JP2020049803A - Release film for producing ceramic green sheet and method for evaluating the same - Google Patents

Abstract

To provide a release film for producing a ceramic green sheet capable of suppressing the cissing and pin holes of a ceramic green sheet and also forming a suitable float around a half cut mark upon ceramic half cut, and a method for evaluating the release film for producing a ceramic green sheet.SOLUTION: A release film is obtained by laminating a release layer(s) on at least either side of a polyester film directly or the other layer(s), in which the maximum crest height (Rp) of the surface(s) of the release layer(s) is 60 nm or lower, and, in the case a ceramic green sheet-fitted release film is created and is half-cut, a specified float easiness of a ceramic green sheet is shown. A method for evaluating a release film for producing a ceramic green sheet is performed by a half cut process.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a release film for producing an ultra-thin ceramic green sheet, and more particularly, suppresses the occurrence of process defects due to pinholes and thickness unevenness during the production of an ultra-thin ceramic green sheet, and suppresses the occurrence of ceramic during peeling. The present invention relates to a release film for producing a ceramic green sheet having an ultra-thin layer, which can suppress breakage of a green sheet, and a method for evaluating the same.

  2. Description of the Related Art Conventionally, a release film in which a release layer is laminated on a polyester film as a substrate has been used for forming a ceramic green sheet such as a multilayer ceramic capacitor (hereinafter referred to as MLCC), a ceramic substrate and the like. In recent years, the thickness of ceramic green sheets has tended to be reduced as the size and capacity of multilayer ceramic capacitors have increased. The ceramic green sheet is formed by applying a slurry containing a ceramic component such as barium titanate and a binder resin to a release film and drying the slurry. After printing the electrodes on the molded ceramic green sheet, cutting the ceramic green sheet with the printed electrodes in half and peeling it from the release film, laminating, pressing and cutting the ceramic green sheets, firing, and applying external electrodes By doing so, a multilayer ceramic capacitor is manufactured. Until now, when molding a ceramic green sheet on the release layer surface of a polyester film, minute projections on the release layer surface affect the molded ceramic green sheet, and defects such as cissing and pinholes are likely to occur. There was a problem. Therefore, various techniques for realizing a release layer surface having excellent flatness have been developed (for example, Patent Document 1).

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

  As a method from the release layer side to smooth the release layer surface and to suppress the load on the ceramic green sheet during peeling, the release layer of the release film is formed by using an active energy ray-curable component. In order to increase the cross-linking density and improve the elastic modulus of the ceramic green sheet, measures for suppressing the elastic deformation of the release layer at the time of peeling the ceramic green sheet and reducing the peeling force have been studied (for example, Patent Documents 2 and 3). However, this method has problems such as surface peeling due to too high smoothness, heavy peeling force and poor ceramic peeling such as tearing of the green sheet upon peeling.

JP 2000-117899 A International Publication No. WO 2013/145864 International Publication No. 2013/145865

  Thus, the present inventors have conducted intensive studies and as a result, it has been found that when a ceramic green sheet is half-cut, it is effective to suppress the ceramic peeling defect by causing a certain or more floating of the ceramic green sheet around a half-cut mark. Was found. An object of the present invention is to provide a release film for producing a ceramic green sheet capable of suppressing cissing and pinholes of a ceramic green sheet and forming an appropriate float around a half-cut mark at the time of a ceramic half-cut. Is to provide a way.

That is, the present invention has the following configurations.
1. A release film in which a release layer is laminated on at least one surface of a polyester film directly or via another layer, wherein the maximum peak height (Rp) of the release layer surface is 60 nm or less, and the polyester of the release layer is A ceramic slurry is applied to the surface on the opposite side of the film, and a release film with a ceramic green sheet obtained by drying is created, and the release film with the ceramic green sheet reaches the release film from the ceramic green sheet side, When the half-cut is performed at a depth of 10 μm or less from the surface of the release layer of the release film and the width (B) of the half-cut mark on the surface of the release layer is 50 μm or less, the following expression is obtained. Filling release film for manufacturing ceramic green sheets.
A / B ≧ 20
A: Floating width of ceramic green sheet around half-cut mark (μm)
B: Width of half-cut mark on release layer surface (μm)
2. 2. The release film for producing a ceramic green sheet according to the above 1, wherein the surface average surface roughness (Sa) of the release layer surface is 5 to 40 nm.
3. The ceramic slurry is applied on the release layer of the release film, and the release film with the ceramic green sheet obtained by drying is half-cut from the ceramic green sheet side, and the depth at which the half-cut mark reaches the release film, In addition, the depth (B) of the half-cut mark on the surface of the release layer is 10 μm or less from the surface of the release layer of the release film, and the width (B) of the half-cut mark on the release layer is 50 μm or less. A method for evaluating a release film for producing a ceramic green sheet, which measures the floating width (A) to evaluate the ease of floating of a ceramic green sheet after half-cutting.

  ADVANTAGE OF THE INVENTION According to the release film for ceramic green sheet manufacture of this invention, compared with the conventional release film for ceramic green sheet manufacture, the peeling failure rate in the manufacturing process of the ultra-thin ceramic green sheet whose thickness is 1 micrometer or less is reduced. It has become possible to provide a release film for producing ceramic green sheets which can be reduced. In addition, it was possible to easily evaluate a release film for producing a ceramic green sheet having the above-mentioned characteristics.

It is a plane schematic diagram of a release film with a ceramic green sheet for explaining width (A) of floating of a ceramic green sheet around a half cut mark, and width (B) of a half cut mark on a release layer surface. It is a cross section showing an outline of a half-cut test.

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 it is possible to use a polyester film that is generally used as a release film base film-formed. Preferably, it is a crystalline linear saturated polyester comprising an aromatic dibasic acid component and a diol component. For example, polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, or a mixture thereof. A copolymer containing the resin component as a main component is more preferable, and a polyester film formed from polyethylene terephthalate is particularly preferable. In polyethylene terephthalate, the repeating unit of ethylene terephthalate is preferably at least 90 mol%, more preferably at least 95 mol%, and other dicarboxylic acid components and diol components may be copolymerized in small amounts, but from the viewpoint of cost. And those produced only from terephthalic acid and ethylene glycol. Known additives such as an antioxidant, a light stabilizer, an ultraviolet absorber, and a crystallization agent may be added as long as the effects of the film of the present invention are not impaired. The polyester film is preferably a polyester film because of the high elastic modulus in both directions.

