Process release paper for ceramic green sheets, and ceramic green sheet and method for manufacturing the same.

Abstract

To provide a sheet with good breathability and high smoothness, which is used in the manufacturing process of ceramic green sheets and has a release layer on the surface of the paper. [Solution] Process release paper for ceramic green sheets comprising a paper layer and a release layer, wherein the release layer comprises (1) calcium carbonate and clay minerals, (2) a silicone compound, and (3) a binder resin.

Description

[Technical Field]

[0001] This invention relates to a ceramic green sheet that can be used in the manufacture of ceramic substrates used in electronic component packages, wireless communication module substrates, control circuit boards, semiconductor testing equipment, etc. It also relates to release paper used in the manufacturing process of the ceramic green sheet. [Background technology]

[0002] Conventionally, a known method for manufacturing ceramic green sheets involves forming them on a carrier film using a ceramic slurry containing ceramic components, resin components, etc. For example, a ceramic slurry is continuously coated or extruded onto a moving carrier film, and then introduced into a drying oven for heating and drying to produce a ceramic green sheet.

[0003] Furthermore, in the stage of manufacturing a ceramic substrate from a ceramic green sheet, the carrier film is peeled off the ceramic green sheet to obtain a single ceramic green sheet, and the ceramic substrate can be manufactured by firing this ceramic green sheet.

[0004] Furthermore, when using a resin film as a carrier film, it is possible to manufacture ceramic green sheets with high smoothness. However, because the resin film has poor breathability, the slurry can dry well from the open side in the drying oven, but it is difficult to dry from the side in contact with the resin film, resulting in a longer drying time.

[0005] Therefore, it has been proposed to use a sheet with a release layer on the surface of paper as the carrier film, rather than a resin film (Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-179663 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, in sheets with a release layer on the surface of the paper, it may be difficult to obtain the desired breathability depending on the material of the release layer.

[0008] Furthermore, in order to manufacture ceramic green sheets with high smoothness, it is necessary to improve the surface smoothness even in sheets that have a release layer on the surface of the paper.

[0009] The present invention aims to solve the above-mentioned problems. Specifically, the present invention aims to provide a sheet used in the manufacturing process of ceramic green sheets, which has a release layer on the surface of paper, and which has good breathability and high smoothness. [Means for solving the problem]

[0010] Therefore, after diligent research, the inventors discovered that by devising the structure of the release layer, it is possible to provide a paper-based sheet with good breathability and high smoothness, thus completing the present invention.

[0011] The present invention Paper layer, and, Exfoliation layer Process release paper for ceramic green sheets, comprising: The aforementioned peeling layer (1) Calcium carbonate and clay minerals, (2) Silicone compounds, and (3) Binder resin This is a process release paper for ceramic green sheets, which includes [the specified ingredient].

[0012] It is preferable that the calcium carbonate is light calcium carbonate.

[0013] It is preferable that the clay mineral is kaolin.

[0014] It is preferable that the silicone compound is an addition-curable silicone.

[0015] It is preferable that the binder resin is an acrylic resin.

[0016] It is preferable that the release layer further contains starch and / or modified starch.

[0017] It is preferable that the release layer is a coating layer.

[0018] The present invention relates to a step of coating a slurry of a ceramic green sheet on the process release paper for the ceramic green sheet, and a step of drying the slurry to obtain a ceramic green sheet and also relates to a method for producing a ceramic green sheet including these steps.

[0019] It is preferable that the method for producing the ceramic green sheet further includes a step of peeling the process release paper for the ceramic green sheet from the ceramic green sheet.

[0020] The present invention also relates to a ceramic green sheet obtained by the production method.

[0021] When the process release paper for the ceramic green sheet is peeled from the ceramic green sheet, it is preferable that the arithmetic mean roughness Ra of the peeled surface of the ceramic green sheet is 0.5 μm or more and 0.8 μm or less, and the maximum height Ry is 4 μm or more and 6 μm or less.

