Sa) of the outer surface of the easy-to-slip coating layer is 1 nm or more and the maximum protrusion height (P) is 60 nm or more, the easy-to-slip coating surface is not too smooth and maintains an appropriate slipperiness. This is preferable because it is possible. If the area surface average roughness (Sa) is 25 nm or less and the maximum protrusion height (P) is 500 nm or less, the easy-slip coating surface does not become too rough, and defects in the ceramic green sheet due to the protrusion do not occur.

In the present invention, in addition to setting the region surface average roughness (Sa) and the maximum protrusion height (P) within the above ranges, the average length (RSm) of the roughness curve elements is preferably 10 μm or less. By controlling the average length (RSm) of the roughness curve element to 10 μm or less, the number of protrusions per unit area increases. Increasing the number of protrusions is preferable because the pressure applied to each protrusion is dispersed and reduced, and thus pinholes can be effectively suppressed. The average length (RSm) of the roughness curve element is more preferably 5 μm or less, and further preferably 3 μm or less. However, when the average length (RSm) of the roughness curve element is too small, it is related to the excessive content of particles in the easy-to-slip coating layer, and the area surface average roughness (Sa) becomes large. In addition, since it is also related to an increase in the maximum protrusion height (P), it is preferably 0.1 μm or more, may be 0.5 μm or more, and may be 1 μm or more.

In the present invention, in order to make the average length (RSm) of the roughness curve element within a predetermined range, it is preferable that the average particle diameter of the particles contained in the easy-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 the particles does not become too large, and RSm is preferably adjusted within a predetermined range.

(Release 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 and the like can be used, and each resin can be used alone or in combination of two or more. You can also

As the release coating layer of the present invention, for example, a silicone resin is a resin having a silicone structure in the molecule, and examples thereof include a curable silicone, a silicone graft resin, and a modified silicone resin such as alkyl modification. It is preferable to use a reactive cured silicone resin from the viewpoint of properties. As the reactive cured silicone resin, an addition reaction type, a condensation reaction type, an ultraviolet ray or electron beam curing type, or the like can be used. More preferably, a low-temperature curable addition reaction system that can be processed at a low temperature, and an ultraviolet ray or electron beam curing system are preferable. By using these materials, the polyester film can be processed at a low temperature. As a result, a polyester film with high flatness can be obtained with less heat damage to the polyester film during processing, 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. .

Examples of the addition reaction type silicone resin include those obtained by reacting polydimethylsiloxane having a vinyl group introduced into the terminal or side chain thereof with hydrodienesiloxane using a platinum catalyst to cure. At this time, it is more preferable to use a resin that can be cured at 120 ° C. within 30 seconds because processing at a low temperature is possible. As an example, low temperature addition curing type (LTC1006L, LTC1056L, LTC300B, LTC303E, LTC310, LTC314, LTC350G, LTC450A, LTC371G, LTC750A, LTC755A, LTC85A, L85 type, UV85B, LTC760A, etc. -510, BY24-561, 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.).

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

Examples of UV curable silicone resins include those that use the same radical reaction as ordinary silicone rubber crosslinks as the most basic types, those that introduce photopolymerization by introducing unsaturated groups, and those that decompose onium salts with UV light. Examples include those that generate a strong acid and then cleave the epoxy group to crosslink, and those that crosslink by the addition reaction of thiol to vinylsiloxane. Further, an electron beam can be used instead of the ultraviolet rays. Electron beams have stronger energy than ultraviolet rays, and can use a radical crosslinking reaction without using an initiator as in the case of ultraviolet curing. Examples of the resin used include UV curable silicones manufactured by Shin-Etsu Chemical Co., Ltd. (X62-7028A / B, X62-7052, X62-7205, X62-7622, X62-7629, X62-7660, etc.), Momentive Performance UV curable silicones manufactured by Materials (TPR6502, TPR6501, TPR6500, UV9300, UV9315, XS56-A2982, UV9430, etc.), UV curable silicones manufactured by Arakawa Chemical (Silicolys UV POLY200, POLY215, POLY201, KF-UV265AM, etc.) ).

As the above-mentioned UV-curable silicone resin, acrylate-modified or glycidoxy-modified polydimethylsiloxane can also be used. Mixing these modified polydimethylsiloxanes with polyfunctional acrylate resins or epoxy resins and using them in the presence of an initiator can also provide good release performance.

