KR20230106723A - Mold release film for molding of resin sheet - Google Patents

Abstract

An object of the present invention is to provide a release film capable of forming an ultra-thin resin sheet, particularly an ultra-thin ceramic green sheet, without defects by using a release film having a release layer having particularly excellent smoothness and peelability.
A release film for molding a resin sheet having a polyester film as a base material and a release layer, wherein the polyester film has a surface layer A substantially free of inorganic particles, and the release layer is formed on the surface layer A. The release layer is a layer in which the release layer forming composition is cured, the release layer forming composition contains at least cationically cured polydimethylsiloxane (a), and the area surface average roughness (Sa) of the release layer is 2 nm or less, A release film for resin sheet molding, wherein the number of protrusions having a height of 10 nm or more existing on the surface of the release layer is 200 pieces/mm 2 or less.

Description

Release film for resin sheet molding {MOLD RELEASE FILM FOR MOLDING OF RESIN SHEET}

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

Conventionally, a release film in which a release layer is laminated on a polyester film as a base material is used as a process film for forming resin sheets such as adhesive sheets, cover films, polymer films, and optical lenses.

The release film is also used as a process film for molding ceramic green sheets requiring high smoothness, such as multilayer ceramic capacitors and ceramic substrates. In recent years, the thickness of the ceramic green sheet tends to be reduced with the miniaturization and increase in capacity of multilayer ceramic capacitors. The ceramic green sheet is formed by coating a slurry containing a ceramic component such as barium titanate and a binder resin onto a release film and drying it. A multilayer ceramic capacitor is manufactured by printing an electrode on a molded ceramic green sheet and peeling it from a release film, and then laminating, pressing, firing, or applying an external electrode to the obtained ceramic green sheet.

When a ceramic green sheet is molded on the surface of the release layer of a polyester film base material, minute protrusions on the surface of the release layer affect the molded ceramic green sheet, and defects such as cissing and pinholes tend to occur. had a problem. In recent years, further thinning of ceramic green sheets has progressed, and ceramic green sheets having a thickness of 1.0 μm or less, more specifically, 0.2 μm to 1.0 μm are required. Therefore, the demand regarding the smoothness of the surface of a mold release layer is getting higher. In addition, there has been a problem that minute protrusions and foreign matter on the release layer lead to deformation of the ceramic green sheet to be molded, making it easy to generate pinholes and sheet cracks during peeling.

In addition, as the thinning of the ceramic green sheet proceeds, the releasability of peeling the ceramic green sheet from the release film becomes more important. If the peeling force is large and non-uniform, damage is applied to the ceramic green sheet in the peeling process, resulting in sheet defects, non-uniform thickness, etc., resulting in problems such as pinholes and sheet cracks. Therefore, it is also required to peel the ceramic green sheet with a lower and uniform force. That is, in order to manufacture an ultra-thin resin sheet, especially a ceramic green sheet, without defects, a release film having extremely high smoothness and excellent peelability is required.

As a release film excellent in smoothness and peelability, the thing of patent literature described below is mentioned. For example, in Patent Document 1, a release film having a release layer using a radical curable resin as a main component is proposed. In patent document 2, the release film of the structure in which the smoothing layer and the release layer were laminated|stacked is proposed. In Patent Document 3, a release film having a release layer using a cation-curable epoxy resin as a main component is proposed. In Patent Document 4, a release film having a release layer using a cation-curable polydimethylsiloxane as a main component is proposed.

Japanese Patent No. 5492352 Japanese Patent Laid-Open No. 2015-164762 International Publication No. 2018/079337 Japanese Patent Laid-Open No. 2016-079349

However, in the release film of Patent Literature 1, since the release layer is provided with respect to the base film with insufficient smoothness, there is a problem that the smoothness of the release layer is insufficient. In addition, as a result of intensive studies, the inventors of the present invention have found that radical curing type resins suffer from poor curing due to oxygen inhibition, so that the surface of the release layer has poor solvent resistance, and is used during molding of ceramic green sheets or printing of internal electrodes. It was found that there is a problem that the release layer is eroded by the organic solvent and the peelability is deteriorated.

In the invention of Patent Literature 2, a thermosetting melamine resin is used for the smoothing coating layer and the release coating layer, and high heat is required to promote the curing reaction. Therefore, there exists a possibility that the planarity of a release film may be damaged by the heat at the time of processing. In addition, since a plurality of processes of the smoothing coating layer and the release coating layer are required, not only contamination of the release film with foreign substances may occur, but there is a risk that the release layer may be scratched, and the ceramic green sheet formed on the release layer may have foreign substances or There is a possibility that a flaw may be transferred and a problem may occur.

In Patent Literatures 3 and 4, in order to improve curing defects due to oxygen inhibition and planar defects due to processing heat, release layers using cation-curable resins are proposed, respectively. However, in the release film of Patent Literature 3, since the smoothness of the base film is insufficient, there is a problem that the smoothness of the surface of the release layer is poor. Moreover, in the release agent component disclosed in Patent Document 3, the reactivity was insufficient, the solvent resistance was poor, and the release property also had a problem.

In the release film of Patent Document 4, since it has a release layer using a liquid cation-curable polydimethylsiloxane resin as a main component, the resin aggregates on projections such as oligomers present on the surface of the base film and unevenness of the base film, resulting in flatness. There was a risk of problems. Moreover, the crosslinking density of the release layer was low, and there was a problem also in peelability.

The present invention is made against the background of these prior art problems. That is, it is possible to provide a release film having a release layer having particularly excellent smoothness and peelability, and also capable of forming an ultra-thin resin sheet, particularly an ultra-thin ceramic green sheet, without defects. to be

As a result of earnestly examining in order to solve the said subject, the present inventors found that the said objective could be achieved with the release film which has the following structure, and completed this invention.

That is, the present invention consists of the following configurations.

[1] A release film for molding a resin sheet having a polyester film as a base material and a release layer,

The polyester film has a surface layer A that does not substantially contain inorganic particles,

having the release layer on the surface layer A,

The release layer is a layer in which the release layer forming composition is cured,

The release layer forming composition includes a cation-curable polydimethylsiloxane (a),

The area surface average roughness (Sa) of the release layer is 2 nm or less,

The release film for resin sheet molding, wherein the number of protrusions having 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 projection height (Sp) of the release layer is 20 nm or less, and the sum of the number of projections having a height of 5 nm or more and less than 10 nm existing on the surface of the release layer and the number of projections with a height of 10 nm or more is 1500. /mm2 or less.

[3] In one embodiment, the cation-curable polydimethylsiloxane (a) has at least one functional group selected from a vinyl ether group, an oxetanyl group, an epoxy group, and an alicyclic epoxy group.

[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) having no silicone skeleton,

The cation-curable compound (b-1) has two or more alicyclic epoxy groups in the molecule, and the cation-curable compound ( The content of b-1) is 80% by mass or more.

[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) has two or more alicyclic epoxy groups in the molecule, and the cyclic siloxane compound ( The content of b-2) is 80% by mass or more.

[7] In one embodiment, the release layer forming composition includes an organic solvent having an SP value (δ) of 14 or more and 17 or less, and the release layer forming composition includes the organic solvent having an SP value (δ) of 14 or more and 17 or less. 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.

[8] In one embodiment, a release film for producing a resin sheet containing an inorganic compound is provided.

[9] In one embodiment, the resin sheet containing the inorganic compound is a ceramic green sheet.

[10] In one embodiment, a release film for molding a resin sheet having a thickness of 0.2 μm or more and 1.0 μm or less is provided.

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

Hereinafter, the present invention will be described in detail.

The present invention is a release film for resin sheet molding having a polyester film as a base material and a release layer,

The polyester film has a surface layer A that does not substantially contain inorganic particles,

having a release layer on the surface layer A,

The release layer is a layer in which the release layer forming composition is cured,

The release layer forming composition includes a cation-curable polydimethylsiloxane (a),

The area surface average roughness (Sa) of the release layer is 2 nm or less,

A release film for molding a resin sheet, wherein the number of protrusions having a height of 10 nm or more existing on the surface of the release layer is 200 pieces/mm 2 or less.

Since the present invention having such a configuration has excellent smoothness and peelability of the mold release layer, it is possible to provide a uniform thickness without defects with respect to a resin sheet having a thickness of, for example, 0.2 μm to 1.0 μm or less, and pin Defects such as holes can be suppressed.

In addition, the present invention can exhibit the following effects. In this invention, since the release layer is provided with respect to the base film with sufficient smoothness, the smoothness of a release layer is also securable. Furthermore, in the present invention, in the release layer, curing failure due to oxygen inhibition can be suppressed, and high crosslinking of the release layer can be exhibited. This invention exhibiting such an effect can improve the solvent resistance of the surface of a release layer, for example. By improving the solvent resistance of the surface of the release layer, it is possible to suppress the release layer from being eroded by the organic solvent used during molding of the ceramic green sheet or printing of the internal electrode, and thus it can have high peelability.

Moreover, if it is this invention, compared with the release layer which has a thermosetting melamine resin, for example, in order to accelerate a hardening reaction, high heat|fever is not required. Therefore, it can suppress that the planarity of a release film is damaged by the heat|fever at the time of processing. Further, in the production method of the present invention, by passing through the application step and the drying step according to the present invention, the aggregation of the release layer-forming composition can be suppressed, and a release film having a release layer having extremely high smoothness can be obtained. there is.

More specifically, a composition for forming a release layer containing a predetermined amount of cation-curable polydimethylsiloxane (a) is applied to the surface layer A of the base film that does not substantially contain inorganic particles, and cured to achieve an extremely high quality. A release layer having smoothness can be obtained.

In addition, by controlling the content of the cation-curable polydimethylsiloxane (a) in the release layer to a predetermined amount or less, against minute foreign matter and oligomer-derived microprotrusions present in the base film during processing of the release layer , It is possible to suppress aggregation of the cation-curable polydimethylsiloxane (a). Although it should not be construed as being limited to a specific theory, it is possible to prevent the component (a) from aggregating with respect to fine protrusions caused by disks by increasing the first drying temperature (by intensifying drying).

