CN111527136B

CN111527136B - Release film for producing ceramic green sheet

Info

Publication number: CN111527136B
Application number: CN201880083606.2A
Authority: CN
Inventors: 松尾有加; 本乡有记
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2017-12-27
Filing date: 2018-12-20
Publication date: 2022-12-30
Anticipated expiration: 2038-12-20
Also published as: SG11202005633XA; JPWO2019131449A1; MY192990A; JP6822549B2; KR20200098678A; WO2019131449A1; CN111527136A; JP7017168B2; JP2020175668A; KR102518776B1

Abstract

[ problem ] to provide: a mold release film for molding a ceramic green sheet which has excellent releasability and is less likely to cause pinhole defects in an extremely thin ceramic green sheet to be molded or to cause damage such as cracks during release. [ solution ] A release film for producing a ceramic green sheet, comprising a polyester film and, laminated directly on at least one side thereof or via another layer, a release layer having a thickness of 0.2 to 3.5 [ mu ] m, wherein the surface of the release layer has a surface roughness (Sa) of 5 to 40nm in area and a maximum peak height (Rp) of 60nm or less in maximum.

Description

Release film for producing ceramic green sheet

Technical Field

The present invention relates to a mold release film for producing an ultrathin layer ceramic green sheet, and more particularly, to a mold release film for producing an ultrathin layer ceramic green sheet, which can produce an ultrathin layer ceramic green sheet in which occurrence of a step failure due to pin holes, thickness unevenness, and peeling failure is suppressed.

Background

Conventionally, a release film having a polyester film as a base material and a release layer laminated thereon has been used for molding a ceramic green sheet such as a laminated ceramic capacitor (hereinafter referred to as MLCC) or a ceramic substrate. In recent years, as the size and capacity of multilayer ceramic capacitors have been reduced, the thickness of ceramic green sheets has also tended to be reduced. The ceramic green sheet is formed by applying a slurry containing a ceramic component such as barium titanate and a binder resin to a release film and drying the slurry. After the electrodes are printed on the molded ceramic green sheets and peeled from the mold release film, the ceramic green sheets are stacked, pressed, cut, and then fired and applied to external electrodes to produce a multilayer ceramic capacitor. Conventionally, when a ceramic green sheet is formed on the surface of a release layer of a polyester film, there has been a problem that fine protrusions on the surface of the release layer affect the formed ceramic green sheet and defects such as dents and pinholes are likely to occur. Therefore, various methods for realizing a surface of a release layer having excellent flatness have been developed (for example, patent document 1).

However, in recent years, further thinning of the ceramic green sheet has been advanced, and a ceramic green sheet having a thickness of 1.0 μm or less, more specifically, 0.2 μm to 1.0 μm has been required. Therefore, the surface of the release layer is required to have higher smoothness. Further, since the strength of the ceramic green sheet is reduced as the ceramic green sheet is thinned, it is preferable that not only the surface of the release layer is smoothed, but also the peeling force when the ceramic green sheet is peeled from the release film is made low and uniform, and it is preferable to reduce the load applied to the ceramic green sheet when the ceramic green sheet is peeled from the release film as small as possible in order not to damage the ceramic green sheet.

As a method from the aspect of the release layer for smoothing the surface of the release layer and suppressing the load on the ceramic green sheet at the time of peeling, the following measures have been studied: by using an active energy ray-curable component for the release layer of the release film, the crosslinking density of the release layer is increased, and the elastic modulus is improved, whereby the elastic deformation of the release layer at the time of peeling the ceramic green sheet is suppressed, and the peeling force is reduced (for example, patent documents 2 and 3). However, in this method, since the smoothness is too high, surface peeling occurs, the peeling force becomes heavy, and cracks may be introduced into the green sheet. Further, when a ceramic green sheet is processed into an ultrathin film, if a smooth surface is brought into contact with a smooth roller or a rubber roller for controlling the tension of a coating apparatus, the slip property between the roller and the smooth surface is insufficient, and the tension control becomes unstable, resulting in a problem that the smoothness of the coated surface of the green sheet is lowered.

Thus, the following release films were reported: a release film having excellent balance between smoothness and uniform peelability is obtained by forming a polyester film having a moderately large protrusion serving as a starting point (peeling starting point) at the start of peeling (for example, patent document 4). However, in the case of a filler kneaded with PET, coarse protrusions generated by aggregation of the filler cannot be completely eliminated, and this causes a problem of becoming a defect factor of the product. In particular, in the ultrathin ceramic green sheet, the inorganic filler used as a ceramic material has a particle diameter of about 60nm to 800nm (patent documents 5 and 6), and therefore, if the film described in patent document 4 is used, there is a problem that local pores are generated in the release surface.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2000-117899

Patent document 2: international publication No. 2013/145864

Patent document 3: international publication No. 2013/145865

Patent document 4: international publication No. 2014/203702

Patent document 5: japanese patent laid-open publication No. 2016-127120

Patent document 6: japanese patent laid-open publication No. 2017-081805

Disclosure of Invention

Problems to be solved by the invention

Therefore, the present inventors have conducted intensive studies and, as a result, have found that: by continuously forming low protrusions having a constant shape on the surface of the release layer, the occurrence of the above-described re-peeling, the decrease in processing suitability, and the defect factor can be suppressed at the same time. Further, an object of the present invention is to provide: a mold release film for molding a ceramic green sheet which has excellent releasability and is less likely to cause pinhole defects in an extremely thin ceramic green sheet to be molded or to cause damage such as cracks during release.

Means for solving the problems

That is, the present invention includes the following configurations.

1. A release film for producing a ceramic green sheet, comprising a polyester film and, directly laminated on at least one surface thereof or laminated via another layer, a release layer having a thickness of 0.2 to 3.5 μm, wherein the surface roughness (Sa) of the release layer is 5 to 40nm in area and the maximum peak height (Rp) is 60nm or less.

2. The release film for manufacturing a ceramic green sheet according to the above 1, wherein the release layer is formed by curing a coating film comprising at least: an energy ray-curable compound (I) having 3 or more reactive groups in 1 molecule; a resin (II) which contains the energy ray-curable compound (I) as a sea component, is immiscible with the energy ray-curable compound (I), and forms an island component; and, a mold release component (III).

3. The release film for manufacturing a ceramic green sheet according to the above 1 or 2, wherein the release layer contains substantially no inorganic particles.

4. The release film for manufacturing a ceramic green sheet according to any one of the above 1 to 3, wherein the polyester film is a laminated polyester film comprising at least 2 layers including a surface layer A and a surface layer B on the opposite side of the surface layer A, the release layer is laminated on the surface layer A, and the surface layer A contains substantially no inorganic particles.

5. The release film for producing a ceramic green sheet according to the above 4, wherein the surface layer B contains particles, the particles are silica particles and/or calcium carbonate particles, and the total content of the particles is 5000 to 15000ppm based on the total mass of the surface layer B.

