Demolding film

Abstract

Provided is a mold release film in which both peelability and wettability of a mold release layer can be easily achieved, and the coating uniformity of the mold release layer is high. Also provided is a mold release film which has good reusability and excellent adhesion between the mold release layer and the base material. The present invention is a mold release film having a base film and a mold release layer obtained by reacting and curing an aqueous coating composition, the aqueous coating composition comprising: an alkenyl group-containing silicone (A) having a number average molecular weight of 1,000-14,000 (inclusive); and a Si-H group-containing silicone (B) having a phenyl group.

Description

Technical Field

[0001] This invention relates to a release film having a substrate film and a release layer, and to a release film useful as a film for various processes. Background Technology

[0002] Previously, release films based on polyester films and the like have high heat resistance and mechanical properties, and are used in the process of making films for resin sheets such as adhesive sheets, cover films, ceramic slurries, and polymer electrolyte membranes. In addition, as a release layer for release films, many release layers formed of coating compositions containing organosilicon have been proposed due to their good heat resistance and peelability (Patent Documents 1-5).

[0003] The aforementioned release film is also used as a process film in the molding of ceramic green sheets, such as ceramic capacitors and ceramic substrates, where high smoothness is required. In recent years, with the miniaturization and increasing capacitance of multilayer ceramic capacitors, there has been a trend towards thinner ceramic green sheets. Ceramic green sheets are formed by coating a slurry containing ceramic components such as barium titanate and binder resin onto the release layer of the release film and then drying it. Multilayer ceramic capacitors are manufactured by laminating, pressing, sintering, and coating external electrodes on the ceramic green sheets obtained by printing electrodes on the formed ceramic green sheets and peeling them off from the release film.

[0004] Patent documents 1 and 2 disclose a release film that utilizes a coating composition comprising a polysiloxane having unsaturated groups, a polysiloxane having phenyl and Si-H groups, and a platinum group metal catalyst to form a release layer. The use of solvent-free silicone is described, exhibiting excellent adhesion, particularly to plastic film substrates.

[0005] Patent document 3 also proposes a release film, which similarly consists of a coating composition comprising a polysiloxane with unsaturated groups, a polysiloxane with phenyl and Si-H groups, and a platinum group metal catalyst, forming a release layer. It describes these films as typically produced via in-line coating, which improves adhesion to polyester films. The in-line coating involves extruding an amorphous melt of polymer to solidify it into a sheet form, applying a release coating at this point, and then subjecting the film to preheating, stretching, heat setting, and cooling processes to create the release film.

[0006] Patent document 4 discloses a release film in which a release layer is formed from a coating composition comprising a polysiloxane with unsaturated groups having a weight-average molecular weight of 500 or more and 30,000 or less, a polysiloxane with Si-H groups having a weight-average molecular weight of 150 or more and 10,000 or less, and a platinum group metal catalyst. It describes good release properties of the self-adhesive, minimal transfer of adhesive to the component, and good antistatic properties.

[0007] Patent document 5 discloses a release film having a release layer, which is a coating composition comprising a polysiloxane having unsaturated groups, a polysiloxane having Si-H groups, and a platinum group metal catalyst, with a specified ratio of unsaturated groups to Si-H groups. It describes how the increase in peel force with the adhesive can be suppressed even when the release agent layer of the release sheet is exposed to the atmosphere for a long time.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2018-012827

[0011] Patent Document 2: Japanese Patent Application Publication No. 2018-119056

[0012] Patent Document 3: Japanese Patent Publication No. 2011-509323

[0013] Patent Document 4: International Publication No. 2017 / 200056

[0014] Patent Document 5: Japanese Patent Application Publication No. 2013-202831 Summary of the Invention

[0015] The problem the invention aims to solve

[0016] However, in recent years, there has been a trend towards thin-film-based components such as ceramic green sheets formed on the release layer of release films. Sometimes, both peelability and wettability of the release layer surface are required, making it difficult to simultaneously achieve both. That is, changing the chemical composition of the release layer to improve wettability results in reduced peelability. Furthermore, there is a lack of precedent for release films that also possess reusability and substrate adhesion. For example, regarding reusability, when using recycled resin made from release films in new release films, foreign matter from the recycled resin sometimes appears as protrusions on the surface, deteriorating surface smoothness. Regarding the adhesion between the substrate and the release layer, there is a problem that peelability changes when ceramic slurry is applied to the release film and transferred to the contacting rollers.

[0017] Patent documents 1-3 did not envision its use for molding ceramic green sheets, but rather evaluated its peelability to adhesive tapes. However, there was no indication of its peelability for thin-layer ceramic green sheets. Furthermore, a crosslinking agent containing phenyl groups was used to improve the adhesion between the substrate and the release layer, but the effect of phenyl groups on peel force was not confirmed, making it unsuitable as a release film exhibiting light peelability applicable to thin-layer ceramic green sheets, etc.

[0018] Patent document 4 proposes a release film having a release layer formed by a coating composition comprising a polysiloxane having unsaturated groups with a weight average molecular weight of 500 or more and 30,000 or less, and a polysiloxane having Si-H groups with a weight average molecular weight of 150 or more and 10,000 or less, but does not suggest a balance between peelability and wettability.

[0019] In Patent Document 5, a polysiloxane with unsaturated groups and a weight-average molecular weight of 1,100,000 is used, which has problems such as lack of wettability and poor coating uniformity of the release layer.

[0020] The object of this invention is to provide a release film that easily balances the peelability and wettability of the release layer, and has high coating uniformity of the release layer. Furthermore, it provides a release film with the advantages of good reusability and excellent adhesion between the substrate and the release layer.

[0021] Solution for solving the problem

[0022] In order to solve this problem, the inventors conducted in-depth research and found that the above-mentioned problem could be solved by reacting and curing a release layer containing an alkenyl organosilicon (A) having a specified molecular weight and a Si-H-based organosilicon (B) having a phenyl group according to the present invention. Thus, the present invention was completed. That is, the present invention includes the following contents.

[0023] [1] A release film having a substrate film and a release layer formed by reacting and curing an aqueous coating composition.

[0024] The waterborne coating composition comprises: an alkenyl organosilicon (A) having a number average molecular weight of 1,000 or more and 14,000 or less; and a Si-H organosilicon (B) having a phenyl group, wherein the Si-H organosilicon (B) is represented by general formula (I).

[0025]

[0026] (In formula (I), a1 is a natural number selected from 1 to 50, b1 is a natural number selected from 1 to 50, and c1 is a natural number selected from 0 to 50.)

[0027] [2] According to the release film of [1], wherein the Si-H based organosilicon (B) comprises organosilicon with a number average molecular weight of 1,000 or more and 5,000 or less.

[0028] [3] The release film according to [1] or [2], wherein the alkenyl organosilicon (A) is represented by the following general formula (II).

[0029]

[0030] (In general formula (II), R1 is an alkenyl group, which may be the same or different, having 2 or more but less than 8 carbon atoms, or a monovalent hydrocarbon group containing an alkyl or phenyl group, having 1 or more but less than 16 carbon atoms, wherein, with [SiO] a2 The R1 bonded to the silicon atom shown is not an alkenyl group, but rather [SiO]. c2 At least one of the silicon atoms bonded in R1 is the aforementioned alkenyl group.

[0031] With [SiO] b2 The silicon atoms bonded to Y1 may be the same or different, and may be an alkenyl group with 2 or more but less than 8 carbon atoms, or a monovalent hydrocarbon group containing alkyl or phenyl atoms with 1 or more but less than 16 carbon atoms, or may be represented by the following general formula (III).

[0032] In general formula (III), R1 is optionally the same as at least one R1 in general formula (II), and in general formula (III), R1 may be the same or different.

[0033] When the total of a2, b2, c2, and all d2 is set to 100 mol%, then a2 is 1 mol% or more, b2 is 0 mol% or more, c2 is 0 mol% or more, and d2 is 0 mol% or more.

[0034]

[0035] [4] The release film according to any one of [1] to [3], wherein when the total amount of the alkenyl organosilicon (A) and the Si-H organosilicon (B) is set to 100 parts by mass, the content of the Si-H organosilicon (B) is 3 to 30 parts by mass.

[0036] [5] The release film according to any one of [1] to [4], wherein the release layer is formed by coating the aqueous coating composition onto a substrate film before crystal orientation is completed, stretching it in at least one direction and then heat-treating it to complete crystal orientation.

[0037] [6] The release film according to any one of [1] to [5], wherein the substrate film is a polyester film.

[0038] [7] The release film according to any one of [1] to [6], wherein the release film is a release film for laminated ceramic capacitors or a release film for resin sheets.

[0039] The effects of the invention

[0040] According to the present invention, a release film can be provided that has the advantages of easily balancing the peelability and wettability of the release layer, high coating uniformity of the release layer, and thus good reusability and excellent adhesion.

