Release film for resin sheet molding

Abstract

[Problem] To provide a release film for resin sheet molding which can provide a resin sheet having high smoothness and good sliding property without adding particles in the resin sheet. In particular, the present invention relates to a release film for resin sheet molding used in electronic parts and optical applications. [Solution] A release film for resin sheet molding, in which a release layer is directly laminated on at least one side of a base film or is laminated via another layer, and the skewness Ssk of the surface of the release layer is 1 or less.

Description

Technical Field

[0001] This invention relates to release films for resin sheet molding. In particular, it relates to release films for resin sheet molding used in electronic components and optical applications.

[0002] Previously, release films using polyester film as a substrate, due to their high heat resistance and mechanical properties, were increasingly used as process films in the solution film preparation of resin sheets such as adhesive sheets, protective films, polymer electrolyte membranes, and dielectric resin sheets. In recent years, the demand for high smoothness and transparency in resin sheets used in electronic components and optical applications has led to a growing requirement for high surface smoothness in release films used as process films. Therefore, the technologies described in Patent Documents 1-3 have been disclosed, proposing solutions to reduce the surface roughness of the release layer.

[0003] However, in applications such as optics, high smoothness is required to improve transparency, but excessive smoothness can worsen slippage, leading to concerns about scratches and reduced yield during transport processes. Furthermore, in electronic component applications, smoothness is required to improve electrical properties, but excessive smoothness results in poor slippage, causing misalignment and wrinkles when the resin sheet is wound onto the rollers, preventing perfect winding and raising concerns about performance degradation in electronic components.

[0004] To improve these aspects, Patent Documents 4-6 propose a method of adding specific particles to the resin sheet to make it slippery. Patent Document 7 proposes a method of making the resin sheet slippery by providing an easy-slip layer. Patent Document 8 proposes a method of improvement by bonding a protective film with a constant Ra (arithmetic mean roughness) and Sm (average spacing of unevenness) to the surface.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-144021

[0008] Patent Document 2: Japanese Patent Application Publication No. 2014-154273

[0009] Patent Document 3: Japanese Patent Application Publication No. 2015-182261

[0010] Patent Document 4: Japanese Patent Application Publication No. 2019-095661

[0011] Patent Document 5: Japanese Patent Application Publication No. 7-138471

[0012] Patent Document 6: Japanese Patent Application Publication No. 2016-053177

[0013] Patent Document 7: Japanese Patent Application Publication No. 2006-123465

[0014] Patent Document 8: Japanese Patent Application Publication No. 2004-130736

[0015] Patent Document 9: Japanese Patent Application Publication No. 2012-061712 Summary of the Invention

[0016] The problem the invention aims to solve

[0017] However, in the methods of Patent Documents 4-7, the resulting resin sheets contain particles. Therefore, there are concerns that the transparency may become insufficient due to increased internal haze, and that particle aggregation may increase the maximum protrusion height Sp on the surface, potentially damaging the resin sheet. In the method of Patent Document 8, a component with an uneven surface is pressed into the resin sheet to transfer the unevenness onto the resin sheet. However, the transferred resin sheet needs to be softened, thus limiting the type of resin and the processing conditions. Furthermore, the pressing process can damage the resin sheet. In the method of Patent Document 9, the Ra of the transferred unevenness is too large, potentially damaging the resin sheet, especially in the case of a thin film resin sheet.

[0018] The present invention addresses the above-mentioned problems by providing a release film for molding resin sheets that can provide highly smooth resin sheets with good sliding properties without substantially adding particles inside the resin sheets.

[0019] Therefore, the inventors have discovered that, according to the present invention, which sets fine concave and convex parts by separating the resin phase and makes the proportion of concave parts greater than that of convex parts instead of adding particles to the release film, the convex parts are efficiently transferred to the resin sheet, and even a small surface roughness Sa can effectively impart sliding properties to the resin sheet.

[0020] In addition, the present invention provides a release film for molding resin sheets that, in addition to the effects described above, has a small maximum protrusion height Sp on the surface of the region, no particle shedding, and therefore does not damage the resin sheet, and provides good stable sliding properties.

[0021] Solution for solving the problem

[0022] The inventors conducted in-depth research and found that by coating a smooth substrate film with a coating liquid containing at least a specific resin under specific conditions and then drying and curing it, the irregularities originating from the phase separation structure are formed on the surface of the laminated film, successfully achieving good sliding properties without containing particles, etc.

[0023] That is, the present invention comprises the following components.

[0024] [1] A release film for molding resin sheets, wherein a release layer is directly laminated on at least one side of a substrate film or laminated by means of other layers, wherein the surface skewness Ssk of the aforementioned release layer is 1 or less.

[0025] [2] In one method, the maximum protrusion height Sp of the surface of the release layer is less than 500 nm and the surface roughness Sa is more than 2 nm and less than 200 nm.

[0026] [3] In one method, the ratio of the volume of the protruding protrusion at a load area ratio of 10% to the volume of the protruding valley at a load area ratio of 80% to the volume of the protruding valley at a load area ratio of 80% is: Vm(10) / Vv(80) satisfies the following relationship:

[0027] 0 <Vm(10) / Vv(80)≤1.5。

[0028] [4] In one method, the release layer does not actually contain particles.

[0029] [5] In one embodiment, the release layer is a layer formed by curing the composition, the composition comprising at least: an energy-curable resin (I) having three or more reactive groups within one molecule, a resin (II) separated from the aforementioned resin (I) to form an island structure, and a release component (III).

[0030] [6] In one embodiment, the present invention provides a (stacked) resin sheet that can be laminated on the release film for molding the resin sheet, wherein the release layer side of the resin sheet has a shape on which the release surface shape of the aforementioned release film is transferred.

[0031] The effects of the invention

[0032] The release film for resin sheet molding of the present invention can provide a release film that provides a resin sheet with high smoothness and good sliding properties. Detailed Implementation

[0033] The present invention will now be described in detail.

[0034] The present invention relates to a release film for molding resin sheets, wherein a release layer is directly laminated on at least one side of a substrate film or laminated by means of other layers, wherein the surface skewness Ssk of the aforementioned release layer is 1 or less.

[0035] The present invention preferably forms fine irregularities by separating the resin phase, thus achieving a surface formation effect different from that based on conventional resin addition. For example, since the release layer is substantially free of particles, insufficient transparency, such as increased internal haze, can be suppressed. The present invention exhibits excellent transparency, thereby facilitating the identification of defects during resin sheet manufacturing and defects in the release film itself.

[0036] Furthermore, since the release layer does not contain particles, aggregation in the particle release layer can be suppressed, and the maximum protrusion height Sp on the surface of the region can be prevented from increasing. As a result, for example, the opening and breakage of resin sheets formed on the release film can be suppressed.

