Release film for ceramic green sheet manufacturing

Abstract

The present invention addresses the problem of providing a release film for the production of a ceramic green sheet, the release film comprising a base material and a release agent layer, making release of the green sheet easy, undergoing little change over time in terms of ease in releasability, and enabling stable achievement of excellent ease in releasability even after the lapse of a long time since coating of the green sheet. The problem is solved by a release film for the production of a ceramic green sheet, the release film comprising a base material and a release agent layer that is provided on at least one side of the base material, wherein: the difference δBCA = BCA2 - BCA1 between the bromonaphthalene contact angle BCA1 of a surface on the reverse side of the release agent layer from the base material and the bromonaphthalene contact angle BCA2 of the surface on the reverse side of the release agent layer from the base material after having a ceramic slurry, which has the composition described below, applied thereto and dried, and subsequently removed after being stored for one week in a constant-temperature and constant-humidity environment at 23 ± 2°C and 50 ± 5% RH, is within the range of -1.5° to 1.0°. The ceramic slurry contains (a) 45% by mass of barium titanate particles, (b) 3.6% by mass of a polyvinyl butyral, (c) 0.9% by mass of dibutyl phthalate, (d) 25% by mass of toluene and (e) 25% by mass of ethanol.

Description

[Technical Field]

[0001] The present invention relates to a release film for producing ceramic green sheets, and more specifically to a release film for producing ceramic green sheets that allows easy peeling of the green sheets, undergoes little change in peelability over time, and can stably achieve excellent peelability even long periods after the green sheet is applied, and is particularly suitable for use in the production of various ceramic products such as multilayer ceramic capacitors and multilayer ceramic substrates. [Background technology]

[0002] Release films for producing ceramic green sheets have been used in the production of sheet-like ceramic members. For example, to produce multilayer ceramic products such as multilayer ceramic capacitors and multilayer ceramic substrates, ceramic green sheets are formed on a release film for producing ceramic green sheets, and then multiple ceramic green sheets are stacked and fired. In recent years, with the miniaturization and improved performance of electronic devices, multilayer ceramic capacitors and multilayer ceramic substrates have become smaller and more multilayered. To achieve this, ceramic green sheets must be thinner. To prevent defects such as pinholes and uneven thickness in thin ceramic green sheets and to effectively prevent breakage when thin ceramic green sheets are peeled from the release film, a release film for producing ceramic green sheets has been proposed, which includes a substrate and a release agent layer of specific components, in which the arithmetic mean roughness (Ra) and maximum projection height (Rp) of the release agent layer on the side opposite the substrate are each equal to or less than a predetermined value, and the arithmetic mean roughness (Ra) and maximum projection height (Rp) of the substrate on the side opposite the release agent layer are each within a predetermined numerical range (see, for example, Patent Document 1).

[0003] In the production of various ceramic products such as multilayer ceramic capacitors and multilayer ceramic substrates, it is required that the ceramic green sheet formed on the release film for producing the ceramic green sheet be easily peeled off from the viewpoints of the quality and productivity of the ceramic products. However, when using a release film for producing ceramic green sheets using conventional technology, even if the ceramic green sheet is easy to peel immediately after coating with ceramic slurry to form it, the peelability may decrease if the sheet is stored for, for example, about one week after coating, and the sheet may become difficult to peel due to storage, or the ceramic green sheet may break when peeled after storage. Therefore, improvements in this area were needed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2013 / 145865 A1 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above technical background, the present invention aims to provide a release film for producing ceramic green sheets, which has a substrate and a release agent layer, and which allows easy peeling of the green sheet, exhibits little change in peelability over time, and can stably achieve excellent peelability even long periods of time after the green sheet is coated. [Means for solving the problem]

[0006] As a result of extensive research, the inventors have found that in a release film for producing a ceramic green sheet having a substrate and a release agent layer provided on at least one side of the substrate, by controlling the amount of change in bromonaphthalene contact angle on the surface of the release agent layer before and after coating, drying, storage and peeling of a ceramic slurry of a predetermined composition within a predetermined numerical range, it is possible to stabilize the ease of releasability over time at a high level that exceeds the limits of conventional technology, and have completed the present invention. That is, the present invention provides: [1] A release film for producing a ceramic green sheet, comprising a substrate and a release agent layer provided on at least one side of the substrate, a bromonaphthalene contact angle BCA1 on the surface of the release agent layer opposite to the substrate; and The release film for producing a ceramic green sheet relates to the above release film, in which a ceramic slurry having the following composition is applied to the surface of the release agent layer opposite the substrate and dried, and the release agent is stored in a constant temperature and humidity environment of 23±2°C x 50±5% RH for one week, and then peeled off, and the difference from the bromonaphthalene contact angle BCA2, δBCA = BCA2 - BCA1, is within the range of -1.5° to 1.0°. a) 45% by weight of barium titanate particles; b) 3.6% by weight of polyvinyl butyral; c) 0.9% by mass of dibutyl phthalate, d) 25% by weight of toluene, and e) Ceramic slurry containing 25% by mass of ethanol.

[0007] Below, [2] to [8] are each a preferred aspect or embodiment of the present invention. [2] The release film for producing a ceramic green sheet according to [1], wherein the coating amount of the ceramic slurry is 50 μm before drying, the drying conditions are 70°C and 2 minutes, and the peeling is performed at an angle of 180°. [3] a water contact angle WCA1 of the surface of the release agent layer opposite to the substrate; The release film for producing a ceramic green sheet according to [1] or [2], wherein the ceramic slurry is applied to the surface of the release agent layer opposite the substrate, the ceramic slurry is dried, and the release agent layer is stored in a constant temperature and humidity environment of 23±2°C x 50±5% RH for one week, and then peeled off. The difference between the water contact angle WCA2 and the release agent layer, δWCA=WCA2-WCA1, is within the range of -3.5° to 1.0°. [4] The release film for producing a ceramic green sheet according to any one of [1] to [3], characterized in that the release agent layer contains a cured product of a curable composition, the curable composition contains at least one reactive compound (a) having at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, and the total amount of the reactive compound (a) accounts for 50% or more of the release agent layer in terms of mass ratio. [5] The release film for producing a ceramic green sheet according to [4], wherein the curable composition contains, as the reactive compound (a), at least one reactive silicone (a1) having at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, and a siloxane skeleton, and at least one reactive compound (a2) having the same reactive functional group as the reactive silicone (a1) and having a reactive functional group equivalent of 2000 g / mol or less. [6] The release film for producing a ceramic green sheet according to [5], wherein the curable composition further contains a film-forming compound (a3) ​​having two or more (meth)acryloyl groups in one molecule. [7] The release film for producing a ceramic green sheet according to any one of [1] to [6], wherein the arithmetic mean roughness (Ra) of the surface of the base material on the release agent layer side is 1 to 70 nm. [8] The release film for producing a ceramic green sheet according to any one of [1] to [7], which is used in producing a multilayer ceramic capacitor or a multilayer ceramic substrate. [Effects of the Invention]

