Method for manufacturing release film for resin sheet molding

Abstract

The purpose of the present invention is to provide a mold release film that has a mold release layer having particularly excellent smoothness and releasability.　Provided is a method for producing a mold release film for resin sheet molding, the method including the following steps: a coating step for coating a mold release layer formation composition onto a surface layer A of a polyester film having said surface layer A, the surface layer A containing substantially no inorganic particles and the mold release layer formation composition including at least cation-curable polydimethylsiloxane (a); a drying step for heat-drying the polyester film coated with the mold release layer formation composition, the heat-drying including a first drying step followed by a second drying step and the drying temperature T1 during the first drying step being higher than the drying temperature T2 during the second drying step; and, after the drying step, a photocuring step for radiating active energy rays and curing the mold release layer formation composition.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a release film for molding resin sheets, and more specifically, to a method for manufacturing a release film used when molding an ultra-thin resin sheet. [Background technology]

[0002] Conventionally, release films, which use a polyester film as a base material and laminate a release layer on top of it, have been used as process films for molding resin sheets such as adhesive sheets, cover films, polymer films, and optical lenses.

[0003] The aforementioned release film is also used as a process film for molding ceramic green sheets, which require high smoothness for applications such as multilayer ceramic capacitors and ceramic substrates. In recent years, with the miniaturization and increase in capacitance of multilayer ceramic capacitors, there has been a trend towards thinner ceramic green sheets. Ceramic green sheets are molded by coating a slurry containing ceramic components such as barium titanate and a binder resin onto a release film and drying it. Multilayer ceramic capacitors are manufactured by printing electrodes onto the molded ceramic green sheet, peeling it off the release film, and then laminating, pressing, firing, and applying external electrodes to the resulting ceramic green sheet.

[0004] When molding ceramic green sheets onto the surface of a polyester film substrate's release layer, a problem has arisen where minute protrusions on the release layer surface affect the molded ceramic green sheet, easily causing defects such as repellency and pinholes. In recent years, further thinning of ceramic green sheets has progressed, and there is a growing demand for ceramic green sheets with thicknesses of 1.0 μm or less, more specifically 0.2 μm to 1.0 μm. Therefore, the requirements for smoothness of the release layer surface have increased even further. In addition, there has been a problem where extremely minute protrusions and foreign matter on the release layer can lead to deformation of the molded ceramic green sheet, making it easier for pinholes to occur and the sheet to crack during peeling.

[0005] Furthermore, as ceramic green sheets become thinner, the release properties when peeling the ceramic green sheet from the release film become even more important. If the peeling force is strong and uneven, the ceramic green sheet will be damaged during the peeling process, resulting in sheet defects, uneven thickness, pinholes, sheet cracking, and other problems. Therefore, there is a need to peel the ceramic green sheet with a lower and more uniform force. In other words, in order to manufacture ultra-thin resin sheets, especially ceramic green sheets, without defects, a release film with extremely high smoothness and excellent peelability is required.

[0006] Examples of release films with excellent smoothness and release properties include those described in the following patent documents. For example, Patent Document 1 proposes a release film having a release layer mainly composed of a radical-curing resin. Patent Document 2 proposes a release film having a structure in which a smoothing layer and a release layer are laminated. Patent Document 3 proposes a release film having a release layer mainly composed of a cationic-curing epoxy resin. Patent Document 4 proposes a release film having a release layer mainly composed of a cationic-curing polydimethylsiloxane. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 5492352 [Patent Document 2] Japanese Patent Publication No. 2015-164762 [Patent Document 3] International Publication No. 2018 / 079337 [Patent Document 4] Japanese Patent Publication No. 2016-079349 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, the release film described in Patent Document 1 has the problem that the release layer is not smooth enough because it is provided on a substrate film that is not smooth enough. Furthermore, as a result of diligent research, the present inventors have found that radical-curing resins suffer from curing failure due to oxygen inhibition, resulting in poor solvent resistance of the release layer surface. This leads to a problem where the release layer is eroded by organic solvents used during the molding of ceramic green sheets or printing of internal electrodes, resulting in poor release properties. In the invention described in Patent Document 2, thermosetting melamine resin is used for the smoothing coating layer and the release coating layer, requiring high heat to accelerate the curing reaction. Therefore, the flatness of the release film may be impaired by the heat generated during processing. Furthermore, because multiple processing steps are required for the smoothing coating layer and the release coating layer, there is a risk of not only contamination of the release film but also scratches occurring in the release layer. These scratches and foreign matter may be transferred to the ceramic green sheet molded on the release layer, potentially causing defects.

[0009] Patent documents 3 and 4 propose release layers using cationic resins to improve curing defects caused by oxygen inhibition and flatness defects caused by processing heat, respectively. However, the release film in Patent Document 3 has the problem of poor surface smoothness of the release layer due to the poor smoothness of the base film. Furthermore, the release agent components disclosed in Patent Document 3 have poor reactivity, poor solvent resistance, and problems with release properties. In the release film described in Patent Document 4, the release layer is mainly composed of liquid cationic curable polydimethylsiloxane resin. As a result, the resin may aggregate on irregularities in the base film and on protrusions such as oligomers present on the surface of the base film, potentially causing problems with flatness. Furthermore, the crosslinking density of the release layer is low, resulting in problems with release properties.

[0010] This invention was made against the backdrop of the problems of the prior art. Specifically, it aims to provide a release film having a release layer with particularly excellent smoothness and peelability, and further, a method for manufacturing a release film that can mold ultrathin resin sheets, especially ultrathin ceramic green sheets, without defects. Furthermore, the present invention provides a method for manufacturing a release film that can solve the above problems, suppressing curing defects due to oxygen inhibition and improving flatness defects caused by processing heat. [Means for solving the problem]

[0011] As a result of diligent research to solve the above problems, the inventors of the present invention found that the above objective can be achieved by a method for manufacturing a release film having the following configuration, and thus completed the present invention.

[0012] In other words, the present invention consists of the following configuration. [1] The present invention provides a method for manufacturing a release film for resin sheet molding. A method for manufacturing a release film for resin sheet molding, comprising the following steps; A coating step of applying a release layer forming composition onto the surface layer A of a polyester film having a surface layer A, The aforementioned surface layer A is a layer that does not substantially contain inorganic particles. The release layer forming composition contains a cationic curable polydimethylsiloxane (a), Application process; A drying step in which the polyester film coated with a release layer forming composition is heat-dried, The aforementioned heating and drying process comprises a first drying step and a second drying step. A drying process in which the drying temperature T1 in the first drying process is higher than the drying temperature T2 in the second drying process; A photocuring step is performed after the drying step, in which the release layer forming composition is cured by irradiating it with active energy rays. [2] In one embodiment, the release layer forming composition contains an organic solvent having an SP value (δ) of 14 or more and 17 or less, and the release layer forming composition contains an organic solvent having an SP value (δ) of 14 or more and 17 or less in an amount of 10% by mass or more per 100 parts by mass of the total weight of the release layer forming composition, in the coating process The amount of coating in the release layer forming composition is 10 g / m². 2 The following applies: [3] In one embodiment, a method for manufacturing a release film for producing a resin sheet containing an inorganic compound is provided. [4] In one embodiment, a method for manufacturing a release film for resin sheet molding is provided, in which the resin sheet containing an inorganic compound is a ceramic green sheet. [5] In one embodiment, the method for manufacturing a release film for resin sheet molding further includes forming a ceramic green sheet with a thickness of 0.2 μm or more and 1.0 μm or less. A method for manufacturing ceramic green sheets is provided. [6] In one embodiment, a resin sheet having a thickness of 0.2 μm or more and 1.0 μm or less is molded. A method for manufacturing a release film for resin sheet molding is provided, which includes the following steps. [Effects of the Invention]

[0013] The release film obtained by the method for manufacturing a release film for resin sheet molding according to the present invention can improve the smoothness and peelability of the release layer, and furthermore, can suppress the occurrence of defects in ultrathin resin sheets, especially ceramic green sheets. Furthermore, the present invention, in its method for manufacturing a release film for resin sheet molding, can suppress the loss of flatness of the release film due to heat during processing. Furthermore, the manufacturing method of the present invention can suppress aggregation of the release layer forming composition during the coating and drying processes, and can form a release layer with extremely high smoothness. [Modes for carrying out the invention]

[0014] The present invention will be described in detail below. The present invention makes it possible to manufacture a release film having the following configuration. A release film for molding resin sheets, comprising a polyester film as a base material and a release layer, The polyester film has a surface layer A that is substantially free of inorganic particles, A release layer is provided on the surface layer A. The release layer is a layer formed by curing the release layer forming composition. The release layer forming composition contains a cationic curable polydimethylsiloxane (a), The surface roughness (Sa) of the release layer region is 2 nm or less. The number of protrusions with a height of 10 nm or more on the surface of the release layer is 200 per mm. 2 The following is a release film for resin sheet molding.

[0015] The release film manufactured by the present invention having such a configuration has excellent smoothness and peelability of the release layer, so for example, for a resin sheet with a thickness of 0.2 μm to 1.0 μm or less, It can provide a uniform thickness without defects and suppress flaws such as pinholes. Furthermore, the release film manufactured according to the present invention can provide the following effects. In this invention, since the release layer is provided on a base film with sufficient smoothness, the smoothness of the release layer can also be ensured. Moreover, in this invention, curing defects due to oxygen inhibition can be suppressed in the release layer, and high crosslinking of the release layer can be achieved. The present invention, which provides these effects, can, for example, improve the solvent resistance of the surface of the release layer. By improving the solvent resistance of the surface of the release layer, it is possible to suppress the erosion of the release layer by organic solvents used during the molding of ceramic green sheets and printing of internal electrodes, and high release properties can be achieved. Furthermore, with the present invention, compared to, for example, a release layer having a thermosetting melamine resin, high heat is not required to accelerate the curing reaction. Therefore, it is possible to suppress the loss of flatness of the release film due to heat during processing. In addition, with the manufacturing method of the present invention, aggregation of the release layer forming composition can be suppressed by going through the coating step and drying step according to the present invention, and a release film with a release layer having extremely high smoothness can be obtained.

