JP2019072848A - Release film for ceramic green sheet production - Google Patents

Abstract

To provide a release film for ceramic green sheet production in which, by maintaining high smoothness of release layer surface and making the force applied when peeling a ceramic green sheet from a release film low and uniform, there is no risk of damaging the ceramic green sheet at the time of peeling even with an ultrathin layer product having a thickness of 1 μm or less.SOLUTION: Provided is a release film for ceramic green sheet production that is a release film provided with a release layer on at least one side of polyester film and in which the area surface average roughness (Sa) of the release layer surface is 7 nm or less, the release layer is formed by curing a composition containing a cationically curable substance-containing binder a and a release agent b, and the binder a contains a compound having two or more oxetane rings in one molecule.SELECTED DRAWING: None

Description

  The present invention relates to a release film for producing a ceramic green sheet, which suppresses the erosion of a release layer by an organic solvent at the time of ceramic sheet processing and internal electrode printing, thereby increasing the peel strength and uniformity of peeling. The present invention relates to a release film for producing a ceramic green sheet which is not likely to be damaged.

  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 coating and drying a slurry containing a ceramic component such as barium titanate and a binder resin on a release film. After printing an electrode on a molded ceramic green sheet and peeling it from a release film, a multilayer ceramic capacitor is manufactured by laminating and pressing the ceramic green sheet, baking, and applying an external electrode. 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 are likely to occur. there were. 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 radical curable substance that reacts under active energy ray irradiation. It has also been found that the releasability from the ceramic sheet is also excellent due to the silicone component or the cured product thereof contained in the release layer at the same time (see, for example, Patent Document 2).

  However, according to the method described in Patent Document 2, when processed in the atmosphere, there is a problem that the radical polymerization reaction is affected by the inhibition of oxygen and the surface of the release layer becomes a curing failure. If curing failure occurs on the surface of the mold release layer, the mold release layer is corroded by the organic solvent at the time of ceramic green sheet processing and internal electrode printing, and the increase in peel strength and the uniformity of peel are impaired. There was a risk of damaging the sheet.

  In addition, since the radical polymerization reaction has a large curing shrinkage, there has been a problem that the release film tends to curl. When the release film curls, the transportability of the release film may be deteriorated and the electrode printing accuracy may be deteriorated, which may cause a defect.

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

  As a result of intensive investigations in view of the above situation, the present invention maintains the high smoothness of the surface of the release layer, and makes the force applied when peeling the ceramic green sheet from the release film low and uniform. It is an object of the present invention to provide a release film for producing a ceramic green sheet, which is unlikely to damage the ceramic green sheet at the time of peeling 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 surface 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 contains a cationic curable substance A release film for producing a ceramic green sheet, wherein a composition containing a binder a and a release agent b is cured, and the binder a contains a compound having two or more oxetane rings in one molecule.
2. The release according to the _first , wherein the difference between the diiodomethane contact angle θ ₁ on the release layer surface and the diiodomethane contact angle θ _{2 on} the release layer surface after immersion in toluene is 3.0 ° or less as an absolute value. Mold film.
3. The release film for producing a ceramic green sheet according to the first or the second, wherein the binder a contains a compound having an alicyclic epoxy group.
4. The mold release film for producing a ceramic green sheet according to any one of the above first to third features, wherein the mold release agent b is a compound containing a silicone skeleton.
5. The content of the compound having two or more oxetane rings in one molecule contained in the binder a comprising the cationic curable substance is 50 parts by mass or more and 99 parts by mass when the total mass of the binder a is 100 parts by mass The release film for producing a ceramic green sheet according to any one of the above first to fourth, which is the following.
6. 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 5, 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 the surface layer B in an amount of 5000 to 15000 ppm. Release film for manufacturing.
7. It is a manufacturing method of the ceramic green sheet which has a thickness of 0.2 micrometer-1.0 micrometer, Comprising: The manufacturing method of the ceramic green sheet using the release film for ceramic green sheet manufacture in any one of the said 1st-6th.
8. The manufacturing method of the ceramic capacitor which employ | adopts the manufacturing method of the ceramic green sheet as described in said 7th.

  According to the present invention, since there is no erosion of the release layer by the organic solvent at the time of ceramic sheet processing or internal electrode printing, the release film for ceramic green sheet manufacture without a possibility that the uniformity of increase in exfoliation power or exfoliation may be impaired. Can be provided.

