CN110997258B - Release film for producing ceramic green sheet - Google Patents

Abstract

[ problem ] to provide: even when the ceramic green sheet is made thin, the excellent release film for producing the ceramic green sheet can achieve both good winding properties and prevention of pinholes, partial thickness unevenness, and the like. [ solution ] A release film for producing a ceramic green sheet, which comprises a polyester film substantially free of inorganic particles as a base material, has a release coating layer on one surface of the base material, has a coating elastic modulus of 2.0GPa or more as measured from the surface of the release coating layer on the side opposite to the base material by a nanoindentation test on the release coating layer, and has an easy-to-slide coating layer containing particles on the other surface of the base material, wherein the area surface average roughness (Sa) of the easy-to-slide coating layer is 1nm to 25nm, the maximum protrusion height (P) is 60nm to 500nm, and the average width (RSm) of profile elements is 10 [ mu ] m or less.

Description

Release film for producing ceramic green sheet

Technical Field

The present invention relates to a release sheet for producing a ceramic green sheet. More specifically, the present invention relates to: even when the ceramic green sheet is made thin, the release film for producing a ceramic green sheet can have good winding properties and can prevent pinholes, partial thickness unevenness, and the like.

Background

Conventionally, the following techniques have been disclosed: by making the surface roughness of the surface (back surface) opposite to the surface of the base film on which the release coating layer is provided thicker, the problem that the surface and back surface of the release film for ceramic green sheet production adhere (block) when the release film for ceramic green sheet production is stored in a wound state is eliminated (for example, see patent document 1). However, the above-described prior art has the following problems: since the projection is large, a pinhole is generated and the thickness of a part is not uniform.

Therefore, in order to reduce the height of the protrusion, the following techniques are disclosed: the projections on the back surface are filled with the coating layer to prevent occurrence of pinholes and partial thickness unevenness in the ceramic green sheet (see, for example, patent document 2). However, according to the above-mentioned conventional technique, since the protrusion height is low but the protrusion density is low, there is a problem that pinholes are generated when the ceramic green sheet is further thinned due to a large pressure applied to the protrusions.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2003-203822

Patent document 2: japanese patent laid-open No. 2014-144636

Disclosure of Invention

Problems to be solved by the invention

The present invention was made in view of the above-mentioned problems of the prior art. That is, an object of the present invention is to provide: even when the ceramic green sheet is made thin, the release film for producing a ceramic green sheet is excellent in winding properties and in preventing pinholes, partial thickness unevenness, and the like.

Means for solving the problems

The present inventors have conducted intensive studies to achieve the above object, and as a result, the present invention has been completed. That is, the present invention includes the following configurations.

1. A release film for producing a ceramic green sheet, which comprises a polyester film substantially free of inorganic particles as a base material, a release coating layer on one surface of the base material, wherein the release coating layer has a film elastic modulus of 2.0GPa or more as measured from the surface of the release coating layer on the side opposite to the base material by a nanoindentation test on the release coating layer, and an easy-to-slide coating layer containing particles on the other surface of the base material, wherein the easy-to-slide coating layer has a regional surface average roughness (Sa) of 1nm to 25nm, a maximum protrusion height (P) of 60nm to 500nm, and an average width of contour elements (RSm, Mean width of the rough profile elements) of 10 [ mu ] m or less.

2. The release film for producing a ceramic green sheet according to the above 1, wherein the area surface average roughness (Sa) of the release coating layer is 5nm or less, and the maximum protrusion height (P) is 30nm or less.

3. The release film for producing a ceramic green sheet according to the above 1 or 2, wherein the thickness of the easy-slip coating layer is 0.001 μm or more and 2 μm or less.

4. A method for producing a ceramic green sheet, which comprises using the release film for producing a ceramic green sheet described in any one of the above items 1 to 3.

5. The method for producing a ceramic green sheet according to the above 4, wherein the thickness of the ceramic green sheet to be produced is 0.2 μm to 2.0 μm.

6. A method for producing a ceramic capacitor, which comprises using the method for producing a ceramic green sheet according to the above 4 or 5.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be provided: even when the ceramic green sheet is made thin, the release film for producing a ceramic green sheet can have good winding properties and can prevent pinholes, partial thickness unevenness, and the like.

Detailed Description

The present invention will be described in detail below.

The release film for producing a ceramic green sheet (hereinafter, may be simply referred to as a release film) of the present invention is a release film having a release coating layer on one surface of a biaxially oriented polyester film as a base film and an easy-to-slide coating layer containing particles on the other surface.

(base film)

The film preferably used as the substrate in the present invention is a film made of a polyester resin, and is preferably a polyester film mainly containing at least 1 selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Further, the polyester film may be a film formed by copolymerizing a third component monomer as a part of the dicarboxylic acid component or the diol component of the above-mentioned polyester. The polyester film is preferably a biaxially oriented polyester film for the reason of high modulus of elasticity in both directions.

The polyester film may be a single layer or a multilayer. In addition, in these layers, various additives may be contained in the polyester resin as necessary as long as the effect of the present invention is exerted. Examples of the additives include antioxidants, light stabilizers, anti-gelling agents, organic wetting agents, antistatic agents, and ultraviolet absorbers.

(easily sliding coating layer)

The release film of the present invention has an easily slidable coating layer on one surface of the polyester base film as described above. The slip-coat layer preferably contains at least a binder resin and particles.

(Binder resin in easy-to-slip coating layer)

The binder resin constituting the slip-resistant coating layer is not particularly limited, and specific examples of the polymer include polyester resins, acrylic resins, urethane resins, polyvinyl resins (e.g., polyvinyl alcohol), polyalkylene glycols, polyalkylene imines, methyl cellulose, hydroxy cellulose, and starches. Among them, polyester resins, acrylic resins, and urethane resins are preferably used from the viewpoint of retention of particles and adhesion. In addition, an acrylic resin is particularly preferable in view of the hardness of the easy-slip coating layer. In addition, as another preferable binder resin constituting the easy-slip coating layer on the polyester base film, polyester resin and urethane resin can be mentioned. As the polyester resin, a copolyester is preferable. The polyester resin may be modified with polyurethane. The urethane resin may be a polycarbonate urethane resin. Further, an acrylic resin, a polyester resin, or a polyurethane resin may be used in combination, or the above-mentioned other binder resins may be used in combination.

(crosslinking agent)

In the present invention, the slip-resistant coating layer may be formed to include a crosslinking agent in order to form a crosslinked structure in the slip-resistant coating layer. By containing a crosslinking agent, the hardness of the slip-resistant coating layer can be further improved. Specific examples of the crosslinking agent include urea-based, epoxy-based, melamine-based, isocyanate-based, oxazoline-based, and carbodiimide-based crosslinking agents. In particular, oxazoline-based or carbodiimide-based crosslinking agents are particularly preferable because the crosslinking density can be improved. In addition, a catalyst or the like may be suitably used as needed to promote the crosslinking reaction.

(particles in easy-slip coating layer)

The slip-resistant coating layer preferably contains lubricant particles for imparting slip properties to the surface. The particles may be inorganic particles or organic particles, and are not particularly limited, and examples thereof include (1) inorganic particles such as silica, kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, zirconium oxide, titanium dioxide, satin white, aluminum silicate, diatomaceous earth, calcium silicate, aluminum hydroxide, halloysite hydrate, calcium carbonate, magnesium carbonate, calcium phosphate, magnesium hydroxide, and barium sulfate; (2) organic particles such as acrylic or methacrylic, vinyl chloride, vinyl acetate, nylon, styrene/acrylic, styrene/butadiene, polystyrene/acrylic, polystyrene/isoprene, methyl methacrylate/butyl methacrylate, melamine, polycarbonate, urea, epoxy, urethane, phenol, diallyl phthalate, and polyester, and silica is particularly preferably used in order to provide a suitable sliding property to the coating layer.

The average particle diameter of the particles is preferably 10nm or more, more preferably 20nm or more, and further preferably 30nm or more. When the average particle diameter of the particles is 10nm or more, aggregation is less likely to occur, and the sliding property can be secured.

The average particle diameter of the particles is preferably 1000nm or less, more preferably 800nm or less, and still more preferably 600nm or less. When the average particle diameter of the particles is 1000nm or less, the transparency can be maintained and the particles are preferably not exfoliated.