[0016] More specifically, a release layer-forming composition containing a predetermined amount of cationic curable polydimethylsiloxane (a) is applied to a surface layer A of the base film that is substantially free of inorganic particles. By applying and curing the material, a release layer with extremely high smoothness can be obtained. Furthermore, the content of cationic curable polydimethylsiloxane (a) in the release layer is predetermined By controlling the amount to a certain level, the cation-curable polydimethylsiloxane (a) aggregates against minute foreign matter and oligomer-derived microprotrusions present in the base film during the processing of the release layer. This can be suppressed. Although it should not be interpreted in a way that is limited to a specific theory, increasing the first drying temperature (increasing the drying) can prevent component (a) from agglomerating on the fine protrusions caused by the raw material. Furthermore, by preventing curing defects due to oxygen inhibition, improving the solvent resistance of the release layer surface, suppressing the incorporation of foreign matter into the release layer, and suppressing scratches on the release layer, it is possible to prevent damage during peeling, scratches, and sheet deformation due to the transfer of foreign matter to the object to be released, such as ceramic green sheets. As a result, a release layer with excellent smoothness, hardness, peelability, and stain prevention for the object to be released can be obtained. Furthermore, the cation-curable polydimethylsiloxane (a) is less likely to aggregate during the drying of the organic solvent contained in the release layer forming composition, resulting in a release layer with excellent smoothness. Details will be described later.

[0017] Furthermore, the present invention provides a method for manufacturing a release film for resin sheet molding, comprising the following steps. A coating step of applying a release layer forming composition onto the surface layer A of a polyester film having a surface layer A, Surface layer A is a layer that substantially does not contain inorganic particles. The release layer forming composition comprises at least a cationic curable polydimethylsiloxane (a) , Application process; A drying step in which a polyester film coated with a release layer forming composition is heat-dried, The aforementioned heating and drying process comprises a first drying step and a second drying step. A drying process in which the drying temperature T1 in the first drying process is higher than the drying temperature T2 in the second drying process; A photocuring step is performed after the drying step, in which the release layer forming composition is cured by irradiating it with active energy rays.

[0018] In the manufacturing method according to the present invention, in particular, by setting the manufacturing conditions when processing the release layer to a predetermined method, a release layer with high smoothness can be formed. For example, this can be achieved by controlling the amount of the release layer forming composition applied, the organic solvent composition, the drying time, the drying temperature, etc. By manufacturing the release film under the conditions of the present invention, aggregation of the cation-curable polydimethylsiloxane (a) contained in the release layer forming composition can be suppressed, and a release layer with excellent smoothness can be obtained. Details will be described later.

[0019] (Polyester film) The polyester constituting the polyester film used as the base material of the present invention is not particularly limited, and a film made from polyester commonly used as a base material for release films 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 copolymers mainly composed of these resin components are more preferable, and a polyester film formed from polyethylene terephthalate is particularly preferable. The polyethylene terephthalate preferably has 90 mol% or more, more preferably 95 mol% or more of repeating units of ethylene terephthalate, and may also have small amounts of other dicarboxylic acid components and diol components copolymerized, but from the viewpoint of cost, it is preferable to have one made only from terephthalic acid and ethylene glycol. In addition, known additives, such as antioxidants, light stabilizers, ultraviolet absorbers, and crystallizers, may be added within a range that does not hinder the effect of the film of the present invention. The polyester film is preferably a biaxially oriented polyester film due to reasons such as high bidirectional elastic modulus.

[0020] The intrinsic viscosity of the above polyester film is preferably 0.50 to 0.70 dl / g, and more preferably 0.52 to 0.62 dl / g. An intrinsic viscosity of 0.50 dl / g or higher is preferable because it does not cause many breaks during the stretching process. Conversely, an intrinsic viscosity of 0.70 dl / g or lower is preferable because it allows for good cutting when cutting to a predetermined product width and prevents dimensional defects. Furthermore, it is preferable to thoroughly vacuum dry the raw material pellets. In this specification, when simply referred to as "polyester film," it means a polyester film having (laminated) a surface layer A. Furthermore, in the present invention, the polyester film has a surface layer A that substantially does not contain inorganic particles, and the release layer is located on the surface layer A. Furthermore, where mentioned in the specification, a polyester film having an additional surface layer B (a laminated film) may simply be referred to as "polyester film."

[0021] The method for manufacturing the polyester film in the present invention is not particularly limited, and conventional methods can be used. For example, the polyester can be melted in an extruder, extruded into a film, cooled in a rotating cooling drum to obtain an unstretched film, and then stretched. Biaxial stretching is preferred for its mechanical properties. A biaxially oriented film can be obtained by sequentially biaxially stretching a uniaxially oriented film in the longitudinal or transverse direction in the transverse or longitudinal direction, or by simultaneously biaxially stretching an unstretched film in the longitudinal and transverse directions.

[0022] In the present invention, it is preferable that the stretching temperature during stretching of the polyester film be above the secondary transition temperature (Tg) of the polyester. It is also preferable to stretch the film by 1 to 8 times, and particularly 2 to 6 times, in both the longitudinal and transverse directions.

[0023] The polyester film described above preferably has a thickness of 12 to 50 μm, more preferably 15 to 38 μm, and more preferably 19 to 33 μm. A film thickness of 12 μm or more is preferable because it does not risk deformation due to heat during film production, release layer processing, or molding of ceramic green sheets. On the other hand, a film thickness of 50 μm or less is preferable because it does not result in an excessively large amount of film being discarded after use, thus reducing the environmental burden.

[0024] The polyester film described above may be a single layer or a multilayer of two or more layers. The polyester film has a surface layer A that is substantially free of inorganic particles. For example, it may be a single layer of surface layer A, or it may be a multilayer structure having surface layer A and other layers, such as surface layer B described later. In the case of a laminated polyester film consisting of two or more layers, it is preferable to have a surface layer B on the opposite side of surface layer A, which substantially does not contain inorganic particles, and which may contain particles. As for the laminated structure, if the layer on the side to which the release layer is applied is surface layer A, the layer on the opposite side is surface layer B, and the other core layers are layer C, then the layer configuration in the thickness direction can be a laminated structure such as release layer / A / B or release layer / A / C / B. Naturally, layer C may consist of multiple layers. Also, surface layer B may not contain particles. In that case, it is preferable to provide a coating layer containing particles and a binder on surface layer B in order to provide slipperiness for winding the film into a roll.

[0025] In the polyester film of the present invention, the surface layer A located on the surface to which the release layer is applied is substantially free of inorganic particles. In the present invention, since the surface layer A is substantially free of inorganic particles, it can exhibit the following regional average surface roughness. In this invention, the regional average surface roughness (Sa) of surface layer A is the regional average surface roughness (Sa) on the surface on which the release layer is placed, and the regional average surface roughness (Sa) on the surface on which the release layer is placed is 7 nm or less. When Sa is 7 nm or less, the release layer laminated on surface layer A can also exhibit high smoothness, and the occurrence of pinholes and other defects is less likely to occur when molding the ultrathin ceramic green sheet laminated on the release layer. Furthermore, when forming the release layer, it is possible to suppress the aggregation of release layer components on protrusions on surface layer A, and the deterioration of the smoothness of the release layer surface can be prevented.

[0026] The regional average surface roughness (Sa) of surface layer A is preferably as small as possible, and may be 0.1 nm or more. In one embodiment, the regional average surface roughness (Sa) of surface layer A is 0.1 nm or more and 7 nm or less, for example, 0.5 nm or more and 5 nm or 0.5 nm or more and 4 nm or less. Being within this range improves the smoothness of the release layer and suppresses the occurrence of pinholes and other defects during the molding of the laminated ultrathin ceramic green sheets. Furthermore, when forming the release layer, it is possible to suppress the aggregation of release layer components on protrusions on surface layer A, thereby preventing deterioration of the smoothness of the release layer surface.

[0027] In this invention, "substantially free of inorganic particles" means that when inorganic elements are quantified by X-ray fluorescence analysis, the content is 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit. This is because even without actively adding inorganic particles to the film, contamination components originating from foreign substances, or dirt adhering to the raw resin or the production lines and equipment in the film manufacturing process, may be mixed into the film.

[0028] In the polyester film substrate of the present invention, a surface layer B may be provided on the side opposite to the surface on which the release layer is placed. The surface layer B preferably contains particles. The inclusion of particles provides excellent slipperiness and air release properties, resulting in superior transportability and winding capabilities. In particular, the inclusion of silica particles and / or calcium carbonate particles is preferred. The total amount of particles contained in surface layer B is 1,000 to 15,000 ppm. In this case, the average surface roughness (Sa) of the surface layer B film is, for example, 1 nm to 40 nm. More preferably, it is 5 nm to 35 nm. When the total amount of silica particles and / or calcium carbonate particles is 1,000 ppm or more and Sa is 1 nm or more, when the film is rolled up, air can be released uniformly, resulting in a good rolled appearance and good flatness. Due to these characteristics, for example, when manufacturing an ultrathin resin sheet with a thickness of 0.2 μm to 1.0 μm, such as a ceramic green sheet, wrinkles and misalignment of the rolled ceramic green sheet can be prevented, and a release film with excellent transportability, winding, and storage properties can be provided. Furthermore, 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, particle aggregation that also functions as a lubricant is less likely to occur, and coarse protrusions (e.g., protrusions with a height of 1 μm or more) are not formed, so ultrathin resin sheets, for example, ceramic During the manufacturing of Mick Green sheets, for example, the occurrence of pinholes due to winding can be suppressed, and a resin sheet with stable quality can be provided.

[0029] As particles contained in surface layer B, inert inorganic particles and / or heat-resistant organic particles other than silica and / or calcium carbonate can be used. From the viewpoint of transparency and cost, it is more preferable to use silica particles and / or calcium carbonate particles. Other inorganic particles that can be used include alumina-silica composite oxide particles and hydroxyapatite particles. Heat-resistant organic particles include cross-linked polyacrylic particles, cross-linked polystyrene particles and benzoguanamine particles. When silica particles are used, porous colloidal silica is preferred. When calcium carbonate particles are used, light calcium carbonate surface-treated with a polyacrylic acid-based polymer compound is preferred from the viewpoint of preventing particle shedding.

[0030] 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. An average particle size of 0.1 μm or more is preferable because it provides good slipperiness for the release film. Furthermore, if the average particle size is 2.0 μm or less, deformation of the surface layer A is suppressed, and the occurrence of thickness unevenness and pinholes in the ceramic green sheet can be suppressed.

[0031] The surface layer B may contain two or more types of particles made of different materials. Alternatively, it may contain particles of the same type but with different average particle sizes. Furthermore, the two or more types of different particles may have different average particle diameters within the above range. Including two different types of particles is preferable because it allows for a high degree of control over the irregularities formed on the surface layer B, enabling a balance between slipperiness and smoothness.

[0032] From the viewpoint of reducing pinholes, it is preferable not to use recycled materials or the like in the surface layer A, which is the layer on the side where the release layer is provided, in order to prevent the inclusion of particles or impurities.

[0033] The thickness ratio of surface layer A, which is the layer on the side where the release layer is provided, is preferably 20% to 50% of the total thickness of the base film. If it is 20% or more, the influence of particles contained in surface layer B and the like from inside the film is less likely to occur, and the average surface roughness Sa can satisfy the above range, which is preferable. If it is 50% or less of the total thickness of the base film, the proportion of recycled raw materials used in surface layer B and the aforementioned intermediate layer C can be increased by co-extrusion, which is preferable as it reduces the environmental impact.