  The present inventors provide a release layer on one side of a polyester film, the composition of the release layer is cured by a composition containing a binder a containing a cationically curable substance and a release agent b, and the binder a By containing a compound having two or more oxetane rings in one molecule, there is no possibility that the release layer is corroded by the organic solvent, and release from the ceramic green sheet having excellent releasability. It has been found that a film can be provided. In addition, it has been found that it is possible to provide a release film which is less likely to be curled and is unlikely to lower the electrode printing accuracy because a cationic curable material having a small cure shrinkage is used. Hereinafter, the present invention will be described in detail.

  The release film for producing a ceramic green sheet according to the present invention is obtained by laminating a release layer formed by curing a composition containing a binder a containing a cationically curable substance and a release agent b on at least one side of a polyester film. Is preferred. Since the cationically curable material is not affected by the inhibition of curing by oxygen, there is no possibility of causing curing defects on the surface of the release layer even in the air, and the erosion of the release layer by the organic solvent can be suppressed. In addition, since the cationically curable material has a small curing shrinkage, curling is less likely to occur, and there is no risk of lowering the electrode printing accuracy. In addition, the cation curable substance used here points out the compound in which the cation which generate | occur | produces in reaction system becomes active species and hardening reaction advances.

  It is preferable that the release layer in the present invention has low erosion by the organic solvent. The erosion of the release layer 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 an organic solvent used for immersion, it is preferable to use toluene generally used for a ceramic slurry supposing the ceramic green sheet manufacturing process. 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 droplet used in measuring the contact angle is not particularly limited, and water, bromonaphthalene, ethylene glycol and the like can be suitably used, but the difference in the surface state of the release layer can be seen more noticeably. Most preferably, diiodomethane is used.

When diiodomethane is used as a droplet used for the measurement of the contact angle, the contact angle θ _{1 of the} surface of the release layer and the contact angle θ _{2 of the} surface of the release layer after immersing the release film in toluene for 5 minutes at room temperature The smaller the absolute value of the difference (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 and internal 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.

(Polyester film)
The polyester constituting the polyester film used as the substrate of the present invention is not particularly limited, and polyesters generally used as a substrate for release film can be used to form a film, and preferably 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 it is preferable to have 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, the phrase "containing substantially no 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. Means quantity. 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 It is more preferable to use calcium carbonate particles, but examples of inorganic particles that can be used include alumina-silica composite oxide particles and hydroxyapatite particles. 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 lubricant from falling off .

  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 surface layer B described above 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)
It is preferable that a composition containing at least a binder a containing a cationically curable substance and a release agent b (an additive for imparting releasability) be cured in the release layer in the present invention. The binder a containing a cationically curable substance can be crosslinked to form a coating film having a high modulus of elasticity. By increasing the elastic modulus of the release layer, the release layer is not deformed and follows when peeled, and there is no risk of damaging the ceramic green sheet, which is preferable.

  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 cationically curable substance is considered to have changed the structure of the compound after being cured in the coating layer, but the altered structure itself resulting from the cationically curable substance Since it is extremely difficult to accurately express and describe, as described above, the expression "the composition containing the binder a containing a cationically curable material and the releasing agent b is cured" doing.

(Binder a)
The binder a preferably contains at least a cationically curable substance, and preferably contains, as a cationically curable substance, a compound having two or more oxetane rings in one molecule. A compound having two or more oxetane rings in one molecule has a fast growth reaction in cationic curing, so that the cationic curing proceeds efficiently, the crosslink density of the release layer is increased, and the erosion of the organic solvent can be suppressed. It is preferable because it can be done. The number of oxetane rings contained in one molecule is preferably 2 or more. When the number of oxetane rings is two or more, a crosslink structure can be formed between molecules, and the crosslink density of the release layer can be increased to improve the solvent resistance, which is preferable.

  As a compound which has two or more oxetane rings in 1 molecule contained in the said binder a, an aliphatic, an aromatic, and an alicyclic compound can be used suitably, respectively. The position at which the oxetane ring is introduced may be at an end, a side chain, or any position in the main chain. The compound to be used may be any of a monomer, an oligomer and a polymer, but in order to increase the crosslink density and suppress the erosion of the release layer by the organic solvent, it is particularly preferable to use a monomer. The use of a monomer is preferable because the number of crosslinking points per given mass can be increased and the crosslinking density can be increased.

