Release film and application of the same

Abstract

To provide a release film which is excellent in winding property and unwinding property without sticking a thin ceramic green sheet onto a rear face (mold release opposite-side surface), even when the ceramic green sheet is wound in a stacked state.SOLUTION: A release film has a resin layer A on one surface of a polyester film and a resin layer B on a surface opposite to the one surface, wherein the resin layer A contains a non-silicone-based release agent, the resin layer B and a ceramic green sheet are pressed, and a charging amount to the ceramic green sheet of the resin layer B in peeling under the following measurement condition is 10 kV or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a release film, a release film with a ceramic green sheet, and a method for manufacturing a ceramic green sheet.

Background Art

[0002] Polyester films typified by polyethylene terephthalate films and polyethylene naphthalate films have excellent properties such as mechanical properties, dimensional stability, flatness, heat resistance, chemical resistance, and optical properties, and are used in various applications because of their excellent cost performance.

[0003] In addition, polyester films are suitably used in various applications such as release films for forming green sheets of multilayer ceramic capacitors, base materials for interlayer insulating resin release, and base materials for dry film resists by utilizing the smoothness of the film surface.

[0004] Conventionally, a release film having a release layer containing a silicone-based release agent on one surface of a polyester film has been widely used for forming green sheets (Patent Document 1). In addition, in order to cope with applications that extremely dislike the mixing of silicon (Si) elements, such as in the semiconductor field, a release film having a release layer using a non-silicone-based release agent has been proposed (Patent Documents 2 and 3). In these documents, in any case, the problem is to improve the peelability of the release layer from the ceramic green sheet at normal temperature or after heat treatment.

[0005] In recent years, with the further increase in the capacitance of multilayer ceramic capacitors, the thickness of ceramic green sheets has also been increasingly tending to be thinned. In particular, when forming a ceramic green sheet with a thickness (after drying) of 2 μm or less, simply thinning the sheet thickness alone makes the ceramic green sheet itself brittle and easily cracked. Therefore, in order to ensure handleability, measures have been taken to impart appropriate flexibility to the ceramic green sheet itself by adjusting the composition of the ceramic slurry.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the case where a flexible thin-film ceramic green sheet is formed using a conventional release film, when the release film is wound up in a roll state with the thin-film ceramic green sheet laminated, and the release film is unwound again, the present inventors have found that a phenomenon occurs in which the ceramic green sheet does not have a release layer or the ceramic green sheet adheres to the film surface on the anti-release surface side.

[0008]

Means for Solving the Problems

[0009] In view of the above circumstances, the present inventors have conducted intensive studies and as a result, have found that the above problems can be easily solved by using a release film having the following configuration, and have completed the present invention. That is, the present invention provides the following [1] to

[23] .

[0010] [1] A release film having a resin layer A on one side of a polyester film and a resin layer B on the opposite side, wherein the resin layer A contains a non-silicone release agent, and the amount of charge generated during peeling under the following measurement conditions when the resin layer B is peeled from a ceramic green sheet is 10 kV or less; (Measurement conditions) A ceramic green sheet is formed on the resin layer A from a composition containing 39.84 parts by mass of toluene, 39.84 parts by mass of ethanol, 17.65 parts by mass of barium titanate, 1.77 parts by mass of polyvinyl butyral, and 0.90 parts by mass of dioctyl phthalate, and having a thickness of 1.0 μm. After treating the ceramic green sheet and the resin layer B under a pressing pressure (8.2 MPa) for 5 hours, the amount of static electricity when the ceramic green sheet is peeled from the resin layer B is measured; the peeling angle when the ceramic green sheet is peeled is 90 degrees, and the peeling speed is 4 cm / second. [2] The release film according to [1], wherein the resin layer B contains a (C) antistatic agent. [3] The release film according to [2], wherein the (C) antistatic agent is an ion conductive polymer compound. [4] The release film according to [2] or [3], wherein the (C) antistatic agent is at least one selected from (a1) a polymer in which a compound composed of thiophene or a thiophene derivative is doped with another anionic compound, and (a2) a polymer in which a compound composed of thiophene or a thiophene derivative has an anionic group and is self-doped. [5] The release film according to any one of [1] to [4], wherein the resin layer B contains an (A) non-silicone release agent. [6] The release film according to [5], wherein the (A) non-silicone release agent is at least one selected from wax and a long-chain alkyl group-containing compound. [7] The release film according to any one of [1] to [6], wherein the resin layer B contains a (B) binder resin. [8] The release film according to [7], wherein the (B) binder resin is at least one selected from a (meth)acrylic resin and polyvinyl alcohol. [9] The release film according to any one of [1] to [8], wherein the resin layer B contains a (D) crosslinking agent.

[10] The release film according to [9], wherein the (D) crosslinking agent is at least one selected from a melamine compound and an oxazoline compound.

[11] The release film according to any one of [1] to

[10] , wherein the non-silicone release agent contained in the resin layer A contains one or more selected from wax and a long-chain alkyl group-containing compound.

[12] The release film according to any one of [1] to

[11] , wherein the polyester film has a three-layer structure.

[13] The release film according to

[12] , wherein the polyester film has a three-layer structure of three types.

[14] The release film according to any one of [1] to

[13] , wherein the arithmetic mean height (Sa) of the resin layer A surface in the release film is 5 nm or less.

[15] The release film according to any one of [1] to

[14] , wherein the thickness of the release film is 9 to 50 μm.

[16] The release film according to any one of [1] to

[15] , wherein the coefficient of kinetic friction between the resin layer B surface and the resin layer A surface in the release film is 0.20 or less.

[17] The release film according to any one of [1] to

[16] , which is used as a support for a ceramic green sheet in the manufacturing process of a multilayer ceramic capacitor.

[18] The release film according to any one of [1] to

[17] , which is used as a support for a ceramic green sheet in the manufacturing process of an automotive ceramic capacitor.

[19] A release film with a ceramic green sheet, in which a ceramic green sheet is laminated on the resin layer A of the release film according to any one of [1] to

[18] .

[20] The release film with a ceramic green sheet according to

[19] , wherein the thickness (after drying) of the ceramic green sheet is 2 μm or less.

[21] The release film with a ceramic green sheet according to

[19] or

[20] , which is used in the manufacturing process of a multilayer ceramic capacitor.

[22] A release film with a ceramic green sheet as described in any of

[19] to

[21] , which is used in the manufacturing process of automotive ceramic capacitors.

[23] A method for manufacturing a ceramic green sheet, comprising a step of coating a ceramic slurry containing a ceramic component on at least one surface side of the release film as described in any of [1] to

[18] .

Advantages of the Invention

[0011] According to the present invention, even when a thin film ceramic green sheet with a thickness (after drying) of 2 μm or less is wound up in a laminated state, a release film can be provided in which the ceramic green sheet does not stick to the back surface (anti-release surface) and which is excellent in winding property and unwinding property.

Brief Description of the Drawings

[0012]

Figure 1

Embodiments for Carrying Out the Invention

[0013] Next, an example of an embodiment of the present invention will be described. However, the present invention is not limited to the embodiments described below, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In this specification, when expressed as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it means "X or more and Y or less", and also includes the meaning of "preferably larger than X" or "preferably smaller than Y". Further, when expressed as "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), it also includes the intention of "preferably larger than X" or "preferably less than Y". Note that the "film" and "sheet" used in the following description are not clearly distinguished, and when referred to as "film", it includes "sheet", and when referred to as "sheet", it includes "film".

[0014] <Release Film> The release film of the present invention (hereinafter, also referred to as "this release film") includes resin layers (hereinafter, also referred to as "this resin layer") formed on both sides of a polyester film (hereinafter, also referred to as "this polyester film") using a resin composition. Specifically, the structure of this release film is such that it has a resin layer A on one side of the polyester film and a resin layer B on the opposite side.

[0015] As shown in FIG. 1, the release film 100 of this embodiment has a resin layer A (surface layer A) 20 on one surface side of a polyester film (intermediate layer B) 10 and a resin layer B (surface layer C) 30 on the other surface side. In this embodiment, the polyester film 10 and each resin layer (20, 30) may be laminated so as to be in direct contact, or another layer may be provided between the polyester film 10 and the resin layers (20, 30).

[0016] In this embodiment, the resin layer A contains a non-silicone-based release agent. Also, the charge amount during peeling under the following measurement conditions of the resin layer B with respect to the ceramic green sheet is 10 kV or less. When measuring, under the following conditions, a ceramic green sheet is formed on the resin layer A of the release film, and after performing a press treatment in a state where the resin layer B of the release film is in contact with the formed ceramic green sheet, the charge amount is measured. (Measurement conditions) A ceramic green sheet having a thickness of 1.0 μm and formed from a composition containing 39.84 parts by mass of toluene, 39.84 parts by mass of ethanol, 17.65 parts by mass of barium titanate, 1.77 parts by mass of polyvinyl butyral, and 0.90 parts by mass of dioctyl phthalate is formed on the resin layer A, and after treating the ceramic green sheet and the resin layer B at a press pressure (8.2 MPa) for 5 hours, the amount of static electricity when peeling the ceramic green sheet from the resin layer B is measured; the peeling angle when peeling the ceramic green sheet is 90 degrees, and the peeling speed is 4 cm / second.

[0017] <<Polyester film>> This polyester film serves as the base material of this release film. This polyester film may have a single-layer structure or a multi-layer structure. When this polyester film has a multi-layer structure, it may have a two-layer structure, a three-layer structure, etc., and may have four or more layers as long as it does not deviate from the gist of the present invention, and the number of layers is not particularly limited. Incidentally, when this polyester film has a multi-layer structure of two or more layers, it is particularly preferable that it has a configuration of two types in three layers or three types in three layers. In particular, this polyester film preferably has a three-layer configuration. In this case, this polyester film preferably has a layer configuration of surface layer A / intermediate layer B / surface layer C.

[0018] Also, this polyester film may be an unstretched film (sheet) or a stretched film. Among them, this polyester film is preferably a stretched film stretched in a uniaxial direction or a biaxial direction. Among them, it is more preferable that it is a biaxially stretched film in terms of excellent balance of mechanical properties and flatness.

[0019] (Polyester) The polyester that is the raw material of this polyester film may be a homopolyester or a copolyester. When this polyester film is made of a homopolyester, the homopolyester is preferably obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Representative homopolyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), etc., and polyethylene terephthalate is preferable.

[0020] On the one hand, the copolyester is preferably a polycondensation polymer of, for example, a dicarboxylic acid component and a glycol component. Examples of the dicarboxylic acid component include one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (e.g., p-oxybenzoic acid, etc.). Examples of the glycol component include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, and neopentyl glycol. The copolyester preferably contains terephthalic acid as the dicarboxylic acid component and ethylene glycol as the glycol component, and further preferably contains a copolymerization component of at least one dicarboxylic acid component and / or glycol component. The content of the copolymerization component is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total moles of all the constituent units constituting the polyester.

[0021] The copolyester may contain a structural unit derived from a bifunctional compound other than the above-mentioned dicarboxylic acid component and glycol component. The structural unit derived from a bifunctional compound other than the above-mentioned dicarboxylic acid component and glycol component is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total moles of all the constituent units constituting the polyester. Examples of the bifunctional compound include various hydroxycarboxylic acids, aromatic diols, and the like.

[0022] The content of terephthalic acid in all the dicarboxylic acid components in the polyester constituting the present polyester film is preferably 50 mol% or more, more preferably 70 mol% or more, and still more preferably 90 mol% or more. Also, the content of ethylene glycol in all the glycol components in the polyester constituting the present polyester film is preferably 50 mol% or more, more preferably 70 mol% or more, and still more preferably 90 mol% or more. Note that the upper limit of the contents of terephthalic acid and ethylene glycol is 100 mol%.

[0023] Further, the above polyester may be a recycled polyester, a polyester using a chemical recycling raw material, a polyester using a material recycling raw material, or a polyester using a biomass-derived raw material. When using a recycled polyester, it is preferable that the intermediate layer of the polyester film contains 50% by mass or more of the recycled polyester raw material.

[0024] (Polymerization catalyst) There is no particular limitation on the polymerization catalyst for the polyester, and conventionally known compounds can be used. Examples include titanium compounds, germanium compounds, antimony compounds, manganese compounds, aluminum compounds, magnesium compounds, and calcium compounds. Among these, at least one of a titanium compound and an antimony compound is preferable, and particularly, it is preferable to use a titanium compound. Therefore, this polyester film preferably contains at least one of a titanium compound and an antimony compound, and more preferably contains a titanium compound.

