JP7311545B2 - Release film for manufacturing ceramic green sheets - Google Patents

Description

The present invention relates to a release film for producing a ceramic green sheet. More specifically, when the separation temperature between the ceramic green sheet and the release film is high during the production of an ultra-thin ceramic green sheet, the release film can be peeled off even when the peeling angle is low. The present invention relates to a release film for manufacturing an ultra-thin ceramic green sheet, which has a low force and can suppress damage to the ceramic green sheet.

Conventionally, a release film obtained by laminating a release layer on a polyester film as a base material has been used for molding ceramic green sheets such as laminated ceramic capacitors and ceramic substrates. In recent years, along with miniaturization and increase in capacity of laminated ceramic capacitors, the thickness of ceramic green sheets tends to be reduced. A ceramic green sheet is formed by coating a release film with a slurry containing a ceramic component such as barium titanate and a binder resin and drying the slurry. After electrodes are printed on the molded ceramic green sheets and separated from the release film, the ceramic green sheets are laminated, pressed, fired, and external electrodes are applied to manufacture the laminated ceramic capacitor. When molding a ceramic green sheet on the release layer surface of a polyester film, there is a problem that microscopic projections on the surface of the release layer affect the molded ceramic green sheet, making defects such as repelling and pinholes more likely to occur. there were. Therefore, various techniques have been developed for realizing a release layer surface having excellent flatness (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, a thickness of 0.2 μm to 1.0 μm have been required. Therefore, since the strength of the ceramic green sheet decreases, it has become necessary not only to smooth the surface of the release layer, but also to perform a low and uniform release force when the ceramic green sheet is released from the release film. . In other words, it is becoming more important to minimize the force applied to the ceramic green sheets when peeling the ceramic green sheets from the release film so as not to damage the ceramic green sheets.

As a method for peeling a ceramic green sheet, a method has been proposed in which the ceramic green sheet side is fixed to a suction head and a release film, which is a carrier film, is peeled off from the edge (for example, Patent Document 2). In the case of Patent Document 2, it can be seen from the dimensions of the device that the peeling angle is as low as about 3°. Generally, it is known that when the peeling angle is lower than 90°, the peeling force becomes heavy (for example, Non-Patent Document 1). In some cases, the head for separating the ceramic sheet from the release film and the head for laminating the ceramic sheet are the same. In this case, a constant temperature is applied to the peeling head in order to fuse the binders in the ceramic sheets during lamination.

In recent years, it has been found that the surface of the release layer can be made smooth by using an ultraviolet curable resin. At the same time, it has been found that the silicone-based component contained in the release layer or the cured product thereof is excellent in releasability from the ceramic sheet (see, for example, Patent Document 3).

However, according to the method described in Patent Document 3, the silicone component tends to segregate on the surface of the release layer during processing of the release layer, and surface curing inhibition peculiar to radical polymerization occurs. There is a problem that the deterioration of the solvent property is caused. If the solvent resistance near the surface of the release layer is poor, the surface of the release layer will be corroded by organic solvents such as toluene used during ceramic green sheet processing and internal electrode printing. There is a problem in that the peeling force at the time of peeling is remarkably increased, and the ceramic sheet is damaged. From the above, it was found that a release layer having a low peeling force at a low angle and a low peeling force even when peeled at a high temperature is effective in reducing damage to a ceramic green sheet, and the present invention has been completed. rice field.

JP-A-2000-117899 Japanese Patent Application Laid-Open No. 2004-031489 WO2013/145864

Inao, Saeki, Sugisaki, Shimizu, Inaba, Kishimoto, "Peeling Energy of Adhesive/Release Agent Interface and its Effect", Journal of Adhesion Society of Japan, Vol.48, No.9, p. 308-313, 2012

As a result of intensive studies in view of the above-mentioned circumstances, the present invention has found that, in order not to damage the ceramic green sheets, the surface of the release layer of the release film is maintained with high smoothness. Ceramic green with low peeling force even when the peeling angle is low when manufacturing a ceramic green sheet compared to a release film, and low peeling force when manufacturing an ultra-thin ceramic green sheet with a thickness of 1 μm or less. An object of the present invention is to provide a release film for sheet production.

As a result of intensive studies by the present inventors in order to solve the above problems, a polyester film was used, a release layer was provided on at least one side, and a release temperature of 50 between the ceramic sheet applied on the release layer and the release layer C. and a peeling angle of 30.degree. C. and a peeling angle of 30.degree.

That is, the present invention consists of the following configurations.
1. A polyester film is used as a base material, and the base material has a surface layer A on at least one side that does not substantially contain inorganic particles, and the surface layer A on at least one side is separated directly or via another layer. When a release film is laminated with a mold layer, and a ceramic green sheet is formed on the release layer, the release force F at a release temperature of 50 ° C. and a release angle of 30 ° between the ceramic green sheet and the release film A release film for producing a ceramic green sheet having a (T50/A30) of 60 mN/mm or less.
2. 1. The ceramic green sheet production according to 1 above, wherein the film elastic modulus measured from the surface of the release layer opposite to the substrate is 2.0 GPa or more by a nanoindentation test on the release layer. release film.
3. The ceramic green according to the first or second above, wherein the release layer is formed by curing a coating film containing at least a release agent and a binder component, and the binder component accounts for 85% by mass or more of the solid content of the release layer. Release film for sheet manufacturing.
4. 3. The release film for producing a ceramic green sheet as described in 3 above, wherein the release agent contains a silicone skeleton and the content of the release agent is 15% by mass or less relative to the solid content of the release layer.
5. 4. The release film for producing a ceramic green sheet according to any one of 1 to 4 above, wherein the release layer has a thickness of 0.01 μm to 1.5 μm.
6. The release film for producing a ceramic green sheet according to any one of the above 3rd to 5th, wherein the binder component comprises a crosslinked product of at least one of a melamine-based compound, an epoxy-based compound and an acrylate-based compound.
7. The surface layer B forming the surface layer opposite to the surface layer A of the polyester film base contains particles, the particles are silica particles and / or calcium carbonate particles, and the total of the particles is the surface layer B 6. The release film for producing a ceramic green sheet according to any one of 1 to 6 above, which contains 5000 to 15000 ppm in the release film.
8. A method for producing a ceramic green sheet by molding a ceramic green sheet using the release film for producing a ceramic green sheet according to any one of the first to seventh items, wherein the molded ceramic green sheet has a thickness of 0.2 μm to 0.2 μm. A method for producing a ceramic green sheet having a thickness of 1.0 μm.
9. A method for manufacturing a ceramic capacitor employing the method for manufacturing a ceramic green sheet according to the eighth above.

In the release film for producing a ceramic green sheet of the present invention, the surface of the release layer is smooth, and when the peeling angle is low during the production of the ceramic green sheet compared to the conventional release film for producing a ceramic green sheet, The release force is also low, and damage to the ceramic green sheet can be suppressed, and an ultra-thin ceramic green sheet with a thickness of 0.2 to 1.0 μm can be produced.

It is a schematic diagram for demonstrating the measuring method of the peeling force in this invention.

The present invention will be described in detail below.

The release film for producing a ceramic green sheet of the present invention has a surface layer A that does not substantially contain inorganic particles on at least one side of a polyester film, and directly or on the surface of the surface layer A on at least one side or another A release layer is laminated via layers, and the release force F (T50/A30) at a release temperature of 50°C and a release angle of 30° between the ceramic sheet applied on the release layer and the release layer is 60 mN. /mm or less.

(polyester film)
The polyester that constitutes the polyester film used as the base material in the present invention is not particularly limited, and it is possible to use a film-formed polyester that is commonly used as a base material for a release film. It is preferably a crystalline linear saturated polyester comprising an aromatic dibasic acid component and a diol component, such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, or resins thereof. Component-based copolymers 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 may be copolymerized with a small amount of other dicarboxylic acid component or diol component, but from the viewpoint of cost. , preferably made only from terephthalic acid and ethylene glycol. In addition, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, crystallization agents, etc. may be added within limits that do not impair the effects of the film of the present invention. The polyester film is preferably a biaxially oriented polyester film because of its high bidirectional elastic modulus.

The intrinsic viscosity of the polyethylene terephthalate film is preferably 0.50 to 0.70 dl/g, more preferably 0.52 to 0.62 dl/g. When the intrinsic viscosity is 0.50 dl/g or more, it is preferable because many breakages do not occur in the stretching process. Conversely, when it is 0.70 dl/g or less, the cutting performance is good when cutting into a predetermined product width, and dimensional defects do not occur, which is preferable. Moreover, it is preferable to sufficiently vacuum-dry the raw material pellets.

