JPWO2020067090A1 - Release film for manufacturing ceramic green sheets - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film for molding a ceramic green sheet, which has excellent peelability and is less likely to cause damage such as cracks in a half-cut test for an ultrathin ceramic green sheet to be molded. A release film in which a release layer is laminated directly on at least one surface of a polyester film or via another layer, and the release layer is an energy ray-curable compound (I), a polyester resin ( The coating film containing at least the release component (II) and the release component (III) is cured, and the polyester resin (II) is a mold release for producing a ceramic green sheet containing an ester constituent unit derived from the 5-sodium sulfoisophthalic acid component. the film. [Selection diagram] None

Description

The present invention relates to a release film for manufacturing an ultra-thin layer ceramic green sheet, and more specifically, a film that suppresses the occurrence of process defects due to pinholes, uneven thickness, and poor peeling during the production of an ultra-thin layer ceramic green sheet. It relates to a mold release film for manufacturing an ultra-thin ceramic green sheet that can be manufactured.

Conventionally, a release film obtained by laminating a release layer on a polyester film as a base material is used for molding a ceramic green sheet such as a laminated ceramic capacitor (hereinafter referred to as MLCC) and a ceramic substrate. In recent years, with the miniaturization and large capacity of multilayer ceramic capacitors, the thickness of the ceramic green sheet tends to be reduced. The ceramic green sheet is molded by applying a slurry containing a ceramic component such as barium titanate and a binder resin to a release film and drying it. A laminated ceramic capacitor is manufactured by printing an electrode on a molded ceramic green sheet, peeling it from a release film, laminating the ceramic green sheet, pressing and cutting, firing, and applying an external electrode. Until now, when a ceramic green sheet was molded on the surface of the release layer of a polyester film, minute protrusions on the surface of the release layer affected the molded ceramic green sheet, and defects such as cissing and pinholes were likely to occur. There was a problem. Therefore, various methods for realizing a release layer surface having excellent flatness have been developed (see, for example, Patent Document 1).

However, in recent years, further thinning of the ceramic green sheet has progressed, and a ceramic green sheet having a thickness of 1.0 μm or less, more specifically 0.2 μm to 1.0 μm, has been required. Therefore, higher smoothness is required for the surface of the release layer. In addition, since the strength of the ceramic green sheet decreases as the ceramic green sheet becomes thinner, not only the surface of the release layer is smoothed, but also the peeling force when the ceramic green sheet is peeled from the release film is low and uniform. It has become preferable to minimize the load applied to the ceramic green sheet when peeling the ceramic green sheet from the release film so as not to damage the ceramic green sheet.

As a method from the release layer side to smooth the surface of the release layer and suppress the load on the ceramic green sheet at the time of peeling, the release layer is formed by using an active energy ray-curable component for the release layer of the release film. Measures to suppress elastic deformation of the release layer at the time of peeling of the ceramic green sheet and reduce the peeling force by increasing the cross-linking density and the elastic modulus of the ceramic green sheet have been studied (see, for example, Patent Documents 2 and 3). .. However, in this method, since the smoothness is too high, surface peeling occurs, the peeling force becomes heavy, and the green sheet may be cracked. Furthermore, when the ultra-thin ceramic green sheet is processed, if the smooth surface comes into contact with a smooth roll or rubber roll for controlling the tension of the coating equipment, the slipperiness of the roll and the smooth surface becomes insufficient and the tension control becomes unstable. There is a problem that the smoothness of the green sheet coated surface is lowered.

Therefore, a release film having an excellent balance between smoothness and uniform peelability has been reported by using a polyester film having an appropriate large protrusion that serves as a trigger (peeling start point) at the start of peeling (for example). , Patent Document 4). However, in the case of the filler kneaded into PET, there is a problem that the coarse protrusions due to the aggregation of the filler cannot be completely eliminated, which causes a defect of the product. In particular, in the ultrathin ceramic green sheet, since the inorganic filler used as the ceramic material has a particle size of about 60 nm to 800 nm (see, for example, Patent Documents 5 and 6), a film as described in Patent Document 4 is used. When used, there was a problem that local holes were generated on the peeled surface.

Japanese Unexamined Patent Publication No. 2000-117899 International Publication No. 2013/145864 International Publication No. 2013/145856 International Publication No. 2014/203702 Japanese Unexamined Patent Publication No. 2016-127120 Japanese Unexamined Patent Publication No. 2017-081805

Therefore, as a result of diligent studies, the present inventors have determined that by forming surface irregularities due to low protrusions on the surface of the release layer, it is possible to simultaneously suppress the above-mentioned heavy peeling, deterioration of processing suitability, and occurrence of defect factors. It was. An object of the present invention is to provide a release film for molding a ceramic green sheet, which has excellent peelability and is less likely to cause damage such as cracks in a half-cut test for an ultrathin ceramic green sheet to be molded.

That is, the present invention has the following configuration.
1. 1. A release film in which a release layer is laminated directly on at least one side of the polyester film or via another layer, and the release layer is an energy ray-curable compound (I), a polyester resin (II), and A release film for producing a ceramic green sheet, wherein the coating film containing at least the release component (III) is cured, and the polyester resin (II) contains an ester structural unit derived from the 5-sodium sulfoisophthalic acid component.
2. 2. The mold release layer has a phase-separated structure in which the energy ray-curable compound (I) is a sea component and the polyester resin (II) is an island component, and has surface irregularities. Release film.
3. 3. The release film for producing a ceramic green sheet according to the first or second above, wherein the release layer does not substantially contain inorganic particles.
4. The release film for producing a ceramic green sheet according to any one of the above 1 to 3, wherein the energy ray-curable compound (I) is a (meth) acrylic acid ester having 3 or more acryloyl groups in one molecule. ..
5. The release film for producing a ceramic green sheet according to any one of the first to fourth above, wherein the release layer has a thickness of 0.2 to 3.5 μm.
6. The release film for producing a ceramic green sheet according to any one of the first to fifth above, wherein the region surface average roughness (Sa) of the release layer is 5 to 40 nm.
7. The release film for producing a ceramic green sheet according to any one of the first to sixth above, wherein the maximum protrusion height (Rp) on the surface of the release layer is 60 nm or less.
8. A method for producing a ceramic green sheet by molding a ceramic green sheet using the release film for producing a ceramic green sheet according to any one of the above 1 to 7, wherein the molded ceramic green sheet is 0.2 μm to A method for manufacturing a ceramic green sheet having a thickness of 1.0 μm.

According to the release film for producing a ceramic green sheet of the present invention, the release force is not too heavy, the workability is excellent, and large protrusions are formed on the release layer as compared with the conventional release film for producing a ceramic green sheet. Therefore, it has become possible to provide a release film for manufacturing a ceramic green sheet that is less likely to cause damage such as cracks in a half-cut test for an ultra-thin ceramic green sheet having a thickness of 1 μm or less to be molded.