[0037] Furthermore, the present invention can form uniform unevenness on the release film, and therefore, it can also form a uniformly shaped uneven surface on the resin sheet. As a result, a resin sheet exhibiting stable sliding properties can be provided.

[0038] It is believed that the present invention preferably forms the release layer under specific conditions to more significantly achieve the above-mentioned effects. As a result, for example, the release layer can be formed with a greater proportion of concave portions than convex portions. It should not be limited to a specific theory for explanation, but by forming a release layer with a greater proportion of concave portions than convex portions, the convex portions of the resin sheet can be formed efficiently and well, and the resin sheet can be given good sliding properties.

[0039] Here, for the resin sheet of the present invention, the surface shape of the surface in contact with the release layer has the shape of the release surface of the release film of the present invention. In the present invention, the protrusions are formed on the resin sheet efficiently, unlike the conventional method of forming a concave portion on the resin sheet by pressing the protrusion of the release film onto the resin sheet.

[0040] More specifically, the present invention is as follows: the composition forming the resin sheet flows into the recesses of the release layer and cures, thereby forming protrusions on the surface of the resin sheet.

[0041] In addition, if it is the release layer of the present invention, it can be peeled off from the release layer without destroying the shape of the protrusions formed on the resin sheet.

[0042] Furthermore, since this invention does not involve pressing the protrusions of the release film onto the resin sheet, it is also possible to achieve thin-film resin sheets. For example, even with thin-film resin sheets, good sliding properties can be provided while maintaining the desired film thickness. This should not be interpreted as a specific theoretical limitation, but in the method of pressing the protrusions of the release film onto the resin sheet, force is applied along the thickness direction of the resin sheet when pressing the release layer onto the resin sheet. Therefore, if the resin sheet is extremely thin, there is a concern about pinholes and other defects, and the possibility of uneven thickness within the resin sheet.

[0043] However, with the present invention, protrusions can be efficiently formed on the resin sheet, thus uniformly maintaining the required film thickness for the resin sheet. Furthermore, appropriate protrusions can be formed on this basis, resulting in resin sheets with excellent rollability. In addition, the originally desired characteristics can be fully utilized. Therefore, the present invention can, for example, contribute more significantly to the thin-film production of resin sheets.

[0044] In addition, it can make the maximum valley depth of the resin sheet shallower, so that the resulting resin sheet is less prone to cracking.

[0045] In one embodiment, the present invention has a release layer directly on at least one side of the substrate film or by means of other layers, wherein the surface roughness (Sa) of the surface of the release layer is 2 nm or more and 200 nm or less, and the maximum surface protrusion height (Sp) is 500 nm or less. In another embodiment, a release film for resin sheet molding is preferred, wherein the release film for resin sheet molding is characterized in that the aforementioned release layer is formed by curing a composition, the composition comprising at least: an energy-ray curable resin (I) having three or more reactive groups per molecule, a resin (II) separated from the aforementioned resin (I) to form an island structure, and a release component (III).

[0046] (Substrate film)

[0047] The release film of the present invention comprises: a substrate and a release layer disposed on the surface of the substrate. If a resin sheet is disposed on the release layer of the release film, the resin sheet can be molded into the same shape as the substrate. Furthermore, the release layer and the resin sheet are easily peeled off; therefore, the shape of the resin sheet can be deformed and maintained into a desired shape. The release layer may be disposed on one side or both sides of the substrate surface.

[0048] As the substrate, known substrates can be used. For example, resin films formed from polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene, and polyimide can be used as the substrate. From the viewpoint of cost and productivity, polyester films are particularly preferred, and polyethylene terephthalate films are even more preferred.

[0049] The thickness of the substrate is preferably 10 μm or more and 188 μm or less, and more preferably 25 μm or more and 100 μm or less. By making the substrate thickness 10 μm or more, deformation can be suppressed by heat during substrate production, processing steps, and molding. On the other hand, if the substrate thickness is 188 μm or less, the required physical properties of the substrate are met, and the amount of substrate to be discarded after use can be reduced, thereby reducing the burden on the environment.

[0050] An easy-adhesive coating to improve adhesion can also be applied between the substrate and the release layer. Additionally, a coating to impart slip resistance, heat resistance, antistatic properties, etc., can be applied to the side of the substrate opposite to the side where the release layer is applied.

[0051] The average surface roughness (Sa) of the surface region of the laminated release layer of the substrate film used in this invention is preferably in the range of 1 nm or more and 50 nm or less, more preferably 2 nm or more and 30 nm or less. The maximum protrusion height (Sp) of the surface region of the laminated release layer of the substrate film used in this invention is preferably 2 μm or less, more preferably 1.5 μm or less. If Sa is 50 nm or less and (Sp) is 2 μm or less, the suppression of thickness unevenness of the release layer and the smoothness of the release layer surface can be maintained constant. Furthermore, the thickness unevenness of the resin sheet can be reduced, and the possibility of cracking starting from the thinner portion when peeling the resin sheet from the release film can be suppressed.

[0052] The average surface roughness (Sa) of the region of the substrate film opposite to the surface of the laminated release layer used in this invention is preferably in the range of 10 to 100 nm, more preferably 2 to 30 nm. The maximum protrusion height (Sp) of the region of the substrate film opposite to the surface of the laminated release layer used in this invention is preferably 2 μm or less, more preferably 1.5 μm or less. If Sa is 10 nm or more, the sliding properties between the release surface and the reverse release surface are improved, resulting in excellent winding performance. In addition, if (Sp) is 2 μm or less, the possibility of a portion of the release layer being peeled off is reduced, and the surface of the release layer is not damaged during winding. Furthermore, the possibility of cracking starting from the peeled portion of the release layer when peeling the resin sheet from the release film can be suppressed.

[0053] The haze of the substrate film used in this invention is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. If the haze is 10% or less, it is easier to perform visual inspection when making the release film and processing the resin sheet on the release film.

[0054] The substrate film of this invention can use recycled materials such as polyester film scraps and plastic bottles. Because of this, the environmental impact can be significantly reduced. Furthermore, including recycled materials from film scraps and plastic bottles improves the film's slip properties and facilitates air degassing. The release layer of this invention allows for the proper recycling, processing, and reuse of polyester films used in various applications.

[0055] When such recycled raw materials are included, particles with an average surface roughness (Sa) in the area of ​​the laminated release layer of the substrate film may be included, which are particles with a size in the range of 1 to 50 nm. In addition, particles with a maximum protrusion height (Sp) in the area of ​​the laminated release layer of the substrate film may be included, which are particles with a size in the range of 2 μm or less.

