Release film

Abstract

A release film including a polyester film and a release layer, wherein the release layer is a layer obtained by curing a silicone composition containing addition-curable silicone, and the silicone composition contains a resin containing neither a silicon atom nor a nitrogen atom in a molecule but containing multiple alkenyl groups and multiple rings in the molecule.

Description

Technical Field

[0001] The present invention relates to a release film.

Background Art

[0002] Conventionally, release films including a polyester film and a release layer have been used in various applications. For example, they are not only used for molding ceramic green sheets, but also used in, for example, the production of adhesive sheets, cover films, polymer films, and optical lenses.

[0003] Depending on the application of the release film, various resins are used for the release layer of the release film. In the case of a release film for an application where light peelability is required, a silicone resin is often used. A release layer using a silicone resin, that is, a silicone release layer, can be formed, for example, by crosslinking a silicone resin having an alkenyl group and a silicone crosslinking agent having a hydrosilyl group.

[0004] When a liquid fluid (for example, a ceramic slurry or a liquid composition for forming a polymer film) is applied to the silicone release layer, the edge of the applied fluid may partially recede, resulting in a phenomenon where the distribution of the fluid becomes non-uniform, that is, peeling may occur. In addition to this, pinholes may also occur. Peeling and pinholes lead to a decrease in yield and an increase in the defect rate.

[0005] In order to suppress the occurrence of peeling, release films have been proposed in which resins other than the main silicone resin (for example, alkyd resins, acrylic resins, etc.) are used for the release layer (see Patent Documents 1 and 2). However, such release films tend to have a heavy peeling force (that is, a large peeling force), and thus such release films have to be said to have limitations in the range of applications.

[0006] On the other hand, in Patent Document 3, in order to solve the problem that the edge of the applied ceramic slurry bulges, that is, the problem of repelling, a release film including a silicone release layer formed using a phenyl-modified polydimethylsiloxane having an alkenyl group has been proposed. However, since the structure of the phenyl-modified polydimethylsiloxane having an alkenyl group is limited in the sense that it is polydimethylsiloxane, the adjustment range of the peeling force by this phenyl-modified polydimethylsiloxane is also limited. Considering this, it has to be said that there is also a limit to the range of uses of the release film. In fact, in Patent Document 3, the use of the release film is limited to ceramic green sheet molding. Under such circumstances, a new method capable of suppressing the occurrence of repelling is required.

[0007] By the way, in a release film having a polyester film and a silicone release layer provided on the polyester film, if the adhesion between the polyester film and the silicone release layer is poor, the silicone constituting the silicone release layer may fall off from the polyester film. Since the fallen silicone may be transferred to an adherend (for example, a ceramic green sheet) disposed or formed on the release layer, the fall of the silicone release layer may lead to some problems (for example, deterioration of yield or defect rate). In order to suppress the fall of the silicone release layer, although it is known to add an adhesion promoter to the composition for forming the silicone release layer (see Patent Document 4), there is still a need for a new method capable of improving the adhesion between the silicone release layer and the polyester film.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention aims to provide a release film that can reduce the degree of repellency or suppress the occurrence of repellency, and moreover, can improve the adhesion between the release layer and the polyester film, and can avoid the release force from becoming excessively strong.

Means for Solving the Problems

[0010] To solve this problem, the present invention has the configuration of the following [1]. [1] A polyester film, and a release layer, wherein the release layer is a layer obtained by curing a silicone composition containing an addition-curable silicone, the silicone composition contains a resin that contains neither a silicon atom nor a nitrogen atom in the molecule and contains a plurality of alkenyl groups and a plurality of rings in the molecule, each of the rings is independently selected from at least one of the group consisting of a monovalent aromatic ring, a divalent aromatic ring, a monovalent aliphatic ring, and a divalent aliphatic ring, Release film. Here, "addition-curable silicone" is defined in this specification as including a polysiloxane containing a hydrosilyl group, that is, a SiH group. "Silicone composition" is defined in this specification as a composition that can be cured at least by hydrosilylation.

[0011] The present invention preferably further has the configurations of [2] and subsequent ones.

[0012] [2] The release film according to [1], wherein the alkenyl group is an allyl group.

[0013] [3] The release film according to [1] or [2], wherein each of the rings is independently at least one selected from the group consisting of a phenylene group, a naphthylene group, a cyclopentylene group, and a cyclohexylene group.

[0014] [4] The release film according to any one of [1] to [3], wherein the resin contains a plurality of ester bonds in the molecule.

[0015] [5] The release film according to any one of [1] to [4], wherein the resin contains a plurality of structural units represented by the following formula (hereinafter sometimes referred to as "Formula C-U1") in the molecule. [Chemical formula] (A plurality of X are each independently at least one selected from the group consisting of a phenylene group, a naphthylene group, a cyclopentylene group, and a cyclohexylene group.) Among the release films according to [5], the release film citing [1] can be rephrased as follows. A polyester film and a release layer, and the release layer is a layer obtained by curing a silicone composition containing an addition-curable silicone, the silicone composition contains no silicon atom or nitrogen atom in the molecule, and contains a resin containing a plurality of structural units represented by the above formula (that is, Formula C-U1) in the molecule, a release film.

[0016] [6] The release film according to any one of [1] to [5], wherein the weight average molecular weight of the resin is 4000 or more.

[0017] [7] The release film according to any one of [1] to [6], which is used for manufacturing a ceramic green sheet.

[0018] [8] The release film according to any one of [1] to [7], wherein the resin contains a plurality of structural units represented by the following formula (hereinafter sometimes referred to as "Formula C-U2") in the molecule together with the structural unit represented by the formula C-U1.

Chemical formula

Advantages of the Invention

[0019] According to the present invention, it is possible to reduce the degree of repellency or suppress the occurrence of repellency, and moreover, it is possible to improve the adhesion between the release layer and the polyester film, and furthermore, it is possible to provide a release film capable of avoiding an excessive increase in the peel force.

Embodiments for Carrying Out the Invention

[0020] <1. First> The release film of the present embodiment is a polyester film, and a release layer, and the release layer is a layer obtained by curing a silicone composition containing an addition-curable silicone, the silicone composition contains a resin that contains neither a silicon atom nor a nitrogen atom in the molecule and contains a plurality of alkenyl groups and a plurality of rings in the molecule, each of the rings is independently at least one selected from the group consisting of a monovalent aromatic ring, a divalent aromatic ring, a monovalent aliphatic ring, and a divalent aliphatic ring.

[0021] In the release film of the present embodiment, since the resin in the silicone composition contains a plurality of rings, it is possible to reduce the degree of repellency that may occur when a liquid flowing material such as a ceramic slurry is applied to the release film, or to suppress the occurrence of repellency. This is presumably because a plurality of rings of the resin form extremely minute irregularities on the surface of the release layer, and as a result, the adhesion energy (specifically, the adhesion energy obtained by measuring the sliding angle using water. Hereinafter, it may be referred to as "water adhesion energy") is improved. It is also considered that this (specifically, the ability to reduce the degree of repellency or suppress the occurrence of repellency by a plurality of rings of the resin) is because a plurality of rings of the resin disrupt the arrangement of the organic groups (for example, methyl groups) of the polysiloxane in the silicone composition on the surface of the release layer, thereby improving the adhesion energy.

[0022] Moreover, since the resin in the silicone composition contains a plurality of alkenyl groups, the adhesion between the release layer and the polyester film can be improved. This is presumably because the resin in the silicone composition (specifically, the resin containing a plurality of alkenyl groups) is somewhat biased toward the polyester film, and the alkenyl groups of the resin present toward the polyester film can undergo an addition reaction (i.e., hydrosilylation) with the hydrosilyl groups in the silicone composition.

[0023] Furthermore, the resin in the silicone composition does not have silicon atoms or nitrogen atoms in the molecule, that is, it is neither a melamine resin nor a silane coupling agent. Thus, according to the release film of the present embodiment, it is possible to reduce the degree of repellency, suppress the occurrence of repellency, and improve the adhesion between the release layer and the polyester film without using a melamine resin or a silane coupling agent.

[0024] In addition, since the resin in the silicone composition is a resin rather than a monomer, it is possible to avoid the release force when peeling the coating film from the release film (for example, the release force when peeling a coating film formed by applying a liquid fluid such as a ceramic slurry to a release film, drying it, and curing it as necessary) from becoming excessively strong. That is, excessive re-peeling can be avoided. This is presumably because the resin in the silicone composition is less likely to move to the surface of the release layer and less likely to precipitate on the surface of the release layer compared to the monomer. This will be explained. Assuming that it was a monomer instead of the resin, the monomer would be likely to move to the surface of the release layer and emerge on the surface of the release layer. Therefore, the monomer may cause excessive re-peeling. On the other hand, in the release film of the present embodiment, since the resin in the silicone composition is a resin rather than a monomer, it is less likely to move to the surface of the release layer and less likely to precipitate on the surface of the release layer. Therefore, according to the release film of the present embodiment, since the resin in the silicone composition is a resin rather than a monomer, that is, a polymer, excessive re-peeling can be avoided.

