JP2019116013A - Release film for manufacturing ceramic green sheet - Google Patents

Abstract

To provide a release film for manufacturing a ceramic green sheet capable of molding the ceramic green sheet less in defect even with ultra thin layer article with thickness of 1 μm or less by providing a release layer excellent in solvent resistance, small in hardening shrinkage, low in peel force and uniform, while maintaining high smoothness of a release layer surface of the release film.SOLUTION: There is provided a release film for manufacturing a ceramic green sheet having a release layer on at least a single surface of a polyester film, in which area surface average roughness (Sa) of the release layer surface is 7 nm or less, and the release layer is manufactured by curing a composition containing a radical curable material (a) having one or more kind of radial curable functional group selected from a (meth)acryloyl group and an alkenyl group, a thiol group-containing compound (b), a mold releasing agent (c), and a radical initiator (d).SELECTED DRAWING: None

Description

  The present invention relates to a release film for producing a ceramic green sheet, and more particularly, a release for producing a ceramic green sheet capable of suppressing the occurrence of process defects such as pinholes and thickness unevenness at the time of producing an ultrathin ceramic green sheet. It relates to film.

  Conventionally, a release film having a polyester film as a base material and a release layer laminated thereon is used for forming a ceramic green sheet such as a multilayer ceramic capacitor, a ceramic substrate or the like. In recent years, the thickness of ceramic green sheets tends to be thinner along with the miniaturization and the increase in capacity of multilayer ceramic capacitors. The ceramic green sheet is molded by applying a slurry containing a ceramic component such as barium titanate and a binder resin such as a polyvinyl acetal resin on a release film and drying. After printing the electrode on the molded ceramic green sheet and peeling it from the release film, the ceramic green sheet is laminated, pressed, fired, and an external electrode is applied to manufacture a laminated ceramic capacitor. So far, when molding a ceramic green sheet on the surface of the release layer of polyester film, the minute projections on the surface of the release layer affect the formed ceramic green sheet, and defects such as repelling and pinholes tend to occur. There was a problem such as Therefore, a method for realizing a release layer surface excellent in flatness has been developed (see, for example, Patent Document 1).

  However, in recent years, the thickness of ceramic green sheets has been further reduced, and ceramic green sheets having a thickness of 1.0 μm or less, more specifically 0.2 μm to 1.0 μm, have been required. Therefore, a release film having a smoother release layer surface is desired. In addition, since the strength of the ceramic green sheet is reduced as the film thickness is reduced, it is also desired to perform peeling force uniformly and low when peeling the ceramic green sheet from the release film. That is, it has become more important to minimize the force applied to the ceramic green sheet when peeling the ceramic green sheet from the release film and to prevent the ceramic green sheet from being damaged.

  In recent years, it has been found that the surface of the release layer becomes smooth by using a cured product of a composition containing a radical curable substance that reacts under active energy ray irradiation and a silicone component as the release layer. It was issued. In addition, when the ceramic green sheet is peeled off by increasing the elastic modulus of the mold release layer, the mold release layer is less likely to be deformed and it becomes difficult to follow the ceramic green sheet, so that it is also excellent in peelability. (See, for example, Patent Documents 2 and 3).

  However, according to the methods described in Patent Documents 2 and 3, there is a possibility that curing failure may occur due to the influence of oxygen inhibition due to the radical polymerization reaction. The silicone component segregated on the surface of the release layer is particularly susceptible to oxygen inhibition, and when using a silicone component having a radically polymerizable functional group, the curability of the surface of the release layer may be deteriorated. . As a result, the organic solvent used at the time of ceramic sheet processing or electrode printing corrodes the mold release layer, causing heavy peeling and deterioration of peeling uniformity, and there was a possibility of giving a defect to the ceramic green sheet at the time of peeling.

Generally, by performing radical polymerization under an inert gas atmosphere, curing failure due to oxygen inhibition can be prevented, but in this case, it is necessary to introduce special equipment and the processing speed is limited. As a result, productivity is poor and there is a problem in cost. When manufacturing under the atmosphere, it is necessary to secure a sufficient film thickness of the release layer in order to prevent curing failure due to oxygen inhibition, but since the radical curing substance has a large cure shrinkage, the release layer When the film thickness of the above was thick, there was a problem that the release film was likely to be curled. As a result, there is a possibility that the precision of electrode printing after ceramic green sheet molding may fall, and a release film with few curls was called for. On the other hand, if the film thickness of the release layer is reduced to suppress curling, curing failure due to oxygen inhibition is likely to occur, and the solvent resistance of the release layer may be deteriorated to cause heavy peeling. .

  That is, using a photo-radical curable substance that reacts by active energy ray irradiation in the air, the thickness of the release layer is made thin, specifically 0.5 μm or less, or 0.3 μm or less. In this case, the radical curing reaction does not proceed efficiently due to the influence of oxygen inhibition, which may cause curing failure and damage the ceramic green sheet at the time of peeling.

JP 2000-117899 A International Publication No. 2013/145864 International Publication No. 2013/145865

  The present invention has been made on the background of the problems of the prior art. That is, an object of the present invention is to provide a release layer which is excellent in solvent resistance, small in cure shrinkage, low in peeling force and uniform while maintaining high smoothness of the release layer surface of the release film. It is an object of the present invention to provide a release film for producing a ceramic green sheet capable of forming a ceramic green sheet having few defects even with an ultrathin layer product having a thickness of 1 μm or less.

That is, the present invention has the following constitution.
1. A release film provided with a release layer on at least one side of a polyester film, wherein the area average surface roughness (Sa) of the release layer surface is 7 nm or less, and the release layer has a (meth) acryloyl group and Composition containing a radical curable substance (a) having at least one radical curable functional group selected from alkenyl groups, a thiol group-containing compound (b), a mold release agent (c) and a radical initiator (d) A release film for producing a ceramic green sheet in which a product is cured.
2. The release film for producing a ceramic green sheet according to the first above, wherein the thiol group-containing compound (b) does not have a radical curable functional group selected from a (meth) acryloyl group and an alkenyl group.
3. The release film for producing a ceramic green sheet according to the first or the second, wherein the thiol group-containing compound (b) is a compound having two or more thiol groups in one molecule.
4. The difference (θ ₁ -θ ₂ ) between diiodomethane contact angle θ _{1 on} the release layer surface and diiodomethane contact angle θ _{2 on} the release layer surface after immersion of the release film in toluene is 3.0 ° or less as an absolute value The mold release film for ceramic green sheet manufacture in any one of said 1st-3rd.
5. The mold release film for ceramic green sheet manufacture in any one of said 1st-4th whose mold release agent (c) is a compound containing a silicone component.
6. The mold release film for ceramic green sheet manufacture in any one of said 1st-4th whose mold release agent (c) is a compound which contains a fluorine atom in a molecule | numerator.
7. For the production of the ceramic green sheet according to any one of the above first to sixth, wherein the content of the thiol group-containing compound (b) is 1 to 30% by mass with respect to the total mass of the composition forming the release layer. Release film.
8. The polyester film has a surface layer A substantially free of inorganic particles and an opposite surface layer B containing inorganic particles, and a release layer is provided on the surface layer A, the surface layer The ceramic green sheet according to any one of the above 1 to 7, wherein the inorganic particles contained in B are silica particles and / or calcium carbonate particles, and the total of the inorganic particles is contained in an amount of 5000 to 15000 ppm in the surface layer B. Release film for manufacturing.
9. The release film for ceramic green sheet manufacture in any one of said 1st-8th whose film thickness of a release layer is the range of 0.01 micrometer or more and 0.5 micrometer or less.
10. Radical curable substance (a) having at least one radical curable functional group selected from (meth) acryloyl group and alkenyl group, thiol group-containing compound (b), mold release agent (c), radical initiator ( The method for producing a release film for producing a ceramic green sheet according to any one of the above 1 to 9, wherein the composition containing d) is cured in the atmosphere to form a release layer.
11. A method for producing a ceramic green sheet having a thickness of 0.2 μm to 1.0 μm, which is a method for producing a ceramic green sheet using the release film for producing a ceramic green sheet according to any one of the first to ninth aspects. . The manufacturing method of the ceramic capacitor which employ | adopts the manufacturing method of the ceramic green sheet as described in said 11th.

  The release film for producing a ceramic green sheet according to the present invention can suppress oxygen inhibition, which is a problem unique to radical curable substances, and can enhance the curability of the surface of the release layer, so it is excellent in solvent resistance and releasability. It is possible to provide a mold release film. In addition, since the cure shrinkage can be reduced, the occurrence of curling is suppressed, and there is provided a release film for producing a ceramic green sheet without the risk of occurrence of unevenness in thickness of the ceramic green sheet and reduction in electrode printing accuracy. it can.