  As the compound having two or more oxetane rings in one molecule, commercially available compounds can also be used. Examples of commercially available products include OXT221, OXT-121 (above, manufactured by Toagosei Co., Ltd.), ETERNACOL (registered trademark) OXTP, OXBP (above, manufactured by Ube Industries, Ltd.), and the like.

  It is more preferable that the binder a consisting of a cationically curable substance contains an alicyclic epoxy compound in addition to the compound having two or more oxetane rings in one molecule. Alicyclic epoxy compounds have a faster initiation reaction (ring opening reaction of cyclic ether) in cationic curing than compounds having two or more oxetane rings in one molecule, and therefore, two or more oxetane rings in one molecule The crosslink density of the release layer can be further enhanced and the solvent resistance can be improved by using in combination with a compound having the The number of functional groups of the alicyclic epoxy compound (the number of alicyclic epoxy groups contained in one molecule) is not particularly limited, and may be one or two or more, but two It is more preferable that it is the above, since a crosslinked structure can be taken.

  As an alicyclic epoxy compound contained in the said binder a, what introduce | transduced ester frame | skeleton, alkyl frame | skeleton, dicyclopentadiene frame | skeleton, fluorene frame | skeleton, etc. is mentioned as an example, and it has frame | skeleton other than this. May be The compound to be used may be any of a monomer, an oligomer and a polymer, but in order to increase the crosslink density and suppress the erosion of the release layer by the organic solvent, it is preferable to use the monomer for the same reason as above. .

  What is marketed can also be used as said alicyclic epoxy compound. As examples of commercially available products, Cyclomer (registered trademark) M 100, Celoxide (registered trademark) 2000 (above, made by Daicel, 1 functional), Celoxide (registered trademark) 2021 P, 2081 (above, made by Daicel, 2 functional) , Epolide (registered trademark) GT401 (manufactured by Daicel Corporation, tetrafunctional), EHPE (registered trademark) 3150 (manufactured by Daicel Corporation, multifunctional), and the like.

  The content of the compound having two or more oxetane rings in one molecule contained in the binder a is preferably 50 parts by mass or more and 100 parts by mass or less, where the total mass of the binder a is 100 parts by mass, More preferably, it is 75 parts by mass or more and 99 parts by mass or less. It is preferable that the content is 50 parts by mass or more, since the crosslinking density of the release layer can be increased and the erosion of the release layer can be suppressed without insufficient curability even if the film thickness is large. If the amount is 99 parts by mass or less, the curing rate of the compound having two or more oxetane rings in one molecule can be improved by the alicyclic epoxy compound having a rapid initiation reaction, and the reaction proceeds efficiently. preferable. In addition, even when 100 parts by mass of a compound having two or more oxetane rings in one molecule is used, the curability is sufficiently satisfactory, and it is preferable from the viewpoint of increasing the crosslinking density.

  The molecular weight of the compound having two or more oxetane rings in one molecule and the alicyclic epoxy compound is preferably 100,000 or less, more preferably 10,000 or less, and most preferably 1,000 or less. By setting the molecular weight to 100,000 or less, the viscosity of the coating liquid does not become extremely high, and it is preferable because a uniform film is formed after being coated on a film and dried. However, if the molecular weight is too small, care must be taken because there is a risk that part of the resin may volatilize during drying of the dilution solvent due to the low boiling point. Specifically, the boiling point is preferably 130 ° C. or more.

  In the release layer of the present invention, the binder a consisting of a cationically curable material is preferably contained in an amount of 80% by mass to 99.9% by mass with respect to the solid content of the entire release layer, more preferably 90% % Or more and 99.9 mass% or less, more preferably 95 mass% or more and 99.9 mass% or less. By containing the binder a in an amount of 80% by mass or more, a high crosslinking density can be obtained by a cationic polymerization reaction, and erosion of the release layer by the organic solvent can be suppressed, which is preferable. At this time, with the solid content of the entire release layer, the acid generator is decomposed in the drying step or under irradiation with active energy rays, and it is difficult to accurately calculate the trace mass remaining in the release layer. Therefore, it is expressed as the total value of the solid content of the binder component and the release agent.