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

  The method for producing the polyester film in the present invention is not particularly limited, and a method generally used conventionally can be used. For example, the polyester can be melted by an extruder, extruded into a film, and obtained by cooling with a rotary cooling drum to obtain an unstretched film, and uniaxially or biaxially stretching the unstretched film. I can do it. A biaxially stretched film can be obtained by a method of sequentially biaxially stretching a longitudinally or transversely uniaxially stretched film in the transverse or longitudinal direction, or a method of simultaneously biaxially stretching an unstretched film in the longitudinal and transverse directions. I can do it.

  In the present invention, the stretching temperature at the time of stretching the polyester film is preferably 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 polyester film preferably has a thickness of 12 to 50 μm, more preferably 12 to 38 μm, and still more preferably 15 to 31 μm. When the thickness of the film is 12 μm or more, there is no possibility of being deformed by heat at the time of film production, processing of a release layer, and molding of a ceramic green sheet, which is preferable. On the other hand, if the thickness of the film is 50 μm or less, the amount of the film to be discarded after use is not extremely large, which is preferable in reducing the environmental load. Further, the material per area of the release film to be used is small. Therefore, it is preferable from an economic viewpoint.

  The polyester film substrate may be a single layer or a multilayer of two or more layers, but may be a laminated polyester film having a surface layer A substantially free of inorganic particles on at least one surface. 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 and the like on the surface opposite to the surface layer A substantially containing no inorganic particles. As for the laminated structure, the layer on the side on which the release layer is applied is the surface layer A, the layer on the opposite side is the surface layer B, and the other core layers are the core layer C. / A surface layer A / a surface layer B or a release layer / a surface layer A / a core layer C / a surface layer B. 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 provide slipperiness for winding the film into a roll.

  In the polyester film substrate of the present invention, the surface layer A forming the surface on which the release layer is applied preferably contains substantially no inorganic particles. At this time, the average surface roughness (Sa) of the surface layer A is preferably 7 nm or less. When Sa is 7 nm or less, even if the release layer has a film thickness of 2.0 μm or less, and even a thin film having a thickness of 0.5 μm or less, pinholes or the like occur when molding the super-thin ceramic green sheets to be laminated. It is difficult and preferable. It can be said that the smaller the area surface average roughness (Sa) of the surface layer A is, the more preferable it is, but it may be 0.1 nm or more. However, when an anchor coat layer or the like described below is provided on the surface layer A, it is preferable that the coat layer contains substantially no inorganic particles, and the area average surface roughness (Sa) after the coat layer is laminated is within the above range. Preferably, there is. In the present invention, "substantially free of inorganic particles" is defined as being 50 ppm or less when the inorganic element is quantified by fluorescent X-ray analysis, preferably 10 ppm or less, most preferably the detection limit or less. Content. This is because even if the inorganic particles are not positively added to the film, the contamination components derived from the foreign matter and the dirt attached to the raw material resin or the line or the device in the manufacturing process of the film are separated and mixed into the film. This is because there are cases.

  In the case where the polyester film substrate in the present invention is a laminated film, the surface layer B forming the opposite surface to the surface layer A on which the release layer is applied has a particle size in view of the slipperiness of the film and the ease of air release. , And particularly preferably silica particles and / or calcium carbonate particles. The content of the particles contained in the surface layer B is preferably 5,000 to 15,000 ppm in total. At this time, the surface average roughness (Sa) of the film of the surface layer B is preferably in the range of 1 to 40 nm. More preferably, it is in the range of 5 to 35 nm. When the total of the silica particles and / or calcium carbonate particles of the surface layer B is 5000 ppm or more and Sa is 1 nm or more, when the film is wound up into a roll, air can be uniformly released and the wound appearance is good. Good flatness makes it suitable for the production of ultra-thin ceramic green sheets. When the total of the silica particles and / or calcium carbonate particles is 15000 ppm or less and Sa is 40 nm or less, the aggregation of the lubricant hardly occurs, and coarse projections cannot be formed. In this case, it is preferable because defects such as pinholes do not occur in the ceramic green sheet.

  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. Inert 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. Can be Examples of the heat-resistant organic particles include crosslinked polyacrylic particles, crosslinked polystyrene particles, and benzoguanamine particles. Further, when using silica particles, porous colloidal silica is preferable, and when using calcium carbonate particles, light calcium carbonate surface-treated with a polyacrylic acid-based polymer compound is preferable from the viewpoint of preventing the lubricant from falling off. .

  The average particle diameter of the particles added to the surface layer B is preferably from 0.1 μm to 2.0 μm, and particularly preferably from 0.5 μm to 1.0 μm. When the average particle diameter 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 diameter is 2.0 μm or less, there is no possibility that pinholes due to coarse particles are generated on the surface of the release layer, which is preferable. The average particle diameter of the particles is measured by observing the particles on the cross section of the processed film with a scanning electron microscope, observing 100 particles, and using the average value as the average particle diameter. Can be. 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 non-spherical particles can be used. The particle diameter of the amorphous particles can be calculated as a circle equivalent diameter. The equivalent circle diameter is a value obtained by dividing the area of the observed particle by the pi (π), calculating the square root, and doubling the square root.

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

  When particles are not contained in the surface layer B, it is also preferable that the coat layer containing the particles on the surface layer B has lubricity. Means for providing the present coat layer is not particularly limited, but is preferably provided by a so-called in-line coating method for applying during the production of a polyester film. In the case where a coat layer having lubricity 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 inorganic particles are substantially contained. It may be composed of a single-layered polyester film which is not contained in the film.

  The average surface roughness (Sa) of the surface layer B is preferably 40 nm or less, more preferably 35 nm or less, and still more preferably 30 nm or less. When the surface of the surface layer B or the surface of the single-layer polyester film on which the release layer is not laminated has a slipperiness with the coating layer (D), the surface Sa is measured by measuring the surface on which the coating layer is laminated. The average surface roughness (Sa) of the surface layer B is preferably in the same range as that described above.

