CN115401974A

CN115401974A - Release film for producing ceramic green sheet

Info

Publication number: CN115401974A
Application number: CN202211019624.9A
Authority: CN
Inventors: 重野健斗; 柴田悠介; 中谷充晴
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2018-08-10
Filing date: 2019-08-06
Publication date: 2022-11-29
Also published as: JP6699816B1; JP2020114669A; JP2020114671A; SG11202100938WA; PH12021550196A1; CN112918057A; JPWO2020032007A1; SG10202101747TA; WO2020032007A1; KR102335930B1; CN115401975A; JP6699814B1; KR20210022163A; CN112334305A; PH12021550317A1; JP6699813B1; JP2020114670A; KR102335164B1; JP6683295B1; KR20210018512A

Abstract

[ problem ] to provide: a release film for producing a ceramic green sheet, which can be peeled off with a low and uniform force even when the thickness of the ultra-thin ceramic green sheet is 1 μm or less, and which can suppress the transfer of an organosilicon component to the ceramic green sheet without causing defects such as pinholes. [ solution ] A release film for producing a ceramic green sheet, which comprises a biaxially oriented polyester film as a substrate, wherein at least one surface of the substrate has a surface layer A substantially free of inorganic particles, and a release layer is laminated on the surface of the surface layer A of at least one surface directly or via another layer, wherein the release layer is obtained by curing a composition comprising at least a release agent and a melamine compound, the release agent is a carboxyl group-containing polyorganosiloxane, and the content of the melamine compound is 80 mass% or more relative to the solid content of the release layer-forming composition.

Description

Release film for producing ceramic green sheet

The application is a divisional application with the application date of 2019, 8 and 6, and the application number of 201980043670.2, entitled "release film for manufacturing ceramic green sheets".

Technical Field

The present invention relates to a release film for producing a ceramic green sheet, and more particularly, to a release film for producing an ultrathin layer, which can suppress the occurrence of defective steps due to pinholes and thickness unevenness in the production of an ultrathin layer ceramic green sheet, and can suppress the transfer of a silicone component in a release layer to a produced ceramic green sheet.

Background

Conventionally, a release film comprising a polyester film as a base material and a release layer laminated thereon has been used for molding a ceramic green sheet such as a laminated ceramic capacitor or a ceramic substrate. In recent years, as the size and capacity of multilayer ceramic capacitors have been reduced, the thickness of ceramic green sheets has also tended to be reduced. The ceramic green sheet is formed by applying a slurry containing a ceramic component such as barium titanate and a binder resin to a release film and drying the applied slurry. After printing electrodes on the formed ceramic green sheet and peeling it from the release film, the ceramic green sheet is laminated, pressed, fired, and applied with external electrodes, thereby producing a laminated ceramic capacitor. When a ceramic green sheet is formed on the surface of a release layer of a polyester film, there is a problem that fine protrusions on the surface of the release layer affect the formed ceramic green sheet, and thus defects such as shrinkage and pinholes are likely to occur. Therefore, various methods for realizing a surface of a release layer having excellent flatness are being developed. (see, for example, patent documents 1 and 2).

However, in recent years, ceramic green sheets have been further thinned, and ceramic green sheets having a thickness of 1.0 μm or less, particularly 0.2 to 1.0 μm, have been required. Since the strength of the ceramic green sheet is reduced with the progress of the thinning, it is desired not only to smooth the surface of the release layer but also to reduce and uniformize the peeling force when the ceramic green sheet is peeled from the release film. That is, it is important to minimize the force applied to the ceramic green sheet when the ceramic green sheet is peeled from the release film so as not to damage the ceramic green sheet.

In addition, the silicone component in the release layer is easily transferred to the surface in contact with the release layer of the ceramic green sheet to be produced. The silicone transferred surface has slidability and the adhesiveness is reduced. When a ceramic green sheet is produced from such a release film that is likely to transfer the silicone component, and a laminated ceramic product is produced using the ceramic green sheet, when pressure is applied between the laminated ceramic green sheets, the surface direction between the layers of the laminated ceramic product may be displaced. If such a shift occurs, the positional accuracy of the electrodes and the like of the obtained laminated ceramic ware is degraded, and the product performance of the laminated ceramic ware cannot be obtained. Therefore, a release film which is less likely to transfer the silicone component to the ceramic green sheet is required.

Therefore, a release film having a small silicone transfer amount has been proposed by using a polyorganosiloxane having at least 1 hydroxyl group in 1 molecule and a melamine resin which reacts with a hydroxyl group (for example, see patent document 3). However, although the amount of transfer is small, the hydroxyl group of the polyorganosiloxane strongly interacts with the melamine resin in the drying step, and therefore, the silicone is less likely to transfer to the surface of the finally obtained release layer, and the ceramic green sheet may be damaged due to an increased peeling force.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2000-117899

Patent document 2: international publication No. 2013/145864

Patent document 3: japanese patent laid-open publication No. 2017-007227

Disclosure of Invention

Problems to be solved by the invention

The present invention is based on the problem of the prior art. That is, an object of the present invention is to provide a release film for producing a ceramic green sheet, which can form a ceramic green sheet with few defects and can suppress the transfer of a silicone component to the ceramic green sheet, even if an ultrathin layer having a uniform thickness of 1 μm or less is obtained while maintaining high smoothness of the surface of the release layer of the release film and a low peeling force.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that: a release film for producing a ceramic green sheet, which is capable of suppressing transfer of an organosilicon component to a ceramic green sheet and is excellent in releasability, can be obtained by using a polyester film, providing a release layer on at least one surface, and curing the release layer with a composition containing at least a melamine compound and a polyorganosiloxane containing a carboxyl group.

That is, the present invention is composed of the following configurations.

1. A release film for producing a ceramic green sheet, comprising a biaxially oriented polyester film as a substrate, at least one surface of the substrate having a surface layer A substantially free of inorganic particles, and a release layer laminated on the surface of the surface layer A of the at least one surface directly or via another layer, wherein the release layer is obtained by curing a composition containing at least a release agent and a melamine compound, the release agent is a carboxyl group-containing polyorganosiloxane, and the content of the melamine compound is 80% by mass or more relative to the solid content of the release layer-forming composition.

2. The release film for producing a ceramic green sheet according to the above item 1, wherein the release film has a surface layer a substantially free of inorganic particles on one surface of a base material, and a surface layer B on the opposite side of the base material from the surface layer a, the surface layer B containing particles, at least a part of the particles being silica particles and/or calcium carbonate particles, and the total content of the particles is 5000 to 15000ppm with respect to the mass of the surface layer B.

3. The release film for producing a ceramic green sheet according to the above 1 or 2, wherein a region surface average roughness (Sa) of a release layer of the release film is 7nm or less, and a maximum protrusion height (P) is 100nm or less.

4. A method for producing a ceramic green sheet, which comprises forming a ceramic green sheet by using the release film for producing a ceramic green sheet described in any one of the above items 1 to 3, wherein the formed ceramic green sheet has a thickness of 0.2 to 1.0. Mu.m.

5. A method for producing a ceramic capacitor, which comprises the method for producing a ceramic green sheet according to the above-mentioned item 4.

