TW202330223A - 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 forming a resin sheet, and more specifically relates to a release film used when forming an ultra-thin layer of resin sheet.

In the past, a polyester film was used as a base material and a release film layered on the base material was used as an adhesive sheet system as a step film for molding resin sheets such as coatings, polymer films, and optical lenses. to use.

The aforementioned release film is also used as a step film for ceramic green molding that requires high smoothness, such as multilayer ceramic capacitors and ceramic substrates. In recent years, along with miniaturization and higher capacity of multilayer ceramic capacitors, the thickness of ceramic green sheets tends to be thinner. The ceramic green body is molded by coating a slurry containing ceramic components such as barium titanate and a binder resin on a release film and drying it. The formed ceramic green body is printed with electrodes and peeled off from the release film. The resulting ceramic green body is laminated, pressed, fired, and coated with external electrodes to manufacture a multilayer ceramic capacitor.

In the case of forming a ceramic green body 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 easily produce defects such as shrinkage cavities (cissing) or pinholes. This is the problem. In recent years, further thinning of the ceramic green body is being pursued, and a ceramic green body having a thickness of 1.0 μm or less, more specifically, 0.2 μm to 1.0 μm, is increasingly required. For this reason, the requirements for the smoothness of the surface of the release layer are even higher. In addition, microscopic protrusions and foreign matter on the release layer are involved in deformation of the molded ceramic green body, and there are problems that pinholes and fragments during peeling are likely to occur.

In addition, as the ceramic green body becomes thinner, the peelability 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, and sheet defects, uneven thickness, etc., pinholes, and fragments will occur. This is the problem. Therefore, it is required to be able to peel off the ceramic green body with a lower and uniform force. That is, in order to produce an ultra-thin resin sheet without defects, especially a ceramic green body without defects, a release film having extremely high smoothness and excellent peelability is required.

As a release film excellent in smoothness and peelability, what is described in the following patent documents is mentioned. For example, Patent Document 1 proposes a release film having a release layer mainly composed of a radical-curable resin. Patent Document 2 proposes a release film formed by laminating a smoothing layer and a release layer. Patent Document 3 proposes a release film having a release layer using a cation-curing epoxy resin as a main component. Patent Document 4 proposes a release film having a release layer using cation-curable polydimethylsiloxane as a main component. [Prior Art Literature] [Patent Document]

[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.

[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 insufficient because the release layer is provided on the base film having insufficient smoothness. Furthermore, the present inventors have worked hard to find that free radical hardening resins are poorly cured due to oxygen hindrance, so the solvent resistance on the surface of the release layer is poor, and the release layer will be damaged due to the molding of the ceramic green body or The organic solvent used for internal electrode printing is corroded, resulting in poor peelability. The invention of Patent Document 2 uses a thermosetting melamine resin for the smoothing coating layer and the release coating layer, and high heat is required to accelerate the curing reaction. For this reason, the planarity of a release film may be impaired by the heat at the time of processing. In addition, due to the need for multiple processing of the smoothing coating layer and the release coating layer, not only the foreign matter may be mixed into the release film, but also the release layer may be scratched, and the ceramic green body molded on the release layer may be damaged. Defects occur due to transfer of foreign matter or scratches.

Patent Document 3 and Patent Document 4 respectively propose release layers using cation-curable resins in order to improve hardening defects due to oxygen barriers and planar defects caused by processing heat. However, the release film of Patent Document 3 lacks the smoothness of the base film and has a problem of poor smoothness on the surface of the release layer. In addition, the release agent component disclosed in Patent Document 3 lacks reactivity, has poor solvent resistance, and has problems with peelability. Since the release film of Patent Document 4 has a release layer using a liquid cationic hardening type polydimethylsiloxane resin as the main component, the resin will condense on the unevenness of the base film and the oligomers present on the surface of the base film. Objects and other protrusions may cause flatness problems. In addition, the crosslink density of the release layer is low, and there is also a problem in peelability.

The present invention is made on the basis of the subject of related prior art. That is, the purpose is to provide a release film with a release layer that is particularly excellent in smoothness and peelability, and to provide a resin sheet that can form an ultra-thin layer without defects, especially an ultra-thin layer. The release film of the ceramic green body. [Means to solve the problem]

As a result of diligent research by the present inventors to solve the above-mentioned problems, they 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 constitutions. [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; Type 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 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/mm ² or less. [2] In one embodiment, the maximum protrusion height (Sp) of the release layer is 20 nm or less, and the ratio of the number of protrusions with a height of 5 nm or more to less than 10 nm existing on the surface of the release layer to the number of protrusions of 10 nm or more The total is 1500 pieces/mm ² or less. [3] In one embodiment, the cationic hardening polydimethylsiloxane (a) has at least one functional group 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 cation-curable compound (b-1) that does not have a polysiloxane skeleton; the cation-curable compound (b-1) has two or more The alicyclic epoxy group, the content of the cation-curable compound (b-1) relative to the total of 100 parts by mass of the cation-curable polydimethylsiloxane (a) and the cation-curable compound (b-1) It is more than 80% by mass. [6] In one embodiment, the release layer forming composition further contains a cyclic siloxane compound (b-2) having an alicyclic epoxy group; the cyclic siloxane compound (b-2) is Having two or more alicyclic epoxy groups in the molecule, cyclic silicon is 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 with an SP value (δ) of 14 to 17. In the release layer-forming composition, relative to the total amount of the release layer-forming composition 100 parts by mass by weight contain the aforementioned organic solvent having an SP value (δ) of 14 or more and 17 or less in an amount of 10 mass % or more. [8] In one embodiment, a release film is provided, which is used to manufacture a resin sheet containing an inorganic compound. [9] In one embodiment, the resin sheet containing the inorganic compound is a ceramic green body. [10] In one embodiment, a release film is provided, which is used to form a resin sheet with a thickness of not less than 0.2 μm and not more than 1.0 μm. [Efficacy of the invention]

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

Hereinafter, the present invention will be described in detail. The present invention is a release film for forming a resin sheet, which has 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 surface roughness (Sa) of the release layer is less than 2nm ; The number of protrusions with a height of 10 nm or more existing on the surface of the release layer is 200/mm ² or less.

The present invention having such a structure can provide a uniform thickness without defects for a resin sheet with a thickness of 0.2 μm to less than 1.0 μm, and can suppress defects such as pinholes, because the release layer has excellent smoothness and peelability. In addition, the present invention can exhibit the following effects. In the present invention, since a release layer is provided on a base film having sufficient smoothness, the smoothness of the release layer can also be ensured. Furthermore, the present invention can suppress poor hardening caused by oxygen hindrance in the release layer, and can exert high cross-linking of the release layer. This invention which can exhibit such an effect can improve the solvent resistance of the release layer surface, for example. By improving the solvent resistance of the surface of the release layer, it is possible to prevent the release layer from being corroded by the organic solvent used in the molding of the ceramic green body and the printing of the internal electrodes, and has high peelability. Moreover, according to this invention, compared with the release layer which has a thermosetting melamine resin, for example, high heat is not needed in order to accelerate hardening reaction. Therefore, the heat during processing can be suppressed from impairing the planarity of the release film. In addition, according to the production method of the present invention, by passing through the coating step and the drying step of the present invention, aggregation of the composition for forming the release layer can be suppressed, and a release film having a release layer with extremely high smoothness can be obtained.

