Release film

Abstract

Provided is a mold release film configured so that, when peeling off a sheet-like molding after half cutting, a problem caused by adherence of the sheet-like molding to half-cut sections is unlikely to occur. This mold release film has a substrate film and a mold release layer. Regarding the mold release layer, in a micro slurry jet erosion test with a projection force for which the erosion rate is 0.019 μm / g with respect to polymethyl methacrylate resin, the erosion rate is 0.003 μm / g or more when a slurry, obtained by dispersing polygonal alumina particles having a mean particle diameter (D50) of 0.3 μm in water, is projected.

Description

[Technical Field]

[0001] The present invention relates to a release film having a base film and a release layer, and more particularly to a release film useful as a film for various processes. [Background technology]

[0002] Conventionally, release films based on polyester films and the like have high heat resistance and mechanical properties, and have been used as process films for manufacturing adhesive sheets, cover films, and resin sheets such as ceramic slurries and polymer electrolyte membranes. Furthermore, as release layers for release films, many release layers formed from silicone-containing coating compositions have been proposed (for example, Patent Documents 1 to 4) due to their good heat resistance and release properties.

[0003] Patent documents 1 and 2 propose a release film in which a release layer is formed by a coating composition containing a polysiloxane having an unsaturated group, a polysiloxane having a Si-H group, a platinum group metal catalyst, and an organic solvent.

[0004] Furthermore, as a technique suitable for coating during the stretching and film formation of a base film (hereinafter referred to as "in-line coating"), Patent Document 3 proposes a release film in which a release layer is formed using an aqueous coating composition containing an alkenyl group-containing silicone and a Si-H group-containing silicone. In addition, as an example, a release film is disclosed in which a release layer is formed using an alkenyl group-containing silicone with a number average molecular weight of 25,000 and a Si-H group-containing silicone with a number average molecular weight of 4,500.

[0005] Furthermore, Patent Document 4 describes SiO2, which aims to achieve both easy peelability and good wettability. 4 / 2There has been proposed a release film formed using an aqueous coating composition containing an alkenyl group-containing silicone having a Q unit represented by and a Si-H group-containing silicone. Further, as an example, a release film formed using an alkenyl group-containing silicone having a number average molecular weight of 25,000 having a Q unit and a Si-H group-containing silicone having a number average molecular weight of 4,500 has been disclosed.

[0006] Thus, conventionally, when forming a release layer, a relatively high molecular weight unsaturated group-containing polysiloxane has generally been used so that a helical structure of polydimethylsiloxane is likely to be formed on the coating film surface. This was the same even when using an organic solvent-based coating composition (for example, Patent Documents 1 and 2).

[0007] On the other hand, there are also attempts to improve the peelability of the release film by measuring the hardness of the release layer of the release film and adjusting the hardness of the release layer. For example, in Patent Document 5, a release layer of a release film is separately prepared as a solid, its rubber hardness is measured, and an attempt is made to evaluate the release characteristics of the release film. However, with this method, a solid of a release layer having a formation history different from the actual release film manufacturing process is evaluated, so the release characteristics evaluation is different from that of the actual release film.

[0008] Also, as a technique for directly measuring the hardness of the release layer, in Patent Document 6, a release film for manufacturing a ceramic green sheet is proposed, which has a polyester film as a base material, a release coating layer on one surface, and the film elastic modulus measured from the surface is 2.0 GPa or more by a nanoindentation test on the release coating layer, and has a slip coating layer containing particles on the other surface of the base material. At that time, a nanoindentation test is performed at a maximum indentation depth of 50 nm of the indenter using a microhardness evaluation device to measure the film elastic modulus of the release coating layer.

Prior Art Documents

Patent Documents

[0009] [Patent Document 1] Japanese Patent Publication No. 2003-292894 [Patent Document 2] Japanese Patent Publication No. 2003-292895 [Patent Document 3] Patent No. 6077327 [Patent Document 4] Japanese Patent Publication No. 2021-11081 [Patent Document 5] Japanese Patent Publication No. 2012-6213 [Patent Document 6] International Publication No. WO2019 / 065214 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] Incidentally, when release films are used to manufacture sheet-like molded products, the sheet-like molded product, such as a ceramic green sheet, formed on its surface is often half-cut using a cutting blade, then peeled off the release film and transported to the next process. In this case, even if the release film has sufficient release properties, the sheet-like molded product may not peel properly at the point where peeling begins (the half-cut section), which has led to a decrease in yield.

[0011] When the inventors investigated the cause, they found that when a half-cut is performed, the sheet-like molded product deforms due to the cutting blade and adheres to the half-cut portion. As a result, the adhesion between the sheet-like molded product and the release film increases in that area, making it difficult to peel off from the release film.

[0012] Furthermore, it was found that simply increasing the hardness of the release layer is insufficient to avoid this problem; it is crucial to improve the toughness against microscopic physical forces.

[0013] Therefore, the object of the present invention is to provide a release film that is less likely to cause problems due to adhesion to the half-cut portion when peeling off a sheet-like molded product after half-cutting. [Means for solving the problem]

[0014] The inventors of the present invention have diligently studied to solve the above problems and have found that the above problems can be solved by forming a release layer in which the erosion obtained in the micro-slurry jet erosion test is within a specific range, and have completed the present invention. That is, the present invention includes the following:

[0015] [1] A release film having a base film and a release layer, wherein the release layer, in a micro-slurry jet erosion test, exhibits an erosion rate of 0.019 μm / g relative to a polymethyl methacrylate resin at a projection force, with an average particle size (D 50 A release film having an erosion rate of 0.003 μm / g or more when a slurry of 0.3 μm polygonal alumina particles dispersed in water is projected onto it.

[0016] [2] The release layer is a release film according to [1], which is obtained by reacting and solidifying a reaction-curable composition containing a silicone compound.

[0017] [3] The reaction-curable composition is SiO 4 / 2 The release film according to [2], comprising an alkenyl group-containing silicone having a Q unit represented by [2].

[0018] [4] The release film according to any one of items [1] to [3], wherein the base film is a polyester film.

[0019] [5] The release film according to any one of items [1] to [4], wherein the release film is a release film for multilayer ceramic capacitors or a release film for resin sheets. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a release film that is less likely to cause problems due to adhesion to the half-cut portion when peeling off a sheet-like molded product after half-cutting.

[0021] The exact reasons for this effect are unclear, but the following explanation is possible: In release layers where the erosion obtained in the micro-slurry jet erosion test exceeds a certain level, the toughness against microscopic physical forces is low (brittle). Therefore, during half-cutting, the release layer is more likely to break without deforming, effectively suppressing the deformation of the sheet-like molded product that adheres to the release layer and its adhesion to the half-cut portion. This can also be seen from the fact that after peeling off the sheet-like molded product, there is little sheet-like molded product remaining in the half-cut portion of the release film. [Brief explanation of the drawing]

[0022] [Figure 1] This photograph shows an example where the half-cut evaluation is "○". [Figure 2] This photograph shows an example of a case where the half-cutability evaluation is "△". [Figure 3] This photograph shows an example of a case where the half-cut evaluation is "×". [Modes for carrying out the invention]

[0023] The release film of the present invention is a release film having a base film (hereinafter sometimes referred to as "base") and a release layer, wherein the release layer, in a micro-slurry jet erosion test, exhibits an erosion rate of 0.019 μm / g with respect to a polymethyl methacrylate resin at a projection force, and the average particle size (D 50 The characteristic feature is that the erosion rate when a slurry of 0.3 μm polygonal alumina particles dispersed in water is projected is 0.003 μm / g or higher. First, the micro-slurry jet erosion test will be explained.

[0024] [Micro-slurry jet erosion test] The principle of this test is to measure the shape of abrasion marks caused by particle impacts and evaluate the hardness or softness of a material based on the degree of abrasion. By selecting the particles and conditions, it is possible to evaluate toughness against microscopic physical forces. The erosion rate in the MSE test can be calculated, for example, by using a micro-slurry jet erosion (MSE) tester, manufactured by Palmeso Co., Ltd., model name MSE-A, to impact the object to be measured with particles, measuring the erosion depth using a stylus-type shape measuring instrument, and then calculating the erosion rate from the erosion depth relative to the amount of particles impacted.