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

In the present invention, the stretching temperature during stretching of the polyester film is preferably higher than the secondary transition point (Tg) of the polyester. It is preferable that the film is stretched 1 to 8 times, particularly 2 to 6 times, in each of the longitudinal and transverse directions.

The polyester film preferably has a thickness of 12 to 50 μm, more preferably 15 to 38 μm, more preferably 19 to 33 μm. If the thickness of the film is 12 μm or more, it is preferable because there is no risk of deformation due to heat during film production, the process of releasing the release layer, or the molding of ceramic green sheets. On the other hand, if the thickness of the film is 50 μm or less, the amount of the film to be discarded after use is not excessively increased, which is preferable for reducing the environmental load.

The polyester film substrate may be a single layer or a multilayer of two or more layers, but preferably has 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 particles and the like on the opposite side of the surface layer A which does not substantially contain inorganic particles. As a laminated structure, the layer on the side to which the release layer is applied is the surface layer A, the layer on the opposite side is the surface layer B, and the core layer other than these is the layer C. The layer structure in the thickness direction is release layer / Laminated structures such as A/B or release layer/A/C/B may be mentioned. As a matter of course, the layer C may be composed of a plurality of layers. Alternatively, the surface layer B may not contain particles. In that case, it is preferable to provide a coating layer containing particles and a binder on the surface layer B in order to impart lubricity for winding the film into a roll.

In the polyester film substrate of the present invention, the surface layer A forming the surface to be coated with the release layer preferably does not substantially contain inorganic particles. At this time, the area surface average roughness (Sa) of the surface layer A is preferably 7 nm or less. When Sa is 7 nm or less, pinholes and the like are less likely to occur during molding of laminated ultra-thin ceramic green sheets, which is preferable. It can be said that the smaller the region surface average roughness (Sa) of the surface layer A is, the more preferable it is, but it may be 0.1 nm or more. Here, when the below-described anchor coat layer or the like is provided on the surface layer A, it is preferable that the coat layer does not substantially contain inorganic particles, and the region surface average roughness (Sa) after lamination of the coat layer is within the above range. It is preferable to enter In the present invention, "substantially free of inorganic particles" means a content of 50 ppm or less, preferably 10 ppm or less, most preferably a detection limit or less when the inorganic elements are quantified by fluorescence X-ray analysis. do. This is because even if inorganic particles are not positively added to the film, contaminants derived from foreign substances and dirt adhering to the lines and equipment in the raw material resin or film manufacturing process peel off and mix into the film. This is because there are cases.

In the polyester film substrate of the present invention, the surface layer B, which forms the surface opposite to the surface to which the release layer is applied, preferably contains particles from the viewpoint of the slipperiness of the film and the ease with which air can escape. Silica particles and/or calcium carbonate particles are preferably used. The content of the particles contained in the surface layer B is preferably 5000 to 15000 ppm in total. At this time, the area average surface roughness (Sa) of the film of the surface layer B is preferably in the range of 1 to 40 nm. More preferably, it is in the range of 5 to 35 nm. When the total amount of silica particles and/or calcium carbonate particles is 5000 ppm or more and Sa is 1 nm or more, when the film is wound into a roll, air can escape uniformly, resulting in a good roll shape and good flatness. , suitable for the production of ultra-thin ceramic green sheets. In addition, when the total amount 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 protrusions cannot be formed, so that the quality is stable when manufacturing an ultra-thin ceramic green sheet. and preferred.

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

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

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

In addition, the method for measuring the average particle size of the particles is to observe the particles in the cross section of the film after processing with a transmission electron microscope or scanning electron microscope, observe 100 particles that are not agglomerated, and measure the maximum particle size of each particle. The diameter is defined as the particle diameter, and the average value thereof is defined as the average particle diameter.

When the surface layer B does not contain particles, it is preferable that a coating layer containing particles on the surface layer B provides lubricity. Although the present coat layer is not particularly limited, it is preferably provided as an in-line coat that is applied during film formation of the polyester film. When the surface layer B does not contain particles and the surface layer B has a coat layer containing particles, the surface of the coat layer has a region surface roughness (Sa) for the same reason as the region surface roughness (Sa) of the surface layer B The average surface roughness (Sa) is preferably in the range of 1-40 nm. More preferably, it is in the range of 5 to 35 nm.

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

The thickness ratio of the surface layer A, which is the layer on which the release layer is provided, is preferably 20% or more and 50% or less of the total layer thickness of the base film. If it is 20% or more, the inside of the film is less likely to be affected by the particles contained in the surface layer B, etc., and it is easy for the region surface average roughness Sa to satisfy the above range, which is preferable. When the total thickness of the base film is 50% or less of the total thickness of the base film, the ratio of the recycled raw material used in the surface layer B can be increased, and the environmental load is reduced, which is preferable.

From the viewpoint of economy, the layers other than the surface layer A (the surface layer B or the intermediate layer C described above) may contain 50 to 90% by mass of recycled film scraps and PET bottle raw materials. Even in this case, the type and amount of lubricant contained in the surface layer B, the particle size, and the area surface average roughness (Sa) preferably satisfy the above ranges.

In addition, a film before or after uniaxial stretching is applied to the surface of the surface layer A and/or the surface layer B in order to improve the adhesion of a release layer to be applied later or to prevent electrification. A coat layer may be provided on the surface, and corona treatment or the like may be applied.

(release layer)
The release layer in the present invention is preferably formed by curing a coating film containing at least a release agent and a binder component. The release layer in the present invention preferably has a high crosslink density. By increasing the cross-linking density, the elastic modulus is also improved, so that the deformation during peeling is reduced, so that the peel force at high temperatures and low angles can be reduced. It is also preferable that the surface of the release layer has high solvent resistance in order to reduce the release force at high temperatures and low angles. Since the release layer surface has high solvent resistance, it is possible to prevent corrosion of the release layer surface by the solvent during slurry coating. Releasing force can be lowered by reducing deformation of the release layer surface due to solvent erosion. It is also preferable that the release agent in the release layer is appropriately segregated on the surface while maintaining interaction with the binder in terms of lowering the release force at high temperatures and low angles.

The binder component contained in the release layer in the present invention is not particularly limited, but in order to increase the crosslink density of the release layer, a crosslinkable component is preferably crosslinked. A thermosetting resin, an ultraviolet curable resin, or the like can be used as the binder component. The release agent, binder component, etc., which are constituents of the coating liquid and coating film before crosslinking and curing, may change in chemical structure in the release layer after crosslinking and curing. Since it is difficult to describe the chemical structure itself in its crosslinked and cured state, the release layer is expressed as a cured coating film containing at least a release agent and a binder component.

The binder component contained in the release layer in the present invention preferably contains two or more reactive functional groups per molecule. Having two or more functional groups is preferable because the crosslink density can be increased.

Suitable binder components for thermosetting resins include melamine compounds. It is preferable to use a melamine-based compound because a release layer having a high cross-linking density can be obtained.

(melamine compound)
As the melamine-based resin used for the release layer in the present invention, a general one can be used without particular limitation, but it is obtained by condensing melamine and formaldehyde, and has a triazine ring and a methylol group and / or alkoxy in one molecule. Each preferably has one or more methyl groups. Specifically, a methylolmelamine derivative obtained by condensing melamine and formaldehyde is preferably etherified by dehydration condensation reaction with a lower alcohol such as methyl alcohol, ethyl alcohol, isopropyl alcohol, or butyl alcohol. Examples of methylolated melamine derivatives include monomethylolmelamine, dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylolmelamine, and hexamethylolmelamine. One type may be used, or two or more types may be used.

The release layer in the present invention preferably has a high crosslink density and a high elastic modulus in order to reduce the peeling force. Therefore, as the melamine-based resin used for the release layer, it is preferable to use hexamethylolmelamine, which has many cross-linking points in one molecule, so that the cross-linking density of the release layer can be increased.

As the melamine-based resin used in the release layer in the present invention, when using an ether compound obtained by dehydration condensation reaction of a methylolmelamine derivative with alcohol, from the viewpoint of reactivity, hexamethoxy obtained by dehydration condensation with methyl alcohol Methylmelamine is particularly preferred.