  The present inventors provide a release layer on at least one surface of a biaxially oriented polyester film directly or through another layer, and the area average surface roughness (Sa) of the release layer surface is 7 nm or less, and the release layer Under the atmosphere by curing the composition containing the radical curable substance (a), the thiol group-containing compound (b), the mold release agent (c) and the radical initiator (d). However, it has been found that the film thickness of the release layer can be reduced and a release film free from curling can be provided. Hereinafter, the present invention will be described in detail.

(Polyester film)
The polyester constituting the polyester film to be used as the substrate of the present invention is not particularly limited, and those obtained by film-forming polyester generally used as a substrate for release film can be used, but It may be a crystalline linear saturated polyester comprising an aromatic dibasic acid component and a diol component, for example, polyethylene terephthalate, polyethylene 2,6 naphthalate, polybutylene terephthalate, polytrimethylene terephthalate or resins thereof. Copolymers having a component as a main component are more preferred, and polyester films formed from polyethylene terephthalate are particularly preferred. In polyethylene terephthalate, the repeating unit of ethylene terephthalate is preferably 90 mol% or more, more preferably 95 mol% or more, and small amounts of other dicarboxylic acid components and diol components may be copolymerized, but from the viewpoint of cost And those produced solely from terephthalic acid and ethylene glycol. In addition, known additives, for example, an antioxidant, a light stabilizer, an ultraviolet light absorber, a crystallizing agent and the like may be added within a range not to inhibit the effect of the film of the present invention. The polyester film is preferably a biaxially oriented polyester film for reasons such as the height of the elastic modulus in both directions.

  The intrinsic viscosity of the polyethylene terephthalate film is preferably 0.50 to 0.70 dl / g, and more preferably 0.52 to 0.62 dl / g. When the intrinsic viscosity is 0.50 dl / g or more, a large number of fractures do not occur in the stretching step, which is preferable. On the contrary, when it is 0.70 dl / g or less, it is preferable because the cutting property when cutting into a predetermined product width is good and dimensional defects do not occur. In addition, it is preferable that the raw material be sufficiently vacuum dried.

  The method for producing the polyester film in the present invention is not particularly limited, and a method generally used conventionally can be used. For example, the polyester can be melted by an extruder, extruded into a film, cooled by a rotary cooling drum to obtain an unstretched film, and obtained by biaxially stretching the unstretched film. A biaxially stretched film can be obtained by sequentially biaxially stretching a longitudinally or transversely uniaxially stretched film in the transverse direction or longitudinal direction, or by simultaneously biaxially stretching an unstretched film in the longitudinal direction and transverse direction. It can.

  In the present invention, the stretching temperature at the time of stretching the polyester film is preferably at least the secondary transition point (Tg) of the polyester. It is preferable to stretch 1 to 8 times, particularly 2 to 6 times in the longitudinal and transverse directions.

  The polyester film preferably has a thickness of 12 to 50 μm, more preferably 15 to 38 μm, and still more preferably 19 to 33 μm. If the thickness of the film is 12 μm or more, there is no risk of deformation due to heat at the time of film production, processing steps, and molding, which is preferable. On the other hand, if the thickness of the film is 50 μm or less, the amount of the film discarded after use is not extremely large, which is preferable in reducing the environmental load.

  The polyester film substrate may be a single layer or a multilayer of two or more layers, but is preferably a laminated film having a surface layer A substantially free of inorganic particles on at least one side. . In the case of a laminated polyester film having a multilayer structure of two or more layers, it is preferable to have a surface layer B capable of containing inorganic particles and the like on the opposite surface of the surface layer A substantially not containing inorganic particles. Assuming that the layer to which the release layer is applied is layer A, the layer on the opposite side is layer B, and the core layer other than these layers is layer C, the layer configuration in the thickness direction is release layer / A /. B, or a laminated structure of release layer / A / C / B or the like. Naturally, the C layer may have a plurality of layer configurations. The surface layer B can also contain no inorganic particles. In that case, it is preferable to provide a coat layer containing at least inorganic particles and a binder on the surface layer B in order to impart slipperiness for winding the film into a roll.

  In the polyester film substrate in the present invention, it is preferable that the surface layer A forming the surface to which the release layer is applied does not substantially contain inorganic particles. At this time, the area average surface roughness (Sa) of the surface layer A is preferably 7 nm or less. It is preferable that occurrence of pinholes and the like does not easily occur at the time of molding of the laminated ultrathin ceramic green sheet that Sa is 7 nm or less. The area average surface roughness (Sa) of the surface layer A is preferably as small as possible, but may be 0.1 nm or more. Here, when providing the below-mentioned anchor coat layer etc. on surface layer A, it is preferable that an inorganic particle is not included in a coat layer substantially, and the field surface average roughness (Sa) after coat layer lamination is the above-mentioned range Is preferred. In the present invention, "substantially free of inorganic particles" means that the inorganic particles are 50 ppm or less, preferably 10 ppm or less, most preferably the detection limit or less when the inorganic element is quantified by fluorescent X-ray analysis. It means the content. This is because, even if the inorganic particles are not positively added to the film, contamination components derived from extraneous foreign matter, stains attached to the lines and devices in the manufacturing process of the raw material resin or the film are peeled off and mixed in the film. It is because there is a case.

  In the polyester film substrate according to the present invention, the surface layer B forming the opposite surface of the surface to which the release layer is applied preferably contains inorganic particles from the viewpoint of film slipperiness and ease of removal of air, In particular, silica particles and / or calcium carbonate particles are preferably used. It is preferable that the inorganic particle content to be contained is 5000 to 15000 ppm in total of the inorganic particles in the surface layer B. At this time, it is preferable that the area | region surface average roughness (Sa) of the film of surface layer B is the range of 1-40 nm. More preferably, it is in the range of 5 to 35 nm. When the total amount of silica particles and / or calcium carbonate particles is 5000 ppm or more and Sa is 1 nm or more, air can be uniformly released when the film is rolled up, and the winding appearance is good and flatness is good. And ultra-thin ceramic green sheets. In addition, when the total of silica particles and / or calcium carbonate particles is 15000 ppm or less and Sa is 40 nm or less, aggregation of the lubricant is difficult to occur and coarse projections can not be made, so the quality is stable at the time of manufacturing ceramic green sheet of ultrathin layer. Preferred.

  In addition to silica and / or calcium carbonate, inactive inorganic particles and / or heat-resistant organic particles can be used as the particles contained in the above-mentioned B layer, but from the viewpoint of transparency and cost, silica particles and / or More preferably, calcium carbonate particles are used. Moreover, as inorganic particles which can be used, alumina-silica composite oxide particles, hydroxyapatite particles and the like can be mentioned. Further, as the heat resistant organic particles, crosslinked polyacrylic particles, crosslinked polystyrene particles, benzoguanamine particles and the like can be mentioned. When silica particles are used, porous colloidal silica is preferable, and when calcium carbonate particles are used, light calcium carbonate which has been surface-treated with a polyacrylic acid-based polymer compound is preferable from the viewpoint of preventing the slippage of the lubricant. .

  The average particle diameter of the inorganic particles added to the surface layer B is preferably 0.1 μm to 2.0 μm and particularly preferably 0.5 μm to 1.0 μm. If the average particle diameter of the inorganic particles is 0.1 μm or more, the slipperiness of the release film is good, which is preferable. In addition, if the average particle diameter is 2.0 μm or less, there is no possibility that pinholes occur in the ceramic green sheet due to the coarse particles on the surface of the release layer, which is preferable.

  The surface layer B may contain two or more kinds of particles different in material. Further, particles of the same type but different in average particle diameter may be contained.

  In the case where the surface layer B does not contain particles, it is preferable that the coat layer containing the particles on the surface layer B have lubricity. The present coating layer is not particularly limited, but is preferably provided by in-line coating which is applied during film formation of a polyester film. When the surface layer B does not contain particles but has a coat layer containing particles on the surface layer B, the surface of the coat layer is an area for the same reason as the area average roughness (Sa) of the above-mentioned surface layer B. The surface average roughness (Sa) is preferably in the range of 1 to 40 nm. More preferably, it is in the range of 5 to 35 nm.

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

  It is preferable that the thickness ratio of surface layer A which is a layer at the side which provides the said mold release layer is 20% or more and 50% or less of the total layer thickness of a base film. If it is 20% or more, the influence of particles contained in the surface layer B or the like is not easily received from the inside of the film, and the area surface average roughness Sa easily meets the above range, which is preferable. The use ratio of the reproduction | regeneration raw material in surface layer B can be increased as it is 50% or less of the thickness of the whole layer of a base film, an environmental impact is small and preferable.

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

  In addition, a film after stretching or uniaxial stretching in the film forming process on the surface of the surface layer A and / or the surface layer B in order to improve adhesion of a release layer applied later or to prevent charging etc. May be provided with a coating layer, or may be subjected to corona treatment or the like.

