Release film and method for producing electrode-printed ceramic green sheet

Abstract

Provided is a release film which comprises a base member and a release agent layer provided on one side of the base member. When a release force measurement sheet having a thickness of 3 μm is formed on a side opposite to the base member in the release agent layer by using a release force measurement application liquid containing 100 parts by mass of barium titanate, 8 parts by mass of a polyvinyl butyral resin, and 4 parts by mass of dioctyl phthalate, and when a post-heating release force is measured as a release force obtained by, after heating a laminate of the release force measurement sheet and the release film at 150°C for 180 seconds, releasing the release force measurement sheet from the release film at a release angle of 90° and at a release speed of 0.3 m / min under conditions of 23°C and 50% R.H., the post-heating release force is less than 70 mN / 40 mm. Said release film can satisfactorily release an object such as a ceramic green sheet even after subjected to a step for drying at a high temperature.

Description

Method for manufacturing release film and electrode-printed ceramic green sheet

[0001] This invention relates to a release film suitable for use in the process of manufacturing ceramic green sheets, and to a method for manufacturing electrode-printed ceramic green sheets.

[0002] Conventionally, the manufacturing of multilayer ceramic products such as multilayer ceramic capacitors and multilayer ceramic substrates involves forming ceramic green sheets, stacking multiple of these sheets, and then firing them.

[0003] Ceramic green sheets are formed by coating a ceramic slurry containing ceramic materials such as barium titanate and titanium oxide onto a release film. The release film used is one in which a silicone-based compound such as polysiloxane has been treated to release the film substrate. This release film is required to have release properties that allow the thin ceramic green sheet formed on it to be peeled off the film without tearing or other damage.

[0004] As an example of the above-mentioned release film, Patent Document 1 discloses a release film comprising a release layer formed from a release agent composition containing melamine resin, polyorganosiloxane, polyalkylene glycol, and a dispersant.

[0005] Patent No. 7082890

[0006] Incidentally, electrode printing is sometimes performed on ceramic green sheets. In particular, after forming the ceramic green sheet on a release film, electrode printing is performed on the side of the ceramic green sheet opposite to the release film while it is still placed on the release film. These electrodes are usually printed by applying a printing paste, which is obtained by kneading the metal and resin components that will be the electrode materials with a high-boiling point solvent, to the ceramic green sheet and drying it at a high temperature.

[0007] The inventors have discovered that when performing electrode printing with high-temperature drying as described above using a conventional release film, the printed ceramic green sheet may not peel off properly from the release film, sometimes resulting in the ceramic green sheet breaking.

[0008] This invention has been made in view of the above circumstances, and aims to provide a release film that can reliably peel off objects such as ceramic green sheets, even after undergoing a drying process at high temperatures.

[0009] To achieve the above objective, firstly, the present invention provides a release film comprising a base material and a release agent layer provided on one side of the base material, wherein a 3 μm thick release force measuring sheet is formed on the side of the release agent layer opposite to the base material using a coating solution for measuring release force containing 100 parts by mass of barium titanate, 8 parts by mass of polyvinyl butyral resin, and 4 parts by mass of dioctyl phthalate, and after heating the laminate of the release force measuring sheet and the release film at 150°C for 180 seconds, the post-heating release force measured when the release force measuring sheet is peeled from the release film at a peeling angle of 90° and a peeling speed of 0.3 m / min under conditions of 23°C and 50% R.H. is less than 70 mN / 40 mm (Invention 1).

[0010] In the above invention (Invention 1), it is preferable that the peeling force after heating is 10 mN / 40 mm or more (Invention 2).

[0011] In the above inventions (Inventions 1 and 2), it is preferable that the peeling force measured before heating, which is measured when the peeling force measured sheet is peeled from the release film at a peeling angle of 90° and a peeling speed of 0.3 m / min under conditions of 23°C and 50% R.H., is 10 mN / 40 mm or more and 65 mN / 40 mm or less (Invention 3).

[0012] In the above inventions (Inventions 1 to 3), after forming a 3 μm thick peeling force measuring sheet on the side of the release agent layer opposite to the substrate using a coating solution for peeling force measurement containing 100 parts by mass of barium titanate, 8 parts by mass of polyvinyl butyral resin, and 4 parts by mass of dioctyl phthalate, and then peeling the peeling force measuring sheet from the release film at a peeling angle of 90° and a peeling speed of 0.3 m / min under conditions of 23°C and 50% R.H., it is preferable that the rate of change of the peeling force before and after heating, calculated from the formula change rate (%) = (peeling force after heating - peeling force before heating) / peeling force before heating × 100, is 50% or less (Invention 4).