It is an electron micrograph of the surface of the release layer of the product of the present invention (Example 1). It is an electron micrograph of the surface of the release layer of the product of the present invention (Example 2).

Hereinafter, the present invention will be described in detail.

(Polyester film)
The polyester constituting the polyester film used as the base material in the release film of the present invention is not particularly limited, and a film-molded polyester usually generally used as the release film base material can be used. Preferably, it is a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component, for example, polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate or these. A copolymer containing the constituent components of the resin as a main component is more preferable, and a polyester film formed from polyethylene terephthalate is particularly preferable. The repeating unit of ethylene terephthalate is preferably 90 mol% or more, more preferably 95 mol% or more, and other dicarboxylic acid components and diol components may be copolymerized in a small amount, but from the viewpoint of cost. , Preferably made only from terephthalic acid and ethylene glycol. Further, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, crystallization agents and the like may be added as long as the effects of the film of the present invention are not impaired. The polyester film is preferably a biaxially stretched polyester film because of its high bidirectional elastic modulus and the like.

The intrinsic viscosity of the polyethylene terephthalate film is preferably 0.50 to 0.70 dl / g, more preferably 0.52 to 0.62 dl / g. When the intrinsic viscosity is 0.50 dl / g or more, it is preferable that breakage does not easily occur in the stretching step. On the contrary, when it is 0.70 dl / g or less, it is preferable because the cutability when cutting to a predetermined product width is good and dimensional defects do not occur. Further, it is preferable that the raw material is sufficiently vacuum dried.

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

In the present invention, the stretching temperature at the time of stretching the polyester film is preferably set to be equal to or higher than the secondary transition point (Tg) of the polyester. It is preferable to stretch 1 to 8 times, particularly 2 to 6 times in each of the vertical and horizontal directions.

The thickness of the polyester film is preferably 12 to 50 μm, more preferably 12 to 38 μm, and even more preferably 15 μm to 31 μm. When the thickness of the film is 12 μm or more, it is preferable because there is no possibility of deformation due to heat during film production, the processing process of the release layer, and the molding of the ceramic green sheet. On the other hand, when the thickness of the film is 50 μm or less, the amount of film discarded after use does not become extremely large, which is preferable in reducing the environmental load, and moreover, the material per area of the release film used is small. Therefore, it is also preferable from an economic point of view.

The polyester film base material may be a single layer or a multilayer of two or more layers, but it may be a laminated polyester film having a surface layer A substantially free of inorganic particles on at least one side. preferable. In the case of a laminated polyester film having a multilayer structure of two or more layers, it is preferable to have a surface layer B capable of containing particles or the like on the opposite surface of the surface layer A which does not substantially contain inorganic particles. As for the laminated structure, if the layer to which the release layer is applied is the surface layer A, the layer on the opposite surface is the surface layer B, and the core layers other than these are the core layer C, the layer structure in the thickness direction is the release layer. A laminated structure such as / surface layer A / surface layer B or release layer / surface layer A / core layer C / surface layer B can be mentioned. As a matter of course, the core layer C may have a plurality of layer configurations. Further, the surface layer B may not contain particles. In that case, it is preferable to provide a coat layer (D) containing particles and a binder on the surface layer B in order to impart slipperiness for winding the film in a roll shape.

In the polyester film base material of the present invention, it is preferable that the surface layer A forming the surface to which the release layer is applied does not substantially contain inorganic particles. At this time, the region surface average roughness (Sa) of the surface layer A is preferably 7 nm or less. When Sa is 7 nm or less, pinholes and the like occur during molding of the ultra-thin ceramic green sheet to be laminated even if the release layer has a film thickness of 2.0 μm or less and is even thinner and 0.5 μm or less. Difficult and preferable. The smaller the region surface average roughness (Sa) of the surface layer A, the more preferable the sheet, but it may be 0.1 nm or more. However, when an anchor coat layer or the like described later is provided on the surface layer A, it is preferable that the coat layer does not substantially contain inorganic particles, and the region surface average roughness (Sa) after laminating the coat layer is within the above range. It is preferable to have. In the present invention, "substantially free of inorganic particles" is defined as 50 ppm or less when the inorganic element is quantified by Kay light X-ray analysis, preferably 10 ppm or less, and most preferably below the detection limit. The content is. This means that even if inorganic particles are not actively added to the film, contaminant components derived from foreign substances and stains attached to the raw material resin or the line or device in the film manufacturing process are peeled off and mixed into the film. This is because there are cases.

When the polyester film base material in the present invention is a laminated film, the surface layer B forming the opposite surface to the surface layer A to which the release layer is applied is a particle from the viewpoint of the slipperiness of the film and the ease with which air can escape. Is preferable, and silica particles and / or calcium carbonate particles are particularly preferable. The total amount of particles contained in the surface layer B is preferably 5000 to 15000 ppm. At this time, the region surface average roughness (Sa) of the surface layer B is preferably in the range of 1 to 40 nm. More preferably, it is in the range of 5 to 35 nm. When the total amount of silica particles and / or calcium carbonate particles in the surface layer B is 5000 ppm or more and Sa is 1 nm or more, air can be uniformly released when the film is rolled up in a roll shape, and the rolled shape is good. The good flatness makes it suitable for manufacturing ultra-thin ceramic green sheets. Further, when the total amount of silica particles and / or calcium carbonate particles is 15,000 ppm or less and Sa is 40 nm or less, the lubricant is unlikely to aggregate and coarse protrusions cannot be formed. Therefore, the ultrathin ceramic green sheet is wound up after molding. Even in this case, it is preferable that the ceramic green sheet does not cause defects such as pinholes.

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

The average particle size 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 size of the particles is 0.1 μm or more, the slipperiness of the release film is good, which is preferable. Further, when the average particle size is 2.0 μm or less, pinholes due to coarse particles are not likely to occur on the surface of the release layer, which is preferable. The average particle size of the particles is measured by observing the particles in the cross section of the processed film with a scanning electron microscope, observing 100 particles, and using the average value as the average particle size. Can be done. The shape of the particles is not particularly limited as long as it satisfies the object of the present invention, and spherical particles and irregular non-spherical particles can be used. The particle size of the amorphous particles can be calculated as the equivalent circle diameter. The equivalent circle diameter is a value obtained by dividing the observed particle area by the pi (π), calculating the square root, and doubling it.

The surface layer B may contain two or more types of particles having different materials. Further, particles of the same type having different average particle diameters may be contained.

When the surface layer B does not contain particles, it is also preferable that a coat layer containing particles on the surface layer B has slipperiness. The means for providing the coating layer is not particularly limited, but it is preferable to provide the coating layer by a so-called in-line coating method in which the coating is applied during the film formation of the polyester film. Further, when a coat layer having a slipperiness is provided on the surface of the polyester film on the side where the release layer is not laminated, the polyester film does not need to have the surface layers A and B, and the inorganic particles are substantially contained. It may consist of a single-layer polyester film that does not contain the material.