In addition, by inhibiting curing failure due to oxygen inhibition, improving the solvent resistance of the surface of the release layer, suppressing contamination of the release layer, and suppressing damage to the release layer, damage to the release target such as ceramic green sheet and the like during peeling , sheet deformation due to transfer of scratches, foreign matter, etc. can be prevented. As a result, it is possible to obtain a release layer having excellent smoothness, hardness, peelability, and antifouling properties with respect to the release layer.

In addition, during drying of the organic solvent contained in the release layer-forming composition, the cation-curable polydimethylsiloxane (a) becomes difficult to aggregate, resulting in a release layer having excellent smoothness. Details will be described later.

Moreover, this invention provides the manufacturing method of the release film for resin sheet molding which has the following process in another aspect.

An application step of applying a release layer forming composition on the surface layer A of a polyester film having a surface layer A,

The surface layer A is a layer that does not substantially contain inorganic particles,

An application step in which the release layer forming composition includes a cation-curable polydimethylsiloxane (a);

As a drying step of heating and drying the polyester film coated with the release layer forming composition,

The heat drying has a 1st drying process and then a 2nd drying process,

a drying step in which the drying temperature T1 in the first drying step is higher than the drying temperature T2 in the second drying step;

A photocuring step of curing the release layer-forming composition by irradiating active energy rays after the drying step.

In the production method according to the present invention, in particular, by setting the production conditions at the time of processing the release layer to a predetermined method, a release layer having high smoothness can be formed, for example, the amount of application of the composition for forming a release layer , controlling the organic solvent composition, drying time, drying temperature, and the like. By producing a release film under the conditions of the present invention, aggregation of the cation-curable polydimethylsiloxane (a) contained in the composition for forming a 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 as the substrate of the present invention is not particularly limited, and a film-molded polyester commonly used as a substrate for a release film can be used. Preferably, it is a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component, and examples thereof include polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, Polytrimethylene terephthalate or a copolymer mainly composed of constituents of these resins is more suitable, and among them, a polyester film formed of polyethylene terephthalate is particularly suitable. In polyethylene terephthalate, the repeating unit of ethylene terephthalate is preferably 90 mol% or more, more preferably 95 mol% or more, and other dicarboxylic acid components and diol components may be copolymerized in small amounts, but in terms of cost, terephthalic acid and ethylene glycol alone. In addition, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, and crystallizers may be added within a range that does not impair the effect of the film of the present invention. The polyester film is preferably a biaxially oriented polyester film for reasons such as high elastic modulus in both directions.

0.50-0.70 dl/g is preferable and, as for the intrinsic viscosity of the said polyester film, 0.52-0.62 dl/g is more preferable. When the intrinsic viscosity is 0.50 dl/g or more, breakage does not occur much in the stretching step, which is preferable. Conversely, when it is 0.70 dl/g or less, the cutting property at the time of cutting to a predetermined product width is good, and dimensional defects do not occur, which is preferable. Moreover, it is preferable to fully vacuum dry raw material pellets.

In addition, in this specification, when describing only as "polyester film", it means the polyester film which has (laminated) the surface layer A. Moreover, in this invention, the polyester film has the surface layer A which does not contain inorganic particles substantially, and has the said release layer on the surface layer A.

In addition, when there is mention in a specification, the polyester film which further has (laminated) the surface layer B may be simply called a "polyester film."

The manufacturing method of the polyester film in this invention is not specifically limited, A conventionally generally used method can be used. For example, it can be obtained by melting the polyester in an extruder, extruding it into a film form, cooling it with a rotating cooling drum to obtain an unstretched film, and stretching the unstretched film. As for the stretching, it is preferable that it is biaxial stretching in terms of mechanical properties and the like. The biaxially stretched film can be obtained by sequentially biaxially stretching a longitudinally or transversely uniaxially oriented film in the transverse or longitudinal direction, or by simultaneously biaxially stretching an unstretched film in the longitudinal and transverse directions. there is.

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 polyester. It is preferable to perform stretching 1 to 8 times, particularly 2 to 6 times in each of the vertical and horizontal directions.

The polyester film preferably has a thickness of 12 to 50 µm, more preferably 15 to 38 µm, and more preferably 19 µm to 33 µm. When the thickness of the film is 12 μm or more, there is no risk of deformation due to heat during production of the film, processing of the release layer, or molding of a ceramic green sheet, which is preferable. On the other hand, when the thickness of the film is 50 μm or less, the amount of the film discarded after use does not become extremely large, which is preferable in reducing the environmental load.

The polyester film may be a single layer or a multilayer of two or more layers. The polyester film has a surface layer A substantially free of inorganic particles. For example, a single layer of the surface layer A may be used, or a multilayer structure including the surface layer A and another layer, for example, a surface layer B described later may be used.

In the case of a laminated polyester film composed of two or more layers, it is preferable to have a surface layer B capable of containing particles or the like on the opposite side of the surface layer A that does not substantially contain inorganic particles. As for the layered configuration, if the layer on the side where the release layer is applied is called the surface layer A, the layer on the opposite side is called the surface layer B, and the layer other than these is called the layer C, the layer configuration in the thickness direction is release layer/A /B, or a laminated structure such as release layer /A/C/B is exemplified. Naturally, the layer C may have a plurality of layer configurations. Also, the surface layer B may not contain particles. In that case, it is preferable to provide a coating layer containing particles and a binder on the surface layer B in order to impart sliding properties for winding the film into a roll shape.

In the polyester film of the present invention, the surface layer A located on the surface to which the release layer is applied contains substantially no inorganic particles. In the present invention, since the surface layer A does not substantially contain inorganic particles, it can exhibit the following area surface average roughness.

In the present invention, the area surface average roughness (Sa) of the surface layer A refers to the area surface average roughness (Sa) on the surface on which the release layer is disposed, and the area surface average roughness (Sa) on the surface on which the release layer is disposed ( Sa) is 7 nm or less. When Sa is 7 nm or less, the release layer laminated on the surface layer A can also exhibit high smoothness, so that pinholes and the like are less likely to occur during molding of the ultra-thin ceramic green sheet laminated on the release layer. Furthermore, when forming a release layer, it can suppress aggregation of the release layer component to the protrusion on surface layer A, and it can prevent deterioration of the smoothness of the surface of a release layer.

The area surface average roughness (Sa) of the surface layer A is preferably as small as possible, and may be 0.1 nm or more. In one aspect, the area surface average roughness Sa of the surface layer A is 0.1 nm or more and 7 nm or less, for example, 0.5 nm or more and 5 nm or less, or 0.5 nm or more and 4 nm or less. By being within this range, the smoothness of the release layer can be increased, and generation of pinholes and the like can be suppressed during molding of the ultra-thin layer ceramic green sheets to be laminated. Furthermore, when forming a release layer, it can suppress aggregation of the release layer component to the protrusion on surface layer A, and it can prevent deterioration of the smoothness of the surface of a release layer.

In the present invention, "substantially free of inorganic particles" means a content that is 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit when inorganic elements are quantified by fluorescence X-ray analysis. do. This is because even if inorganic particles are not actively added to the film, contaminants derived from foreign substances and contaminants adhering to lines or equipment in the raw resin or film manufacturing process may be mixed in the film.

In the polyester film substrate in the present invention, the surface layer B may be provided on the surface opposite to the surface on which the release layer is disposed. The surface layer B preferably contains particles. By including the particles, the film is excellent in slipperiness and easy removal of air, and can have excellent conveyance and winding properties. In particular, it is preferable to include silica particles and/or calcium carbonate particles.

The amount of particles contained in the surface layer B is 1000 to 15000 ppm in total. At this time, the area surface average roughness Sa of the film of the surface layer B is, for example, 1 nm or more and 40 nm or less. More preferably, they are 5 nm or more and 35 nm or less. When the total amount of silica particles and/or calcium carbonate particles is 1000 ppm or more and Sa is 1 nm or more, when the film is rolled up into a roll, air can be uniformly released, the winding appearance is good, and the flatness is good. can do Due to this feature, when manufacturing an ultra-thin resin sheet, for example, a ceramic green sheet having a thickness of 0.2 μm or more and 1.0 μm or less, for example, wrinkles and misalignment of the wound ceramic green sheet can be prevented. Therefore, it is possible to provide a release film having excellent transportability, winding and storage properties.

In addition, when the total amount of silica particles and/or calcium carbonate particles is 15000 ppm or less and Sa is 40 nm or less, aggregation of particles that also function as a lubricant is unlikely to occur, and coarse protrusions (e.g., height Protrusions of 1 μm or more) do not occur, therefore, when manufacturing an ultra-thin layer resin sheet, such as a ceramic green sheet, generation of pinholes due to winding, for example, can be suppressed, and a resin sheet with stable quality can be provided. can do.

As the particles contained in the surface layer B, inactive inorganic particles and/or heat-resistant organic particles other than silica and/or calcium carbonate can be used. It is more preferable to use silica particles and/or calcium carbonate particles from the viewpoints of transparency and cost. Other inorganic particles that can be used include alumina-silica composite oxide particles, hydroxyapatite particles, and the like. Moreover, as heat-resistant organic particle|grains, crosslinked polyacryl type particle|grains, crosslinked polystyrene particle|grains, benzoguanamine type particle|grains, etc. are mentioned. Moreover, when using silica particles, porous colloidal silica is preferable. When using calcium carbonate particles, precipitated calcium carbonate subjected to surface treatment with a polyacrylic acid-based high molecular compound is preferable from the viewpoint of preventing the particles from falling off.

The average particle diameter of the particles added to the surface layer B is preferably 0.1 μm or more and 2.0 μm or less, and particularly preferably 0.5 μm or more and 1.0 μm or less. When the average particle diameter of the particles is 0.1 μm or more, the slipperiness of the release film is good and is preferable. In addition, when the average particle diameter is 2.0 μm or less, deformation of the surface layer A is suppressed, and uneven thickness of the ceramic green sheet and generation of pinholes can be suppressed.