[0025] By using a titanium compound, the amount of the antimony compound used can be reduced as a result. Therefore, the risk of new protrusion formation due to the precipitation of the antimony compound on the film surface is reduced, and high surface smoothness can be maintained. Therefore, as a particularly preferable form, when this polyester film has a multilayer structure, a form in which the polyester constituting at least one surface layer uses a titanium compound can be mentioned.

[0026] The titanium element content derived from the titanium compound in the surface layer is preferably 3 ppm or more and 40 ppm or less, and more preferably 4 ppm or more and 35 ppm or less. Further, when the surface layer contains at least one of an antimony compound and a titanium compound, the antimony element content in the surface layer is preferably 0 ppm or more and 100 ppm or less. Within such a range, foreign substances caused by the catalyst can be reduced without reducing the production efficiency. From the viewpoints of productivity and cost, it is preferable that the polyester constituting the layer other than the surface layer does not use a titanium compound. On the other hand, by including a titanium compound in the surface layer, a polyester film having excellent smoothness can be obtained. By laminating this resin layer on such a polyester film to form a release film, this release film can be suitably used for forming a ceramic green sheet or the like.

[0027] (Intrinsic viscosity) The intrinsic viscosity (IV) of the polyester constituting this polyester film is preferably 0.50 dL / g or more, more preferably 0.55 dL / g or more, and still more preferably 0.60 dL / g or more. If it is within such a range, there are advantages such as high dispersion of particles due to an increase in shear stress during kneading. Note that the "intrinsic viscosity (IV) of the polyester constituting this polyester film" means the intrinsic viscosity (IV) of a mixed polyester when two or more polyesters having different intrinsic viscosities (IV) are used.

[0028] When this polyester film has a multilayer structure, it is preferable that the intrinsic viscosity (IV) of the polyester constituting the surface layer is within the above range.

[0029] (Particles) In this polyester film, particles can also be blended mainly for the purpose of imparting slipperiness and preventing the occurrence of scratches in each process. The types of particles to be combined are not particularly limited as long as they can impart lubricity. Specific examples include, for example, inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, titanium oxide, etc., crosslinked silicone resin particles, crosslinked acrylic resin particles, crosslinked styrene-acrylic resin particles, crosslinked polyester particles and other crosslinked polymers, and organic particles such as calcium oxalate and ion exchange resins. Among these, it is preferable to use organic particles, silica, aluminum oxide, etc. Further, during the polyester production process, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst can also be used.

[0030] The shape of the particles to be used is not particularly limited either, and any of spherical, massive, rod-shaped, flat-shaped, etc. may be used. Also, there are no particular restrictions on their hardness, specific gravity, color, etc. These series of particles may be used in combination of two or more kinds as necessary.

[0031] Further, the average particle size of the particles to be used is preferably 5 μm or less, more preferably in the range of 0.01 to 3 μm. When it is 5 μm or less, the surface roughness of the film does not become too rough, and there are no problems when forming various surface functional layers in subsequent processes, which is preferable. Also, if the average particle size is within such a range, the haze can be kept low, and it is easy to ensure transparency for the entire release film. In addition, when the particles are in powder form, the average particle size of the particles can be taken as the particle size (d50) at the cumulative volume fraction of 50% in the equivalent spherical distribution obtained by measuring the powder using a centrifugal sedimentation type particle size distribution measuring device (for example, "SA-CP3 type" manufactured by Shimadzu Corporation). For the average particle size of the particles in the film, layer or resin, the diameters of 10 or more particles can be measured by observing them with a scanning electron microscope (SEM), and the average value can be obtained as the average particle size. In that case, for non-spherical particles, the average value of the longest diameter and the shortest diameter can be measured as the diameter of each particle.

[0032] When incorporating particles into this polyester film, for example, it is preferable to provide a surface layer and an intermediate layer and incorporate the particles into the surface layer. The content of the particles depends on the average particle size, but in the layer containing the particles, it is preferably about 5000 ppm or less. By setting the content of the particles within the above range, slipperiness can be imparted. When this polyester film does not contain particles, the slipperiness can be improved or the handling property when winding the film into a roll can be improved by laminating the resin layer described later. Also, if the content of the particles is 5000 ppm or less, the transparency of the polyester film is also good.

[0033] For example, when imparting excellent smoothness to at least one surface of this polyester film, the surface layer on the smooth surface side may or may not contain particles. When making an extremely highly smooth film, it is preferably substantially free of particles. Note that "substantially free" means intentionally not containing, and specifically refers to the content (particle concentration) of the particles being preferably 50 ppm or less, more preferably 40 ppm or less, and even more preferably 30 ppm or less.

[0034] The method of adding particles into this polyester film is not particularly limited, and a conventionally known method can be adopted. For example, in the case of a multilayer polyester film, it can be added at any stage of manufacturing the polyester constituting each layer, but it is preferably added after the completion of the esterification or transesterification reaction.

[0035] (Others) In order to suppress the precipitation amount of the oligomer component, a polyester film may be produced using a polyester with a low content of the oligomer component as a raw material. As a method for producing a polyester with a low content of the oligomer component, various known methods can be used, such as a method of subjecting the polyester to solid-phase polymerization after production. Alternatively, the polyester film may have a three-layer or more structure, and the surface layer of the polyester film may be a layer made of a polyester raw material with a low oligomer component content, thereby suppressing the precipitation amount of the oligomer component. Further, the polyester may be obtained by performing an esterification or transesterification reaction and then increasing the reaction temperature and carrying out melt polycondensation under reduced pressure.

[0036] In addition, in the present polyester film, in addition to the above-mentioned particles, conventionally known ultraviolet absorbers, antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, etc. can be added as necessary.

[0037] The thickness of the polyester film is not particularly limited as long as it is within the range where the film can be formed, but from the viewpoints of mechanical strength, handleability, productivity, etc., it is preferably 9 μm or more, more preferably 12 μm or more. Also, the thickness of the polyester film is preferably 50 μm or less, more preferably 38 μm or less, and even more preferably 35 μm or less.

[0038] <Manufacturing method of polyester film> Next, the manufacturing example of the present polyester film will be specifically described, but it is not limited to the following manufacturing examples. For example, when manufacturing a biaxially stretched film, a method of extruding the dried pellets of the polyester raw material described above from a die as a molten sheet using an extruder and cooling and solidifying it with a cooling roll to obtain an unstretched sheet is preferable. In this case, it is preferable to enhance the adhesion between the sheet and the rotating cooling drum in order to improve the flatness of the sheet, and the electrostatic printing adhesion method and / or the liquid coating adhesion method are preferably adopted.

[0039] Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or tenter-type stretching machine. The stretching temperature is preferably 70 to 120 °C, more preferably 80 to 110 °C, and the stretching ratio is preferably 2.5 to 7.0 times, more preferably 3.0 to 6.0 times. Next, it is stretched in a direction orthogonal to the stretching direction of the first stage. In that case, the stretching temperature is preferably 70 to 170 °C, and the stretching ratio is preferably 3.0 to 7.0 times, more preferably 3.5 to 6.0 times. Then, subsequently, heat treatment is preferably performed at a temperature of 180 to 270 °C under tension or with relaxation within 30% to obtain a biaxially stretched film. In the above stretching, a method of performing one-way stretching in two or more stages can also be adopted. In that case, it is preferable to perform so that the biaxial stretching ratios in the end are respectively within the above ranges.

[0040] Also, a simultaneous biaxial stretching method can be adopted in the production of this polyester film. The simultaneous biaxial stretching method is a method of simultaneously stretching and orienting in the machine direction and the width direction while controlling the temperature of an unstretched sheet preferably at 70 to 120 °C, more preferably at 80 to 110 °C. As the stretching ratio, the area ratio is preferably 4 to 50 times, more preferably 7 to 35 times, and even more preferably 10 to 25 times. Then, subsequently, heat treatment is preferably performed at a temperature of 170 to 250 °C under tension or with relaxation within 30% to obtain a stretched and oriented film. Regarding the simultaneous biaxial stretching apparatus adopting the above stretching method, conventionally known stretching methods such as a screw method, a pantograph method, and a linear drive method can be adopted.

[0041] <<Resin layer>> This release film is provided with resin layers formed from a resin composition on both surfaces of a polyester film. This resin layer is formed from a resin composition (hereinafter, also referred to as "this composition") as described above.

[0042] Here, the "resin" in the resin composition refers to the main component involved in film formation. More specifically, the "resin" also includes the following (A) release agent, (B) binder resin, and (C) antistatic agent, etc.

[0043] This release film has a structure in which a resin layer A is provided on one side of a polyester film and a resin layer B is provided on the opposite side. The resin layer A is composed of a resin composition A, and the resin layer B is composed of a resin composition B.

[0044] The thickness of the resin layer A is preferably 1 nm or more, more preferably 3 nm or more, still more preferably 6 nm or more, and particularly preferably 10 nm or more. Also, the thickness of the resin layer A is preferably 100 nm or less, more preferably 80 nm or less, still more preferably 60 nm or less, and particularly preferably 40 nm or less.

[0045] The thickness of the resin layer B is preferably 1 nm or more, more preferably 3 nm or more, still more preferably 6 nm or more, and particularly preferably 10 nm or more. Also, the thickness of the resin layer B is preferably 100 nm or less, more preferably 80 nm or less, still more preferably 60 nm or less, and particularly preferably 40 nm or less.

[0046] <<Resin layer B / Resin composition B>> The resin layer B preferably contains a (C) antistatic agent. Also, the resin layer B preferably further contains an (A) non-silicone release agent.

[0047] The total content of the (A) non-silicone release agent and the (C) antistatic agent contained in the resin layer B is preferably 20% by mass or more, more preferably 30% by mass or more, and still more preferably 40% by mass or more based on the total mass of the resin layer B. If the total content is within such a range, it becomes easy to control the charge amount at the time of peeling between the resin layer B and the ceramic green sheet to a predetermined value or less, and the adhesion prevention property of the ceramic green sheet to the resin layer B is likely to be sufficiently exhibited.

[0048] ((A) Non-silicone release agent) The resin layer B preferably contains (A) a non-silicone release agent. The non-silicone release agent is not particularly limited, and examples thereof include waxes, long-chain alkyl group-containing compounds, and fluorine compounds. Among them, the (A) non-silicone release agent is preferably at least one selected from waxes and long-chain alkyl group-containing compounds, and more preferably a long-chain alkyl group-containing compound from the viewpoint of preventing the adhesion of the ceramic green sheet.

[0049] When the resin layer B contains the (A) non-silicone release agent, the adhesiveness to the ceramic green sheet can be reduced by the water-repellent and / or oil-repellent effect of the release agent. Further, in the present embodiment, by using (C) an antistatic agent in combination, the adhesiveness of the ceramic green sheet to the resin layer B, which is considered to be caused by peeling electrification during peeling of the ceramic green sheet, can be more effectively prevented.

[0050] The content of the (A) non-silicone release agent in the resin layer B is preferably in the range of 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 50% by mass with respect to the total mass of the resin layer B. By setting the content of the (A) non-silicone release agent within the above range, the adhesiveness of the ceramic green sheet to the resin layer B can be more effectively prevented.

[0051] (Wax) Examples of the wax include natural waxes, synthetic waxes, and modified waxes. Examples of the natural wax include plant-based waxes, animal-based waxes, mineral-based waxes, and petroleum waxes. Examples of the plant-based wax include candelilla wax, carnauba wax, rice wax, wood rosin, and jojoba oil. Examples of the animal-based wax include beeswax, lanolin, and sperm whale oil. Examples of the mineral-based wax include montan wax, ozokerite, and ceresin. Examples of petroleum waxes include paraffin wax, microcrystalline wax, and petrolatum. Examples of synthetic waxes include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, acid amides, amines, imides, ester waxes, and ketones.

[0052] Examples of synthetic waxes include, for example, Fischer-Tropsch wax (also known as Sasol wax), polyethylene wax, etc. In addition, the following polymers, which are low molecular weight polymers (specifically, polymers having a number average molecular weight of 500 to 20,000), namely, polypropylene, ethylene-acrylic acid copolymer, polyethylene glycol, polypropylene glycol, and block or graft conjugates of polyethylene glycol and polypropylene glycol, etc. can be mentioned.