The region surface average roughness (Sa) of the surface layer B is preferably 40 nm or less, more preferably 35 nm or less, and further preferably 30 nm or less. Further, when the surface layer B or the surface on the side where the release layer of the single-layer polyester film is not laminated is provided with the slipperiness by the coat layer (D), the surface Sa of the surface is measured by measuring the surface on which the coat layer is laminated. It is preferable that the surface layer B is in the same range as the region surface average roughness (Sa).

(Coat layer D)
It is preferable that at least a binder resin and particles are contained in the coat layer D on the surface of the polyester film on the side where the release layer is not laminated.

(Binder resin of coat layer D)
The binder resin constituting the slippery coating layer is not particularly limited, but specific examples of the polymer include polyester resin, acrylic resin, urethane resin, polyvinyl-based resin (polyvinyl alcohol, etc.), polyalkylene glycol, polyalkyleneimine, and methyl cellulose. , Hydroxycellulose, starches and the like. Among these, it is preferable to use polyester resin, acrylic resin, or urethane resin from the viewpoint of particle retention and adhesion. Further, a polyester resin is particularly preferable in consideration of compatibility with a polyester film. The polyester of the binder is preferably a copolymerized polyester in order to achieve solubility in a solvent, dispersibility, and adhesion to a base film and other layers. The polyester resin may be modified with polyurethane. Further, as another preferable binder resin constituting the I Ching coating layer on the polyester base film, urethane resin can be mentioned. Examples of the urethane resin include polycarbonate polyurethane resin. Further, the polyester resin and the polyurethane resin may be used in combination, or the other binder resin described above may be used in combination.

(Crosslinking agent for coat layer D)
In the present invention, in order to form a crosslinked structure in the easy-slip coating layer, the easy-slip coating layer may be formed by containing a cross-linking agent. By containing a cross-linking agent, it becomes possible to further improve the adhesion under high temperature and high humidity. Specific examples of the cross-linking agent include urea-based, epoxy-based, melamine-based, isocyanate-based, oxazoline-based, carbodiimide-based, and aziridine. Further, in order to promote the cross-linking reaction, a catalyst or the like can be appropriately used as needed.

(Particles in coat layer D)
The slippery coating layer preferably contains lubricant particles in order to impart slipperiness to the surface. The particles may be inorganic particles or organic particles, and are not particularly limited. (1) Silica, kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, Barium Sulfate, Carbon Black, Zinc Oxide, Zinc Sulfate, Zinc Carbonate, Zinc Oxide, Titanium Dioxide, Satin White, Aluminum Silate, Kaiso Soil, Calcium Sirate, Aluminum Hydroxide, Hydrate Halloysite, Calcium Carbonate, Magnesium Carbonate, Calcium Phosphate Inorganic particles such as magnesium and barium sulfate, (2) Acrylic or methacrylic, vinyl chloride, vinyl acetate, nylon, styrene / acrylic, styrene / butadiene, polystyrene / acrylic, polystyrene / isoprene, polystyrene / Organic particles such as isoprene-based, methyl methacrylate / butyl methacrylate-based, melamine-based, polycarbonate-based, urea-based, epoxy-based, urethane-based, phenol-based, diallyl phthalate-based, and polyester-based are suitable for the coating layer. Silica is particularly preferably used to provide slipperiness.

The average particle size of the particles is preferably 10 nm or more, more preferably 20 nm or more, still more preferably 30 nm or more. It is preferable that the average particle size of the particles is 10 nm or more because it is difficult to aggregate and slipperiness can be ensured.

The average particle size of the particles is preferably 1000 nm or less, more preferably 800 nm or less, still more preferably 600 nm or less. When the average particle size of the particles is 1000 nm or less, transparency is maintained and the particles do not fall off, which is preferable.

Further, for example, it is also possible to mix small particles having an average particle size of about 10 to 270 nm and large particles having an average particle size of about 300 to 1000 nm, which will be described later in terms of region surface average roughness (Sa) and maximum protrusion height (Sa). It is preferable to reduce the average length (RSm) of the roughness curve element while keeping Rp) small to achieve both slipperiness and smoothness, and particularly preferably, small particles of 30 nm or more and 250 nm or less and average particles. Large particles with a diameter of 350 to 600 nm are used in combination. When small particles and large particles are mixed, it is preferable that the mass content of the small particles is larger than the mass content of the large particles with respect to the total solid content of the coating layer.

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

The thickness ratio of the surface layer A, which is the layer on which the release layer is provided, is preferably 20% or more and 50% or less of the total thickness of the base film. If it is 20% or more, it is not easily affected by the particles contained in the surface layer B or the like from the inside of the film, and it is easy for the region surface average roughness Sa to satisfy the above range, which is preferable. When it is 50% or less of the thickness of all the layers of the base film, the ratio of the recycled raw material used in the surface layer B can be increased, and the environmental load is small, which is preferable.

Further, from the viewpoint of economy, 50 to 90% by mass of film waste or a recycled raw material for PET bottles can be used for the layers other than the surface layer A (surface layer B or the core layer C described above). Even in this case, it is preferable that the type and amount of the lubricant contained in the surface layer B, the particle size, and the region surface average roughness (Sa) satisfy the above ranges.

In addition, a film before or after uniaxial stretching in the film forming process on the surface of the surface layer A and / or the surface layer B in order to improve the adhesion of the release layer to be applied later and prevent charging. A coat layer may be provided on the surface, or a corona treatment or the like may be applied. When a coat layer is also provided, the (Sa) of each layer is substituted by the measured value on the surface of the coat layer. Further, when these coat layers are provided on the surface of the surface layer A, it is preferable that they do not contain particles.

(Release layer)
The release layer in the present invention is preferably formed by curing a coating film containing at least an energy ray-curable compound (I), a polyester resin (II), and a release component (III). Since the energy ray-curable compound (I) and the polyester resin (II) are phase-separated to form a sea-island structure, unevenness of an appropriate height due to low protrusions can be easily formed, and coarse protrusions do not occur. No pinholes are generated on the molded green sheet. In addition, since the flat surface is reduced due to the appropriate unevenness, the stress at the time of cutting is easily released during the half-cut test of the green sheet, and point peeling (small peeling that naturally occurs at the end) occurs at the cut end. Damage such as cracks and deformation at the end can be suppressed, and peeling can be performed smoothly by triggering peeling in the peeling step of the next step.

(Energy ray-curable compound (I))
As the energy ray-curable compound (I) used in the present invention, an energy ray-curable compound having 3 or more reactive groups in one molecule can be used. By having 3 or more reactive groups in one molecule, it becomes a release layer having a high elastic modulus, deformation of the release layer at the time of peeling the green sheet can be suppressed, and heavy peeling can be suppressed, which is preferable. Further, since the solvent resistance of the release layer can be improved, erosion of the release layer by the solvent during slurry coating can be prevented, which is preferable. Further, the energy ray-curable compound having 3 or more reactive groups in one molecule is not particularly limited as to whether it reacts directly with energy rays or with an indirectly generated active species. The content of the energy ray-curable compound (I) in the solid content in the coating liquid for forming the release layer is preferably 60 to 98% by mass, preferably 75 to 97% by mass. By adding 60% by mass or more, the degree of cross-linking can be maintained and a high elastic modulus can be obtained.