The surface layer B may contain two or more types of particles of different materials. Moreover, you may contain the particle|grains of the same kind but different average particle diameters. Moreover, two or more types of different particle|grains may have different average particle diameters within the said range. By including two different types of particles, the irregularities formed in the surface layer B can be highly controlled, and both slipperiness and smoothness can be achieved, which is preferable.

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

It is preferable that the thickness ratio of the surface layer A which is a layer on the side where the release layer is provided is 20% or more and 50% or less of the total layer thickness of the base film. When it is 20% or more, it is difficult to receive the influence of particles included in the surface layer B or the like from the inside of the film, and the area surface average roughness Sa can satisfy the above range, which is preferable. When it is 50% or less of the thickness of all layers of the base film, the use ratio of the recycled raw material in the surface layer B by co-extrusion and the above-mentioned intermediate layer C can be increased, and the environmental load is reduced, which is preferable.

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

In addition, a coating layer may be provided on the film before stretching or after uniaxial stretching in the film forming step on the surface of the surface layer A and/or the surface layer B to improve the adhesion of a release layer or the like applied later or to prevent charging, etc. Corona treatment etc. can also be performed. When providing a coating layer on the surface layer A, it is preferable that the said coating layer does not contain particle|grains substantially.

(release layer)

In the present invention, the release layer is laminated on the surface layer A. In the present invention, the release layer is a layer in which the release layer-forming composition is cured, and the release layer and the release layer-forming composition contain at least cation-curable polydimethylsiloxane (a), and the area surface average roughness of the release layer (Sa ) is less than 2 nm,

The number of protrusions having a height of 10 nm or more existing on the surface of the release layer is 200 pieces/mm 2 or less.

By having such characteristics of the release layer, it is possible to suppress occurrence of pinholes in an ultra-thin resin sheet requiring high smoothness, for example, a ceramic green sheet, and a resin sheet having a uniform film thickness can be formed. .

More specifically, in the release layer, in the present invention, curing failure due to oxygen inhibition can be suppressed, and high crosslinking of the release layer can be exhibited. This invention exhibiting such an effect can improve the solvent resistance of the surface of a release layer, for example. By improving the solvent resistance of the surface of the release layer, it is possible to suppress the release layer from being eroded by the organic solvent used during molding of the ceramic green sheet or printing of the internal electrode, and thus it can have high peelability.

Further, according to the present invention, high heat of 130°C or higher is not required to promote the curing reaction. Therefore, it can suppress that the planarity of a release film is damaged by the heat|fever at the time of processing. In addition, the incorporation of foreign substances into the release film for resin sheet molding and the occurrence of scratches on the release layer can be suppressed, and the occurrence of sheet damage due to transfer of foreign substances and scratches to the release object such as ceramic green sheet can be suppressed. can

The area surface average roughness (Sa) of the release layer is 2 nm or less. Moreover, the number of protrusions having a height of 10 nm or more existing on the surface of the release layer is 200 pieces/mm 2 or less. The surface of the release layer of the release film has predetermined conditions such as the area surface average roughness (Sa) and the number of protrusions of 10 nm or more in order not to cause defects in the ceramic green sheet applied and formed thereon.

When the area surface average roughness (Sa) is 2 nm or less and the number of protrusions having a height of 10 nm or more is 200/mm2 or less, defects such as pinholes do not occur in the ceramic green sheet during molding, and the yield is good, which is preferable. do.

More preferably, the area surface average roughness (Sa) is 1.7 nm or less, for example, 1.6 nm or less, and may be 1.5 nm or less. In one aspect, the area surface average roughness (Sa) is 1.3 nm or less. Further, the area surface average roughness Sa may be 0.1 nm or more, or 0.2 nm or more.

On the other hand, in one aspect, the number of protrusions having a height of 10 nm or more is 180/mm 2 or less, for example, 170/mm 2 or less, and may be 160/mm 2 or less. In one aspect, the number of projections having a height of 10 nm or more may be 120/mm 2 or less, or 100/mm 2 or less. Moreover, the number of protrusions having a height of 10 nm or more may be 1/mm 2 or more, for example, 10/mm 2 or more.

When the number of protrusions having a height of 10 nm or more is within the above range, defects such as pinholes do not occur in the ceramic green sheet, and excellent releasability can be obtained in a well-balanced manner.

More preferably, the area surface average roughness (Sa) is 1.0 nm or less, and the number of protrusions having a height of 10 nm or more is 100 pieces/mm 2 or less.

The release layer having the area surface average roughness (Sa) and the number of protrusions according to the present invention can exhibit extremely excellent smoothness.

In one aspect, the maximum projection height (Sp) of the release layer is 20 nm or less. When the maximum protrusion height is within this range, defects of the ceramic green sheet can be further suppressed. More preferably, the maximum protrusion height (Sp) is 15 nm or less, and still more preferably 10 nm or less.

In one aspect, the sum of the number of protrusions having a height of 5 nm or more and less than 10 nm and the number of protrusions having a height of 10 nm or more existing on the surface of the release layer is 1500 pieces/mm 2 or less. When the sum of the number of projections with a height of 5 nm or more and less than 10 nm existing on the release layer and the number of projections with a height of 10 nm or more is 1500/mm2 or less, defects in the ceramic green sheet can be further suppressed, and the release layer has high smoothness. It is desirable to be able to obtain

More preferably, the total number of protrusions having a height of 5 nm or more and less than 10 nm and the number of protrusions having a height of 10 nm or more is 1000 pieces/mm 2 or less, for example, 500 pieces/mm 2 or less is still more preferable.

The release layer according to the release film for resin sheet molding of the present invention is a layer obtained by curing the release layer-forming composition, and the release layer-forming composition contains at least a cation-curable polydimethylsiloxane (a). Cation-curable polydimethylsiloxane (a), since a crosslinking reaction proceeds by a cation curing reaction, does not cause curing failure due to oxygen inhibition, and becomes a release layer excellent in solvent resistance. Therefore, there is no fear that the release layer will be eroded by organic solvents used during molding of the ceramic green sheet, printing of internal electrodes, etc., and a release layer with excellent release properties can be obtained.

Further, the inventors of the present invention found that, in a release layer containing cation-curable polydimethylsiloxane (a), the amount of cation-curable polydimethylsiloxane (a) is important for realizing a release layer having high smoothness.

The cation-curable polydimethylsiloxane (a) is preferably contained in the release layer at 90 mg/m2 or less, for example, 60 mg/m2 or less, 50 mg/m2 or less, and more preferably 40 mg/m2 or less. And, it is more preferable that it is 30 mg / m 2 or less. Further, for example, the amount of cation-curable polydimethylsiloxane (a) may be 20 mg/m 2 or less.

When the content of the cation-curable polydimethylsiloxane (a) in the release layer is 50 mg/m or less, it is possible to suppress aggregation of the polydimethylsiloxane (a) during the step of forming the release layer, for example, the drying step, There is no possibility of generating a large number of protrusions outside the scope of the present invention, and the effect of the present invention can be exhibited.

In one aspect, components other than the cation-curable polydimethylsiloxane (a) may be contained in the release layer and the release layer-forming composition. In this case as well, although it should not be judged based on a specific theory, in the present invention, it is possible for the polydimethylsiloxane (a) to segregate on the surface of the release layer during processing of the release layer, and the content is 50 If it is mg/m 2 or less, aggregation is difficult and a release layer having high smoothness can be formed.

The smaller the content of the polydimethylsiloxane (a) according to the present invention, the more difficult it is to aggregate. When the content of the polydimethylsiloxane (a) in the release layer is 0.1 mg/m 2 or more, the leveling property of the release layer is maintained, the coat appearance is excellent, and the release layer has high smoothness. layers can be obtained. Moreover, since peelability is also excellent when it is 0.1 mg/m<2> or more, it is preferable. For example, the content of polydimethylsiloxane (a) may be 0.5 mg/m 2 or more.

In the present invention, the release layer forming composition contains a cation-curable polydimethylsiloxane (a). Moreover, in the release layer in which the release layer forming composition was cured, a compound (cured product) derived from cation-curable polydimethylsiloxane (a) is present. In this specification, the compound derived from (a) present in the release layer may also be simply described as cation-curable polydimethylsiloxane (a).

In the present invention, the cation-curable polydimethylsiloxane (a) refers to polydimethylsiloxane having a cation-curable functional group. A cation-curable functional group is a reactive functional group which shows cation-curable property, and specifically, a vinyl ether group, an oxetanyl group, an epoxy group, and an alicyclic epoxy group are mentioned. Among them, those having at least one functional group selected from an oxetanyl group, an epoxy group, and an alicyclic epoxy group are preferred from the viewpoint of reactivity, and an alicyclic epoxy group is most preferred. By having such a functional group, a crosslinked structure is formed by a cation curing reaction, and since it becomes a release layer having excellent solvent resistance and excellent peelability, it is preferable.

The number of cation-curable functional groups that the cation-curable polydimethylsiloxane (a) has may be one or more. For example, by having two or more cation-curable functional groups, the cation-curing reaction proceeds more easily, and since it becomes a release layer with a high crosslinking density, it is preferable. The introduction position of the cation-curable functional group is not particularly limited, and it is common to have it on the side chain or terminal of polydimethylsiloxane. The structure of polydimethylsiloxane may be a linear structure or a branched structure, and even if it has a functional group other than a cation-curable functional group, it can be used without problems.

As the cation-curable polydimethylsiloxane (a), a commercially available one can be suitably used. Examples include Silicolith (registered trademark) UV POLY200, UV POLY201, UV POLY215, UV RCA200, UV RCA251 manufactured by Arakawa Chemical Industry Co., Ltd., X-62-7622, X-62-7629 manufactured by Shin-Etsu Chemical Industry Co., Ltd. , X-62-7660, KF-101, KF-105, X-22-343, X-22-169AS, X-22-169B, X-22-163, X-22-173BX, X-22-173DX , X-22-9002, Momentive Performance Materials, UV9440E, UV9430, etc. are mentioned.