[0053] Examples of modified waxes include, for example, montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. The derivatives here are compounds obtained by any one of purification, oxidation, esterification, saponification, or a combination thereof. Examples of hydrogenated waxes include hydrogenated castor oil and hydrogenated castor oil derivatives.

[0054] Among them, from the viewpoint of excellent mold release performance, synthetic waxes are preferred, among which polyethylene wax is more preferred, and oxidized polyethylene wax is even more preferred.

[0055] From the viewpoints of concavo-convex formation performance due to phase separation and handleability, the number average molecular weight of the synthetic wax is preferably in the range of 500 to 30,000, more preferably 1,000 to 15,000, and even more preferably 2,000 to 8,000.

[0056] In addition, when forming the resin layer B, considering heating for crosslinking or the like, the melting point or softening point of the wax is preferably 80°C or higher, more preferably 110°C or higher. On the other hand, from the viewpoint of controlling the phase separation performance after heat treatment, the melting point or softening point of the wax is preferably 200°C or lower, more preferably 170°C or lower, and even more preferably 150°C or lower.

[0057] (Compound containing a long-chain alkyl group) The compound containing a long-chain alkyl group refers to a compound having a linear or branched alkyl group with 6 or more carbon atoms, preferably 8 or more carbon atoms, and more preferably 12 or more carbon atoms. Examples of the alkyl group include a hexyl group, an octyl group, a decyl group, a lauryl group, an octadecyl group, a behenyl group, etc. Examples of the compound having an alkyl group include various high-molecular compounds containing a long-chain alkyl group, amine compounds containing a long-chain alkyl group, ether compounds containing a long-chain alkyl group, quaternary ammonium salts containing a long-chain alkyl group, etc. Considering heat resistance, it is preferably a high-molecular compound, and from the viewpoint of obtaining the uneven formation performance by appropriate phase separation effectively with a small content, it is more preferably a high-molecular compound having a long-chain alkyl group in the side chain.

[0058] The high-molecular compound having a long-chain alkyl group in the side chain can be obtained by reacting a high-molecular compound having a reactive group with a compound having an alkyl group capable of reacting with the reactive group. Examples of the reactive group include a hydroxyl group, an amino group, a carboxy group, an acid anhydride, etc. Examples of the compound having these reactive groups include polyvinyl alcohol, polyethyleneimine, polyethyleneamine, a reactive-group-containing polyester resin, a reactive-group-containing poly(meth)acrylic resin, etc. Among these, considering ease of handling, polyvinyl alcohol is preferably used.

[0059] Examples of the compound having an alkyl group capable of reacting with the above reactive group include long-chain alkyl group-containing isocyanates such as hexyl isocyanate, octyl isocyanate, decyl isocyanate, lauryl isocyanate, octadecyl isocyanate, behenyl isocyanate, etc., long-chain alkyl group-containing acid chlorides such as hexanoyl chloride, octanoyl chloride, decanoyl chloride, lauroyl chloride, octadecanoyl chloride, behenoyl chloride, etc., long-chain alkyl group-containing amines, long-chain alkyl group-containing alcohols, and the like. Among these, considering ease of handling, long-chain alkyl group-containing isocyanates are preferred, and octadecyl isocyanate is particularly preferred.

[0060] In addition, a polymer compound having a long-chain alkyl group in the side chain can also be obtained by polymerizing a long-chain alkyl (meth) acrylate or copolymerizing a long-chain alkyl (meth) acrylate with another vinyl group-containing monomer. Examples of the long-chain alkyl (meth) acrylate include hexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, octadecyl (meth) acrylate, behenyl (meth) acrylate, and the like.

[0061] (Fluorine compound) A fluorine compound is a compound containing a fluorine atom in the compound. As the fluorine compound, an organic fluorine compound is preferably used in terms of the coating appearance by in-line coating. Examples include perfluoroalkyl group-containing compounds, polymers of olefin compounds containing fluorine atoms, aromatic fluorine compounds such as fluorobenzene, and the like. From the viewpoint of obtaining the uneven formation performance by appropriate phase separation effectively with a small content, a compound having a perfluoroalkyl group is preferred. Furthermore, as the fluorine compound, a compound containing the above-described long-chain alkyl compound can also be used.

[0062] Examples of the compound having a perfluoroalkyl group include perfluoroalkyl (meth)acrylate, perfluoroalkylmethyl (meth)acrylate, 2-perfluoroalkylethyl (meth)acrylate, 3-perfluoroalkylpropyl (meth)acrylate, 3-perfluoroalkyl-1-methylpropyl (meth)acrylate, 3-perfluoroalkyl-2-propenyl (meth)acrylate and other perfluoroalkyl group-containing (meth)acrylates and their polymers, perfluoroalkylmethyl vinyl ether, 2-perfluoroalkylethyl vinyl ether, 3-perfluoropropyl vinyl ether, 3-perfluoroalkyl-1-methylpropyl vinyl ether, 3-perfluoroalkyl-2-propenyl vinyl ether and other perfluoroalkyl group-containing vinyl ethers and their polymers. Considering heat resistance, a polymer is preferably used. The polymer may be a polymer of a single compound or a polymer of a plurality of compounds. Further, from the viewpoint of obtaining the uneven formation performance by appropriate phase separation effectively with a small content, the perfluoroalkyl group preferably has 3 to 11 carbon atoms. Furthermore, it may be a polymer with a compound containing a long-chain alkyl compound as described above, and a polymer with vinyl chloride is also preferably used from the viewpoint of adhesion to the polyester film as the base material.

[0063] ((B) Binder resin) The resin layer B preferably further contains (B) a binder resin. The (B) binder resin can improve the coatability when the resin composition B is used as a coating solution.

[0064] (B) The binder resin selected as the binder resin is a polymer compound having a number average molecular weight (Mn) of 1000 or more by gel permeation chromatography (GPC) measurement in accordance with the "Polymer Compound Safety Evaluation Flow Scheme" (November 1985, sponsored by the Chemical Substances Review Committee), and preferably has film-forming properties. Such a binder resin is not particularly limited, and conventionally known binder resins can be used. For example, (meth)acrylic resins, polyvinyl alcohol, polyester resins, polyurethane resins, etc. can be mentioned. Among them, from the viewpoint of high hydrophilicity and film formation, (B) the binder resin is preferably at least one selected from (meth)acrylic resins and polyvinyl alcohol, and more preferably a (meth)acrylic resin. Note that as the (B) binder resin, only one kind may be used alone, or two or more kinds may be used in combination.

[0065] ((meth)acrylic resin) The (meth)acrylic resin is a polymer composed of polymerizable monomers containing acrylic and methacrylic monomers. These may be homopolymers, copolymers, or copolymers with polymerizable monomers other than acrylic and methacrylic monomers.

[0066] In this specification, when the expression "(meth)acrylic" is used, "(meth)acrylic" means one or both of "acrylic" and "methacrylic". Similarly, "(meth)acrylic acid" means one or both of "acrylic acid" and "methacrylic acid", "(meth)acrylate" means one or both of "acrylate" and "methacrylate", and "(meth)acryloyl" means one or both of "acryloyl" and "methacryloyl". The same applies to others.

[0067] The (meth)acrylic resin is a polymer having (meth)acrylic acid or (meth)acrylic acid alkyl ester as a constituent unit, and may be a copolymer of styrene or a styrene derivative and (meth)acrylic acid or (meth)acrylic acid alkyl ester. Further, the (meth)acrylic resin may be a copolymer of these polymers and other polymers (such as polyester, polyurethane, etc.). For example, the (meth)acrylic resin may be a block copolymer or a graft copolymer. That is, the (meth)acrylic resin may be a (meth)acrylic-modified polyester resin or a (meth)acrylic-modified polyurethane resin.

[0068] In addition, the (meth)acrylic resin also includes polymers (in some cases, mixtures of polymers) obtained by polymerizing polymerizable monomers containing acrylic or methacrylic monomers in a polyester solution or a polyester dispersion. Similarly, polymers (in some cases, mixtures of polymers) obtained by polymerizing the above polymerizable monomers in a polyurethane solution or a polyurethane dispersion are also included. Similarly, polymers (in some cases, polymer mixtures) obtained by polymerizing the above polymerizable monomers in other polymer solutions or dispersions are also included, and these are also regarded as (meth)acrylic-modified polyester resins or (meth)acrylic-modified polyurethane resins in this specification. It should be noted that the polyester and polyurethane used in the (meth)acrylic resin can be appropriately selected from those exemplified as the polyester and polyurethane used in the binder resin described later. In addition, the (meth)acrylic resin can also contain a hydroxy group or an amino group in order to further improve the adhesion to the polyester film.

[0069] The above-mentioned polymerizable monomers are not particularly limited, but particularly representative compounds include, for example, various carboxy group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, citraconic acid, and salts thereof; various hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, monobutyl hydroxyfumarate, monobutyl hydroxyitaconate; various alkyl (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate; various nitrogen-containing compounds such as (meth)acrylamide, diacetone acrylamide, or (meth)acrylonitrile; hydroxyl group-containing nitrogen-containing compounds such as N-methylol (meth)acrylamide; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, vinyltoluene; various vinyl esters such as vinyl propionate; various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane; phosphorus-containing vinyl-based monomers; various vinyl halides such as vinyl chloride, vinylidene chloride; and various conjugated dienes such as butadiene.

[0070] Among the above-mentioned (meth)acrylic resins, polymers obtained by polymerizing polymerizable monomers containing acrylic or methacrylic monomers are preferred, and it is more preferred that the polymerizable monomers contain alkyl (meth)acrylates. Note that the resin composition B is preferably diluted with a solvent to form a coating solution as described later. In this case, it is preferable that the solvent has water as the main solvent (50% by mass or more). That is, from the viewpoint of facilitating dissolution or dispersion when the coating solution is aqueous, it is preferable that the polymerizable monomer has a hydrophilic group such as a hydroxyl group or a carboxyl group. Therefore, it is also preferable that the (meth)acrylic resin is a polymer obtained by polymerizing alkyl (meth)acrylates and polymerizable monomers containing hydrophilic group-containing monomers such as hydroxyl group-containing monomers and carboxyl group-containing monomers. Further, the (meth)acrylic resin may be an emulsion polymer obtained by polymerizing polymerizable monomers in the presence of, for example, a surfactant.

[0071] (Polyvinyl alcohol) Polyvinyl alcohol is a compound having a polyvinyl alcohol moiety. For example, conventionally known polyvinyl alcohols can be used, including modified compounds that are partially acetalized or butyralized with respect to polyvinyl alcohol. The degree of polymerization of polyvinyl alcohol is not particularly limited, but it is preferably 100 or more, more preferably in the range of 300 to 40,000. If the degree of polymerization is 100 or more, it is preferable because the water resistance of the resin layer can be obtained. The degree of saponification of polyvinyl alcohol is not particularly limited, but it is preferably 70 mol% or more, more preferably in the range of 70 to 99.9 mol%, still more preferably 80 to 97 mol%, and most preferably 86 to 95 mol% of the saponified polyvinyl acetate is practically used.

[0072] (Polyester resin) Examples of the polyester resin include those composed of the following polyvalent carboxylic acids and polyvalent hydroxy compounds as main constituent components. Examples of the polyvalent carboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, monopotassium trimellitate, and ester-forming derivatives thereof. Examples of the polyvalent hydroxy compound include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylol ethyl sulfonate, potassium dimethylolpropionate, and the like. One or more of these compounds can be appropriately selected from among them, and a polyester resin can be synthesized by a conventional polycondensation reaction.

[0073] Alternatively, a polyester resin in which sulfoisophthalic acid is copolymerized as a part of the above polyvalent carboxylic acid, a sulfonic acid group is introduced into the polyester skeleton, and the polyester resin is neutralized and hydrophilized can also be used. In this case, the copolymerization amount is preferably 1 to 13 mol%, more preferably 3 to 10 mol%, and still more preferably 5 to 9 mol% based on the total polyvalent carboxylic acid. By introducing an appropriate amount of sulfonic acid groups, the hydrophilicity of the resin layer can be increased, and it is possible to easily form an uneven structure. Furthermore, the water dispersion stability can be improved.