[0025] Hereinafter, embodiments of the present invention will be described in more detail.

[0026] <2. Release Film> The release film of the present embodiment includes a polyester film and a release layer. Specifically, the release film of the present embodiment includes a polyester film and a release layer provided on at least one surface of the polyester film.

[0027] An easy-adhesion layer, an antistatic layer, a smoothing layer, etc. may be provided between the release layer and the polyester film. In the present embodiment, good adhesion can be easily obtained even without an easy-adhesion layer or the like intervening. That is, as a preferred embodiment, a release film in which a release layer is directly provided on a polyester film is exemplified.

[0028] <2.1. Release Layer> The release layer is a layer formed by curing a silicone composition. Here, the silicone composition contains an addition-curable silicone and is a composition that can be cured at least by hydrosilylation. Note that hydrosilylation is a reaction in which a polysiloxane containing an SiH group adds to an unsaturated bond such as a carbon-carbon double bond with cleavage of the Si-H bond.

[0029] The addition-curable silicone contained in the silicone composition contains a hydrosilyl group, that is, a polysiloxane containing an SiH group. The addition-curable silicone preferably contains, for example, a polysiloxane A containing two or more alkenyl groups in the molecule and a polysiloxane B containing two or more hydrosilyl groups in the molecule. That is, the silicone composition preferably contains a polysiloxane A containing two or more alkenyl groups in the molecule and a polysiloxane B containing two or more hydrosilyl groups in the molecule.

[0030] <2.1.1. Polysiloxane A> The polysiloxane A only needs to contain two or more alkenyl groups in the side chain and / or at the terminal, and a polyorganosiloxane containing an alkenyl group at least in the side chain is preferred, and a polyorganosiloxane containing an alkenyl group only in the side chain is more preferred. Also, a copolymer containing a siloxane unit containing an alkenyl group and a dialkylsiloxane unit or an alkylphenylsiloxane unit is preferred because it is easy to adjust the amount of alkenyl groups in one molecule while exhibiting release properties. The terminal silicon atom preferably has a trialkylsilane structure such as trimethylsilane.

[0031] Examples of the alkenyl group include alkenyl groups having 2 to 10 carbon atoms. By including such an alkenyl group, the strength of the release layer becomes excellent. The alkenyl group is preferably an alkenyl group having 2 to 8 carbon atoms, more preferably an alkenyl group having 2 to 6 carbon atoms, and particularly preferably a vinyl group or a hexenyl group. A plurality of alkenyl groups may be bonded to the silicon atom to which the alkenyl group is bonded, but it is preferable that an alkenyl group and an alkyl group are bonded. As the alkyl group in that case, a methyl group or the like is preferable.

[0032] In addition to the siloxane unit containing an alkenyl group, examples of the dialkylsiloxane unit contained in polysiloxane A include dimethylsiloxane units and phenylmethylsiloxane units, which are preferably exemplified.

[0033] Examples of the polysiloxane as described above include polysiloxanes represented by the following structural formula (1).

[0034]

Chemical formula

[0035] Note that the above formula does not mean an embodiment of a block copolymer, but merely indicates that the total numbers of these respective units are l, m, and n. Therefore, the polysiloxane in the above formula may be a random copolymer or a block copolymer.

[0036] In this embodiment, as the polysiloxane A, one type of the polysiloxanes as described above may be used alone, a polysiloxane containing two or more different alkenyl groups in one molecule may be used, or two or more polysiloxanes having different structures, such as those containing different alkenyl groups, may be used in combination.

[0037] The weight average molecular weight of the polysiloxane A is preferably 300,000 or more and 600,000 or less, and particularly preferably 400,000 or more and 550,000 or less. The weight average molecular weight in this specification is a value in terms of standard polystyrene measured by gel permeation chromatography (GPC) method.

[0038] When the weight average molecular weight of the polysiloxane A is 300,000 or more, the release layer after crosslinking has appropriate coating film strength, and the peeling off of the coating film can be more effectively prevented. Also, when the weight average molecular weight is 600,000 or less, the planarity of the coating film after drying is good.

[0039] <2.1.2. Polysiloxane B> The polysiloxane B only needs to contain two or more hydrosilyl groups (groups in which a hydrogen atom is directly bonded to a silicon atom) in the side chain and / or at the terminal, and a hydrogen polysiloxane containing a hydrosilyl group at least in the side chain is preferable, and a hydrogen polysiloxane containing a hydrosilyl group only in the side chain is more preferable. Also, a copolymer containing a siloxane unit containing a hydrosilyl group and a dialkylsiloxane unit or an alkylphenylsiloxane unit is preferable because it is easy to adjust the amount of hydrosilyl groups in one molecule while exhibiting releasability. A plurality of hydrogen atoms may be directly bonded to the silicon atom to which the hydrogen atom is directly bonded, but it is preferable that a hydrogen atom and an alkyl group are bonded. As the alkyl group in that case, a methyl group or the like is preferable. The terminal silicon atom preferably has a trialkylsilane structure such as trimethylsilane.

[0040] In addition to the siloxane units containing a hydrosilyl group, examples of the dialkylsiloxane units contained in polysiloxane B include dimethylsiloxane units, phenylmethylsiloxane units, etc., which are preferably exemplified.

[0041] Examples of such hydrogen polysiloxanes include polysiloxanes represented by the following structural formula (2).

[0042]

Chemical formula

[0043] Note that the above formula does not mean an aspect of a block copolymer, but merely indicates that the total number of each unit is o and p. Therefore, the hydrogen polysiloxane in the above formula may be a random copolymer or a block copolymer.

[0044] As polysiloxane B, one type of the above hydrogen polysiloxane may be used alone, or two or more types of hydrogen polysiloxanes having different structures, such as different numbers of hydrosilyl groups in one molecule, may be used in combination.

[0045] The weight average molecular weight of polysiloxane B is preferably 5000 or more and 100000 or less, particularly preferably 7000 or more and 20000 or less. When the weight average molecular weight of polysiloxane B is 5000 or more, the release layer after crosslinking has appropriate coating film strength, and it is possible to prevent the coating film from peeling off. Also, when the weight average molecular weight is 100000 or less, the planarity of the dried coating film becomes good.

[0046] In this embodiment, the polysiloxane A and the polysiloxane B are preferably those obtained by addition polymerization in the presence of a platinum-based catalyst or the like described later, and serve as the main components of the release layer. The addition polymerization referred to here means that the functional group at the molecular terminal or in the molecular side chain in the polysiloxane A represented by ~Si-CH=CH2 or ~Si-R-CH=CH2 and the functional group at the molecular terminal or in the molecular side chain in the polysiloxane B represented by H-Si~ react to form ~Si-CH2CH2-Si~ or ~Si-R-CH2CH2-Si~. However, "~" in the above functional group indicates that the molecule is further connected. When the reaction at this time is represented as a reaction formula, it is shown as the following formula. Here, R represents an alkylene group having 1 or more and 8 or less carbon atoms.

[0047]

Chemical formula

[0048] <2.1.3. Mixing mass ratio and total content of polysiloxane A and B> In the silicone composition, the mixing mass ratio (B / A) of the polysiloxane A and the polysiloxane B can be set as appropriate.

[0049] The total content of the polysiloxane A and the polysiloxane B is preferably 20% by mass or more, more preferably 40% by mass or more, still more preferably 60% by mass or more, and still more preferably 70% by mass or more in 100% by mass of the solid content in the silicone composition. On the other hand, the total content of the polysiloxane A and the polysiloxane B is preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less, and still more preferably 80% by mass or less.

[0050] <2.1.4. Resin containing neither silicon atoms nor nitrogen atoms in the molecule, and containing a plurality of alkenyl groups and a plurality of rings in the molecule (resin C)> The silicone composition contains a resin (hereinafter sometimes referred to as "resin C") that contains neither silicon atoms nor nitrogen atoms in the molecule and contains a plurality of alkenyl groups and a plurality of rings in the molecule. That is, the silicone composition contains a polymer that contains neither silicon atoms nor nitrogen atoms and contains a plurality of alkenyl groups and a plurality of rings.

[0051] Since resin C contains a plurality of rings, it is possible to reduce the degree of repellency that may occur when a liquid fluid such as a ceramic slurry is applied to a release film, or to suppress the occurrence of repellency. This is presumably because a plurality of rings of resin C form extremely minute irregularities on the surface of the release layer, and as a result, the adhesion energy (specifically, water adhesion energy) is improved. This (specifically, the fact that the degree of repellency can be reduced or the occurrence of repellency can be suppressed by a plurality of rings of the resin) is also presumably because a plurality of rings of resin C disrupt the arrangement of the organic groups (for example, methyl groups) of the polysiloxane in the silicone composition on the surface of the release layer, thereby improving the adhesion energy.