[0008] The release film for producing ceramic green sheets of the present invention allows easy release of the ceramic green sheets formed thereon, exhibits little change in releasability over time, and maintains excellent releasability even long periods after application of the green sheets. This achieves technical effects of great practical value at a high level that surpasses the limitations of conventional technology, and can be suitably used in the production of various ceramic products. For example, the release film significantly improves the productivity of various ceramic products such as multilayer ceramic capacitors and multilayer ceramic substrates, and is particularly suitable for use in the production of these products. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing one embodiment of a release film for producing a ceramic green sheet. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention provides a release film for producing a ceramic green sheet, comprising a substrate and a release agent layer provided on at least one side of the substrate, a bromonaphthalene contact angle BCA1 on the surface of the release agent layer opposite to the substrate; and The release film for producing a ceramic green sheet is prepared by coating and drying a ceramic slurry having the following composition on the surface of the release agent layer opposite the substrate, storing the slurry in a constant temperature and humidity environment of 23±2°C x 50±5% RH for one week, and then peeling the release agent off. The difference between the contact angle of bromonaphthalene BCA2, δBCA=BCA2-BCA1, is within the range of -1.5° to 1.0°. Here, the ceramic slurry is a) 45% by weight of barium titanate particles; b) 3.6% by weight of polyvinyl butyral; c) 0.9% by mass of dibutyl phthalate, d) 25% by weight of toluene, and e) A ceramic slurry containing 25% by mass of ethanol. That is, the release film for producing a ceramic green sheet of the present invention has a substrate and a release agent layer. The release film for producing a ceramic green sheet of the present invention only needs to have a substrate and a release agent layer, and may or may not have other layers. Therefore, as shown in Figure 1, the release film for producing a ceramic green sheet of the present invention may consist only of a substrate (13) and a release agent layer (12), or may have other layers such as an antistatic layer in addition to the substrate and release agent layer. Each of the above layers will now be described.

[0011] Base material The substrate constituting the release film for producing ceramic green sheets of the present invention is not particularly limited, and any substrate known in the art can be appropriately selected and used. Examples of such substrates include films made of polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene and polymethylpentene, polycarbonate, and plastics such as ethylene-vinyl acetate copolymers. These may be single-layer or multi-layers of two or more layers of the same or different materials. Among these, polyester films are preferred, with polyethylene terephthalate films being particularly preferred, and biaxially oriented polyethylene terephthalate films being even more preferred. Polyethylene terephthalate films are less likely to generate dust during processing and use, effectively preventing, for example, ceramic slurry coating defects due to dust.

[0012] Furthermore, in order to improve adhesion to the release agent layer provided on at least one surface of the substrate, the substrate may be subjected to a surface treatment such as an oxidation method or a primer treatment. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone treatment, and ultraviolet irradiation treatment. These surface treatment methods are appropriately selected depending on the type of substrate film, but corona discharge treatment is generally preferred in terms of effectiveness and operability. There are no particular restrictions on the thickness of the substrate, and the thickness may be set appropriately based on factors such as mechanical strength and ease of handling during production and use. It is usually 10 to 300 μm, preferably 12 to 200 μm, and particularly preferably 15 to 125 μm.

[0013] The arithmetic mean roughness (Ra) of the surface of the substrate on the release agent layer side is preferably 0.1 to 70 nm, and more preferably 1 to 60 nm. The arithmetic mean roughness (Ra) of the surface of the substrate on the release agent layer side is preferably 0.1 to 70 nm in terms of handling of the substrate, suppression of poor conduction, etc. Furthermore, substrates having a surface arithmetic mean roughness (Ra) of 1 to 70 nm are relatively easy and inexpensive to obtain, and are therefore preferred from the viewpoints of availability and production costs of the release film for producing the ceramic green sheet of the present invention.

[0014] The arithmetic mean roughness (Ra) of the surface of the substrate opposite to the release agent layer side is preferably from 5 to 70 nm, particularly preferably from 10 to 60 nm. When the arithmetic mean roughness (Ra) of the surface of the substrate opposite to the release agent layer side is equal to or greater than the above lower limit, blocking can be effectively suppressed during winding of the release film for producing a ceramic green sheet of the present invention, and when it is equal to or less than the above upper limit, it becomes easier to smooth the surface of the release agent layer.

[0015] Release agent layer There are no particular restrictions on the material of the release agent layer that constitutes the release film for producing ceramic green sheets of the present invention, and any material can be used as long as the following condition is met: the difference between the bromonaphthalene contact angle BCA1 on the surface of the release agent layer opposite the substrate and the bromonaphthalene contact angle BCA2 after a ceramic slurry of the specific composition described above is applied to the surface opposite the substrate, dried, stored in a constant temperature and humidity environment of 23±2°C x 50±5% RH for one week, and then peeled off, δBCA = BCA2 - BCA1, is within the range of -1.5° to 1.0°. From the viewpoint of ease of production of the release film for producing a ceramic green sheet and appropriate control of the bromonaphthalene contact angle, water contact angle, etc., it is preferable to form the release agent layer by coating a curable composition on a substrate and curing it, and it is particularly preferable to form the release agent layer by coating a photocurable and / or thermosetting curable composition and curing it. That is, the release agent layer in the present invention preferably contains a cured product of the curable composition.

[0016] curable composition The curable composition preferably used in the present invention for forming the release agent layer preferably contains at least one reactive compound (a) having at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group. By using a curable composition containing at least one reactive compound (a) having at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, the release agent layer of the release film for producing a ceramic green sheet of this embodiment can be formed easily and with good controllability of the surface free energy, etc.

[0017] The curable composition may contain only one reactive compound (a) having at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, or may contain two or more reactive compounds (a) having at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group. From the viewpoint of controlling various properties of the release agent layer, such as curability, releasability, and surface free energy, it is preferable to use two or more reactive compounds (a) in combination, and it is particularly preferable to use a combination of a reactive silicone (a1) and a crosslinkable compound (a2) described below, and it is further preferable to combine them with a film-forming compound (a3) ​​described below.