ADVANTAGEOUS EFFECTS OF INVENTION

The release film for producing an ultrathin ceramic green sheet of the present invention can suitably produce an ultrathin ceramic green sheet having a smooth surface of a release layer, in which occurrence of process defects due to pinholes and thickness unevenness can be suppressed in the production of a ceramic green sheet, and transfer of a silicone component in the release layer to the ceramic green sheet is small, as compared with a conventional release film for producing a ceramic green sheet, and the thickness of the ultrathin ceramic green sheet is 0.2 to 1.0 μm.

Detailed Description

The present invention will be described in detail below.

The release film for producing an ultrathin ceramic green sheet of the present invention is preferably: the biaxially oriented polyester film has a surface layer A substantially free of inorganic particles on at least one surface thereof, and a release layer obtained by curing a composition containing at least a melamine compound and a polyorganosiloxane containing a carboxyl group is laminated on the surface layer A directly or with another layer interposed therebetween.

(polyester film)

In the present invention, the polyester constituting the biaxially oriented polyester film used as the substrate is not particularly limited, and a polyester generally used as a substrate for a release film can be used by film-forming, and a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component is preferable, and for example, a polyethylene terephthalate, a poly (2,6-polyethylene naphthalate), a polybutylene terephthalate, a polytrimethylene terephthalate, or a copolymer mainly composed of these resins is more preferable, and a polyester film composed of a polyethylene terephthalate is particularly preferable. The polyethylene terephthalate has a repeating unit of preferably 90 mol% or more, more preferably 95 mol% or more, and other dicarboxylic acid component and diol component may be copolymerized in a small amount, but from the viewpoint of cost, it is preferably produced from only terephthalic acid and ethylene glycol. In addition, known additives such as an antioxidant, a light stabilizer, an ultraviolet absorber, a crystallizing agent, and the like may be added within a range in which the effect of the film of the present invention is not inhibited. The polyester film is preferably a biaxially oriented polyester film for the reason of high elastic modulus in both directions.

The intrinsic viscosity of the polyethylene terephthalate film is preferably 0.50 to 0.70dl/g, and more preferably 0.52 to 0.62dl/g. When the intrinsic viscosity is 0.50dl/g or more, breakage is not likely to occur in the drawing step, and therefore, it is preferable. On the other hand, a value of 0.70dl/g or less is preferred because it is excellent in cuttability and does not cause dimensional defects when cut to a predetermined product width. In addition, the raw material pellets are preferably subjected to sufficient vacuum drying.

The method for producing the biaxially oriented polyester film of the present invention is not particularly limited, and conventionally used methods can be used. For example, the polyester can be obtained by melting the polyester with an extruder, extruding the melt into a film, cooling the film with a rotating cooling drum to obtain an unstretched film, and biaxially stretching the unstretched film. The biaxially stretched film can be obtained by a method of sequentially biaxially stretching a uniaxially stretched film in the longitudinal direction or in the transverse direction while being stretched in the transverse direction or in the longitudinal direction, or a method of simultaneously biaxially stretching an unstretched film while being stretched in the longitudinal direction and in the transverse direction.

In the present invention, the stretching temperature at the time of stretching the polyester film is preferably set to be not less than the secondary transition point (Tg) of the polyester. The stretching is preferably performed by1 to 8 times, particularly 2 to 6 times, in the longitudinal and lateral directions.

The thickness of the polyester film is preferably 12 to 50 μm, more preferably 15 to 38 μm, and still more preferably 19 to 33 μm. When the thickness of the film is 12 μm or more, there is no possibility of deformation due to heat in the step of processing a release layer or molding a ceramic green sheet during the production of the film, and therefore, it is preferable. On the other hand, a film thickness of 50 μm or less is preferable because the amount of the film to be discarded after use is not excessive and the environmental load can be reduced.

The biaxially oriented polyester film substrate may have a single layer or a plurality of layers of 2 or more, and preferably has a surface layer a substantially free of inorganic particles on at least one surface. In the case of a laminated polyester film comprising 2 or more layers, it is preferable that the surface layer B which may contain particles or the like is provided on the opposite side of the surface layer A which does not substantially contain inorganic particles. When the layer on the side to which the release layer is applied is the surface layer a, the layer on the opposite side thereof is the surface layer B, and the core layers other than these are the layers C, examples of the layer structure in the thickness direction include a laminate structure such as release layer/a/B or release layer/a/C/B. Of course, the layer C may be constituted by a plurality of layers. In addition, the surface layer B may contain no particles. In this case, in order to impart slidability for winding the film into a roll shape, it is preferable to provide a coating layer containing particles and a binder on the surface layer B.

In the biaxially oriented polyester film substrate of the present invention, the surface layer a on the side on which the coating release layer is formed preferably contains substantially no inorganic particles. At this time, the regional surface average roughness (Sa) of the surface layer a is preferably 7nm or less. When the Sa is 7nm or less, pinholes are less likely to occur during the molding of the laminated ultrathin ceramic green sheet, and therefore, the Sa is preferable. The smaller the area surface average roughness (Sa) of the surface layer a is, the more preferable it is, but may be 0.1nm or more. Here, when an anchor coat or the like described later is provided on the surface layer a, the coat preferably contains substantially no inorganic particles, and the region surface average roughness (Sa) after the coats are laminated preferably falls within the above range. In the present invention, "substantially no inorganic particles" means a content of 50ppm or less, preferably 10ppm or less, and most preferably not more than the detection limit, when an inorganic element is quantitatively determined by fluorescent X-ray analysis. This is because, even if the inorganic particles are not positively added to the film, contamination components derived from foreign substances and contaminants adhering to lines and devices in the production process of the raw material resin or the film may be peeled off and mixed into the film.

In the biaxially oriented polyester film substrate of the present invention, the surface layer B on the side opposite to the side on which the release layer is formed preferably contains particles, and particularly preferably silica particles and/or calcium carbonate particles, from the viewpoint of the slidability of the film and the ease of air discharge. The content of the particles contained is preferably 5000 to 15000ppm based on the total amount of the particles in the surface layer B. In this case, the regional surface average roughness (Sa) of the thin film of the surface layer B is preferably in the range of 1 to 40 nm. More preferably in the range of 5 to 35 nm. When the total of the silica particles and/or calcium carbonate particles is 5000ppm or more and the Sa is 1nm or more, air can be uniformly discharged when the film is wound into a roll, and the roll shape is good and the flatness is good, and thus the method is suitable for producing an ultrathin ceramic green sheet. Further, silica particles and/or calcium carbonate particles in a total amount of 15000ppm or less and Sa of 40nm or less are preferable because aggregation of the lubricant hardly occurs and coarse protrusions are not generated, and therefore, the quality is stable in the production of an ultra-thin ceramic green sheet.

As the particles contained in the surface layer B, inactive inorganic particles and/or heat-resistant organic particles, etc. may be used in addition to silica and/or calcium carbonate. From the viewpoint of transparency and cost, silica particles and/or calcium carbonate particles are more preferably used, and examples of other inorganic particles that can be used include alumina-silica composite oxide particles, hydroxyapatite particles, and the like. Examples of the heat-resistant organic particles include crosslinked polyacrylic acid-based particles, crosslinked polystyrene particles, and benzoguanamine-based particles. In the case of using silica particles, porous colloidal silica is preferable, and in the case of using calcium carbonate particles, light calcium carbonate surface-treated with a polyacrylic acid-based polymer compound is preferable from the viewpoint of preventing the lubricant from falling off.