More specifically, by applying a composition for forming a release layer containing a predetermined amount of cation-curable polydimethylsiloxane (a) to the surface layer A of the base film that does not substantially contain inorganic particles, and using Hardening can obtain a release layer with extremely high smoothness. Furthermore, by controlling the content of the cation-curable polydimethylsiloxane (a) in the release layer to be below a predetermined amount, the cation-curable polydimethylsiloxane can be suppressed during the processing of the release layer. The alkane (a) aggregates microscopic foreign matter present in the substrate film and microscopic protrusions derived from oligomers. Although the explanation should not be limited to a specific theory, by raising the first drying temperature (enhanced drying), it is possible to prevent component (a) from coagulating on the fine protrusions caused by the original roll body. In addition, by suppressing poor hardening caused by oxygen inhibition, improving the solvent resistance of the surface of the release layer, suppressing the incorporation of foreign matter into the release layer, and suppressing the scratches of the release layer, it is possible to prevent damage to the release material such as ceramic green bodies. Deformation of the sheet due to transfer printing, such as damage, scars, and foreign matter during peeling. As a result, a release layer excellent in smoothness, hardness, releasability, and contamination prevention of 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 formed. Details will be described later.

Moreover, this invention provides the manufacturing method of the release film for resin sheet molding which has the following steps in another aspect. The coating step is to apply a release layer forming composition on the aforementioned surface layer A of the polyester film having a surface layer A. The surface layer A is a layer substantially free of 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 aforementioned heating drying has a first drying step and a subsequent second drying step, the aforementioned first The drying temperature T1 in the drying step is higher than the drying temperature T2 in the second drying step; and, the photocuring step is to irradiate active energy rays after the drying step to harden the release layer forming composition.

In the manufacturing method related to the present invention, in particular, by setting the manufacturing conditions when 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 release layer forming composition, organic solvent composition, drying time, drying temperature, etc. is 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 the release layer can be suppressed, and a release layer with excellent 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 a polyester generally used as a base material for a release film by film-forming can be used. It is preferably a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component, such as polyethylene terephthalate, polyethylene naphthalate-2,6-ethylene glycol, polyethylene terephthalate Butyl phthalate, polytrimethylene terephthalate, or copolymers with these resin components as the main component are more suitable, especially polyester films formed of polyethylene terephthalate is particularly suitable. In polyethylene terephthalate, the repeating unit of ethylene terephthalate is preferably more than 90 mole%, more preferably more than 95 mole%. A small amount of other dicarboxylic acid components and diols can also be copolymerized components, but considering the cost, it is better to manufacture only terephthalic acid and ethylene glycol. In addition, known additives such as antioxidants, photostabilizers, ultraviolet absorbers, crystallizers, and the like may be added within the range that does not hinder the film effect of the present invention. For reasons such as the elastic modulus of the polyester film in two directions, etc., a biaxially oriented polyester film is preferred.

The intrinsic viscosity of the polyester film is preferably from 0.50 dl/g to 0.70 dl/g, more preferably from 0.52 dl/g to 0.62 dl/g. When the intrinsic viscosity is 0.50 dl/g or more, it is preferable because a large amount of fracture does not occur in the stretching step. Conversely, when it is 0.70 dl/g or less, the cutting property when cutting 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, when only the "polyester film" is described in this specification, it means the polyester film which has (laminated) the surface layer A. Moreover, in this invention, a 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, when mentioned in the specification, the polyester film which further has (laminates) the surface layer B may be abbreviated as "polyester film".

The method for producing the polyester film in the present invention is not particularly limited, and conventionally generally used methods can be used. For example, the aforementioned polyester is melted with an extruder, extruded into a film, cooled in a rotating cooling drum to obtain an unstretched film, and the unstretched film is stretched. When stretching is biaxial stretching, it is preferable in terms of mechanical properties and the like. A biaxially stretched film can be obtained by biaxially stretching a longitudinally or transversely uniaxially stretched film stepwise in the transverse or longitudinal direction, or by synchronously biaxially stretching an unstretched film in the longitudinal and transverse directions .

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 stretch 1 to 8 times, especially 2 to 6 times in the vertical and horizontal directions.

The thickness of the polyester film is preferably from 12 μm to 50 μm, more preferably from 15 μm to 38 μm, and still more preferably from 19 μm to 33 μm. As long as the thickness of the film is 12 μm or more, it is preferable because there is no risk of thermal deformation during film production, processing steps of release layer, and molding of ceramic green bodies. On the other hand, as long as the thickness of the film is 50 μm or less, the amount of film discarded after use will not increase extremely, which is preferable in terms of reducing 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 may contain particles on the opposite side of the surface layer A that does not substantially contain inorganic particles. In terms of laminate composition, if the layer on the side where the release layer is coated is regarded as surface layer A, the layer on the opposite side is regarded as surface layer B, and the core layer other than surface layer A and surface layer B is regarded as layer C, then The layer configuration in the thickness direction includes a laminated structure such as a release layer/A/B or a release layer/A/C/B. Of course, the layer C can also be composed of plural 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 slipperiness when the film is wound up into a roll.

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, it can exhibit the following average surface roughness in the region. In the present invention, the area surface average roughness (Sa) of the surface layer A is the area surface average roughness (Sa) in the face where the release layer is configured, and the area surface average roughness (Sa) in the face where the release layer is configured ( Sa) is 7nm or less. If Sa is 7nm 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, protrusions of the release layer components aggregated on the surface layer A can be suppressed, and deterioration of the smoothness of the release layer surface can be prevented.

The average surface roughness (Sa) of the area of the surface layer A is preferably as small as possible, and may be at least 0.1 nm. In one aspect, the area average surface roughness (Sa) of the surface layer A is not less than 0.1 nm and not more than 7 nm, for example, not less than 0.5 nm and not more than 5 nm, or not less than 0.5 nm and not more than 4 nm. 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 layer ceramic green body. Furthermore, when the release layer is formed, protrusions of the release layer components that aggregate on the surface layer A can be suppressed, and deterioration of the smoothness of the release layer surface can be prevented.

In the present invention, "substantially free of inorganic particles" means that the content of inorganic elements is not more than 50 ppm, preferably not more than 10 ppm, most preferably not more than the detection limit when the inorganic elements are quantified by fluorescent X-ray analysis. This is because even if inorganic particles are not actively added to the film, there are still cases where contamination components from external foreign matter, pollutants attached to the production line or equipment in the raw material resin or film manufacturing steps are mixed into the film. .

In the polyester film base material of this invention, you may have the surface layer B on the surface opposite to the surface in which the release layer was arrange|positioned. Surface layer B preferably contains particles. By containing particles, it is excellent in film sliding properties and ease of degassing, and can have excellent conveyance and winding properties. It is especially preferable to contain silicon dioxide 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 area average surface roughness (Sa) of the film of the surface layer B is, for example, not less than 1 nm and not more than 40 nm. More preferably, it is not less than 5 nm and not more than 35 nm. When the total amount of silica particles and/or calcium carbonate particles is more than 1000ppm, and Sa is more than 1nm, when the film is rolled into a roll, the air can escape evenly, and the winding state can be good and the planarity is good . With this feature, for example, in the case of manufacturing ultra-thin resin sheets (such as ceramic green bodies) with a thickness of 0.2 μm or more to 1.0 μm or less, it is possible to prevent wrinkles and misalignment of the coiled ceramic green bodies, and to provide transportation Release film with excellent performance, rollability and storage properties. In addition, when the total content of silica particles and/or calcium carbonate particles is 15000ppm or less and Sa is 40nm or less, the particles functioning as a lubricant are less likely to aggregate and coarse protrusions (such as those with a height of 1 μm or more) will not occur. Protrusions), so when manufacturing ultra-thin layer resin sheets (such as ceramic green bodies), it can suppress the occurrence of pinholes caused by winding, for example, and provide resin sheets with stable quality.

As the particles contained in the surface layer B, in addition to silicon dioxide and/or calcium carbonate, inert inorganic particles and/or heat-resistant organic particles may be used. From the perspective of transparency and cost, it is better to use silicon dioxide particles and/or calcium carbonate particles. Other usable inorganic particles include alumina-silicon dioxide composite oxide particles, hydroxyapatite particles, and the like. Furthermore, examples of the heat-resistant organic particles include cross-linked polyacrylic particles, cross-linked polystyrene particles, benzoguanamine-based particles, and the like. When silica particles are used, porous colloidal silica is preferred. When calcium carbonate particles are used, light calcium carbonate surface-treated with a polyacrylic acid-based polymer compound is preferable from the viewpoint of preventing the particles from falling off.

