TWI848029B - Release film, method for producing release film, method for producing ceramic green body, and method for producing ceramic capacitor - Google Patents

Abstract

The present invention provides a release film that can be manufactured with reduced manufacturing costs, and even when the sheet formed on the release layer is further thinned, it can have all the characteristics of good wettability to sheet slurry and resin solution, and appropriate sheet peeling force. The release film of the present invention has a release layer on at least one side of a polyester film directly or through another layer, and the release layer is formed by curing a composition, and the composition contains: an acrylic resin introduced with a long-chain alkyl group, and at least one crosslinking agent selected from an oxazoline crosslinking agent or a carbodiimide crosslinking agent.

Description

Release film, method for producing release film, method for producing ceramic green body, and method for producing ceramic capacitor

The present invention relates to a release film. More specifically, it relates to a release film that can be manufactured at a reduced manufacturing cost and has all the properties of good wettability to slurry and resin solution and moderate sheet peeling force even when the sheet formed on the release layer is further thinned. For example, it can be particularly preferably used for manufacturing ceramic green sheets, which are intermediate products in the manufacturing steps of ceramic laminate capacitors.

Release film is a member used to shape and peel the sheet to be peeled evenly and without damage. Examples of the sheet include ceramic green sheets, sheets containing other particles and resins, or resin sheets.

Release films are mainly manufactured using off-line coating, which involves applying a solvent-based release formulation to the substrate film obtained in the film-making step in another step (see, for example, Patent Document 1). However, in the prior art, the film-making step of the film substrate and the release layer processing step are different steps, which is a major cause of increased costs.

Therefore, the following technology is disclosed: in the film-making step, a water-based release formula is applied by in-line coating to produce a release film (for example, refer to patent documents 2 and 3). However, according to the prior art, since the main resin of the water-based release formula is a silicone resin, there is a problem that the surface free energy becomes too low, and when the film is further thinned, pinholes are generated due to poor wetting of the slurry or the resin solution. [Prior art document] [Patent document]

[Patent Document 1] Japanese Patent Publication No. 2010-155459. [Patent Document 2] Japanese Patent Publication No. 2010-017932. [Patent Document 3] Japanese Patent Publication No. 2013-208810.

[The problem that the invention wants to solve]

The present invention is completed with the above-mentioned prior art as the background. That is, the purpose of the present invention is to provide a release film that can be produced while suppressing the manufacturing cost, and even when the sheet formed on the release layer is further thinned, it can also have all the characteristics of good wettability of the sheet slurry and the resin solution, and appropriate sheet peeling force. [Means for solving the problem]

The inventors of the present invention have made great efforts to achieve the above-mentioned purpose, and have completed the present invention. That is, the present invention has the following structure. 1. A release film comprising a polyester film and a release layer, and having a release layer on at least one side of the polyester film directly or via other layers, the release layer being formed by curing a composition, wherein the composition contains: an acrylic resin having a long-chain alkyl group, and at least one crosslinking agent selected from an oxazoline crosslinking agent or a carbodiimide crosslinking agent. 2. A release film as described in the above 1, wherein the acrylic resin contains an acrylate monomer containing a long-chain alkyl group, and the copolymerization ratio of the acrylate monomer containing a long-chain alkyl group in the acrylic resin is 5 mol% or more and 60 mol% or less. 3. A release film as described in item 1 or 2 above, wherein the crosslinking agent is an oxazoline crosslinking agent, and the oxazoline crosslinking agent contains 3.0 mmol/g to 9.0 mmol/g of oxazoline groups. 4. A release film as described in any one of items 1 to 3 above, wherein the acid value of the acrylic resin having a long-chain alkyl group is 40 mgKOH/g or more and 400 mgKOH/g or less. 5. A release film as described in any one of items 1 to 4 above, wherein the thickness of the release layer is 0.001 μm or more and 2 μm or less. 6. A release film as described in any one of items 1 to 5 above, wherein the release film is a release film for manufacturing ceramic green bodies. 7. A method for producing a release film, comprising producing a release film comprising a polyester film and a release layer; wherein the release film has a release layer on at least one side of the polyester film directly or via another layer, and the release layer is formed by curing a composition, wherein the composition contains: an acrylic resin having a long-chain alkyl group, and at least one crosslinking agent selected from an oxazoline-based crosslinking agent or a carbodiimide-based crosslinking agent; after applying a release coating liquid to an unstretched film or a uniaxially stretched film, the film is stretched along at least a uniaxial direction of the unstretched film, and heat-treated. 8. A method for producing a release film as described in item 7 above, wherein the method for producing a release film is a method for producing a release film for producing a ceramic green body. 9. A method for manufacturing a ceramic green body, wherein the ceramic green body is formed using the release film for manufacturing a ceramic green body as described in the above 6, or the release film for manufacturing a ceramic green body as described in the above 8. 10. A method for manufacturing a ceramic green body as described in the above 9, wherein the thickness of the manufactured ceramic green body is greater than 0.2 μm and less than 2.0 μm. 11. A method for manufacturing a ceramic capacitor, wherein the method for manufacturing a ceramic green body as described in the above 9 or 10 is used. [Effect of the invention]

According to the present invention, a release film can be provided which can be produced while suppressing the production cost and which has all the characteristics of good wettability with sheet slurry and resin solution and appropriate sheet peeling force even when the formed sheet is made thinner.

The present invention is described in detail below. The release film of the present invention preferably has a release layer on at least one side of a polyester film as a substrate film. The aforementioned polyester film is preferably a biaxially oriented polyester film.

In the present invention, the release layer is formed by hardening a composition containing: a resin having a long-chain alkyl group and at least one crosslinking agent selected from an oxazoline crosslinking agent or a carbodiimide crosslinking agent. If it is the release layer of the present invention, the hardness of the release layer becomes moderately high, and the surface free energy of the release layer is within a predetermined range, so that a good peeling force can be obtained.

(Polyester film) The polyester constituting the polyester film used as the substrate in the present invention is not particularly limited, and is a polyester generally used as a substrate for release films, preferably a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component, and more preferably polyethylene terephthalate, polyethylene 2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, or a copolymer having the components of these resins as the main components. Polyethylene terephthalate is particularly preferred. Polyethylene terephthalate may also be copolymerized with a small amount of other dicarboxylic acid components and glycol components, preferably with 90 mol% or more of the repeating units of ethylene terephthalate, but in terms of cost, it is preferably made of only terephthalic acid and ethylene glycol. In addition, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, crystallization agents, etc. may be added within the range that does not hinder the effect of the film of the present invention. For reasons such as high elastic modulus in both directions, the polyester film is preferably a biaxially oriented polyester film.

The inherent viscosity of the polyester film is preferably 0.50 dl/g to 0.70 dl/g, and more preferably 0.52 dl/g to 0.62 dl/g. When the inherent viscosity is 0.50 dl/g or more, it is preferred because many cracks will not occur during the stretching step. On the contrary, when the inherent viscosity is 0.70 dl/g or less, it is preferred because the cutting property is good when cutting into a predetermined product width and no dimensional defects occur. In addition, the raw material particles are preferably fully vacuum dried.

As a method for producing a polyester film in the present invention, for example, the aforementioned polyester is melted and extruded into a film by an extruder, and cooled by a rotating cooling drum to obtain an unstretched film, and the unstretched film is stretched uniaxially or biaxially to obtain a polyester film. The biaxially stretched film can be obtained by stretching a uniaxially stretched film in the longitudinal or transverse direction in the transverse direction or in the longitudinal direction stepwise in the biaxial direction, or by stretching an unstretched film in the longitudinal and transverse directions in a synchronous biaxial direction. In the present invention, a release layer is applied in the production step of the polyester film. It is preferably used the so-called in-line coating method.

In the present invention, the stretching temperature of the polyester film during stretching is preferably set to be above the secondary transition point (Tg) of the polyester. It is preferably stretched 1 to 8 times, especially 2 to 6 times in each of the longitudinal and transverse directions.

The polyester film preferably has a thickness of 12 μm to 50 μm, more preferably 15 μm to 38 μm, and even more preferably 19 μm to 33 μm. If the thickness of the film is 12 μm or more, it is preferred because there is no risk of deformation due to heat during the processing step of the release layer and the sheet forming step during film production. On the other hand, if the thickness of the film is 50 μm or less, the amount of film discarded after use will not increase significantly, thereby reducing the environmental load, which is preferred in this regard.

The polyester film substrate may be a single layer or a multi-layer structure of two or more layers. For example, the polyester film substrate preferably has a surface layer A substantially free of inorganic particles on at least one side. In the case of a laminated polyester film composed of a multi-layer structure of two or more layers, it is preferred that the surface layer B that may contain particles is provided on the opposite side of the surface layer A substantially free of inorganic particles. As a laminated structure, if the layer on one side of the release layer (laminated side) is set as surface layer A, the layer on the opposite side of the release layer is set as surface layer B, and the core layer other than these is set as layer C, then the layer structure in the thickness direction can be listed as a laminated structure such as release layer/A/B, or release layer/A/C/B. Of course, layer C can also be a multi-layer structure. In addition, the surface layer B may not contain particles. In this case, in order to provide the film with slippery properties for winding it into a roll shape, it is preferred to set a coating layer containing particles and an adhesive on the surface layer B.

In the polyester film substrate of the present invention, the average surface roughness (Sa) of the regional surface of the surface layer A is preferably less than 10 nm, and more preferably less than 7 nm. If Sa is less than 10 nm, it is less likely to cause pinholes when the ultra-thin layer is formed, so it is better. If Sa is less than 7 nm, it is more difficult to cause pinholes when the ultra-thin layer is formed, so it is better. The smaller the average surface roughness (Sa) of the regional surface of the surface layer A, the better. For example, the average surface roughness (Sa) of the regional surface of the surface layer A is greater than 0.1 nm. In one embodiment, the average surface roughness (Sa) of the regional surface of the surface layer A is greater than 0.1 nm and less than 10 nm, for example, greater than 0.1 nm and less than 7 nm, can be greater than 0.1 nm and less than 5 nm, and can also be greater than 0.5 nm and less than 3 nm. Here, when the anchor coating layer described later is provided on the surface layer A, it is preferred that the coating layer does not substantially contain inorganic particles, and it is preferred that the average surface roughness (Sa) of the area after the coating layer is laminated is within the aforementioned range. In the present invention, "substantially containing no inorganic particles" means that when the inorganic elements are quantified by silicon light X-ray analysis, the content is below 50 ppm, preferably below 10 ppm, and most preferably below the detection limit. The reason is that even if inorganic particles are not actively added to the membrane, sometimes contamination components from foreign matter or dirt attached to the production line or equipment in the manufacturing step of the raw resin or membrane will be peeled off and mixed into the membrane.

