JP7188536B2 - Release film for manufacturing ceramic green sheets - Google Patents

Description

TECHNICAL FIELD The present invention relates to a release film for manufacturing ceramic green sheets, and more specifically, a release film for manufacturing ceramic green sheets that can suppress the occurrence of process defects such as pinholes and uneven thickness when manufacturing ultra-thin ceramic green sheets. It is about film.

Conventionally, a release film obtained by laminating a release layer on a polyester film as a base material has been used for molding ceramic green sheets such as laminated ceramic capacitors and ceramic substrates. In recent years, along with miniaturization and increase in capacity of laminated ceramic capacitors, the thickness of ceramic green sheets tends to be reduced. A ceramic green sheet is formed by coating a release film with a slurry containing a ceramic component such as barium titanate and a binder resin such as polyvinyl acetal resin, followed by drying. After electrodes are printed on the molded ceramic green sheets and separated from the release film, the ceramic green sheets are laminated, pressed, fired, and external electrodes are applied to manufacture the laminated ceramic capacitor. Until now, when molding a ceramic green sheet on the release layer surface of a polyester film, minute protrusions on the surface of the release layer affect the molded ceramic green sheet, and defects such as cissing and pinholes are likely to occur. There was a problem. Therefore, techniques have been developed for realizing a release layer surface with excellent flatness (see, for example, Patent Document 1).

However, in recent years, the thickness of ceramic green sheets has been further reduced, and ceramic green sheets having a thickness of 1.0 μm or less, more specifically, a thickness of 0.2 μm to 1.0 μm have been required. Therefore, a release film having a smoother release layer surface is desired. In addition, as the thickness of the ceramic green sheet decreases, the strength of the ceramic green sheet decreases. Therefore, it is desired that the peel force when peeling the ceramic green sheet from the release film be low and uniform. That is, it is becoming more important to minimize the force applied to the ceramic green sheets when peeling the ceramic green sheets from the release film so as not to damage the ceramic green sheets.

In recent years, it has been found that the surface of the release layer can be made smooth by using a cured product of a composition containing a radical-curable substance that reacts under irradiation with active energy rays and a silicone-based component as the release layer. served. In addition, by increasing the elastic modulus of the release layer, it becomes difficult for the release layer to deform when the ceramic green sheet is peeled off, making it difficult for the release layer to follow the ceramic green sheet. (see Patent Documents 2 and 3, for example).

However, according to the methods described in Patent Literatures 2 and 3, there is a possibility that curing failure may occur due to the influence of oxygen inhibition due to the radical polymerization reaction. In particular, the silicone component segregated on the release layer surface is susceptible to oxygen inhibition, and when using a silicone component having a radically polymerizable functional group, the curability of the release layer surface may deteriorate. . As a result, the release layer is eroded by the organic solvent used during ceramic sheet processing and electrode printing, causing heavy release and deterioration in release uniformity, which may cause defects in the ceramic green sheet during release.

In general, radical polymerization in an inert gas atmosphere can prevent poor curing due to oxygen inhibition, but in this case, the introduction of special equipment is required, and the processing speed is limited. Therefore, there was a problem in terms of productivity and cost. When manufacturing in the atmosphere, it is necessary to secure a sufficient film thickness of the release layer to prevent poor curing due to oxygen inhibition. When the thickness of the release film is large, there is a problem that the release film tends to curl. As a result, there is a possibility that the accuracy of electrode printing after molding the ceramic green sheet may be lowered, and there has been a demand for a release film that curls less. On the other hand, when the thickness of the release layer is reduced to suppress curling, poor curing due to oxygen inhibition is likely to occur, and the solvent resistance of the release layer deteriorates, which may cause heavy release. .

That is, using a photo-radical curable substance that reacts with active energy ray irradiation in the air, the release layer is cured to a thin film thickness, specifically 0.5 μm or less, further 0.3 μm or less. In some cases, the radical curing reaction does not proceed efficiently due to the influence of oxygen inhibition, which may lead to poor curing and damage to the ceramic green sheet during detachment.

JP-A-2000-117899 WO2013/145864 WO2013/145865

The present invention has been made against the background of such problems of the prior art. That is, the object of the present invention is to provide a release layer that maintains high smoothness on the surface of the release layer of the release film, has excellent solvent resistance, has small cure shrinkage, has low release force and is uniform. It is an object of the present invention to provide a release film for producing a ceramic green sheet, which can form a ceramic green sheet having few defects even in an ultra-thin layer product having a thickness of 1 μm or less.

That is, the present invention consists of the following configurations.
1. A release film provided with a release layer on at least one side of a polyester film, wherein the release layer surface has an area average surface roughness (Sa) of 7 nm or less, and the release layer contains a (meth)acryloyl group and A composition containing a radical-curable substance (a) having one or more radical-curable functional groups selected from alkenyl groups, a thiol group-containing compound (b), a release agent (c), and a radical initiator (d) Release film for manufacturing ceramic green sheets, which is obtained by curing a material.
2. 1. The release film for producing a ceramic green sheet according to 1 above, wherein the thiol group-containing compound (b) does not have a radical-curable functional group selected from (meth)acryloyl groups and alkenyl groups.
3. 2. The release film for producing a ceramic green sheet according to the above 1st or 2nd, wherein the thiol group-containing compound (b) is a compound having two or more thiol groups in one molecule.
4. The difference (θ ₁ - θ ₂ ) between the diiodomethane contact angle θ ₁ on the release layer surface and the diiodomethane contact angle θ ₂ on the release layer surface after the release film is immersed in toluene is 3.0° or less as an absolute value. A release film for producing a ceramic green sheet according to any one of the above 1st to 3rd.
5. 4. The release film for producing a ceramic green sheet according to any one of 1 to 4 above, wherein the release agent (c) is a compound containing a silicone component.
6. 4. The release film for producing a ceramic green sheet according to any one of 1 to 4 above, wherein the release agent (c) is a compound containing a fluorine atom in the molecule.
7. The content of the thiol group-containing compound (b) is 1 to 30% by mass with respect to the total mass of the composition forming the release layer. release film.
8. The polyester film has a surface layer A that does not substantially contain inorganic particles and an opposite surface layer B that contains inorganic particles, a release layer is provided on the surface layer A, and the surface layer The ceramic green sheet according to any one of the above 1st to 7th, wherein the inorganic particles contained in B are silica particles and/or calcium carbonate particles, and the total amount of the inorganic particles is contained in the surface layer B at 5000 to 15000 ppm. Release film for manufacturing.
9. 8. The release film for producing a ceramic green sheet as described in any one of 1 to 8 above, wherein the thickness of the release layer is in the range of 0.01 μm or more and 0.5 μm or less.
10. (Meth) a radical-curable substance having one or more radical-curable functional groups selected from acryloyl groups and alkenyl groups (a), a thiol group-containing compound (b), a release agent (c), a radical initiator ( 9. The method for producing a release film for producing a ceramic green sheet according to any one of 1 to 9 above, wherein the composition containing d) is cured in the air to form a release layer.
11. Method 12 for producing a ceramic green sheet having a thickness of 0.2 μm to 1.0 μm, wherein the release film for producing a ceramic green sheet according to any one of the first to ninth above is used. . A method for manufacturing a ceramic capacitor employing the method for manufacturing a ceramic green sheet according to the eleventh aspect.

The release film for producing a ceramic green sheet of the present invention can suppress oxygen inhibition, which is a problem peculiar to radical curing substances, and can improve the curability of the surface of the release layer, so it is excellent in solvent resistance and peelability. A release film can be provided. In addition, since curing shrinkage can be reduced, the occurrence of curling is suppressed, and it is possible to provide a release film for producing a ceramic green sheet that does not cause unevenness in the thickness of the ceramic green sheet or decrease the accuracy of electrode printing. can.

The present inventors provided a release layer on at least one side of a biaxially oriented polyester film directly or via another layer, and adjusted the area average surface roughness (Sa) of the release layer surface to 7 nm or less. The composition is a cured composition containing a radical curable substance (a), a thiol group-containing compound (b), a release agent (c), and a radical initiator (d). However, the inventors have found that the film thickness of the release layer can be reduced and a release film free from curling can be provided. The present invention will be described in detail below.

(polyester film)
The polyester constituting the polyester film used as the base material of the present invention is not particularly limited, and it is possible to use a film-molded polyester that is commonly used as a base material for a release film, but preferably, It is preferably a crystalline linear saturated polyester comprising an aromatic dibasic acid component and a diol component, such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, or resins thereof Component-based copolymers are more preferred, and polyester films formed from polyethylene terephthalate are particularly preferred. In polyethylene terephthalate, the repeating unit of ethylene terephthalate is preferably 90 mol % or more, more preferably 95 mol % or more, and may be copolymerized with a small amount of other dicarboxylic acid component or diol component, but from the viewpoint of cost. , preferably made only from terephthalic acid and ethylene glycol. In addition, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, crystallization agents, etc. may be added within limits that do not impair the effects of the film of the present invention. The polyester film is preferably a biaxially oriented polyester film because of its high bidirectional elastic modulus.