[0034] Furthermore, from an economic standpoint, 50 to 90% by mass of recycled film scraps or PET bottles can be used in layers other than the surface layer A (surface layer B or the aforementioned intermediate layer C). Even in this case, it is preferable that the type, amount, particle size, and average surface roughness (Sa) of the lubricant contained in surface layer B satisfy the above range.

[0035] Furthermore, to improve the adhesion of release layers applied later and to prevent static electricity, a coating layer may be provided on the surface of surface layer A and / or surface layer B of the film before stretching or after uniaxial stretching during the film-forming process, and corona treatment may also be applied. When a coating layer is provided on surface layer A, it is preferable that the coating layer substantially does not contain particles.

[0036] (Release layer) In the present invention, the release layer is laminated on the surface layer A. In the present invention, the release layer is a layer formed by curing the release layer forming composition, and the release layer and the release layer forming composition contain at least a cationic curable polydimethylsiloxane (a), and the regional surface roughness (Sa) of the release layer is 2 nm or less. And, The number of protrusions with a height of 10 nm or more on the surface of the release layer is 200 per mm. 2 The following applies: Because the release layer has these characteristics, it is possible to suppress the occurrence of pinholes in ultrathin resin sheets that require high smoothness, such as ceramic green sheets, and to form resin sheets with a uniform film thickness. More specifically, the present invention can suppress curing defects caused by oxygen inhibition in the release layer and achieve high crosslinking of the release layer. The present invention, which achieves these effects, can, for example, improve the solvent resistance of the release layer surface. By improving the solvent resistance of the release layer surface, it is possible to suppress erosion of the release layer by organic solvents used during the molding of ceramic green sheets and printing of internal electrodes, thereby achieving high release properties. Furthermore, with this invention, high temperatures of 130°C or higher are not required to accelerate the curing reaction. Therefore, it is possible to suppress the loss of flatness of the release film due to heat during processing. In addition, it is possible to suppress the incorporation of foreign matter into the release film for resin sheet molding and the occurrence of scratches in the release layer, and to suppress the occurrence of sheet damage to the object to be released, such as ceramic green sheets, due to the transfer of foreign matter and scratches.

[0037] The average surface roughness (Sa) of the release layer is 2 nm or less. Furthermore, the number of protrusions with a height of 10 nm or more on the release layer surface is 200 per mm.2 The following applies. In order not to cause defects in the ceramic sheet coated and molded thereon, the surface of the release layer of the release film has a predetermined condition in terms of the average surface roughness (Sa) of the above region and the number of protrusions of 10 nm or more. The average surface roughness (Sa) of the region is 2 nm or less, and the number of protrusions with a height of 10 nm or more is 200 per mm 2 If it is below, when molding the ceramic sheet, there are no defects such as pinholes in the ceramic sheet, and the yield is good, which is preferable. More preferably, the average surface roughness (Sa) of the region is 1.7 nm or less, for example, 1.6 nm or less, and may be 1.5 nm or less. In one aspect, the average surface roughness (Sa) of the region is 1.3 nm or less. Also, the average surface roughness (Sa) of the region may be 0.1 nm or more, and may be 0.2 nm or more. On the other hand, in one aspect, the number of protrusions with a height of 10 nm or more is 180 per mm 2 or less, for example 170 per mm 2 or less, 160 per mm 2 or less may be sufficient. In one aspect, the number of protrusions with a height of 10 nm or more is 120 per mm 2 or less may be sufficient, or 100 per mm 2 or less may be sufficient. Also, the number of protrusions with a height of 10 nm or more may be 1 per mm 2 or more, for example, 10 per mm 2 or more may be sufficient. When the number of protrusions with a height of 10 nm or more is within the above range, there are no defects such as pinholes in the ceramic sheet, and excellent release properties can be achieved in a well-balanced manner. More preferably, the average surface roughness (Sa) of the region is 1.0 nm or less, and the number of protrusions with a height of 10 nm or more is 1 00 per mm 2 or less. The release layer having the average surface roughness (Sa) of the region according to the present invention and the number of protrusions can exhibit extremely excellent smoothness.

[0038] In one embodiment, the maximum protrusion height (Sp) of the release layer is 20 nm or less. Having the maximum protrusion height within this range further suppresses defects in the ceramic sheet. More preferably, the maximum protrusion height (Sp) is 15 nm or less, and even more preferably 10 nm or less. In one embodiment, the sum of the number of protrusions with a height of 5 nm or more and less than 10 nm present on the surface of the release layer, and the number of protrusions with a height of 10 nm or more, is 1500 per mm. 2 The following applies: The sum of the number of protrusions with a height of 5 nm or more but less than 10 nm on the release layer and the number of protrusions with a height of 10 nm or more is 1500 per mm. 2 The following conditions are preferable because they further suppress defects in the ceramic sheet and allow for the acquisition of a release layer with high smoothness. More preferably, the total number of protrusions with a height of 5 nm or more and less than 10 nm, plus the number of protrusions with a height of 10 nm or more, is 1000 per mm. 2 For example, 500 pieces / mm 2 The following is even more preferable:

[0039] The release layer in the resin sheet molding release film of the present invention is a layer formed by curing a release layer forming composition, and the release layer forming composition contains a small amount of cationic curable polydimethylsiloxane (a). It also includes cation-curable polydimethylsiloxane (a) is obtained by a cation curing reaction. Because the cross-linking reaction proceeds, curing defects due to oxygen inhibition do not occur, resulting in a release layer with excellent solvent resistance. Therefore, there is no risk of the release layer being eroded by organic solvents used during ceramic green sheet molding, internal electrode printing, etc., and a release layer with excellent peelability can be obtained.

[0040] Furthermore, the present inventors have found that a release layer containing cationic curable polydimethylsiloxane (a) The amount of cationic curable polydimethylsiloxane (a) is high, resulting in a release layer with high smoothness. To achieve this, we identified what was important. Cationic curable polydimethylsiloxane (a) is present in the release layer at a concentration of 90 mg / m². 2For example, 60 mg / m² 2 Below, 50mg / m 2 Preferably, it contains the following, at 40 mg / m² 2 The following More preferably, 30 mg / m² 2 It is even more preferable that the following conditions are met. Also, for example, catio The hardened polydimethylsiloxane (a) is 20 mg / m² 2 The following is also acceptable. The release layer contains 50 mg / m² of cationic curable polydimethylsiloxane (a). 2 If the following occurs, polydimethylsiloxane (a) will condense during the process of forming the release layer, for example, during the drying process. This method can suppress the accumulation of particles, eliminate the risk of generating numerous protrusions that fall outside the scope of the present invention, and achieve the effects of the present invention. In one embodiment, the release layer and the release layer forming composition may also contain components other than cationic curable polydimethylsiloxane (a). In this case as well, based on a specific theory Although it should not be judged based on this, in the present invention, polydimethylsiloxane (a) can segregate onto the surface of the release layer during processing of the release layer, and the content is 50 mg / m³ 2 The following conditions make it difficult for aggregation to occur and allow for the formation of a release layer with high smoothness. The lower the content of polydimethylsiloxane (a) according to the present invention, the less likely it is to aggregate. 0.1 mg / m³ in the release layer 2 If the above conditions are met, the leveling properties of the release layer will be maintained, and the coating appearance will be preserved. This is excellent and allows for the acquisition of a highly smooth release layer. Also, 0.1 mg / m 2 If above, peeling It is also preferable because it is excellent in this respect. For example, the polydimethylsiloxane (a) content is 0.5 mg / m². 2 That's fine too. In the present invention, the release layer forming composition is a cation-curable polydimethylsiloxane (a ) is included. Furthermore, in the release layer formed by the curing of the release layer-forming composition, a compound (cured product) derived from cationic curable polydimethylsiloxane (a) is present. In this specification, in the release layer Compounds derived from (a) present in the above may also be simply described as cation-curable polydimethylsiloxane (a).

[0041] In the present invention, cationic curable polydimethylsiloxane (a) is a cationic curable polydimethylsiloxane. This refers to polydimethylsiloxane having a functional group. A cationic curable functional group is a reactive functional group that exhibits cationic curability, and specific examples include vinyl ether groups, oxetanyl groups, epoxy groups, and alicyclic epoxy groups. Among these, it is preferable from the viewpoint of reactivity to have at least one functional group selected from oxetanyl groups, epoxy groups, and alicyclic epoxy groups, and an alicyclic epoxy group is most preferable. Having such a functional group is preferable because it forms a crosslinked structure by the cationic curing reaction, resulting in a release layer with excellent solvent resistance and excellent release properties.

[0042] The number of cationic curable functional groups in cationic curable polydimethylsiloxane (a) is one or more. For example, by having two or more cationic curable functional groups, This is preferable because it facilitates the curing reaction and results in a release layer with high crosslink density. The location of the cationic curable functional group is not particularly limited, and it is generally located on the side chains or terminals of the polydimethylsiloxane. The structure of the polydimethylsiloxane can be linear or branched, and it can be used without problems even if it has functional groups other than cationic curable functional groups.

[0043] Cationic curable polydimethylsiloxane (a) can preferably be a commercially available product. Yes, it is possible. For example, SilicoLease (registered trademark) UV POLY20 manufactured by Arakawa Chemical Industries, Ltd. Examples include UV 0, UV POLY201, UV POLY215, UV RCA200, UV RCA251, X-62-7622, ​​X-62-7629, X-62-7660, KF-101, KF-105, X-22-343, X-22-169AS, X-22-169B, X-22-163, X-22-173BX, X-22-173DX, X-22-9002 from Shin-Etsu Chemical Co., Ltd., and UV9440E and UV9430 from Momentive Performance Materials.

[0044] The weight-average molecular weight of cation-curable polydimethylsiloxane (a) is 1000-5000. It is preferable that the weight-average molecular weight is 00, and more preferably 5000 to 100000. A weight-average molecular weight of 1000 or more is preferable because the cation curing reaction proceeds easily and the release properties are excellent. A weight-average molecular weight of 500000 or less is preferable because the viscosity does not become too high, the release layer has excellent coating properties and high flatness.

[0045] The release layer forming composition of the present invention may also contain other resins in addition to cationic curable polydimethylsiloxane (a). A release layer cured with cationic curable polydimethylsiloxane (a) as the main component is preferred. In this case, the film thickness of the release layer can be reduced. In the present invention, since the release layer is provided on the surface layer A of a substrate film that substantially does not contain inorganic particles, a release layer with extremely high smoothness can be obtained even if the film thickness of the release layer is thin. Furthermore, because the film thickness of the release layer is thin, the curing reaction proceeds easily, processing can be done at a faster speed, and a release layer can be obtained economically.

