TW202231433A - Mold release film for molding of resin sheet - Google Patents

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 release properties, and therefore, allows molding of an ultra-thin resin sheet, particularly an ultra-thin ceramic green sheet, without defect. This mold release film for molding of a resin sheet comprises: a polyester film as a base; and a mold release layer. The polyester film has a surface layer A that contains substantially no inorganic particles. The mold release layer is provided on the surface layer A. The mold release layer is made of a cured mold release layer formation composition. The mold release layer formation composition contains at least a cationic-curable polydimethylsiloxane (a). The regional surface roughness (Sa) of the mold release layer is at most 2 nm. The number of protrusions having a height of at least 10 nm present on a surface of the mold release layer is at most 200/mm2.

Description

Release film for resin sheet molding

The present invention relates to a release film for resin sheet molding, and more specifically, to a release film used for molding an ultra-thin resin sheet.

In the past, a release film with a polyester film as a base material and a release layer laminated on the base material was used as an adhesive sheet and used as a step film for forming resin sheets such as coating films, polymer films, and optical lenses. to use.

The aforementioned release film is also used as a step film for forming ceramic green bodies, such as multilayer ceramic capacitors and ceramic substrates, which require high smoothness. In recent years, with the miniaturization and higher capacitance of multilayer ceramic capacitors, the thickness of the ceramic green body also tends to be thinned. The ceramic green body is molded by applying a slurry containing a ceramic component such as barium titanate and a binder resin onto a release film and drying it. The formed ceramic green body is printed with electrodes and peeled from the release film, and the ceramic green body obtained by lamination, pressurization, firing, and external electrode coating is used to manufacture a multilayer ceramic capacitor.

When a ceramic green body is formed on the surface of the release layer of the polyester film substrate, the tiny protrusions on the surface of the release layer will affect the formed ceramic green body, and it is easy to produce defects such as cissing or pinholes. This is the problem. In recent years, the further thinning of the ceramic green body has been carried out, and a ceramic green body having a thickness of 1.0 μm or less, more specifically, 0.2 μm to 1.0 μm, has been gradually demanded. For this reason, the requirements for the smoothness of the surface of the release layer are further increased. In addition, the microscopic protrusions and foreign matter on the release layer are involved in the deformation of the ceramic green body to be molded, and there are problems that pinholes and fragments during peeling are easily generated.

In addition, once the ceramic green body is thinned, the releasability at the time of peeling the ceramic green body from the release film becomes more important. If the peeling force is large and uneven, the ceramic green body will be damaged during the peeling step, resulting in sheet defects, uneven thickness, pinholes, and fragments. This is the problem. Therefore, it is required to peel the ceramic green body with a lower and uniform force. That is, in order to manufacture an ultra-thin resin sheet without defects, especially a ceramic green body without defects, a release film having extremely high smoothness and excellent releasability is required.

As a release film excellent in smoothness and releasability, the patent documents described below are mentioned. For example, Patent Document 1 proposes a release film having a release layer using a radical-curable resin as a main component. Patent Document 2 proposes a release film in which a smoothing layer and a release layer are laminated. Patent Document 3 proposes a release film having a release layer using a cationically curable epoxy resin as a main component. Patent Document 4 proposes a release film having a release layer using a cation-curable polydimethylsiloxane as a main component. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5492352. [Patent Document 2] Japanese Patent Laid-Open No. 2015-164762. [Patent Document 3] International Publication No. 2018/079337. [Patent Document 4] Japanese Patent Laid-Open No. 2016-079349.

[The problem to be solved by the invention]

However, the release film of Patent Document 1 has a problem that the smoothness of the release layer is not sufficient because the release layer is provided on the base film having insufficient smoothness. In addition, the inventors of the present invention have found that the resin of the radical hardening type is not hardened due to the inhibition of oxygen, so the solvent resistance of the surface of the release layer is poor, and the release layer may be damaged during the molding of the ceramic green body or The organic solvent used in the printing of the internal electrodes is corroded, and there is a problem that the peelability is deteriorated. The invention of Patent Document 2 uses a thermosetting melamine resin for the smoothing coating layer and the release coating layer, and requires high heat in order to accelerate the curing reaction. Therefore, there is a possibility that the flatness of the release film may be damaged by the heat during processing. In addition, due to the need for multiple processing of the smoothing coating layer and the release coating layer, there is not only the possibility of foreign matter being mixed into the release film, but also the possibility of scars on the release layer, and there is a fear that the ceramic green body formed on the release layer will be damaged. Difficulty occurs due to foreign matter or scratches being transferred.

Patent Document 3 and Patent Document 4 propose a release layer using a cation-curable resin, respectively, in order to improve curing defects due to oxygen inhibition and flat defects due to processing heat. However, since the release film of Patent Document 3 lacks the smoothness of the base film, the smoothness of the surface of the release layer is poor. In addition, the release agent component disclosed in Patent Document 3 lacks reactivity, is poor in solvent resistance, and has problems in releasability. Since the release film of Patent Document 4 has a release layer using a liquid cation-curable polydimethylsiloxane resin as a main component, the resin aggregates on the unevenness of the base film and the oligomers present on the surface of the base film. If there are protrusions such as objects, flatness problems may occur. In addition, the crosslinking density of the release layer is low, and there is also a problem in peelability.

The present invention has been made on the background of the problems of the related prior art. That is, the purpose is to provide a release film having a release layer particularly excellent in smoothness and peelability, and further, to provide a resin sheet, especially an ultra-thin layer, which can be formed into an ultra-thin layer without defects. The release film of the ceramic green body. [means to solve the problem]

The inventors of the present invention, as a result of diligent research in order to solve the above-mentioned problems, found that the above-mentioned object can be achieved by a release film having the following constitution, and completed the present invention.

That is, the present invention has the following constitution. [1] A release film for forming a resin sheet, comprising a polyester film as a base material and a release layer; the polyester film has a surface layer A substantially free of inorganic particles; the surface layer A has the release film mold layer; the aforementioned release layer is a layer in which the release layer-forming composition is hardened; the aforementioned release layer-forming composition contains cationic hardening polydimethylsiloxane (a); the region surface roughness of the aforementioned release layer (Sa) is 2 nm or less; the number of protrusions with a height of 10 nm or more existing on the surface of the release layer is 200 pieces/mm ² or less. [2] In one embodiment, the maximum protrusion height (Sp) of the release layer is 20 nm or less, and the number of protrusions with a height of 5 nm or more to less than 10 nm and the number of protrusions with a height of 10 nm or more existing on the surface of the release layer The total is 1500 pieces/mm ² or less. [3] In one embodiment, the cation-curable polydimethylsiloxane (a) has at least one function selected from vinyl ether group, oxetanyl group, epoxy group, and alicyclic epoxy group base. [4] In one embodiment, the content of the cation-curable polydimethylsiloxane (a) contained in the release layer is 90 mg/m ² or less. [5] In one embodiment, the release layer-forming composition further contains a cationic hardening compound (b-1) without a polysiloxane skeleton; the cationic hardening compound (b-1) has two or more in the molecule The alicyclic epoxy group, the content of the cationic hardening compound (b-1) relative to the total of 100 parts by mass of the cationic hardening polydimethylsiloxane (a) and the cationic hardening compound (b-1) It is 80 mass % or more. [6] In one embodiment, the release layer forming composition further contains a cyclosiloxane compound (b-2) having an alicyclic epoxy group; the cyclosiloxane compound (b-2) is There are two or more alicyclic epoxy groups in the molecule, and the cyclic silicon The content of the oxane compound (b-2) is 80% by mass or more. [7] 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 is relative to the total amount of the release layer-forming composition. The aforementioned organic solvent having an SP value (δ) of 14 or more and 17 or less is contained in 100 parts by mass by weight in an amount of 10% by mass or more. [8] In one embodiment, a release film is provided for producing an inorganic compound-containing resin sheet. [9] In one embodiment, the inorganic compound-containing resin sheet is a green ceramic body. [10] In one embodiment, a release film is provided for molding a resin sheet with a thickness of 0.2 μm or more and 1.0 μm or less. [Inventive effect]

The release film for resin sheet molding of the present invention can improve the smoothness and peelability of the release layer, thereby suppressing the occurrence of defects in the ultra-thin layer resin sheet, especially the ceramic green body.

Hereinafter, the present invention will be described in detail. The present invention is a release film for resin sheet molding, comprising a polyester film as a base material and a release layer; the polyester film has a surface layer A substantially free of inorganic particles; the surface layer A has a release layer; The release layer is a hardened layer of the release layer-forming composition; the release layer-forming composition contains cationic hardening polydimethylsiloxane (a); the area surface roughness (Sa) of the release layer is below 2nm ; The number of protrusions with a height of 10 nm or more on the surface of the release layer is 200/mm ² or less.

The present invention having such a configuration is excellent in smoothness and peelability of the release layer, so that, for example, for a resin sheet having a thickness of 0.2 μm to 1.0 μm or less, a uniform thickness can be provided without defects, and defects such as pinholes can be suppressed. In addition, the present invention can exhibit the following effects. In the present invention, since the release layer is provided on the base film with sufficient smoothness, the smoothness of the release layer can also be ensured. Furthermore, the present invention can suppress the poor curing due to oxygen barrier in the release layer, and can exert high crosslinking of the release layer. The present invention which can exert such an effect can improve the solvent resistance of the surface of the release layer, for example. By improving the solvent resistance of the surface of the release layer, the release layer can be prevented from being eroded by the organic solvent used in the molding of the ceramic green body and the printing of the internal electrodes, and has high peelability. In addition, according to the present invention, compared with, for example, a release layer having a thermosetting melamine resin, high heat is not required in order to promote the hardening reaction. Therefore, the flatness of the release film can be suppressed from being damaged by heat during processing. In addition, in the production method of the present invention, by going through the coating step and the drying step of the present invention, aggregation of the release layer forming composition can be suppressed, and a release film having a release layer with extremely high smoothness can be obtained.

More specifically, the composition for forming a release layer containing a predetermined amount of cation-curable polydimethylsiloxane (a) is applied to the surface layer A of the base film that does not substantially contain inorganic particles, and After hardening, a release layer with extremely high smoothness can be obtained. Furthermore, by controlling the content of the cationic hardening polydimethylsiloxane (a) in the release layer to be below a predetermined amount, the cationic hardening polydimethylsiloxane can be suppressed during the processing of the release layer. The alkane (a) aggregates extremely minute foreign matter and oligomer-derived minute protrusions present in the base film. Although it should not be construed as being limited to a specific theory, by increasing the first drying temperature (intensive drying), the component (a) can be prevented from agglomerating with respect to the fine protrusions originating from the original roll body. In addition, by suppressing poor hardening caused by oxygen barrier, improving the solvent resistance of the surface of the release layer, preventing foreign matter from mixing into the release layer, and suppressing the scratches of the release layer, it can prevent the ceramic green body from being released. Damage, scratches, foreign matter, etc. during peeling are caused by sheet deformation due to transfer. As a result, a release layer excellent in smoothness, hardness, releasability, and contamination prevention to the release layer can be obtained. In addition, during drying of the organic solvent contained in the release layer forming composition, the cation-curable polydimethylsiloxane (a) becomes less likely to aggregate, and a release layer excellent in smoothness can be obtained. Details will be described later.