The intrinsic viscosity of the polyethylene terephthalate film is preferably 0.50 to 0.70 dl/g, more preferably 0.52 to 0.62 dl/g. When the intrinsic viscosity is 0.50 dl/g or more, it is preferable because many breakages do not occur in the stretching process. Conversely, when it is 0.70 dl/g or less, the cutting performance is good when cutting into a predetermined product width, and dimensional defects do not occur, which is preferable. Moreover, it is preferable to sufficiently vacuum-dry the raw material.

The method for producing the polyester film in the present invention is not particularly limited, and conventionally generally used methods can be used. For example, the polyester can be melted by an extruder, extruded into a film, cooled by a rotating cooling drum to obtain an unstretched film, and biaxially stretched to obtain the unstretched film. The biaxially stretched film can be obtained by a method of sequentially biaxially stretching a longitudinally or laterally uniaxially stretched film in the lateral direction or longitudinal direction, or by a method of simultaneously biaxially stretching an unstretched film in the longitudinal direction and the lateral direction. I can.

In the present invention, the stretching temperature during stretching of the polyester film is preferably higher than the secondary transition point (Tg) of the polyester. It is preferable that the film is stretched 1 to 8 times, particularly 2 to 6 times, in each of the longitudinal and transverse directions.

The polyester film preferably has a thickness of 12 to 50 μm, more preferably 15 to 38 μm, and still more preferably 19 to 33 μm. If the thickness of the film is 12 μm or more, it is preferable because there is no risk of deformation due to heat during film production, processing, and molding. On the other hand, if the thickness of the film is 50 μm or less, the amount of the film to be discarded after use is not excessively increased, which is preferable for reducing the environmental load.

The polyester film substrate may be a single layer or a multilayer of two or more layers, but it is preferably a laminated film having a surface layer A substantially free of inorganic particles on at least one side. . In the case of a laminated polyester film having a multilayer structure of two or more layers, it is preferable to have a surface layer B capable of containing inorganic particles and the like on the opposite side of the surface layer A which does not substantially contain inorganic particles. As a laminated structure, 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 configuration in the thickness direction is release layer / A / B, or a laminated structure such as release layer/A/C/B. Of course, the C layer may have a multi-layer structure. In addition, the surface layer B may not contain inorganic particles. In that case, it is preferable to provide a coating layer containing at least inorganic particles and a binder on the surface layer B in order to impart lubricity for winding the film into a roll.

In the polyester film substrate of the present invention, the surface layer A forming the surface to be coated with the release layer preferably does not substantially contain inorganic particles. At this time, the area surface average roughness (Sa) of the surface layer A is preferably 7 nm or less. When Sa is 7 nm or less, pinholes and the like are less likely to occur during molding of laminated ultra-thin ceramic green sheets, which is preferable. It can be said that the smaller the region surface average roughness (Sa) of the surface layer A is, the more preferable it is, but it may be 0.1 nm or more. Here, when the below-described anchor coat layer or the like is provided on the surface layer A, it is preferable that the coat layer does not substantially contain inorganic particles, and the region surface average roughness (Sa) after lamination of the coat layer is within the above range. It is preferable to enter In the present invention, "substantially free of inorganic particles" means that the inorganic particles are 50 ppm or less, preferably 10 ppm or less, most preferably less than the detection limit when the inorganic elements are quantified by fluorescence X-ray analysis. means content. This is because even if inorganic particles are not positively added to the film, contaminants derived from foreign substances and dirt adhering to the lines and equipment in the raw material resin or film manufacturing process peel off and mix into the film. This is because there are cases.

In the polyester film substrate of the present invention, the surface layer B, which forms the surface opposite to the surface to which the release layer is applied, preferably contains inorganic particles from the viewpoint of film slipperiness and ease of air release. In particular, silica particles and/or calcium carbonate particles are preferably used. The content of the inorganic particles contained in the surface layer B is preferably 5000 to 15000 ppm in total of the inorganic particles. At this time, the area average surface roughness (Sa) of the film of the surface layer B is preferably in the range of 1 to 40 nm. More preferably, it is in the range of 5 to 35 nm. When the total amount of silica particles and/or calcium carbonate particles is 5000 ppm or more and Sa is 1 nm or more, when the film is wound into a roll, air can be released uniformly, resulting in a good roll shape and good flatness. , suitable for the production of ultra-thin ceramic green sheets. In addition, when the total amount of silica particles and/or calcium carbonate particles is 15000 ppm or less and Sa is 40 nm or less, aggregation of the lubricant is difficult to occur and coarse protrusions cannot be formed, so that the quality is stable when manufacturing an ultra-thin ceramic green sheet. and preferred.

As the particles contained in the B layer, inactive inorganic particles and/or heat-resistant organic particles can be used in addition to silica and/or calcium carbonate. More preferably, calcium carbonate particles are used. Inorganic particles that can also be used include alumina-silica composite oxide particles, hydroxyapatite particles, and the like. Examples of heat-resistant organic particles include crosslinked polyacrylic particles, crosslinked polystyrene particles, and benzoguanamine particles. When silica particles are used, porous colloidal silica is preferable, and when calcium carbonate particles are used, light calcium carbonate surface-treated with a polyacrylic acid-based polymer compound is preferable from the viewpoint of preventing the lubricant from falling off. .

The average particle size of the inorganic particles added to the surface layer B is preferably 0.1 μm or more and 2.0 μm or less, and particularly preferably 0.5 μm or more and 1.0 μm or less. If the average particle size 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 size is 2.0 μm or less, it is preferable because there is no fear of generating pinholes in the ceramic green sheet due to coarse particles on the surface of the release layer.

The surface layer B may contain two or more kinds of particles made of different materials. Further, particles of the same type but different in average particle diameter may be contained.

When the surface layer B does not contain particles, it is preferable that a coating layer containing particles on the surface layer B provides lubricity. Although the present coat layer is not particularly limited, it is preferably provided as an in-line coat that is applied during film formation of the polyester film. When the surface layer B does not contain particles and the surface layer B has a coat layer containing particles, the surface of the coat layer has a region surface roughness (Sa) for the same reason as the region surface roughness (Sa) of the surface layer B The average surface roughness (Sa) is preferably in the range of 1-40 nm. More preferably, it is in the range of 5 to 35 nm.

From the viewpoint of reducing pinholes, it is preferable not to use recycled raw materials in the surface layer A, which is the layer on which the release layer is provided, in order to prevent inorganic particles such as lubricants from being mixed.

The thickness ratio of the surface layer A, which is the layer on which 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, the inside of the film is less likely to be affected by the particles contained in the surface layer B, etc., and it is easy for the region surface average roughness Sa to satisfy the above range, which is preferable. When the total thickness of the base film is 50% or less of the total thickness of the base film, the ratio of the recycled raw material used in the surface layer B can be increased, and the environmental load is small, which is preferable.

From the viewpoint of economy, the layers other than the surface layer A (the surface layer B or the intermediate layer C described above) may contain 50 to 90% by mass of recycled film scraps and PET bottle raw materials. Even in this case, the type and amount of the lubricant contained in the B layer, the particle size, and the area surface average roughness (Sa) preferably satisfy the above ranges.

In addition, in order to improve the adhesion of a release layer to be applied later, or to prevent electrification, a film before stretching or after uniaxial stretching is applied to the surface of the surface layer A and / or surface layer B in the film forming process. A coat layer may be provided on the surface, and corona treatment or the like may be applied.

(release layer)
The release layer in the present invention comprises a radical-curable substance (a) having a radical-curable functional group selected from (meth)acryloyl groups and alkenyl groups, a thiol group-containing compound (b), a release agent (c), It is preferably obtained by curing a composition containing the radical initiator (d). Additives other than the above resins and additives can be added as long as they do not impair the functions of the present invention. Here, in the present invention, the radical curable substance (a) and the thiol group-containing compound (b) are considered to have changed their structure after being cured in the coating layer. Since it is extremely difficult to accurately express and describe the structure itself, as described above, the release layer has a radical-curable functional group selected from (meth)acryloyl and alkenyl groups. ), a thiol group-containing compound (b), a release agent (c), and a radical initiator (d) are cured."