It is preferable that it is 1000-500000, and, as for the weight average molecular weight of cation-curable polydimethylsiloxane (a), it is more preferable that it is 5000-100000. When the weight average molecular weight is 1000 or more, the cationic curing reaction proceeds easily and the peelability is excellent, so it is preferable. If it is 500000 or less, the viscosity does not become too high, the coatability is excellent, and since it becomes a mold release layer having high planarity, it is preferable.

In addition to the cation-curable polydimethylsiloxane (a), other resins may be contained in the release layer-forming composition of the present invention. In this case, the film thickness of the release layer can be made thin. In the present invention, since the release layer is provided on the surface layer A of the base film that does not substantially contain inorganic particles, even if the thickness of the release layer is thin, it can be set as a release layer having extremely high smoothness. Moreover, since the film thickness of a release layer is thin, hardening reaction advances easily, it can process at a higher speed, and a release layer can be economically obtained.

In addition, when the film thickness is thin, there is no fear that minute foreign substances present in the base film, the release processing step, etc. are introduced into the release layer. Therefore, there is no possibility that projections caused by foreign substances will occur 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 release layer obtained by curing a composition containing cation-curable polydimethylsiloxane (a) as a main component, the thickness of the release layer is preferably 0.001 μm or more and less than 0.050 μm. If it is 0.001 micrometer or more, it is excellent in releasability, so it is preferable. If it is less than 0.050 μm, aggregation of the release layer-forming composition can be prevented, and a smooth release layer is obtained, which is preferable.

Further, in the present invention, when the cation-curable polydimethylsiloxane (a) is the main component, the composition is 50 parts by mass or more of the cation-curable polydimethylsiloxane (a) with respect to 100 parts by mass of the resin solid content of the release layer. For example, more than 50 parts by mass, preferably 70 parts by mass or more, for example, 80 parts by mass or more, and in one aspect, 90 parts by mass or more. Moreover, the aspect in which the cation-curable polydimethylsiloxane (a) is contained in the whole resin solid content of a mold release layer may be sufficient substantially.

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) does not have a polydimethylsiloxane structure. Specifically, it is roughly divided into two types: a cation-curable compound (b-1) having no silicone backbone and a cyclic siloxane compound (b-2) having an alicyclic epoxy group.

In one aspect, the release layer forming composition contains, in addition to the cation-curable polydimethylsiloxane (a), a cation-curable compound (b-1) that does not have a silicone backbone. Examples of the cation-curable compound (b-1) having no silicone skeleton include polymers and monomers having two or more cation-curable functional groups in the molecule and having no silicone skeleton. Among them, resins having two or more epoxy groups or alicyclic epoxy groups are preferable, and those having two or more alicyclic epoxy groups are more preferable. For example, the number of alicyclic epoxy groups may be 6 or less.

By having two or more alicyclic epoxy groups, a crosslinking reaction proceeds by a cationic curing reaction, and it becomes a mold release layer excellent in solvent resistance. In addition, since a crosslinking reaction also proceeds with the polydimethylsiloxane (a) contained in the release layer at the same time, it is preferable because it has excellent peelability and suppresses the transfer of the polydimethylsiloxane (a) to the ceramic green sheet.

In one aspect, since the release layer forming composition contains both the cation-curable resin (b-1) having no silicone backbone and the polydimethylsiloxane (a), a release layer having high smoothness can be realized. By using the release layer containing the compound (b-1), it is possible to bury fine irregularities, extremely minute foreign matter, projections derived from oligomers, and the like existing in the base film, resulting in an ultra-smooth release layer. Moreover, since a hardening reaction advances by an ultraviolet-ray, it becomes a mold release layer with high smoothness. Although it should not be interpreted as being limited to a specific theory, in the drying step of the release layer forming composition at the time of release layer processing, it is believed that (b-1) and (a) are leveled uniformly and curing proceeds after flatness is increased. It can be guessed that a release layer having high smoothness can be obtained. In addition, since the polydimethylsiloxane (a) contained simultaneously is segregated on the surface of the release layer in the drying step in the present invention, a release layer excellent in peelability can be obtained.

The cation-curable compound (b-1) having no silicone backbone is preferably a low-molecular-weight monomer. Specifically, the number average molecular weight is preferably 200 or more and less than 5000, more preferably 200 or more and less than 2500, and still more preferably 200 or more and less than 1000. When the number average molecular weight is 200 or more, the boiling point is not lowered, and there is no risk of volatilization of the cation-curable compound (b-1) in the drying step of the release layer forming composition during release layer processing, which is preferable. If it is less than 5000, the crosslinking density of the release layer increases and the solvent resistance is excellent, so it is preferable. In addition, since it can exist in a liquid state with fluidity during the drying process, it has excellent leveling properties and becomes an ultra-smooth release layer, which is preferable.

As the cation-curable compound (b-1) having no silicone backbone, a commercially available one can be suitably used. Examples of the compound having an alicyclic epoxy group include Celoxide 2021P, Celloxide 2081, Eporide GT401, EHPE3150 manufactured by Daicel Co., Ltd., HiREM-1 manufactured by Shikoku Kasei, THI-DE, DE-102, and DE manufactured by ENEOS. -103 and the like. Examples of the resin having an epoxy group include DIC's EPICLON (registered trademark) 830, 840, 850, 1051-75M, N-665, N-670, N-690, N-673-80M, N-690-75M, Nagase Denacol (registered trademark) EX-611, EX-313, EX-321 by Chemtech Co., Ltd., etc. are mentioned.

The content of the cation-curable compound (b-1) not having a silicone skeleton is 80% by mass or more with respect to 100 parts by mass in total of the cation-curable polydimethylsiloxane (a) and the cation-curable compound (b-1) in the release layer. It is preferable, it is more preferable that it is 85 mass % or more, and it is still more preferable that it is 90 mass % or more.

It is preferable to make the content of the cation-curable compound (b-1) 80% by mass or more as a main component in the release layer, since a release layer having a high crosslinking density and excellent peelability is obtained. In addition, the content of the cation-curable polydimethylsiloxane (a) contained in the release layer can be reduced, and the aggregation of the composition derived from the polydimethylsiloxane (a) on the surface of the release layer in the drying step can be suppressed, resulting in deterioration in planarity. It is desirable that there is no risk of becoming The higher the content of the cation-curable compound (b-1), the higher the smoothness of the release layer. However, in order to contain the cation-curable polydimethylsiloxane (a) and ensure release properties, the cation-curable compound (b-1) is 99.9 mass. It is preferable that it is % or less.

In the present invention, in the release layer obtained by curing the release layer-forming composition, a compound (cured product) derived from the cation-curable compound (b-1) having no silicone skeleton is present. In this specification, the compound derived from (b-1) present in the release layer may also be simply described as a cation-curable compound (b-1) having no silicone backbone.

When the release layer forming composition contains the cation-curable polydimethylsiloxane (a) and the cation-curable compound (b-1), the release layer has a high crosslinking density, excellent solvent resistance, and a release layer having excellent peeling force, so it is preferable. do. Moreover, when the cation-curable compound (b-1) is contained, the film thickness of the release layer can be increased while keeping the content of the cation-curable polydimethylsiloxane (a) within a predetermined range, which is preferable. By increasing the film thickness of the release layer, scratches existing in the base film and minute irregularities can be buried, and a smooth release layer is obtained as described above, which is preferable.

When the release layer forming composition contains cation-curable polydimethylsiloxane (a) and cation-curable compound (b-1), the film thickness of the release layer is preferably 0.05 μm or more and 1.0 μm or less, and is 0.1 μm or more and 0.5 μm. It is more preferable that it is below. Since it becomes a smooth release layer as it is 0.05 micrometer or more, it is preferable. If it is 1.0 μm or less, curl does not occur and a release film excellent in planarity is obtained, so it is preferable.

In one aspect, the release layer forming composition may further have a cyclic siloxane compound (b-2) having an alicyclic epoxy group. Examples of the cyclic siloxane compound (b-2) having an alicyclic epoxy group include those represented by the following structural formula (Formula 1) (in Formula 1, R ² is an alkyl group having 1 to 4 carbon atoms). Further, 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 curing reaction proceeds to form a release layer having a high crosslinking density, which is preferable.

The use of the cyclic siloxane compound (b-2) having an alicyclic epoxy group is preferable because it results in an ultra-smooth mold release layer for the same reasons as the case of using the cation-curable compound (b-1). That is, it is possible to bury minute irregularities, extremely minute foreign matter, projections derived from oligomers, and the like existing in the base film. In addition, since the curing reaction proceeds by ultraviolet rays, the compound (b-2) and the polydimethylsiloxane (a) are uniformly leveled in the drying step of the release layer forming composition at the time of release layer processing, and the flatness is increased, and then curing begins. Since it progresses, an ultra-smooth release layer can be obtained. Further, in the present invention, since the polydimethylsiloxane (a) contained simultaneously is segregated on the surface of the release layer in the drying step, a release layer having excellent releasability can be obtained.

Since the cyclic siloxane compound (b-2) having an alicyclic epoxy group has good compatibility with the cation-curable polydimethylsiloxane (a), it is properly mixed in the mold release layer, and a crosslinking reaction proceeds with each other. Therefore, since it becomes a release layer which is excellent in solvent resistance and shows excellent peelability, it is preferable. Further, the cyclic siloxane compound (b-2) is preferable because it has a rigid molecular skeleton in view of having a cyclic siloxane structure and increases film hardness when cured. When the film hardness is increased, the mold release layer is less likely to be deformed when peeling the resin sheet, for example, a ceramic green sheet, and good peelability can be exhibited. Furthermore, it is preferable that the release layer is less likely to be scratched, and there is no risk of problems occurring due to the flaws of the release layer being transferred to a resin sheet, for example, a ceramic green sheet.