In the polyester film substrate of the present invention, from the viewpoint of the slipperiness of the film and the ease of air escape, the surface layer B on the opposite side of the surface on which the release layer is applied preferably contains particles, and it is particularly preferred to use silica particles and/or calcium carbonate particles. The content of the particles contained is preferably 5000ppm to 15000ppm in total in the surface layer B. When the total content of silica particles and/or calcium carbonate particles is 5000ppm or more, when the film is wound into a roll, air can escape uniformly, and the winding posture is good and the flatness is good, thereby being suitable for manufacturing ultra-thin sheets. In addition, when the total content of silicon dioxide particles and/or calcium carbonate particles is below 15000 ppm, the lubricant is unlikely to aggregate and coarse protrusions cannot be formed, so the quality is stable when manufacturing ultra-thin sheets, which is better.

In the polyester film substrate of the present invention, from the viewpoint of the slipperiness of the film or the ease of air escape, the surface layer B on the opposite side of the surface on which the release layer is applied preferably contains particles, and it is particularly preferred to use silicon dioxide particles and/or calcium carbonate particles. At this time, the regional surface average roughness (Sa) of the film of the surface layer B is preferably in the range of 1nm to 40nm. More preferably, it is in the range of 5nm to 35nm. When Sa is 1nm or more, when the film is wound into a roll shape, air can escape evenly, the winding posture is good, and the flatness is good, thereby being suitable for manufacturing ultra-thin sheets. In addition, when Sa is below 40nm, the lubricant is not easily aggregated and large protrusions cannot be formed, so the quality is stable when manufacturing ultra-thin sheets, which is better.

As the particles contained in the surface layer B, in addition to silicon dioxide and/or calcium carbonate, inert inorganic particles and/or heat-resistant organic particles can also be used. From the perspective of transparency and cost, it is more preferable to use silicon dioxide particles and/or calcium carbonate particles. As other inorganic particles that can be used, aluminum oxide-silicon dioxide composite oxide particles, hydroxyapatite particles, etc. can be listed. In addition, as heat-resistant organic particles, cross-linked polyacrylic acid particles, cross-linked polystyrene particles, benzoguanamine particles, etc. can be listed. In addition, when silicon dioxide particles are used, porous colloids are preferred. When calcium carbonate particles are used, from the perspective of preventing the lubricant from falling off, light calcium carbonate surface-treated with a polyacrylic acid polymer compound is preferred.

The average particle size of the particles added to the surface layer B is preferably 0.1 μm or more and 2.0 μm or less, and more 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 preferred. If the average particle size is 2.0 μm or less, there is no risk of pinholes being generated in the film due to coarse particles on the surface of the release layer, which is preferred.

The surface layer B may contain two or more particles of different materials. In addition, the surface layer B may contain particles of the same kind but with different average particle sizes.

When the surface layer B does not contain particles, it is preferred to use a coating layer containing particles to make the surface layer B have lubricity. The coating layer is not particularly limited, and is preferably provided by in-line coating applied during the film formation of the polyester film. When the surface layer B does not contain particles and a coating layer containing particles is provided on the surface layer B, the surface of the coating layer preferably has an average surface roughness (Sa) of 1 nm to 40 nm for the same reason as the average surface roughness (Sa) of the surface layer B described above. More preferably, it is in the range of 5 nm to 35 nm.

In the surface layer A which is provided on one side of the release layer, it is preferred not to use recycled materials or the like in order to prevent the mixing of particles of lubricant or the like from the viewpoint of reducing pinholes.

The thickness ratio of the layer disposed on one side of the release layer, i.e., the surface layer A, is preferably 20% or more and 50% or less of the thickness of all layers of the substrate film. If it is 20% or more, the film is not easily affected by particles contained in the surface layer B, etc., and it is easy to make the regional surface average roughness Sa meet the above range, so it is preferred. If it is 50% or less of the thickness of all layers of the substrate film, the ratio of recycled raw materials used in the surface layer B can be increased, and the environmental load becomes smaller, so it is preferred.

In addition, from the viewpoint of economy, in the layer other than the surface layer A (the surface layer B or the intermediate layer C), 50% to 90% by mass of film scraps and/or recycled materials of PET bottles can be used. In this case, the type and amount of the lubricant contained in the surface layer B, the particle size and the average surface roughness (Sa) of the area preferably meet the above ranges.

In order to improve the adhesion of the coated release layer or prevent static electricity, a coating layer may be provided on the surface of the surface layer A and/or the surface layer B before stretching or after uniaxial stretching in the film forming step, and a corona treatment may be performed.

(Release layer) The release film of the present invention preferably has a release layer on one surface of the polyester substrate film as described above. The release layer is a layer formed by curing a composition containing: an acrylic resin having a long-chain alkyl group, and at least one crosslinking agent selected from an oxazoline crosslinking agent and a carbodiimide crosslinking agent. The release film of the present invention having such a release layer can be produced while suppressing the manufacturing cost. Furthermore, the release film of the present invention can have all the characteristics of good wettability to the sheet slurry and the resin solution, and appropriate sheet peeling force, even when the sheet is further thinned. For example, it is preferred that the release layer contains at least a binder resin, a crosslinking agent, and an additive. In addition, the release layer is a layer formed by coating the composition containing the resin and the crosslinking agent of the present invention, and is sometimes also referred to as a release coating layer.

(Binder resin in release layer)

The adhesive resin constituting the release layer in the present invention preferably includes an acrylic resin. The acrylic resin is preferably an acrylic resin having at least one selected from the group consisting of a hydroxyl group, a carboxyl group, and a long-chain alkyl group in the molecule. In one embodiment, the acrylic resin is an acrylic resin having a long-chain alkyl group. In addition, in this specification, these acrylic resins are sometimes simply described as acrylic resins. The constituent unit having a hydroxyl group is further preferably included in 5 mol% to 90 mol% of the total constituent unit 100 mol%. If the constituent unit having a hydroxyl group is 5 mol% or more, the water solubility of the acrylic resin can be appropriately maintained, so it is preferred. On the other hand, if it is less than 90 mol%, the particles contained in the release layer and the hydroxyl group of the acrylic resin will not interact extremely and the particles will be evenly dispersed, which is better. In one embodiment, the constituent units having hydroxyl groups account for 5 mol% to 50 mol% of the total constituent units (100 mol%), for example, 5 mol% to 45 mol%.

In order to introduce a hydroxyl group into the acrylic resin, monomers having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and ring-opening adducts of γ-butyrolactone or ε-caprolactone to 2-hydroxyethyl (meth)acrylate can be used as copolymerization components. Among them, 2-hydroxyethyl (meth)acrylate is preferred in terms of not hindering water solubility. In addition, these can also be used in combination of two or more.

The hydroxyl value of the acrylic resin is preferably 2 mgKOH/g or more, more preferably 5 mgKOH/g or more, and further preferably 10 mgKOH/g or more. When the hydroxyl value of the acrylic resin is 2 mgKOH/g or more, the water solubility of the acrylic resin is improved, which is preferred.

The hydroxyl value of the acrylic resin is preferably 250 mgKOH/g or less, more preferably 230 mgKOH/g or less, and further preferably 200 mgKOH/g or less. If the hydroxyl value of the acrylic resin is 250 mgKOH/g or less, the hydroxyl groups of the acrylic resin and the particles contained in the release layer will not interact extremely, so that the particles are uniformly dispersed, which is preferred.

The acrylic resin used in the present invention may also include a resin having a hydroxyl group. In addition, it may also include a resin having a carboxyl group. In another aspect, the acrylic resin may also include a resin having a hydroxyl group and a resin having a carboxyl group. By having a carboxyl group, a cross-linked structure with a crosslinking agent can be formed, and water solubility can be easily imparted. As examples, monomers containing carboxyl groups such as (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid, and monomers containing anhydride groups such as maleic anhydride and itaconic anhydride can be listed.

The monomer having a carboxyl group is preferably 4 mol% or more, more preferably 10 mol% or more, in 100 mol% of all constituent units of the acrylic resin. If it is 4 mol% or more, it is easy to form a cross-linked structure in the release layer and impart water solubility, so it is preferred. The monomer having a carboxyl group is preferably 65 mol% or less, more preferably 50 mol% or less. If it is 65 mol% or less, the Tg of the obtained coating will not be too high relative to the preferred range described later, and the film-forming property and the elongation suitability in the in-line coating are good, so it is preferred.

In order to show good water solubility, it is preferred to neutralize the carboxyl group introduced into the acrylic resin by copolymerization of acrylic acid or methacrylic acid. As alkaline neutralizers, there are amine compounds such as ammonia, trimethylamine, triethylamine, dimethylaminoethanol, and inorganic alkaline substances such as potassium hydroxide and sodium hydroxide. Among them, considering the ease of volatility of the neutralizer and the ease of forming a cross-linked structure, it is preferred to use an amine compound as a neutralizer. Among them, ammonia is the best in terms of not causing the aggregation of particles when the release layer contains particles. In addition, as a neutralization rate, it is preferably 30 mol% to 95 mol%, and more preferably 40 mol% to 90 mol%. When the neutralization rate is 30 mol% or more, the acrylic resin has sufficient water solubility, and the acrylic resin is easily dissolved when preparing the coating liquid, and there is no risk of the coating surface turning white after drying, so it is preferred. On the other hand, if the neutralization rate is 95 mol% or less, the water solubility is not too high, and alcohol and the like are easily mixed when preparing the coating liquid.

The acid value of the acrylic resin is preferably 40 mgKOH/g or more, more preferably 50 mgKOH/g or more, and further preferably 60 mgKOH/g or more. If the acid value of the acrylic resin is 40 mgKOH/g or more, for example, the crosslinking points with the oxazoline crosslinking agent or the carbodiimide crosslinking agent increase, thereby obtaining a stronger coating film with a higher crosslinking density, which is preferred.

The acid value of the acrylic resin is preferably, for example, 400 mgKOH/g or less, more preferably 350 mgKOH/g or less, and further preferably 300 mgKOH/g or less. In one embodiment, the acid value of the acrylic resin is 200 mgKOH/g or less, for example, 150 mgKOH/g or less. If the acid value of the acrylic resin is 400 mgKOH/g or less, the crosslinking density with the oxazoline crosslinker or the carbodiimide crosslinker will not become too high, and cracks will not be generated during extension, so it is better. In addition, it is believed that this tendency is also obtained in the embodiment in which the oxazoline crosslinker and the carbodiimide crosslinker are used together. In addition, if the acid value of the acrylic resin is 400 mgKOH/g or less, the carboxyl groups of the acrylic resin and the particles contained in the release layer will not interact extremely, and the particles will be evenly dispersed, which is better. If the dispersibility of the particles is good, no coarse protrusions will be generated on the release coating surface, and no pinholes will be generated in the sheet, which is better. In one embodiment, the acid value of the acrylic resin having a long-chain alkyl group is 40 mgKOH/g or more and 400 mgKOH/g or less, for example, 40 mgKOH/g or more and 300 mgKOH/g or less.