6. The release film for manufacturing a ceramic green sheet according to any one of the above 1 to 3, wherein the polyester film does not substantially contain inorganic particles, and a coating layer containing particles is laminated on a side of the polyester film on which the release layer is not laminated.

7. A method for producing a ceramic green sheet, characterized in that the ceramic green sheet is molded using the release film for producing a ceramic green sheet according to any one of the above items 1 to 6 to form a ceramic green sheet, and the ceramic green sheet after molding has a thickness of 0.2 to 1.0 μm.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the release film for producing a ceramic green sheet of the present invention, there can be provided: compared with the prior release film for manufacturing ceramic green sheets, the release film for manufacturing ceramic green sheets has no excessive weight of stripping force, excellent processability and no large protrusion in a release layer, so that defects such as pinholes and the like can be reduced in ultra-thin ceramic green sheets with the thickness of less than 1 μm to be formed.

Detailed Description

The present invention will be described in detail below.

The release film for producing an ultrathin ceramic green sheet of the present invention preferably has a release layer directly on at least one surface of a polyester film or has a release layer through another layer, and the surface roughness (Sa) of the release layer is preferably 5 to 40nm in area and the maximum peak height (Rp) is preferably 60nm or less. Further, the following release film for producing a ceramic green sheet is preferable: the release layer is formed by curing a coating film, and the coating film at least comprises: an energy ray-curable compound (I) having 3 or more reactive groups in 1 molecule; a resin (II) which is immiscible with the energy ray-curable compound (I) and forms a sea-island structure based on phase separation; and, a mold release component (III).

(polyester film)

The polyester film constituting the polyester film used as the substrate in the release film of the present invention is not particularly limited, and a polyester film obtained by film-molding a polyester generally used as a release film substrate can be used, and preferably a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component, and for example, further preferably polyethylene terephthalate, polyethylene 2,6-naphthalate, polybutylene terephthalate, polypropylene terephthalate, or a copolymer mainly composed of these resins, and particularly preferably a polyester film composed of polyethylene terephthalate. In the case of polyethylene terephthalate, the repeating unit of ethylene terephthalate is preferably 90 mol% or more, more preferably 95 mol% or more, and a small amount of other dicarboxylic acid component and diol component may be copolymerized, and a polyester film produced from only terephthalic acid and ethylene glycol is preferable from the viewpoint of cost. In addition, known additives such as an antioxidant, a light stabilizer, an ultraviolet absorber, a crystallizing agent, and the like may be added within a range not to impair the effects of the film of the present invention. The polyester film is preferably a polyester film for the reason of high elastic modulus in both directions.

The intrinsic viscosity of the polyethylene terephthalate film is preferably 0.50 to 0.70dl/g, more preferably 0.52 to 0.62dl/g. When the intrinsic viscosity is 0.50dl/g or more, it is preferable that the breaking is not easily caused in the drawing step. On the other hand, 0.70dl/g or less is preferable because the cuttability is good and no dimensional defect is caused when the product is cut into a predetermined width. Further, the raw material is preferably sufficiently vacuum-dried.

The method for producing the polyester film in the present invention is not particularly limited, and conventionally generally used methods can be employed. This can be obtained, for example, as follows: the polyester is melted in an extruder, extruded into a film, cooled on a rotary cooling drum to obtain an unstretched film, and uniaxially or biaxially stretched to obtain the unstretched film. The biaxially stretched film can be obtained by: a method of subjecting a uniaxially stretched film in the longitudinal direction or the transverse direction to sequential biaxial stretching in the transverse direction or the longitudinal direction, or a method of subjecting an unstretched film to simultaneous biaxial stretching in the longitudinal direction and the transverse direction.

In the present invention, the stretching temperature at the time of stretching the polyester film is preferably set to be not less than the secondary transition point (Tg) of the polyester. The stretching is preferably performed 1 to 8 times, particularly 2 to 6 times in the longitudinal and transverse directions.

The thickness of the polyester film is preferably 12 to 50 μm, more preferably 12 to 38 μm, and still more preferably 15 to 31 μm. When the thickness of the film is 12 μm or more, there is no possibility of deformation due to heat at the time of film production, the step of processing the release layer, and the molding of the ceramic green sheet, and therefore it is preferable. On the other hand, if the film thickness is 50 μm or less, the amount of the film to be discarded after use is not extremely increased, which is preferable in terms of reducing the environmental load, and furthermore, the material per unit area of the release film to be used is decreased, which is also preferable from the viewpoint of economy.

The polyester film substrate may be a single layer or a plurality of layers of 2 or more layers, and is preferably a laminated polyester film having a surface layer a substantially free of inorganic particles on at least one surface thereof. In the case of a laminated polyester film comprising 2 or more layers, it is preferable that the surface layer B capable of containing particles or the like is provided on the opposite side of the surface layer a substantially not containing inorganic particles. When the layer on the side to which the release layer is applied is the surface layer a, the layer on the opposite side thereof is the surface layer B, and the core layer other than these is the core layer C, examples of the layer structure in the thickness direction include a laminate structure such as release layer/surface layer a/surface layer B, or release layer/surface layer a/core layer C/surface layer B. The core layer C may be formed of multiple layers. In addition, the surface layer B may contain no particles. In the above case, in order to impart slidability for winding the film into a roll shape, it is preferable to provide a coating layer (D) containing particles and a binder on the surface layer B.

In the polyester film substrate of the present invention, the surface layer a on the side on which the coated release layer is formed preferably contains substantially no inorganic particles. In this case, the regional surface average roughness (Sa) of the surface layer a is preferably 7nm or less. When the Sa is 7nm or less, it is preferable that the film thickness of the release layer is 2.0 μm or less, and further 0.5 μm or less, since pinholes and the like are less likely to occur at the time of molding the laminated ultrathin ceramic green sheet. The smaller the area surface average roughness (Sa) of the surface layer a is, the more preferable it is, but it may be 0.1nm or more. However, when an anchor coat layer or the like described later is provided on the surface layer a, the coating layer preferably contains substantially no inorganic particles, and the region surface average roughness (Sa) after the coating layers are laminated is preferably within the above range. In the present invention, "substantially no inorganic particles" means a content defined as 50ppm or less, preferably 10ppm or less, and most preferably not more than the detection limit when the inorganic element is quantified by fluorescent X-ray analysis. This is because, even if the inorganic particles are not positively added to the film, a contaminant component derived from a foreign substance or a raw material resin or a contaminant attached to a pipe or a device in the film production process may be peeled off and mixed into the film.

In the case where the polyester film substrate in the present invention is a laminated film, the surface layer B formed on the opposite side of the surface layer a coated with the release layer preferably contains particles, particularly preferably silica particles and/or calcium carbonate particles, from the viewpoint of the slidability of the film and the ease of air bleeding. The content of the contained particles in the surface layer B is preferably 5000 to 15000ppm in terms of the total amount of the particles. In this case, the regional surface average roughness (Sa) of the thin film of the surface layer B is preferably in the range of 1 to 40nm. More preferably in the range of 5 to 35 nm. When the total of silica particles and/or calcium carbonate particles in the surface layer B is 5000ppm or more and Sa is 1nm or more, air can be uniformly released when the film is wound into a roll, and the wound form is good and the planarity is good, so that it is suitable for producing an ultrathin ceramic green sheet. Further, when the total of the silica particles and/or calcium carbonate particles is 15000ppm or less and the Sa is 40nm or less, aggregation of the lubricant does not easily occur and coarse protrusions do not occur, and therefore, when a ceramic green sheet formed into an ultra-thin layer is wound up, defects such as pinholes are not generated in the ceramic green sheet, which is preferable.