The average particle size of the particles added to the above-mentioned surface layer B is preferably from 0.1 μm to 2.0 μm, particularly preferably from 0.5 μm to 1.0 μm. 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, if the average particle diameter is 2.0 μm or less, the deformation of the surface layer A can be suppressed, and the uneven thickness of the ceramic green body and the occurrence of pinholes can be suppressed.

The above-mentioned surface layer B may contain two or more types of particles of different materials. In addition, particles of the same kind but having different average particle diameters may be included. Moreover, different particle|grains of 2 or more types may have a different average particle diameter within the said range. By containing two different types of particles, it is possible to suppress the unevenness formed on the surface layer B to a high degree, and it is preferable because it can balance sliding properties and smoothness.

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

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

In addition, from an economic point of view, 50% to 90% by mass of film scraps or recycled plastic bottles can be used in layers other than the above-mentioned surface layer A (surface layer B or the aforementioned 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 surface average roughness (Sa) satisfy the above-mentioned range.

In addition, based on the improvement of the adhesion of the release layer coated later or the consideration of antistatic, etc., the surface of the surface layer A and/or the surface of the surface layer B can be stretched before or uniaxially in the film forming step. After coating, corona treatment, etc. can also be applied. In the case of providing a coating on the surface layer A, it is preferable that the coating does not substantially contain particles.

(Release layer) In this invention, a release layer is laminated|stacked on the surface layer A. As shown in FIG. 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 contain at least cation-hardening polydimethylsiloxane (a), and the release layer region The surface roughness (Sa) is 2nm or less, and the number of protrusions with a height of 10nm or more existing on the surface of the release layer is 200/mm ² or less. Due to the characteristics of the release layer, it can suppress pinholes in ultra-thin film resin sheets (such as ceramic green bodies) that require high smoothness, and can form resin sheets with uniform film thickness. More specifically, the release layer of the present invention can suppress poor hardening caused by oxygen hindrance, and can exhibit high crosslinking of the release layer. This invention which exhibits such an effect can improve the solvent resistance of the release layer surface, for example. By improving the solvent resistance of the surface of the release layer, it is possible to suppress the erosion of the release layer due to the organic solvent used in the molding of the ceramic green body and the printing of the internal electrodes, and high peelability can be achieved. In addition, according to the present invention, it is not necessary to use high heat above 130° C. to accelerate the hardening reaction. Therefore, damage to the planarity of the release film due to heat during processing can be suppressed. In addition, it can prevent foreign matter from being mixed into the release film for resin sheet molding, and prevent the occurrence of scratches on the release layer. For release objects such as ceramic green bodies, it can suppress the occurrence of sheet damage caused by the transfer of foreign matter and scratches.

The area surface average roughness (Sa) of the release layer is 2nm or less. In addition, the number of protrusions with a height of 10 nm or more present on the surface of the release layer is 200/mm ² or less. The surface of the release layer of the release film is to avoid defects in the coated and molded ceramic sheet on the release layer, so the average surface roughness (Sa) and the number of protrusions above 10nm in the above region meet the predetermined conditions. As long as the area surface roughness (Sa) is 2nm or less, and the number of protrusions with a height of 10nm or more is 200/ ^mm2 or less, there will be no defects such as pinholes in the ceramic sheet during molding of the ceramic sheet, and the yield rate is good, so it is better. More preferably, the area surface roughness (Sa) is 1.7 nm or less, for example, 1.6 nm or less, 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 not less than 0.1 nm, and may be not less than 0.2 nm. On the other hand, in one aspect, the number of protrusions with 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 or less, or 100/mm 2 or} less. In addition, the number of protrusions with a height of 10 nm or more may be 1/mm ² or more, for example, may be 10/mm ² or more. By setting the number of protrusions with a height of 10 nm or more within the above-mentioned range, defects such as pinholes do not occur on the ceramic sheet, and excellent release properties can be provided 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/mm ² or less. The release layer having the area surface average 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 within such a range, 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 present on the surface of the release layer with a height of 5 nm or more to less than 10 nm and the number of protrusions of 10 nm or more is 1500/mm ² or less. If the total number of protrusions with a height of 5 nm or more to less than 10 nm on the release layer and the number of protrusions with a height of 10 nm or more is 1500/ ^mm2 or less, the defects of the ceramic sheet can be further suppressed, and a product with high smoothness can be obtained. The release layer is therefore better. More preferably, 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 of 10 nm or more is 1000/mm ² or less, for example, 500/mm ² or less.

The release layer related to the release film for resin sheet molding of the present invention is a layer obtained by hardening the release layer forming composition, and the release layer forming composition contains at least cation-curable polydimethylsiloxane (a). Cationic hardening type polydimethylsiloxane (a) undergoes crosslinking reaction due to cationic hardening reaction, so it does not cause poor hardening due to oxygen inhibition, and becomes a release layer with excellent solvent resistance. Therefore, there is no need to worry about the corrosion of the release layer due to the organic solvent used in the molding of ceramic green bodies and the printing of internal electrodes, and a release layer with excellent peelability can be obtained.

Furthermore, the present inventors have found that in the release layer containing the cation-curable polydimethylsiloxane (a), a high amount of the cation-curable polydimethylsiloxane (a) is important for realizing a release layer having smoothness. Type layer is important. Cationic hardening type polydimethylsiloxane (a) contains 90 mg/ ^m2 or less in the release layer, for example, 60 mg/ ^m2 or less, preferably 50 mg/ ^m2 or less, preferably 40 mg/ ^m2 or less More preferably, it is better to contain 30mg/ ^m2 or less. In addition, the cation-curable polydimethylsiloxane (a) may be 20 mg/m ² or less, for example. If the content of the cation-hardening type polydimethylsiloxane (a) in the release layer is 50 mg/m ^or less, it can suppress the polydimethylsiloxane (a) in the step of forming the release layer (such as the drying step). a) Agglomeration occurs, and there is no need to worry about producing a large number of 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, when the release layer is processed, polydimethylsiloxane (a) may segregate on the surface of the release layer, if the content is 50mg/ ^m2 or less It is not easy to coagulate, and can form a release layer with high smoothness. The smaller the content of polydimethylsiloxane (a) related to the present invention, the less likely it is to coagulate. As long as the content of the polydimethylsiloxane (a) in the release layer is more than 0.1mg/ ^m2 , 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, if it is 0.1 mg/m ² or more, it is also excellent in detachability, and 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 cation-curable polydimethylsiloxane (a). In addition, the compound (cured product) derived from the cation-curable polydimethylsiloxane (a) exists in the release layer in which the release layer forming composition was cured. In this specification, the compound derived from polydimethylsiloxane (a) present in the release layer may also be simply referred to as cation-curable polydimethylsiloxane (a).

The cation-curable polydimethylsiloxane (a) in the present invention refers to a polydimethylsiloxane having a cationic-curable functional group. The cation-curable functional group includes reactive functional groups exhibiting cation-curable properties, and specifically, vinyl ether groups, oxetanyl groups, epoxy groups, and alicyclic epoxy groups are examples. From the viewpoint of reactivity, among them, it is preferable to have at least one functional group selected from the group consisting of oxetanyl, epoxy, and alicyclic epoxy, and alicyclic epoxy is most preferred. By having such a functional group, a cross-linked structure can be formed by a cationic hardening reaction, and it becomes a release layer having excellent solvent resistance and excellent peelability, so it is preferable.

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

As the cation-curing polydimethylsiloxane (a), a commercially available one can be used suitably. Examples include Silicon Corlis (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, 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, etc. manufactured by Momentive Performance Materials.