The average particle diameter of the particles added to the surface layer B is preferably 0.1 μm or more and 2.0 μm or less, and particularly preferably 0.5 μm or more and 1.0 μm or less. When the average particle diameter of the particles is 0.1 μm or more, the slip of the release film is good, and therefore, it is preferable. In addition, an average particle diameter of 2.0 μm or less is preferable because it is not necessary to cause pinholes in the ceramic green sheet due to coarse particles on the surface of the release layer.

The surface layer B may contain particles of 2 or more different raw materials. Further, the particles may contain the same kind of particles and have different average particle diameters.

When the surface layer B does not contain particles, it is preferable to make it slippery with a coating layer containing particles on the surface layer B. The present coating layer is not particularly limited, and is preferably provided by line coating (Inline coat) in which coating is performed in film formation of a polyester film. When the surface layer B does not contain particles and the surface layer B has a coating layer containing particles thereon, the regional surface average roughness (Sa) of the surface of the coating layer is preferably in the range of 1 to 40nm for the same reason as the above-described regional surface average roughness (Sa) of the surface layer B. More preferably in the range of 5 to 35 nm.

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

The thickness ratio of the surface layer a as a layer on the side where the release layer is provided is preferably 20% to 50% of the total layer thickness of the base film. When the content is 20% or more, the inside of the film is less likely to be affected by the particles contained in the surface layer B and the like, and the region surface average roughness Sa easily satisfies the above range, which is preferable. When the thickness of the base film is 50% or less of the total thickness of the base film, the use ratio of the recycled material in the surface layer B can be increased, and the environmental load is reduced, which is preferable.

In addition, from the viewpoint of economy, 50 to 90 mass% of film scrap or recycled material of plastic bottles can be used for the layers other than the surface layer a (the surface layer B or the intermediate layer C). In this case, the type, amount, particle diameter, and regional surface average roughness (Sa) of the lubricant contained in the surface layer B are preferable since they easily satisfy the above ranges.

In addition, in order to improve the adhesion of a release layer or the like to be applied later and 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 in the film-forming step or after uniaxial stretching, or corona treatment or the like may be performed.

(Structure of Release layer)

The release layer in the present invention is preferably obtained by curing a composition containing at least a melamine compound and a carboxyl group-containing polyorganosiloxane. Other components than the above-described resins and additives may be added within the range not to impair the effects of the present invention.

The melamine compound used in the releasing layer in the present invention may be any one of those generally used, and is not particularly limited, but is preferably one obtained by condensing melamine with formaldehyde and having 1 or more triazine rings and hydroxymethyl groups and/or alkoxymethyl groups in each molecule. Specifically, a methylol melamine derivative obtained by condensing melamine with formaldehyde is preferably etherified by a dehydration condensation reaction with a lower alcohol such as methanol, ethanol, isopropanol, or butanol. Examples of the methylolated melamine derivative include monomethylolmelamine, dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylmelamine, and hexamethylolmelamine. One kind or two or more kinds may be used.

In order to suppress deformation of the release layer occurring at the time of peeling and to make the peeling force low and uniform, the release layer in the present invention is preferably high in crosslinking density and high in elastic modulus. Therefore, hexamethylolmelamine and hexaalkoxymethylmelamine having more crosslinking points in 1 molecule are preferably used, hexaalkoxymethylmelamine having more excellent reactivity is more preferred, and hexamethoxymethylmelamine is particularly preferred. In this case, hexamethylol melamine means that X in the following formula (a) is a methylol group (-CH) ₂ -OH). Hexaalkoxymethyl melamine is obtained by dehydrating condensation of a methylol melamine derivative with an alcohol, and X is (-CH) ₂ -OR), R is alkyl with 1-4 carbon atoms. Hexamethoxymethyl groupMelamine means that X is (-CH) ₂ -OMe).

X in the above (a) may be the same or different. The above-mentioned R may be the same or different. In addition, X may be (-H).

In the melamine compound used in the release layer in the present invention, the weight average molecular weight is preferably 250 or more and 1000 or less. The weight average molecular weight is more preferably 250 to 900 inclusive, and still more preferably 300 to 800 inclusive. When the weight average molecular weight is 1000 or less, the crosslinking reaction is easily progressed, a film having a higher crosslinking density can be formed, and the peeling force can be reduced, which is preferable. When the weight average molecular weight is 250 or more, the crosslinking density is not excessively high and the curl is not deteriorated, which is preferable. The weight average molecular weight in the present specification is a value in terms of standard polystyrene measured by a Gel Permeation Chromatography (GPC) method.

The weight average molecular weight of the melamine-based compound is 250 to 1000, which means that the melamine-based compound used in the present invention contains many mononuclear bodies. Since the single core bodies have more crosslinking points and are more reactive than the multi-core bodies obtained by condensing 2 or more melamine derivatives, a release layer having a high crosslinking density and excellent releasability can be obtained. The more the content of the monokaryon is, the more preferable, and the melamine-based compound formed only from the monokaryon is most preferably used.

The weight average molecular weight can be expressed as a weight average degree of polymerization. The weight-average degree of polymerization of the melamine compound to be used is preferably 2.0 or less, more preferably 1.5 or less, and the smaller the weight-average degree of polymerization, the more suitable the smaller the weight-average degree of polymerization. When the weight-average degree of polymerization is 2.0 or less, the content of the mononuclear bodies contained in the melamine compound increases, and a release layer having excellent reactivity and releasability can be formed. The weight-average degree of polymerization in the present specification is a value calculated based on a weight-average molecular weight determined by gel permeation chromatography in terms of standard polystyrene.

The melamine compound contains amino (-NH) groups during its synthesis ₂ -) or a multikaryon. Even when these melamine derivatives are mixed, the reactivity is excellent as long as the weight-average degree of polymerization of the melamine compound is within the above range, and each of these melamine derivatives can be suitably used.

In the release layer of the present invention, the melamine compound is contained in an amount of preferably 80 mass% to 99.9 mass%, more preferably 90 mass% to 99.9 mass%, and still more preferably 95 mass% to 99.9 mass%, based on the solid content of the release layer forming composition. By containing 80 mass% or more of the melamine compound, the releasing layer can be crosslinked by itself of the melamine compound to obtain a high crosslinking density, and the deformation of the releasing layer at the time of peeling can be suppressed. In this case, since the solvent and the acid catalyst are evaporated in a considerable portion during the drying process, the solid content of the release layer forming composition can be regarded as the total of the solid content of the melamine compound and the solid content of the release agent.

In the release layer of the present invention, in order to promote the crosslinking reaction of the melamine compound, it is preferable to add an acid catalyst, and it is preferable to add an acid catalyst to the release layer-forming composition and coat and cure the composition. The acid catalyst to be used is not particularly limited, and a known acid catalyst may be used, and a sulfonic acid-based catalyst is preferably used.

As the sulfonic acid-based catalyst, for example, p-toluenesulfonic acid, xylenesulfonic acid, isopropyl benzenesulfonate, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, trifluoromethanesulfonic acid and the like can be suitably used, and from the viewpoint of reactivity, p-toluenesulfonic acid can be particularly suitably used.