(Release layer)
The release layer in the present invention is a radical curable substance (a) having a radical curable functional group selected from a (meth) acryloyl group and an alkenyl group, a thiol group-containing compound (b), a release agent (c), It is preferable to cure the composition containing the radical initiator (d). It can be added in addition to the resin and the additives as long as the function of the present invention is not impaired. Here, in the present invention, the radical curable substance (a) and the thiol group-containing compound (b) are considered to have changed in the structure of the compound after being cured in the coating layer, but changed As it is extremely difficult to accurately express and describe the structure itself, as described above, a “radically curable substance having a radically curable functional group selected from a (meth) acryloyl and an alkenyl group (a releasing layer (a ), The composition containing the thiol group-containing compound (b), the releasing agent (c) and the radical initiator (d) is cured.

(Radical curable substance (a))
The radical curable substance (a) preferably has a radical curable functional group selected from a (meth) acryloyl group and an alkenyl group, and at least one type has two or more radical curable functional groups. You may use. In radical curing, since the reaction rate is very fast, the polymerization reaction proceeds instantaneously simultaneously with the cleavage of the radical initiator, and a coating film with a high crosslink density can be formed. By increasing the crosslink density of the release layer, the release layer can be made to have a high elastic modulus, deformation of the release layer is difficult at the time of peeling of the ceramic green sheet, and the ceramic green sheet can be peeled uniformly with low peeling force. The term "alkenyl group" as used in the present invention refers to an alkenyl group having 2 to 10 carbon atoms, such as a vinyl group, an allyl group, a propenyl group and a hexenyl group.

  The number of radically curable functional groups is preferably 3 or more from the viewpoint of increasing the crosslinking density, more preferably 6 or more, and still more preferably 9 or more. There is no particular upper limit to the number of functional groups, but it is preferably 20 or less. By setting the ratio to 20 or less, the intramolecular reaction is more likely to progress than the crosslinking reaction between molecules, and the effect of improving the elastic modulus of the releasing layer can be obtained efficiently, which is preferable.

Examples of radical curable substances include acrylates, methacrylates, urethane acrylates, acrylamides, allyl compounds, methallyl compounds and maleimide compounds.
From the viewpoint of reactivity, acrylates, methacrylates, urethane acrylates, allyl compounds and methallyl compounds are preferable, and acrylates, methacrylates and urethane acrylates are most preferable. Although acrylates and methacrylates have a relatively large cure shrinkage, in the present invention, since the film thickness can be reduced, appearance defects such as curling may not occur, and they can be suitably used. From the viewpoint of curling, urethane acrylate is most suitable because of its small cure shrinkage.

  The radical curable substance to be used may be a monomer, an oligomer or a polymer, but it is preferable to use a monomer or an oligomer from the viewpoint of solubility in organic solvents and handleability. These may be used alone or in combination of two or more.

  When a monomer is used as (meth) acrylate, for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol Examples include tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethoxylated isocyanurate tri (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate and the like.

  When an oligomer is used as the (meth) acrylate, for example, polyfunctional (meth) acrylate oligomers, polyester acrylate oligomers, epoxy acrylate oligomers, polyether acrylate oligomers, polybutadiene acrylate oligomers, silicone acrylate oligomers, etc. may be mentioned. .

  The urethane acrylate used in the present invention refers to one having a urethane bond and at least one radically curable functional group selected from an acryloyl group and a methacryloyl group in a molecular chain. The synthesis method is not particularly limited, but can be obtained, for example, by the reaction of a polyhydric alcohol and an organic polyisocyanate with a hydroxy acrylate.

  Examples of the polyhydric alcohol include neopentyl glycol, 3-methyl-1,5-pentanediol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane and pentaerythritol. Tricyclodecanedimethylol, bis- [hydroxymethyl] -cyclohexane, etc .; the above polyhydric alcohols and polybasic acids (eg, succinic acid, phthalic acid, hexahydrophthalic anhydride, terephthalic acid, adipic acid, azelaic acid, tetrahydroanhydride) Polyester polyols obtained by the reaction with phthalic acid, etc .; polycaprolactone polyols obtained by the reaction of the above polyhydric alcohol with ε-caprolactone; polycarbonate polyols (eg, 1,6-hexanediol) Polycarbonate diols obtained by the reaction of phenyl carbonate); and, like the polyether polyol. Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene oxide modified bisphenol A and the like.

  Examples of the organic polyisocyanate include isophorone diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, xylene diisocyanate, isocyanate compounds such as diphenylmethane-4,4'-diisocyanate and dicyclopentanyl isocyanate, adducts of these isocyanate compounds, or these The polymer of isocyanate etc. are mentioned.

  Examples of the above-mentioned hydroxy (meth) acrylate compound include pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, hydroxyethyl (meth) And the like) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, dimethylol cyclohexyl mono (meth) acrylate, hydroxycaprolactone (meth) acrylate and the like. Among them, pentaerythritol tri (meth) acrylate and dipentaerythritol penta (meth) acrylate are preferable from the viewpoint of hardness.

  As the urethane acrylate used in the present invention, commercially available ones can also be used. Examples of commercially available products include: Nippon Synthetic Chemical Industry Co., Ltd .: UV 1700 B (10 functions), UV 7620 EA (9 functions), UV 7610 B (9 functions), UV 7600 B (6 functions), UV 7650 B (5 functions), Nippon Kayaku Co., Ltd .: DPHA 40 H (10 functions), UX 5003 (6 functions), manufactured by Arakawa Chemical Industries, Ltd .: Beam set 577 (6 functions), manufactured by Taisei Fine Chemicals: 8UX-015A (15 functions), and Shin Nakamura Chemical Industries, Ltd .: U15 HA (15 Sensuality) etc. can be mentioned.

  The compound having an alkenyl group to be used for the release layer of the present invention is not particularly limited, and general compounds can be suitably used. As an example of what is marketed, the Nippon Chemical Industries Co., Ltd. product: TAIC (registered trademark) triallyl isocyanurate (trifunctional), the Shikoku Kasei Co., Ltd. product: LDAIC (bifunctional), TA-G (tetrafunctional), DD-1 (4 functions) etc. are mentioned.

(Thiol group-containing compound (b))
The release layer in the present invention preferably contains a thiol group-containing compound. Since the thiol group-containing compound acts as a curing accelerator for radical polymerization reaction, it is less susceptible to oxygen inhibition and exhibits excellent reactivity even in the atmosphere. Therefore, it is preferable because the curability of the surface of the release layer can be increased and the solvent resistance can be improved. Moreover, since oxygen inhibition is suppressed, even if the release layer is made thin, it is preferable because solvent resistance does not deteriorate and peeling does not occur. Furthermore, the addition of a thiol group-containing compound proceeds with a radical curable functional group, so that the compound is incorporated into the cross-linked structure of the radical curable substance, and a flexible structure derived from the thiol group-containing compound is introduced into the cured product. For this reason, even if the film thickness of the release layer is large, the curing shrinkage which is a problem unique to radical curable substances is suppressed, and the thickness unevenness of the ceramic green sheet occurs during the formation of the ceramic green sheet, and the electrode printing accuracy is lowered. There is no risk of causing

  When a coating film containing a radically curable substance is cured in the air, since the polar groups such as hydroxyl groups and carboxyl groups are formed on the surface by oxygen inhibition, the wettability of the ceramic slurry is improved. When a coating film containing a radically curable substance is cured in an inert gas atmosphere, the effect of inhibiting oxygen inhibition is large and the surface curability can be enhanced, but on the other hand, the wettability of the ceramic slurry is poor. As a result, there is a problem that repelling and pinholes are easily generated in the molded ceramic green sheet. The thiol group-containing compound is preferable because it can simultaneously exhibit two contradictory effects of improvement of surface hardness and improvement of wettability by oxygen inhibition.

  Further, by forming a release layer composed of a cured product containing a thiol group-containing compound, S atoms are introduced into the release layer, so that the affinity with the molded ceramic green sheet is improved. Therefore, the ceramic green sheet is less likely to float during conveyance, and generation of defects can be suppressed, which is preferable.

  The thiol group-containing compound is not particularly limited and general ones are used, but it is preferable that the compound does not contain a radically curable functional group selected from (meth) acryloyl group and alkenyl group. By using the thiol group-containing compound not having a radical curable functional group, radical curable functional groups in the same molecule preferentially react with each other than a thiol group acting as a curing accelerator, and oxygen There is no fear that the inhibitory effect can not be obtained, which is preferable. The term "thiol group-containing compound" as used in the present invention refers to an organic compound having a hydrogenated sulfur atom at its terminal, and is synonymous with a compound called thioalcohol. Moreover, a thiol group may be called a mercapto group and a sulfhydryl group.

  The number of functional groups of the thiol group-containing compound is preferably 2 or more, more preferably 3 or more, and most preferably 4 or more. When the number of functional groups is two or more, a radical curable substance and a crosslinked structure can be easily obtained, and the effect of inhibiting oxygen inhibition can be easily obtained, which is preferable.