Examples of the reactive group of the energy ray-curable compound (I) include (meth) acryloyl group, alkenyl group, acrylamide group, maleimide group, epoxy group, cyclohexene oxide group and the like. Among them, an energy ray-curable compound having a (meth) acryloyl group having excellent processability is preferable.

The energy ray-curable compound having a (meth) acryloyl group is not limited to a monomer, an oligomer, and a polymer, and can be used. Further, it is preferable that at least one molecule contains a compound having 3 or more reactive groups, but 2 or more compounds such as a compound having 1 to 2 reactive groups in the molecule are mixed and used. You can also do it. By mixing these compounds having a small number of reactive groups, curling and the like can be suppressed.

Examples of the energy ray-curable monomer having 3 or more (meth) acryloyl groups in the molecule include isocyanuric acid triacrylate, glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and tri. Methylolpropantri (meth) acrylate, ditrimethylolpropanetetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) ) Polyfunctional (meth) acrylates such as acrylates and their ethylene oxide modified products, propylene oxide modified products, caprolactone modified products and the like can be mentioned.

Examples of the energy ray-curable monomer having 1 to 2 reactive groups in the molecule include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and butyl (meth) acrylate. Isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, cyclopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, Nonyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, isobornyl (meth) acrylate, cyclic trimethylolpropaneholemar (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxybutyl (Meta) acrylate, hydroxypropyl (meth) acrylate, (meth) acrylic acid, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, Tetrahydrofurfuryl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, pentamethylpiperidinyl (meth) acrylate, tetramethylpiperidinyl (meth) acrylate, 1,4-butanediol di (meth) acrylate, polyethylene glycol Monomers such as di (meth) acrylate, nonanediol di (meth) acrylate, bisphenol A di (meth) acrylate, neopentyl glycol di (meth) acrylate, cyclohexanediol di (meth) acrylate and their ethylene oxide modified products, Examples thereof include propylene oxide modified products and caprolactone modified products.

Examples of energy ray-curable oligomers having 3 or more (meth) acryloyl groups in the molecule include urethane acrylates, polyester acrylates, polyether acrylates, epoxy acrylates, silicone-modified acrylates, and the like, which are generally commercially available. Can be used. For example, Arakawa Chemical Industry Co., Ltd. Beam Set (registered trademark) series, Shin Nakamura Chemical Industry Co., Ltd. NK Oligo series, Dicelle Ornex Co., Ltd. EBECRYL series, Osaka Organic Chemical Industry Co., Ltd. Viscoat series, Kyoei Co., Ltd. Chemical Company urethane acrylate series, Examples include the Unidic series manufactured by DIC.

Examples of energy ray-curable polymers having three or more (meth) acryloyl groups in the molecule include graft polymers obtained by grafting (meth) acryloyl groups on the polymers, and block polymers in which a polyfunctional acrylic monomer is added to the polymer ends. Can be mentioned. As the polymers as described above, acrylic resin, epoxy resin, polyester resin, polyorganosiloxane and the like can be used, and the present invention is not particularly limited.

(Polyester resin (II))
As the polyester resin (II) used in the present invention, a polyester resin containing an ester structural unit derived from the 5-sodium sulfoisophthalic acid component can be used. The ester constituent units derived from the 5-sodium sulfoisophthalic acid component are 5-sodium sulfoisophthalic acid, ethylene glycol, diethylene glycol, propanediol, 1,4-butanediol, opentyl glycol, and 1.4-cyclohexanedimethanol. , 1,6-Hexanediol or the like, which is an ester constituent unit composed of any diol and glycol component, and means that this ester constituent unit is contained in the polyester resin. The mode of containing the ester constituent unit derived from the 5-sodium sulfoisophthalic acid component in the polyester resin may be a mixed state with another ester constituent unit or polyester, or a copolymerized state with another ester constituent unit. It is a particularly preferable embodiment that the polyester resin (II) is a copolymerized polyester containing an ester structural unit derived from a 5-sodium sulfoisophthalic acid component. Since the polyester resin (II) contains an ester structural unit derived from the 5-sodium sulfoisophthalic acid component, the compatibility with the energy ray-curable compound (I) is reduced, and the surface unevenness due to the sea-island structure suitable for the release layer is reduced. Is preferable because it facilitates formation. The content of the ester constituent unit derived from the 5-sodium sulfoisophthalic acid component in the polyester resin (II) is 0.5 mol% when all the ester constituent units constituting the polyester resin (II) are 100 mol%. It is preferably 12 mol% or more and 12 mol% or less. When it is 0.5 mol% or more, the compatibility with the energy ray-curable compound (I) is lowered, and surface unevenness due to an appropriate sea-island structure is easily formed on the release layer, which is preferable. On the other hand, when it is 12 mol% or less, the SP value of the solvent in which the polyester resin (II) can be dissolved does not become too high, the energy ray-curable compound (I) is relatively easy to dissolve in the solvent, and the coating is applied. It is preferable because the liquid can be easily prepared. The content of the ester constituent unit derived from the 5-sodium sulfoisophthalic acid component in the polyester resin (II) is more preferably 1 mol% or more and 10 mol% or less.

The polyester resin (II) may be a single polyester resin, or two or more types of polyester resins may be used at the same time. When two or more kinds of polyester resins are used, the other polyester resins are not particularly limited as long as at least one kind of polyester resin contains an ester structural unit derived from the 5-sodium sulfoisophthalic acid component. The content of the polyester resin (II) in the coating liquid for forming a release layer is preferably 1 to 40% by mass, more preferably 1 to 10% by mass. Sufficient surface unevenness can be formed by containing 1% by mass or more, and the degree of cross-linking of the release layer by the energy ray-curable compound (I) increases by containing 40% by mass or less, and the temperature at the time of peeling. It has low dependence and is preferable.

As the polyester resin (II), a commercially available one can be used as long as it contains an ester constituent unit derived from the 5-sodium sulfoisophthalic acid component. For example, Toyobo Co., Ltd.'s Byron (registered trademark) series and Nippon Synthetic Chemical Industry Co., Ltd.'s Nichigo Polyester (registered trademark) series can be mentioned.

(Release component (III))
The release component (III) used in the present invention is not particularly limited as long as it is a material capable of exhibiting releasability with a green sheet such as polyorganosiloxane, fluorine compound, long-chain alkyl compound, and waxes. Further, a material having a functional group capable of reacting with and binding to the energy ray-curable compound (I) having a (meth) acryloyl group or the like is preferable. It is also possible to use a mixture of two or more kinds of materials. The content of the release component (III) in the solid content of the release layer forming coating liquid is preferably 0.05 to 10% by mass, more preferably 0.1 to 5% by mass. If it is added in an amount of 0.05% by mass or more, the peeling force can be lightened, and if it is 10% by mass or less, the transfer of the release component to a ceramic green sheet or the like can be suppressed, which is preferable.