For example, when small particles having an average particle diameter of about 10 to 270nm and large particles having an average particle diameter of about 300 to 1000nm are mixed, it is preferable to reduce the average width (RSm) of the contour elements while keeping the area surface average roughness (Sa) and the maximum protrusion height (P) of the easily slippery coating layer, which will be described later, small particles having an average particle diameter of 30nm to 250nm, and large particles having an average particle diameter of 350 to 600nm in combination. When the small particles and the large particles are mixed, the mass content of the small particles is preferably larger than the mass content of the large particles with respect to the entire solid content of the easily slippery coating layer.

The average particle size of the particles was measured as follows: the particles of the cross section of the processed film were observed by a transmission electron microscope or a scanning electron microscope, and 100 particles which were not aggregated were observed, and the average value thereof was taken as the average particle diameter.

The shape of the particles is not particularly limited as long as the object of the present invention is satisfied, and spherical particles and irregular particles other than spherical particles can be used. The particle size of the amorphous particles can be calculated as the circle-equivalent diameter. The circle equivalent diameter is the value obtained by dividing the area of the observed particle by pi, calculating the square root, and forming a factor of 2.

The ratio of the particles to the total solid content of the slip-resistant coating layer is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less. When the ratio of the particles to the entire solid content of the slip-coat layer is 50% by mass or less, the transparency can be maintained and the particles are not significantly peeled off from the slip-coat layer, and therefore, it is preferable.

The ratio of the particles to the total solid content of the slip-resistant coating layer is preferably 1 mass% or more, more preferably 1.5 mass% or more, and still more preferably 2 mass% or more. The ratio of the particles to the entire solid content of the slip-resistant coating layer is preferably 1 mass% or more, since the slip property can be secured.

As a method for measuring the content of the particles contained in the easy-slip coating layer, for example, in the case where the easy-slip coating layer contains the resin containing the organic component and the inorganic particles, the following method can be used. First, the easy-to-slide coating layer provided on the processed film is extracted from the processed film with a solvent or the like and dried to be solidified, thereby taking out the easy-to-slide coating layer. Next, heat is applied to the obtained easy-slip coating layer, and the organic component contained in the easy-slip coating layer is thermally burned and distilled off, whereby only the inorganic component can be obtained. The mass% of the particles contained in the easily slippery coating layer can be measured by measuring the weight of the obtained inorganic component and the easily slippery coating layer before removal by combustion distillation. In this case, a commercially available differential heat/thermogravimetric simultaneous measurement apparatus was used, and thus measurement was performed with high accuracy. When a plurality of types of particles are present, the ratio of the particles to the total solid content of the slip-resistant coating layer means the ratio of the total amount of the plurality of types of particles.

(additive in easy-slip coating layer)

In order to impart other functionality to the slip-coat layer, various additives may be contained within a range not impairing the coating appearance. Examples of the additives include fluorescent dyes, fluorescent brighteners, plasticizers, ultraviolet absorbers, pigment dispersants, foam inhibitors, defoaming agents, and preservatives.

The easy-slip coating layer may contain a surfactant for the purpose of improving leveling property at the time of coating and defoaming of the coating liquid. The surfactant may be any of cationic, anionic, nonionic, etc., and is preferably a silicone, acetylene glycol, or fluorine-based surfactant. It is preferable that these surfactants are contained in the coating layer in such a range that the coating appearance is not abnormal by adding the surfactants in excess.

As the coating method, any of a so-called inline coating method in which the polyester substrate film is simultaneously coated in the case of forming the polyester substrate film and a so-called offline coating method in which the polyester substrate film is formed and then coated with a coater may be applied, and the inline coating method is effective, and more preferable.

As a coating method, any known method can be used for applying the coating liquid to a polyethylene terephthalate (hereinafter, sometimes abbreviated as PET) film. Examples thereof include a reverse roll coating method, a gravure coating method, a kiss coating method, a die coater method, a roll brush method, a spray coating method, an air knife coating method, a wire bar coating method, a tube blade method, an impregnation coating method, and a curtain coating method. These methods are used alone or in combination for coating.

In the present invention, as a method for providing a slip-resistant coating layer on a polyester film, the following methods can be mentioned: a coating liquid containing a solvent, particles and a resin is applied to a polyester film and dried. Examples of the solvent include an organic solvent such as toluene, water, or a mixed system of water and a water-soluble organic solvent, and water alone or a so-called aqueous solvent in which a water-soluble organic solvent is mixed with water is preferable from the viewpoint of environmental problems.

The solid content concentration of the slip-facilitating coating liquid depends on the type of the binder resin, the type of the solvent, and the like, and is preferably 0.5% by mass or more, and more preferably 1% by mass or more. The solid concentration of the coating liquid is preferably 35% by mass or less, more preferably 20% by mass or less.

The drying temperature after coating is preferably 70 ℃ or higher and 250 ℃ or lower, depending on the type of binder resin, the type of solvent, the presence or absence of a crosslinking agent, the solid content concentration, and the like.

(production of polyester film)

In the present invention, the polyester film to be the base film can be produced by a general method for producing a polyester film. For example, the following methods can be mentioned: a non-oriented polyester molded by melting and extruding a polyester resin into a sheet is stretched in the longitudinal direction at a temperature equal to or higher than the glass transition temperature by a speed difference between rolls, and then stretched in the transverse direction by a tenter to be subjected to heat treatment. Further, a method of simultaneously performing longitudinal and transverse biaxial stretching in a tenter may be mentioned.

In the present invention, the polyester film to be the base film may be a uniaxially stretched film or a biaxially stretched film, and a biaxially stretched film is preferable.

The thickness of the polyester film substrate is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 15 μm or more. When the thickness is 5 μm or more, wrinkles are less likely to be formed when the film is conveyed.

The thickness of the polyester film substrate is preferably 50 μm or less, more preferably 45 μm or less, and further preferably 40 μm or less. A thickness of 40 μm or less is preferable because the cost per unit area is reduced.

In the case of in-line coating, the coating may be applied to an unstretched film before stretching in the machine direction, or may be applied to a uniaxially stretched film before stretching in the transverse direction after stretching in the machine direction. In the case of coating before longitudinal stretching, a drying step is preferably provided before roll stretching. In the case of a uniaxially stretched film before transverse stretching, a separate drying step is not necessarily required because the drying step can be simultaneously performed in the film heating step in the tenter. The same applies to simultaneous biaxial stretching.

The thickness of the slip-resistant coating layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, still more preferably 0.02 μm or more, and particularly preferably 0.03 μm or more. When the thickness of the coating 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 preferable.

The thickness of the slip-resistant coating layer is preferably 2 μm or less, more preferably 1 μm or less, still more preferably 0.8 μm or less, and particularly preferably 0.5 μm or less. When the film thickness of the coating layer is 2 μm or less, blocking is not concerned, and it is preferable.

The ceramic green sheet coated and formed on a release coating layer described later is coated and formed, and then wound up in a roll shape together with a release film. At this time, the easily-slippery coating layer of the release film was taken up in contact with the surface of the ceramic green sheet. In order to prevent the occurrence of defects on the surface of the ceramic green sheet, the outer surface of the easy-to-slide coating layer (the surface of the easy-to-slide coating layer of the entire coating film not in contact with the polyester film) needs to be appropriately flat, and preferably, the areal surface average roughness (Sa) is 1nm to 25nm, and the maximum protrusion height (P) is 60nm to 500 nm.

When the regional surface average roughness (Sa) of the outer surface of the easy-to-slide coating layer is 1nm or more and the maximum protrusion height (P) is 60nm or more, the easy-to-slide coating surface is not excessively smooth and appropriate sliding properties can be maintained, which is preferable. When the area surface average roughness (Sa) is 25nm or less and the maximum protrusion height (P) is 500nm or less, the easily-coated surface is not excessively roughened, and defects of the ceramic green sheet due to the protrusions are not generated, which is preferable.

In the present invention, it is preferable that the average width (RSm) of the contour elements is 10 μm or less, in addition to the region surface average roughness (Sa) and the maximum protrusion height (P) being in the above ranges. By controlling the average width (RSm) of the contour elements to 10 μm or less, the number of protrusions per unit area increases. If the number of projections is increased, the pressure applied to each projection is dispersed and reduced, and therefore, the occurrence of pinholes can be effectively suppressed. The average width (RSm) of the outline elements is more preferably 5 μm or less, and still more preferably 3 μm or less. However, since the average width (RSm) of the contour elements is too small, which is associated with an excessive content of particles in the slip-prone coating layer, and the area surface average roughness (Sa) is large, and the maximum protrusion height (P) is large, it is preferably 0.1 μm or more, and may be 0.5 μm or more, or may be 1 μm or more.