(Radical curable substance (a))
The radical-curable substance (a) preferably has a radical-curable functional group selected from a (meth)acryloyl group and an alkenyl group, and is a substance having one or two or more radical-curable functional groups. can be used. Since radical curing has a very high reaction rate, the polymerization reaction progresses instantaneously at the same time as the radical initiator is cleaved, and a coating film with a high crosslink density can be formed. By increasing the crosslink density of the release layer, the release layer can have a high elastic modulus, the release layer is less likely to deform when the ceramic green sheet is peeled off, and the ceramic green sheet can be uniformly peeled off with a low peel force, which is preferable. The alkenyl group in the present invention refers to those having 2 to 10 carbon atoms such as vinyl group, allyl group, propenyl group and hexenyl group.

The number of radical-curable functional groups is preferably 3 or more, more preferably 6 or more, and even more preferably 9 or more, from the viewpoint of increasing the crosslink density. Although there is no particular upper limit to the number of functional groups, it is preferably 20 or less. By making it 20 or less, the intramolecular reaction proceeds more easily than the intermolecular cross-linking reaction, and the effect of efficiently improving the elastic modulus of the release layer is obtained, which is preferable.

Examples of radical-curable substances include acrylates, methacrylates, urethane acrylates, acrylamides, allyl compounds, methallyl compounds, and maleimide compounds. From the viewpoint of reactivity, acrylates, methacrylates, urethane acrylates, allyl compounds, and methallyl compounds are preferred. Most preferred are acrylates, methacrylates and urethane acrylates. Acrylates and methacrylates have a relatively large cure shrinkage, but in the present invention, they can be used favorably because the film thickness can be reduced, so that there is no risk of appearance defects such as curling. From the viewpoint of curling, urethane acrylate is most suitable because of its small cure shrinkage.

The radical curing substance to be used may be a monomer, an oligomer, or a polymer, but it is preferable to use a monomer or an oligomer from the viewpoint of solubility in organic solvents and handleability. These may be used alone or in combination of two or more.

When using a monomer as a (meth)acrylate, for example, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol Tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated isocyanurate tri(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and the like.

When oligomers are used as (meth)acrylates, examples include polyfunctional (meth)acrylate oligomers, polyester acrylate oligomers, epoxy acrylate oligomers, polyether acrylate oligomers, polybutadiene acrylate oligomers, and silicone acrylate oligomers. .

The urethane acrylate used in the present invention means one having a urethane bond and one or more radical-curing functional groups selected from acryloyl groups and methacryloyl groups in the molecular chain. Although the synthesis method is not particularly limited, it can be obtained, for example, by reacting a polyhydric alcohol and an organic polyisocyanate with hydroxyacrylate.

Examples of the polyhydric alcohol include neopentyl glycol, 3-methyl-1,5-pentanediol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, and pentaerythritol. , tricyclodecanedimethylol, bis-[hydroxymethyl]-cyclohexane, etc.; the above polyhydric alcohols and polybasic acids (e.g., succinic acid, phthalic acid, hexahydrophthalic anhydride, terephthalic acid, adipic acid, azelaic acid, tetrahydroanhydride polyester polyol obtained by reaction with phthalic acid, etc.); polycaprolactone polyol obtained by reaction of the above polyhydric alcohol with ε-caprolactone; polycarbonate polyol (for example, obtained by reaction of 1,6-hexanediol and diphenyl carbonate) polycarbonate diols, etc.); and polyether polyols. Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene oxide-modified bisphenol A, and the like.

Examples of the organic polyisocyanate include isocyanate compounds such as isophorone diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, xylene diisocyanate, diphenylmethane-4,4′-diisocyanate and dicyclopentanyl isocyanate, adducts of these isocyanate compounds, or these Polymers of isocyanate and the like can be mentioned.

Examples of the hydroxy(meth)acrylate compounds include pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, hydroxyethyl (meth)acrylate, ) acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, dimethylolcyclohexyl mono (meth)acrylate, hydroxycaprolactone (meth)acrylate and the like. Among them, pentaerythritol tri(meth)acrylate and dipentaerythritol penta(meth)acrylate are preferable from the viewpoint of hardness.

Commercially available urethane acrylates can also be used in the present invention. Examples of commercially available products include UV1700B (10-functional), UV7620EA (9-functional), UV7610B (9-functional), UV7600B (6-functional), UV7650B (5-functional) manufactured by Nippon Kayaku Co., Ltd.: DPHA40H (10 functional), UX5003 (hexafunctional), Arakawa Chemical Industries: Beamset 577 (hexafunctional), Taisei Fine Chemicals: 8UX-015A (15 functional) and Shin-Nakamura Chemical: U15HA (15 functionality) and the like.

The compound having an alkenyl group used in the release layer of the present invention is not particularly limited, and general compounds can be suitably used. Examples of commercially available products include Nippon Kasei Co., Ltd.: TAIC (registered trademark) triallyl isocyanurate (trifunctional), Shikoku Kasei Co., Ltd.: LDAIC (bifunctional), TA-G (tetrafunctional), DD-1. (tetrafunctional) and the like.

(thiol group-containing compound (b))
The release layer in the invention preferably contains a thiol group-containing compound. Since the thiol group-containing compound acts as a curing accelerator for radical polymerization reaction, it is less susceptible to oxygen inhibition and exhibits excellent reactivity even in the atmosphere. Therefore, it is possible to enhance the curability of the release layer surface and improve the solvent resistance, which is preferable. In addition, since oxygen inhibition is suppressed, even if the release layer is made thin, deterioration of solvent resistance and peeling failure do not occur, which is preferable. Furthermore, since the thiol group-containing compound undergoes an addition polymerization reaction with the radical-curable functional group, it is incorporated into the crosslinked structure of the radical-curable substance, and a flexible structure derived from the thiol group-containing compound is introduced into the cured product. Therefore, even if the thickness of the release layer is thick, curing shrinkage, which is a problem peculiar to radical curing substances, can be suppressed. It is preferable because there is no risk of causing

When a coating film containing a radically curable substance is cured in the atmosphere, polar groups such as hydroxyl groups and carboxyl groups are formed on the surface due to oxygen inhibition, which improves the wettability of the ceramic slurry. When a coating film containing a radically curable substance is cured in an inert gas atmosphere, the effect of suppressing oxygen inhibition is large, and the curability of the surface can be enhanced, but on the other hand, the wettability of the ceramic slurry is poor. As a result, there is a problem that repelling and pinholes are likely to occur in the molded ceramic green sheets. A thiol group-containing compound is preferable because it can exhibit two contradictory effects of improving surface hardness and improving wettability by inhibiting oxygen.

Furthermore, by forming the release layer from a cured product containing a thiol group-containing compound, S atoms are introduced into the release layer, thereby improving affinity with the molded ceramic green sheet. Therefore, the ceramic green sheets are less likely to float during transportation, and the occurrence of defects can be suppressed, which is preferable.

The thiol group-containing compound is not particularly limited and a common one is used, but it preferably does not contain a radical-curable functional group selected from (meth)acryloyl groups and alkenyl groups. By using a thiol group-containing compound that does not have the radical-curable functional group, the radical-curable functional groups in the same molecule preferentially react with each other rather than the thiol group that functions as a curing accelerator, resulting in oxygen It is preferable because there is no possibility that the effect of suppressing inhibition will be lost. In addition, the thiol group-containing compound in the present invention refers to an organic compound having a hydrogenated sulfur atom at its terminal, and is synonymous with a compound called thioalcohol. A thiol group is also called a mercapto group or a sulfhydryl group.

The number of functional groups in the thiol group-containing compound is preferably 2 or more, more preferably 3 or more, and most preferably 4 or more. When the number of functional groups is 2 or more, it becomes easier to form a crosslinked structure with the radical curable substance, and the effect of inhibiting inhibition of oxygen can be easily obtained, which is preferable.

Examples of thiol group-containing compounds include 1,4-bis(3-mercaptobutyryloxy)butane, tetraethylene glycol bis(3-mercaptopropionate) 1,3,5-tris(3-mercaptobutyryloxy ethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimethylolpropane tris(3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)- ethyl]-isocyanurate, pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutyrate), dipentaerythritol hexakis (3-mercaptopropionate) and the like.

Commercially available thiol group-containing compounds can be suitably used. Examples include Karenz MT (registered trademark) BD1 (bifunctional), NR1 (trifunctional), PE1 (tetrafunctional) manufactured by Showa Denko Co., Ltd., and TMMP (trifunctional) and TEMPIC (trifunctional) manufactured by SC Organic Chemical Co., Ltd. , PEMP (tetrafunctional), EGMP-4 (tetrafunctional), DPMP (hexafunctional), and the like.

As the thiol group-containing compound, a polymer, an oligomer, or a monomer can be suitably used, but a monomer is most preferable. The molecular weight is preferably 10,000 or less, most preferably 1,000 or less. By setting the molecular weight to 10,000 or less, the number of thiol groups per fixed mass becomes a sufficient number to obtain the effect of accelerating radical curing, which is preferable.