(Coat layer D)
It is preferable that at least the binder resin and the particles are contained in the coat layer D on the surface of the polyester film on which 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 a polyester resin, an acrylic resin, a urethane resin, a polyvinyl resin (eg, polyvinyl alcohol), a polyalkylene glycol, a polyalkyleneimine, and methylcellulose. , Hydroxycellulose, starch and the like. Among these, it is preferable to use a polyester resin, an acrylic resin, or a urethane resin from the viewpoint of retaining particles and adhesion. Further, in consideration of compatibility with the polyester film, a polyester resin is particularly preferable. In order to achieve solubility and dispersibility in a solvent and adhesion to a base film and other layers, the polyester of the binder is preferably a copolymer polyester. Incidentally, the polyester resin may be modified with polyurethane. Another preferred binder resin that forms the easy-to-lubricate coating layer on the polyester base film is urethane resin. Examples of the urethane resin include a polycarbonate polyurethane resin. Further, a polyester resin and a polyurethane resin may be used in combination, and the above-mentioned other binder resins may be used in combination.

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

(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, zirconium oxide, titanium dioxide, satin white, aluminum silicate, diatomaceous earth, calcium silicate, aluminum hydroxide, hydrohaloysite, calcium carbonate, magnesium carbonate, calcium phosphate, hydroxylated 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 / Iso Organic particles such as len-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 exemplified, but are suitable for a coating layer. Silica is particularly preferably used to provide lubricity.

  The average particle size of the particles is preferably 10 nm or more, more preferably 20 nm or more, and further preferably 30 nm or more. It is preferable that the average particle diameter of the particles is 10 nm or more, since the particles are hardly aggregated and the slipperiness can be secured.

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

  Further, for example, mixing small particles having an average particle diameter of about 10 to 270 nm and large particles having an average particle diameter of about 300 to 1000 nm can also be achieved by the following method. It is preferable to reduce the average length (RSm) of the roughness curve element while keeping Rp) small, and to achieve both smoothness and smoothness. Particularly preferable are small particles of 30 nm or more and 250 nm or less, Large particles having a diameter of 350 to 600 nm are used in combination. When the small particles and the 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 entire solid content of the coating layer.

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

  The thickness ratio of the surface layer A on the side where 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, the influence of the particles contained in the surface layer B and the like is hardly affected from the inside of the film, and it is easy to satisfy the above-mentioned range of the area average surface roughness Sa, which is preferable. When the thickness is not more than 50% of the thickness of all the layers of the base film, the usage ratio of the recycled material in the surface layer B can be increased and the environmental load is preferably small.

  In addition, from the viewpoint of economy, the layers other than the surface layer A (the surface layer B or the above-mentioned core layer C) can be made of 50 to 90% by mass of film waste or PET bottle recycled material. Even in this case, it is preferable that the type and amount of lubricant contained in the surface layer B, the particle diameter, and the average surface roughness (Sa) satisfy the above ranges.

  In addition, a film before or after uniaxial stretching in the film forming process is applied to the surface of the surface layer A and / or the surface layer B in order to improve the adhesion of a release layer or the like to be applied later or to prevent electrification. May be provided with a coat layer, or a corona treatment or the like may be performed. When a coat layer is also provided, the measured value of the surface of the coat layer is substituted for Sa of each layer. When these coat layers are provided on the surface of the surface layer A, it is preferable that no particles are contained.

(Release layer)

  In the release film for manufacturing a ceramic green sheet of the present invention, it is preferable that a certain amount or more of “floating” occurs when the release film with the ceramic green sheet is half-cut as described below. The present inventors have conducted intensive studies and as a result, it is considered that the area surface average roughness (Sa) of the release layer of the release film for producing a ceramic green sheet is related to the above-mentioned “floating”. It is preferable that the region average surface roughness (Sa) of the layer is in the range of 5 to 40 nm. However, on the other hand, when the maximum protrusion height (Rp) of the release layer is equal to or more than a certain value, problems such as pinholes of the ceramic green sheet are likely to occur, and therefore, the maximum protrusion height (Rp) of the release layer. Is preferably 60 nm or less.

  In the present invention, when the ceramic green sheet laminated on the release layer of the release film is peeled, it is required that the ceramic green sheet has sufficient peelability. In particular, when peeling a thin ceramic sheet, it is preferable to generate a sufficient peeling notch in advance at the stage where the ceramic sheet is half-cut. When the peeling notch is sufficient, when the ceramic sheet is peeled, defects such as breakage and distortion of the ceramic green sheet hardly occur, and problems such as short-circuiting of the electrode in the final product can be easily avoided, which is preferable.

  The present inventors have conducted intensive studies, and as a result, applied a ceramic slurry to the surface of the release layer opposite to the polyester film, and half-cut the release film with the ceramic green sheet obtained by drying by the following method. It has been found that by performing the above, the easiness of occurrence of peeling notch of the ceramic green sheet can be easily quantified.

  This will be described below with reference to FIGS. A half-cutting of the release film with the ceramic green sheet is performed by using a rotary die cutter or the like, and a punching die such as a pinnacle die (reference numeral 9 in FIG. 2) is used as the ceramic of the release film with the ceramic green sheet (reference numeral 7 in FIG. 2). Half cutting is performed by pressing the surface of the green sheet (reference numeral 6 in FIG. 2) to cut the ceramic green sheet portion (reference numeral 6 in FIG. 2) of the release film with the ceramic green sheet. At this time, at the time of half-cutting, not only the ceramic green sheet portion (reference numeral 6 in FIG. 2) is completely cut, but also the release film (reference numeral 5 in FIG. 2) half-cut marks (reference numeral 2 in FIG. 1). It is desirable to perform half-cut so as to remain. At this time, the half-cut mark (2 in FIG. 1) of the release film has a depth (not shown) of 10 μm or less from the surface of the release layer of the release film, depending on the thickness of the release film. It is preferable that the width of the interval between the arrows of the half-cut mark (reference numeral 2 in FIG. 1) is 50 μm or less. The depth from the surface of the release layer of the release film is more preferably 1 μm or more and 10 μm or less, and the width of the half-cut mark (reference numeral 2 in FIG. 1) between arrows is more preferably 5 μm or more and 50 μm or less. . When the depth of the half-cut mark is 1 μm or more and the width is 5 μm or more, it is desirable that the ceramic green sheet is completely cut. In addition, depending on the thickness of the release film, if the depth is 10 μm or less and the width is 50 μm or less, there is no possibility that the release film is punched out, and the shear amount around the half cut portion is not too large. It is preferable because there is no possibility that the ceramic green sheet is damaged.