[0013] In the above inventions (inventions 1 to 4), it is preferable that the arithmetic mean height Sa on the surface of the release agent layer opposite to the substrate is less than 10 nm (invention 5).

[0014] In the above inventions (Inventions 1 to 5), the release agent layer is preferably a cured product of a release agent composition containing an active energy ray curable component and a silicone-based component (Invention 6).

[0015] In the above inventions (Inventions 1 to 6), it is preferable that they are for use in the ceramic green sheet manufacturing process (Invention 7).

[0016] Secondly, the present invention provides a method for manufacturing an electrode-printed ceramic green sheet, which includes forming a ceramic green sheet on the side of the release agent layer of the release film (Inventions 1 to 7), printing electrodes on the side of the ceramic green sheet opposite to the release film, and peeling the electrode-printed ceramic green sheet from the release film (Invention 8).

[0017] The release film according to the present invention can reliably peel off objects such as ceramic green sheets, even after undergoing a drying process at high temperatures.

[0018] Embodiments of the present invention will be described below. The release film according to this embodiment comprises a substrate and a release agent layer provided on one side of the substrate.

[0019] Furthermore, the release film according to this embodiment satisfies the conditions for release force described below. First, as a prerequisite, a 3 μm thick sheet for measuring release force is formed on the side of the release agent layer opposite to the substrate (hereinafter sometimes referred to as the "release surface") using a coating solution for measuring release force containing 100 parts by mass of barium titanate, 8 parts by mass of polyvinyl butyral resin, and 4 parts by mass of dioctyl phthalate. After heating the laminate of the sheet for measuring release force and the release film at 150°C for 180 seconds, the sheet for measuring release force is peeled from the release film according to this embodiment at a peeling angle of 90° and a peeling speed of 0.3 m / min under conditions of 23°C and 50% R.H. The release force measured at this point is defined as the "post-heating release force." The release film according to this embodiment has a post-heating release force of less than 70 mN / 40 mm. Note that the post-heating release force can be measured if the thickness of the sheet for measuring release force is 3 μm when rounded to the first decimal place.

[0020] Generally, when electrode printing is performed on a ceramic green sheet formed on a release film, as mentioned above, the process involves drying at high temperatures. The inventors hypothesized that during this printing process, the adhesion of the ceramic green sheet to the release film increases, resulting in peeling defects such as the ceramic green sheet breaking when separating it from the release film.

[0021] In the release film according to this embodiment, by satisfying the above-mentioned post-heating release force conditions, it is possible to successfully release objects such as ceramic green sheets without the above-mentioned release defects occurring even after going through a high-temperature drying process.

[0022] Furthermore, from the viewpoint of making it easier to improve peelability after the high-temperature drying process, the post-heating peeling force is preferably 50 mN / 40 mm or less, more preferably 40 mN / 40 mm or less, and particularly preferably 30 mN / 40 mm or less.

[0023] On the other hand, regarding the lower limit of the post-heating peeling force, from the viewpoint of easily suppressing the ceramic green sheet or other object from unintentionally lifting or peeling off from the release film, it is preferable that it be 10 mN / 40 mm or more, particularly preferably 14 mN / 40 mm or more, and even more preferably 18 mN / 40 mm or more.

[0024] Further details regarding the method for measuring the peeling force after heating are as described in the test examples below.

[0025] 1. Substrate The substrate in this embodiment is not particularly limited, and any conventionally known substrate can be appropriately selected and used. Examples of such substrates include films made of polyester such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene and polymethylpentene, polycarbonate, and plastics such as ethylene-vinyl acetate copolymer. These may be single layers or multilayer layers of two or more of the same or different materials.

[0026] Among the above, polyester film is preferred, polyethylene terephthalate film is particularly preferred, and biaxially oriented polyethylene terephthalate film is even more preferred. Polyethylene terephthalate film is less likely to generate dust during processing and use, and therefore can effectively prevent defects in ceramic slurry coating caused by dust, for example.

[0027] The surface of the substrate facing the release agent layer may be subjected to surface treatment such as oxidation or primer treatment in order to improve the adhesion of the release agent layer. Examples of oxidation methods include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone treatment, and ultraviolet irradiation treatment. These surface treatment methods are appropriately selected depending on the type of substrate, but corona discharge treatment is generally preferred in terms of effectiveness and ease of operation.

[0028] The thickness of the substrate can be selected as appropriate, usually 10 to 300 μm, preferably 15 to 125 μm, and particularly preferably 20 to 80 μm.

[0029] The arithmetic mean roughness Ra of the substrate surface is preferably 2 to 50 nm, and particularly preferably 5 to 30 nm. Having the arithmetic mean roughness Ra of the substrate surface within this range makes it easier to impart the desired smoothness to the peel surface, thereby facilitating the formation of a ceramic green sheet with fewer pinholes and variations in thickness.