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

Examples of the aminoalkyd resin obtained by the reaction of methylated melamine include Tesfine 303, Tesfine 305, Tesfine 314 and the like manufactured by Hitachi Chemical Co., Ltd. Examples of the aminoacrylic resin obtained by the reaction of methylated melamine include Tesfine 322 manufactured by Hitachi Chemical Co., Ltd.

In the case of using the above resin for the release coating layer of the present invention, one type may be used, or two or more types may be mixed and used. 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.

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

In the release coating layer of the present invention, an additive such as an adhesion improver or an antistatic agent may be added. In order to improve the adhesion to the substrate, it is also preferable that the polyester film surface is subjected to pretreatment such as anchor coating, corona treatment, plasma treatment, atmospheric pressure plasma treatment, etc. before providing the release coating layer.

In the present invention, the thickness of the release coating layer may be set according to the purpose of use, and is not particularly limited. However, the thickness of the release coating layer after curing is preferably in the range of 0.005 to 2 μm. Good. When the thickness of the release coating layer is 0.005 μm or more, the peeling performance is maintained, which is preferable. Moreover, it is preferable that the thickness of the release coating layer is 2 μm or less because the curing time does not become too long and there is no possibility of uneven thickness of the ceramic green sheet due to a decrease in the flatness of the release film. In addition, since the curing time does not become too long, the resin constituting the release coating layer does not have a possibility of agglomeration and there is no possibility of forming protrusions.

The outer surface of the film on which the release coating layer is formed (the surface of the release coating layer of the entire coating film that is not in contact with the polyester film) is flat so as not to cause defects in the ceramic green sheet applied and molded thereon. It is desirable that the area surface average roughness (Sa) is 5 nm or less and the maximum protrusion height (P) is 30 nm or less. Furthermore, it is more preferable that the area surface average roughness (Sa) is 5 nm or less and the maximum protrusion height (P) is 20 nm or less. Particularly preferably, the area surface average roughness (Sa) is 3 nm or less and the maximum protrusion height (P) is 17 nm or less. If the area surface roughness (Sa) is 5 nm or less and the maximum protrusion height (P) is 30 nm or less, there is no occurrence of defects such as pinholes when forming the ceramic green sheet, and the yield is favorable. It can be said that the smaller the surface average surface roughness (Sa), the better, 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 better, but it may be 1 nm or more, or 3 nm or more.

In the present invention, in order to adjust the film surface on which the release coating layer is formed to a predetermined roughness range, it is preferable that the PET film does not substantially contain particles. In the present invention, “substantially free of particles” means, for both the base film and the release coating layer, for example, in the case of inorganic particles, quantitative analysis of elements derived from the particles by fluorescent X-ray analysis. Is defined as 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit. This means that even if particles are not actively added to the base film, contaminants derived from foreign substances and raw material resin or dirt adhering to the line or equipment in the film manufacturing process will be peeled off and mixed into the film. It is because there is a case to do.

In the present invention, the method for forming the release coating layer is not particularly limited, and a coating solution in which a release resin is dissolved or dispersed is spread on one surface of the polyester film of the substrate by coating or the like, Etc. are removed by drying, followed by heat drying, heat curing or ultraviolet curing. At this time, the drying temperature at the time of solvent drying and thermosetting is preferably 180 ° C. or less, more preferably 150 ° C. or less, and most preferably 120 ° C. or less. The heating time is preferably 30 seconds or less, and more preferably 20 seconds or less. When the temperature is 180 ° C. or lower, the flatness of the film is maintained, and there is little possibility of causing uneven thickness of the ceramic green sheet. When the temperature is 120 ° C. or less, 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.

In the present invention, the surface tension of the coating liquid when applying the release coating layer is not particularly limited, but is preferably 30 mN / m or less. By making the surface tension as described above, the paintability after coating can be improved, and the unevenness of the coating film surface after drying can be reduced.

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 at the time of drying can be prevented, the coating film can be leveled, and the smoothness of the coating film surface after drying can be improved. The addition amount is preferably about 10 to 80% by mass with respect to the whole coating solution.

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

(Ceramic green sheet and ceramic capacitor)
In general, a multilayer ceramic capacitor has a rectangular parallelepiped ceramic body. In the ceramic body, first internal electrodes and second internal electrodes are alternately provided along the thickness direction. The first internal electrode is exposed at 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 at the second end face 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 at the second end face.