[0025] Commonly used particles include those made of materials such as resins, metals, and ceramics, with an average particle diameter of 10 μm or less. For quantitative comparison between measurement samples, particles of specific sizes, such as polygonal alumina, spherical alumina, and spherical silica, can be used.

[0026] The erosion rate of the release layer in the present invention is measured in the MSE test as follows: Average particle size (D 50 A slurry containing 1% by mass of 0.3 μm polygonal alumina particles was projected onto the surface of the release layer from a nozzle with a diameter of 0.3 mmΦ, at a distance of 4 mm from the nozzle tip to the sample, to cut the release layer. The displacement cut relative to the amount of slurry sprayed, and the depth cut per gram of slurry, were expressed as the erosion rate (μm / g). In other words, a high erosion rate indicates that the cut material is brittle and weak, while a low erosion rate indicates that the cut material is flexible and strong.

[0027] In the present invention, the erosion rate of the release layer in the MSE test is 0.003 μm / g or more, preferably 0.003 μm / g or more and 0.020 μm / g or less, and more preferably 0.004 μm / g or more and 0.010 μm / g or less.

[0028] If the erosion rate of the release layer is low, the release layer is considered flexible and strong. When the ceramic green sheet laminated on the surface of the release layer is half-cut, if the release layer is flexible and strong, the ceramic green sheet cannot be cut cleanly and follows the release layer, which can lead to stretching and residue of the ceramic green sheet at the half-cut portion. Stretching and residue of the ceramic green sheet at the half-cut portion are undesirable because they prevent uniform peeling during the peeling process. In contrast, if the erosion rate is 0.003 μm / g or higher, the release layer is brittle when the ceramic green sheet is half-cut, allowing for a clean, instantaneous cut. Therefore, stretching and residue of the ceramic green sheet do not occur, enabling uniform and stable peeling during the peeling process. Furthermore, if the erosion rate is below the upper limit of the preferred range mentioned above, it is preferable because it reduces the likelihood of detachment and cohesive failure of the release layer.

[0029] Methods for adjusting the erosion rate include, for example, adjusting the density of crosslinking points in the resin contained in the release layer, specifically by using an alkenyl group-containing silicone or Si-H group-containing silicone with a lower number-average molecular weight, or by using a Si-H group-containing silicone with a higher molar ratio of Si-H groups, thereby increasing the erosion rate. Alternatively, methods for adjusting the density of the branched structure in the resin contained in the release layer include, for example, adjusting the density of the branched structure in the resin. 4 / 2 The erosion rate can be increased by using an alkenyl group-containing silicone having a Q unit represented by .

[0030] In the above case, the erosion rate can be adjusted so that it is not too high by adjusting the molecular weight of the alkenyl group-containing silicone or Si-H group-containing silicone, adjusting the molar ratio of Q units, or adjusting the molar ratio of Si-H groups. It is also possible to reduce the erosion rate by adding a modifying resin that imparts flexibility to the release layer.

[0031] Furthermore, it is also possible to increase the erosion rate by using a resin with a high crosslink density separately from the release component, or by using a substance with many reaction points such as a low molecular weight crosslinking agent or coupling agent.

[0032] [Release layer] The release layer only needs to contain a release agent component such as a silicone-based compound, a long-chain alkyl group-containing compound, a fluorine-containing compound, an acrylic-based compound, etc. Further, it may also contain a binder component, a crosslinking agent, a resin for modification, a solvent, a catalyst, a surfactant, a crosslinking reaction inhibitor, a coupling agent, etc. From the viewpoint of having good heat resistance and peelability and being easy to suitably control the surface free energy and erosion rate, the release layer is preferably a release layer formed by reacting and solidifying a reaction curable composition containing a silicone-based compound. Also, from the viewpoints of environmental consideration and safety, a release layer formed by reacting and solidifying an aqueous coating composition is more preferable.

[0033] The aqueous coating composition preferably contains an alkenyl group-containing silicone having a number average molecular weight of 1000 or more and less than 10000 and having a Q unit represented by SiO 4 / 2 which may be present in the molecule and having two or more alkenyl groups in the molecule, and a Si-H group-containing silicone having a number average molecular weight of 1000 or more and 5000 or less and having two or more Si-H groups in the molecule. Details of each component will be described below.

[0034] (Alkenyl group-containing silicone) As the alkenyl group-containing silicone, an alkenyl group-containing silicone having two or more alkenyl groups in the molecule and having a Q unit represented by SiO 4 / 2 and / or an alkenyl group-containing silicone having two or more alkenyl groups in the molecule and not having a Q unit represented by SiO 4 / 2 can be used.

[0035] As the alkenyl group-containing silicone having a Q unit, an alkenyl group-containing silicone having two or more alkenyl groups and SiO 4 / 2Any compound having a Q unit represented by and a siloxane bond in the main chain is acceptable, but polyorganosiloxanes having alkenyl groups at the terminals and / or side chains are preferred. Furthermore, copolymers containing dialkylsiloxane units or alkylphenylsiloxane units are preferred because they allow for easy adjustment of the amount of alkenyl groups in one molecule while exhibiting exfoliation properties. The terminal silicon atoms preferably have alkenyl groups, but they may also have a trialkylsilane structure such as trimethylsilane.

[0036] As an alkenyl group-containing silicone that does not have Q units, any compound having two or more alkenyl groups in the molecule and a siloxane bond in the main chain may be used, but polyorganosiloxanes having alkenyl groups at the terminals and / or side chains are preferred. Furthermore, copolymers containing dialkylsiloxane units or alkylphenylsiloxane units are preferred because they allow for easy adjustment of the amount of alkenyl groups in one molecule while exhibiting peelability. The terminal silicon atoms preferably have alkenyl groups, but they may also have a trialkylsilane structure such as trimethylsilane.

[0037] In any alkenyl group-containing silicone, the alkenyl group may be introduced at one end, both ends, or in the side chain, but it is preferable that it be introduced at least at one end, and more preferably at both ends of the main chain. The molecule has two or more alkenyl groups, preferably between 2 and 20, and more preferably between 2 and 10.

[0038] In the case of a silicone containing an alkenyl group having a Q unit, SiO 4 / 2The Q unit content, represented by , is preferably 0.5 mol% to 30 mol%, and more preferably 0.5 mol% to 20 mol%, when all silicon atoms, including terminals within the molecule, are considered to be 100 mol%. When the Q unit content is 0.5 mol% or more, it becomes easier to form a dense release layer with high cohesive force, making it easier to achieve both release properties and wettability in the release layer. When the Q unit content is 30 mol% or less, it becomes easier to suppress the formation of an overly dense structure, thereby preventing the coating film from becoming brittle.

[0039] Examples of alkenyl group-containing silicones include organopolysiloxanes represented by the following general formula (I).

[0040] [ka]

[0041] (In general formula (I), R 1 [SiO] is a monovalent hydrocarbon group having 1 to 16 carbon atoms, which may be the same or different alkenyl group having 2 to 8 carbon atoms, or an alkyl group or aryl group. b1 R bonded to the silicon atom shown 1 One or more of these are alkenyl groups with 2 to 8 carbon atoms, R 2 Y is a monovalent hydrocarbon group having 1 to 16 carbon atoms, which may be the same or different alkyl or aryl group. 1 These are represented by the general formula (Ia), which may be the same or different.

[0042] [ka]

[0043] (In general formula (Ia), R 1 R is the R of general formula (I). 1 It is the same as, and may be identical or different. Y 1In the entirety of general formula (I) including the , when all silicon atoms, including terminal ones, are considered to be 100 mol%, a1 is between 50 mol% and 98 mol%, b1 is between 0 mol% and 10 mol%, c1 is between 0 mol% and 30 mol%, and d1 is between 0 mol% and 50 mol%. 1 In the entirety of general formula (I) including R 1 Two or more of these are alkenyl groups with 2 to 8 carbon atoms. In general formula (I), when c1 is 0 mol%, i.e., in the case of an alkenyl group-containing silicone that does not have Q units, examples of alkenyl group-containing silicones include organopolysiloxanes represented by the following general formula (I').