When the release layer forming composition contains the cyclic siloxane compound (b-2), the adhesion of the release layer to the base film is improved, so it is preferable. When the adhesiveness of the release layer is improved, occurrence of scratches in the conveyance step can be suppressed, and there is no fear that the release layer will be transferred during peeling of the resin sheet, which is preferable.

In one aspect, the cyclic siloxane compound (b-2) has two or more alicyclic epoxy groups in a molecule. By having two or more alicyclic epoxy groups in the molecule, a crosslinking reaction proceeds by a cationic curing reaction, resulting in a release layer having excellent solvent resistance. In addition, since a crosslinking reaction also proceeds with the polydimethylsiloxane (a) contained in the release layer at the same time, it is preferable because it has excellent peelability and suppresses the transfer of the polydimethylsiloxane (a) to the ceramic green sheet.

For example, the cyclic siloxane compound (b-2) has 6 or less alicyclic epoxy groups in its molecule.

As the cyclic siloxane 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.

The content of the cyclic siloxane compound (b-2) is preferably 80% by mass or more with respect to the total of 100 parts by mass of the cation-curable polydimethylsiloxane (a) and the cyclic siloxane compound (b-2) in the mold release layer. It is more preferable that it is mass % or more, and it is still more preferable that it is 90 mass % or more. It is preferable to make the content of the cyclic siloxane compound (b-2) 80% by mass or more as a main component in the release layer, since a release layer having a high crosslinking density and excellent peelability is obtained. In addition, the content of the cation-curable polydimethylsiloxane (a) contained in the release layer can be reduced, and in the present invention, the aggregation of the cation-curable polydimethylsiloxane (a) on the surface of the release layer can be suppressed in the drying step. There is no fear of deterioration of planarity, which is preferable. The higher the content of the cyclic siloxane compound (b-2), the higher the smoothness of the release layer. It is preferable that silver is 99.9 mass % or less.

In the present invention, a compound (cured product) derived from the cyclic siloxane compound (b-2) is present in the release layer obtained by curing the release layer-forming composition. In this specification, also about the compound derived from the cyclic siloxane compound (b-2) which exists in a mold release layer, it may only describe as a cyclic siloxane compound (b-2).

When the release layer forming composition contains the cation-curable polydimethylsiloxane (a) and the cyclic siloxane compound (b-2), the thickness of the release layer is preferably 0.05 μm or more and 1.0 μm or less, and is 0.1 μm or more and 0.5 μm. It is more preferable that it is below. Since it becomes a smooth release layer as it is 0.05 micrometer or more, it is preferable. If it is 1.0 μm or less, curl does not occur and a release film excellent in planarity is obtained, so it is preferable.

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

In the present invention, it is necessary to proceed with a cationic curing reaction to form the release layer. Therefore, it is preferable that the release layer forming composition contains an acid generator (c). Moreover, a compound derived from the 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, and a general one is used. However, using a photoacid generator that generates an acid under ultraviolet irradiation is preferable because the amount of heat during processing can be suppressed and a mold release layer with excellent flatness can be obtained.

As the photoacid generator, it is preferable to use a salt composed of an onium ion and a non-nucleophilic anion from the viewpoint of reactivity. In addition, organometallic complexes represented by iron arene complexes, carbocation salts represented by tropylium, or anthracene derivatives or phenols substituted with electron withdrawing groups, such as pentafluorophenols, may be used.

In the case of using a salt composed of the onium ion and a non-nucleophilic anion as a photoacid generator, examples of the onium ion include iodonium, sulfonium, and ammonium. As the organic group of the onium ion, triaryl, diaryl (monoalkyl), monoaryl (dialkyl), or trialkyl may be used, or benzophenone or 9-fluorene may be introduced, or other organic groups may be used. . As the non-nucleophilic anion, it is preferable to use hexafluorophosphorate, hexafluoroantimonate, hexafluoroborate, and tetra(pentafluorophenyl)borate. Further, tetra(pentafluorophenyl)gallium ions or anions obtained by substituting some of the fluorine anions with perfluoroalkyl groups or organic groups may be used, or other anion components may be used.

The addition amount of the photoacid generator is from 0.1 to 10 with respect to 100 parts by mass in total of the cation-curable polydimethylsiloxane (a), the cation-curable compound (b-1) and/or the cyclic siloxane compound (b-2) in the release layer. It is mass %, More preferably, it is 0.5-8 mass %. More preferably, it is 1-5 mass %. By setting it as 0.1 mass % or more, there is no possibility that the quantity of the acid to generate|occur|produces becomes insufficient and hardening becomes insufficient, and it is preferable. Moreover, setting it to 10% by mass or less is preferable because the amount of acid generated is appropriate and the amount of acid migrating to the ceramic green sheet to be molded can be suppressed.

In the present specification, the total of 100 parts by mass of the cation-curable polydimethylsiloxane (a), the cation-curable compound (b-1) and/or the cyclic siloxane compound (b-2) in the release layer is the cation-curable polydimethylsiloxane ( It means the total value of the solid content of a) and the solid content of cation-curable resin (b). In the aspect in which 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 solid content in the release layer.

In one aspect, the release layer-forming composition includes an organic solvent having an SP value (δ) of 14 or more and 17 or less, and the release layer-forming composition includes the organic solvent having an SP value (δ) of 14 or more and 17 or less as a release layer. It is contained in an amount of 10% by mass or more based on 100 parts by mass of the total weight of the forming composition.

Organic solvents having an SP value (?) of 14 to 17 exhibit excellent solubility in the cation-curable polydimethylsiloxane (a). Therefore, in the drying step after the application step, even if the concentration of (a) in the release layer forming composition increases due to the drying of the organic solvent, the uniformly dissolved state can be maintained, and the release layer is cleanly leveled without aggregation, and the release layer is smooth. can be obtained.

In addition, when the content is 10% by mass or more, the cation-curable polydimethylsiloxane (a) can remain dissolved for a long time during drying, so there is no fear of aggregation during drying and deterioration in smoothness, which is preferable.

Details of the organic solvent having an SP value (δ) of 14 or more and 17 or less are described later.

In this invention, you may add additives, such as an adhesion improving agent and an antistatic agent, etc. to a release layer, as long as it does not impair the effect of this invention. In addition, in order to improve adhesion to the substrate, it is also preferable to pre-treat the surface of the polyester film prior to providing the release coating layer, such as anchor coat, corona treatment, plasma treatment, or atmospheric plasma treatment.

The release film obtained by the present invention preferably has a peeling force of 0.01 mN/mm or more and 2.0 mN/mm or less when peeling the ceramic green sheet. More preferably, it is 0.05 mN/mm or more and 1.0 mN/mm or less. When the peeling force is 0.01 mN/mm or more, there is no fear of floating the ceramic green sheet during transport, which is preferable. If the peeling force is 2.0 mN/mm or less, it is preferable because there is no risk of damage to the ceramic green sheet during peeling.

Since the release film obtained by the present invention uses a highly flattened base film, the surface of the release layer can be smoothed even if the thickness of the release layer is 1.0 μm or less, more preferably 0.5 μm or less, or even 0.3 μm or less. can Therefore, the amount of solvent or resin used can be reduced, and an environmentally friendly and inexpensive release film for forming an ultra-thin layer ceramic green sheet can be created.

(Method of manufacturing release film)

In another embodiment, the present invention provides a method for manufacturing a release film for resin sheet molding comprising the following steps.

An application step of applying a release layer forming composition on the surface layer A of a polyester film having a surface layer A,

The surface layer A is a layer that does not substantially contain inorganic particles,

An application step in which the release layer forming composition includes a cation-curable polydimethylsiloxane (a);

As a drying step of heating and drying the polyester film coated with the release layer forming composition,

The heat drying has a 1st drying process and then a 2nd drying process,

a drying step in which the drying temperature T1 in the first drying step is higher than the drying temperature T2 in the second drying step;

A photocuring step of curing the release layer-forming composition by irradiating active energy rays after the drying step.

If it is the manufacturing method of this invention, the aggregation of the resin which comprises a release layer can be prevented by strengthening 1st drying conditions (by strengthening drying), and a release layer with high smoothness can be obtained.

In addition, 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.

Thus, in this invention, the mold release layer which has high smoothness can be obtained by the 1st drying process having predetermined conditions, and using a specific solvent in one aspect.

The method for producing a release film of the present invention includes a coating step of applying a release layer forming composition containing at least cation-curable polydimethylsiloxane (a) onto a surface layer A of a polyester film that does not substantially contain inorganic particles; It has a drying step of heat-drying the film after application, for example, using a drying furnace, and a photocuring step of curing using active energy rays after heating and drying in this order. In particular, it is preferable to employ a method in which the application step, the drying step, and the photocuring step are performed in this order.

According to the production method of the present invention, it was found that a release layer having high smoothness can be realized by devising the production conditions in the coating step. Specifically, by containing an organic solvent having an SP value (δ) of 14 to 17 in the release layer forming composition, aggregation of the cation-curable polydimethylsiloxane (a) can be suppressed, and an excellent release layer can be obtained. The SP value (δ) can be used to predict the solubility of a substance, and an organic solvent having an SP value (δ) of 14 to 17 exhibits excellent solubility in cation-curable polydimethylsiloxane (a). Therefore, in the drying step after the application step, even if the concentration of (a) in the release layer forming composition increases due to the drying of the organic solvent, the uniformly dissolved state can be maintained, and the release layer is cleanly leveled without aggregation, and the release layer is smooth. 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 mass% or more, and preferably 15 mass% or more with respect to 100 mass parts of the release layer forming composition. When it is 10% by mass or more, the cation-curable polydimethylsiloxane (a) can maintain a dissolved state for a long time during drying, so there is no fear of deterioration in smoothness due to aggregation during drying, which is preferable. 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, with respect to 100 parts by mass of the release layer forming composition, even if it is less than 50% by mass. do.