The release film for producing a ceramic green sheet of the present invention is used for producing such a multilayer ceramic capacitor. For example, it is manufactured as follows. First, the release film of the present invention is used as a carrier film, and a ceramic slurry for constituting a ceramic body is applied and dried. 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 printed with a conductive layer for constituting the first internal electrode, and a ceramic green sheet printed with a conductive layer for constituting the second internal electrode are appropriately laminated and pressed. Thus, a mother laminate is obtained. The mother laminated body is divided into a plurality of parts to produce a raw ceramic body. 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.

Next, the present invention will be described in detail using examples and comparative examples, but the present invention is not limited to the following examples. The evaluation method used in the present invention is as follows.

(1) Surface characteristics of coated film These are values measured under the following conditions using a non-contact surface shape measurement system (VertScan R550H-M100). The average surface roughness (Sa) and the average length (RSm) of the roughness curve elements were measured using an average of 5 measurements, and the maximum protrusion height (P) was the maximum of 5 measurements.
(Measurement condition)
・ Measurement mode: WAVE mode ・ Objective lens: 50 × ・ 0.5 × Tube lens ・ Measurement area 187 × 139 μm (Sa, P measurement)
Measurement length (Lr: reference length): 187 μm (RSm measurement)

(2) Evaluation of pinhole and thickness variation of ceramic green sheet The composition consisting of the following materials is stirred and mixed and dispersed for 2 hours using a paint shaker using 2.0 mm glass beads as a dispersion medium to obtain a ceramic slurry. It was.
Toluene 22.5% by mass
Ethanol 22.5% by mass
Barium titanate (HPBT-1 manufactured by Fuji Titanium) 50% by mass
Polyvinyl butyral (SLECK BH-3 manufactured by Sekisui Chemical Co., Ltd.)
5% by mass
Next, the slurry after drying is applied to the release surface of the release film sample using an applicator so that the dried slurry has a thickness of 0.5 μm, dried at 90 ° C. for 1 minute, and then the slurry surface and the smoothing coating layer surface are overlapped. After applying a load of 1 kg / cm ² for 1 minute, 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 applied from the opposite side of the ceramic slurry coating surface within a range of 25 cm ² , and the occurrence of pinholes through which light was transmitted was observed. Visual judgment was made.
○: No occurrence of pinholes and thickness variation No particular problem ×: Little occurrence of pinholes and / or slight variation in thickness XX: Little occurrence of pinholes and variation in thickness Slightly conspicuous XXX: There are many pinholes and thickness variation is conspicuous

(Preparation of polyethylene terephthalate pellets (PET (I)))
As the esterification reaction apparatus, a continuous esterification reaction apparatus comprising a three-stage complete mixing tank having a stirrer, a partial condenser, a raw material charging port and a product outlet was used. TPA (terephthalic acid) is 2 tons / hour, EG (ethylene glycol) is 2 moles per mole of TPA, antimony trioxide is made into an amount that makes Sb atoms 160 ppm with respect to the produced PET, and these slurries are esterified. Was continuously supplied to the first esterification reactor of the chemical reaction apparatus, and allowed to react at 255 ° C. at an average residence time of 4 hours at normal pressure. 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 is distilled off from the first esterification reaction can in the second esterification reaction can. EG solution containing 8 mass% of EG with respect to the generated PET, and further containing EG solution containing magnesium acetate tetrahydrate in an amount of 65 ppm of Mg atoms relative to the generated PET, and 40 ppm of P atoms relative to the generated PET An EG solution containing a quantity of TMPA (trimethyl phosphate) was added and reacted at 260 ° C. at normal pressure for an average residence time of 1 hour. Next, the reaction product of the second esterification reaction can was 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.). An average particle of 0.2 mass% of porous colloidal silica having an average particle diameter of 0.9 μm and an ammonium salt of polyacrylic acid adhered to 1 mass% of calcium carbonate, which was dispersed at an average number of treatments of 5 passes under the pressure of While adding 0.4% by mass of synthetic calcium carbonate having a diameter of 0.6 μm as an EG slurry of 10%, the reaction was carried out at 260 ° C. at an average residence time of 0.5 hours at normal pressure. The esterification reaction product produced in the third esterification reaction can was continuously supplied to a three-stage continuous polycondensation reaction apparatus to perform polycondensation, and sintered with a stainless steel fiber having a 95% cut diameter of 20 μm. After filtering with a filter, ultrafiltration was performed and extruded into water, and after cooling, it was cut into chips to obtain PET chips with an intrinsic viscosity of 0.60 dl / g (hereinafter referred to 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 above PET 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)).