The content of the thiol group-containing compound contained in the release layer is preferably 1 to 30% by mass or less, more preferably 2 to 25% by mass or less, relative to the solid content of the entire release layer. Preferably, it is 5 to 20 mass % or less, most preferably. By setting the content of the thiol group-containing compound to 1% by mass or more, the radical curing reaction is accelerated and the effect of making the oxygen inhibition less likely to occur is sufficiently obtained, which is preferable. When the content is 30% by mass or less, the cured product does not become too flexible due to the thiol group-containing compound, and the effect of improving the elastic modulus due to cross-linking between the radical curable substances is obtained, which is preferable.

(Release agent (c))
Examples of release agents (additives for imparting release properties) used in the release layer of the present invention include silicone-based additives and non-silicone additives such as fluorine-based, long-chain alkyl-based, and olefin-based additives. can be preferably used.

The silicone-based additive is a material having polyorganosiloxane with an organic group attached to the siloxane bond, and is not particularly limited as long as the effects of the present invention can be obtained, and a general one can be used. can be done. Among polyorganosiloxanes, dialkylsiloxanes can be preferably used, among which dimethylsiloxane is more preferably used, and dimethylsiloxane having a functional group as a part thereof is even more preferable. Having a functional group facilitates the expression of intermolecular interactions such as hydrogen bonding with the radical-curing substance, making it difficult to migrate to the ceramic green sheet, which is preferable.

The functional group to be introduced into polydimethylsiloxane is not particularly limited, and may be a reactive functional group or a non-reactive functional group. Moreover, the functional group may be introduced at one end of the polydimethylsiloxane, may be introduced at both ends, or may be a side chain. Also, the position to be introduced may be one or plural.

A hydroxyl group, a carboxyl group, a (meth)acryloyl group, an alkenyl group, a thiol group and the like can be used as the reactive functional group to be introduced into the polydimethylsiloxane. Among them, it is preferable to have a radical-curable functional group such as a (meth)acryloyl group, an alkenyl group, or a thiol group. By using polydimethylsiloxane having a radically curable functional group, it is possible to form a crosslinked structure with the radically curable substance (a) and the thiol group-containing compound (b), making it difficult for migration to the ceramic green sheet to occur. preferable. From the standpoint of solvent resistance, the greater the number of reactive functional groups, the easier it is to form a crosslinked structure, which is preferable. The term "radical-curable functional group" as used herein refers to a functional group such as a (meth)acryloyl group or an alkenyl group that can become a cross-linking point in a radical curing reaction.

As non-reactive functional groups to be introduced into polydimethylsiloxane, polyether groups, alkyl groups, fluoroalkyl groups, long-chain alkyl groups, ester groups, amide groups, phenyl groups, and the like can be used.

As the silicone component, it is particularly preferable to use polydimethylsiloxane-modified resins such as acrylic resins, polyester resins, and urethane resins having polydimethylsiloxane in side chains. Polydimethylsiloxane-modified resins are preferred because they have better compatibility with radical-curing substances than other general release agents and can form a uniform release layer, thereby improving releasability. In addition, it is preferable because intermolecular interaction with the radical curable substance is likely to occur and the solvent resistance is improved. Furthermore, it is preferable because migration of the release agent to the ceramic green sheet is less likely to occur during peeling. Among polydimethylsiloxane-modified resins, it is preferable to use a polydimethylsiloxane-modified resin having a radical-curable functional group. A polydimethylsiloxane-modified resin having a radical-curable functional group is preferable because it can form a crosslinked structure with the radical-curable substance (a) or the thiol group-containing compound (b), thereby further improving solvent resistance.

Examples of commercially available acrylic resins having a polydimethylsiloxane skeleton in the side chain include SYMAC (registered trademark) US350, SYMAC (registered trademark) US352 (manufactured by Toagosei Co., Ltd.), 8BS-9000 (manufactured by Taisei Fine Chemical Co., Ltd.), GL-01, GL-03R (manufactured by Kyoeisha Chemical Co., Ltd.) and the like. Examples of commercially available acrylic resins having a polydimethylsiloxane skeleton and a radical-curable functional group on the side chain include 8SS-723 (manufactured by Taisei Fine Chemicals Co., Ltd.), GL-02, GL-04R (manufactured by Kyoeisha Chemical Co., Ltd.), etc. is mentioned.

The fluorine-based additive is not particularly limited, and existing ones can be used. For example, one having a perfluoro group or one having a perfluoroether group can be preferably used. For the same reason as the silicone additive, it is preferable to have a functional group, and it is more preferable to have a radical-curable functional group. Commercially available products include 8FX-038EX (manufactured by Taisei Fine Chemical Co., Ltd.), OPTOOL (registered trademark) (manufactured by Daikin Industries, Ltd.), Megafac (registered trademark) RS-72-K, RS-75, RS-78 (above, DIC company), F Escort (registered trademark) UT-UCH23 (manufactured by AGC Seimi Chemical Co., Ltd.), EBECRYL (registered trademark) 8110 (manufactured by Daicel Allnex), Fclear (registered trademark) (manufactured by Kanto Denka Kogyo Co., Ltd.), etc. be done.

A long-chain alkyl-modified resin can be used as the long-chain alkyl-based additive, and those having an alkyl group having about 8 to 20 carbon atoms in the side chain, such as polyvinyl alcohol and acrylic resin, are preferable. Further, a copolymer having a (meth)acrylic acid ester as a main repeating unit and containing a long-chain alkyl group having 8 to 20 carbon atoms in the transesterified portion can also be preferably used. Also, octyl acrylate, lauryl acrylate, stearyl acrylate, etc. in which an acrylate group is attached to a long-chain alkyl can be preferably used.

Examples of commercially available long-chain alkyl additives include Pyroyl (registered trademark) 1010, 1050, 1070 (manufactured by Lion Specialty Chemicals), Tesfine (registered trademark) 305, 314 (manufactured by Hitachi Kasei Co., Ltd.) and the like.

The olefinic additive is not particularly limited, and a general one can be used. For example, polybutadiene, cycloolefin resins, and the like can be suitably used. Commercially available products include NISSO-PB (registered trademark) B series, G series, JP series (hereinafter, manufactured by Nippon Soda Co., Ltd.), and ARTON (registered trademark) (manufactured by JSR Corporation).

Also, two or more of the release agents may be mixed and used. At this time, although it is not particularly limited by theory, it is better to use two types having different functional groups in terms of releasability, and it is more preferable to use reactive functional groups.

The release layer in the present invention preferably contains 0.05% by mass or more and 20% by mass or less of the release agent (c) based on the solid content of the entire release layer. It is more preferably 0.1% by mass or more and 10% by mass or less, and still more preferably 0.1% by mass or more and 5% by mass or less. When the amount is more than 0.1% by mass, the releasability is imparted, and there is no fear of deteriorating the releasability of the ceramic green sheet, which is preferable. When the content is less than 20% by mass, repelling is less likely to occur when the ceramic slurry is applied, and there is no possibility that the thickness of the ceramic green sheet will be uneven.

(Radical initiator (d))
A radical initiator is preferably used for the release layer in the present invention in order to promote the radical curing reaction. As the radical initiator, both a thermal radical initiator and a photoradical initiator can be preferably used, but it is preferable to use a photoradical initiator because the amount of heat during processing can be suppressed. One type or two or more types of initiators may be used, and a photoradical initiator and a thermal radical initiator may be used at the same time.

The radical initiator is not particularly limited and general ones can be used. Specific examples include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone. , 1-hydroxycyclohexylphenyl ketone, benzyldiphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, 2-benzothiazole-N,N-diethyldithiocarbamate and the like.

As the radical initiator, α-hydroxyalkylphenones and α-aminoalkylphenones, which are said to be particularly excellent in surface curability, can be preferably used to suppress oxygen inhibition. Examples of α-hydroxyalkylphenones include 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}- 2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl- and 1-propan-1-one. Examples of α-aminoalkylphenones include 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-methyl-1-(4-methylthiophenyl)-2-morpholinopro pan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholyl)phenyl]-1-butanone and the like.

When a photoradical initiator is used, a sensitizer can be added to promote absorption of active energy rays and further improve curability. The sensitizer is not particularly limited and commonly used ones, but anthracene derivatives and naphthalene derivatives are suitable. One type or two or more types of sensitizers may be used.

The amount of the radical initiator added is preferably 0.1% by mass or more and 20% by mass or less, and is 0.5% by mass or more and 10% by mass or less with respect to the total solid content in the release layer. is more preferable, and it is most preferable that the content is 1% by mass or more and 8% by mass or less. When the content is 0.1% by mass or more, the amount of generated radicals becomes insufficient, which is preferable because there is no risk of insufficient curing. When the amount is 20 parts by mass or less, the amount of the radical initiator residue contained in the release layer is reduced, which is preferable because it is possible to suppress deterioration of releasability and transfer to the ceramic green sheet to be molded.