The melamine-based resin used for the release layer in the present invention preferably has a weight-average molecular weight of less than 1,000. More preferably, the weight average molecular weight is less than 800, more preferably less than 600. If the weight average molecular weight is less than 1,000, the cross-linking reaction proceeds easily and a film with a higher cross-linking density can be formed, which is preferable. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

When a melamine-based compound is used as the binder for the release layer in the present invention, it is preferable to add a catalyst to promote the cross-linking reaction of the melamine-based compound. The catalyst to be used is not particularly limited, but existing acid catalysts can be used, and carboxylic acid, metal salt, phosphoric acid ester, and sulfonic acid catalysts can be preferably used. Block-type catalysts in which acid sites are blocked can also be used.

When a sulfonic acid system is used as the acid catalyst, for example, p-toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, trifluoromethanesulfonic acid, etc. are preferably used. and p-toluenesulfonic acid is particularly preferred.

When carboxylic acids are used as acid catalysts, for example, benzoic acid, acetic acid, formic acid, oxalic acid, propionic acid, derivatives thereof, and the like can be used. Carboxylic acid-based acid catalysts are known to be weaker in acidity and less reactive than other catalysts such as sulfonic acid-based catalysts, but carboxylic acid-based catalysts can be sufficiently used in the present invention. In addition, since the carboxylic acid system reacts more slowly than the sulfonic acid system, the release agent tends to segregate on the surface during the drying process, and the release agent can be added in a smaller amount to exhibit the effect of release properties. Therefore, it is preferable. In particular, 4-methylbenzoic acid is inexpensive, readily available and easy to use.

The amount of the acid catalyst to be added is preferably 0.1 to 10 mass % with respect to the melamine resin contained in the release layer. More preferably, it is 0.5 to 8% by mass. More preferably, it is 0.5 to 5% by mass. A content of 0.1% by mass or more is preferable because the curing reaction proceeds easily. On the other hand, when the content is 10% by mass or less, the acid catalyst is not likely to migrate to the ceramic green sheet to be molded, which is preferable because there is no possibility of having an adverse effect.

Suitable binder components for the ultraviolet curable resin include cationic curable resins and radical curable resins. Cationic curable resins include epoxy compounds, ether compounds, and oxetane compounds. Moreover, an acrylate-based compound can be preferably used as the radical-curing resin. In the case of cationic curable resins, epoxy compounds are preferred because of their high reactivity.

(Epoxy compound)
Examples of the epoxy group-containing compound used for the release layer in the present invention include glycidyl ether type, glycidyl amine type, glycidyl ester type epoxy, and alicyclic epoxy. and alicyclic epoxies are preferred, and alicyclic epoxies are most preferred from the viewpoint of reactivity. Examples of glycidyl ether type epoxy compounds include aromatic glycidyl ethers typified by bisphenol type epoxy resins and cresol novolac type epoxy resins, and aliphatic glycidyl ethers typified by hydrogenated type A glycidyl ethers and butyl glycidyl ethers. be done. Examples of the alicyclic epoxy include those into which an ester skeleton, a dicyclopentadiene skeleton, a fluorene skeleton, an ε-caprolactone skeleton, or the like is introduced, and may have other skeletons.

A commercially available one can also be used as the alicyclic epoxy compound. Examples of commercially available products include Cychromer (registered trademark) M100, Celoxide (registered trademark) 2000 (manufactured by Daicel, monofunctional), Celoxide (registered trademark) 2021P, 2081 (manufactured by Daicel, bifunctional). , Epolead (registered trademark) GT401 (manufactured by Daicel Corporation, tetrafunctional), EHPE (registered trademark) 3150 (manufactured by Daicel Corporation, multifunctional), and the like.

The epoxy compound used for the release layer in the present invention may be used alone or in combination of two or more. Among these epoxy group-containing compounds, alicyclic epoxy compounds are particularly preferred, and polyfunctional alicyclic epoxy resins having two or more functionalities in one molecule are more preferred.

(Cationic polymerization initiator)
When using a cationic curable resin for the release layer in the present invention, it is preferable to use a cationic polymerization initiator. Cationic polymerization initiators include, for example, onium salts such as aryldiazonium salts, aryliodonium salts, arylhalonium salts, and arylsulfonium salts; mentioned. These may be used alone or in combination of two or more.

Commercially available products include PCI-220, PCI-620 (manufactured by Nippon Kayaku Co., Ltd.), UVI6990 (manufactured by Union Carbide Co., Ltd.), SP-150, SP-152, SP-170, SP-172 (manufactured by Asahi Denka Kogyo Co., Ltd.). ), Uvacure (registered trademark) 1590, 1591 (manufactured by Daicel UCB), San-Aid (registered trademark) SI-110, SI-180, SI-100L, SI-80L, SI60L (manufactured by Sanshin Chemical Co., Ltd.), etc. .

The amount of the cationic polymerization initiator added is not particularly limited. For example, it is preferable to use about 0.1 to 20% by mass with respect to the cationic curing resin used.

When using a photocationic polymerization initiator as a cationic polymerization initiator, it is desirable to use together with a photosensitizer. Examples of photosensitizers include carbonyl compounds, organic sulfur compounds, persulfates, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes. Specific photosensitizers include, for example, benzoin methyl ether, benzoin isopropyl ether, benzoin derivatives such as α,α-dimethoxy-α-phenylacetophenone, benzophenone, 2,4-dichlorobenzophenone, ο-benzoylbenzoic acid. Benzophenone derivatives such as methyl, 4,4′-bis(dimethylamino)benzophenone, 4,4′-bis(dimethylamino)benzophenone, thioxanthone derivatives such as 2-chlorothioxanthone, 2-isopropylthioxanthone, 2-chloroanthraquinone , anthraquinone derivatives such as 2-methylanthraquinone, acridone derivatives such as N-methylacridone and N-butylacridone, α,α-diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl compounds, and halogen compounds. be done. However, it is not limited to these. Moreover, these may be used individually or may be used in mixture. It is preferable to add about 0.1 to 20% by mass of the photosensitizer to the cationic curable resin.

(Acrylate compound)
The acrylate-based compound used in the release layer in the present invention is preferably a (meth)acrylate-based compound that is an ultraviolet curable resin. Since the (meth)acrylate compound has a very fast reaction rate, the radical polymerization reaction proceeds instantaneously at the same time as the photopolymerization initiator is cleaved, and a coating film having a high crosslink density and a high elastic modulus can be formed. By increasing the elastic modulus of the release layer, the release layer is not deformed and follows the release layer, which is preferable because there is no possibility of damaging the ceramic green sheet. Here, the (meth)acrylate compound refers to a group of compounds in which the methacryloyl group and acryloryl group in the molecule serve as cross-linking points and radical curing reaction proceeds.

Examples of (meth)acrylate compounds include acrylates, methacrylates, and urethane acrylates. Although each can be suitably used, it is more preferable to use urethane acrylate. When urethane acrylate is used, urethane bonds in the molecule can form hydrogen bonds, so that the strength of the cured coating film can be further increased. Hereinafter, the term urethane acrylate is used as a term including urethane methacrylate.

The number of functional groups in one molecule of the (meth)acrylate compound (the number of functional groups that can become cross-linking points in the radical curing reaction) is preferably 4 or more from the viewpoint of increasing the cross-linking density, and 6 or more. There is more preferably one, more preferably seven or more, and even more preferably nine or more. Although there is no particular upper limit to the number of functional groups, it is preferably 20 or less. By making it 20 or less, the intramolecular reaction proceeds more easily than the intermolecular cross-linking reaction, and there is no possibility that the effect of improving the cross-linking density will be lost, which is preferable.

The (meth)acrylate compound 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 using a monomer as a (meth) acrylate compound, for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, di pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, etc. .

When oligomers are used as (meth)acrylate compounds, for example, polyfunctional (meth)acrylate oligomers, polyester acrylate oligomers, epoxy acrylate oligomers, polyether acrylate oligomers, polybutadiene acrylate oligomers, silicone acrylate oligomers, etc. mentioned.

The urethane acrylate used in the present invention means one having a urethane bond and one or more radical-curing functional groups selected from acryloyl groups and methacryloyl groups in the molecular chain. Although the synthesis method is not particularly limited, it can be obtained, for example, by reacting a polyhydric alcohol and an organic polyisocyanate with hydroxyacrylate.