The sulfonic acid-based catalyst used in the present invention may be a commercially available one. Examples of commercially available products include Dryer (registered trademark) 900 (p-toluenesulfonic acid, manufactured by Hitachi chemical Co., ltd.), NACURE (registered trademark) DNNDSA series (dinonylnaphthalene disulfonic acid, manufactured by Naben chemical Co., ltd.), the same DNNSA series (dinonylnaphthalene (mono) sulfonic acid, manufactured by Naben chemical Co., ltd.), the same DDBSA series (dodecylbenzenesulfonic acid, manufactured by Naben chemical Co., ltd.), the same p-TSA series (p-toluenesulfonic acid, manufactured by Naben chemical Co., ltd.), and the like.

The sulfonic acid-based catalyst has higher acidity and better reactivity than other acid catalysts such as carboxylic acid-based catalysts, and therefore can process the release layer at a lower temperature. Therefore, it is preferable to suppress the reduction in the flatness of the film and the deterioration in the roll appearance due to heat during processing.

The amount of the acid catalyst added is preferably 0.1 to 10% by mass based on the melamine compound contained in the release layer. More preferably 0.5 to 8 mass%. More preferably 0.5 to 5% by mass. When the content is 0.1% by mass or more, the curing reaction is easily progressed, and therefore, it is preferable. On the other hand, when the amount is 10% by mass or less, there is no concern that the acid catalyst will migrate to the molded ceramic green sheet and no concern that the acid catalyst will adversely affect the molded ceramic green sheet, and therefore, it is preferable.

As the release agent (additive for improving the releasability of the release layer) used in the release layer of the present invention, a carboxyl group-containing polyorganosiloxane is preferably used from the viewpoint of achieving both the releasability and the suppression of the amount of transfer. Among the polyorganosiloxane structures, carboxyl group-containing polyorganosiloxanes having a polydimethylsiloxane structure (abbreviated as PDMS) can be suitably used.

When the polyorganosiloxane as the release agent contains a carboxyl group, the release agent exhibits strong interaction with the melamine compound in the drying step, and the surface of the release layer becomes easily oriented, whereby good releasability can be obtained. Therefore, the use of a carboxyl group-containing polyorganosiloxane is preferable because the releasability can be satisfied even when the amount of the release agent to be added is small. Further, when the polyorganosiloxane as the release agent contains a carboxyl group, it is known that transfer to the ceramic green sheet is not easily caused because it shows a weak interaction with the melamine compound, and therefore, it is preferable.

The carboxyl group may be introduced at one end of the polyorganosiloxane, or may be introduced at both ends or a side chain, and is preferable because it is excellent in releasability when introduced at one end. The number of introduction positions may be 1 or more.

The carboxyl group-modified polyorganosiloxane may be one in which a carboxyl group is directly bonded to a silicon atom of the polyorganosiloxane, or one in which a carboxyl group is bonded to the polyorganosiloxane via an alkyl group or an aryl group. However, those having carboxyl groups bonded to polyorganosiloxane via an organic group having a repeating structure of polyether, polyester, polyurethane or the like are hardly preferred.

The functional group introduced into the polyorganosiloxane as the release agent may have a functional group other than a carboxyl group in 1 molecule, and preferably has only a carboxyl group. When a functional group other than a carboxyl group is contained, the intermolecular interaction of the melamine compound becomes necessary or more, and it may become difficult to align the melamine compound on the surface of the release layer, which is not preferable.

Since the polyorganosiloxane modified with a hydroxyl group or the like which strongly interacts with the melamine compound rapidly reacts with the melamine compound in the drying step, it is difficult to orient the polyorganosiloxane on the surface of the release layer, and it is sometimes difficult to exhibit releasability. Therefore, in order to provide sufficient releasability, it is necessary to increase the amount of addition, and at this time, the elastic modulus of the release layer decreases, and the release layer is likely to be deformed at the time of peeling, and the peeling force may increase. Further, when the amount of polyorganosiloxane to be added is increased, the amount of transfer to the ceramic green sheet tends to be increased, which is not preferable.

The molecular weight of the carboxyl group-containing polyorganosiloxane used in the present invention is preferably 40000 or less. More preferably 30000 or less, still more preferably 10000 or less, and the smaller the molecular weight, the more suitable the use is. When the molecular weight is 40000 or less, the carboxyl group-containing polyorganosiloxane is easily segregated on the surface of the release layer, and the releasability is good, so that it is preferable.

As described above, the carboxyl group-containing polyorganosiloxane is more preferably carboxyl group-containing polydimethylsiloxane. Examples of the carboxyl group-containing polydimethylsiloxane include X22-3701E (side chain carboxyl group-modified polydimethylsiloxane, available from shin-Etsu chemical Co., ltd.), X22-3710 (one-terminal carboxyl group-modified polydimethylsiloxane, available from shin-Etsu chemical Co., ltd.), X22-162C (both-terminal carboxyl group-modified polydimethylsiloxane, available from shin-Etsu chemical Co., ltd.), BY16-750 (both-terminal carboxyl group-modified polydimethylsiloxane, available from Dow Corning Toray Co., ltd.), BY16-880 (side chain carboxyl group-modified polydimethylsiloxane, available from Dow Corning Toray Co., ltd.), magnasoft 800L (both-terminal carboxyl group-modified polydimethylsiloxane, available from Moivement Co., ltd.), and the like.

The carboxyl group-containing polydimethylsiloxane in the present invention may be an acrylic resin obtained by introducing polydimethylsiloxane into a side chain of a carboxyl group-containing acrylic main chain. As the acrylic resin obtained by introducing polydimethylsiloxane into a side chain of an acrylic main chain having a carboxyl group, SYMAC (registered trademark) US-350, US-352, US-380 (manufactured by Toyo Seisakusho Co., ltd.) and the like can be used. Further, the acrylic resin may be one in which polydimethylsiloxane is introduced into a side chain of an acrylic main chain having a carboxyl group and a hydroxyl group in one molecule. As the acrylic resin obtained by introducing polydimethylsiloxane into a side chain of an acrylic main chain having a carboxyl group and a hydroxyl group in one molecule, SYMAC (registered trademark) US-450, US-480 (manufactured by Toyo Kabushiki Kaisha, supra) and the like can be used.

In the release layer of the present invention, the release agent is preferably contained in an amount of 0.1 mass% or more and 20 mass% or less with respect to the solid content of the composition for forming the release layer. More preferably 0.1 to 10 mass%, and still more preferably 0.1 to 5 mass%. When the content is 0.1% by mass or more, the releasability is improved and the releasability of the ceramic green sheet is improved, which is preferable. On the other hand, 20 mass% or less is preferable because the modulus of elasticity of the release layer does not decrease excessively, and the peeling force due to the deformation of the release layer occurring when the ceramic green sheet is peeled can be suppressed from increasing. In addition, when 20 mass% or less, the amount of the release agent transferred is preferably not too high. In this case, since the solvent and the acid catalyst are evaporated in a considerable portion during the drying process, the solid content of the release layer forming composition can be regarded as the total of the solid content of the melamine compound and the solid content of the release agent.