The amount of the sensitizer to be added is preferably 0.1 to 5 times the weight of the radical photoinitiator. More preferably, it is 0.1 to 2 times. When it is larger than 0.1 times, it is preferable because a sufficient sensitizing effect can be obtained. If it is smaller than 5 times, it is preferable because there is no possibility that the absorption of the active energy ray by the photoradical initiator will be inhibited and the amount of generated radicals will be insufficient.

The release layer in the present invention may contain particles having a particle size of 1 μm or less, but from the viewpoint of pinhole generation, it is preferable not to contain particles that form protrusions.

Additives such as an adhesion improver and an antistatic agent may be added to the release layer in the present invention as long as the effects of the present invention are not impaired. In order to improve adhesion to the substrate, it is also preferable to subject the surface of the polyester film to pretreatment such as anchor coating, corona treatment, plasma treatment, atmospheric pressure plasma treatment, etc. before providing the release coating layer.

In the present invention, the thickness of the release layer may be set according to the purpose of use, and is not particularly limited. , more preferably 0.05 to 0.4 μm, more preferably 0.1 to 0.4 μm. In particular, when a release layer is provided on the surface layer A of a polyester film having a surface layer A that does not substantially contain inorganic particles, the thinner the thickness of the release layer, the lower the coating material cost. , which is economical and capable of suppressing the occurrence of curling, is preferable. Specifically, it is preferably 0.4 μm or less, more preferably 0.3 μm or less. When the thickness of the release layer is thicker than 0.01 μm, sufficient release performance can be obtained, which is preferable. Further, when the thickness is less than 0.5 μm, curling of the release film due to curing shrinkage is less likely to occur, which is preferable because there is no risk of unevenness in the thickness of the ceramic green sheet or deterioration of electrode printing accuracy.

The surface of the release layer of the release film of the present invention is desirably flat so as not to cause defects in the ceramic green sheet coated and molded thereon, and the area surface average roughness (Sa) is 7 nm or less. Preferably. Further, it is more preferable that the above Sa is satisfied and the maximum projection height (P) on the release layer surface is 100 nm or less. It is particularly preferable if the region surface average roughness (Sa) is 5 nm or less and the maximum projection height is 80 nm or less. If the area surface roughness is 7 nm or less, defects such as pinholes do not occur when the ceramic green sheets are formed, and the yield is good, which is preferable. It can be said that the smaller the region surface average roughness (Sa) is, the more preferable it is. It can be said that the smaller the maximum protrusion height (P) is, the more preferable it is, but it may be 1 nm or more, or 3 nm or more.

The release film of the present invention preferably has a peel force of 0.5 mN/mm or more and 4.0 mN/mm or less when peeling the ceramic green sheet. More preferably, it is 0.8 mN/mm or more and 3.0 mN/mm or less. A peeling force of 0.5 mN/mm or more is preferable because the peeling force is too light to lift the ceramic green sheet during transportation. When the peel force is 4.0 mN/mm or less, the ceramic green sheet is not damaged during peeling, and thus there is no possibility of causing defects, which is preferable.

It is preferable that the release film of the present invention has higher solvent resistance because it suppresses corrosion of the release layer by an organic solvent such as toluene during ceramic sheet processing or electrode printing. Solvent resistance can be confirmed by evaluating the difference in the surface state of the release layer before and after the release film is immersed in an organic solvent. As the organic solvent, it is preferable to use toluene, which is used for general ceramic slurry and conductive paste, assuming ceramic green sheet processing and electrode printing. An example of a method for evaluating the surface state of the release layer is the evaluation based on the contact angle, and the smaller the change in the contact angle of the release layer surface before and after immersion in toluene, the better.

There is no particular limitation on the type of liquid used to measure the contact angle, but water, bromonaphthalene, ethylene glycol, etc. can be suitably used, but the difference in the surface state of the release layer can be seen more clearly. Most preferably, diiodomethane is used.

When diiodomethane was used as the liquid sample used to measure the contact angle, the diiodomethane contact angle θ1 _on the release layer surface and the contact angle θ on the release layer surface after the release film was immersed in toluene at room temperature for 5 minutes. The smaller the value of the difference in ₂ (θ ₁ −θ ₂ ) is, the better the solvent resistance of the surface of the release layer is. Specifically, the absolute value is preferably 3.0° or less, more preferably 2.0° or less, and most preferably 1.0° or less. When the angle is 3.0° or less, erosion of the release layer by an organic solvent during processing of the ceramic green sheet or printing of electrodes is suppressed, and there is no risk of an increase in the peeling force or loss of uniformity of peeling, which is preferable. The difference (θ ₁ - θ ₂ ) between the diiodomethane contact angle θ ₁ on the release layer surface and the contact angle θ ₂ on the release layer surface after immersing the release film in toluene at room temperature for 5 minutes is most preferably 0°. , the absolute value may be 0.05° or more, or 0.1° or more.

The release film of the present invention is preferably less curled. Less curling is preferable because there is no possibility that uniformity during coating and molding of the ceramic green sheet will deteriorate and that the film thickness of the ceramic green sheet will become non-uniform. Moreover, it is preferable because there is no possibility that the printing accuracy is lowered in the electrode printing process. Furthermore, during roll transport, the difference in tension of the release film is less likely to occur between the center and the ends of the film, which is preferable because there is no possibility of deteriorating appearance quality such as meandering or winding misalignment during transport.

(Method for forming release layer)

In the present invention, the method for forming the release layer is not particularly limited, and a coating liquid in which a composition containing a releasing resin or the like is dissolved or dispersed is spread by coating or the like on one surface of the polyester film as the base material. Then, after removing the solvent and the like by drying and drying by heating, a method of curing by irradiation with active energy rays or heat is used.

When curing using a photoradical initiator, the drying temperature for solvent drying is preferably 50° C. or higher and 100° C. or lower, and more preferably 60° C. or higher and 95° C. or lower. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less. When the temperature is 100° C. or less, the thermal load on the film is suppressed, the poor appearance due to heat shrinkage of the film is less likely to occur, and the possibility of unevenness in the thickness of the ceramic green sheet is small, which is preferable. When the temperature is 95° C. or lower, the thermal load on the film is further reduced, the film can be processed without impairing the flatness of the film, and the possibility of causing unevenness in the thickness of the ceramic green sheet is further reduced, which is particularly preferred. If the temperature is higher than 50°C, drying of the diluent solvent used in coating becomes insufficient, and the risk of process contamination or the like disappearing, which is preferable.

As the active energy ray used for reacting the radical-curable substance with the photoradical initiator, ultraviolet rays, electron beams, X-rays, and the like can be used, but ultraviolet rays are preferable because they are easy to use. The amount of ultraviolet rays to be irradiated is preferably 30 to 300 mJ/cm ² in terms of integrated light amount, more preferably 30 to 200 mJ/cm ² . A density of 30 mJ/cm ² or more is preferable because curing of the resin proceeds sufficiently. It is preferable to make the release film 300 mJ/cm ² or less because the processing speed can be improved and the release film can be produced economically.

The atmosphere in which the active energy ray is applied may be an atmosphere of an inert gas such as nitrogen or argon, but is preferably in general air. In the present invention, by using a thiol group-containing compound, it is possible to obtain a release layer that exhibits excellent curability on the surface of the release layer even when irradiated in the air, and that exhibits excellent wettability with the ceramic slurry. In addition, it is superior in terms of processing cost to performing in an inert gas atmosphere, and is also preferable from an economic point of view.

In the present invention, the surface tension of the coating liquid when the release layer is applied is not particularly limited, but is preferably 30 mN/m or less. By adjusting the surface tension as described above, the wettability after coating can be improved, and the unevenness of the coating film surface after drying can be reduced.

In the present invention, the coating liquid for coating the release coating layer is not particularly limited, but it is preferable to add a solvent having a boiling point of 90° C. or higher. By adding a solvent having a boiling point of 90° C. or higher, bumping during drying can be prevented, the coating film can be leveled, and the smoothness of the coating film surface after drying can be improved. As for the amount to be added, it is preferable to add about 10 to 80% by mass based on the entire coating liquid.

As a method for applying the coating liquid, any known coating method can be applied, for example, a roll coating method such as a gravure coating method or a reverse coating method, a bar coating method such as a wire bar method, a die coating method, a spray coating method, and an air knife. A conventionally known method such as a coating method can be used.