[0041] The exact reasons for this effect are not yet clear, but it is believed that organosilicon crosslinks formed by the reaction of relatively low molecular weight organosilicones tend to form dense three-dimensional structures. Therefore, they tend to maintain hardness even when in contact with organic solvents, reducing the adhesion force when peeling laminates coated or cast onto the surface of the release layer. Furthermore, it is believed that organosilicon crosslinks with dense three-dimensional structures are less likely to form helical structures such as polydimethylsiloxane, which also affects the surface free energy of the release layer surface, thus easily exhibiting moderate wettability to the laminates.

[0042] Furthermore, it is believed that by reducing the molecular weight of the organosilicon contained in the water-based coating composition, the stability and uniformity of the coating film are increased, and aggregates are less likely to form in the release layer, thus improving the coating uniformity. In addition, it is believed that during remelting during reuse, since the coating film has high uniformity, the coating films are also easily dispersed within the base film resin after remelting, thereby reducing the generation of foreign matter.

[0043] Furthermore, it is believed that by preparing a release layer containing a cured organosilicon with a phenyl siloxane structure, it is easy to arrange phenyl groups on the substrate side and methyl groups on the surface of the release layer, thereby producing a release film with improved peelability and excellent substrate adhesion. Detailed Implementation

[0044] The present invention will now be described in detail.

[0045] <Polyester Film>

[0046] The polyester constituting the polyester film used as a substrate film is not particularly limited, and polyester obtained by film forming of polyester commonly used as a substrate for release films can be used. Preferably, it is a crystalline linear saturated polyester containing aromatic dicarboxylic acid and glycol components, such as polyethylene terephthalate, polyethylene 2,6-naphthalenedicarboxylate, polyethylene terephthalate, polyethylene terephthalate, propylene terephthalate, or copolymers with components of these resins as the main components. Polyester films formed from polyethylene terephthalate are particularly preferred. In polyethylene terephthalate, the repeating unit of polyethylene terephthalate is preferably 90 mol% or more, more preferably 95 mol% or more, and small amounts of other dicarboxylic acid components and glycol components may also be copolymerized. For example, from a cost perspective, it is preferable to manufacture it only from terephthalic acid and ethylene glycol. Furthermore, known additives, such as antioxidants, light stabilizers, ultraviolet absorbers, and crystallizing agents, can be added to the extent that they do not impair the effect of the release film of the present invention. Considering the high biaxial elastic modulus, the polyester film is preferably a biaxially oriented polyester film.

[0047] The intrinsic viscosity of the aforementioned polyester film is preferably 0.50 dl / g or higher and 0.70 dl / g or lower, more preferably 0.52 dl / g or higher and 0.62 dl / g or lower. An intrinsic viscosity of 0.50 dl / g or higher is preferred as it minimizes breakage during the stretching process. Conversely, an intrinsic viscosity of 0.70 dl / g or lower provides good cutability when cut to the specified product width, preventing dimensional defects. Furthermore, the raw material granules are preferably thoroughly vacuum-dried.

[0048] It should be noted that in this specification, when referred to only as "polyester film", it sometimes refers to a polyester film having (layered) surface layer A and surface layer B.

[0049] The method for manufacturing the polyester film in this invention is not particularly limited, and conventionally used methods can be used. For example, the aforementioned polyester can be melted in an extruder, extruded into a film, cooled with a rotary cooling drum to obtain an unstretched film, and then biaxially stretched. The biaxially stretched film can be obtained by sequentially biaxially stretching a longitudinally or transversely uniaxially stretched film in the transverse or longitudinal direction, or by simultaneously biaxially stretching an unstretched film in both the longitudinal and transverse directions.

[0050] In this invention, the stretching temperature during polyester film stretching is preferably above the secondary transformation point (Tg) of the polyester. Preferably, the stretching is performed by more than 1 and less than 8 times, particularly more than 2 and less than 6 times, in both the longitudinal and transverse directions.

[0051] The thickness of the aforementioned polyester film is preferably 12 μm or more and 50 μm or less, more preferably 15 μm or more and 38 μm or less, and even more preferably 19 μm or more and 33 μm or less. If the film thickness is 12 μm or more, it will not deform due to heat during film production, processing, or molding, which is preferable. On the other hand, if the film thickness is 50 μm or less, the amount of waste film after use will not increase drastically, which is preferable in terms of reducing environmental impact.

[0052] 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.

[0053] In this method, surface layer A may contain particles with a diameter of less than 1.0 μm and greater than 1 nm. By making surface layer A substantially free of particles with a diameter of 1.0 μm or greater, such as inorganic particles, it is possible to reduce defects caused by the transfer of particle shapes from the substrate to the resin sheet.

[0054] In one approach, surface layer A also does not contain particles with a diameter less than 1.0 μm, thereby more effectively suppressing defects caused by the transfer of particle shape from the substrate to the resin sheet.

[0055] 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 allows for more effective suppression of particle shapes in the substrate from being transferred to the resin sheet and causing defects.

[0056] For example, surface layer A, which is substantially free of particles smaller than 1.0 μm, is preferably also substantially free of particles larger than 1.0 μm.

[0057] In this invention, "substantially free of particles" means, for example, in the case of inorganic particles smaller than 1.0 μm, a content of 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 inorganic 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 can sometimes detach and mix into the film. Furthermore, "substantially free of particles with a diameter of 1.0 μm or larger" means actively free of particles with a diameter of 1.0 μm or larger.

[0058] In the case of a laminated polyester film consisting of two or more layers, it is preferable to have a surface layer B that can contain inorganic particles on the opposite side of the surface layer A, which is substantially free of inorganic particles.

[0059] As a laminated structure, 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 remaining core layers as layer C, the layer structure in the thickness direction can be exemplified by a release layer / A / B or a release layer / A / C / B laminated structure. Of course, layer C can also be a multi-layered structure. Furthermore, surface layer B may not contain inorganic particles. In this case, to impart slipperiness for winding the film into a roll, it is preferable to provide a coating containing inorganic particles and a binder on surface layer B.

[0060] In the polyester film substrate of the present invention, from the viewpoint of film slippage and ease of air expulsion, the surface layer B opposite to the side on which the release layer is formed preferably contains inorganic particles, and silica particles and / or calcium carbonate particles are particularly preferred. The content of inorganic particles contained is preferably 5000 ppm or more and 15000 ppm or less in the surface layer B, based on the total amount of inorganic particles.

[0061] At this point, the average surface roughness (Sa) of the thin film in the surface layer B is preferably in the range of 1 nm or more and 40 nm or less. More preferably, it is in the range of 5 nm or more and 35 nm or less. When the total amount of silica particles and / or calcium carbonate particles is 5000 ppm or more and Sa is 1 nm or more, air can be uniformly dispersed when the film is wound into a roll, resulting in a good winding shape and good planarity, thus making it suitable for the manufacture of ultrathin ceramic green sheets. 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, lubricant aggregation is less likely to occur, and coarse protrusions are not formed, thus ensuring stable quality during the manufacture of ultrathin ceramic green sheets, which is preferred.

[0062] In addition to silica and / or calcium carbonate, inactive inorganic particles and / or heat-resistant organic particles can also be used as particles in layer B. From the viewpoints of transparency and cost, silica particles and / or calcium carbonate particles are preferred. Other usable inorganic particles include alumina-silica composite oxide particles and hydroxyapatite particles. Heat-resistant organic particles include cross-linked polyacrylic acid particles, cross-linked polystyrene particles, and benzoguanamine particles. When using silica particles, porous colloidal silica is preferred. When using calcium carbonate particles, from the viewpoint of preventing lubricant detachment, light calcium carbonate with a surface treatment using a polyacrylic acid-based polymer is preferred.

[0063] The average particle size of the inorganic particles added to the surface layer B is preferably 0.1 μm or more and 2.0 μm or less, particularly preferably 0.5 μm or more and 1.0 μm or less. If the average particle size of the inorganic particles is 0.1 μm or more, the release film exhibits good sliding properties, which is therefore preferred. Furthermore, if the average particle size is 2.0 μm or less, there is no concern about adversely affecting the smoothness of the release layer surface, and therefore no concern about pinholes forming on the ceramic green sheet, which is also preferred.

[0064] From the perspective of reducing pinholes, in order to prevent the mixing of inorganic particles such as lubricants, it is preferable not to use recycled materials in the layer on the side where the above-mentioned release layer is set, namely surface layer A.

[0065] The thickness ratio of surface layer A, which is the layer on the side where the above-mentioned release layer is provided, is preferably 20% or more and 50% or less of the total thickness of the substrate film. If it is 20% or more, it is less likely to be affected by particles contained in surface layer B, etc., from inside the film, and the average surface roughness Sa of the region is more likely to meet the above range, which is preferred. If it is 50% or less of the total thickness of the substrate film, the utilization rate of recycled materials in surface layer B can be increased, resulting in a lower environmental impact, which is also preferred.