[0022] Furthermore, the present invention also relates to a ceramic green sheet in which the arithmetic mean roughness Ra of one surface of the ceramic green sheet is 0.5 μm or more and 0.8 μm or less, and the maximum height Ry is 4 μm or more and 6 μm or less, and the arithmetic mean roughness Ra of the other surface of the ceramic green sheet is 0.4 μm or more and 1.0 μm or less, and the maximum height Ry is 3 μm or more and 8 μm or less. [Effects of the Invention]

[0023] The process release paper for ceramic green sheets of the present invention can be provided with good breathability and high smoothness. Therefore, the process release paper for ceramic green sheets of the present invention can be suitably used in the manufacture of ceramic green sheets.

[0024] Furthermore, the method for manufacturing ceramic green sheets of the present invention uses process release paper for ceramic green sheets that has good breathability, eliminating the need for long drying times and enabling simplification of manufacturing equipment and reduction of manufacturing time. In addition, the method for manufacturing ceramic green sheets of the present invention allows the use of process release paper for ceramic green sheets that has high smoothness, making it possible to provide ceramic green sheets with high smoothness.

[0025] Furthermore, the ceramic green sheet obtained by the manufacturing method of the present invention can have high smoothness. In addition, the unevenness of the peeled surface of the ceramic green sheet is suppressed and the surface condition is improved, resulting in improved processability and increased design flexibility. Moreover, by bringing the arithmetic mean roughness (Ra) and maximum height (Ry) of one side and the other side of the ceramic green sheet closer together, the surface structure of the ceramic green sheet approaches front-to-back symmetry. This improves the design flexibility of subsequent sheet processing processes, such as the printing and lamination processes. [Brief explanation of the drawing]

[0026] [Figure 1] A schematic cross-sectional view showing one embodiment of the process release paper for ceramic green sheets of the present invention. [Figure 2] A schematic cross-sectional view showing another embodiment of the process release paper for ceramic green sheets of the present invention. [Figure 3] A diagram showing the schematic configuration of a manufacturing apparatus used in one embodiment of the method for manufacturing ceramic green sheets of the present invention. [Figure 4] A diagram showing a schematic configuration of a manufacturing apparatus used in another embodiment of the method for manufacturing ceramic green sheets of the present invention. [Figure 5] Photographs showing the peeled surfaces of the ceramic green sheets from Examples 3 and 4. [Figure 6] A photograph showing the peeled surface of the ceramic green sheet of Comparative Example 3. [Modes for carrying out the invention]

[0027] The present invention mainly relates to a process release paper for ceramic green sheets comprising a paper layer and a release layer, wherein the release layer (1) Calcium carbonate and clay minerals, (2) Silicone compounds, and (3) Binder resin It is characterized by including.

[0028] The present invention will be described below.

[0029] [Process release paper for ceramic green sheets] Paper used in the manufacturing process of various products is called "process paper." Therefore, the "process release paper for ceramic green sheets" of the present invention refers to release paper used in the manufacturing process of ceramic green sheets.

[0030] (paper layer) The process release paper for ceramic green sheets of the present invention has at least one paper layer. The process release paper for ceramic green sheets of the present invention may have multiple paper layers, but it is preferable to have only one paper layer. The paper layer can constitute the base material of the process release paper for ceramic green sheets of the present invention.

[0031] The paper layer typically contains cellulose fibers. Examples of cellulose fibers include wood pulp such as bleached softwood kraft pulp (NBKP), bleached hardwood kraft pulp (LBKP), bleached softwood sulfite pulp (NBSP), and thermomechanical pulp (TMP); other non-wood pulp such as hemp, bamboo, straw, kenaf, mitsumata, kozo, and cotton; modified pulp such as cationized pulp and mercerized pulp; and cellulose fibers or regenerated cellulose fibers derived from rayon, etc. One of these can be used alone or in combination of two or more.