  When a rotary die cutter or the like is used, in order to adjust the half-cut marks as described above, between the pinnacle die (reference numeral 9 in FIG. 2) and the release film with ceramic green sheet (reference numeral 7 in FIG. 2) and ceramic green It is desirable to install a half-cut depth adjusting polyester film (reference numerals 4 and 8 in FIG. 2) between the release film with sheet (reference numeral 7 in FIG. 2) and the loader die cutter driving unit. It is desirable that the thickness of the half-cut depth adjusting polyester film is appropriately adjusted so that the half-cut marks satisfy the above conditions.

The present inventors have found that when the ceramic green sheet is half-cut under the above conditions, when the following formula is satisfied, sufficient lifting such that defects such as breakage and distortion of the ceramic green sheet do not occur in the subsequent peeling step. (A phenomenon in which the ceramic green sheet partially and spontaneously peels off from the release film) has been found to be secured.

A / B ≧ 20

A: Floating width of the ceramic sheet around the half-cut mark (μm)
B: Width of half-cut mark on release layer surface (μm)

Here, the floating width (μm) of the ceramic sheet around the half-cut mark in (A) corresponds to the interval indicated by the arrow 3 in FIG. Further, the width (μm) of the half-cut mark on the surface of the release layer in (B) corresponds to the interval of the arrow 2 in FIG. 1 as described above.

  As described above, when a release film with a ceramic green sheet is half-cut as described below, a certain amount or more of “floating” occurs, so that the release film for producing a ceramic green sheet is formed on the surface of the release layer surface. It is preferable to increase the average roughness (Sa) to a certain level, but it is preferable to control the maximum protrusion height (Rp) to be smaller. By satisfying these conditions, it is possible to obtain a release film for producing a ceramic sheet having both smoothness, releasability, and releasability that cannot be obtained by conventional techniques.

  It is preferable that the release layer surface in the present invention satisfies the above-mentioned small maximum protrusion height (Rp). In order to combine the above-mentioned area average surface roughness (Sa), the above-mentioned area average surface roughness (Sa), and the maximum projection height (Rp) of the release layer surface with each other, it is necessary to form the release layer with each other. There is a method of forming a sea-island structure with incompatible compounds of different types to obtain an appropriate release layer surface roughness.

  Hereinafter, a preferred embodiment in which surface irregularities having a sea-island structure are provided on the surface of the release layer will be described. The release layer in the present invention is an energy ray-curable compound (I) having three or more reactive groups in one molecule and is incompatible with the energy ray-curable compound (I), and undergoes phase separation to form a sea-island structure. It is preferable to cure a coating film containing at least the resin (II) forming the resin and the release component (III). Since the energy ray-curable compound (I) and the resin (II) phase-separate to form a sea-island structure, irregularities of moderate height can be easily formed and coarse projections do not occur. No holes are generated. In addition, since the flat portion is almost eliminated, and peeling is performed at a point, even a brittle ultra-thin ceramic green sheet can be peeled without zipping, thereby suppressing damage such as cracks and deformation. .

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

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

  The energy ray-curable compound having a (meth) acryloyl group can be used without being limited to a monomer, an oligomer or a polymer. In addition, it is preferable to contain at least one compound having three or more reactive groups in one molecule, but two or more compounds such as compounds having one to two reactive groups in a molecule are used as a mixture. You can also. By mixing these compounds having a small number of reactive groups, curling and the like can be suppressed.

  Examples of energy ray-curable monomers having three or more (meth) acryloyl groups in the molecule include isocyanuric acid triacrylate, glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, Methylolpropane tri (meth) acrylate, ditrimethylolpropanetetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meta) ) Polyfunctional (meth) acrylates such as acrylates and their ethylene oxide modified products, propylene oxide modified products, caprolactone modified products, etc. .

  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, 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 trimethylolpropane formal (Meth) acrylate, hydroxyethyl (meth) acrylate, hydroxybutyl (meth) 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 di (meth) acrylate, nonanediol di (meth) acrylate, bisphenol A di (meth) acrylate Rate, neopentyl glycol di (meth) acrylate, monomers and their ethylene oxide-modified products such as cyclohexane diol di (meth) acrylate, propylene oxide-modified products, caprolactone-modified products, and the like.

  Examples of energy ray-curable oligomers having three or more (meth) acryloyl groups in the molecule include urethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, and silicone-modified acrylate, and those commercially available are generally available. Can be used. For example, beam set (registered trademark) series manufactured by Arakawa Chemical Industry Co., Ltd., NK oligo series manufactured by Shin-Nakamura Chemical Co., EBECRYL series manufactured by Daicel Ornex, Biscoat series manufactured by Osaka Organic Chemical Industry Co., Ltd., urethane acrylate series manufactured by Kyoeisha Chemical Co., Ltd., DIC's Unidick series.

  Examples of the energy ray-curable polymers having three or more (meth) acryloyl groups in the molecule include a graft polymer obtained by grafting a (meth) acryloyl group to a polymer and a block polymer obtained by adding a polyfunctional acrylic monomer to a polymer terminal. Is mentioned. As the above-mentioned polymers, an acrylic resin, an epoxy resin, a polyester resin, a polyorganosiloxane, or the like can be used, and is not particularly limited.

(Resin (II))
In the present invention, the resin (II) used in the coating liquid for forming a release layer is dissolved or dispersed in the same solvent as the energy ray-curable compound (I), and in the state of a coating material, both are dissolved or dispersed. However, it is incompatible with each other in the release layer formed after drying and curing of the solvent after coating, and the energy ray-curable compound (I) is used as a sea component, and the resin (II) is used as an island component. It is preferable to form a structure, and the resin (II) can be used without any particular limitation as long as the above requirements are satisfied. Two or more resins can be used simultaneously. The content of the resin (II) in the solid content of the coating solution for forming a release layer is preferably 1 to 40% by mass, and more preferably 1 to 10% by mass. When the content is 1% by mass or more, sufficient unevenness can be formed, and when the content is 40% by mass or less, the degree of crosslinking of the release layer is high, and the temperature dependency at the time of peeling is low, which is preferable.

  As the resin (II), for example, a polyester resin, an acrylic resin, a urethane resin, a polyester urethane resin, a polyimide resin, a polyamideimide resin, a cellulose resin, and the like can be used without particular limitation as long as the solvent is soluble. The condition is that the resin is incompatible with the energy ray-curable compound (I).