[0030] Furthermore, it is preferable that the substrate in this embodiment substantially does not contain microbubbles. Here, microbubbles refer to bubbles with a diameter of about 3 to 50 μm. By the substrate not containing such microbubbles, the thickness accuracy of the substrate can be increased, and the surface smoothness of the resulting release film can be further improved.

[0031] 2. Release Agent Layer In this embodiment, the release agent layer is not particularly limited in composition, as long as the aforementioned post-heat release force can be achieved. From the viewpoint of making it easier to achieve the aforementioned post-heat release force, the release agent layer in this embodiment is preferably a cured product of a release agent composition containing an active energy ray curable component and a silicone-based component. Note that the mass ratios in the description of compositions such as the release agent composition are based on the active ingredient (solid content), and solvents are not included unless otherwise specified.

[0032] (1) Active Energy Ray Curable Component The active energy ray curable component is not particularly limited as long as it is a component that hardens when irradiated with active energy rays, and may be, for example, a monomer, oligomer or polymer, or a mixture thereof. The active energy ray curable component is preferably a (meth)acrylic acid ester. If the main component of the release agent layer is a cured product of a (meth)acrylic acid ester component, the ceramic slurry is less likely to be repelled in the release agent layer. In this specification, (meth)acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms.

[0033] The (meth)acrylic acid ester is preferably at least one selected from polyfunctional (meth)acrylate monomers and (meth)acrylate oligomers, and more preferably at least one selected from trifunctional or higher (meth)acrylate monomers and (meth)acrylate oligomers, and even more preferably trifunctional or higher (meth)acrylate monomers, and particularly preferably pentafunctional or higher (meth)acrylate monomers. Having trifunctional or higher functions results in excellent curability of the release agent composition, and also better peelability of the surface of the resulting release agent layer, making it easier to reduce the post-heating peeling force mentioned above.

[0034] Examples of polyfunctional (meth)acrylate monomers include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphate di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, isocyanurate di(meth)acrylate, and trimethylolpropane. Examples include tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris((meth)acryloxyethyl) isocyanurate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, etc., with dipentaerythritol hexa(meth)acrylate being preferred. These may be used individually or in combination of two or more.

[0035] Examples of the polyfunctional (meth)acrylate oligomers include polyester acrylate oligomers, epoxy acrylate oligomers, urethane acrylate oligomers, polyether acrylate oligomers, polybutadiene acrylate oligomers, silicone acrylate oligomers, and the like.

[0036] The polyester acrylate oligomers can be obtained, for example, by esterifying the hydroxyl groups of a polyester oligomer having hydroxyl groups at both ends, which is obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol, with (meth)acrylic acid, or by esterifying the terminal hydroxyl groups of an oligomer obtained by adding an alkylene oxide to a polyvalent carboxylic acid with (meth)acrylic acid.

[0037] The epoxy acrylate oligomers can be obtained, for example, by reacting (meth)acrylic acid with the oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolac type epoxy resin for esterification. Also, a carboxyl modified type epoxy acrylate oligomer obtained by partially modifying the epoxy acrylate oligomer with a dibasic carboxylic acid anhydride can be used.

[0038] The urethane acrylate oligomers can be obtained, for example, by esterifying a polyurethane oligomer obtained by the reaction of a polyether polyol or a polyester polyol and a polyisocyanate with (meth)acrylic acid.

[0039] The polyether acrylate oligomers can be obtained by esterifying the hydroxyl groups of a polyether polyol with (meth)acrylic acid.

[0040] The above polyfunctional (meth)acrylate monomers and polyfunctional (meth)acrylate oligomers can be used individually or in combination of two or more. Also, a combination of a polyfunctional (meth)acrylate monomer and a polyfunctional (meth)acrylate oligomer can be used.

[0041] In the release agent composition, the active energy ray curable component may be used alone or in combination of two or more kinds.

[0042] The blending amount of the active energy ray curable component in the release agent composition is preferably 80 to 99 parts by mass, more preferably 85 to 98 parts by mass, and particularly preferably 90 to 97 parts by mass with respect to 100 parts by mass of the release agent composition. By satisfying these conditions for the blending amount of the active energy ray curable component, it becomes difficult for the ceramics slurry to be repelled in the release agent layer, and it becomes easier to achieve the above-described peeling force after heating.