[0032] The paper layer may contain components other than cellulose fibers. Examples of other components include synthetic fibers made of resins such as polyethylene, polypropylene, and polyethylene terephthalate; paper strength enhancers or fixatives such as starch, polyacrylamide, polyamine polyamide, and epichlorohydrin; sizing agents, fillers, filtration yield improvers, water-resistant agents, fixatives, defoamers, slime control agents, etc., and one of these can be used alone or in combination of two or more.

[0033] The method of manufacturing the paper layer (papermaking) is not particularly limited, and it can be manufactured using known papermaking machines such as wire screen machines and cylinder screen machines, and by known manufacturing (papermaking) methods. Size pressing may be performed using paper strength enhancers such as polyacrylamide. When size pressing is performed, a layer may be formed by the size pressing, but this layer does not fall under the category of the release layer described later, and constitutes part of the paper layer. On the other hand, when size pressing is not performed, the paper layer can be a single layer.

[0034] The basis weight of the paper layer is not particularly limited, but the basis weight (measurement method: JIS P 8124

[2011] ) is 40 g / m². 2 ~240g / m 2 Preferably, 50 g / m 2 ~120g / m 2 More preferably, 70 / m 2 ~90g / m 2This is even more preferable. Furthermore, the paper thickness of the paper layer is not particularly limited, but a paper thickness (measurement method: JIS P 8118

[2014] ) of 50 μm to 300 μm is preferred, 60 μm to 150 μm is more preferred, and 85 μm to 115 μm is even more preferred.

[0035] Because the process release paper for ceramic green sheets of the present invention is paper-based, it has higher breathability compared to resin films. Therefore, the drying process in the manufacturing of ceramic green sheets can be carried out in a relatively short time.

[0036] The paper layer preferably has an air permeability of 20 seconds or less, more preferably 15 seconds or less, and even more preferably 10 seconds or less, in accordance with JIS P8117. For measurement, it is preferable to pre-treat the sample at 23°C and 50% relative humidity for 4 hours or more, in accordance with JIS-P8111 (1998).

[0037] The paper layer preferably has a smoothness of 20 seconds or more, more preferably 25 seconds or more, and even more preferably 30 seconds or more, in accordance with JIS P8119. For measurement, it is preferable to pre-treat the sample at 23°C and 50% relative humidity for 4 hours or more, in accordance with JIS-P8111 (1998).

[0038] (Exfoliation layer) The process release paper for ceramic green sheets of the present invention has at least one release layer. The process release paper for ceramic green sheets of the present invention may have one or more release layers. If there is one release layer, it is preferable that the release layer is located on one surface of the paper layer. If there are multiple release layers, it is preferable that the release layers are located on both surfaces of the paper layer. The release layer can come into contact with the ceramic green sheet.

[0039] The release layer of the process release paper for ceramic green sheets of the present invention is (1) Calcium carbonate and clay minerals, (2) Silicone compounds, and (3) Binder resin This includes the above components (1) to (3).

[0040] (1) Calcium carbonate and clay minerals The release layer of the process release paper for ceramic green sheets of the present invention contains at least one type of calcium carbonate and at least one type of clay mineral. It may also contain two or more types selected from calcium carbonate and clay minerals.

[0041] The calcium carbonate is not particularly limited, and any calcium carbonate such as heavy calcium carbonate or light calcium carbonate can be used, but light calcium carbonate is preferred, and columnar or needle-shaped light calcium carbonate is particularly preferred. The particle size of the calcium carbonate is preferably 0.5 to 2.0 μm. As commercially available calcium carbonate, for example, Tamapearl TP-121-7C, Tamapearl TP-121MS, Tamapearl TP-221GS, Tamapearl TP123, and Tamapearl TP-123CS manufactured by Okutama Kogyo Co., Ltd. can be used.

[0042] The amount of calcium carbonate contained in the release layer is preferably 1% to 80% by mass of the release layer, more preferably 10% to 60% by mass, and even more preferably 20% to 40% by mass.

[0043] The clay minerals used are not particularly limited; kaolin, smectite, sericite, zeolite, or any combination thereof can be used.