[0044] [ka]

[0045] [SiO] a1 R bonded to the silicon atom shown 2 The group may be any monovalent hydrocarbon group containing an alkyl group or an aryl group, but it is preferably a monovalent hydrocarbon group having 1 to 16 carbon atoms selected from alkyl groups or aryl groups, more preferably a methyl group or a phenyl group, and even more preferably a methyl group.

[0046] [SiO] b1 R bonded to the silicon atom shown 1 This is a monovalent hydrocarbon group containing an alkenyl group having 2 to 8 carbon atoms, or an alkyl group or aryl group, and one or more of them may be alkenyl groups having 2 to 8 carbon atoms, but it is preferable that they be a monovalent hydrocarbon group having 1 to 16 carbon atoms selected from alkenyl groups having 2 to 8 carbon atoms, or alkyl groups or aryl groups. 1 If the group is a hydrocarbon group other than an alkenyl group, a methyl group or a phenyl group is more preferred, and a methyl group is even more preferred.

[0047] [SiO] d1 R bonded to the silicon atom shown 1This may be a monovalent hydrocarbon group containing an alkenyl group having 2 to 8 carbon atoms, or an alkyl group or aryl group, but it is preferably a monovalent hydrocarbon group having 1 to 16 carbon atoms selected from an alkenyl group having 2 to 8 carbon atoms, or an alkyl group or aryl group, and more preferably a monovalent hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl group or aryl group. 1 If the group is a hydrocarbon group other than an alkenyl group, a methyl group or a phenyl group is more preferred, and a methyl group is even more preferred.

[0048] R at both ends of the main chain 1 o[SiO] b1 R bonded to the silicon atom shown 1 Similar to the above, but a preferred configuration is an alkenyl group having 2 to 8 carbon atoms. Terminal alkenyl groups are particularly preferred because they result in relatively small steric hindrances when reacting with Si-H groups, thus improving extensibility.

[0049] R bonded to the terminal silicon atom in general formula (Ia) 1 o[SiO] b1 R bonded to the silicon atom shown 1 Similar to the above, but a preferred configuration is an alkenyl group having 2 to 8 carbon atoms, as this improves the cohesive force of the release layer and enhances the release properties of process materials, such as those involving organic solvents.

[0050] R 1 Examples of alkenyl groups with 2 to 8 carbon atoms represented by include vinyl groups, allyl groups, butenyl groups, pentenyl groups, and hexenyl groups, with vinyl groups being particularly preferred among these.

[0051] Y 1In the entire general formula (I) including the , when all silicon atoms, including terminals, are considered to be 100 mol%, a1 is 50 mol% or more and 98 mol% or less, but 70 mol% or more and 98 mol% or less is preferred. Also, b1 is 0 mol% or more and 10 mol% or less, but 0 mol% or more and 5 mol% or less is preferred. c1 is 0.5 mol% or more and 30 mol% or less, but 0.5 mol% or more and 20 mol% or less is preferred. d1 is 0 mol% or more and 50 mol% or less, A concentration of 0 mol% to 30 mol% is preferred.

[0052] [SiO] a1 and [SiO] b1 When the total constituent units of are set to 100 mol%, from the viewpoint of localizing hydrocarbon groups on the coating surface in order to improve peelability, [SiO] a1 The range of constituent units is preferably 90 mol% to 100 mol%, and more preferably 95 mol% to 100 mol%.

[0053] The number-average molecular weight of alkenyl group-containing silicones is preferably 1,000 or more and less than 10,000, more preferably 3,000 or more and less than 10,000. If it is above, The hydrocarbon groups become localized on the coating surface, making it easier to obtain sufficient peelability. On the other hand, if the number average molecular weight is less than 10,000, To aqueous coating compositions The emulsification properties tend to improve, and uniform coating properties also tend to improve.

[0054] (Si-H group-containing silicone) Any compound containing two or more Si-H groups (i.e., two or more hydrogen atoms directly bonded to a Si atom) and having a siloxane bond in the main chain can be used as the Si-H group-containing silicone, but polyorganosiloxanes having Si-H groups in the side chains are preferred. Furthermore, copolymers containing dialkylsiloxane units or alkylphenylsiloxane units are preferred because they allow for easy adjustment of the amount of Si-H groups in one molecule while exhibiting peelability. The terminal silicon atoms may have Si-H groups, but it is preferable that they have a trialkylsilane structure such as trimethylsilane.

[0055] Examples of Si-H group-containing silicones include organohydrogenpolysiloxanes represented by the following general formula (II).

[0056] [ka]

[0057] (In general formula (II), R 3 (These are monovalent hydrocarbon groups having 1 to 16 carbon atoms, which may be the same or different, and which contain an alkyl group or an aryl group. When a2 + b2 is considered to be 100 mol%, a2 is 30 mol% to 90 mol%, and b2 is 10 mol% to 70 mol%.) [SiO] a2 The silicon atom shown has a hydrogen atom (hydrogen group) bonded to it, R 3 This can be any monovalent hydrocarbon group containing an alkyl group or an aryl group, but it is preferably a monovalent hydrocarbon group with 1 to 16 carbon atoms selected from alkyl groups or aryl groups.

[0058] [SiO] b2 , and R bonded to terminal Si atoms 3 This can be any monovalent hydrocarbon group containing an alkyl group or an aryl group, but it is preferably a monovalent hydrocarbon group with 1 to 16 carbon atoms selected from alkyl groups or aryl groups.

[0059] Which R 3 In this regard, a smaller number of carbon atoms in the alkyl or aryl group is preferable, as this results in relatively less steric structural interference and facilitates the crosslinking reaction. It is also preferable from the viewpoint of fluidity and uniformity of the reaction structure in the release layer. For this reason, preferred alkyl groups include methyl, ethyl, propyl, and butyl groups, and preferred aryl groups include phenyl and tolyl groups.

[0060] [SiO] a2 and [SiO] b2If the total constituent units are assumed to be 100 mol%, then [SiO] a2 The constituent units are preferably in the range of 30 mol% to 90 mol%, and more preferably 40 mol% to 80 mol%. [SiO] a2 When the constituent units of are 30 mol% or more, there is a sufficient amount of crosslinking reaction sites, the cohesive force of the release layer increases, and the abrasion resistance and solvent resistance of the release layer also improve, which is preferable. Also, [SiO] a2 When the constituent units are 90 mol% or less, Si-H groups are less likely to remain in the release layer, the activity of the release layer surface is less likely to increase, and good release properties are maintained, which is preferable.

[0061] In the present invention, the number-average molecular weight of the Si-H group-containing silicone is preferably 1000 to 5000, and more preferably 3000 to 5000. When the number-average molecular weight is 1000 or more, sufficient release properties are easily obtained. On the other hand, when the number-average molecular weight is 5000 or less, the emulsification properties in aqueous coating compositions tend to be good, and coating uniformity also tends to be good. Furthermore, the crosslinking reaction proceeds more efficiently, the amount of residual Si-H groups in the release layer decreases, and the release properties improve.

[0062] In the aqueous coating composition, it is preferable that the composition contains 1 to 50 parts by mass of Si-H group-containing silicone per 100 parts by mass of alkenyl group-containing silicone, more preferably 2 to 40 parts by mass, and even more preferably 3 to 30 parts by mass. When the Si-H group-containing silicone content is 1 part by mass or more, there are a sufficient number of crosslinking reaction sites, making it easier to form a dense crosslinked structure and improving the release layer properties, which is preferable. When the Si-H group-containing silicone content is 50 parts by mass or less, it is preferable that Si-H groups do not remain in the release layer, the activity of the release layer surface does not increase easily, and good peelability is maintained.

[0063] (Polyvinyl alcohol-based resin) When using a modifying resin, it is preferable to use a polyvinyl alcohol-based resin as the modifying resin for adjusting the surface free energy, etc. As the polyvinyl alcohol-based resin, polyvinyl alcohol or its copolymers can be used. Examples of polyvinyl alcohol copolymers include vinyl alcohol-vinyl acetate copolymer, vinyl alcohol-vinyl butyral copolymer, ethylene-vinyl alcohol copolymer, and polyvinyl alcohol polymers having silyl groups in the molecule, and among these, vinyl alcohol-vinyl acetate copolymer and ethylene-vinyl alcohol copolymer are preferred. When the polyvinyl alcohol-based resin is a copolymer, the repeating units derived from vinyl alcohol are preferably 70 mol% to 100 mol%, and more preferably 85 mol% to 99 mol%.