In the present invention, the average particle diameter of the particles contained in the easy-slip coating layer is preferably 1000nm or less so that the average width (RSm) of the contour elements is within a predetermined range. More preferably 800nm or less, and still more preferably 600nm or less. When the particle size is 1000nm or less, the distance between particles is not excessively increased, and it is preferable to adjust RSm to a predetermined range.

(mold release coating layer)

The release coating layer of the present invention preferably comprises at least a release agent and a binder component. In addition, the release coating layer of the present invention is preferably high in crosslinking density in order to suppress deformation of the release coating layer. By increasing the crosslinking density, the solvent resistance is improved, and corrosion of the release coating layer by a solvent at the time of coating the slurry is prevented. Further, the modulus of elasticity of the coating film of the release coating layer is also improved, and therefore, the deformation at the time of peeling can be reduced.

The binder component contained in the release coating layer of the present invention is not particularly limited, and a crosslinkable component is preferably crosslinked in order to increase the crosslinking density of the release coating layer. As the binder component, a thermosetting resin, an ultraviolet curable resin, or the like can be used.

In the binder component contained in the release coating layer of the present invention, it is preferable that 1 molecule contains 2 or more reactive functional groups. Having 2 or more functional groups is preferable because the crosslinking density can be increased.

Examples of suitable binder components for the thermosetting resin include melamine compounds. The use of a melamine compound is preferred because a release coating layer having a high crosslinking density can be obtained.

(Melamine compound)

The melamine resin used for the release coating layer of the present invention is not particularly limited, and is generally used, but is preferably obtained by condensing melamine with formaldehyde, and has 1 or more triazine rings and hydroxymethyl groups and/or alkoxymethyl groups in each molecule. Specifically, preferred are compounds obtained by condensing melamine with formaldehyde to obtain methylolmelamine derivatives, and subjecting the obtained methylolmelamine derivatives to dehydration condensation reaction with lower alcohols such as methanol, ethanol, isopropanol, and butanol to etherification, and the like. Examples of the methylolated melamine derivative include monomethylolmelamine, dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylmelamine, and hexamethylolmelamine. The number of the species may be 1 or 2 or more.

In the release coating layer of the present invention, in order to suppress the deformation of the release coating layer, it is preferable that the crosslinking density is high and the modulus of elasticity of the coating film is high. Therefore, as the melamine resin used for the release coat layer, it is preferable to use hexamethylol melamine having a plurality of crosslinking sites in 1 molecule, which can increase the crosslinking density of the release coat layer.

As the melamine-based resin used for the release coating layer of the present invention, methylolmelamine and derivatives thereof are preferred, and when an ether compound obtained by dehydration condensation reaction of an alcohol and a methylolmelamine derivative is used, hexamethoxymethylmelamine obtained by dehydration condensation of methanol is particularly preferred from the viewpoint of reactivity.

When a melamine compound is used as the binder for the release coating layer of the present invention, a catalyst is preferably added in order to promote the crosslinking reaction of the melamine compound. The catalyst to be used is not particularly limited, and a conventional acid catalyst may be used, and a carboxylic acid-based, metal salt-based, phosphate-based, or sulfonic acid-based acid catalyst may be suitably used. In addition, a blocked catalyst in which an acid site is blocked may be used.

When a sulfonic acid-based catalyst is used, for example, p-toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, trifluoromethanesulfonic acid and the like can be suitably used, and p-toluenesulfonic acid can be particularly suitably used.

When a carboxylic acid is used as the acid catalyst, for example, benzoic acid, acetic acid, formic acid, oxalic acid, propionic acid, derivatives thereof, and the like can be used. It is known that carboxylic acid-based acid catalysts have weak acidity and poor reactivity as compared with other catalysts such as sulfonic acid-based catalysts, but carboxylic acid-based catalysts can be fully used in the present invention. In addition, carboxylic acids are preferred because they react more slowly than sulfonic acids, so that the release agent is likely to segregate on the surface in the drying step, and the release agent can be added in a smaller amount to exhibit the effect of releasability. In particular, 4-methylbenzoic acid and the like are inexpensive, readily available and easy to use.

The amount of the acid catalyst added is preferably 0.1 to 10% by mass based on the melamine resin contained in the release coating layer. More preferably 0.5 to 8 mass%. Further preferably 0.5 to 5 mass%. If the content is 0.1% by mass or more, the curing reaction is easily progressed, and it is preferable. On the other hand, if the content is 10% by mass or less, there is no fear that the acid catalyst migrates to the ceramic green sheet to be formed, and there is no fear that adverse effects are caused, so that it is preferable.

Examples of suitable binder components for the ultraviolet curable resin include cationic curable resins and radical curable resins. Examples of the cationically curable resin include epoxy compounds, ether compounds, and oxetane compounds. As the radical curable resin, an acrylate compound can be suitably used. In the case of a radical-curable resin, when a film is formed so that the thickness of the release coating layer is 1 μm or less, curing may not sufficiently proceed due to an oxygen inhibition reaction. Therefore, in the case of a cationic curable resin, it is preferable that the curing is sufficiently performed even when a film having a film thickness of 1.5 μm or less is released from the coating layer, and a release coating layer having a high crosslinking density can be obtained. Among the cationic curable resins, epoxy compounds are preferred because of their high reactivity.

(epoxy compound)

The epoxy compound used in the release film of the present invention is not particularly limited, and the following compounds may be mentioned. Typical examples thereof include bisphenol a type epoxy compounds obtained by reacting bisphenol a with epichlorohydrin in the presence of a base, bisphenol F type epoxy compounds, bisphenol AD type epoxy compounds, and the like. The novolak-type epoxy compound includes phenol novolak-type epoxy compounds, cresol novolak-type epoxy compounds, and the like. Further, there are trisphenol methane triglycidyl ether type epoxy compounds and hydrides, bromides and the like thereof.

Examples of the alicyclic epoxy compound include: a compound obtained by oxidizing a double bond of a cyclohexene ring-containing compound with peracetic acid or the like. Specifically, the following compounds may be mentioned. Comprises the following steps: 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate, 3, 4-epoxy-2-methylcyclohexylmethyl-3, 4-epoxy-2-methylcyclohexanecarboxylate, bis (3, 4-epoxycyclohexyl) adipate, bis (3, 4-epoxycyclohexylmethyl) adipate, bis (3, 4-epoxy-6-methylcyclohexylmethyl) adipate, 2- (3, 4-epoxycyclohexyl-5, 5-spiro-3, 4-epoxy) cyclohexanone-m-dioxane, bis (2, 3-epoxycyclopentyl) ether, and the like. Specific examples of commercially available products thereof include: celoxide 2021P, Celoxide 2081, Celoxide 2000(Daicel corporation), etc.

Further, there are: diglycidyl ether of 1, 4-butanediol, diglycidyl ether of 1, 6-hexanediol, triglycidyl ether of glycerol, triglycidyl ether of trimethylolpropane, diglycidyl ether of polyethylene glycol, diglycidyl ether of polypropylene glycol, polyglycidyl ethers of long-chain polyols containing an alkylene group having 2 to 9 (preferably 2 to 4) carbon atoms, polyoxyalkylene glycols containing polytetramethylene ether glycol, and the like.

As the glycidyl ester type epoxy compound, there are: diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, diglycidyl-paraoxybenzoic acid, glycidyl ether-glycidyl ester of salicylic acid, glycidyl dimer acid, and hydrogenated products thereof.

As the glycidylamine-type epoxy resin, there are: triglycidyl isocyanurate, N' -diglycidyl derivatives of cyclic alkyleneureas, N, O-triglycidyl derivatives of p-aminophenol, N, O-triglycidyl derivatives of m-aminophenol, and the like, and hydrides thereof.

The epoxy compound used for the release coating layer of the present invention may be used alone, or 2 or more kinds may be used in combination. Among these epoxy group-containing compounds, alicyclic epoxy compounds are particularly suitable, and polyfunctional alicyclic epoxy resins having 2 or more functions in 1 molecule are more preferred.

(cationic polymerization initiator)

When a cationic curable resin is used for the release coating layer of the present invention, a cationic polymerization initiator is preferably used. Examples of the cationic polymerization initiator include onium salts such as aryldiazonium salts, aryliodonium salts, arylhalonium salts and arylsulfonium salts, and organometallic complexes such as iron-allene complexes, titanocene complexes and arylsilanol-aluminum complexes. These may be used alone, or 2 or more of them may be used in combination.