[0044] Kaolin is preferred as the clay mineral. Various types of kaolin are available, including natural (hydrated) kaolin, calcined kaolin, and delaminated kaolin. Calcined kaolin is produced by calcining natural kaolin; for example, natural kaolin (hydrated aluminum silicate) is heated at a high temperature in a calcination furnace to remove the crystal water, resulting in anhydrous aluminum silicate. Delaminated kaolin is produced by applying mechanical force to natural kaolin to exfoliate and pulverize it, and it has a flat, plate-like shape.

[0045] Examples of natural kaolin include Kaogloss, Kaobright, and Kaofine from Shiraishi Calcium Co., Ltd., and RC-1 from Takehara Chemical Industry Co., Ltd.

[0046] Examples of calcined kaolin include Kaocal manufactured by Shiraishi Calcium Co., Ltd., and Satinton manufactured by BASF.

[0047] Examples of delaminated kaolin include Astraplate from Imerys Minerals Japan Co., Ltd., Kaowhite S, Kaowhite, Kaowhite C from Shiraishi Calcium Co., Ltd., Polyplate P, Polyplate P01, HYDRAPLATE LV, Polyplate HMT from Huber, Nu Clay from BASF, and Kaolax HS from Shiraishi Calcium Co., Ltd., and engineered delaminated kaolin such as Astraplus, Contour 1500, Contour 2070, Contour Extreme, Capim DG, Capim NP, and Capim CC from Imerys Minerals Japan Co., Ltd.

[0048] In the present invention, the mixing ratio (mass ratio) of calcium carbonate and clay minerals is not particularly limited. For example, it can be 90:10 to 10:90, 80:20 to 20:80, or 70:30 to 30:70. However, it is preferable that the amount of clay minerals is greater than the amount of calcium carbonate. For example, the mixing ratio (mass ratio) of calcium carbonate and clay minerals can be 10:90 to 49:51, or 20:80 to 45:55.

[0049] The amount of clay minerals contained in the exfoliation layer is preferably 0.1% to 80% by mass of the exfoliation layer, more preferably 15% to 65% by mass, and even more preferably 30% to 50% by mass.

[0050] (2) Silicone compounds The release layer of the process release paper for ceramic green sheets of the present invention contains at least one silicone compound. It may also contain two or more silicone compounds.

[0051] The silicone compound contained in the release layer contributes to the release properties of the ceramic green sheet from the process release paper for ceramic green sheets according to the present invention. Furthermore, the use of the silicone compound provides thermal stability, insulation, and other properties.

[0052] As the silicone compound, silicone compounds included in known mold release agents can be used. In the present invention, the term "silicone compound" refers to polymers collectively called organopolysiloxanes, which have a main chain (silicone skeleton) in which organic groups (e.g., alkyl groups, phenyl groups, etc.) are bonded to siloxane bonds. As the organopolysiloxane, polydimethylsiloxane (PDMS) is preferred, and it is preferable that a part of the polydimethylsiloxane has reactive or non-reactive functional groups.

[0053] As the silicone compound contained in the release layer, cured products of curable silicone compounds are preferred in terms of stable release properties and excellent film-forming properties during manufacturing. The curable silicone compound may be either an addition-curable silicone or a condensation-curable silicone. When the curable silicone reacts, it can harden by forming a three-dimensional crosslinked structure. Examples of addition-curable silicones include a combination of polydimethylsiloxane and organohydrogenpolysiloxane, which are linear polymers having siloxane bonds and having vinyl groups at both ends of the main chain. A platinum-based curing catalyst may be used to accelerate curing.

[0054] Specific examples of addition-curing silicones include KS-3703T, KS-847T, KM-3951, X-52-151, X-52-6068, and X-52-6069 (manufactured by Shin-Etsu Chemical Co., Ltd.). Addition-curing silicones are preferably used in a form dissolved or dispersed in an organic solvent.