[0064] The degree of polymerization of the polyvinyl alcohol-based resin in the present invention can be expressed by the viscosity of a 4% by mass aqueous solution at 20°C, and it is preferable that the viscosity is between 5 mPa·s and 50 mPa·s. When the viscosity is within the above numerical range, the miscibility in the aqueous coating composition is high, and it becomes easier to obtain a more uniform release layer. In other words, when the viscosity is 5 mPa·s or higher, it becomes less likely to flow within the coating film after the release layer is formed, and it is preferable that the release properties do not deteriorate. When the viscosity is 50 mPa·s or lower, the viscosity of the entire aqueous coating composition does not tend to become high, and it is preferable that uniform coating is easier.

[0065] Furthermore, polyvinyl alcohol-based resins can be mixed with silicone before emulsification and can also be used as emulsifiers.

[0066] Typically, polyvinyl alcohol is obtained by polymerizing vinyl acetate to polyvinyl acetate, followed by saponification, and the amount of saponification is expressed as the degree of saponification. In the present invention, a degree of saponification of the polyvinyl alcohol-based resin of 85 mol% to 99 mol% is preferred. When the degree of saponification is within the aforementioned numerical range, the miscibility in the aqueous coating composition is high, and a more uniform release layer is easily obtained. In particular, when the degree of saponification is 85 mol% or higher, adhesion to the substrate is improved, while also maintaining good miscibility with silicone. When the degree of saponification is 99% or lower, the hydrophilicity of the release layer does not become too high, the cohesive force of the release layer coating film is easily maintained, and cases where the adhesion of the release layer deteriorates are less likely to occur.

[0067] Commercially available polyvinyl alcohol-based resins can be used as is. Specific examples of such commercially available products include POVA manufactured by Kuraray Co., Ltd. and Gosenol manufactured by Mitsubishi Chemical Corporation.

[0068] When using a polyvinyl alcohol-based resin in the release layer, it is preferable that the content be between 1% by mass and 20% by mass relative to the release layer. A more preferable range is between 1% by mass and 15% by mass, and an even more preferable range is between 1% by mass and 10% by mass. When the content of the polyvinyl alcohol-based resin is within the above numerical range, it is possible to more favorably achieve both the miscibility with silicone and the adhesion between the substrate and the release layer. In other words, when the content of the polyvinyl alcohol-based resin in the release layer is 1% by mass or more, the stability of the silicone emulsion in the coating liquid tends to be good, and when it is 20% by mass or less, the release properties do not tend to deteriorate.

[0069] (Platinum catalyst) The crosslinking reaction between alkenyl group-containing silicone and Si-H group-containing silicone is an addition reaction, and in one embodiment, it is preferable to use a platinum-based catalyst to promote the reaction.

[0070] Known platinum-based catalysts can be used, such as platinum chloride and chloroplatinic acid. Considering dispersibility in silicone, a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum(0) complex (Karstedt catalyst) may also be used as the platinum-based catalyst. By dispersing it simultaneously with the emulsification of the silicone, uniform dispersion can be ensured.

[0071] Preferably, the platinum-based catalyst content is such that the mass of platinum is between 10 ppm and 400 ppm relative to the combined mass of the alkenyl group-containing silicone and the Si-H group-containing silicone. This range allows for sufficient curing of the silicone, suppresses the formation of silicone aggregates, and yields a release film with excellent surface properties. When the mass ratio of platinum is below the upper limit, the addition reaction between the alkenyl groups and Si-H groups becomes moderate, tending to suppress the formation of silicone aggregates. From this viewpoint, the platinum-based catalyst content 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, making it less likely to cause poor silicone curing. From this viewpoint, the platinum catalyst content is more preferably 15 ppm or more, and even more preferably 20 ppm or more.

[0072] (Aqueous solvent) When using an aqueous coating composition, the aqueous coating composition usually contains an aqueous solvent in addition to alkenyl group-containing silicone and Si-H group-containing silicone, but the aqueous solvent is Contains water Preferably, the following are used. In one embodiment, an aqueous dispersion of alkenyl group-containing silicone and an aqueous dispersion of Si-H group-containing silicone are used for the preparation of an aqueous coating composition. Preferably, the aqueous dispersions of each silicone are: Aqueous emulsion It will be used.

[0073] The release layer is formed from such an aqueous emulsion, and the release layer is formed by applying an aqueous coating composition containing the aqueous emulsion (hereinafter sometimes abbreviated as "aqueous coating solution"). By using an aqueous solvent, the release layer can be formed without the need for explosion-proof and recovery equipment required for organic solvents during the film manufacturing process. It is also possible to include a small amount of organic solvent if necessary.

[0074] (Other ingredients) In one embodiment, when using an aqueous coating composition, other additives such as surfactants, coupling agents, crosslinking reaction inhibitors, antistatic agents, ultraviolet absorbers, pigments, colorants, organic or inorganic particles, lubricants, and antiblocking agents can be mixed into the aqueous coating composition, provided that the effects of the invention are not impaired.

[0075] (Surfactants) In one embodiment, it is preferable to add a surfactant to the aqueous coating composition in order to promote wetting of the substrate film when forming the release layer. Examples of such surfactants include anionic surfactants, cationic surfactants, and nonionic surfactants, and it is possible to use one or more of these. In order to prevent aggregation of the aqueous emulsions of each silicone and not to affect the curing reaction of the silicone, it is preferable to use a nonionic surfactant as an emulsifier.

[0076] Nonionic surfactants are preferably those with an HLB value in the range of 6 to 18. Examples include at least one selected from alkylene oxide adducts such as 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 sorbitan esters, and alkylene oxide adducts of higher fatty acid glycerides. Here, the HLB value is calculated using Griffin's formula.

[0077] Examples of alkylene oxides include ethylene oxide, propylene oxide, and butylene oxide, and one or more of these may be used. When multiple are used, the addition method can be block or random, but it is preferable that the HLB value is in the range of 8 to 18, and more preferably in the range of 10 to 15. Among these nonionic surfactants, polyoxyethylene lauryl ether and polyoxyethylene tridecyl ether are preferred. If necessary, two or more nonionic surfactants may be mixed. If a nonionic surfactant with an HLB value outside the specified range is used as an emulsifier for a silicone aqueous dispersion, the emulsifying and dispersing power and the stability of the aqueous dispersion may decrease.

[0078] The surfactant is preferably used in an amount of 0.1% to 20% by mass relative to the total solids, more preferably in an amount of 0.2% to 15% by mass, and even more preferably in an amount of 0.5% to 10% by mass. If the amount is above the lower limit of this range, the emulsification state will be good, and if it is below the upper limit of this range, severe peeling will be less likely to occur.

[0079] (Crosslinking reaction inhibitor) In one embodiment, it is preferable that a reaction inhibitor is included in the aqueous coating solution to suppress the activity of the platinum-based catalyst at room temperature. Such a reaction inhibitor is preferably an alkynyl group-containing reaction inhibitor. The reaction inhibitor having an alkynyl group is not particularly limited as long as it has an alkynyl group, but specific examples include 1-ethynyl-1-cyclohexanol, 4-ethyl-1-octin-3-ol, 3-methyl-1-dodecine-3-ol, 3,7,11-trimethyl-1-dodecine-3-ol, 1,1-diphenyl-2-propyne-3-ol, 3-ethyl-6-ethyl-1-nonin-3-ol, 3-methyl-1-pentadecin-3-ol, 2,5-dimethyl-3-hexyn-2,5-diol, and 3-phenyl-1-butyne-3-ol. In this invention, since the coating solution is aqueous, it is preferable to use a reaction inhibitor having an alkynyl group and a hydroxyl group, as exemplified, considering the balance between affinity and solubility in water, coordination ability to platinum, and boiling point. Alternatively, the platinum-based catalyst may be mixed with a common organopolysiloxane and used as an aqueous emulsion for addition to the aqueous coating solution.