The weight average molecular weight of the cation-curable polydimethylsiloxane (a) is preferably from 1,000 to 500,000, more preferably from 5,000 to 100,000. When the weight average molecular weight is 1000 or more, the cationic hardening reaction is easy to proceed and the releasability is excellent, so it is preferable. If it is 500,000 or less, the viscosity does not become too high, and it is excellent in applicability and has a high planarity release layer, so it is preferable.

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 substrate film substantially not containing 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, and processing can be performed at a higher speed, and the release layer can be obtained with high economical efficiency.

If the film thickness is further reduced, there is no need to worry about the tiny foreign matter that exists in the release processing steps and the like being entrained into the release layer. Therefore, there is no risk of protrusions originating from foreign matter 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 composed of a cation-curable polydimethylsiloxane (a) as the main component, the film thickness of the release layer is preferably 0.001 μm or more and less than 0.050 μm. If it is 0.001 μm or more, it is preferable because the release property is excellent. If it is less than 0.050 μm, it is preferable to prevent the aggregation of the release layer-forming composition and form a smooth release layer. In addition, in the present invention, when the main component is cation-curable polydimethylsiloxane (a), the composition contains cation-curable polydimethylsiloxane relative to 100 parts by mass of resin solids in the release layer. The oxane (a) is 50 parts by mass or more, for example more than 50 parts by mass, preferably more than 70 parts by mass, for example 80 parts by mass or more, and in one embodiment 90 parts by mass or more. In addition, it may be an aspect in which the cation-hardening type polydimethylsiloxane (a) is contained substantially in the solid resin content of the release layer as a whole.

The release layer forming composition of the present invention may contain a cation-curable resin (b) in addition to the cation-curable polydimethylsiloxane (a). At this time, (b) is a resin different from (a), and resin (b) is a resin without polydimethylsiloxane structure. Specifically, it can be roughly divided into two types: a cation-curable compound (b-1) not having a polysiloxane skeleton and a cyclosiloxane compound (b-2) having an alicyclic epoxy group.

In one aspect, the release layer forming composition further contains a cation-curable compound (b-1) not having a polysiloxane skeleton in addition to the cation-curable polydimethylsiloxane (a). Examples of the cation-curable compound (b-1) not having a silicone skeleton include polymers and monomers that have two or more cationic-curable functional groups in the molecule and do not have a silicone skeleton. Among them, a resin having two or more epoxy groups or alicyclic epoxy groups is preferable, and a resin having two or more alicyclic epoxy groups is more preferable. For example, the number of alicyclic epoxy groups may be 6 or less. By having 2 or more alicyclic epoxy groups, a crosslinking reaction can progress by cationic hardening reaction, and it can become the release layer excellent in solvent resistance. In addition, it also undergoes a cross-linking reaction with polydimethylsiloxane (a) contained in the release layer, so the release property is excellent, and the migration of polydimethylsiloxane (a) to the ceramic green body is suppressed. better.

In one aspect, the composition for forming the release layer contains both a cation-curable resin (b-1) without a polysiloxane skeleton and polydimethylsiloxane (a), so that a release layer with high smoothness can be realized. type layer. By making the release layer containing the compound (b-1), it is possible to fill in the fine asperities, extremely small foreign matters, protrusions derived from oligomers, etc. existing in the substrate film, and become an ultra-smooth release layer. In addition, since the hardening reaction is carried out by ultraviolet rays, it becomes a release layer with high smoothness. Although the explanation should not be limited to a specific theory, it can be speculated that in the drying step of the release layer forming composition during the release layer processing, the cation-curable resin (b-1) without the polysiloxane skeleton is uniformly made It is equal to polydimethylsiloxane (a), and then hardened after improving the planarity, a release layer with high smoothness can be obtained. In addition, since the polydimethylsiloxane (a) contained at the same time is segregated on the surface of the release layer in the drying step in the present invention, a release layer having excellent releasability can be obtained.

The cation-curable compound (b-1) not having a polysiloxane skeleton is preferably a low-molecular-weight monomer. Specifically, the number average molecular weight is preferably from 200 to less than 5,000, more preferably from 200 to less than 2,500, and more preferably from 200 to less than 1,000. If the number average molecular weight is 200 or more, the boiling point will not be lowered, and the cation-curable compound (b-1) is preferable 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. In addition, since it can exist in a liquid state with fluidity in the drying step, it is excellent in leveling property and is preferable as an ultra-smooth release layer.

As the cation-curable compound (b-1) not having a silicone skeleton, commercially available ones can be used suitably. Examples of compounds having an alicyclic epoxy group include Celloxide 2021P, Celloxide 2081, Epolead GT401, EHPE3150 manufactured by Daicel, HiREM-1 manufactured by Shikoku Kasei Co., Ltd., THI-DE, 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 Co., Ltd.

The cation-curable compound (b-1) not having a polysiloxane skeleton relative to 100 parts by mass of the total of the cation-curable polydimethylsiloxane (a) and the cation-curable compound (b-1) in the release layer ) content is preferably at least 80% by mass, more preferably at least 85% by mass, and most preferably at least 90% by mass. When the content of the cation-curable compound (b-1) is 80% by mass or more and it becomes the main component in the release layer, it is preferable because the release layer has a high crosslink density and is excellent in releasability. In addition, the content of cation-hardening polydimethylsiloxane (a) contained in the release layer can be reduced, and the composition derived from polydimethylsiloxane (a) can be inhibited from agglomerating on the release layer during the drying step. The surface of the layer is preferable because there is no risk of deterioration of planarity. The more the content of the cation-curing compound (b-1), the more smooth the release layer can be. However, in order to ensure the peelability by containing the cation-curing polydimethylsiloxane (a), the cation-curing type Compound (b-1) is preferably at most 99.9% by mass. In the present invention, a compound (cured product) derived from a cation-curable compound (b-1) not having a polysiloxane skeleton exists in the release layer in which the release layer-forming composition is cured. In this specification, the compound derived from (b-1) present in the release layer may also be simply referred to as a cation-curable compound (b-1) not having a polysiloxane skeleton.

When the release layer forming composition contains cation-curable polydimethylsiloxane (a) and cation-curable compound (b-1), since the release layer has a high crosslink density and excellent solvent resistance, it becomes A release layer having excellent peeling force is therefore preferable. In addition, if the cation-curable 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 cation-curable polydimethylsiloxane (a) within a predetermined range. . By increasing the film thickness of the release layer, it is preferable to fill the flaws and extremely small unevenness of the substrate film, and obtain a smooth release layer as described above.

When the release layer forming composition contains cation-curing polydimethylsiloxane (a) and cation-curing 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 0.1 μm or more and 0.5 μm or less. If it is 0.05 micrometer or more, it will become a smooth release layer, so it is preferable. If it is 1.0 μm or less, it is preferable to obtain a release film having excellent planarity 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 cyclic siloxane compounds (b-2) with alicyclic epoxy groups include those shown in the following structural formula (chemical formula 1) (in chemical formula 1, R ² is carbon number 1 to 4 alkyl). In addition, the cation-curable compound (b-2) having a cyclic siloxane skeleton preferably has at least two or more alicyclic epoxy groups. When there are two or more alicyclic epoxy groups, the cationic hardening reaction proceeds and it becomes a release layer with a high crosslink density, so it is preferable.

[chemical formula 1]

By using the cyclosiloxane compound (b-2) having an alicyclic epoxy group, an ultra-smooth release layer can be obtained for the same reason as when using the aforementioned cation-curing compound (b-1). So better. That is, it is possible to fill in fine unevenness, extremely small foreign matter, protrusions derived from oligomers, etc. present in the base film. In addition, since the hardening reaction is carried out by ultraviolet rays, the compound (b-2) and polydimethylsiloxane (a) can be uniformly averaged in the drying step of the release layer forming composition during the release layer processing. , and after hardening after improving the planarity, an ultra-smooth release layer can be obtained. Furthermore, in the present invention, since the polydimethylsiloxane (a) contained at the same time is segregated on the surface of the release layer during the drying step, a release layer having excellent peelability can be obtained.