Commercially available products include: PCI-220, PCI-620 (manufactured by Nippon chemical Co., Ltd.), UVI6990 (manufactured by Union Carbide Corporation), SP-150, SP-152, SP-170, SP-172 (manufactured by Asahi Denka Co., Ltd.), Uvacure (registered trademark) 1590, 1591 (manufactured by Daicel-UCB Co. Ltd.), San-Aid (registered trademark) SI-110, SI-180, SI-100L, SI-3580 80L, SI60L (manufactured by Sanxin chemical Co., Ltd.), and the like.

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

In the case of using a photo-cationic polymerization initiator as the cationic polymerization initiator, it is desirable to use it in combination with a photosensitizer. Examples of the photosensitizing agent include carbonyl compounds, organic sulfur compounds, persulfates, redox compounds, azo and diazo compounds, halogen compounds, and photoreducible dyes. Specific examples of the photosensitizing agent include benzoin methyl ether, benzoin isopropyl ether, benzoin derivatives such as α, α -dimethoxy- α -phenylacetophenone, benzophenone, 2, 4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4 '-bis (dimethylamino) benzophenone, benzophenone derivatives such as 4, 4' -bis (dimethylamino) benzophenone, thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone, anthraquinone derivatives such as 2-chloroanthraquinone and 2-methylanthraquinone, acridone derivatives such as N-methylacridone and N-butylacridone, α -diethoxyacetophenone, benzil, fluorenone, xanthone, uranyl compounds, halogen compounds, and the like. But is not limited thereto. Further, they may be used alone or in combination. The photosensitizer is preferably added in an amount of about 0.1 to 20% by mass based on the cationic curable resin.

(acrylate-based Compound)

As the acrylate-based compound used for the release coating layer of the present invention, a polyfunctional (meth) acrylate monomer or (meth) acrylate oligomer is preferably used, and a trifunctional or higher (meth) acrylate monomer or (meth) acrylate oligomer is particularly preferred. It is preferable to use a trifunctional or higher functionality because the crosslinking density can be improved, the solvent resistance is high, and the deformation of the release coat layer can be reduced. The acrylate compound used may be one kind or two or more kinds in combination. When used in combination, at least one is preferably trifunctional or higher.

Examples of the polyfunctional (meth) acrylate monomer include trimethylolpropane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide-modified trimethylolpropane tri (meth) acrylate, tris ((meth) acryloyloxyethyl) isocyanurate, propionic acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, and the like. These may be used alone, or 2 or more kinds may be used in combination.

Examples of the polyfunctional (meth) acrylate oligomer include polyester acrylate oligomers, epoxy acrylate oligomers, urethane acrylate oligomers, polyether acrylate oligomers, polybutadiene acrylate oligomers, and silicone acrylate oligomers.

(photo radical initiator)

When a radical polymerization resin is used for the release coating layer of the present invention, a photo radical polymerization initiator is preferably added. Specific examples of the photo radical polymerization initiator include benzophenone, acetophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzil dimethyl ketal, 2, 4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzil, diacetyl, β -chloroanthraquinone, (2,4, 6-trimethylbenzyldiphenyl) phosphine oxide, and 2-benzothiazole-N, N-diethyldithiocarbamate. Particularly preferred are 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl ] -phenyl } -2-methylpropan-1-one, 1-hydroxy-cyclohexyl-phenyl-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, and 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one, which are excellent in surface curability, and among these, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, and 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one A ketone. These may be used alone, or 2 or more kinds may be used in combination.

The amount of the photo radical polymerization initiator to be added is not particularly limited. For example, about 0.1 to 20% by mass of the radical curable resin is preferably used.

The binder component contained in the release coating layer of the present invention is preferably contained in an amount of 85 mass% or more, more preferably 90 mass% or more, and still more preferably 95 mass% based on the solid content of the entire release coating layer. By containing the binder component in an amount of 85 mass% or more, the release coating layer has a high crosslinking density, can have high solvent resistance and a high film elastic modulus, and can suppress deformation of the release coating layer when the ceramic green sheet is peeled. In the present invention, components other than the binder component and the release agent component in the release coating layer such as the residual solvent, the acid catalyst, the photo cation initiator and the photo radical initiator are volatile or trace, and in the present invention, the solid content of the entire release coating layer is a value obtained by totaling the binder component and the release agent.

(mold releasing agent)

As the release agent (additive for improving the releasability of the release coating layer) used in the present invention, a silicone additive, an olefin-based, long-chain alkyl-based, fluorine-based or other non-silicone additive, and the like can be used, and from the viewpoint of releasability, a silicone additive is preferably used.

The silicone additive is a compound having an organosilicon skeleton in the molecule, and polyorganosiloxane or the like can be suitably used. In addition, an acrylic resin having polyorganosiloxane in a side chain, an alkyd resin, or the like may be used. Among the polyorganosiloxanes, polydimethylsiloxane (abbreviated as PDMS) can be suitably used, and one having a functional group in a part of the polydimethylsiloxane is also preferable. Having a functional group is preferable because intermolecular interaction with a binder component, for example, hydrogen bond, is easily exhibited and migration to the ceramic green sheet is less likely to occur.

The functional group to be introduced into polydimethylsiloxane is not particularly limited, and may be a reactive functional group or a non-reactive functional group. The functional group may be introduced into a single end of the polydimethylsiloxane, may be introduced into both ends, or may be introduced into a side chain. The number of introduction positions may be 1 or more. Although theoretical examination cannot be made, it is preferable to introduce the single terminal because the terminal exhibits good peelability.

The functional group introduced into polydimethylsiloxane may be 2 or more, preferably 1 in 1 molecule. In the case of 1 type, the intermolecular interaction with the melamine binder component is not easily increased more than necessary, and the surface of the release coating layer is easily oriented, so that it is preferable.

As the reactive functional group introduced into polydimethylsiloxane, an amino group, an epoxy group, a hydroxyl group, a mercapto group, a carboxyl group, a methacryloyl group, an acryloyl group, or the like 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, or the like can be used. In particular, without being bound by theory, those having an epoxy group, a carboxyl group, a polyether group, a methacryloyl group, an acryloyl group, and an ester group are preferable.

Further, an acrylic resin, a polyester resin, a urethane resin, or the like having polydimethylsiloxane in the side chain can also be suitably used. Commercially available products of acrylic resins having a silicone skeleton in a side chain include Saimac (registered trademark) US350, Saimac (registered trademark) US352, (manufactured by tokyo Chemical co.), 8BS-9000 (manufactured by Taisei Fine Chemical co., ltd.), and the like.

The fluorine-containing additive is not particularly limited, and those conventionally used can be used. For example, those having a perfluoro group or those having a perfluoroether group can be suitably used. Commercially available products include MEGAFACF (registered trademark) (product of DIC Co., Ltd.), Optool (registered trademark) (product of Daikin Industries, Ltd.), and the like.

The long-chain alkyl group-based additive may be a resin modified with a long-chain alkyl group, and preferably a resin having an alkyl group with about 8 to 20 carbon atoms in a side chain, such as polyvinyl alcohol or an acrylic resin. In addition, it is also possible to suitably use: a polymer having a (meth) acrylate as a main repeating unit, wherein the ester-exchanged portion contains a long-chain alkyl group having 8 to 20 carbon atoms. Examples of commercially available products include Peyrole (registered trademark) 1010, Peyrole (registered trademark) 1050, and Peyrole (registered trademark) 1070 (see above, LION SPECIALTY CHEMICALS co., ltd.,), Tesfine (registered trademark) 305, Tesfine (registered trademark) 314 (see above, manufactured by hitachi chemical co., ltd.), and the like.

The release coating layer of the present invention preferably contains a release agent in an amount of 0.1 mass% or more and 15 mass% or less based on the solid content of the entire release coating layer. More preferably 0.5% by mass or more and 10% by mass or less, and still more preferably 0.5% by mass or more and 5% by mass or less. When 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, if it is 15 mass% or less, the modulus of elasticity of the film of the release coating layer as a whole is not excessively lowered, and deformation of the release coating layer is less likely to occur when the ceramic green sheet is peeled. In this case, the solid content of the release coating layer as a whole is a total value of the binder component and the solid content of the release agent.

The release coating layer of 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 occurrence of pinholes.

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

In the present invention, the thickness of the release coating layer is not particularly limited and may be set according to the purpose of use, but is preferably in the range of 0.01 to 1.5 μm, more preferably 0.1 to 1.2 μm, and still more preferably 0.5 to 1.1 μm in weight of the release coating layer after curing. The thickness of the release coating layer is preferably 0.01 μm or more, since the release performance can be obtained. Further, if it is 1.5 μm or less, the curing time can be shortened, the planarity of the release film can be maintained, and the variation in the thickness of the ceramic green sheet can be suppressed. Further, when the thickness of the release coating layer is small, the curl of the release film when heated is reduced, and therefore, it is preferable that no traveling defect is caused in the process of molding and drying the ceramic green sheet.