  The polyester resin is not particularly limited, and a commercially available polyester resin can be used. Examples include the Byron (registered trademark) series manufactured by Toyobo and the Nichigo Polyester (registered trademark) series manufactured by Nippon Synthetic Chemical Industry.

  The acrylic resin refers to an oligomer or polymer obtained by polymerizing an acrylate, and may be a homopolymer or a copolymer. Also, commercially available products can be used. For example, ADICIC (registered trademark) series manufactured by DIC Corporation, ARFON (registered trademark) series manufactured by Toagosei Co., Ltd., and the like can be mentioned.

  Examples of the polyester urethane resin include Byron (registered trademark) UR series manufactured by Toyobo.

(Release component (III))
The release component (III) used in the coating liquid for forming a release layer in the present invention is a material capable of exhibiting release properties with a green sheet, such as a polyorganosiloxane, a fluorine compound, a long-chain alkyl compound, or a wax. There is no particular limitation as long as it is sufficient. Further, a material having a functional group which can react with and bond to the energy ray-curable compound (I) having a (meth) acryloyl group or the like is preferable. Further, two or more kinds of materials can be mixed and used. The content of the release component (III) in the solid content in the coating liquid for forming a release layer is preferably 0.05 to 10% by mass, more preferably 0.1 to 5% by mass. Addition of 0.05% by mass or more is preferred because the peeling force can be reduced and 10% by mass or less can suppress the transfer of the release component to the ceramic green sheet or the like.

  Examples of the polyorganosiloxane include polydimethylsiloxane, polydiethylsiloxane, polyphenylsiloxane, a partially organically modified siloxane-based compound, a block polymer having a polyorganosiloxane, and a polymer obtained by grafting a polyorganosiloxane. Can be used. As commercially available products, for example, BYK (registered trademark) series manufactured by BYK Japan KK and Modiper (registered trademark) series manufactured by NOF Corporation can be used.

  The fluorine compound is not particularly limited, and a commercially available one can be used. For example, there is a MegaFac (registered trademark) series manufactured by DIC Corporation.

  Examples of the long-chain alkyl compound include an acrylic polymer obtained by copolymerizing a long-chain alkyl acrylate, a graft polymer obtained by grafting a long-chain alkyl, and a block polymer having a long-chain alkyl added to a terminal. There is no particular limitation, and commercially available products can be used. Examples include the Tesfine (registered trademark) series manufactured by Hitachi Chemical Co., Ltd., and Peiroyl (registered trademark) manufactured by Lion Specialty Chemicals.

  Examples of active energy rays for curing the release layer after heating and drying include infrared rays, visible rays, ultraviolet rays, electromagnetic waves such as X-rays, electron beams, ion beams, neutron rays, and particle rays such as α rays. Among them, it is preferable to use ultraviolet light which is excellent in production cost.

  The atmosphere for irradiating the active energy ray may be general air or nitrogen gas atmosphere. In a nitrogen gas atmosphere, the radical reaction can proceed smoothly by reducing the oxygen concentration and the elastic modulus of the release layer can be improved. It is preferable to do so from an economic viewpoint.

(Photopolymerization initiator)
When a radical polymerization compound is used in 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, and 2,4. -Diethylthioxanthone, 1-hydroxycyclohexylphenylketone, benzyldiphenylsulfide, tetramethylthiurammonosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, (2,4,6-trimethyl (Benzyldiphenyl) phosphine oxide, 2-benzothiazole-N, N-diethyldithiocarbamate and the like. In particular, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methylpropan-1-one, which is considered to have excellent surface curability, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 -One is preferable, and 2-hydroxy-2-methyl-1-phenyl-propan-1-one and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one are particularly preferable. preferable. These may be used alone or in combination of two or more.

  The amount of the photopolymerization initiator to be added is not particularly limited. For example, it is preferable that the photopolymerization initiator be contained in an amount of about 0.1 to 20% by mass as a solid content in the coating solution 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 that form projections such as particles from the viewpoint of pinhole generation.

  An additive such as an adhesion improver or an antistatic agent 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 a pretreatment such as an anchor coat, a corona treatment, a plasma treatment, or an atmospheric pressure plasma treatment on the polyester film surface 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. Preferably, the release layer after curing has a range of 0.02 to 3.5 μm. More preferably, it is 0.5 to 3.0 μm. When the thickness of the release layer is 0.02 μm or more, the curability of the energy ray-curable copolymer is good, and the elasticity of the release layer is improved, so that good release performance can be obtained, which is preferable. Further, when the thickness is 3.5 μm or less, curling hardly occurs even when the thickness of the release film is reduced, and the running property is not deteriorated in the process of molding and drying the ceramic green sheet, which is preferable.

  An additive such as an adhesion improver, an antistatic agent and a surfactant 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 a pretreatment such as an anchor coat, a corona treatment, a plasma treatment, or an atmospheric pressure plasma treatment on the polyester film surface before providing the release coating layer.

  The release film of the present invention preferably has a maximum protrusion height (Rp) of 60 nm or less on the surface of the release layer from the viewpoint of suppressing defects such as pinholes of the ceramic sheet. However, from the viewpoint of "floating" at the time of half-cutting of the ceramic green sheet, it is preferable that the surface of the release layer has moderate unevenness. Therefore, it is preferable that the average surface roughness (Sa) of the release layer surface is 5 to 40 nm. Further, it is more preferable that the above-mentioned Sa is satisfied and the maximum projection height (Rp) of the surface of the release layer is 60 nm or less. Further, the average surface roughness (Sa) of the region is preferably 5 to 20 nm, and at the same time, the maximum projection height (Rp) is particularly preferably 50 nm or less. If the average surface roughness (Sa) is 5 nm or more, sufficient lifting occurs around the half cut of the ceramic green sheet at the time of half cutting, and the ceramic green sheet can be peeled without being damaged. When the average surface 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.

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

When the release layer of the present invention is applied on a substrate film by solution coating, the drying temperature of solvent drying is preferably 50 ° C or more and 120 ° C or less, and is preferably 60 ° C or more and 100 ° C or less. More preferred. The drying time is preferably 30 seconds or less, more preferably 20 seconds or less. Further, it is preferable that after the solvent is dried, the curing reaction proceeds by irradiating with an active energy ray. As the active energy ray used at this time, an ultraviolet ray, an electron beam, an X-ray, or the like can be used. Preferably 30~300mJ / cm ² in quantity as the amount of ultraviolet rays to be irradiated, more preferably 30~200mJ / cm ^2. Curing proceed sufficiently in composition by a 30 mJ / cm ² or more, it is possible to create economically release film it is possible to improve the speed during processing by a 300 mJ / cm ² or less preferable.