Moreover, this invention provides the manufacturing method of the release film for resin sheet shaping|molding which has the following steps in another aspect. The coating step is to coat a release layer forming composition on the surface layer A of the polyester film with the surface layer A, the surface layer A is a layer that does not substantially contain inorganic particles, and the release layer forming composition contains a cationic hardening type Polydimethylsiloxane (a); drying step, heating and drying the polyester film coated with the release layer forming composition, the heating drying has a first drying step and a subsequent second drying step, the first drying step The drying temperature T1 in the drying step is higher than the drying temperature T2 in the second drying step; and in the photohardening step, active energy rays are irradiated after the drying step to harden the release layer forming composition.

In the manufacturing method according to the present invention, particularly by setting the manufacturing conditions at the time of processing the release layer to a predetermined method, a release layer having high smoothness can be formed. For example, control of the coating amount of the composition for forming a release layer, the composition of the organic solvent, the drying time, the drying temperature, etc. can be mentioned. By producing the release film under the conditions of the present invention, the aggregation of the cation-curable polydimethylsiloxane (a) contained in the composition for forming a release layer can be suppressed, and a release layer excellent in smoothness can be obtained . Details will be described later.

(polyester film) The polyester constituting the polyester film used for the base material of the present invention is not particularly limited, and one obtained by film-forming a polyester generally used as a base material for a release film can be used. Preferably, it is a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component, such as polyethylene terephthalate, polyethylene 2,6-ethylene naphthalate, polyethylene terephthalate, and polyethylene terephthalate. Butylene phthalate, polytrimethylene terephthalate, or copolymers with the constituent components of these resins as the main component are more suitable, especially the polyester film formed by polyethylene terephthalate is particularly suitable. In polyethylene terephthalate, the repeating unit of ethylene terephthalate is preferably 90 mol% or more, more preferably 95 mol% or more, and a small amount of other dicarboxylic acid components, diols can also be copolymerized. ingredients, but in consideration of cost, it is preferably made only from terephthalic acid and ethylene glycol. In addition, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, crystallization agents, etc. may be added within the range that does not hinder the film effect of the present invention. For reasons such as the elasticity modulus of the polyester film in two directions, a biaxially oriented polyester film is preferred.

The intrinsic viscosity of the polyester film is preferably 0.50 dl/g to 0.70 dl/g, more preferably 0.52 dl/g to 0.62 dl/g. When the intrinsic viscosity is 0.50 dl/g or more, it is preferable that a large number of fractures do not occur in the extending step. Conversely, when it is 0.70 dl/g or less, the cutting property when it is cut to a predetermined product width is good, and dimensional defects do not occur, so it is preferable. In addition, it is preferable that the raw material particles are sufficiently vacuum-dried. In addition, in this specification, when it describes as "polyester film", it means the polyester film which has (laminated) the surface layer A. Moreover, in this invention, the polyester film has the surface layer A which does not contain an inorganic particle substantially, and has the said release layer on the surface layer A. In addition, if mentioned in the specification, the polyester film which further has (laminated) the surface layer B may be abbreviated as "polyester film".

In the present invention, the method for producing the polyester film is not particularly limited, and conventionally generally employed methods can be used. For example, the polyester is melted with an extruder, extruded into a film form, cooled in a rotating cooling drum to obtain an unstretched film, and obtained by stretching the unstretched film. Biaxial stretching is preferable in view of mechanical properties and the like. The biaxially stretched film can be obtained by a method of progressively biaxially stretching a uniaxially stretched film in the longitudinal direction or the transverse direction in the transverse direction or the longitudinal direction, or a method of simultaneously biaxially stretching an unstretched film in the longitudinal direction and the transverse direction. .

In the present invention, the stretching temperature at the time of stretching the polyester film is preferably equal to or higher than the secondary transition point (Tg) of the polyester. It is better to extend 1 to 8 times, especially 2 to 6 times, in the individual directions of the longitudinal and transverse directions.

The thickness of the above polyester film is preferably 12 μm to 50 μm, more preferably 15 μm to 38 μm, and still more preferably 19 μm to 33 μm. As long as the thickness of the film is 12 μm or more, it is preferable that there is no possibility of thermal deformation during the production of the film, the processing step of the release layer, and the molding of the ceramic green body. On the other hand, as long as the thickness of the film is 50 μm or less, the amount of the film discarded after use does not increase extremely, and it is preferable to reduce the environmental load.

The above-mentioned polyester film may be a single layer, or a multi-layer of two or more layers may be used. The polyester film has a surface layer A substantially free of inorganic particles. For example, it may be a single layer of the surface layer A, or may be a multilayer structure having the surface layer A and other layers (for example, the surface layer B described later). In the case of a laminated polyester film composed of two or more layers, it is preferable to have a surface layer B that can contain particles and the like on the opposite side of the surface layer A that does not substantially contain inorganic particles. In the laminated structure, if the layer on the side where the release layer is applied is regarded as the surface layer A, the layer on the opposite side is regarded as the surface layer B, and the core layer other than the surface layer A and the surface layer B is regarded as the layer C, then As for the layer structure in the thickness direction, a laminated structure such as release layer/A/B or release layer/A/C/B can be exemplified. Of course, the layer C may also be composed of a plurality of layers. In addition, the surface layer B may not contain particles. In this case, it is preferable to provide a coating layer containing particles and a binder on the surface layer B in order to impart sliding properties when the film is wound into a roll shape.

In the polyester film of the present invention, the surface layer A located on the surface of the coated release layer does not substantially contain inorganic particles. In the present invention, since the surface layer A does not substantially contain inorganic particles, the average surface roughness of the following regions can be exhibited. In the present invention, the average surface roughness (Sa) of the region of the surface layer A is the average surface roughness (Sa) of the region on the surface where the release layer is arranged, and the average surface roughness (Sa) of the region on the surface where the release layer is arranged ( Sa) is 7 nm or less. If Sa is 7 nm or less, even the release layer laminated on the surface layer A can exhibit high smoothness, and pinholes and the like are less likely to occur during molding of the ultra-thin ceramic green body laminated on the release layer. Furthermore, when the release layer is formed, it is possible to suppress the aggregation of the release layer components on the protrusions on the surface layer A, and to prevent the deterioration of the smoothness of the surface of the release layer.

The average surface roughness (Sa) of the region of the surface layer A is preferably as small as possible, and it does not matter if it is 0.1 nm or more. In one aspect, the average surface roughness (Sa) of the area of the 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 less, or 0.5 nm or more and 4 nm or less. By setting it within such a range, the smoothness of the release layer can be improved, and pinholes and the like can be suppressed during molding of the laminated ultra-thin ceramic green body. Furthermore, when the release layer is formed, it is possible to suppress the aggregation of the release layer components on the protrusions on the surface layer A, and to prevent deterioration of the smoothness of the surface of the release layer.

In the present invention, "substantially free of inorganic particles" means that when an inorganic element is quantified by fluorescent X-ray analysis, the content is 50 ppm or less, preferably 10 ppm or less, and most preferably equal to or less than the detection limit. This is because even if inorganic particles are not actively added to the film, contaminants originating from external foreign matter, and contaminants adhering to the production line or equipment during the raw resin or film production steps may be mixed into the film. .

In the polyester film substrate of the present invention, the surface layer B may be provided on the opposite surface of the surface on which the release layer is arranged. The surface layer B preferably contains particles. By containing particles, it is excellent in the sliding property of the film and the easiness of removing air, and can have excellent transportability and winding property. In particular, it is preferable to contain silica particles and/or calcium carbonate particles. The amount of particles contained in the surface layer B is 1000 ppm to 15000 ppm in total. At this time, the average surface roughness (Sa) of the area of the film of the surface layer B is, for example, 1 nm or more and 40 nm or less. More preferably, it is 5 nm or more and 35 nm or less. When the total amount of silica particles and/or calcium carbonate particles is 1000 ppm or more and Sa is 1 nm or more, when the film is wound into a roll shape, the air can be uniformly dissipated, and the winding state and flatness can be good. . With this feature, for example, in the case of producing ultra-thin resin sheets (such as ceramic green bodies) with a thickness of 0.2 μm or more and 1.0 μm or less, the coiled ceramic green body can be prevented from wrinkling and misalignment, and can be transported. A release film with excellent properties, winding properties and storage properties. In addition, when the total amount of silica particles and/or calcium carbonate particles is 15,000 ppm or less, and Sa is 40 nm or less, the particles that also function as lubricants are less likely to agglomerate, and coarse protrusions (for example, those with a height of 1 μm or more) are not generated. Therefore, in the manufacture of ultra-thin resin sheets (such as ceramic green bodies), the occurrence of pinholes caused by winding, for example, can be suppressed, and a resin sheet with stable quality can be provided.

As the particles contained in the surface layer B, in addition to silica and/or calcium carbonate, inactive inorganic particles and/or heat-resistant organic particles can also be used. From the viewpoint of transparency and cost, it is better to use silica particles and/or calcium carbonate particles. Other usable inorganic particles include alumina-silica composite oxide particles, hydroxyapatite particles, and the like. Moreover, as heat-resistant organic particle|grains, crosslinked polyacrylic-type particle|grains, crosslinked polystyrene particle|grains, benzoguanamine-type particle|grains, etc. are mentioned. When using silica particles, porous colloidal silica is preferred. When calcium carbonate particles are used, from the viewpoint of preventing the particles from falling off, a light calcium carbonate surface-treated with a polyacrylic polymer compound is preferred.

The average particle diameter of the particles added to the surface layer B is preferably 0.1 μm or more and 2.0 μm or less, particularly preferably 0.5 μm or more and 1.0 μm or less. As long as the average particle diameter of the particles is 0.1 μm or more, the sliding property of the release film is good, so it is preferable. In addition, as long as the average particle diameter is 2.0 μm or less, deformation of the surface layer A can be suppressed, and thickness unevenness of the ceramic green body and occurrence of pinholes can be suppressed.

The said surface layer B may contain the particle|grains of 2 or more types of different materials. In addition, particles of the same type but different in average particle diameter may be contained. In addition, two or more kinds of different particles may have different average particle diameters within the above-mentioned range. By containing two different kinds of particles, the unevenness formed in the surface layer B can be suppressed to a high degree, and it is preferable that both slidability and smoothness can be achieved.