The release film of the present invention has a curl of preferably 3mm or less, more preferably 1mm or less after being heated at 100 ℃ for 15 minutes without applying a tension. It is of course also preferred that no curling at all is present. By setting the thickness to 3mm or less, the ceramic green sheet is excellent in traveling property when molded and dried, and printing accuracy when printing on the electrode can be improved, which is preferable.

The elastic modulus of the film on the surface of the release coating layer of the release film of the present invention, as measured by the nanoindentation test, is 2.0GPa or more, preferably 2.3GPa or more. Since the release coating layer is less likely to deform when the elastic modulus of the coating film on the surface of the release coating layer is 2.0GPa or more, the release coating layer is less likely to follow the ceramic green sheet when the ceramic green sheet is peeled from the release coating layer, and thus the ceramic green sheet can be normally peeled. On the other hand, the upper limit of the elastic modulus of the film on the surface of the release coating layer is not particularly limited, but is preferably 10.0GPa or less, more preferably 7.0GPa or less, from the viewpoint of appropriately maintaining the adhesion between the release coating layer and the PET substrate.

In the present specification, the elastic modulus of the coating film on the surface of the release coating layer is measured by a nanoindentation test in an atmosphere at 23 ℃. Specifically, the back surface side of the base material of the release film cut into a size of 10mm × 10mm was fixed to a glass plate bonded to an aluminum base with a 2-pack type epoxy adhesive, and the measurement was performed using a microhardness measuring device.

The surface free energy of the surface of the release coating layer of the release film of the present invention is preferably 18mJ/m²Above and 40mJ/m²The following. More preferably 23mJ/m²Above and 35mJ/m²Hereinafter, more preferably 23mJ/m²Above and 30mJ/m²The following. If it is 18mJ/m²The above is preferable because the ceramic slurry is less likely to cause shrinkage when coated and can be uniformly coated. And, if it is 40mJ/m²Hereinafter, the releasability of the ceramic green sheet is not lowered, and is preferable. By setting the above range, a release film having excellent releasability without sink marks at the time of coating 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/mm²More preferably 0.8mN/mm or more²The above. The peel force is 0.5mN/mm²The above is preferable because the peeling force is not too low and the ceramic green sheet is not likely to float during transportation. On the other hand, the peel force is preferably 3mN/mm²Less than, more preferably 2.5mN/mm²The following. The peel force is 3mN/mm²Hereinafter, the ceramic green sheet is preferably not easily damaged at the time of peeling.

In the present invention, the method for forming the release coating layer is not particularly limited, and the following methods can be used: a coating liquid in which a mold-release resin is dissolved or dispersed is spread on one surface of a polyester film of a substrate by coating or the like, and after removing a solvent or the like by drying, the polyester film is heated to dry and heat-cured.

In the present invention, when a thermosetting resin such as melamine is used as the binder for the release coating layer, the drying temperature at the time of solvent drying and thermosetting is preferably 100 ℃ to 180 ℃, more preferably 110 ℃ to 160 ℃, and most preferably 125 ℃ to 150 ℃. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less. When the temperature is 180 ℃ or lower, the flatness of the film can be maintained, and the possibility of causing thickness unevenness of the ceramic green sheet is small, and it is preferable. A temperature of 140 ℃ or lower is particularly preferable because the processing can be performed without impairing the planarity of the film, and the possibility of causing thickness unevenness of the ceramic green sheet is further reduced. When the temperature is 100 ℃ or higher, the curing reaction of the thermosetting resin proceeds sufficiently, and the modulus of elasticity of the coating film of the release coating layer is improved, and it is preferable.

When an active energy ray-curable resin such as epoxy or acrylate is used as the binder for the release coating layer in the present invention, the drying temperature for solvent drying is preferably 50 ℃ or higher and 110 ℃ or lower, more preferably 60 ℃ or higher and 100 ℃ or lower. The drying time is preferably 30 seconds or less, more preferably 20 seconds or less. After the solvent is further dried, the curing reaction is performed by irradiation with active energy rays. As the active energy ray used in this case, ultraviolet rays, electron beams, X-rays, and the like can be used, and ultraviolet rays are preferred because they are easy to use. The amount of ultraviolet light to be irradiated is preferably 30 to 300mJ/cm in light amount²More preferably 30 to 200mJ/cm²More preferably 30 to 80mJ/cm². By setting to 30mJ/cm²As described above, the curing of the resin was sufficiently progressed, and the thickness was set to 300mJ/cm²Since the processing speed can be improved as described below, a release film can be produced economically, which is preferable.

In the case where a radically reactive active energy ray-curable resin such as an acrylate is used as the binder in the release coating layer of the present invention, the irradiation with the active energy ray is preferably performed in a nitrogen atmosphere. In the nitrogen atmosphere, the oxygen concentration is preferably reduced, so that the radical reaction proceeds smoothly and the modulus of elasticity of the coating film of the release coating layer can be improved.

In the present invention, the surface tension of the coating liquid when applying the release coating layer is not particularly limited, but is preferably 30mN/m or less. By setting the surface tension to the 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, a solvent having a boiling point of 90 ℃ or higher is preferably added to the coating liquid for applying the release coating layer, and is not particularly limited. 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 the additive is preferably about 10 to 80% by mass based on the whole 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.

The outer surface of the film on which the release coating layer is formed (the surface of the release coating layer of the entire coated film which is not in contact with the polyester film) is desirably flat in order to prevent defects from occurring in the ceramic green sheet coated and molded thereon, and the area surface average roughness (Sa) is preferably 5nm or less and the maximum protrusion height (P) is preferably 30nm or less. More preferably, the area surface average roughness is 5nm or less and the maximum protrusion height is 20nm or less. When the area surface roughness is 5nm or less and the maximum protrusion height is 30nm or less, no defective spots such as pinholes are generated when forming the ceramic green sheet, and the yield is good and preferable. The smaller the area surface average roughness (Sa) is, the more preferable it is, it may be 0.1nm or more, and may be 0.3nm or more. The smaller the maximum protrusion height (P) is, the more preferable, the maximum protrusion height may be 1nm or more, or may be 3nm or more.

In the present invention, in order to adjust the surface of the film on which the release coating layer is formed to have a predetermined roughness range, it is preferable that the PET film contains substantially no inorganic particles. In the present invention, "substantially no inorganic particles" means that, in the case of inorganic particles, for example, both of the base film and the release coating layer, when the particle-derived elements are quantitatively analyzed by fluorescent X-ray analysis, the content is defined to be 50ppm or less, preferably 10ppm or less, and most preferably the detection limit or less. This is because, even if the particles are not positively added to the base film, a contaminant component derived from foreign matter or a contaminant adhering to a production line or an apparatus in a production process of the raw resin or the film may be peeled off and mixed into the film.

(ceramic Green sheet and ceramic capacitor)

Generally, a laminated ceramic capacitor has a ceramic body in a rectangular parallelepiped shape. In the interior of the ceramic body, the 1 st internal electrode and the 2 nd internal electrode are alternately provided 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 is used for producing such a laminated ceramic capacitor. For example, it can be manufactured as follows. First, a ceramic slurry for forming a ceramic body is applied and dried using the release film of the present invention as a carrier film. On the ceramic green sheet after coating and drying, a conductive layer for constituting the 1 st or 2 nd internal electrode was printed. The ceramic green sheets, the ceramic green sheets on which the conductive layers for constituting the 1 st internal electrode are printed, and the ceramic green sheets on which the conductive layers for constituting the 2 nd internal electrode are printed are stacked as appropriate and pressed to obtain a main laminate. The primary laminate is cut into a plurality of pieces to produce an original ceramic body. The ceramic body is obtained by firing the original ceramic body. After that, the 1 st and 2 nd external electrodes are formed, whereby a laminated ceramic capacitor can be completed.

Examples

The present invention will be described in detail with reference to examples and comparative examples, but it is needless to say that the present invention is not limited to the following examples. The evaluation method used in the present invention is as follows.

(1) Surface characteristics of coating film

The obtained value was measured under the following conditions using a non-contact surface shape measuring system (VertScan R550H-M100). The area surface average roughness (Sa) and the average width of the contour elements (RSm) were the average of 5 measurements, and the maximum protrusion height (P) was the maximum of 5 measurements.