(Manufacture of laminated film Z)
These PET chips were dried, melted at 285 ° C., melted at 290 ° C. with a separate melt extruder extruder, sintered with stainless steel fibers having a 95% cut diameter of 15 μm, and a 95% cut diameter Two-stage filtration of a filter obtained by sintering 15 μm stainless steel particles is performed and merged in a feed block, so that PET (I) becomes an anti-release surface side layer and PET (II) becomes a release surface side layer. And then extruded (casting) into a sheet at a speed of 45 m / min, electrostatically adhered and cooled on a casting drum at 30 ° C. by an electrostatic adhesion method, and unstretched with an intrinsic viscosity of 0.59 dl / g A polyethylene terephthalate sheet was obtained. The layer ratio was adjusted so that PET (I) / PET (II) = 60% / 40% in the discharge amount calculation of each extruder. Next, this unstretched sheet was heated with an infrared heater, and then stretched 3.5 times in the longitudinal direction at a roll temperature of 80 ° C. due to the speed difference between the rolls. Thereafter, the film was guided to a tenter and stretched 4.2 times in the transverse direction at 140 ° C. Subsequently, it heat-processed at 210 degreeC in the heat setting zone. Thereafter, a relaxation treatment of 2.3% was performed in the transverse direction at 170 ° C. to obtain a biaxially stretched polyethylene terephthalate film Z having a thickness of 31 μm. Sa of the release surface side layer of the obtained laminated film Z was 2 nm, and Sa of the anti-release surface side layer was 28 nm.

(Polymerization of polyester resin A-1)
In a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial reflux condenser, 194.2 parts by weight of dimethyl terephthalate, 184.5 parts by weight of dimethyl isophthalate, 14.8 parts by weight 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 a transesterification reaction was performed at a temperature of 160 ° C. to 220 ° C. over 4 hours. . Next, the temperature was raised to 255 ° C., and the pressure of the reaction system was gradually reduced, followed by reaction for 1 hour 30 minutes under a reduced pressure of 30 Pa to obtain a copolyester resin (A-1). The obtained copolyester resin (A-1) was light yellow and transparent. The reduced viscosity of the copolyester resin (A-1) was measured and found to be 0.60 dl / g. The glass transition temperature by DSC was 65 ° C.

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

(Polymerization of polyester resin A-2)
In a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial reflux condenser, 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 0.5 parts by mass of tetra-n-butyl titanate was charged, and a transesterification reaction was carried out from 160 ° C. to 220 ° C. over 4 hours.
Next, 14 parts by mass of fumaric acid and 203 parts by mass of sebacic acid were added, and the temperature was raised from 200 ° C. to 220 ° C. over 1 hour to carry out an esterification reaction. Next, the temperature was raised to 255 ° C., and the pressure of the reaction system was gradually reduced, followed by reaction for 1 hour 30 minutes under a reduced pressure of 29 Pa to obtain a hydrophobic copolyester resin (A-2). The obtained hydrophobic copolyester resin (A-2) was light yellow and transparent.

(Production of polyester water dispersion Aw-2)
Subsequently, 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 added to a reactor equipped with a stirrer, a thermometer, a reflux apparatus and a quantitative dropping apparatus. The mixture was heated and stirred at 65 ° C. to dissolve the resin. After the resin was completely dissolved, 24 parts by weight of maleic anhydride was added to the polyester solution.
Next, a solution obtained by dissolving 16 parts by mass of styrene and 1.5 parts by mass of azobisdimethylvaleronitrile in 19 parts by mass of methyl ethyl ketone was dropped into the polyester solution at 0.1 ml / min, and stirring was further continued for 2 hours. After sampling for analysis from the reaction solution, 8 parts by mass of methanol was added. Next, 300 parts by mass of water and 24 parts by mass of triethylamine were added to the reaction solution and stirred for 1 hour.
Thereafter, the internal temperature of the reactor was raised to 100 ° C., and methyl ethyl ketone, isopropyl alcohol and excess triethylamine were distilled off to obtain a pale yellow transparent polyester resin, and a uniform water dispersibility with a solid content concentration of 25% by mass. A polyester-based graft copolymer dispersion (Aw-2) was prepared. The obtained polyester-based graft copolymer had a glass transition temperature of 68 ° C.