[0066] Furthermore, from an economic point of view, the layers other than surface layer A (surface layer B or the aforementioned intermediate layer C) can use 50% by mass and 90% by mass of recycled materials from film scraps and plastic bottles. In this case, the type, amount, particle size, and average surface roughness (Sa) of the lubricant contained in layer B preferably also meet the above-mentioned ranges.

[0067] In addition, in order to improve the adhesion of the release layer and other coatings applied later and to prevent static electricity, a coating may be applied to the surface of surface layer A and / or surface layer B before stretching or after uniaxial stretching in the film-making process, or surface treatment may be performed.

[0068] In one approach, to improve adhesion to the release layer, a surface treatment can be applied to the surface of the release layer formed by coating the water-based paint composition, and an easy-adhesion layer can be provided. Examples of surface treatments include plasma treatment, corona discharge treatment, ultraviolet treatment, flame treatment, and electron beam / radiation treatment. Examples of easy-adhesion layers include layers containing the same resin as the substrate film and also containing antistatic agents, pigments, surfactants, lubricants, anti-blocking agents, etc. When an adhesion improver such as a coupling agent is added to the water-based paint composition, the release layer can achieve sufficient adhesion to the substrate film even without an easy-adhesion layer.

[0069] <Mold Release Layer>

[0070] In this invention, a release layer is laminated onto a substrate film, for example, the release layer is laminated onto surface layer A of the substrate. The release layer of this invention is a layer formed by reacting and curing a water-based coating composition.

[0071] The waterborne coating composition comprises: an alkenyl organosilicon (A) having a number average molecular weight of 1,000 or more and 14,000 or less; and a Si-H organosilicon (B) having a phenyl group, wherein the Si-H organosilicon (B) is represented by the following general formula (I).

[0072]

[0073] (In formula (I), a1 is a natural number selected from 1 to 50, b1 is a natural number selected from 1 to 50, and c1 is a natural number selected from 0 to 50.)

[0074] The release layer may be a Si-H-based organosilicon (C) without phenyl groups (e.g., sometimes referred to as a phenyl-free Si-H-based organosilicon (C)).

[0075] By using both a Si-H-based organosilicon (C) without phenyl groups and a Si-H-based organosilicon (B) with phenyl groups, compared to using only a Si-H-based organosilicon (B) with phenyl groups, the arrangement of methyl groups on the surface of the release layer can be controlled, thus controlling the wettability and peelability of the ceramic slurry, which is therefore preferred. Furthermore, the number of crosslinking reaction points increases, the cohesive force of the release layer becomes greater, and the abrasion resistance and solvent resistance of the release layer also improve, which is also preferred.

[0076] (Contains alkenyl organosilicon (A))

[0077] As an alkenyl-containing organosilicon (A), it is an organopolysiloxane represented by the following general formula (II).

[0078]

[0079] (In general formula (II), R1 is an alkenyl group, which may be the same or different, having 2 or more but less than 8 carbon atoms, or a monovalent hydrocarbon group containing an alkyl or phenyl group, having 1 or more but less than 16 carbon atoms, wherein, with [SiO] a2 The R1 bonded to the silicon atom shown is not an alkenyl group, but rather [SiO]. c2 At least one of the silicon atoms bonded in R1 is the aforementioned alkenyl group.

[0080] With [SiO] b2 The silicon atoms bonded to Y1 may be the same or different, and may be an alkenyl group with 2 or more but less than 8 carbon atoms, or a monovalent hydrocarbon group containing alkyl or phenyl groups with 1 or more but less than 16 carbon atoms, or represented by the following general formula (III).

[0081] In general formula (III), R1 is optionally the same group as at least one R1 in general formula (II). In addition, in general formula (III), R1 may be the same or different.

[0082] When the total of a2, b2, c2, and all d2 is set to 100 mol%, then a2 is 1 mol% or more, b2 is 0 mol% or more, c2 is 0 mol% or more, and d2 is 0 mol% or more.

[0083]

[0084] [SiO] of general formula (II) a2 [SiO] c2 [SiO] of general formula (III) d1 The R1 group, which is bonded to silicon atoms, is preferably an alkenyl group with 2 or more but less than 8 carbon atoms, or a monovalent hydrocarbon group containing an alkyl or phenyl group. For example, with [SiO]. a2 [SiO] c2 [SiO] d1 In the silicon atom bonded R1 shown, one or more of them are alkenyl groups with 2 or more but less than 8 carbon atoms.

[0085] By making one or more of R1 above an alkenyl group having 2 or more but less than 8 carbon atoms, it can react with [SiO] of general formula (I). a1 The hydrogen-based reaction of silicon atoms shown can achieve the effect of forming cross-linked structures.

[0086] In one embodiment, the terminal R1 may also be an alkenyl group with 2 or more but less than 8 carbon atoms, or a monovalent hydrocarbon group containing an alkyl or phenyl group. For example, the terminal R1 is preferably an alkenyl group or a methyl group with 2 or more but less than 8 carbon atoms. The steric hindrance of the terminal alkenyl group becomes relatively small when it reacts with the Si-H group, which facilitates the improvement of exfoliation properties, and is therefore particularly preferred.

[0087] Examples of alkenyl groups with 2 or more but less than 8 carbon atoms as represented by R1 include vinyl, phenyl, butenyl, pentenyl and hexenyl, among which vinyl is particularly preferred.

[0088] In general formulas (II) and (III), [SiO] a2 [SiO] b2 [SiO] c2 [SiO] d1 Assuming the total structural units are 100 mol%, [SiO] is considered... b2 The range of structural units can be 0 mol%, preferably 1 mol% or more and 99 mol% or less, and more preferably 2 mol% or more and 80 mol% or less. For example, [SiO]b2 The range of structural units can be 2 mol% or more and 50 mol% or less, or 2 mol% or more and 40 mol% or less.

[0089] Furthermore, [SiO] is preferred. b2 The structural units are within the range described above, and the number-average molecular weight of the alkenyl organosilicon (A) is within the range described in this specification. If it is within the range described above, the ratio of branched structures is appropriate, so that the hydrocarbon groups are locally present on the coating surface and form a dense film, resulting in good peelability and wettability.

[0090] When the total of a2, b2, c2 and all d2 in general formulas (II) and (III) is set to 100 mol%, it is preferable that a2 is 1 mol% or more, c2 is 0 mol% or more, and d2 is 0 mol% or more. In particular, from the viewpoint of achieving a balance between the crosslinking density and surface free energy of the release layer, it is more preferable that a2 is 2 mol% or more and 90 mol% or less, c2 is 5 mol% or more and 90 mol% or less, and d2 is 10 mol% or more and 90 mol% or less, and even more preferably that a2 is 5 mol% or more and 50 mol% or less, c2 is 10 mol% or more and 50 mol% or less, and d2 is 30 mol% or more and 50 mol% or less.

[0091] The number average molecular weight of the alkenyl organosilicon (A) is 1,000 or more and 14,000 or less, for example, 1,000 or more and 12,000 or less, 1,000 or more and 11,000 or more and 10,000 or less, for example, 1,000 or more and less than 10,000.

[0092] In another approach, the number average molecular weight of the alkenyl organosilicon (A) can be above 2000 and below 12,000, or above 2500 and below 12,000.

[0093] When the number average molecular weight is 1,000 or higher, hydrocarbon groups are locally present on the coating surface, making it easy to achieve sufficient peelability. On the other hand, when the number average molecular weight is 14,000 or lower, there is a tendency for the emulsification properties, wetting properties, and uniform coating properties of the water-based coating composition to become better.

[0094] In the alkenyl-containing organosilicon (A), the alkenyl group can be introduced at any of the single-end, double-end, or side chain locations. The alkenyl group is present in the molecule at two or more sites, preferably two or more and 20 or less, more preferably two or more and 10 or less. If there are two or more sites, a cross-linked structure can be formed, ensuring a sufficient amount of cross-linking reaction points. If there are 20 or less sites, deviations in the cross-linked structure can be reduced, resulting in uniform peelability. For example, the alkenyl group is introduced at the single-end or double-end locations. Furthermore, an appropriate amount of cross-linking reaction points can reduce the size of foreign matter consisting of unmelted release layer contained in the reusable resin made from the release film, thus tending to improve reusability.