[0052] Moreover, since resin C contains a plurality of alkenyl groups, the adhesion between the release layer and the polyester film can be improved. This is presumably because resin C is somewhat biased toward the polyester film, and the alkenyl groups of resin C present closer to the polyester film can undergo an addition reaction (i.e., hydrosilylation) with the hydrosilyl groups in the silicone composition.

[0053] Furthermore, since resin C contains a plurality of alkenyl groups, the strength of the release layer (i.e., the amount of deformation until rupture) can also be increased compared to the case where no alkenyl groups are contained at all. This is presumably because resin C can undergo hydrosilylation or crosslinking between the molecules (i.e., polymers) in resin C by containing a plurality of alkenyl groups.

[0054] Moreover, resin C does not have silicon atoms or nitrogen atoms in its molecule, that is, it is neither a melamine resin nor a silane coupling agent. Thus, according to the release film of this embodiment, it is possible to reduce the degree of repellency, suppress the occurrence of repellency, and improve the adhesion between the release layer and the polyester film without using a melamine resin or a silane coupling agent.

[0055] In addition, since resin C is a resin rather than a monomer, it is possible to avoid the peeling force (for example, the peeling force when peeling a coating film formed by applying a liquid flowing material such as a ceramic slurry onto a release film, drying it, and curing it as necessary) from becoming excessively strong when peeling the coating film from the release film. That is, it is possible to avoid excessive double peeling. This is presumably because resin C is less likely to move to the surface of the release layer and less likely to precipitate on the surface of the release layer compared to a monomer. This will be explained. Suppose that instead of resin C, it is a monomer. Then the monomer is likely to move to the surface of the release layer and is likely to come out on the surface of the release layer. Therefore, the monomer may cause excessive double peeling. On the other hand, in the release film of this embodiment, since resin C is a resin rather than a monomer, it is less likely to move to the surface of the release layer and less likely to precipitate on the surface of the release layer. Therefore, according to the release film of this embodiment, since resin C is a resin rather than a monomer, it is possible to avoid excessive double peeling.

[0056] The alkenyl groups contained in the molecule of resin C are preferably each independently an alkenyl group having 2 to 6 carbon atoms. Examples of such alkenyl groups include a vinyl group and an allyl group. Among them, the allyl group is more preferable because the product used in the examples described later is commercially available and basically easy to obtain.

[0057] The rings contained in the molecule of Resin C are each independently at least one selected from the group consisting of a monovalent aromatic ring, a divalent aromatic ring, a monovalent aliphatic ring, and a divalent aliphatic ring. Examples of the monovalent aromatic ring, i.e., an aryl group, include a phenyl group and a naphthyl group (e.g., 1-naphthyl group, 2-naphthyl group). Examples of the divalent aromatic ring, i.e., an arylene group, include a phenylene group (e.g., o-phenylene group, m-phenylene group, p-phenylene group) and a naphthylene group (e.g., 2,6-naphthylene group). Examples of the monovalent aliphatic ring, i.e., a cycloalkyl group, include a cyclopentyl group and a cyclohexyl group. Examples of the divalent aliphatic ring, i.e., a cycloalkylene group, include a cyclopentylene group (e.g., 1,2-cyclopentylene group, 1,3-cyclopentylene group) and a cyclohexylene group (e.g., 1,2-cyclohexylene group, 1,3-cyclohexylene group, 1,4-cyclohexylene group). Among them, since the products used in the examples described later are commercially available and basically easy to obtain, the divalent aromatic ring and the divalent aliphatic ring are preferred. That is, the rings in the molecule are each independently preferably a divalent aromatic ring or a divalent aliphatic ring. In particular, due to the reason that the rings are stable and can stably exhibit the effects of reducing and suppressing repellency, a phenylene group, a naphthylene group, a cyclopentylene group, and a cyclohexylene group are preferred, and a phenylene group and a cyclohexylene group are more preferred. That is, the rings in the molecule are each independently preferably at least one selected from the group consisting of a phenylene group, a naphthylene group, a cyclopentylene group, and a cyclohexylene group, and more preferably a phenylene group or a cyclohexylene group.

[0058] It is preferable that Resin C contains a plurality of ester bonds, that is, a plurality of ester groups in the molecule. Since the presence of an ester bond in Resin C can generate an electrostatic attraction between the ester bond and polar groups (such as carboxyl groups and hydroxy groups) present on the surface of the polyester film (for example, the corona discharge treated surface), the adhesion between the release layer and the polyester film can be further improved.

[0059] Specifically describing a preferred example of Resin C, it is preferable that Resin C contains a plurality of structural units represented by the following formula (hereinafter sometimes referred to as "Formula C-U1") in the molecule.

Chemical formula

[0060] By Resin C containing a plurality of structural units represented by Formula C-U1, the occurrence of repelling can be further suppressed, and the adhesion between the release layer and the polyester film can be further improved.

[0061] Resin C may contain a plurality of structural units represented by the following formula (hereinafter sometimes referred to as "Formula C-U2") in the molecule together with the structural unit represented by Formula C-U1.

Chemical formula

[0062] When the resin C contains in the molecule a structural unit represented by the formula C-U1 and a structural unit represented by the formula C-U2, it is preferable that both the plurality of Xs and the plurality of Ys are phenylene groups or both the plurality of Xs and the plurality of Ys are cyclohexylene groups.

[0063] The molar ratio of the structural unit represented by the formula C-U1 to the structural unit represented by the formula C-U2, specifically, the number of moles of the structural unit represented by the formula C-U1 / the number of moles of the structural unit represented by the formula C-U2, may be 0.5 or more, may be 0.7 or more, or may be 0.8 or more. This molar ratio may be, for example, 1.5 or less, 1.3 or less, or 1.2 or less.

[0064] The resin C preferably contains a structure represented by the following formula (hereinafter sometimes referred to as "formula C-P").

Chemical formula

[0065] The plurality of Ys are each independently a divalent aromatic ring or a divalent aliphatic ring. Each of the plurality of Ys is preferably a phenylene group, a naphthylene group, a cyclopentylene group, or a cyclohexylene group, and more preferably a phenylene group or a cyclohexylene group. It is even more preferable that the plurality of Ys are commonly a phenylene group or commonly a cyclohexylene group. When the plurality of Ys are commonly a phenylene group, the two ester bonds adjacent to the phenylene group may be in the ortho position, the meta position, or the para position.

[0066] It is particularly preferable that both the plurality of Xs and the plurality of Ys are phenylene groups, or both the plurality of Xs and the plurality of Ys are cyclohexylene groups.

[0067] m is an integer of 2 or more, and n is also an integer of 2 or more. The structure represented by formula C-P includes a structural unit represented by formula C-U1 and a structural unit represented by formula C-U2. The molar ratio of the structural unit represented by formula C-U1 to the structural unit represented by formula C-U2 (specifically, the number of moles of the structural unit represented by formula C-U1 / the number of moles of the structural unit represented by formula C-U2) may be 0.5 or more, may be 0.7 or more, or may be 0.8 or more. This molar ratio may be, for example, 1.5 or less, may be 1.3 or less, or may be 1.2 or less.

[0068] Note that the formula C-P does not mean a block copolymer, but simply indicates that the total number of each unit is m and n. Therefore, the polymer containing the structure represented by the formula C-P may be a random copolymer or a block copolymer. Among them, a random copolymer is preferred.

[0069] Preferable examples of the resin C include diallyl phthalate resin and diallyl cyclohexane resin. When the resin C is diallyl phthalate resin or diallyl cyclohexane resin, the generation of repellency can be further suppressed, and the adhesion between the release layer and the polyester film can be further improved. Examples of the diallyl phthalate resin include resins containing a plurality of structural units represented by the formula C-U1 in the molecule and having X as a phenylene group. Examples of the diallyl phthalate resin also include resins containing the structure represented by the formula C-P and having both X and Y as phenylene groups. Commercially available products of the diallyl phthalate resin include, for example, DAP-K, ISODAP, and DAP-A manufactured by Osaka Soda Co., Ltd. Examples of the diallyl cyclohexane resin include resins containing a plurality of structural units represented by the formula C-U1 in the molecule and having X as a cyclohexylene group. Examples of the diallyl phthalate resin also include resins containing the structure represented by the formula C-P and having both X and Y as cyclohexylene groups. A commercially available product of the diallyl cyclohexane resin includes, for example, AD-032 manufactured by Osaka Soda Co., Ltd.

[0070] The diallyl cyclohexane resin is preferably a polymer containing a structure represented by the following formula (hereinafter sometimes referred to as "formula C1").

Chemical formula

[0071] Note that formula C1 does not mean a block copolymer, but simply indicates that the total number of each unit is m and n. Therefore, the polymer containing the structure represented by formula C1 may be a random copolymer or a block copolymer. Among them, a random copolymer is preferred.

[0072] The diallyl phthalate resin preferably contains a polymer represented by the following formula (hereinafter sometimes referred to as "formula C2").