[0056] For example, the size of the aforementioned particles in the substrate of the present invention can be in the range of (0.001 μm or more and 10 μm). If the particles have a size within this range, the average surface roughness (Sa) and the maximum protrusion height (Sp) of the surface of the laminated release layer of the substrate film can be satisfied.

[0057] In one approach, the substrate has a surface layer that is substantially free of inorganic particles, on which a release layer may be laminated.

[0058] The aforementioned polyester film substrate can be a single layer or a multilayer consisting of two or more layers. For example, the substrate film can be a polyester film having a surface layer A that substantially does not contain particles with a particle size of 1.0 μm or larger and a surface layer B that contains particles. Preferably, surface layer A substantially does not contain inorganic particles with a particle size of 1.0 μm or larger.

[0059] In this method, particles with a diameter of less than 1.0 μm and greater than 1 nm may also be present in surface layer A. By substantially eliminating particles with a diameter of 1.0 μm or greater, such as inorganic particles, surface layer A can reduce defects caused by the transfer of particle shapes from the substrate to the resin sheet.

[0060] In one method, the surface layer A also does not contain particles with a diameter of less than 1.0 μm, which can more effectively suppress the transfer of particle shape from the substrate to the resin sheet and cause defects.

[0061] In one embodiment, the aforementioned polyester film substrate is preferably a laminated film having a surface layer A that is substantially free of inorganic particles on at least one side. This further effectively suppresses the transfer of particle shapes from the substrate to the resin sheet, thus preventing defects.

[0062] For example, surface layer A, which is substantially free of particles with a particle size smaller than 1.0 μm, is preferably also substantially free of particles with a particle size larger than 1.0 μm.

[0063] In this invention, "substantially free of particles" means, for example, that in the case of inorganic particles smaller than 1.0 μm, the content is 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit when quantifying inorganic elements by fluorescence X-ray analysis. This is because even without actively adding particles to the film, contaminants from foreign matter, raw material resins, or dirt adhering to the production line or equipment during the film manufacturing process may be shed and mixed into the film. Furthermore, "substantially free of particles with a diameter of 1.0 μm or larger" means that particles with a diameter of 1.0 μm or larger are not actively contained.

[0064] In the case of a laminated polyester film consisting of two or more layers, the opposite side of the surface layer A, which does not substantially contain inorganic particles, preferably has a surface layer B that may contain inorganic particles, etc.

[0065] As a laminated configuration, when the layer on one side of the release layer is designated as layer A, the layer on the opposite side as layer B, and the core layer (other than these) as layer C, the layer configuration in the thickness direction can be a laminated structure such as release layer / A / B or release layer / A / C / B. Of course, layer C can also consist of multiple layers. Furthermore, surface layer B may not contain inorganic particles. In this case, to impart slip properties for winding the film into a roll, it is preferable to provide a coating layer on surface layer B that contains at least inorganic particles and a binder.

[0066] (release layer)

[0067] The release layer of the present invention is preferably a layer formed by curing a composition, the composition comprising at least: an energy-ray curable resin (I) having three or more reactive groups per molecule, a resin (II) that separates from the aforementioned resin (I) to form an island structure, and a release component (III). The island structure formed by the phase separation of resin (I) and resin (II) allows for the easy formation of numerous recesses without particles. Therefore, even with a small surface roughness Sa, the resin sheet can be efficiently provided with protrusions, imparting slip properties. Furthermore, the low surface roughness Sa prevents the formation of large protrusions, and the low maximum protrusion height Sp on the surface contributes to slip properties without damaging the resin sheet. Additionally, the phase separation forms the protrusions, eliminating the need for pressure application to the resin sheet as required by embossing, thus preventing damage to the resin sheet; therefore, this is preferable.

[0068] (Resin (I))

[0069] As the resin (I) used in this invention, an energy-curable resin having three or more reactive groups per molecule can be used. By having three or more reactive groups per molecule, a release layer with a high elastic modulus can be formed, suppressing deformation of the release layer during resin sheet peeling and inhibiting re-peeling. Furthermore, the solvent resistance of the release layer can be improved, thus preventing corrosion of the release layer caused by solvents during resin sheet coating, which is preferable. Moreover, as an energy-curable resin having three or more reactive groups per molecule, there is no particular limitation on whether the reaction is carried out directly by energy rays or indirectly by the generated active substances. The amount of resin (I) added is preferably 60-98% by mass, more preferably 80-97% by mass, relative to 100 parts by mass of the solid components in the composition forming the release layer. By adding 60% by mass or more, a release layer with a high elastic modulus can be maintained.

[0070] It should be noted that, unless otherwise specified, the solid components in the composition forming the release layer in this specification refer to a total of 100 parts by mass of the solid components of resin (I), resin (II), release component (III), and initiator component.

[0071] Examples of reactive groups in energy-ray curable resins (I) include (meth)acryloyl, alkenyl, acrylamide, maleimide, epoxy, and cyclohexenyl oxide. Among these, energy-ray curable resins with (meth)acryloyl groups are preferred due to their excellent processability.

[0072] As an energy-ray curable resin with acryloyl groups, it can be used in various forms, including monomers, oligomers, and polymers. Furthermore, it must contain at least a resin with three or more reactive groups per molecule, but it can also be used by mixing two or more resins, such as resins with one or two reactive groups per molecule. By mixing these resins with fewer reactive groups, curling and other defects can be suppressed.

[0073] Examples of energy-curable monomers with three or more (meth)acryloyl groups in the molecule include triacrylate isocyanurate, glyceryl tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, di(trimethylolpropane tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and other multifunctional (meth)acrylates, as well as their ethylene oxide modified, propylene oxide modified, and caprolactone modified derivatives.

[0074] Examples of energy-ray-curable monomers having one or two reactive groups within the molecule include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, amyl methacrylate, cyclopentyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, isooctyl methacrylate, nonyl methacrylate, lauryl methacrylate, stearyl methacrylate, behenyl methacrylate, isobornyl methacrylate, cyclic trimethylolpropane acetal (meth)acrylate, and hydroxyethyl methacrylate. Monomers such as hydroxybutyl methacrylate, hydroxypropyl methacrylate, methacrylic acid, dicyclopentenyloxyethyl methacrylate, dicyclopentyl methacrylate, benzyl methacrylate, phenoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, methoxy polyethylene glycol (meth)acrylate, pentamethylpiperidin methacrylate, methylpiperidin methacrylate, 1,4-butanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, nonanediol di(meth)acrylate, bisphenol A di(meth)acrylate, neopentyl glycol di(meth)acrylate, cyclohexanediol di(meth)acrylate, etc., and their ethylene oxide modified, propylene oxide modified, caprolactone modified, etc.