[0018] The curable composition may be composed solely of a reactive compound (a) having at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, or may contain other components such as a solvent, a radical initiator, a cationic initiator, a leveling agent, an antistatic agent, a dye, or a pigment. The total amount of reactive compound (a) having at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group used is preferably 50% by mass or more, particularly preferably 60 to 96% by mass, of the mass of the release agent layer.

[0019] Reactive Compound (a) The reactive compound (a) preferably used for forming the release agent layer in the present invention has at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group. By having at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, it is possible to impart photocurability and / or thermosetting properties to the curable composition.

[0020] The reactive compound (a) may have one or more reactive functional groups, but from the viewpoint of photocurability and / or thermosetting property, it preferably has two or more reactive functional groups, more preferably has 2 to 15 reactive functional groups, and particularly preferably has 2 to 10 reactive functional groups. When the reactive compound (a) has two or more reactive functional groups, it may have two or more of the same type of reactive functional groups, or it may have a combination of two or more different types of reactive functional groups in total. From the viewpoint of curability, etc., the reactive compound (a) preferably has a (meth)acryloyl group when active energy rays are used, and when heat curing is also used, a material containing a hydroxyl group or an epoxy group can be appropriately selected.

[0021] Preferred examples of the reactive compound (a) include a reactive silicone (a1) having at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, and a siloxane skeleton; a reactive compound (a2) having the same reactive functional group as the reactive silicone (a1) and having a reactive functional group equivalent of 2000 g / mol or less; and a film-forming compound (a3) ​​having two or more (meth)acryloyl groups in one molecule. In the curable composition, it is preferable to use a combination of the reactive silicone (a1) and the reactive compound (a2), and it is also preferable to use a combination of the film-forming compound (a3).

[0022] Reactive silicone (a1) The curable composition preferably contains, as the reactive compound (a), at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, and a reactive silicone (a1) having a siloxane skeleton. The use of the reactive silicone (a1) can impart desired releasability to the surface of the release agent layer, making it easier to release the ceramic green sheet, and also allows for appropriate control of the bromonaphthalene contact angle, water contact angle, etc. The reactive silicone (a1) is not limited as long as it has at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, and has a siloxane skeleton. By containing at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, the reactive functional group reacts with the siloxane skeleton to incorporate it into a crosslinked structure and fix it by irradiation with active energy rays or by a separate reaction step (for example, a heating step), which makes it possible to more effectively control the releasability, bromonaphthalene contact angle, water contact angle, etc. of the release agent layer. As the reactive functional group, an epoxy group is particularly preferred.

[0023] The reactive functional group may be introduced into one end of the siloxane skeleton, may be introduced into both ends, or may be introduced into a side chain. At least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group is preferably introduced into one molecule of the reactive silicone (a1). When two or more reactive functional groups are present, they may be two or more of the same type of reactive functional group, or a combination of two or more different reactive functional groups may be present in total. In addition to the reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, the compound may further have a vinyl group, a maleimide group, a carboxyl group, an isocyanate group, or the like.

[0024] There are no particular restrictions on the molecular weight of the reactive silicone (a1), but from the viewpoints of appropriate release properties and controllability of the bromonaphthalene contact angle, water contact angle, etc., it is preferably 5,000 to 100,000, and particularly preferably 10,000 to 70,000.

[0025] In the curable composition, the reactive silicone (a1) may be used alone or in combination of two or more. The content of the reactive silicone (a1) in the curable composition is not particularly limited, but is preferably 0.1 to 20 mass %, and particularly preferably 0.2 to 15 mass %, based on the total mass of the release agent layer.

[0026] Reactive compound (a2) (crosslinking compound (a2)) The curable composition preferably contains, as the reactive compound (a), a reactive compound (a2) having the same reactive functional group as the reactive silicone (a1) and having a reactive functional group equivalent of 2000 g / mol or less. It is particularly preferred to use the reactive compound (a2) in combination with the reactive silicone (a1). The reactive compound (a2) functions as a crosslinking agent for the reactive silicone (a1), etc., promoting the effects of the curable composition and allowing the reactive silicone (a1), etc., to be incorporated and fixed into the crosslinked structure. This prevents contamination of the ceramic green sheet, and the crosslinked structure promotes curing, resulting in improved stability over time. In light of its function as a crosslinking agent, the reactive compound (a2) is also referred to herein as the "crosslinkable compound (a2)."

[0027] The reactive functional group equivalent of the reactive compound (a2) is 2000 g / mol or less, preferably 1800 g / mol or less, particularly preferably 1700 g / mol or less. By having a reactive functional group equivalent weight of 2000 g / mol or less, the number of (meth)acryloyl groups, hydroxyl groups, and / or epoxy groups sufficient to achieve suitable crosslinking performance will be present. The reactive compound (a2) preferably has a total of one or more reactive functional groups ((meth)acryloyl groups, hydroxyl groups, and / or epoxy groups), preferably 2 to 15, and particularly preferably 2 to 6. When the number of reactive functional groups is within the above range, more appropriate crosslinking performance can be achieved.

[0028] There are no particular restrictions on the molecular weight of the crosslinkable compound (a2), but from the viewpoint of crosslinking performance and the like, it is preferably from 150 to 4,000, and particularly preferably from 150 to 3,000. The crosslinkable compound (a2) may have a siloxane skeleton. In this case, by introducing a sufficient amount of siloxane skeleton into the release agent layer together with the siloxane skeleton of the reactive silicone (a1), even more preferable release performance can be achieved.

[0029] In the curable composition, the crosslinkable compound (a2) may be used alone or in combination of two or more. The content of the crosslinkable compound (a2) in the curable composition is not particularly limited, but is preferably 0.08 to 99 mass%, more preferably 0.4 to 50 mass%, even more preferably 0.7 to 30 mass%, and particularly preferably 1.0 to 15 mass%, based on the total mass of the release agent layer. Furthermore, based on the amount of reactive silicone (a1) used, the content is preferably 81 to 9900 mass parts, particularly preferably 85 to 1000 mass parts, based on 100 mass parts of reactive silicone (a1).