Chemical formula

[0073] Note that formula C2 does not mean a block copolymer, but simply indicates that the total number of each unit is m and n. Therefore, the polymer containing the structure represented by formula C2 may be a random copolymer or a block copolymer. Among them, a random copolymer is preferred.

[0074] The diallyl phthalate resin preferably contains a polymer having a structure represented by the following formula (hereinafter sometimes referred to as "Formula C3").

Chemical formula

[0075] The polymers containing the structures represented by Formula C1, Formula C2, and Formula C3 may contain other structural units in addition to the structural units shown in those formulas.

[0076] The weight average molecular weight of Resin C is preferably 4000 or more, more preferably 5000 or more, still more preferably 10000 or more, and even more preferably 15000 or more. When it is 4000 or more, the peeling force when peeling the coating film from the release film (for example, the peeling force when peeling the coating film formed by applying a liquid flowing material such as a ceramic slurry to the release film, drying it, and curing it as necessary from the release film) can be further avoided from becoming excessively strong. This is presumably because when the weight average molecular weight is 4000 or more, Resin C is more difficult to move to the surface of the release layer and more difficult to precipitate on the surface of the release layer. On the other hand, the weight average molecular weight of Resin C may be, for example, 200000 or less, 100000 or less, 80000 or less, or 60000 or less. The weight average molecular weight in this specification is a value in terms of standard polystyrene measured by the gel permeation chromatography (GPC) method.

[0077] When the total amount of polysiloxane A and polysiloxane B is 100 parts by mass, the content of resin C in the silicone composition is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more. When it is 5 parts by mass or more, the degree of repellency can be further reduced, the generation of repellency can be further suppressed, and the adhesion between the release layer and the polyester film can be further improved. On the other hand, when the total of polysiloxane A and polysiloxane B is 100 parts by mass, the content of resin C is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, still more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. When it is 80 parts by mass or less, it is possible to further avoid the peeling force (for example, the peeling force when peeling a coating film formed by applying a liquid flowing material such as a ceramic slurry to a release film, drying it, and curing it as necessary) from becoming excessively strong.

[0078] <2.1.5. Catalyst> The silicone composition preferably further contains a catalyst. The catalyst is not particularly limited as long as it can promote the curing reaction of the silicone composition, but platinum group metal-based compounds are particularly preferred.

[0079] Examples of platinum group metal-based compounds include particulate platinum, particulate platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, palladium, rhodium, and the like. By containing such a catalyst in the silicone composition, the curing reaction of the silicone composition can proceed more efficiently.

[0080] The content of the catalyst in the silicone composition is preferably about 1 ppm or more and 1000 ppm or less with respect to the total amount of polysiloxane A and polysiloxane B.

[0081] <2.1.6. Photoinitiator> The silicone composition preferably further contains a photoinitiator. In particular, when the content of Resin C is high (for example, when Resin C is 50 parts by mass or more based on a total of 100 parts by mass of Polysiloxane A and Polysiloxane B), it is preferable to contain a photoinitiator. The reason is that since a catalyst such as a platinum group metal compound is considered to exist in a compatible manner with Polysiloxane A and Polysiloxane B, there is a possibility that the catalyst may not act efficiently in the self-crosslinking reaction of Resin C. Examples of the photoinitiator include alkylphenone-based photoinitiators. Specifically, Omnirad 185, Omnirad 907, etc. can be mentioned.

[0082] The content of the photoinitiator in the silicone composition is preferably about 1 ppm or more and 1000 ppm or less with respect to the total amount of all solid components other than the photoinitiator.

[0083] <2.1.7. Other Components> In addition to the above components, the silicone composition may contain a reaction inhibitor, a solvent, a silicone resin having no reactive functional group, an antistatic agent, a melamine resin, a silane coupling agent, etc.

[0084] <2.1.8. Thickness of Release Layer> The thickness of the release layer is preferably 0.005 μm or more, more preferably 0.01 μm or more. When it is 0.005 μm or more, the function as a release layer can be effectively exhibited. On the other hand, the thickness of the mold layer is preferably 0.5 μm or less, more preferably 0.1 μm or less, and even more preferably 0.05 μm or less. When it is 0.5 μm or less, the occurrence of breakage in the release layer, that is, cohesive failure, can be suppressed.

[0085] <2.2. Polyester Film> In this embodiment, the polyester film used as the base film (hereinafter sometimes referred to as the base material) is a film containing polyester as a resin component, and preferably, it is a film containing the most polyester (for example, 90% by mass or more) in the resin component.

[0086] The polyester constituting the polyester film is not particularly limited, and a film formed by molding a polyester generally commonly used as a base material for a release film can be used. Preferably, it is a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component. For example, polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, or a copolymer mainly composed of the constituent components of these resins is more preferable.

[0087] In particular, a polyester film formed from polyethylene terephthalate is particularly preferable. In polyethylene terephthalate, the repeating unit of ethylene terephthalate is preferably 90 mol% or more, more preferably 95 mol% or more, and a small amount of other dicarboxylic acid components and diol components may be copolymerized. For example, from the viewpoint of cost, those produced only from terephthalic acid and ethylene glycol are preferable. In addition, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, and crystallization agents may be added to the polyester film. The polyester film is preferably a biaxially oriented polyester film for reasons such as high biaxial elastic modulus.

[0088] The intrinsic viscosity of the polyethylene terephthalate film 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, the frequency of breakage in the stretching process can be reduced. On the other hand, when it is 0.70 dl / g or less, the cuttability is good when cutting to a predetermined product width, so the frequency of occurrence of dimensional defects can be reduced. Incidentally, it is preferable to sufficiently vacuum dry the raw material pellets.

[0089] In the present specification, when simply described as "polyester film", it may mean a (laminated) polyester film including surface layer A and surface layer B.

[0090] The method for manufacturing the polyester film is not particularly limited, and a conventionally generally used method can be employed. For example, the polyester can be melted by an extruder, extruded into a film shape, and cooled by a rotary cooling drum to obtain an unstretched film, which can be obtained by uniaxially or biaxially stretching the unstretched film. The biaxially stretched film can be obtained by a method of sequentially biaxially stretching a uniaxially stretched film in the longitudinal or transverse direction in the transverse or longitudinal direction, or a method of simultaneously biaxially stretching the unstretched film in the longitudinal and transverse directions.

[0091] The stretching temperature during the stretching of the polyester film is preferably equal to or higher than the secondary transition point (Tg) of the polyester. It is preferable to perform stretching of 1 to 8 times, particularly 2 to 6 times, in each of the longitudinal and transverse directions.

[0092] The above polyester film preferably has a thickness of 12 μm or more and 50 μm or less, more preferably 15 μm or more and 38 μm or less, and still more preferably 19 μm or more and 33 μm or less. If the film thickness is 12 μm or more, there is no risk of deformation due to heat during film production, processing steps, or molding, which is preferable. On the other hand, if the film thickness is 50 μm or less, the amount of film to be discarded after use does not extremely increase, which is preferable in terms of reducing the environmental load.

[0093] The polyester film may be single-layer or multi-layer of two or more layers. For example, the polyester film may include a surface layer A substantially free of particles having a particle size of 1.0 μm or more and a surface layer B containing particles. The surface layer A preferably substantially does not contain inorganic particles having a particle size of 1.0 μm or more.

[0094] In this embodiment, particles having a particle size of less than 1.0 μm and 1 nm or more may be present in the surface layer A. By making the surface layer A substantially free of particles having a particle size of 1.0 μm or more, such as inorganic particles, it is possible to reduce defects caused by the transfer of the particle shape in the substrate to the resin sheet.

[0095] In one embodiment, the surface layer A does not contain any particles having a particle diameter of less than 1.0 μm, so that defects caused by the transfer of the particle shape in the substrate to the resin sheet can be more effectively prevented.

[0096] In one embodiment, the polyester film substrate is preferably a laminate film having a surface layer A substantially free of inorganic particles on at least one side thereof, which can more effectively prevent defects caused by the transfer of particle shapes in the substrate to the resin sheet.

[0097] For example, a preferred embodiment is one in which the surface layer A substantially does not contain particles having a particle size of less than 1.0 μm, and also substantially does not contain particles having a particle size of 1.0 μm or more.

[0098] Here, in the present invention, "substantially free of particles" means, for example, in the case of inorganic particles less than 1.0 μm, that the content is 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit when the inorganic elements are quantified by fluorescent X-ray analysis. This is because even if particles are not actively added to the film, contaminants from foreign matter or dirt attached to the raw material resin or the line or equipment in the film manufacturing process may peel off and be mixed into the film. In addition, "substantially free of particles with a particle size of 1.0 μm or more" means that particles with a particle size of 1.0 μm or more are not actively included.

[0099] In the case of a laminated polyester film having a multi-layer structure of two or more layers, it is preferable that a surface layer B that can contain inorganic particles is provided on the surface opposite to a surface layer A that does not substantially contain inorganic particles.