  Examples of the thiol group-containing compound include 1,4-bis (3-mercaptobutyryloxy) butane, tetraethylene glycol bis (3-mercaptopropionate) 1,3,5-tris (3-mercaptobutyryloxy). Ethyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, trimethylolpropane tris (3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)- Ethyl] -isocyanurate, pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutyrate), dipentaerythritol hexakis (3-mercaptopropionate) and the like.

  A commercially available thing can be suitably used for a thiol group containing compound, respectively. For example, Kalores MT (registered trademark) BD1 (bifunctional), NR1 (trifunctional), PE1 (tetrafunctional), SC Organic Chemical Co .: TMMP (trifunctional), TEMPIC (trifunctional) manufactured by Showa Denko KK PEMP (4 functional), EGMP-4 (4 functional) DPMP (6 functional), etc. can be mentioned.

  As the thiol group-containing compound, whether it is a polymer, an oligomer or a monomer can be suitably used, but the monomer is most preferable. The molecular weight is preferably 10000 or less, and most preferably 1000 or less. By setting the molecular weight to 10000 or less, the number of thiol groups per constant mass is preferable because the number is sufficient to obtain the effect of promoting radical curing.

  The content of the thiol group-containing compound contained in the release layer is preferably 1 to 30% by mass or less, and more preferably 2 to 25% by mass or less based on the solid content of the entire release layer. Preferably, it is 5 to 20% by mass or less. By setting the content of the thiol group-containing compound to 1% by mass or more, it is preferable because the radical curing reaction is promoted and the effect of being hard to receive oxygen inhibition is sufficiently obtained. By setting the content to 30% by mass or less, the cured product is not too soft due to the thiol group-containing compound, and the effect of improving the elastic modulus by crosslinking between radical curable substances is obtained, which is preferable.

(Release agent (c))
As a mold release agent (additive for imparting mold releasability) used in the mold release layer in the present invention, silicone type additives, non-silicone type additives such as fluorine type, long chain alkyl type, olefin type, etc. Can be suitably used.

  The silicone-based additive is a material having a polyorganosiloxane in which an organic group is attached to a siloxane bond, and is not particularly limited as long as the effects of the present invention can be obtained, and a general one may be used. Can. Among polyorganosiloxanes, dialkylsiloxanes can be suitably used. Among them, dimethylsiloxane is more preferably used, and one having a functional group in part of dimethylsiloxane is more preferable. By having a functional group, intermolecular interaction such as a hydrogen bond and the like with a radical curable substance is likely to be developed, and migration to a ceramic green sheet is less likely to occur, which is preferable.

  The functional group to be introduced into polydimethylsiloxane is not particularly limited, and may be either a reactive functional group or a non-reactive functional group. The functional group may be introduced to one end of polydimethylsiloxane, or may be both ends or side chains. In addition, one or more positions may be introduced.

  As a reactive functional group introduced into polydimethylsiloxane, a hydroxy group, a carboxyl group, a (meth) acryloyl group, an alkenyl group, a thiol group or the like can be used. Among them, it is preferable to have a radically curable functional group such as a (meth) acryloyl group, an alkenyl group or a thiol group. By using polydimethylsiloxane having a radically curable functional group, a crosslinked structure can be obtained with the radically curable substance (a) or the thiol group-containing compound (b), and it is difficult to cause a transition to a ceramic green sheet. preferable. From the viewpoint of solvent resistance, the larger the number of reactive functional groups, the easier it is to obtain a crosslinked structure, which is preferable. In addition, the radically curable functional group shown here points out the functional group which can become a crosslinking point in radical curing reaction, such as a (meth) acryloyl group and an alkenyl group.

  As a non-reactive functional group to be introduced into polydimethylsiloxane, a polyether group, an alkyl group, a fluoroalkyl group, a long chain alkyl group, an ester group, an amide group, a phenyl group or the like can be used.

  As the silicone component, it is particularly preferable to use a polydimethylsiloxane-modified resin such as an acrylic resin, a polyester resin, or a urethane resin having polydimethylsiloxane in the side chain. The polydimethylsiloxane-modified resin is preferable because it has good compatibility with the radical curable substance and can form a uniform release layer as compared with other general release agents, and the releasability is improved. In addition, it is preferable because an interaction between the radical curable substance and the molecule is easily developed and the solvent resistance is improved. Furthermore, it is preferable because migration of the release agent to the ceramic green sheet is less likely to occur at the time of peeling. Among polydimethylsiloxane modified resins, it is preferable to use polydimethylsiloxane modified resin having a radical curable functional group. The polydimethylsiloxane modified resin having a radically curable functional group is preferable because it can have a cross-linked structure with the radically curable substance (a) and the thiol group-containing compound (b), and thus the solvent resistance is further improved.

  As an example of a commercial item of acrylic resin which has a polydimethylsiloxane skeleton in a side chain, Cymac (registered trademark) US 350, Cymac (registered trademark) US 352, (manufactured by Toagosei Co., Ltd.), 8BS-9000 (manufactured by Taisei Fine Chemical Co., Ltd.) GL-01, GL-03R (made by Kyoeisha Chemical Co., Ltd.) etc. are mentioned. Examples of commercially available acrylic resins having a polydimethylsiloxane skeleton and a radical curable functional group in the side chain include 8SS-723 (manufactured by Taisei Fine Chemical Co., Ltd.), GL-02, GL-04R (manufactured by Kyoeisha Chemical Co., Ltd.), etc. Can be mentioned.

  The fluorine-based additive is not particularly limited, and an existing one can be used. For example, those having a perfluoro group or those having a perfluoroether group can be suitably used. It is preferable to have a functional group for the same reason as the silicone-based additive, and more preferable to have a radical curable functional group. As a commercial item, 8FX-038EX (made by Taisei Fine Chemical Co., Ltd.), Optool (registered trademark) (made by Daikin Industries, Ltd.), Megafuck (registered trademark) RS-72-K, RS-75, RS-78 (all, above, DIC) Products), FS Coat (registered trademark) UT-UCH23 (manufactured by AGC Seimi Chemical Co., Ltd.), EBECRYL (registered trademark) 8110 (manufactured by Daicel Ornex Co., Ltd.), F Clear (registered trademark) (manufactured by Kanto Denka Kogyo Co., Ltd.) Be

  As long-chain alkyl additives, long-chain alkyl-modified resins can be used, and those having an alkyl group having about 8 to 20 carbon atoms in its side chain, such as polyvinyl alcohol or acrylic resin, are preferable. Moreover, it is a polymer which has (meth) acrylic acid ester as a main repeating unit, and the copolymer which contains a C8-C20 long-chain alkyl group in the transesterified part can also be used conveniently. Further, octyl acrylate, lauryl acrylate, stearyl acrylate and the like in which an acrylate group is attached to long chain alkyl can also be suitably used.

  Examples of commercially available long-chain alkyl-based additives include Peyrol (registered trademark) 1010, 1050, 1070 (all manufactured by Lion Specialty Chemicals), Tesfine (registered trademark) 305, 314 (all manufactured by Hitachi, Ltd.). And the like.

  The olefin additive is not particularly limited and a general one can be used. For example, polybutadiene and cycloolefin resins can be suitably used. Commercially available products include NISSO-PB (registered trademark) B series, G series, JP series (hereinafter, manufactured by Nippon Soda Co., Ltd.), ARTON (registered trademark) (manufactured by JSR Corporation), and the like.

  Moreover, you may mix and use 2 or more types of the said mold release agent. At this time, although not particularly limited by theory, it is better to use two types having different functional groups in terms of releasability, and it is more preferable to contain a reactive functional group.

  It is preferable that the release agent (c) is contained in the release layer in the present invention at 0.05% by mass or more and 20% by mass or less based on the solid content of the entire release layer. More preferably, it is 0.1 mass% or more and 10 mass% or less, and still more preferably 0.1 mass% or more and 5 mass% or less. By making the amount more than 0.1% by mass, releasability is imparted, and there is no possibility that the removability of the ceramic green sheet may be deteriorated, which is preferable. When the amount is less than 20% by mass, repelling is less likely to occur when the ceramic slurry is coated, and there is no possibility of uneven thickness in the ceramic green sheet.

(Radical initiator (d))
It is preferable to use a radical initiator in the release layer in the present invention in order to advance a radical curing reaction. As a radical initiator, either a thermal radical initiator or a photo radical initiator can be suitably used, but using a photo radical initiator is preferable because the amount of heat during processing can be suppressed. The initiator used may be of one type or two or more types, and the photo radical initiator and the thermal radical initiator may be used simultaneously.