[0095] In the waterborne coating composition, relative to a total of 100 parts by mass of alkenyl-containing organosilicon (A) and phenyl-containing Si-H-based organosilicon (B), it is preferable to include 3 parts by mass and 30 parts by mass of phenyl-containing Si-H-based organosilicon (B), more preferably 4 parts by mass and 20 parts by mass, and even more preferably 4.5 parts by mass and 15 parts by mass and below. When the content of Si-H-based organosilicon (B) is 3 parts by mass or more, the crosslinking reaction sites are sufficient, making it easy to form a dense crosslinked structure and improving peelability, which is therefore preferred. When the content of Si-H-based organosilicon (B) is 30 parts by mass or less, Si-H groups in the release layer are less likely to remain, the activity of the release layer surface is less likely to increase, and peelability is well maintained, which is also preferred.

[0096] For example, for an alkenyl organosilicon (A), the release layer may contain a plurality of organosilicones (A) having the molecular weight described in this invention.

[0097] In another embodiment, the waterborne coating composition of the present invention may contain a phenyl-free Si-H-based organosilicon (C). In this embodiment, the amount of alkenyl organosilicon (A) contained in the waterborne coating composition is preferably 70 parts by mass or more and 95 parts by mass or less, more than 75 parts by mass or less and 93 parts by mass or less, and more preferably 75 parts by mass or more and 88 parts by mass or less, relative to a total of 100 parts by mass of alkenyl organosilicon (A), Si-H-based organosilicon (B), and phenyl-free Si-H-based organosilicon (C). By exhibiting such a mixing amount, the crosslinking reaction points are sufficient, the cohesive force of the release layer is increased, and the abrasion resistance and solvent resistance of the release layer are also improved, which is therefore preferred.

[0098] As an alkenyl-containing organosilicon (A), a branched structure is preferred. By having a branched structure, the release layer becomes a dense structure, resulting in good peelability, and is therefore preferred.

[0099] (B) Si-H group-containing organosilicon compounds with phenyl groups

[0100] The Si-H-based organosilicon (B) containing phenyl groups is an organohydrogen polysiloxane represented by the following general formula (I).

[0101]

[0102] (In formula (I), a1 is a natural number selected from 1 to 50, b1 is a natural number selected from 1 to 50, and c1 is a natural number selected from 0 to 50.)

[0103] As a Si-H-containing organosilicon (B) with a phenyl group, it is preferable to have two or more Si-H groups (i.e., two or more hydrogen atoms directly bonded to Si atoms) within the molecule. In addition, the terminal silicon atom is preferably a trialkylsilane structure such as trimethylsilane.

[0104] In the Si-H-based organosilicon (B) represented by general formula (I), [SiO] a1 [SiO] b1 and [SiO] c1 When the total number of structural units is set to 100 mol%, [SiO] a1 The structural unit percentage is preferably 40 mol% or more and 80 mol% or less, more preferably 50 mol% or more and 70 mol% or less. [SiO] a1 When the structural unit content is 40 mol% or more, the crosslinking reaction points become sufficient, the cohesive force of the release layer increases, and the wipe resistance and solvent resistance of the release layer also become good, which is the preferred option.

[0105] In the Si-H-based organosilicon (B) represented by general formula (I), [SiO] with a phenyl group is present. b1 The structural unit percentage is preferably 10 mol% or more and 40 mol% or less, more preferably 15 mol% or more and 35 mol% or less. [SiO] containing phenyl groups. b1 When the structural unit content is 10 mol% or more, the rapid curing reaction caused by the steric hindrance of the phenyl group can be suppressed, for example, the rapid curing of the release layer before the substrate film is stretched can be suppressed. As a result, the stretchability of the coating composition can be maintained, and the reduction in the adhesion between the release layer and the substrate caused by the stress difference between the substrate film and the release layer is not observed, which is preferred. In addition, the phenyl group in the Si-H-based organosilicon (B) interacts with the π electrons of the aromatic ring in the substrate, and the adhesion between the substrate and the release layer becomes good through the stacking effect. Furthermore, by arranging the phenyl group on the substrate side, the methyl group is easily arranged on the surface of the release layer, and the peelability becomes good.

[0106] In the Si-H-based organosilicon (B) represented by general formula (I), [SiO] is used as... c1The range of structural units is preferably 3 mol% or more and 30 mol% or less, more preferably 5 mol% or more and 20 mol% or less. When the structural units are 3 mol% or more, the amount of methyl groups locally present on the surface of the release layer increases, and the peelability becomes better, therefore it is preferred.

[0107] The number average molecular weight of the Si-H-based organosilicon (B) of the present invention is preferably 1,000 or more and 5,000 or less, more preferably 1,000 or more and less than 5,000, for example 1,500 or more and 4,000 or less, or 2,000 or more and 4,000 or less.

[0108] When the number average molecular weight is 1,000 or higher, sufficient peelability is easily obtained. On the other hand, when the number average molecular weight is 5,000 or lower, there is a tendency for the emulsification properties of the water-based coating composition to become better, and the coating uniformity also becomes better. Furthermore, the crosslinking reaction can be carried out appropriately, without reacting during stretching, but reacting efficiently after stretching. Therefore, there are fewer residual Si-H groups in the release layer, resulting in better peelability.

[0109] In the waterborne coating composition, relative to 100 parts by mass of alkenyl silicone (A) and Si-H silicone (B), it is preferable to include 3 or more but less than 30 parts by mass of Si-H silicone (B), more preferably 4 or more but less than 20 parts by mass, and even more preferably 4.5 or more but less than 15 parts by mass. When the content of Si-H silicone (B) is 3 or more parts by mass, the crosslinking reaction sites are sufficient, making it easy to form a dense crosslinked structure and improving peelability, thus it is preferred. When the content of Si-H silicone (B) is 30 parts by mass or less, Si-H groups in the release layer are less likely to remain, the activity of the release layer surface is less likely to increase, and peelability is well maintained, thus it is preferred.

[0110] Compared to using only Si-H-based organosilicon (C) without phenyl groups, the adhesion of the release layer is improved by incorporating Si-H-based organosilicon with phenyl groups (B). The reason for this is not yet certain, but it is believed that the phenyl groups segregate on the substrate side where the structures are similar, allowing intermolecular forces to play a role and facilitating their immobilization. Simultaneously, it is believed that the methyl groups segregate on the surface side, improving peelability.

[0111] (Phenyl-free, Si-H-based organosilicon (C))

[0112] The release layer may be a Si-H-based silicone (C) without phenyl groups (e.g., sometimes referred to as a Si-H-based silicone (C) without phenyl groups).

[0113] As a phenyl-free, Si-H-based organosilicon (C), an organohydrogen polysiloxane of the following general formula (IV) can be exemplified.

[0114]

[0115] (In formula (IV), a3 is a natural number selected from 1 to 50, and b3 is a natural number selected from 10 to 80.)

[0116] In the Si-H-based organosilicon (C) without phenyl groups as shown in general formula (IV), [SiO] a3 With [SiO] b3 When the total number of structural units is set to 100 mol%, it is considered as [SiO]. a3 The range of structural units is preferably 40 mol% or more and 80 mol% or less, more preferably 45 mol% or more and 70 mol% or less. [SiO] a3 When the structural unit content is 40 mol% or higher, the crosslinking reaction sites become sufficient, the cohesive force of the release layer increases, and the wipe resistance and solvent resistance of the release layer also become good, therefore it is preferred. [SiO] b3 The range of structural units is preferably 20 mol% or more and 60 mol% or less, more preferably 30 mol% or more and 55 mol% or less. [SiO] b3 When the structural unit is 20 mol% or more, the amount of methyl groups locally present on the surface of the release layer increases, and the peelability becomes better, so it is preferred.

[0117] The number-average molecular weight of the phenyl-free Si-H-based organosilicon (C) in this invention is preferably 1,000 or more and 10,000 or less, more preferably 2,000 or more and 8,000 or less. When the number-average molecular weight is 1,000 or more, sufficient peelability is easily obtained. On the other hand, when the number-average molecular weight is 10,000 or less, there is a tendency for the emulsification properties of the water-based coating composition to become better, and the coating uniformity to also become better.

[0118] In the waterborne coating composition, relative to a total of 100 parts by mass of alkenyl-containing organosilicon (A) and phenyl-free Si-H-containing organosilicon (C), it is preferable to contain 1 part by mass and 30 parts by mass of phenyl-free Si-H-containing organosilicon (C), more preferably 3 parts by mass and 20 parts by mass, and even more preferably 5 parts by mass and 15 parts by mass. When the content of phenyl-free Si-H-containing organosilicon (C) is 1 part by mass or more, the crosslinking reaction sites are sufficient, making it easy to form a dense crosslinked structure and improving peelability, which is therefore preferred. When the content of phenyl-free Si-H-containing organosilicon (C) is 30 parts by mass or less, the Si-H groups in the release layer become less likely to remain, and the amount of uncrosslinked material decreases, thus maintaining good peelability, which is also preferred.