The particles contained in the surface layer B are preferably silica particles and/or calcium carbonate particles from the viewpoint of transparency and cost. Inactive inorganic particles and/or heat-resistant organic particles may be used in addition to silica and/or calcium carbonate, and examples of inorganic particles that can be used in addition to these include alumina-silica composite oxide particles and hydroxyapatite particles. Examples of the heat-resistant organic particles include crosslinked polyacrylic acid-based particles, crosslinked polystyrene particles, and benzoguanamine-based particles. In the case of using silica particles, porous colloidal silica is preferable, and in the case of using calcium carbonate particles, light calcium carbonate surface-treated with a polyacrylic acid-based polymer compound is preferable from the viewpoint of preventing the lubricant from falling off.

The average particle diameter of the particles added to the surface layer B is preferably 0.1 μm or more and 2.0 μm or less, and particularly preferably 0.5 μm or more and 1.0 μm or less. When the average particle diameter of the particles is 0.1 μm or more, the slipperiness of the release film is good, and it is preferable. Further, if the average particle diameter is 2.0 μm or less, pinholes due to coarse particles are not likely to be generated on the surface of the release layer, which is preferable. The method for measuring the average particle diameter of the particles can be performed by the following method: the particles on the cross section of the processed film were observed by a scanning electron microscope, and 100 particles were observed, and the average value thereof was taken as the average particle diameter. The shape of the particles is not particularly limited as long as the object of the present invention is satisfied, and spherical particles, irregular particles and particles other than spherical particles can be used. The particle size of the amorphous particles can be calculated as the circle-equivalent diameter. The circle-equivalent diameter is the area of the observed particle divided by the circumference ratio (pi), the square root calculated and multiplied by 2 times.

The surface layer B may contain 2 or more kinds of particles of different raw materials. Further, the particles of the same kind may be contained and have different average particle diameters.

When the surface layer B does not contain particles, the surface layer B preferably has slipperiness due to the coating layer containing particles. The means for providing the coating layer is not particularly limited, and it is preferably provided by a so-called inline coating method in which coating is performed in the production of a polyester film. In the case where a coating layer having slipperiness is provided on the surface of the polyester film on the side where the release layer is not laminated, the polyester film does not need to have the surface layers a and B, and may be a single-layer polyester film substantially containing no inorganic particles.

The area surface average roughness (Sa) of the surface layer B is preferably 40nm or less, more preferably 35nm or less, and further preferably 30nm or less. When the surface layer B or the surface of the single-layer polyester film on the side on which the release layer is not laminated has slipperiness due to the coating layer (D), the Sa of the surface is a range in which the coating layer is measured, and is preferably equivalent to the area surface average roughness (Sa) of the surface layer B.

(coating layer D)

The polyester film preferably contains at least a binder resin and particles in the coating layer D on the surface on the side where the release layer is not laminated.

(Binder resin for coating layer D)

The binder resin constituting the slip-resistant coating layer is not particularly limited, and specific examples of the polymer include polyester resins, acrylic resins, urethane resins, polyvinyl resins (e.g., polyvinyl alcohol), polyalkylene glycols, polyalkylene imines, methyl cellulose, hydroxy cellulose, and starches. Among them, polyester resins, acrylic resins, and urethane resins are preferably used from the viewpoint of retention of particles and adhesion. In addition, in view of affinity with the polyester film, the polyester resin is particularly preferable. The polyester of the binder is preferably a copolyester in order to achieve solubility in a solvent, dispersibility, and adhesion to a base film or other layers. The polyester resin may be modified with polyurethane. Another preferable binder resin constituting the easy-slip coating layer on the polyester base film is a urethane resin. The urethane resin may be a polycarbonate urethane resin. Further, the polyester resin and the polyurethane resin may be used in combination, or the other binder resins may be used in combination.

(crosslinking agent for coating layer D)

In the present invention, the slip-resistant coating layer may be formed to include a crosslinking agent in order to form a crosslinked structure in the slip-resistant coating layer. By containing the crosslinking agent, the adhesion under high temperature and high humidity can be further improved. Specific examples of the crosslinking agent include urea-based, epoxy-based, melamine-based, isocyanate-based, oxazoline-based, carbodiimide-based, and aziridine-based agents. In addition, a catalyst or the like may be suitably used as needed to promote the crosslinking reaction.

(particles in coating layer D)

The slip-resistant coating layer preferably contains lubricant particles for imparting slip properties to the surface. The particles may be inorganic particles or organic particles, and are not particularly limited, and examples thereof include (1) inorganic particles such as silica, kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, zirconium oxide, titanium dioxide, satin white, aluminum silicate, diatomaceous earth, calcium silicate, aluminum hydroxide, halloysite hydrate, calcium carbonate, magnesium carbonate, calcium phosphate, magnesium hydroxide, and barium sulfate, (2) organic particles such as acrylic acids or methacrylic acids, vinyl chloride, vinyl acetate, nylon, styrene/acrylic acids, styrene/butadiene, polystyrene/acrylic acids, polystyrene/isoprene, methyl methacrylate/butyl methacrylate, melamine, polycarbonate, urea, epoxy, urethane, phenol, diallyl phthalate, and polyester, and silica is particularly preferably used in order to provide a suitable sliding property to the coating layer.

The average particle diameter of the particles is preferably 10nm or more, more preferably 20nm or more, and further preferably 30nm or more. When the average particle diameter of the particles is 10nm or more, aggregation is less likely to occur, and the sliding property can be secured.

The average particle diameter of the particles is preferably 1000nm or less, more preferably 800nm or less, and further preferably 600nm or less. When the average particle diameter of the particles is 1000nm or less, the transparency can be maintained and the particles are preferably not exfoliated.

For example, when small particles having an average particle size of about 10 to 270nm and large particles having an average particle size of about 300 to 1000nm are used in combination, it is preferable to reduce the average width (RSm) of the contour elements while keeping the surface average roughness (Sa) and the maximum peak height (RP) of the region, which will be described later, and to achieve both sliding properties and smoothness, and it is particularly preferable to use small particles having an average particle size of 30nm to 250nm in combination with large particles having an average particle size of 350 to 600 nm. When the small particles and the large particles are used in combination, the mass content of the small particles is preferably larger than that of the large particles in advance with respect to the entire solid content of the coating layer.

In the surface layer a on the side on which the release layer is provided, it is preferable not to use a recycled material or the like in order to prevent the mixing of particles such as a lubricant or the like from the viewpoint of reducing pinholes.