(Acid generator)
It is preferable to use an acid generator in the release layer in the present invention in order to advance the cationic polymerization reaction. As the acid generator to be used, it is preferable to use a photoacid generator or a thermal acid generator, and more preferably, the use of a photoacid generator which generates an acid under irradiation of active energy rays suppresses the amount of heat during processing. It is preferable because By using a general acid such as sulfonic acid or carboxylic acid, the crosslink density of the release layer can be increased to obtain a release layer having high solvent resistance, but a high processing temperature is required. For this reason, the surface of the release layer may be roughened due to the thermal contraction and the reduction of the smoothness of the raw fabric. In addition, metal salt type, phosphoric ester type, and block type acid generator with blocked acid sites can also be used, but using the photo acid generator for the reason described above is the viewpoint of heat quantity at processing Most preferred.

  The photoacid generator is not particularly limited and may be a general one. However, it is preferable from the viewpoint of reactivity to use a salt composed of an onium ion and a non-nucleophilic anion. Alternatively, an organic metal complex represented by an iron arene complex or a carbocation salt represented by tropylium may be used, or an anthracene derivative or a phenol substituted with an electron withdrawing group such as pentafluorophenol may be used. .

  When a salt comprising the onium ion and a non-nucleophilic anion is used as the photoacid generator, for example, iodonium, sulfonium, or ammonium can be used as the onium ion. The organic group of the onium ion is not particularly limited, but triaryl, diaryl (monoalkyl), monoaryl (dialkyl), trialkyl may be used, and even if benzophenone or 9-fluorene is introduced, the other organic compounds may be used. A group may be used. As the non-nucleophilic anion, hexafluorophosphate, hexafluoroantimonate, hexafluoroborate and tetra (pentafluorophenyl) borate are preferably used from the viewpoint of reactivity. Further, tetra (pentafluorophenyl) gallium ion, or anion obtained by replacing the fluorine anion of the above-mentioned nucleophilic anion with an arbitrary number of perfluoroalkyl groups or organic groups may be used, and other anion components are used. May be

  Examples of commercially available products of photoacid generators include CPI (registered trademark) 100P, 101A, 210S, 300 (all manufactured by San Apro Corporation), IRGACURE (registered trademark) 250, 270, 290 (manufactured by BASF Corporation), UV9380C (manufactured by Momentive Performance Materials), CAT-7605 (manufactured by Shin-Etsu Chemical), UV CATA 211 (manufactured by Arakawa Chemical), WPI-116, 124 (manufactured by Wako Pure Chemical Industries, Ltd.), SP -150, 170 (above, ADEKA company make) etc. are mentioned.

  The thermal acid generator is not particularly limited and a general one may be used. However, it is preferable to use one having a low decomposition temperature because it is possible to suppress the thermal contraction of the raw fabric and the decrease in smoothness. Examples of commercially available products include San-Aid (registered trademark) SI-300, SI-360, SI-45, SI-60, SI-80, SI-100, SI-B2A, SI-B3A, SI-B3 (above, etc.) Sanshin Chemical Industry Co., Ltd.) and the like.

  Two or more acid generators may be used in combination. At this time, by using a photoacid generator and a thermal acid generator in combination, an acid can be generated by the amount of heat during drying and irradiation with active energy rays, and it is preferable because the reaction proceeds more efficiently.

  When using the said photo-acid generator, the activity of an acid generator can be raised and the crosslinking density of a release layer can further be raised by adding a sensitizer. 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 amount of the acid generator to be added to the coating solution is 0.1 to 10 parts by mass when the total mass of the binder a and the releasing agent b consisting of a cationically curable substance contained in the release layer is 100 parts by mass. Is preferred. More preferably, it is 0.5 to 8 parts by mass. More preferably, it is 1 to 5 parts by mass. By setting the amount to 0.1 parts by mass or more, the amount of the generated acid is insufficient, which is preferable because there is no possibility of curing failure. By setting the amount to 10 parts by mass or less, the amount of the generated acid becomes appropriate, which is preferable because the amount of transfer of the acid to the ceramic green sheet to be molded can be suppressed.

  The addition amount of the sensitizer is preferably 0.1 to 5 times by mass with respect to the photoacid generator. 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. If it is smaller than 5 times, absorption of the active energy ray of the photoacid generator is inhibited, and the amount of the generated acid is preferable because there is no possibility of shortage.

(Release agent b)
As the releasing agent b (additive for imparting releasing property) used in the releasing layer in the present invention, silicone based additives and non-silicone based additives such as long chain alkyl based, olefin based and fluorine based. And the like, but it is preferable to use a silicone-based additive from the viewpoint of releasability.