(ceramic green sheet and ceramic capacitor)
Generally, a multilayer ceramic capacitor has a rectangular parallelepiped ceramic body. Inside the ceramic body, first internal electrodes and second internal electrodes are alternately provided along the thickness direction. The first internal electrode is exposed on the first end face of the ceramic body. A first external electrode is provided on the first end surface. The first internal electrode is electrically connected to the first external electrode at the first end surface. The second internal electrode is exposed on the second end face of the ceramic body. A second external electrode is provided on the second end surface. The second internal electrode is electrically connected to the second external electrode at the second end surface.

The release film for producing ceramic green sheets of the present invention is used for producing such a laminated ceramic capacitor. For example, it is manufactured as follows. First, using the release film of the present invention as a carrier film, a ceramic slurry for forming a ceramic body is applied and dried. As for the thickness of the ceramic green sheet, an ultra-thin product with a thickness of 0.2 to 1.0 μm is required. A conductive layer for forming the first or second internal electrode is printed on the coated and dried ceramic green sheet. Ceramic green sheets, ceramic green sheets printed with conductive layers for forming first internal electrodes, and ceramic green sheets printed with conductive layers for forming second internal electrodes are appropriately laminated and pressed. Thus, a mother laminate is obtained. The mother laminate is divided into a plurality of pieces to produce raw ceramic bodies. A ceramic body is obtained by firing a raw ceramic body. After that, the multilayer ceramic capacitor can be completed by forming the first and second external electrodes.

EXAMPLES The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. The characteristic values used in the present invention were evaluated using the following methods.

(Intrinsic viscosity of polyester resin (dl/g))
Measured at 30° C. using a mixed solvent of phenol (60% by mass) and 1,1,2,2-tetrachloroethane (40% by mass) as a solvent in accordance with JIS K 7367-5.

(Base film thickness)
Using a millitron (electronic microindicator), 4 pieces of 5 cm square samples were cut out from 4 arbitrary points of the film to be measured, 5 points each (20 points in total) were measured, and the average value was taken as the thickness.

(Release layer thickness)
The cut release film was embedded in a resin and cut into ultrathin slices using an ultramicrotome. Then, using a JEOL JEM2100 transmission electron microscope, direct observation was performed at a magnification of 20,000, and the film thickness of the release layer was measured from the observed TEM image.

(Area surface roughness Sa, maximum protrusion height P)
These are values measured under the following conditions using a non-contact surface profile measuring system (VertScan R550H-M100 manufactured by Ryoka Systems Co., Ltd.). The area surface average roughness (Sa) was the average value of 5 measurements, and the maximum protrusion height (P) was measured 7 times, and the maximum value of the 5 measurements excluding the maximum and minimum values was used.
(Measurement condition)
・Measurement mode: WAVE mode ・Objective lens: 10x ・0.5×Tube lens ・Measurement area: 936 μm×702 μm
(analysis conditions)
・Surface correction: Quaternary correction ・Interpolation processing: Complete interpolation

(Evaluation of pinholes in ceramic green sheets)
A composition composed of the following materials was stirred and mixed, and dispersed with zirconia beads having a diameter of 0.5 mm for 30 minutes using a bead mill to obtain a ceramic slurry.
Toluene 76.3 parts by mass Ethanol 76.3 parts by mass Barium titanate (HPBT-1 manufactured by Fuji Titanium Co., Ltd.) 35.0 parts by mass Polyvinyl butyral (Eslec (registered trademark) BM-S manufactured by Sekisui Chemical Co., Ltd.) 3.5 parts by mass DOP (dioctyl phthalate) 1.8 parts by mass Next, the slurry after drying was applied to the release surface of the obtained release film sample using an applicator so that the thickness was 0.8 μm, and dried at 90° C. for 2 minutes. After that, the release film was peeled off to obtain a ceramic green sheet. In the central region of the obtained ceramic green sheet in the film width direction, light was applied from the opposite side of the ceramic slurry-coated surface in a range of 25 cm ² , and the occurrence of pinholes that can be seen through light transmission was observed. judged visually. The measurement was performed 5 times and the average value was adopted.
◎: No pinholes ○: Almost no pinholes (reference: 2 or less pinholes per measurement area)
△: Pinholes occur (reference: 3 or more pinholes per measurement area, 5 or less)
×: Many pinholes are generated

(Evaluation of ceramic slurry coatability)
A composition composed of the following materials was stirred and mixed, and dispersed with zirconia beads having a diameter of 0.5 mm for 30 minutes using a bead mill to obtain a ceramic slurry.
Toluene 76.3 parts by mass Ethanol 76.3 parts by mass Barium titanate (HPBT-1 manufactured by Fuji Titanium Co., Ltd.) 35.0 parts by mass Polyvinyl butyral (S-lec BM-S manufactured by Sekisui Chemical Co., Ltd.) 3.5 parts by mass DOP (phthalic acid Dioctyl) 1.8 parts by mass Then, the release surface of the obtained release film sample was coated with an applicator so that the slurry after drying became 0.8 μm, dried at 90 ° C. for 2 minutes, and then dried according to the following criteria. to evaluate the coatability.
◯: Coating was completed on the entire surface without cissing or the like.
Δ: Slight repellency at the coating edge, but almost the entire surface is coated.
x: Repelling occurs even in areas other than the coating edge, and the entire surface cannot be coated.

(Peelability evaluation of ceramic green sheet)
A composition consisting of the following materials was stirred and mixed, and dispersed with zirconia beads having a diameter of 0.5 mm using a bead mill for 60 minutes to obtain a ceramic slurry.
Toluene 38.3 parts by mass Ethanol 38.3 parts by mass Barium titanate (HPBT-1 manufactured by Fuji Titanium Co., Ltd.) 64.8 parts by mass Polyvinyl butyral 6.5 parts by mass (Eslec (registered trademark) BM-S manufactured by Sekisui Chemical Co., Ltd. )
DOP (dioctyl phthalate) 3.3 parts by mass Next, the release surface of the release film sample was coated with an applicator so that the dried ceramic green sheet had a thickness of 10 μm, and dried at 90° C. for 2 minutes. A sheet was cast on a release film. The release film with the ceramic green sheet thus obtained was cut into a piece having a width of 30 mm and a length of 80 mm to obtain a sample for peel strength measurement. After static elimination using a static eliminator (manufactured by Keyence Corporation, SJ-F020), using a peel tester (manufactured by Kyowa Interface Science Co., Ltd., VPA-3), a peeling angle of 90 degrees, a peeling temperature of 25 ° C., a peeling speed of 10 m / It peeled off at min. As for the peeling direction, a double-sided adhesive tape (manufactured by Nitto Denko Co., Ltd., No. 535A) was attached to the SUS plate attached to the peel tester, and the ceramic green sheet side was adhered to the double-sided tape on the release film. was fixed and peeled off by pulling the release film side. Among the obtained measured values, the average value of the peel force at the peel distance of 20 mm to 70 mm was calculated, and the value was defined as the peel force. The measurement was carried out a total of 5 times, and the average value of the peel strength was used for evaluation. Judgment was made according to the following criteria from the numerical value of the obtained peel strength.
⊚: The peeling force was 2.0 mN/mm or less, which was very light.
◯: The peel force was greater than 2.0 mN/mm, and peeled with a relatively light force of 3.0 mN/mm or less.
Δ: The peeling force was greater than 3.0 mN/mm and could be peeled off with a light force of 4.0 mN/mm or less.
x: A peeling force greater than 4.0 mN/mm was required.

(Curl evaluation of release film)
A release film sample was cut into a size of 10 cm×10 cm, and heat-treated in a hot air oven at 90° C. for 1 minute without applying tension to the release film. After that, it was taken out of the oven and cooled to room temperature, and then the release film sample was placed on a glass plate so that the release surface faced up, and the height of the part floating above the glass plate was measured. At this time, the height of the portion that was the largest floating from the glass plate was used as the measured value. Curl property was evaluated according to the following criteria.
⊚: Curl of 1 mm or less, almost no curl O: Curl of more than 1 mm and 2 mm or less, slightly curled.
Δ: Curling was greater than 2 mm and 4 mm or less, and curling was observed.
x: Curl was greater than 4 mm.

(contact angle)
Diiodomethane (droplet amount A droplet of 0.9 μL) was prepared and its contact angle was measured. For the contact angle, the contact angle 30 seconds after dropping on the release film was adopted, and the average value of the values measured five times was adopted.

(Contact angle after immersion in toluene)
A release film used for measurement was cut into a size of 5 cm×5 cm, and immersed in a glass tray containing 30 mL of toluene at a liquid temperature of 25° C. for 5 minutes with the release surface facing downward. The immersed release film was taken out, and air-dried for 15 minutes with the release surface facing up, and then vacuum-dried overnight at 25°C. The release film thus obtained after immersion in toluene was measured by the same method as the method for measuring the contact angle.