(Production of polyurethane water dispersion Aw-3)
In a four-necked 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, 153.41 parts by mass of polyhexamethylene carbonate diol having a number average molecular weight of 2000, 0.03 parts by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent were added and stirred at 75 ° C. for 3 hours in a nitrogen atmosphere. It was confirmed that the liquid reached a predetermined amine equivalent. Next, after the temperature of this reaction liquid was lowered to 40 ° C., 8.77 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 g of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring and adjusted to 25 ° C., while stirring and mixing at 2000 min ⁻¹ , the polyurethane prepolymer solution was added and dispersed in water. . Thereafter, a part of acetone and water was removed under reduced pressure to prepare a water-soluble polyurethane resin solution Aw-3 having a solid content of 37% by mass. The obtained polyurethane resin had a glass transition temperature of −30 ° C.

(Silica particle B-1)
Colloidal silica (manufactured by Nissan Chemical Co., Ltd., 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 Co., Ltd., trade name Snowtex ZL, average particle size 100 nm, solid content concentration 40% by mass)

(Silica particle B-3)
Colloidal silica (manufactured by Nissan Chemical Co., Ltd., trade name MP2040, average particle size 200 nm, solid content concentration 40% by mass)

(Silica particle B-4)
Colloidal silica (manufactured by Nissan Chemical Co., Ltd., trade name MP4540M, average particle size 450 nm, solid content concentration 40 mass%)

(Acrylic particles B-5)
Acrylic particle water dispersion (product of Nippon Shokubai, trade name MX100W, average particle size 150 nm, solid content concentration 10% by mass)

(Releasing agent solution X-1)
100 parts by mass of UV curable silicone resin (Momentive UV9300, solid content concentration: 100% by mass) and 1 part by mass of curing catalyst bis (alkylphenyl) iodonium hexafluoroantimonate, toluene / methyl ethyl ketone / heptane (= 3: 5: 2) Diluted with a solution to prepare a release agent solution having a solid content of 2% by mass.

(Releasing agent solution X-2)
Thermosetting amino alkyd resin (Tesfine 314, manufactured by Hitachi Chemical Co., Ltd., 100 mass parts) and p-toluenesulfonic acid (Hitachi Chemical Co., Ltd., dryer 900, solid content 50 mass%) as a curing catalyst 2 parts by mass was diluted with a toluene / methyl ethyl ketone / heptane (= 3: 5: 2) solution to prepare a release agent solution having a solid content of 2% by mass.

(Back smoothing coating solution Y)
94 parts by mass of dipentaerythritol hexaacrylate [solid content: 100% by mass] as an active energy ray compound, and polydimethylsiloxane having a polyether-modified acryloyl group as a polyorganosiloxane [trade name, manufactured by Big Chemie Japan Co., Ltd. “BYK-3500”, solid content 100% by mass] 1 part by mass, α-aminoalkylphenone photopolymerization initiator [trade name “IRGACURE907”, manufactured by BASF, 2-methyl-1 as a photopolymerization initiator 5 parts by mass of [4- (methylthio) phenyl] -2-morpholinopropan-1-one, solid content 100% by mass] was diluted with an isopropyl alcohol / methyl ethyl ketone mixed solvent (mass ratio 3/1) to obtain a solid content. A material for forming a back surface smoothing coat layer of 20% by mass was obtained.

Example 1
(Adjustment of easy-slip coating solution 1)
Easy-slip coating solution 1 having the following composition was prepared.
(Easy-slip coating solution 1)
Water 48.33 parts by weight Isopropyl alcohol 35.00 parts by weight Polyester water dispersion Aw-1 15.78 parts by weight (solid content concentration 30% by weight)
Silica particle B-3 0.59 parts by mass (average particle size 200 nm, solid content concentration 40% by mass)
Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

(Manufacture of polyester film)
As a film raw material polymer, an intrinsic viscosity (solvent: phenol / tetrachloroethane = 60/40) is 0.62 dl / g, and PET resin pellets (PET (II)) containing substantially no particles are 133 Pa. It dried for 6 hours at 135 degreeC under pressure reduction. Thereafter, the sheet was supplied to an extruder, melted and extruded into a sheet at about 280 ° C., and rapidly cooled and solidified on a rotating cooling metal roll maintained at a surface temperature of 20 ° C. to obtain an unstretched PET sheet.