[0043] (2) Silicone-based component The silicone-based component is not particularly limited as long as it can impart desired releasability to the release surface, and polyorganosiloxane, preferably polyorganosiloxane having a reactive functional group, particularly preferably polydimethylsiloxane having a reactive functional group is used. When polyorganosiloxane having a reactive functional group is used, the reactive functional group reacts by irradiation with active energy rays or by a separate reaction step (for example, a heating step), and the polyorganosiloxane (silicone-based component) is incorporated into the crosslinked structure formed by other release agent compositions and fixed. As a result, transfer of the silicone-based component in the release agent layer to the ceramic green sheet formed on the release agent layer is suppressed. Further, from the viewpoint of more easily achieving the above-described peeling force after heating, it is more preferable that the silicone-based component is a non-aqueous type having a relatively low polarity rather than a water-based type having a relatively high polarity (easily dissolved in water and easily added to a water-containing composition).

[0044] The reactive functional group may be introduced at one end of the polyorganosiloxane, at both ends, or in the side chain. Examples of reactive functional groups include (meth)acryloyl groups, vinyl groups, maleimide groups, epoxy groups, carboxyl groups, isocyanate groups, and hydroxyl groups. Among these, (meth)acryloyl groups, vinyl groups, and maleimide groups are preferred as they can be cured simultaneously with the curing of the active energy ray-curable component (during active energy ray irradiation). It is preferable that at least two of these reactive functional groups are introduced into one molecule of polyorganosiloxane. Furthermore, two or more types of these reactive functional groups may be introduced into one molecule of polyorganosiloxane.

[0045] Furthermore, in the release agent composition, one type of silicone component may be used alone, or two or more types may be used in combination.

[0046] The amount of silicone-based components in the release agent composition is preferably 0.25 to 5 parts by mass, more preferably 0.5 to 3.5 parts by mass, and particularly preferably 1.0 to 2.5 parts by mass, per 100 parts by mass of the release agent composition. When the amount of silicone-based components satisfies these conditions, the aforementioned post-heat release force becomes easier to achieve. In particular, when the amount of silicone-based components is 0.25 parts by mass or more, the release film is more likely to exhibit good release performance. Furthermore, when the amount of silicone-based components is 5 parts by mass or less, the occurrence of ceramic slurry repulsion when the ceramic slurry is applied to the release surface becomes easier to reduce.

[0047] Furthermore, the total mass ratio of the active energy ray curable component and the silicone-based component to the total mass in the release agent composition is preferably 85% by mass or more, more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Having the total mass ratio of the active energy ray curable component and the silicone-based component within the above range makes the surface of the formed release agent layer highly smooth, making it easier to achieve the aforementioned post-heat release force, and making it easier to obtain sufficient curability of the release agent composition.

[0048] (3) When ultraviolet light is used as the active energy ray to irradiate the photopolymerization initiator release agent composition, it is preferable that the release agent composition further contains a photopolymerization initiator. By including a photopolymerization initiator in this way, the active energy ray curable component (and silicone-based component) can be cured efficiently, and the polymerization curing time and the amount of light irradiation can be reduced. Furthermore, by adjusting the photopolymerization initiator, the post-heat release force described above can be more easily achieved, and the pre-heat release force described below can also be easily adjusted to a desired value.

[0049] Examples of photopolymerization initiators include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 2-benzothiazole-N,N-diethyldithiocarbamate. In particular, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-(dimethylamino)-4'-morpholinobyrophenone, and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one are preferred, and among these, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2-benzyl-2-(dimethylamino)-4'-morpholinobyrophenone, and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one are particularly preferred from the viewpoint of making it easier to achieve the aforementioned peeling force after heating. These can be used individually or in combination of two or more types.

[0050] The amount of photopolymerization initiator added is preferably in the range of 1 to 20 parts by mass, 2 to 14 parts by mass, and particularly 3 to 9 parts by mass, per 100 parts by mass of the release agent composition.

[0051] (4) Other components The release agent layer may contain silica, antistatic agents, dyes, pigments and other additives as needed. These additives are preferably used in an amount of 10 parts by mass or less, more preferably 5 parts by mass or less, and particularly preferably 2 parts by mass or less, per 100 parts by mass of the release agent composition.

[0052] (5) Thickness of the release agent layer The thickness of the release agent layer is preferably 0.3 to 2 μm, and particularly preferably 0.5 to 1.5 μm. A thickness of 0.3 μm or more in the release agent layer makes it easier to improve the smoothness of the surface of the release agent layer, making it easier to suppress the occurrence of pinholes and thickness variations in the ceramic green sheet, and making it easier to achieve the aforementioned post-heat release force. Furthermore, a thickness of 2 μm or less in the release agent layer makes it easier to reduce the curing shrinkage of the release agent layer, making it easier to suppress the occurrence of curling of the release film. In addition, it makes it easier to suppress blocking of the release film when the release film is wound into a roll, reducing the occurrence of winding defects, and also reduces the amount of static charge during unwinding, making it easier to suppress the adhesion of foreign matter.