  The silicone-based additive is a material based on polyorganosiloxane having an organic group 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 material is used. can do. An acrylic resin or alkyd resin having a polyorganosiloxane in the side chain can also be used. Among the polyorganosiloxanes, polydialkylsiloxanes can be suitably used. Among these, polydimethylsiloxanes are more preferably used, and those having a functional group in part of the polydimethylsiloxanes are more preferable. By having a functional group, intermolecular interaction such as hydrogen bonding and the like with the cationically curable material is easily developed, and the transition to the ceramic green sheet becomes difficult, which is preferable.

  The functional group to be introduced into the polydimethylsiloxane is not particularly limited, but it may be 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 cyclic ether group, a hydroxy group, a mercapto group, a carboxyl group, a methacryloyl group, an acryloyl group or the like can be used. Although not particularly limited, it is preferable to use a cyclic ether group, and in particular, when it contains a cation curable functional group such as a glycidyl ether group, an alicyclic epoxy group, or an oxetane ring, the above-mentioned cation curable substance In the cross-linked structure of the present invention, the transition to the ceramic green sheet becomes difficult. Among them, when an alicyclic epoxy group is contained, since the compatibility with the binder component is excellent, the releasability is easily expressed, and the most preferable. As a non-reactive functional group, a polyether group, an alkyl group, a fluoroalkyl group, a long chain alkyl group, an ester group, an amide group, a phenyl group etc. can be used.

  The silicone additive used in the present invention is not particularly limited, and any conventional one may be used. For example, as a commercial item of silicone having a reactive functional group, X-22-170DX, X-22-3710, X-22-176DX, X-22-167B (all manufactured by Shin-Etsu Chemical Co., Ltd.), BYK- UV 3500, BYK-UV 3505, BYK-UV 3575 (above, manufactured by Big Chemie Japan) and the like can be mentioned as examples. As a commercial item of the silicone type additive which has a cation curable functional group, X-22-173BX, X-22-173DX, X-22-4741, X-22-9002 (above, Shin-Etsu Chemical Co., Ltd. make) etc. X-22-169B, KF-102, X-62-7629, X62-7660, X-62-7622 (above, Shin-Etsu Chemical Co., Ltd.), which are commercial products of silicone having an alicyclic epoxy group. , UV9300, UV9315, UV9430 (above, Momentive Performance Materials Co., Ltd.), SILIKOLIES (registered trademark) UV Poly200, 201, 215 (above, Arakawa Chemical Industry Co., Ltd.), etc. can be suitably used. .

  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. Commercially available products include Megafuck (registered trademark) (manufactured by DIC Corporation), Optool (registered trademark) (manufactured by Daikin Industries, Ltd.), F-Clear (registered trademark) (manufactured by Kanto Denka Kogyo Co., Ltd.), and the like.

  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. As an example of what is marketed, Peyrol (registered trademark) 1010, Peyrol (registered trademark) 1050, Peyrol (registered trademark) 1070, etc. (above, Lion Specialty Chemicals Inc.), Tesfine (registered trademark) 305, Tesfine (Registered trademark) 314 (all manufactured by Hitachi Chemical Co., 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 B series, G series, JP series (hereinafter, manufactured by Nippon Soda Co., Ltd.), ARTON (registered trademark) (manufactured by JSR Corporation), and the like.

  In addition, although two or more types of the above-mentioned mold release agents may be mixed and used, at least one mold release agent is preferably a silicone-based additive, and it is a silicone having a cationically curable functional group. More preferably, it is most preferably silicone having an alicyclic epoxy group. It is preferable that at least one kind of release agent is a silicone-based additive, since it becomes a release layer excellent in releasability.

  In the release layer in the present invention, the release agent b is preferably contained in an amount of 0.1% by mass or more and 20% by mass or less based on the solid content of the entire release layer. More preferably, they are 0.5 mass% or more and 10 mass% or less, more preferably 0.5 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. The use of less than 20% by mass is preferable because the decrease in the intermolecular interaction with the cationically curable substance is suppressed and there is no possibility of causing a transition to a ceramic green sheet. At this time, with the solid content of the entire release layer, the acid generator is decomposed in the drying step or under irradiation with active energy rays, and it is difficult to accurately calculate the trace mass remaining in the release layer. Therefore, it is expressed as the total value of the solid content of the binder component and the release agent.

  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.