[0030] It is also preferable to use a compound having excellent film-forming properties as the reactive compound (a) in the curable composition. The compound having excellent film-forming properties may be either a compound having a (meth)acryloyl group or a compound having a hydroxyl group, but it is preferable to use a film-forming compound (a3) ​​having two or more (meth)acryloyl groups in one molecule. Film-forming compound (a3) The curable composition preferably contains, as the reactive compound (a), a film-forming compound (a3) ​​having two or more (meth)acryloyl groups in one molecule. By including the film-forming compound (a3) ​​having two or more (meth)acryloyl groups in one molecule, the curable composition can be cured by irradiation with active energy rays. The film-forming compound (a3) ​​may be any one of a monomer, an oligomer, or a polymer, or a mixture thereof. The film-forming compound (a3) ​​is preferably a (meth)acrylic acid ester. Here, the term "(meth)acrylic acid ester" refers to both an acrylic acid ester and a methacrylic acid ester. The same applies to other similar terms.

[0031] The (meth)acrylic acid ester is preferably at least one selected from polyfunctional (meth)acrylate monomers and (meth)acrylate oligomers, particularly preferably at least one selected from difunctional or higher functional (meth)acrylate monomers and (meth)acrylate oligomers, and more preferably a trifunctional or higher functional (meth)acrylate monomer. By being difunctional or higher, and more preferably trifunctional or higher, the curability of the curable composition is excellent, and the releasability of the surface of the obtained release agent layer is also excellent.

[0032] There are no particular restrictions on the (meth)acryloyl group equivalent of the film-forming compound (a3), and film-forming compounds (a3) ​​having a wide range of (meth)acryloyl group equivalents can be used as long as they satisfy the δBCA condition of the present invention. From the viewpoint of achieving even better peeling properties and controllability of the bromonaphthalene contact angle, water contact angle, etc., the amount of the film-forming compound (a3) ​​is particularly preferably 300 g / mol or less, and particularly preferably 260 g / mol or less.

[0033] Examples of polyfunctional (meth)acrylate monomers include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphate di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, and isocyanurate di(meth)acrylate. acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris((meth)acryloxyethyl)isocyanurate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate. These may be used alone or in combination of two or more.

[0034] Examples of polyfunctional (meth)acrylate oligomers include polyester acrylate oligomers, epoxy acrylate oligomers, urethane acrylate oligomers, polyether acrylate oligomers, polybutadiene acrylate oligomers, and silicone acrylate oligomers.

[0035] The polyester acrylate oligomer can be obtained, for example, by esterifying the hydroxyl groups of a polyester oligomer having hydroxyl groups at both ends, obtained by condensation of a polycarboxylic acid and a polyhydric alcohol, with (meth)acrylic acid, or by esterifying the terminal hydroxyl groups of an oligomer obtained by adding an alkylene oxide to a polycarboxylic acid, with (meth)acrylic acid.

[0036] Epoxy acrylate oligomers can be obtained, for example, by esterifying the oxirane ring of a relatively low molecular weight bisphenol epoxy resin or novolac epoxy resin with (meth)acrylic acid. Alternatively, carboxyl-modified epoxy acrylate oligomers can be used, in which epoxy acrylate oligomers are partially modified with dibasic carboxylic acid anhydrides.

[0037] The urethane acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by reacting a polyether polyol or polyester polyol with a polyisocyanate with (meth)acrylic acid.

[0038] The polyether acrylate oligomer can be obtained by esterifying the hydroxyl groups of a polyether polyol with (meth)acrylic acid.

[0039] In the curable composition, the film-forming compound (a3) ​​may be used alone or in combination of two or more. The content of the film-forming compound (a3) ​​in the curable composition is not particularly limited, but is preferably 50 to 90 mass %, particularly preferably 60 to 85 mass %, based on the total mass of the release agent layer.

[0040] The release agent layer can be formed by applying the raw material of the release agent layer, preferably the above-mentioned curable composition, to at least one surface of the substrate, followed by drying as necessary and curing by irradiation with active energy rays such as light. If the reactive functional group of the reactive compound (a) is one that reacts with heat, the reaction is induced by drying at this time, and preferably the reactive compound (a) having a siloxane skeleton can be incorporated into a crosslinked structure. There are no particular limitations on the coating method of the curable composition, and for example, gravure coating, bar coating, spray coating, spin coating, knife coating, roll coating, die coating, etc. can be used.

[0041] As the active energy ray, ultraviolet rays, electron beams, etc. are usually used. The irradiation dose of the active energy ray varies depending on the type of energy ray. For example, in the case of ultraviolet rays, the light dose is 10 to 1000 mJ / cm. 2 is preferred, particularly 20 to 500 mJ / cm 2 In the case of electron beams, the dose is preferably about 0.1 to 50 kGy.

[0042] In the release film for producing ceramic green sheets of the present invention, the difference between the bromonaphthalene contact angle BCA1 on the surface of the release agent layer opposite the substrate and the bromonaphthalene contact angle BCA2 after a ceramic slurry of a specific composition (a) containing 45% by weight of barium titanate particles, b) 3.6% by weight of polyvinyl butyral, c) 0.9% by weight of dibutyl phthalate, d) 25% by weight of toluene, and e) 25% by weight of ethanol is coated and dried on the surface of the release agent layer opposite the substrate, stored for one week in a constant temperature and humidity environment of 23±2°C x 50±5% RH, and then peeled off, i.e., δBCA=BCA2-BCA1, is within the range of -1.5° to 1.0°. The fact that the δBCA is within the range of -1.5° to 1.0°, coupled with other technical features of the present invention, means that the release film for producing a ceramic green sheet of the present invention allows easy release of the ceramic green sheet formed thereon, and exhibits little change in releasability over time, ensuring stable, excellent releasability even long periods of time after the green sheet is applied. This makes it possible to achieve technical effects of great practical value at a high level that exceeds the limits of conventional technology. The mechanism by which a δBCA within the range of -1.5° to 1.0° achieves excellent ceramic green sheet releasability and suppression of its deterioration over time is not entirely clear, but it is estimated that the hardness of the release agent layer affects the interaction at the ceramic green sheet interface, and as a result, there is a range of the contact angle change δBCA of bromonaphthalene that corresponds to an optimal surface state for suppressing migration of release agent components and transfer of green sheet components, thereby achieving easy releasability and suppressing its deterioration over time; specifically, the contact angle change δBCA of bromonaphthalene is estimated to be in the range of -1.5° to 1.0°.