[0053] 3. Method for Manufacturing the Release Film The release film according to this embodiment can be manufactured by conventionally known methods. For example, the release agent composition described above or a coating solution obtained by diluting the release agent composition with an organic solvent can be applied to one side of a substrate, and then the resulting coating film can be dried as needed and cured by irradiation with active energy rays to form a release agent layer and obtain a release film. Isopropyl alcohol, methyl ethyl ketone, and the like can be used as appropriate organic solvents.

[0054] If the reactive functional groups of the silicone-based components are heat-activated, the reaction can be induced by heating during the drying of the coating film, thereby incorporating the silicone-based components into the cross-linked structure.

[0055] Methods for applying the release agent solution include, for example, gravure coating, bar coating, spray coating, spin coating, knife coating, roll coating, and die coating.

[0056] Typically, ultraviolet light and electron beams are used as active energy rays. The irradiation dose of active energy rays varies depending on the type of energy ray, but for example, in the case of ultraviolet light, it is 50 to 1000 mJ / cm². ２ Preferably, and especially 100 to 500 mJ / cm² ２ This is preferable. In the case of electron beams, a dose of about 0.1 to 50 kGy is preferable.

[0057] 4. Physical Properties of the Release Film The release film according to this embodiment satisfies the conditions for post-heating release force described above, but it is also preferable that it satisfies the following conditions for release force. First, as a prerequisite, a release force measuring sheet with a thickness of 3 μm is formed on the side of the release agent layer opposite to the substrate using a coating solution for release force measurement containing 100 parts by mass of barium titanate, 8 parts by mass of polyvinyl butyral resin, and 4 parts by mass of dioctyl phthalate. Then, under conditions of 23°C and 50% R.H., the release force measured when the release force measuring sheet is peeled from the release film at a peeling angle of 90° and a peeling speed of 0.3 m / min is defined as the "pre-heating release force". Note that the pre-heating release force can be measured if the thickness of the release force measuring sheet is 3 μm when rounded to the first decimal place.

[0058] Furthermore, the release film according to this embodiment preferably has a pre-heating release force of 10 mN / 40 mm or more, particularly preferably 14 mN / 40 mm or more, and even more preferably 18 mN / 40 mm or more. A pre-heating release force of 10 mN / 40 mm or more makes it easier to suppress the unintended shifting or peeling of the target, such as a ceramic green sheet, from the release film (especially before the high-temperature drying process). On the other hand, the upper limit of the pre-heating release force is not particularly limited, but it is preferably 65 mN / 40 mm or less, particularly preferably 45 mN / 40 mm or less, and even more preferably 35 mN / 40 mm or less. A pre-heating release force of 65 mN / 40 mm or less makes it easier to achieve the post-heating release force mentioned above. Details of the method for measuring the pre-heating release force are described in the test examples below.

[0059] Furthermore, in this embodiment, the rate of change of the release force before and after heating, calculated from the formula: Rate of change (%) = (Release force after heating - Release force before heating) / Release force before heating × 100, is preferably 50% or less, particularly preferably 35% or less, and even more preferably 20% or less. By having a rate of change of 50% or less, the release film can be used more effectively whether the temperature of the hot air in the high-temperature drying process is relatively high or relatively low. The lower limit of the rate of change is not particularly limited, and may be, for example, 0.5% or more, particularly 1% or more, and even more preferably 2% or more.

[0060] Furthermore, in the release film according to this embodiment, it is preferable that the pre-heating release force described above is generally constant within the release surface. Specifically, when the pre-heating release force is measured at any 10 points within the release surface and the average, maximum, and minimum values ​​are calculated and determined, it is preferable that the maximum value is less than 1.1 times the average value and the minimum value is less than 0.9 times the average value. When the release film according to this embodiment satisfies these conditions, the unevenness of the release force is reduced, and stable release becomes easier.

[0061] In the release film according to this embodiment, the arithmetic mean height Sa, which is an indicator of smoothness on the surface of the release agent layer opposite to the substrate, is preferably less than 10 nm, particularly preferably 8 nm or less, and even more preferably 5 nm or less. Having an arithmetic mean height Sa of less than 10 nm makes it easier to suppress the occurrence of pinholes when applying ceramic slurry to the release surface, thereby suppressing the occurrence of pinholes and thickness variations in the molded ceramic green sheet and reducing the defect rate. Details of the method for measuring the arithmetic mean height Sa are described in the test examples below.