The acrylic resin used in the present invention is preferably a resin having at least one selected from the group consisting of a hydroxyl group, a carboxyl group and a long-chain alkyl group. Having a long-chain alkyl group makes it possible to make the peeling force lighter, so it is preferred. As an acrylic resin having a long-chain alkyl group, it is preferred to have an alkyl group with a carbon number of 8 to 25 on the side chain of the acrylic resin, and it is more preferred to have an alkyl group with a carbon number of 12 to 22 on the side chain of the acrylic resin, and it is further preferred to have an alkyl group with a carbon number of 16 to 20 on the side chain of the acrylic resin. In addition, the following copolymers can also be preferably used: a polymer with (meth)acrylate as the main repeating unit, and a long-chain alkyl group with 8 to 20 carbon atoms in the ester-exchanged part. As examples, lauryl (meth)acrylate, stearyl (meth)acrylate, etc. can be listed. Among them, stearyl methacrylate can be preferably used in terms of ease of acquisition and cost, and obtaining good peeling power. For example, the acrylic resin used in the present invention is a resin formed by using at least one selected from the group consisting of methyl methacrylate (MMA; methyl methacrylate), hydroxyethyl methacrylate (HEMA; hydroxyethyl methacrylate) and methacrylic acid (MAA; methacrylic acid) in addition to stearyl methacrylate (SMA; stearyl methacrylate). By including such an acrylic resin, in the release film of the present invention, the crosslinking density of the acrylic resin and the oxazoline crosslinker or the carbodiimide crosslinker in the release layer will not become too high, so that cracking during stretching can be suppressed. Furthermore, by including such an acrylic resin, the manufacturing cost can be suppressed. Furthermore, the release film of the present invention can have all the characteristics of good wettability of the sheet slurry and the resin solution, and appropriate sheet peeling force, even when the sheet is further thinned.

The glass transition temperature (Tg) of the acrylic resin is preferably 50° C. or higher, more preferably 55° C. or higher, and further preferably 60° C. or higher. When the glass transition temperature of the acrylic resin is 50° C. or higher, the hardness of the release layer becomes moderately high, which is preferred.

The glass transition temperature (Tg) of the acrylic resin is preferably 110°C or lower, more preferably 105°C or lower, and further preferably 100°C or lower. If the glass transition temperature of the acrylic resin is 110°C or lower, the coating film is preferably stretched uniformly without cracks in the stretching step after the release layer is applied.

As the Tg adjusting monomer copolymerized to make Tg fall within the above range, a (meth)acrylic monomer or a non-acrylic vinyl monomer can be used. Specific examples of the (meth)acrylic monomer include: alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; nitrogen-containing acrylic monomers such as (meth)acrylamide, diacetone acrylamide, N-hydroxymethylacrylamide, and (meth)acrylonitrile; and vinyl methacrylate, and one or more of these can be used.

In addition, as non-acrylic vinyl monomers, there can be listed: styrene monomers such as styrene, α-methylstyrene, vinyltoluene (a mixture of m-methylstyrene and p-methylstyrene), and chlorostyrene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl pivalate, vinyl caprylate, vinyl monochloroacetate, divinyl adipate, vinyl butyrate, vinyl hexadienoate, vinyl benzoate, and vinyl cinnamate; halogenated vinyl monomers such as vinyl chloride and vinylidene chloride; one or more kinds may be used.

The monomer having a long chain alkyl group preferably accounts for 60 mol% or less, and more preferably 50 mol% or less, of the total constituent units of the acrylic resin (100 mol%). If it is 60 mol% or less, the Tg of the obtained coating will not be too low relative to the preferred range, and the hardness of the coating can be maintained high, which is preferred. The monomer having a long chain alkyl group preferably accounts for 5 mol% or more, and more preferably 15 mol% or more, of the total constituent units of the acrylic resin (100 mol%). If it is 5 mol% or more, the surface free energy is reduced, thereby reducing the peeling force, which is preferred.

The monomers for adjusting Tg are preferably the remainder after determining the appropriate amounts of the monomers containing hydroxyl groups, the monomers containing carboxyl groups and the monomers containing long-chain alkyl groups. The Tg of the copolymer is determined using the following Fox equation.

[Number 1] _Wn : Mass fraction of each monomer (mass %) _Tgn : Tg (K) of the homopolymer of each monomer

The acrylic resin used in the present invention can be obtained by known free radical polymerization. Any of emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, etc. can be adopted. In terms of operability, solution polymerization is preferred. As water-soluble organic solvents that can be used for solution polymerization, there can be listed: ethylene glycol n-butyl ether, isopropyl alcohol, ethanol, N-methylpyrrolidone, tetrahydrofuran, 1,4-dioxane, 1,3-dioxacyclopentane, methyl solvent, ethyl solvent, ethyl carbitol, butyl carbitol, propylene glycol monopropyl ether, propylene glycol monobutyl ether, etc. These can also be mixed with water and used.

The polymerization initiator may be any known compound that generates free radicals, and preferably is a water-soluble azo polymerization initiator such as 2,2-azobis-2-methyl-N-2-hydroxyethylpropionamide. The polymerization temperature and time may be appropriately selected.

The mass average molecular weight (Mw) of the acrylic resin is preferably about 10,000 to 200,000. A more preferred range is 20,000 to 150,000. When the Mw is 10,000 or more, there is no risk of thermal decomposition in the tenter, so it is preferred. If the Mw is 200,000 or less, the viscosity of the coating liquid will not increase significantly, and the coating property is good, so it is preferred.

As the binder of the release layer in the present invention, other binder resins may be used in addition to acrylic resins. Examples of other binder resins include polyester resins, urethane resins, polyethylene resins (polyvinyl alcohol, etc.), polyalkylene glycols, polyalkylene imides, methyl cellulose, hydroxy cellulose, starches, etc.

The content of the acrylic resin in the release layer is preferably 20% by mass or more and 95% by mass or less in the total solid content. More preferably, it is 30% by mass or more and 90% by mass or less. If it is 20% by mass or more, the amount of carboxyl groups as the crosslinking component will not be too small and the crosslinking density will not be low, which is preferred. If it is 95% by mass or less, the amount of the crosslinking agent as the object of crosslinking will not be too small and the crosslinking density will not be low, which is preferred.

(Crosslinking agent) In the present invention, in order to form a crosslinking structure in the release layer, the release layer preferably contains at least one crosslinking agent selected from oxazoline crosslinking agents or carbodiimide crosslinking agents. By containing oxazoline crosslinking agents or carbodiimide crosslinking agents, the adhesion with the PET substrate is improved, and the crosslinking with the carboxyl group of the acrylic resin is promoted, thereby improving the coating strength of the release layer, and as a result, the peeling force can be reduced. In addition, other crosslinking agents can also be used in combination. As specific crosslinking agents that can be used in combination, urea, epoxy, melamine, isocyanate, silanol, etc. can be listed. In addition, in order to promote the cross-linking reaction, a catalyst may be used as needed.

Examples of the crosslinking agent having an oxazoline group include polymers having an oxazoline group obtained by copolymerizing a polymerizable unsaturated monomer having an oxazoline group with other polymerizable unsaturated monomers as needed by a conventionally known method (e.g., solution polymerization, emulsion polymerization, etc.).

Examples of polymerizable unsaturated monomers having an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. These may be used alone or in combination of two or more.

As other polymerizable unsaturated monomers, for example, there can be listed: alkyl or cycloalkyl esters of (meth)acrylic acid having 1 to 24 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, etc.; 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate; Hydroxyl alkyl esters of (meth) acrylic acid with 2 to 8 carbon atoms; vinyl aromatic compounds such as styrene and vinyl toluene; (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate and amine adducts; polyethylene glycol (meth) acrylate; N-vinyl pyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate, (meth) acrylonitrile, etc. These can be used alone or in combination of two or more.

From the viewpoint of making the obtained crosslinking agent having an oxazoline group a water-soluble crosslinking agent and improving the compatibility with other resins, wettability, crosslinking reaction efficiency, etc., other polymerizable unsaturated monomers are preferably hydrophilic monomers. As hydrophilic monomers, there can be listed: monomers having a polyethylene glycol chain such as 2-hydroxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, monoester compounds of (meth)acrylic acid and polyethylene glycol, 2-aminoethyl (meth)acrylate and its salts, (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, N-(2-hydroxyethyl) (meth)acrylamide, (meth)acrylonitrile, sodium styrene sulfonate, etc. Among these, monomers having a polyethylene glycol chain such as methoxypolyethylene glycol (meth)acrylate and monoester compounds of (meth)acrylic acid and polyethylene glycol, which are highly soluble in water, are preferred.

The crosslinking agent having an oxazoline group preferably has an oxazoline group content of 3.0 mmol/g to 9.0 mmol/g. More preferably, it is in the range of 4.0 mmol/g to 8.0 mmol/g. If it is in the range of 3.0 mmol/g to 9.0 mmol/g, a moderate crosslinking structure can be formed, and the peeling force becomes lighter, so it is preferred. In addition, when the content of the oxazoline crosslinking agent is within the above range, a moderate crosslinking structure with the acrylic resin can be formed, and no cracks are generated during extension, so it is preferred.

As the carbodiimide crosslinking agent, monocarbodiimide compounds and polycarbodiimide compounds can be listed. As the monocarbodiimide compound, for example, dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, tert-butylisopropylcarbodiimide, diphenylcarbodiimide, di-tert-butylcarbodiimide, di-β-naphthylcarbodiimide, etc. can be listed. As the polycarbodiimide compound, a polycarbodiimide compound produced by a previously known method can be used. For example, it can be produced in the following manner: an isocyanate-terminated polycarbodiimide can be synthesized by a condensation reaction accompanied by the removal of carbon dioxide from a diisocyanate.

Examples of the diisocyanate used as a raw material for synthesizing the polycarbodiimide compound include isomers of tolyl diisocyanate, aromatic diisocyanates such as 4,4-diphenylmethane diisocyanate, aromatic aliphatic diisocyanates such as xylylene diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, and 1,3-bis(isocyanatemethyl)cyclohexane, and aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate. In view of the yellowing problem, aromatic aliphatic diisocyanates, alicyclic diisocyanates, and aliphatic diisocyanates are preferred.

In addition, the above-mentioned diisocyanate can also be used by controlling the molecule to an appropriate degree of polymerization using a compound that reacts with a terminal isocyanate, such as a monoisocyanate. Examples of the monoisocyanate used to block the terminal of polycarbodiimide and control the degree of polymerization of polycarbodiimide include phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, naphthyl isocyanate, etc. In addition, a compound having an OH group, a _-NH2 group, a COOH group, or a _SO3H group can also be used as a terminal blocking agent.

The condensation reaction accompanied by the decarbonation of diisocyanate is carried out in the presence of a carbodiimidization catalyst. Examples of the catalyst include 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, 3-methyl-1-phenyl-2-phospholene-1-oxide, and phospholene oxides such as 3-phospholene isomers thereof. In terms of reactivity, 3-methyl-1-phenyl-2-phospholene-1-oxide is preferred. In addition, the amount of the above catalyst used can be set as the catalyst amount.