Examples of polyorganosiloxane include polydimethylsiloxane, polydiethylsiloxane, polyphenylsiloxane, and other siloxane-based compounds that are partially organically modified, block polymers that have polyorganosiloxane, and polymers that are grafted with polyorganosiloxane. Can be used. As commercially available products, for example, BYK (registered trademark) series manufactured by Big Chemie Japan, Modiper (registered trademark) series manufactured by NOF Corporation, and the like can be used.

The fluorine compound is not particularly limited, and commercially available ones can be used. For example, the Mega Fvck (registered trademark) series manufactured by DIC Corporation can be mentioned.

Examples of the long-chain alkyl compound include an acrylic polymer copolymerized with a long-chain alkyl acrylate, a graft polymer grafted with a long-chain alkyl, and a block polymer having a long-chain alkyl added to the end. Further, the product is not particularly limited, and a commercially available product can be used. For example, Tessfine (registered trademark) series manufactured by Hitachi Kasei Co., Ltd. and Piroyl (registered trademark) manufactured by Lion Specialty Chemicals Co., Ltd. can be mentioned.

Examples of the active energy ray include electromagnetic waves such as infrared rays, visible rays, ultraviolet rays, and X-rays, electron beams, ion beams, neutron beams, particle beams such as α rays, and the like. It is preferable to use excellent ultraviolet rays.

The atmosphere when irradiating the active energy rays may be general air or a nitrogen gas atmosphere. In a nitrogen gas atmosphere, the radical reaction proceeds smoothly and the elastic modulus of the release layer can be improved by reducing the oxygen concentration, but if there is no practical problem even if it is irradiated in air, it is irradiated in air. It is preferable from an economic point of view.

(Photopolymerization initiator)
When a radical polymerization compound is used for the release layer of the present invention, it is preferable to add a photopolymerization initiator. Specific examples of the photopolymerization initiator include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, methyl benzoin benzoate, benzoin dimethyl ketal, 2,4. -Diethylthioxanson, 1-hydroxycyclohexylphenylketone, benzyldiphenylsulfide, tetramethylthium monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, (2,4,6-trimethyl) Benzyldiphenyl) phosphine oxide, 2-benzothiazole-N, N-diethyldithiocarbamate and the like can be mentioned. In particular, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methylpropan-1-one, which is said to have excellent surface curability, 1-Hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 -On is preferable, and 2-hydroxy-2-methyl-1-phenyl-propane-1-one and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one are particularly preferable. preferable. These may be used alone or in combination of two or more.

The amount of the photopolymerization initiator added is not particularly limited, but for example, it is preferably contained in an amount of about 0.1 to 20% by mass as the solid content in the coating liquid for forming a release layer.

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

An adhesion improver, an additive such as an antistatic agent, or the like may be added to the release layer in the present invention as long as the effect of the present invention is not impaired. Further, in order to improve the adhesion to the base material, it is also preferable to perform pretreatment such as anchor coating, corona treatment, plasma treatment, and atmospheric pressure plasma treatment on the surface of the polyester film before providing the release coating layer.

In the present invention, the thickness of the release layer may be set according to the purpose of use and is not particularly limited, but preferably, the release layer after curing is preferably in the range of 0.2 to 3.5 μm. More preferably, it is 0.5 to 3.0 μm. When the thickness of the release layer is 0.2 μm or more, the curability of the energy ray-curable copolymer polymer is good, and the elastic modulus of the release layer is improved, so that good peeling performance can be obtained, which is preferable. Further, when the thickness is 3.5 μm or less, curling is unlikely to occur even if the thickness of the release film is thin, and the ceramic green sheet is preferably formed and dried without causing poor running performance.

In the release film of the present invention, it is preferable that the surface of the release layer has appropriate irregularities. Therefore, the region surface average roughness (Sa) on the surface of the release layer is preferably 5 to 40 nm. Further, it is more preferable that the Sa is satisfied and the maximum protrusion height (Rp) on the surface of the release layer is 60 nm or less. The region surface average roughness (Sa) is preferably 5 to 20 nm, and at the same time, the maximum protrusion height (Rp) is more preferably 50 nm or less. The region surface average roughness (Sa) is particularly preferably 8.1 to 18 nm, and most preferably 8.5 to 17 nm. When the region surface average roughness (Sa) is 5 nm or more, zipping is reduced when the ceramic green sheet is peeled off, and even an ultrathin layer green sheet can be easily peeled off without damage. Further, when the region surface average roughness (Sa) is 40 nm or less, it is sufficiently smaller than the particle size of the ceramic and does not affect the surface shape of the green sheet. When the Sa is satisfied and the maximum protrusion height (Rp) of the release layer surface is 60 nm or less, the possibility of further pinhole defects is further reduced, which is preferable. The maximum protrusion height (Rp) is preferably small, but the maximum protrusion height (Rp) may be 5 nm or more in relation to adjusting the region surface average roughness (Sa) to 5 nm or more, and is 10 nm or more. It doesn't matter. Various factors are involved in adjusting the range of the region surface average roughness (Sa) and the maximum protrusion height (Rp) of the release layer as described above, but mainly the surface of the polyester film. Since the layer A or the single-layer polyester film does not substantially contain inorganic particles, the surface roughness on which the release layer is laminated is small, and the release layer has three or more reactive groups in one molecule. It contains an energy ray-curable compound (I) and a resin (II) containing the energy ray-curable compound (I) as a sea component and being incompatible with the energy ray-curable compound (I) and serving as an island component. It can be said that it is related to being cured. The method of adjusting the region surface average roughness (Sa) and the maximum protrusion height (Rp) of the release layer to an appropriate range as described above is not particularly limited, but mainly with the energy ray-curable compound (I). This can be preferably achieved by adjusting the combination of the materials of the resin (II) and the content ratio.

In the present invention, the method for forming the release layer is not particularly limited, and a coating liquid in which a releaseable compound is dissolved or dispersed is developed by coating or the like on one surface of a polyester film of a base material, and a solvent or the like is formed. Is removed by drying and then cured.

When the release layer of the present invention is applied onto the base film by solution coating, the drying temperature of solvent drying is preferably 50 ° C. or higher and 120 ° C. or lower, and 60 ° C. or higher and 100 ° C. or lower. More preferred. The drying time is preferably 30 seconds or less, more preferably 20 seconds or less. Further, after drying with a solvent, it is preferable to irradiate with active energy rays to proceed with the curing reaction. As the active energy beam used at this time, ultraviolet rays, electron beams, X-rays and the like can be used, but ultraviolet rays are preferable because they are easy to use. The amount of ultraviolet rays to be irradiated is preferably 30 to 300 mJ / cm ² in terms of the amount of light, and more preferably 30 to 200 mJ / cm ² . When the temperature is 30 mJ / cm ² or more, the composition is sufficiently cured, and when the temperature is 300 mJ / cm ² or less, the processing speed can be improved, so that a release film can be economically produced. preferable.