[0046] Furthermore, if the film thickness is thin, there is no risk of extremely small foreign matter present in the base film, release process, etc., being incorporated into the release layer. Therefore, there is no risk of protrusions caused by foreign matter forming on the surface of the release layer, and a release layer with the smooth surface described above can be obtained.

[0047] In the case of a release layer cured from a composition mainly composed of cationic curable polydimethylsiloxane (a), the thickness of the release layer is preferably 0.001 μm or more and less than 0.050 μm. A thickness of 0.001 μm or more is preferable because it provides excellent release properties. A thickness of less than 0.050 μm is preferable because it prevents aggregation of the release layer forming composition, resulting in a smooth release layer. In the present invention, when the main component is cationic curable polydimethylsiloxane (a), the composition contains at least 50 parts by mass, for example more than 50 parts by mass, preferably 70 parts by mass or more, for example 80 parts by mass or more, with 100 parts by mass of resin solids in the release layer, and in one embodiment, 90 parts by mass or more. Alternatively, the entirety of the resin solids in the release layer may be substantially composed of cationic curable polydimethylsiloxane (a).

[0048] The release layer forming composition of the present invention may also contain a cationic curable resin (b) in addition to a cationic curable polydimethylsiloxane (a). In this case, (b) is different from (a). Resins, and resin (b) does not have a polydimethylsiloxane structure. Specifically, they are broadly classified into two types: cationic curable compounds (b-1) that do not have a silicone skeleton, and cyclic siloxane compounds (b-2) that have alicyclic epoxy groups.

[0049] In one embodiment, the release layer forming composition further contains a cationic curable compound (b-1) without a silicone skeleton in addition to a cationic curable polydimethylsiloxane (a). Examples of cationic curable compounds (b-1) without a silicone skeleton include polymers and monomers having two or more cationic curable functional groups in the molecule and without a silicone skeleton. Among these, resins having two or more epoxy groups or alicyclic epoxy groups are preferred, and having two or more alicyclic epoxy groups is more preferred. For example, the number of alicyclic epoxy groups may be six or less. Having two or more alicyclic epoxy groups allows for crosslinking through cationic curing, resulting in a release layer with excellent solvent resistance. Furthermore, since crosslinking also occurs with the polydimethylsiloxane (a) contained in the release layer, it exhibits excellent release properties and suppresses the migration of polydimethylsiloxane (a) to the ceramic green sheet, which is preferable.

[0050] In one embodiment, the release layer forming composition contains both a cationic curable resin (b-1) without a silicone skeleton and polydimethylsiloxane (a), thereby achieving a release layer with high smoothness. By using a release layer containing compound (b-1), fine irregularities, minute foreign matter, and oligomer-derived protrusions present in the substrate film can be filled, resulting in an ultra-smooth release layer. Furthermore, since the curing reaction proceeds with ultraviolet light, a release layer with high smoothness is achieved. Although it should not be interpreted in a way that is limited to a specific theory, during the drying process in the release layer forming composition during release layer processing, (b-1) and (a) level uniformly, resulting in high flatness. It can be inferred that hardening will proceed after the material has set, resulting in a release layer with high smoothness. Furthermore, the polydimethylsiloxane (a) contained in the material segregates on the surface of the release layer during the drying process in this invention, resulting in a release layer with excellent peelability.

[0051] The cation-curable compound (b-1) that does not have a silicone skeleton is preferably a low molecular weight monomer. Specifically, it is preferably a number-average molecular weight of 200 or more and less than 5000, more preferably 200 or more and less than 2500, and even more preferably 200 or more and less than 1000. A number-average molecular weight of 200 or more is preferable because the boiling point does not become low, and there is no risk of the cation-curable compound (b-1) volatilizing during the drying process of the release layer forming composition during release layer processing. A number-average molecular weight of less than 5000 is preferable because it increases the crosslinking density of the release layer and provides excellent solvent resistance. Furthermore, it is preferable because it can exist in a fluid liquid state during the drying process, resulting in excellent leveling properties and an ultra-smooth release layer.

[0052] A commercially available cation-curing compound (b-1) that does not have a silicone skeleton can be suitably used. Examples of compounds having an alicyclic epoxy group include Celoxide 2021P, Celoxide 2081, Epolid GT401, and EHPE3150 from Daicel Corporation, HiREM-1 from Shikoku Chemicals, and THI-DE, DE-102, and DE-103 from ENEOS Corporation. Examples of resins include DIC Corporation's EPICLON® 830, 840, 850, 1051-75M, N-665, N-670, N-690, N-673-80M, N-690-75M, and Nagase Chemtec Corporation's Denacol® EX-611, EX-313, EX-321.

[0053] In the release layer, the content of the cation-curable compound (b-1) without a silicone skeleton is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, based on a total of 100 parts by mass of the cation-curable polydimethylsiloxane (a) and the cation-curable compound (b-1). It is preferable to have a release layer with a high crosslinking density and excellent release properties by having a cation-curable compound (b-1) content of 80% by mass or more and making it the main component of the release layer. Furthermore, the content of cation-curable polydimethylsiloxane (a) contained in the release layer can be reduced, and the drying process This suppresses the aggregation of polydimethylsiloxane (a)-derived components on the surface of the release layer, and It is preferable as there is no risk of deterioration of surface properties. The higher the content of the cationic curable compound (b-1), the smoother the release layer becomes, but it contains cationic curable polydimethylsiloxane (a). In order to ensure peelability, it is preferable that the cation-curable compound (b-1) is 99.9% by mass or less. In the present invention, the mold release layer formed by the curing of the mold release layer-forming composition contains compounds (cured products) derived from a cationic curable compound (b-1) that does not have a silicone skeleton. In this specification, the compounds derived from (b-1) present in the mold release layer may also be simply referred to as a cationic curable compound (b-1) that does not have a silicone skeleton.

[0054] When the release layer forming composition contains a cationic curable polydimethylsiloxane (a) and a cationic curable compound (b-1), it is preferable because the release layer has a high crosslinking density, excellent solvent resistance, and excellent peeling power. Furthermore, the inclusion of a cationic curable compound (b-1) is preferable because it allows for a thicker release layer while keeping the content of cationic curable polydimethylsiloxane (a) within a predetermined range. A thicker release layer is preferable because it can fill in scratches and minute irregularities present in the substrate film, resulting in a smooth release layer as described above.

[0055] When the release layer forming composition contains a cationic curable polydimethylsiloxane (a) and a cationic curable compound (b-1), the thickness of the release layer is preferably 0.05 μm or more and 1.0 μm or less, and more preferably 0.1 μm or more and 0.5 μm or less. A thickness of 0.05 μm or more is preferable because it results in a smooth release layer. A thickness of 1.0 μm or less is preferable because it results in a release film with excellent flatness without curling.

[0056] In one embodiment, the release layer forming composition may further contain a cyclic siloxane compound (b-2) having an alicyclic epoxy group. Examples of cyclic siloxane compounds (b-2) having an alicyclic epoxy group include those shown in the following structural formula (Chemical Formula 1) (wherein R 2 (where is an alkyl group having 1 to 4 carbon atoms). Furthermore, it is preferable that the cationic curable compound (b-2) having a cyclic siloxane skeleton has at least two or more alicyclic epoxy groups. If there are two or more cyclic epoxy groups, the cationic curing reaction proceeds, forming a release layer with high crosslink density. It is preferable to become that way.

[0057] [ka]

[0058] Using a cyclic siloxane compound (b-2) having an alicyclic epoxy group is preferable because it results in an ultra-smooth release layer for the same reasons as when using the cationic curable compound (b-1). That is, it can fill in fine irregularities, minute foreign matter, and protrusions derived from oligomers present in the substrate film. Furthermore, since the curing reaction proceeds with ultraviolet light, the compound (b-2) and polydimethylsiloxane (a) level uniformly during the drying process of the release layer forming composition during release layer processing, and curing proceeds after the flatness is improved, resulting in an ultra-smooth release. A layer can be obtained. Furthermore, in this invention, the polydimethylsiloxane (a) contained at the same time segregates on the surface of the release layer during the drying process, so a release layer with excellent peelability can be obtained.

[0059] The cyclic siloxane compound (b-2) having an alicyclic epoxy group is well compatible with the cationic curable polydimethylsiloxane (a), so it mixes appropriately in the release layer and crosslinks with each other. The reaction proceeds. Therefore, it is preferable as it forms a release layer with excellent solvent resistance and excellent peelability. Furthermore, the cyclic siloxane compound (b-2) has a cyclic siloxane structure, which gives it a rigid molecular skeleton, and is preferable because it increases the hardness of the film when cured. With increased film hardness, the release layer is less likely to deform when peeling off a resin sheet, such as a ceramic green sheet, and good peelability can be achieved. Moreover, scratches are less likely to occur in the release layer, and there is no risk of scratches in the release layer being transferred to the resin sheet, such as a ceramic green sheet, causing defects, which is preferable.

[0060] It is preferable that the release layer forming composition contains a cyclic siloxane compound (b-2) because it improves the adhesion of the release layer to the base film. Improved adhesion of the release layer is preferable because it suppresses the occurrence of scratches during the transport process and eliminates the risk of the release layer transferring when the resin sheet is peeled off.

[0061] In one embodiment, the cyclic siloxane compound (b-2) has two or more alicyclic epoxy groups in its molecule. Having two or more alicyclic epoxy groups in its molecule allows for crosslinking by cationic curing, resulting in a release layer with excellent solvent resistance. Furthermore, since crosslinking also proceeds with polydimethylsiloxane (a) contained in the release layer, it is preferable because it has excellent release properties and suppresses the migration of polydimethylsiloxane (a) to the ceramic green sheet. For example, cyclic siloxane compounds (b-2) have six or fewer alicyclic epoxy groups in their molecule.

[0062] A commercially available cyclic siloxane compound (b-2) having an alicyclic epoxy group can be used. Examples include X-40-2670 and X-40-2678 manufactured by Shin-Etsu Chemical Co., Ltd.

[0063] In the release layer, the content of cyclic siloxane compound (b-2) is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, based on 100 parts by mass of the total of cation-curable polydimethylsiloxane (a) and cyclic siloxane compound (b-2). A content of 80% by mass or more of cyclic siloxane compound (b-2) as the main component in the release layer is preferable because it results in a release layer with high crosslinking density and excellent release properties. Furthermore, the content of cation-curable polydimethylsiloxane (a) in the release layer can be reduced, and in the present invention, during the drying process, the cation-curable polydimethylsiloxane (a) This suppresses the aggregation of lusiloxane (a) on the surface of the release layer, thus preventing deterioration of flatness. It is preferable. The higher the content of the cyclic siloxane compound (b-2), the smoother the release layer becomes. For example, it contains cationic curable polydimethylsiloxane (a) to ensure release properties. To achieve this, it is preferable that the cyclic siloxane compound (b-2) is 99.9% by mass or less. In the present invention, the mold release layer formed by the curing of the mold release layer-forming composition contains compounds (cured products) derived from cyclic siloxane compound (b-2). In this specification, compounds derived from cyclic siloxane compound (b-2) present in the mold release layer may also be simply referred to as cyclic siloxane compound (b-2).