[0080] The crosslinking reaction inhibitor content is preferably 5 ppm to 1000 ppm, more preferably 10 ppm to 700 ppm, and even more preferably 20 ppm to 500 ppm, relative to the mass of the aqueous coating composition used to form the release layer. When the crosslinking reaction inhibitor content is above the lower limit, the pot life is extended, the addition curing reaction of the silicone is less likely to proceed at room temperature, and silicone aggregates tend to be less likely to form. Furthermore, when the crosslinking reaction inhibitor content is below the upper limit, the silicone is less likely to migrate to the mating material after the mating material has been peeled off, and the amount of reaction inhibitor that volatilizes during heat treatment is reduced, thus reducing contamination inside the oven.

[0081] (Coupling agent) In one embodiment, a coupling agent may be added to the aqueous coating composition to improve the adhesion between the silicone component and the substrate film. Examples of coupling agents include compounds represented by the general formula YRSiX3, such as silane coupling agents. Here, Y is an organic functional group such as a vinyl group, epoxy group, amino group, or mercapto group, and it is particularly preferable that Y is an epoxy group or a vinyl group.

[0082] R is an alkylene group such as a methylene, ethylene, or propylene group, or a single bond. X is a hydrolyzable group such as a methoxy group, ethoxy group, or acetoxy, or an alkyl group, and at least one of the three Xs is a hydrolyzable group, preferably all three Xs are hydrolyzable groups. A methoxy group is preferred as the hydrolyzable group.

[0083] Preferred silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltris(2-methoxyethoxy)silane, vinylmethyldimethoxysilane, and the like.

[0084] Other examples of coupling agents include organometallic compounds containing metals such as zirconium, titanium, and aluminum, with preferred organometallic compounds being classified as alkoxides, chelates, or acylates. Specific examples include, but are not limited to, zirconium tetraacetylacetonate, zirconium acetate, titanium acetylacetonate, triethanolamine titanate, and titanium lactate.

[0085] Furthermore, it is possible to use two or more coupling agents, such as using a silane coupling agent in which Y is an epoxy group and a silane coupling agent in which Y is a vinyl group in combination.

[0086] In one embodiment, the addition of a coupling agent improves the durable adhesion between the silicone, which is the main component of the release layer, and the polyester film, etc. For example, when casting resin sheets using a solution casting method with an organic solvent, organic solvent components may penetrate the release layer, potentially causing erosion of the release layer. However, erosion can be suppressed by adding a coupling agent. When casting resin sheets using a melt casting method at high temperatures, the release layer is exposed to high temperatures, potentially leading to thermal degradation. However, the addition of a coupling agent suppresses thermal degradation and allows the release layer to be retained.

[0087] From the above viewpoint, the coupling agent content 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, based on 100 parts by mass of the total of the alkenyl group-containing silicone and Si-H group-containing silicone contained in the release layer.

[0088] (Preparation of silicone aqueous dispersion) In the case of using an aqueous coating composition, in one embodiment, the preparation of an aqueous emulsion can be done by emulsifying a predetermined alkenyl group-containing silicone or Si-H group-containing silicone, an aqueous solvent, and a surfactant. Known methods can be used to emulsify these components, for example, by mechanically emulsifying a predetermined silicone, surfactant, and other components in an aqueous medium using a stirring device such as a homogenizer, adi-homomia mixer, or ultraplanetary mixer.

[0089] Furthermore, the particle size of the aqueous dispersion can be adjusted by adjusting the size of the stirring blade, the stirring speed, and the stirring time. The average particle size of the dispersed particles in each silicone aqueous dispersion is preferably 200 nm or less, and more preferably 100 nm or more and 200 nm or less.

[0090] [Base film] The base film in the present invention is not particularly limited, but examples include sheets or films made of polyester such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polycarbonate, polyethylene, and polypropylene, polystyrene triacetylcellulose, acrylic, and polyimide. Among these, films made of polyester are preferred from the viewpoint of having excellent mechanical properties and heat resistance, and a good balance between these properties and price. The following explanation will use the case of a polyester film as an example, but even when other resin films are used, the copolymer components, blending components, additives, film manufacturing method, laminated structure, etc., are the same as described below.

[0091] (Polyester film) The polyester used as the base film is not particularly limited, and a film-formed polyester commonly used as a base film for release films can be used. Preferably, it is a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component, and more preferably, polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, or copolymers mainly composed of these resin components. In particular, a polyester film formed from polyethylene terephthalate is especially preferred. The polyethylene terephthalate preferably has 90 mol% or more, more preferably 95 mol% or more of repeating units of ethylene terephthalate, and may also have small amounts of other dicarboxylic acid components and diol components copolymerized. For example, from the viewpoint of cost, it is preferable to have one made only from terephthalic acid and ethylene glycol. In addition, known additives, such as antioxidants, light stabilizers, ultraviolet absorbers, and crystallizers, may be added within a range that does not hinder the effect of the release film of the present invention. The polyester film is preferably a biaxially oriented polyester film due to reasons such as high bidirectional elastic modulus.

[0092] The intrinsic viscosity of the polyester film described above is preferably 0.50 dl / g or more and 0.70 dl / g or less, and more preferably 0.52 dl / g or more and 0.62 dl / g or less. When the intrinsic viscosity is 0.50 dl / g or more, it is preferable because breakage does not occur frequently during the stretching process. Conversely, when it is 0.70 dl / g or less, it is preferable because the cutability is good when cutting to a predetermined product width and dimensional defects do not occur. In addition, it is preferable that the raw material pellets are thoroughly vacuum-dried.

[0093] In this specification, when the term "polyester film" is used, it refers to a polyester film having surface layer A and surface layer B (a laminated film).

[0094] The method for manufacturing the polyester film in the present invention is not particularly limited, and conventional methods can be used. For example, the polyester can be melted in an extruder, extruded into a film, cooled in a rotating cooling drum to obtain an unstretched film, and then biaxially stretched to obtain the film. The biaxially oriented film can be obtained by sequentially biaxially stretching a uniaxially oriented film in the longitudinal or transverse direction in the transverse or longitudinal direction, or by simultaneously biaxially stretching an unstretched film in the longitudinal and transverse directions.

[0095] In the present invention, it is preferable that the stretching temperature during stretching of the polyester film be above the secondary transition temperature (Tg) of the polyester. It is also preferable to stretch the film by 1 to 8 times, and particularly by 2 to 6 times, in both the longitudinal and transverse directions.

[0096] The polyester film described above preferably has a thickness of 12 μm to 50 μm, more preferably 15 μm to 38 μm, and more preferably 19 μm to 33 μm. A film thickness of 12 μm or more is preferable because it does not risk deformation due to heat during film production, processing, or molding. On the other hand, a film thickness of 50 μm or less is preferable because it does not result in an excessively large amount of film being discarded after use, thus reducing the environmental burden.

[0097] The polyester film substrate described above may be a single layer or a multilayer of two or more layers. For example, the substrate film may 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.

[0098] In this embodiment, the surface layer A may contain particles with a particle size of less than 1.0 μm and 1 nm or larger. By substantially excluding particles with a particle size of 1.0 μm or larger, such as inorganic particles, from the surface layer A, it is possible to reduce the transfer of the particle shape in the substrate to the resin sheet, which can cause defects.

[0099] In one embodiment, by not including particles with a particle size of less than 1.0 μm in the surface layer A, it is possible to more effectively suppress defects caused by the transfer of the particle shape in the substrate to the resin sheet.

[0100] In one embodiment, the 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 makes it possible to more effectively suppress defects caused by the transfer of the particle shape in the substrate to the resin sheet. For example, a surface layer A that substantially does not contain particles with a particle size of less than 1.0 μm is preferably also substantially free of particles with a particle size of 1.0 μm or larger.

[0101] In this invention, "substantially free of particles" means, for example, in the case of inorganic particles smaller than 1.0 μm, that the content of inorganic elements is 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit when quantified by fluorescence X-ray analysis. This is because even without actively adding particles to the film, contaminants originating from foreign substances, or dirt adhering to the raw material resin or the lines and equipment in the film manufacturing process, may peel off and become mixed into the film. Furthermore, "substantially free of particles with a particle size of 1.0 μm or larger" means that the film actively does not contain particles with a particle size of 1.0 μm or larger.

[0102] In the case of a laminated polyester film consisting of two or more layers, it is preferable that the surface opposite to surface layer A, which substantially does not contain inorganic particles, has a surface layer B that may contain inorganic particles.