[0075] Examples of energy-curable oligomers containing three or more (meth)acryloyl groups include urethane acrylates, polyester acrylates, polyether acrylates, epoxy acrylates, and silicone-modified acrylates. Commercially available products can be used. Examples include the BEAMSET (registered trademark) series manufactured by Arakawa Chemical Industry Co., Ltd., the NK Oligo series manufactured by Shin-Nakamura Chemical Industry Co., Ltd., the EBECRYL series manufactured by Daicel-Allnex Ltd., the Viscoat series manufactured by Osaka Organic Chemical Industry Co., Ltd., the urethane acrylate series manufactured by Kyoeisha Chemical Co., Ltd., and the UniDic series manufactured by DIC Co., Ltd.

[0076] Examples of energy-curable polymers having three or more (meth)acryloyl groups within the molecule include: grafted polymers with (meth)acryloyl groups grafted onto the polymer; and block polymers with polyfunctional acrylic monomers added to the polymer ends. Acrylic resins, epoxy resins, polyester resins, polysiloxanes, etc., can be used as polymers, without particular limitation.

[0077] (Resin (II))

[0078] The resin (II) used in this invention is dissolved in the same solvent as resin (I) and is uniformly dissolved in the form of a coating (composition before film formation). However, it must become immiscible with each other through drying and curing in the solvent, forming an island structure with resin (I) as the sea component and resin (II) as the island component. Resin (II) can be used without particular limitation as long as the aforementioned conditions are met. Two or more resins can also be used simultaneously. The amount of resin (II) added is preferably 1 to 30% by mass, more preferably 1 to 10% by mass, relative to 100 parts by mass of the solid components in the composition forming the release layer. Adding 1% by mass or more allows for sufficient unevenness to be formed, while setting it to 30% by mass or less results in a high degree of cross-linking of the release layer and low temperature dependence during peeling, which is preferable.

[0079] As a resin (II), for example, any resin that is polyester resin, acrylic resin, polyimide resin, polyamide-imide resin, cellulose resin, etc., and is solvent-soluble, can be used without particular limitation.

[0080] As for polyester resins, there are no particular limitations, and commercially available products can be used. For example, the Vylon series (registered trademark) manufactured by Toyobo Co., Ltd., and the Nichigo-Polyester series (registered trademark) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. can be cited.

[0081] As an acrylic resin, it refers to oligomers and polymers containing polymerized acrylates, which can be homopolymers or copolymers. Additionally, commercially available products can be used. Examples include the ACRYDIC (registered trademark) series manufactured by DIC Corporation and the ARFON (registered trademark) series manufactured by Toa Synthetic Co., Ltd.

[0082] (Mold release component (III))

[0083] As the release agent (III) used in this invention, there are no particular limitations as long as it is a material that can be peeled off from raw sheets such as polysiloxanes, fluorinated compounds, long-chain alkyl compounds, and waxes. Furthermore, materials having functional groups such as (meth)acryloyl groups that can react with and bind to resin (I) are preferred. Alternatively, two or more materials can be mixed. The amount of release agent (III) added relative to 100 parts by weight of the solid components in the composition forming the release layer is preferably 0.05 to 10% by weight, more preferably 0.1 to 5% by weight. If 0.05% by weight or more is added, the peel strength is low; if 10% by weight or less is added, the cross-linking degree of the release layer is high, and the temperature dependence during peeling is low, which is preferable.

[0084] In addition to polydimethylsiloxane, polydiethylsiloxane, and polyphenylsiloxane, some organically modified siloxane compounds, block polymers containing polyorganosiloxanes, and polymers grafted with polyorganosiloxanes can also be used as polyorganosiloxanes. Commercially available products include, for example, the BYK series manufactured by BYK Japan Co., Ltd. (registered trademark) and the Modiper series manufactured by Nippon Yusen Co., Ltd. (registered trademark).

[0085] As a fluorinated compound, there are no particular limitations, and commercially available products can be used. For example, the MEGAFACE (registered trademark) series manufactured by DIC Corporation can be cited.

[0086] Examples of long-chain alkyl compounds include: acrylic polymers copolymerized with long-chain alkyl esters of acrylic acid, grafted polymers grafted with long-chain alkyl groups, and block polymers with long-chain alkyl groups added to the ends. Furthermore, there are no particular limitations; commercially available products can be used. Examples include the Tess Fine (registered trademark) series manufactured by Hitachi Chemicals Co., Ltd., and Peroyl (registered trademark) manufactured by LionSpecialty Chemicals Co., Ltd.

[0087] Examples of active energy rays include electromagnetic waves such as infrared rays, visible light, ultraviolet rays, and X-rays, as well as particulate rays such as electron beams, ion beams, neutral beams, and alpha rays. Among these, ultraviolet rays, which have excellent manufacturing costs, are preferred.

[0088] The atmosphere for irradiating the aforementioned active energy rays can be either ordinary air or a nitrogen atmosphere. In a nitrogen atmosphere, the free radical reaction proceeds smoothly by reducing the oxygen concentration, which can improve the elastic modulus of the release layer. However, if irradiation in air is also practically feasible, then from an economic point of view, irradiation in air is preferred.

[0089] (Photopolymerization initiator)

[0090] When a free radical polymeric resin is used in the release layer of the present invention, a photopolymerization initiator is preferably added. Specifically, examples of photopolymerization initiators include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoyl dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexylphenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azoisobutyronitrile, benzoyl, biphenylyl, butanedione, β-chloroanthraquinone, (2,4,6-trimethylbenzyl diphenyl)phosphine oxide, and 2-benzothiazolyl-N,N-diethyl dithiocarbamate. Preferably, the following compounds are considered to have excellent surface curing properties: 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propanoyl)-benzyl]-phenyl}-2-methylpropane-1-one, 1-hydroxy-cyclohexyl-phenyl-one, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one, with 2-hydroxy-2-methyl-1-phenyl-propane-1-one and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one being particularly preferred. They can be used alone or in combination of two or more.

[0091] There is no particular limitation on the amount of photopolymerization initiator added. For example, it is preferable to use about 0.1 to 20% by mass relative to the resin used.

[0092] In the release layer of this invention, additives such as adhesion improvers and antistatic agents can be added as long as they do not impair the effects of this invention. Furthermore, to improve adhesion to the substrate, it is preferable to pretreat the polyester film surface before applying the release coating layer, such as by anchor coating, corona treatment, plasma treatment, or atmospheric pressure plasma treatment.