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

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

  The release film for producing a ceramic green sheet of the present invention is used as a support when performing electrode printing by applying and drying a ceramic slurry containing fine ceramic powder, a binder, a plasticizer and the like on a release layer. The thus formed ceramic green sheet is half-cut on a release film, and is subjected to a peeling, laminating, and sintering process to obtain a product such as a ceramic capacitor.

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

(1) Base film thickness Using a Millitron (electronic microindicator), four 5 cm square samples are cut out from any four points of the film to be measured, and each point is measured at 5 points (20 points in total) and averaged. Is the thickness.

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

(4) Pinhole Evaluation of Ceramic Green Sheet A composition comprising the following materials was stirred and mixed, and dispersed for 60 minutes using a bead mill using zirconia beads having a diameter of 0.5 mm as a dispersion medium to prepare a ceramic slurry.
76.3 parts by mass of toluene 76.3 parts by mass of ethanol 76.3 parts by mass of barium titanate (HPBT-1 manufactured by Fuji Titanium Co., Ltd.) 35.0 parts by mass 3.5 parts by mass of polyvinyl butyral 3.5 parts by mass (ESLEC (registered trademark) BM-S manufactured by Sekisui Chemical Co., Ltd.) )
1.8 parts by mass of DOP (dioctyl phthalate) Next, the release surface of the release film sample is coated using an applicator so that the dried ceramic green sheet has a thickness of 0.8 μm, and dried at 90 ° C. for 2 minutes. The release film was peeled off to obtain a ceramic green sheet.
In the center area of the obtained ceramic green sheet in the film width direction, light is applied from the opposite side of the ceramic slurry application surface within a range of 25 cm 2, and the occurrence of pinholes through which light is visible is observed. Judged. The measurement was performed five times and the average value was adopted.
○: Almost no pinholes (approximate: 2 or less pinholes per measurement area)
△: Pinholes are generated (approximate: 3 or more pinholes per measurement area, 5 or less)
×: Many pinholes occurred (approximate: 6 or more pinholes per measurement area)

(5) Half cut evaluation of ceramic green sheet The release film with the ceramic green sheet obtained by the method of (4) was subjected to a rotary die cutter (RDC (FB) -A4, manufactured by Tsukaya Nebuta Seisakusho Co., Ltd.). It was half-cut so as to have a size of 16 mm × 32 mm square from the ceramic green sheet surface side and a depth of about 3 μm from the surface of the release layer. Use a rotary die cutter blade with a double edge of 50 °, a blade depth of 0.3 mm and a blade height of 0.6 mm. To adjust the half-cut depth, use a polyester film of appropriate thickness with the rotary die cutter blade and ceramic. It was carried out by sandwiching between green sheets and between a release film and an anvil roll.
Regarding the half-cut release film with ceramic green sheet, the width of the half-cut mark (A) (unit: μm) on the surface of the release layer and the width of the part where the sexual green sheet around the half-cut mark floats ( B) (unit: μm) was measured at five places with a laser microscope (KEYENCE VK-X100), and the average value of each was determined. From the measurement results, the following formula was used to calculate the value, which was taken as the floatability of the ceramic green sheet after half-cutting.
A / B
A: Floating width of the ceramic sheet around the half-cut mark (μm)
B: Width of half-cut mark on release layer surface (μm)

(6) Evaluation of surface peeling of ceramic green sheet A peeling terminal is attached via an adhesive film to the inside of a half-cut portion of the release film with a half-cut ceramic green sheet obtained by the method of (5), and is then subjected to tensilon. Peeling was performed in a direction perpendicular to the film at a tensile speed of 10 m / min, and it was confirmed whether a damaged ceramic green sheet remained inside the half cut at the time of peeling. The peel test was performed five times for each sample, and the following judgment was made based on the number of times the damaged ceramic green sheet remained.
：: The ceramic green sheet is hardly damaged (0 to 1 damage)
Δ: The ceramic green sheet may be damaged (number of times of damage: 2 to 3 times)
×: The ceramic green sheet is almost broken (four times to five times)

(Preparation of polyethylene terephthalate pellet (PET (1)))
As the esterification reactor, a continuous esterification reactor consisting of a three-stage complete mixing tank having a stirrer, a decomposer, a raw material inlet, and a product outlet was used. TPA (terephthalic acid) was set at 2 tons / hour, EG (ethylene glycol) was set at 2 moles with respect to 1 mole of TPA, antimony trioxide was used in such an amount that Sb atoms became 160 ppm with respect to generated PET, and these slurries were esterified. The mixture was continuously supplied to the first esterification reactor of the conversion reaction apparatus, and reacted at 255 ° C. at ordinary pressure for 4 hours on average. Next, the reaction product in the first esterification reactor is continuously taken out of the system and supplied to the second esterification reactor, and is distilled from the first esterification reactor into the second esterification reactor. EG solution containing magnesium acetate tetrahydrate in an amount such that Mg atoms become 65 ppm with respect to the generated PET, and 40 ppm with P atoms with respect to the generated PET. An EG solution containing the following amount of TMPA (trimethyl phosphate) was added and reacted at 260 ° C. for 1 hour at an average residence time at normal pressure. Next, the reaction product of the second esterification reaction vessel was continuously taken out of the system, supplied to the third esterification reaction vessel, and subjected to 39 MPa (400 kg / cm2) using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.). 0.2 mass% of porous colloidal silica having an average particle diameter of 0.9 μm and an average particle diameter of 1 mass% per calcium carbonate adhered to calcium carbonate after dispersion treatment with an average number of treatments of 5 passes under pressure. And 0.4% by mass of synthetic calcium carbonate having a particle size of 0.6 μm, and reacted at 260 ° C. for 0.5 hour on average residence time at normal pressure while adding each as 10% EG slurry. The esterification reaction product generated in the third esterification reaction vessel was continuously supplied to a three-stage continuous polycondensation reaction apparatus to perform polycondensation, and sintered a stainless steel fiber having a 95% cut diameter of 20 μm. After filtration with a filter, ultrafiltration was performed and the mixture was extruded into water. After cooling, the mixture was cut into chips to obtain a PET chip 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 pellet (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)).