Cyclic siloxane compound (b-2) with alicyclic epoxy group has good miscibility with cationic hardening polydimethylsiloxane (a), so it will be moderately mixed in the release layer , carry out cross-linking reaction with each other. Therefore, it is excellent in solvent resistance, and it is preferable since it becomes a release layer which shows excellent releasability. In addition, the cyclic siloxane compound (b-2) is preferable because it has a rigid molecular skeleton due to its cyclic siloxane structure, and has a high film hardness when cured. By increasing the film hardness, when the resin sheet (for example, a ceramic green sheet) is peeled off, the release layer becomes less likely to be deformed, and good peelability can be exhibited. Furthermore, the release layer becomes less likely to be scratched, and it is preferable that there is no fear of transfer of scratches on the release layer to a resin sheet (such as a ceramic green body).

When the release layer forming composition contains a cyclic siloxane compound (b-2), it is preferable because the adhesiveness of the release layer to the substrate film can be improved. If the adhesiveness of the release layer is improved, it is possible to suppress the occurrence of scratches in the conveying step, and it is preferable to avoid worrying about transfer of the release layer when the resin sheet is peeled off.

In one aspect, the cyclic siloxane compound (b-2) has two or more alicyclic epoxy groups in the molecule. If there are two or more alicyclic epoxy groups in the molecule, the cross-linking reaction can be carried out by cationic hardening reaction, and it becomes a release layer with excellent solvent resistance. In addition, it also undergoes a cross-linking reaction with the polydimethylsiloxane (a) contained in the release layer, so the release property is excellent, and it can inhibit the migration of the polydimethylsiloxane (a) to the ceramic green body. better. For example, the cyclic siloxane compound (b-2) has 6 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, Shin-Etsu Chemical Co., Ltd. X-40-2670, X-40-2678, etc. are mentioned.

With respect to 100 parts by mass of the total of cation-curing polydimethylsiloxane (a) and cyclic siloxane compound (b-2) in the release layer, the amount of 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% by mass or more and it becomes the main component in the release layer, it is preferable because the release layer has a high crosslink density and is excellent in releasability. In addition, the content of the cation-curable polydimethylsiloxane (a) contained in the release layer can be reduced, and in the present invention, the cation-curable polydimethylsiloxane (a) in the drying step can be suppressed It is better to condense on the surface of the release layer without worrying about deterioration of planarity. The more the content of the cyclic siloxane compound (b-2), the better the smoothness of the release layer. For example, in order to ensure the peelability by containing the cation-curing polydimethylsiloxane (a), the cyclic The siloxane compound (b-2) is preferably at most 99.9% by mass. In the present invention, the compound (cured product) derived from the cyclic siloxane compound (b-2) exists in the release layer in which the release layer forming composition is cured. In this specification, the compound derived from the cyclic siloxane compound (b-2) which exists in a release layer may be simply described as a cyclic siloxane compound (b-2).

When the release layer forming composition contains cationic hardening type polydimethylsiloxane (a) and cyclic siloxane type compound (b-2), the film thickness of the release layer is 0.05 μm or more to 1.0 μm It is preferably not more than μm, more preferably not less than 0.1 μm and not more than 0.5 μm. If it is 0.05 micrometer or more, since it becomes a smooth release layer, it is preferable. If it is 1.0 μm or less, warping can be avoided and a release film with excellent planarity can be obtained, so it is preferable.

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

In the present invention, it is necessary to carry out a cation hardening reaction in order to form a release layer. Therefore, it is preferable that the composition for forming a release layer contains an acid generator (c). In addition, a compound derived from an acid generator (c) may exist in the release layer. Here, the compound derived from the acid generator (c) present in the release layer may also be simply referred to as the acid generator (c). The acid generator is not particularly limited. General acid generators can be used, but by using a photoacid generator that generates acid under ultraviolet radiation, heat during processing can be suppressed, and it is preferable to form a release layer with excellent planarity. .

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

When using a salt formed of the aforementioned onium ion and a non-nucleophilic anion as the photoacid generator, the onium ion can be, for example, iodonium, perium, or ammonium. As the organic group of the onium ion, triaryl, diaryl (monoalkyl), monoaryl (dialkyl), and trialkyl can be used, and 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 preferably used. In addition, tetrakis(pentafluorophenyl)gallium ions, anions obtained by substituting several fluorine anions for perfluoroalkyl groups or organic groups, or other anion components may also be used.

The amount of the photoacid generator added is relative to the cation-curing polydimethylsiloxane (a) and the cation-curing compound (b-1) and/or the cyclic siloxane compound (b-1) in the release layer. 2) The total 100 mass parts 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% by mass or more, there is no need to worry about insufficient hardening due to an insufficient amount of generated acid. In addition, if it is 10% by mass or less, the amount of generated acid becomes appropriate, and the amount of migration of acid to the molded ceramic green body can be suppressed, so it is preferable.

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

In one aspect, the release layer-forming composition includes an organic solvent with an SP value (δ) of 14 to 17, and the release layer-forming composition is such that the SP value (δ) is 14 to 17. 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. An organic solvent having an SP value (δ) of 14 to 17 exhibits excellent solubility for the cation-curing polydimethylsiloxane (a). Therefore, in the drying step after the coating step, even if the organic solvent is dried to increase the concentration of the cation-curable polydimethylsiloxane (a) in the release layer forming composition, it can still be maintained in a uniformly dissolved state, It can be well averaged 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 need to worry about deterioration of smoothness caused by aggregation during drying. good. Details of the aforementioned organic solvent having an SP value (δ) of 14 or more and 17 or less will be described later.

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

When the release film obtained by the present invention is used to peel off the ceramic green body, the peeling force is preferably not less than 0.01 mN/mm and not more than 2.0 mN/mm. 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, it is preferable because there is no fear of the ceramic green body rising during transportation. If the peeling force is 2.0 mN/mm or less, there is no need to worry about damage to the green ceramic body during peeling.

The release film obtained by the present invention uses a highly planarized base film, so even if the thickness of the release layer is less than 1.0 μm, or even less than 0.5 μm, or even less than 0.3 μm, the release layer can still be made Surface smoothing. Therefore, the amount of solvent and resin used can be reduced, which is environmentally friendly, and a release film for ultra-thin ceramic green body molding can be produced at low cost.

(Manufacturing method of release film) Another embodiment of the present invention provides a method for manufacturing a release film for forming a resin sheet, which includes the following steps. The coating step is to apply a release layer forming composition on the aforementioned surface layer A of the polyester film having the surface layer A, the aforementioned 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 aforementioned polyester film coated with the release layer forming composition, and the aforementioned heat drying has a first drying step and a subsequent second drying step, The drying temperature T1 in the aforementioned first drying step is higher than the drying temperature T2 in the aforementioned second drying step; and, the photocuring step is to irradiate active energy rays after the aforementioned drying step to harden the release layer forming composition.

According to the production method of the present invention, by enhancing the first drying condition (enhanced drying) to prevent aggregation of the resin constituting the release layer, a release layer with high smoothness can be obtained. Furthermore, by setting the SP value of the solvent in the release layer-forming composition to a predetermined value, aggregation of the resin constituting the release layer can be prevented, and a release layer having high smoothness can be obtained. In this way, the first drying step in the present invention has predetermined conditions, and in one aspect, a release layer with high smoothness can be obtained by using a specific solvent.