[0093] In this invention, the thickness of the release layer can be set according to its intended use and is not particularly limited. Preferably, the cured release layer is in the range of 0.3 to 5.0 μm, more preferably 0.5 to 3.0 μm. If the thickness of the release layer is 0.3 μm or more, the curability of the energy-cured copolymer is good, the elastic modulus of the release layer is improved, and therefore, good peel performance is obtained, which is preferable. In addition, if it is 5.0 μm or less, even if the thickness of the release film becomes thinner, curling is less likely to occur, and poor mobility is not caused during the molding and drying of the resin sheet, which is preferable.

[0094] The skewness (also sometimes called skewness) of the release film of the present invention, which represents the unevenness of the surface of the release layer, is preferably 1 or less. By making skewness 1 or less, more concave portions are formed, and protrusions can be formed efficiently in the resin sheet, which is therefore preferred. More preferably, 0.7 or less, even more preferably 0.5 or less, and most preferably 0 or less.

[0095] In one method, the skewness Ssk can also have a negative value. For example, Ssk can be greater than -1, greater than -0.7, or greater than -0.5. For example, the skewness Ssk of the unevenness of the surface of the release layer can be greater than -1 and less than 1, or greater than -0.7 and less than 1.

[0096] In this invention, when the surface roughness deviation Ssk of the release layer is within the above-mentioned range, it is preferable that the release layer is a layer formed by curing a composition, said composition comprising at least: an energy-curable resin (I) having three or more reactive groups per molecule, a resin (II) that separates from the aforementioned resin (I) to form an island structure, and a release component (III). The inventors have discovered that by preferably coating and drying / curing the composition under the specific conditions described in this specification, the surface roughness deviation Ssk of the release layer can be adjusted to the above-mentioned range more effectively.

[0097] Preferably, the ratio of the volume of the protruding portion at a load area ratio of 10% to the volume of the protruding valley portion at a load area ratio of 80% is Vm(10) / Vv(80), which satisfies the following relationship.

[0098] 0 <Vm(10) / Vv(80)≤1.5

[0099] If Vm(10) / Vv(80)≤1.5, the number of concave portions increases, and protrusions can be formed efficiently in the resin sheet, which is preferred. More preferably, it is 1.0 or less, even more preferably 0.7 or less, and most preferably 0.5 or less.

[0100] In one approach, Vm(10) / Vv(80) is greater than 0.1, for example, greater than 0.15, or greater than 0.20.

[0101] The haze of the release film of the present invention is preferably 15% or less, more preferably 10% or less, and even more preferably 5% or less. If the haze is 15% or less, it is easier to perform visual inspection when processing resin sheets on the release film.

[0102] The release film of the present invention preferably contains no particles. By being free of particles, it prevents the formation of coarse protrusions caused by particle aggregation, thus avoiding damage to the resin sheet during transfer. Furthermore, since it contains no particles, there is no particle shedding, preventing contamination of the resin sheet, which is also preferable. Additionally, it provides uniform and stable sliding properties without the instability of uneven areas in the transfer due to particle shedding, thus preventing unstable sliding properties. Moreover, since the resin sheet is substantially free of particles, it exhibits high transparency, for example, in optical applications, and excellent electrical properties, for electronic components.

[0103] The release film of the present invention preferably has a release layer with a moderately uneven surface. Therefore, the average surface roughness (Sa) of the surface area of ​​the release layer is preferably 2 nm or more and 200 nm or less, for example, 2 nm or more and 100 nm or less, 2 nm or more and 50 nm or less, and more preferably 5 nm or more and 30 nm or less. If the surface roughness (Sa) is 2 nm or more, it imparts unevenness to the resin sheet, providing slip resistance. Furthermore, if the surface roughness (Sa) is 200 nm or less, it is preferable that it does not affect the surface shape of the resin sheet. Additionally, it is preferable that the aforementioned Sa is satisfied, and the maximum protrusion height (Sp) of the surface area of ​​the release layer is 500 nm or less, more preferably 100 nm or less, and even more preferably 60 nm or less. If the maximum protrusion height (Sp) of the surface area is 500 nm or less, concerns about pinhole defects in the resin sheet are reduced, and the gaps in the wound resin sheet are decreased, thus allowing for more compact winding, which is preferable. In addition, if the maximum protrusion height (Sp) on the regional surface is below 500 nm, a smoother resin sheet can be formed, and a resin sheet roll with less twist can be formed.

[0104] For example, the maximum protrusion height (Sp) on the regional surface is above 1 nm.

[0105] In this invention, the method for forming the release layer is not particularly limited, and the following method is used: a coating liquid containing a resin with release properties is spread on one side of a polyester film substrate by coating or the like, and after the solvent is removed by drying, it is cured. Preferably, the composition is coated and dried / cured under the specific conditions described in this specification, so that the release layer of this invention can be formed more effectively, and a resin sheet with high smoothness and good sliding properties can be provided.

[0106] When applying the release layer of the present invention to the substrate film via solution coating, the solvent drying temperature is preferably 50°C or higher and 120°C or lower, more preferably 60°C or higher and 100°C or lower. The drying time is preferably 30 seconds or less, more preferably 20 seconds or less. Furthermore, after solvent drying, it is preferable to irradiate the film with active energy rays to induce a curing reaction. As the active energy rays used at this time, ultraviolet light, electron beams, X-rays, etc., can be used, but ultraviolet light is preferred as it is readily available. The amount of ultraviolet light irradiated is preferably 30 to 300 mJ / cm². 2 More preferably 30~200mJ / cm 2 By setting it to 30mJ / cm 2 The above ensures that the resin cures sufficiently, by setting the value to 300 mJ / cm. 2 This allows for improved processing speed, thus enabling the economical production of release films, which is preferable.

[0107] The atmosphere for irradiating the aforementioned active energy rays can be either ordinary air or a nitrogen atmosphere. In a nitrogen atmosphere, the oxygen concentration is reduced, allowing the free radical reaction to proceed smoothly and improving the elastic modulus of the release layer. However, if irradiation in air is also practically feasible, then from an economic point of view, irradiation in air is preferred.

[0108] In this invention, the surface tension of the coating liquid when applying the release layer is not particularly limited, but is preferably 30 mN / m or less. By maintaining the surface tension as described above, the coatability after coating is improved, and the unevenness of the dried coating surface can be reduced.

[0109] As for the coating method of the above-mentioned coating liquid, any known coating method can be applied, such as roll coating methods such as gravure coating, reverse coating, bar coating, mold coating, spray coating, air knife coating, etc.

[0110] It should be noted that by coating the composition and drying / curing it in the manner described above, a release layer with a surface deflection Ssk of less than 1 can also be obtained, as the release layer is substantially free of particles.