[0055] The amount of silicone compound contained in the release layer is preferably 0.1 to 55 parts by mass, more preferably 15 to 45 parts by mass, and even more preferably 25 to 35 parts by mass, based on 100 parts by mass of the total amount of calcium carbonate and clay minerals contained in the release layer.

[0056] (3) Binder resin The release layer of the process release paper for ceramic green sheets of the present invention contains at least one binder resin. It may also contain two or more binder resins.

[0057] The aforementioned binder resin is different from a silicone compound. That is, the binder resin is a non-silicone compound.

[0058] The binder resin is not particularly limited, and examples include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, polyamide resins such as nylon, polyurethane resins, acrylic resins, and vinyl resins such as polyvinyl chloride and polyvinylidene chloride. One or more of these can be used. These binder resins can also be used in mixtures.

[0059] Acrylic resin is preferred as the binder resin.

[0060] Acrylic resins can be obtained by the homopolymerization of (meth)acrylic monomers or copolymerization with other monomers.

[0061] When the acrylic resin is a copolymer of (meth)acrylic monomer and another monomer, the other monomer copolymerized with the (meth)acrylic monomer may be any monomer having a carbon-carbon double bond, such as styrene, or it may be a monomer having an ester bond or a urethane bond.

[0062] The copolymer of (meth)acrylic monomer and other monomers may be a random copolymer, a block copolymer, or a graft copolymer.

[0063] The form of the acrylic resin is not particularly limited and may be either dissolved in an organic solvent or dispersed in a solvent such as water. Dispersion in water is preferred in terms of environmental impact and ease of application.

[0064] The (meth)acrylic monomers that can be used in the synthesis of acrylic resins are not particularly limited, but typical (meth)acrylic monomers include, for example, (meth)acrylic acid, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and lauryl (meth)acrylate; (meth)acrylamide; N-substituted acrylamides such as diacetone acrylamide and N-methylolacrylamide; (meth)acrylonitrile; and silicon-containing (meth)acrylic monomers such as γ-methacryloxypropyltrimethoxysilane.

[0065] Commercially available acrylic resins may be used. Examples of commercially available acrylic resins include Alphon (manufactured by Toagosei Chemical Co., Ltd.), Bonlon XPS-001, XPS-002, XPS-004, XHS-20, XHS-21S, and XHS-50 (manufactured by Mitsui Chemicals, Inc.).

[0066] The amount of binder resin contained in the release layer is preferably 0.1 to 30 parts by mass, more preferably 5 to 25 parts by mass, and even more preferably 10 to 20 parts by mass, based on 100 parts by mass of the total amount of calcium carbonate and clay minerals contained in the release layer.

[0067] The release layer of the process release paper for ceramic green sheets of the present invention preferably contains at least one type of starch or modified starch. It may also contain two or more types selected from starch and modified starch.

[0068] The starch is not particularly limited and can include, for example, corn starch, potato starch, tapioca starch, wheat starch, sweet potato starch, rice starch, etc.

[0069] Modified starch is starch that has been altered. Types of alteration include hydrophobization, cationization, phosphate crosslinking, adipic acid crosslinking, dextrinization, maltodextrinization, oxidation, acid denaturation, and other enzymatic denaturation. Furthermore, two or more of these alteration processes can be combined during processing.

[0070] As for the modified starch, hydrophobized starch is preferred, and carboxylic acid esterified starch esterified with a monocarboxylic acid or dicarboxylic acid having a linear, branched, or cyclic alkyl or alkenyl group having 4 to 18 carbon atoms is more preferred.

[0071] As the carboxylic acid esterified starch, octenyl succinate esterified starch is preferred. Octenyl succinate esterified starch can be obtained, for example, by reacting octenyl succinate anhydride with starch in an aqueous system.

[0072] Commercially available modified starch may be used. For example, Ingredion's Film Coat series can be used as a commercially available modified starch.

[0073] The amount of starch and / or modified starch contained in the exfoliation layer is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, based on 100 parts by mass of the total amount of calcium carbonate and clay minerals contained in the exfoliation layer.