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

According to the production method of the present invention, it was found that a high-smooth release layer can be realized by concentrating on the production conditions of the coating step. Specifically, by containing an organic solvent with an SP value (δ) of 14 to 17 in the composition for forming the release layer, the aggregation of the cation-hardening polydimethylsiloxane (a) can be suppressed, and an excellent release layer can be obtained. type layer. The SP value (δ) can be used to predict the solubility of a substance, and organic solvents with an SP value (δ) of 14 to 17 exhibit excellent solubility for cationic 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 cation-curable polydimethylsiloxane (a) in the release layer forming composition, it can still be maintained in a uniformly dissolved state. , without agglomeration and well-leveled, a smooth release layer can be obtained.

The content of the organic solvent having an 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, based on 100 parts by mass of the release layer forming composition good. If it is 10% by mass or more, the cation-curable polydimethylsiloxane (a) can be kept in a dissolved state for a long time during drying, so 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% by mass or less, for example, 65% by mass or less and less than 50% by mass relative to 100 parts by mass of the release layer forming composition.

The SP value (δ) in this specification is based on the Hidd Brown solubility parameter. The Hidden Brown solubility parameter can be experimentally calculated from the Hansen solubility parameters (Hansen Solubility Parameters, HSP value) in the manner of Equation 1. SP value (δ)＝((δ _d ) ² ＋(δ _p ) ² ＋(δ _h ) ² ) ^1/2・・・・・・(Formula 1) Here (δ _D ) is the dispersion force term, (δ _P ) is a polar term, (δ _H ) is a hydrogen bond term, and the way of thinking of decomposing the Hidd Brown solubility parameter into three components is the Hansen solubility parameter. In addition, it can also be calculated using computer software HSPiP (Hansen Solubility Parameters in Practice), etc. The values described in this manual are the HSP values recorded in the database in HSPiP ver4. value.

Examples of organic solvents with an SP value (δ) of 14 to 17 include n-hexane (δ: 14.9), n-heptane (δ: 15.3), n-octane (δ: 15.5), isopropyl ether (δ: 15.8) , 1,1-diethoxyethane (δ: 15.9), methylcyclohexane (δ: 16.0), cycloheptane (δ: 16.5), cyclohexane (δ: 16.8), etc.

The coating amount of the release layer forming composition is preferably not more than 10 g/m ² , more preferably not more than 8 g/m ² . If the coating amount is 10 g/ ^m2 or less, for example, when coating by gravure coating, the contact portion between the film and the gravure roll becomes less prone to turbulence, and a release layer with excellent smoothness can be obtained, so it is preferable.

In the present invention, the solvent contained in the release layer forming composition is preferably two or more types, at least one of which is a solvent with an SP value (δ) of 14 to 17 as described above, and at least one of which has a boiling point of 100 °C or higher is preferred. By adding a solvent with a boiling point above 100°C, bumping during drying can be prevented, the coating film can be evened out, and the smoothness of the coating film surface after drying can be improved. The added amount of the solvent is preferably about 10% by mass to 70% by mass relative to the entire release layer forming composition. Examples of solvents with a boiling point above 100°C 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 solution of the release layer forming composition is preferably filtered before coating. There is no particular limitation on the filtering method, and a known method can be used, preferably a surface type, depth type, or adsorption type cassette filter. The use of a cassette filter is preferable because it can be used when continuously feeding the coating liquid from the tank to the coating part, and can perform filtration with high productivity and high efficiency. The filtration accuracy of the filter is preferably used to remove more than 99% of objects with a size of 1 μm, and more preferably to filter out more than 99% of objects with a size of 0.5 μm. By using the filter with the above-mentioned filtration precision, foreign matter mixed in the coating solution forming the release layer can be removed, foreign matter adhering to the release film of the present invention can be reduced, and a release layer with excellent smoothness can be obtained. So better.

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

As a method of coating and drying the release layer-forming composition on the base film, well-known hot air drying, infrared heater, etc. are mentioned, and hot air drying with a fast drying speed is preferable. Drying is preferably carried out in a drying oven, and known drying ovens can be used without particular limitation. As for the method of drying oven, it can be either roll support or floating. If the roller support is used, the air volume can be adjusted in a wide range during drying, 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 the first drying step) and a decreasing rate drying step (hereinafter referred to as the second drying step) in the initial stage of drying. The two steps are preferably continuous in the order of the first drying step and the second drying step, which can be separated by dividing the area in the drying furnace. The first (initial) drying step can be dried using the first drying furnace. In the second (later) drying step, drying can be performed using a second drying oven.

The present inventors 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 range described later. Manufacturing under such conditions can shorten the constant-rate drying time in the first drying step and lengthen the decreasing-rate drying time in the second drying step, so that a release layer with excellent planarity can be obtained, so it is preferable.

Furthermore, the present inventors have 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 above 90°C and below 180°C, preferably above 100°C and below 150°C. It is preferable to shorten the constant rate drying time by increasing the temperature in the first drying oven to prevent aggregation of the cation-curable polydimethylsiloxane (a) contained in the release layer forming composition. The higher the temperature of the first drying oven, the shorter the constant-rate drying time is, so it is better, but 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 above 60°C and below 140°C, more preferably above 80°C and below 120°C. In the second drying step, it is preferable to increase the smoothness of the release layer by prolonging the drying time without roughening the surface of the release layer before photohardening.

For example, the constant-rate drying time in the first drying step is preferably shorter than the decreasing-rate drying time in the second drying step. Thereby, deterioration of planarity of the film can be prevented, furthermore, drying can be performed without roughening the surface of the release layer before photohardening, and the smoothness of the release layer can be improved.

The time after coating until entering the first drying oven is preferably from 0.1 second to 2.5 seconds, preferably from 0.1 second to 2.0 seconds, and the shorter the better. By shortening the time required to enter the first drying oven, the drying time in the first drying step can be shortened, the aggregation of cationic hardening 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 photocuring step of hardening the release layer forming composition by irradiating active energy rays after the drying step. In the photohardening step, the cationic hardening reaction of the dried release layer forming composition proceeds by irradiating active energy rays. The active energy ray to be used can use known techniques such as ultraviolet rays and electron beams, and it is preferable to use ultraviolet rays. The cumulative amount of light when using ultraviolet rays can be expressed as the product of illuminance and irradiation time. For example, it is preferably 10mJ/cm ² to 500mJ/cm ² . By setting it as more than the said minimum, since a release layer can fully harden, it is preferable. By setting it below the said upper limit, thermal damage to a film by the heat at the time of irradiation can be suppressed, and the smoothness of the release layer surface can be maintained, and it is preferable.

When irradiating active energy rays, it is preferable to hold the inner surface of the film with a backup roll. By providing a back roller, it is preferable to maintain a constant distance from the active energy ray source and to uniformly irradiate. In addition, it is preferable to irradiate the active energy ray while cooling the surface of the back roller to cool the film. By cooling, even when active energy rays are irradiated, the film is less likely to be 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 a resin sheet containing an inorganic compound.

(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 forming a resin sheet containing an inorganic compound. Examples of the inorganic compound include metal particles, metal oxides, minerals, and the like, for example, calcium carbonate, silica particles, alumina particles, barium titanate particles, and the like. Since the present invention has a high-smooth release layer, even if the resin sheet contains such inorganic compounds, it can suppress the defects that may be caused by the inorganic compounds (such as damage to the resin sheet, and the resin sheet becomes difficult to self-destruct). The problem of peeling of the release layer). The resin component forming the resin sheet can be appropriately selected according to the application. In one aspect, the resin sheet containing the inorganic compound is a ceramic green body. For example, a ceramic green body may contain barium titanate as an inorganic compound. In addition, the resin component may contain polyvinyl butyral resin, for example. In one aspect, the thickness of the resin sheet is not less than 0.2 μm and not more than 1.0 μm. For example, the present invention can provide a method for producing a release film for producing a resin sheet containing these inorganic compounds. In addition, the method for manufacturing a release film for forming a resin sheet in the present invention may also include: a step of forming a resin sheet with a thickness of not less than 0.2 μm and not more than 1.0 μm.