The SP value (δ) in this specification employs the Hildebrand solubility parameter. Hildebrand solubility parameters can be experimentally calculated as in Equation 1 from Hansen Solubility Parameters (HSP values).

SP value (δ) = ((δ _d ) ² + (δ _p ) ² + (δ _h ) ² ) ^1/2 . … (Equation 1)

Here, (δ _D ) is the dispersion force term, (δ _P ) is the polar term, (δ _H ) is the hydrogen bonding force term, and the concept of decomposing the Hildebrand solubility parameter into three components is the Hansen solubility parameter.

In addition, it can be calculated using computer software HSPiP (Hansen Solubility Parameters in Practice) or the like, and the values described in this specification are calculated as in Equation 1 using the HSP values described in the database in HSPiP ver4.0 value is being adopted.

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

It is preferable that it is 10 g/m<2> or less, and, as for the application amount of a release layer formation composition, it is more preferable that it is 8 g/m<2> or less. When the application amount is 10 g/m or less, for example, when applied by the gravure coating method, liquid disturbance is less likely to occur in the kissing portion between the film and the gravure roll, and a release layer with excellent smoothness is obtained, so it is preferable.

In the present invention, the number of solvents contained in the composition for forming a release layer is preferably two or more, at least one of which is a solvent having an SP value (δ) of 14 to 17 as described above, and at least one having a boiling point of 100 It is preferable that it is more than °C. By adding a solvent having a boiling point of 100°C or higher, bumping during drying can be prevented, the coating can be leveled, and smoothness of the surface of the coating after drying can be improved.

It is preferable to add about 10-70 mass % with respect to the whole release layer formation composition as the addition amount. Examples of the solvent having a boiling point of 100° C. or higher include toluene, xylene, normal octane, cyclohexanone, methyl isobutyl ketone, propylene glycol monomethyl ether, propylene glycol monopropyl ether, isobutyl acetate, normal butanol, and the like. there is.

In this invention, it is preferable to filter the coating liquid of a release layer formation composition before application. The filtration method is not particularly limited, and an existing method can be used, but it is preferable to use a surface type, depth type, or suction type cartridge filter. By using a cartridge-type filter, since it can be used when the coating liquid is continuously fed from the tank to the coating part, productivity is good and it can be filtered efficiently, so it is preferable. As for the filtration accuracy of the filter, it is preferable to use one that removes 99% or more of the filter having a size of 1 μm, more preferably one capable of filtering 99% or more of the filter having a size of 0.5 μm. By using the above filtering precision, foreign substances mixed in the coating solution forming the release layer can be removed, foreign substances adhering to the release film of the present invention can be reduced, and a release layer with excellent smoothness can be obtained, so it is preferable.

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

As a method of applying the release layer forming composition on a base film and drying it, well-known hot air drying, infrared heaters, etc. are mentioned, but hot air drying with a high drying speed is preferable. It is preferable to dry in a drying furnace, and an existing drying furnace may be used without particular limitation. Regarding the method of the drying furnace, it does not matter whether it is a roll support method or a floating method, but since the range in which the air volume during drying can be adjusted is wider in the roll support method, the air volume etc. can be adjusted according to the type of release layer. desirable.

The drying process is divided into two drying processes: a constant rate drying process (hereinafter referred to as a first drying process) and a reduced rate drying process (hereinafter referred to as a second drying process) at the initial stage of drying. can The two processes are preferably continuous in the order of the first drying process and the second drying process, and can be distinguished by zone division within the drying furnace, and the first (initial) drying process is the first drying process. 2 (late) drying process can be dried using the second drying furnace.

The present inventors found that it is important that the drying temperature T1 in the first drying step is higher than the drying temperature T2 in the second drying step, in order to improve the smoothness of the mold release layer. The temperature of the first drying furnace and the temperature of the second drying furnace are preferably within the ranges described later. By manufacturing under such conditions, the constant rate drying time in the first drying step is short, and the decreasing rate drying time in the second drying step can be lengthened, which is preferable because a mold release layer with excellent planarity can be obtained.

Further, the present inventors have found that it is important to increase the internal temperature of the first drying furnace and shorten the constant rate drying time.

More specifically, the drying temperature T1 is preferably 90°C or higher and 180°C or lower, and is preferably 100°C or higher and 150°C or lower. By raising the temperature in the first drying furnace and shortening the constant rate drying time, since aggregation of the cation-curable polydimethylsiloxane (a) contained in the release layer forming composition can be prevented, it is preferable. The higher the temperature of the first drying furnace, the shorter the constant-modulus drying time is, which is preferable. However, if it is too high, deterioration of flatness of the film due to heat occurs, so it is preferably 180°C or less. If it is 90 degreeC or more, drying ability becomes sufficient and it is preferable.

The temperature in the second drying furnace is preferably 60°C or higher and 140°C or lower, more preferably 80°C or higher and 120°C or lower. In the 2nd drying process, since it can dry without roughening the surface of the release layer before photocuring by making drying time slow, and the smoothness of a release layer increases, it is preferable.

For example, it is preferable that the constant rate drying time in the first drying step is shorter than the decreasing rate drying time in the second drying step. Thereby, deterioration of the flatness of a film is prevented, and it can dry without roughening the surface of the release layer before photocuring, and the smoothness of a release layer can be improved.

The time from application to entry into the first drying furnace is preferably 0.1 second or more and 2.5 seconds or less, preferably 0.1 second or more and 2.0 seconds or less, and shorter is preferable. By accelerating the time until entering the first drying furnace, the drying time in the first drying step can be shortened, suppressing aggregation of the cation-curable polydimethylsiloxane (a), and obtaining a release layer with excellent smoothness, which is preferable. do. The time required to enter the drying furnace can be calculated from the processing speed and the structure of the processing machine stand.

The production method of the present invention includes a photocuring step of curing the release layer forming composition by irradiating active energy rays after the drying step.

Photocuring step WHEREIN: The cation curing reaction of the release layer forming composition after drying advances by irradiating an active energy ray. As active energy rays to be used, existing techniques such as ultraviolet rays and electron beams can be used, and it is preferable to use ultraviolet rays. The cumulative amount of light when ultraviolet rays are used can be expressed as the product of the illuminance and the irradiation time. For example, it is preferable that it is 10-500 mJ/cm<2>. By setting it as more than the said lower limit, since a mold release layer can fully be hardened, it is preferable. Since heat damage to the film by the heat|fever at the time of irradiation can be suppressed and smoothness of the surface of a release layer can be maintained by carrying out below the said upper limit, it is preferable.

When irradiating active energy rays, it is preferable to hold the back side of the film with a backup roll. Since the distance with an active energy source can be kept constant by providing a back-up roll, it can irradiate uniformly, and it is preferable. Moreover, it is preferable to irradiate an active energy ray, cooling the back-up roll surface and cooling a film. Cooling is preferable because even when active energy rays are irradiated, the film is hardly damaged by heat and the smoothness of the surface of the release layer can be maintained.

In one aspect, the manufacturing method of the present invention provides a method for manufacturing 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 sheet containing resin. In one aspect, the release film of the present invention is a release film for molding a resin sheet containing an inorganic compound. Examples of the inorganic compound include metal particles, metal oxides, minerals, and the like, and examples thereof include calcium carbonate, silica particles, aluminum particles, and barium titanate particles. Since the present invention has a release layer having high smoothness, even in an embodiment in which these inorganic compounds are included in the resin sheet, defects that can be attributed to the inorganic compound, such as breakage of the resin sheet and peeling of the resin sheet from the release layer problems can be suppressed.

The resin component forming the resin sheet can be appropriately selected according to the use. In one aspect, the resin sheet containing the inorganic compound is a ceramic green sheet. For example, the ceramic green sheet may contain barium titanate as an inorganic compound. Moreover, as a resin component, a polyvinyl butyral-type resin can be included, for example.

In one aspect, the resin sheet has a thickness of 0.2 μm or more and 1.0 μm or less.

For example, the present invention can provide a method for manufacturing a release film for manufacturing a resin sheet containing such an inorganic compound. Moreover, the manufacturing method of the release film for resin sheet molding in this invention may also include the process of shape|molding the resin sheet whose thickness is 0.2 micrometer or more and 1.0 micrometer or less.

(Ceramic Green Sheet and Ceramic Condenser)

In general, a multilayer ceramic capacitor has a rectangular parallelepiped ceramic body. Inside the ceramic body, first internal electrodes and second internal electrodes are alternately provided 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 surface. The first internal electrode is electrically connected to the first external electrode in the first cross section. The second internal electrode is exposed on the second end face 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 in the second cross section.

In one aspect, the release film of the present invention is a release film for manufacturing a ceramic green sheet, and is used to manufacture such a multilayer ceramic capacitor.

For example, in the method of manufacturing a ceramic green sheet in which the ceramic green sheet is molded using the release film for manufacturing a ceramic green sheet of the present invention, a ceramic green sheet having a thickness of 0.2 μm or more and 1.0 μm or less can be formed.

More specifically, for example, a ceramic green sheet is manufactured as follows. First, the release film of the present invention is used as a carrier film, and a ceramic slurry for constituting a ceramic body is applied and dried. The ceramic green sheet has a thickness of 0.2 to 1.0 µm and is required to be ultra-thin. A conductive layer for constituting the first or second internal electrode is printed on the applied and dried ceramic green sheet. A mother laminate is obtained by appropriately stacking ceramic green sheets, ceramic green sheets printed with conductive layers for constituting first internal electrodes, and printed ceramic green sheets with conductive layers for constituting second internal electrodes, and pressing them. . The mother laminate is divided into a plurality of parts to produce a raw ceramic body. A ceramic body is obtained by firing the bioceramic body. After that, the multilayer ceramic capacitor can be completed by forming first and second external electrodes.