From the viewpoint of reducing pinholes, it is preferable that the surface layer A, which is the layer on the side where the release layer is provided, does not use recycled raw materials or the like in order to prevent particles or impurities from being mixed in.

The thickness ratio of the layer on the side where the release layer is provided, that is, the surface layer A is preferably 20% or more and 50% or less of the total layer thickness of the base film. As long as it is 20% or more, it is not easy to be affected by the particles contained in the surface layer B and the like from the inside of the film, and the average surface roughness Sa of the region can satisfy the above range, so it is preferable. If it is less than 50% of the total layer thickness of the base film, the use ratio of recycled raw materials in the surface layer B and the intermediate layer C obtained by co-extrusion can be increased, and the environmental load is reduced, so it is preferable.

In addition, from the viewpoint of economy, 50% to 90% by mass of film scraps or recycled raw materials of PET bottles can be used in the layers other than the above-mentioned surface layer A (surface layer B or the above-mentioned intermediate layer C). This is the case, and it is preferable that the type and amount of the lubricant contained in the surface layer B, the particle size, and the area average surface roughness (Sa) satisfy the above-mentioned ranges.

In addition, based on the consideration of the improvement of the adhesion of the release layer, etc. or antistatic, etc. of the subsequent coating, the surface of the surface layer A and/or the surface layer B can be stretched before the film-forming step or uniaxially stretched After the coating is provided, corona treatment and the like can also be applied. When a coating is provided on the surface layer A, the coating is preferably substantially free of particles.

(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 hardened layer of the release layer-forming composition, the release layer and the release layer-forming composition at least contain cationic hardening polydimethylsiloxane (a), and the region of the release layer The surface roughness (Sa) was 2 nm or less, and the number of protrusions with a height of 10 nm or more existing on the surface of the release layer was 200 pieces/mm ² or less. Due to this characteristic of the release layer, pinholes can be suppressed in ultra-thin film resin sheets requiring high smoothness (eg, ceramic green bodies), and a resin sheet with a uniform film thickness can be formed. More specifically, the release layer of the present invention can suppress the poor hardening caused by oxygen barrier, and can exhibit high cross-linking of the release layer. The present invention exerting such an effect can improve the solvent resistance of the surface of the release layer, for example. By improving the solvent resistance of the surface of the release layer, the release layer can be prevented from being eroded by the organic solvent used in the molding of the ceramic green body and the printing of the internal electrodes, and high peelability can be obtained. In addition, according to the present invention, it is not necessary to use high heat of 130° C. or higher in order to promote the hardening reaction. Therefore, the flatness of the release film can be suppressed from being damaged by heat during processing. In addition, it can prevent foreign matter from entering the release film for resin sheet molding, suppress the occurrence of scratches in the release layer, and suppress the occurrence of sheet damage caused by transfer of foreign matter and scratches to the object to be released such as a ceramic green body.

The average surface roughness (Sa) of the area of the release layer is 2 nm or less. In addition, the number of protrusions with a height of 10 nm or more existing on the surface of the release layer was 200/mm ² or less. The surface of the release layer of the release film is to avoid defects in the ceramic sheet coated and molded on the release layer, so the average surface roughness (Sa) of the above-mentioned area and the number of protrusions above 10 nm meet the predetermined conditions. As long as the area surface roughness (Sa) is 2 nm or less and the number of protrusions with a height of 10 nm or more is 200/mm ² or less, defects such as pinholes will not occur in the ceramic sheet during molding, and the yield is good, so it is preferable. More preferably, the region surface roughness (Sa) is 1.7 nm or less, for example, 1.6 nm or less, or 1.5 nm or less. In one aspect, the area surface roughness (Sa) is 1.3 nm or less. In addition, the area surface roughness (Sa) 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 having a height of 10 nm or more is 180/mm ² or less, for example, 170/mm ² or less, or 160/mm ² or less. In one aspect, the number of protrusions with a height of 10 nm or more may be 120 pieces/mm ² or less, or 100 pieces/mm ² or less. In addition, the number of protrusions having a height of 10 nm or more may be 1/mm ² or more, for example, 10/mm ² or more. By making the number of protrusions with a height of 10 nm or more in the above-mentioned range, defects such as pinholes are not generated in the ceramic sheet, and excellent mold release properties can be obtained in a balanced manner. More preferably, the area surface roughness (Sa) is 1.0 nm or less, and the number of protrusions with a height of 10 nm or more is 100 pieces/mm ² or less. The release layer having the area average surface roughness (Sa) and the number of protrusions related to the present invention can exhibit extremely excellent smoothness.

In one aspect, the maximum protrusion height (Sp) of the release layer is 20 nm or less. If the maximum protrusion height is in this range, the defects of the ceramic sheet can be further suppressed. More preferably, the maximum protrusion height (Sp) is 15 nm or less, more preferably 10 nm or less. In one aspect, the sum of the number of protrusions with a height of 5 nm or more to less than 10 nm and the number of protrusions with a height of 10 nm or more existing on the surface of the release layer is 1500 pieces/mm ² or less. If the total number of protrusions with a height of 5 nm or more to less than 10 nm and the number of protrusions with a height of 10 nm or more existing on the release layer is less than 1500/mm ² A release layer is therefore preferred. More preferably, the sum of the number of protrusions with a height of 5 nm or more and less than 10 nm and the number of protrusions with a height of 10 nm or more is 1000 pieces/mm ² or less, for example, 500 pieces/mm ² or less is more preferable.

The release layer related to the release film for resin sheet molding of the present invention is a layer in which the release layer-forming composition is hardened, and the release layer-forming composition contains at least cation-curable polydimethylsiloxane (a). The cation-curable polydimethylsiloxane (a) undergoes a cross-linking reaction due to a cation-curing reaction, and thus does not cause poor curing due to oxygen inhibition, and becomes a release layer excellent in solvent resistance. Therefore, there is no need to worry about the corrosion of the release layer caused by the organic solvent used in the molding of the ceramic green body, the printing of the internal electrodes, etc., and a release layer with excellent releasability can be obtained.

Furthermore, the present inventors have found that in the release layer containing the cationic hardening type polydimethylsiloxane (a), a high amount of the cationic hardening type polydimethylsiloxane (a) is essential for achieving a smooth release layer. important for the type layer. Cationic hardening type polydimethylsiloxane (a) in the release layer contains 90 mg/m ² or less, for example, 60 mg/m ² or less, preferably 50 mg/m ² or less, preferably 40 mg/m ² or less More preferably, it is more preferable to contain 30 mg/m ² or less. In addition, the cation-curable polydimethylsiloxane (a) may be, for example, 20 mg/m ² or less. If the content of the cation-hardening polydimethylsiloxane (a) in the release layer is less than 50 mg/m ² , the polydimethylsiloxane ( a) When agglomeration occurs, there is no need to worry about the occurrence of many protrusions outside the scope of the present invention, and the effect of the present invention can be exerted. In one aspect, components other than the cation-curable polydimethylsiloxane (a) may be contained in the release layer and the release layer-forming composition. Even in this case, although it should not be judged based on a specific theory, in the present invention, polydimethylsiloxane (a) may segregate on the surface of the release layer when the release layer is processed, if the content is below 50 mg/m ² It is not easy to agglomerate, and a release layer with high smoothness can be formed. The less the content of the polydimethylsiloxane (a) related to the present invention, the less likely it is to agglomerate. As long as the content of the polydimethylsiloxane (a) in the release layer is more than 0.1 mg/m ² , the uniformity of the release layer can be maintained, and the coating can be obtained. A release layer with excellent appearance and high smoothness. Moreover, as long as it is 0.1 mg/m ² or more, it is also excellent in peelability, so it is preferable. For example, the content of polydimethylsiloxane (a) may be 0.5 mg/m ² or more. In the present invention, the release layer-forming composition contains a cation-curable polydimethylsiloxane (a). Moreover, the compound (hardened|cured material) derived from the cation hardening-type polydimethylsiloxane (a) exists in the release layer hardened|cured by the release layer forming composition. In this specification, the compound derived from polydimethylsiloxane (a) which exists in a release layer may be abbreviated as cation hardening type polydimethylsiloxane (a).

In the present invention, the cation-curable polydimethylsiloxane (a) means a polydimethylsiloxane having a cation-curable functional group. The cation-hardenable functional group includes a reactive functional group exhibiting cation-hardenability, and specific examples thereof include vinyl ether group, oxetanyl group, epoxy group, and alicyclic epoxy group. From the viewpoint of reactivity, it is preferable to have at least one functional group selected from the group consisting of oxetanyl group, epoxy group, and alicyclic epoxy group, and alicyclic epoxy group is the most preferable. By having such a functional group, a cross-linked structure can be formed by a cationic curing reaction, and it is preferable to be a release layer having excellent solvent resistance and excellent releasability.

The number of the cationic hardening functional group which the cation hardening type polydimethylsiloxane (a) has should just be 1 or more. For example, by having two or more cationic curable functional groups, the cationic curing reaction is more likely to proceed, and it is preferable to form a release layer with a high crosslinking density. The introduction position of the cationic sclerosing functional group is not particularly limited, and generally it can be located at the side lock or terminal of the polydimethylsiloxane. The structure of the polydimethylsiloxane may be a linear structure or a branched structure, and even if it has a functional group other than a cationic sclerosing functional group, it can be used without problems.

As the cation-curable polydimethylsiloxane (a), a commercially available one can be suitably used. Examples include Silicon Conris (registered trademark) UV POLY200, UV POLY201, UV POLY215, UV RCA200, UV RCA251 manufactured by Arakawa Chemical Industry Co., Ltd., X-62-7622, X-62-7629 manufactured by Shin-Etsu Chemical Industry Co., Ltd., 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, UV9440E, UV9430 manufactured by Momentive Performance Materials, etc.

The weight average molecular weight of the cation-hardening polydimethylsiloxane (a) is preferably 1,000 to 500,000, more preferably 5,000 to 100,000. When the weight average molecular weight is 1,000 or more, the cationic curing reaction is easy to proceed and the peelability is excellent, so it is preferable. If it is 500,000 or less, the viscosity will not become too high, and it is preferable to be a release layer having excellent coatability and high planarity.

The release layer forming composition of the present invention may contain other resins in addition to the cation-curable polydimethylsiloxane (a). 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 the base film substantially free of inorganic particles, even if the film thickness of the release layer is thin, it can be a release layer with extremely high smoothness. In addition, since the film thickness of the release layer is thin, the hardening reaction is easy to proceed, the processing can be performed at a higher speed, and the release layer can be obtained economically.

If the film thickness is further reduced, there is no need to worry about the entrainment of extremely minute foreign matter, etc., existing in the release process, etc., into the release layer. Therefore, there is no possibility that protrusions originating from foreign substances are generated on the surface of the release layer, and a release layer having a smooth surface as described above can be obtained.