[0103] In terms of the lamination structure, if the layer on the side to which the release layer is applied is designated as layer A, the layer on the opposite side as layer B, and the remaining core layer as layer C, then the layer configuration in the thickness direction can be a laminated structure such as release layer / A / B or release layer / A / C / B. Naturally, layer C may consist of multiple layers. Furthermore, the surface layer B may not contain inorganic particles. In that case, it is preferable to provide a coating layer containing at least inorganic particles and a binder on the surface layer B in order to provide slipperiness for winding the film into a roll.

[0104] In the polyester film substrate of the present invention, the surface layer B that forms the opposite side of the surface to which the release layer is applied preferably contains inorganic particles from the viewpoint of the film's slipperiness and ease of air release, and it is particularly preferable to use silica particles and / or calcium carbonate particles. The inorganic particle content is preferably 1,000 ppm to 15,000 ppm in total in the surface layer B.

[0105] In this case, the average surface roughness (Sa) of the surface layer B film is preferably in the range of 1 nm to 40 nm. More preferably, it is in the range of 5 nm to 35 nm. When the total amount of silica particles and / or calcium carbonate particles is 1000 ppm or more and Sa is 1 nm or more, when the film is wound into a roll, air can be released uniformly, resulting in a good winding shape and good flatness, making it suitable for the manufacture of ultrathin ceramic green sheets. Furthermore, 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 no coarse protrusions are formed, resulting in stable quality during the manufacture of ultrathin ceramic green sheets, which is preferable.

[0106] In addition to silica and / or calcium carbonate, other inert inorganic particles and / or heat-resistant organic particles can be used as particles in the above-mentioned B layer, but silica particles and / or calcium carbonate particles are more preferable from the viewpoint of transparency and cost. Other inorganic particles that can be used include alumina-silica composite oxide particles and hydroxyapatite particles. Heat-resistant organic particles include cross-linked polyacrylic particles, cross-linked polystyrene particles and benzoguanamine particles. When silica particles are used, porous colloidal silica is preferred, and when calcium carbonate particles are used, light calcium carbonate surface-treated with a polyacrylic acid-based polymer compound is preferred from the viewpoint of preventing lubricant detachment.

[0107] 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, and particularly preferably 0.5 μm or more and 1.0 μm or less. An average particle size of 0.1 μm or more is preferable because it provides good slipperiness for the release film. Furthermore, an average particle size of 2.0 μm or less is preferable because it does not adversely affect the smoothness of the surface of the release layer, thus preventing the formation of pinholes in the ceramic green sheet.

[0108] In the surface layer A, which is the layer on the side where the release layer is provided, it is preferable not to use recycled materials or the like in order to prevent the inclusion of inorganic particles such as lubricants, from the viewpoint of reducing pinholes.

[0109] The thickness ratio of surface layer A, which is the layer on which the release layer is provided, is preferably 20% to 50% of the total thickness of the base film. If it is 20% or more, the influence of particles contained in surface layer B and the like from inside the film is less likely to occur, and it is easier for the average surface roughness Sa to satisfy the above range, which is preferable. If it is 50% or less of the total thickness of the base film, the proportion of recycled materials used in surface layer B can be increased, which is preferable because it reduces the environmental impact.

[0110] Furthermore, from an economic standpoint, layers other than the surface layer A (surface layer B or the aforementioned intermediate layer C) can use 50% to 90% by mass of recycled film scraps or PET bottles. Even in this case, it is preferable that the type, amount, particle size, and average surface roughness (Sa) of the lubricant contained in layer B satisfy the above range.

[0111] Furthermore, the film before stretching or after uniaxial stretching during the film-forming process is used to improve the adhesion of release layers and other materials applied later, and to prevent static electricity. On the surface of surface layer A and / or surface layer B A coating layer may be added, and surface treatments may also be applied.

[0112] In one embodiment, the surface on which the aqueous coating composition is applied to form the release layer may be surface-treated or an easy-adhesion layer may be provided to improve adhesion with the release layer. 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 a layer containing the same resin as the base film, and further containing an antistatic agent, pigment, surfactant, lubricant, antiblocking agent, etc. If an adhesion-enhancing agent such as a coupling agent is added to the aqueous coating composition, the release layer can have sufficient adhesion to the base film even without providing an easy-adhesion layer or the like.

[0113] [Formation of release layer] In one embodiment, the release layer is formed by applying an aqueous coating composition containing an aqueous emulsion of alkenyl group-containing silicone and an aqueous emulsion of Si-H group-containing silicone. In this case, the release layer is formed on at least one surface of the base film. The release layer is formed by applying the aqueous coating solution onto the base film, followed by heating and drying, during which the components of the aqueous coating solution react and solidify. The release layer is It is preferable that the film is formed during the film manufacturing process.

[0114] The thickness of the release layer after drying is preferably 5 nm to 100 nm. If the thickness of the release layer is above the lower limit, sufficient release properties are easily obtained, and if it is below the upper limit, the release strength tends not to increase, and it also tends to be easier to apply as it eliminates the need to increase the concentration of the release layer component in the water-based coating solution or increase the coating amount. Therefore, the thickness of the release layer is more preferably 5 nm to 70 nm, and even more preferably 5 nm to 50 nm.

[0115] When applying the aqueous coating solution onto a substrate film, the solid content concentration is preferably 20% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, based on the release layer component in the aqueous coating solution. When the solid content concentration of the release layer component in the aqueous coating solution is above the lower limit, the film-forming properties tend to be good. Also, when the solid content concentration is below the upper limit, the stability of the aqueous coating solution and the appearance of the release layer tend to be good. Water is preferably used as the aqueous solvent to adjust the solid content concentration.

[0116] The aqueous coating solution applied to the base film to form a release layer can be carried out at any stage, but it is preferable to carry it out during the polyester film manufacturing process, and more preferably to apply it to the polyester film before orientation crystallization is complete. After that, the film can be stretched in at least one direction and then heat-treated to complete the crystal orientation.

[0117] Here, polyester films before crystal orientation is complete include unstretched films, uniaxially oriented films in which the unstretched film is oriented in either the longitudinal direction (hereinafter sometimes referred to as the continuous film formation direction, longitudinal direction, or MD direction) or the transverse direction (hereinafter sometimes referred to as the direction perpendicular to the longitudinal direction, width direction, or TD direction), and films that have been low-magnification stretched and oriented in both the longitudinal and transverse directions (biaxially oriented films before they are finally re-stretched in the longitudinal or transverse direction to complete the orientation crystallization).

[0118] In particular, so-called in-line coating is preferred, in which an aqueous coating solution is applied to an unstretched film or a uniaxially oriented film, and then longitudinal and / or transverse stretching and heat fixing are performed immediately. The release layer may be dried by the stretching or heat fixing process after coating, and a drying process may be added as needed. Furthermore, when curing the composition using a catalyst to obtain a cured film, curing can be achieved by the stretching or heat fixing process, and a curing process may be added as needed.

[0119] When applying an aqueous coating solution to a polyester film, it is preferable to perform a physical treatment on the film surface, such as corona surface treatment, flame treatment, or plasma treatment, as a preliminary treatment to improve coating properties, or to use the aforementioned emulsifier in combination with the composition as a wetting agent, or to add a surfactant as a wetting agent.

[0120] Any known coating method can be applied. For example, roll coating, gravure coating, roll brushing, spray coating, air knife coating, impregnation, curtain coating, etc., can be used individually or in combination.

[0121] [Characteristics of release film] In the present invention, the surface free energy of the release layer in the test method described later is preferably in the range of 10 mN / m to 40 mN / m, more preferably 12 mN / m to 38 mN / m, even more preferably 14 mN / m to 36 mN / m, and particularly preferably 15 mN / m to 35 mN / m. If the surface free energy of the release layer is below the upper limit, the adhesion force is reduced and severe peeling becomes less likely. If it is above the lower limit, defects due to repulsion of the processed layer such as ceramic sheets 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.

[0122] [Application] The release film in this invention can be used as a process film during the manufacture of multilayer ceramic capacitors or resin sheet casting. In particular, even when a thin resin sheet with a thickness of 1 μm or less after drying is produced, the wettability is good, so pinholes in the processed layer are reduced, and for example, when used as a release film for the manufacture of green sheets, the defect rate of thin-walled multilayer ceramic capacitors can be reduced. [Examples]

[0123] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The evaluation methods for physical properties, etc., in the following examples are as follows.