(Feature of release layer)
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 coating layer after curing is 0.01 to 1.0 μm is good More preferably, it is 0.01 to 0.8 μm, and more preferably 0.01 to 0.5 μm. 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. , Preferred to be economical. Specifically, it is preferably 0.01 to 0.4 μm, and more preferably 0.01 to 0.3 μm. When the thickness of the release layer is thicker than 0.01 μm, sufficient release performance is obtained, which is preferable. If the thickness is less than 1.0 μm, a curling defect does not easily occur, and sufficient curability can be obtained, and erosion of the release layer by the organic solvent can be suppressed, which is preferable.

  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 and the maximum projection height is 100 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 ² or more and 3.0 mN / mm ² or less when peeling the ceramic green sheet. More preferably, it is 0.8 mN / mm ² or more and 2.5 mN / mm ² or less. When the peeling force is 0.5 mN / mm ² 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 3.0 mN / mm ² or less, since the ceramic green sheet is not damaged during peeling.

The release film of the present invention preferably has a curl of 3 mm or less, more preferably 1 mm or less, after being heated at 100 ° C. for 15 minutes without tension. Of course, it is also preferable not to curl at all. By setting the thickness to 3 mm or less, curling is less when forming a ceramic green sheet and printing an electrode, and printing accuracy can be enhanced, which is preferable.
(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 using a photoacid generator, the heating temperature is preferably 50 ° C. or more and 110 ° C. or less, and more preferably 60 ° C. or more and 100 ° C. or less. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less. When the temperature is 110 ° C. or less, the thermal load on the film can be suppressed, appearance defects such as heat shrinkage of the film are less likely to occur, and the thickness unevenness of the ceramic green sheet is less likely to occur, which is preferable. When the temperature is 100 ° C. or less, the thermal load on the film is further reduced, and processing can be performed 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 coating is sufficient, and there is no possibility of process contamination and the like, which is preferable.

As an active energy ray used to react a cationically curable substance with a photoacid generator, ultraviolet rays, electron beams, X-rays and the like can be used, but ultraviolet rays are preferred because they are easy to use. The amount of ultraviolet rays to be irradiated is preferably 10 to 1000 mJ / cm ² in terms of integrated light amount, more preferably 15 to 500 mJ / cm ² , and further preferably 15 to 100 mJ / cm ² . By setting it as 10 mJ / cm < ² > or more, since hardening of resin advances sufficiently, it is preferable. Since the speed at the time of processing can be improved by setting it as 1000 mJ / cm < ² > or less, a mold release film can be created economically and is preferable.

  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.

  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.

(Film thickness of release layer)
The film cross section when the release film was cut into an arbitrary size was observed with a transmission electron microscope and the value calculated was taken as the release layer thickness.

(Surface roughness)
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

(Contact angle)
The amount of diiodomethane (droplet amount) on the release surface of a release film that has been allowed to stand using a contact angle meter (manufactured by Kyowa Interface Science, 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 °

(Pinhole evaluation of ceramic green sheet)
The composition consisting of the following materials was stirred and mixed, and dispersed for 30 minutes using a bead mill having dispersoids of glass beads with a diameter of 0.5 mm, 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. S-LEC (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 1 minute 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 (Guide: no more than 2 pinholes per measurement area)
:: Occurrence of pinholes (estimate: no more than 5 pinholes per measurement area)
X: There are many pinholes

(Evaluation of peelability of ceramic green sheet)
The composition consisting of the following materials was stirred and mixed, and dispersed for 60 minutes using a bead mill having zirconia beads of 0.5 mm in diameter as a dispersoid, 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 (manufactured by Sekisui Chemical Co., Ltd. S-LEC (registered trademark) BM-S) 6.5 parts by mass DOP (dioctyl phthalate) 3.3 parts by mass Next, the resulting release film sample was coated with the applicator so that the dried slurry had a thickness of 10 μm using an applicator and dried at 90 ° C. for 2 minutes. The green sheet was molded on a release film. After removing the obtained release film with ceramic green sheet using a static remover (SJ-F020 manufactured by KEYENCE CORPORATION), the width of 30 mm is measured using a high-speed peel tester (TE-701 manufactured by Tester Sangyo Co., Ltd.) The film was peeled at a peeling angle of 90 degrees and a peeling speed of 10 m / min. Peeling fixed the ceramic green sheet surface, and peeled in the direction which pulls a release film surface. The stress applied at the time of peeling at this time was measured and used as peeling force.