  The radical initiator is not particularly limited, and a general one can be used. Specific examples include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, methyl benzoin benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloroanthraquinone, (2,4,6-trimethylbenzyldiphenyl) phosphine Oxides, 2-benzothiazole-N, N-diethyldithiocarbamate and the like.

  As the radical initiator, α-hydroxyalkylphenone and α-aminoalkylphenone, which are considered to be particularly excellent in surface curability, can be suitably used to suppress oxygen inhibition. Examples of α-hydroxyalkylphenone include 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl}- 2-Methylpropan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl- 1-propan-1-one etc. are mentioned. Examples of α-aminoalkylphenones include 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopro. Pan-1-one, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone and the like can be mentioned.

  When a photo radical initiator is used, the addition of a sensitizer accelerates the absorption of active energy rays and can further improve the curability. The sensitizer is not particularly limited and general ones are used, but anthracene derivative and naphthalene derivative are preferable. The sensitizer may be used alone or in combination of two or more.

  The addition amount of the radical initiator is preferably 0.1% by mass or more and 20% by mass or less with respect to the total solid content in the release layer, and is 0.5% by mass or more and 10% by mass or less Is more preferable, and 1% by mass or more and 8% by mass or less is the most preferable. By setting the content to 0.1% by mass or more, the amount of generated radicals is insufficient, which is preferable because there is no possibility of insufficient curing. By setting the content to 20 parts by mass or less, the amount of the residue of the radical initiator contained in the release layer can be reduced, and it is possible to suppress a decrease in releasability and a transition to a ceramic green sheet to be molded.

  The addition amount of the sensitizer is preferably 0.1 to 5 times by mass with respect to the photo radical initiator. More preferably, it is preferably 0.1 to 2 times. If it is larger than 0.1 times, it is preferable because a sufficient sensitization effect can be obtained. When it is smaller than 5 times, absorption of the active energy ray of the photo radical initiator is inhibited, and the amount of the generated radicals is preferable without causing a shortage.

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

  An adhesion improver, an additive such as an antistatic agent, or the like may be added to the release layer in the present invention as long as the effects of the present invention are not impaired. Further, in order to improve the adhesion to the substrate, it is also preferable to subject the polyester film surface to pretreatment such as anchor coating, corona treatment, plasma treatment, atmospheric pressure plasma treatment or the like before the release coating layer is provided.

  In the present invention, the thickness of the release layer may be set according to the purpose of use and is not particularly limited, but preferably, the range in which the release coated layer after curing is 0.01 to 0.5 μm is good More preferably, it is 0.05-0.4 micrometer, and it is more preferable if it is 0.1-0.4 micrometer. In particular, when a release layer is provided on the surface layer A of a polyester film having a surface layer A substantially free of inorganic particles, the cost of the coating material decreases if the thickness of the release layer is thinner. , Economical, and preferable because curling can be suppressed. Specifically, it is preferably 0.4 μm or less, and more preferably 0.3 μm or less. When the thickness of the release layer is thicker than 0.01 μm, sufficient release performance is obtained, which is preferable. When the thickness is smaller than 0.5 μm, curling of the release film due to curing and shrinkage is unlikely to occur, and therefore, there is no possibility of causing unevenness in thickness of the ceramic green sheet or lowering of electrode printing accuracy.

  The surface of the release layer of the release film of the present invention is preferably flat so as not to cause defects in the ceramic green sheet applied and molded thereon, and the area surface average roughness (Sa) is 7 nm or less Is preferred. Further, it is more preferable that the above-mentioned Sa is satisfied, and the maximum projection height (P) on the surface of the releasing layer is 100 nm or less. It is particularly preferable that the area surface average roughness (Sa) is 5 nm or less and the maximum projection height is 80 nm or less. If the area surface roughness is 7 nm or less, defects such as pinholes do not occur at the time of forming the ceramic green sheet, which is preferable because the yield is good. The smaller the area surface average roughness (Sa) is, the more preferable it is, but it may be 0.1 nm or more, and may be 0.3 nm or more. The smaller the maximum projection height (P), the better, but it may be 1 nm or more, or 3 nm or more.

  The release film of the present invention preferably has a peeling force of 0.5 mN / mm or more and 4.0 mN / mm or less when peeling the ceramic green sheet. More preferably, they are 0.8 mN / mm or more and 3.0 mN / mm or less. When the peeling force is 0.5 mN / mm or more, there is no possibility that the peeling force is too light and the ceramic green sheet may float during transportation, which is preferable. It is preferable that the peeling force is 4.0 mN / mm or less because the ceramic green sheet is not damaged at the time of peeling and no defect occurs.

  The release film of the present invention is preferable because the corrosion resistance of the release layer by the organic solvent at the time of ceramic sheet processing or electrode printing, such as toluene, can be suppressed as the solvent resistance is higher. The solvent resistance can be confirmed by evaluating the difference in the surface state of the release layer before and after the release film is immersed in the organic solvent. As the organic solvent, it is preferable to use toluene that is used for general ceramic slurry and conductive paste, assuming processing of ceramic green sheets and electrode printing. As an example of the method of evaluating the surface state of the release layer, evaluation by a contact angle is mentioned, and the smaller the change in contact angle on the surface of the release layer before and after immersion in toluene, the better.

  The type of liquid drop used to measure the contact angle is not particularly limited, but water, bromonaphthalene, ethylene glycol, etc. can be suitably used, but the difference in the surface state of the release layer should be more clearly seen. Most preferably, diiodomethane is used.

When using diiodomethane as Eki摘used to measure contact angle at room temperature diiodomethane contact angle theta ₁ and the release film of the release layer surface in toluene, the contact angle of the release layer surface after immersion 5 minutes theta _The smaller the value of the difference of ₂ (θ ₁ -θ ₂ ), the better the solvent resistance of the surface of the release layer, which is preferable. Specifically, the absolute value is preferably 3.0 ° or less, more preferably 2.0 ° or less, and most preferably 1.0 ° or less. The erosion of the release layer by the organic solvent at the time of ceramic green sheet processing or electrode printing is suppressed as it is 3.0 degrees or less, and there is no possibility that the increase in exfoliation power or the uniformity of exfoliation will be impaired. The difference (θ ₁ -θ ₂ ) between the diiodomethane contact angle θ ₁ on the release layer surface and the contact angle θ ₂ of the release layer surface after immersion of the release film in toluene for 5 minutes at room temperature is most preferably 0 ° The absolute value may be 0.05 ° or more, or 0.1 ° or more.

  It is preferable that the release film of the present invention has less curl. When the curl is small, the uniformity at the time of coating and molding of the ceramic green sheet is deteriorated, and there is no possibility that the film thickness of the ceramic green sheet becomes nonuniform, which is preferable. Moreover, there is no possibility that printing accuracy may fall in an electrode printing process, and it is preferable. Furthermore, at the time of roll conveyance, the tension of the release film is less likely to be different at the film central portion and the end portion, and there is no possibility that the appearance quality such as meandering or winding deviation during conveyance is deteriorated.

(Method of forming release layer)

  In the present invention, the method for forming the release layer is not particularly limited, and a coating liquid in which a composition containing a releasable resin or the like is dissolved or dispersed is applied to one surface of the polyester film of the substrate by coating etc. After removing the solvent and the like by drying, heating and drying, a method of curing by irradiation of active energy rays or heat is used.

  When curing is carried out using a photo radical initiator, the drying temperature of solvent drying is preferably 50 ° C. or more and 100 ° C. or less, and more preferably 60 ° C. or more and 95 ° C. or less. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less. When the temperature is 100 ° C. or less, the thermal load on the film is suppressed, appearance defects due to thermal contraction of the film are unlikely to occur, and the possibility of causing thickness unevenness of the ceramic green sheet is small, which is preferable. When the temperature is 95 ° C. or less, the thermal load on the film is further reduced, the film can be processed without impairing the flatness of the film, and the possibility of causing thickness unevenness of the ceramic green sheet is further reduced, which is particularly preferable. When the temperature is higher than 50 ° C., drying of the dilution solvent used at the time of application becomes insufficient, and there is no possibility of process contamination and the like, which is preferable.

As an active energy ray used to react a radical curable substance with a photo radical initiator, ultraviolet rays, electron rays, X-rays and the like can be used, but ultraviolet rays are preferred because they are easy to use. As an ultraviolet-ray amount to irradiate, 30-300 mJ / cm < ² > is preferable in integral light quantity, More preferably, it is 30-200 mJ / cm < ² >. By setting it as 30 mJ / cm ² or more, curing of the resin proceeds sufficiently, which is preferable. Since the speed at the time of processing can be improved by setting it as 300 mJ / cm < ² > or less, since a release film can be created economically, it is preferable.

The atmosphere for irradiating the active energy ray may be an inert gas atmosphere such as nitrogen or argon, but is preferably in general air. In the present invention, by using a thiol group-containing compound, it is possible to obtain a release layer which is excellent in the curability of the surface of the release layer even when irradiated in air and is also excellent in the wettability of the ceramic slurry. In addition, it is superior in terms of processing cost to that performed under an inert gas atmosphere, and is preferable from the economical point of view.