[0062] In the release film according to this embodiment, the surface free energy on the side of the release agent layer opposite to the substrate is 23 mN / m ２ Preferably, it is 24 mN / m ２ Preferably, it is 25 mN / m ２It is preferable that the above conditions are met. Having the surface free energy within the above range makes it easier to effectively suppress the occurrence of repulsion when applying the ceramic slurry to the release surface of the release film. On the other hand, from a manufacturing standpoint, the upper limit of the surface free energy is 45 mN / m ２ The following is preferable, and in particular 40 mN / m ２ Preferably the following, and more preferably 35 mN / m ２ The following is preferable. The method for measuring the surface free energy is as shown in the test examples described later, and in particular, it is measured based on the Kitazaki-Hata theory (see Kitazaki, Yasuaki et al., Journal of the Japan Adhesion Society, Vol. 8, No. 3, 1972, pp. 131-141).

[0063] 5. Method of Use of the Release Film The release film according to this embodiment can be used as an ordinary release film, but it is particularly suitable for use in the ceramic green sheet manufacturing process. As described above, the release film according to this embodiment can be easily peeled off from the target even after going through a high-temperature drying process. For this reason, the release film according to this embodiment is particularly suitable for use in the ceramic green sheet manufacturing process, which involves a high-temperature drying process such as electrode printing. The temperature of the hot air in the high-temperature drying process may be 140°C or higher, 145°C or higher, 150°C or higher, or 150°C or higher and 160°C or lower.

[0064] In particular, the release film according to this embodiment is preferably used in the following method for manufacturing an electrode-printed ceramic green sheet. Specifically, it is preferable to use it in a method that includes forming a ceramic green sheet on the release agent layer side of the release film according to this embodiment, performing electrode printing (especially electrode printing involving a high-temperature drying process) on the side of the ceramic green sheet opposite to the release film, and peeling the electrode-printed ceramic green sheet from the release film.

[0065] In the above method, the molding of the ceramic green sheet, the electrode printing, and the peeling of the ceramic green sheet can each be carried out by known methods.

[0066] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. Accordingly, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0067] For example, other layers may be provided between the substrate and the release agent layer, or on the surface of the substrate opposite to the release agent layer.

[0068] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0069] [Example 1] (1) Preparation of the substrate A polyethylene terephthalate (PET) film (31 μm thick) with the same roughness on both sides was prepared as the substrate. The arithmetic mean roughness (Ra) on both sides of this PET film was 29 nm, and the maximum protrusion height (Rp) was 257 nm. These arithmetic mean roughness (Ra) and maximum protrusion height (Rp) were measured using the method described later.

[0070] (2) Preparation of the release agent composition Dipentaerythritol hexaacrylate (manufactured by Shin Nakamura Kogyo Co., Ltd., product name "A-DPH", solid content 100% by mass) 99.0 parts by mass (solid content equivalent, the same applies hereinafter) as an active energy ray curable component, polyether-modified acryloyl group-containing polydimethylsiloxane (low polarity silicone component for non-aqueous systems, manufactured by Big Chemie, product name "BYK-3510") 2.0 parts by mass as a silicone component, and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one (IGM Resins) as a photopolymerization initiator 5.0 parts by mass of B.V. Co.'s product "Omnirad 127D" was mixed in a mixture of isopropyl alcohol and methyl ethyl ketone (mixture ratio 3:1) to obtain a coating solution of the stripping agent composition (solid content concentration 20% by mass).

[0071] (3) Formation Step of Release Agent Layer A coating solution of the release agent composition obtained in Step (2) was applied to one side of the substrate prepared in Step (1) using a bar coater, and the obtained coating film was dried at 80°C for 1 minute. Then, the dried coating film was irradiated with ultraviolet rays under the condition of an integrated light amount of 500 mJ / cm ２ and cured. Thus, a release film having a release agent layer (thickness: 0.97 μm) formed on one side of a substrate (thickness: 31 mm) was obtained. The thickness of the release agent layer was measured by the method described below.

[0072] (4) Various Measurements The arithmetic mean roughness (Ra) and maximum protrusion height (Rp) of the above-described PET film were measured as follows. After fixing the PET film to a glass plate via double-sided tape so that the opposite surface of the side to be measured was on the glass plate side, for the surface to be measured, using a surface roughness measuring instrument (manufactured by Mitutoyo Corporation, product name "SV-3000S4", stylus type), in accordance with JIS B0601-1994, the arithmetic mean roughness (Ra; nm) and maximum protrusion height (Rp; nm) were measured.

[0073] The thickness of the above-described release agent layer was measured as follows. After cutting the obtained release film into 100×100 mm, the release film was placed on a reflection type film thickness meter (manufactured by Filmmetrics, product name "F20") so that the surface on the substrate side was on the suction stage side, and the film thickness was measured at 10 locations on the surface of the release agent layer side, and the average value was taken as the thickness (μm) of the release agent layer.