The 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 above easy-to-slip coating solution was applied to one side of a 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, the film was stretched 4.0 times in the width direction at 150 ° C. with a tenter, and heated at 230 ° C. for 0.5 seconds with the length in the width direction fixed, and further at 230 ° C. for 10 seconds. % In the width direction, and an in-line coated polyester film having a thickness of 31 μm was obtained.

(Formation of release coating layer)
On the surface of the inline-coated polyester film obtained above, opposite to the surface where the easy-coating layer is laminated, the release agent solution X-1 is applied with a reverse gravure coater so that the thickness after drying is 0.1 μm. Next, after drying for 30 seconds with hot air at 90 ° C., UV irradiation (300 mJ / cm ² ) was immediately performed with an electrodeless lamp (H bulb manufactured by Fusion Co., Ltd.) to form a release coating layer to form an ultrathin layer ceramic green. A release film for sheet production was obtained. In addition, the winding property, the process passing property, and the handling property were excellent with no particular problems.

(Example 2)
Other than using the easy-to-slip coating solution 2 in which the silica particles B-3 in the easy-to-slip coating solution 1 used in Example 1 were changed to silica particles B-4 (average particle size 450 nm, solid content concentration 40% by mass). Obtained a release film for producing an ultrathin ceramic green sheet in the same manner as in Example 1.

(Example 3)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1 except that the easy-slip coating solution 1 was changed to the following easy-slip coating solution 3.
(Easy-slip coating solution 3)
Water 47.43 parts by weight Isopropyl alcohol 35.00 parts by weight Polyester water dispersion Aw-1 14.92 parts by weight (solid content concentration 30% by weight)
Silica particle B-1 2.24 parts by mass (average particle size 40 nm, solid content concentration 20% by mass)
Silica particle B-4 0.11 part by mass (average particle size 450 nm, solid content concentration 40% by mass)
Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

Example 4
A polyester film was obtained in the same manner as in Example 1 except that the easy-to-slip coating liquid 1 was changed to the following easy-to-slip coating liquid 4.
(Easy-slip coating solution 4)
Water 48.54 parts by weight Isopropyl alcohol 35.00 parts by weight Polyester water dispersion Aw-1 14.92 parts by weight (solid content concentration 30% by weight)
Silica particle B-2 1.12 parts by mass (average particle size 100 nm, solid content concentration 40% by mass)
Silica particle B-4 0.11 part by mass (average particle size 450 nm, solid content concentration 40% by mass)
Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

(Example 5)
A polyester film was obtained in the same manner as in Example 1 except that the slippery coating liquid 1 was changed to the slippery coating liquid 5 described below.
(Easy-slip coating solution 5)
Water 45.18 parts by weight Isopropyl alcohol 35.00 parts by weight Polyester water dispersion Aw-2 18.93 parts by weight (solid content concentration 25% by weight)
Silica particle B-3 0.59 parts by mass (average particle size 200 nm, solid content concentration 40% by mass)
Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

(Example 6)
A polyester film was obtained in the same manner as in Example 1 except that the easy-slip coating solution 1 was changed to the following easy-slip coating solution 6.
(Easy-slip coating solution 6)
Water 51.32 parts by weight Isopropyl alcohol 35.00 parts by weight Polyurethane resin water dispersion Aw-3 12.79 parts by weight (solid content concentration 37% by weight)
Silica particle B-3 0.59 parts by mass (average particle size 200 nm, solid content concentration 40% by mass)
Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

(Example 7)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the release coating layer was formed as described below.
(Formation of release coating layer)
The release agent solution X-2 was applied to the surface layer (a) opposite to the slippery coating layer with a reverse gravure coater so that the thickness after drying was 0.1 μm. Then, a release coating layer was formed by drying with hot air at 130 ° C. for 30 seconds to obtain a release film for producing an ultrathin layer ceramic green sheet.