In the case of a hardened release layer of a composition mainly composed of cation-curable polydimethylsiloxane (a), the film thickness of the release layer is preferably 0.001 μm or more and less than 0.050 μm. It is preferable that it is 0.001 micrometer or more because the mold release property is excellent. If the thickness is less than 0.050 μm, the aggregation of the release layer forming composition can be prevented and a smooth release layer can be obtained. In addition, in the present invention, when the cation-curable polydimethylsiloxane (a) is used as the main component, the composition contains cation-curable polydimethylsiloxane with respect to 100 parts by mass of the resin solid content of the release layer. The oxane (a) is 50 parts by mass or more, for example, more than 50 parts by mass, preferably 70 parts by mass or more, for example, 80 parts by mass or more, and in one embodiment, 90 parts by mass or more. Moreover, it may be the state which contains cation hardening-type polydimethylsiloxane (a) substantially in the whole resin solid matter of a release layer.

The release layer forming composition of the present invention may contain a cation-curable resin (b) in addition to the cation-curable polydimethylsiloxane (a). In this case, (b) is a resin different from (a), and resin (b) is a resin without a polydimethylsiloxane structure. Specifically, it can be roughly classified into two types: a cation-curable compound (b-1) having no polysiloxane skeleton and a cyclosiloxane compound (b-2) having an alicyclic epoxy group.

In one aspect, the release layer-forming composition contains, in addition to the cationic hardening polydimethylsiloxane (a), a cationic hardening compound (b-1) without a polysiloxane skeleton. As an example of the cationic curable compound (b-1) which does not have a polysiloxane skeleton, the polymer and monomer which have two or more cationic curable functional groups in a molecule|numerator and do not have a polysiloxane skeleton are mentioned. Among them, resins having two or more epoxy groups or alicyclic epoxy groups are preferable, and resins having two or more alicyclic epoxy groups are more preferable. For example, the number of alicyclic epoxy groups may be 6 or less. By having two or more alicyclic epoxy groups, a crosslinking reaction can proceed by a cation hardening reaction, and it becomes a release layer excellent in solvent resistance. In addition, it also undergoes a cross-linking reaction with the polydimethylsiloxane (a) contained in the release layer at the same time, so that the peelability is excellent, and the movement of the polydimethylsiloxane (a) to the ceramic green body is suppressed, so better.

In one aspect, the release layer-forming composition contains both the cationic curable resin (b-1) without a polysiloxane skeleton and the polydimethylsiloxane (a), so that a release layer with high smoothness can be realized. type layer. By forming the release layer containing the compound (b-1), it is possible to fill in the fine unevenness, extremely minute foreign matter, oligomer-derived protrusions, etc. existing in the base film, and it becomes an ultra-smooth release layer. In addition, it becomes a release layer with high smoothness due to the curing reaction by ultraviolet rays. Although not limited to a specific theory, it is presumed that the cationic curable resin (b-1) having no polysiloxane skeleton is uniformly made in the drying step of the release layer forming composition during release layer processing. Even with polydimethylsiloxane (a), it is hardened after improving the flatness, and a release layer with high smoothness can be obtained. In addition, in the present invention, the polydimethylsiloxane (a) contained at the same time is segregated on the surface of the release layer in the drying step, so that a release layer excellent in releasability can be obtained.

The cationic hardening compound (b-1) having no polysiloxane skeleton is preferably a low molecular weight monomer. Specifically, the number average molecular weight is preferably more than 200 and less than 5,000, more preferably more than 200 and less than 2,500, and more preferably more than 200 and less than 1,000. If the number average molecular weight is 200 or more, the boiling point will not be lowered, and the cationic curable compound (b-1) is preferred because there is no risk of volatilization in the drying step of the release layer forming composition during release layer processing. If it is less than 5000, the crosslinking density of the release layer is high and the solvent resistance is excellent, so it is better. Moreover, since it exists in the liquid state with fluidity in a drying process, it is excellent in uniformity, and it is preferable that it becomes an ultra-smooth release layer.

A commercially available one can be suitably used for the cationic curable compound (b-1) which does not have a polysiloxane skeleton. Examples of compounds having an alicyclic epoxy group include Celloxide 2021P, Celloxide 2081, Epolead GT401, EHPE3150 manufactured by Daicel, HiREM-1 manufactured by Shikoku Chemicals, THI-DE and DE- 102, DE-103, etc. Examples of resins having epoxy groups include EPICLON (registered trademark) 830, 840, 850, 1051-75M, N-665, N-670, N-690, N-673-80M, N- 690-75M, Denacol (registered trademark) EX-611, EX-313, EX-321, etc. manufactured by Nagasechemtex.

With respect to the total of 100 parts by mass of the cationic hardening polydimethylsiloxane (a) and the cationic hardening compound (b-1) in the release layer, the cationic hardening compound (b-1) without a polysiloxane skeleton ) content is preferably 80 mass % or more, more preferably 85 mass % or more, and even more preferably 90 mass % or more. When the content of the cationic curable compound (b-1) is 80% by mass or more and becomes the main component in the release layer, it is preferable to be a release layer with high crosslinking density and excellent releasability. In addition, the content of the cationic hardening polydimethylsiloxane (a) contained in the release layer can be reduced, and the composition derived from the polydimethylsiloxane (a) in the drying step can be suppressed from agglomerating in the release layer. The surface of the layer is preferred because there is no fear of deterioration of planarity. Although the content of the cationic hardening compound (b-1) is high, the release layer with excellent smoothness can be obtained. However, in order to contain the cationic hardening polydimethylsiloxane (a) to ensure releasability, the cationic hardening type The compound (b-1) is preferably 99.9 mass % or less. In this invention, the compound (hardened|cured material) derived from the cation hardening type compound (b-1) which does not have a polysiloxane skeleton exists in the release layer hardened|cured by the release layer forming composition. In this specification, the compound derived from (b-1) existing in the release layer is sometimes simply referred to as a cation-hardening compound (b-1) having no polysiloxane skeleton.

When the release layer-forming composition contains the cationic hardening polydimethylsiloxane (a) and the cationic hardening compound (b-1), since the crosslinking density of the release layer is high and the solvent resistance is excellent, it becomes A release layer with excellent peeling force is preferred. In addition, if the cationic hardening compound (b-1) is contained, it is preferable because the film thickness of the release layer can be increased while controlling the content of the cationic hardening polydimethylsiloxane (a) within a predetermined range. . By increasing the film thickness of the release layer, it is possible to fill in the scars and extremely minute irregularities existing in the base film, and it is preferable to obtain a smooth release layer as described above.

When the release layer forming composition contains the cationic hardening polydimethylsiloxane (a) and the cationic hardening compound (b-1), the film thickness of the release layer is preferably 0.05 μm or more and 1.0 μm or less. , more preferably from 0.1 μm or more to 0.5 μm or less. If it is 0.05 μm or more, a smooth release layer is obtained, so it is preferable. If it is 1.0 μm or less, it is preferable that a release film excellent in flatness can be obtained without warping.

In one aspect, the release layer-forming composition may further include a cyclosiloxane compound (b-2) having an alicyclic epoxy group. Examples of the cyclosiloxane compound (b-2) having an alicyclic epoxy group include those represented by the following structural formula (chemical formula 1) (in chemical formula 1, R ² is a carbon number from 1 to 1). 4 alkyl). Moreover, it is preferable that the cation hardening type compound (b-2) which has a cyclic siloxane skeleton has at least 2 or more alicyclic epoxy groups. When the number of alicyclic epoxy groups is two or more, a cationic hardening reaction proceeds and a release layer with a high crosslinking density is obtained.

[Chemical formula 1]

By using the cyclosiloxane compound (b-2) having an alicyclic epoxy group, for the same reason as when using the aforementioned cation-curable compound (b-1), an ultra-smooth release layer can be obtained So better. That is, it can be embedded in the fine unevenness|corrugation, the extremely fine foreign matter, the protrusion derived from an oligomer, etc. which exist in a base film. In addition, since the curing reaction is carried out by ultraviolet rays, the compound (b-2) and the polydimethylsiloxane (a) can be made uniform in the drying step of the release layer forming composition during the release layer processing. , while the flatness is improved and then hardened to obtain an ultra-smooth release layer. Furthermore, in the present invention, since the polydimethylsiloxane (a) contained at the same time is segregated on the surface of the release layer in the drying step, a release layer excellent in releasability can be obtained.

The cyclosiloxane compound (b-2) having an alicyclic epoxy group has good compatibility with the cationic hardening type polydimethylsiloxane (a), so it is properly mixed in the release layer , undergo cross-linking reaction with each other. Therefore, it is excellent in solvent resistance, and it is preferable that it becomes a release layer which shows excellent releasability. In addition, the cyclosiloxane compound (b-2) has a rigid molecular skeleton because it has a cyclosiloxane structure, and it is preferable that the film hardness during curing is high. By increasing the film hardness, when peeling a resin sheet (for example, a green ceramic body), the release layer is less likely to be deformed, and good peelability can be exhibited. In addition, the release layer becomes less prone to scratches, and there is no need to worry that the scratches of the release layer are transferred to the resin sheet (eg, ceramic green body) and cause defects, so it is better.

If the composition for forming the release layer contains the cyclic siloxane compound (b-2), it is preferable because the adhesion of the release layer to the base film can be improved. If the adhesiveness of the release layer is improved, the occurrence of scratches in the conveying step can be suppressed, and it is better not to worry about the transfer of the release layer when the resin sheet is peeled off.

In one aspect, the cyclosiloxane compound (b-2) has two or more alicyclic epoxy groups in the molecule. If it has two or more alicyclic epoxy groups in a molecule|numerator, a crosslinking reaction can progress by a cation hardening reaction, and it becomes a release layer excellent in solvent resistance. In addition, it also undergoes a cross-linking reaction with the polydimethylsiloxane (a) contained in the release layer at the same time, so it is excellent in peelability, and can prevent the polydimethylsiloxane (a) from moving to the ceramic green body. better. For example, the cyclosiloxane compound (b-2) has six or less alicyclic epoxy groups in the molecule.

As the cyclosiloxane compound (b-2) having an alicyclic epoxy group, a commercially available one can be used. For example, X-40-2670 and X-40-2678 manufactured by Shin-Etsu Chemical Co., Ltd., etc. are mentioned.