[0111] On the other hand, the surface shape of the release layer is fine and complex, so it is impossible or impractical to directly specify it based on the structure or characteristics described in this specification. Therefore, in this invention, the release layer of the present invention can be effectively formed by using the specific composition described above and through specific manufacturing processes. Therefore, it is sometimes necessary to use the expression "release layer formed by the manufacturing method described in this specification".

[0112] Alternatively, sometimes it is necessary to use various conditions such as the mixing ratio of an energy-curable resin (I) with three or more reactive groups within one molecule and a resin (II) that is separated from the aforementioned resin (I) to form an island structure, the type of resin (II), and the drying temperature, and to obtain a release layer under such conditions.

[0113] Similarly, the surface shape of the resulting resin sheet is also fine and complex, so it is impossible or impractical to directly specify it based on the structure or characteristics described in this specification. Therefore, in this invention, for the resin sheet of the present invention, it is sometimes necessary to use a description such as "the surface of the resin sheet on the release layer side has a shape in which the release surface shape of the release film of the present invention is transferred".

[0114] (Resin sheet)

[0115] In one embodiment, the present invention relates to release films used in the medical field, industrial field, for example, in the manufacturing processes of electronic components, electronic substrates, and thermosetting resin components such as fiber-reinforced plastics. More specifically, it relates to the following substances: release films useful for surface protective films, release films such as adhesive tapes, release pads, separators, separators for process tapes used in the manufacture of semiconductor products (cutting, chip bonding, back-side grinding), carriers for forming unfired sheets in the manufacture of ceramic capacitors, carriers in the manufacture of composite materials, and separators for protective materials.

[0116] In particular, the release film used as a thin film for optical applications or for manufacturing electronic components, and the resin sheet formed on the release film, are not particularly limited, and examples include vinyl resin, acrylic resin, epoxy resin, polyester resin, styrene resin, fluororesin, amino resin, phenolic resin, etc.

[0117] Resin sheets formed using the aforementioned resins lack slip properties on their own, resulting in poor workability, reduced yield, and the possibility of adhesion. To avoid these issues, particles or wax are added as slip agents. However, with the addition of particles, the particles can aggregate into large protrusions, potentially damaging the resin sheet. Furthermore, if transparency is required in the resin sheet, particle aggregation can increase haze, potentially leading to a loss of transparency. Additionally, with the addition of wax, when the resin sheet is used in electronic components, the wax can be transferred to the electronic components, causing contamination and potentially leading to malfunctions.

[0118] This invention imparts lubricity to resin sheets without using particles or waxes, thus suppressing the aforementioned problems. The resin composition forming the resin sheet can be appropriately selected according to the intended application.

[0119] In one embodiment, the present invention provides a method for manufacturing a resin sheet using the release film for resin sheet molding of the present invention. For example, the method for manufacturing the resin sheet includes the following steps: treating the resin sheet at a drying temperature of 50°C or higher and 120°C or lower, for example, at a drying temperature of 60°C or higher and 100°C or lower, wherein the drying time is preferably 30 seconds or less, more preferably 20 seconds or less.

[0120] If such drying conditions are met, resin sheets can be formed without compromising the surface shape of the release layer of the present invention.

[0121] In one embodiment, a resin sheet is provided, which is a (laminated) resin sheet that can be laminated onto a release film for molding resin sheets.

[0122] The release layer side of the aforementioned resin sheet has a shape with the release surface shape of the aforementioned release film transferred on it.

[0123] Example

[0124] To illustrate the invention in detail, the following examples are provided, but the invention is not limited to these examples. The characteristic values ​​used in the invention are evaluated using the following methods.

[0125] (1) Substrate film thickness

[0126] Using a Milltron (electronic micro indicator), cut four 5cm square samples from any four locations on the film to be measured, and measure five points on each sample (a total of 20 points). The average value is taken as the thickness.

[0127] (2) Demolding layer thickness

[0128] The thickness of the release layer was measured using an optical interferometer (F20, manufactured by Filmetrics, INC.). (The refractive index of the release layer was calculated as 1.52.)

[0129] (3) Regional surface roughness Sa, regional surface maximum protrusion height Sp

[0130] The values ​​were obtained using a non-contact surface shape measurement system (VertScan R550H-M100, manufactured by Mitsubishi Chemical Systems, Inc.) under the following conditions. The average surface roughness (Sa) of the region is the average of 5 measurements, and the maximum protrusion height (Sp) of the region surface is the maximum value of 5 measurements excluding the maximum and minimum values ​​out of 7 measurements.

[0131] (Measurement conditions)

[0132] • Measurement mode: WAVE mode

[0133] Objective lens: 50x

[0134] · 0.5× Tube lens

[0135] (Analysis conditions)

[0136] • Surface correction: 4 corrections

[0137] • Interpolation processing: Full interpolation

[0138] • Filter: Gaussian (cutoff: 20μm)

[0139] (4) The ratio of the volume of the protruding part at a load area ratio of 10% to the volume of the protruding valley at a load area ratio of 80% is: Vm(10) / Vv(80).

[0140] The values ​​were measured using a non-contact surface shape measuring system (VertScan R550H-M100, manufactured by Mitsubishi Chemical Systems, Inc.) under the following conditions.

[0141] (Measurement conditions)

[0142] • Measurement mode: WAVE mode

[0143] Objective lens: 50x

[0144] · 0.5× Tube lens

[0145] (Analysis conditions)

[0146] • Surface correction: 4 corrections

[0147] • Interpolation processing: Full interpolation

[0148] • Filter: Gaussian (cutoff: 20μm)

[0149] • ISO parameters: Void and Material Volume Parameters

[0150] (5) Sliding

[0151] The resin sheet coating solutions 1 to 4 with the following compositions are mixed separately and coated onto the release surface of the release film for molding resin sheet of the present invention using a wire rod, so that the dried resin has a thickness of 5.0 μm. After drying at 90°C for 1 minute, the release film is peeled off to obtain a resin sheet.

[0152] Slide the resin sheet fixed on the table with its surface facing up and slide the back of the peeled resin sheet by hand, and determine the sliding performance based on the following criteria.

[0153] ○: Slides without hooking

[0154] △: There is a hook, but it slides.

[0155] ×: No movement and no sliding

[0156] (Resin sheet 1)

[0157] 100.00 parts by weight of resin

[0158] (Polyester resin, Toyobo Co., Ltd., Vylon (registered trademark) RV280)

[0159] Dilute solvent 700.00 parts by weight

[0160] (Methyl ethyl ketone / toluene = 1 / 1)

[0161] (Resin sheet 2)

[0162] 100.00 parts by weight of resin

[0163] (Polyvinyl butyral resin, BM-S, manufactured by Sekisui Chemicals Co., Ltd.)