(Example 8)
A polyester film was obtained in the same manner as in Example 1 except that the easy-to-slip coating liquid 1 was changed to the following easy-to-slip coating liquid 8.
(Easy-slip coating solution 8)
Water 46.56 parts by weight Isopropyl alcohol 35.00 parts by weight Polyester water dispersion Aw-1 15.78 parts by weight (solid content concentration 30% by weight)
Acrylic particle B-5 2.37 parts by mass (average particle size 150 nm, solid content concentration 10% by mass)
Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

(Comparative Example 1)
As the film for forming the mold release coating layer, it was carried out except that it was changed to E5000-25 μm (manufactured by Toyobo Co., Ltd.) instead of the inline coating film having the slippery coating layer on one surface prepared in Example 1. A release film for producing a ceramic green sheet was obtained in the same manner as in Example 1. E5000 contained particles inside the film, and Sa on both surfaces was 0.031 μm.

(Comparative Example 2)
A release film for producing a ceramic green sheet was obtained in the same manner as in Comparative Example 1, except that the coating thickness of the release layer was changed to 1.0 μm.

(Comparative Example 3)
As a film for forming the release coating layer, instead of the inline coating film having an easy-to-slip coating layer on one surface prepared in Example 1, it is used by changing to the laminated film Z, and contains the lubricant of the film Z. A release film for producing a ceramic green sheet was obtained in the same manner as in Example 1 except that a release coating layer was formed on the non-side surface.

(Comparative Example 4)
Reverse gravure so that the thickness of the back surface smoothing coating liquid Y is 0.5 μm after drying on the surface opposite to the surface on which the release coating layer of the release film for producing the ceramic green sheet obtained in Comparative Example 3 is formed. After coating with a coater and then drying with hot air at 90 ° C. for 30 seconds, UV irradiation (300 mJ / cm ² ) is immediately performed with an electrodeless lamp (H bulb manufactured by Fusion Corporation) to form a back smoothing layer. Thus, a release film for producing a ceramic green sheet was obtained.

(Comparative Example 5)
A release film for producing a ceramic green sheet was obtained in the same manner as in Comparative Example 4 except that the back smoothing layer was coated to 0.7 μm.

(Comparative Example 6)
A release film for producing a ceramic green sheet was obtained in the same manner as in Comparative Example 4 except that the back smoothing layer was coated to 1.0 μm.

Table 1 shows the evaluation results of each example and comparative example. In addition, the winding property of each Example, the process passing property, and the handling property were excellent as in Example 1 without any particular problems.

In Examples 1 to 8, since all the parameters of Sa, P, and RSm on the surface of the easy-coating layer were in an appropriate range, a ceramic green sheet free from pinholes could be obtained. In Comparative Examples 1 to 3, since all the parameters of Sa, P and RSm on 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 the smoothing layer, Sa and P can be within an appropriate range, but since RSm is large, it is not effective for suppressing the occurrence of pinholes. It was enough. A large RSm means that the interval between the projections is wide and the number of projections per unit area is small, and the pressure applied to each projection is increased, which is considered to have caused a pinhole.

ADVANTAGE OF THE INVENTION According to this invention, even when a ceramic green sheet is made into a thin film, it is possible to provide a release film for producing a ceramic green sheet that can achieve both good winding properties and prevention of pinholes and partial thickness variations. Is possible. Further, by using the release film for producing a ceramic green sheet of the present invention, an extremely thin ceramic green sheet can be obtained, and a minute ceramic capacitor can be produced efficiently.

Claims

A polyester film substantially free of particles is used as a base material, a release coating layer is provided on one surface of the base material, and a slippery coating layer containing particles is provided on the other surface. Having an average surface roughness (Sa) of 1 nm to 25 nm, a maximum protrusion height (P) of 60 nm to 500 nm, and an average length (RSm) of the roughness curve element of 10 μm or less. A release film for producing a ceramic green sheet, characterized in that
2. The release film for producing a ceramic green sheet according to claim 1, wherein an area surface average roughness (Sa) of the release coating layer is 5 nm or less and a maximum protrusion height (P) is 30 nm or less.
The release film for producing a ceramic green sheet according to claim 1 or 2, wherein the thickness of the easy-slip coating layer is 0.001 µm or more and 2 µm or less.
A method for producing a ceramic green sheet, wherein the release film for producing a ceramic green sheet according to any one of claims 1 to 3 is used.
The method for producing a ceramic green sheet according to claim 4, wherein the thickness of the ceramic green sheet to be produced is 0.2 µm or more and 2 µm or less.
A method for producing a ceramic capacitor, wherein the method for producing a ceramic green sheet according to claim 4 or 5 is adopted.