[0074] The release layer of the process release paper for ceramic green sheets of the present invention may contain inorganic particles other than calcium carbonate and clay minerals. Examples of inorganic particles include inorganic oxide particles such as silica. It may also contain two or more types of inorganic particles.

[0075] The amount of inorganic particles contained in the exfoliation layer is preferably 1 to 25 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 3 to 15 parts by mass, based on 100 parts by mass of the total amount of calcium carbonate and clay minerals contained in the exfoliation layer.

[0076] The release layer of the process release paper for ceramic green sheets of the present invention may contain various additives in addition to (1) calcium carbonate and clay minerals, (2) silicone compounds, and (3) binder resins. Examples of additives include dispersants, wetting agents, water-retaining agents, defoaming agents, water-resistant agents, fluorescent dyes, coloring dyes, coloring pigments, surfactants, pH adjusters, cationic resins, anionic resins, ultraviolet absorbers, metal salts, and the like.

[0077] The process release paper for ceramic green sheets of the present invention may comprise at least one additional layer in addition to the paper layer and the release layer. For example, a sealing layer may be present between the paper layer and the release layer. The sealing layer is intended to suppress the deterioration of the release layer's performance by preventing the release layer-forming composition from sinking into the paper layer. The sealing layer is not particularly limited as long as it can suppress the sinking of the release layer-forming composition into the paper layer, but it is preferable, for example, to include a pigment and a binder resin. The sealing layer may also contain sizing agents, water-resistant agents, water-repellent agents, dyes, surfactants, etc., as needed.

[0078] However, it is preferable that the process release paper for ceramic green sheets of the present invention consists only of a paper layer and a release layer. In other words, it is preferable that the process release paper for ceramic green sheets of the present invention does not have any additional layers other than the paper layer and the release layer. By not having additional layers, the thickness of the process release paper for ceramic green sheets of the present invention can be suppressed. In particular, the process release paper for ceramic green sheets of the present invention does not have a resin film layer integrated with the paper layer or release layer by bonding or the like. By not having additional layers and resin film layers, it is easier to obtain the desired breathability as a process release paper for ceramic green sheets.

[0079] The method for forming the release layer (and any additional layers if necessary) is not particularly limited, and for example, it can be formed on the paper layer by coating using known coating apparatus and coating systems. The release layer is preferably a coated layer. Examples of coating apparatus include blade coaters, bar coaters, air knife coaters, curtain coaters, spray coaters, roll coaters, reverse roll coaters, size press coaters, gate roll coaters, etc. Examples of coating systems include wet lamination such as aqueous coating using solvents such as water, and solvent-based coating using solvents such as organic solvents. The viscosity, solid content concentration, etc. of the composition for forming the release layer (and any additional layers if necessary), such as the coating liquid, can be appropriately adjusted according to the coating apparatus, coating system, etc. used.

[0080] It is preferable to heat-dry the release layer (and any additional layers if necessary) after coating. Conventional methods such as steam heaters, gas heaters, infrared heaters, electric heaters, hot air heaters, microwaves, and cylinder dryers can be used for heat drying.

[0081] In the process release paper for ceramic green sheets of the present invention, it is preferable that the surface in contact with the ceramic green sheet has high smoothness. Specifically, it is preferable that the surface of the release layer in contact with the ceramic green sheet is highly smooth.

[0082] The arithmetic mean roughness (Ra) of the peeling layer, in accordance with ISO 25178, is preferably 0.8 μm or less, more preferably 0.7 μm or less, and even more preferably 0.5 μm or less. The lower limit of the arithmetic mean roughness (Ra) of the peeling layer is not particularly limited, but can be, for example, 0.1 μm or more.

[0083] The maximum peak height (Rp) of the peeling layer, in accordance with ISO 25178, is preferably 5 μm or less, more preferably 4.5 μm or less, and even more preferably 4 μm or less. The lower limit of the maximum peak height (Rp) of the peeling layer is not particularly limited, but can be, for example, 0.5 μm or more.