  In the present invention, the surface tension of the coating liquid when the release layer is applied is not particularly limited, but is preferably 30 mN / m or less. By setting the surface tension as described above, the coating property after coating can be improved, and unevenness on the surface of the coated film 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 more. By adding a solvent having a boiling point of 90 ° C. or more, bumping during drying can be prevented, the coating film can be leveled, and the smoothness of the surface of the coating film after drying can be improved. It is preferable to add about 10-80 mass% with respect to the whole coating liquid as the addition amount.

  Any known coating method can be applied as the coating method of the above coating solution, for example, roll coating such as gravure coating or reverse coating, bar coating such as wire bar, die coating, spray coating, air knife A conventionally known method such as a coating method can be used.

(Ceramic green sheet and ceramic capacitor)
In general, a laminated 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 inner 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 inner electrode is electrically connected to the first outer electrode at the first end face. The second inner 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 inner electrode is electrically connected to the second outer electrode at the second end face.

  The release film for producing a ceramic green sheet of the present invention is used to produce such a multilayer ceramic capacitor. For example, it is manufactured as follows. First, using the release film of the present invention as a carrier film, a ceramic slurry for forming a ceramic body is applied and dried. As for the thickness of the ceramic green sheet, a very thin product of 0.2 to 1.0 μm has been required. A conductive layer for forming a first or second internal electrode is printed on the coated and dried ceramic green sheet. The ceramic green sheet, the ceramic green sheet on which the conductive layer for forming the first internal electrode is printed, and the ceramic green sheet on which the conductive layer for forming the second internal electrode is printed are appropriately laminated and pressed. Thus, a mother laminate is obtained. The mother laminate is divided into a plurality of pieces to prepare a green ceramic body. A ceramic body is obtained by firing a green ceramic body. Thereafter, the laminated ceramic capacitor can be completed by forming the first and second external electrodes.

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

(Inherent viscosity of polyester resin (dl / g))
It measured at 30 degreeC using the mixed solvent of a phenol (60 mass%) and 1,1,2,2- tetrachloroethane (40 mass%) as a solvent according to JISK7367-5.

(Base film thickness)
Using a Millitron (electronic micro indicator), 4 pieces of 5 cm square samples were cut out from any 4 parts of the film to be measured, and 5 pieces of each sample (20 pieces in total) were measured to obtain an average value as a thickness.

(Release layer thickness)
The cut release film was resin-embedded and ultrathin-sectioned using an ultramicrotome. Thereafter, using a JEM 2100 transmission electron microscope manufactured by Nippon Denshi K.K., observation was directly performed at a magnification of 20,000 times, and the film thickness of the releasing layer was measured from the observed TEM image.

(Area surface roughness Sa, maximum projection height P)
It is the value measured on condition of the following using the non-contact surface shape measurement system (the Ryoka system company make, VertScan R550H-M100). The area surface average roughness (Sa) was an average value of 5 measurements, and the maximum projection height (P) was 7 measurements, and the maximum value of 5 values excluding the maximum value and the minimum value was used.
(Measurement condition)
・ Measurement mode: WAVE mode ・ Objective lens: 10 times ・ 0.5 × Tube lens ・ Measurement area 936μm × 702μm
(Analysis conditions)
-Face correction: 4th order correction-Interpolation: Complete interpolation

(Pinhole evaluation of ceramic green sheet)
The composition consisting of the following materials was stirred and mixed, and dispersed with zirconia beads of 0.5 mm in diameter for 30 minutes using a bead mill to obtain a ceramic slurry.
Toluene 76.3 parts by mass Ethanol 76.3 parts by mass Barium titanate (HPBT-1 manufactured by Fuji Titanium Co., Ltd.) 35.0 parts by mass Polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd. SLEK (registered trademark) BM-S) 3.5 parts by mass Next, 1.8 parts by mass of DOP (dioctyl phthalate) is applied to the release surface of the obtained release film sample using an applicator so that the dried slurry has a thickness of 0.8 μm and dried at 90 ° C. for 2 minutes Thereafter, the release film was peeled off to obtain a ceramic green sheet. In the central region of the film width direction of the obtained ceramic green sheet, light is applied from the opposite surface of the ceramic slurry application surface in the range of 25 cm ² , and the occurrence of pinholes where light is seen to be transmitted is observed. It judged visually. The measurement was performed 5 times, and the average value was adopted.
:: No occurrence of pinholes ○: Almost no occurrence of pinholes (estimate: no more than 2 pinholes per measurement area)
:: Occurrence of pinholes (estimated: 3 or more, 5 or less pinholes per measurement area)
X: There are many pinholes

(Evaluation of coatability of ceramic slurry)
The composition consisting of the following materials was stirred and mixed, and dispersed with zirconia beads of 0.5 mm in diameter for 30 minutes using a bead mill to obtain a ceramic slurry.
Toluene 76.3 parts by mass Ethanol 76.3 parts by mass Barium titanate (HPBT-1 manufactured by Fuji Titanium Co., Ltd.) 35.0 parts by mass Polyvinyl butyral (Selec BM-S manufactured by Sekisui Chemical Co., Ltd.) 3.5 parts by mass DOP (phthalic acid Dioctyl) 1.8 parts by mass Next, the following standard is applied to the release surface of the release film sample obtained using an applicator so that the dried slurry becomes 0.8 μm and dried at 90 ° C. for 2 minutes. The coatability was evaluated.
○: No coating was done and coating was possible on the entire surface.
Fair: There is some repelling at the coating end, but coating is possible on almost the entire surface.
X: Repelling has occurred even at the coating end, and coating has not been performed on the entire surface.

(Evaluation of peelability of ceramic green sheet)
The composition consisting of the following materials was stirred and mixed, and dispersed with zirconia beads of 0.5 mm in diameter for 60 minutes using a bead mill to obtain a ceramic slurry.
Toluene 38.3 parts by mass Ethanol 38.3 parts by mass Barium titanate (HPBT-1 manufactured by Fuji Titanium Co., Ltd.) 64.8 parts by mass Polyvinyl butyral 6.5 parts by mass (S-Rec (registered trademark) BM-S manufactured by Sekisui Chemical Co., Ltd. )
DOP (dioctyl phthalate) 3.3 parts by mass Then, an applicator was used to apply a thickness of 10 μm to the release surface of the release film sample, and dried for 2 minutes at 90 ° C. The sheet was molded on a release film. The obtained release film with a ceramic green sheet was cut into a width of 30 mm and a length of 80 mm, and used as a sample for measurement of peel force. After removing electricity using an electric discharge machine (manufactured by KEYENCE CORPORATION, SJ-F020), using a peeling tester (VPA-3 manufactured by Kyowa Interface Science), peeling angle 90 °, peeling temperature 25 ° C., peeling speed 10 m / It peeled in min. As a peeling direction, a double-sided adhesive tape (Nitto Denko Co., Ltd., No. 535A) is stuck on a SUS plate attached to a peeling tester, and a release film is formed by bonding the ceramic green sheet side to the double-sided tape on it. Were fixed and peeled off in the form of pulling the release film side. The average value of the peeling force of 20 mm-70 mm of peeling distances was computed among the obtained measured values, and the value was made into peeling force. The measurement was performed a total of five times, and the value of the average value of the peeling force was adopted and evaluated. From the numerical value of the peeling force obtained, it was judged according to the following criteria.
◎: Peeling was possible with a very light force of 2.0 mN / mm or less.
:: Peeling force was greater than 2.0 mN / mm, and peeling was possible with a relatively light force of 3.0 mN / mm or less.
Fair: Peeling force was greater than 3.0 mN / mm, and peeling was possible with a light force of 4.0 mN / mm or less.
X: Peeling force required a force greater than 4.0 mN / mm.

(Curl evaluation of release film)
The release film sample was cut into a size of 10 cm × 10 cm, and heat treatment was performed at 90 ° C. for 1 minute in a hot air oven without tension applied to the release film. Then, after taking out from oven and cooling to room temperature, the release film sample was placed on the glass plate so that the release surface was on the top, and the height of the part floating from the glass plate was measured. At this time, the height of the part which floated the largest from the glass plate was taken as the measurement value. The curling was evaluated based on the following criteria.
◎: The curl was 1 mm or less and hardly curled ○: The curl was larger than 1 mm and 2 mm or less, and a slight curl was observed.
Δ: The curl was larger than 2 mm and smaller than 4 mm, and curl was observed.
X: The curl was larger than 4 mm.

(Contact angle)
The amount of diiodomethane (droplet amount) on the release surface of the release film which was allowed to stand using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., fully automatic contact angle meter DM-701) under conditions of 25 ° C. and 50% RH. Drops of 0.9 μL) were prepared and their contact angles were measured. As the contact angle, the contact angle after 30 seconds after dropping on the release film was adopted, and the average value of the values measured five times was adopted.