[0074] (Polyurethane resin) A polyurethane resin is a high molecular compound having a urethane bond in the molecule, and those having water dispersibility or water solubility are preferred.

[0075] In order to impart water dispersibility or water solubility, it is preferable to introduce hydrophilic groups such as hydroxyl groups, carboxyl groups, sulfonic acid groups, sulfonyl groups, phosphate groups, and ether groups into the urethane resin. Among the above hydrophilic groups, it is particularly preferable to introduce a carboxyl group or a sulfonic acid group from the viewpoint of the adhesion between the resin layer B and the polyester film.

[0076] One of the methods for producing a urethane resin is by the reaction of a hydroxyl group-containing compound and an isocyanate. As the hydroxyl group-containing compound used as a raw material, a polyol is preferably used, and examples thereof include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination of multiple types.

[0077] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol.

[0078] Examples of polyester polyols include those obtained from the reaction of polyvalent carboxylic acids (such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or their acid anhydrides with polyhydric alcohols (such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3 - butanediol, 1,4 - butanediol, 2,3 - butanediol, 2 - methyl - 1,3 - propanediol, 1,5 - pentanediol, neopentyl glycol, 1,6 - hexanediol, 3 - methyl - 1,5 - pentanediol, 2 - methyl - 2,4 - pentanediol, 2 - methyl - 2 - propyl - 1,3 - propanediol, 1,8 - octanediol, 2,2,4 - trimethyl - 1,3 - pentanediol, 2 - ethyl - 1,3 - hexanediol, 2,5 - dimethyl - 2,5 - hexanediol, 1,9 - nonanediol, 2 - methyl - 1,8 - octanediol, 2 - butyl - 2 - ethyl - 1,3 - propanediol, 2 - butyl - 2 - hexyl - 1,3 - propanediol, cyclohexanediol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyldialkanolamine, lactone diol, etc.).

[0079] Examples of polycarbonate polyols include polycarbonate diols obtained by a dealcoholization reaction from polyhydric alcohols and dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, etc., such as poly(1,6 - hexylene) carbonate, poly(3 - methyl - 1,5 - pentylene) carbonate, etc.

[0080] Among these, polyester polyols are preferred.

[0081] Examples of the polyisocyanate compounds used to obtain the urethane resin include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate; aliphatic diisocyanates having an aromatic ring such as α,α,α’,α’-tetramethylxylylene diisocyanate; aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate; and alicyclic diisocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and isopropylidene dicyclohexyl diisocyanate. These may be used alone or in combination of two or more.

[0082] When synthesizing the urethane resin, a chain extender may be used. The chain extender is not particularly limited as long as it has two or more active groups that react with isocyanate groups. Generally, a chain extender having two hydroxyl groups or amino groups can be mainly used.

[0083] Examples of the chain extender having two hydroxyl groups include glycols such as aliphatic glycols like ethylene glycol, propylene glycol, and butanediol; aromatic glycols like xylylene glycol and bis(hydroxyethoxy)benzene; and ester glycols like neopentyl glycol hydroxypivalate.

[0084] Examples of the chain extender having two amino groups include aromatic diamines such as tolylene diamine, xylylene diamine, diphenylmethane diamine; aliphatic diamines such as ethylenediamine, propanediamine, hexanediamine, 2,2-dimethyl-1,3-propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine; alicyclic diamines such as 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethane diamine, 1,4-diaminocyclohexane, 1,3-bisaminomethylcyclohexane, and the like.

[0085] ((C) Antistatic agent) The resin layer B preferably contains the (C) antistatic agent. Examples of the antistatic agent include ion conductive polymer compounds. By containing a predetermined antistatic agent in the resin layer B, it becomes easy to control the charge amount at the time of peeling between the resin layer B and the ceramic green sheet to a predetermined value or less, and the adhesion prevention property of the ceramic green sheet to the resin layer B is easily sufficiently exhibited.

[0086] The content of the (C) antistatic agent contained in the resin layer B is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, based on the total mass of the resin layer B. Also, the content of the (C) antistatic agent contained in the resin layer B is preferably 60% by mass or less, more preferably 55% by mass or less, still more preferably 50% by mass or less, and even more preferably 45% by mass or less. By setting the content of the (C) antistatic agent within the above range, it becomes easy to control the charge amount at the time of peeling between the resin layer B and the ceramic green sheet to a predetermined value or less, and the adhesion prevention property of the ceramic green sheet to the resin layer B is easily sufficiently exhibited.

[0087] An ion-conductive polymer compound is a polymer compound containing an ion-conductive functional group, and examples thereof include polymer compounds such as ammonium group-containing compounds, polyether compounds, sulfonic acid compounds, and betaine compounds. Among these, ammonium group-containing compounds are particularly preferred from the viewpoint of high polarity and prevention of peeling electrification.

[0088] An ammonium group-containing compound refers to a compound having an ammonium group in the molecule, and is preferably a polymer compound having an ammonium group. For example, a polymer using a monomer having an ammonium group and an unsaturated double bond as a component can be used.

[0089] Specific examples of such polymers include, for example, polymers having repeating units represented by the following formula (1). The ammonium group-containing polymer compound may be a homopolymer or copolymer of these, or may further copolymerize a plurality of other components.

[0090]

Chemical formula

[0091] In the above formula (1), R 1 , R 2 are each independently a hydrogen atom, an alkyl group, a phenyl group, etc., and these alkyl groups and phenyl groups may be substituted with the groups shown below. Substitutable groups are, for example, a hydroxy group, an amide group, an ester group, an alkoxy group, a phenoxy group, a naphthoxy group, a thioalkoxy group, a thiophenoxy group, a cycloalkyl group, a trialkylammonium alkyl group, a cyano group, a halogen, etc. Also, R 1 and R 2 may be chemically bonded, and the linked R 1 and R 2 are, for example, -(CH 2 ) m -(m is an integer from 2 to 5), -CH(CH 3 )CH(CH 3)-, -CH=CH-CH=CH-, -CH=CH-CH=N-, -CH=CH-N=C-, -CH 2 OCH 2 -, -(CH 2 ) 2 O(CH 2 ) 2 - etc. may also be used.

[0092] X in the above formula (1) - can be appropriately selected within the range that does not impair the gist of the present invention. For example, X - can include halogen ions, sulfonates, phosphates, nitrates, alkyl sulfonates, carboxylates, etc.

[0093] Among polymers containing a monomer having an ammonium group and an unsaturated double bond, from the viewpoint of enhancing film-forming properties and obtaining a stable film, the polymer may have other monomers as copolymerization components. Examples of other monomers include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate, alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate, and acrylamides such as n-methylolacrylamide.

[0094] However, from the viewpoint of further enhancing polarity and preventing peeling charge, the above polymer is preferably a homopolymer having the repeating unit represented by the above formula (1).

[0095] Also, the number average molecular weight of the ammonium group-containing polymer compound is preferably 1000 to 500000, more preferably 2000 to 350000, and even more preferably 5000 to 200000 or less. By setting the number average molecular weight of the ammonium group-containing polymer compound to 1000 or more, the strength of the coating film can be increased and the heat resistance stability can be enhanced. Also, by setting the number average molecular weight of the ammonium group-containing polymer compound to 500000 or less, the viscosity of the coating solution can be controlled within an appropriate range, and the handleability and coatability can be enhanced.

[0096] Further, the (C) antistatic agent is preferably at least one selected from (a1) a polymer in which a compound composed of thiophene or a thiophene derivative is doped with another anionic compound, and (a2) a polymer in which a compound composed of thiophene or a thiophene derivative has an anionic group and is self-doped. Examples of such an antistatic agent include those obtained by polymerizing a compound represented by the following formula (2) or the following formula (3) in the presence of a polyanion.

[0097]

Chemical formula

[0098] In the above formula (2), R 1 and R 2 each independently represent a hydrogen atom, or an aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group, etc. having 1 to 20 carbon atoms.

[0099]

Chemical formula

[0100] In the above formula (3), n represents an integer of 1 to 4.

[0101] Specific examples of the above polymer include, for example, a polymer having a repeating unit represented by the formula (4). The above polymer may be a homopolymer, copolymer, or may copolymerize other plural components. However, from the viewpoint of improving antistatic properties, the above polymer is preferably a homopolymer.

[0102]

Chemical formula

[0103] In the above formula (4), the substituent R 1 is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R2 is preferably -O- or -NH-, and R 3 is preferably an alkylene group having 1 to 6 carbon atoms or another linking group capable of forming the structure of formula (4), and R 4 , R 5 and R 6 at least one of which is a hydrogen atom, and the other substituents are preferably an alkyl group having 1 to 3 carbon atoms or a hydroxyalkyl group having 2 to 3 carbon atoms in the alkyl group. X - is preferably an alkylsulfonate ion having an alkyl group having 1 to 4 carbon atoms.

[0104] Examples of the polyanion used during polymerization include poly(meth)acrylic acid, polymaleic acid, polystyrene sulfonic acid, polyvinyl sulfonic acid, and the like. As a method for producing such a polymer, for example, a method as disclosed in JP-A-7-90060 can be adopted.

[0105] In the present embodiment, in the compound represented by the above formula (3), n is 2, and a compound using polystyrene sulfonic acid as the polyanion is preferably used.

[0106] When these polyanions are acidic, part or all of them may be neutralized. As the base used for neutralization, ammonia, organic amines, and alkali metal hydroxides are preferable.

[0107] ((D) Crosslinking agent) Resin composition B preferably further contains (D) a crosslinking agent, and resin layer B also preferably further contains (D) a crosslinking agent. There are no particular restrictions on the crosslinking agent, and conventionally known crosslinking agents can be used. For example, melamine compounds, oxazoline compounds, epoxy compounds, carbodiimide compounds, isocyanate compounds, silane coupling compounds, etc. can be mentioned. Among them, from the viewpoint of imparting durability to resin layer B, it is preferably to contain at least one selected from melamine compounds, epoxy compounds and oxazoline compounds, and more preferably to contain at least one selected from melamine compounds and epoxy compounds.

[0108] The content of (D) crosslinking agent in resin composition B is preferably in the range of 10 to 90% by mass, more preferably 15 to 85% by mass, and still more preferably 20 to 65% by mass based on the total mass of the non-volatile components of resin composition B. By setting the content of (D) crosslinking agent within the above range, the coatability when resin composition B is used as a coating solution can be improved. Also, by setting the content of (D) crosslinking agent within the above range, the durability of resin layer B can be more effectively enhanced.

[0109] (Melamine compound) A melamine compound refers to a compound having a melamine skeleton in the compound. For example, alkylolated melamine derivatives, compounds obtained by reacting an alcohol with an alkylolated melamine derivative to partially or completely etherify, and mixtures thereof can be used. Examples of alkylolation include methylolation, ethylolation, isopropylation, n-butylation, isobutylation, etc. Among these, from the viewpoint of reactivity, methylolation is preferred. As the alcohol used for etherification, methanol, ethanol, isopropanol, n-butanol, isobutanol, etc. are preferably used, and among these, methanol is more preferred. The melamine compound may be either a monomer or a multimer of dimer or higher, or a mixture thereof may be used. Further, a compound obtained by co-condensing urea or the like with a part of melamine may also be used, and in order to increase the reactivity of the melamine compound, it is also possible to further use a catalyst in the resin composition.

[0110] (oxazoline compound) An oxazoline compound is a compound having an oxazoline group in the molecule, and a polymer containing an oxazoline group is particularly preferred. A polymer containing an oxazoline group can be prepared by polymerization of an addition-polymerizable oxazoline group-containing monomer alone or with other monomers. Examples of the addition-polymerizable oxazoline group-containing monomer include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline, etc., and a mixture of one or more of these can be used. Among these, 2-isopropenyl-2-oxazoline is industrially easily available and suitable. Other monomers are not limited as long as they are monomers copolymerizable with the addition-polymerizable oxazoline group-containing monomer. For example, (meth)acrylic acid esters such as alkyl (meth)acrylates (the alkyl group includes methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, and cyclohexyl group); unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated amides such as (meth)acrylamide, N-alkyl (meth)acrylamide and N,N-dialkyl (meth)acrylamide (the alkyl group includes methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; halogen-containing α,β-unsaturated monomers such as vinyl chloride and vinylidene chloride; α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene, etc., and one or more of these monomers can be used. In addition, the oxazoline compound may have a polyalkylene oxide chain such as a polyethylene oxide chain, and for example, a (meth)acrylate having a polyalkylene oxide chain may be used as another monomer. From the viewpoint of improving the adhesion of the resin layer B to the polyester film, the amount of oxazoline groups in the oxazoline compound is preferably in the range of 0.5 to 10 mmol / g, more preferably 1 to 9 mmol / g, and even more preferably 3 to 8 mmol / g.