The mono- or polycarbodiimide compounds mentioned above are preferably able to maintain a uniform dispersion state when formulated into an aqueous coating. For this purpose, it is preferably used in the form of an emulsion by emulsifying with a suitable emulsifier, or a hydrophilic chain segment is added to the molecular structure of the polycarbodiimide compound and formulated into the coating in the form of a self-emulsifiable product or a self-dissolving product.

The carbodiimide crosslinking agent used in the present invention can be water-dispersible or water-soluble. Water-soluble is preferred in terms of good compatibility with other water-soluble resins and improved crosslinking reaction efficiency of the release layer. In order to make the carbodiimide compound water-soluble, it can be produced in the following manner: after synthesizing an isocyanate-terminated polycarbodiimide by a condensation reaction accompanied by the removal of carbon dioxide from an isocyanate, a hydrophilic site having a functional group reactive with an isocyanate group is further added.

Examples of the hydrophilic site include: (1) quaternary ammonium salts of dialkylamino alcohols or quaternary ammonium salts of dialkylaminoalkylamines, (2) alkyl sulfonates having at least one reactive hydroxyl group, (3) poly(ethylene oxide) terminally blocked by alkoxy groups, and mixtures of poly(ethylene oxide) and poly(propylene oxide). When the carbodiimide compound is introduced with the above hydrophilic site, it becomes (1) cationic, (2) anionic, or (3) nonionic. Of these, nonionic compounds that are compatible with other water-soluble resins are preferred.

The content of the crosslinking agent in the release layer is preferably 5% by mass or more and 80% by mass or less in the total solid content. More preferably, it is 10% by mass or more and 70% by mass or less. If it is 5% by mass or more, the crosslinking density of the resin of the coating layer will not be reduced, which is preferred. If it is 80% by mass or less, the amount of carboxyl groups in the acrylic resin to be crosslinked will not be too small, and the crosslinking density will not be reduced, which is preferred.

(Particles in release layer) In order to control the peeling force at the starting point of sheet peeling and the peeling force during constant peeling, and to impart slipperiness to the surface, the release layer may also contain lubricant particles. The particles may be inorganic particles or organic particles, and are not particularly limited. Examples include: (1) silicon dioxide, kaolin, talc, light calcium carbonate, heavy calcium carbonate, zeolite, aluminum oxide, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, zirconium oxide, titanium dioxide, satin white, aluminum silicate, diatomaceous earth, calcium silicate, aluminum hydroxide, kaolinite, calcium carbonate, magnesium carbonate, calcium phosphate, magnesium hydroxide, barium sulfate, etc. Inorganic particles; (2) Organic particles of acrylic or methacrylic acid series, vinyl chloride series, vinyl acetate series, nylon, styrene/acrylic acid series, styrene/butadiene series, polystyrene/acrylic acid series, polystyrene/isoprene series, methyl methacrylate/butyl methacrylate series, melamine series, polycarbonate series, urea series, epoxy series, urethane series, phenol series, diallyl phthalate series, polyester series, etc.

The average particle size of the particles is preferably 10 nm or more, more preferably 20 nm or more, and further preferably 30 nm or more. If the average particle size of the particles is 10 nm or more, the particles are less likely to aggregate and the lubricity can be ensured, which is preferred.

The average particle size of the particles is preferably 500 nm or less, more preferably 400 nm or less, and further preferably 300 nm or less. If the average particle size of the particles is 500 nm or less, pinholes are less likely to be generated during sheet processing, and the particles will not fall off, which is preferred.

The average particle size of the particles can be determined by the following method: observing the particles in the cross section of the processed film using a transmission electron microscope or a scanning electron microscope, observing 100 unagglomerated particles, and setting the average value of the 100 particles as the average particle size.

As long as the purpose of the present invention is met, the shape of the particles is not particularly limited, and spherical particles and amorphous non-spherical particles can be used. The particle size of amorphous particles can be calculated by the equivalent circle diameter. The equivalent circle diameter is the value obtained by dividing the observed particle area by π, calculating the square root, and then multiplying it by 2.

The ratio of the particles to the total solid content of the release layer is preferably 50% by mass or less, more preferably 30% by mass or less, and further preferably 10% by mass or less. If the ratio of the particles to the total solid content of the release layer is 50% by mass or less, pinholes are less likely to be generated during sheet processing, and particles will not significantly fall off the release layer, which is preferred. Alternatively, it may be 0% by mass.

As a method for measuring the content of particles contained in a release layer, for example, when the release layer contains a resin containing an organic component and inorganic particles, the following method can be used. First, the release layer provided on the processing film is extracted from the processing film using a solvent or the like and dried to remove the release layer. Next, heat is applied to the obtained release layer so that the organic components contained in the release layer are burned and distilled off by the heat, thereby obtaining pure inorganic components. The weight of the obtained inorganic components and the release layer before the burning and distilling is measured, thereby determining the mass % of the particles contained in the release layer. At this time, by using a commercially available differential thermal-thermogravimetric simultaneous measuring device, the measurement can be performed with high precision. Furthermore, when there are a plurality of types of particles, the ratio of the above-mentioned particles to the total solid content of the release layer refers to the ratio of the total amount of the plurality of types of particles.

(Additives) In the present invention, the use of an acrylic resin having a long-chain alkyl group can exhibit release properties, but additives can also be added to further improve the release properties. As additives used in the release layer, silicone additives and non-silicone additives such as olefinic, long-chain alkyl, and fluorine additives can be used, but from the perspective of releasability, silicone additives are preferably used. The silicone additives used in the present invention not only improve the release properties, but also have the effect of improving the leveling properties during coating and defoaming the coating liquid.

(Polysilicone additive in release layer) In the present invention, the polysilicone additive used in the release layer is a compound having a polysilicone structure in the molecule. As long as it is within the scope of the effect of the present invention, there is no particular limitation, and polyorganosiloxane and the like can be preferably used. Among polyorganosiloxanes, polydimethylsiloxane (abbreviated as: PDMS) can be preferably used, and it is preferred that a part of the polydimethylsiloxane has a functional group. By having a functional group, polydimethylsiloxane and the adhesive resin become easy to produce intermolecular interactions such as hydrogen bonds and are not easy to transfer to the sheet, so it is better.

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

As the reactive functional group introduced into the polydimethylsiloxane, an amino group, an epoxy group, a hydroxyl group, a hydroxyl group, a carboxyl group, a methacryl group, an acryl group, etc. can be used. As the non-reactive functional group, a polyether group, an aralkyl group, a fluoroalkyl group, a long-chain alkyl group, an ester group, an amide group, a phenyl group, etc. can be used. Although not particularly limited by theory, among the above, polydimethylsiloxane having an epoxy group, a carboxyl group, a polyether group, a methacryl group, an acryl group, and an ester group is preferred.

As the functional group introduced into the polydimethylsiloxane, it is preferred to use a polyether group or an ester group which does not react with the binder resin, is easily aligned on the surface of the release layer, and has little transferability to the green body.

The polysilicone additive used in the present invention preferably has a molecular weight of 40,000 or less. More preferably, it is 30,000 or less. If the molecular weight is 40,000 or less, the polysilicone additive is easily segregated to the surface of the release layer and has good releasability, which is preferred.

(Long-chain alkyl additives in release layer) As long-chain alkyl additives, resins modified with long-chain alkyl groups can be used, preferably compounds having an alkyl group with a carbon number of about 8 to 20 in the side chain of polyvinyl alcohol or acrylic resin. In addition, the following copolymers can be preferably used: polymers with (meth)acrylate as the main repeating unit, and containing a long-chain alkyl group with a carbon number of 8 to 20 in the ester-exchanged part. By using a long-chain alkyl additive different from the acrylic resin having a long-chain alkyl group as the main agent, the release property is sometimes improved. As an example of the commercially available long-chain alkyl additive mentioned above, PEELOIL (registered trademark) 406 (the above is Lion Specialty Chemicals Co., Ltd.) can be cited.

(Other additives in release layer) In order to impart other functionality to the release layer, various additives other than silicone additives may be contained within the range that does not damage the coating appearance. Examples of the aforementioned additives include: fluorescent dyes, fluorescent whitening agents, plasticizers, ultraviolet absorbers, pigment dispersants, antifoaming agents, defoaming agents, preservatives, etc.

The release layer may contain additives other than silicone additives for the purpose of improving the leveling property during coating and defoaming the coating liquid. The additives may be any of cationic, anionic, and nonionic, preferably acetylene glycol or fluorine additives. These additives are preferably contained in the release layer within a range that does not cause abnormalities in the coating appearance due to excessive addition.

The additive used in the present invention is preferably 20% by mass or less. If it is 20% by mass or less, there will be no excessive migration of the additive to the sheet, which is preferred. In addition, the additive may also be 0% by mass.

As a coating method, the coating can be applied to the polyester substrate film at the same time as the film is formed, which is called an in-line coating method, or the polyester substrate film is formed and then coated by a coating machine, which is called an off-line coating method. The in-line coating method is more efficient and therefore more preferable.

As a coating method, any known method can be used to coat the coating liquid on the polyethylene terephthalate (hereinafter, sometimes referred to as PET) film. For example, reverse roll coating, gravure coating, touch coating, die coating, roll brush coating, spray coating, air knife coating, wire rod coating, pipe doctor method, impregnation coating, curtain coating, etc. These methods can be used alone or in combination for coating.

In the present invention, as a method for providing a release layer on a polyester film, the following method can be cited: a coating liquid containing a solvent, particles, and a resin is applied to the polyester film and dried. As the solvent, organic solvents such as toluene, water, or a mixture of water and a water-soluble organic solvent can be cited. In terms of environmental issues, water alone or a so-called aqueous solvent in which a water-soluble organic solvent is mixed is preferred.

The solid content concentration of the release coating liquid also depends on the type of the binder resin or the type of the solvent, and is preferably 0.5 mass % or more, more preferably 1 mass % or more. The solid content concentration of the coating liquid is preferably 35 mass % or less, more preferably 20 mass % or less. In addition, the release coating liquid is sometimes described as a release coating liquid.

The drying temperature after coating also depends on the type of adhesive resin, the type of solvent, the presence or absence of a crosslinking agent, the solid content concentration, etc., but is preferably above 70°C and preferably below 250°C.

In the case of in-line coating, it can be applied to an unstretched film before longitudinal stretching, or it can be applied to a uniaxially stretched film after longitudinal stretching and before transverse stretching. In the case of coating before longitudinal stretching, it is preferred to set a drying step before roll stretching. In the case of coating on a uniaxially stretched film before transverse stretching, the drying step can be combined with the film heating step in the tenter, so it is not necessary to set a drying step separately. In addition, the same is true for the case of synchronous biaxial stretching.

The film thickness of the release layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, further preferably 0.02 μm or more, and particularly preferably 0.03 μm or more. If the film thickness of the release layer is 0.001 μm or more, the film forming property of the coating film can be maintained and a uniform coating film can be obtained, which is preferred.

The film thickness of the release layer is preferably 2 μm or less, more preferably 1 μm or less, further preferably 0.8 μm or less, and particularly preferably 0.5 μm or less. If the film thickness of the coating layer is 2 μm or less, there is no risk of blocking, which is preferred.