The release layer in the present invention may contain particles having a particle diameter of 1 μm or less, and preferably does not contain particles or the like to form protrusions from the viewpoint of pinhole generation.

In the release layer of the present invention, additives such as adhesion improving agents and antistatic agents may be added within a range not to impair the effects of the present invention. In order to improve the adhesion of the base material, it is preferable to subject the surface of the polyester film to pretreatment such as anchor coating agent application, corona treatment, plasma treatment, atmospheric pressure plasma treatment, or the like before providing the release coating layer.

(characteristics of Release layer)

In the present invention, the thickness of the release layer may be set according to the purpose of use thereof, and is not particularly limited, and the thickness of the release coating layer after curing is preferably in the range of 0.01 to 2.0. Mu.m, more preferably 0.01 to 1.0. Mu.m, further preferably 0.01 to 0.8. Mu.m, further preferably 0.02 to 0.5. Mu.m, and most preferably 0.02 to 0.3. Mu.m. The thickness of the release layer is preferably 0.01 μm or more because the release performance can be obtained. Further, a thickness of 2.0 μm or less is preferred because the curing time can be shortened, the planarity of the release film can be ensured, and the thickness unevenness of the ceramic green sheet can be suppressed.

The release layer surface of the release film of the present invention is preferably flat so as not to cause defects in the ceramic green sheet coated and molded thereon, and preferably has a region surface average roughness (Sa) of 7nm or less and a maximum protrusion height (P) of 100nm or less. Further, it is more preferable that the area surface average roughness is 5nm or less and the maximum protrusion height is 80nm or less. When the area surface roughness is 7nm or less and the maximum protrusion height is 100nm or less, defects such as pinholes are not generated at the time of forming the ceramic green sheet, and the yield is good, so that it is preferable. The smaller the area surface average roughness (Sa), the more preferable, but the smaller the area surface average roughness (Sa), the smaller the area surface average roughness (Sa) may be 0.1nm or more, or 0.3nm or more. The maximum protrusion height (P) is preferably smaller, but may be 1nm or more, or may be 3nm or more.

Since the release film of the present invention uses a highly planarized base film, the surface of the release layer can be made smooth even if the thickness of the release layer is smaller than 0.5 μm, and further smaller than 0.2 μm. Therefore, even when a release layer of a melamine compound having high reactivity is used, occurrence of curling can be suppressed. In addition, the amount of solvent and resin used can be reduced, so that the release film for forming ultrathin ceramic green sheets can be produced at low cost and in an environment-friendly manner.

The surface free energy (. Gamma.s) of the surface of the release layer film of the present invention is preferably 18mJ/m ² Above and 35mJ/m ² The following. More preferably 23mJ/m ² Above and 35mJ/m ² Hereinafter, it is more preferably 23mJ/m ² Above and 30mJ/m ² The following. Is 18mJ/m ² In the above case, it is preferable that the ceramic slurry is applied because the ceramic slurry is less likely to shrink and can be uniformly applied. In addition, 35mJ/m ² The following is preferable because the releasability of the ceramic green sheet is not likely to be deteriorated. By setting the above range, a release film having no shrinkage at the time of coating and excellent releasability can be provided.

In the release film of the present invention, the peeling force at the time of peeling the ceramic green sheet is preferably 0.5mN/mm ² Above and 2.5mN/mm ² The following. More preferably 0.8mN/mm ² 2.0mN/mm or more ² The following. The peel force was 0.5mN/mm ² The above is preferable because the peeling force is not too low and there is no fear that the ceramic green sheet floats during conveyance. The peel force was 2.5mN/mm ² The following is preferable because the ceramic green sheet is not likely to be damaged during peeling.

The release film of the present invention preferably has a curl of 3mm or less, more preferably 1mm or less, after heating at 100 ℃ for 15 minutes without applying a tension. Of course, it is preferable that no curling occurs at all. When the thickness is 3mm or less, curling is reduced and printing accuracy can be improved when the ceramic green sheet is molded and an electrode is printed, which is preferable.

The release film of the present invention is more preferable as the amount of silicone component transferred to the ceramic green sheet after peeling is smaller. The amount of silicone component transferred was evaluated by pseudo-coating 1 PVB, which was the binder component contained in the ceramic green sheet, on a release film, molding, and measuring the Si strength of the release layer before and after peeling with fluorescent X-rays. More specifically, when Si (front) is the Si strength of the surface of the release layer and Si (rear) is the Si strength of the release surface of the release film after the PVB sheet is coated/peeled, the Si (front) -Si (rear) value is used as the transfer amount. The amount of transfer at this time is preferably 0.10kcps or less, more preferably 0.04kcps or less. When the transfer amount is 0.10kcps or less, occurrence of process defects such as lamination shift and adhesion failure is suppressed, and there is no concern of lowering the reliability of the ceramic capacitor, so that it is preferable.

In the present invention, the method for forming the release layer is not particularly limited, and the following methods can be used: a coating liquid in which a mold-releasable resin is dissolved or dispersed is spread on one surface of the polyester film of the substrate by coating or the like, and after the solvent or the like is removed by drying, it is heated, dried, and thermally cured. In this case, the drying temperature at the time of solvent drying and thermosetting is preferably 100 ℃ to 180 ℃, more preferably 100 ℃ to 160 ℃, and most preferably 100 ℃ to 140 ℃. The heating time is preferably 30 seconds or less, and more preferably 20 seconds or less. When the temperature is 180 ℃ or lower, the flatness of the film is protected, and the thickness of the ceramic green sheet is less likely to be uneven, so that the temperature is preferable. The temperature of 140 ℃ or lower is particularly preferable because the processing can be performed without impairing the flatness of the thin film and the possibility of causing thickness unevenness of the ceramic green sheet is further reduced. If the temperature is less than 100 ℃, the curing reaction of melamine does not proceed sufficiently, and the modulus of elasticity of the release layer is undesirably lowered.

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

In the present invention, the coating liquid used for applying the release coating layer is not particularly limited, and a solvent having a boiling point of 90 ℃ or higher is preferably added. By adding a solvent having a boiling point of 90 ℃ or higher, bumping during drying can be prevented, the coating film can be leveled, and the smoothness of the surface of the coating film after drying can be improved. The amount of addition is preferably about 10 to 80% by mass based on the entire coating liquid.

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

(ceramic green sheet and ceramic capacitor)

Generally, a laminated ceramic capacitor has a rectangular parallelepiped ceramic body. Inside the ceramic body, the 1 st internal electrode and the 2 nd internal electrode are alternately arranged in the thickness direction. The 1 st internal electrode is exposed at the 1 st end surface of the ceramic body. A1 st external electrode is provided on the 1 st end face. The 1 st internal electrode is electrically connected to the 1 st external electrode at the 1 st end face. The 2 nd internal electrode is exposed at the 2 nd end surface of the ceramic body. A2 nd external electrode is provided on the 2 nd end face. The 2 nd internal electrode is electrically connected to the 2 nd external electrode at the 2 nd end face.