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

Any known coating method can be applied as the coating method, for example, a roll coating method such as a gravure coating method or a reverse coating method, a bar coating method such as a wire bar, a die coating method, a spray coating method, or an air knife. Conventionally known methods such as the coating method can be used.

In order to explain the present invention in detail, examples will be given below, but the present invention is not limited to these examples. The characteristic values used in the present invention were evaluated using the following method. Hereinafter, the weight average molecular weight may be simply referred to as Mw.

(1) Base film thickness Using a millitron (electronic micro-indicator), cut four 5 cm square samples from any four points of the film to be measured, measure each five points (20 points in total), and measure the average value. Was taken as the thickness.

(2) Thickness of release layer The thickness of the release layer was measured using a light interference type film thickness meter (F20, manufactured by Filmometry). (The refractive index of the release layer is calculated as 1.52)

(3) Area surface average roughness (Sa), maximum protrusion height (Rp)
It is a value measured under the following conditions using a non-contact surface shape measurement system (VertScan R550H-M100, manufactured by Ryoka System Co., Ltd.). The region surface average roughness (Sa) was measured 5 times, and the maximum protrusion height (Rp) was measured 7 times, and the maximum value of 5 times excluding the maximum value and the minimum value was used.
(Measurement condition)
・ Measurement mode: WAVE mode ・ Objective lens: 50x ・ 0.5 × Tube lens (analysis conditions)
・ Surface correction: 4th order correction ・ Interpolation processing: Complete interpolation

(4) Phase Separation Structure Using an electron microscope (VE-8800, manufactured by KEYENCE CORPORATION), the surface of the release layer was observed at 5000 times to evaluate the presence or absence of phase separation.

◯: Phase separation is formed (concave and convex structure due to phase separation can be confirmed)
X: No phase separation (no uneven structure due to phase separation)

(5) Half-cut evaluation of ceramic green sheet The composition consisting of the following materials was stirred and mixed, and dispersed for 60 minutes using a bead mill using zirconia beads having a diameter of 0.5 mm as a dispersion medium to prepare a ceramic slurry.
Toluene 76.3 parts by mass Ethanol 76.3 parts by mass Barium titanate (HPBT-1 manufactured by Fuji Titanium Industry Co., Ltd.) 35.0 parts by mass Polyvinyl butyral 3.5 parts by mass (Sekisui Chemical Co., Ltd. Eslek (registered trademark) BM-S )
DOP (Dioctyl Phthalate) 1.8 parts by mass Then, the release surface of the release film sample was coated with an applicator so that the dried ceramic green sheet was 1.0 μm, and dried at 90 ° C. for 2 minutes.
Using a rotary die cutter (RDC (FB) -A4, manufactured by Tsukaya Komono Seisakusho Co., Ltd.), the obtained release film with a ceramic green sheet was 16 mm x 32 mm at 50 ° on both blades from the surface side of the ceramic green sheet. It was half-cut so that the angle and depth were 3 μm. For the portion where the green sheet was peeled off, the distance from the edge portion of the film to the peeled portion was measured with a laser microscope and determined according to the following criteria. The measurement was performed 5 times and the average value was adopted.
◯: There are no defects such as cracks at the end, and there is a sufficient peeling part (reference: the distance reached by the peeling is 4 mm or more from the end).
Δ: There are no defects such as cracks at the end, and there is a little peeling part (reference: the distance reached by the peeling is 1 mm or more and less than 4 mm from the end).
X: There is a defect such as a crack at the end, or there is no peeling part (reference: the distance reached by the peeling is less than 1 mm from the end)

(Preparation of polyethylene terephthalate pellets (PET (1)))
As the esterification reaction device, a continuous esterification reaction device consisting of a stirrer, a splitter, a raw material charging port, and a three-stage complete mixing tank having a raw material charging port and a product outlet was used. TPA (terephthalic acid) was set to 2 tons / hour, EG (ethylene glycol) was set to 2 mol per 1 mol of TPA, antimony trioxide was set to an amount of 160 ppm of Sb atoms with respect to the PET produced, and these slurries were esterified. It was continuously supplied to the first esterification reaction can of the chemical reaction apparatus and reacted at normal pressure for an average residence time of 4 hours and 255 ° C. Next, the reaction product in the first esterification reaction can is continuously taken out of the system and supplied to the second esterification reaction can, and distilled off from the first esterification reaction can in the second esterification reaction can. EG is supplied in an amount of 8% by mass with respect to the produced PET, and an EG solution containing an amount of magnesium acetate tetrahydrate having an amount of Mg atoms of 65 ppm with respect to the produced PET and 40 ppm of P atoms with respect to the produced PET. An EG solution containing an amount of TMPA (trimethyl phosphate) was added, and the reaction was carried out at normal pressure for an average residence time of 1 hour and 260 ° C. Next, the reaction product of the second esterification reaction can is continuously taken out of the system and supplied to the third esterification reaction can, and is 39 MPa (400 kg / cm2) using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.). 0.2% by mass of porous colloidal silica having an average particle size of 0.9 μm after dispersion treatment with an average number of treatments of 5 passes under pressure, and 1% by mass of ammonium salt of polyacrylic acid attached per calcium carbonate. The reaction was carried out at normal pressure for an average residence time of 0.5 hours and 260 ° C. while adding 0.4% by mass of synthetic calcium carbonate having an ester value of 0.6 μm as a 10% EG slurry. The esterification reaction product produced in the third esterification reaction can was continuously supplied to a three-stage continuous polycondensation reaction apparatus to carry out polycondensation, and a stainless steel fiber having a 95% cut diameter of 20 μm was sintered. After filtering with a filter, ultrafiltration was performed, extruded into water, cooled, and then cut into chips to obtain PET chips having an intrinsic viscosity of 0.60 dl / g (hereinafter abbreviated as PET (1)). .. The lubricant content in the PET chip was 0.6% by mass.

(Preparation of polyethylene terephthalate pellets (PET (2)))
On the other hand, in the production of the PET chip, a PET chip having an intrinsic viscosity of 0.62 dl / g containing no particles such as calcium carbonate and silica was obtained (hereinafter, abbreviated as PET (2)).