(measurement conditions)

Measurement mode: WAVE mode

Objective lens: 50 times of

0.5 × Tube lens

Measurement area 187X 139. mu.m (measurement of Sa and P)

Measurement length (Lr: sampling length): 187 μm (RSm measurement)

(2) Evaluation of pinhole and thickness unevenness of ceramic Green sheet

A composition comprising the following materials was stirred and mixed, and dispersed for 2 hours with a paint shaker using 2.0mm glass beads as a dispersion medium to obtain a ceramic slurry.

(hydropsy chemical industry Co., Ltd., S-LEC BH-3)

Next, the release surface of the release film sample was coated with an applicator so that the dried slurry had a thickness of 0.5 μm, dried at 90 ℃ for 1 minute, and then the slurry surface and the smooth coating layer surface were superposed on each other and applied at 1kg/cm²After 10 minutes under load, the release film was peeled off to obtain a ceramic green sheet.

In the central region of the obtained ceramic green sheet in the film width direction, 25cm²In the above range, the surface of the ceramic slurry opposite to the coated surface was irradiated with light, and the occurrence of pinholes visible through light transmission was observed, and the occurrence was visually evaluated according to the following criteria.

O: no pinhole, no thickness unevenness

X: with only a few pinholes and/or with slightly noticeable thickness variations

X: less occurrence of pinholes and less thickness variation

XXXXXX: a large number of pinholes and uneven thickness are conspicuous

(3) Evaluation of elastic modulus of coating film on surface of Release coating layer

The mold release films obtained in examples and comparative examples were cut into a size of 10mm × 10mm, and then the back surface of the base material of the cut mold release film was fixed to a glass plate bonded to an aluminum base with a 2-liquid epoxy adhesive. Then, a nanoindentation test was performed in an atmosphere of 23 ℃ at a maximum indentation depth of an indenter of 50nm using a micro hardness evaluation apparatus (ENT-3100, manufactured by eionix corporation), and the coating elastic modulus of the release coating layer of the release film was measured. The results are shown in Table 1.

(preparation 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 adjusted to 2 ton/hr, EG (ethylene glycol) was adjusted to 2 mol based on TPA1 mol, and antimony trioxide was adjusted to 160ppm based on atoms of PET and Sb produced, and these slurries were continuously supplied to the 1 st esterification reaction vessel 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 vessel was continuously taken out of the system, supplied to the 2 nd esterification reaction vessel, and 8 mass% of EG distilled off from the 1 st esterification reaction vessel was supplied to the 2 nd esterification reaction vessel relative to the produced PET, and further, to the produced PET, an EG solution containing magnesium acetate tetrahydrate salt in an amount of 65ppm of Mg atom and an EG solution containing TMPA (trimethyl phosphate) in an amount of 40ppm of P atom relative to the produced PET were added, and the reaction was carried out at an average residence time of 1 hour and 260 ℃. Then, the reaction product in the 2 nd esterification reaction vessel was continuously taken out of the system, supplied to the 3 rd esterification reaction vessel, and kept at 39MPa (400 kg/cm) by using a high-pressure disperser (manufactured by Nippon Seiko Co., Ltd.)²) 0.2 mass% of porous colloidal silica having an average particle size of 0.9 μm after dispersion treatment in which the number of treatments was 5 and 0.4 mass% of synthetic calcium carbonate having an average particle size of 0.6 μm to which 1 mass% of ammonium salt of polyacrylic acid per calcium carbonate unit was attached were added to 10% of EG slurry, and the mixture was reacted at 260 ℃ for 0.5 hour of average retention time under normal pressure. Continuously feeding the esterification reaction product generated in the 3 rd esterification reaction kettle to a 3-stage continuous polycondensation reaction device, performing polycondensation, filtering with a filter obtained by sintering 95% stainless steel fiber with 20 μm cut particle sizeThe resulting mixture was subjected to ultrafiltration, extruded in water, cooled and cut into pellets to obtain PET pellets 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%.

(preparation of polyethylene terephthalate Pellets (PET) (II))

On the other hand, in the production of the above PET chips, PET chips having an intrinsic viscosity of 0.62dl/g (hereinafter, abbreviated as PET (II)) completely free of particles such as calcium carbonate and silica are obtained.

(production of laminated film Z)

After drying these PET chips, they were melted at 285 ℃ and melted at 290 ℃ by different melt extruders, and 2-stage filtration was performed using a filter obtained by sintering 95% of stainless steel fibers having a divided particle size of 15 μm and a filter obtained by sintering 95% of stainless steel particles having a divided particle size of 15 μm, and these were combined in a feed head, and laminated so that PET (i) became a reverse release surface side layer and PET (ii) became a release surface side layer, and extruded (cast) into a sheet shape at a speed of 45 m/min, and by an electrostatic adhesion method, the sheet was electrostatically adhered to a casting drum at 30 ℃ and cooled to obtain an unstretched polyethylene terephthalate sheet having an intrinsic viscosity of 0.59 dl/g. The layer ratio was adjusted so that the discharge amount of each extruder was 60%/40% of pet (i)/(II). 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 a speed difference between rolls. Thereafter, the resultant was introduced into a tenter and stretched at 140 ℃ by 4.2 times in the transverse direction. Next, in the heat fixing zone, heat treatment was performed at 210 ℃. Thereafter, relaxation treatment was carried out at 170 ℃ for 2.3% in the transverse direction to obtain a biaxially stretched polyethylene terephthalate film Z having a thickness of 31 μm. The Sa of the release side layer of the obtained film Z was 2nm, and the Sa of the reverse release side layer was 28 nm.

(polymerization of polyester resin A0-1)

194.2 parts by mass of dimethyl terephthalate, 184.5 parts by mass of dimethyl isophthalate, 14.8 parts by mass of dimethyl isophthalate-5-sulfonic acid sodium salt, 185.1 parts by mass of ethylene glycol, 185.1 parts by mass of neopentyl glycol, and 0.2 part by mass of tetra-n-butyl titanate were put into a stainless autoclave equipped with a stirrer, a thermometer, and a partial reflux condenser, and ester exchange reaction was carried out at a temperature of 160 to 220 ℃ for 4 hours. Subsequently, the temperature was raised to 255 ℃ and the pressure of the reaction system was gradually reduced, followed by reaction under a reduced pressure of 30Pa for 1 hour and 30 minutes to obtain a copolyester resin (A0-1). The resulting copolyester resin (A0-1) was transparent in pale yellow. The reduced viscosity of the copolyester resin (A0-1) was measured to find that it was 0.60 dl/g. The glass transition temperature based on DSC is 65 ℃.

(preparation of aqueous polyester Dispersion A-1)

In a reactor equipped with a stirrer, a thermometer and a reflux apparatus, 30 parts by mass of a polyester resin (A0-1) and 15 parts by mass of ethylene glycol-n-butyl ether were placed, and the mixture was heated and stirred at 110 ℃ to dissolve the resin. After the resin was completely dissolved, 55 parts by mass of water was slowly added to the polyester solution while stirring. After the addition, the liquid was cooled to room temperature while stirring, to prepare a milky-white aqueous polyester dispersion (a-1) having a solid content of 30 mass%.

(polymerization of polyester resin A0-2)

163 parts by mass of dimethyl terephthalate, 163 parts by mass of dimethyl isophthalate, 169 parts by mass of 1, 4-butanediol, 324 parts by mass of ethylene glycol, and 0.5 part by mass of tetra-n-butyl titanate were charged into a stainless autoclave equipped with a stirrer, a thermometer, and a partial reflux condenser, and ester exchange reaction was carried out at 160 ℃ to 220 ℃ for 4 hours.

Then, 14 parts by mass of fumaric acid and 203 parts by mass of sebacic acid were added, and the temperature was raised from 200 ℃ to 220 ℃ over 1 hour to perform an esterification reaction. Subsequently, the temperature was raised to 255 ℃ and the pressure of the reaction system was gradually reduced, followed by reaction under a reduced pressure of 29Pa for 1 hour and 30 minutes to obtain a hydrophobic copolyester resin (A0-2). The resulting hydrophobic copolyester resin (A0-2) was light yellow and transparent.

(preparation of aqueous polyester Dispersion A-2)

Then, 60 parts by mass of the copolyester resin (A0-2), 45 parts by mass of methyl ethyl ketone, and 15 parts by mass of isopropyl alcohol were placed in a reactor equipped with a stirrer, a thermometer, a reflux device, and a quantitative dropping device for producing a graft resin, and the resin was dissolved by heating and stirring at 65 ℃. After the resin was completely dissolved, 24 parts by mass of maleic anhydride was added to the polyester solution.