[0124] (1) Uniformity of the release layer application The release film was cut to A4 size, and the release layer surface was visually observed using fluorescent and halogen lights. The number of aggregated coating defects (number per A4 sheet) was compared and evaluated according to the following criteria. ◎: No application defects ○: 1-2 coating defects △: 3-5 application defects ×: Six or more coating defects

[0125] (2) Surface free energy of the release layer For samples that had been conditioned for 24 hours under conditions of 23°C and 50% RH, the static contact angle was measured using a contact angle meter (DMo-501, manufactured by Kyowa Interface Chemical Co., Ltd.) after adding water and allowing it to stand for 30 seconds. Similarly, the static contact angles of ethylene glycol and methylene iodide were measured, and the following simultaneous equations relating to the surface tension components of the release layer were constructed using the surface tension components of each liquid listed below (the measured solutions for water, ethylene glycol, and methylene iodide are designated as 1, 2, and 3 respectively; γLD is the dispersion 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 the surface tension components in the liquid, γSD is the dispersion force component of the release layer, γSP is the polar force component of the release layer, and γSH is the hydrogen bonding component of the release layer. Also, θ represents the contact angle). (γSD·γLD1) 1 / 2 +(γSP·γLP1) 1 / 2 +(γSH·γLH1) 1 / 2 =γL1(1+cosθ1) / 2 (γSD·γLD2) 1 / 2 +(γSP·γLP2) 1 / 2 +(γSH·γLH2) 1 / 2 =γL2(1+cosθ2) / 2 (γSD·γLD3) 1 / 2 +(γSP·γLP3) 1 / 2 +(γSH·γLH3) 1 / 2 =γL3(1+cosθ3) / 2 The γLD, γLP, γLH, and γL values ​​for water, ethylene glycol, and methylene iodide are shown in Table 1.

[0126] [Table 1]

[0127] Next, the surface free energy γS of the release layer surface was calculated using the following formula based on the values ​​of γSD, γSP, and γSH obtained above. γS = γSD + γSP + γSH

[0128] (3) Erosion rate Average particle diameter (D 50 A slurry containing 1% by mass of polygonal alumina particles (BUEHLER Micropolish Alumina, manufactured by BUEHLER) with a diameter of 0.3 μm was prepared by dispersing these particles in water. A release film was fixed to the sample stage using a Micro-Slurry Jet Erosion (MSE) tester (Palmeso Co., Ltd., device name MSE-A). The projection distance of the nozzle for spraying the slurry was set to 4 mm.

[0129] The nozzle diameter for projecting (injecting) the particles was set to 0.3 mmΦ, and the particles were impacted onto the surface of the release layer to cut it. The injection strength at this time was determined by first cutting polymethyl methacrylate resin (Kuraray Co., Ltd., Paraglass P, sheet thickness 2 mm) under similar experimental conditions, and calculating the standard projection force from the displacement cut relative to the amount of slurry injected (i.e., the depth cut when 1 g of slurry is sprayed), and then determining the standard projection strength based on that value. Average particle diameter (D 50 In this embodiment, using 0.3 μm polygonal alumina particles, the projection force at which 0.019 μm / g was removed from the polymethyl methacrylate resin was defined as the standard projection force. The erosion depth of the release layer was measured at this standard projection force. In the above test machine, the projection force is adjusted by the projection air pressure, so once the projection force is determined, the projection air pressure and projection air volume are also determined.

[0130] Erosion depth was measured using a stylus-type surface shape measuring instrument (Kosaka Laboratory Co., Ltd., model PU-EU1, stylus tip radius R: 0.5 μm, load: 50 μN, measurement magnification: 50,000, measurement length: 4 mm, measurement speed: 0.1 mm / s). More specifically, first, slope correction was performed using reference areas A and B at both ends of the measurement length that were not worn. Next, the step difference from the reference regression line to the center C of the wear mark (average value over a width of 50 μm) was measured. Then, the difference between the step difference data at 0 g projection (untreated surface) and the step difference data at each projection amount was taken to obtain the erosion depth. From the obtained projection amount-erosion depth data, the erosion rate (μm / g) was determined from the change in erosion depth between slurry projection amounts of 0 g and 25 g.

[0131] (4) Evaluation of half-cut properties 100 parts by mass of barium titanate (BaTiO3, manufactured by Kyoritsu Material), 7 parts by mass of polyvinyl butyral (manufactured by Sekisui Chemical), 3 parts by mass of dioctyl phthalate, and 3 parts by mass of dispersant (DISPERBYK-103, manufactured by Bic Chemie) were added to a mixed solvent of toluene:ethanol = 1:1 (volume ratio), and dispersed using a ball mill to prepare a slurry.

[0132] This slurry was uniformly coated onto the release layer of a release film to a thickness of 2 μm after drying, and then dried to form a ceramic green sheet. The release film with the ceramic sheet formed on it was half-cut using a rotary die cutter (RDC(FB)-A4, manufactured by Tsukaya Hamono Seisakusho Co., Ltd.) to a size of 16 mm x 32 mm from the ceramic green sheet side, with a depth of approximately 3 μm from the surface of the release layer. The rotary die cutter used had a double-edged blade with a 50° angle, a blade depth of 0.3 mm, and a blade height of 0.6 mm. The depth of the half-cut was adjusted by inserting a polyester film of appropriate thickness between the rotary die cutter blade and the ceramic green sheet, and between the release film and the anvil roll. The cutting condition of the cut section was observed with an optical microscope (magnification approximately 10x) and evaluated as follows. Figures 1 to 3 show photographs corresponding to each case where the half-cut performance evaluation was "○" to "×". ○: No residue of the ceramic green sheet was observed in the cut area. △: A very small amount of ceramic green sheet residue can be seen in the cut area. ×: A large amount of ceramic green sheet residue is visible in the cut area.

[0133] (5) Recyclability assessment Recyclability was assessed by using a universal projector to magnify the size and number of foreign particles contained in the film 20 times by projection irradiation, and counting the number of foreign particles with a maximum diameter of 50 μm or more. The measurement area was 0.05 m². 2 That's what I decided. ◎: Number of foreign objects: 10 / 0.05m 2 Less than this does not pose a problem in terms of usage. ○: Number of foreign objects: 10 / 0.05m 2 Based on the above, 30 pieces / 0.05m 2 It is slightly affected in terms of flatness, but this does not pose a problem in use. △: Number of foreign objects: 30 / 0.05 m 2 Based on the above, 100 pieces / 0.05m 2 It can be used for limited purposes if it is below a certain level. ×: Number of foreign objects: 100 / 0.05m 2 In summary, the deformation of the cast surface is very noticeable and the product is unusable.

[0134] (6) Number average molecular weight Gel permeation chromatography (GPC) was measured, and the value was calculated as a polystyrene equivalent.

[0135] (7) Thickness of the release layer After cutting the release film into triangular pieces, a 2 nm thick Pt (platinum) layer was formed on the surface of the release layer by coating. The obtained samples were fixed in a multiaxial embedding capsule and embedded using epoxy resin. Using a microtome ULTRACUT-S, the film was sliced ​​perpendicular to the plane direction to obtain ultrathin samples with a thickness of 50 nm. Next, the obtained ultrathin samples were placed on a grid and vapor-stained with 2% osmium acid at 60°C for 2 hours. Using the ultrathin samples after vapor staining, the film cross-section was observed with a transmission electron microscope LEM-2000 under an acceleration voltage of 100 kV, and the thickness of the release layer was measured. Measurements were performed at 10 arbitrary points, and the average value was taken as the thickness of the release layer (unit: nm).

[0136] [Example 1] Polyethylene terephthalate ([η]=0.64 dl / g, Tg=78℃) containing 0.25% by mass of calcium carbonate particles with an average particle size of 0.6 μm was melted in an extruder, passed through a filter with a filtration accuracy of 10 μm, extruded from a die, and cooled in a cooling drum by conventional methods to obtain an unstretched film. Next, it was stretched 3.3 times in the longitudinal direction at 80℃, and then the aqueous coating solution (aqueous coating composition) obtained in Production Example 1 was uniformly applied using a roll coater so that the release layer thickness shown in Table 2 corresponds to the product thickness. The aqueous coating solution used was prepared within 24 hours.