(Evaluation of contact angle change)
When the initial diiodomethane contact angle on the release layer surface before immersion in toluene measured by the above method is θ ₁ , and the diiodomethane contact angle on the release layer surface after immersion in toluene is θ ₂ , θ ₁ - θ ₂ The absolute value was taken as the change in contact angle before and after immersion in toluene. The contact angle change was evaluated according to the following criteria.
◎: |θ ₁ −θ ₂ | < 1.0°
○: 1.0° ≤ |θ ₁ - θ ₂ | < 2.0°
△: 2.0° ≤ |θ ₁ - θ ₂ | ≤ 3.0°
×: |θ ₁ -θ ₂ | > 3.0°

(Preparation of polyethylene terephthalate pellets (PET (I)))
As the esterification reactor, a continuous esterification reactor comprising a three-stage complete mixing tank having a stirrer, a partial condenser, a raw material inlet and a product outlet was used. TPA (terephthalic acid) was adjusted to 2 tons/hour, EG (ethylene glycol) was adjusted to 2 mol per 1 mol of TPA, and antimony trioxide was adjusted to give an amount of Sb atoms of 160 ppm relative to the produced PET. It was continuously supplied to the first esterification reactor of the reaction apparatus and reacted at 255° C. for an average residence time of 4 hours under normal pressure. Next, the reaction product in the first esterification reaction can is continuously taken out of the system and supplied to the second esterification reaction can, and distilled from the first esterification reaction can into the second esterification reaction can. 8% by mass of EG is supplied to the produced PET, and an EG solution containing magnesium acetate tetrahydrate in an amount such that the Mg atom is 65 ppm relative to the produced PET, and the P atom is 40 ppm relative to the produced PET. An EG solution containing a certain amount of TMPA (trimethyl phosphate) was added and reacted at normal pressure at 260° C. for an average residence time of 1 hour. Next, the reaction product in the second esterification reactor was continuously taken out of the system, supplied to the third esterification reactor, and subjected to 39 MPa (400 kg/cm ² ) using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.). 0.2% by mass of porous colloidal silica having an average particle size of 0.9 μm, which has been subjected to dispersion treatment for an average of 5 passes at a pressure of , and 1% by mass of ammonium salt of polyacrylic acid per calcium carbonate. While adding 0.4% by mass of synthetic calcium carbonate with a diameter of 0.6 μm as a 10% EG slurry, the mixture was reacted at normal pressure at 260° C. for an average residence time of 0.5 hours. The esterification reaction product produced in the third esterification reaction vessel was continuously supplied to a three-stage continuous polycondensation reactor for polycondensation to sinter stainless steel fibers having a 95% cut diameter of 20 μm. After filtration with a filter, ultrafiltration was performed, the product was extruded into water, and after cooling, it was cut into chips to obtain PET chips having an intrinsic viscosity of 0.60 dl/g (hereinafter abbreviated as PET (I)). . The lubricant content in the PET chip was 0.6% by mass.

(Preparation of polyethylene terephthalate pellets (PET (II)))
On the other hand, in the production of the PET chip, a PET chip containing no inorganic particles such as calcium carbonate, silica, etc. and having an intrinsic viscosity of 0.62 dl/g was obtained (hereinafter abbreviated as PET (II)).

(Production of laminated film X1)
After drying these PET chips, they were melted at 285° C. and melted at 290° C. by a separate melt extruder extruder to filter sintered stainless steel fibers with a 95% cut diameter of 15 μm and Two-stage filtration of sintered stainless steel particles of 15 μm is performed, and they are combined in the feed block to form PET (I) on the surface layer B (anti-releasing surface side layer) and PET (II) on the surface. Laminated so as to form layer A (releasing surface side layer), extruded (cast) into a sheet at a speed of 45 m / min, electrostatically adhered on a casting drum at 30 ° C. by an electrostatic adhesion method, cooled, An unstretched polyethylene terephthalate sheet having an intrinsic viscosity of 0.59 dl/g was obtained. The layer ratio was adjusted so that PET(I)/PET(II)=60%/40% by calculation of the discharge amount of each extruder. Then, the unstretched sheet was heated with an infrared heater and then stretched 3.5 times in the machine direction at a roll temperature of 80° C. due to the speed difference between the rolls. After that, it was led to a tenter and stretched 4.2 times in the transverse direction at 140°C. It was then heat treated at 210° C. in a heat setting zone. After that, a 2.3% relaxation treatment was applied in the transverse direction at 170° C. to obtain a biaxially stretched polyethylene terephthalate film X1 having a thickness of 25 μm. The Sa of the surface layer A of the obtained film X1 was 2 nm, and the Sa of the surface layer B was 29 nm.

(Production of laminated film X2)
A biaxially stretched polyethylene terephthalate film X2 having a thickness of 22 μm was obtained by adjusting the thickness by changing the casting speed without changing the same layer structure and stretching conditions as those of the laminated film X1. The Sa of the surface layer A of the obtained film X2 was 3 nm, and the Sa of the surface layer B was 29 nm.

(Manufacturing method of laminated film X3)
As the laminated film X3, E5101 (Toyobo Ester (registered trademark) film, manufactured by Toyobo Co., Ltd.) having a thickness of 25 μm was used. E5101 has a structure in which inorganic particles are contained in the film. The Sa of the surface layer A of the laminated film X3 was 24 nm, and the Sa of the surface layer B was 24 nm.

(Example 1)
Coating solution 1 having the composition shown below was coated on surface layer A of laminated film X1 using a wire bar so that the thickness of the release layer after drying was 0.4 μm, and dried at 90° C. for 15 seconds. After that, ultraviolet light (LC6B, H bulb, manufactured by Heraeus) was irradiated in the atmosphere with an integrated light amount of 70 mJ/cm ² to obtain a release film for producing an ultra-thin ceramic green sheet. A ceramic slurry was applied to the obtained release film, and the surface roughness of the release layer, releasability, pinholes, coating properties, curling, and solvent resistance were evaluated, and good evaluation results were obtained.
Methyl ethyl ketone 22.40 parts by mass Isopropyl alcohol 67.20 parts by mass Radical curing substance (a): 10-functional urethane acrylate 8.50 parts by mass (product name: Shiko (registered trademark) UV-1700B, manufactured by Nippon Synthetic Chemical Co., Ltd., solid min 100% by mass)
Thiol group-containing compound (b): 1.00 parts by mass of tetrafunctional thiol group-containing compound
(Product name: Karenz MT (registered trademark) PE1, manufactured by Showa Denko K.K., solid content 100% by mass)
Release agent (c): acryloyl group-containing acrylic silicone 0.50 parts by mass (product name: GL-04R, manufactured by Kyoeisha Chemical Co., Ltd., solid content 20% by mass)
Radical initiator (d): 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Example 2)
A separator for producing an ultrathin ceramic green sheet was prepared in the same manner as in Example 1, except that the radical curable substance (a) was changed to a 9-functional urethane acrylate (Shiko (registered trademark) UV-7620EA, manufactured by Nippon Synthetic Chemical Co., Ltd.). A mold film was obtained.

(Example 3)
A separator for producing an ultrathin ceramic green sheet was prepared in the same manner as in Example 1, except that the radical curable substance (a) was changed to a hexafunctional urethane acrylate (Shiko (registered trademark) UV-7600B, manufactured by Nippon Synthetic Chemical Co., Ltd.). A mold film was obtained.

(Example 4)
A separator for producing an ultrathin ceramic green sheet was prepared in the same manner as in Example 1, except that the radical curable substance (a) was changed to a pentafunctional urethane acrylate (Shiko (registered trademark) UV-7650B, manufactured by Nippon Synthetic Chemical Co., Ltd.). A mold film was obtained.

(Example 5)
A separator for producing an ultrathin ceramic green sheet was prepared in the same manner as in Example 1, except that the radical curable substance (a) was changed to a trifunctional urethane acrylate (Shiko (registered trademark) UV-7550B, manufactured by Nippon Synthetic Chemical Co., Ltd.). A mold film was obtained.

(Example 6)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the radical curable substance (a) was changed to a hexafunctional acrylate (A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd.). .

(Example 7)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the radical curable substance (a) was changed to a tetrafunctional acrylate (A-TMMT, manufactured by Shin-Nakamura Chemical Co., Ltd.). .

(Example 8)
A release film for producing an ultra-thin ceramic green sheet was prepared in the same manner as in Example 1, except that the radical-curable substance (a) was changed to a dendrimer-type polyfunctional acrylate (SIRIUS-501, manufactured by Osaka Organic Chemical Industry Co., Ltd.). Obtained.

(Example 9)
A release mold for producing an ultra-thin ceramic green sheet was prepared in the same manner as in Example 1, except that the radical-curable substance (a) was changed to a trifunctional allyl compound (Taiku (registered trademark) triisocyanurate, manufactured by Nippon Kasei Co., Ltd.). got the film.