(Curl evaluation of release film)
The release film sample was cut into a size of 10 cm × 10 cm, and heat treatment was performed in a hot air oven at 100 ° C. for 15 minutes so that no tension was 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. The height from the glass plate to each corner apex at this time was measured, and the curling was evaluated according to the following judgment criteria.
:: The total sum of each corner is 1 mm or less ○: The total sum of each corner is greater than 1 mm and 3 mm or less.
Δ: The sum of each corner is greater than 3 mm and 10 mm or less.
X: The total curl at each corner is greater than 10 mm.

(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 horizontal direction at 170 ° C. to obtain a 31 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 28 nm.

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

(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
A coating solution of the following composition is coated 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 0.3 μm, and dried at 90 ° C. for 15 seconds, and then integrated An ultraviolet ray having a light quantity of 70 mJ / cm ² was irradiated using an ultraviolet irradiator (LC6B, H bulb manufactured by Heraeus Co., Ltd.) to obtain a release film for producing an ultrathin ceramic green sheet. A ceramic slurry was coated on the obtained mold release film, and the surface roughness of the mold release layer, peelability, change in contact angle after immersion in toluene, pinholes, curl, etc. were evaluated, and good evaluation results were obtained. The
Methyl ethyl ketone 44.75 parts by mass Toluene 44.75 parts by mass Binder containing a cationically curable substance a:
3-Ethyl-3-{[(3-ethyloxetan-3-yl) methoxy] methyl} oxetane 9.90 parts by mass (Difunctional oxetane compound, product name: Aron Oxetane (registered trademark) OXT-221, Toagosei Co., Ltd. Made, solid content 100% by mass)
Releasing agent b: Alicyclic epoxy group-containing polydimethylsiloxane 0.10 parts by mass (Product name: SILIKOLYS (registered trademark) UV Poly 215, manufactured by Arakawa Chemical Industries, solid content 100% by mass)
Acid generator: 0.50 parts by mass of triarylsulfonium salt (Product name: CPI (registered trademark) 210S, manufactured by San Apro, 100% by mass of active ingredient)

(Example 2)
A compound having an oxetane ring is converted to 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene (bifunctional oxetane compound, product name: Aron Oxetane (registered trademark) OXT-121, manufactured by Toagosei Co., Ltd.) A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except for the change.

(Example 3)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1 except that the coating liquid had the composition shown below.
Methyl ethyl ketone 44.75 parts by mass Toluene 44.75 parts by mass Binder comprising a cationically curable material a:
Aron Oxetane (registered trademark) OXT-221 9.40 parts by mass
3 ', 4'-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate 0.50 parts by mass
(Product name: Celoxide (registered trademark) 2021 P, manufactured by Daicel, solid content 100% by mass)
Release agent b: SILICOLIES (registered trademark) UV Poly 215 0.10 parts by mass Acid generator: CPI (registered trademark) 210 S 0.50 parts by mass

(Example 4)
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 44.75 parts by mass Toluene 44.75 parts by mass Binder comprising a cationically curable material a:
Aron Oxetane (registered trademark) OXT-221 7.92 parts by mass Celoxide (registered trademark) 2021 P 1.98 parts by mass Releasing agent b: Silicones (registered trademark) UV Poly 215 0.10 parts by mass Acid generator: CPI (registered trademark) ) 210S 0.50 parts by mass

(Example 5)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 3, except that the compound having a bifunctional oxetane ring was changed to Aron Oxetane (registered trademark) OXT-121 (manufactured by Toagosei Co., Ltd.). The

(Example 6)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 3 except that Celoxide (registered trademark) 2021P was changed to Cyclomer (registered trademark) M100 (manufactured by Daicel Corporation).

(Example 7)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 3, except that Celoxide (registered trademark) 2021P was changed to Epolide (registered trademark) GT401 (manufactured by Daicel).

(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 release agent b was changed to one end epoxy modified polydimethylsiloxane (product name: X22-173DX, manufactured by Shin-Etsu Chemical Co., Ltd.) I got

(Example 9)
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 b was changed to acrylic silicone (product name: KF2005, manufactured by Shin-Etsu Chemical Co., Ltd.).

(Example 10)
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 b was changed to a long chain alkyl group-containing release agent obtained by preparing as follows.
(Preparation method of long chain alkyl group-containing releasing agent)
The mixture was mixed so that the ratio of 95 mol% of stearyl acrylate and 5 mol% of hydroxyethyl methacrylate was reached, diluted with toluene so that the solid content concentration became 40 mass%, and azobisisobutyronitrile was adjusted to 0. A 5 mol% addition and copolymerization were carried out to obtain a release agent A. The weight average molecular weight of the polymer obtained at this time was 30,000.