(Contact angle after immersion in toluene)
The release film used for the measurement was cut into a size of 5 cm × 5 cm, and immersed in a glass tray containing 30 mL of toluene having a liquid temperature of 25 ° C. for 5 minutes with the release surface down. The dipped release film was taken out, air-dried with the release surface facing upward for 15 minutes, and then vacuum-dried at 25 ° C. overnight. The release film after immersion in toluene thus obtained was measured by the same method as the measurement method of the contact angle.

(Evaluation of contact angle change)
When the diiodomethane contact angle of the initial release layer surface before toluene immersion is measured by the above method is θ ₁ , and the diiodomethane contact angle of the release layer surface after toluene immersion is θ ₂ , θ ₁ -θ ₂ The absolute value was taken as the value of the contact angle change before and after immersion in toluene. The change of the contact angle was evaluated on the basis of the following criteria.
:: | θ ₁ −θ ₂ | <1.0 °
○: 1.0 ° ≦ | θ ₁ −θ ₂ | <2.0 °
Δ: 2.0 ° ≦ | θ ₁ −θ ₂ | ≦ 3.0 °
×: | θ ₁ −θ ₂ |> 3.0 °

(Preparation of polyethylene terephthalate pellets (PET (I)))
As an esterification reaction apparatus, a continuous esterification reaction apparatus was used which was composed of a three-stage complete mixing tank having a stirrer, a partial condenser, a raw material feed port and a product outlet. TPA (terephthalic acid) is 2 tons / hour, EG (ethylene glycol) is 2 moles with respect to 1 mole of TPA, antimony trioxide is produced in an amount such that 160 ppm of Sb atoms are formed with respect to PET, and these slurries are ester The reaction mixture was continuously fed to the first esterification reactor of the esterification reactor, and reacted at 255 ° C. for 4 hours at an average residence time under normal pressure. Then, the reaction product in the first esterification reaction vessel is continuously taken out of the system, supplied to the second esterification reaction vessel, and distilled from the first esterification reaction vessel in the second esterification reaction vessel. The EG solution is supplied at 8% by mass with respect to the produced PET, and an EG solution containing magnesium acetate tetrahydrate in an amount of 65 ppm of Mg atoms with respect to the produced PET, and 40 ppm of P atoms with respect to the produced PET An EG solution containing an amount of TMPA (trimethyl phosphate) was added, and the reaction was carried out at 260 ° C. under an atmospheric pressure for an average residence time of 1 hour. Then, the reaction product of the second esterification reaction vessel is continuously taken out of the system, supplied to the third esterification reaction vessel, and 39 MPa (400 kg / cm ² ) using a high pressure disperser (manufactured by Nippon Seiki Co., Ltd.) 0.2% by mass of porous colloidal silica with an average particle size of 0.9 μm dispersed by an average pressure of 5 passes and an average particle with 1% by mass of ammonium salt of polyacrylic acid attached per calcium carbonate While adding 0.4 mass% of synthetic calcium carbonate having a diameter of 0.6 μm as an EG slurry of 10% each, the reaction was carried out at 260 ° C. at an average residence time of 0.5 hours under normal pressure. The esterification reaction product generated in the third esterification reaction vessel was continuously supplied to a three-stage continuous polycondensation reaction apparatus to conduct polycondensation, and a 95% cut diameter sintered a 20 μm stainless steel fiber After filtration with a filter, it was ultrafiltered and extruded in water, and after cooling it was cut into chips to obtain PET chips with an intrinsic viscosity of 0.60 dl / g (hereinafter abbreviated as PET (I)) . The lubricant content in the PET chip was 0.6% by mass.

(Preparation of polyethylene terephthalate pellets (PET (II)))
On the other hand, in the manufacture of the PET chip, a PET chip having an intrinsic viscosity of 0.62 dl / g which does not contain any inorganic particles such as calcium carbonate and silica was obtained (hereinafter referred to as PET (II)).

(Manufacture of laminated film X1)
After drying, these PET chips are melted at 285 ° C., melted at 290 ° C. by a separate melt extruder extruder, and a 95% cut diameter sintered filter of 15 μm stainless steel fibers, 95% cut diameter Two-stage filtration of a filter made of sintered 15 μm stainless steel particles is carried out and merged in a feed block to make PET (I) a surface layer B (reciprocal side layer), PET (II) a surface Layer A (release surface side layer) is laminated, extruded in a sheet shape at a speed of 45 m / min (casting), and electrostatically adhered and cooled on a casting drum at 30 ° C. by an electrostatic adhesion method. An unstretched polyethylene terephthalate sheet having an intrinsic viscosity of 0.59 dl / g was obtained. The layer ratio was adjusted to be PET (I) / PET (II) = 60% / 40% in calculation of the discharge amount of each extruder. Next, this unstretched sheet was heated by 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, it was introduced into a tenter and stretched 4.2 times in the transverse direction at 140 ° C. It was then heat treated at 210 ° C. in the heat setting zone. Thereafter, the film was subjected to a relaxation treatment at 2.3 ° C. in the transverse direction at 170 ° C. to obtain a 25 μm-thick biaxially stretched polyethylene terephthalate film X1. The Sa of the surface layer A of the obtained film X1 was 2 nm, and the Sa of the surface layer B was 29 nm.

(Production of laminated film X2)
The thickness was adjusted by changing the casting speed without changing the layer configuration and the stretching conditions similar to the laminated film X1, to obtain a 22 μm thick biaxially stretched polyethylene terephthalate film X2. In the surface layer A of the obtained film X2, Sa was 3 nm, and Sa of the surface layer B was 29 nm.

(Method of manufacturing laminated film X3)
As laminated film X3, E5101 (Toyobo ester (registered trademark) film, manufactured by Toyobo Co., Ltd.) having a thickness of 25 μm was used. E5101 is the structure which contained the inorganic particle in the film. Sa of the surface layer A of the laminated film X3 was 24 nm, and Sa of the surface layer B was 24 nm.

Example 1
Apply coating solution 1 of the composition shown below on the surface layer A of the laminated film X1 using a wire bar so that the thickness of the release layer after drying is 0.4 μm, and dry at 90 ° C. for 15 seconds After that, ultraviolet rays having a cumulative light quantity of 70 mJ / cm ² (H hereus, LC6B, H bulb) were irradiated in the air to obtain a release film for producing an ultrathin ceramic green sheet. A ceramic slurry was applied to the obtained mold release film, and the surface roughness, mold release property, pinholes, coatability, curling and solvent resistance of the mold release layer were evaluated. As a result, good evaluation results were obtained.
Methyl ethyl ketone 22.40 parts by mass Isopropyl alcohol 67.20 parts by mass Radical curable substance (a): 10-functional urethane acrylate 8.50 parts by mass (Product name: Purple light (registered trademark) UV-1700B, manufactured by Japan Synthetic Chemical Co., Ltd., solid Min 100 mass%)
Thiol group-containing compound (b): 1.00 parts by mass of a tetrafunctional thiol group-containing compound
(Product name: Kalens MT (registered trademark) PE1, manufactured by Showa Denko, solid content 100% by mass)
Release agent (c): Acryloyl group-containing acrylic silicone 0.50 parts by mass (Product name: GL-04R, manufactured by Kyoeisha Chemical Co., Ltd., solid content 20% by mass)
Radical initiator (d): 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Example 2)
Release in the same manner as in Example 1 except that the radical curable substance (a) was changed to 9 functional urethane acrylate (purple light (registered trademark) UV-7620EA, manufactured by Nippon Gohsei Chemical Co., Ltd.). The mold film was obtained.

(Example 3)
Release in the same manner as in Example 1 except that the radical curable substance (a) was changed to hexafunctional urethane acrylate (purple light (registered trademark) UV-7600B, manufactured by Nippon Gohsei Chemical Co., Ltd.). The mold film was obtained.

(Example 4)
Release in the same manner as in Example 1 except that the radical curable substance (a) was changed to pentafunctional urethane acrylate (purple light (registered trademark) UV-7650B, manufactured by Nippon Gohsei Chemical Co., Ltd.). The mold film was obtained.

(Example 5)
Release in the same manner as in Example 1 except that the radical curable substance (a) was changed to trifunctional urethane acrylate (purple light (registered trademark) UV-7550B, manufactured by Nippon Gohsei Chemical Co., Ltd.). The mold film was obtained.

(Example 6)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the radical curable substance (a) was changed to a hexafunctional acrylate (A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd.) .

(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 radical curable substance (a) was changed to tetrafunctional acrylate (A-TMMT, manufactured by Shin-Nakamura Chemical Co., Ltd.) .