The thickness ratio of the surface layer a, which is the layer on the side on which the release layer is provided, is preferably 20% to 50% of the total thickness of the base film. If the content is 20% or more, the inside of the film is less likely to be affected by particles contained in the surface layer B and the like, and the region surface average roughness Sa is preferable because the above range is easily satisfied. If the thickness of the entire layer of the base film is 50% or less, the ratio of the recycled material used in the surface layer B can be increased, and the environmental load is small, which is preferable.

From the viewpoint of economy, 50 to 90 mass% of film scrap or recycled material for plastic bottles can be used for the layers other than the surface layer a (the surface layer B or the core layer C). In the above case, the type, amount, particle diameter, and region surface average roughness (Sa) of the lubricant contained in the surface layer B preferably satisfy the above ranges.

In addition, in order to improve the adhesion of a release layer or the like to be applied later, to prevent charging, or the like, a coating layer may be provided on the surface of the surface layer a and/or the surface layer B before stretching in the film-forming step or after uniaxial stretching, or corona treatment or the like may be performed. When the coating layer was further provided, the Sa of each layer was substituted by the measured value of the surface of the coating layer. In addition, when these coating layers are provided on the surface of the surface layer a, it is preferable that no particles are contained.

(Release layer)

The release layer of the present invention is preferably formed by curing a coating film comprising at least: an energy ray-curable compound (I) having 3 or more reactive groups in 1 molecule; a resin (II) which is immiscible with the energy ray-curable compound (I) and phase-separates to form a sea-island structure; and, a mold release component (III). The energy ray-curable compound (I) and the resin (II) are phase-separated to form a sea-island structure, and thus, unevenness having an appropriate height can be easily formed without generating coarse protrusions, and thus, pinholes and the like are not generated in the green sheet. Further, since the flat portion is almost eliminated and is peeled as a dot, even a brittle ultrathin ceramic green sheet can be peeled without being pulled, and thus damage such as cracking and deformation can be suppressed.

(energy ray-curable Compound (I) having 3 or more reactive groups in 1 molecule.)

As the energy ray-curable compound (I) used in the present invention, an energy ray-curable compound having 3 or more reactive groups in 1 molecule can be used. The release layer has 3 or more reactive groups in 1 molecule and has a high elastic modulus, and can suppress deformation of the release layer at the time of green sheet peeling and re-peeling. Further, since the solvent resistance of the release layer can be improved, it is preferable to prevent the corrosion of the release layer by the solvent when coating the slurry. The energy ray-curable compound having 3 or more reactive groups in 1 molecule is not particularly limited as long as it is directly reacted by an energy ray or indirectly reacted by an active material generated indirectly. The content of the energy ray-curable compound (I) in the solid content of the release layer-forming coating liquid is preferably 60 to 98 mass%, and more preferably 75 to 97 mass%. By adding 60% by mass or more, the degree of crosslinking can be maintained, and a high elastic modulus can be obtained.

Examples of the reactive group of the energy ray-curable compound (I) include a (meth) acryloyl group, an alkenyl group, an acrylamide group, a maleimide group, an epoxy group, and a cyclohexenyl oxide group. Among them, an energy ray-curable compound having a (meth) acryloyl group excellent in processability is preferable.

The energy ray-curable compound having a (meth) acryloyl group may be used without being limited to a monomer, an oligomer, or a polymer. Further, it is preferable to contain a compound having at least 3 reactive groups in 1 molecule, and 2 or more compounds such as a compound having 1 to 2 reactive groups in a molecule may be mixed and used. By mixing these compounds having a small number of reactive groups, curling and the like can be suppressed.

Examples of the energy ray-curable monomer having 3 or more (meth) acryloyl groups in the molecule include multifunctional (meth) acrylates such as isocyanuric acid triacrylate, glycerol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate, ethylene oxide-modified products thereof, propylene oxide-modified products thereof, and caprolactone-modified products thereof.

Examples of the energy ray-curable monomer having 1 to 2 reactive groups in the molecule include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, cyclopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, isobornyl (meth) acrylate, cyclic trimethylolpropane (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypropyl (meth) acrylate, meth) acrylic acid, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, pentamethylpiperidine (meth) acrylate, tetramethylpiperidinium (meth) acrylate, 1,4-butanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, nonanediol di (meth) acrylate, bisphenol a di (meth) acrylate, neopentyl glycol di (meth) acrylate, cyclohexanediol di (meth) acrylate, and the like, and ethylene oxide-modified products, propylene oxide-modified products, caprolactone-modified products thereof, and the like.

Examples of the energy ray-curable oligomer having 3 or more (meth) acryloyl groups in the molecule include urethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, silicone-modified acrylate, and the like, and generally commercially available products can be used. Examples thereof include BEAMSET (registered trademark) series manufactured by Mitsukawa chemical industries, NK oligo series manufactured by Newzhonghamu chemical industries, daicel Ornex Co., ltd., EBECRYL series manufactured by Ltd., biscoat series manufactured by Osaka organic chemical industries, urethane acrylate series manufactured by Kyowa chemical industries, and Unidic series manufactured by DIC.

Examples of the energy ray-curable polymer having 3 or more (meth) acryloyl groups in the molecule include graft polymers in which a (meth) acryloyl group is grafted to a polymer; and a block polymer having a polyfunctional acrylic monomer added to the polymer terminal. The polymer is not particularly limited, and an acrylic resin, an epoxy resin, a polyester resin, a polyorganosiloxane, or the like can be used.

(resin (II))

The resin (II) used in the present invention is dissolved or dispersed in the same solvent as the energy ray-curable compound (I), and both are dissolved or dispersed in the state of a coating agent, but after coating, in a release layer formed by drying and curing the solvent, a sea-island structure in which the energy ray-curable compound (I) is a sea component and the resin (II) is an island component, which are mutually immiscible, is preferably formed, and the resin (II) may be used without particular limitation as long as the above-described characteristics are satisfied. More than 2 kinds of resins may be used simultaneously. The content of the resin (II) in the solid content of the coating liquid for forming a releasing layer is preferably 1 to 40 mass%, and preferably 1 to 10 mass%. The content of 1 mass% or more is preferably 1 mass% or more, so that sufficient unevenness can be formed, and 40 mass% or less, so that the crosslinking degree of the release layer is high and the temperature dependence at the time of peeling is low.

The resin (II) is not particularly limited as long as it is a solvent-soluble resin such as a polyester resin, an acrylic resin, a urethane resin, a polyester urethane resin, a polyimide resin, a polyamideimide resin, or a cellulose resin, and is not particularly limited, and a resin that is not soluble in the energy ray-curable compound (I) is used.

The polyester resin is not particularly limited, and commercially available products can be used. Examples thereof include Vylon (registered trademark) series manufactured by Toyo Boseki K.K., nichigo polyester (registered trademark) series manufactured by Nippon synthetic chemical industry Co., ltd.