When the surface roughness of both sides of the polyester film substrate is different, the release layer may be coated on either side. However, in terms of obtaining a smoother surface roughness of the release side, it is preferred to coat the release layer on the smooth area of the substrate.

Regarding the outer surface of the film formed with the release layer (the release layer surface of the entire coated film that is not in contact with the polyester film), in order to prevent defects from occurring on the sheet to be coated and formed on the outer surface, it is ideally flat, and preferably the average regional surface roughness (Sa) is 5 nm or less and the maximum protrusion height (P) is 50 nm or less. Furthermore, it is more preferred that the average regional surface roughness is 5 nm or less and the maximum protrusion height is 40 nm or less. If the regional surface roughness is 5 nm or less and the maximum protrusion height is 50 nm or less, defects such as pinholes will not occur when the sheet is formed, and the yield is good, so it is preferred. The smaller the regional surface average roughness (Sa), the better, and it can be 0.1 nm or more, or 0.3 nm or more. The maximum protrusion height (P) can also be said to be the smaller the better, and can be greater than 1nm, or greater than 3nm. In one embodiment, the average surface roughness of the region is less than 4.4nm and the maximum protrusion height is less than 40nm, for example, the average surface roughness of the region is less than 4nm and the maximum protrusion height is less than 40nm.

The surface free energy of the release layer is preferably 45 mJ/m ² or less, more preferably 35 mJ/m ² or less. When the surface free energy of the release layer is 45 mJ/m ² or less, the peeling force of the sheet becomes lighter, which is preferred. The surface free energy of the release layer is preferably 20 mJ/m ² or more, more preferably 25 mJ/m ² or more. When the surface free energy of the release layer is 20 mJ/m ² or more, the peeling force of the sheet does not become too light, and splashing of the slurry or resin solution is less likely to occur, which is preferred.

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

The release film of the present invention can be particularly preferably used to manufacture such a laminated ceramic capacitor. For example, it can be manufactured in the following manner. First, the release film of the present invention is used as a carrier film to coat and dry the ceramic slurry used to constitute the ceramic body. On the coated and dried ceramic green body, a conductive layer used to constitute the first internal electrode or the second internal electrode is printed. The ceramic green body, the ceramic green body printed with the conductive layer used to constitute the first internal electrode, and the ceramic green body printed with the conductive layer used to constitute the second internal electrode are appropriately laminated and pressurized to obtain a mother laminated body. The mother laminated body is divided into multiple pieces to produce raw ceramic bodies. The raw ceramic body is sintered to obtain a ceramic body. Then, a first external electrode and a second external electrode are formed to complete a multilayer ceramic capacitor. [Example]

Next, the present invention is described in detail using embodiments and comparative examples, but the present invention is of course not limited to the following embodiments. In addition, the evaluation method used in the present invention is as follows.

(NMR (Nuclear Magnetic Resonance) measurement) The ratio of the copolymer components introduced into the acrylic resin (e.g., acryl polyol) is confirmed using nuclear magnetic resonance spectroscopy ( ^1H -NMR, ^13C -NMR: Varian Unity 400, manufactured by Agilent). The measurement is performed by removing the solvent from the synthesized acrylic resin (polyol acrylate) using a vacuum dryer and dissolving the dried product in deuterated chloroform. Based on the obtained NMR spectrum, the peak of the chemical shift δ (ppm) attributed to each base site is identified. The integrated intensity of each peak obtained was determined, and the composition ratio (mol %) of the copolymer component introduced into the acrylic resin (polyol acrylate) was confirmed based on the number of hydrogen atoms at each base site and the integrated intensity.

(Confirmation of Tg) The Tg of each acrylic resin (polyol acrylate) was determined based on the composition ratio of the copolymer components determined by the above-mentioned NMR measurement and the aforementioned Fox equation.

(Stretchability) In order to evaluate the stretchability of the acrylic resin (polyol acrylate) itself, the synthesized acrylic resin (polyol acrylate) (1) to acrylic resin (polyol acrylate) (5) were placed in a mixed solvent (25°C) of 30% by mass of isopropyl alcohol and 70% by mass of water in such a manner that the solid content concentration became 12% by mass. After preparing a solution of the acrylic resin (polyol acrylate) monomer, the solution was applied to the surface of a polyester film that had been stretched only in the longitudinal direction using a Meyer bar #5. Then, the film sample with the coating layer (thickness 6.5μm) was placed in a hot air circulation oven set at a temperature of 60°C for 30 seconds, and then the film sample was taken out of the oven and pre-dried. Next, the sample is manually placed in a stretching device (manufactured by Toyobo Engineering Co., Ltd.), placed in a hot air circulation oven at 100°C, and slowly stretched. The stretching operation is performed until the length becomes 4 times the length before stretching, and the stretching device is removed from the hot air circulation oven. Then, the stretched coating is observed using an optical microscope (magnification: 200 times), and the presence or absence of cracks caused by stretching is determined based on the following criteria. ○: No cracks are seen at all. △: Slightly visible cracks (1 to 4). ×: 5 or more cracks are visible or cracks are visible on the entire surface.

(Determination of acid value) Weigh approximately 0.2 g of the sample accurately and place it in a conical flask with a branch tube (A(g)), add 10 ml of benzyl alcohol, and heat it at 230°C for 15 minutes under a nitrogen atmosphere to dissolve the resin. After cooling to room temperature, add 10 ml of benzyl alcohol, 20 ml of chloroform, and a few drops of phenolphthalein solution, and titrate with 0.02 normal concentration KOH solution (titration amount = B(ml), valency of KOH solution = p). Perform a blank measurement in the same way (titration amount = C(ml)) and calculate according to the following formula. Acid value (mgKOH/g) = (B-C) × 0.02 × 56.11 × p÷A

(Quantitative determination of oxazoline groups in resins containing oxazoline groups) The resin containing oxazoline groups was freeze-dried and analyzed by 1H-NMR using a nuclear magnetic resonance analyzer (NMR) ("Gemini-200" manufactured by Balian) to determine the absorption peak intensity derived from the oxazoline groups and the absorption peak intensity derived from other monomers. The oxazoline group amount (mmol/g) was calculated based on the peak intensities.

(Surface properties of coated and uncoated substrate films) The surface properties of coated and uncoated substrate films are measured using a non-contact surface profile measuring system (VertScan R550H-M100) under the following conditions. The average value of 5 measurements is used for the area surface roughness (Sa), and the maximum value of 5 measurements is used for the maximum protrusion height (P). (Measurement conditions) ・Measurement mode: WAVE mode ・Objective lens: 50x ・0.5x tube lens ・Measurement area 187μm×139μm (Sa, P measurement)

(Surface free energy) At 25°C and 50% RH, a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.: Fully Automatic Contact Angle Meter DM-701) was used to make droplets of water (drop volume 1.8μL), diiodomethane (drop volume 0.9μL), and ethylene glycol (drop volume 0.9μL) on the release surface of the release film, and the contact angle of the droplets was measured. The contact angle was the contact angle 10 seconds after each droplet was added to the release film. According to the Kitasaki-Hata theory, the contact angle data of water, diiodomethane, and ethylene glycol obtained by the above method are used to calculate the dispersion component γsd, polar component γsp, and hydrogen bond component γsh of the surface free energy of the release film, and the data obtained by summing up each component is set as the surface free energy γs. This calculation is performed using the calculation software in this contact angle meter software (FAMAS).

(Pinhole evaluation of ceramic slurry) The composition consisting of the following materials was stirred and mixed, and dispersed using a bead mill with 0.5 mm diameter zirconia beads for 60 minutes to obtain a ceramic slurry. Toluene 38.3 parts by mass Ethanol 38.3 parts by mass Barium titanium oxide (HPBT-1 manufactured by Fuji Titanium Co., Ltd.) 64.8 parts by mass Polyvinyl butyral (S-LEC BM-S manufactured by Sekisui Chemical Co., Ltd.) 6.5 parts by mass DOP (dioctyl phthalate) 3.3 parts by mass Then, the dried slurry was applied to the release surface of the obtained release film sample using an applicator so that it would have a particle size of 1 μm, and dried at 90°C for 1 minute to form a ceramic green body. Next, the release film is peeled off from the formed release film with the ceramic green body, and a ceramic green body is obtained. Light is irradiated from the opposite side of the ceramic slurry coating surface in the central area of the film width direction of the obtained ceramic green body within a range of 25 ^cm2 , and the occurrence of pinholes visible through the light is observed and visually judged according to the following criteria. ○: No pinholes are generated △: Almost no pinholes are generated ×: A large number of pinholes are generated

(Evaluation of the peelability of ceramic green body) In the same manner as the evaluation of the coating property of the ceramic slurry described above, the ceramic sheet was coated in a manner such that the thickness of the dried ceramic sheet was 0.8 μm, and dried at 60°C for 1 minute to form a ceramic green body on the release film. The obtained release film with the ceramic green body was destaticized using a destaticizer (manufactured by KEYENCE, SJ-F020), and then peeled using a peeling tester (manufactured by Kyowa Interface Science, VPA-3) at a peeling angle of 90 degrees, a peeling temperature of 25°C, and a peeling speed of 10 m/min. As the peeling direction, a double-sided adhesive tape (manufactured by Nitto Denko Co., Ltd., No. 535A) is attached to the SUS plate attached to the peeling tester. The release film is fixed on the double-sided adhesive tape in a form that the ceramic green body side is bonded to the double-sided tape, and the release film side is peeled off by pulling. From the measured values obtained, the average value of the peeling force at a peeling distance of 20mm to 70mm is calculated, and the average value is set as the peeling force. The measurement is carried out a total of 5 times, and the value of the average value of the peeling force is used for evaluation. The following criteria are used to judge based on the obtained peeling force value. ○: 3.5mN/mm or less △: greater than 3.5mN/mm and less than 6.0mN/mm ×: greater than 6.0mN/mm