[0164] Dilute solvent 700.00 parts by weight

[0165] (Ethanol / Toluene = 1 / 1)

[0166] (Resin sheet 3)

[0167] 100.00 parts by weight of resin

[0168] (Epoxy resin, CELLOXIDE 2021P, manufactured by Daicel Corporation)

[0169] 40.00 parts by weight of photoinitiator

[0170] (Boron-based cationic UV curing initiator, CATA211, manufactured by Arakawa Chemical Industry Co., Ltd., solid content concentration 18.5% by mass)

[0171] Dilute solvent 500.00 parts by weight

[0172] (Methyl ethyl ketone / toluene = 1 / 1)

[0173] (Preparation of polyethylene terephthalate granules (PET(1)))

[0174] As the esterification reactor, a continuous esterification reactor is used, comprising a three-stage fully mixed tank with a stirrer, a condenser, a feed inlet, and a product outlet. The slurry is continuously fed to the first esterification reactor of the esterification reactor at a rate of 2 tons / hour of TPA, 2 moles of EG (ethylene glycol) relative to 1 mole of TPA, and 160 ppm of antimony trioxide and Sb atoms relative to the generated PET. The reaction is carried out at atmospheric pressure, with an average residence time of 4 hours, and at 255°C. Next, the reaction product in the first esterification reactor is continuously removed from the system and supplied to the second esterification reactor. EG removed by distillation from the first esterification reactor is supplied to the second esterification reactor in an amount of 8% by mass relative to the generated PET. Then, an EG solution containing 65 ppm of magnesium acetate tetrahydrate relative to the generated PET and an EG solution containing 40 ppm of TMPA (trimethyl phosphate) relative to the generated PET are added. The reaction is carried out at atmospheric pressure, with an average residence time of 1 hour and at 260°C. Next, the reaction product from the second esterification reactor was continuously removed from the system and fed into the third esterification reactor. Using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.), 0.2% by mass of porous colloidal silica with an average particle size of 0.9 μm and dispersed for an average of 5 times under a pressure of 39 MPa (400 kg / cm2) and 0.4% by mass of synthetic calcium carbonate with an average particle size of 0.6 μm and ammonium salt of polyacrylic acid attached to 1% by mass relative to calcium carbonate were respectively formed into a 10% EG slurry. The reaction was carried out at atmospheric pressure, with an average residence time of 0.5 hours and a temperature of 260°C, while the slurry was being added. The esterification reaction product generated in the third esterification reactor was continuously fed to the third-stage continuous polycondensation reactor for polycondensation. After filtration through a filter with 95% sintered stainless steel fibers with a particle size of 20 μm, the product was ultrafiltered, extruded into water, and cut into small pieces after cooling to obtain PET flakes with an intrinsic viscosity of 0.60 dl / g (hereinafter referred to as PET (1)). The lubricant content in the PET flakes was 0.6% by mass.

[0175] (Preparation of polyethylene terephthalate granules (PET(2)))

[0176] On the other hand, in the manufacturing of the above-mentioned PET flakes, PET flakes with an intrinsic viscosity of 0.62 dl / g that are completely free of particles such as calcium carbonate and silicon dioxide are obtained (hereafter referred to as PET (2)).

[0177] (Manufacturing of the laminated thin film X1)

[0178] After drying these PET flakes, they were melted at 285°C and then melted at 290°C using a separate melt extruder. This resulted in a two-stage filtration process: a filter containing 95% stainless steel fibers with a particle size of 15μm and a filter containing 95% stainless steel particles with a particle size of 15μm. The PET flakes were then combined in the feed head, and PET (1) was layered as surface layer B (reverse demolding side layer) and PET (2) as surface layer A (demolding side layer). The PET flakes were extruded (cast) into sheets at a rate of 45 m / min. The sheets were then electrostatically bonded to a casting drum at 30°C and cooled to obtain unstretched polyethylene terephthalate sheets with an intrinsic viscosity of 0.59 dl / g. The layer ratio was adjusted to PET (1) / (2) = 60% / 40% based on the discharge rate of each extruder. Next, the unstretched sheet was heated in an infrared heater, and then stretched longitudinally by 3.5 times using the speed difference between the rollers at a roller temperature of 80°C. Afterward, it was fed into a tenter frame and stretched transversely by 4.2 times at 140°C. Then, it was heat-treated at 210°C in a heat-setting zone. Following this, a 2.3% relaxation treatment was performed transversely at 170°C to obtain a biaxially stretched polyethylene terephthalate film X1 with a thickness of 31 μm. The surface layer A of the obtained film X1 has a Sa value of 2 nm, and the surface layer B has a Sa value of 29 nm.

[0179] (Example 1)

[0180] (Preparation of release coating liquid)

[0181] Using a reverse gravure printing plate, a coating liquid 1 with the following composition was applied to the surface layer A of the laminated film X1, resulting in a release layer thickness of 2.0 μm after drying. After drying at 90°C for 30 seconds, the film was irradiated with ultraviolet light at a rate of 200 mJ / cm² using a high-pressure mercury lamp to obtain a release film for resin sheet molding. The release film was evaluated for release layer thickness, regional surface roughness Sa, maximum protrusion height (Sp) of the regional surface, the ratio of the volume of the protrusion to the volume of the valley: Vm (10) / Vv (80), and slip properties.

[0182] (Coating liquid 1)

[0183] Resin (I) 100.00 parts by weight

[0184] (Dipentaerythritol hexaacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., A-DPH)

[0185] Resin (II-1) 6.59 parts by weight

[0186] (Polyester resin, Toyobo Co., Ltd., Vylon (registered trademark) RV280)

[0187] Resin (II-2) 10.99 parts by weight

[0188] (Polyester polyurethane resin, Toyobo Co., Ltd. Vylon (registered trademark) UR1400, solid content concentration 30.0% by mass)

[0189] Release agent (III) 1.26 parts by weight

[0190] (Acryloyl-modified polydimethylsiloxane, BYK-UV3505, manufactured by BYK Japan Co., Ltd., solid content concentration 40.0% by mass)

[0191] Photopolymerization initiator (IV) 5.49 parts by weight

[0192] (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK Co., Ltd.)

[0193] Diluent (V) 425.11 parts by weight

[0194] (Methyl ethyl ketone / cyclohexanone = 4 / 1)

[0195] (Example 2)

[0196] The coating was applied so that the dried release layer film thickness was 3.0 μm. Otherwise, the procedure was the same as in Example 1 to obtain the release film. Furthermore, the same evaluation as in Example 1 was performed.

[0197] (Example 3)

[0198] The coating liquid used is the following coating liquid 3, to which dipropylene glycol diacrylate as resin (II-3) is added to coating liquid 1.