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 (e.g., succinic acid, phthalic acid, hexahydrophthalic anhydride, terephthalic acid, adipic acid, azelaic acid, tetrahydroanhydride polyester polyol obtained by reaction with phthalic acid, etc.); polycaprolactone polyol obtained by reaction of the above polyhydric alcohol with ε-caprolactone; polycarbonate polyol (for example, obtained by reaction of 1,6-hexanediol and diphenyl carbonate) polycarbonate diols, etc.); and polyether polyols. 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 isocyanate compounds such as isophorone diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, xylene diisocyanate, diphenylmethane-4,4′-diisocyanate and dicyclopentanyl isocyanate, adducts of these isocyanate compounds, or these Polymers of isocyanate and the like can be mentioned.

Examples of the hydroxy(meth)acrylate compounds include pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, hydroxyethyl (meth)acrylate, ) acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, dimethylolcyclohexyl 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 increasing the crosslink density.

Commercially available urethane acrylates can also be used in the present invention. Examples of commercially available products include UV1700B (10-functional), UV7620EA (9-functional), UV7610B (9-functional), UV7600B (6-functional), UV7650B (5-functional) manufactured by Nippon Kayaku Co., Ltd.: DPHA40H (10 functional), UX5003 (hexafunctional), Arakawa Chemical Industries: Beamset 577 (hexafunctional), Taisei Fine Chemicals: 8UX-015A (15 functional) and Shin-Nakamura Chemical: U15HA (15 functionality) and the like.

(Photo radical initiator)
When a radically polymerizable resin is used for the release layer in the present invention, it is preferable to add a radical photopolymerization initiator. Specific examples of photoradical polymerization initiators include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2, 4-diethylthioxanthone, 1-hydroxycyclohexylphenyl ketone, benzyldiphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, (2,4,6- trimethylbenzyldiphenyl)phosphine oxide, 2-benzothiazole-N,N-diethyldithiocarbamate and the like. In particular, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methylpropan-1-one, which is said to have excellent surface curability, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1 -one is preferred, especially 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one preferable. These may be used alone or in combination of two or more.

The amount of the radical photopolymerization initiator to be added is not particularly limited. For example, it is preferable to use about 0.1 to 20% by mass with respect to the radical curing resin used.

The binder component contained in the release layer in the present invention is preferably contained in an amount of 85% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass, based on the solid content of the entire release layer. is. By containing 85% by mass or more of the binder component, the release layer has a high cross-linking density, which increases the elastic modulus of the release layer and improves the solvent resistance of the surface of the release layer. Sometimes it can be peeled off with a low peeling force. In the present invention, components other than the binder component and the release agent component in the release layer, such as residual solvent, acid catalyst, photocationic initiator and photoradical initiator, are volatile or in trace amounts, and , the solid content of the entire release layer is the sum of the solid content of the binder component and the release agent.

(Release agent)
As the release agent (additive for improving the releasability of the release layer) used in the release layer in the present invention, silicone additives and non-silicone additives such as olefin-based, long-chain alkyl-based and fluorine-based additives However, from the viewpoint of releasability, it is preferable to use a silicone-based additive.

The silicone additive is a compound having a silicone skeleton in the molecule, and polyorganosiloxane or the like can be preferably used. Acrylic resins and alkyd resins having polyorganosiloxane in side chains can also be used. Among polyorganosiloxanes, polydimethylsiloxane (abbreviation: PDMS) can be preferably used, and polydimethylsiloxane having a functional group as a part thereof is also preferable. Having a functional group facilitates the expression of intermolecular interactions such as hydrogen bonding with the binder component, thereby improving the solvent resistance of the surface of the release layer, which is preferable.

Amino groups, epoxy groups, hydroxyl groups, mercapto groups, carboxyl groups, methacrylic groups, acryl groups, and the like can be used as reactive functional groups to be introduced into polydimethylsiloxane. As non-reactive functional groups, polyether groups, aralkyl groups, fluoroalkyl groups, long-chain alkyl groups, ester groups, amide groups, phenyl groups and the like can be used.

When a melamine-based compound is used as a binder, it is preferable to use carboxyl group-modified polydimethylsiloxane that exhibits moderate interaction with the hydroxyl group of the melamine-based compound, although it is not particularly limited. It is preferable to use the above-mentioned compound because it interacts with the binder while moderately segregating on the surface of the release layer, so that the solvent resistance of the surface of the release layer can be increased. By improving the solvent resistance of the surface of the release layer, it is possible to reduce the peel force at a low angle and at a high temperature, which is preferable.

Regarding carboxyl group-modified polydimethylsiloxane, carboxyl groups may be directly bonded to silicon atoms of polydimethylsiloxane, but carboxyl groups may be bonded to polydimethylsiloxane via alkyl groups or aryl groups. There may be. However, polydimethylsiloxane having carboxyl groups bonded via an organic group having a repeating structure such as polyether, polyester, or polyurethane is not very preferable.

When an epoxy-based compound is used as the binder, it is preferable to use epoxy-modified polydimethylsiloxane in consideration of the reactivity between the binder and polydimethylsiloxane. By using the above compound, it is preferable because it interacts with the binder while appropriately segregating on the surface of the release layer, so that the solvent resistance of the surface of the release layer can be increased. By improving the solvent resistance of the surface of the release layer, it is possible to reduce the peel force at a low angle and at a high temperature, which is preferable.

When using an acrylate compound as the binder, it is preferable to use an energy ray-curable copolymer having (meth)acryloyl groups and polyorganosiloxane groups in the molecule. It is preferable to use the above-mentioned compound because it segregates appropriately on the surface of the release layer and interacts with the binder, so that the solvent resistance of the surface of the release layer can be increased. By improving the solvent resistance of the surface of the release layer, it is possible to reduce the peel force at a low angle and at a high temperature, which is preferable.

The release layer in the present invention preferably contains 0.1% by mass or more and 15% by mass or less of the release agent based on the solid content of the entire release layer. It is more preferably 0.5% by mass or more and 10% by mass or less, and still more preferably 0.5% by mass or more and 5% by mass or less. When it is 0.1% by mass or more, the releasability is improved, and the releasability of the ceramic green sheet is improved, which is preferable. On the other hand, if it is 15% by mass or less, the elastic modulus of the entire release layer and the solvent resistance of the release layer surface do not decrease excessively, and the release layer deforms when the ceramic green sheet is peeled off, resulting in a large peeling force. It is preferable because it is difficult to At this time, the solid content of the entire release layer is the sum of the solid content of the binder component and the release agent.

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

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

In the present invention, the thickness of the release layer may be set according to the purpose of use, and is not particularly limited. Well, more preferably 0.05 to 1.3 μm, still more preferably 0.1 to 1.1 μm. It is preferable that the thickness of the release layer is 0.01 μm or more, because the release performance can be obtained. Further, when the thickness is 1.5 μm or less, the curing time can be shortened, the flatness of the release film can be maintained, and the thickness unevenness of the ceramic green sheet can be suppressed, which is preferable. In addition, when the thickness of the release layer is small, curling becomes small when the release film is heated.

The surface free energy of the release layer surface of the release layer film of the present invention is preferably 18 mJ/m ² or more and 40 mJ/m ² or less. It is more preferably 23 mJ/m ² or more and 35 mJ/m ² or less, still more preferably 23 mJ/m ² or more and 30 mJ/m ² or less. When it is 18 mJ/m ² or more, cissing is less likely to occur when the ceramic slurry is applied, and the coating can be uniformly applied, which is preferable. Also, if it is 40 mJ/m ² or less, it is preferable because there is no possibility that the releasability of the ceramic green sheet is deteriorated. By setting the content in the above range, it is possible to provide a release film that is free from repelling during coating and has excellent release properties.

The release film of the present invention preferably has a ceramic green sheet peel force F (T25/A90) at a peel temperature of 25° C. and a peel angle of 90° of 0.5 mN/mm or more, more preferably 1.0 mN. / mm or more. When the peel force F (T25/A90) is 0.5 mN/mm or more, the peel force is not too light, and there is no fear that the ceramic green sheet will lift during transportation, which is preferable. On the other hand, the peel force F (T25/A90) is preferably 4.5 mN/mm or less, more preferably 4.3 mN/mm or less. When the peel force is 4.5 mN/mm or less, the ceramic green sheet is less likely to be damaged during peeling, which is preferable.

The release film of the present invention preferably has a ceramic green sheet peel force F (T25/A30) at a peel temperature of 25° C. and a peel angle of 30° of 50.0 mN/mm or less, more preferably 45.0 mN/mm. mm or less. When the peel force F (T25/A30) is 50.0 mN/mm or less, the ceramic green sheet is less likely to be damaged during peeling at a low peel angle, which is preferable.