[0064] When the release layer forming composition contains a cationic curable polydimethylsiloxane (a) and a cyclic siloxane compound (b-2), the thickness of the release layer is preferably 0.05 μm or more and 1.0 μm or less, and more preferably 0.1 μm or more and 0.5 μm or less. A thickness of 0.05 μm or more is preferable because it results in a smooth release layer. A thickness of 1.0 μm or less is preferable because it results in a release film with excellent flatness without curling.

[0065] In one embodiment, the release layer may contain both a cationic curable resin (b-1) and a cyclic siloxane compound (b-2), and the total amount of these cationic curable resins (b-1) and cyclic siloxane compounds (b-2) can be 80% by mass or more and 99.9% by mass or less, based on 100 parts by mass of the total of the cationic curable polydimethylsiloxane (a), cationic curable compound (b-1), and cyclic siloxane compound (b-2) in the release layer.

[0066] In the present invention, it is necessary to carry out a cationic curing reaction in order to form a release layer. Therefore, the release layer forming composition preferably contains an acid generator (c). Furthermore, compounds derived from the acid generator (c) may be present in the release layer. Here, compounds derived from the acid generator (c) present in the release layer may also be simply referred to as the acid generator (c). While there are no particular limitations on the acid generators used, and general-purpose ones are generally employed, using a photoacid generator that generates acid under ultraviolet irradiation is preferable because it reduces the amount of heat generated during processing and results in a release layer with excellent flatness.

[0067] From a reactivity standpoint, a salt consisting of an onium ion and a non-nucleophilic anion is preferred as the photoacid generator. Alternatively, organometallic complexes such as iron arene complexes or carbocation salts such as tropylium may be used, as well as anthracene derivatives or phenols substituted with electron-withdrawing groups, such as pentafluorophenol.

[0068] When a salt consisting of the onium ion and a non-nucleophilic anion is used as a photoacid generator, iodonium, sulfonium, and ammonium can be used as the onium ion. Triaryl, diaryl(monoalkyl), monoaryl(dialkyl), and trialkyl groups may be used as the organic group of the onium ion, and benzophenone or 9-fluorene may be introduced, or other organic groups may be used. Hexafluorophosphorate, hexafluoroantimonate, hexafluoroborate, and tetra(pentafluorophenyl)borate are preferred as the non-nucleophilic anion. In addition, tetra(pentafluorophenyl)gallium ions or anions in which some of the fluorine anions are replaced with perfluoroalkyl groups or organic groups may be used, or other anionic components may be used.

[0069] The amount of photoacid generator added is 0.1 to 10% by mass, more preferably 0.5 to 8% by mass, based on 100 parts by mass of the total of the cationic curable polydimethylsiloxane (a) and cationic curable compound (b-1) and / or cyclic siloxane compound (b-2) in the release layer. Even more preferably, it is 1 to 5% by mass. An amount of 0.1% by mass or more is preferable because it prevents insufficient acid generation and the risk of inadequate curing. An amount of 10% by mass or less is preferable because it ensures an appropriate amount of acid is generated, thereby suppressing the transfer of acid to the molded ceramic green sheet.

[0070] In this specification, the total of a cation-curable polydimethylsiloxane (a) and a cation-curable compound (b-1) and / or a cyclic siloxane compound (b-2) in the release layer is 1 00 parts by mass refers to the total value of the solid content of the cationic curable polydimethylsiloxane (a) and the cationic curable resin (b). In the embodiment in which the release layer does not contain the cationic curable resin (b), the weight of the cationic curable polydimethylsiloxane (a) corresponds to 100 parts by mass of the resin solid content in the release layer.

[0071] In one embodiment, the release layer forming composition contains an organic solvent having an SP value (δ) of 14 or more and 17 or less, and the release layer forming composition contains the organic solvent having an SP value (δ) of 14 or more and 17 or less in an amount of 10% by mass or more per 100 parts by mass of the total weight of the release layer forming composition. Organic solvents with an SP value (δ) of 14-17 exhibit excellent solubility for cationic curable polydimethylsiloxane (a). Therefore, even if the concentration of (a) in the release layer forming composition increases as the organic solvent dries during the drying process after the coating process, it can maintain a uniformly dissolved state, leveling cleanly without aggregation and obtaining a smooth release layer. Furthermore, if the content is 10% by mass or more, the cation-curable polydimethylsiloxane (a) can remain dissolved for a long time during drying, which is preferable because there is no risk of aggregation during drying and deterioration of smoothness. Details of the aforementioned organic solvent with an SP value (δ) of 14 or more and 17 or less will be described later.

[0072] In the present invention, additives such as adhesion enhancers and antistatic agents may be added to the release layer, as long as they do not hinder the effects of the present invention. Furthermore, in order to improve adhesion to the substrate, it is also preferable to pre-treat the surface of the polyester film, such as anchor coating, corona treatment, plasma treatment, or atmospheric pressure plasma treatment, before applying the release coating layer.

[0073] The release film obtained by the present invention preferably has a peeling force of 0.01 mN / mm or more and 2.0 mN / mm or less when peeling off the ceramic green sheet. More preferably, it has a peeling force of 0.05 mN / mm or more and 1.0 mN / mm or less. A peeling force of 0.01 mN / mm or more is preferable because there is no risk of the ceramic green sheet lifting up during transport. A peeling force of 2.0 mN / mm or less is preferable because the ceramic green sheet does not lift up when peeled off. It is preferable as there is no risk of causing damage.

[0074] Because the release film obtained by the present invention uses a highly flattened base film, the surface of the release layer can be made smooth even if the thickness of the release layer is 1.0 μm or less, 0.5 μm or less, or even 0.3 μm or less. Therefore, the amount of solvent and resin used can be reduced, making it possible to create an environmentally friendly and inexpensive release film for molding ultrathin ceramic green sheets.

[0075] (Method of manufacturing release film) In another embodiment, the present invention provides a method for manufacturing a release film for resin sheet molding, comprising the following steps. A coating step of applying a release layer forming composition onto the surface layer A of a polyester film having a surface layer A, The aforementioned surface layer A is a layer that does not substantially contain inorganic particles. The release layer forming composition contains a cationic curable polydimethylsiloxane (a), Application process; A drying step in which the polyester film coated with a release layer forming composition is heat-dried, The aforementioned heating and drying process comprises a first drying step and a second drying step. A drying process in which the drying temperature T1 in the first drying process is higher than the drying temperature T2 in the second drying process; A photocuring step is performed after the drying step, in which the release layer forming composition is cured by irradiating it with active energy rays.

[0076] With the manufacturing method of the present invention, by strengthening the first drying conditions (increasing the drying), aggregation of the resin constituting the release layer can be prevented, and a release layer with high smoothness can be obtained. Furthermore, by setting the SP value of the solvent in the release layer forming composition to a predetermined value, aggregation of the resin constituting the release layer can be prevented, and a release layer with high smoothness can be obtained. Thus, the present invention makes it possible to obtain a release layer with high smoothness by having a first drying step under predetermined conditions and, in one embodiment, by using a specific solvent.

[0077] The present invention provides a method for producing a release film, comprising the following steps in order: a coating step of applying a release layer-forming composition containing at least a cationic curable polydimethylsiloxane (a) onto a surface layer A of a polyester film that is substantially free of inorganic particles; a drying step of heating and drying the film after coating, for example, using a drying oven; and a photocuring step of curing the film after heating and drying using active energy rays. In particular, it is preferable to employ a method in which the steps are carried out in the order of coating, drying, and photocuring.

[0078] The present invention's manufacturing method reveals that a highly smooth release layer can be achieved by optimizing the manufacturing conditions in the coating process. Specifically, by including an organic solvent with an SP value (δ) of 14-17 in the release layer forming composition, aggregation of the cationic curable polydimethylsiloxane (a) can be suppressed, resulting in an excellent release layer. The SP value (δ) can be used to predict the solubility of a substance, and organic solvents with an SP value (δ) of 14-17 exhibit excellent solubility for cationic curable polydimethylsiloxane (a). Therefore, even if the concentration of (a) in the release layer forming composition increases as the organic solvent dries during the drying process after the coating process, it can maintain a uniformly dissolved state, leveling cleanly without aggregation and resulting in a smooth release layer.

[0079] The content of organic solvents with an SP value (δ) of 14 to 17 in the release layer forming composition is preferably 10% by mass or more, and preferably 15% by mass or more, per 100 parts by mass of the release layer forming composition. A content of 10% by mass or more is preferable because it allows the cation-curable polydimethylsiloxane (a) to remain dissolved for a long time during drying, thus preventing aggregation and deterioration of smoothness during drying. For example, the content of organic solvents with an SP value (δ) of 14 to 17 may be 80% by mass or less, for example, 65% by mass or less, per 100 parts by mass of the release layer forming composition, and may also be less than 50% by mass.

[0080] In this specification, the SP value (δ) is based on the Hildebrand solubility parameter. The Hildebrand solubility parameter can be experimentally calculated from the Hansen solubility parameter (HSP value) as shown in Equation 1. SP value (δ) = ((δ d ) 2 +( δ p ) 2 +( δ h ) 2 ) 1 / 2 ...(Formula 1) Here (δ D ) is the dispersion force term, (δ P ) is the polar term, (δ H ) is the hydrogen bonding force term, and the Hansen solubility parameter is a concept that decomposes the Hildebrand solubility parameter into three components. Furthermore, these values ​​can also be calculated using computer software such as HSPiP (Hansen Solubility Parameters in Practice), and the values ​​described herein are based on HSPiP ver4.0. The value used is calculated using Equation 1, based on the HSP values ​​listed in the internal database.

[0081] Examples of organic solvents with an SP value (δ) of 14-17 include n-hexane (δ: 14). 9) n-heptane (δ:15.3), n-octane (δ:15.5), isopropyl ether (δ:15.8), 1,1-diethoxyethane (δ:15.9), methyl Examples include cyclohexane (δ:16.0), cyclopentane (δ:16.5), and cyclohexane (δ:16.8).

[0082] The amount of release layer forming composition to be applied is 10 g / m². 2 Preferably, it is 8 g / m 2 The following is more preferable: Application amount of 10g / m² 2 The following conditions are preferable because, for example, when applied using a gravure coating method, liquid turbulence is less likely to occur at the kiss points between the film and the gravure roll, resulting in a release layer with excellent smoothness.