(Example 8)
A release film for producing an ultrathin ceramic green sheet was prepared in the same manner as in Example 1 except that the radical curable substance (a) was changed to a dendrimer-type polyfunctional acrylate (SIRIUS-501, manufactured by Osaka Organic Chemical Industry Co., Ltd.). Obtained.

(Example 9)
Releasing for producing ultrathin ceramic green sheets in the same manner as in Example 1 except that the radical curable substance (a) was changed to a trifunctional allyl compound (Tike (registered trademark) triisocyanurate, manufactured by Nippon Kasei Co., Ltd.) I got a film.

(Examples 10 and 11)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the content of the thiol group-containing compound (b) was changed to the amount described in Table 1.

(Example 12)
A release film for producing an ultrathin ceramic green sheet was prepared in the same manner as in Example 1 except that the thiol group-containing compound (b) was changed to a trifunctional thiol (Kalens MT (registered trademark) NR1, manufactured by Showa Denko KK). Obtained.

(Example 13)
A release film for producing an ultrathin ceramic green sheet was prepared in the same manner as in Example 1 except that the thiol group-containing compound (b) was changed to a bifunctional thiol (Kalens MT (registered trademark) BD1, manufactured by Showa Denko KK). Obtained.

(Example 14)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the coating liquid had the composition shown below.
Methyl ethyl ketone 22.50 parts by mass Isopropyl alcohol 67.50 parts by mass Radical curable substance (a): 6-functional acrylate 8.50 parts by mass (product name: A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd., solid content 100% by mass)
Thiol group-containing compound (b): 1.00 parts by mass of a tetrafunctional thiol group-containing compound
(Product name: Kalens MT (registered trademark) PE1, manufactured by Showa Denko, solid content 100% by mass)
Release agent (c):
Acryloyl group-containing polyether-modified polydimethylsiloxane 0.10 parts by mass (product name: BYK UV-3500, manufactured by Big Chemie Japan, solid content 100% by mass)
Radical initiator (d): 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Example 15)
An ultrathin ceramic green sheet was produced in the same manner as in Example 1 except that the mold release agent (c) was changed to a fluorine type mold release agent (product name: Megafac (registered trademark) RS-75, manufactured by DIC). A mold release film was obtained.

(Example 16)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the release agent (c) was changed to stearyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.).

(Example 17)
An ultrathin ceramic green sheet was produced in the same manner as in Example 1 except that the releasing agent (c) was changed to an acryloyl group-containing polyether-modified polydimethylsiloxane (product name: BYK-UV 3500, manufactured by Big Chemie Japan). A mold release film was obtained.

(Example 18)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the film thickness of the release layer was 1.0 μm.

(Example 19)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the film thickness of the release layer was 0.2 μm.

Example 20
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the film thickness of the release layer was 0.05 μm.

(Example 21)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the base film was changed to X2.

(Example 22)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the substrate film was changed to X3.

(Comparative example 1)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the coating solution had the composition shown below.
Methyl ethyl ketone 22.40 parts by mass Isopropyl alcohol 67.20 parts by mass Radical curable substance (a): 10-functional urethane acrylate 9.50 parts by mass (Product name: Purple light (registered trademark) UV-1700B, manufactured by Japan Synthetic Chemical Co., Ltd., solid Minutes 100%)
Release agent (c): Acryloyl group-containing acrylic silicone 0.50 parts by mass (Product name: GL-04R, manufactured by Kyoeisha Chemical Co., Ltd., solid content 20% by mass)
Radical initiator (d): 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Comparative example 2)
A release film for producing an ultrathin ceramic green sheet was obtained by the same method as in Example 1 except that the coating solution had the composition shown below.
Methyl ethyl ketone 22.50 parts by mass Isopropyl alcohol 67.50 parts by mass Radical curable substance (a) 10-functional urethane acrylate 8.60 parts by mass (Product name: Purple light (registered trademark) UV 1700 B, manufactured by Japan Synthetic Chemical Industry Co., Ltd. 100% solid content )
Thiol group-containing compound (b): 1.00 parts by mass of a tetrafunctional thiol group-containing compound
(Product name: Kalens MT (registered trademark) PE1, manufactured by Showa Denko, solid content 100% by mass)
Radical initiator (d): 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Comparative example 3)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Comparative Example 1 except that the film thickness of the release layer was 1.0 μm.

(Comparative example 4)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Comparative Example 1 except that the film thickness of the release layer was 0.05 μm.

(Comparative example 5)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the coating liquid had the composition shown below.
Methyl ethyl ketone 22.50 parts by mass Isopropyl alcohol 67.50 parts by mass Radical curable substance (a) 6-functional acrylate 9.50 parts by mass (product name: A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd., solid content 100% by mass)
Release agent (c):
Acryloyl group-containing polyether-modified polydimethylsiloxane 0.10 parts by mass (product name: BYK UV-3500, manufactured by Big Chemie Japan, solid content 100% by mass)
Radical initiator (d): 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Comparative example 6)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Comparative Example 5 except that the release layer was coated to have a thickness of 1.0 μm.

(Comparative example 7)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that a coating solution having the following composition was used.
Methyl ethyl ketone 22.40 parts by mass Isopropyl alcohol 67.20 parts by mass Radical curable substance (a): triallyl isocyanurate 9.50 parts by mass (product name: Tike (registered trademark), Nippon Kasei Chemical Co., Ltd., solid content 100%)
Release agent (c): Acryloyl group-containing acrylic silicone 0.50 parts by mass (Product name: GL-04R, manufactured by Kyoeisha Chemical Co., Ltd., solid content 20% by mass)
Radical initiator (d): 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Comparative example 8)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Comparative Example 1 except that ultraviolet rays were irradiated and cured in a nitrogen atmosphere.

  The release film for producing a ceramic green sheet according to the present invention has a surface of the release layer having high smoothness, and the crosslink density of the release layer is high and the solvent resistance is excellent. Therefore, the release layer is not corroded at the time of ceramic green sheet processing or electrode printing, and the peeling force is low and uniform even when peeling the ceramic green sheet of 1 μm or less in thickness, and defects such as pinholes It is possible to form a ceramic green sheet with little Moreover, since there is little curl of a release film, it can be used without the possibility of causing the thickness nonuniformity of a ceramic green sheet and the fall of electrode printing precision.

Claims (12)

  A release film provided with a release layer on at least one side of a polyester film, wherein the area average surface roughness (Sa) of the release layer surface is 7 nm or less, and the release layer has a (meth) acryloyl group and Composition containing a radical curable substance (a) having at least one radical curable functional group selected from alkenyl groups, a thiol group-containing compound (b), a mold release agent (c) and a radical initiator (d) A release film for producing a ceramic green sheet in which a product is cured.   The release film for producing a ceramic green sheet according to claim 1, wherein the thiol group-containing compound (b) has no radically curable functional group selected from a (meth) acryloyl group and an alkenyl group.   The release film for producing a ceramic green sheet according to claim 1 or 2, wherein the thiol group-containing compound (b) is a compound having two or more thiol groups in one molecule. The difference (θ ₁ -θ ₂ ) between diiodomethane contact angle θ _{1 on} the release layer surface and diiodomethane contact angle θ _{2 on} the release layer surface after immersion of the release film in toluene is 3.0 ° or less as an absolute value The release film for ceramic green sheet manufacture in any one of Claims 1-3.   The mold release film according to any one of claims 1 to 4, wherein the mold release agent (c) is a compound containing a silicone component.   The mold release film according to any one of claims 1 to 4, wherein the mold release agent (c) is a compound containing a fluorine atom in the molecule.   The content of the thiol group-containing compound (b) is 1 to 30% by mass with respect to the total mass of the composition forming the release layer, The release according to any one of claims 1 to 6, Mold film.   The polyester film has a surface layer A substantially free of inorganic particles and an opposite surface layer B containing inorganic particles, and a release layer is provided on the surface layer A, the surface layer The ceramic green sheet according to any one of claims 1 to 7, wherein the inorganic particles contained in B are silica particles and / or calcium carbonate particles, and the total of the inorganic particles is contained in an amount of 5000 to 15000 ppm in the surface layer B. Release film.   The film thickness of a release layer is 0.01 micrometer or more and 0.5 micrometers or less, The release film for ceramic green sheet manufacture in any one of Claims 1-8.   Radical curable substance (a) having at least one radical curable functional group selected from (meth) acryloyl group and alkenyl group, thiol group-containing compound (b), mold release agent (c), radical initiator ( The method for producing a release film for producing a ceramic green sheet according to any one of claims 1 to 9, wherein the composition containing d) is cured in the air to form a release layer.   A method of producing a ceramic green sheet having a thickness of 0.2 μm to 1.0 μm, wherein the method of producing a ceramic green sheet using a release film for producing a ceramic green sheet according to any one of claims 1 to 9   A method of manufacturing a ceramic capacitor employing the method of manufacturing a ceramic green sheet according to claim 11.