The release film of the present invention preferably has a ceramic green sheet peel force F (T50/A90) at a peel temperature of 50° C. and a peel angle of 90° of 7.0 mN/mm or less, more preferably 6.0 mN/mm. mm or less. When the peeling force F (T50/A90) is 7.0 mN/mm or less, the ceramic green sheet is less likely to be damaged during peeling at a high peeling temperature, which is preferable.

The release film of the present invention preferably has a ceramic green sheet peel force F (T50/A30) at a peel temperature of 50°C and a peel angle of 30° of 60.0 mN/mm or less, more preferably 45.0 mN/mm. mm or less. When the peel force F (T50/A30) is 60.0 mN/mm or less, the ceramic green sheet is less likely to be damaged during peeling at a low peeling angle and at a high peeling temperature, which is preferable.

In the measurement of the peel force in the present invention, a release film with a ceramic green sheet by the method described later is used as a sample for peel force measurement, and after static elimination, a peel tester (manufactured by Kyowa Interface Science Co., Ltd., VPA-3) is used. , at a peeling angle of 90° or 30°, a peeling temperature of 25°C or 50°C, and a peeling speed of 10 m/min as shown in FIG. As for the peeling direction, a double-sided adhesive tape (manufactured by Nitto Denko Co., Ltd., No. 535A) was attached to the SUS plate attached to the peel tester, and the ceramic green sheet side was adhered to the double-sided tape on the release film. was fixed and peeled off by pulling the release film side. Since the release film of the present invention has a low peeling force even at a peeling angle of 30 degrees, it is particularly suitable for producing an ultra-thin ceramic green sheet.

In the present invention, the elastic modulus of the release layer surface measured by a nanoindentation test is preferably 2.0 GPa or more, preferably 2.3 GPa or more, in order to achieve the above-mentioned peel strength. When the release layer surface has an elastic modulus of 2.0 GPa or more, the release layer becomes difficult to deform, so that when the release layer is peeled off the ceramic green sheet, the release layer follows the ceramic green sheet. Therefore, the ceramic green sheet can be normally peeled off with a light force, which is preferable. On the other hand, although the upper limit of the elastic modulus of the film on the surface of the release coating layer is not particularly defined, it is preferably 10.0 GPa or less from the viewpoint of maintaining appropriate adhesion between the release coating layer and the PET substrate. It is more preferably 0 GPa or less.

In the present invention, in order to achieve the above-mentioned peel strength, it is preferable that the corrosion by the organic solvent is small. 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 an organic solvent. As the organic solvent used for the immersion, it is preferable to use toluene, which is used for a general ceramic slurry, assuming the ceramic green sheet manufacturing process. An example of a method for evaluating the surface state of the release layer is the evaluation based on the contact angle, and the smaller the change in the contact angle of the release layer surface before and after immersion in toluene, the better.

The type of droplet used for measuring the contact angle is not particularly limited, and water, bromonaphthalene, ethylene glycol, and the like can be suitably used. Most preferably, diiodomethane is used.

When using diiodomethane as a droplet used for measuring the contact angle, the diiodomethane contact angle θ ₁ on the release layer surface and the contact angle θ ₂ on the release layer surface after the release film was immersed in toluene at room temperature for 5 minutes. The smaller the absolute value of the difference (θ ₁ −θ ₂ ), the better the solvent resistance of the surface of the release layer. Specifically, the absolute value is preferably 3.0° or less, more preferably 2.0° or less, and most preferably 1.0° or less. When the angle is 3.0° or less, erosion of the release layer by an organic solvent during processing of the ceramic green sheet or printing of the internal electrodes is suppressed, and there is no risk of an increase in the peeling force or loss of uniformity of peeling, which is preferable. The difference (θ ₁ - _{θ 2} ) between the diiodomethane contact angle θ ₁ on the release layer surface and the contact angle θ ₂ on the release layer surface after immersing the release film in toluene at room temperature for 5 minutes is most preferably 0°. , may be 0.05° or more as an absolute value.

In the present invention, in order to achieve the above peel strength, the initial contact angle of diiodomethane on the release layer surface is preferably 45.0° or more, more preferably 50.0° or more, and more preferably 55.0°. ° or more is most preferable. When the initial contact angle of diiodomethane on the surface of the release layer is 45.0° or more, the release agent that reduces the release force is appropriately exposed to the surface of the release layer, so the release force can be lowered, which is preferable. . The initial contact angle of diiodomethane on the release layer surface is preferably 100.0° or less, more preferably 90.0° or less, and most preferably 80.0° or less. When the initial contact angle of diiodomethane on the surface of the release layer is 100.0° or less, the wettability of the ceramic sheet is not excessively deteriorated and uniform coating can be achieved, which is preferable.

In the present invention, the method for forming the release layer is not particularly limited. is removed by drying, followed by heat drying and heat curing.

In the present invention, when a thermosetting resin such as melamine is used as a binder in the release layer, the drying temperature during solvent drying and thermosetting is preferably 100° C. or higher and 180° C. or lower, preferably 110° C. or higher, It is more preferably 160°C or lower, and most preferably 125°C or higher and 150°C or lower. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less. When the temperature is 180° C. or lower, the flatness of the film is maintained, and the possibility of causing unevenness in the thickness of the ceramic green sheet is small, which is preferable. When the temperature is 140° C. or lower, the film can be processed without impairing the flatness of the film, and the possibility of causing unevenness in the thickness of the ceramic green sheet is further reduced, which is particularly preferred. When the temperature is 100° C. or higher, the curing reaction of the thermosetting resin proceeds sufficiently, and the elastic modulus of the release layer increases, which is preferable.

When an active energy ray-curable resin such as epoxy or acrylate is used as a binder for the release layer in the present invention, the drying temperature for solvent drying is preferably 50°C or higher and 110°C or lower, and preferably 60°C or higher and 100°C. °C or less is more preferable. The drying time is preferably 30 seconds or less, more preferably 20 seconds or less. Further, after the solvent is dried, an active energy ray is irradiated to advance the curing reaction. As the active energy rays used at this time, ultraviolet rays, electron beams, X-rays, and the like can be used, but ultraviolet rays are preferable because they are easy to use. The amount of ultraviolet light to be irradiated is preferably 30 to 300 mJ/cm ² , more preferably 30 to 200 mJ/cm ² , and still more preferably 30 to 80 mJ/cm ² . If it is 30 mJ/cm ² or more, the curing of the resin will proceed sufficiently, and if it is 300 mJ/cm ² or less, the processing speed can be improved, which is preferable because the release film can be produced economically. .

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

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

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

The surface of the release layer of the release film of the present invention is desirably flat so as not to cause defects in the ceramic green sheet coated and molded thereon, and the area surface average roughness (Sa) is 7 nm or less. Preferably. Further, it is more preferable that the above Sa is satisfied and the maximum projection height (P) on the release layer surface is 100 nm or less. It is particularly preferable if the region surface average roughness (Sa) is 5 nm or less and the maximum projection height is 80 nm or less. If the surface roughness of the region is 7 nm or less and the maximum protrusion height is 100 nm or less, defects such as pinholes do not occur when the ceramic green sheets are formed, and the yield is good, which is preferable. It can be said that the smaller the region surface average roughness (Sa) is, the more preferable it is. It can be said that the smaller the maximum projection height (P) is, the more preferable it is, but the maximum projection height (P) may be 1 nm or more, or 3 nm or more.

In the present invention, the PET film preferably contains substantially no inorganic particles in order to adjust the surface roughness of the film on which the release coating layer is formed within a predetermined range. The term "substantially free of inorganic particles" as used in the present invention means that, for both the base film and the release coating layer, when the elements derived from the particles are quantitatively analyzed by fluorescent X-ray analysis, the content is 50 ppm or less. is preferably 10 ppm or less, most preferably the detection limit or less. This is because even if particles are not actively added to the base film, contaminants derived from foreign substances and dirt adhering to the lines and equipment in the raw material resin or film manufacturing process will peel off and enter the film. This is because there are cases where

(ceramic green sheet and ceramic capacitor)
Generally, a multilayer ceramic capacitor has a rectangular parallelepiped ceramic body. Inside the ceramic body, first internal electrodes and second internal electrodes are alternately provided along the thickness direction. The first internal electrode is exposed on the first end surface of the ceramic body. A first external electrode is provided on the first end surface. The first internal electrode is electrically connected to the first external electrode at the first end surface. The second internal electrode is exposed on the second end face of the ceramic body. A second external electrode is provided on the second end surface. The second internal electrode is electrically connected to the second external electrode at the second end surface.