[0199] (Coating liquid 3)

[0200] Resin (I) 100.00 parts by weight

[0201] (Dipentaerythritol hexaacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., A-DPH)

[0202] Resin (II-1) 6.71 parts by weight of polyester resin

[0203] (Vylon RV280 manufactured by Toyobo Co., Ltd. (registered trademark))

[0204] Resin (II-2): 11.18 parts by weight of polyester polyurethane resin.

[0205] (Vylon UR1400 manufactured by Toyobo Co., Ltd. (registered trademark), solid content concentration 30.0% by mass)

[0206] Resin (II-3) Polyacrylate 49.68 parts by weight

[0207] (Dipropylene glycol diacrylate, APG-100)

[0208] Release agent (III) 1.60 parts by weight

[0209] (Free radical polymerizable silicone release agent, KF-2005, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0210] Photopolymerization initiator (IV) 11.18 parts by weight

[0211] (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK Co., Ltd.)

[0212] Diluent (V) 434.05 parts by weight

[0213] (Methyl ethyl ketone / cyclohexanone = 4 / 1)

[0214] The coating was applied so that the dried release film thickness was 2.0 μm. Coating liquid 3 was used, and the procedure was otherwise the same as in Example 1 to obtain the release film. Furthermore, the same evaluation as in Example 1 was performed.

[0215] (Example 4)

[0216] The coating liquid used was the following 4, which had a reduced ratio of resin (II-1) to resin (II-2) compared to Example 1.

[0217] (Coating liquid 4)

[0218] Resin (I) 100.00 parts by weight

[0219] (Dipentaerythritol hexaacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.)

[0220] Resin (II-1): 2.06 parts by weight of polyester resin

[0221] (Vylon RV280 manufactured by Toyobo Co., Ltd. (registered trademark))

[0222] Resin (II-2): 3.44 parts by weight of polyester polyurethane resin.

[0223] (Vylon UR1400 manufactured by Toyobo Co., Ltd. (registered trademark), solid content concentration 30.0% by mass)

[0224] Release agent (III) 1.19 parts by weight

[0225] (Acryloyl-modified polydimethylsiloxane, BYK-UV3505, manufactured by BYK Japan Co., Ltd., solid content concentration 40.0% by mass)

[0226] Photopolymerization initiator (IV) 5.15 parts by weight

[0227] (OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK Co., Ltd.)

[0228] Diluent (V) 403.63 parts by weight

[0229] (Methyl ethyl ketone / cyclohexanone = 4 / 1)

[0230] The coating was applied so that the dried release film thickness was 2.0 μm. Coating liquid 4 was used, and the procedure was otherwise the same as in Example 1 to obtain the release film. Furthermore, the same evaluation as in Example 1 was performed.

[0231] (Comparative Example 1)

[0232] As Comparative Example 1, a coating liquid 5 with the following composition was used to coat a resin sheet containing particles in the release layer, resulting in a release film with a dried release layer thickness of 0.1 μm. The same procedure as in Example 1 was followed, using the same coating liquid 5 and a dried release layer thickness of 0.1 μm. Furthermore, the same evaluation as in Example 1 was performed.

[0233] (Coating liquid 5)

[0234] 100.00 parts by weight of resin

[0235] (Organic silicone resin, LTC851, manufactured by Dow Corning Toray Co., Ltd., solid content concentration 30.0% by mass)

[0236] 7.50 parts by weight of granules

[0237] (Silica gel solution, MEK-ST-40, manufactured by Nissan Chemical Co., Ltd., solid content concentration 40.0% by mass)

[0238] 1.70 parts by weight of curing catalyst

[0239] (Platinum catalyst, SRX212, manufactured by Dow Corning Toray Co., Ltd.)

[0240] Dilute solvent 5000.00 parts by weight

[0241] (Methyl ethyl ketone / toluene = 1 / 1)

[0242] (Comparative Example 2)

[0243] As Comparative Example 2, a release film was obtained using a coating liquid 6 with the following composition, operated in the same manner as in Comparative Example 1. Furthermore, the same evaluation as in Comparative Example 1 was performed.

[0244] (Coating liquid 6)

[0245] 100.00 parts by weight of resin

[0246] (Organic silicone resin, LTC851, manufactured by Dow Corning Toray Co., Ltd., solid content concentration 30.0% by mass)

[0247] 45.00 parts by weight of granules

[0248] (Silica gel solution, MEK-ST-UP, manufactured by Nissan Chemical Co., Ltd., solid content concentration 20.0% by mass)

[0249] 1.70 parts by weight of curing catalyst

[0250] (Platinum catalyst, SRX212, manufactured by Dow Corning Toray Co., Ltd.)

[0251] Dilute solvent 5000.00 parts by weight

[0252] (Methyl ethyl ketone / toluene = 1 / 1)

[0253] [Table 1]

[0254]

[0255] In the embodiments, sliding properties were demonstrated in any of the resin sheets.

[0256] In Comparative Example 1, Ssk is greater than 1, the protrusions were not transferred to the resin sheet, and no sliding property was observed on any resin sheet. In Comparative Example 2, Sa is also larger and Ssk is smaller than in Comparative Example 1, but Ssk is greater than 1. Therefore, the transferred protrusions are not sufficient, and no sliding property was observed on any resin sheet.

[0257] Industrial availability

[0258] This invention relates to release films for resin sheet molding. In particular, it relates to release films for resin sheet molding used in electronic components and optical applications.

Claims

1. A release film for molding resin sheets, wherein a release layer is directly laminated on at least one side of a substrate film or laminated with other layers. The release layer is essentially free of particles. The release layer is a layer formed by curing the composition, which at least includes: a solvent, an energy-curable resin (I) having three or more reactive groups within one molecule, a resin (II) that separates from the resin (I) to form an island structure, and a release component (III). The resin (II) comprises a polyester resin (II-1) and a polyester polyurethane resin (II-2). The solvent contains methyl ethyl ketone and cyclohexanone. The surface skewness Ssk of the release layer is less than 0.

2. The release film for resin sheet molding according to claim 1, wherein, The maximum protrusion height Sp of the surface of the release layer is less than 500 nm, and the surface roughness Sa is more than 2 nm and less than 200 nm.

3. The release film for resin sheet molding according to claim 1, wherein, The ratio of the volume of the protruding protrusion at a load area ratio of 10% (Vm(10)) to the volume of the protruding valley at a load area ratio of 80% (Vv(80)) (Vm(10) / Vv(80)) satisfies the following relationship: 0 <Vm(10) / Vv(80)≤1.5。 4. A resin sheet, which is a resin sheet capable of being laminated onto a release film for molding resin sheet according to any one of claims 1 to 3. The release layer side of the resin sheet has a shape with the release surface shape of the release film transferred on it.

Images