(Examples 10 and 11)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1, except that the content of the thiol group-containing compound (b) was changed to the amount shown in Table 1.

(Example 12)
A release film for producing an ultrathin ceramic green sheet was prepared in the same manner as in Example 1, except that the thiol group-containing compound (b) was changed to a trifunctional thiol (Karenzu MT (registered trademark) NR1, manufactured by Showa Denko KK). Obtained.

(Example 13)
A release film for producing an ultrathin ceramic green sheet was prepared in the same manner as in Example 1, except that the thiol group-containing compound (b) was changed to a bifunctional thiol (Karenzu MT (registered trademark) BD1, manufactured by Showa Denko KK). Obtained.

(Example 14)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the coating solution was changed to the composition shown below.
Methyl ethyl ketone 22.50 parts by mass Isopropyl alcohol 67.50 parts by mass Radical curing substance (a): Hexafunctional acrylate 8.50 parts by mass (product name: A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd., solid content 100% by mass)
Thiol group-containing compound (b): 1.00 parts by mass of tetrafunctional thiol group-containing compound
(Product name: Karenz MT (registered trademark) PE1, manufactured by Showa Denko K.K., solid content 100% by mass)
Release agent (c):
Acryloyl group-containing polyether-modified polydimethylsiloxane 0.10 parts by mass (product name: BYK UV-3500, manufactured by Big Chemie Japan, solid content 100% by mass)
Radical initiator (d): 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Example 15)
Ultra-thin ceramic green sheets were produced in the same manner as in Example 1, except that the release agent (c) was changed to a fluorine-based release agent (product name: Megafac (registered trademark) RS-75, manufactured by DIC Corporation). A release film for

(Example 16)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the release agent (c) was changed to stearyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.).

(Example 17)
Ultra-thin layer ceramic green sheets were produced in the same manner as in Example 1, except that the release agent (c) was changed to acryloyl group-containing polyether-modified polydimethylsiloxane (product name: BYK-UV3500, manufactured by Big Chemie Japan). A release film for

(Example 18)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the release layer was coated so as to have a thickness of 1.0 μm.

(Example 19)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the release layer was coated so as to have a thickness of 0.2 μm.

(Example 20)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the release layer was coated so as to have a thickness of 0.05 μm.

(Example 21)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the base film was changed to X2.

(Example 22)
A release film for producing an ultrathin ceramic green sheet was obtained in the same manner as in Example 1, except that the base film was changed to X3.

(Comparative example 1)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the coating solution was changed to the composition shown below.
Methyl ethyl ketone 22.40 parts by mass Isopropyl alcohol 67.20 parts by mass Radical curing substance (a): 10-functional urethane acrylate 9.50 parts by mass (product name: Shiko (registered trademark) UV-1700B, Nippon Synthetic Chemical Co., Ltd., solid min 100%)
Release agent (c): acryloyl group-containing acrylic silicone 0.50 parts by mass (product name: GL-04R, manufactured by Kyoeisha Chemical Co., Ltd., solid content 20% by mass)
Radical initiator (d): 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Comparative example 2)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the coating solution was changed to the composition shown below.
Methyl ethyl ketone 22.50 parts by mass Isopropyl alcohol 67.50 parts by mass Radical curing substance (a) 10-functional urethane acrylate 8.60 parts by mass (product name: Shiko (registered trademark) UV1700B, manufactured by Nippon Synthetic Chemical Co., Ltd., solid content 100% )
Thiol group-containing compound (b): 1.00 parts by mass of tetrafunctional thiol group-containing compound
(Product name: Karenz MT (registered trademark) PE1, manufactured by Showa Denko K.K., solid content 100% by mass)
Radical initiator (d): 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Comparative Example 3)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Comparative Example 1, except that the release layer was coated so as to have a film thickness of 1.0 μm.

(Comparative Example 4)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Comparative Example 1, except that the release layer was coated so as to have a film thickness of 0.05 μm.

(Comparative Example 5)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that the composition of the coating solution was changed to that shown below.
Methyl ethyl ketone 22.50 parts by mass Isopropyl alcohol 67.50 parts by mass Radical curing substance (a) Hexafunctional acrylate 9.50 parts by mass (product name: A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd., solid content 100% by mass)
Release agent (c):
Acryloyl group-containing polyether-modified polydimethylsiloxane 0.10 parts by mass (product name: BYK UV-3500, manufactured by Big Chemie Japan, solid content 100% by mass)
Radical initiator (d): 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Comparative Example 6)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Comparative Example 5, except that the release layer was coated so as to have a film thickness of 1.0 μm.

(Comparative Example 7)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Example 1, except that a coating liquid having the following composition was used.
Methyl ethyl ketone 22.40 parts by mass Isopropyl alcohol 67.20 parts by mass Radical curable substance (a): Triallyl isocyanurate 9.50 parts by mass (product name: Tyke (registered trademark), manufactured by Nippon Kasei Chemical Co., Ltd., solid content 100%)
Release agent (c): acryloyl group-containing acrylic silicone 0.50 parts by mass (product name: GL-04R, manufactured by Kyoeisha Chemical Co., Ltd., solid content 20% by mass)
Radical initiator (d): 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one 0.40 parts by mass (Product name: Omnirad 127, manufactured by IGM Resins, solid content 100% by mass)

(Comparative Example 8)
A release film for producing an ultra-thin ceramic green sheet was obtained in the same manner as in Comparative Example 1, except that the film was cured by irradiation with ultraviolet rays in a nitrogen atmosphere.

The release film for producing a ceramic green sheet of the present invention has a highly smooth surface of the release layer, a high crosslinking density of the release layer, and excellent solvent resistance. Therefore, the release layer is not eroded during ceramic green sheet processing or electrode printing, and even when an ultra-thin ceramic green sheet with a thickness of 1 μm or less is peeled off, the peeling force is low and uniform. It is possible to mold a ceramic green sheet with less In addition, since the release film is less curled, it can be used without causing unevenness in the thickness of the ceramic green sheet or deterioration in electrode printing accuracy.

Claims (12)

A release film having a release layer on at least one side of a polyester film,
Radical-curable substance (a), thiol group-containing compound (b), release agent (c), wherein the release layer has one or more radical-curable functional groups selected from (meth)acryloyl groups and alkenyl groups , obtained by curing a composition containing a radical initiator (d) ,
The curl amount measured under the condition that the release film is heat-treated at 90° C. for 1 minute under no tension is 2.0 mm or less.
Release film for manufacturing ceramic green sheets. 2. The release film for producing a ceramic green sheet according to claim 1, wherein the thiol group-containing compound (b) does not have a radical-curable functional group selected from (meth)acryloyl groups and alkenyl groups. 3. The release film for producing a ceramic green sheet according to claim 1, wherein the thiol group-containing compound (b) is a compound having two or more thiol groups in one molecule. The difference (θ ₁ - θ ₂ ) between the diiodomethane contact angle θ ₁ on the release layer surface and the diiodomethane contact angle θ ₂ on the release layer surface after the release film is immersed in toluene is 3.0° or less as an absolute value. A release film for producing a ceramic green sheet according to any one of claims 1 to 3. The release film for producing a ceramic green sheet according to any one of claims 1 to 4, wherein the release agent (c) is a compound containing a silicone component. 5. The release film for producing a ceramic green sheet according to any one of claims 1 to 4, wherein the release agent (c) is a compound containing a fluorine atom in its molecule. The content of the thiol group-containing compound (b) is 1 to 30% by mass with respect to the total mass of the composition forming the release layer. mold film. The polyester film has a surface layer A that does not substantially contain inorganic particles and an opposite surface layer B that contains inorganic particles, a release layer is provided on the surface layer A, and the surface layer The ceramic green sheet production according to any one of claims 1 to 7, wherein the inorganic particles contained in B are silica particles and/or calcium carbonate particles, and the total amount of inorganic particles is contained in the surface layer B at 5000 to 15000 ppm. release film. The release film for producing a ceramic green sheet according to any one of claims 1 to 8, wherein the thickness of the release layer is in the range of 0.01 µm or more and 0.5 µm or less. (Meth) a radical-curable substance having one or more radical-curable functional groups selected from acryloyl groups and alkenyl groups (a), a thiol group-containing compound (b), a release agent (c), a radical initiator ( 10. The method for producing a release film for producing a ceramic green sheet according to any one of claims 1 to 9, wherein the release layer is formed by curing the composition containing d) in the atmosphere. A method for producing a ceramic green sheet having a thickness of 0.2 μm to 1.0 μm, wherein the release film for producing a ceramic green sheet according to any one of claims 1 to 9 is used. A method for manufacturing a ceramic capacitor employing the method for manufacturing a ceramic green sheet according to claim 11.