[0100] As for the laminated structure, assuming that the layer on the side where the release layer is applied is layer A, the layer on the opposite side is layer B, and the core layer other than these is layer C, the layer structure in the thickness direction includes laminated structures such as release layer / A / B, or release layer / A / C / B. Naturally, layer C may have a plurality of layer structures. Also, the surface layer B may not contain inorganic particles. In that case, in order to impart slipperiness for winding the film in a roll shape, it is preferable to provide a coat layer D containing at least inorganic particles and a binder on the surface layer B.

[0101] In the polyester film base material of the present invention, the surface layer B forming the opposite surface to the surface where the release layer is applied preferably contains inorganic particles from the viewpoints of the slipperiness of the film and the ease of air escape, and particularly preferably uses silica particles and / or calcium carbonate particles. The total content of the inorganic particles contained is preferably 5000 ppm or more and 15000 ppm or less in the surface layer B.

[0102] At this time, the surface average roughness (Sa) of the surface of the film of 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 of silica particles and / or calcium carbonate particles is 5000 ppm or more and Sa is 1 nm or more, air can be uniformly released when the film is wound up in a roll shape, and the winding shape is good and the flatness is good, making it suitable for manufacturing an ultra-thin layer ceramic green sheet. Also, when the total of silica particles and / or calcium carbonate particles is 15000 ppm or less and Sa is 40 nm or less, aggregation of the lubricant hardly occurs and no large protrusions are formed, so the quality is stable during the manufacture of the ultra-thin layer ceramic green sheet, which is preferable.

[0103] As the particles contained in the above B layer, in addition to silica and / or calcium carbonate, inert inorganic particles and / or heat-resistant organic particles can also be used. However, from the viewpoints of transparency and cost, it is more preferable to use silica particles and / or calcium carbonate particles. In addition, examples of other inorganic particles that can be used include alumina-silica composite oxide particles and hydroxyapatite particles. Examples of heat-resistant organic particles include crosslinked polyacrylic particles, crosslinked polystyrene particles, and benzoguanamine particles. When using silica particles, porous colloidal silica is preferable. When using calcium carbonate particles, lightweight calcium carbonate surface-treated with a polyacrylic acid-based polymer compound is preferable from the viewpoint of preventing the lubricant from falling off.

[0104] The average particle diameter of the inorganic particles added to the above 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. If the average particle diameter of the inorganic particles is 0.1 μm or more, the slipperiness of the release film is good, which is preferable. In addition, if the average particle diameter is 2.0 μm or less, there is no fear of adversely affecting the smoothness of the surface of the release layer, so there is no possibility of pinholes occurring in the ceramic green sheet, which is preferable. The method for measuring the average particle diameter of the particles can be carried out by observing the particles in the cross-section of the processed film with a scanning electron microscope, observing 100 particles, and taking the average value as the average particle diameter. As long as it satisfies the object of the present invention, the shape of the particles is not particularly limited, and spherical particles and non-spherical irregularly shaped particles can be used. The particle diameter of the irregularly shaped particles can be calculated as the equivalent circle diameter. The equivalent circle diameter is a value obtained by dividing the area of the observed particle by pi (π), calculating the square root, and doubling it.

[0105] In the surface layer A, which is the layer on the side where the above release layer is provided, from the viewpoint of reducing pinholes, it is preferable not to use recycled raw materials or the like in order to prevent the mixing of inorganic particles such as lubricants.

[0106] The thickness ratio of the surface layer A, which is the layer on the side where the release layer is provided, is preferably 20% or more and 50% or less of the total layer thickness of the base film. If it is 20% or more, it is difficult to be affected by the particles contained in the surface layer B or the like from inside the film, and it is easy and preferable for the surface average roughness Sa of the region to satisfy the above range. When it is 50% or less of the total layer thickness of the base film, the use ratio of the recycled raw material in the surface layer B can be increased, which is preferable because the environmental load is small.

[0107] Also, from the viewpoint of economy, 50% by mass or more and 90% by mass or less of recycled raw materials of film scraps or PET bottles can be used for the layers other than the surface layer A (the surface layer B or the aforementioned intermediate layer C). Even in this case, it is preferable that the type and amount of the lubricant, the particle size, and the surface average roughness (Sa) of the region contained in the B layer satisfy the above range.

[0108] Further, in order to improve the adhesion of the release layer to be applied later or to prevent charging, a coat layer D may be provided on the surface of the surface layer A and / or the surface layer B on the film before stretching or after uniaxial stretching in the film forming process, and corona treatment or the like can also be performed.

[0109] When the surface layer B does not contain particles, it is also preferable to provide lubricity with a coat layer D containing particles on the surface layer B. The means for providing this coat layer D is not particularly limited, but it is preferably provided by a so-called in-line coating method that is coated during the film formation of the polyester film. Further, when providing a coat layer D having lubricity on the surface of the polyester film on the side where the release layer is not laminated, the polyester film does not necessarily need to include the surface layers A and B, and may be composed of a single-layer polyester film that does not substantially contain inorganic particles.

[0110] The surface average roughness (Sa) of the surface of the region of the surface layer B is preferably 40 nm or less, more preferably 35 nm or less, and even more preferably 30 nm or less. Further, when imparting slipperiness to the surface on the side where the release layer of the surface layer B or the single-layer polyester film is not laminated with the coat layer D, the Sa of that surface is measured as the surface on which the coat layer D is laminated, and it is preferably in the same range as the surface average roughness (Sa) of the region of the surface layer B described above.

[0111] In the coat layer D on the surface on the side where the release layer is not laminated on the polyester film described above, it is preferably contained at least a binder resin and particles.

[0112] (Binder resin of coat layer D) The binder resin constituting the slip coating layer is not particularly limited, but specific examples of the polymer include polyester resin, acrylic resin, urethane resin, polyvinyl-based resins (such as polyvinyl alcohol), polyalkylene glycol, polyalkyleneimine, methyl cellulose, hydroxycellulose, starches, and the like. Among these, from the viewpoints of particle retention and adhesion, it is preferable to use polyester resin, acrylic resin, or urethane resin. Further, considering the compatibility with the polyester film, polyester resin is particularly preferable. In order to achieve solubility and dispersibility in the solvent, and further adhesion to the base film and other layers, the polyester of the binder is preferably a copolymerized polyester. Note that the polyester resin may be modified with polyurethane. Another preferable binder resin constituting the slip coating layer on the polyester base film is urethane resin. Examples of the urethane resin include polycarbonate polyurethane resin. Further, the polyester resin and the polyurethane resin may be used in combination, or the above other binder resins may be used in combination.

[0113] (Crosslinking agent of coat layer D) In order to form a crosslinked structure in the low-friction coating layer, the low-friction coating layer may be formed containing a crosslinking agent. By incorporating a crosslinking agent, it becomes possible to further improve the adhesion under high temperature and high humidity conditions. Specific crosslinking agents include urea-based, epoxy-based, melamine-based, isocyanate-based, oxazoline-based, carbodiimide-based, aziridine, and the like. Further, in order to accelerate the crosslinking reaction, a catalyst or the like can be appropriately used as needed.

[0114] (Particles in Coating Layer D) The low-friction coating layer preferably contains lubricant particles in order to impart slipperiness to the surface. The particles may be inorganic particles or organic particles and are not particularly limited. However, (1) inorganic particles such as silica, kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, zirconium oxide, titanium dioxide, satin white, aluminum silicate, diatomaceous earth, calcium silicate, aluminum hydroxide, hydrated halloysite, calcium carbonate, magnesium carbonate, calcium phosphate, magnesium hydroxide, barium sulfate, etc., (2) organic particles such as acrylic or methacrylic, vinyl chloride, vinyl acetate, nylon, styrene / acrylic, styrene / butadiene, polystyrene / acrylic, polystyrene / isoprene, polystyrene / isoprene, methyl methacrylate / butyl methacrylate, melamine, polycarbonate, urea, epoxy, urethane, phenol, diallyl phthalate, polyester, etc. are mentioned. However, silica is particularly preferably used in order to impart appropriate slipperiness to the coating layer.

[0115] The average particle size of the particles is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more. When the average particle size of the particles is 10 nm or more, it is difficult to aggregate and slipperiness can be ensured, which is preferable.

[0116] The average particle size is preferably 1000 nm or less, more preferably 800 nm or less, and even more preferably 600 nm or less. When the average particle size is 1000 nm or less, transparency is maintained and it is preferable that the particles do not fall off.

[0117] Also, for example, mixing small particles with an average particle size of about 10 nm or more and 270 nm or less and large particles with an average particle size of about 300 nm or more and 1000 nm or less is also preferable for achieving both slidability and smoothness while keeping the surface average roughness (Sa) and maximum protrusion height (RP) of the region described later small by reducing the average length (RSm) of the roughness curve elements. Particularly preferably, it is to use small particles of 30 nm or more and 250 nm or less and large particles with an average particle size of 350 nm or more and 600 nm or less in combination. When mixing small particles and large particles, it is preferable that the mass content ratio of the small particles is larger than the mass content ratio of the large particles with respect to the total solid content of the coating layer.