Example

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

(release layer thickness)

The cut release film was resin-embedded and ultra-thin sectioned using an ultramicrotome. Then, cross-sectional observation was performed using JEM2100 transmission electron microscope made by JEOL, and the film thickness of the mold release layer was measured from the observed TEM image. When the thickness was too thin and could not be accurately evaluated by cross-sectional observation, it was measured using a reflection spectrophotometer (FE-3000, manufactured by Otsuka Electronics Co., Ltd.).

(weight of release layer)

In this specification, the value of the weight calculated assuming that the weight per 1 μm of the release layer thickness is 1 g/m 2 is employed. For example, when the thickness of the release layer measured by the above 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 the blending ratio of each component contained in the release layer forming composition. A value calculated from the total weight of the release layer was employed. For example, when the release layer thickness is 0.2 µm and the weight ratio of the release layer of the cation-curable polydimethylsiloxane (a) is 5 parts by mass, the weight of (a) contained in the release layer is 0.01 g/m 2 . In addition, the weight ratio (mass %) of the release layer was calculated by taking the total of the component (a) and the component (b) as 100 parts by mass.

(Application Amount of Release Layer Forming Composition)

The value calculated from the liquid consumption weight and processing area of the release layer forming composition used in the application step was adopted.

(Time from application to first drying furnace)

The value calculated from the travel distance of the film from the application part to the first drying furnace and the processing speed was employed.

(area surface average roughness Sa, maximum protrusion height Sp)

It was measured under the following conditions using a non-contact surface shape measurement system (VertScan R550H-M100). The area average surface roughness (Sa) was the average value of 5 measurements, and the maximum protrusion height (Sp) was measured 7 times and the largest value in the 5 measurement results excluding the maximum and minimum values was adopted.

(Measuring conditions)

・Measurement mode: WAVE mode

Objective lens: 50x

・0.5×Tube lens

・Measurement area 187㎛×139㎛

(analysis condition)

Face correction: 4th correction

・Interpolation processing: complete interpolation

(Number of protrusions with a height of 10 nm or more, number of protrusions with a height of 5 nm or more)

Particle analysis was performed using measurement data representing the central value among the seven measurements of the maximum protrusion height. Particle analysis was obtained under the following conditions using analysis software of Vertscan R550H-M100. Particle analysis was performed on the same area as the area surface average roughness and maximum protrusion height measurement, and the number of protrusions having the highest peak of 10 nm or more or 5 nm or more was calculated. The number of protrusions adopted the value converted in terms of 1 mm 2 .

(Particle analysis conditions)

Face correction: 4th correction

Interpolation processing: full interpolation

･Protrusion analysis

Reference height: zero plane

(Ceramic Green Sheet Peeling Force)

Slurry composition I consisting of the following materials was stirred and mixed for 10 minutes, and dispersed for 10 minutes with zirconia beads having a diameter of 0.5 mm using a bead mill to obtain a primary dispersion. Thereafter, slurry composition II composed of the following materials was added to the primary dispersion in a ratio of (slurry composition I): (slurry composition II) = 3.4: 1.0, and the mixture was mixed with zirconia beads having a diameter of 0.5 mm using a bead mill for 10 minutes. Secondary dispersion was performed to obtain a ceramic slurry.

(Slurry composition I)

toluene 22.3 parts by mass

ethanol 18.3 parts by mass

Barium titanate (average particle diameter 100 nm) 57.5 parts by mass

Homogenol L-18 (manufactured by Gao) 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 (S-REC BM-S manufactured by Sekisui Chemical Co., Ltd.) 16.3 parts by mass

1-Ethyl-3-methylimidazolium ethyl sulfate 0.5 parts by mass

Subsequently, the resulting slurry was applied to the release surface of the obtained release film sample using an applicator to a thickness of 1.0 μm, and dried at 60° C. for 1 minute to obtain a release film with ceramic green sheet. The resulting release film with ceramic green sheet was static neutralized using a static charge eliminator (SJ-F020, manufactured by Keyence Corporation), and then peeled off using a peel tester (VPA-3, manufactured by Kyowa Science and Technology Co., Ltd., load cell load: 0.1 N). It peeled at an angle of 90 degrees, a peeling temperature of 25°C, and a peeling speed of 10 m/min. In the peeling direction, a double-sided adhesive tape (No.535A manufactured by Nitto Denko Co., Ltd.) is affixed on the SUS plate attached to the peel tester, and the ceramic green sheet side is adhered to the double-sided tape on top of the release film. was fixed, and it peeled in the form which pulled the release film side. Among the measured values obtained, an average value of the peeling force at a peeling distance of 20 mm to 70 mm was calculated, and the value was used as the peeling force. The measurement was performed 5 times in total, and evaluation was performed using the value of the average value of the peel force. From the numerical value of the obtained peeling force, it was determined according to the following criteria.

○: 0.1 mN/mm or more, less than 1.0 mN/mm

×: 1.0 mN/mm or more

(Pin hole evaluation of ceramic green sheet)

A ceramic green sheet having a thickness of 1 μm was molded on the release surface of the release film in the same manner as the evaluation of the release property of the ceramic slurry. Then, the release film was peeled from the molded release film with ceramic green sheet to obtain a ceramic green sheet. The obtained ceramic green sheet was exposed to light from the opposite side of the ceramic slurry coated surface in the range of 25 cm 2 in the central region in the film width direction, and the occurrence of pinholes through which light was transmitted was observed, and visually determined according to the following criteria.

○: No occurrence of pinholes

×: One or more occurrences of pinholes

(Preparation of polyethylene terephthalate pellets (PET (I)))

As the esterification reaction apparatus, a continuous esterification reaction apparatus consisting of a three-stage complete mixing tank having a stirrer, a condenser, a raw material inlet, and a product outlet was used. TPA (terephthalic acid) is 2 tons/hour, EG (ethylene glycol) is 2 moles per 1 mole of TPA, antimony trioxide is used in an amount such that the Sb atom is 160 ppm with respect to the produced PET, and these slurries are prepared in an esterification reactor was continuously supplied to the first esterification reaction tube, and reacted at 255°C with an average residence time of 4 hours under normal pressure. Then, the reaction product in the first esterification reaction tube is continuously taken out of the system, supplied to the second esterification reaction tube, and distilled off from the first esterification reaction tube in the second esterification reaction tube. 8% by mass of EG to be produced is supplied to the product PET, and further, an EG solution containing magnesium acetate tetrahydrate in an amount such that the Mg atom is 65 ppm with respect to the product PET, and the amount of P atom is 40 ppm with respect to the product PET An EG solution containing TMPA (trimethyl phosphate) was added and reacted at 260° C. with an average residence time of 1 hour under normal pressure. Then, the reaction product in the second esterification reaction tube was continuously taken out of the system and supplied to the third esterification reaction tube, and was averaged at a pressure of 39 MPa (400 kg/cm 2 ) using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.). 0.2% by mass of porous colloidal silica having an average particle size of 0.9 μm subjected to dispersion treatment for 5 passes of treatment, and 0.4% by mass of synthetic calcium carbonate having an average particle size of 0.6 μm in which 1 mass% of ammonium salt of polyacrylic acid is adhered per calcium carbonate. , each was added as a 10% EG slurry, and reacted at 260°C with an average residence time of 0.5 hours at normal pressure. The esterification reaction product generated in the third esterification reaction tube is continuously supplied to a three-stage continuous polycondensation reactor to undergo polycondensation, and 95% of the esterification reaction product is filtered through a filter made of sintered stainless steel fibers having a cut diameter of 20 μm. After performing, ultrafiltration was performed, extruded in water, cooled, and then cut into chips to obtain PET chips having an intrinsic viscosity of 0.60 dl/g (hereinafter abbreviated as PET (I)). The lubricant content in the PET chip was 0.6% by mass.

(Preparation of polyethylene terephthalate pellets (PET (II)))

Meanwhile, in the production of the PET (I) chip, a PET chip having an intrinsic viscosity of 0.62 dl/g and containing no particles such as calcium carbonate and silica was obtained (hereinafter abbreviated as PET (II)).

(Preparation of laminated film X1)

After drying, these PET chips were melted at 285°C, melted at 290°C by a separate melting extruder, and a filter obtained by sintering stainless steel fibers having a 95% cut diameter of 15 µm and a filter having a 95% cut diameter of 15 µm Filters made of sintered stainless steel particles are filtered in two stages, joined in a feed block, and PET (I) is used as the surface layer B (anti-release surface side layer) and PET (II) is used as surface layer A (release surface side layer). ), extruded (casting) at a speed of 45 m/min into a sheet form, electrostatically adhered and cooled on a casting drum at 30° C. by an electrostatic adhesion method, and unstretched polyethylene having an intrinsic viscosity of 0.59 dl/g. A terephthalate sheet was obtained. The layer ratio was adjusted so that PET (I) / (II) = 60% by mass / 40% by mass by calculating the discharge amount of each extruder. Next, after heating this unstretched sheet with an infrared heater, it was stretched 3.5 times in the machine direction by a speed difference between rolls at a roll temperature of 80°C. After that, it was guided by a tenter and stretched 4.2 times in the transverse direction at 140°C. Subsequently, heat treatment was performed at 210°C in a heat setting zone. Thereafter, a 2.3% relaxation treatment was performed at 170°C in the transverse direction to obtain a biaxially stretched polyethylene terephthalate film X1 having a thickness of 31 µm. Sa of the surface layer A of the obtained film X1 was 1 nm, and Sa of the surface layer B was 28 nm.