With respect to a total of 100 parts by mass of the cation-curable polydimethylsiloxane (a) and the cyclic siloxane compound (b-2) in the release layer, the cyclic siloxane compound (b-2) The content is preferably at least 80% by mass, more preferably at least 85% by mass, and even more preferably at least 90% by mass. When the content of the cyclic siloxane compound (b-2) is 80 mass % or more and becomes the main component in the release layer, it is preferable to be a release layer with high crosslinking density and excellent releasability. In addition, the content of the cationic hardening type polydimethylsiloxane (a) contained in the release layer can be reduced, and in the present invention, the cationic hardening type polydimethylsiloxane (a) in the drying step can be suppressed It is better to condense on the surface of the release layer without worrying about the deterioration of the flatness. The higher the content of the cyclic siloxane compound (b-2), the better the smoothness of the release layer will be. The siloxane compound (b-2) is preferably 99.9 mass % or less. In the present invention, a compound (hardened product) derived from the cyclic siloxane compound (b-2) is present in the hardened release layer of the release layer forming composition. In this specification, the compound derived from the cyclosiloxane compound (b-2) existing in the release layer may be simply described as the cyclosiloxane compound (b-2).

When the release layer forming composition contains cation hardening polydimethylsiloxane (a) and cyclosiloxane compound (b-2), the film thickness of the release layer is 0.05 μm or more and 1.0 μm or more. It is preferably not more than μm, more preferably not less than 0.1 μm and not more than 0.5 μm. It is preferable that it is 0.05 micrometer or more, since it becomes a smooth release layer. If it is 1.0 μm or less, warpage can be avoided and a release film excellent in flatness can be obtained, so it is preferable.

In one aspect, the release layer may contain both the cation-curable resin (b-1) and the cyclosiloxane compound (b-2), these cation-curable resin (b-1) and the cyclosiloxane The total amount of the compound (b-2) relative to the cation-hardening polydimethylsiloxane (a), the cation-hardening compound (b-1) and the cyclic siloxane compound (b-2) in the release layer ) can be 80 mass % or more and 99.9 mass % or less in total of 100 mass parts.

In the present invention, it is necessary to carry out a cationic hardening reaction in order to form a release layer. Therefore, it is preferable that the release layer-forming composition contains the acid generator (c). In addition, a compound derived from the acid generator (c) may be present in the release layer. Here, the compound derived from the acid generator (c) existing in the release layer may be simply referred to as the acid generator (c). The acid generator is not particularly limited. General acid generators can be used. However, by using a photoacid generator that generates acid when irradiated with ultraviolet rays, heat during processing can be suppressed and a release layer with excellent flatness can be used. .

From the viewpoint of reactivity, it is suitable to use a salt of an onium ion and a non-nucleophilic anion as the photoacid generator. In addition, organometallic complexes represented by iron arene complexes, carbocation salts represented by titanium, and phenols substituted by onion derivatives or electron withdrawing groups, such as pentafluorophenol, can also be used .

In the case of using a salt of the aforementioned onium ion and a non-nucleophilic anion as the photoacid generator, as the onium ion, for example, iodonium, perionium, and ammonium can be used. As the organic group of the onium ion, a triaryl group, a diaryl group (monoalkyl group), a monoaryl group (dialkyl group), and a trialkyl group can be used, benzophenone and 9-fluorene can also be introduced, and other organic groups can be used. base. As the non-nucleophilic anion, hexafluorophosphate, hexafluoroantimonate, hexafluoroborate, and tetrakis(pentafluorophenyl)borate are suitably used. In addition, tetrakis(pentafluorophenyl) gallium ions, anions obtained by substituting several fluorine anions for perfluoroalkyl groups or organic groups, and other anion components can also be used.

The addition amount of the photoacid generator is relative to the cation-hardening polydimethylsiloxane (a) and the cation-hardening compound (b-1) and/or the cyclic siloxane compound (b-) in the release layer 2) 100 mass parts in total is 0.1 mass % - 10 mass %, More preferably, it is 0.5 mass % - 8 mass %. More preferably, it is 1 mass % to 5 mass %. If it is 0.1 mass % or more, there is no fear that the amount of acid generated will become insufficient and the curing will be insufficient, so it is preferable. In addition, if it is 10 mass % or less, the amount of the acid to be generated becomes an appropriate amount, and the amount of movement of the acid to the ceramic green body to be molded can be suppressed, so it is preferable.

In this specification, the so-called cation-hardening polydimethylsiloxane (a) in the release layer, the cation-hardening compound (b-1) and/or the cyclic siloxane compound (b-2) is the sum of 100 parts by mass means the total value of the solid content of the cation-curable polydimethylsiloxane (a) and the solid content of the cation-curable resin (b). In addition, in a state in which the release layer does not contain the cationically curable resin (b), the weight of the cationically curable polydimethylsiloxane (a) corresponds to 100 parts by mass of resin solids in the release layer.

In one aspect, the release layer-forming composition includes an organic solvent having an SP value (δ) of 14 or more and 17 or less, and the release layer-forming composition is the aforementioned organic solvent having an SP value (δ) of 14 or more and 17 or less. The solvent is contained in an amount of 10% by mass or more with respect to 100 parts by mass of the total weight of the release layer forming composition. Organic solvents having SP values (δ) of 14 to 17 exhibit excellent solubility for cation-hardening polydimethylsiloxane (a). Therefore, in the drying step after the coating step, even if the organic solvent is dried to increase the concentration of the cationic hardening type polydimethylsiloxane (a) in the release layer forming composition, the uniformly dissolved state can be maintained. It is well leveled without agglomeration, and a smooth release layer can be obtained. In addition, as long as the content is 10% by mass or more, the cation-curable polydimethylsiloxane (a) can remain in a dissolved state for a long time during drying, so there is no fear of deterioration of smoothness due to aggregation during drying. good. The details of the organic solvent whose SP value (δ) is 14 or more and 17 or less will be described later.

In the present invention, as long as the effects of the present invention are not inhibited, additives such as adhesion promoters and antistatic agents may be added to the release layer. In addition, in order to improve the adhesion to the substrate, it is also preferable to apply anchor coating, corona treatment, plasma treatment, atmospheric pressure plasma treatment, etc. on the surface of the polyester film before disposing the release coating layer.

The peeling force when peeling off the ceramic green body using the release film obtained by the present invention is preferably 0.01 mN/mm or more and 2.0 mN/mm or less. More preferably, it is 0.05 mN/mm or more and 1.0 mN/mm or less. If the peeling force is 0.01 mN/mm or more, there is no concern that the ceramic green body will bulge during transportation, so it is preferable. If the peeling force is 2.0 mN/mm or less, there is no fear of damage to the ceramic green body during peeling.

Since the release film obtained by the present invention uses a highly planarized base film, even if the thickness of the release layer is 1.0 μm or less, or even 0.5 μm or less, or even 0.3 μm or less, the release layer can still be made. Surface smoothing. Therefore, the amount of solvent and resin to be used can be reduced, which is good for the environment, and a release film for ultra-thin ceramic green body molding can be produced inexpensively.

(Manufacturing method of release film) In another embodiment of the present invention, there is provided a method for producing a release film for resin sheet molding, which includes the following steps. The coating step is to coat the release layer forming composition on the surface layer A of the polyester film with the surface layer A, the surface layer A is a layer substantially free of inorganic particles, and the release layer forming composition contains cationic hardening Type polydimethylsiloxane (a); the drying step is to heat and dry the polyester film coated with the release layer forming composition, and the heat drying has a first drying step and a subsequent second drying step, The drying temperature T1 in the first drying step is higher than the drying temperature T2 in the second drying step; and, in the photohardening step, active energy rays are irradiated after the drying step to harden the release layer forming composition.

According to the production method of the present invention, by enhancing the first drying conditions (intensive drying), agglomeration of the resin constituting the release layer can be prevented, and a release layer having 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 having high smoothness can be obtained. As described above, in the present invention, the first drying step has predetermined conditions, and in one aspect, a release layer having high smoothness can be obtained by using a specific solvent.

The manufacturing method of the release film of the present invention includes in sequence: a coating step of coating the release layer-forming composition containing at least cation-curable polydimethylsiloxane (a) on the polyester film that does not substantially contain On the surface layer A of the inorganic particles; in the drying step, after coating, the film is heated and dried using, for example, a drying oven; In particular, it is preferable to employ a method of sequentially performing a coating step, a drying step, and a photohardening step.

According to the manufacturing method of the present invention, it has been found that a release layer having high smoothness can be realized by improving the manufacturing conditions of the coating step. Specifically, since the composition for forming the release layer contains an organic solvent with an SP value (δ) of 14 to 17, the aggregation of the cation-curable polydimethylsiloxane (a) can be suppressed, and an excellent release layer can be obtained. type layer. SP value (δ) can be used to predict the solubility of a substance, and organic solvents with SP value (δ) of 14 to 17 exhibit excellent solubility for cation-hardening polydimethylsiloxane (a). Therefore, in the drying step after the coating step, even if the organic solvent is dried to increase the concentration of the cationic hardening type polydimethylsiloxane (a) in the release layer forming composition, the uniformly dissolved state can be maintained. , it is well leveled without agglomeration, and a smooth release layer can be obtained.

The content of the organic solvent with SP value (δ) of 14 to 17 contained in the release layer forming composition is preferably 10% by mass or more, more preferably 15% by mass or more, relative to 100 parts by mass of the release layer forming composition. good. If it is 10 mass % or more, since the cation-curable polydimethylsiloxane (a) can be kept in a dissolved state for a long time during drying, there is no fear of deterioration of smoothness due to aggregation during drying. For example, the content of the organic solvent having an SP value (δ) of 14 to 17 is 80 mass % or less, for example, 65 mass % or less and less than 50 mass % with respect to 100 mass parts of the release layer forming composition.

The SP value (δ) in this specification adopts the Hide Brown solubility parameter. The Hide-Brown solubility parameter can be experimentally calculated from the Hansen Solubility Parameters (HSP value) in the form of Equation 1. SP value (δ)=((δ _d ) ² +(δ _p ) ² +(δ _h ) ² ) ^1/2・・・・・(Formula 1) Here (δ _D ) is the dispersing force term, and (δ _P ) is the polar term, (δ _H ) is the hydrogen bond term, and the way of thinking about decomposing the Hide-Brown solubility parameter into 3 components is the Hansen solubility parameter. In addition, it can also be calculated by using HSPiP (Hansen Solubility Parameters in Practice) of computer software, etc. The values described in this manual use the HSP values recorded in the database in HSPiP ver4.0. value.

Examples of organic solvents having SP values (δ) of 14 to 17 include n-hexane (δ: 14.9), n-heptane (δ: 15.3), n-octane (δ: 15.5), and isopropyl ether (δ: 15.8) , 1,1-diethoxyethane (δ: 15.9), methylcyclohexane (δ: 16.0), cycloheptane (δ: 16.5), cyclohexane (δ: 16.8) and the like.