The acrylic resin refers to an oligomer or polymer obtained by polymerizing an acrylic ester, and may be a homopolymer or a copolymer. In addition, commercially available products may be used. For example, acrydic (registered trademark) series manufactured by DIC corporation, ARFON (registered trademark) series manufactured by Toyo Synthesis K.K., and the like can be cited.

Examples of the polyester urethane resin include Vylon (registered trademark) UR series manufactured by Toyo Boseki K.K.

(mold release component (III))

The release component (III) used in the present invention is not particularly limited as long as it is a material capable of exhibiting releasability between green sheets, such as polyorganosiloxane, fluorine compound, long-chain alkyl compound, wax, or the like. Further, these materials are preferably those having a functional group which can react with and bond to the energy ray-curable compound (I) having a (meth) acryloyl group or the like. Furthermore, 2 or more kinds of materials may be mixed and used. The content of the release component (III) in the solid content of the release layer forming coating liquid is preferably 0.05 to 10% by mass, and more preferably 0.1 to 5% by mass. The addition of 0.05% by mass or more is preferable because the peeling force can be reduced, and the addition of 10% by mass or less is preferable because migration of the release component to the ceramic green sheet or the like can be suppressed.

Examples of the polyorganosiloxane include polydimethylsiloxane, polydiethylsiloxane, and polyphenylsiloxane, and a siloxane compound obtained by organically modifying a part of the polyorganosiloxane, a block polymer having polyorganosiloxane, and a polymer obtained by grafting polyorganosiloxane can be used. Examples of commercially available products include BYK (registered trademark) series manufactured by BYK Japan, and Modiper (registered trademark) series manufactured by Japan oil corporation.

The fluorine compound is not particularly limited, and commercially available products can be used. For example, MEGAFACE (registered trademark) series manufactured by DIC corporation may be mentioned.

Examples of the long-chain alkyl compound include: an acrylic polymer obtained by copolymerizing a long-chain alkyl acrylate; graft polymers obtained by grafting long-chain alkyl groups; block polymers obtained by adding a long chain alkyl group to the terminal thereof, and the like. Further, the catalyst is not particularly limited, and a commercially available product can be used. Examples thereof include Tesfine (registered trademark) series manufactured by Hitachi chemical Co., ltd., and Pyroil (registered trademark) manufactured by Lion Specialty Chemicals Co., ltd.

Examples of the active energy ray include an electromagnetic wave such as infrared ray, visible ray, ultraviolet ray, and X-ray, an electron beam, an ion beam, a neutron beam, and a particle beam such as α -ray, and among them, ultraviolet ray having excellent production cost is preferably used.

The atmosphere in the case of irradiation with the active energy ray may be in a general air atmosphere or a nitrogen atmosphere. In the nitrogen atmosphere, the elastic modulus of the release layer can be improved by reducing the oxygen concentration so that the radical reaction proceeds smoothly, but if there is no practical problem even when irradiation is performed in air, it is preferable from the viewpoint of economy when irradiation is performed in air.

(photopolymerization initiator)

When a radical polymerization compound is used for the release layer of the present invention, a photopolymerization initiator is preferably added. Specific examples of the photopolymerization initiator include benzophenone, acetophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzil, diacetyl, β -chloroanthraquinone, (2,4,6-trimethylbenzyl diphenyl) phosphine oxide, and 2-benzothiazole-N, N-diethyldithiocarbamate. Particularly preferred are 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl ] -phenyl } -2-methylpropan-1-one, 1-hydroxy-cyclohexyl-phenyl-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, and 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one, which are excellent in surface curability, and among them, 2-hydroxy-2-methyl-1-phenyl-propan-1-one and 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one are particularly preferred. These may be used alone, or 2 or more kinds may be used in combination.

The amount of the photopolymerization initiator added is not particularly limited, and is preferably about 0.1 to 20 mass% based on the solid content in the coating liquid for forming a release layer, for example.

The release layer of the present invention may contain particles having a particle diameter of 1 μm or less, and preferably does not contain particles forming protrusions or the like from the viewpoint of generation of pinholes.

The release layer of the present invention may contain additives such as adhesion improving agents and antistatic agents as long as the effects of the present invention are not impaired. In order to improve the adhesion to the substrate, it is also preferable to subject the surface of the polyester film to a pretreatment such as anchor coating, corona treatment, plasma treatment, or atmospheric pressure plasma treatment before providing the release coating layer.

In the present invention, the thickness of the release layer is not particularly limited and may be set according to the purpose of use, but the release layer after curing may be in the range of 0.2 to 3.5 μm, more preferably 0.5 to 3.0 μm. When the thickness of the release layer is 0.2 μm or more, the energy ray-curable copolymer polymer has good curability, and the elastic modulus of the release layer is improved, and therefore, good release performance can be obtained. In addition, if the thickness is 3.5 μm or less, curling is not easily caused even if the thickness of the release film is reduced, and it is preferable that the ceramic green sheet is not deteriorated in traveling property in the process of molding and drying.

In the release film of the present invention, the surface of the release layer preferably has appropriate irregularities. Therefore, the regional surface average roughness (Sa) of the surface of the release layer is preferably 5 to 40nm. Further, the maximum peak height (Rp) of the surface of the release layer satisfying the Sa is preferably 60nm or less. Further, the regional surface average roughness (Sa) is preferably 5 to 20nm, more preferably 8.5 to 20nm. In this case, it is particularly preferable that the maximum peak height (Rp) is 50nm or less. When the area surface roughness (Sa) is 5nm or more, the ceramic green sheet can be easily peeled without being damaged by a slight pulling when the ceramic green sheet is peeled, even in the case of an ultra-thin green sheet. Further, if the area surface roughness (Sa) is 40nm or less, it is sufficiently smaller than the particle size of the ceramic, and does not affect the surface shape of the green sheet. If the above Sa is satisfied and the maximum peak height (Rp) of the surface of the release layer is 60nm or less, the occurrence of pinhole defects is less likely, and it is preferable. The maximum peak height (Rp) is preferably small, but when the surface average roughness (Sa) of the adjustment region is 5nm or more, the maximum peak height (Rp) may be 5nm or more, or may be 10nm or more. In order to adjust the surface roughness (Sa) and the maximum peak height (Rp) of the release layer to the ranges described above, various factors are involved, but since the surface layer a of the polyester film or the single-layer polyester film mainly contains substantially no inorganic particles, it can be said that the surface roughness of the laminated release layer is small, and there is a relationship in which the release layer contains an energy ray-curable compound (I) having 3 or more reactive groups in 1 molecule, and the energy ray-curable compound (I) is a sea component, and a resin (II) which is insoluble in the energy ray-curable compound (I) and is an island component is cured. The method of adjusting the surface roughness (Sa) and the maximum peak height (Rp) of the release layer to the above-mentioned appropriate ranges is not particularly limited, and can be preferably achieved mainly by adjusting the combination and content ratio of the materials of the energy ray-curable compound (I) and the resin (II).