(Evaluation of Pinholes in Resin Sheets) Three types of resin solutions for resin sheet molding were prepared by the following method. (Resin Sheet (1)) 0.5 parts by mass of cyclic olefin resin (ARTON (registered trademark) G7810/manufactured by JSR Corporation, solid content 100% by mass) was dissolved in 80 parts by mass of toluene and 20 parts by mass of tetrahydrofuran to prepare resin solution (1). The solution was applied to the release surface of the release film sample using an applicator so that the dried sheet would have a thickness of 0.5 μm, and dried at 100°C for 1 minute to mold a cyclic olefin resin sheet. Next, the release film with the cyclic olefin resin sheet formed was peeled off to obtain a cyclic olefin resin sheet (1). (Resin sheet (2)) 10 parts by mass of an ion exchange resin (20% Nafion (registered trademark) 20Dispersion Solution DE2021 CS type, manufactured by Wako Pure Chemical Industries, Ltd., solid content 20%), 10 parts by mass of water, and 20 parts by mass of isopropyl alcohol were mixed to prepare a resin solution (2). The release surface of the release film sample was applied using an applicator in such a way that the dried sheet became 0.5 μm, and dried at 100°C for 1 minute to form an ion exchange resin sheet. Next, the release film is peeled off from the release film with the formed ion exchange resin sheet, thereby obtaining an ion exchange resin sheet (2). (Resin sheet (3)) 20 parts by mass of a UV curable resin (acrylic urethane, product name: 8UX-015A, manufactured by Taisei Fine Chemicals Co., Ltd., solid content 100% by mass), 40 parts by mass of methyl ethyl ketone, 39 parts by mass of isopropyl alcohol, and 1 part by mass of a photoradical initiator (Irgacure (registered trademark) 907, manufactured by BASF) are mixed to prepare a resin solution (3). The release film sample was coated on the release surface using an applicator in such a way that the dried sheet became 1.0 μm, and after drying at 90°C for 15 seconds, it was irradiated with ultraviolet light using a high-pressure mercury lamp in such a way that it became 300 mJ/ ^cm2 , thereby forming an ultraviolet curing resin sheet. Then, the release film with the formed ultraviolet curing resin sheet was peeled off to obtain an ultraviolet curing resin sheet (3). The three types of resin sheets obtained were evaluated using the following method. Light was irradiated from the opposite side of the resin slurry coating surface in the central area of the obtained resin sheet in the film width direction within a range of 25 ^cm2 , and the occurrence of pinholes visible through the light was observed and visually judged according to the following criteria. ○: No pinholes were generated △: Almost no pinholes were generated ×: Many pinholes were generated

(Preparation of polyethylene terephthalate pellets (PET(I))) A continuous esterification reaction apparatus consisting of a three-stage complete mixing tank having a stirring device, a partial condenser, a raw material addition port, and a product outlet was used as an esterification reaction apparatus. TPA (terephthalic acid) was set to 2 tons/hour, EG (etylene glycol) was set to 2 mol relative to 1 mol of TPA, and antimony trioxide was set to an amount such that Sb atoms were 160 ppm relative to the generated PET. These slurries were continuously supplied to the first esterification reaction tank of the esterification reaction apparatus and reacted at 255°C at an average residence time of 4 hours under normal pressure. Next, the reaction product in the first esterification reaction tank was continuously taken out of the system and supplied to the second esterification reaction tank, and EG distilled from the first esterification reaction tank was supplied to the second esterification reaction tank in an amount of 8% by mass relative to the generated PET. Furthermore, an EG solution containing magnesium acetate tetrahydrate in an amount of 65 ppm of Mg atoms relative to the generated PET and an EG solution containing TMPA (trimethyl phosphate) in an amount of 40 ppm of P atoms relative to the generated PET were added, and the reaction was carried out at 260° C. with an average residence time of 1 hour under normal pressure. Next, the reaction product of the second esterification reaction tank was continuously taken out of the system and supplied to the third esterification reaction tank, while 0.2 mass % of porous colloidal silica with an average particle size of 0.9 μm, which was dispersed at a pressure of 39 MPa (400 kg/cm ² ) for an average of 5 times, and 0.4 mass % of synthetic calcium carbonate with an average particle size of 0.6 μm, to which 1 mass % of ammonium salt of polyacrylic acid was attached per unit of calcium carbonate, were added as 10% EG slurry, and reacted at 260°C at normal pressure with an average retention time of 0.5 hours. The esterification reaction product generated in the third esterification reaction tank was continuously supplied to the three-stage continuous polycondensation reaction device for polycondensation, filtered using a filter made of sintered stainless steel fiber with a 95% cutoff diameter of 20 μm, and then superfiltered and extruded into water. After cooling, it was cut into pieces to obtain PET chips with an inherent viscosity of 0.60 dl/g (hereinafter referred to as PET (I)). The lubricant content in the PET chips was 0.6 mass%.

(Preparation of polyethylene terephthalate particles (PET(II))) On the other hand, in the production of the above-mentioned PET(I) fragments, PET fragments with an inherent viscosity of 0.62 dl/g that are completely free of calcium carbonate, silicon dioxide and other particles were obtained (hereinafter referred to as PET(II)).

(Preparation of polyethylene terephthalate particles (PET(III))) On the other hand, in the production of the above-mentioned PET(I) chips, the particles of calcium carbonate, silica, etc. were replaced with porous colloidal silica with an average particle size of 0.2μm and synthetic calcium carbonate with an average particle size of 0.1μm. In addition, PET chips with an intrinsic viscosity of 0.62dl/g (hereinafter referred to as PET(III)) were obtained in the same manner.

(Manufacturing of acrylic resin (polyol acrylate) A-1) In a four-necked flask equipped with a stirrer, a reflux cooler, a thermometer, and a nitrogen blowing tube, 103 parts by mass of methyl methacrylate (MMA), 173 parts by mass of stearyl methacrylate (SMA), 100 parts by mass of hydroxyethyl methacrylate (HEMA), 22 parts by mass of methacrylic acid (MAA), and 929 parts by mass of isopropyl alcohol (IPA) were added, and the temperature in the flask was raised to 80°C while stirring. The flask was stirred for 3 hours while maintaining the temperature at 80°C, and then 0.5 parts by mass of 2,2-azobis-2-methyl-N-2-hydroxyethylpropionamide was added to the flask. After nitrogen replacement was performed while the temperature in the flask was raised to 120°C, the mixture was stirred at 120°C for 2 hours. Then, a 1.5 kPa decompression operation was performed at 120°C to remove the unreacted raw materials and solvent to obtain an acrylic resin (polyol acrylate). The flask was returned to atmospheric pressure and cooled to room temperature, and 1592 parts by weight of an IPA aqueous solution (water content 50% by weight) was added and mixed. Then, while stirring, ammonia was added using a dropping funnel to neutralize the acrylic resin (polyol acrylate) until the pH of the solution was in the range of 5.5 to 7.5, and an acrylic resin (polyol acrylate) (A-1) with a solid content concentration of 20% by weight was obtained. The composition ratio, Tg, elongation suitability, and acid value of the acrylic resin (polyol acrylate) (A-1) obtained by NMR measurement are shown in Table 1.

(Production of acrylic resin (polyol acrylate) (A-2) to acrylic resin (polyol acrylate) (A-6)) As shown in Table 1, except for changing the amount of MMA, SMA, HEMA, MAA, IPA during addition, and IPA aqueous solution during dilution, polyol acrylate (A-2) to polyol acrylate (A-6) having a solid content concentration of 20 mass% were obtained in the same manner as the production of acrylic resin (polyol acrylate) 1. The composition ratio, Tg, elongation suitability, and acid value of acrylic resin (polyol acrylate) (A-2) to acrylic resin (polyol acrylate) (A-6) obtained by NMR measurement are shown in Table 1. In addition, the composition ratio is expressed as n1 (unit) for MMA, n2 (unit) for SMA, n3 (unit) for HEMA, and n4 (unit) for MAA.

[Table 1] No. Acrylic resin raw materials Solvent Composition ratio in acrylic resin (mol %) Physical properties n1 n2 n3 n4 Neutralizer Aggregation When diluting Material Added quantity (weight) Material Added quantity (weight) Material Added quantity (weight) Material Added quantity (weight) Material Added quantity (weight) Material Added quantity (weight) n1 n2 n3 n4 Tg (℃) Extension suitability Acid value (mgKOH/g) A-1 M M A 103 S M A 173 H E M A 100 M A A twenty two NH3 I P A 929 IPA aqueous solution 1592 40 20 30 10 73 ○ 72 A-2 231 130 100 33 NH3 1153 1976 60 10 20 10 88 ○ 87 A-3 38 0 100 11 NH3 349 598 30 0 60 10 66 ○ 96 A-4 231 1041 100 794 NH3 5052 8660 15 20 5 60 125 △ 478 A-5 10 325 100 8 NH3 1034 1772 5 50 40 5 46 ○ twenty four A-6 0 195 100 50 NH3 804 1379 0 30 40 30 71 ○ 188 MMA: Methyl Methacrylate SMA: Stearyl Methacrylate HEMA: Hydroxyethyl Methacrylate MAA: Methacrylic Acid

(Manufacturing of Oxazoline Crosslinking Agent C-1) In a flask equipped with a stirrer, reflux cooler, nitrogen inlet tube and thermometer, add 460.6 parts of isopropyl alcohol and heat to 80°C while slowly flowing nitrogen. To the above solution, a monomer mixture consisting of 126 parts of methyl methacrylate, 210 parts of 2-isopropenyl-2-oxazoline and 84 parts of methoxy polyethylene glycol acrylate prepared in advance, and an initiator solution consisting of 21 parts of 2,2'-azobis(2-methylbutyronitrile) ("ABN-E" manufactured by Nippon Hydrazine Industries Co., Ltd.) and 189 parts of isopropanol as a polymerization initiator were added dropwise from a dropping funnel over a period of 2 hours to react. After the addition was completed, the reaction was continued for 5 hours. During the reaction, nitrogen was continuously circulated and the temperature in the flask was maintained at 80±1°C. Then, the reaction solution was cooled to obtain a resin (C-1) having an oxazoline group with a solid content concentration of 10%. The obtained resin (C-1) having an oxazoline group had an oxazoline group content of 7.7 mmol/g, and a number average molecular weight of 40,000 as determined by GPC (Gel Permeation Chromatography).

(Preparation of Oxazoline Crosslinking Agent C-2) Using the same method as the synthesis of the above-mentioned oxazoline resin (C-1), a resin (C-2) with a different composition (oxazoline amount and molecular weight) and a solid content concentration of 25% was obtained. The oxazoline amount of the obtained resin (C-2) with an oxazoline group was 4.3 mmol/g, and the number average molecular weight measured by GPC was 20,000.

(Preparation of carbodiimide crosslinking agent D-1) In a flask equipped with a stirrer, a thermometer, and a reflux cooling tube, 168 parts by mass of hexamethylene diisocyanate and 220 parts by mass of polyethylene glycol monomethyl ether (M400, average molecular weight 400) were added, and stirred at 120°C for 1 hour. Then, 26 parts by mass of 4,4'-dicyclohexylmethane diisocyanate and 3.8 parts by mass of 3-methyl-1-phenyl-2-phosphocyclopentene-1-oxide as a carbodiimidization catalyst (2% by mass relative to the total isocyanate) were added, and the mixture was further stirred at 185°C for 5 hours under a nitrogen flow. The infrared spectrum of the reaction solution was measured to confirm that the absorption at wavelengths of 2200 cm ^-1 to 2300 cm ^-1 disappeared. The solution was cooled to 60°C and 567 parts by weight of ion exchange water was added to obtain a carbodiimide water-soluble resin (D-1) having a solid content of 40% by weight.