[0084] To make the surface of the release layer smoother, it is preferable to form the release layer by cast coating. In cast coating, for example, a release layer-forming composition such as a coating liquid is applied to a paper layer, cast onto a smooth film while still wet, pressed and dried, and then peeled off to form a release layer on the paper layer, thereby producing the process release paper for ceramic green sheets of the present invention. By using a smooth film, the smoothness of the film can be transferred, making the surface of the release layer smooth. The material of the film is not particularly limited, but a thermoplastic resin is preferred, for example, polyethylene terephthalate (PET) can be used.

[0085] Tesa Tape 7475 (manufactured by Tesa Tape Co., Ltd.) is applied to the release layer, a load of 200 kgf / cm is applied at room temperature, and after standing for about 10 minutes, the Tesa Tape 7475 is pulled at an angle of 180 degrees and a peeling speed of 0.3 m / min using a Tensilon universal testing machine (manufactured by A&D Co., Ltd., RTC-1210) to peel it off. The force required to peel it off (N / 25mm), i.e., the peeling strength, is preferably 12 N / 25mm or less, more preferably 10 N / 25mm or less, and even more preferably 8 N / 25mm or less.

[0086] The process release paper for ceramic green sheets of the present invention preferably has an air permeability of 10,000 seconds or less, more preferably 7,500 seconds or less, and even more preferably 5,000 seconds or less, according to the Gurley tester method of JIS P8117. For measurement, it is preferable to pre-treat the sample at 23°C and 50% relative humidity for 4 hours or more, according to JIS-P8111 (1998).

[0087] The process release paper for ceramic green sheets of the present invention preferably has a smoothness of 1000 seconds or more, more preferably 1500 seconds or more, and even more preferably 2000 seconds or more, in accordance with JIS P8155. For measurement, it is preferable to pre-treat the sample at 23°C and 50% relative humidity for 4 hours or more, in accordance with JIS-P8111 (1998).

[0088] The amount of the release layer is 1 m of paper layer. 2 Preferably, 5g or more per unit, more preferably 10g or more, and even more preferably 15g or more. There is no particular upper limit to the amount of the release layer, but the amount per 1m of paper layer 2 Preferably, the amount per serving is 50g or less, more preferably 40g or less, and even more preferably 30g or less.

[0089] (Laminated structure) The process release paper for ceramic green sheets of the present invention is a laminate comprising a paper layer and a release layer.

[0090] Figure 1 is a schematic cross-sectional view showing one embodiment of the process release paper for ceramic green sheets of the present invention. In this embodiment, a release layer 12 is present on one surface of the paper layer 11, which is the base material of the process release paper 1 for ceramic green sheets of the present invention, and there is no layer on the other surface of the paper layer 11 (the lower side in Figure 1), and this other surface is open.

[0091] Figure 2 is a schematic cross-sectional view showing another embodiment of the process release paper for ceramic green sheets of the present invention. In this embodiment, the release layer 22 is present on both sides of the paper layer 21, which is the base material of the process release paper 2 for ceramic green sheets of the present invention.

[0092] In the embodiments shown in Figures 1 and 2, the process release paper for ceramic green sheets of the present invention consists only of a paper layer and a release layer.

[0093] [Method for manufacturing ceramic green sheets] The process release paper for ceramic green sheets of the present invention is used in the manufacture of ceramic green sheets. Another aspect of the present invention is a method for manufacturing ceramic green sheets using the process release paper for ceramic green sheets of the present invention.

[0094] (Manufacturing method) The method for manufacturing the ceramic green sheet of the present invention is as follows: The present invention relates to a process for applying a ceramic green sheet slurry onto a release paper for ceramic green sheets, and The process of drying the slurry to obtain a ceramic green sheet. Includes.

[0095] The method for manufacturing a ceramic green sheet of the present invention may further include a step of peeling off the ceramic green sheet process release paper from the ceramic green sheet.