[0118] <2.3. Formation of release layer> In the present invention, the method for forming the release layer is not particularly limited, and a method is used in which a coating solution in which a release compound is dissolved or dispersed is developed by coating or the like on one surface of a polyester film of a substrate, and after removing a solvent or the like by drying, it is cured. A method of curing by heat simultaneously with solvent removal may be used.

[0119] When the release layer of the present invention is applied onto a substrate film by solution coating, the drying temperature for solvent drying is preferably 50°C or higher and 120°C or lower, and more preferably 60°C or higher and 100°C or lower. The drying time is preferably 30 seconds or less, and more preferably 20 seconds or less. Further, after solvent drying, it is preferable to irradiate active energy rays to advance the curing reaction. As the active energy rays used at this time, ultraviolet rays, electron beams, X-rays, etc. can be used, but ultraviolet rays are easy to use and are preferable. The amount of ultraviolet rays irradiated is preferably 30 mJ / cm 2 or more and 300 mJ / cm 2 or less, and more preferably 30 mJ / cm 2200 mJ / cm or more 2 and 30 mJ / cm or less. By setting it to 30 mJ / cm or more, the curing of the composition can proceed sufficiently. On the other hand, by setting it to 300 mJ / cm or less, the processing speed can be improved, so that the release film can be manufactured economically. 2 and 300 mJ / cm or less, the processing speed can be improved, so that the release film can be manufactured economically. 2

[0120] The surface tension of the coating liquid when applying the release layer is not particularly limited, but is preferably 30 mN / m or less. By setting the surface tension as described above, the coatability after coating can be improved, and the unevenness on the surface of the coating film after drying can be reduced.

[0121] As the coating method of the above coating liquid, any known coating method can be applied. For example, roll coating methods such as gravure coating method and reverse coating method, bar coating methods such as wire bar, die coating method, spray coating method, air knife coating method, and other conventionally known methods can be used.

[0122] <2.4. Physical properties of the release film> The water adhesion energy on the surface of the release layer, that is, the adhesion energy obtained by measuring the sliding angle using water, is preferably 7.0 mJ / m or more, more preferably 7.5 mJ / m or more. The water adhesion energy on the surface of the release layer may be 8.0 mJ / m or more, 8.1 mJ / m or more, or 8.2 mJ / m or more. The water adhesion energy on the surface of the release layer is measured by the method described in the examples below. 2 and 7.5 mJ / m or more is more preferable. 2 The water adhesion energy on the surface of the release layer may be 8.0 mJ / m or more, 8.1 mJ / m or more, or 8.2 mJ / m or more. 2 even if it is 8.0 mJ / m or more, 2 even if it is 8.1 mJ / m or more, 2 even if it is 8.2 mJ / m or more. The water adhesion energy on the surface of the release layer is measured by the method described in the examples below.

[0123] The change magnification of the rub-off after the wet heat treatment (that is, the peel strength of the rubbed part / the peel strength of the unrubbed part), as an index of adhesion, is preferably less than 5 times, more preferably less than 4 times, and even more preferably less than 3 times. The change magnification of the rub-off after the wet heat treatment is measured by the method described in the examples below.

[0124] ​After laminating the release film with the adhesive tape, the peel strength measured by the T-peel method at 23°C and 0.3 m / min is preferably, for example, 100 mN / 50 mm or less, and more preferably 95 mN / 50 mm or less. This peel strength is measured by the method described in the examples below.

[0125] These physical properties (specifically, water adhesion energy, change magnification of lov-off after wet heat treatment, peel strength) can be appropriately set according to the use of the release film. Of course, these physical property values may deviate from the above-mentioned preferred numerical ranges.

[0126] <2.5. Applications of the Release Film> The application of the release film of this embodiment is not particularly limited. The release film can be used not only for manufacturing ceramic green sheets, but also, for example, for manufacturing adhesive sheets, cover films, polymer films, optical lenses, multilayer printed wiring boards, etc. In the application for manufacturing ceramic green sheets, for example, the release film of this embodiment can be used to manufacture ceramic green sheets for multilayer ceramic capacitors. That is, the release film of this embodiment can be used to manufacture multilayer ceramic capacitors. In the application for manufacturing multilayer printed wiring boards, for example, the release film of this embodiment can be used as a support film for supporting the insulating layer when manufacturing multilayer printed wiring boards by the build-up method. The release film of this embodiment can be particularly preferably used for manufacturing ceramic green sheets.

[0127] A ceramic green sheet can be manufactured by applying a ceramic slurry for forming a ceramic green sheet to the release layer of the release film of this embodiment and then drying it.

[0128] The ceramic green sheet can contain inorganic compounds. Examples of inorganic compounds include metal particles, metal oxides, minerals, etc. For example, calcium carbonate, silica particles, aluminum particles, barium titanate particles can be mentioned.

[0129] The ceramic green sheet can contain a resin component. The resin component can be appropriately selected according to the application. Examples of the resin component include polyvinyl butyral resins.

[0130] The thickness of the ceramic green sheet may be, for example, 0.2 μm or more and 1.0 μm or less.

[0131] By the way, generally, a multilayer ceramic capacitor includes a rectangular parallelepiped ceramic element. Inside the ceramic element, a first internal electrode and a second internal electrode are alternately provided along the thickness direction. The first internal electrode is exposed on a first end face of the ceramic element. A first external electrode is provided on the first end face. The first internal electrode is electrically connected to the first external electrode at the first end face. The second internal electrode is exposed on a second end face of the ceramic element. A second external electrode is provided on the second end face. The second internal electrode is electrically connected to the second external electrode at the second end face.

[0132] The multilayer ceramic capacitor can be manufactured, for example, by the following procedure. First, using the release film of the present embodiment as a carrier film, a ceramic slurry for forming the ceramic element is applied and dried. An ultra-thin product with a thickness of 0.2 μm or more and 1.0 μm or less has been required for the ceramic green sheet. A conductive layer for forming the first or second internal electrode is printed on the applied and dried ceramic green sheet. The ceramic green sheet, the ceramic green sheet printed with the conductive layer for forming the first internal electrode, and the ceramic green sheet printed with the conductive layer for forming the second internal electrode are appropriately laminated and pressed to obtain a mother laminate. The mother laminate is divided into a plurality to produce a raw ceramic element. The raw ceramic element is fired to obtain a ceramic element. Thereafter, the multilayer ceramic capacitor can be completed by forming the first and second external electrodes.

Example

[0133] Examples and comparative examples are given below to more specifically explain the present invention. In the present invention, physical properties and the like were measured or evaluated by the following methods. Hereinafter, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0134] <Measurement method of each physical property> (Weight-average molecular weight) A sample solution with the sample concentration adjusted to 0.2% was filtered through a 0.2 μm membrane filter, and gel permeation chromatography (GPC) analysis was performed under the following conditions to obtain the weight-average molecular weight. The molecular weight was calculated in terms of standard polystyrene. Apparatus: TOSOH HLC-8320GPC Column: TSKgel SuperHM-H×2 + TSKgel SuperH2000 (TOSOH) Solvent: 100% chloroform Flow rate: 0.6 ml / min Concentration: 0.2% Injection volume: 20 μl Temperature: 40 °C Detector: RI

[0135] (Release layer thickness) The release film was embedded in resin and ultrathin sectioned using an ultramicrotome. Then, cross-sectional observation was performed using a JEOL JEM2100 transmission electron microscope, and the film thickness of the release layer was measured from the observed TEM image. When the thickness is too thin to be accurately evaluated by cross-sectional observation, the Si intensity was measured using a fluorescent X-ray device (ZSX PRIMUSII manufactured by Rigaku), and the coating amount was calculated by the calibration curve method.

[0136] (Tape peeling force of the release layer) The adhesive layer surface of a 50 mm wide acrylic pressure-sensitive adhesive tape No. 31B (manufactured by Nitto Denko Corporation) was bonded to the release layer surface of a release film using a hand roller to produce a laminate. After storing this laminate at 23°C for 24 hours, the release film was pulled downward and the pressure-sensitive adhesive tape was pulled upward using a tensile tester, that is, pulled at a speed of 0.3 m / min by the T-peel method, and the peel strength (mN / 50 mm) measured in a 23°C atmosphere was recorded.