[0083] In the present invention, it is preferable that the release layer composition contains two or more solvents, at least one of which is a solvent with an SP value (δ) of 14 to 17 as described above, and at least one of which has a boiling point of 100°C or higher. By adding a solvent with a boiling point of 100°C or higher, bumping during drying can be prevented, the coating film can be leveled, and the smoothness of the coating film surface after drying can be improved. The amount added is preferably about 10 to 70% by mass of the total release layer forming composition. Examples of solvents with a boiling point of 100°C or higher include toluene, xylene, n-octane, cyclohexanone, methyl isobutyl ketone, propylene glycol monomethyl ether, propylene glycol monopropyl ether, isobutyl acetate, and n-butanol.

[0084] In the present invention, it is preferable to filter the coating liquid of the release layer forming composition before application. The filtration method is not particularly limited and known methods can be used, but it is preferable to use a surface type, depth type, or adsorption type cartridge filter. Using a cartridge type filter is preferable because it can be used when continuously supplying the coating liquid from the tank to the coating area, thus improving productivity and efficient filtration. The filtration accuracy of the filter is preferably such that it removes 99% or more of particles with a size of 1 μm, and more preferably it is such that it can filter 99% or more of particles with a size of 0.5 μm. Using a filter with the above filtration accuracy is preferable because it is possible to remove foreign matter mixed into the coating liquid that forms the release layer, reduce the amount of foreign matter adhering to the release film of the present invention, and obtain a release layer with excellent smoothness.

[0085] Any known coating method can be applied to the above coating liquid. For example, conventional methods such as roll coating methods including gravure coating and reverse coating, bar coating methods such as wire bar coating, die coating, spray coating, and air knife coating can be used.

[0086] Methods for applying the release layer forming composition onto a base film and drying it include known methods such as hot air drying and infrared heaters, but hot air drying, which has a faster drying speed, is preferred. Drying in a drying oven is preferred, and there are no particular limitations; known drying ovens can be used. Regarding the type of drying oven, either a roll support type or a floating type is acceptable, but the roll support type is preferred because it allows for a wider range of adjustment of the airflow during drying, so the airflow can be adjusted according to the type of release layer.

[0087] The drying process can be divided into two drying processes: an initial constant-rate drying process (hereinafter referred to as the first drying process) and a reduction-rate drying process (hereinafter referred to as the second drying process). The two processes are preferably consecutive in the order of the first drying process followed by the second drying process, and can be distinguished by dividing the drying oven into zones. The first (initial) drying process is in the first drying oven, and the second ( The later drying process can be carried out using a second drying oven.

[0088] The inventors have found that in order to improve the smoothness of the release layer, it is important that the drying temperature T1 in the first drying step is higher than the drying temperature T2 in the second drying step. It is preferable that the temperatures of the first and second drying ovens be within the ranges described below. By manufacturing under these conditions, the constant rate drying time in the first drying step can be shortened and the decay rate drying time in the second drying step can be lengthened, resulting in a release layer with excellent flatness, which is preferable.

[0089] Furthermore, the inventors found that it is important to increase the temperature inside the first drying oven to shorten the constant-rate drying time. More specifically, the drying temperature T1 is preferably 90°C or higher and 180°C or lower, and preferably 100°C or higher and 150°C or lower. Increasing the temperature in the first drying oven and shortening the constant-rate drying time is preferable because it prevents aggregation of the cation-curable polydimethylsiloxane (a) contained in the release layer forming composition. A higher temperature in the first drying oven is preferable because it shortens the constant-rate drying time, but if it is too high, the flatness of the film deteriorates due to heat, so it is preferable to keep it at 180°C or lower. A temperature of 90°C or higher is preferable because it provides sufficient drying capacity.

[0090] The temperature inside the second drying oven is preferably 60°C to 140°C, and more preferably 80°C to 120°C. In the second drying step, slowing down the drying time allows drying without roughening the surface of the release layer before photocuring, and is preferable because it improves the smoothness of the release layer.

[0091] For example, it is preferable that the constant-rate drying time in the first drying step is shorter than the decay-rate drying time in the second drying step. This prevents deterioration of the film's flatness and allows drying without roughening the surface of the release layer before photocuring, thereby improving the smoothness of the release layer.

[0092] The time from application to entering the first drying oven is preferably 0.1 seconds or more and 2.5 seconds or less, preferably 0.1 seconds or more and 2.0 seconds or less, and the shorter the time, the better. By shortening the time to enter the first drying oven, the drying time in the first drying step can be shortened, the aggregation of cation-curable polydimethylsiloxane (a) is suppressed, and a release layer with excellent smoothness can be obtained, which is preferable. The time to enter the drying oven can be calculated from the processing speed and the structure of the processing machine stand.

[0093] The manufacturing method of the present invention includes a photocuring step in which the release layer forming composition is cured by irradiating it with active energy rays after the drying step. In the photocuring process, the cation curing reaction of the release layer-forming composition after drying is promoted by irradiation with an active energy ray. Known technologies such as ultraviolet light and electron beams can be used as the active energy ray, with ultraviolet light being preferred. The integrated light dose when using ultraviolet light can be expressed as the product of illuminance and irradiation time. For example, 10 to 500 mJ / cm². 2 It is preferable that the value is above the lower limit because it allows the release layer to harden sufficiently. It is also preferable that the value is below the upper limit because it suppresses thermal damage to the film due to heat during irradiation and maintains the smoothness of the release layer surface.

[0094] When irradiating with active energy rays, it is preferable to hold the back surface of the film with a backup roll. Providing a backup roll allows the distance from the active energy ray source to be kept constant, which is preferable as it allows for uniform irradiation. Furthermore, it is preferable to cool the surface of the backup roll and irradiate the film with active energy rays while cooling it. Cooling is preferable because it reduces the film's susceptibility to thermal damage even when irradiated with active energy rays, and helps maintain the smoothness of the release layer surface.

[0095] In one embodiment, the manufacturing method of the present invention provides a method for producing a release film for manufacturing a resin sheet containing an inorganic compound.

[0096] (Resin sheet) The resin sheet in the present invention is not particularly limited as long as it is a sheet containing resin. In one embodiment, the release film of the present invention is a release film for molding a resin sheet containing an inorganic compound. Examples of inorganic compounds include metal particles, metal oxides, minerals, etc., such as calcium carbonate, silica particles, aluminum particles, and barium titanate particles. Because the present invention has a highly smooth release layer, even when these inorganic compounds are included in the resin sheet, it is possible to suppress defects that may be caused by the inorganic compounds, such as damage to the resin sheet and difficulty in peeling the resin sheet from the release layer. The resin components forming the resin sheet can be appropriately selected depending on the application. In one embodiment, the resin sheet containing an inorganic compound is a ceramic green sheet. For example, the ceramic green sheet may contain barium titanate as the inorganic compound. Furthermore, the resin component may include, for example, a polyvinyl butyral resin. In one embodiment, the resin sheet has a thickness of 0.2 μm or more and 1.0 μm or less. For example, the present invention can provide a method for producing a release film for manufacturing a resin sheet containing such an inorganic compound. Furthermore, the method for producing a release film for resin sheet molding according to the present invention includes a step of molding a resin sheet having a thickness of 0.2 μm or more and 1.0 μm or less. It may be included.

[0097] (Ceramic green sheet and ceramic capacitor) Generally, a multilayer ceramic capacitor has a rectangular parallelepiped ceramic body. Inside the ceramic body, first internal electrodes and second internal electrodes are alternately arranged along the thickness direction. The first internal electrodes are exposed on the first end face of the ceramic body. A first external electrode is provided on the first end face. The first internal electrodes are electrically connected to the first external electrode at the first end face. The second internal electrodes are exposed on the second end face of the ceramic body. A second external electrode is provided on the second end face. The second internal electrodes are electrically connected to the second external electrode at the second end face.

[0098] In one embodiment, the release film of the present invention is a release film for manufacturing ceramic green sheets and is used to manufacture such multilayer ceramic capacitors. For example, a method for manufacturing ceramic green sheets using the release film for manufacturing ceramic green sheets of the present invention can produce ceramic green sheets having a thickness of 0.2 μm or more and 1.0 μm or less. More specifically, the ceramic green sheet is manufactured as follows: First, the release film of the present invention is used as a carrier film, and a ceramic slurry for forming the ceramic body is applied and dried. There is a growing demand for extremely thin ceramic green sheets with a thickness of 0.2 to 1.0 μm. A conductive layer for forming the first or second internal electrode is printed on the applied and dried ceramic green sheet. A mother laminate is obtained by appropriately laminating the ceramic green sheet, the ceramic green sheet with the conductive layer for forming the first internal electrode printed on it, and the ceramic green sheet with the conductive layer for forming the second internal electrode printed on it, and pressing them. The mother laminate is divided into multiple parts to produce raw ceramic bodies. Ceramic bodies are obtained by firing the raw ceramic bodies. After that, a multilayer ceramic capacitor can be completed by forming the first and second external electrodes. [Examples]

[0099] The present invention will be described in more detail below using examples, but the present invention is not limited in any way by these examples. The characteristic values ​​used in the present invention were evaluated using the following method.

[0100] (Release layer thickness) The cut-out release film was embedded in resin and then ultrathin sectioned using an ultramicrotome. Cross-sectional observation was then performed using a JEOL JEM2100 transmission electron microscope, and the thickness of the release layer was measured from the observed TEM images. If the thickness was too thin to be accurately evaluated by cross-sectional observation, a reflectance spectrophotometer (Otsuka Electronics FE-3000) was used for measurement.

[0101] (Weight of the release layer) In this specification, the weight per 1 μm of release layer thickness is 1 g / m². 2 The weight value calculated as follows was adopted. For example, if the release layer thickness measured by the method described above is 0.2 μm, the total weight of the release layer is 0.2g / m 2 Furthermore, the release layer contains cationic curable polydimethylsiloxane ( a) The weight of the cation-curing resin (b) and the acid generator (c) are the weights of the release layer forming components. The values ​​used were calculated from the mixing ratio of each component contained in the product and the total weight of the release layer. For example, the release layer thickness is 0.2 μm, and the release layer weight is cation-curable polydimethylsiloxane (a). When the ratio is 5 parts by mass, the weight of (a) contained in the release layer is 0.01 g / m³ 2 The release layer weight ratio (mass%) was calculated assuming that the sum of component (a) and component (b) was 100 parts by mass.

[0102] (Amount of release layer forming composition applied) The values ​​used were calculated from the liquid consumption weight and processing area of ​​the release layer forming composition used in the coating process.

[0103] (Time from application to the first drying oven) The values ​​used were calculated from the film travel distance from the coating section to the first drying oven and the processing speed.