(Manufacturing of isocyanate crosslinking agent E-1) In a flask equipped with a stirrer, a thermometer, and a reflux cooling tube, 100 parts by mass of a polyisocyanate compound having an isocyanurate structure (manufactured by Asahi Kasei Chemicals, DURANATE TPA) with hexamethylene diisocyanate as a raw material, 55 parts by mass of propylene glycol monomethyl ether acetate, and 30 parts by mass of polyethylene glycol monomethyl ether (average molecular weight 750) were added, and the mixture was kept at 70°C for 4 hours under a nitrogen atmosphere. Then, the temperature of the reaction solution was lowered to 50°C, and 47 parts by mass of methyl ethyl ketone oxime was added dropwise. The infrared spectrum of the reaction solution was measured to confirm that the absorption of the isocyanate group disappeared, and a blocked polyisocyanate aqueous dispersion (E-1) with a solid content of 75% by mass was obtained.

(Silica particles F-1) Colloidal silica (Nissan Chemical Co., Ltd., trade name SNOWTEX XL, average particle size 40nm, solid content concentration 40% by mass)

(Example 1) (Preparation of release coating liquid 1) Prepare release coating liquid 1 of the following composition. (Release coating liquid 1) Water 48.01 parts by mass Isopropyl alcohol 25.95 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 14.00 parts by mass Oxazoline crosslinking agent C-1 (solid content concentration 10% by mass) 12.00 parts by mass Additive G-1 0.04 parts by mass (Polyether-modified polydimethylsiloxane, 67Additive, solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

(Production of polyester film) After drying the PET chips, melt them at 285℃, and then melt them at 290℃ in another melt extruder. Then, two-stage filtration is performed: a filter made of sintered stainless steel fibers with a 95% cutoff diameter of 15μm and a filter made of sintered stainless steel particles with a 95% cutoff diameter of 15μm. The two layers are merged and layered in such a way that PET (I) becomes the surface layer B (the layer opposite to the release surface) and PET (II) becomes the surface layer A (the layer on the side of the release surface). The layers are extruded (cast) at a speed of 45 m/min into a sheet. The sheets are electrostatically bonded to a casting drum at 30°C by an electrostatic bonding method and then cooled to obtain an unstretched polyethylene terephthalate sheet. The layer ratio is adjusted in such a way that PET (I)/(II) = 60 mass %/40 mass % is calculated according to the ejection amount of each extruder. Next, the unstretched sheet was heated by an infrared heater and stretched 3.5 times in the longitudinal direction at a roll temperature of 80° C. by the speed difference between the rolls.

Then, the above release coating liquid was applied to the surface layer A of the PET film using a rod coater and dried at 80°C for 15 seconds. In addition, the coating amount after final stretching and drying was adjusted to 0.07μm. Then, the film was stretched 4.0 times in the width direction at 150°C using a tenter, and heated at 230°C for 4 seconds while the length of the film in the width direction was fixed. Then, a relaxation treatment of 3% in the width direction was performed at 170°C to obtain a 31μm thick in-line release-coated polyester film. The surface layer B (opposite side to the release surface) of the obtained film had an Sa of 28nm and a P of 754nm. Here, the PET substrate not including the release layer is designated as Z. The intrinsic viscosity of the obtained PET substrate is 0.59 dl/g. In addition, the surface layer A of the PET substrate not including the release layer has a Sa of 1 nm and a P of 16 nm.

(Example 2) A release polyester film was obtained in the same manner as in Example 1 except that the release coating liquid 1 was changed to the release coating liquid 2 described below. (Release coating liquid 2) Water 54.03 parts by mass Isopropyl alcohol 23.93 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 18.00 parts by mass Oxazoline crosslinking agent C-1 (solid content concentration 10% by mass) 4.00 parts by mass Additive G-1 0.04 parts by mass (Polyether-modified polydimethylsiloxane, 67Additive, solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

(Example 3) A release polyester film was obtained in the same manner as in Example 1 except that the release coating liquid 1 was changed to the release coating liquid 3 described below. (Release coating liquid 3) Water 51.01 parts by mass Isopropyl alcohol 24.95 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 16.00 parts by mass Oxazoline crosslinking agent C-1 (solid content concentration 10% by mass) 8.00 parts by mass Additive G-1 0.04 parts by mass (Polyether-modified polydimethylsiloxane, 67 Additive, solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

(Example 4) A release polyester film was obtained in the same manner as in Example 1 except that the release coating liquid 1 was changed to the release coating liquid 4 described below. (Release coating liquid 4) Water 41.99 parts by mass Isopropyl alcohol 27.97 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 10.00 parts by mass Oxazoline crosslinking agent C-1 (solid content concentration 10% by mass) 20.00 parts by mass Additive G-1 0.04 parts by mass (Polyether-modified polydimethylsiloxane, 67 Additive, solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

(Example 5) A release polyester film was obtained in the same manner as in Example 1 except that the acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) in the release coating liquid 1 used in Example 1 was changed to acrylic resin (polyol acrylate resin) A-2 (solid content concentration 20% by mass).

(Example 6) A release coating liquid 6 was used. The release coating liquid 6 was obtained in the same manner as in Example 1 except that the crosslinking agent in the release coating liquid 1 used in Example 1 was changed to an oxazoline crosslinking agent C-2 (solid content concentration 25 mass %). (Release coating liquid 6) Water 55.23 parts by mass Isopropyl alcohol 25.93 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 14.00 parts by mass Oxazoline crosslinking agent C-2 (solid content concentration 25% by mass) 4.80 parts by mass Additive G-1 0.04 parts by mass (Polyether-modified polydimethylsiloxane, 67 Additive, solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

(Example 7) A release coating liquid 7 was used, wherein the acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20 mass %) in the release coating liquid 1 used in Example 1 was changed to acrylic resin (polyol acrylate resin) A-2 (solid content concentration 20 mass %), and the crosslinking agent was changed to oxazoline crosslinking agent C-2 (solid content concentration 25 mass %). A release polyester film was obtained in the same manner as in Example 1. (Release coating liquid 7) Water 55.23 parts by mass Isopropyl alcohol 25.93 parts by mass Acrylic resin (polyol acrylate resin) A-2 (solid content concentration 20% by mass) 14.00 parts by mass Oxazoline crosslinking agent C-2 (solid content concentration 25% by mass) 4.80 parts by mass Additive G-1 0.04 parts by mass (Polyether-modified polydimethylsiloxane, 67 Additive, solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

(Example 8) A release coating liquid 8 was used. The release coating liquid 8 was obtained in the same manner as in Example 1 except that the crosslinking agent in the release coating liquid 1 used in Example 1 was changed to a carbodiimide crosslinking agent D-1 (solid content concentration 40 mass %). (Release coating liquid 8) Water 56.63 parts by mass Isopropyl alcohol 26.97 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 12.00 parts by mass Carbodiimide crosslinking agent D-1 (solid content concentration 40% by mass) 4.00 parts by mass Additive G-1 0.04 parts by mass (Polyether-modified polydimethylsiloxane, 67Additive, solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

(Example 9) A release polyester film was obtained in the same manner as in Example 1 except that the release coating liquid 1 was changed to the release coating liquid 9 described below. (Release coating liquid 9) Water 47.51 parts by mass Isopropyl alcohol 25.95 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 14.00 parts by mass Oxazoline crosslinking agent C-1 (solid content concentration 10% by mass) 12.00 parts by mass Silicon dioxide particles F-1 0.50 parts by mass (average particle size 40nm, solid content concentration 40% by mass) Additive G-1 0.04 parts by mass (Polyether-modified polydimethylsiloxane, 67Additive, solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

(Example 10) A release polyester film was obtained in the same manner as in Example 1 except that the release coating liquid 1 was changed to the release coating liquid 10 described below. (Release coating liquid 10) Water 47.01 parts by mass Isopropyl alcohol 25.95 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 14.00 parts by mass Oxazoline crosslinking agent C-1 (solid content concentration 10% by mass) 12.00 parts by mass Silicon dioxide particles F-1 1.00 parts by mass (average particle size 40nm, solid content concentration 40% by mass) Additive G-1 0.04 parts by mass (Polyether-modified polydimethylsiloxane, 67Additive, solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

(Example 11) A release coating liquid 11 is used, wherein the additive in the release coating liquid 1 used in Example 1 is changed to polyester-modified polydimethylsiloxane G-2 (solid content concentration 25 mass %), and a release polyester film is obtained in the same manner as in Example 1. (Release coating liquid 11) Water 47.90 parts by mass Isopropyl alcohol 25.93 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 14.00 parts by mass Oxazoline crosslinking agent C-1 (solid content concentration 10% by mass) 12.00 parts by mass Additive G-2 0.17 parts by mass (Polyester modified polydimethylsiloxane, BYK-315N, solid content concentration 25% by mass, manufactured by BYK-Chemie Japan)

(Example 12) A release coating liquid 12 was used. The release coating liquid 12 was obtained in the same manner as in Example 1 except that the additive in the release coating liquid 1 used in Example 1 was changed to a long-chain alkyl additive G-1 (solid content concentration 15 mass %). (Release coating liquid 12) Water 47.80 parts by mass Isopropyl alcohol 25.93 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 14.00 parts by mass Oxazoline crosslinking agent C-1 (solid content concentration 10% by mass) 12.00 parts by mass Additive H-1 0.27 parts by mass (PEELOIL (registered trademark) 406, solid content concentration 15% by mass, manufactured by Lion Specialty Chemicals)

(Example 13) A release coating liquid 13 described below is used. The release coating liquid 13 does not contain the additives in the release coating liquid 1 used in Example 1. A release polyester film is obtained in the same manner as in Example 1. (Release coating liquid 13) Water 48.05 parts by mass Isopropyl alcohol 25.95 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 14.00 parts by mass Oxazoline crosslinking agent C-1 (solid content concentration 10% by mass) 12.00 parts by mass

(Example 14) A release polyester film was obtained in the same manner as in Example 1 except that the thickness of the release layer was changed to 0.035 μm.

(Example 15) A release polyester film was obtained in the same manner as in Example 1 except that the thickness of the release layer was changed to 0.100 μm.

(Example 16) A release polyester film was obtained in the same manner as in Example 1 except that the thickness of the release layer was changed to 0.140 μm.

(Example 17) A release polyester film was obtained in the same manner as in Example 1 except that the acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) in the release coating liquid 1 used in Example 1 was changed to acrylic resin (polyol acrylate resin) A-4 (solid content concentration 20% by mass).

(Example 18) A release polyester film was obtained in the same manner as in Example 1 except that the acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) in the release coating liquid 1 used in Example 1 was changed to acrylic resin (polyol acrylate resin) A-5 (solid content concentration 20% by mass).

(Example 19) A release polyester film was obtained in the same manner as in Example 1 except that PET(II) of the surface layer A of the PET substrate was changed to PET(III). Here, the PET substrate not including the release layer was set as Y. The intrinsic viscosity of the obtained PET substrate was 0.59 dl/g. In addition, the surface layer A of the PET substrate Y before laminating the release layer had Sa of 10 nm and P of 130 nm.