[0043] The bromonaphthalene contact angles BCA1 and BCA2 of the surface of the release agent layer opposite the substrate of the release film for producing a ceramic green sheet can be measured by a method conventionally known in the art, for example, by an automatic contact angle meter, etc. More specifically, they can be measured by the method described in the examples of the present specification. The conditions for coating, drying, and peeling the ceramic slurry between measurements of bromonaphthalene contact angles BCA1 and BCA2 are typically as follows: the ceramic slurry coating thickness before drying is 50 μm, drying conditions are 70°C, 2 minutes, and the peel angle is 180°. The composition of the ceramic slurry is as described above. The change in the bromonaphthalene contact angle, ΔBCA, can be calculated from the BCA1 and BCA2 measured above according to the formula ΔBCA=BCA2−BCA1.

[0044] The change δBCA in the bromonaphthalene contact angle of the release agent layer on the surface of the release film for producing a ceramic green sheet opposite the substrate is preferably from -1.2° to 0.8°, more preferably from -1.0° to 0.6°, and particularly preferably from -0.8° to 0.5°. There are no particular restrictions on the initial bromonaphthalene contact angle BCA1 on the surface of the release agent layer opposite the substrate, but from the standpoint of facilitating the release of the green sheet and making it easier to keep the δBCA value within a specified range, it is preferably 55° to 85°, and particularly preferably 60° to 80°.

[0045] The initial bromonaphthalene contact angle BCA1 on the surface of the release agent layer opposite the substrate, the bromonaphthalene contact angle BCA2 after a ceramic slurry of a specific composition is applied and dried, stored for one week in a constant temperature and humidity environment of 23±2°C x 50±5% RH, and then peeled off, and the change in bromonaphthalene contact angle δBCA can be adjusted appropriately by adjusting the type and amount of material constituting the release agent layer, the amount of the release agent layer applied, and curing conditions such as the drying temperature and the amount of active energy ray irradiation. In particular, it can be appropriately adjusted by adjusting the (meth)acryloyl group equivalent and the amount used of a reactive compound (a) having at least one reactive functional group selected from the group consisting of a (meth)acryloyl group, a hydroxyl group, and an epoxy group, particularly a reactive compound (a2) having the same reactive functional group as the reactive silicone (a1) and having a reactive functional group equivalent of 2000 g / mol or less, or a film-forming compound (a3) ​​having two or more (meth)acryloyl groups in one molecule.

[0046] The release film for producing ceramic green sheets of the present invention is sufficient if the difference δBCA=BCA2-BCA1 between the bromonaphthalene contact angle BCA1 of the surface of the release agent layer opposite the substrate and the bromonaphthalene contact angle BCA2 obtained after coating and drying a ceramic slurry of a specific composition on the surface of the release agent layer opposite the substrate, storing it in a constant temperature and humidity environment of 23±2°C x 50±5%RH for one week, and then peeling it off, satisfies the above-mentioned condition, and no other restrictions are imposed. However, it is preferable that the difference δWCA=WCA2-WCA1 between the water contact angle WCA1 of the surface of the release agent layer opposite the substrate and the water contact angle WCA2 obtained after coating and drying a ceramic slurry of a specific composition on the surface of the release agent layer opposite the substrate, storing it in a constant temperature and humidity environment of 23±2°C x 50±5%RH for one week, and then peeling it off, is within the range of -3.5° to 1.0°. By having a δWCA within the range of -3.5° to 1.0°, in combination with other technical features of the present invention, the release film for producing ceramic green sheets of this embodiment makes it easy to peel off the ceramic green sheet formed thereon, and changes in releasability over time are minimal, allowing for stable, excellent releasability even long periods of time after the green sheet is applied, and it is possible to suppress charging when the green sheet is peeled off, thereby achieving technical effects of great practical value at an even higher level.

[0047] The mechanism by which a δWCA within the range of -3.5° to 1.0° can achieve better ease of releasability of a ceramic green sheet, suppression of changes over time, and suppression of charging when the green sheet is released is not entirely clear, but it is believed that the hardness of the release agent layer affects the interactions at the interface of the ceramic green sheet, and as a result, there is a range of the water contact angle change δWCA that corresponds to an optimal surface state for ease of releasability and suppression of changes over time, whereby migration of release agent components and transfer of green sheet components are suppressed, and the specific numerical value of the water contact angle change δWCA is estimated to be in the range of -3.5° to 1.0°.

[0048] The water contact angles WCA1 and WCA2 of the surface of the release agent layer opposite the substrate of the release film for producing a ceramic green sheet can be measured by a method conventionally known in the art, for example, by an automatic contact angle meter, etc. More specifically, they can be measured by the method described in the examples of the present specification. The conditions for coating, drying, and peeling the ceramic slurry between measurements of water contact angles WCA1 and WCA2 are typically as follows: the ceramic slurry is coated to a thickness of 50 μm before drying, dried at 70°C for 2 minutes, and the peel angle is 180°. The composition of the ceramic slurry is as described above. The change in water contact angle ΔWCA can be calculated from the WCA1 and WCA2 measured above according to the formula ΔWCA=WCA2-WCA1.

[0049] In the release film for producing a ceramic green sheet, the change in water contact angle ΔWCA of the surface of the release agent layer opposite the substrate is preferably −3.3° to 0.8°, particularly preferably −3.2° to 0.6°. There are no particular restrictions on the initial water contact angle WCA1 of the surface of the release agent layer opposite the substrate, but from the standpoint of making it easier to peel the green sheet and making it easier to keep the δWCA value within a specified range, it is preferably 85° to 115°, and particularly preferably 90° to 110°.

[0050] The initial water contact angle (WCA1) of the release agent layer on the surface opposite the substrate, the water contact angle (WCA2) after coating and drying a ceramic slurry of a specific composition and storing it in a constant temperature and humidity environment of 23±2°C and 50±5%RH for one week before peeling, and the change in water contact angle (δWCA) can be appropriately adjusted by adjusting the type and amount of materials constituting the release agent layer, the coating amount of the release agent layer, and curing conditions such as the drying temperature and the amount of active energy ray irradiation. In particular, these can be appropriately adjusted by adjusting the reactive functional group equivalent and amount of reactive compound (a) having at least one reactive functional group selected from the group consisting of (meth)acryloyl, hydroxyl, and epoxy groups, particularly reactive compound (a2) having the same reactive functional group as reactive silicone (a1) and having a reactive functional group equivalent of 2000 g / mol or less, or film-forming compound (a3) ​​having two or more (meth)acryloyl groups per molecule.