The release film for producing a ceramic green sheet of the present invention can be used for producing such a multilayer ceramic capacitor. For example, it can be manufactured in the following manner. First, a ceramic slurry for forming a ceramic body is applied to a release film of the present invention as a carrier film and dried. The thickness of the ceramic green sheet is required to be extremely thin, i.e., 0.2 to 1.0 μm. On the ceramic green sheet subjected to coating and drying, a conductive layer for constituting the 1 st or 2 nd internal electrode was printed. The ceramic green sheet, the ceramic green sheet on which the conductive layer for constituting the 1 st internal electrode is printed, and the ceramic green sheet on which the conductive layer for constituting the 2 nd internal electrode is printed are appropriately laminated, and pressed to obtain a mother laminate. The mother laminate is divided into a plurality of pieces to produce a green ceramic body. The ceramic body is obtained by firing a green ceramic body. After that, the 1 st and 2 nd external electrodes are formed to complete the multilayer ceramic capacitor.

Examples

The present invention will be described in further detail with reference to examples below, but the present invention is not limited to these examples. The characteristic values used in the present invention were evaluated by the following methods.

(surface roughness)

The measured value was measured under the following conditions using a non-contact surface shape measuring system (VertScan R550H-M100). The area surface average roughness (Sa) was measured by taking the average of 5 measurements, the maximum protrusion height (P) was measured 7 times, the maximum value and the minimum value were removed, and the maximum value of 5 times was used.

(measurement conditions)

Measurement mode: WAVE mode

Objective lens: 10 times of

0.5 × Tube lens

Measurement area 936. Mu. M.times.702. Mu.m

(analysis conditions)

Surface correction: 4 times correction

Interpolation processing: full interpolation

(surface free energy)

A droplet of water (droplet amount: 1.8. Mu.L), diiodomethane (droplet amount: 0.9. Mu.L) and ethylene glycol (droplet amount: 0.9. Mu.L) was formed on the release surface of the release film by using a contact angle meter (manufactured by Nippon Kogyo Co., ltd.: full-automatic contact angle meter, DM-701) under conditions of 25 ℃ and 50% RH, and the contact angle thereof was measured. The contact angle was measured after 10 seconds after each droplet was applied to the release film. The contact angle data of water, diiodomethane and ethylene glycol obtained by the above method was calculated by the theory of "hogasaki-u-zuku", and the dispersed component γ sd, polar component γ sp and hydrogen bond component γ sh of the surface free energy of the release film were obtained, and the total value of the components was defined as the surface free energy γ s. This calculation is performed using calculation software in the contact angle measuring software (FAMAS).

(evaluation of coating Property of ceramic slurry)

A composition comprising the following materials was stirred and mixed, and dispersed for 30 minutes using a bead mill using zirconia beads having a diameter of 0.5mm to obtain a ceramic slurry.

Then, the release surface of the obtained release film sample was coated with a coater so that the dried slurry became 1 μm, and after drying at 90 ℃ for 1 minute, the coating property was evaluated in accordance with the following criteria.

O: the entire surface may be coated without shrinkage or the like.

And (delta): the coated end is slightly constricted but substantially the entire surface can be coated.

X: the shrinkage was large and the coating was not performed.

(pinhole evaluation of ceramic Green sheet)

As in the evaluation of the coatability of the ceramic slurry, a ceramic green sheet having a thickness of 1 μm was formed on the release surface of the release film. Then, the release film was peeled from the release film with the molded ceramic green sheet to obtain a ceramic green sheet. In the central region of the obtained ceramic green sheet in the film width direction of 25cm ² In a state where light is irradiated from the side opposite to the applied side of the ceramic slurry, and visible pinholes are generated by observing light transmission, the evaluation was made by visual observation according to the following criteria.

O: no generation of pin holes

And (delta): substantially free from generation of pinholes

X: the generation of pinholes is large

(evaluation of releasability of ceramic green sheet)

A composition comprising the following materials was stirred and mixed, and dispersed for 60 minutes using a bead mill using zirconia beads having a diameter of 0.5mm to obtain a ceramic slurry.

Then, the release surface of the obtained release film sample was coated with a dried slurry using an applicator so that the thickness of the slurry was 10 μm, and the slurry was dried at 90 ℃ for 1 minute to mold a ceramic green sheet on the release film. The obtained release film with a ceramic green sheet was subjected to static elimination using a static elimination machine (SJ-F020, manufactured by Keyence corporation), and then peeled at a peeling angle of 90 degrees and a peeling speed of 10 m/min with a width of 30 mm. The stress required for peeling was measured and used as the peeling force. The obtained value of the peeling force was determined according to the following criteria.

○：0.5mN/mm ² Above and 2.0mN/mm ² The following

And (delta): greater than 2.0mN/mm ² And 2.5mN/mm ² The following

X: greater than 2.5mN/mm ²

(evaluation of the amount of Silicone component transferred to the Release layer)

A composition comprising the following materials was mixed with stirring to obtain a polyvinyl butyral (PVB) solution.

45.0 parts by mass of toluene

45.0 parts by mass of ethanol

Polyvinyl butyral (S-LEC BM-S, waterlogging chemical Co., ltd.) 10.0 part by mass

Then, the release surface of the obtained release film sample was coated with a polyvinyl butyral (PVB) sheet having a thickness of 10 μm by using an applicator, the release film was peeled off after drying at 90 ℃ for 1 minute, and the Si strength of the surface (release layer) of the peeled PVB sheet in contact with the release film and the release layer of the release film before coating the PVB sheet was measured by a fluorescent X-ray apparatus (zsxprimus 2 manufactured by Rigaku) to determine the amount of transfer of the silicone component. The measurement conditions of the fluorescent X-ray apparatus are as follows.

And (3) analyzing rays: si-KA, target: rh4.0kW

Tube voltage: 50kV, tube current: 60mA

A filter: OUT, attenuator: 1/1, slit: s4, spectroscopic crystal: PET

A detector: PC and PHA conditions: 100 (lower limit) -300 (upper limit)

And (3) measuring the diameter: 30mm, atmosphere: vacuum

The amount of silicone component transferred was determined by subtracting Si (rear) from Si (front) where Si (front) is the Si strength of the release surface of the release film before coating the PVB sheet and Si (rear) where Si (rear) is the Si strength of the release surface of the release film after coating/peeling the PVB sheet. The transfer amount of the silicone component obtained was evaluated based on the following criteria.

O: less than 0.04kcps

And (delta): greater than 0.04kcps and less than 0.10kcps.

X: more than 0.10kcps

(curl evaluation of Release film)

The sample of the release film was cut into a size of 10cm × 10cm, and heat-treated with a hot air oven at 100 ℃ for 15 minutes in such a manner that no tension was applied to the release film. After that, the glass plate was taken out from the oven and cooled to room temperature, and then a release film sample was placed on the glass plate with the release surface facing upward, and the height of the portion floating from the glass plate at the 4-corner was measured. The average value of the floating amounts at 4 angles measured at this time was defined as the curl amount. The curling properties were evaluated according to the following criteria.

Very good: the crimp is 1mm or less and almost no crimp

O: the curl was more than 1mm and 3mm or less, and a small amount of curl was observed.

And (delta): the curl was larger than 3mm and 10mm or less, and the curl was observed.

X: the curl was greater than 10mm and the curl occurred.

(method of measuring weight-average polymerization degree)

Conditions of analysis

A sample (16 mg) was weighed and dissolved in chloroform (8 ml). The sample solution was filtered through a 0.2 μm membrane filter, and Gel Permeation Chromatography (GPC) analysis of the obtained sample solution was performed under the following conditions.