The release film for producing ceramic green sheets of the present invention is used for producing such a laminated 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. The coated and dried ceramic green sheet preferably has a thickness of 0.2 μm to 1.0 μm. A conductive layer for forming the first or second internal electrode is printed on the coated and dried ceramic green sheet. Ceramic green sheets, ceramic green sheets printed with conductive layers for forming first internal electrodes, and ceramic green sheets printed with conductive layers for forming second internal electrodes are appropriately laminated and pressed. Thus, a mother laminate is obtained. The mother laminate is divided into a plurality of pieces to produce raw ceramic bodies. A ceramic body is obtained by firing a raw ceramic body. After that, the multilayer ceramic capacitor can be completed by forming the first and second external electrodes.

EXAMPLES The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. The characteristic values used in the present invention were evaluated using the following methods.

(Surface roughness)
These are values measured under the following conditions using a non-contact surface profile measurement system (VertScan R550H-M100). The area surface average roughness (Sa) was the average value of 5 measurements, and the maximum protrusion height (P) was measured 7 times, and the maximum value of the 5 measurements excluding the maximum and minimum values was used.
(Measurement condition)
・Measurement mode: WAVE mode ・Objective lens: 10x ・0.5×Tube lens ・Measurement area: 936 μm×702 μm
(analysis conditions)
・Surface correction: Quaternary correction ・Interpolation processing: Complete interpolation

(Method for producing release film with ceramic green sheet)
A composition comprising the following materials was stirred and mixed, and dispersed for 60 minutes using a bead mill containing zirconia beads with a diameter of 0.5 mm as a dispersoid to obtain a ceramic slurry.
Toluene 43.75 parts by mass Ethanol 43.75 parts by mass Barium titanate (HPBT-1 manufactured by Fuji Titanium Co., Ltd.) 10.86 parts by mass Polyvinyl butyral (Eslec BM-S manufactured by Sekisui Chemical Co., Ltd.) 1.09 parts by mass DOP (phthalic acid Dioctyl) 0.55 parts by mass Next, the slurry after drying was applied to the release surface of the obtained release film sample using an applicator so as to have a thickness of 1.0 μm, and dried at 90° C. for 2 minutes to form a ceramic green sheet. was molded on a release film.

(Evaluation of peelability of ceramic green sheet)
The release film with a ceramic green sheet prepared by the above method was cut into a 30 mm wide and 80 mm long piece to prepare a sample for peel force measurement. After static elimination using a static eliminator (manufactured by Keyence Corporation, SJ-F020), using a peel tester (manufactured by Kyowa Interface Science Co., Ltd., VPA-3), a peel angle of 90 degrees or 30 degrees, a peel temperature of 25 ° C. or 50 °C and a peeling speed of 10 m/min. As for the peeling direction, a double-sided adhesive tape (manufactured by Nitto Denko Co., Ltd., No. 535A) was attached to the SUS plate attached to the peel tester, and the ceramic green sheet side was adhered to the double-sided tape on the release film. was fixed and peeled off by pulling the release film side. Among the obtained measured values, the average peel force at a peel distance of 20 mm to 70 mm was calculated, and this value was defined as the peel force. The measurement was carried out a total of 5 times, and the average value of the peel strength was used for evaluation. Judgment was made according to the following criteria from the numerical value of the obtained peel strength.
○: 45.0 mN / mm or less △: greater than 45.0 mN / mm, 60.0 mN / mm or less ×: greater than 60.0 mN / mm The peel angle in this evaluation method is fixed to the peel tester. It refers to the angle of the direction in which the release film is pulled with respect to the evaluation sample axis. The peeling temperature is the temperature when the fixed release film is heated using a heater-type stage system attached to the apparatus. Using a handy type thermometer (manufactured by Anritsu Keiki Co., Ltd., HD-1400E), peeling is performed after confirming that the measured sample has reached the corresponding temperature.

(contact angle)
Diiodomethane (droplet amount A droplet of 0.9 μL) was prepared and its contact angle was measured. For the contact angle, the contact angle 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)
A release film used for measurement was cut into a size of 5 cm×5 cm, and immersed in a glass tray containing 30 mL of toluene at a liquid temperature of 25° C. for 5 minutes with the release surface facing downward. The immersed release film was taken out, and air-dried for 15 minutes with the release surface facing up, and then vacuum-dried overnight at 25°C. The release film thus obtained after immersion in toluene was measured by the same method as the method for measuring the contact angle.

When the initial diiodomethane contact angle on the release layer surface before immersion in toluene measured by the above method is θ ₁ , and the diiodomethane contact angle on the release layer surface after immersion in toluene is θ ₂ , θ ₁ - _{θ 2} The absolute value was taken as the change in contact angle before and after immersion in toluene. The initial contact angle and change in contact angle were evaluated according to the following criteria.
(Evaluation of initial contact angle)
○: 45.0° ≤ _θ1
×: θ ₁ < 45.0°
(Evaluation of contact angle change)
◎: |θ ₁ −θ ₂ | < 1.0°
○: 1.0° ≤ |θ ₁ - θ ₂ | < 2.0°
△: 2.0° ≤ |θ ₁ - θ ₂ | ≤ 3.0°
×: |θ ₁ -θ ₂ | > 3.0°

(Release layer elastic modulus evaluation)
The release films obtained in Examples and Comparative Examples were cut to a size of 10 mm × 10 mm, and then the back surface of the cut release film was adhered to a glass plate adhered to an aluminum pedestal by two-liquid epoxy bonding. fixed with an agent. Then, using a microhardness evaluation device (manufactured by Elionix, ENT-3100), a nanoindentation test was performed in an atmosphere at a maximum indentation depth of 50 nm and 23 ° C., and the release layer of the release film. was measured. Table 2 shows the results.

(Preparation of polyethylene terephthalate pellets (PET (I)))
As the esterification reactor, a continuous esterification reactor comprising a three-stage complete mixing tank having a stirrer, a partial condenser, a raw material inlet and a product outlet was used. TPA (terephthalic acid) was adjusted to 2 tons/hour, EG (ethylene glycol) was adjusted to 2 mol per 1 mol of TPA, and antimony trioxide was adjusted to give an amount of Sb atoms of 160 ppm relative to the produced PET. It was continuously supplied to the first esterification reactor of the reaction apparatus and reacted at 255° C. for an average residence time of 4 hours under normal pressure. Next, the reaction product in the first esterification reaction can is continuously taken out of the system and supplied to the second esterification reaction can, and distilled off from the first esterification reaction can into the second esterification reaction can. 8 mass % of EG is supplied to the produced PET, and further, an EG solution containing magnesium acetate tetrahydrate in an amount such that the Mg atom is 65 ppm relative to the produced PET, and an EG solution containing 40 ppm of P atom relative to the produced PET. An EG solution containing TMPA (trimethyl phosphate) in an amount corresponding to the above was added and reacted at 260° C. under normal pressure for an average residence time of 1 hour. Next, the reaction product in the second esterification reactor was continuously taken out of the system and supplied to the third esterification reactor, and was subjected to 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 having an average particle size of 0.9 μm, which has been subjected to dispersion treatment for an average number of 5 passes at a pressure of , and 1% by mass of ammonium salt of polyacrylic acid per calcium carbonate. While adding 0.4% by mass of synthetic calcium carbonate with a diameter of 0.6 μm as a 10% EG slurry, the mixture was reacted at normal pressure at 260° C. for an average residence time of 0.5 hours. The esterification reaction product produced in the third esterification reaction vessel was continuously supplied to a three-stage continuous polycondensation reactor for polycondensation to sinter stainless steel fibers having a 95% cut diameter of 20 μm. After filtration with a filter, ultrafiltration was performed, the product was extruded into water, and after cooling, it was cut into chips to obtain PET chips having an intrinsic viscosity of 0.60 dl/g (hereinafter abbreviated as PET (I)). . The lubricant content in the PET chip was 0.6% by mass.

(Preparation of polyethylene terephthalate pellets (PET (II)))
On the other hand, in the production of the PET(I) chip, a PET chip containing no particles of calcium carbonate, silica, etc. and having an intrinsic viscosity of 0.62 dl/g was obtained (hereinafter abbreviated as PET(II)).