[0119] In one embodiment, when the total amount of the phenyl-containing Si-H-based organosilicon (B) and the non-phenyl-containing Si-H-based organosilicon (C) in the waterborne coating composition is set to 100 parts by mass, it is preferable to include 30 parts by mass and 80 parts by mass of component (B), more preferably 32 parts by mass and 75 parts by mass, and even more preferably 34 parts by mass and 70 parts by mass. When component (B) is included in the amount of 30 parts by mass or more, the reaction can be controlled by the volume of the phenyl group, which can reduce the amount of crosslinking reaction points. Therefore, the amount of foreign matter derived from the reusable resin used in the release film is reduced, and the reusability is improved. When component (B) is 80 parts by mass or less, the amount of crosslinking reaction points is sufficient, the cohesive force of the release layer is increased, and the abrasion resistance and solvent resistance of the release layer are also good, which is preferable.

[0120] (Platinum group catalysts)

[0121] The crosslinking reaction between alkenyl organosilicon (A) and Si-H organosilicon (B) is an addition reaction. In one approach, a platinum-based catalyst is preferably used to promote the reaction.

[0122] As a platinum-based catalyst, well-known catalysts can be used, such as chloroplatinum and chloroplatinic acid. Considering the dispersibility in organosilicon, the platinum-based catalyst can use 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum(0) complex (Karstedt catalyst), which can ensure uniform dispersion by dispersing it simultaneously during organosilicon emulsification.

[0123] Regarding the content of the platinum-based catalyst, it is preferably within a range of 10 ppm to 400 ppm by mass of platinum relative to the total mass of the alkenyl-containing organosilicon (A) and the Si-H-containing organosilicon (B). By setting this range, sufficient curing of the organosilicon can be achieved, and the formation of organosilicon aggregates can be suppressed, resulting in a release film with excellent surface properties. When the mass ratio of platinum is below the upper limit, the addition reaction between the alkenyl and Si-H groups becomes moderate, tending to suppress the formation of organosilicon aggregates. From this viewpoint, the content of the platinum-based catalyst is more preferably 300 ppm or less, and even more preferably 200 ppm or less. Furthermore, when the mass ratio of platinum is above the lower limit, the addition reaction proceeds sufficiently, and poor curing of the organosilicon is less likely to occur. From this viewpoint, the content of the platinum catalyst is more preferably 15 ppm or more, and even more preferably 20 ppm or more.

[0124] (Aqueous solvent)

[0125] In waterborne coating compositions, in addition to alkenyl-containing organosilicon (A) and Si-H-containing organosilicon (B), an aqueous solvent is usually also contained, preferably a solvent containing water. In one embodiment, an aqueous dispersion of alkenyl-containing organosilicon (A) and an aqueous dispersion of Si-H-containing organosilicon (B) are used to prepare the waterborne coating composition. As the aqueous dispersion of each organosilicon, an aqueous emulsion is preferably used.

[0126] The waterborne coating composition is preferably substantially free of organic solvents and uses water as the dispersion medium. By being substantially free of organic solvents, the stability of the silicone emulsion is improved, preventing compositional changes in the waterborne coating composition, resin aggregation in the silicone emulsion, and gelation caused by emulsion breakdown.

[0127] Essentially, "free of organic solvents" means, for example, that the content in the total weight of the water-based coating composition is 10,000 ppm or less, preferably 5,000 ppm or less, more preferably 3,000 ppm or less, and most preferably below the detection limit. This is because, even without intentional use of organic solvents, small amounts of organic solvents used in the polymerization process of the resin contained in the silicone emulsion, the emulsification process of the emulsion, etc., may sometimes remain.

[0128] By using an emulsion containing an aqueous solvent, i.e., an organosilicon resin dispersed in water, coating can be performed without adverse effects on the human body or the environment.

[0129] (Other ingredients)

[0130] In one approach, without impairing the effectiveness of the invention, surfactants, coupling agents, crosslinking reaction inhibitors, antistatic agents, ultraviolet absorbers, pigments, colorants, organic or inorganic particles, lubricants, anti-blocking agents, and other additives may be mixed into the waterborne coating composition.

[0131] (surfactant)

[0132] In one approach, to promote wetting of the substrate film during the application of the release layer, it is preferable to add a surfactant to the aqueous coating composition. Examples of such surfactants include anionic surfactants, cationic surfactants, and nonionic surfactants; one or more of these may also be used. To prevent the aggregation of the aqueous emulsions of the silicones and to avoid affecting the curing reaction of the silicones, a nonionic surfactant is preferably used as the emulsifier.

[0133] As a nonionic surfactant, an HLB value in the range of 6 or higher and 18 or lower is preferred. Examples include at least one type selected from alkylene oxide adducts of higher alcohols or higher fatty acids, esters of alkylene oxide adducts of higher fatty acids and alcohols, alkylene oxide adducts of alkanolamides, alkylene oxide adducts of sorbitol esters, and alkylene oxide adducts of higher fatty acid glycerides. Here, the HLB value is calculated using Griffin's formula.

[0134] Examples of epoxy alkane include ethylene oxide, propylene oxide, and butane oxide; one or more of these can be used. When using multiple types, regardless of whether it is a block or random addition form, the HLB value is preferably in the range of 8 to 18, more preferably in the range of 10 to 15. Among these nonionic surfactants, polyoxyethylene lauryl ether and polyoxyethylene tridecyl ether are preferred examples. Two or more nonionic surfactants can also be mixed as needed. When using nonionic surfactants with HLB values ​​deviating from this range as emulsifiers for organosilicon aqueous dispersions, the emulsifying and dispersing power and the stability of the aqueous dispersion may sometimes decrease.

[0135] The surfactant is preferably used in a range of 0.1% by mass or more and 20% by mass or less relative to the total solids content, more preferably in a range of 0.2% by mass or more and 15% by mass or less, and even more preferably in a range of 0.5% by mass or more and 10% by mass or less. When the surfactant is above the lower limit of this range, the emulsification state becomes good, and when it is below the upper limit of this range, it is less likely to cause re-stripping.

[0136] (Cross-linking reaction inhibitor)

[0137] In one embodiment, to suppress the activity of the platinum-based catalyst at room temperature in an aqueous coating solution, a reaction inhibitor is preferably included. This reaction inhibitor is preferably a reaction inhibitor with an alkynyl group. As a reaction inhibitor with an alkynyl group, there is no particular limitation as long as it contains an alkynyl group; specifically, examples include 1-ethynyl-1-cyclohexanol, 4-ethyl-1-octyyn-3-ol, 3-methyl-1-dodecyn-3-ol, 3,7,11-trimethyl-1-dodecyn-3-ol, 1,1-diphenyl-2-propyn-3-ol, 3-ethyl-6-ethyl-1-nonyn-3-ol, 3-methyl-1-pentadenyyn-3-ol, 2,5-dimethyl-3-hexyn-2,5-diol, and 3-phenyl-1-butyn-3-ol. In this invention, since it is an aqueous coating solution, from the perspective of the balance between water affinity and solubility, coordination ability with platinum, and boiling point, the example reaction inhibitors with alkynyl and hydroxyl groups are preferred. Alternatively, platinum-based catalysts are sometimes mixed with common organopolysiloxanes to be added to aqueous coating solutions, and used as aqueous emulsions.

[0138] Relative to the mass of the waterborne coating composition used to form the release layer, the content of the crosslinking reaction inhibitor is preferably 5 ppm or more and 1000 ppm or less, more preferably 10 ppm or more and 700 ppm or less, and even more preferably 20 ppm or more and 500 ppm or less. When the content of the crosslinking reaction inhibitor is above the lower limit, there is a tendency for the pot life to be longer, for the silicone addition curing reaction to be difficult to carry out at room temperature, and for silicone aggregates to be difficult to form. On the other hand, when the content of the crosslinking reaction inhibitor is below the upper limit, silicone is less likely to transfer to the target material after peeling, and the amount of reaction inhibitor volatilized during heat treatment is reduced, thus reducing the likelihood of contamination inside the oven.

[0139] (Coupled agent)

[0140] In one approach, to improve the adhesion between the silicone component and the substrate film, a coupling agent can be added to the waterborne coating composition. As a coupling agent, for example, is a compound represented by the general formula YRSiX3, such as silane coupling agents. Here, Y is an organic functional group such as vinyl, epoxy, amino, mercapto, etc., and Y is particularly preferably epoxy or vinyl.

[0141] R is an alkylene group such as methylene, ethylene, or propylene, or a single bond. X is a hydrolyzable group such as methoxy, ethoxy, or acetoxy, or an alkyl group, wherein at least one of the three X's is a hydrolyzable group, preferably all three X's are hydrolyzable groups. Methoxy is preferred as a hydrolyzable group.

[0142] Preferred silane coupling agents include 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, and vinylmethyldimethoxysilane.