(Example 20) A release polyester film was obtained in the same manner as in Example 1 except that the release coating liquid 1 was changed to the release coating liquid 16 described below. (Release coating liquid 16) Water 47.85 parts by mass Isopropyl alcohol 25.95 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 14.00 parts by mass Oxazoline crosslinking agent C-1 (solid content concentration 10% by mass) 12.00 parts by mass Additive G-1 0.20 parts by mass (Polyether-modified polydimethylsiloxane, 67Additive, solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

(Example 21) A release coating liquid 17 was used, wherein the acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20 mass %) in the release coating liquid 1 used in Example 1 was replaced with acrylic resin (polyol acrylate resin) A-6 (solid content concentration 20 mass %). A release polyester film was obtained in the same manner as in Example 1 except that the release coating liquid 17 was used.

(Comparative Example 1) A release polyester film was obtained in the same manner as in Example 1 except that the release coating liquid 1 was replaced with the release coating liquid 18 described below. (Release coating liquid 18) Water 76.76 parts by mass Isopropyl alcohol 19.19 parts by mass Hardening polysilicone aqueous emulsion B-1 4.01 parts by mass (Shin-Etsu Silicone, solid content concentration 40%, KM3951) Platinum catalyst B-2 0.04 parts by mass (Shin-Etsu Silicone, CAT-PM-10A)

(Comparative Example 2) A release coating liquid 19 was used, wherein the acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20 mass %) in the release coating liquid 1 used in Example 1 was replaced with acrylic resin (polyol acrylate resin) A-3 (solid content concentration 20 mass %). A release polyester film was obtained in the same manner as in Example 1.

(Comparative Example 3) A polyester film was obtained in the same manner as in Example 1 except that the release coating liquid 1 was changed to the release coating liquid 20 described below. (Release coating liquid 20) Water 58.30 parts by mass Isopropyl alcohol 25.95 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 14.00 parts by mass Isocyanate crosslinking agent E-1 (solid content concentration 75% by mass) 1.72 parts by mass Surfactant G-1 0.04 parts by mass (Polyether-modified polydimethylsiloxane, 67 Additive, solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

(Comparative Example 4) A polyester film was obtained in the same manner as in Example 1 except that the release coating liquid 1 was changed to the release coating liquid 21 described below. (Release coating liquid 21) Water 57.04 parts by mass Isopropyl alcohol 22.93 parts by mass Acrylic resin (polyol acrylate resin) A-1 (solid content concentration 20% by mass) 20.00 parts by mass Surfactant G-1 0.04 parts by mass (Polyether-modified polydimethylsiloxane, 67 Additive. Solid content concentration 100% by mass, manufactured by Toray Dow Corning Co., Ltd.)

The evaluation results of each embodiment and comparative example are shown in Table 2.

[Table 2] PET substrate Release coating liquid (composition ratio is expressed as the mass percentage of each solid component) Release layer Ceramic green body Resin Sheet Coating liquid Resin Crosslinking agent or catalyst Resin/crosslinking agent or catalyst ratio (weight parts) particle Particle ratio (mass fraction) Additives Additive ratio (weight) Ceramic peeling force (mN/mm) Ceramic peeling force determination Average surface roughness Sa (nm) Maximum protrusion height P (nm) Release coating thickness (nm) Surface free energy γs (mJ/m ² ) Pinhole Pinhole Type SMA ratio mol% Embodiment 1 Z 1 A-1 20 C-1 70/30 - - G-1 1.0 1.9 ○ 0.9 35.4 70 34.5 ○ ○ Embodiment 2 Z 2 A-1 20 C-1 90/10 - - G-1 1.0 5.4 △ 0.9 35.6 70 32.3 ○ ○ Embodiment 3 Z 3 A-1 20 C-1 80/20 - - G-1 1.0 2.5 ○ 1.0 35.9 70 33.5 ○ ○ Embodiment 4 Z 4 A-1 20 C-1 50/50 - - G-1 1.0 2.0 ○ 0.9 34.7 70 35.7 ○ ○ Embodiment 5 Z 5 A-2 10 C-1 70/30 - - G-1 1.0 3.2 ○ 0.9 34.2 70 39.6 ○ ○ Embodiment 6 Z 6 A-1 20 C-2 70/30 - - G-1 1.0 2.5 ○ 0.9 34.5 70 32.9 ○ ○ Embodiment 7 Z 7 A-2 10 C-2 70/30 - - G-1 1.0 4.3 △ 0.9 34.6 70 38.5 ○ ○ Embodiment 8 Z 8 A-1 20 D-1 60/40 - - G-1 1.0 3.5 ○ 1.0 37.8 70 35.8 ○ ○ Embodiment 9 Z 9 A-1 20 C-1 70/30 F-1 5 G-1 1.0 1.7 ○ 2.1 46.0 70 36.8 ○ ○ Embodiment 10 Z 10 A-1 20 C-1 70/30 F-1 10 G-1 1.0 1.7 ○ 2.9 48.2 70 34.8 ○ ○ Embodiment 11 Z 11 A-1 20 C-1 70/30 - - G-2 1.0 2.0 ○ 0.9 35.4 70 34.7 ○ ○ Embodiment 12 Z 12 A-1 20 C-1 70/30 - - H-1 1.0 1.9 ○ 1.0 38.6 70 33.2 ○ ○ Embodiment 13 Z 13 A-1 20 C-1 70/30 - - - - 2.1 ○ 1.0 36.3 70 35.7 ○ ○ Embodiment 14 Z 1 A-1 20 C-1 70/30 - - G-1 1.0 2.0 ○ 0.8 30.1 35 35.5 ○ ○ Embodiment 15 Z 1 A-1 20 C-1 70/30 - - G-1 1.0 2.0 ○ 1.0 38.2 100 34.1 ○ ○ Embodiment 16 Z 1 A-1 20 C-1 70/30 - - G-1 1.0 2.0 ○ 1.2 39.4 140 35.1 ○ ○ Embodiment 17 Z 14 A-4 20 C-1 70/30 - - G-1 1.0 1.9 ○ 4.4 70.0 70 34.6 △ △ Embodiment 18 Z 15 A-5 50 C-1 70/30 - - G-1 1.0 5.1 △ 0.9 34.7 70 31.2 ○ ○ Embodiment 19 Y 1 A-1 20 C-1 70/30 - - G-1 1.0 1.9 ○ 10.5 152.0 70 34.5 △ △ Embodiment 20 Z 16 A-1 20 C-1 70/30 - - G-1 5.0 2.1 ○ 0.9 35.5 70 34.5 ○ ○ Embodiment 21 Z 17 A-６ 30 C-1 70/30 - - G-1 1.0 1.7 ○ 0.9 36.7 70 34.5 ○ ○ Comparison Example 1 Z 18 B-1 0 B-2 98/2 - - - - 1.7 ○ 0.9 48.2 70 18.0 × × Comparison Example 2 Z 19 A-3 0 C-1 70/30 - - G-1 1.0 10.5 × 0.9 32.8 70 63.2 × × Comparison Example 3 Z 20 A-1 20 E-1 70/30 - - G-1 1.0 8.5 × 0.9 37.2 70 34.3 × × Comparison Example 4 Z twenty one A-1 20 - 100/0 - - G-1 1.0 Unable to determine × 0.9 35.6 70 31.5 × ×

In the above Table 2, the composition of each of the resin, crosslinking agent, particle, and additive in the release coating liquid is described in terms of mass fraction of solid content. The sum of the mass fractions of the solid content of the resin, crosslinking agent, particle, and additive in the release coating liquid becomes the mass fraction of the total solid content of the release layer. For each of the resin, crosslinking agent, particle, and additive, the mass fraction of the solid content of each of the resin, crosslinking agent, particle, and additive can be divided by the mass fraction of the total solid content of the release layer to determine the mass percentage of the resin, crosslinking agent, particle, and additive in the total solid content of the release layer.

In Examples 1 to 21, the manufacturing cost can be suppressed by in-line coating, and when the formed sheet is further thinned, the sheet slurry and the resin solution have good wettability and a moderate sheet peeling force. On the other hand, in Comparative Example 1, when the sheet is further thinned, the wettability of the sheet slurry and the resin solution is poor, and pinholes are generated. In Comparative Example 2, since the acrylic resin does not contain a long-chain alkyl component, the surface free energy becomes larger and the sheet peeling force becomes larger. Since the sheet peeling force is heavy, pinholes are generated in the sheet during peeling. In Comparative Examples 3 and 4, since no oxazoline crosslinking agent or carbodiimide crosslinking agent was used, the coating was not sufficiently hardened and the peeling force increased. Since the peeling force was strong, pinholes were generated in the sheet during peeling. [Industrial Applicability]

According to the present invention, a release film can be manufactured, which can be manufactured at a reduced manufacturing cost and has all the characteristics of good wettability with sheet slurry and resin solution and appropriate sheet peeling force even when the sheet is made thinner.

Claims (10)

A release film comprises a polyester film and a release layer; the release layer is provided on at least one side of the polyester film directly or via another layer, the release layer is formed by curing a composition, the composition comprising: an acrylic resin having a long-chain alkyl group, and at least one crosslinking agent selected from an oxazoline crosslinking agent or a carbodiimide crosslinking agent; and the acid value of the acrylic resin having a long-chain alkyl group is greater than 40 mgKOH/g and less than 400 mgKOH/g. The release film as described in claim 1, wherein the acrylic resin contains an acrylate monomer containing a long-chain alkyl group; the copolymerization ratio of the acrylate monomer containing a long-chain alkyl group in the acrylic resin is greater than 5 mol% and less than 60 mol%. The release film as described in claim 1 or 2, wherein the crosslinking agent is an oxazoline crosslinking agent, and the oxazoline crosslinking agent contains 3.0 mmol/g to 9.0 mmol/g of oxazoline groups. A release film as described in claim 1 or 2, wherein the thickness of the release layer is greater than 0.001 μm and less than 2 μm. The release film as described in claim 1 or 2, wherein the release film is a release film used for manufacturing ceramic green bodies. A method for manufacturing a release film comprises manufacturing a release film comprising a polyester film and a release layer; the release film has a release layer on at least one side of the polyester film directly or through other layers; the release layer is formed by curing a composition, the composition comprising: an acrylic resin having a long-chain alkyl group, and at least one crosslinking agent selected from an oxazoline-based crosslinking agent or a carbodiimide-based crosslinking agent; the acid value of the acrylic resin having a long-chain alkyl group is greater than 40 mgKOH/g and less than 400 mgKOH/g; after applying a release coating liquid to an unstretched film or a uniaxially stretched film, the film is stretched along at least the uniaxial direction of the unstretched film, and heat-treated. The method for manufacturing a release film as described in claim 6 is a method for manufacturing a release film for manufacturing ceramic green bodies. A method for manufacturing a ceramic green body, wherein the ceramic green body is formed using a release film for manufacturing a ceramic green body as described in claim 5, or a method for manufacturing a release film for manufacturing a ceramic green body as described in claim 7. The method for manufacturing a ceramic green body as described in claim 8, wherein the thickness of the manufactured ceramic green body is greater than 0.2μm and less than 2.0μm. A method for manufacturing a ceramic capacitor is a method for manufacturing a ceramic green body as described in claim 8 or 9.