[0111] (Epoxy compound) An epoxy compound is a compound having an epoxy group in the molecule, and examples thereof include condensates with hydroxyl groups or amino groups such as epichlorohydrin, ethylene glycol, polyethylene glycol, glycerin, polyglycerin, and bisphenol A, polyepoxy compounds, diepoxy compounds, monoepoxy compounds, and glycidylamine compounds. Examples of the polyepoxy compound include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, and trimethylolpropane polyglycidyl ether. Examples of the diepoxy compound include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polytetramethylene glycol diglycidyl ether. Examples of the monoepoxy compound include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, and phenyl glycidyl ether. Examples of the glycidylamine compound include N,N,N',N'-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N-diglycidylamino)cyclohexane. From the viewpoint of improving the adhesion of the resin layer B to the polyester film, a polyether-based epoxy compound is preferred. Also, as the amount of epoxy groups, a polyepoxy compound having three or more functional groups rather than two functional groups is preferred.

[0112] (Carbodiimide compound) A carbodiimide compound refers to a compound having a carbodiimide structure and is a compound having one or more carbodiimide structures in the molecule. For better adhesion between the resin layer B and the polyester film, a polycarbodiimide compound having two or more carbodiimide structures in the molecule is more preferred.

[0113] The carbodiimide compound can be synthesized by a conventionally known technique, and generally, a condensation reaction of a diisocyanate compound is used. The diisocyanate compound is not particularly limited, and either an aromatic or aliphatic type can be used. Specifically, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, and dicyclohexylmethane 4,4'-diisocyanate can be mentioned.

[0114] The content of the carbodiimide group contained in the carbodiimide compound is preferably in the range of 100 to 1000 in terms of carbodiimide equivalent (the weight [g] of the carbodiimide compound for providing 1 mol of the carbodiimide group), more preferably in the range of 250 to 800, and even more preferably in the range of 300 to 700. By using within the above range, the durability of the resin layer B is improved.

[0115] Furthermore, within the range that does not impair the gist of the present invention, a surfactant may be added to improve the water solubility and water dispersibility of the polycarbodiimide compound, and hydrophilic monomers such as polyalkylene oxide, quaternary ammonium salts of dialkylamino alcohol, and hydroxyalkyl sulfonate may also be added and used.

[0116] (Isocyanate compound) The isocyanate compound refers to a compound having an isocyanate or an isocyanate derivative structure typified by blocked isocyanate. Examples of the isocyanate compound include aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate; aliphatic isocyanates having an aromatic ring such as α,α,α’,α’-tetramethylxylylene diisocyanate; aliphatic isocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate; and alicyclic isocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylene bis(4-cyclohexyl isocyanate), and isopropylidene dicyclohexyl diisocyanate. In addition, polymers and derivatives such as biuret compounds, isocyanurate compounds, uretdione compounds, and carbodiimide-modified products of these isocyanates can also be mentioned. These may be used alone or in combination of two or more. Among the above isocyanate compounds, aliphatic isocyanates or alicyclic isocyanates are more preferable than aromatic isocyanates in order to avoid yellowing due to ultraviolet rays.

[0117] When used in the form of blocked isocyanate, examples of the blocking agent include bisulfites; phenolic compounds such as phenol, cresol, and ethylphenol; alcohol compounds such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol, and ethanol; active methylene compounds such as methyl isobutanoyl acetate, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, and acetylacetone; mercaptan compounds such as butyl mercaptan and dodecyl mercaptan; lactam compounds such as ε-caprolactam and δ-valerolactam; amine compounds such as diphenylaniline, aniline, and ethyleneimine; acid amide compounds such as acetanilide and acetic acid amide; and oxime compounds such as formaldehyde oxime, acetaldehyde oxime, acetone oxime, methyl ethyl ketone oxime, and cyclohexanone oxime. These may be used alone or in combination of two or more.

[0118] The isocyanate compound may be used alone or as a mixture or conjugate with various polymers. In terms of improving the dispersibility and crosslinkability of the isocyanate compound, it is preferable to use a mixture or conjugate with a polyester resin or a urethane resin.

[0119] (Silane coupling compound) A silane coupling compound is an organosilicon compound having an organic functional group and a hydrolyzable group such as an alkoxy group in one molecule. For example, epoxy group-containing compounds such as 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; vinyl group-containing compounds such as vinyltrimethoxysilane, vinyltriethoxysilane; styryl group-containing compounds such as p-styryltrimethoxysilane, p-styryltriethoxysilane; (meth)acrylic group-containing compounds such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane; amino group-containing compounds such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane; isocyanurate group-containing compounds such as tris(trimethoxysilylpropyl)isocyanurate, tris(triethoxysilylpropyl)isocyanurate; mercapto group-containing compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, etc.

[0120] (Crosslinking catalyst) When the resin layer B contains a (D) crosslinking agent, the resin composition B may further contain a crosslinking catalyst. The crosslinking catalyst is used to enhance the reactivity of the crosslinking agent, and various known catalysts can be used. For example, amine compounds, salts of amine compounds, aromatic sulfonic acid compounds such as p-toluenesulfonic acid, organic acids such as phosphoric acid compounds and their salts, imine compounds, amidine compounds, guanidine compounds, organometallic compounds, metal salts such as zinc stearate, zinc myristate, aluminum stearate, calcium stearate, etc. Among these, amine compounds, salts of amine compounds, and p-toluenesulfonic acid are preferred, and amine compounds and salts of amine compounds are more preferred.

[0121] When the resin composition B contains a crosslinking catalyst, the content of the crosslinking catalyst is preferably in the range of 0.01 to 5% by mass, more preferably 0.1 to 4% by mass, and still more preferably 1 to 3% by mass with respect to the total mass of the non-volatile components in the resin composition B. By setting the content of the crosslinking catalyst within such a range, a decrease in pot life can be suppressed.

[0122] (Fine particles) The resin composition B may further contain fine particles. By using the fine particles in combination, a fine concavo-convex structure is formed on the surface of the resin layer B, so that even when the release film is formed into a roll shape, the convex portions on the surface of the resin layer are less likely to be deformed, and a good roll appearance can be obtained.

[0123] Examples of the fine particles include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, as well as crosslinked polymers such as crosslinked silicone resin particles, crosslinked acrylic resin particles, crosslinked styrene-acrylic resin particles, and crosslinked polyester particles, and organic particles such as calcium oxalate and ion exchange resins. Among these, silica and aluminum oxide are preferred.

[0124] The average particle diameter (average primary particle diameter) of the fine particles is preferably from 1 to 100 nm, more preferably from 2 to 60 nm, and still more preferably from 3 to 30 nm. If the average particle diameter is within such a range, generation of coarse protrusions due to aggregation of the particles and contamination of the process due to dropping of the particles can be suppressed, and it becomes easy to obtain a desired fine uneven structure.

[0125] When the resin composition B contains fine particles, the content of the fine particles is preferably in the range of 1 to 50% by mass, more preferably 5 to 45% by mass, and still more preferably 10 to 40% by mass with respect to the total mass of the non-volatile components in the resin composition B. By setting the content of the fine particles within the above range, a desired fine uneven structure can be obtained.

[0126] ((Particularly preferred form)) As the combination of the compounds contained in the resin composition B, a combination of (B) a binder resin and (C) an antistatic agent is preferable, and more preferably, a combination of (B) a binder resin, (C) an antistatic agent, and (D) a crosslinking agent. Most preferably, a combination of (B) a binder resin and (C) an ion conductive polymer compound, or a combination of (B) a binder resin, (C) at least one selected from a polymer in which a compound composed of (a1) thiophene or a thiophene derivative is doped with another anionic compound and (a2) a polymer in which a compound composed of thiophene or a thiophene derivative has an anionic group and is self-doped, and (D) a crosslinking agent is good. Among them, in particular, a combination of (A) a non-silicone release agent, (B) a binder resin, and (C) an ion conductive polymer compound, or a combination of (B) a binder resin, (C) at least one selected from a polymer in which a compound composed of (a1) thiophene or a thiophene derivative is doped with another anionic compound and (a2) a polymer in which a compound composed of thiophene or a thiophene derivative has an anionic group and is self-doped, and (D) a crosslinking agent is good.

[0127] <<Resin layer A / Resin composition A>> The resin layer A contains a non-silicone release agent. That is, the resin composition A contains a non-silicone release agent. By including a non-silicone release agent in the resin composition A, the coatability with respect to the ceramic slurry can be enhanced.

[0128] The non-silicone release agent is preferably at least one selected from wax and a long-chain alkyl group-containing compound, and more preferably a long-chain alkyl group-containing compound. As the non-silicone release agent, the (A) non-silicone release agent that the above-described resin layer B may contain can be similarly exemplified.

[0129] In addition, the resin layer A may further contain, as necessary, (B) a binder resin, (D) a crosslinking agent, fine particles, etc. As the (B) binder resin, (D) crosslinking agent, and fine particles, the (B) binder resin, (D) crosslinking agent, and fine particles that the above-described resin layer B may contain can be similarly exemplified.

[0130] The content of the non-silicone release agent in the resin composition A is preferably in the range of 5 to 90% by mass, more preferably 15 to 75% by mass, and still more preferably 15 to 50% by mass with respect to the total mass of the non-volatile components in the resin composition A. By setting the content of the non-silicone release agent within the above range, after applying and drying the ceramic slurry, the releasability with respect to the obtained ceramic green sheet becomes good.

[0131] (Particularly preferred form) As the combination of the compounds contained in the resin composition A, the combination of a long-chain alkyl group-containing compound, melamine, and a binder resin is preferable. More preferably, it is the combination of a long-chain alkyl group compound, melamine, and a polyester resin.

[0132] (Other components) In the resin layer A and the resin layer B, additives such as an antifoaming agent, a coatability improver, a surfactant, a thickener, an organic lubricant, an ultraviolet absorber, an antioxidant, a foaming agent, a dye, and a pigment may be further appropriately blended within a range not impairing the gist of the present invention.

[0133] (Solvent) Resin composition A and resin composition B may each be diluted with a solvent to form a coating solution. That is, as a liquid coating solution, it may be applied to this polyester film and, if necessary, dried and cured to form resin layer A and resin layer B respectively. In addition, each component constituting resin composition A and resin composition B (for example, (A) non-silicone release agent, (B) binder resin, (C) antistatic agent, (D) crosslinking agent, and optionally added crosslinking catalyst and fine particles, other components, etc.) may be dissolved in a solvent or dispersed in a solvent.

[0134] When the resin composition is used as a coating solution, the concentration of the total non-volatile components of the resin composition in the coating solution is preferably 0.1 to 50% by mass. If the concentration of the total non-volatile components is 0.1% by mass or more, a resin layer with a desired thickness can be efficiently formed. On the other hand, if the concentration of the total non-volatile components is 50% by mass or less, the appearance of the resin layer can be improved by suppressing the viscosity during coating, and the stability in the coating solution can be enhanced.

[0135] There is no particular limitation on the solvent used for dilution, and either water or an organic solvent can be used. From the perspective of environmental protection, it is preferable to use water as the main solvent (50% by mass or more). The water content is preferably 60% by mass or more, more preferably 70% by mass or more. A small amount of organic solvent may be contained in the aqueous coating solution. The specific amount of the organic solvent should be less than that of water on a mass basis. For example, it is preferably less than 50% by mass in the solvent, more preferably less than 30% by mass, and even more preferably less than 20% by mass. Examples of organic solvents to be used in combination with water include alcohols such as ethanol, isopropanol, ethylene glycol, and glycerin; ethers such as ethyl cellosolve, t-butyl cellosolve, propylene glycol monomethyl ether, and tetrahydrofuran; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; and amines such as dimethylethanolamine. These can be used alone or in combination. By appropriately selecting and incorporating these organic solvents into the aqueous coating solution as needed, the stability and coatability of the coating solution may be improved.