(Manufacturing of laminated film X1)
After drying these PET chips, they are melted at 285 ° C., melted at 290 ° C. by a separate melt extruder extruder, and a filter obtained by sintering stainless steel fibers having a 95% cut diameter of 15 μm and a 95% cut diameter are obtained. Two-stage filtration of a filter obtained by sintering 15 μm stainless steel particles is performed, and the PET (1) is combined with the surface layer B (extrusion type surface side layer) and the PET (2) is surfaced. It is laminated so as to be layer A (separation surface side layer), extruded (casting) into a sheet at a speed of 45 m / min, and electrostatically adhered and cooled on a casting drum at 30 ° C. by the electrostatic adhesion method. An unstretched polyethylene terephthalate sheet having an intrinsic viscosity of 0.59 dl / g was obtained. The layer ratio was adjusted so that PET (1) / (2) = 60% / 40% in the discharge amount calculation of each extruder. Next, the unstretched sheet was heated with an infrared heater and then stretched 3.5 times in the vertical direction at a roll temperature of 80 ° C. due to the speed difference between the rolls. Then, it was guided to a tenter and stretched 4.2 times in the lateral direction at 140 ° C. Then, in the heat fixing zone, heat treatment was performed at 210 ° C. Then, a 2.3% relaxation treatment was carried out in the transverse direction at 170 ° C. to obtain a biaxially stretched polyethylene terephthalate film X1 having a thickness of 31 μm. The Sa of the surface layer A of the obtained film X1 was 2 nm, and the Sa of the surface layer B was 29 nm.

(Example 1)
A coating liquid 1 having the following composition is applied onto the surface layer A of the laminated film X1 using reverse gravure so that the release layer thickness after drying is 2.5 μm, dried at 90 ° C. for 30 seconds, and then subjected to high pressure. A release film for producing an ultrathin ceramic green sheet was obtained by irradiating ultraviolet rays at 200 mJ / cm ² using a mercury lamp. The obtained release film was evaluated for the thickness of the release layer, the area surface average roughness Sa, the maximum protrusion height Rp, the phase separation structure, and the trigger for peeling of the ceramic green sheet at the time of half-cutting.

(Coating liquid 1)
Compound (I) Dipentaerythritol Hexaacrylate
100.00 parts by mass
(NK ester (registered trademark) A-DPH, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., hexafunctional acrylate, solid content concentration 100%)
Resin (II) Polyester resin (A) 9.45 parts by mass Release agent (III) 1.26 parts by mass (modified polydimethylsiloxane having an acryloyl group, BYK-UV3505, manufactured by Big Chemie Japan, solid content concentration 40% by mass %)
Photopolymerization initiator 5.25 parts by mass (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK, solid content concentration 100% by mass)
Diluting solvent (MEK / toluene = 1/1) 431.30 parts by mass

As the polyester resin (A), a polyester resin copolymerized with the following composition was used.
Monomer composition: (acid component) terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / diethylene glycol = 49 / 48.5 / 2.5 // 50/50 (mol%)

(Example 2)
Compared with Example 1, the polyester resin (B) was changed and the following coating liquid 2 was used. A release film was obtained in the same manner as in Example 1 except that the coating liquid 2 was used. The obtained release film was evaluated for the thickness of the release layer, the area surface average roughness Sa, the maximum protrusion height Rp, the phase separation structure, and the trigger for peeling of the ceramic green sheet at the time of half-cutting.

(Coating liquid 2)
Compound (I) Dipentaerythritol Hexaacrylate
100.00 parts by mass
(NK ester (registered trademark) A-DPH, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., hexafunctional acrylate, solid content concentration 100%)
Resin (II) Polyester resin (B) 9.45 parts by mass
Release agent (III) 1.26 parts by mass (modified polydimethylsiloxane having an acryloyl group, BYK-UV3505 manufactured by Big Chemie Japan, solid content concentration 40% by mass)
Photopolymerization initiator 5.25 parts by mass (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK, solid content concentration 100% by mass)
Diluting solvent (MEK / toluene = 1/1) 431.30 parts by mass

As the polyester resin (B), a polyester resin copolymerized with the following composition was used.
Monomer composition: (acid component) terephthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / propanediol / trimethylolpropane = 97.5 / 2.5 // 20/79.2 / 0.8 (Mol%)

(Example 3)
Compared with Example 1, the polyester resin (II) and the diluting solvent were changed, and the following coating liquid 3 was used. A release film was obtained in the same manner as in Example 1 except that the coating liquid 3 was used. The obtained release film was evaluated for the thickness of the release layer, the area surface average roughness Sa, the maximum protrusion height Rp, the phase separation structure, and the trigger for peeling of the ceramic green sheet at the time of half-cutting.

(Coating liquid 3)
Compound (I) Dipentaerythritol Hexaacrylate
100.00 parts by mass
(NK ester (registered trademark) A-DPH, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., hexafunctional acrylate, solid content concentration 100%)
Resin (II) Polyester resin (C) 9.45 parts by mass
Release agent (III) 1.26 parts by mass (modified polydimethylsiloxane having an acryloyl group, BYK-UV3505, manufactured by Big Chemie Japan, solid content concentration 40% by mass)
Photopolymerization initiator 5.25 parts by mass (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK, solid content concentration 100% by mass)
Diluting solvent (cyclopentanone) 431.30 parts by mass

As the polyester resin (C), a polyester resin copolymerized with the following composition was used.
Monomer composition: (acid component) terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / diethylene glycol = 48/48/4 // 80/20 (mol%)

(Example 4)
Compared with Example 1, the polyester resin (II) and the diluting solvent were changed, and the following coating liquid 4 was used. A release film was obtained in the same manner as in Example 1 except that the coating liquid 4 was used. The obtained release film was evaluated for the thickness of the release layer, the area surface average roughness Sa, the maximum protrusion height Rp, the phase separation structure, and the trigger for peeling of the ceramic green sheet at the time of half-cutting.

(Coating liquid 4)
Compound (I) Dipentaerythritol Hexaacrylate
100.00 parts by mass
(NK ester (registered trademark) A-DPH, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., hexafunctional acrylate, solid content concentration 100%)
Resin (II) Polyester resin (D) 9.45 parts by mass
Release agent (III) 1.26 parts by mass (modified polydimethylsiloxane having an acryloyl group, BYK-UV3505, manufactured by Big Chemie Japan, solid content concentration 40% by mass)
Photopolymerization initiator 5.25 parts by mass (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK, solid content concentration 100% by mass)
Diluting solvent (cyclopentanone) 431.30 parts by mass

As the polyester resin (D), a polyester resin copolymerized with the following composition was used.
Monomer composition: (acid component) isophthalic acid / 5-sodium sulfoisophthalic acid // (diol component) diethylene glycol = 93/7 // 100 (mol%)

(Comparative Example 1)
Compared with Example 1, the polyester resin (II) was changed and the following coating liquid 5 was used. A release film was obtained in the same manner as in Example 1 except that the coating liquid 5 was used. The obtained release film was evaluated for the release layer thickness, the region surface average roughness Sa, the maximum protrusion height Rp, the phase separation structure, and the peeling trigger at the time of half-cutting of the ceramic green sheet.