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

In one aspect, the release film of the present invention is a release film for manufacturing a ceramic green body, and is used to manufacture such a multilayer ceramic capacitor. For example, the method of manufacturing a ceramic green body that uses the release film for manufacturing a ceramic green body of the present invention to mold a ceramic green body can mold a ceramic green body having a thickness of not less than 0.2 μm and not more than 1.0 μm. More specifically, ceramic green bodies are produced, for example, as follows. First, the release film of the present invention is used as a carrier film, and the ceramic slurry for constituting the ceramic 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, the conductive layer for constituting the first internal electrode or the second internal electrode is printed. The matrix can be obtained by appropriately laminating and pressing ceramic green bodies, ceramic green bodies printed with a conductive layer constituting a first internal electrode, and ceramic green bodies printed with a conductive layer constituting a second internal electrode. laminated body. The mother laminated body is divided into plural pieces to produce a green ceramic element body. The ceramic body is obtained by firing the raw ceramic body. Thereafter, a 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 using examples, but the present invention is not limited to these examples at all. The characteristic values used in the present invention were evaluated using the following methods.

(release layer thickness) Resin-embed the cut release film, and perform ultra-thin sectioning with a super microtome. Thereafter, 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 to be evaluated correctly by cross-sectional observation, it is measured using a reflection spectroscopic film thickness meter (manufactured by Otsuka Electronics Co., Ltd., FE-3000) instead.

(Release layer weight) In this specification, the weight of the release layer per thickness of 1 μm 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 based on the composition formed from 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 cation-curing polydimethylsiloxane (a) is 5 parts by mass, the cation-curing polydimethylsiloxane contained in the release layer The weight of siloxane (a) is 0.01 g/m ² . In addition, the release layer weight ratio (mass %) is calculated with the total of the component (a) and the component (b) being 100 mass parts.

(Coating amount of 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 process was used.

(Time from coating to 1st drying oven) The value calculated from the film travel distance and processing speed from the coating section to the first drying furnace was used.

(area 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 area surface average roughness (Sa) is the average value of 5 measurements, and the maximum protrusion height (Sp) is the maximum value of the 5 measurement results after excluding the maximum and minimum values from 7 measurements. (measurement conditions) ・Measurement mode: WAVE mode ・Objective lens: 50 times ・0.5×Tube lens ・Measurement area 187μm×139μm (analysis conditions) ・Surface correction: 4 corrections ・Interpolation processing: full interpolation

(The number of protrusions with a height of 10 nm or more, the number of protrusions with a height of 5 nm or more) Particle analysis was performed using measurement data showing a central value among the measured values of the above-mentioned maximum protrusion height measured 7 times in total. Particle analysis was obtained under the following conditions using Vertscan R550H-M100 analysis software. Particle analysis is carried out by measuring the surface roughness of the above region, the maximum protrusion height, and the measured area of the same area, and calculating 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. As for the number of protrusions, the values converted in 1 mm ² conversion were used. (Particle analysis conditions) ・Surface calibration: 4 times calibration ・Storage processing: full interpolation ・Protrusion analysis ・Reference height: zero plane

(Peel force of ceramic sheet) The slurry composition I composed of the following materials was stirred and mixed for 10 minutes, and dispersed with zirconia beads with a diameter of 0.5 mm using a bead mill for 10 minutes to obtain a primary dispersion. Afterwards, 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 mm zirconia beads were dispersed twice for 10 minutes to obtain a ceramic slurry. (slurry composition I) Toluene 22.3 parts by mass Ethanol 18.3 parts by mass Barium titanate (average particle size 100nm) 57.5 parts by mass Hemojie Nuolu L-18 (manufactured by Kao Corporation) 1.9 parts by mass (Slurry Composition II) Toluene 39.6 parts by mass Ethanol 39.6 parts by mass Dioctyl phthalate 3.3 parts by mass Polyvinyl butyral (ESLEC 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, apply an applicator to the release surface of the obtained release film sample so that the dried slurry becomes 1.0 μm, and dry at 60°C for 1 minute to obtain a release film with a ceramic green body . After de-energizing the obtained release film with a ceramic green body with a de-energizer (manufactured by Keyence, SJ-F020), use a peeling tester (manufactured by Kyowa Interface Science Co., Ltd., VPA-3, load cell load 0.1N) to 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, stick double-sided adhesive tape (manufactured by Nitto Denko Co., Ltd., No. 535A) on the SUS (stainless steel) plate attached to the peeling tester, and place the double-sided adhesive tape on the ceramic green side on the double-sided adhesive tape In the following form, the release film is fixed, and the release film side is pulled to peel off. The average value of the peeling force at which the peeling distance was 20 mm to 70 mm among the obtained measured values was calculated, and this value was made into peeling force. The measurement was carried out 5 times in total, and the average value of the peeling force was used for evaluation. From the obtained value of peeling force, it judged by the following reference|standard. 〇: 0.1mN/mm or more to less than 1.0mN/mm ×: 1.0mN/mm or more

(Evaluation of pinholes in ceramic green body) Similar to the evaluation of peelability of the above-mentioned ceramic slurry, a ceramic green body with a thickness of 1 μm was molded on the release surface of the release film. Secondly, the release film is peeled off from the molded release film with the ceramic green body to obtain the ceramic green body. In the central region of the obtained ceramic green body in the film width direction, light was irradiated from the opposite side of the ceramic slurry coating surface in a range of 25 cm ² , and the occurrence of pinholes visible through light penetration was observed, and visual judgment was performed based on the following criteria. 〇: No pinholes occurred ×: One or more pinholes occurred

(Preparation of Polyethylene Terephthalate Granules (PET (I))) As an esterification reaction device, a three-stage complete mixing tank with a stirring device, a fractionator, a raw material charging port, and a product outlet is used. A continuous esterification reaction device. TPA (terephthalic acid) was set to 2 tons/hour, EG (ethylene glycol) was set to 2 moles per 1 mole of TPA, and antimony trioxide was set in such an amount that Sb atoms became 160 ppm with respect to the formed PET, These slurries were continuously supplied to the 1st esterification reaction tank of the esterification reaction apparatus, and it reacted at 255 degreeC 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 and supplied to the second esterification reaction tank, and in the second esterification reaction tank, the EG was supplied in an amount of 8% by mass relative to the resulting PET, and further, an EG solution containing magnesium acetate tetrahydrate in an amount of 65 ppm of Mg atoms relative to the resulting PET, and TMPA (phosphoric acid) containing 40 ppm of P atoms relative to the resulting 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 39MPa (400kg/cm ² ) 0.2% by mass of porous silica gel with an average particle size of 0.9 μm after pressure-treated average number of times of dispersion treatment of 5 paths, and an average particle size of 0.6 μm with 1 mass % of ammonium polyacrylic acid attached per unit of calcium carbonate 0.4% by mass of synthetic calcium carbonate was added as 10% EG slurry, 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 is continuously supplied to the three-stage continuous polycondensation reaction device for polycondensation, and 95% of the sintered stainless steel fiber with a cross-sectional diameter of 20 μm is used for filtration. Afterwards, carry out ultrafiltration and extrude into water, cut into fragments after cooling, obtain the PET fragment (hereinafter referred to as PET (I)) of inherent viscosity 0.60dl/g. The content of the slip agent in the PET chips was 0.6% by mass.