[0137] (Adhesion after wet heat treatment of the release layer (love-off after wet heat treatment)) The release film was stored in an environment of 60°C and 90% RH for 3 days. Next, after attaching pearl paper (Toyobo Estar Film P4255-35 manufactured by Toyobo Co., Ltd.) to the load head part (i.e., the friction element) of a Gakushin type friction tester (manufactured by Yamaguchi Kagaku Sangyo Co., Ltd.) via gauze (Hakujuji Gauze manufactured by Hakujuji Co., Ltd.), the load head part with the pearl paper was reciprocated 10 times at a load of 200 gf / 25 mm 2 (5 mm × 5 mm) (i.e., 0.0785 MPa) to rub the release layer of the release film. An adhesive tape (Nitto-31B manufactured by Nitto Denko Corporation) was attached to the rubbed part and the unrubbed part of the release layer, and after storing for 20 hours, T-peel was performed at a speed of 300 mm / min using an autograph to measure the peel strength. The change magnification (i.e., peel strength of the rubbed part / peel strength of the unrubbed part) was obtained from the peel strength of the rubbed part and the peel strength of the unrubbed part, and judged as follows. Along with the judgment results, this change magnification is shown in Table 1. The smaller this change magnification, the better the adhesion between the release layer and the polyester film (this can also be referred to as adhesion durability). 〇: The peel strength of the rubbed part is less than 3 times that of the unrubbed part △: The peel strength of the rubbed part is 3 times or more and less than 10 times that of the unrubbed part ×: The peel strength of the rubbed part is 10 times or more that of the unrubbed part

[0138] (Water adhesion energy of the release layer) The water adhesion energy of the release film was measured using a fully automatic contact angle meter DM-701 manufactured by Kyowa Interface Science Co., Ltd. Specifically, in an environment with a temperature of 23 degrees and a humidity of 50%, the release film was stationary (i.e., fixed) on a flat glass substrate, and at an inclination of 0 degrees of the glass substrate (i.e., horizontal), a 7.0 μl droplet of water was dropped onto the surface of the release layer of the release film. Three seconds after the droplet stopped moving, the glass substrate was inclined at a speed of 1 degree / second, and when the endpoint of the droplet moved away from the stationary position, the adhesion energy (mJ / m 2 ) was determined using the following formula from the sliding angle, wetting radius, droplet mass, and gravitational acceleration of the droplet. E=(m×g×sinα) / (2×π×r) In this formula, E is the adhesion energy, m is the droplet mass, g is the gravitational acceleration, α is the sliding angle, and r is the wetting radius.

[0139] (Si element ratio of the outermost surface of the release layer) The Si element ratio of the outermost surface of the release layer of the release film was measured by ESCA (Electron Spectroscopy for Chemical Analysis). The K-Alpha + (manufactured by Thermo Fisher Scientific) was used. The details of the measurement conditions are shown below. Using this apparatus, a narrow scan was performed on the five elements of C, O, N, S, and Si on the surface of the release layer, and the Si element ratio (at%) was calculated from the following formula. That is, here, the Si element ratio is the ratio (at%) of Si among the five elements of C, O, N, S, and Si. Si element ratio (at%)={Si / (C+O+N+S+Si)}×100 In addition, during the analysis, background removal was performed by the Shirley method. The surface Si element ratio was taken as the average value of the measurement results at three or more locations. Measurement conditions Excitation X-ray: Monochromatized Al Ka line X-ray output: 12 kV, 6 mA Photoelectron escape angle: 90° Spot size: 400 mm f (approx.) Pass energy: 50 eV Step: 0.1 eV

[0140] <Example 1> An adhesion promoter S1 (allylcyclohexane resin AD-032 manufactured by Osaka Soda Co., Ltd., polymer having a weight average molecular weight of 24,000 and containing a structure represented by formula C1) was dissolved in toluene so that the solid content concentration became 30% to prepare an adhesion promoter solution A1. A coating solution M1 was prepared by adding the adhesion promoter solution A1 to a heat-curable silicone resin (DOWSIL LTC750A manufactured by Dow Corning Toray Co., Ltd., solid content concentration 30%) so that the solid content ratio became 20% (that is, the solid content ratio of the adhesion promoter S1 to the heat-curable silicone resin). (Coating solution M1) Methyl ethyl ketone 46.62 parts Toluene 46.62 parts Heat-curable silicone resin 5.56 parts (DOWSIL LTC750A manufactured by Dow Corning Toray Co., Ltd., solid content concentration 30%) Adhesion promoter solution A1 1.11 parts Catalyst 0.10 part (SRX212 manufactured by Dow Corning Toray Co., Ltd. (platinum complex of 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, solid content concentration 5%)) The coating solution M1 was applied to one side (specifically, the corona-treated side) of a polyester film (Toyobo Ester Film E5100 manufactured by Toyobo Co., Ltd., thickness 50 μm, one-sided corona-treated product) using reverse gravure so that the dried coating thickness became 50 nm. Then, the processing speed was adjusted so that it would enter the first drying oven after 0.5 seconds, and continuous heat drying and curing of the release layer were performed at a first drying oven temperature of 120°C and a second drying oven temperature of 160°C to obtain a release film.

[0141] <Example 2> The adhesion promoter S2 (a diallyl phthalate resin manufactured by Osaka Soda Co., Ltd. with a weight average molecular weight of 50,000 and a polymer containing the structure represented by formula C2) was dissolved in toluene to a solid content concentration of 30% to prepare an adhesion promoter solution A2. A coating solution M2 was prepared by adding the adhesion promoter solution A2 to a heat-curable silicone resin (DOWSIL LTC750A manufactured by Dow Corning Toray Co., Ltd. with a solid content concentration of 30%) at a solid content ratio of 20%. A release film was produced in the same manner as in Example 1, except that the coating solution M2 was used instead of the coating solution M1. (Coating solution M2) Methyl ethyl ketone 46.62 parts Toluene 46.62 parts Heat-curable silicone resin 5.56 parts (DOWSIL LTC750A manufactured by Dow Corning Toray Co., Ltd. with a solid content concentration of 30%) Adhesion promoter solution A2 1.11 parts Catalyst 0.10 part (SRX212 manufactured by Dow Corning Toray Co., Ltd. (platinum complex of 1,1,3,3-tetramethyl-1,3-divinyldisiloxane with a solid content concentration of 5%))

[0142] <Example 3> The adhesion promoter S3 (a diallyl phthalate resin manufactured by Osaka Soda Co., Ltd. with a weight average molecular weight of 20,000 and a polymer containing the structure represented by formula C3) was dissolved in toluene to a solid content concentration of 30% to prepare an adhesion promoter solution A3. A coating solution M3 was prepared by adding the adhesion promoter solution A3 to a heat-curable silicone resin (DOWSIL LTC750A manufactured by Dow Corning Toray Co., Ltd. with a solid content concentration of 30%) at a solid content ratio of 20%. A release film was produced in the same manner as in Example 1, except that the coating solution M3 was used instead of the coating solution M1. (Coating solution M3) Methyl ethyl ketone 46.62 parts Toluene 46.62 parts Heat-curable silicone resin 5.56 parts (DOWSIL LTC750A manufactured by Dow Corning Toray Co., Ltd. with a solid content concentration of 30%) Adhesion promoter liquid A3 1.11 parts Catalyst 0.10 part (SRX212 manufactured by Dow Corning Toray Co., Ltd. (platinum complex of 1,1,3,3 - tetramethyl - 1,3 - divinyldisiloxane, solid content concentration 5%))

[0143] [Example 4] Coating liquid M4 was prepared by adding adhesion promoter liquid A1 to a heat - curable silicone resin (DOWSIL LTC750A manufactured by Dow Corning Toray Co., Ltd., solid content concentration 30%) so that the solid content ratio was 10%. A release film was produced in the same manner as in Example 1 except that coating liquid M4 was used instead of coating liquid M1. (Coating liquid M4) Methyl ethyl ketone 46.89 parts Toluene 46.89 parts Heat - curable silicone resin 5.56 parts (DOWSIL LTC750A manufactured by Dow Corning Toray Co., Ltd., solid content concentration 30%) Adhesion promoter liquid A1 0.56 part Catalyst 0.10 part (SRX212 manufactured by Dow Corning Toray Co., Ltd. (platinum complex of 1,1,3,3 - tetramethyl - 1,3 - divinyldisiloxane, solid content concentration 5%))

[0144] [Comparative Example 1] A release film was produced in the same manner as in Example 1 except that coating liquid M5 with the following composition was used instead of coating liquid M1. (Coating liquid M5) Methyl ethyl ketone 47.17 parts Toluene 47.17 parts Heat - curable silicone resin 5.56 parts (DOWSIL LTC750A manufactured by Dow Corning Toray Co., Ltd., solid content concentration 30%) Catalyst 0.10 part (SRX212 manufactured by Dow Corning Toray Co., Ltd. (platinum complex of 1,1,3,3 - tetramethyl - 1,3 - divinyldisiloxane, solid content concentration 5%))

[0145] [Comparative Example 2] An adhesion promoter, specifically, a reaction product of vinyltriacetoxysilane and glycidoxypropyltrimethoxysilane (SD7200 with a solid content concentration of 90% manufactured by Dow Corning Toray Co., Ltd.) was added to a heat-curable silicone resin (DOWSIL LTC750A with a solid content concentration of 30% manufactured by Dow Corning Toray Co., Ltd.) at a solid content ratio of 10% to prepare a coating solution M6. A release film was prepared in the same manner as in Example 1, except that coating solution M6 was used instead of coating solution M1. (Coating solution M6) 47.08 parts of methyl ethyl ketone 47.08 parts of toluene 5.56 parts of heat-curable silicone resin (DOWSIL LTC750A with a solid content concentration of 30% manufactured by Dow Corning Toray Co., Ltd.) Reaction product of vinyltriacetoxysilane and glycidoxypropyltrimethoxysilane (SD7200 with a solid content concentration of 90% manufactured by Dow Corning Toray Co., Ltd.) 0.19 part 0.10 part of catalyst (SRX212 (platinum complex of 1,1,3,3-tetramethyl-1,3-divinyldisiloxane with a solid content concentration of 5%) manufactured by Dow Corning Toray Co., Ltd.)