Subsequently, a solution prepared by dissolving 16 parts by mass of styrene and 1.5 parts by mass of azobisdimethylvaleronitrile in 19 parts by mass of methyl ethyl ketone was added dropwise to the polyester solution at a rate of 0.1 ml/min, and the mixture was stirred for a further 2 hours. After sampling for analysis from the reaction solution, 8 parts by mass of methanol was added. Subsequently, 300 parts by mass of water and 24 parts by mass of triethylamine were added to the reaction solution, and stirred for 1 hour.

Then, the internal temperature of the reactor was increased to 100 ℃, and methyl ethyl ketone, isopropyl alcohol, and excess triethylamine were distilled off by distillation to obtain a pale yellow transparent polyester resin, and a uniform water-dispersible polyester graft copolymer dispersion (a-2) having a solid content of 25 mass% was prepared. The glass transition temperature of the resulting polyester-based graft copolymer was 68 ℃.

(production of polyurethane aqueous Dispersion A-3)

In a four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen introduction tube, a silica gel drying tube, and a thermometer, 43.75 parts by mass of 4, 4-dicyclohexylmethane diisocyanate, 12.85 parts by mass of dimethylolbutyric acid, 153.41 parts by mass of polyhexamethylene carbonate diol having a number average molecular weight of 2000, 0.03 parts by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent were charged, and the mixture was stirred at 75 ℃ for 3 hours under a nitrogen atmosphere, whereby it was confirmed that the reaction solution had a predetermined amine equivalent. Subsequently, the reaction solution was cooled to 40 ℃, and 8.77 parts by mass of triethylamine was added to the reaction solution to obtain a polyurethane prepolymer solution. Next, 450g of water was added to a reaction vessel equipped with a homogeneous disperser capable of high-speed stirring, and the temperature was adjusted to 25 ℃ for 2000min^-1The polyurethane prepolymer solution was added to the mixture while stirring and mixing the mixture, and the mixture was dispersed in water. Then, under reduced pressure, acetone and water were partially removed to prepare a water-soluble urethane resin solution a-3 having a solid content of 37 mass%. The glass transition temperature of the obtained polyurethane resin was-30 ℃.

(production of acrylic polyol A-4)

In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas blowing tube, 231 parts by mass of Methyl Methacrylate (MMA), 130 parts by mass of Stearyl Methacrylate (SMA), 100 parts by mass of hydroxyethyl methacrylate (HEMA), 33 parts by mass of methacrylic acid (MAA) and 1153 parts by mass of isopropyl alcohol (IPA) were charged, and the temperature in the flask was raised to 80 ℃ while stirring. After the flask was kept at 80 ℃ and stirred for 3 hours, 0.5 part by mass of 2, 2-azobis-2-methyl-N-2-hydroxyethylpropionamide was added to the flask. After the flask was purged with nitrogen while the temperature was raised to 120 ℃, the mixture was stirred at 120 ℃ for 2 hours.

Subsequently, the pressure was reduced at 120 ℃ under 1.5kPa to remove the unreacted starting materials and the solvent, thereby obtaining an acrylic polyol. The inside of the flask was returned to atmospheric pressure, cooled to room temperature, and 1976 parts by mass of an aqueous IPA solution (water content 50 mass%) was added and mixed. Then, triethylamine was added to the solution through a dropping funnel while stirring, and neutralization treatment of the acrylic polyol was performed until the pH of the solution became 5.5 to 7.5, thereby obtaining acrylic polyol (a-4) having a solid content concentration of 20 mass%.

(preparation of oxazoline-based crosslinking agent B-1)

In a flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 460.6 parts of isopropyl alcohol were charged, and the flask was heated to 80 ℃ while nitrogen gas was slowly flowed. A monomer mixture containing 126 parts of methyl methacrylate, 210 parts of 2-isopropenyl-2-oxazoline and 84 parts of methoxypolyethylene glycol acrylate, which were prepared in advance, and an initiator solution containing 21 parts of 2, 2' -azobis (2-methylbutyronitrile) (Nippon Hydrazine Industry co., ltd., "ABN-E" manufactured by ltd.) and 189 parts of isopropyl alcohol as a polymerization initiator were added dropwise thereto over 2 hours from a dropping funnel, and the mixture was reacted, followed by further reaction for 5 hours after the completion of the dropwise addition. During the reaction, nitrogen gas was continuously passed through the flask, and the temperature in the flask was maintained at 80. + -. 1 ℃. Thereafter, the reaction solution was cooled to obtain an oxazoline-group-containing resin (B-1) having a solid content of 25%. The oxazoline group content of the resulting oxazoline group-having resin (B-1) was 4.3mmol/g, and the number average molecular weight thereof was 20000 as measured by GPC (gel permeation chromatography).

(silica particles C-1)

Colloidal silica (trade name SNOWTEX XL manufactured by Nissan chemical Co., Ltd., average particle diameter 40nm, solid content concentration 40% by mass)

(silica particles C-2)

Colloidal silica (trade name SNOWTEX ZL, manufactured by Nissan chemical Co., Ltd., average particle diameter 100nm, solid content concentration 40% by mass)

(silica particles C-3)

Colloidal silica (trade name MP2040, average particle diameter 200nm, solid content concentration 40% by mass, manufactured by Nissan chemical Co., Ltd.)

(silica particles C-4)

Colloidal silica (trade name MP4540M, manufactured by Nissan chemical Co., Ltd., average particle diameter 450nm, solid content concentration 40% by mass)

(acrylic particle C-5)

Acrylic particle aqueous dispersion (trade name MX100W, manufactured by Japan catalyst, average particle diameter 150nm, solid content concentration 10% by mass)

(Binder component for releasing coating layer)

As the binder component of the release coating layer, the following materials were used.

(X-1) Melamine Compound

Hexamethoxymethyl melamine (manufactured by Tokyo chemical industry Co., Ltd., solid content 100% by mass)

(X-2) epoxy Compound (alicyclic epoxy Compound)

3',4' -epoxycyclohexylmethyl 3, 4-epoxycyclohexanecarboxylate

(product name: Celoxide (registered trade Mark) manufactured by 2021P, Daicel K.K., solid content 100% by mass)

(X-3) acrylate-based Compound (polyfunctional)

Dipentaerythritol hexaacrylate (product name: DPHA, manufactured by DAICEL-ALLNEX LTD., manufactured by RTM., solid content: 100% by mass)

(X-4) Heat curing addition reaction type Silicone

(product name: KS-847H, manufactured by shin Yue Silicone K.K., solid content: 30% by mass)

(Back surface smoothing coating liquid Y)

A material for forming a backside smoothed coating layer having a solid content of 20 mass% was obtained by diluting 94 parts by mass of dipentaerythritol hexaacrylate [ solid content 100 mass% ] as an active energy ray compound, 1 part by mass of a polyorganosiloxane having a polyether-modified acryloyl group [ BYK-UV3500 "trade name, 100 mass% solid content", manufactured by BYK Japan K.K. ] and 5 parts by mass of an alpha-aminoalkylbenzophenone-based photopolymerization initiator [ IRGACURE907 ", 2-methyl-1 [4- (methylthio) phenyl ] -2-morpholinopropane-1-one, 100 mass% solid content, manufactured by BASF corporation, as a photopolymerization initiator ] with an isopropyl alcohol/methyl ethyl ketone mixed solvent (mass ratio 3/1).

(example 1)

(preparation of easy-slip coating liquid 1)

An easy-slip coating solution 1 having the following composition was prepared.

(Yishu coating liquid 1)

(production of polyester film)

PET resin Pellets (PETII) having an intrinsic viscosity (solvent: phenol/tetrachloroethane: 60/40) of 0.62dl/g and containing substantially no inorganic particles were dried at 135 ℃ under a reduced pressure of 133Pa for 6 hours as a film raw material polymer. Thereafter, the sheet was fed to an extruder, melt-extruded at about 280 ℃ into a sheet, and rapidly cooled, closely adhered and solidified on a rotating cooling metal roll having a surface temperature of 20 ℃ to obtain an unstretched PET sheet.

The unstretched PET sheet was heated to 100 ℃ by a heated roll set and an infrared heater, and then stretched 3.5 times in the longitudinal direction by the roll set having a circumferential speed difference to obtain a uniaxially stretched PET film.