[0104] (Surface roughness Sa, maximum protrusion height Sp) The surface shape was measured using a non-contact surface shape measurement system (VertScan R550H-M100) under the following conditions. The average surface roughness (Sa) of the region was taken as the average of 5 measurements, and the maximum protrusion height (Sp) was taken as the highest value from the 5 measurements obtained after excluding the maximum and minimum values ​​from 7 measurements. (Measurement conditions) • Measurement mode: WAVE mode • Objective lens: 50x 0.5x Tube Lens ·Measurement area 187μm×139μm (Analysis conditions) • Surface correction: 4th order correction • Interpolation process: Full interpolation

[0105] (Number of protrusions with a height of 10 nm or more, number of protrusions with a height of 5 nm or more) Particle analysis was performed using the measurement data representing the center value from all seven measurements taken to determine the maximum protrusion height. The particle analysis was performed using the Vertscan R550H-M100 analysis software under the following conditions: Particle analysis was performed on the same measurement area as the above-mentioned surface roughness and maximum protrusion height measurements, and the number of protrusions with a maximum thickness of 10 nm or more, or 5 nm or more, was calculated. The number of protrusions was 1 mm. 2 The converted value was used. (Particle analysis conditions) • Surface correction: 4th order correction • Storage process: Full interpolation ·Surprise analysis • Reference height: Zero plane

[0106] (Ceramic sheet peeling force) Slurry composition I, consisting of the materials listed below, was stirred and mixed for 10 minutes, and then dispersed using a bead mill with 0.5 mm diameter zirconia beads for 10 minutes to obtain a primary dispersion. Subsequently, slurry composition II, consisting of the materials listed below, was added to the primary dispersion in a ratio of (slurry composition I):(slurry composition II) = 3.4:1.0, and secondary dispersion was performed using a bead mill with 0.5 mm diameter zirconia beads for 10 minutes to obtain a ceramic slurry. (Slurry composition I) Toluene 22.3 parts by mass Ethanol 18.3 parts by mass Barium titanate (average particle size 100 nm) 57.5 parts by mass Homogenol L-18 (manufactured by Kao Corporation) 1.9 parts by mass (Slurry Composition II) Toluene 39.6 parts by mass Ethanol 39.6 parts by mass Dioctyl phthalate 3.3 parts by mass Polyvinyl butyral (Sekisui Chemical Co., Ltd., Esrec BM-S) 16.3 parts by mass 1-Ethyl-3-methylimidazolium ethyl sulfate 0.5 parts by mass Next, the release surface of the obtained release film sample was coated using an applicator so that the slurry after drying was 1.0 μm thick, and dried at 60°C for 1 minute to obtain a release film with a ceramic green sheet. The obtained release film with a ceramic green sheet was destaticized using a static eliminator (Keyence Corporation, SJ-F020), and then peeled using a peel tester (Kyowa Interface Science Co., Ltd., VPA-3, load cell load 0.1 N) at a peel angle of 90 degrees, peel temperature of 25°C, and peel speed of 10 m / min. For peeling, double-sided adhesive tape (Nitto Denko Corporation, No. 535A) was attached to a SUS plate attached to the peel tester, and the release film was fixed on top of it with the ceramic green sheet side adhering to the double-sided tape, and then peeled by pulling the release film side. From the obtained measured values, the average value of the peel force for peel distances of 20 mm to 70 mm was calculated and this value was defined as the peel force. A total of 5 measurements were performed, and the average value of the peel force was adopted for evaluation. The peeling force values ​​obtained were evaluated according to the following criteria. ○: 0.1 mN / mm or more, less than 1.0 mN / mm ×: 1.0 mN / mm or higher

[0107] (Pinhole evaluation of ceramic green sheets) A ceramic green sheet with a thickness of 1 μm was molded onto the release surface of the release film in the same manner as the release properties evaluation of the ceramic slurry described above. Next, the release film was peeled off from the molded ceramic green sheet attached to the release film to obtain the ceramic green sheet. In the central region of the obtained ceramic green sheet in the film width direction, 25 cm 2 Within the specified range, light was shone from the opposite side of the coated surface of the ceramic slurry, and the occurrence of pinholes visible through the transmitted light was observed and visually judged according to the following criteria. ○: No pinholes were found. ×: One or more pinholes have occurred.

[0108] (Preparation of polyethylene terephthalate pellets (PET (I))) A continuous esterification reactor consisting of a three-stage complete mixing tank equipped with a stirrer, a partial condenser, a raw material inlet, and a product outlet was used as the esterification reactor. Terephthalic acid (TPA) was supplied at a rate of 2 tons / hour, ethylene glycol (EG) at a ratio of 2 moles per mole of TPA, and antimony trioxide was added in an amount that resulted in 160 ppm of Sb atoms relative to the produced PET. This slurry was continuously supplied to the first esterification reactor of the esterification reactor and reacted at atmospheric pressure at 255°C for an average residence time of 4 hours. Next, the reaction products from the first esterification reactor were continuously removed from the system and supplied to the second esterification reactor. EG distilled off from the first esterification reactor was supplied to the second esterification reactor at 8% by mass relative to the generated PET. Furthermore, an EG solution containing magnesium acetate tetrahydrate in an amount that resulted in 65 ppm of Mg atoms relative to the generated PET, and an EG solution containing TMPA (trimethyl phosphate) in an amount that resulted in 40 ppm of P atoms relative to the generated PET were added, and the reaction was carried out at atmospheric pressure at 260°C for an average residence time of 1 hour. Next, the reaction products from the second esterification reactor were continuously removed from the system and supplied to the third esterification reactor, and the mixture was dispersed at 39 MPa (400 kg / cm²) using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.).2 0.2% by mass of porous colloidal silica with an average particle size of 0.9 μm, which was dispersed by a dispersion treatment with an average of 5 passes at a pressure of ) and 0.4% by mass of synthetic calcium carbonate with an average particle size of 0.6 μm, which had 1% by mass of polyacrylic acid ammonium salt attached to calcium carbonate, were added as 10% EG slurry each and reacted at atmospheric pressure at 260°C with an average residence time of 0.5 hours. 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 after filtration with a filter made of sintered stainless steel fibers with a 95% cut diameter of 20 μm, it was extruded into water by ultrafiltration, cooled and cut into chips to obtain PET chips with an intrinsic viscosity of 0.60 dl / g (hereinafter abbreviated as PET(I)). The lubricant content in the PET chips was 0.6% by mass.

[0109] (Preparation of polyethylene terephthalate pellets (PET(II))) On the other hand, in the production of the above-mentioned PET(I) chip, a PET chip with an intrinsic viscosity of 0.62 dl / g that does not contain any particles such as calcium carbonate or silica was obtained (hereinafter abbreviated as PET(II)).

[0110] (Manufacturing of laminated film X1) After drying these PET chips, they are melted at 285°C and then melted again at 290°C in a separate extruder. This process involves two stages of filtration: one with a sintered filter containing stainless steel fibers with a 95% cut diameter of 15 μm, and another with a sintered filter containing stainless steel particles with a 95% cut diameter of 15 μm. The mixture is then combined in a feed block to form PET(I) into surface layer B (releasing type). The surface layer (side layer) and PET(II) were laminated so that they would form the surface layer A (release side layer), and the sheets were extruded (cast) at a speed of 45 m / min. The sheets were then electrostatically bonded and cooled on a casting drum at 30°C using the electrostatic adhesion method to obtain an unstretched polyethylene terephthalate sheet with an intrinsic viscosity of 0.59 dl / g. The layer ratio was calculated using the discharge rate of each extruder, and was PET(I) / (II) = 6 The composition was adjusted to 0% by mass / 40% by mass. Next, the unstretched sheet was heated with an infrared heater and then stretched 3.5 times in the longitudinal direction by the speed difference between the rolls at a roll temperature of 80°C. After that, it was guided to a tenter and stretched 4.2 times in the transverse direction at 140°C. Next, it was heat-treated at 210°C in a heat-setting zone. After that, a 2.3% relaxation treatment was performed in the transverse direction at 170°C to obtain a biaxially oriented polyethylene terephthalate film X1 with a thickness of 31 μm. The Sa of surface layer A of the obtained film X1 was 1 nm, and the Sa of surface layer B was 28 nm.

[0111] (Manufacturing of laminated film X2) As the laminated film X2, E5101 (Toyobo Ester® film, manufactured by Toyobo Co., Ltd.) with a thickness of 25 μm was used. E5101 has a structure in which particles are contained in surface layer A and surface layer B. The Sa of surface layer A of laminated film X2 was 24 nm, and the Sa of surface layer B was also 24 nm.

[0112] (Cationically curable polydimethylsiloxane (a)) (a)-1: UV POLY215 (manufactured by Arakawa Chemical Industries, 100% solids content)

[0113] (Cation-cured resin (b)) (b)-1: Celoxide 2021P (manufactured by Daicel Corporation, 100% solids) (b)-2: X-40-2670 (manufactured by Shin-Etsu Chemical Co., Ltd., solids content 100%)

[0114] (Acid generator (c)) (c)-1: CPI-101A (manufactured by Sunapro, 50% solids content)

[0115] (Example 1) A release layer forming composition 1 with the following composition is applied to the surface layer A of the laminated film X1 using reverse gravure at a rate of 5.0 g / m² after passing it through a filter capable of removing 99% or more of foreign matter larger than 0.5 μm. 2 It was coated in such a way. Then, after 0.5 seconds, it was placed into the first drying oven. The processing speed was adjusted, and the material was continuously heated and dried at a first drying oven temperature of 120°C and a second drying oven temperature of 90°C. After the drying process, an ultraviolet irradiation unit (Heraeus, H-bulb) was used on a cooling roll to deliver an integrated light intensity of 100 mJ / cm². 2 By irradiating with ultraviolet light, the release layer is cured, resulting in a resin sheet. A mold release film was obtained. Furthermore, the smoothness, peelability, and pinhole properties of the obtained release film were evaluated, and the results were good, as shown in Table 1. Thus, the resulting release film for resin sheet molding has a thickness of, for example, 0.2 μm or more. This release film was capable of manufacturing resin sheets with a thickness of 1.0 μm or less. Note that the weight (mg / m³) of each component (a), (b), and (c) listed in the table is... 2 ) indicates the content ratio per solid (weight of each component relative to the total weight of the release layer). (Release layer forming composition 1) Methyl ethyl ketone 24,000 parts by mass (SP value (δ): 19.1, (δ D ):16.0, (δ P ):9.0, (δ H ):5. 1) Toluene 24,000 parts by mass (SP value (δ): 18.2, (δ D ):18.0, (δ P ):1.4, (δ H ):2. 0) n-heptane 48,000 parts by mass (SP value (δ): 15.3, (δ D ): 15.3, (δ P ):0.0, (δ H ):0. 0) (a)-1 0.039 parts by mass (b)-1 3.883 parts by mass (c)-1 0.078 parts by mass

[0116] (Examples 2-4) A release film for resin sheet molding was obtained in the same manner as in Example 1, except that the composition and manufacturing method of the release layer were changed as shown in Table 1.