[0143] Other examples of coupling agents include organometallic compounds containing metals such as zirconium, titanium, and aluminum. These organometallic compounds are preferably classified as alkoxides, chelates, or acylates. Specific examples include zirconium tetraacetylacetonate, zirconium acetate, titanium acetylacetonate, triethanolamine titanate, and titanium lactate, but are not limited to these.

[0144] In addition, as a coupling agent, two or more coupling agents can be used together, such as silane coupling agents with Y being epoxy group and silane coupling agents with Y being vinyl group.

[0145] In one approach, the durable adhesion between silicone, a major component of the release layer, and polyester film, is improved by adding a coupling agent. For example, in the casting of resin sheets using a solution casting method with organic solvents, the organic solvent components sometimes penetrate into the release layer, potentially causing it to be eroded. However, adding a coupling agent can suppress this erosion. Similarly, in the casting of resin sheets using a melt casting method at high temperatures, the release layer is exposed to high temperatures and may experience thermal degradation. However, adding a coupling agent can suppress this thermal degradation and maintain the release layer's integrity.

[0146] Based on the above viewpoint, the content of the coupling agent is preferably 0.1 parts by mass or more and 20 parts by mass or less, and more preferably 1 part by mass or more and 10 parts by mass or less, relative to a total of 100 parts by mass of alkenyl-containing organosilicon and Si-H-containing organosilicon contained in the release layer.

[0147] (Preparation of organosilicon aqueous dispersions)

[0148] In one approach, the preparation of an aqueous emulsion may involve emulsification using a specified alkenyl-containing or Si-H-containing organosilicon, an aqueous solvent, and a surfactant. The emulsification of these components can be performed using known methods, such as mechanical emulsification of pre-prepared specified organosilicon, surfactant, and other desired components in an aqueous medium using a homogenizer, a vacuum emulsifier (AGI-HOMO MIXER), an Ultra Planetary Mixer, or other stirring devices.

[0149] In addition, the particle size of the aqueous dispersion can be adjusted by changing the size of the stirring blades, the stirring speed, and the stirring time. The average particle size of the dispersed particles in each organosilicon aqueous dispersion is preferably 900 nm or less, more preferably 100 nm or more and 800 nm or less.

[0150] <Formation of the release layer>

[0151] In one embodiment, the release layer is formed by applying an aqueous coating composition comprising an aqueous emulsion containing alkenyl silicone and an aqueous emulsion containing Si-H silicone. In this case, the release layer is formed on at least one side of the substrate film. Regarding the release layer, after applying the aqueous coating liquid to the substrate film, heating / drying is performed to form a release layer resulting from the reaction and curing of the components of the aqueous coating liquid. The release layer is preferably formed during the film-forming process.

[0152] The thickness of the release layer, measured after drying, is preferably 5 nm or more and 100 nm or less. When the thickness of the release layer is above the lower limit, sufficient peelability is easily obtained; however, when it is below the upper limit, there is a tendency for the peel strength to not increase easily. Furthermore, there is a tendency for easy coating as there is no need to make the release layer component of the aqueous coating liquid have a high concentration or increase the coating amount. Therefore, the thickness of the release layer is more preferably 5 nm or more and 70 nm or less, and even more preferably 5 nm or more and 50 nm or less.

[0153] When applying the aqueous coating solution to a substrate film, the solids concentration, based on the release layer component in the aqueous coating solution, is preferably 20% by mass or less, more preferably 1% by mass or more and 10% by mass or less. When the solids concentration of the release layer component in the aqueous coating solution is above the lower limit, film-forming properties tend to improve. Furthermore, when the solids concentration is below the upper limit, the stability of the aqueous coating solution and the appearance of the release layer tend to improve. Water is preferably used as the aqueous solvent for adjusting the solids concentration.

[0154] The aqueous coating solution applied to the substrate film to form a release layer can be carried out at any stage, preferably during the manufacturing process of the polyester film, and more preferably on the polyester film before orientation and crystallization are completed. Then, it can be stretched in at least one direction and then heat-treated to complete the crystal orientation.

[0155] Here, polyester films before crystal orientation are completed include: unstretched films; uniaxially oriented films formed by oriented unstretched films in either the longitudinal direction (hereinafter sometimes referred to as the film continuous film-forming direction, length direction, MD direction) or the transverse direction (hereinafter sometimes referred to as the direction orthogonal to the longitudinal direction, width direction, TD direction); and films formed by low-ratio stretching and orientation in both the longitudinal and transverse directions (biaxially stretched films before final stretching in the longitudinal or transverse direction to complete orientation crystallization), etc.

[0156] Preferably, an aqueous coating liquid is applied to an unstretched film or a uniaxially stretched film oriented in one direction, and so-called online coating is performed by directly applying longitudinal stretching and / or transverse stretching and heat setting. The release layer can be dried by a stretching process or heat setting treatment after coating, and a further drying process can be applied as needed. In addition, when a cured film is obtained by curing the composition using a catalyst, it can be cured by a stretching process or heat setting treatment, and a further curing process can be added as needed.

[0157] When coating an aqueous coating solution onto a polyester film, as a pretreatment to improve coating properties, it is preferable to perform physical treatments such as corona surface treatment, flame treatment, or plasma treatment on the film surface, or to use the above-mentioned emulsifier as a wetting agent together with the composition and to add a surfactant as a wetting agent.

[0158] As a coating method, any known coating method can be applied. For example, roller coating, gravure coating, roller brush coating, spray coating, air knife coating, impregnation coating, curtain coating, etc., can be used alone or in combination.

[0159] Properties of release film

[0160] In this invention, the surface free energy of the release layer in the experimental method described later is preferably 10 mJ / m. 2 Above and 40mJ / m 2 The following range is more preferably 12 mJ / m 2 Above and 38mJ / m 2 The following is a further preferred value: 14 mJ / m 2 Above and 36mJ / m 2 The following is particularly preferred: 15 mJ / m 2 Above and 35mJ / m 2 The following range applies. When the surface free energy of the release layer is below the upper limit, the adhesion decreases, making it difficult to re-peel. Conversely, when it is above the lower limit, defects caused by shrinkage cavities from processing layers such as ceramic or resin sheets coated on the surface of the release layer are less likely to occur, and pinhole defects are also less likely to occur.

[0161] <Applications>

[0162] The release film of this invention can be used as a process film in the manufacture of multilayer ceramic capacitors, the casting of resin sheets, etc. For example, it can also be called a release film for multilayer ceramic capacitors or a release film for resin sheets.

[0163] In particular, even when producing thin film resin sheets with a thickness of less than 1 μm after drying, the wettability is good, thus reducing pinholes in the processed layer. For example, in the case of release films used for green film manufacturing, it can reduce the defect rate of thin-walled multilayer ceramic capacitors.

[0164] Example

[0165] The present invention will be described in more detail below with examples and comparative examples, but the invention is not limited to the following examples. It should be noted that the methods for evaluating physical properties, etc., in the following examples are as described below.

[0166] (1) Surface free energy of the release layer

[0167] For samples conditioned at 23°C and 50%RH for 24 hours, the static contact angle was measured using a contact angle meter (DMo-501, Kyowa Interface Chemicals Co., Ltd.) after adding water and allowing it to stand for 30 seconds. Similarly, the static contact angles of ethylene glycol and diiodomethane were measured separately. Using the surface tension components of each liquid, the following simultaneous equations were established regarding the surface tension components of the release layer (the test solutions of water, ethylene glycol, and diiodomethane are designated as 1, 2, and 3, respectively; γLD is the dispersing force component of the liquid; γLP is the polar force component of the liquid; γLH is the hydrogen bonding component of the liquid; γL is the sum of all surface tension components in the liquid; γSD represents the dispersing force component of the release layer; γSP represents the polar force component of the release layer; γSH represents the hydrogen bonding component of the release layer; and θ represents the contact angle).

[0168]

[0169] It should be noted that the γLD, γLP, γLH, and γL of water, ethylene glycol, and diiodomethane are shown in Table 1.

[0170] [Table 1]

[0171]

[0172] Next, using the values ​​of γSD, γSP, and γSH obtained above, the surface free energy γS of the release layer surface is calculated using the following formula.

[0173] γS = γSD + γSP + γSH

[0174] (2) Uniformity of the release layer coating

[0175] Cut the release film into A4 sheets. When visually observing the release layer using fluorescent and halogen lamps, compare the number of aggregated coating defects (number per A4 sheet) and evaluate according to the following criteria.

[0176] ○: Coating defects number 3 or fewer

[0177] △: Coating defects number 3 to 5

[0178] ×: There are 6 or more coating defects.