[0051] The thickness of the release agent layer is preferably 0.05 to 2 μm, and particularly preferably 0.2 to 1.5 μm. A thickness of 0.05 μm or more is preferred from the viewpoint of smoothness of the release agent layer surface and suppression of pinholes and thickness unevenness in the ceramic green sheet. A thickness of 2 μm or less is preferred from the viewpoint of suppressing curling due to cure shrinkage of the release agent layer. It is also preferred from the viewpoint of suppressing blocking and charging.

[0052] Other layers The release film for producing a ceramic green sheet of the present invention may have layers other than the above-mentioned substrate and release agent layer, such as a protective layer, an adhesive layer, an antistatic layer, etc. The substrate and the release agent layer may be laminated directly or via another layer such as an adhesive layer.

[0053] Release film for ceramic green sheet manufacturing The release film for producing ceramic green sheets of the present invention allows easy release of the ceramic green sheets formed thereon, and changes in releasability little over time, so that excellent easy releasability can be stably achieved even long periods after the green sheet is applied. This achieves technical effects of great practical value at a high level that exceeds the limits of conventional technology, and can therefore be suitably used in the production of ceramic green sheets used in various ceramic products, such as multilayer ceramic capacitors or multilayer ceramic substrates.

[0054] There are no particular limitations on the method for producing a ceramic green sheet using the release film for producing a ceramic green sheet of the present invention. For example, the release film for producing a ceramic green sheet of the present invention can be preferably used in a production method having the following steps. A) A step of applying a ceramic slurry onto the release film for producing a ceramic green sheet of the present invention. B) A step of forming a ceramic green sheet from the ceramic slurry applied in the step A). C) A step of peeling the ceramic green sheet formed in the step B) from the release film for producing the ceramic green sheet.

[0055] A) Ceramic slurry coating In step A) of the method for producing a ceramic green sheet of this embodiment, for example, a technique conventionally used in this technical field for applying a ceramic slurry to a release film for producing a ceramic green sheet can be used as appropriate, and for example, the following technique can be used.

[0056] ceramic slurry There are no particular limitations on the ceramic slurry used in step A) of this embodiment, and for example, any ceramic slurry that has been conventionally used in the art for producing ceramic green sheets can be used as appropriate.

[0057] The ceramic slurry used in step A) may be the same as or different from a ceramic slurry of a specific composition (a) containing 45% by mass of barium titanate particles, b) 3.6% by mass of polyvinyl butyral, c) 0.9% by mass of dibutyl phthalate, d) 25% by mass of toluene, and e) 25% by mass of ethanol) that is coated on the release film for producing a ceramic green sheet between the measurements of the bromonaphthalene contact angle BCA1 and the bromonaphthalene contact angle BCA2 when measuring δBCA=BCA2-BCA1, which characterizes the release film for producing a ceramic green sheet of the present invention. That is, the method for manufacturing a ceramic green sheet according to this embodiment is not limited to a method for manufacturing a ceramic green sheet using a ceramic slurry of the above-mentioned specific composition, but can also be applied to a method for manufacturing a ceramic green sheet using a ceramic slurry of a wide range of other compositions.

[0058] The ceramic slurry preferably contains ceramic particles and a solvent, and the ceramic particles are preferably dispersed in the solvent. As the ceramic particles, inorganic compound particles that can form ceramics by sintering can be used, and examples of inorganic compounds include oxides, nitrides, oxynitrides, borides, etc. of metals or semimetals. More specific examples of inorganic compounds include perovskite compounds such as barium titanate (BaTiO3), calcium titanate (CaTiO3), strontium titanate (SrTiO3), calcium zirconate (CaZrO3), strontium zirconate (SrZrO3), etc. When these inorganic compounds are used as the main component of the ceramic particles, they may contain Mn, Mg, Si, Co, Ni, rare earth elements, or the like as a minor component in a content less than that of the main component.

[0059] The particle size of the ceramic particles is preferably 1 μm or less in terms of primary particles.

[0060] The solvent may be an organic solvent or an inorganic solvent such as an aqueous solvent, but an organic solvent is preferred from the viewpoint of ease of solvent removal when forming a ceramic green sheet in step B) described below. A typical organic solvent can be used, and can be appropriately selected depending on the drying temperature when forming the green sheet and the type of binder used. Aromatic, alcohol, ester, ketone, or hydrocarbon solvents are generally used, and a mixture of these can also be used. There is no particular limitation on the boiling point of the solvent, but it is preferably from 60 to 130°C, and particularly preferably from 70 to 130°C.

[0061] From the viewpoint of ease of handling of the ceramic green sheets, the ceramic slurry preferably contains a binder in addition to ceramic particles and a solvent. As the binder, various binders conventionally used in the production of ceramic green sheets in this technical field can be used as appropriate, such as polyvinyl butyral, urethane resin, polyvinyl acetate resin, acrylic resin, cellulose resin, etc. Among them, polyvinyl butyral, acrylic, etc. are particularly preferably used. There are no particular restrictions on the amount of binder used, but it is preferably 3 to 20 parts by mass, and particularly preferably 5 to 15 parts by mass, per 100 parts by mass of ceramic particles.

[0062] The ceramic slurry may contain other components such as a plasticizer, a surfactant, a dispersion stabilizer, an antistatic agent, etc. in addition to the ceramic particles, the solvent, and an optional binder. Suitable plasticizers include dibutyl phthalate and fatty acid esters.

[0063] The ceramic slurry can be produced by stirring and mixing the above-mentioned ceramic particles, an organic solvent, and, if desired, other components such as a binder and a plasticizer. The stirring and mixing method is not particularly limited, and any method and apparatus conventionally used in the art for producing ceramic slurries can be used as appropriate, but stirring and mixing can be performed using, for example, a ball mill, which allows for particle size adjustment of the ceramic particles.

[0064] In step A), the method for applying the ceramic slurry can be appropriately selected depending on the viscosity of the ceramic slurry and the type and thickness of the ceramic green sheet to be formed in step B). For example, an applicator, on-roll die coater, reduced pressure die coater, off-roll die coater, slit coater, curtain coater, lift coater, knife coater, cast coater, reverse roll coater, blade coater, screen printing method, etc. can be appropriately used.