(Production of laminated film X1)
After drying these PET chips, they were melted at 285° C. and melted at 290° C. by a separate melt extruder extruder to filter sintered stainless steel fibers with a 95% cut diameter of 15 μm and Two-stage filtration of sintered stainless steel particles of 15 μm is performed, and they are combined in the feed block to form PET (I) on the surface layer B (anti-releasing surface side layer) and PET (II) on the surface. Laminated so as to form layer A (releasing surface side layer), extruded (cast) into a sheet at a speed of 45 m / min, electrostatically adhered on a casting drum at 30 ° C. by an electrostatic adhesion method, cooled, An unstretched polyethylene terephthalate sheet having an intrinsic viscosity of 0.59 dl/g was obtained. The layer ratio was adjusted so that PET (I)/(II)=60% by mass/40% by mass by calculating the discharge amount of each extruder. Then, the unstretched sheet was heated with an infrared heater and then stretched 3.5 times in the machine direction at a roll temperature of 80° C. due to the speed difference between the rolls. After that, it was led to a tenter and stretched 4.2 times in the transverse direction at 140°C. It was then heat treated at 210° C. in a heat setting zone. After that, a 2.3% relaxation treatment was applied in the transverse direction at 170° C. to obtain a biaxially stretched polyethylene terephthalate film X1 having a thickness of 31 μm. The Sa of the surface layer A of the obtained film X1 was 2 nm, and the Sa of the surface layer B was 28 nm.

(binder component)
The following materials were used as binder components.
(A-1) Epoxy compound (alicyclic epoxy compound)
3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate (product name: Celoxide (registered trademark) 2021P, manufactured by Daicel Corporation, solid content 100% by mass)
(A-2) Epoxy compound (alicyclic epoxy compound)
Butanetetracarboxylic acid tetra(3,4-epoxycyclohexylmethyl-modified ε-caprolactone (product name: Epolead (registered trademark) GT401, manufactured by Daicel Corporation, solid content 100% by mass)
(A-3) Epoxy compound (alicyclic epoxy compound)
Polyfunctional alicyclic epoxy group-containing polymer (product name: EHPE (registered trademark) 3150, manufactured by Daicel Corporation, solid content 100% by mass)
(B-1) Acrylate compound (hexafunctional)
Dipentaerythritol hexaacrylate (product name: A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd., solid content 100% by mass)
(B-2) Acrylate-based compound (10-functional)
10-functional urethane acrylate (product name: Shiko (registered trademark) UV1700B, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., solid content 100% by mass)
(C-1) Melamine compound Hexamethoxymethyl melamine, solid content 100%, manufactured by Tokyo Chemical Industry Co., Ltd. (product name N,N,N',N',N'',N''-hexakis (methoxymethyl) melamine, molecular weight 390)
(C-2) Melamine-based compound Hexamethoxymethylmelamine, solid content 100%, manufactured by MT Aquapolymer (product name Cymel 303)

(Example 1)
Coating solution 1 having the following composition was applied on surface layer A of laminated film X1 using reverse gravure so that the thickness of the release layer after drying was 0.8 μm, dried at 90° C. for 15 seconds, and applied at 70 mJ. A release film for producing a ceramic green sheet was obtained by irradiating ultraviolet rays at a rate of 1/cm ² using an ultraviolet irradiation machine (manufactured by Heraeus, LC6B, H bulb). A ceramic slurry was applied to the obtained release film by the method described above, and the release force was evaluated. As a result, good evaluation results were obtained.
(Coating liquid 1)
Methyl ethyl ketone 43.70 parts by mass Toluene 43.70 parts by mass Binder component (A-1) 9.00 parts by mass (product name: Celoxide (registered trademark) 2021P, manufactured by Daicel Corporation, solid content 100% by mass))
Release agent 1.00 parts by mass (alicyclic epoxy group-containing silicone resin, UV POLY215, solid content 100%, manufactured by Arakawa Chemical Industries, Ltd.)
Photo cationic initiator 2.60 parts by mass (UV CATA211, active ingredient 19% by mass, manufactured by Arakawa Chemical Industries, Ltd.)

(Example 2)
A release film for producing a ceramic green sheet was obtained in the same manner as in Example 1, except that the composition was changed to coating liquid 2 having the composition shown below.
(Coating liquid 2)
Methyl ethyl ketone 43.70 parts by mass Toluene 43.70 parts by mass Binder component (A-2) 9.00 parts by mass (Product name: Epolead (registered trademark) GT401, manufactured by Daicel Corporation, solid content 100%)
Release agent 1.00 parts by mass (alicyclic epoxy group-containing silicone resin, UV POLY215, solid content 100%, manufactured by Arakawa Chemical Industries, Ltd.)
Photo cationic initiator 2.60% mass parts
(UV CATA211, active ingredient 19% by mass, manufactured by Arakawa Chemical Industries, Ltd.)

(Example 3)
A release film for producing a ceramic green sheet was obtained in the same manner as in Example 1, except that the coating liquid was changed to coating liquid 3 having the composition shown below.
(Coating liquid 3)
Methyl ethyl ketone 44.50 parts by mass Toluene 44.50 parts by mass Binder component (A-3) 9.00 parts by mass ((Product name: EHPE (registered trademark) 3150, manufactured by Daicel Corporation, solid content 100% by mass)
Release agent 1.00 parts by mass (alicyclic epoxy group-containing silicone resin, UV POLY215, solid content 100%, manufactured by Arakawa Chemical Industries, Ltd.)
Photo cationic initiator 1.00% by mass (Hexafluoroantimonate triarylsulfonium salt)
(Product name: CPI (registered trademark) 101A, active ingredient 50% by mass, manufactured by San-Apro)

(Example 4)
A release film for producing a ceramic green sheet was obtained in the same manner as in Example 1, except that coating liquid 1 was changed to coating liquid 4.
(Coating liquid 4)
Isopropyl alcohol 59.40 parts by mass Methyl ethyl ketone 19.80 parts by mass Binder component (B-1) 19.00 parts by mass (Dipentaerythritol hexaacrylate Product name: A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd., solid content 100% by mass )
(Meth) acryloyl group-containing copolymer silicone acrylic polymer 1.00 parts by mass (product name: GL-04R, manufactured by Kyoeisha Chemical Co., Ltd., solid content 20%)
α-Hydroxyalkylphenone 0.80 parts by mass (product name: IRGACURE127, manufactured by BASF, active ingredient 100%)

(Example 5)
A release film for producing a ceramic green sheet was obtained in the same manner as in Example 1, except that coating liquid 1 was changed to coating liquid 5.
(Coating liquid 5)
Isopropyl alcohol 59.40 parts by mass Methyl ethyl ketone 19.80 parts by mass Binder component (B-2) 19.00 parts by mass (10-functional urethane acrylate acrylate Product name: Shiko (registered trademark) UV1700B, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., solid content 100% by mass)
(Meth) acryloyl group-containing copolymer silicone acrylic polymer 1.00 parts by mass (product name: GL-04R, manufactured by Kyoeisha Chemical Co., Ltd., solid content 20%)
α-Hydroxyalkylphenone 0.80 parts by mass (product name: IRGACURE127, manufactured by BASF, active ingredient 100%)

(Example 6)
A coating liquid 6 having the following composition was applied on the surface layer A of the laminated film X1 using reverse gravure so that the thickness of the release layer after drying was 0.6 μm, and dried at 140° C. for 15 seconds. A release film for manufacturing a ceramic green sheet was obtained.
(Coating liquid 6)
Methyl ethyl ketone 44.50 parts by mass Toluene 44.50 parts by mass Binder (C-1) 10.00 parts by mass (Hexamethoxymethyl melamine, solid content 100%, manufactured by Tokyo Chemical Industry Co., Ltd., trade name N,N,N',N ',N'',N''-hexakis(methoxymethyl)melamine, molecular weight 390))
Release agent 0.50 parts by mass (single-end carboxyl-modified polydimethylsiloxane, X22-3710, solid content 100%, manufactured by Shin-Etsu Chemical Co., Ltd., alkyl group interposed between dimethylsiloxane and carboxyl group)
Acid catalyst (p-toluenesulfonic acid) 0.50 parts by mass

(Example 7)
A release film for producing a ceramic green sheet was obtained in the same manner as in Example 6, except that the amount of release agent (X22-3710) added to coating liquid 6 of Example 6 was changed to 0.20 parts by mass.

(Example 8)
The procedure was the same as in Example 6 except that the amount of hexamethoxymethylmelamine added to coating liquid 6 of Example 6 was changed to 9.0 parts by mass and the amount of release agent (X22-3710) added was changed to 1.0 parts by mass. to obtain a release film for producing a ceramic green sheet.