[0074] 2]] Release films were obtained in the same manner as in Example 1, except that the blending amount of the silicone-based component, the integrated light amount of ultraviolet rays, and the thickness of the release agent layer were changed as shown in Table 1.

[0075] [Comparative Example 1] A coating solution of a release agent composition (solid content concentration 30% by mass) was obtained by mixing 90 parts by mass (on a solid content basis, the same applies hereinafter) of methylated melamine resin (manufactured by Nippon Carbide Co., Ltd., product name "MW-30"), 5.0 parts by mass of terminally carbinol-modified polydimethylsiloxane as a polyorganosiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KF-6000", mass average molecular weight: 6000), and 5.0 parts by mass of p-toluenesulfonic acid as an acid catalyst in a mixed solvent of isopropyl alcohol and isobutyl alcohol (mass ratio 4:1).

[0076] The obtained coating solution was uniformly applied to one side of a biaxially oriented polyethylene terephthalate film (thickness: 38 μm) used as a substrate by a bar coater. Next, it was heated and dried at 120°C for 1 minute to cure the release agent composition. This resulted in a release film in which a release agent layer (thickness: 1.0 μm) was formed on one side of the substrate (thickness: 38 mm). The thickness of the release agent layer was measured using the method described above.

[0077] [Test Example 1] (Measurement of Peeling Force) (1) Preparation of Sample for Measurement Barium titanate powder (BaTiO) ３ A coating solution for peeling force measurement was prepared by mixing and dispersing 100 parts by mass of (product name "BT-03" manufactured by Sakai Chemical Industry Co., Ltd.), 8 parts by mass of polyvinyl butyral resin (product name "Eslec B-KBM-2" manufactured by Sekisui Chemical Co., Ltd.) as a binder, and 4 parts by mass of dioctyl phthalate (product name "Dioctyl Phthalate Grade 1" manufactured by Kanto Chemical Co., Ltd.) as a plasticizer in 135 parts by mass of a mixture of glycol monomethyl ether and toluene (mass ratio 50:50) using a ball mill.

[0078] The obtained coating solution for measuring peeling force was applied to the peeling surface of the peeling films obtained in the examples and comparative examples, and dried at 105°C for 60 seconds. This resulted in obtaining a measurement sample comprising a peeling film and a 3 μm thick peeling force measuring sheet formed on the peeling surface of the peeling film.

[0079] (2) Measurement of pre-heating peel force The sample for measurement obtained in step (1) above was cut to a width of 40 mm and left to stand for one day at 23°C and 50% R.H. Thereafter, at 23°C and 50% R.H., the sheet for measuring the peel force was peeled from the release film using a tensile testing machine at a peel angle of 90° and a peel speed of 0.3 m / min, and the force required to peel (peel force; unit: mN / 40 mm) was measured. The measurement length was set to 70 mm, and the measurement values ​​for the first 10 mm and the last 10 mm were excluded from the valid values. The average of these measurement values ​​was taken as the peel force, and this peel force measurement was performed three times, with the average value being taken as the pre-heating peel force. The results are shown in Table 1.

[0080] (3) Measurement of peeling force after heating The sample obtained in step (1) above was cut into 40 mm widths and placed in an oven (ESPEC "SPH-201") heated to 150°C. It was heated at 150°C for 180 seconds, removed, and allowed to cool to 23°C. After that, the peeling force (mN / 40 mm) was measured in the same manner as in step (2) above. This peeling force measurement was performed three times, and the average value was taken as the peeling force after heating. The results are shown in Table 1.

[0081] (4) Calculation of the rate of change Using the peeling force before heating and the peeling force after heating measured in steps (2) and (3) above, the rate of change of the peeling force before heating was calculated from the following formula: Rate of change (%) = (Peeling force after heating - Peeling force before heating) / Peeling force before heating × 100. The results are shown in Table 1.

[0082] [Test Example 2] (Measurement of Surface Roughness) The release surfaces of the release films obtained in the Examples and Comparative Examples were observed using a scanning white-light interference microscope (Hitachi High-Tech Science Co., Ltd., product name "VS-1550") under the following conditions: measurement magnification: 50x, measurement area: 251 × 251 μm, height difference: ±150 nm, and the arithmetic mean height Sa (μm) was measured. The results are shown in Table 1.

[0083] [Test Example 3] (Evaluation of Peelability) The measurement sample obtained in the same manner as in step (1) of Test Example 1 was cut to A4 size. Then, the cut measurement sample was placed in a hot air dryer (150°C, 180 seconds) to simulate the process in which printing paste solution is applied to a ceramic green sheet and dried at high temperature, and then allowed to cool to 23°C.