The device comprises the following steps: TOSOH HLC-8320GPC

Column: K-G + K-802 (exclusion limit molecular weight 5X 10) ³ ) + K-801 (exclusion limit molecular weight 1.5X 10) ³ )(Shodex)、

Solvent: 100% of chloroform

Flow rate: 1.0 ml/min

Concentration: 0.2 percent of

Injection amount: 50 μ L

Temperature: 40 deg.C

A detector: RI (Ri)

The weight average molecular weight was calculated in terms of polystyrene, and the weight average polymerization degree was calculated based on the weight average molecular weight. Polystyrene PStQuick C (TOSOH) of the PStQuick series was used. Among the polystyrenes with PStQuick C (TOSOH) added, the polystyrenes Mw2110000, 427000, 37900 regarding the exclusion limit molecular weight of the far-exceeding column were removed from the standard curve preparation.

(production of polyethylene terephthalate pellets (PET (I))

As the esterification reaction apparatus, a continuous esterification reaction apparatus comprising a 3-stage complete mixing tank having a stirring apparatus, a partial condenser, a raw material inlet and a product outlet was used. TPA (terephthalic acid) was set to 2 tons/hr, EG (ethylene glycol) was set to 2 moles per 1 mole of TPA, and antimony trioxide was set to an amount of 160ppm per atom of PET or Sb produced, and these slurries were continuously supplied to the 1 st esterification reaction tank of the esterification reaction apparatus, and reacted at 255 ℃ with an average residence time of 4 hours under normal pressure. Then, the reaction product in the 1 st esterification reaction tank was continuously taken out of the system and supplied to the 2 nd esterification reaction tank, 8 mass% of EG distilled off from the 1 st esterification reaction tank was supplied to the produced PET in the 2 nd esterification reaction tank, and an EG solution containing magnesium acetate tetrahydrate salt in an amount of 65ppm as an Mg atom to the produced PET and an EG solution containing TMPA (trimethyl phosphate) in an amount of 40ppm as a P atom to the produced PET were further added, and the reaction was carried out at an average residence time of 1 hour and 260 ℃ under normal pressure. Next, the reaction product in the 2 nd esterification reaction tank was continuously taken out of the system and supplied to the 3 rd esterification reaction tank, and the reaction product was dispersed by a high pressure disperser (manufactured by Nippon Seiko Co., ltd.) at 39MPa (400 kg/cm) ² ) 0.2 mass% of porous colloidal silica having an average particle diameter of 0.9 μm obtained by dispersion treatment with an average treatment frequency of 5 times (pass) and 0.4 mass% of synthetic calcium carbonate having an average particle diameter of 0.6 μm and having 1 mass% of an ammonium salt of polyacrylic acid attached to the calcium carbonate unit were added as 10% EG slurry, and the reaction was carried out at 260 ℃ for an average residence time of 0.5 hour under normal pressure. Continuously feeding the esterification reaction product generated in the 3 rd esterification reaction tank to a 3-stage continuous polycondensation reaction apparatus, polycondensing the esterification reaction product, and burning the esterification reaction productAfter filtration through a filter having 95% of stainless steel fibers having a diameter of 20 μm, the resulting mixture was ultrafiltered, extruded in water, cooled, and cut into small pieces (chips) to obtain PET chips having an intrinsic viscosity of 0.60dl/g (hereinafter, abbreviated as PET (I)). The content of the lubricant in the PET chips was 0.6 mass%.

(production of polyethylene terephthalate pellets (PET (II))

On the other hand, in the production of the above PET (I) chips, PET chips having an intrinsic viscosity of 0.62dl/g (hereinafter referred to as PET (II)) containing no particles such as calcium carbonate and silica are obtained.

(production of polyethylene terephthalate pellets (PET (III))

The type and content of the PET (I) particles were changed to: PET chips (hereinafter referred to as PET (III)) were obtained in the same manner as PET (I) except that 0.75 mass% of synthetic calcium carbonate having an average particle diameter of 0.9 μm, in which 1 mass% of ammonium salt of polyacrylic acid was attached per unit of calcium carbonate. The content of the lubricant in the PET chips was 0.75 mass%.

(production of laminated film X1)

These PET chips were dried, melted at 285 ℃, melted at 290 ℃ by a separate melt extruder, 2-stage filtration of a filter sintered with 95% of stainless steel fibers having a cut diameter of 15 μm and a filter sintered with 95% of stainless steel particles having a cut diameter of 15 μm was performed, and the two were combined in a feed block (feed block) so that PET (I) became a surface layer B (reverse release surface side layer) and PET (II) became a surface layer a (release surface side layer), and extruded (cast) at a speed of 45 m/min into a sheet form, and electrostatically bonded and cooled on a casting drum at 30 ℃ by an electrostatic bonding method to obtain an unstretched polyethylene terephthalate sheet having an intrinsic viscosity of 0.59 dl/g. The layer ratio was adjusted so that PET (I)/(II) =60 mass%/40 mass% by calculation according to the discharge amount of each extruder. Subsequently, the unstretched sheet was heated by an infrared heater and then stretched 3.5 times in the machine direction at a roll temperature of 80 ℃ by the speed difference between rolls. Thereafter, the resultant was introduced into a tenter and stretched 4.2 times in the transverse direction at 140 ℃. Subsequently, heat treatment was performed at 210 ℃ in the heat-set region. Thereafter, a 2.3% relaxation treatment was performed at 170 ℃ in the transverse direction to obtain a biaxially stretched polyethylene terephthalate film X1 having a thickness of 31 μm. The Sa of the surface layer A and the Sa of the surface layer B of the obtained film X1 were 2nm and 28nm, respectively.

(production of laminated film X2)

The thickness of the biaxially stretched polyethylene terephthalate film X2 was adjusted by changing the casting speed without changing the layer composition and stretching conditions similar to those of the laminated film X1, and a thickness of 25 μm was obtained. The Sa of the surface layer A and the Sa of the surface layer B of the obtained film X2 were 3nm and 29nm, respectively.

(laminated film X3)

A4100 (COSMOSHINE (registered trademark), toyo Co., ltd.) having a thickness of 25 μm was used as the laminated film X3. A4100 is substantially free of particles in the thin film, and is configured such that a coating layer containing particles is provided on the surface layer B side by in-line coating (Inline coat). The Sa of the surface layer A of the laminated film X3 was 1nm, and the Sa of the surface layer B was 2nm.

(laminated film X4)

E5101 (Toyobo ester (registered trademark) film, manufactured by Toyo Boseki Co., ltd.) having a thickness of 25 μm was used as the laminated film X4. E5101 is a film containing particles. The Sa of the surface layer A of the laminated film X4 was 24nm, and the Sa of the surface layer B was 24nm.

(example 1)

The surface layer a of the laminated film X1 was coated with a coating liquid having the following composition using a reverse gravure printing plate so that the thickness of the release layer after drying became 50nm, and dried at 140 ℃ for 15 seconds to obtain a release film for producing an ultrathin ceramic green sheet. The ceramic slurry was coated on the obtained release film, and coatability, releasability, transfer amount of silicone component, pin hole, curl and the like were evaluated, and good evaluation results were obtained.