The coefficient of static friction of the surface of the release layer film of the present invention is preferably 0.05 to 2.00. More preferably 0.1 to 1.00, and still more preferably 0.1 to 0.50. When the static friction coefficient is in the above range, the sliding between the roller of the coating equipment and the surface of the release layer is good, and excessive force is not applied, so that scratches on the surface of the release layer are reduced, damage to the green sheet can be reduced, and a good green sheet surface can be obtained.

The coefficient of dynamic friction of the surface of the release layer of the release film of the present invention is preferably 1.00 or less. If the above range is used, a good green sheet surface can be obtained without causing tension abnormality in the process.

When the static friction coefficient and the dynamic friction coefficient of the surface of the release layer are adjusted within the ranges described above, the adjustment method is not particularly limited in relation to the ranges of the surface roughness (Sa) and the maximum peak height (Rp) of the release layer, and can be preferably and preferably achieved by mainly adjusting the combination and the content ratio of the materials of the energy ray-curable compound (I) and the resin (II).

In the present invention, the method for forming the release layer is not particularly limited, and the following methods can be used: a coating liquid in which a mold-releasing compound is dissolved or dispersed is spread on one surface of a polyester film of a substrate by coating or the like, and the solvent or the like is removed by drying, followed by curing.

The drying temperature of the solvent drying when the release layer of the present invention is applied to the base film by solution coating is preferably 50 ℃ or more and 120 ℃ or less, more preferably 60 ℃ or more and 100 ℃ or less. The drying time is preferably 30 seconds or less, more preferably 20 seconds or less. Further, it is preferable that the solvent is dried and then irradiated with active energy rays to cause a curing reaction. As the active energy ray used in this case, ultraviolet rays, electron beams, X-rays, and the like can be used, and ultraviolet rays are preferred because they are easy to use. The dose of ultraviolet light to be irradiated is preferably 30 to 300mJ/cm in terms of light quantity ² More preferably 30 to 200mJ/cm ² . By setting to 30mJ/cm ² As described above, the curing of the composition proceeded sufficiently, and the thickness was set to 300mJ/cm ² Since the processing speed can be improved, a release film can be produced economically.

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

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

Examples

The present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. The characteristic values used in the present invention were evaluated by the following methods. Hereinafter, the weight average molecular weight may be abbreviated as Mw.

(1) Thickness of base film

From any 4 positions of the film to be measured, 4 samples of 5cm square were cut out using Millitron (Electronic micro indicator), and each 5 points (20 points in total) were measured, and the average value was defined as the thickness.

(2) Thickness of mold release layer

The thickness of the release layer was measured using an optical interferometric film thickness meter (F20, manufactured by Filmetrics Corporation). (calculated by assuming that the refractive index of the releasing layer was 1.52)

(3) Regional surface roughness (Sa), maximum peak height (Rp)

The measured value was measured under the following conditions using a non-contact surface shape measuring system (VertScan R550H-M100, manufactured by Mitsubishi systems corporation). The area surface average roughness (Sa) was an average value of 5 measurements, and the maximum peak height (Rp) was the maximum value of 5 measurements in which the maximum value and the minimum value were removed by 7 measurements.

(measurement conditions)

Measurement mode: WAVE mode

Objective lens: 50 times of

0.5 × Tube lens

(analysis conditions)

Surface correction: 4 times correction

Complementary processing: complete supplement

(4) Pinhole evaluation of ceramic Green sheet

A composition containing the following materials was stirred and mixed, and dispersed for 60 minutes using a bead mill using zirconia beads having a diameter of 0.5mm as a dispersion medium, to prepare a ceramic slurry.

Toluene 76.3 parts by mass

76.3 parts by mass of ethanol

Barium titanate (Fuji titanium Industrial Co., ltd. HPBT-1) 35.0 parts by mass

Polyvinyl butyral 3.5 parts by mass

(S-LEC (registered trademark) BM-S, manufactured by SEPER CHEMICAL CO., LTD.)

1.8 parts by mass of DOP (dioctyl phthalate)

Next, the mold release surface of the mold release film sample was coated with an applicator so that the dried ceramic green sheet became 0.8 μm, and after drying at 90 ℃ for 2 minutes, the mold release film was peeled off to obtain a ceramic green sheet.

In the central region of the obtained ceramic green sheet in the film width direction, 25cm ² In the above range, the surface of the ceramic slurry opposite to the coated surface was irradiated with light, and the occurrence of pinholes visible through the transmission of light was observed, and the occurrence was visually evaluated according to the following criteria. The assay was as follows: the average value was used for 5 measurements.

O: essentially no pinholes occurred (standard: pinholes of 2 or less per unit area measured)

Δ: occurrence of pinholes (standard: pinholes are 3 or more and 5 or less per unit area of measurement)

X: occurrence of a large number of pinholes (standard: more than 6 pinholes per unit area of measurement)

(5) Evaluation of damage to ceramic Green sheet

The release film with ceramic green sheet obtained in the above manner was cut into a 30mm width and a 80mm length, and used as a sample for measuring a peeling force. Static electricity was removed by using a static electricity remover (SJ-F020, manufactured by KEYENCE CORPORATION), and then peeling was performed by using a peeling tester (VPA-3, manufactured by Kyowa Kagaku Co., ltd.) at a peeling angle of 30 degrees, a peeling temperature of 25 degrees, and a peeling speed of 10 m/min. In the direction of peeling, a double-sided pressure-sensitive adhesive tape (No. 535A, manufactured by hiton electric corporation) was adhered to a SUS plate attached to a peeling tester, and a release film was fixed thereon so as to adhere the ceramic green sheet side to the double-sided pressure-sensitive adhesive tape, and peeling was performed so as to stretch the release film side. The surface of the ceramic green sheet after peeling in contact with the release film was observed in a range of 1250. Mu. M.times.900 μm at 100 times in the central region in the film width direction with a scanning electron microscope, and the average value of 10 measurements was used. The visual determination was performed according to the following criteria.

O: no damage upon peeling (Standard: no occurrence of cracks and deformation)

Δ: slight damage in peeling (Standard: crack and deformation 1 to 3 in the unit area of measurement)

X: severe damage in peeling (Standard: cracks and deformations are 4 or more)

The peel angle in the present evaluation method is an angle in a direction in which the release film is stretched with respect to an evaluation sample axis fixed to a peel tester. The peeling temperature is a temperature at which the fixed release film is heated by using a heater-type stage system attached to the apparatus. Using a portable thermometer (An Li instruments, HD-1400E), it was confirmed that the temperature of the measurement sample was at that temperature, and then the sample was peeled off.

(6) Coefficient of static friction and coefficient of dynamic friction

The static friction coefficient (μ s) and the dynamic friction coefficient (μ D) of the contact surface were measured under the following conditions when the surface of the release layer of the film was brought into contact with an SUS plate while being superposed on the surface of the release layer by using a Tensilon Universal testing machine ((A & D Corporation, RTG-1210) in accordance with JIS K-7125.