[0117] (Example 5) A release film for resin sheet molding was obtained in the same manner as in Example 1, except that a release layer forming composition 2 having the composition described below was used. (Release layer forming composition 2) Methyl ethyl ketone 38,400 parts by mass (SP value (δ): 19.1, (δ D ):16.0, (δ P ):9.0, (δ H ):5. 1) Toluene 38,400 parts by mass (SP value (δ): 18.2, (δ D ):18.0, (δ P ):1.4, (δ H ):2. 0) n-heptane 19,200 parts by mass (SP value (δ): 15.3, (δ D ): 15.3, (δ P ):0.0, (δ H ):0.0)(a)-1 0.196 parts by mass (b)-1 3.726 parts by mass (c)-1 0.078 parts by mass

[0118] (Example 6) n-heptane in the release layer forming composition is cyclohexane (SP value (δ): 16.8, (Erotic manga) D ):16.8, (δ P ):0.0, (δ H Except for the change to ):0.2), the example A release film for resin sheet molding was obtained using the same method as in 2.

[0119] (Examples 7, 8) A release film for resin sheet molding was obtained in the same manner as in Example 2, except that the coating amount and solid content ratio were changed as shown in Table 1. At this time, the organic solvent ratio was prepared to be the same as that of release layer forming composition 1.

[0120] (Example 9) A release film for resin sheet molding was obtained in the same manner as in Example 1, except that the release layer forming composition 3 had the following composition. (Composition for forming a release layer 3) Methyl ethyl ketone 24,000 parts by mass (SP value (δ): 19.1, (δ D ):16.0, (δ P ):9.0, (δ H ):5. 1) Toluene 24,000 parts by mass (SP value (δ): 18.2, (δ D ):18.0, (δ P ):1.4, (δ H ):2. 0) n-heptane 48,000 parts by mass (SP value (δ): 15.3, (δ D ): 15.3, (δ P ):0.0, (δ H ):0. 0) (a)-1 0.039 parts by mass (b)-2 3.883 parts by mass (c)-1 0.078 parts by mass

[0121] (Examples 10-12) A release film for resin sheet molding was obtained in the same manner as in Example 1, except that the composition and manufacturing method of the release layer were changed as shown in Table 1.

[0122] (Example 13) A release film for resin sheet molding was obtained in the same manner as in Example 1, except that a release layer forming composition 4 having the composition described below was used. (Release layer forming composition 4) Methyl ethyl ketone 38,400 parts by mass (SP value (δ): 19.1, (δ D ): 16.0, (δ P ): 9.0, (δ H ): 5. 1) Toluene 38.400 parts by mass (SP value (δ): 18.2, (δ D ): 18.0, (δ P ): 1.4, (δ H ): 2. 0) Normal heptane 19.200 parts by mass (SP value (δ): 15.3, (δ D ): 15.3, (δ P ): 0.0, (δ H ): 0. 0) (a)-1 0.196 parts by mass (b)-2 3.726 parts by mass (c)-1 0.078 parts by mass

[0123] (Example 14) A release film for resin sheet molding was obtained in the same manner as in Example 2, except that normal heptane in the release layer forming composition was changed to cyclohexane (SP value (δ): 16.8, (δ D ): 16.8, (δ P ): 0.0, (δ H ): 0.2). A release film for resin sheet molding was obtained in the same manner as in Example 2, except that normal heptane in the release layer forming composition was changed to cyclohexane (SP value (δ): 16.8,

[0124] (Examples 15, 16) A release film for resin sheet molding was obtained in the same manner as in Example 2, except that the coating amount and solid content ratio described in Table 1 were changed. At this time, the organic solvent ratio was adjusted to be the same as that of the release layer forming composition 3.

[0125] (Example 17) An ultra-thin layer release film for resin sheet molding was obtained in the same manner as in Example 1, except that the release layer forming composition 5 having the following composition was used. (Release layer forming composition 5) Methyl ethyl ketone 24.950 parts by mass (SP value (δ): 19.1, (δ D ): 16.0, (δ P ): 9.0, (δ H ): 5. 1) Toluene 24.950 parts by mass (SP value (δ): 18.2, (δ D ): 18.0, (δ P ): 1.4, (δ H ): 2. 0) Heptane 49.900 parts by mass (SP value (δ): 15.3, (δ D ): 15.3, (δ P ): 0.0, (δ H ): 0. 0) (a)-1 0.196 parts by mass​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​P ):9.0, (δ H ):5. 1) Heptane 19.960 parts by mass (SP value (δ): 15.3, (δ D ): 15.3, (δ P ):0.0, (δ H ):0. 0) (a)-1 0.196 parts by mass (c)-1 0.004 parts by mass

[0129] (Example 21) Heptane in release layer forming composition 5 is cyclohexane (SP value (δ): 16.8, (δ D ):16.8, (δ P ):0.0, (δ H Except for the change to ):0.2), it is the same as Example 1. A release film for resin sheet molding was obtained using the following method.

[0130] (Examples 22, 23) A release film for resin sheet molding was obtained in the same manner as in Example 17, except that the coating amount and solid content concentration were changed as shown in Table 1. At this time, the organic solvent ratio was prepared to be the same as that of release layer forming composition 5.

[0131] (Comparative Example 1) A release film for molding an ultrathin resin sheet was obtained in the same manner as in Example 1, except that the release layer forming composition 7 had the composition described below. (Release layer forming composition 7) Methyl ethyl ketone 24,000 parts by mass (SP value (δ): 19.1, (δ D ):16.0, (δ P ):9.0, (δ H ):5. 1) Toluene 24,000 parts by mass (SP value (δ): 18.2, (δ D ):18.0, (δ P ):1.4, (δ H ):2. 0) n-heptane 48,000 parts by mass (SP value (δ): 15.3, (δ D ): 15.3, (δ P ):0.0, (δ H ):0. 0) (b)-1 3.922 parts by mass (c)-1 0.078 parts by mass

[0132] (Comparative Example 2) A release film for molding an ultrathin resin sheet was obtained in the same manner as in Example 10, except that it was applied to a laminated film X2.

[0133] (Comparative Examples 3, 4) A release film for molding ultrathin resin sheets was obtained using the same method as in Example 10, except that the manufacturing method was changed to the one described in Table 1.

[0134] (Comparative Example 5) A release film for molding ultrathin resin sheets was obtained using the same method as in Example 17, except that the manufacturing method was changed to the one described in Table 1.

[0135] (Comparative Example 6) A release film for molding an ultrathin resin sheet was obtained in the same manner as in Example 1, except that a release layer forming composition 8 having the composition described below was used. (Release layer forming composition 8) Methyl ethyl ketone 48,000 parts by mass (SP value (δ): 19.1, (δ D ):16.0, (δ P ):9.0, (δ H ):5. 1) Toluene 48,000 parts by mass (SP value (δ): 18.2, (δ D ):18.0, (δ P ):1.4, (δ H ):2.0) (a)-1 0.196 parts by mass (b)-2 3.726 parts by mass (c)-1 0.078 parts by mass

[0136]

Table 1A

[0137]

Table 1B

[0138]

Table 1C

[0139]

Table 2A

[0140]

Table 2B

[0141]

Table 2C

[0142] In Comparative Example 1, since it did not contain the cation-curable polydimethylsiloxane (a), the peel strength of the ceramic sheet was high and it was impossible to peel. In Comparative Example 2, the number of protrusions with a height of 10 nm or more exceeded 200 per mm 2 and pinholes occurred in the green sheet which was the release object. Furthermore, in Comparative Example 2, inorganic particles were present throughout the substrate, the smoothness of the release film was extremely poor, and damage, pinholes, etc. occurred in the green sheet.

[0143] In Comparative Example 3, since the first drying temperature T1 was lower than the second drying temperature T2 and the constant rate drying time was long, aggregation of the release layer-forming composition occurred, Sa was larger than 2 nm, and the number of protrusions with a height of 10 nm or more exceeded 200 per mm 2 In Comparative Examples 4 and 5, the first drying temperature T1 is low, aggregation of the release layer-forming composition occurs, Sa is greater than 2 nm, and the number of protrusions with a height of 10 nm or more is 200 / mm 2 It exceeded [value]. In Comparative Example 6, the release layer forming composition contained Because it did not contain organic solvents with an SP value (δ) of 14-17, aggregation of the release layer-forming composition occurred during drying, resulting in a release layer with poor smoothness. [Industrial applicability]

[0144] According to the present invention, by improving the smoothness and peelability of the release layer, a release film is provided that enables the molding of resin sheets with few defects even in ultra-thin layers with a thickness of 1 μm or less, thereby enabling the manufacture of resin sheets without the risk of defects.

Claims

1. A method for manufacturing a release film for resin sheet molding, comprising a base material and a release layer, The above manufacturing method comprises the following steps: A coating step in which a release layer forming composition is applied to the surface layer A of a polyester film having a surface layer A, The aforementioned surface layer A is a layer that does not substantially contain inorganic particles. The release layer forming composition comprises a cationic curable polydimethylsiloxane (a), Coating process; A drying step in which the polyester film coated with the release layer forming composition is heat-dried, The aforementioned heating and drying process comprises a first drying step and a second drying step. A drying step in which the drying temperature T1 in the first drying step is higher than the drying temperature T2 in the second drying step; The drying step is followed by a photocuring step in which the release layer forming composition is cured by irradiating it with active energy rays; A method for producing a release film for resin sheet molding, wherein the content of cationic curable polydimethylsiloxane (a) in the release layer is 90 mg / m² or less.

2. The aforementioned release layer forming composition contains an organic solvent with an SP value (δ) of 14 or more and 17 or less. The aforementioned release layer forming composition contains an organic solvent with an SP value (δ) of 14 or more and 17 or less in an amount of 10% by mass or more per 100 parts by mass of the total weight of the release layer forming composition. In the coating step, the amount of the release layer forming composition applied is 10 g / m². 2 The following is: A method for manufacturing a release film for resin sheet molding according to claim 1.

3. A method for producing a release film for manufacturing a resin sheet containing an inorganic compound, A method for producing a release film for resin sheet molding according to claim 1 or 2, wherein the content of cationic curable polydimethylsiloxane (a) in the release layer is 50 mg / m² or less.

4. A method for producing a release film for molding a resin sheet according to claim 3, wherein the resin sheet containing an inorganic compound is a ceramic green sheet.

5. A method for manufacturing a release film for resin sheet molding according to claim 4, further comprising forming a ceramic green sheet with a thickness of 0.2 μm or more and 1.0 μm or less,

6. A method for producing a release film for molding resin sheets according to claim 3 or 4, comprising molding a resin sheet having a thickness of 0.2 μm or more and 1.0 μm or less.

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