(Example 11)
A release film for producing an ultrathin ceramic green sheet was prepared in the same manner as in Example 1 except that the release agent b was changed to a fluorine-based resin varnish (product name: FCLIA (registered trademark) KD6100, manufactured by Kanto Denka Kogyo Co., Ltd.). I got

(Example 12)
An ultrathin ceramic green sheet was produced in the same manner as in Example 1, except that the releasing agent b was changed to a long chain alkyl group-containing polymer (product name: Peiroi (registered trademark) 1010S, manufactured by Lion Specialty Chemicals). A mold release film was obtained.

(Example 13)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 3, except that the release layer thickness after drying was 0.05 μm.

(Example 14)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 3, except that the release layer thickness after drying was 0.6 μm.

(Example 15)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 3, except that the release layer thickness after drying was 1.0 μm.

(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 base film was changed to X2.

(Example 17)
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.

(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 acid generator was changed to San-Aid (registered trademark) SI-60.

(Example 19)
A release film for producing an ultrathin ceramic green sheet was prepared in the same manner as in Example 1 except that the acid generator was changed to a 1: 1 mixture of SANAID (registered trademark) SI-60 and CPI (registered trademark) -210S. Obtained.

(Comparative example 1)
Release in the same manner as in Example 3 except that Aron Oxetane (registered trademark) OXT-221 was changed to Aron Oxetane (registered trademark) OXT-212 (a monofunctional oxetane compound manufactured by Toagosei Co., Ltd.). The mold film was obtained.

(Comparative example 2)
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 44.75 parts by mass Toluene 44.75 parts by mass Binder comprising a cationically curable material a:
Aron Oxetane (registered trademark) OXT-221 9.50 parts by mass Celoxide (registered trademark) 2021 P 0.50 parts by mass Photoacid generator: CPI (registered trademark) 210S 0.50 parts by mass

(Comparative example 3)
Releasing for the production of ultrathin ceramic green sheets in the same manner as in Example 1 except that the coating liquid having the composition shown below was changed and the film thickness of the releasing layer was coated to be 0.8 μm. I got a film.
Methyl ethyl ketone 49.43 parts by mass Toluene 49.43 parts by mass A binder comprising a photo-radical curable substance:
Dipentaerythritol hexaacrylate 0.99 parts by mass (Product name: A-DPH, Shin-Nakamura Chemical Co., Ltd., solid content 100% by mass)
Release agent b: Acryloyl group-containing polyether-modified polydimethylsiloxane
0.01 parts by mass (Product name: BYK-UV 3500, manufactured by Big Chemie Japan, solid content 100% by mass)
Photo radical polymerization initiator:
Methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one
0.05 parts by mass (Product name: IRGACURE (registered trademark) 907, manufactured by BASF, 100% by mass of active ingredient)

  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 there is no possibility that the release layer is corroded by the organic solvent. It is possible to form a ceramic green sheet which is low in the number of defects such as pinholes. Moreover, since appearance defects, such as curling, are suppressed by using a cationic curable material having a small curing shrinkage, it was possible to provide a release film without a possibility of lowering the accuracy of electrode printing.

Claims (8)

  A release film provided with a release layer on at least one surface 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 contains a cationic curable substance A release film for producing a ceramic green sheet, wherein a composition containing a binder a and a release agent b is cured, and the binder a contains a compound having two or more oxetane rings in one molecule. 2. The release according to claim 1, wherein the difference between the diiodomethane contact angle θ ₁ on the release layer surface and the diiodomethane contact angle θ _{2 on} the release layer surface after immersion in toluene is 3.0 ° or less as an absolute value. Mold film.   The release film for producing a ceramic green sheet according to claim 1 or 2, wherein the binder a contains a compound having an alicyclic epoxy group.   The mold release film according to any one of claims 1 to 3, wherein the mold release agent b is a compound containing a silicone skeleton.   The content of the compound having two or more oxetane rings in one molecule contained in the binder a comprising the cationic curable substance is 50 parts by mass or more and 99 parts by mass when the total mass of the binder a is 100 parts by mass It is the following, The release film for ceramic green sheet manufacture in any one of the Claims 1-4 characterized by the above-mentioned.   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 5, 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.   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 6.   A method of manufacturing a ceramic capacitor employing the method of manufacturing a ceramic green sheet according to claim 7.