[0179] (3) Ceramic sheet peelability

[0180] 100 parts by weight of barium titanate (BaTiO3, manufactured by Kyoritsu Materials Co., Ltd.), 7 parts by weight of polyvinyl butyral (manufactured by Sekisui Chemicals Co., Ltd.), 3 parts by weight of dioctyl phthalate, and 3 parts by weight of dispersant (DISPERBYK-103, manufactured by BYK-Chemie Co., Ltd.) were added to a toluene:ethanol mixture of 1:1 (volume ratio) and dispersed using a ball mill to prepare a slurry. This slurry was then uniformly coated onto the release layer of a release film to a thickness of 2 μm after drying, and allowed to dry to form a ceramic sheet. The release film with the ceramic sheet was cut into 30 mm × 80 mm pieces to prepare test pieces. Next, the ceramic sheet was peeled using a tensile testing machine at a peel angle of 180° and a peel speed of 10 m / min to determine the peel strength. The peel strength of the ceramic sheet was judged according to the following indicators.

[0181] ◎: Peel strength less than 1 mN / mm

[0182] 〇: Peel strength is above 1 mN / mm and less than 1.5 mN / mm

[0183] △: Peel strength is ≥1.5mN / mm and <2.0mN / mm

[0184] ×: Peel strength is above 2.0 mN / mm

[0185] (4) Peeling test of the release layer (adhesion)

[0186] Rub the release surface of the release film with your thumb 10 times with a load of about 500gf. To confirm the removal of silicone from this part, apply adhesive tape (manufactured by Nitto Denko Corporation, trade name "31B tape") and check the peeling condition of the adhesive tape. Evaluate according to the following criteria.

[0187] ○: When the adhesive tape is peeled off, the peel change is less than 1.5 times.

[0188] △: When the adhesive tape is peeled off, the peel change is more than 1.5 times but less than 2 times.

[0189] ×: When the adhesive tape is peeled off, the peeling change is more than 2 times.

[0190] (5) Reusability evaluation

[0191] Regarding reusability, the size and number of foreign objects contained in the film were magnified 20 times using a universal projector, and the number of foreign objects with a maximum diameter of 50 μm or more was counted. The measurement area was 0.05 m². 2 .

[0192] 〇: Number of foreign objects less than 5 / 0.05m 2 There are no problems with its use.

[0193] △: The number of foreign objects is 5 to less than 10 per 0.05m 2 It has some impact on flatness, but its use can be limited to specific applications.

[0194] ×: The number of foreign objects is 10 per 0.05m 2 The above affects flatness and cannot be used.

[0195] (6) Number-average molecular weight

[0196] Determined by gel permeation chromatography (GPC) and calculated as a polystyrene equivalent.

[0197] (7) Thickness of the release layer

[0198] After cutting the release film into small triangular pieces, a 2 nm thick Pt (platinum) layer was formed on the surface of the release layer. The resulting sample was fixed in a multiaxial embedding capsule and embedded in epoxy resin. Using an ULTRACUT-S microtome, sections were cut perpendicular to the film's surface direction to obtain an ultrathin sample with a thickness of 50 nm. Next, the ultrathin sample was placed on a grid and vapor-stained with 2% osmium tetroxide at 60 °C for 2 hours. Using the vapor-stained ultrathin sample, the film cross-section was observed using a LEM-2000 transmission electron microscope at an accelerating voltage of 100 kV to determine the thickness of the release layer. Measurements were taken at any 10 points, and their average value was taken as the thickness of the release layer (unit: nm).

[0199] (Contains alkenyl organosilicon (A-1))

[0200] Using an emulsification device (manufactured by NP-Labo, device name "UltraPlanetary Mixer") capable of stirring the entire container, a raw material consisting of 95% by mass of silicone oil with a number average molecular weight of 3,000 and a concentration of a2 of 40 mol%, b2 of 5 mol%, c2 of 20 mol%, d1 of 35 mol%, and polyoxyethylene tridecyl ether (manufactured by LION SPECIALTY CHEMICALS CO., Ltd., trade name "LEOCOL TD-90") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion of sample (A-1) with a solid content of 50% by mass. Furthermore, by adjusting the stirring speed and stirring time during emulsification, the emulsion particle size was adjusted to an average particle size of 180 nm. It should be noted that in each embodiment, R1 of general formulas (II) and (III) is vinyl or methyl, and Y1 is silicone oil represented by general formula (III).

[0201]

[0202]

[0203] (Contains alkenyl organosilicon (A-2))

[0204] Using an emulsification device (manufactured by NP-Labo, device name "Ultra Planetary Mixer") capable of stirring the entire container, a raw material consisting of 35 mol% a2, 7 mol% b2, 20 mol% c2, 38 mol% d1 of general formula (II) and (III), 96 wt% silicone oil with a number average molecular weight of 6,000, and 4 wt% polyoxyethylene tridecyl ether (manufactured by LIONSPECIALTY CHEMICALS CO., Ltd., trade name "LEOCOL TD-90") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion sample (A-2) with a solid content of 50 wt%. Furthermore, by adjusting the stirring speed and stirring time during emulsification, the emulsion particle size was adjusted to an average particle size of 185 nm.

[0205] (Contains alkenyl organosilicon (A-3))

[0206] Using an emulsification device (manufactured by NP-Labo, device name "Ultra Planetary Mixer") capable of stirring the entire container, a raw material consisting of 30 mol% a2, 10 mol% b2, 30 mol% c2, 30 mol% d1 of general formulas (II) and (III), 96 wt% silicone oil with a number average molecular weight of 10,000, and 4 wt% polyoxyethylene tridecyl ether (manufactured by LIONSPECIALTY CHEMICALS CO., Ltd., trade name "LEOCOL TD-90") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion sample (A-3) with a solid content of 50 wt%. Furthermore, by adjusting the stirring speed and stirring time during emulsification, the emulsion particle size was adjusted to an average particle size of 190 nm.

[0207] (Contains alkenyl organosilicon (A-4))

[0208] Using an emulsification device (manufactured by NP-Labo, device name "UltraPlanetary Mixer") capable of stirring the entire container, a raw material consisting of 97% by mass of silicone oil of general formula (II) and (III) with a2 of 10 mol%, b2 of 20 mol%, c2 of 30 mol%, d1 of 40 mol% and a number average molecular weight of 500, and 3% by mass of polyoxyethylene tridecyl ether (manufactured by LION SPECIALTY CHEMICALS CO., Ltd., trade name "LEOCOL TD-90") as a surfactant, was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion sample (A-4) with a solid content of 50% by mass. Furthermore, by adjusting the stirring speed and stirring time during emulsification, the emulsion particle size was adjusted to an average particle size of 175 nm.

[0209] (Contains alkenyl organosilicon (A-5))

[0210] Using an emulsification device (manufactured by NP-Labo, device name "UltraPlanetary Mixer") capable of stirring the entire container, a raw material consisting of 94% by mass of silicone oil of general formulas (II) and (III) with a2 of 30 mol%, b2 of 10 mol%, c2 of 40 mol%, d1 of 20 mol% and a number average molecular weight of 15,000, and 6% by mass of polyoxyethylene tridecyl ether (manufactured by LION SPECIALTY CHEMICALS CO., Ltd., trade name "LEOCOL TD-90") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion sample (A-5) with a solid content of 50% by mass. Furthermore, by adjusting the stirring speed and stirring time during emulsification, the emulsion particle size was adjusted to an average particle size of 195 nm.

[0211] (Contains alkenyl organosilicon (A-6))

[0212] Using an emulsification device (manufactured by NP-Labo, device name "Ultra Planetary Mixer") capable of stirring the entire container, a raw material consisting of 92% by mass of silicone oil of general formulas (II) and (III) with a2 of 10 mol%, b2 of 30 mol%, c2 of 30 mol%, d1 of 30 mol% and a number average molecular weight of 20,000, and 8% by mass of polyoxyethylene tridecyl ether (manufactured by LIONSPECIALTY CHEMICALS CO., Ltd., trade name "LEOCOL TD-90") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion sample (A-3) with a solid content of 50% by mass. Furthermore, by adjusting the stirring speed and stirring time during emulsification, the emulsion particle size was adjusted to an average particle size of 210 nm.

[0213] (B-1) is a Si-H-containing organosilicon compound with phenyl groups.

[0214] Using an emulsification device (manufactured by NP-Labo, device name "Ultra PlanetaryMixer") capable of stirring the entire container, a raw material consisting of 60 mol% a1, 23 mol% b1, 11 mol% c1 of general formula (I), 95 wt% silicone oil with a number average molecular weight of 2,800, and 5 wt% polyoxyethylene lauryl ether (manufactured by Kao Corporation, trade name "EMULGEN 109P") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion sample (B-1) with a solid content of 40 wt%. Furthermore, by adjusting the stirring speed and stirring time during emulsification, the emulsion particle size was adjusted to an average particle size of 180 nm.