The coating amount of the release layer forming composition is preferably 10 g/m ² or less, more preferably 8 g/m ² or less. When the coating amount is 10 g/m ² or less, for example, when coating is performed by gravure coating, turbulence is less likely to occur at the contact portion between the film and the gravure roll, and a release layer excellent in smoothness can be obtained.

In the present invention, it is preferable that two or more kinds of solvents are contained in the release layer-forming composition, and at least one of them is a solvent whose SP value (δ) is 14 to 17 as described above, and at least one is a solvent whose boiling point is 100. ℃ or higher is better. By adding a solvent with a boiling point of 100°C or higher, sudden boiling during drying can be prevented, the coating film can be made uniform, and the smoothness of the coating film surface after drying can be improved. The addition amount of the solvent is preferably about 10% by mass to 70% by mass with respect to the entire 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, n-butanol, etc. .

In the present invention, the coating liquid of the release layer forming composition is preferably filtered before coating. There is no particular limitation on the filtration method, and a known method can be used, but a surface type, depth type, or adsorption type cartridge filter is preferably used. By using the cassette filter, it can be used when the coating liquid is continuously fed from the tank to the coating section, and filtration can be performed with high productivity and high efficiency. The filtration precision of the filter should preferably be able to remove more than 99% of 1μm-sized objects, and more preferably, 0.5μm-sized objects can be filtered out more than 99%. By using the filter with the above-mentioned filtration precision, the foreign matter mixed in the coating liquid for forming the release layer can be removed, the foreign matter adhering to the release film of the present invention can be reduced, and the release layer with excellent smoothness can be obtained. So better.

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

As a method of applying the release layer-forming composition on the base film and drying it, well-known hot air drying, infrared heaters, etc. may be mentioned, and hot air drying with a high drying speed is preferable. It is preferable to perform drying in a drying furnace, and a known drying furnace can be used without particular limitation. As for the drying oven, it can be either roll support or floating. If it is roll support, the air volume during drying can be adjusted in a wider range, and the type of release layer can be adjusted. It is better to adjust the air volume, etc.

The drying step can be divided into two drying steps, a constant rate drying step (hereinafter referred to as a first drying step) and a reduced rate drying step (hereinafter referred to as a second drying step) at the initial stage of drying. The two steps are preferably continuous in the order of the first drying step and the second drying step. They can be separated by dividing the area in the drying furnace. The first (initial) drying step can be dried using the first drying furnace. The second (post-stage) drying step can be dried using a second drying furnace.

The inventors of the present invention found that in order to improve the smoothness of the release layer, it is important to make the drying temperature T1 in the first drying step higher than the drying temperature T2 in the second drying step. The temperature of the first drying furnace and the temperature of the second drying furnace are preferably controlled within the ranges described later. Manufacturing under such conditions can shorten the constant-rate drying time in the first drying step and lengthen the reduced-rate drying time in the second drying step, so that a release layer excellent in flatness can be obtained, which is preferable.

Furthermore, the present inventors found that it is important to increase the temperature in the first drying furnace 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. It is preferable to shorten the constant-rate drying time by increasing the temperature in the first drying furnace, so as to prevent aggregation of the cation-curable polydimethylsiloxane (a) contained in the release layer forming composition. The higher the temperature of the first drying furnace, the shorter the constant rate drying time is, so it is better. However, if the temperature is too high, the flatness of the film will be deteriorated due to heat, so it is better to be below 180°C. If it is 90 degreeC or more, since drying ability becomes sufficient, it is preferable.

The temperature in the second drying furnace is preferably 60°C or higher and 140°C or lower, more preferably 80°C or higher and 120°C or lower. In the second drying step, by prolonging the drying time, drying can be performed on the premise that the surface of the release layer before photohardening is not roughened, and the smoothness of the release layer can be improved, so it is preferable.

For example, the constant rate drying time in the first drying step is preferably shorter than the reduced rate drying time in the second drying step. Thereby, the flatness of the film can be prevented from deteriorating, and further, the surface of the release layer before photocuring can be dried without roughening the surface of the release layer, and the smoothness of the release layer can be improved.

The time from coating to entering the first drying oven is preferably from 0.1 seconds to less than 2.5 seconds, preferably from 0.1 seconds to less than 2.0 seconds, and the shorter the better. By shortening the time required to enter the first drying furnace, the drying time in the first drying step can be shortened, the aggregation of the cation-curable polydimethylsiloxane (a) can be suppressed, and a release layer with excellent smoothness can be obtained So better. The time required to enter the drying furnace can be calculated from the processing speed and the structure of the processing machine.

The production method of the present invention includes a photohardening step of irradiating an active energy ray after the drying step to harden the release layer-forming composition. In the photohardening step, the cationic hardening reaction of the post-drying release layer forming composition is performed by irradiating active energy rays. Known techniques such as ultraviolet rays and electron beams can be used for the active energy rays to be used, and ultraviolet rays are preferably used. The cumulative amount of light when using ultraviolet rays can be expressed as the product of the illuminance and the irradiation time. For example, it is preferably 10 mJ/cm ² to 500 mJ/cm ² . It is preferable that the release layer can be sufficiently hardened by setting it to be more than the aforementioned lower limit. By setting it below the said upper limit, the film can be prevented from being thermally damaged by the heat at the time of irradiation, and the smoothness of the surface of the release layer can be maintained, so it is preferable.

When irradiating active energy rays, it is preferable to hold the inner surface of the film by a backup roll. By setting the back roller, the distance from the active energy ray source can be kept constant and uniform irradiation can be achieved, so it is preferable. In addition, it is preferable to irradiate the active energy ray while cooling the surface of the backing roller to cool the film. By cooling, even in the case of irradiating active energy rays, the film is not easily damaged by heat, and the smoothness of the surface of the release layer can be maintained, so it is preferable.

In one aspect, the manufacturing method of the present invention provides a manufacturing method of a release film for manufacturing an inorganic compound-containing resin sheet.

(resin sheet) The resin sheet in the present invention is not particularly limited as long as it is a resin-containing sheet. In one aspect, the release film of the present invention is a release film for molding a resin sheet containing an inorganic compound. Examples of the inorganic compound include metal particles, metal oxides, minerals, and the like, and examples thereof include calcium carbonate, silica particles, alumina particles, barium titanate particles, and the like. Since the present invention has a release layer with high smoothness, even if the resin sheet contains such an inorganic compound, defects that may be caused by the inorganic compound (for example, breakage of the resin sheet, difficulty of the resin sheet from being freed) can be suppressed. The problem of peeling off the release layer). The resin component which forms a resin sheet can be suitably selected according to a use. In one aspect, the inorganic compound-containing resin sheet is a green ceramic body. For example, the ceramic green body may contain barium titanate as the inorganic compound. In addition, the resin component may contain, for example, a polyvinyl butyral-based resin. In one aspect, the thickness of the resin sheet is 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 producing a resin sheet containing these inorganic compounds. Moreover, the manufacturing method of the release film for resin sheet shaping|molding in this invention may also comprise the process of shaping|molding the resin sheet whose thickness is 0.2 micrometer or more and 1.0 micrometer or less.

(Ceramic green body and ceramic capacitor) Generally, a multilayer ceramic capacitor has a rectangular parallelepiped ceramic body. Inside the ceramic body, the first internal electrode and the second internal electrode are alternately provided along the thickness direction. The first internal electrode is exposed on the first end face of the ceramic element body. A first external electrode is provided on the first end surface. The first inner electrode is electrically connected to the first end surface and the first outer electrode. The second internal electrode is exposed on the second end face of the ceramic element body. A second external electrode is provided on the second end surface. The second inner electrode is electrically connected to the second end surface and the second outer electrode.

In one aspect, the release film of the present invention is a release film for green ceramic production, and is used for the production of such a multilayer ceramic capacitor. For example, a ceramic green body having a thickness of 0.2 μm or more and 1.0 μm or less can be formed by using the release film for ceramic green body manufacturing of the present invention to form a ceramic green body. More specifically, the ceramic green body is produced, for example, in the following manner. First, the release film of the present invention is used as a carrier film, and a ceramic slurry for constituting a ceramic element body is coated and dried. The thickness of the ceramic green body is gradually required to be extremely thin from 0.2 μm to 1.0 μm. On the coated and dried ceramic green body, a conductive layer for forming the first internal electrode or the second internal electrode is printed. The mother can be obtained by appropriately laminating and pressing a ceramic green body, a ceramic green body on which a conductive layer for forming the first internal electrode is printed, and a ceramic green body on which a conductive layer for forming the second internal electrode is printed. Laminated body. The mother laminate is divided into a plurality of pieces to produce a green ceramic element body. The ceramic element body is obtained by firing the green ceramic element body. After that, the multilayer ceramic capacitor can be completed by forming the first external electrode and the second external electrode. [Example]

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples at all. The characteristic values used in the present invention were evaluated by the following methods.

(release layer thickness) The cut release film was embedded in resin, and ultrathin sectioning was performed using a super microtome. Then, cross-sectional observation was performed using a JEM2100 transmission electron microscope manufactured by JEOL Ltd., and the film thickness of the release layer was measured from the observed TEM image. When the thickness is too thin, the cross-sectional observation cannot be accurately evaluated, and the measurement is performed using a reflection spectroscopic film thickness meter (manufactured by Otsuka Electronics Co., Ltd., FE-3000).

(Release layer weight) In this specification, the weight per thickness of 1 μm of the release layer is used as the weight value calculated by 1 g/m ² . For example, when the thickness of the release layer measured by the aforementioned method is 0.2 μm, the total weight of the release layer is 0.2 g/m ² . In addition, the weight of the cation-curable polydimethylsiloxane (a), the weight of the cation-curable resin (b), and the weight of the acid generator (c) contained in the release layer are determined from the composition of the release layer. The value calculated from the blending ratio of each component contained in the product and the total weight of the release layer. For example, when the thickness of the release layer is 0.2 μm and the weight ratio of the release layer of the cationic hardening polydimethylsiloxane (a) is 5 parts by mass, the cationic hardening polydimethylsiloxane contained in the release layer The weight of the siloxane (a) was 0.01 g/m ² . In addition, the weight ratio (mass %) of the release layer is calculated by taking the total of the component (a) and the component (b) as 100 parts by mass.

(coating amount of the release layer forming composition) The value calculated from the liquid consumption weight and the processing area of the release layer forming composition used in the coating step was used.

(Time from coating to first drying oven) The value calculated from the film travel distance and the processing speed from the coating section to the first drying furnace was used.