Test piece: width 50mm x length 60mm

Loading: 4.4kg

Test speed: 200 mm/min

The material to be rubbed: SUS plate

(production of polyethylene terephthalate pellets (PET (1)))

As the esterification reaction apparatus, a continuous esterification reaction apparatus comprising a 3-stage complete mixing tank having a stirring apparatus, a partial condenser, a raw material inlet and a product outlet was used. TPA (terephthalic acid) was set at 2 tons/hr, EG (ethylene glycol) was set at 2 moles based on 1 mole of TPA, and antimony trioxide was set at 160ppm of Sb atoms based on the amount of PET produced, and these slurries were continuously supplied to the 1 st esterification reaction vessel of the esterification reaction apparatus, and reacted at 255 ℃ with an average residence time of 4 hours under normal pressure. Then, the reaction product in the 1 st esterification reaction vessel was continuously taken out of the system and supplied to the 2 nd esterification reaction vessel, and EG distilled off from the 1 st esterification reaction vessel was supplied to the 2 nd esterification reaction vessel in an amount of 8 mass% based on the amount of PET produced, and further addedAn EG solution containing magnesium acetate tetrahydrate salt in an amount of 65ppm in terms of Mg atoms relative to the produced PET and an EG solution containing TMPA (trimethyl phosphate) in an amount of 40ppm in terms of P atoms relative to the produced PET were added thereto, and the mixture was reacted at 260 ℃ for 1 hour in an average residence time under normal pressure. Then, the reaction product in the 2 nd esterification reaction vessel was continuously taken out of the system, supplied to the 3 rd esterification reaction vessel, and kept at 39MPa (400 kg/cm) by using a high-pressure disperser (manufactured by Nippon Seiko Co., ltd.) ² ) 0.2 mass% of porous colloidal silica having an average particle size of 0.9 μm after dispersion treatment in 5 passes of the average treatment and 0.4 mass% of synthetic calcium carbonate having an average particle size of 0.6 μm to which 1 mass% of ammonium salt of polyacrylic acid per calcium carbonate is attached were added to 10% of EG slurry, and the mixture was reacted at 260 ℃ for an average retention time of 0.5 hour under normal pressure. The esterification reaction product produced in the 3 rd esterification reaction vessel was continuously supplied to a 3-stage continuous polycondensation reaction apparatus, subjected to polycondensation, filtered with a filter obtained by sintering 95% stainless steel fibers having a cut particle size of 20 μm, subjected to ultrafiltration, extruded in water, cooled, and cut into small pieces to obtain PET chips (hereinafter, abbreviated as PET (I)) having an intrinsic viscosity of 0.60 dl/g. The content of the lubricant in the PET chips was 0.6 mass%.

(production of polyethylene terephthalate pellets (PET (2))

On the other hand, in the production of the above PET chips, PET chips having an intrinsic viscosity of 0.62dl/g, which do not contain any particles such as calcium carbonate and silica, are obtained (hereinafter, referred to as PET (2)).

(production of polyethylene terephthalate pellets (PET (3))

PET flakes (hereinafter, abbreviated as PET (3)) were obtained in the same manner as PET (1) except that the type and content of the particles of PET (I) were changed to 0.75% by mass of synthetic calcium carbonate having an average particle diameter of 0.9 μm, based on 1% by mass of ammonium salt having polyacrylic acid adhered thereto per calcium carbonate unit. The content of the lubricant in the PET chips was 0.75 mass%.

(production of laminated film X1)

After drying these PET chips, they were melted at 285 ℃ and melted at 290 ℃ by different melt extruders, and 2-stage filtration was performed using a filter obtained by sintering stainless steel fibers having a 95% split particle size of 15 μm and a filter obtained by sintering stainless steel particles having a 95% split particle size of 15 μm, and the two were combined in a feed block, and laminated so that PET (1) became a surface layer B (reverse release surface side layer) and PET (2) became a surface layer a (release surface side layer), and extruded (cast) at a speed of 45 m/min into a sheet form, and by an electrostatic adhesion method, the sheet was electrostatically adhered to a casting drum at 30 ℃ and cooled to obtain an unstretched polyethylene terephthalate sheet having an intrinsic viscosity of 0.59 dl/g. The layer ratio was adjusted so that the discharge amount of each extruder was calculated to be PET (1)/(2) = 60%/40%. Subsequently, the unstretched sheet was heated by an infrared heater and then stretched 3.5 times in the machine direction at a roll temperature of 80 ℃ by a speed difference between rolls. Thereafter, the resultant was introduced into a tenter and stretched at 140 ℃ by 4.2 times in the transverse direction. Next, in the heat fixing zone, heat treatment was performed at 210 ℃. Then, 2.3% relaxation treatment was carried out at 170 ℃ in the transverse direction to obtain a biaxially stretched polyethylene terephthalate film X1 having a thickness of 31 μm. The Sa of the surface layer A and the Sa of the surface layer B of the obtained film X1 were 2nm and 29nm, respectively.

(production of laminated film X2)

The thickness of the biaxially stretched polyethylene terephthalate film X2 was adjusted by changing the casting speed without changing the layer structure and stretching conditions similar to those of the laminated film X1, and a thickness of 25 μm was obtained. The Sa of the surface layer A and the Sa of the surface layer B of the obtained film X2 were 3nm and 29nm, respectively.

(laminated film X3)

A4100 (Cosmoshine (registered trademark), toyo Kabushiki Co., ltd.) having a thickness of 25 μm was used as the laminated film X3. A4100 is constituted as follows: the film contains substantially no particles, and a coating layer containing particles is provided on the surface layer B side by in-line coating. The Sa of the surface layer A of the laminated film X3 was 1nm, and the Sa of the surface layer B was 2nm.

(example 1)

Using a reverse gravure plate, a coating solution 1 having the following composition was applied to a surface layer a of a laminate film X1 so that the thickness of a release layer after drying became2.5 μm, dried at 90 deg.C for 30 s, and irradiated with ultraviolet light to 200mJ/cm by a high pressure mercury lamp ² Thereby obtaining a release film for manufacturing an ultrathin ceramic green sheet. The obtained release film was subjected to evaluation of the thickness of the release layer, the regional surface roughness Sa, the maximum peak height Rp, pinholes in the ceramic green sheet, damage to the ceramic green sheet, static friction coefficient, and dynamic friction coefficient.

(coating liquid 1)

100.00 parts by mass of Compound (I)

(dipentaerythritol hexaacrylate, A-DPH manufactured by New Zhongcun chemical industries, ltd., solid content concentration 100%)

Resin (II) polyester resin 9.47 parts by mass

(Toyo Boseki Kabushiki Kaisha Vylon (registered trademark) RV280, solid content concentration 100% by mass)

1.26 parts by mass of mold release agent (III)

(modified polydimethylsiloxane having acryloyl group, BYK-UV3505, BYK Japan K.K., having a solid content concentration of 40% by mass.)