[0084] Next, a 180 mm x 180 mm cutting blade was inserted into the sample for measurement after cooling, from the side with the ceramic green sheet towards the side with the release film, partway through the thickness of the release film. This cut the ceramic green sheet into a closed 180 mm x 180 mm square while leaving the release film intact.

[0085] Then, the side of the sample with the release film was fixed to the suction table, and a position 10 mm from the edge of one side of a square-cut ceramic green sheet was held. The square-shaped ceramic green sheet was peeled from the release film at a peeling angle of 90° and a peeling speed of 0.3 m / min. The peelability was evaluated according to the following criteria. The results are shown in Table 1. A: The ceramic green sheet was completely peeled off without breaking. B: Minor cracks (less than 2 mm) were observed in the ceramic green sheet, but it was completely peeled off. C: The ceramic green sheet broke during the peeling process and could not be completely peeled off.

[0086] [Test Example 4] (Measurement of Surface Free Energy) For the release films obtained in the examples and comparative examples, the contact angles of various droplets with respect to the release surface of the release agent layer were measured, and based on these values, the surface free energy (mJ / m) was calculated using the Kitazaki-Hata theory. ２The contact angle was determined using a contact angle meter (Kyowa Interface Science Co., Ltd., product name "DM-701") and measured by the static droplet method in accordance with JIS R3257. For the droplets, diiodomethane was used as the "dispersion component," 1-bromonaphthalene as the "dipole component," and distilled water as the "hydrogen bonding component." Other conditions were as follows. The results are shown in Table 1. Measurement environment: 23°C, 50% RH Droplet volume: 2 μL Time from dropping to measurement: 3 seconds The average value of the contact angle measured at 6 locations using each liquid was adopted as the average value of the contact angle, and the surface free energy was calculated and adopted using this average value of the contact angle.

[0087]

[0088] As can be seen from Table 1, the release film obtained in the examples was able to successfully peel off the ceramic green sheet even after the heating process.

[0089] The release film of the present invention can be suitably used in the process of manufacturing ceramic green sheets.

Claims

1. A release film comprising a base material and a release agent layer provided on one side of the base material, wherein a 3 μm thick release force measuring sheet is formed on the side of the release agent layer opposite to the base material using a coating solution for measuring release force containing 100 parts by mass of barium titanate, 8 parts by mass of polyvinyl butyral resin, and 4 parts by mass of dioctyl phthalate, and the laminate of the release force measuring sheet and the release film is heated at 150°C for 180 seconds, and then, under conditions of 23°C and 50% R.H., the post-heat release force measured when the release force measuring sheet is peeled from the release film at a peel angle of 90° and a peel speed of 0.3 m / min is less than 70 mN / 40 mm.

2. The release film according to claim 1, characterized in that the post-heating release force is 10 mN / 40 mm or more.

3. The release film according to claim 1, characterized in that, after forming a 3 μm thick sheet for measuring peeling force on the side of the release agent layer opposite to the substrate using a coating solution for measuring peeling force containing 100 parts by mass of barium titanate, 8 parts by mass of polyvinyl butyral resin, and 4 parts by mass of dioctyl phthalate, the pre-heating peeling force measured when the sheet is peeled from the release film at a peeling angle of 90° and a peeling speed of 0.3 m / min under conditions of 23°C and 50% R.H. is 10 mN / 40 mm or more and 65 mN / 40 mm or less.

4. The release film according to claim 1, characterized in that, after forming a 3 μm thick sheet for measuring peeling force using a coating solution for measuring peeling force containing 100 parts by mass of barium titanate, 8 parts by mass of polyvinyl butyral resin, and 4 parts by mass of dioctyl phthalate on the side of the release agent layer opposite to the substrate, and then peeling the sheet from the release film at a peeling angle of 90° and a peeling speed of 0.3 m / min under conditions of 23°C and 50% R.H., the peeling force measured when the sheet is peeled off the release film is defined as the peeling force before heating, the rate of change (%) = (peeling force after heating - peeling force before heating) / peeling force before heating × 100, is 50% or less.

5. The release film according to claim 1, characterized in that the arithmetic mean height Sa on the side of the release agent layer opposite to the substrate is less than 10 nm.

6. The release film according to claim 1, characterized in that the release agent layer is a cured product of a release agent composition containing an active energy ray curable component and a silicone-based component.

7. The release film according to claim 1, characterized in that it is for use in the manufacturing process of ceramic green sheets.

8. A method for manufacturing an electrode-printed ceramic green sheet, comprising: forming a ceramic green sheet on the side of the release agent layer of the release film according to claim 1; printing electrodes on the side of the ceramic green sheet opposite to the release film; and peeling the electrode-printed ceramic green sheet from the release film.

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