(region surface roughness Sa, maximum protrusion height Sp) The measurement was performed under the following conditions using a non-contact surface shape measurement system (VertScan R550H-M100). The average surface roughness (Sa) of the area is the average value of 5 measurements, and the maximum protrusion height (Sp) is the maximum value of the 5 measurements excluding the maximum value and the minimum value after 7 measurements. (measurement conditions) ・Measurement mode: WAVE mode ・Objective lens: 50x ・0.5×Tube lens ・Measurement area 187μm×139μm (analysis condition) ・Surface correction: 4 corrections ・Interpolation processing: full interpolation

(The number of protrusions with a height of 10 nm or more, and the number of protrusions with a height of 5 nm or more) The particle analysis was performed using measurement data showing a center value among the measurement values obtained by measuring the maximum protrusion height 7 times. The particle analysis was obtained under the following conditions using the analysis software of Vertscan R550H-M100. The particle analysis was performed based on the surface roughness of the above-mentioned region, the measurement of the maximum protrusion height, and the measurement area of the same area, and the number of protrusions with a maximum height of 10 nm or more, or the number of protrusions with a maximum height of 5 nm or more was calculated. The number of protrusions is a value converted by 1 mm ² . (Particle analysis conditions) ・Surface correction: 4 times of correction ・Storage processing: Complete interpolation ・Break analysis ・Reference height: Zero surface

(Ceramic peeling force) The slurry composition I composed of the following materials was stirred and mixed for 10 minutes, and dispersed with zirconia beads having a diameter of 0.5 mm using a bead mill for 10 minutes to obtain a primary dispersion. Then the slurry composition II composed of the following materials was added to the primary dispersion at a ratio of (slurry composition I): (slurry composition II)=3.4:1.0, using a bead mill with a diameter of 0.5 The mm zirconia beads were dispersed twice for 10 minutes to obtain a ceramic slurry. (Slurry Composition I) Toluene 22.3 parts by mass 18.3 parts by mass ethanol Barium titanate (average particle size 100nm) 57.5 parts by mass 1.9 parts by mass (Slurry Composition II) Toluene 39.6 parts by mass 39.6 parts by mass of ethanol 3.3 parts by mass of dioctyl phthalate Polyvinyl butyral (Esleck BM-S manufactured by Sekisui Chemical Co., Ltd.) 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 with an applicator so that the dried slurry became 1.0 μm, and dried at 60° C. for 1 minute to obtain a release film with a ceramic green body. . The obtained release film with ceramic green body was de-energized by a de-electric machine (manufactured by Keyence Corporation, SJ-F020), and then a peeling tester (manufactured by Kyowa Interface Science Co., Ltd., VPA-3, with a load cell load of 0.1 N) was used to remove electricity. The peeling was performed at a peeling angle of 90 degrees, a peeling temperature of 25° C., and a peeling speed of 10 m/min. Regarding the peeling direction, a double-sided adhesive tape (No. 535A, manufactured by Nitto Denko Co., Ltd.) was attached to a SUS (stainless steel) plate attached to the peeling tester, and the double-sided adhesive tape was placed on the double-sided adhesive tape with the ceramic green body side. In the following form, the release film is fixed, and peeling is performed by pulling the side of the release film. Among the obtained measured values, the average value of the peeling force at a peeling distance of 20 mm to 70 mm was calculated, and this value was taken as the peeling force. The measurement was carried out five times in total, and the average value of the peeling force was used for evaluation. The numerical value of the peeling force obtained was judged by the following reference|standard. 〇: 0.1mN/mm or more to less than 1.0mN/mm ×: 1.0mN/mm or more

(Pinhole evaluation of ceramic green body) In the same manner as the peelability evaluation of the aforementioned ceramic slurry, a ceramic green body having a thickness of 1 μm was formed on the release surface of the release film. Next, peel off the mold release film from the mold release film with the ceramic green body to obtain the ceramic green body. In the central region of the film width direction of the obtained ceramic green body, light was irradiated from the opposite side of the ceramic slurry coated surface in a range of 25 cm ² to observe the generation of pinholes that can be seen through light penetration, and visually judged according to the following criteria. 〇: No pinholes occurred ×: One or more pinholes occurred

(Production of polyethylene terephthalate pellets (PET (I))) For the esterification reaction device, a three-stage complete mixing tank having a stirring device, a fractionator, a raw material charging port, and a product extraction port was used. Constituted continuous esterification reaction device. TPA (terephthalic acid) was set to 2 ton/hour, EG (ethylene glycol) was set to 2 mol with respect to 1 mol of TPA, and antimony trioxide was set to an amount of 160 ppm of Sb atoms with respect to the produced PET, These slurries were continuously supplied to the first esterification reaction tank of the esterification reaction apparatus, and the reaction was carried out at 255° C. with an average residence time of 4 hours under normal pressure. Next, the reaction product in the first esterification reaction tank is continuously taken out of the system to be supplied to the second esterification reaction tank, and the distillate from the first esterification reaction tank is distilled off in the second esterification reaction tank. EG was supplied in an amount of 8% by mass relative to the generated PET, and further, an EG solution containing magnesium acetate tetrahydrate in an amount of 65 ppm of Mg atoms relative to the generated PET, and TMPA (phosphoric acid) containing P atoms in an amount of 40 ppm relative to the generated PET were added. The EG solution of trimethyl ester) was reacted at 260°C with an average residence time of 1 hour under normal pressure. Next, the reaction product of the second esterification reaction tank was continuously taken out of the system and supplied to the third esterification reaction tank, while using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.) at 39 MPa (400 kg/cm ² ) 0.2 mass % of porous silica gel with an average particle size of 0.9 μm and an average particle size of 0.6 μm adhered to 1 mass % of ammonium salt of polyacrylic acid per unit of calcium carbonate 0.4 mass % of the synthetic calcium carbonate was added as a 10% EG slurry, respectively, and the reaction was carried out at 260° C. with an average residence time of 0.5 hours under normal pressure. The esterification reaction product generated in the third esterification reaction tank was continuously supplied to the continuous polycondensation reaction device of the third stage to carry out polycondensation, and the filtration was carried out with a sintered filter of stainless steel with a 95% cut surface diameter of 20 μm. Then, ultrafiltration was performed, it was extruded into water, and after cooling, it was cut into pieces to obtain PET pieces with an intrinsic viscosity of 0.60 dl/g (hereinafter referred to as PET (I)). The lubricant content in the PET flakes was 0.6% by mass.

(Preparation of polyethylene terephthalate particles (PET(II))) On the other hand, in the production of the above-mentioned PET(I) chips, PET chips with an intrinsic viscosity of 0.62 dl/g (hereinafter referred to as PET(II)) completely free of particles such as calcium carbonate and silicon dioxide were obtained.

(Manufacture of Laminated Film X1) After drying these PET chips, they were melted at 285°C, melted at 290°C by a separate extruder, and sintered using 95% stainless steel sintered filters with a section diameter of 15 μm and 95% stainless steel particles with a section diameter of 15 μm. The sintered filter is used for 2-stage filtration, which is collected in the feed block, and PET (I) becomes the surface layer B (the opposite to the release surface side layer), and PET (II) becomes the surface layer A (the release surface side layer) ), extruded (casting) at a speed of 45m/min into a sheet, and electrostatically bonded and cooled on a casting drum at 30°C by the electrostatic bonding method to obtain an inherent viscosity of 0.59dl/g. Unextended polyethylene terephthalate sheet. The layer ratio was adjusted so as to be PET(I)/(II)=60 mass %/40 mass % by the discharge amount of each extruder. Next, after heating this unstretched sheet with an infrared heater, it stretched 3.5 times in the longitudinal direction at a roll temperature of 80° C. with the speed difference between the rolls. After that, it was guided to a tenter and stretched by 4.2 times in the transverse direction at 140°C. Next, heat treatment was performed at 210° C. in the heat setting zone. After that, a 2.3% relaxation treatment was performed at 170° C. in the transverse direction to obtain a biaxially stretched polyethylene terephthalate film X1 with a thickness of 31 μm. The Sa of the surface layer A of the obtained film X1 was 1 nm, and the Sa of the surface layer B was 28 nm.

(Manufacture of Laminated Film X2) As the laminated film X2, E5101 (Toyobo Ester (registered trademark) film, manufactured by Toyobo Co., Ltd.) having a thickness of 25 μm was used. E5101 is a structure in which particles are contained in the surface layer A and the surface layer B. The Sa of the surface layer A of the laminated film X2 was 24 nm, and the Sa of the surface layer B was 24 nm.

(Cationically hardened polydimethylsiloxane (a)) (a)-1: UVPOLY215 (manufactured by Arakawa Chemical Industry, 100% solids)

(Cationically curable resin (b)) (b)-1: Celloxide 2021P (manufactured by Daicel, 100% solid) (b)-2: X-40-2670 (manufactured by Shin-Etsu Chemical Industry, 100% solid)

(acid generator (c)) (c)-1: CPI-101A (manufactured by San-Apro, solid content 50%)

(Example 1) After passing the release layer forming composition 1 of the following composition through a filter capable of removing 99% or more of foreign matter of 0.5 μm or more, it was applied using a reverse gravure so that the coating amount would be 5.0 g/m ² It is applied on the surface layer A of the laminate film X1. Thereafter, the processing speed was adjusted so as to enter the first drying furnace after 0.5 seconds, and heating and drying were continuously performed at a temperature of the first drying furnace of 120°C and a temperature of the second drying furnace of 90°C. After the drying step, the cooling roller was irradiated with ultraviolet rays with a cumulative light intensity of 100 mJ/cm ² with an ultraviolet irradiator (H bulb, manufactured by Heraeus) to harden the release layer to obtain a release film for resin sheet molding. In addition, as a result of evaluating the smoothness, peelability, and pinholes of the obtained release film, as shown in Table 1, favorable results were obtained. Thus, the obtained release film for resin sheet shaping|molding is a release film which can manufacture the resin sheet whose thickness is 0.2 micrometer or more and 1.0 micrometer or less, for example. In addition, the weight (mg/m ² ) of each component (a), (b), (c) described in the table represents the content ratio per unit solid (the weight of each component relative to the total weight of the release layer). (Release layer forming composition 1) 24.000 parts by mass of methyl ethyl ketone (SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1) 24.000 mass parts of toluene Parts (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

(Example 2 to Example 4) A release film for resin sheet molding was obtained by the same method as in Example 1, except that the composition and manufacturing method of the release layer were changed to those described in Table 1.

(Example 5) A release film for resin sheet molding was obtained in the same manner as in Example 1, except that the release layer forming composition 2 of the following composition was used. (Release layer forming composition 2) 38.400 parts by mass of methyl ethyl ketone (SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1) 38.400 parts by mass of toluene Parts (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

(Example 6) Except that n-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.

(Example 7, Example 8) A release film for resin sheet molding was obtained in the same manner as in Example 2, except that the coating amount and the solid content ratio were changed to those described in Table 1. At this time, it prepared so that the organic solvent ratio might become the same as that of the release layer forming composition 1.