The above-mentioned coating liquid was applied to one surface of a PET film by a bar coater, and then dried at 80 ℃ for 15 seconds. The coating weight after final stretching and drying was adjusted to 0.1 μm. Then, the film was stretched at 150 ℃ in the width direction by a 4.0-fold stretching machine, heated at 230 ℃ for 0.5 second with the length of the film in the width direction fixed, and further subjected to a 3% relaxation treatment at 230 ℃ for 10 seconds to obtain an in-line coated polyester film having a thickness of 31 μm.

(formation of mold-releasing coating layer)

On the surface of the in-line coated polyester film obtained in the above manner opposite to the surface on which the easy-to-slip coating layer was laminated, a release coating liquid 1 was applied so as to be 0.6 μm in thickness after drying, and dried at 140 ℃ for 15 seconds to form a release coating layer, thereby obtaining a release film for producing an ultrathin ceramic green sheet. The film has excellent winding properties, process passability, and handling properties without any particular problem. Further, the ceramic slurry was applied to the obtained release film, and pinholes and thickness unevenness were evaluated, and as a result, good evaluation results were obtained.

(mold release coating liquid 1)

(example 2)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the coating solution 1 was changed to the coating solution 2 described below.

(Yi-SLIP COATING LIQUID 2)

(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 solution 1 was changed to the coating solution 3 described below.

(Yi-SLIP coating liquid 3)

(example 4)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the coating solution 1 was changed to the coating solution 4 described below.

(Yi-SLIP COATING LIQUID 4)

(example 5)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the coating solution 1 was changed to the coating solution 5 described below.

(Yi-SLIP COATING LIQUID 5)

(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 coating solution 1 was changed to the coating solution 6 described below.

(Yi-SLIP COATING LIQUID 6)

(example 7)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the coating solution 1 was changed to the coating solution 7 described below.

(Yi-SLIP COATING LIQUID 7)

(example 8)

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 1, except that the coating solution 1 was changed to the coating solution 8 described below.

(Yishu coating liquid 8)

(example 9)

On the obtained in-line coated polyester film, a mold release coating liquid 2 was applied by a reverse gravure coater so that the thickness after drying became 0.6. mu.m on the surface opposite to the easy-to-slip coating layer, followed by drying at 90 ℃ for 15 seconds and then irradiating with ultraviolet rays so that the thickness became 60mJ/cm²A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 4, except that a release coating layer was formed.

(Release coating liquid 2)

(example 10)

On the surface opposite to the easy-slip coating layer of the obtained on-line coated polyester film, irradiation dose was 60mJ/cm under nitrogen atmosphere (oxygen concentration: 1%)²A mold release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 4, except that the mold release coating liquid 3 was applied by ultraviolet irradiation so that the thickness after drying became 1.0 μm.

(mold release coating liquid 3)

(Irgacure (registered trademark) 907, manufactured by BASF corporation)

Comparative example 1

A release film for producing a ceramic green sheet was obtained in the same manner as in example 1, except that the film for forming a release coating layer was used in place of the in-line coated film having an easy-to-slip coating layer on one surface prepared in example 1, except that the thickness was changed to E5000 to 25 μm (manufactured by tokyo corporation). E5000 is as follows: the film contained particles therein, and both surfaces had Sa of 0.031 μm.

Comparative example 2

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 10, except that the release film for forming a release coating layer was used in place of the inline-coated film having an easy-to-slip coating layer on one surface, which was prepared in example 1, instead of using it as an E5000 to 25 μm (manufactured by toyoyo textile).

Comparative 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 film for forming a release coating layer was used instead of the in-line coating film having an easy-to-slip coating layer on one surface, which was prepared in example 1, and the laminated film Z was used. The release coat layer was provided on the surface (layer containing no particles) of the laminated film Z from which the pet (ii) pellets were discharged.

Comparative example 4

The surface of the release film for producing an ultrathin ceramic green sheet obtained in comparative example 3 on which the release coating layer was formed was the opposite surface, the back surface was coated with a smoothing coating liquid Y so that the thickness after drying became 0.5. mu.m, and then dried with hot air at 90 ℃ for 30 seconds, and immediately subjected to ultraviolet irradiation (300 mJ/cm) using an electrodeless lamp (H valve, Heraeus corporation)²) Then, a back surface smoothing layer was formed to obtain a mold release film for producing an ultrathin ceramic green sheet.

Comparative example 5

A mold release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in comparative example 4, except that the back surface smoothing layer was coated so as to have a thickness of 0.7. mu.m.

Comparative example 6

A mold release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in comparative example 4, except that the back surface smoothing layer was coated so as to have a thickness of 1.0. mu.m.

Comparative example 7

A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in example 4, except that the release coating layer was formed by applying a release coating liquid 4 so that the thickness after drying became 0.6 μm on the surface of the obtained in-line coated polyester film opposite to the easy-to-slip coating layer by a reverse gravure coater and then drying at 160 ℃ for 15 seconds.

(mold release coating liquid 4)

(platinum catalyst, CAT-PL-50T, manufactured by shin-Etsu chemical Co., Ltd.)

The evaluation results of the examples and comparative examples are shown in table 1.

[ Table 1]

*1: the column entitled "easily-slippery coating layer" in comparative examples 1 to 3 describes the evaluation results of the surface opposite to the surface laminated with the "release coating layer" of the polyester film

*2: in the column of "easy-to-slide coating layer" in comparative examples 4 to 6, the evaluation results of the surface of "backside smoothing layer" are described

In examples 1 to 10, all parameters of Sa, P, and RSm on the surface of the easily-slid coating layer were in appropriate ranges, and therefore, ceramic green sheets free from occurrence of pinholes could be obtained. In comparative examples 1 to 3, pinholes were observed because all of the parameters Sa, P, RSm of the easy-to-slide surface were large. In comparative examples 4 to 6, while Sa and P can be set to appropriate ranges by filling the irregularities of the slip-susceptible surface with the smoothing layer, RSm is large and thus it is not sufficient to suppress the occurrence of pinholes. The large RSm means that the protrusion interval is wide, the number of protrusions per unit area is small, the pressure applied to 1 protrusion is large, and it is considered that a pinhole is generated. In comparative example 7, all parameters of Sa, P, and RSm on the surface of the easy-slip coating layer were in appropriate ranges, and therefore, a ceramic green sheet free from pinholes could be obtained, but the film elastic modulus on the surface of the release coating layer was low, and therefore, peeling could not be performed normally, and the yield was lowered.

Industrial applicability

According to the present invention, there can be provided: a mold release film for producing a ceramic green sheet, which can achieve both excellent winding properties and prevention of pinholes, partial thickness unevenness, and the like even when the ceramic green sheet is made thin. Further, by using the release film for producing a ceramic green sheet of the present invention, an extremely thin ceramic green sheet can be obtained, and a minute ceramic capacitor can be efficiently produced.

Claims (7)

1. A release film for producing a ceramic green sheet, which comprises a polyester film as a base material, a release coating layer on one surface of the base material, wherein the release coating layer has a film elastic modulus of 2.0GPa or more as measured from the surface on the opposite side of the base material by a nanoindentation test on the release coating layer, and further comprises an easy-to-slide coating layer containing particles on the other surface of the base material, wherein the easy-to-slide coating layer has a regional surface average roughness (Sa) of 1nm to 25nm inclusive, a maximum protrusion height (P) of 60nm to 500nm inclusive, and an average width of contour elements (RSm) of 10 [ mu ] m inclusive,

the polyester film is a polyester film substantially free of inorganic particles,

the easily-sliding coating layer contains particles having an average particle diameter of 10nm to 1000 nm.

2. The release film for manufacturing a ceramic green sheet according to claim 1, wherein the area surface average roughness (Sa) of the release coating layer is 5nm or less, and the maximum protrusion height (P) is 30nm or less.

3. The release film for producing a ceramic green sheet according to claim 1, wherein the thickness of the slip-susceptible coating layer is 0.001 μm or more and 2 μm or less.

4. The release film for producing a ceramic green sheet according to claim 1, wherein the particles contained in the easy-slip coating layer include particles having an average particle diameter of 10 to 270nm and particles having an average particle diameter of 300 to 1000 nm.

5. A method for producing a ceramic green sheet, which comprises using the release film for producing a ceramic green sheet according to any one of claims 1 to 4.

6. The method of manufacturing a ceramic green sheet according to claim 5, wherein the thickness of the ceramic green sheet to be manufactured is 0.2 μm to 2.0 μm.

7. A method for producing a ceramic capacitor using the method for producing a ceramic green sheet according to claim 5 or 6.