(Coating liquid 5)
Compound (I) Dipentaerythritol Hexaacrylate
100.00 parts by mass
(NK ester (registered trademark) A-DPH, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., hexafunctional acrylate, solid content concentration 100%)
Resin (II) Polyester resin (E) 9.45 parts by mass
Release agent (III) 1.26 parts by mass (modified polydimethylsiloxane having an acryloyl group, BYK-UV3505, manufactured by Big Chemie Japan, solid content concentration 40% by mass)
Photopolymerization initiator 5.25 parts by mass (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK, solid content concentration 100% by mass)
Diluting solvent (MEK / toluene = 1/1) 431.30 parts by mass

As the polyester resin (E), a polyester resin copolymerized with the following composition was used.
Monomer composition: (acid component) terephthalic acid / isophthalic acid // (diol component) ethylene glycol / neopentyl glycol = 50/50 // 50/50 (mol%)

(Comparative Example 2)
Compared with Example 1, the polyester resin (II) was changed and the following coating liquid 5 was used. A release film was obtained in the same manner as in Example 1 except that the coating liquid 5 was used. With respect to the obtained release film, the thickness of the release layer, the area surface average roughness Sa, the maximum protrusion height Rp, the phase separation structure, and the trigger for peeling of the ceramic green sheet at the time of half-cutting were evaluated.

(Coating liquid 5)
Compound (I) Dipentaerythritol Hexaacrylate
100.00 parts by mass
(NK ester (registered trademark) A-DPH, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., hexafunctional acrylate, solid content concentration 100%)
Resin (II) Polyester resin (F) 9.45 parts by mass
Release agent (III) 1.26 parts by mass (modified polydimethylsiloxane having an acryloyl group, BYK-UV3505, manufactured by Big Chemie Japan, solid content concentration 40% by mass)
Photopolymerization initiator 5.25 parts by mass (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK, solid content concentration 100% by mass)
Diluting solvent (MEK / toluene = 1/1) 431.30 parts by mass

As the polyester resin (F), a polyester resin copolymerized with the following composition was used.
Monomer composition: (acid component) terephthalic acid / isophthalic acid / sebacic acid // (diol component) ethylene glycol / neopentyl glycol = 52/18/30 // 54/46 (mol%)

(Comparative Example 3)
Compared with Example 1, the polyester resin (II) was changed and the following coating liquid 6 was used. A release film was obtained in the same manner as in Example 1 except that the coating liquid 6 was used. The obtained release film was evaluated for the thickness of the release layer, the area surface average roughness Sa, the maximum protrusion height Rp, the phase separation structure, and the trigger for peeling of the ceramic green sheet at the time of half-cutting.

(Coating liquid 6)
Compound (I) Dipentaerythritol Hexaacrylate
100.00 parts by mass
(NK ester (registered trademark) A-DPH, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., hexafunctional acrylate, solid content concentration 100%)
Resin (II) Polyester resin (G) 9.45 parts by mass
Release agent (III) 1.26 parts by mass (modified polydimethylsiloxane having an acryloyl group, BYK-UV3505, manufactured by Big Chemie Japan, solid content concentration 40% by mass)
Photopolymerization initiator 5.25 parts by mass (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK, solid content concentration 100% by mass)
Diluting solvent (MEK / toluene = 1/1) 431.30 parts by mass

As the polyester resin (G), a polyester resin copolymerized with the following composition was used.
Monomer composition: (acid component) terephthalic acid / isophthalic acid / adipic acid / trimellitic acid // (diol component) 2-methyl-1,3-propanediol / butanediol = 40/39/20/1 // 60 / 40 (mol%)

(Comparative Example 4)
Compared with Example 1, the polyester resin (II) was changed and the following coating liquid 7 was used. A release film was obtained in the same manner as in Example 1 except that the coating liquid 7 was used. The obtained release film was evaluated for the thickness of the release layer, the area surface average roughness Sa, the maximum protrusion height Rp, the phase separation structure, and the trigger for peeling of the ceramic green sheet at the time of half-cutting.

(Coating liquid 7)
Compound (I) Dipentaerythritol Hexaacrylate
100.00 parts by mass
(NK ester (registered trademark) A-DPH, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., hexafunctional acrylate, solid content concentration 100%)
Resin (II) Polyester resin (H) 9.45 parts by mass
Release agent (III) 1.26 parts by mass (modified polydimethylsiloxane having an acryloyl group, BYK-UV3505, solid content concentration 40% by mass)
Photopolymerization initiator 5.25 parts by mass (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK, solid content concentration 100% by mass)
Diluting solvent (MEK / toluene = 1/1) 431.30 parts by mass

As the polyester resin (F), a polyester resin copolymerized with the following composition was used.
Monomer composition: (acid component) terephthalic acid / isophthalic acid / azelaic acid // (diol component) ethylene glycol / neopentyl glycol = 30/20/50 // 65/35 (mol%)

The electron micrographs of the release layer surface of Examples 1 and 2 used for evaluating the state of the release layer surface unevenness by the phase-separated structure are shown in FIGS. 1 and 2.

According to the release film for producing a ceramic green sheet of the present invention, the release force does not become too heavy as compared with the conventional release film for producing a ceramic green sheet, the workability is excellent, and the release layer is large. Since there are no protrusions, it has become possible to provide a release film for manufacturing a ceramic green sheet that can reduce defects such as pinholes in an ultra-thin ceramic green sheet having a thickness of 1 μm or less.

Claims (8)

A release film in which a release layer is laminated directly on at least one side of the polyester film or via another layer, and the release layer is an energy ray-curable compound (I), a polyester resin (II), and A release film for producing a ceramic green sheet, wherein the coating film containing at least the release component (III) is cured, and the polyester resin (II) contains an ester structural unit derived from the 5-sodium sulfoisophthalic acid component. The ceramic green sheet for producing the ceramic green sheet according to claim 1, wherein the release layer has a phase-separated structure in which the energy ray-curable compound (I) is a sea component and the polyester resin (II) is an island component, and has surface irregularities. Release film. The release film for producing a ceramic green sheet according to claim 1 or 2, wherein the release layer does not substantially contain inorganic particles. The release film for producing a ceramic green sheet according to any one of claims 1 to 3, wherein the energy ray-curable compound (I) is a (meth) acrylic acid ester having 3 or more acryloyl groups in one molecule. The release film for producing a ceramic green sheet according to any one of claims 1 to 4, wherein the release layer has a thickness of 0.2 to 3.5 μm. The release film for producing a ceramic green sheet according to any one of claims 1 to 5, wherein the region surface average roughness (Sa) of the release layer is 5 to 40 nm. The release film for producing a ceramic green sheet according to any one of claims 1 to 6, wherein the maximum protrusion height (Rp) on the surface of the release layer is 60 nm or less. A method for manufacturing a ceramic green sheet using the release film for manufacturing a ceramic green sheet according to any one of claims 1 to 7, wherein the molded ceramic green sheet is 0.2 μm to 1 A method for producing a ceramic green sheet having a thickness of 0.0 μm.