[0136] When only an organic solvent is used as the above solvent, examples of such organic solvents include aromatic hydrocarbons such as toluene; aliphatic hydrocarbons such as hexane, heptane, and isooctane; esters such as ethyl acetate and butyl acetate; ketones such as ethyl methyl ketone and isobutyl methyl ketone; alcohols such as ethanol and 2-propanol; and ethers such as diisopropyl ether and dibutyl ether. These may be used alone or in combination of multiple types, taking into account solubility, coatability, boiling point, etc.

[0137] The analysis of each component in the resin layer (for example, (A) release agent, (B) binder resin, (C) antistatic agent, (D) crosslinking agent, crosslinking catalyst and fine particles optionally added, unreacted substances such as other components, compounds after reaction, or mixtures thereof) can be performed by, for example, TOF-SIMS, ESCA, fluorescent X-ray, etc.

[0138] <Method for forming resin layers A and B> The method for forming resin layers A and B (hereinafter also simply referred to as "resin layer") is not particularly limited, and conventionally known coating methods such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, and curtain coating can be used. In addition, as methods for forming the resin layer, there are in-line coating and off-line coating. Regarding the drying and curing conditions, there are no particular limitations. For example, when providing the resin layer by off-line coating, preferably, heat treatment is performed at 80 to 200 °C for 3 to 40 seconds, more preferably at 100 to 180 °C for 3 to 40 seconds as a guide. On the other hand, when providing the resin layer by in-line coating, preferably, heat treatment is performed at 70 to 280 °C for 3 to 200 seconds as a guide.

[0139] Among them, the resin layer is preferably formed by in-line coating, which treats the film surface during the film-forming process of the polyester film. In-line coating is a method of performing coating within the process of manufacturing a polyester film. Specifically, it is a method of performing coating at any stage from melting and extruding the polyester to stretching and then heat-fixing and winding up. Usually, coating is performed on any one of the unstretched sheet obtained by melting and quenching, the uniaxially stretched film, the biaxially stretched film before heat-fixing, and the film after heat-fixing and before winding up. By forming the resin layer by in-line coating, the production efficiency of the release film can be increased.

[0140] For example, when forming the resin layer by in-line coating, in sequential biaxial stretching, a method of coating the uniaxially stretched film stretched particularly in the longitudinal direction (vertical direction) and then stretching it in the transverse direction is excellent. According to such a method, film formation and resin layer formation can be performed simultaneously, so there are merits in terms of manufacturing cost. Also, since stretching is performed after coating, the thickness of the resin layer can be changed by the stretching ratio, and thin film coating can be performed more easily compared to the off-line coating film.

[0141] In addition, by providing the resin layer on the film before stretching, the resin layer can be stretched together with the polyester film, thereby firmly adhering the resin layer to the polyester film.

[0142] Furthermore, in the production of a biaxially stretched polyester film, by stretching while gripping the film edge with a clip or the like, the film can be restrained in the longitudinal and transverse directions, and in the heat setting step, a high temperature can be applied while maintaining flatness without wrinkles. Therefore, the heat treatment applied after coating can be set to a high temperature that cannot be achieved by other methods, the film-forming property of the resin layer is improved, and the resin layer and the polyester film can be adhered more firmly. Furthermore, a strong resin layer can be obtained, and the performance such as migration resistance and heat and humidity resistance to various functional layers that can be formed on the resin layer can be improved.

[0143] Also, regardless of whether it is offline coating or inline coating, heat treatment and irradiation with active energy rays such as ultraviolet irradiation may be used in combination as necessary. The polyester film constituting this release film may be subjected to a surface treatment such as corona treatment or plasma treatment in advance.

[0144] The coating amount (after dry stretching) of the non-volatile component of the resin layer is preferably 0.005 to 1.0 g / m 2 、more preferably 0.01 to 0.5 g / m 2 、even more preferably 0.03 to 0.2 g / m 2 is. If the coating amount is within this range, the desired performance (release property or prevention of ceramic green sheet adhesion) can be exhibited. The coating amount can be calculated from the non-volatile component concentration of the coating solution, the coating amount before drying derived from the consumption amount of the coating solution, the transverse stretching ratio, etc.

[0145] <<<Physical properties of the release film>>> 〔Arithmetic mean height (Sa)〕 From the perspective of improving anti-scratch properties, lengthening the release film roll, and accommodating the thinning of the ceramic green sheet, the arithmetic mean height (Sa) of the resin layer A surface of the release film is preferably 5 nm or less, more preferably 3 nm or less. On the other hand, regarding the lower limit value, from the perspective of film handling properties, 1 nm or more is preferable. By setting the arithmetic mean height (Sa) of the resin layer A surface of the release film within the above range, it is easy to prevent defects such as pinholes due to fine irregularities on the release film surface, and it is easy to suppress a decrease in anti-scratch properties. Also, it can easily accommodate the lengthening of the release film and the thinning of the ceramic green sheet. On the other hand, when the arithmetic mean height (Sa) is 1 nm or more, it can prevent the film surface from being extremely flattened, suppress a decrease in the slipperiness of the film, and suppress a decrease in anti-scratch properties. Also, it can easily accommodate the lengthening of the release film.

[0146] From the perspective of improving film winding properties, the arithmetic mean height (Sa) of the resin layer B surface of the release film is preferably 15 nm or more, more preferably 20 nm or more, and even more preferably 25 nm or more. On the other hand, regarding the upper limit value, from the perspective of reducing roughness transfer to the release surface, it is preferably 40 nm or less, preferably 35 nm or less. By setting the arithmetic mean height (Sa) of the resin layer B surface within the above range, the anti-adhesion property of the ceramic green sheet to the resin layer B can be more effectively enhanced.

[0147] The arithmetic mean height (Sa) is one of the surface roughness parameters (ISO 25178), which is an extension of two-dimensional Ra to three dimensions. It is the volume of the portion surrounded by the surface shape curved surface and the average surface divided by the measurement area, and is obtained from the following formula (1). When the surface is the XY plane and the height direction is the Z axis, assuming A: the defined region (the entire image), and Z(x, y): the height from the plane of height 0 of the image point (x, y), it is expressed as the following formula (1).

[0148]

Equation

[0149] 〔Maximum peak height (Sp)〕 The maximum peak height (Sp) of the resin layer A side of the release film is preferably 70 nm or less, more preferably 65 nm or less. By setting the maximum peak height (Sp) of the resin layer A side of the release film within the above range, it becomes possible to prevent defects such as pinholes due to the unevenness on the surface of the release film, or to ensure damage prevention, and also to cope with the elongation of the release film and the thinning of the ceramic green sheet. Also, there is no particular limitation on the lower limit of the maximum peak height (Sp), but from the viewpoint of improving the winding property of the release film, 5 nm or more is preferable, 10 nm or more is more preferable, and 15 nm or more is even more preferable.

[0150] On the other hand, the maximum peak height (Sp) of the resin layer B side of the release film is preferably 1300 nm or less, more preferably 1250 nm or less, and even more preferably 1200 nm or less. Also, the lower limit value of the maximum peak height (Sp) of the resin layer B side of the release film is preferably 100 nm or more, more preferably 200 nm or more, and even more preferably 400 nm or more. By setting the maximum peak height (Sp) of the resin layer B side of the release film within the above range, the film winding property can be made good. Also, by setting the maximum peak height (Sp) of the resin layer B side within the above range, the adhesion prevention property of the ceramic green sheet to the resin layer B can be more effectively enhanced.

[0151] The maximum peak height (Sp) is one of the surface roughness parameters (ISO 25178), represents the maximum value of the height from the average surface of the surface, and is expressed as the following formula (2).

[0152]

Equation

[0153] Further, the ratio Sp / Sa of the maximum peak height (Sp) to the arithmetic mean height (Sa) on the A side of the resin layer of the release film is preferably 10 or more, more preferably 20 or more, and even more preferably 30 or more. By satisfying the ratio Sp / Sa of the maximum peak height (Sp) to the arithmetic mean height (Sa) within the above range, the arithmetic mean height (Sa) can be minimized as much as possible, and yet the maximum peak height (Sp) can be adjusted in a relatively high state of balance, making it easier to form the thin-film ceramic green sheet. Therefore, it is possible to cope with the thinning of the ceramic green sheet. Further, by setting the ratio Sp / Sa of the resin layer B surface within the above range, the adhesion prevention property of the ceramic green sheet to the resin layer B can be more effectively enhanced. Note that the condition of the ratio Sp / Sa of the maximum peak height (Sp) to the arithmetic mean height (Sa) is not particularly limited. However, from the viewpoint of adjusting in a balance of low Sa and high Sp, it is preferably 50 or less, more preferably 45 or less, and particularly preferably 40 or less among them.

[0154] 〔Water droplet contact angle〕 The water droplet contact angle on the surface of the resin layer B is preferably 105° or less, more preferably 103° or less, and particularly preferably 100° or less among them. By setting the water droplet contact angle on the surface of the resin layer B within the above range, the adhesion prevention property of the ceramic green sheet to the resin layer B can be more effectively enhanced.

[0155] 〔Tape peel strength〕 The peel strength of the surface of the resin layer B against the acrylic adhesive tape is preferably 2000 mN / cm or less, more preferably 1500 mN / cm or less, even more preferably 1300 mN / cm or less, still more preferably 1100 mN / cm or less, and particularly preferably 1000 mN / cm or less. By setting the peel strength within the above range, the adhesion prevention property of the ceramic green sheet to the resin layer B can be more effectively enhanced from the aspect of physical factors.

[0156] 〔Surface resistivity〕 The surface resistivity (23°C ± 2°C, relative humidity 50 ± 10%) of the surface of the resin layer B is 1.0×1012 It is preferably Ω or less, more preferably 1.0×10 11 Ω or less, still more preferably 1.5×10 10 Ω or less. By setting the surface specific resistance of the resin layer B surface within the above range, sticking of the ceramic green sheet to the resin layer B due to charging can be more effectively prevented.

[0157] 〔Coefficient of kinetic friction〕 The coefficient of kinetic friction between the surface of the resin layer A and the surface of the resin layer B is preferably 0.20 or less, more preferably 0.18 or less, and still more preferably 0.16 or less. By setting the coefficient of kinetic friction within the above range, the handleability of the release film can be improved.

[0158] 〔Thickness〕 The overall thickness of the release film is preferably 9 μm or more, more preferably 10 μm or more, and still more preferably 12 μm or more. Also, the overall thickness of the release film is preferably 50 μm or less, more preferably 45 μm or less, and still more preferably 42 μm or less. By setting the thickness of the release film within the above range, the handleability of the release film can be improved.

[0159] <<<Effects and applications>>> The release film of this embodiment is suitable for forming a ceramic green sheet. The release film of this embodiment is preferably used as a support for a ceramic green sheet in the manufacturing process of a multilayer ceramic capacitor. Among them, the release film of this embodiment is preferably used as a support for a ceramic green sheet in the manufacturing process of an automotive ceramic capacitor. The release film of this embodiment is particularly suitable for forming a thin-film ceramic green sheet, and the thickness (after drying) of the thin-film ceramic green sheet is preferably 2 μm or less.

[0160] In particular, even when the release film of the present embodiment is wound up in a state where a thin-film ceramic green sheet with a thickness (after drying) of 2 μm or less is laminated, the ceramic green sheet does not stick to the back surface (anti-release surface), and it is a release film excellent in winding property and unwindability. In the present embodiment, a thin-film ceramic green sheet is laminated on the resin layer A of the release film. When wound up in a roll in this state, the thin-film ceramic green sheet and the resin layer B will be laminated, but in the present embodiment, adhesion of the ceramic green sheet to the resin layer B is suppressed. Therefore, it is possible to provide a release film excellent in winding property and unwindability and excellent in handleability.

[0161] Also, since the surface of the resin layer B of the release film of the present embodiment has a fine concavo-convex structure, for example, when used for forming a ceramic green sheet, the winding property during winding up in a roll can be improved. In addition, since the surface of the resin layer B has a fine concavo-convex structure, there is an advantage that good winding property is exhibited and wrinkles are less likely to occur even when the release film is wound up in a roll.

[0162] Furthermore, since the release film of the present embodiment has an appropriately thin thickness, it can also cope with the elongation of the release film, and can contribute to the improvement of productivity by reducing the switching frequency of the release film roll during processing.