[0065] B) green sheet forming process; In step B), the solvent is removed from the ceramic slurry applied in step A by drying or the like, thereby forming a ceramic green sheet on the release film. The temperature and time for drying in step B) are not particularly limited, but drying can be carried out usually at 60 to 100°C, preferably 70 to 100°C, for usually 30 to 300 seconds, preferably 30 to 200 seconds.

[0066] By setting the drying time in step B) to 30 seconds or more, the particles in the sheet can be uniformly and densely arranged by the time drying is complete, thereby reducing voids in the green sheet. By setting the drying time in step B) to 200 seconds or less, the production efficiency in the ceramic green sheet manufacturing process can be improved.

[0067] By setting the drying temperature in step B) to 70°C or higher, substantially no solvent remains in the ceramic green sheet, preventing the generation of voids in the ceramic during the firing process. Furthermore, by setting the drying temperature to 100°C or lower, the occurrence of swelling or dents on the surface of the green sheet due to rapid evaporation of the solvent can be suppressed. Furthermore, multiple drying zones may be used, with different temperatures for each drying zone.

[0068] C) Peeling process In step C), the ceramic green sheet formed in step B) is peeled off from the release film for producing the ceramic green sheet. The peeling method in step C) is not particularly limited and may be selected appropriately depending on the material and properties of the ceramic green sheet, the subsequent steps, etc. For example, the ceramic green sheet can be peeled off by cutting the ceramic green sheet portion on the release film and then heating or deforming the release film. By using the release film for producing a ceramic green sheet of the present invention, the peel force in step C) can be reduced (light peeling), which effectively reduces breakage of the ceramic green sheet. The peeling force in the peeling step is preferably 5 to 100 (mN / 50 mm), and particularly preferably 10 to 50 (mN / 50 mm).

[0069] By using the release film for producing a ceramic green sheet of the present invention, even if a long time has passed between steps A) and B) and step C), the peel force of the green sheet can be maintained with little change from the initial peel force. For example, even after storage at room temperature for one week following steps A) and B), the peel force in step C) is preferably 115% or less, and particularly preferably 110% or less, of the peel force when step C) is performed immediately after steps A) and B. By having the peel force in step C) after storage at room temperature for one week following step B) being 115% or less, the problem of green sheet breakage can be more effectively suppressed.

[0070] Electrode printing process, half-cut process, punching process In addition to the above steps A) to C), the method for producing a ceramic green sheet of this embodiment may further include a step of performing electrode printing, half-cutting, and / or punching after step B) and before step C).

[0071] By firing the ceramic green sheet obtained by the manufacturing method of this embodiment, various ceramic products can be manufactured. According to the above embodiment in which the electrode printing step is performed after step B) and before step C), after electrode printing, a multilayer ceramic capacitor or a multilayer ceramic substrate can be manufactured through step C) (peeling), lamination and pressure bonding, cutting and separation, firing, and external electrode formation steps.

[0072] By firing the ceramic green sheet obtained by the above-described manufacturing method, various ceramic products can be manufactured. In manufacturing a multilayer ceramic capacitor, a step of printing internal electrodes on the green sheets is inserted between the above steps B) and C).Then, step C) (peeling), lamination and pressure bonding, cutting and separation, firing, and external electrode formation steps are carried out to manufacture the multilayer ceramic capacitor. [Example]

[0073] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0074] In the following Examples and Comparative Examples, the physical properties and characteristics were evaluated by the following methods. (water contact angle) The contact angle of water on the surface of the release agent layer was measured under the following conditions. Contact angle meter: Kyowa Interface Science Co., Ltd. DM-701 Fully Automatic Contact Angle Meter Contact angle meter analysis software: FAMAS by the same company The contact angle θ was calculated using the sessile drop method according to the following procedure. i) The sample cut into a strip was set in a contact angle meter. ii) A droplet of approximately 6.1 μL of water was ejected from the syringe pump. iii) Images of the droplets ejected onto the sample were taken. iv) The angle between the sample and the droplet was measured and taken as the contact angle (°) of water.

[0075] (Bromonaphthalene contact angle) The bromonaphthalene contact angle was measured in the same manner as in the water contact angle measurement method described above, except that 1-bromonaphthalene was used instead of water and the amount of 1-bromonaphthalene was 3.4 μL.

[0076] (peel force) 1) Preparation of ceramic slurry Barium titanate (BT-01, manufactured by Sakai Chemical Industry Co., Ltd.), polyvinyl butyral (S-LEC BH-S, manufactured by Sekisui Chemical Co., Ltd.), dibutyl phthalate, toluene, and ethanol were mixed in a mass ratio of 45:3.6:0.9:25:25 to prepare a ceramic slurry, which would be the raw material for the ceramic green sheets. 2) Formation of ceramic green sheets The ceramic slurry prepared in 1) above was applied to the release agent layer side of the release film sample for producing ceramic green sheets with an applicator to a thickness of 50 μm, and dried at 70°C for 2 minutes to form a ceramic green sheet with a thickness of 10 μm. 3) Measurement of peel strength of green sheet The release film sample and the ceramic green sheet formed on it in the above 2) were cut into strips of 50 mm x 200 mm, and the green sheet was peeled off from the release film at an angle of 180° using a Tensilon (A&D Co., Ltd.: RTG-1210) to measure the peel strength.

[0077] Details of each component such as resin used in the release agent layer in the examples and comparative examples are as follows: (a3) Multifunctional acrylate 1 Shin-Nakamura Chemical Co., Ltd., product name: NK Ester A-9300 Tris-(2-acryloxyethyl) isocyanurate (functional groups: 3) Acrylic equivalent: 141g / mol (a3) Multifunctional acrylate 2 Manufactured by Shin-Nakamura Chemical Co., Ltd., product name: NK Ester A-TMM-3LM-N Pentaerythritol tri- and tetraacrylate (functional groups: 3 and 4) Acrylic equivalent: 93.7g / mol (a3) Multifunctional acrylate 3 Shin-Nakamura Chemical Co., Ltd., product name: NK Ester A-DCP Tricyclodecane dimethanol diacrylate (number of functional groups: 2) Acrylic equivalent: 304g / mol (a3) Multifunctional acrylate 4 Manufactured by Shin-Nakamura Chemical Co., Ltd., product name: NK Ester A-GLY-9E Ethoxylated glycerin triacrylate (functional groups: 3) Acrylic equivalent: 217g / mol (a1) Epoxy-modified silicone 1 Arakawa Chemical Industries, Ltd., product name: Silicolyse UV POLY201 Dimethyl silicone, alicyclic epoxy silicone block copolymer (a2) Epoxy-modified silicone 2 Shin-Etsu Chemical Co., Ltd., product name: Shin-Etsu Silicone KR-470 Alicyclic epoxy group-containing cyclic siloxane tetrafunctional oligomer Epoxy equivalent: 200g / mol (a2) Epoxy-modified silicone 3 Shin-Etsu Chemical Co., Ltd., product name: Shin-Etsu Silicone X-22-169AS Double-ended / alicyclic epoxy-modified silicone oil Epoxy equivalent: 500g / mol (a2) Epoxy-modified silicone 4 Shin-Etsu Chemical Co., Ltd., product name: Shin-Etsu Silicone X-22-169B Double-ended / alicyclic epoxy-modified silicone oil Epoxy equivalent: 1700g / mol Epoxy-modified silicone 5 Shin-Etsu Chemical Co., Ltd., product name: Shin-Etsu Silicone KF-102 Side chain / alicyclic epoxy modified silicone oil Epoxy equivalent: 3600g / mol Cationic initiator 1 Sanshin Chemical Industry Co., Ltd. Product name: San-Aid SI-100 Radical initiator 1 Made by IGM RESINS Product name: Esacure ONE α-Hydroxyketone type photopolymerization initiator