[0137] Next, the coated film was dried at 105°C, stretched 4.7 times in the transverse direction at 150°C, and then heat-set at 235°C for approximately 10 seconds to obtain a release film (thickness 25 μm) having a release layer formed by the reaction and solidification of the aqueous coating solution. This film was then evaluated. The evaluation results are shown in Table 2.

[0138] Furthermore, for each example and comparative example, the release film portions that did not become part of the product during the product roll collection process, as well as release film that was unsuitable for the product due to defects, were crushed until the film piece length was approximately 5 mm or less, melted, and 40% by mass of the recycled raw material was used.

[0139] <Manufacturing Example 1> (Sample 1A) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 95% by mass of silicone oil in which a1 of formula (1) is 100 mol%, b1 is 0 mol%, and the number average molecular weight is 9000, and 5% by mass of polyoxyethylene tridecyl ether (manufactured by ADEKA Corporation, product name "ADEKATOL TN-100") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion of sample 1A with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 210 nm by adjusting the stirring speed and stirring time during emulsification.

[0140] [ka]

[0141] (Sample 2A) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 94% by mass of silicone oil with a number average molecular weight of 4000, where a2 in formula (2) is 50 mol%, b2 is 50 mol%, and polyoxyethylene tridecyl ether (manufactured by Lion Specialty Chemicals Co., Ltd., product name "Leocol TD-90") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous dispersion of Sample 2 with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 170 nm by adjusting the stirring speed and stirring time during emulsification.

[0142] [ka]

[0143] (Water-based coating solution) As an aqueous coating solution, Sample 1A and Sample 2A were prepared so that the solid content mass of the silicone was as shown in Table 2, and the other components were as follows. 5% by mass of the coupling agent listed below relative to the total mass of silicone, 50 ppm of the platinum-based catalyst listed below relative to the total solid content mass of Sample 1A and Sample 2A, and 100 ppm of the crosslinking reaction inhibitor listed below relative to the mass of the coating solution were mixed. The solid content concentration of the coating solution was then diluted with water to achieve the target release layer thickness, and the coating solution was prepared. • Coupling agent: 3-Glycidoxypropyltriethoxysilane (manufactured by JNC Corporation, product name "Syra Ace S510") • Platinum-based catalyst: Platinum-based catalyst emulsion (manufactured by Wacker, product name "CATALYST EM440") • Crosslinking reaction inhibitor: 1-ethinylcyclohexanol (manufactured by Alfa Lancaster) [Example 2] In Example 1, the release film was prepared under exactly the same conditions as in Example 1, except that the aqueous coating solution was prepared using Sample 1B, which was produced in Production Example 2, instead of Sample 1A. The evaluation described above was then performed. The results are shown in Table 2.

[0144] <Manufacturing Example 2> (Sample 1B) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 95% by mass of silicone oil in which a1 of formula (1) is 100 mol%, b1 is 0 mol%, and the number average molecular weight is 5000, and 5% by mass of polyoxyethylene tridecyl ether (manufactured by ADEKA Corporation, product name "Adekatol TN-100") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion of Sample 1B with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 190 nm by adjusting the stirring speed and stirring time during emulsification.

[0145] [Example 3] In Example 1, the release film was prepared under exactly the same conditions as in Example 1, except that the aqueous coating solution was prepared using Sample 1C, which was produced in Production Example 3, instead of Sample 1A. The evaluation described above was then performed. The results are shown in Table 2.

[0146] <Manufacturing Example 3> (Sample 1C) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 95% by mass of silicone oil in formula (1) where a1 is 96 mol%, b1 is 4 mol%, and the number average molecular weight is 7000, and 5% by mass of polyoxyethylene tridecyl ether (manufactured by ADEKA Corporation, product name "Adekatol TN-100") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion of sample 1C with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 200 nm by adjusting the stirring speed and stirring time during emulsification.

[0147] [Example 4] In Example 1, the release film was prepared under exactly the same conditions as in Example 1, except that the aqueous coating solution was prepared using Sample 1D, which was produced in Production Example 4, instead of Sample 1A. The evaluation described above was then performed. The results are shown in Table 2.

[0148] <Manufacturing Example 4> (Sample 1D) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 95% by mass of silicone oil represented by formula (A) 2 mol%, formula (B) 4 mol%, formula (C) 90 mol%, formula (D) 2 mol%, and formula (E) 2 mol%, with a number average molecular weight of 8000, and 5% by mass of polyoxyethylene tridecyl ether (manufactured by ADEKA Corporation, product name "ADEKATOL TN-100") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion of sample 1D with a solid content of 45% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 200 nm by adjusting the stirring speed and stirring time during emulsification.

[0149] [ka]

[0150] [Example 5] In Example 4, the release film was prepared under exactly the same conditions as in Example 4, except that the contents of Sample 1D and Sample 2A were changed when preparing the aqueous coating solution, as shown in Table 2, and the evaluation described above was performed. The results are shown in Table 2.

[0151] [Comparative Examples 1-2] In Examples 4 and 5, release films were prepared under exactly the same conditions as in Examples 4 and 5, except that the aqueous coating solution obtained in Production Example 5 was used instead of the aqueous coating solution obtained in Production Example 4. The evaluation described above was then performed. The results are shown in Table 2.

[0152] <Manufacturing Example 5> (Sample 1E) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 96% by mass of silicone oil in formula (1) where a1 is 97 mol%, b1 is 3 mol%, and the number average molecular weight is 30,000, and 4% by mass of polyoxyethylene tridecyl ether (manufactured by Lion Specialty Chemicals Co., Ltd., product name "Leocol TD-90") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous emulsion of sample 1E with a solid content of 50% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 200 nm by adjusting the stirring speed and stirring time during emulsification.

[0153] (Sample 2B) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 94% by mass of silicone oil in which a3 of formula (2) is 50 mol%, b3 is 50 mol%, and the number average molecular weight is 8000, and 6% by mass of polyoxyethylene tridecyl ether (manufactured by Lion Specialty Chemicals Co., Ltd., product name "Leocol TD-90") as a surfactant was mechanically emulsified in an aqueous medium to obtain an aqueous dispersion of Sample 2 with a solid content of 50% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 180 nm by adjusting the stirring speed and stirring time during emulsification.

[0154] (Water-based coating solution) The aqueous coating solution was prepared under the same conditions as in Production Example 1, except that the solid content mass of the silicone in Sample 1E and Sample 2B was adjusted to the amounts shown in Table 2.

[0155] [Table 2]

[0156] As shown in Table 2, in Examples 1 to 5, the erosion rate is 0.003 μm / g or higher, resulting in good half-cut performance evaluation and reducing the likelihood of adhesion to the half-cut portion when peeling off the sheet-like molded product after half-cutting. In contrast, in Comparative Examples 1 and 2, the erosion rate is less than 0.003 μm / g, and despite the low surface free energy, the half-cut performance evaluation is poor, making it easier for adhesion to the half-cut portion to occur when peeling off the sheet-like molded product after half-cutting.

[0157] In Examples 1-5, the surface free energy was at an appropriate level, and the coating uniformity and recyclability were also good. [Industrial applicability]

[0158] The release film of the present invention is easy to use as a process material for various processes because it is less likely to cause problems due to adhesion to the half-cut portion when peeling off a sheet-like molded product after half-cutting, and it is also recyclable, making it extremely valuable for industrial use.

Claims

1. A release film having a base film and a release layer, In a micro-slurry jet erosion test, the aforementioned release layer exhibited an erosion rate of 0.019 μm / g relative to the polymethyl methacrylate resin at a projection force that resulted in an average particle size (D ５０ The erosion rate when a slurry of 0.3 μm polygonal alumina particles dispersed in water is projected is 0.003 μm / g or higher. The release layer is formed by reacting and solidifying a reaction-curable composition containing a silicone-based compound. The reaction-curable composition includes an alkenyl group-containing silicone having Q units represented by SiO₄ / 2. Release film.

2. The release film according to claim 1, wherein the base film is a polyester film.

3. The release film according to claim 1 or 2, wherein the release film is a release film for multilayer ceramic capacitors or a release film for resin sheets.

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