Photopolymerization initiator 5.25 parts by mass

(OMNIRAD (registered trademark) 907 manufactured by IGM Japan GK, 100% by mass as a solid content)

Diluting solvent (MEK/toluene = 1/1) 459.79 parts by mass

(example 2)

Resin (II) was changed to a polyester urethane resin (Vylon (registered trademark) UR1400, toyo Boseki K.K., solid content concentration 30 mass%), and the following coating liquid 2 was used. The solid content concentration of coating liquid 2 was reduced as compared with coating liquid 1 of example 1. The coating was performed so that the thickness of the release layer after drying became 1.5 μm. A release film was obtained in the same manner as in example 1, except that the coating liquid 2 was used and coating was performed so that the thickness of the release layer after drying became 1.5 μm. The obtained release film was evaluated for the thickness of the release layer, the area surface roughness Sa, the maximum peak height Rp, pinholes in the ceramic green sheet, damage to the ceramic green sheet, the coefficient of static friction, and the coefficient of dynamic friction.

(coating liquid 2)

100.00 parts by mass of Compound (I)

(dipentaerythritol hexaacrylate, A-DPH manufactured by Newzhongcun chemical industries, ltd., solid content concentration 100%)

Resin (II) polyester urethane resin 31.50 parts by mass

(Toyo Boseki Kabushiki Kaisha Vylon (registered trademark) UR1400, solid content concentration 30% by mass)

0.42 part by mass of mold release agent (III)

Photopolymerization initiator 5.25 parts by mass

Diluting solvent (MEK/toluene = 1/1) 975.42 parts by mass

(example 3)

The following coating liquid 3 in which the ratio of the release agent (III) was increased as compared with example 2 was used. The coating was performed so that the thickness of the release layer after drying became 1.8 μm. A release film was obtained in the same manner as in example 1, except that the coating solution 3 was used and coating was performed so that the thickness of the release layer after drying became 1.8 μm. The obtained release film was evaluated for the thickness of the release layer, the area surface roughness Sa, the maximum peak height Rp, pinholes in the ceramic green sheet, damage to the ceramic green sheet, the coefficient of static friction, and the coefficient of dynamic friction.

(coating liquid 3)

100.00 parts by mass of Compound (I)

Resin (II) 31.50 parts by mass of polyester urethane resin (Vylon (registered trademark) UR1400 manufactured by Toyo Boseki K.K., solid content concentration 30% by mass)

1.26 parts by mass of mold release agent (III)

Photopolymerization initiator 5.25 parts by mass

(OMNIRAD (registered trademark) 907, manufactured by IGM Japan GK Co., ltd., solid content 100 mass%)

Diluting solvent (MEK/toluene = 1/1) 982.98 parts by mass

(example 4)

Coating liquid 3 used in example 3 was applied on surface layer a of the laminate film X2. A release film was obtained in the same manner as in example 3, except that the laminated film X2 was used. The obtained release film was evaluated for the thickness of the release layer, the area surface roughness Sa, the maximum peak height Rp, pinholes in the ceramic green sheet, damage to the ceramic green sheet, the coefficient of static friction, and the coefficient of dynamic friction.

(example 5)

Coating liquid 3 used in example 3 was applied on surface layer a of the laminate film X3. A release film was obtained in the same manner as in example 3, except that the laminated film X3 was used. The obtained release film was evaluated for the thickness of the release layer, the area surface roughness Sa, the maximum peak height Rp, pinholes in the ceramic green sheet, damage to the ceramic green sheet, the coefficient of static friction, and the coefficient of dynamic friction.

Comparative example 1

In comparison with example 1, the release agent (III) was changed to polyether-modified polydimethylsiloxane having an acryloyl group (BYKUV-3500, BYK-Chemie Japan K.K., solid content concentration: 100%) without using the resin (II) and by increasing the amount of the release agent to be added, and the following coating solution 4 was used while changing the dilution solvent. A release film was obtained in the same manner as in example 1, except that the coating solution 4 was used and coating was performed so that the thickness of the release layer after drying became 1.0 μm. The obtained release film was evaluated for the thickness of the release layer, the area surface roughness Sa, the maximum peak height Rp, pinholes in the ceramic green sheet, damage to the ceramic green sheet, the coefficient of static friction, and the coefficient of dynamic friction.

(coating liquid 4)

100.00 parts by mass of Compound (I)

1.00 part by mass of mold release agent (III)

(the concentration of the solid content was 100% in the acryl-containing polyether-modified polydimethylsiloxane BYKUV-3500, BYK-Chemie Japan K.K.)

Photopolymerization initiator 5.00 parts by mass

(OMNIRAD (registered trademark) 907, IGM Japan GK company solid content concentration 100 mass%)

Diluting solvent (IPA/MEK = 3/1) 424.25 parts by mass

[ Table 1]

[ Table 2]

Industrial applicability

According to the release film for producing a ceramic green sheet of the present invention, compared with a conventional release film for producing a ceramic green sheet, the release film for producing a ceramic green sheet is excellent in processability without excessively increasing the peeling force, and has no large protrusion in the release layer, and therefore, it is possible to provide a release film for producing a ceramic green sheet capable of reducing defects such as pinholes in an ultra-thin ceramic green sheet having a thickness of 1 μm or less to be formed.

Claims

1. A release film for producing a ceramic green sheet, comprising a polyester film and, directly laminated on at least one surface thereof or laminated via another layer, a release layer having a thickness of 0.2 to 3.5 μm, wherein the surface roughness (Sa) of the release layer is 5 to 40nm in area and the maximum peak height (Rp) is 60nm or less,

the release layer is formed by curing a coating film, and the coating film at least comprises: an energy ray-curable compound (I) having 3 or more reactive groups in 1 molecule; a resin (II) which contains the energy ray-curable compound (I) as a sea component, is immiscible with the energy ray-curable compound (I), and forms an island component; and, a mold release component (III).

2. The release film for producing a ceramic green sheet according to claim 1, wherein the release layer contains substantially no inorganic particles, and the substantially no inorganic particles means 50ppm or less when an inorganic element is quantitatively determined by fluorescent X-ray analysis.

3. The release film for producing a ceramic green sheet according to claim 1, wherein the polyester film is a laminated polyester film comprising at least 2 layers including a surface layer A and a surface layer B on the opposite side of the surface layer A, the release layer is laminated on the surface layer A, and the surface layer A contains substantially no inorganic particles, and the substantially no inorganic particles means 50ppm or less when inorganic elements are quantitatively determined by fluorescent X-ray analysis.

4. The release film for manufacturing a ceramic green sheet according to claim 3, wherein the surface layer B contains particles, the particles are silica particles and/or calcium carbonate particles, and the total content of the particles is 5000 to 15000ppm with respect to the total mass of the surface layer B.

5. The release film for producing a ceramic green sheet according to claim 1, wherein the polyester film contains substantially no inorganic particles, and the coating layer containing particles is laminated on the side of the polyester film on which the release layer is not laminated, and the substantially no inorganic particles means 50ppm or less when an inorganic element is quantified by fluorescent X-ray analysis.

6. A method for producing a ceramic green sheet, characterized in that the ceramic green sheet is molded using the release film for producing a ceramic green sheet according to any one of claims 1 to 5, and the molded ceramic green sheet has a thickness of 0.2 to 1.0 μm.