(Preparation of laminated film X2)

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

(Cation-curable polydimethylsiloxane (a))

(a)-1: UV POLY215 (manufactured by Arakawa Chemical Industry, 100% solid content)

(cationic curable resin (b))

(b)-1: Celloxide 2021P (manufactured by Daicel Co., Ltd., 100% solid content)

(b)-2: X-40-2670 (manufactured by Shin-Etsu Chemical Industry, 100% solid content)

(Acid generator (c))

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

(Example 1)

After passing the release layer forming composition 1 of the following composition on the surface layer A of the laminated film X1 through a filter capable of removing 99% or more of foreign matter of 0.5 μm or more, it is coated using reverse gravure so that the coating amount is 5.0 g / m 2 did. Then, the processing speed was adjusted so that it might enter the 1st drying furnace after 0.5 second, and it heat-dried continuously at the temperature of 120 degreeC of the 1st drying furnace, and 90 degreeC of the 2nd drying furnace. After the drying step, a release film for resin sheet molding was obtained by curing the release layer by irradiating ultraviolet light with a cumulative light amount of 100 mJ/cm 2 on a cooling roll using an ultraviolet irradiator (H valve manufactured by Heraeus). Moreover, as a result of performing smoothness, peelability, and pinhole evaluation of the obtained release film, as shown in Table 1, favorable results were obtained.

Thus, the obtained release film for resin sheet molding was a release film capable of producing a resin sheet having a thickness of 0.2 μm or more and 1.0 μm or less, for example.

In addition, the weight (mg/m 2 ) of each component (a), (b), and (c) described in the table indicates the content ratio per solid content (weight of each component relative to the total weight of the release layer).

(Release Layer Forming Composition 1)

methyl ethyl ketone 24.000 parts by mass

(SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1)

toluene 24.000 parts by mass

(SP value (δ): 18.2, (δ _D ): 18.0, (δ _P ): 1.4, (δ _H ): 2.0)

normal 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

(Examples 2 to 4)

A release film for resin sheet molding was obtained in the same manner as in Example 1, except that the composition and production method of the release layer described in Table 1 were changed.

(Example 5)

A release film for resin sheet molding was obtained in the same manner as in Example 1 except that the release layer forming composition 2 having the following composition was used.

(Release layer forming composition 2)

methyl ethyl ketone 38.400 parts by mass

(SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1)

toluene 38.400 parts by mass

(SP value (δ): 18.2, (δ _D ): 18.0, (δ _P ): 1.4, (δ _H ): 2.0)

normal heptane 19.200 parts by mass

(SP value (δ): 15.3, (δ _D ): 15.3, (δ _P ): 0.0, (δ _H ): 0.0)

(a)-1 0.196 parts by mass

(b)-1 3.726 parts by mass

(c)-1 0.078 parts by mass

(Example 6)

Normal heptane in the release layer forming composition was changed to cyclohexane (SP value (δ): 16.8, (δ _D ): 16.8, (δ _P ): 0.0, (δ _H ): 0.2), and Example 2 and A release film for resin sheet molding was obtained in the same manner.

(Examples 7 and 8)

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

(Example 9)

A release film for resin sheet molding was obtained in the same manner as in Example 1, except that the following composition was changed to composition 3 for forming a release layer.

(Composition 3 for Forming Release Layer)

methyl ethyl ketone 24.000 parts by mass

(SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1)

toluene 24.000 parts by mass

(SP value (δ): 18.2, (δ _D ): 18.0, (δ _P ): 1.4, (δ _H ): 2.0)

normal 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

(Examples 10 to 12)

A release film for resin sheet molding was obtained in the same manner as in Example 1, except that the composition and production method of the release layer described in Table 1 were changed.

(Example 13)

A release film for resin sheet molding was obtained in the same manner as in Example 1 except that the release layer forming composition 4 having the following composition was used.

(Release layer forming composition 4)

methyl ethyl ketone 38.400 parts by mass

(SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1)

toluene 38.400 parts by mass

(SP value (δ): 18.2, (δ _D ): 18.0, (δ _P ): 1.4, (δ _H ): 2.0)

normal heptane 19.200 parts by mass

(SP value (δ): 15.3, (δ _D ): 15.3, (δ _P ): 0.0, (δ _H ): 0.0)

(a)-1 0.196 parts by mass

(b)-2 3.726 parts by mass

(c)-1 0.078 parts by mass

(Example 14)

Normal heptane in the release layer forming composition was changed to cyclohexane (SP value (δ): 16.8, (δ _D ): 16.8, (δ _P ): 0.0, (δ _H ): 0.2), and Example 2 and A release film for resin sheet molding was obtained in the same manner.

(Examples 15 and 16)

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

(Example 17)

A release film for molding an ultra-thin layer resin sheet was obtained in the same manner as in Example 1, except that Composition 5 for Forming a Release Layer having the following composition was used.

(Composition 5 for Forming a Release Layer)

methyl ethyl ketone 24.950 parts by mass

(SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1)

toluene 24.950 parts by mass

(SP value (δ): 18.2, (δ _D ): 18.0, (δ _P ): 1.4, (δ _H ): 2.0)

normal 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 solid content concentration shown in Table 1 was changed and the ratio of the organic solvent was adjusted to be the same as that of the release layer forming composition 5.

(Example 19)

A release film for resin sheet molding was obtained in the same manner as in Example 17, except for changing to the manufacturing method shown in Table 1.

(Example 20)

A release film for forming an ultra-thin layer resin sheet was obtained in the same manner as in Example 1 except for changing to the release layer-forming composition 6.

(Composition 6 for Forming Release Layer)

methyl ethyl ketone 39.920 parts by mass

(SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1)

toluene 39.920 parts by mass

(SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1)

normal 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)

Example 1 except that normal heptane in release layer forming composition 5 was changed to cyclohexane (SP value (δ): 16.8, (δ _D ): 16.8, (δ _P ): 0.0, (δ _H ): 0.2) A release film for resin sheet molding was obtained in the same manner as described above.

(Example 22, 23)

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

(Comparative Example 1)

A release film for forming an ultra-thin layer resin sheet was obtained in the same manner as in Example 1 except that the following composition was changed to the release layer forming composition 7.

(Release Layer Forming Composition 7)

methyl ethyl ketone 24.000 parts by mass

(SP value (δ): 19.1, (δ _D ): 16.0, (δ _P ): 9.0, (δ _H ): 5.1)

toluene 24.000 parts by mass

(SP value (δ): 18.2, (δ _D ): 18.0, (δ _P ): 1.4, (δ _H ): 2.0)

normal heptane 48.000 parts by mass

(SP value (δ): 15.3, (δ _D ): 15.3, (δ _P ): 0.0, (δ _H ): 0.0)

(b)-1 3.922 parts by mass

(c)-1 0.078 parts by mass

(Comparative Example 2)

A release film for forming an ultra-thin layer resin sheet was obtained in the same manner as in Example 1 except that the following composition was changed to the release layer forming composition 8.

(Release layer forming composition 8)

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)

normal heptane 48.000 parts by mass

(SP value (δ): 15.3, (δ _D ): 15.3, (δ _P ): 0.0, (δ _H ): 0.0)

(a)-1 2.941 parts by mass

(b)-2 0.981 parts by mass

(c)-1 0.078 parts by mass

(Comparative Example 3)

A release film for forming an ultra-thin layer resin sheet was obtained in the same manner as in Example 1, except that the following composition was changed to the release layer-forming composition 9.

(Release layer forming composition 9)

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)

normal 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 that the laminated film X2 was applied.

[Table 1A]

[Table 1B]

[Table 1C]

[Table 2A]

[Table 2B]

[Table 2C]

In Comparative Example 1, since the cation-curable polydimethylsiloxane (a) was not contained, the peeling force of the ceramic green sheet was high, and peeling was impossible. In Comparative Examples 2 to 4, the number of protrusions having a height of 10 nm or more exceeded 200/mm 2 , and pinholes occurred in the green sheet as the release object. Further, in Comparative Example 4, inorganic particles were present throughout the substrate, and the smoothness of the release film was remarkably poor, resulting in breakage of the green sheet, pinholes, and the like.

industrial applicability

According to the present invention, by improving the smoothness and peelability of the release layer, a release film capable of molding a resin sheet with fewer defects even in an ultra-thin layer product having a thickness of 1 μm or less is provided, thereby manufacturing a resin sheet without fear of occurrence of defects. can do.

Claims (8)

A release film for molding a resin sheet having a polyester film as a base material and a release layer,
The polyester film has a surface layer A that does not substantially contain inorganic particles,
having the release layer on the surface layer A,
The release layer is a layer in which the release layer forming composition is cured,
The release layer forming composition includes a cation-curable polydimethylsiloxane (a),
The thickness of the release layer is less than 0.050 μm,
Containing 90 parts by mass or more of the cation-curable polydimethylsiloxane (a) based on 100 parts by mass of the resin solid content of the release layer,
The area surface average roughness (Sa) of the release layer is 2 nm or less,
The release film for resin sheet molding, wherein the number of protrusions having a height of 10 nm or more existing on the surface of the release layer is 200/mm 2 or less. According to claim 1,
The release film for resin sheet molding, wherein the maximum protrusion height (Sp) of the release layer is 20 nm or less, and the sum of the number of protrusions having a height of 5 nm or more and less than 10 nm existing on the surface of the release layer and the number of protrusions of 10 nm or more is 1500/mm2 or less. . According to claim 1 or 2,
The release film for resin sheet molding, wherein the cation-curable polydimethylsiloxane (a) has at least one functional group selected from a vinyl ether group, an oxetanyl group, an epoxy group, and an alicyclic epoxy group. According to claim 1 or 2,
The release film for resin sheet molding whose content of the cation-curable polydimethylsiloxane (a) contained in a release layer is 90 mg/m<2> or less. According to claim 1 or 2,
The release layer forming composition contains an organic solvent having an SP value (δ) of 14 or more and 17 or less,
The release layer forming composition contains the organic solvent having an SP value (δ) of 14 or more and 17 or less in an amount of 10% by mass or more with respect to 100 parts by mass of the total weight of the release layer forming composition. According to claim 1 or 2,
A release film for molding a resin sheet, which is a release film for producing a resin sheet containing an inorganic compound. According to claim 6,
A release film for forming a resin sheet, wherein the resin sheet containing an inorganic compound is a ceramic green sheet. According to claim 1 or 2,
A release film for molding a resin sheet, which is a release film for molding a resin sheet having a thickness of 0.2 μm or more and 1.0 μm or less.