[0146] <Comparative Example 3> As an adhesion promoter, diallyl phthalate (DAP) monomer (diallyl phthalate manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in toluene to a solid content concentration of 30% to prepare an adhesion promoter solution A4. A coating solution M7 was prepared by adding the adhesion promoter solution A4 to a heat-curable silicone resin (DOWSIL LTC750A with a solid content concentration of 30% manufactured by Dow Corning Toray Co., Ltd.) at a solid content ratio of 20%. A release film was prepared in the same manner as in Example 1, except that coating solution M7 was used instead of coating solution M1. (Coating solution M7) 46.62 parts of methyl ethyl ketone 46.62 parts of toluene 5.56 parts of heat-curable silicone resin (DOWSIL LTC750A manufactured by The Dow Chemical Company - Toray Co., Ltd., solid content concentration: 30%) Adhesion promoter liquid A4: 1.11 parts Catalyst: 0.10 parts (SRX212 manufactured by The Dow Chemical Company - Toray Co., Ltd. (platinum complex of 1,1,3,3 - tetramethyl - 1,3 - divinyldisiloxane), solid content concentration: 5%))

[0147] <Comparative Example 4> Adhesion promoter S4 (UVAD - 091 manufactured by Osaka Soda Co., Ltd., phthalate resin without vinyl group, weight - average molecular weight: 3000) was dissolved in toluene so that the solid content concentration became 30% to prepare adhesion promoter liquid A5. A coating liquid M8 was prepared by adding adhesion promoter liquid A5 to a heat - addition type silicone resin (DOWSIL LTC750A manufactured by The Dow Chemical Company - Toray Co., Ltd., solid content concentration: 30%) at a solid content ratio of 20%. A release film was produced in the same manner as in Example 1 except that coating liquid M8 was used instead of coating liquid M1. (Coating liquid M8) Methyl ethyl ketone: 46.62 parts Toluene: 46.62 parts Heat - addition type silicone resin: 5.56 parts (DOWSIL LTC750A manufactured by The Dow Chemical Company - Toray Co., Ltd., solid content concentration: 30%) Adhesion promoter liquid A5: 1.11 parts Catalyst: 0.10 parts (SRX212 manufactured by The Dow Chemical Company - Toray Co., Ltd. (platinum complex of 1,1,3,3 - tetramethyl - 1,3 - divinyldisiloxane), solid content concentration: 5%))

[0148]

Table 1

[0149] The release films using adhesion improver S1 (AD-032), adhesion improver S2 (DAP-K), and adhesion improver S3 (ISODAP) had a higher water adhesion energy compared to the release films that did not use any adhesion improver (see Examples 1 to 4 and Comparative Example 1). Therefore, the release films using these adhesion improvers (specifically, adhesion improver S1, S2, and S3) can reduce the degree of repellency that may occur when a liquid flowing material such as a ceramic slurry is applied to the release layer of the release film, or can suppress the occurrence of repellency.

[0150] The release films using adhesion improver S1 (AD-032), adhesion improver S2 (DAP-K), and adhesion improver S3 (ISODAP) had a change magnification (i.e., peeling force of the rubbed portion / peeling force of the unrubbed portion) close to 1.0 in the rub-off after the wet heat treatment compared to the release films that did not use any adhesion improver (see Examples 1 to 4 and Comparative Example 1). Since the increase in the change magnification in the rub-off after the wet heat treatment is caused by the detachment of the release layer (specifically, the release layer detaching from the polyester film), it can be evaluated that the release films using these adhesion improvers (specifically, adhesion improver S1, S2, and S3) are less likely to have the release layer detach from the polyester film compared to the release films that did not use any adhesion improver. That is, it can be evaluated that the adhesion between the release layer and the polyester film was improved by these adhesion improvers (specifically, adhesion improver S1, S2, and S3).

[0151] The tape peeling force of the release films using adhesion improver S1 (AD-032), adhesion improver S2 (DAP-K), and adhesion improver S3 (ISODAP) was not significantly different from the tape peeling force of the release films that did not use any adhesion improver (see Examples 1 to 4 and Comparative Example 1).

[0152] On the other hand, the water adhesion energy of the release film using SD7200 (a reaction product of vinyltriacetoxysilane and glycidoxypropyltrimethoxysilane) as an adhesion promoter was comparable to that of the release film without any adhesion promoter (see Comparative Examples 1 and 2). Regarding the change ratio of the pull-off after the wet heat treatment as an index of adhesion, although the change ratio approached 1.0 due to SD7200, that is, the adhesion was improved (see Comparative Examples 1 and 2), the improvement in adhesion by SD7200 was smaller than that by the adhesion promoters S1, S2, and S3 (see Comparative Examples 1 and 2 and Examples 1 to 4).

[0153] The water adhesion energy of the release film using the DAP monomer as an adhesion promoter was higher than that of the release film without any adhesion promoter (see Comparative Examples 1 and 3). However, the improvement in water adhesion energy by the DAP monomer was smaller than that by the adhesion promoters S1, S2, and S3 (see Comparative Examples 1 and 3 and Examples 1 to 4). Regarding the change ratio of the pull-off after the wet heat treatment as an index of adhesion, although the change ratio decreased due to the DAP monomer, that is, the adhesion was improved (see Comparative Examples 1 and 3), the improvement in adhesion by the DAP monomer was smaller than that by the adhesion promoters S1, S2, and S3 (see Comparative Examples 1 and 3 and Examples 1 to 4). Regarding the peelability, the tape peel strength of the release film using the DAP monomer was considerably higher than that of the release film without any adhesion promoter (see Comparative Examples 1 and 3). Since the Si element ratio of the release film using the DAP monomer was considerably smaller than that of the release film without any adhesion promoter, it is considered that the DAP monomer migrated to the surface of the release layer, resulting in re-peeling in the release film using the DAP monomer (see Comparative Examples 1 and 3).

[0154] The magnification of change (specifically, the magnification of change in rub-off after wet heat treatment as an index of adhesion) of the release film using UVAD-091 (a phthalate resin without a vinyl group) as an adhesion-imparting agent was smaller than that of the release film without using any adhesion-imparting agent (see Comparative Examples 1 and 4). However, the improvement in adhesion by UVAD-091 was smaller compared to the improvement in adhesion by adhesion-imparting agents S1, S2, and S3 (see Comparative Examples 1 and 4 and Examples 1 to 4). Regarding peelability, the tape peel strength of the release film using UVAD-091 was considerably higher than that of the release film without using any adhesion-imparting agent (see Comparative Examples 1 and 4). In addition, regarding the water adhesion energy, the water adhesion energy of the release film using UVAD-091 was higher than that of the release film without using any adhesion-imparting agent (see Comparative Examples 1 and 4) and was comparable to the water adhesion energy of the release film using adhesion-imparting agents S1, S2, and S3 (see Comparative Example 4 and Examples 1 to 4).

Industrial Applicability

[0155] Since the present invention relates to a release film, the present invention has industrial applicability.

Claims

1. A polyester film and a release layer, wherein the release layer is a layer formed by curing a silicone composition containing an addition-curable silicone, the silicone composition contains a resin that contains neither a silicon atom nor a nitrogen atom in the molecule and contains a plurality of alkenyl groups and a plurality of rings in the molecule, each of the rings is independently at least one selected from the group consisting of a monovalent aromatic ring, a divalent aromatic ring, a monovalent aliphatic ring, and a divalent aliphatic ring, a release film.

2. The release film according to claim 1, wherein the alkenyl group is an allyl group.

3. The release film according to claim 1, wherein each of the rings is independently at least one selected from the group consisting of a phenylene group, a naphthylene group, a cyclopentylene group, and a cyclohexylene group.

4. The release film according to claim 1, wherein the resin contains a plurality of ester bonds in the molecule.

5. The release film according to claim 1, wherein the resin contains a plurality of structural units represented by the following formula in the molecule. 【Chemical 1】 (A plurality of X are each independently at least one selected from the group consisting of a phenylene group, a naphthylene group, a cyclopentylene group, and a cyclohexylene group.)

6. The release film according to claim 1, wherein the weight average molecular weight of the resin is 4000 or more.

7. The release film according to any one of claims 1 to 6, which is used for manufacturing a ceramic green sheet.

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