[0078] [Example 1] Polyfunctional acrylate 1, epoxy-modified silicone 1, epoxy-modified silicone 2, cationic initiator 1, and radical initiator 1 were mixed in the mass ratios shown in Table 1 to prepare a curable composition for the release agent layer. A polyethylene terephthalate film having a thickness of approximately 30 μm and a surface arithmetic mean roughness (Ra) of approximately 20 nm was used as the substrate. The curable composition prepared above was applied to one side of the substrate, dried at 100°C for 15 seconds, and then irradiated with ultraviolet light using a high-pressure mercury lamp (integrated light intensity: approximately 40 mJ / cm). 2 ) and cured to form a release agent layer, thereby producing a release film having a substrate and a release agent layer provided on one side of the substrate. The water contact angle and bromonaphthalene contact angle were measured on the release layer surface of the prepared release film by the above-mentioned method to obtain the initial water contact angle WCA1 and the initial bromonaphthalene contact angle BCA1. Next, 1) ceramic slurry was prepared, and 2) ceramic green sheets were formed using the methods described above, and then 3) the peel strength of the green sheets was measured to obtain the initial sheet peel strength. Using a separate unused release film sample and the ceramic slurry obtained in 1) Preparation of Ceramic Slurry, 2) above was used to form a ceramic green sheet, and after storing it for one week in a constant temperature and humidity environment of 23±2°C x 50±5%RH, 3) above the peel strength of the green sheet was measured to obtain the sheet peel strength after one week.Furthermore, after measuring the sheet peel strength after one week (after peeling the green sheet), the water contact angle and bromonaphthalene contact angle were measured again using the above method for the release layer surface of the release film, and the water contact angle after peeling WCA2 and the bromonaphthalene contact angle after peeling BCA2 were obtained. The results are shown in Table 1.

[0079] [Examples 2 to 4 and Comparative Examples 1 to 3] Release films were produced and evaluated in the same manner as in Example 1, except that the formulation of the curing agent composition for the release agent layer was changed to that shown in Table 1. The results are shown in Table 1.

[0080] [Table 1] [Industrial Applicability]

[0081] The release film for producing ceramic green sheets of the present invention allows easy release of ceramic green sheets formed thereon, exhibits little change in releasability over time, and consistently achieves excellent easy releasability even long periods after the green sheet is applied. This achieves technical effects of great practical value at a high level that exceeds the limitations of conventional technology, and can be suitably used in the production of various ceramic products, making it highly applicable in various industrial fields including the electrical and electronics industry, electronic parts industry, machinery industry, and automotive industry. [Explanation of symbols]

[0082] 11: Release film for ceramic green sheet manufacturing 12: Release agent layer 13: Base material

Claims

1. A release film for producing a ceramic green sheet, comprising a substrate and a release agent layer provided on at least one side of the substrate, the release agent layer contains a cured product of a curable composition, the curable composition comprises a dimethylsilicone-alicyclic epoxysilicone block copolymer, a reactive compound having an epoxy equivalent of 2000 g / mol or less and selected from an alicyclic epoxy group-containing cyclic siloxane tetrafunctional oligomer and a dual-end / alicyclic epoxy-modified silicone oil, and a polyfunctional acrylate; The bromonaphthalene contact angle on the surface of the release agent layer opposite to the substrate is １ and A ceramic slurry having the following composition was applied to the surface of the release agent layer opposite to the substrate, dried, and then stored in a constant temperature and humidity environment of 23±2°C x 50±5% RH for one week. After the layer was peeled off, the bromonaphthalene contact angle was measured. The measured bromonaphthalene contact angle BCA ２ and the above BCA １ And, δBCA = BCA ２ -BCA １ The release film for producing a ceramic green sheet, wherein the relationship between the angle .theta. and the surface roughness .theta. is within the range of -1.5° to 1.0°: a) 45% by weight of barium titanate particles, b) 3.6% by weight of polyvinyl butyral, c) 0.9% by weight of dibutyl phthalate, d) 25% by weight of toluene, and e) A ceramic slurry containing 25% by weight of ethanol.

2. 2. The release film for producing a ceramic green sheet according to claim 1, wherein the coating amount of the ceramic slurry is 50 μm before drying, the drying conditions are 70° C. and 2 minutes, and the peeling is performed at an angle of 180°.

3. The water contact angle of the surface of the release agent layer opposite to the substrate is WCA １ and The ceramic slurry was applied to the surface of the release agent layer opposite to the substrate, dried, and then stored in a constant temperature and humidity environment of 23±2°C x 50±5% RH for one week, after which the release agent was peeled off and the water contact angle was measured. The measured water contact angle WCA ２ and the above WCA １ And, δWCA = WCA ２ -WCA １ 3. The release film for producing a ceramic green sheet according to claim 1, wherein the relationship between the angle .theta. and the angle .theta. is within the range of -3.5° to 1.0°.

4. 3. The release film for producing a ceramic green sheet according to claim 1, wherein the surface of the substrate facing the release agent layer has an arithmetic mean roughness (Ra) of 1 to 70 nm.

5. 3. The release film for producing a ceramic green sheet according to claim 1, which is used in producing a multilayer ceramic capacitor or a multilayer ceramic substrate.

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