[0163] The present embodiment may relate to a release film with a ceramic green sheet, in which a ceramic green sheet is laminated on the resin layer A of the above-described release film, or may relate to a release film with a ceramic green sheet used in the manufacturing process of automotive ceramic capacitors. The release film with a ceramic green sheet is used in the manufacturing process of laminated ceramic capacitors. Also, the thickness (after drying) of the ceramic green sheet may be 2 μm or less, may be 1 μm or less, or may be 0.5 μm or less.

[0164] This embodiment may relate to the use of the above-described polyester film as a support for a ceramic green sheet in the manufacturing process of a multilayer ceramic capacitor. Further, this embodiment may relate to a method for manufacturing a ceramic green sheet, which includes a step of coating a ceramic slurry containing a ceramic component on the surface layer side of the above-described polyester film.

Examples

[0165] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

[0166] <Evaluation Method> (1) Intrinsic viscosity (IV) of the polyester film 1 g of a polyester film from which components incompatible with polyester had been removed was precisely weighed, 100 mL of a mixed solvent of phenol / tetrachloroethane = 50 / 50 (mass ratio) was added and dissolved, and the intrinsic viscosity (IV) was measured at 30°C using a viscosity measuring device "VMS-022UPC·F10" (manufactured by Separation Co., Ltd.).

[0167] (2) Average particle size (average primary particle size) The average particle size of the particles was measured by observing the diameters of 10 or more particles with a scanning electron microscope (SEM), and the average value was obtained. In the case of non-spherical particles, the average value of the longest diameter and the shortest diameter was measured as the diameter of each particle.

[0168] (3) Method for measuring the film thickness of the resin layer The surface of the resin layer was stained with RuO 4 and embedded in an epoxy resin. Thereafter, the sections prepared by the ultra-thin section method were stained with RuO 4 and the thickness of the cross-section of the resin layer was measured using a TEM (H-7650 manufactured by Hitachi High-Technologies Corporation, acceleration voltage 100 V).

[0169] (4) Water droplet contact angle The release film was conditioned for 24 hours or more in an environment of 23°C and 50% relative humidity. Then, using an automatic contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., model DMo-501), the water droplet contact angle on the surface (B side) of resin layer B of the release film after 60 seconds was measured.

[0170] (5) Tape peel strength An adhesive tape (Nitto Denko Corporation's "No. 31B", thickness 50 μm) was pressure-bonded once back and forth on the surface (B side) of resin layer B of the release film with a 2 kg rubber roller, and the peel strength after leaving it at room temperature for 1 hour was measured. When measuring the peel strength, "AGX-plus" manufactured by Shimadzu Corporation was used, and 180° peeling was performed under the condition of a tensile speed of 300 mm / min.

[0171] (6) Surface resistivity The release film was conditioned for 30 minutes in an environment of 23°C and 50% relative humidity. Then, using a high-resistance resistivity meter: High Resista UX MCP-HT800 manufactured by Nitto Seiko Analytic Co., Ltd. and a measuring electrode: UR-100, a measurement was performed by applying a voltage of 500 V to the surface (B side) of resin layer B of the release film, and the value after 1 minute was taken as the surface resistivity. If the resistance value exceeded the upper limit of the measurable range, the measurement was considered impossible.

[0172] (7) Arithmetic mean height (Sa), maximum peak height (Sp) The arithmetic mean height (Sa) and maximum peak height (Sp) of the measurement surface (the surface of resin layer A and the surface of resin layer B) were measured as follows. Using a non-contact surface / layer cross-sectional shape measurement system VertScan (registered trademark) R550GML manufactured by Rhodia Systems Co., Ltd., with a CCD camera: SONY HR-50 1 / 3', an objective lens: 20 times, a lens barrel: 1X Body, a zoom lens: No Relay, a wavelength filter: 530 white, and a measurement mode: Wave, a region of a measurement surface of 640 μm × 480 μm was measured. Using the output by fourth-order polynomial correction, the arithmetic mean height (Sa) and maximum peak height (Sp) of each surface were averaged over 10 points.

[0173] (8) Coefficient of static friction / coefficient of kinetic friction The coefficient of static friction between the resin layer A surface (A side) and the resin layer B surface (B side) of the release film was determined by the following method. The release film was attached onto a smooth glass plate with a width of 10 mm and a length of 100 mm, and the frictional force between the resin layer A surface (A side) and the resin layer B surface (B side) was measured by sliding another release film cut into a width of 18 mm and a length of 120 mm thereon. Specifically, another release film was pressed against a metal pin with a diameter of 8 mm, and the metal pin was slid in the longitudinal direction of the glass plate at a weight of 30 g and a speed of 40 mm / min to measure the frictional force. The maximum value immediately after sliding was taken as the coefficient of static friction, and the average value of the coefficient of friction between 4 mm and 6 mm of sliding was evaluated as the coefficient of kinetic friction. The measurement was carried out in an atmosphere of room temperature 23 ± 1°C and relative humidity 50 ± 0.5%. Also, the number of measurements (N) was 10 times, and the average value was adopted. Coefficient of static friction (μs) = Fs / weight of weight (In the above formula, the units of Fs and Fd are g-force, and the unit of the weight of the weight is g-force) In Comparative Example 4 where the resin layer B was not provided, the exposed surface of the polyester film was used for evaluation instead of the B side.

[0174] (9) Ceramic slurry coatability The following composition made of the following materials was stirred and mixed, and dispersed for 60 minutes using a paint shaker with zirconia beads with a diameter of 0.5 mm as the dispersoid to obtain a ceramic slurry. Toluene 39.84 parts by mass Ethanol 39.84 parts by mass Barium titanate (HPBT-1 manufactured by Fuji Titanium Industry Co., Ltd.) 17.65 parts by mass Polyvinyl butyral (Esrec BM-S manufactured by Sekisui Chemical Co., Ltd.) 1.77 parts by mass DOP (dioctyl phthalate) 0.90 parts by mass Next, the obtained ceramic slurry was applied onto the resin layer A surface (release surface) of the release film using an applicator so that the thickness after drying would be 1.0 μm, and dried at 90°C for 2 minutes to form a ceramic green sheet on the resin layer A surface. The coatability of the ceramic slurry was determined according to the following criteria. (Judgment Criteria) A: Good coatability B: There is width shrinkage but can be coated C: Poor coatability (repelling occurs)

[0175] (10) Peelability of ceramic green sheet In the sample sample composed of the structure of resin layer B / polyester film / resin layer A / ceramic green sheet obtained in item (9), the ceramic green sheet was peeled from the resin layer A surface. The peeling situation at that time was judged according to the following judgment criteria. (Judgment Criteria) A: Good peelability B: Poor peelability (a part of the ceramic green sheet remains)

[0176] (11) Prevention of ceramic green sheet sticking Two sample samples composed of the structure of resin layer B / polyester film / resin layer A / ceramic green sheet obtained in item (9) were stacked in the same direction, and a pressing pressure (8.2 MPa) was applied from above and below for 5 hours. Then, when the two were peeled, the degree of peeling (anti-sticking property) between the ceramic green sheet and the resin layer B was evaluated by sensory evaluation according to the following judgment criteria. (Judgment Criteria) A: The ceramic green sheet can be easily peeled from the resin layer B B: The ceramic green sheet can be almost easily peeled from the resin layer B C: The ceramic green sheet is difficult to peel from the resin layer B (sticking can be confirmed)

[0177] (12) Charge amount when peeling the ceramic green sheet Using the two-layered sample prepared in item (11), the amount of static electricity generated when peeling the ceramic green sheet from the resin layer B was measured using a KSD-1000 device manufactured by Kasuga Electric Co., Ltd., and the maximum value of the amount of static electricity generated during peeling was defined as the charge amount at the time of peeling the ceramic green sheet. The peeling angle when peeling the ceramic green sheet was 90 degrees, and the peeling speed was 4 cm / second. Also, the measurement of the charge amount was carried out in an environment of 20°C and 50% relative humidity. The measurement of the charge amount at the time of peeling the ceramic green sheet was performed 10 times, and the average value was calculated. Also, the charge amount at the time of peeling the ceramic green sheet was judged according to the following criteria.

[0178] <Materials Used> The polyesters used in the examples and comparative examples are as follows.

[0179] (1) Production of Polyester A 100 parts by mass of dimethyl terephthalate and 65 parts by mass of ethylene glycol were charged into a transesterification reaction tank equipped with a stirrer, a temperature raising device, and a distillate separation column, and heated to 150°C to melt dimethyl terephthalate.

[0180] Next, an ethylene glycol solution of magnesium acetate tetrahydrate was added so that the addition amount of magnesium acetate to the resulting polyester was 0.09% by mass. Thereafter, the temperature was raised to 225°C over 3 hours under normal pressure, and the mixture was further stirred and held at 225°C for 1 hour and 15 minutes while distilling off methanol to carry out a transesterification reaction, and the transesterification reaction was substantially completed to obtain a polyester low polymer (oligomer).

[0181] Next, the oligomer was transferred to a polycondensation reaction tank equipped with a stirrer and a distillation tube. An ethylene glycol solution of magnesium acetate tetrahydrate was added to the oligomer after transfer so that the addition amount of magnesium acetate was 0.09% by mass based on the resulting polyester resin content. Thereafter, an ethylene glycol solution of phosphoric acid as a heat stabilizer was added so that the addition amount of phosphoric acid was 0.017% by mass based on the resulting polyester.

[0182] Next, an ethylene glycol solution of tetrabutyl titanate as a polycondensation catalyst was added to the oligomer so that the titanium atom content was 4.5 ppm by mass based on the resulting polyester. Thereafter, the pressure was reduced from 101.3 kPa to 0.4 kPa over 85 minutes and maintained at 0.4 kPa, and the temperature was raised from 225 °C to 280 °C over 2 hours and maintained at 280 °C for 1.5 hours to conduct a melt polycondensation reaction, obtaining polyester A having an intrinsic viscosity (IV) of 0.63 dl / g.

[0183] (2) Production of polyester B Calcium carbonate particles with an average primary particle size of 0.7 μm were added to polyester D which is substantially free of particles as described later in an amount of 2.0% by mass, and kneaded using a vented twin-screw kneader to obtain polyester B.

[0184] (3) Production of polyester C In the production of the above polyester A, tetrabutyl titanate was added so that the titanium atom content was 210 ppm by mass based on the resulting polyester, and polyester C having an intrinsic viscosity (IV) of 0.70 dl / g was obtained in the same manner as the production method of polyester A except for subjecting it to solid-phase polymerization.

[0185] (4) Production of polyester D In the production of the above polyester A, tetrabutyl titanate was added so that the titanium atom content was 210 ppm by mass based on the resulting polyester, and polyester D having an intrinsic viscosity (IV) of 0.63 dl / g was obtained in the same manner as polyester A except for subjecting it to solid-phase polymerization.

[0186] (5) Production of Polyester E Into the above substantially particle - free polyester D, 1.0 mass% of organic particles with an average primary particle size of 0.3 μm ((D90 - D10) / D50 = 0.46: divinylbenzene·ethylstyrene·methacrylic acid·styrene copolymer) was added, and polyester E was obtained by kneading using a vented twin - screw kneader.

[0187] (6) Production of Polyester F Into the above substantially particle - free polyester D, 0.75 mass% of alumina particles with an average primary particle size of 0.06 μm was added, and polyester F was obtained by kneading using a vented twin - screw kneader.

[0188] (7) Production of Polyester G Into the above substantially particle - free polyester C, 1.0 mass% of silica particles with an average primary particle size of 0.1 μm was added, and polyester G was obtained by kneading using a vented twin - screw kneader.

[0189] The resin compositions obtained by stirring and mixing with the compositions shown in Table 1 below were diluted with water to prepare coating liquids 1 - 9. The compounds used are as follows.

[0190]

Table 1

[0191] (A1): Long - chain alkyl group - containing compound A long - chain alkyl group - containing compound obtained by adding octadecyl isocyanate to polyvinyl alcohol with an average degree of polymerization of 500 and a saponification degree of 88 mol%.