(Production of laminated film X1)
After drying these PET chips, they were melted at 285 ° C., melted at 290 ° C. by a separate melt extruder extruder, and a filter obtained by sintering a stainless steel fiber having a 95% cut diameter of 15 μm, and a 95% cut diameter. Two-stage filtration of a filter in which 15 μm stainless steel particles are sintered is performed, and the two are merged in a feed block. PET (1) has a surface layer B (anti-release surface side layer) and PET (2) has a surface. It is laminated so as to become the layer A (release side layer), extruded (casted) at a speed of 45 m / min into a sheet, electrostatically adhered and cooled on a casting drum at 30 ° C. by an 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 by an infrared heater, and then stretched 3.5 times in the longitudinal direction at a roll temperature of 80 ° C. due to a speed difference between the rolls. Then, it was guided to a tenter and stretched 4.2 times in the transverse direction at 140 ° C. Next, heat treatment was performed at 210 ° C. in the heat setting zone. Thereafter, a relaxation treatment of 2.3% was performed in the horizontal direction at 170 ° C. to obtain a biaxially stretched polyethylene terephthalate film X1 having a thickness of 31 μm. Sa of the surface layer A of the obtained film X1 was 2 nm, and Sa of the surface layer B was 29 nm.

(Example 1)
A coating solution 1 having the following composition is applied on the surface layer A of the laminated film X1 using reverse gravure so that the thickness of the release layer after drying is 2.5 μm, and dried at 90 ° C. for 30 seconds. Ultraviolet rays were irradiated to 200 mJ / cm ² using a mercury lamp to obtain a release film for producing an ultra-thin ceramic green sheet. About the obtained release film, release layer thickness, area surface average roughness Sa, maximum protrusion height Rp, pinhole evaluation of ceramic green sheet, half-cut evaluation of ceramic green sheet, surface peel evaluation of ceramic green sheet were evaluated. went. Table 1 shows the configurations of the release layer and the substrate. Table 2 shows the physical properties of the obtained release film. A release film suitable for use in peeling off ultra-thin ceramic green sheets, which is excellent in floating during half-cutting of the ceramic green sheets and does not cause abnormalities caused by coarse protrusions such as pinholes in the ceramic green sheets.
(Coating liquid 1)
Compound (I) dipentaerythritol hexaacrylate 100.00 parts by mass
(A-DPH manufactured by Shin-Nakamura Chemical Co., Ltd., hydroxyl value 10 mgKOH / g, hexafunctional acrylate, solid content concentration 100%)
Resin (II) 9.45 parts by mass of polyester resin (Vylon (registered trademark) RV280 manufactured by Toyobo Co., solid content concentration: 100% by mass)
1.26 parts by mass of release agent (III) (modified polydimethylsiloxane having an acryloyl group, BYK-UV3505, manufactured by BYK Japan KK, solid content concentration 40% by mass)
5.25 parts by mass of photopolymerization initiator (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK, solid content concentration 100% by mass)
431.30 parts by mass of diluting solvent (MEK / toluene = 1/1)

(Example 2)
A release film was obtained in the same manner as in Example 1 except that coating liquid 2 having the following composition was used instead of coating liquid 1. About the obtained release film, release layer thickness, area surface average roughness Sa, maximum protrusion height Rp, pinhole evaluation of ceramic green sheet, half-cut evaluation of ceramic green sheet, surface peel evaluation of ceramic green sheet were evaluated. went. Table 1 shows the configurations of the release layer and the substrate. Table 2 shows the physical properties of the obtained release film. A release film suitable for use in peeling off ultra-thin ceramic green sheets, which is excellent in floating during half-cutting of the ceramic green sheets and does not cause abnormalities caused by coarse protrusions such as pinholes in the ceramic green sheets.
(Coating liquid 2)
Compound (I) dipentaerythritol hexaacrylate 100.00 parts by mass
(M-402 manufactured by Toagosei Co., Ltd., hydroxyl value 30 mgKOH / g, hexafunctional acrylate, solid content concentration 100%)
Resin (II) 31.50 parts by mass of polyester urethane resin (Vylon (registered trademark) UR1400 manufactured by Toyobo Co., solid content concentration: 30% by mass)
1.26 parts by mass of release agent (III) (modified polydimethylsiloxane having an acryloyl group, BYK-UV3505, manufactured by BYK Japan KK, solid content concentration 40% by mass)
5.25 parts by mass of photopolymerization initiator (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK, solid content concentration 100% by mass)
431.30 parts by mass of diluting solvent (MEK / toluene = 1/1)

(Comparative Example 1)
A coating solution 3 having the following composition is applied on the surface layer A of the laminated film X1 using reverse gravure so that the thickness of the release layer after drying is 0.03 μm, and dried at 120 ° C. for 30 seconds. Ultraviolet rays were irradiated to 200 mJ / cm ² using a mercury lamp to obtain a release film for producing an ultra-thin ceramic green sheet. About the obtained release film, release layer thickness, area surface average roughness Sa, maximum protrusion height Rp, pinhole evaluation of ceramic green sheet, half-cut evaluation of ceramic green sheet, surface peel evaluation of ceramic green sheet were evaluated. went. Table 1 shows the configurations of the release layer and the substrate. Table 2 shows the physical properties of the obtained release film. Abnormality caused by coarse protrusions such as pinholes does not occur in the ceramic green sheet, but no floating occurs around the half-cut mark, and the ceramic green sheet is easily damaged at the time of surface peeling. The resulting release film was not suitable for use.
(Coating liquid 3)
Curable silicone resin 100.00 parts by mass (Toray Dow Corning LTC856, solid content concentration 30% by mass)
Addition type platinum catalyst 2.10 parts by mass (SRX212 manufactured by Toray Dow Corning, solid content concentration 100% by mass)
Diluent solvent (MEK / toluene = 1/1) 3107.90 parts by mass