(example 2)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1 except that the coating liquid in example 1 was used in which the content of the all-ether methylated melamine in the coating liquid was changed to 0.98 parts by mass and the amount of the release agent (X22-3710) added was changed to 0.02 parts by mass.

(example 3)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1 except that the coating liquid in example 1 was used in which the content of the all-ether methylated melamine in the coating liquid in example 1 was changed to 0.9 parts by mass and the amount of the release agent (X22-3710) added was changed to 0.1 parts by mass.

(example 4)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1 except that the coating liquid in example 1 was used in which the content of the all-ether methylated melamine in the coating liquid was changed to 0.8 parts by mass and the amount of the release agent (X22-3710) added was changed to 0.2 parts by mass.

(examples 5 to 8)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the film thickness of the release layer in example 1 was changed to the film thickness described in table 1.

(example 9)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the base film in example 1 was changed to a laminated film X2 having a film thickness of 25 μm.

(example 10)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the laminated film of example 1 was changed to the laminated film X3.

(example 11)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the drying conditions in example 1 were changed to 90 ℃ for 15 seconds.

(example 12)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the drying conditions in example 1 were changed to 110 ℃ for 15 seconds.

(example 13)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1 except that the release agent in example 1 was changed to a coating solution of X22-3701E (side chain carboxyl-modified polydimethylsiloxane, manufactured by shin-Etsu chemical Co., ltd.).

(example 14)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1 except that the release agent in example 1 was changed to a coating solution of X22-162C (both-terminal carboxyl-modified polydimethylsiloxane, manufactured by shin-Etsu chemical Co., ltd.).

(example 15)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1 except that the coating liquid obtained in example 1 was changed from the full ether type methylated melamine to MW-30 (full ether type methylated melamine, SANWA Chemical Co., ltd., weight-average degree of polymerization of 1.5 manufactured by Ltd.).

(example 16)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1 except that the entirely ether-type methylated melamine in example 1 was changed to a coating liquid of MS-21 (entirely ether-type methylated melamine, SANWA Chemical co., ltd, product, weight-average degree of polymerization of 1.8).

(example 17)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1 except that the full-ether methylated melamine in example 1 was changed to MX-730 (amino methylated melamine, 80% of solid content, SANWA Chemical co., ltd, and weight-average degree of polymerization of 2.4).

Comparative example 1

A release film for producing an ultra-thin ceramic sheet was obtained in the same manner as in example 1, except that a coating solution to which no release agent was added was used for the coating layer in example 1. Since no release agent was added, the peeling force became strong.

Comparative example 2

A release film for producing an ultra-thin ceramic sheet was obtained in the same manner as in example 1, except that the laminated film X1 was changed to the laminated film X4 (E5101-25 μm, manufactured by Toyo Boseki Co., ltd.). Both the surface layer a and the surface layer B of E5101 contain particles, and both the surface layer a and the surface layer B have a Sa of 24nm. Due to the large surface roughness, pinholes are produced on the ceramic green sheet.

Comparative example 3

A release film for producing an ultrathin ceramic sheet was obtained in the same manner as in example 1, except that the coating liquid was changed to a coating liquid having the following composition. In comparative example 3 in which a large amount of the release agent was added and the melamine compound was 70 mass% of the release layer, the amount of PDMS transferred to the ceramic green sheet was increased.

Comparative example 4

A release film for producing an ultrathin ceramic sheet was obtained in the same manner as in example 1, except that the coating liquid was changed to a coating liquid having the following composition. BYK-370 is a polydimethylsiloxane having 2 functional groups (ester and hydroxyl) in 1 molecule. The transfer amount of PDMS is low and good, but the interaction between the hydroxyl group and the melamine compound is strong, so that PDMS is not transferred to the surface and the peeling force is strong.

Comparative example 5

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the release agent in example 1 was changed to a coating solution of one-terminal epoxy-modified polydimethylsiloxane (X22-173 DX, manufactured by shin-Etsu chemical Co., ltd.). The interaction between the melamine compound and the epoxy group is weak, and the transfer amount of PDMS increases.

Comparative example 6

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the release agent in example 1 was changed to a coating solution of single-terminal hydroxyl-modified polydimethylsiloxane (X22-170 DX, manufactured by shin-Etsu chemical Co., ltd.). The transfer amount of PDMS was low and good, but since the interaction between the carbinol group and the melamine compound was strong, PDMS was not transferred to the surface, and the peeling force was strong.

Comparative example 7

A release film for producing an ultrathin ceramic sheet was obtained in the same manner as in example 1, except that the coating liquid was changed to a coating liquid having the following composition. The transfer amount of PDMS was low and good, but the interaction between the hydroxyl group and the melamine compound was strong, so that PDMS was not transferred to the surface, and the peeling force was strong.

Comparative example 8

A release film for producing an ultrathin ceramic sheet was obtained in the same manner as in example 1, except that the coating liquid was changed to a coating liquid having the following composition. The transfer amount of PDMS is low and good, but the interaction between the hydroxyl group and the melamine compound is strong, so that PDMS is not transferred to the surface and the peeling force is strong.

[ Table 1]

[ Table 2]

Industrial applicability

According to the present invention, an ultra-thin ceramic green sheet having a release layer with a smooth surface, which is substantially free from defects such as pinholes and which is less likely to cause polyorganosiloxane transfer than conventional release films for ceramic green sheet production, and which has a thickness of 0.2 to 1.0 μm can be produced.

Claims

1. A release film for producing a ceramic green sheet, comprising a biaxially oriented polyester film as a substrate, at least one surface of the substrate having a surface layer A substantially free of inorganic particles, and a release layer directly laminated on the surface of the surface layer A on at least one surface,

the releasing layer is formed by curing a composition at least comprising a releasing agent and a melamine compound, wherein the releasing agent is carboxyl group-containing polyorganosiloxane, and the content of the melamine compound is 80 mass% or more relative to the solid content of the composition for forming the releasing layer,

the surface free energy (gamma s) of the surface of the release layer is 18mJ/m ² Above and 35mJ/m ² In the following, the following description is given,

the thickness of the demoulding layer is 0.01-0.1 μm.

2. The release film for ceramic green sheet production according to claim 1, wherein the surface free energy (γ s) of the release layer surface is 18mJ/m ² Above and 30mJ/m ² The following.

3. The release film for producing a ceramic green sheet according to claim 1, wherein the surface layer A substantially containing no inorganic particles is provided on one surface of the base material, the surface layer B is provided on the opposite side of the base material from the surface layer A, the surface layer B contains particles, at least a part of the particles are silica particles and/or calcium carbonate particles, and the total content of the particles is 5000 to 15000ppm with respect to the mass of the surface layer B.

4. The release film for producing a ceramic green sheet according to claim 1 or 2, wherein a region surface average roughness (Sa) of a release layer of the release film is 7nm or less, and a maximum protrusion height (P) is 100nm or less.

5. A method for producing a ceramic green sheet, which comprises forming a ceramic green sheet by using the release film for producing a ceramic green sheet according to any one of claims 1 to 4, wherein the formed ceramic green sheet has a thickness of 0.2 to 1.0 μm.

6. A method for producing a ceramic capacitor, which comprises using the method for producing a ceramic green sheet according to claim 5.