(Example 9) A release film for resin sheet molding was obtained by the same method as in Example 1 except that the composition 3 for forming a release layer was changed to the following composition. (Composition 3 for forming a release layer) 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

(Example 10 to Example 12) A release film for resin sheet molding was obtained by the same method as in Example 1, except that the composition and manufacturing method of the release layer were changed to those described in Table 1.

(Example 13) A release film for resin sheet molding was obtained by the same method as in Example 1, except that the release layer forming composition 4 of the following composition was used. (Release layer forming composition 4) 38.400 parts by mass of methyl ethyl ketone (SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1) 38.400 parts by mass of toluene Parts (SP value (δ): 18.2, (δ _D ): 18.0, (δ _P ): 1.4, (δ _H ): 2.0) n-heptane 19.200 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

(Example 14) Except that n-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.

(Example 15, Example 16) A release film for resin sheet molding was obtained in the same manner as in Example 2, except that the coating amount and the solid content ratio were changed to those described in Table 1. At this time, it prepared so that the organic solvent ratio might become the same as that of the release layer forming composition 3.

(Example 17) A release film for forming an ultra-thin layer resin sheet was obtained by the same method as in Example 1, except that the composition 5 for forming a release layer having the following composition was used. (Composition 5 for forming a release layer) 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) n-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 (c)-1 0.004 parts by mass

(Example 18) A release film for resin sheet molding was obtained in the same manner as in Example 1, except that it was prepared in the same manner as in the composition 5 for forming the release layer by changing the solid content concentration described in Table 1 and making the organic solvent ratio the same as that of the release layer forming composition 5. .

(Example 19) A release film for resin sheet molding was obtained by the same method as in Example 17 except that the production method described in Table 1 was changed.

(Example 20) A release film for ultra-thin layer resin sheet molding was obtained in the same manner as in Example 1 except that the composition 6 for forming a release layer was changed. (Composition 6 for forming a release layer) Methyl ethyl ketone 39.920 parts by mass (SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1) Toluene 39.920 Parts by mass (SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1) n-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

(Example 21) Except that the n-heptane in the release layer forming composition 5 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 1.

(Example 22, Example 23) A release film for resin sheet molding was obtained by the same method as in Example 17, except that the coating amount and the solid content concentration were changed to those described in Table 1. At this time, it prepared so that the organic solvent ratio might become the same as that of the release layer forming composition 5.

(Comparative Example 1) A release film for ultra-thin layer resin sheet molding was obtained by the same method as in Example 1 except that the composition 7 for forming a release layer was changed to the following composition. (Release layer forming composition 7) 24.000 parts by mass of methyl ethyl ketone (SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1) 24.000 mass parts of toluene Parts (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

(Comparative Example 2) A release film for ultra-thin-layer resin sheet molding was obtained by the same method as in Example 1, except that the composition 8 for forming a release layer was changed to the following composition. (Release layer forming composition 8) 24.000 parts by mass of methyl ethyl ketone (SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1) 24.000 mass parts of toluene Parts (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 2.941 parts by mass (b)-2 0.981 parts by mass (c)-1 0.078 parts by mass

(Comparative Example 3) A release film for ultra-thin layer resin sheet molding was obtained by the same method as in Example 1, except that the composition 9 for forming a release layer was changed to the following composition. (Release layer forming composition 9) 24.000 parts by mass of methyl ethyl ketone (SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1) 24.000 mass parts of toluene Parts (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 3.922 parts by mass (c)-1 0.078 parts by mass

(Comparative Example 4) A release film for ultra-thin-layer resin sheet molding was obtained in the same manner as in Example 10 except that it was applied to the laminate film X2.

[Table 1A] release film substrate film release layer (a) Cationic hardening polydimethylsiloxane (b) Cation hardening resin (c) Acid generator Thickness (μm) Total weight of release layer (mg/m ² ) type The weight contained in the release layer mg/m ² type The weight contained in the release layer mg/m ² type The weight contained in the release layer mg/m ² Example 1 X1 (a)-1 2.0 (b)-1 194 (c)-1 3.9 0.2 200 Example 2 X1 (a)-1 10 (b)-1 186 (c)-1 3.9 0.2 200 Example 3 X1 (a)-1 39 (b)-1 157 (c)-1 3.9 0.2 200 Example 4 X1 (a)-1 10 (b)-1 186 (c)-1 3.9 0.2 200 Example 5 X1 (a)-1 10 (b)-1 186 (c)-1 3.9 0.2 200 Example 6 X1 (a)-1 10 (b)-1 186 (c)-1 3.9 0.2 200 Example 7 X1 (a)-1 10 (b)-1 186 (c)-1 3.9 0.2 200 Example 8 X1 (a)-1 10 (b)-1 186 (c)-1 3.9 0.2 200 Example 9 X1 (a)-1 2.0 (b)-2 194 (c)-1 3.9 0.2 200 Example 10 X1 (a)-1 10 (b)-2 186 (c)-1 3.9 0.2 200

[Table 1B] release film substrate film release layer (a) Cationic hardening polydimethylsiloxane (b) Cation hardening resin (c) Acid generator Thickness (μm) Total weight of release layer (mg/m ² ) type The weight contained in the release layer mg/m ² type The weight contained in the release layer mg/m ² type The weight contained in the release layer mg/m ² Example 11 X1 (a)-1 39 (b)-2 157 (c)-1 3.9 0.2 200 Example 12 X1 (a)-1 10 (b)-2 186 (c)-1 3.9 0.2 200 Example 13 X1 (a)-1 10 (b)-2 186 (c)-1 3.9 0.2 200 Example 14 X1 (a)-1 10 (b)-2 186 (c)-1 3.9 0.2 200 Example 15 X1 (a)-1 10 (b)-2 186 (c)-1 3.9 0.2 200 Example 16 X1 (a)-1 10 (b)-2 186 (c)-1 3.9 0.2 200 Example 17 X1 (a)-1 10 - - (c)-1 0.2 0.01 10 Example 18 X1 (a)-1 49 - - (c)-1 1.0 0.05 50 Example 19 X1 (a)-1 10 - - (c)-1 0.2 0.01 10 Example 20 X1 (a)-1 10 - - (c)-1 0.2 0.01 10

[Table 1C] release film substrate film release layer (a) Cationic hardening polydimethylsiloxane (b) Cation hardening resin (c) Acid generator Thickness (μm) Total weight of release layer (mg/m ² ) type The weight contained in the release layer mg/m ² type The weight contained in the release layer mg/m ² type The weight contained in the release layer mg/m ² Example 21 X1 (a)-1 10 - - (c)-1 0.2 0.01 10 Example 22 X1 (a)-1 10 - - (c)-1 0.2 0.01 10 Example 23 X1 (a)-1 10 - - (c)-1 0.2 0.01 10 Comparative Example 1 X1 - - (b)-2 196 (c)-1 3.9 0.2 200 Comparative Example 2 X1 (a)-1 147 (b)-2 49 (c)-1 3.9 0.2 200 Comparative Example 3 X1 (a)-1 196 - - (c)-1 3.9 0.2 200 Comparative Example 4 X2 (a)-1 10 (b)-2 186 (c)-1 3.9 0.2 200

[Table 2A]

[Table 2B]

[Table 2C]

In Comparative Example 1, since the cation-curable polydimethylsiloxane (a) was not contained, the peeling force of the ceramic sheet was large, and peeling was impossible. In Comparative Examples 2 to 4, the number of protrusions with a height of 10 nm or more exceeded 200/mm ² , and pinholes were formed in the green body of the object to be released. Furthermore, in Comparative Example 4, inorganic particles were present in the entire base material, the smoothness of the release film was remarkably poor, and breakage of the green body, pinholes, and the like occurred. [Industrial Availability]

According to the present invention, by improving the smoothness and peelability of the release layer, a release film can be provided, and even an ultra-thin layer with a thickness of less than 1 μm can still form a resin sheet with few defects, so that there is no need to worry about it. A defect occurs and a resin sheet is produced.

Claims (10)

A release film for resin sheet molding, comprising a polyester film as a base material and a release layer; the polyester film has a surface layer A substantially free of inorganic particles; the surface layer A has the release layer; The aforementioned release layer is a hardened layer of the release layer-forming composition; the aforementioned release layer-forming composition contains cationic hardening polydimethylsiloxane (a); the region surface roughness (Sa) of the aforementioned release layer It is 2 nm or less; The number of protrusions with a height of 10 nm or more existing on the surface of the release layer is 200 pieces/mm ² or less. The release film for resin sheet molding according to claim 1, wherein the maximum protrusion height (Sp) of the release layer is 20 nm or less, and the number of protrusions with a height of 5 nm or more to less than 10 nm on the surface of the release layer is the same as the above-mentioned The total number of protrusions of 10 nm or more is 1500 pieces/mm ² or less. The release film for resin sheet molding according to claim 1 or 2, wherein the cationically curable polydimethylsiloxane (a) has at least one selected from the group consisting of vinyl ether group, oxetanyl group, epoxy group , The functional group of alicyclic epoxy group. The release film for resin sheet molding as claimed in claim 1 or 2, wherein the content of the cationically curable polydimethylsiloxane (a) contained in the release layer is 90 mg/m ² or less. The release film for resin sheet molding according to claim 1 or 2, wherein the release layer-forming composition further contains a cationic hardening compound (b-1) without a polysiloxane skeleton; The aforementioned cationic curable compound (b-1) has two or more alicyclic epoxy groups in the molecule; Content of the said cation hardening type compound (b-1) is 80 mass % or more with respect to a total of 100 mass parts of cation hardening type polydimethylsiloxane (a) and cation hardening type compound (b-1). The release film for resin sheet molding according to claim 1 or 2, wherein the release layer-forming composition further contains a cyclosiloxane compound (b-2) having an alicyclic epoxy group; The aforementioned cyclic siloxane compound (b-2) has two or more alicyclic epoxy groups in the molecule; The content of the cyclosiloxane compound (b-2) is 80 parts by mass relative to 100 parts by mass in total of the cation-curable polydimethylsiloxane (a) and the cyclosiloxane compound (b-2). %above. The release film for resin sheet molding according to claim 1 or 2, wherein the release layer-forming composition contains an organic solvent with an SP value (δ) of 14 or more and 17 or less; In the release layer forming composition, the organic solvent having an SP value (δ) of 14 or more and 17 or less is contained in an amount of 10 mass % or more with respect to 100 parts by mass of the total weight of the release layer forming composition. The release film for resin sheet molding as described in claim 1 or 2 is used to manufacture a resin sheet containing an inorganic compound. The release film for resin sheet molding according to claim 8, wherein the inorganic compound-containing resin sheet is a green ceramic body. The release film for resin sheet molding as described in claim 1 or 2 is used for molding a resin sheet with a thickness of 0.2 μm or more and 1.0 μm or less.