(Comparative Example 2)
A release film was obtained in the same manner as in Example 1 except that a coating liquid 4 having the following composition was used in place of the coating liquid 1, and that the thickness of the release layer after drying was 2 μm. About the obtained release film, release layer thickness, area surface average roughness Sa, maximum protrusion height Rp, pinhole evaluation of ceramic green sheet, half-cut evaluation of ceramic green sheet, surface peel evaluation of ceramic green sheet were evaluated. went. Table 1 shows the configurations of the release layer and the substrate. Table 2 shows the physical properties of the obtained release film. Abnormality caused by coarse protrusions such as pinholes does not occur in the ceramic green sheet, but no floating occurs around the half-cut mark, and the ceramic green sheet is easily damaged at the time of surface peeling. The resulting release film was not suitable for use.
(Coating liquid 4)
Compound (I) dipentaerythritol hexaacrylate 100.00 parts by mass
(A-DPH manufactured by Shin-Nakamura Chemical Co., Ltd., hydroxyl value 10 mgKOH / g, hexafunctional acrylate, solid content concentration 100%)
1.26 parts by mass of release agent (III) (modified polydimethylsiloxane having an acryloyl group, BYK-UV3505, manufactured by BYK Japan KK, solid content concentration 40% by mass)
5.25 parts by mass of photopolymerization initiator (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK, solid content concentration 100% by mass)
Diluent solvent (MEK / toluene = 1/1) 422.27 parts by mass

(Comparative Example 3)
A coating solution 5 having the following composition was dried on a surface layer (Sa: 28 nm, Rp: 280 nm) of a biaxially stretched polyester film (E5100, 38 μm, manufactured by Toyobo) having inorganic particles inside after drying using reverse gravure. The coating is performed so that the thickness of the mold layer becomes 0.2 μm, dried at 120 ° C. for 30 seconds, and then irradiated with ultraviolet rays using a high-pressure mercury lamp so that the thickness becomes 200 mJ / cm ^2. A release film for production was obtained. About the obtained release film, release layer thickness, area surface average roughness Sa, maximum protrusion height Rp, pinhole evaluation of ceramic green sheet, half-cut evaluation of ceramic green sheet, surface peel evaluation of ceramic green sheet were evaluated. went. Table 1 shows the configurations of the release layer and the substrate. Table 2 shows the physical properties of the obtained release film. Although the ceramic green sheet was lifted during half-cutting, pinholes were likely to be generated in the ceramic green sheet, and the release film was not suitable for use in peeling ultra-thin ceramic green sheets.
(Coating liquid 5)
Curable silicone resin 100.00 parts by mass (LTC 856 manufactured by Toray Dow Corning, solid content concentration 30% by mass)
Addition type platinum catalyst 2.10 parts by mass (SRX212 manufactured by Toray Dow Corning, solid concentration 100% by mass)
Diluting solvent (MEK / toluene = 1/1) 379.16 parts by mass

(Comparative Example 4)
A coating liquid 6 having the following composition is applied on the surface layer A of the laminated film X1 using reverse gravure so that the thickness of the release layer after drying is 0.2 μm, and dried at 120 ° C. for 30 seconds. Ultraviolet rays were irradiated to 200 mJ / cm ² using a mercury lamp to obtain a release film for producing an ultra-thin ceramic green sheet. About the obtained release film, release layer thickness, area surface average roughness Sa, maximum protrusion height Rp, pinhole evaluation of ceramic green sheet, half-cut evaluation of ceramic green sheet, surface peel evaluation of ceramic green sheet were evaluated. went. Table 1 shows the configurations of the release layer and the substrate. Table 2 shows the physical properties of the obtained release film. Although the ceramic green sheet was lifted during half-cutting, pinholes were likely to be generated in the ceramic green sheet, and the release film was not suitable for use in peeling ultra-thin ceramic green sheets.
(Coating liquid 6)
Curable silicone resin 100.00 parts by mass (LTC 856 manufactured by Toray Dow Corning, solid content concentration 30% by mass)
3.00 parts by mass of silicone resin fine particles (Tospearl 120 (average particle size: 2 μm) manufactured by Momentive Performance Materials Japan LLC, solid content concentration: 100% by mass)
Addition type platinum catalyst 2.10 parts by mass (SRX212 manufactured by Toray Dow Corning, solid concentration 100% by mass)
Diluent solvent (MEK / toluene = 1/1) 421.14 parts by mass

  According to the release film for manufacturing a ceramic green sheet of the present invention, compared to the conventional release film for manufacturing a ceramic green sheet, the occurrence of process defects due to pinholes and uneven thickness during the production of an ultra-thin ceramic green sheet. It has become possible to provide a release film for producing a ceramic green sheet, which is excellent in suppressing peelability and suppressing breakage of the ceramic green sheet during peeling.

1: Release film with ceramic green sheet 2: Width of half-cut mark on release layer surface (B)
3: Floating width of ceramic green sheet around half-cut mark (A)
4: Half cut depth adjustment polyester film 5: Release film 6: Ceramic green sheet 7: Release film with ceramic green sheet 8: Half cut depth adjustment polyester film 9: Pinnacle die

Claims (3)

A release film in which a release layer is laminated on at least one surface of a polyester film directly or via another layer, wherein the maximum peak height (Rp) of the release layer surface is 60 nm or less, and the polyester of the release layer is A ceramic slurry is applied to the surface on the opposite side of the film, and a release film with a ceramic green sheet obtained by drying is created, and the release film with the ceramic green sheet reaches the release film from the ceramic green sheet side, When the half-cut is performed at a depth of 10 μm or less from the surface of the release layer of the release film and the width (B) of the half-cut mark on the surface of the release layer is 50 μm or less, the following expression is obtained. Filling release film for manufacturing ceramic green sheets.
A / B ≧ 20
A: Floating width of ceramic green sheet around half-cut mark (μm)
B: Width of half-cut mark on release layer surface (μm)   2. The release film for producing a ceramic green sheet according to claim 1, wherein the surface average surface roughness (Sa) of the release layer surface is 5 to 40 nm.   The ceramic slurry is applied on the release layer of the release film, and the release film with the ceramic green sheet obtained by drying is half-cut from the ceramic green sheet side, and the depth at which the half-cut mark reaches the release film, In addition, the depth (B) of the half-cut mark on the surface of the release layer is 10 μm or less from the surface of the release layer of the release film, and the width (B) of the half-cut mark on the release layer is 50 μm or less. A method for evaluating a release film for producing a ceramic green sheet, which measures the floating width (A) to evaluate the ease of floating of a ceramic green sheet after half-cutting.