(Preparation of Polyethylene Terephthalate Granules (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 flakes, they were melted at 285°C, melted at 290°C by a separate extruder, and sintered filters with 95% stainless steel fibers with a cross-sectional diameter of 15 μm and 95% stainless steel particles with a cross-sectional diameter of 15 μm were passed through The sintered filter is used for 2-stage filtration, which is collected in the feed block, and PET (I) becomes the surface layer B (opposite to the side layer of the release surface), and PET (II) becomes the surface layer A (side layer of the release surface) ) to laminate, extrude (cast) at a speed of 45m/min to form a sheet, use the electrostatic bonding method to carry out static bonding and cooling on a casting drum at 30°C, and obtain an intrinsic viscosity of 0.59dl/g Unstretched polyethylene terephthalate sheet. The layer ratio was adjusted so that PET(I)/(II)=60% by mass/40% by mass was calculated based on 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 a speed difference between the rolls. Thereafter, it was guided to a tenter and stretched 4.2 times in the lateral direction at 140°C. Next, heat treatment is performed at 210° C. in a heat-fixing zone. Thereafter, a relaxation treatment of 2.3% was performed at 170° C. in the lateral 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) For 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 composition that contains particles in surface layer A and surface layer B. The Sa of the surface layer A of the multilayer film X2 is 24 nm, and the Sa of the surface layer B is 24 nm.

(cationically hardening polydimethylsiloxane (a)) (a)-1: UVPOLY215 (manufactured by Arakawa Chemical Industries, solid content 100%)

(cationically curable resin (b)) (b)-1: Celloxide 2021P (manufactured by Daicel, solid content 100%) (b)-2: X-40-2670 (manufactured by Shin-Etsu Chemical Co., Ltd., solid content 100%)

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

(Example 1) After passing the release layer forming composition 1 of the following composition through a filter capable of removing more than 99% of foreign matter of 0.5 μm or more, it was coated using a reverse gravure so that the coating amount became 5.0 g/m ² Apply on the surface layer A of the laminated 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 the first drying furnace temperature of 120°C and the second drying furnace temperature of 90°C. After the drying step, the cooling roll was irradiated with ultraviolet rays with a cumulative light intensity of 100 mJ/cm ² by an ultraviolet irradiation machine (manufactured by Heraeus, H bulb) 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. In this way, the obtained release film for resin sheet molding is a release film capable of producing, for example, a resin sheet having a thickness of 0.2 μm or more and 1.0 μm or less. In addition, the weight (mg/m ² ) of each component (a), (b) and (c) described in the table represents the content ratio per unit solid content (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 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 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) Except having changed the composition and manufacturing method of the release layer described in Table 1, the release film for resin sheet molding was obtained by the method similar to Example 1.

(Example 5) Except having used the release layer forming composition 2 of the following composition, the release film for resin sheet molding was obtained by the method similar to Example 1. (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 changing the n-heptane in the release layer forming composition to cyclohexane (SP value (δ): 16.8, (δ _D ): 16.8, (δ _P ): 0.0, (δ _H ) : 0.2), the release film for resin sheet molding was obtained by the method similar to 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 described in Table 1 were changed. At this time, it prepared so that the ratio of the organic solvent might become the same as that of the release layer forming composition 1.

(Example 9) Except having changed into the composition 3 for release layer formation of the following composition, the release film for resin sheet molding was obtained by the method similar to Example 1. (Composition 3 for release layer formation) 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) Except having changed the composition and manufacturing method of the release layer described in Table 1, the release film for resin sheet molding was obtained by the method similar to Example 1.

(Example 13) Except having used the release layer forming composition 4 of the following composition, the release film for resin sheet molding was obtained by the method similar to Example 1. (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) In addition to changing the n-heptane in the release layer forming composition to cyclohexane (SP value (δ): 16.8, (δ _D ): 16.8, (δ _P ): 0.0, (δ _H ) : 0.2), the release film for resin sheet molding was obtained by the method similar to 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 described in Table 1 were changed. At this time, the organic solvent ratio was prepared in the same manner as that of the release layer forming composition 3 .

(Example 17) Except having used the composition 5 for release layer formation of the following composition, the release film for ultrathin layer resin sheet molding was obtained by the method similar to Example 1. (Composition 5 for release layer formation) 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 the concentration of the solid content described in Table 1 was changed to the organic solvent ratio and prepared in the same manner as the release layer forming composition 5. .

(Example 19) Except having changed into the manufacturing method described in Table 1, the release film for resin sheet molding was obtained by the method similar to Example 17.

(Example 20) Except having changed into the release layer forming composition 6, the release film for ultrathin layer resin sheet molding was obtained by the method similar to Example 1. (Composition 6 for release layer formation) 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) In addition to changing the n-heptane in the release layer forming composition 5 to cyclohexane (SP value (δ): 16.8, (δ _D ): 16.8, (δ _P ): 0.0, (δ _H ): 0.2) Except, the release film for resin sheet molding was obtained by the method similar to Example 1.

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

(Comparative example 1) Except having changed into the release layer forming composition 7 of the following composition, the release film for ultrathin layer resin sheet molding was obtained by the method similar to Example 1. (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 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 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) Except having changed into the release layer forming composition 8 of the following composition, the release film for ultrathin layer resin sheet molding was obtained by the method similar to Example 1. (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 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 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) Except having changed into the release layer forming composition 9 of the following composition, the release film for ultrathin layer resin sheet molding was obtained by the method similar to Example 1. (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 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 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 forming an ultra-thin layer resin sheet was obtained in the same manner as in Example 10 except for coating on the laminated film X2.

[Table 1A] Release film Substrate film Release layer (a) Cationic hardening polydimethylsiloxane (b) Cationic 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) Cationic 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) Cationic 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]

[Form 2B]

[Table 2C]

Since Comparative Example 1 does not contain cation-curable polydimethylsiloxane (a), the peeling force of the ceramic sheet is large and peeling is impossible. In Comparative Example 2 to Comparative Example 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 to-be-released object. Furthermore, in Comparative Example 4, inorganic particles existed in the entire substrate, and the smoothness of the release film was remarkably poor, and breakage, pinholes, etc. of the green sheet occurred. [Industrial availability]

According to the present invention, by improving the smoothness and detachability of the release layer, a release film can be provided. Even an ultra-thin laminate with a thickness of less than 1 μm can still be molded into a resin sheet with few defects, so that there is no need to worry about it. Defects occur to manufacture resin sheets.

Claims (10)

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 release layer is provided on the surface layer A; 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 thickness of the aforementioned release layer is less than 0.050 μm; The amount of cation-curable polydimethylsiloxane (a) contained in the release layer-forming composition is 90% by mass or more; the surface roughness (Sa) of the release layer region is 2nm or less; 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 release film for forming a resin sheet as described in 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/mm ² or less. The release film for forming a resin sheet as described in claim 1 or 2, wherein the above-mentioned cation-curing polydimethylsiloxane (a) has at least one group selected from vinyl ether group, oxetanyl group, and epoxy group , Functional group of alicyclic epoxy group. The release film for forming a resin sheet according to claim 1 or 2, wherein the content of the cation-hardening polydimethylsiloxane (a) contained in the release layer is 90 mg/m ² or less. The release film for forming a resin sheet according to claim 1 or 2, wherein the release layer forming composition further contains a cation-curable compound (b-1) without a polysiloxane skeleton; The aforementioned cation-curing compound (b-1) has two or more alicyclic epoxy groups in the molecule; The content of the cation-curable compound (b-1) is 80% by mass or more relative to 100 parts by mass of the total of the cation-curable polydimethylsiloxane (a) and the cation-curable compound (b-1). The release film for forming a resin sheet 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 cyclic siloxane compound (b-2) is 80 parts by mass relative to the total of 100 parts by mass of the cation-curable polydimethylsiloxane (a) and the cyclic siloxane compound (b-2) %above. The release film for forming a resin sheet according to claim 1 or 2, wherein the release layer forming composition contains an organic solvent with an SP value (δ) of 14 to 17; The release layer forming composition contains the aforementioned organic solvent having an SP value (δ) of 14 to 17 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. The release film for forming a resin sheet as described in claim 1 or 2 is used to manufacture a resin sheet containing an inorganic compound. The release film for forming a resin sheet as described in claim 8, wherein the resin sheet containing the inorganic compound is a ceramic green body. The release film for forming a resin sheet as described in claim 1 or 2 is used to form a resin sheet with a thickness of not less than 0.2 μm and not more than 1.0 μm.