[0215]

[0216] (B-2) is a Si-H-containing organosilicon compound with phenyl groups.

[0217] Using an emulsification device (manufactured by NP-Labo, device name "UltraPlanetary Mixer") capable of stirring the entire container, a raw material consisting of 50 mol% a1, 30 mol% b1, and 20 mol% c1 of general formula (I) and 94 wt% silicone oil with a number average molecular weight of 4,000, and 6 wt% polyoxyethylene lauryl ether (manufactured by Kao Corporation, trade name "EMULGEN 109P") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion with a solid content of 40 wt% (sample B-2). Furthermore, by adjusting the stirring speed and stirring time during emulsification, the emulsion particle size was adjusted to an average particle size of 190 nm.

[0218] (Phenyl-free, Si-H-based organosilicon (C-1))

[0219] Using an emulsification device (manufactured by NP-Labo, device name "UltraPlanetary Mixer") capable of stirring the entire container, a raw material consisting of 42 mol% a3, 56 mol% b3, 96 wt% silicone oil of general formula (IV) with a number average molecular weight of 4,500, and 4 wt% polyoxyethylene lauryl ether (manufactured by Kao Corporation, trade name "EMULGEN 109P") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion sample (C-1) with a solid content of 40 wt%. Furthermore, by adjusting the stirring speed and stirring time during emulsification, the emulsion particle size was adjusted to an average particle size of 200 nm.

[0220]

[0221] (Phenyl-free, Si-H-based organosilicon (C-2))

[0222] Using an emulsification device (manufactured by NP-Labo, device name "UltraPlanetary Mixer") capable of stirring the entire container, a raw material consisting of 60 mol% a3, 40 mol% b3, 94 wt% silicone oil of general formula (IV) with a number average molecular weight of 9,000, and 6 wt% polyoxyethylene lauryl ether (manufactured by Kao Corporation, trade name "EMULGEN 109P") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion sample (C-2) with a solid content of 40 wt%. Furthermore, by adjusting the stirring speed and stirring time during emulsification, the emulsion particle size was adjusted to an average particle size of 210 nm.

[0223] <Example 1 of the manufacture of water-based coating compositions>

[0224] An alkenyl organosilicon (A-3), a Si-H organosilicon with phenyl groups (B-1), and water were mixed in the proportions described in Table 2 to achieve a solid content concentration of 4% by mass, to obtain an aqueous coating composition. At this time, relative to the total weight of the aqueous coating composition, 0.01% by mass of a platinum-based catalyst (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name: CAT-PM-10A) and 150 ppm of a crosslinking reaction inhibitor (1-ethynylcyclohexanol) were added.

[0225] <Examples 2-22 of the manufacture of waterborne coating compositions>

[0226] Except for mixing with the types and ratios listed in Table 2, the water-based coating composition was obtained by the same method as in Manufacturing Example 1.

[0227] <Example 1>

[0228] Polyethylene terephthalate ([η] = 0.64 dl / g, Tg = 78°C) containing 0.1% by mass of calcium carbonate particles with an average particle size of 0.6 μm was melted using an extruder, passed through a 10 μm filter, and extruded from a die. The film was then cooled using a cooling drum via conventional methods to produce an unstretched film. Next, the film was stretched longitudinally to 3.3 times its original length at 80°C, and then uniformly coated with the aqueous coating liquid (water-based paint composition) obtained in Manufacturing Example 1 using a roller coater, achieving the release layer thickness shown in Table 2. It should be noted that the aqueous coating liquid used was prepared within 24 hours of its initial preparation.

[0229] Next, the coated film was dried at 115°C, stretched laterally to 4.0 times its original size at 145°C, and further heat-set at 230°C for about 10 seconds to obtain a release film (25 μm thick) with a release layer formed by the reaction and curing of the aqueous coating liquid. Its evaluation was then carried out. The evaluation results are shown in Table 2.

[0230] It should be noted that in each embodiment and comparative example, the demolding film portion that did not become an article when collecting the article roll, and the demolding film that did not become an article due to defects, etc., were crushed to a film sheet with a long diameter of about 5 mm or less and melted, using 40% by mass of recycled raw materials.

[0231] <Examples 2-12>

[0232] Using the water-based coating compositions obtained by the same method as in Examples 2-12, except that release films were prepared under the exact same conditions as in Example 1, and the above evaluation was performed. Detailed conditions and evaluation results are shown in Table 2A.

[0233] <Comparative Examples 1-10>

[0234] In Comparative Examples 1-10, an organosilicon containing alkenyl group (A) with a molecular weight outside the scope of this invention was used, and the aqueous coating liquid obtained in Manufacturing Examples 13-22 was used. Except for this, release films were prepared under the exact same conditions as in Example 1, and the above evaluation was performed. Detailed conditions and evaluation results are shown in Table 2B.

[0235] In Example 1, the aqueous coating liquid obtained in Manufacturing Examples 6 to 10 was used instead of the aqueous coating liquid obtained in Manufacturing Example 1. Otherwise, a release film was made under the exact same conditions as in Example 1, and the above evaluation was performed.

[0236] [Table 2A]

[0237]

[0238] [Table 2B]

[0239]

[0240] As shown in Table 2, in Examples 2, 5-7, and 10, the peelability and wettability of the release layer were easily balanced, resulting in release films with good coating uniformity, reusability, and adhesion between the substrate and the release layer. Examples 1, 3, 4, 8, 9, 11, and 12 exhibited minimal physical properties. In contrast, in Comparative Examples 1, 6, and 9, where the main silicone component had a low molecular weight, there was a tendency for deterioration in reusability. In Comparative Examples 2, 3, 5, 7, 8, and 10, where the main silicone component had a high molecular weight, there was a tendency for poor coating uniformity and re-peeling of the ceramic sheet. In Comparative Example 4, which used only a formulation containing Si-H-based silicone (C-1) without phenyl groups, re-peeling of the ceramic sheet, poor adhesion, and poor reusability were observed.

[0241] Industrial availability

[0242] The release film of the present invention has the advantages of easily balancing the peelability and wettability of the release layer, high coating uniformity of the release layer, good reusability and excellent adhesion, and has extremely high industrial application value.

Claims

1. A release film having a base film and a release layer formed by reacting and curing an aqueous coating composition, the aqueous coating composition comprising: an alkenyl group-containing organosilicon (A) having a number average molecular weight of 1,000 or more and 14,000 or less; and an Si-H group-containing organosilicon (B) having a phenyl group, the Si-H group-containing organosilicon (B) being represented by general formula (I), in formula (I), a1 is a natural number selected from 1 to 50, b1 is a natural number selected from 1 to 50, and c1 is a natural number selected from 0 to 50.

2. The release film of claim 1, wherein, the Si-H group-containing organosilicon (B) comprising an Si-H group-containing organosilicon having a number average molecular weight of 1,000 or more and 5,000 or less.

3. The release film of claim 1, wherein, the alkenyl group-containing organosilicon (A) being represented by the following general formula (II), In General Formula (II), R1is an alkenyl group, which is optionally the same or different, having 2 or more and 8 or less carbon atoms, or a monovalent hydrocarbon group having 1 or more and 16 or less carbon atoms containing an alkyl group or a phenyl group, wherein R1bonded to the silicon atom represented by [SiO] a2 is not an alkenyl group, at least one of R1bonded to the silicon atom represented by [SiO] c2 is the alkenyl group. and [SiO] b2 Y1bonded to the silicon atom shown in the formula (I) is optionally the same or different and is an alkenyl group having 2 to 8 carbon atoms, or a monovalent hydrocarbon group having 1 to 16 carbon atoms containing an alkyl group or a phenyl group, or is represented by the following general formula (III), in general formula (III), R1 is optionally the same group as at least one R1 in general formula (II), and in general formula (III), R1 is optionally the same or different, when the total of a2, b2, c2, and all of d2 is 100 mol%, a2 is 1 mol% or more, b2 is 0 mol% or more, c2 is 0 mol% or more, and d2 is 0 mol% or more, 。 4. The release film of claim 1, wherein, when the total of the alkenyl group-containing organosilicon (A) and the Si-H group-containing organosilicon (B) is 100 parts by mass, the content of the Si-H group-containing organosilicon (B) is 3 to 30 parts by mass.

5. The release film of claim 1, wherein, the release layer being formed by coating the aqueous coating composition on the base film before crystal orientation is completed, stretching in at least one direction, and then heat treating to complete crystal orientation.

6. The release film of claim 1, wherein, the base film is a polyester film.

7. The release film according to any one of claims 1 to 6, wherein, the release film is a release film for a stacked ceramic capacitor or a release film for a resin sheet. the release film is a release film for a stacked ceramic capacitor or a release film for a resin sheet.

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