(Example 9)
The procedure of Example 6 was repeated except that the amount of hexamethoxymethylmelamine added to coating liquid 6 of Example 6 was changed to 8.0 parts by mass and the amount of release agent (X22-3710) added was changed to 2.0 parts by mass. to obtain a release film for producing a ceramic green sheet.

(Examples 10-12)
A release film for producing a ceramic green sheet was obtained in the same manner as in Example 6, except that the thickness of the release layer of Example 6 was changed to the thickness shown in Table 2.

(Comparative example 1)
A release film for producing a ceramic green sheet was obtained in the same manner as in Example 1, except that coating liquid 1 was changed to coating liquid 7. In Comparative Example 1, polyether-modified silicone, which does not interact with the epoxy binder component, was used, so that the release layer surface had poor solvent resistance and remarkably high peel strength at low angles and high temperatures.
(Coating liquid 7)
Methyl ethyl ketone 43.70 parts by mass Toluene 43.70 parts by mass Binder component (A-1) 9.00 parts by mass (product name: Celoxide (registered trademark) 2021P, manufactured by Daicel Corporation, solid content 100% by mass))
Release agent 1.00 parts by mass (polyether-modified silicone resin, BYK-302, solid content 100%, manufactured by Arakawa Chemical Industries, Ltd.)
Photo cationic initiator 2.60 parts by mass (UV CATA211, active ingredient 19% by mass, manufactured by Arakawa Chemical Industries, Ltd.)

(Comparative example 2)
A release film for producing a ceramic green sheet was obtained in the same manner as in Example 1, except that coating liquid 1 was changed to coating liquid 8. In Comparative Example 2, the solvent resistance near the surface of the release layer deteriorated due to the use of a release agent having a main chain of polydimethylsiloxane and the inhibition of surface curing due to oxygen peculiar to radical polymerization. . As a result, although the release layer had a high elastic modulus, the peel strength at a low angle and at a high temperature was remarkably high because the solvent resistance of the surface of the release layer was poor.
(Coating liquid 8)
Isopropyl alcohol 60.00 parts by mass Methyl ethyl ketone 20.00 parts by mass Binder component (B-1) 19.00 parts by mass (Dipentaerythritol hexaacrylate Product name: A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd., solid content 100% by mass )
Acryloyl group-containing polyether-modified polydimethylsiloxane 0.20 parts by mass (product name: BYK-UV3500, manufactured by Big Chemie Japan, solid content 100%)
α-Hydroxyalkylphenone 0.80 parts by mass (product name: IRGACURE127, manufactured by BASF, active ingredient 100%)

(Comparative Example 3)
A release film for producing a ceramic sheet was obtained in the same manner as in Example 6, except that coating liquid 6 was changed to coating liquid 9 below. In Comparative Example 3, in which a large amount of release agent was added and the melamine resin was only 70% by mass of the release layer, the release layer had a low elastic modulus and poor solvent resistance on the surface of the release layer. has grown. In particular, the peel strength at low angles and high temperatures was remarkably increased.
(Coating liquid 9)
Methyl ethyl ketone 44.80 parts by mass Toluene 44.80 parts by mass Binder (C-1) 7.00 parts by mass (Hexamethoxymethyl melamine, solid content 100%, manufactured by Tokyo Chemical Industry Co., Ltd.)
Release agent 3.00 parts by mass (single-end carboxyl-modified polydimethylsiloxane, X22-3710, solid content 100%, manufactured by Shin-Etsu Chemical Co., Ltd.)
Acid catalyst (p-toluenesulfonic acid) 0.40 parts by mass

(Comparative Example 4)
A release film for producing a ceramic sheet was obtained in the same manner as in Example 1, except that coating liquid 1 was changed to coating liquid 10 below. The interaction between the hydroxyl group of the release agent and the melamine resin is strong, and the release agent does not appear on the surface. became higher.
(Coating liquid 10)
Methyl ethyl ketone 44.75 parts by mass Toluene 44.75 parts by mass Binder (C-2) 9.00 parts by mass (Hexamethoxymethyl melamine, solid content 100%, manufactured by MT Aquapolymer, trade name Cymel 303)
Release agent 1.00 parts by mass (polydimethylsiloxane containing polyester-modified OH group, BYK-370, solid content 25%, manufactured by BYK-Chemie Japan)
Acid catalyst (p-toluenesulfonic acid) 0.50 parts by mass

Tables 1 and 2 show the evaluation results of each example and comparative example.

In Examples 1 to 12, the peel strength at a peel angle of 30° and a peel temperature of 50° C. was low, so that the ceramic sheets could be peeled off without damaging them, and high-quality ceramic capacitors could be obtained. In Comparative Examples 1 to 4, the peeling force at a peeling angle of 30° and a peeling temperature of 50°C was high.

According to the present invention, when the peeling temperature between the ceramic green sheet and the release film is high, the peeling force is low even when the peeling angle is low, and the ceramic green sheet is an ultra-thin layer that can suppress damage to the ceramic green sheet. Sheets can be manufactured.

1: SUS plate 2: Double-sided adhesive tape 3: Ceramic green sheet 4: Release layer 5: Polyester film substrate 6: Pulling direction 7: Peeling angle 8: Release film 9: Release film with ceramic green sheet

Claims (10)

A polyester film is used as a base material, and the base material has a surface layer A on at least one side that does not substantially contain inorganic particles,
A release film in which a release layer is laminated directly or via another layer on at least one surface layer A surface,
The release layer contains at least a release agent and a binder component,
When a ceramic green sheet is formed on the release layer, the release force F (T50/A90) at a release temperature of 50°C and a release angle of 90° between the ceramic green sheet and the release film is 7.0 mN/mm or less. can be,
The polyester film base has a surface layer B on the side opposite to the surface layer A,
The area surface average roughness (Sa) of the surface layer A is smaller than the area surface average roughness (Sa) of the surface layer B,
The binder component in the release layer contains at least one crosslinked product of a melamine-based compound, an epoxy-based compound, and an acrylate-based compound,
When the binder component contains an epoxy compound, the binder component further contains a photocationic polymerization initiator,
The release agent contains a silicone skeleton,
Furthermore, having at least one functional group selected from the group consisting of an epoxy group, an acryloyl group and a carboxyl group,
The content of the release agent is 0.1% by mass or more and 15% by mass or less with respect to the solid content of the release layer,
The ceramic green sheet used for measuring the peeling force F is
A ceramic green sheet formed from a composition containing toluene, ethanol and barium titanate,
The composition contains equal amounts of toluene and ethanol.
Release film for manufacturing ceramic green sheets. 2. The ceramic green sheet production according to claim 1, wherein the film elastic modulus measured from the surface of the release layer opposite to the substrate is 2.0 GPa or more by a nanoindentation test on the release layer. release film. 3. The ceramic according to claim 1 or 2, wherein the release layer is formed by curing a coating film containing at least the release agent and the binder component, and the binder component is 85% by mass or more of the solid content of the release layer. Release film for green sheet production. 4. The release film for producing a ceramic green sheet according to claim 3, wherein the composition forming the ceramic green sheet used for measuring the peel force F contains polyvinyl butyral. The release film for producing a ceramic green sheet according to any one of claims 1 to 4, wherein the release layer has a thickness of 0.01 µm to 1.5 µm. The mold release for producing a ceramic green sheet according to any one of claims 1 to 5, wherein the ceramic green sheet used for measuring the peeling force F is a ceramic green sheet formed from a composition containing barium titanate. the film. The surface layer B forming the surface layer opposite to the surface layer A of the polyester film base contains particles, the particles are silica particles and / or calcium carbonate particles, and the total of the particles is the surface layer B The release film for producing a ceramic green sheet according to any one of claims 1 to 6, containing 5000 to 15000 ppm in the release film. The area surface average roughness (Sa) of the surface layer A is 0.1 nm or more and 7 nm or less, and the area surface average roughness (Sa) of the film of the surface layer B is 1 to 40 nm. A release film for producing a ceramic green sheet according to any one of the above. A method for producing a ceramic green sheet by molding a ceramic green sheet using the release film for producing a ceramic green sheet according to any one of claims 1 to 8, wherein the molded ceramic green sheet has a thickness of 0.2 μm to 1 μm. A method for producing a ceramic green sheet having a thickness of 0 μm. A method for manufacturing a ceramic capacitor employing the method for manufacturing a ceramic green sheet according to claim 9 .