[0192] (A2): Wax A wax emulsion obtained by the following method. In an emulsification equipment with a capacity of 1.5 L equipped with a stirrer, a thermometer, and a temperature controller, 300 g of oxidized polyethylene wax with a melting point of 105 °C, an acid value of 16 mgKOH / g, a density of 0.93 g / mL, and an average molecular weight of 5000, 650 g of ion-exchanged water, 50 g of a decaglycerin monooleate surfactant, and 10 g of a 48% potassium hydroxide aqueous solution were added. After replacement with nitrogen and sealing, it was rapidly stirred at 150 °C for 1 hour, then cooled to 130 °C, passed through a high-pressure homogenizer under 400 atmospheres, and cooled to 40 °C to obtain a wax emulsion.

[0193] (A3): Fluorine compound An aqueous dispersion of a fluorine compound polymerized with the following composition. Octadecyl acrylate / perfluorohexylethyl methacrylate / vinyl chloride = 66 / 17 / 17 (mass%)

[0194] (B1): Binder resin (acrylic resin) An aqueous dispersion of an acrylic resin polymerized with the following composition. Emulsion polymer of ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylolacrylamide / acrylic acid = 65 / 21 / 10 / 2 / 2 (mass%) (emulsifier: anionic surfactant)

[0195] (B2): Binder resin (acrylic resin) An aqueous dispersion of a mixture of an acrylic resin and an oxazoline compound polymerized with the following composition. A mixture in which 90 parts by mass of an acrylic resin formed from methyl methacrylate / ethyl acrylate = 64 / 36 (mass%) and 10 parts by mass of an oxazoline compound are mixed.

[0196] (B3): Binder resin (polyester resin) An aqueous dispersion of a polyester resin copolymerized with the following composition. Monomer composition: (acid component) terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid / / (diol component) ethylene glycol / 1,4-butanediol / diethylene glycol = 56 / 40 / 4 / / 70 / 20 / 10 (mol%)

[0197] (B4): Binder resin (urethane resin) When the polyester polyol composed of 282 parts by mass of terephthalic acid, 282 parts by mass of isophthalic acid, 62 parts by mass of ethylene glycol, and 250 parts by mass of neopentyl glycol was used as (C1a), 876 parts by mass of (C1a), 244 parts by mass of tolylene diisocyanate, 81 parts by mass of ethylene glycol, and 67 parts by mass of dimethylolpropionic acid were neutralized with ammonia and dispersed in water (concentration 20% by mass, viscosity at 25 °C 50 mPa·s)

[0198] (B5): Binder resin (PEO resin) A compound in which polyethylene oxide is added to the polyglycerin skeleton with n = 2 in the following formula on average 40 molecules [Chemical formula]

[0199] (B6): Binder resin (polyester resin) An aqueous dispersion of a polyester resin copolymerized with the following composition Monomer composition: (acid component) terephthalic acid / isophthalic acid / sulfoisophthalic acid / / (diol component) ethylene glycol / neopentyl glycol = 49 / 48 / 3 / / 50 / 50 (mol%)

[0200] (B7): Binder resin (polyester resin) An aqueous dispersion of a polyester resin copolymerized with the following composition Monomer composition: (acid component) 2,6-naphthalenedicarboxylic acid / 5-sodium sulfoisophthalic acid / / (diol component) ethylene glycol / diethylene glycol = 92 / 8 / / 80 / 20 (mol%)

[0201] (C1): Antistatic agent A polymer polymerized with the following composition having a pyrrolidinium ring in the main chain Diallyldimethylammonium chloride / dimethylacrylamide / N-methylolacrylamide = 90 / 5 / 5 (mol%). Number average molecular weight is about 30,000.

[0202] (C2): Antistatic agent PEDOT / PSS A conductive agent composed of polyethylene dioxythiophene and polystyrene sulfonic acid (Orgacon ICP1010 manufactured by Agfa-Gevaert) was neutralized with concentrated aqueous ammonia to a pH of 9 (non-volatile component; 1.2 mass%, solvent; water).

[0203] (D1): Crosslinking agent Melamine compound: Hexamethoxymethylol melamine

[0204] (D2): Crosslinking agent Epoxy compound: Polyglycerol polyglycidyl ether

[0205] (E1): Surfactant A nonionic surfactant having a structure with polyethylene oxide in the side chain, represented by the following formula

Chemical formula

[0206] (E2): Surfactant A fluorine-based nonionic surfactant having a branched perfluoroalkenyl group in the hydrophobic group and a polyethylene oxide chain (average chain length 8 units) in the hydrophilic group

[0207] (F): Particles Silica particles with an average particle size (primary average particle size) of 0.07 μm

[0208] (Example 1) A raw material obtained by blending polyester C at a mass ratio of 88%, polyester G at 8%, and polyester F at 4% was used as the raw material for surface layer A. A raw material with 100% polyester D was used as the raw material for intermediate layer B. A raw material obtained by blending polyester D at 28%, polyester B at 22%, and polyester E at 50% by mass was used as the raw material for surface layer C. These were respectively supplied to an extruder with a vent, and melted at 290 °C. Then, with a three-layer (A / B / C) layer structure having surface layers A and C as the outermost layer (surface layer) and intermediate layer B as the intermediate layer, coextrusion was performed so that the thickness composition ratio was A / B / C = 4 / 25.5 / 1.5. Cooling and solidification were carried out on a cooling roll with the surface temperature set at 40 °C using the electrostatic printing adhesion method to obtain an amorphous film. At this time, the side where surface layer C contacted the cooling roll was used.

[0209] Next, using the roll peripheral speed difference, the film was stretched 3.5 times in the longitudinal direction, that is, in the MD direction, at a film temperature of 86 °C, and then coating liquid 1 and coating liquid 2 described in Table 1 were respectively applied to both sides of the film. Then, it was guided to a tenter and stretched 4.2 times in the transverse direction, that is, in the TD direction, at 105 °C, heat-treated at 230 °C, and then the film was wound up in a roll around a core to obtain a release film with a thickness of about 31 μm.

[0210] (Examples 2 to 5) and (Comparative Examples 1 to 3) Except for changing to the coating liquids described in Table 2 and setting the thickness of surface layer C as described in Table 2, it was manufactured in the same manner as in Example 1 to obtain a release film with a thickness of about 31 μm.

[0211] (Comparative Example 4) In Example 1, except for not providing surface layer C (resin layer B), it was manufactured in the same manner as in Example 1 to obtain a release film with a thickness of about 31 μm.

[0212]

Table 2

[0213] From the results shown in Table 2, it was found that in the examples, the effect of preventing the ceramic green sheet from sticking to the back surface (anti-release surface) of the thin film was good. Therefore, even when the release film of this embodiment is wound into a roll, the ceramic green sheet does not stick to the back surface (anti-release surface) of the release film, and the unwindability is good. Considering the factors causing the phenomenon that the ceramic green sheet adheres to the back surface (anti-release surface) of the release film, from the perspective of 1) physical factors, it is considered the adhesive force between the film back surface (anti-release surface) and the ceramic green sheet, and from the perspective of 2) electrostatic factors, it is considered to be caused by peeling electrification. As a countermeasure against 1) physical factors, reduction of adhesiveness, more specifically, imparting release property is considered. Also, as a countermeasure against 2) electrostatic factors, imparting appropriate antistatic property is considered. It was found that in order to prevent the ceramic green sheet from sticking to the back surface (anti-release surface), first, it is necessary to impart antistatic property, and more preferably, it is necessary to achieve both appropriate release property and antistatic property. On the other hand, Comparative Examples 1 to 3 are all configuration examples of release films having a resin layer that does not use an antistatic agent on the anti-release surface. With only the release agent, simply imparting peelability, as can be read from the peel force evaluation results for the adhesive tape, it was difficult to prevent the ceramic green sheet from sticking to the back surface (anti-release surface) regardless of the magnitude of the peel force.

[0214] The present invention has found a new problem of "adhesion of the thin-film ceramic green sheet to the anti-release surface (back surface) of the release film" caused by the unique flexibility of the thin-film ceramic green sheet, especially with a thickness (after drying) of 2 μm or less, which has not been regarded as a problem in the past. By adopting the configuration of the release film of this embodiment, the above problem is solved, and the present invention has been completed.

Industrial Applicability

[0215] The release film of this embodiment is useful for forming a thin-film ceramic green sheet. In this embodiment, the film can be wound into a roll state with the ceramic green sheets laminated, and in this case, even when a thin-film ceramic green sheet with a thickness (after drying) of 2 μm or less is used, the ceramic green sheet does not adhere to the back surface (anti-release surface), and a release film with excellent handleability is provided.

Explanation of Signs

[0216] 10 Polyester film (intermediate layer B) 20 Resin layer A (surface layer A) 30 Resin layer B (surface layer C) 100 Release film

Claims

1. A polyester film is provided with a resin layer A on one side and a resin layer B on the other side, The resin layer A contains a non-silicone release agent, A release film having an electrostatic charge of 10 kV or less when peeled from the ceramic green sheet of the resin layer B under the following measurement conditions: (Measurement conditions) A ceramic green sheet having a thickness of 1.0 μm is formed on resin layer A from a composition containing 39.84 parts by mass of toluene, 39.84 parts by mass of ethanol, 17.65 parts by mass of barium titanate, 1.77 parts by mass of polyvinyl butyral, and 0.90 parts by mass of dioctyl phthalate. The ceramic green sheet and resin layer B are treated at a press pressure (8.2 MPa) for 5 hours, and then the amount of static electricity is measured when peeling the ceramic green sheet from resin layer B; the peel angle when peeling the ceramic green sheet is 90 degrees and the peel speed is 4 cm / sec.

2. The release film according to claim 1 , wherein the resin layer B comprises an antistatic agent (C).

3. The release film according to claim 2 , wherein the antistatic agent (C) is an ion-conductive polymer compound.

4. 3. The release film according to claim 2, wherein the (C) antistatic agent is at least one selected from the group consisting of (a1) a polymer in which a compound made of thiophene or a thiophene derivative is doped with another anionic compound, and (a2) a polymer in which a compound made of thiophene or a thiophene derivative has an anionic group and is self-doped.

5. The release film according to claim 1 , wherein the resin layer B comprises (A) a non-silicone release agent.

6. 6. The release film according to claim 5, wherein the non-silicone release agent (A) is at least one selected from the group consisting of waxes and compounds containing a long-chain alkyl group.

7. The release film according to claim 1 , wherein the resin layer B comprises a binder resin (B).

8. The release film according to claim 7, wherein the binder resin (B) is at least one selected from a (meth)acrylic resin and a polyvinyl alcohol.

9. The release film according to claim 1 , wherein the resin layer B contains a crosslinking agent (D).

10. The release film according to claim 9, wherein the crosslinking agent (D) is at least one selected from the group consisting of a melamine compound and an oxazoline compound.

11. 2. The release film according to claim 1, wherein the non-silicone release agent contained in the resin layer A comprises at least one selected from the group consisting of waxes and compounds containing a long-chain alkyl group.

12. The release film according to claim 1 , wherein the polyester film has a three-layer structure.

13. The release film according to claim 12 , wherein the polyester film has a three-type three-layer structure.

14. 2. The release film according to claim 1, wherein the arithmetic mean height (Sa) of the resin layer A side in the release film is 5 nm or less.

15. The release film according to claim 1, wherein the thickness of the release film is 9 to 50 μm.

16. 2. The release film according to claim 1, wherein a dynamic friction coefficient between the resin layer B surface and the resin layer A surface in the release film is 0.20 or less.

17. 2. The release film according to claim 1, which is used as a support for a ceramic green sheet in the production process of a multilayer ceramic capacitor.

18. 2. The release film according to claim 1, which is used as a support for a ceramic green sheet in the production process of an automotive ceramic capacitor.

19. A release film with a ceramic green sheet, comprising: a release film according to any one of claims 1 to 18; and a ceramic green sheet laminated on the resin layer A of the release film.

20. 20. The release film with a ceramic green sheet according to claim 19, wherein the ceramic green sheet has a thickness (after drying) of 2 μm or less.

21. The release film with the ceramic green sheet according to claim 19, which is used in a production process of a multilayer ceramic capacitor.

22. The release film with the ceramic green sheet according to claim 19, which is used in a production process of an automotive ceramic capacitor.

23. A method for producing a ceramic green sheet, comprising a step of applying a ceramic slurry containing a ceramic component to at least one surface of the release film according to any one of claims 1 to 18.

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