[0096] The following describes an example of an embodiment of the method for manufacturing the ceramic green sheet of the present invention.

[0097] Figure 3 shows a schematic configuration of a manufacturing apparatus used in one embodiment of the method for manufacturing ceramic green sheets according to the present invention.

[0098] In Figure 3, the green sheet manufacturing apparatus 3 includes a twin roll 31 and a winding roll 32 that support and move the ceramic green sheet process release paper (30 in Figure 3) shown in Figure 1 or Figure 2 while applying tension after unwinding it from an unwinding roll (not shown), a roughly box-shaped liquid reservoir 34 that is placed on the ceramic green sheet process release paper 30 to store slurry 33, a doctor blade (not shown) attached to the right side plate of the liquid reservoir 34, and a drying oven 35.

[0099] A long, narrow opening is provided at the bottom right side of the liquid reservoir 34, allowing the slurry 33 to be continuously applied to the surface of the release layer of the ceramic green sheet release paper 30 located below the liquid reservoir 34. On the other hand, the width of the ceramic green sheet release paper 30 is wider than the opening of the liquid reservoir 34, so that the slurry 33 is not applied to both ends of the ceramic green sheet release paper 30.

[0100] The slurry 33 is typically a mixture and dispersion of ceramic raw material powder, solvent, and binder material. Examples of ceramic raw material powder include metal oxides such as alumina and silica. Examples of solvents include organic solvents such as toluene, ketones, and alcohols. Of these, toluene, methyl ethyl ketone, and ethanol are preferred. Examples of binder material include various resin binders. The resin binder is used to impart a predetermined viscosity to the ceramic slurry for producing ceramic green sheets, thereby facilitating the formation of sheets. Examples of resin binders include butyral-based binders. The slurry is not limited to solvent-based (non-aqueous) types; it may also be aqueous.

[0101] The doctor blade scrapes off excess slurry 33 from the process release paper 30 for the ceramic green sheet while adjusting the thickness of the slurry 33. The slurry 33, whose thickness has been adjusted by the doctor blade, is introduced into the drying oven 35 together with the process release paper 30 for the ceramic green sheet. After the slurry 33 is heated and dried, it becomes a ceramic green sheet 36 and is removed from the drying oven 35.

[0102] Here, as shown in Figure 3, the twin rolls 31 sandwich the ceramic green sheet release paper 30 from above and below, and the winding roll 32 winds up the ceramic green sheet 36 together with the ceramic green sheet after the slurry 33 has been applied and dried. Therefore, the ceramic green sheet release paper 30 is supported by tension and continuously travels between the twin rolls 31 and the winding roll 32, which are spaced apart in the direction of travel (left and right in Figure 1).

[0103] Then, a drying oven 35 is placed directly above the position where the lower surface of the ceramic green sheet process release paper 30 is exposed between the twin rolls 31 and the winding roll 32, and the slurry 33 is heated and dried at this position. As a result, as shown by the arrows in Figure 3, the slurry 33 dries not only from the top surface as the solvent evaporates, but also from the bottom surface in contact with the ceramic green sheet process release paper 30, through which the solvent evaporates. In this way, the slurry 33 is dried from the bottom side as well, which reduces the drying load and shortens the drying time.

[0104] The thickness of the slurry 33 on the process release paper 30 for ceramic green sheets can be, for example, 70 to 800 μm.

[0105] Alternatively, the dried ceramic green sheet 36 may be separated before being wound onto the winding roll 32, and only the process release paper 30 for the ceramic green sheet may be wound and reused.

[0106] Figure 4 shows a schematic configuration of a manufacturing apparatus used in another embodiment of the method for manufacturing ceramic green sheets according to the present invention.

[0107] In Figure 4, components identical to those in the embodiment shown in Figure 3 are denoted by the same reference numerals as in Figure 3, and detailed descriptions are omitted.

[0108] In the manufacturing apparatus 3' shown in Figure 4, a breathable base (roller conveyor) 39 is placed between the twin rolls 31 and the winding roll 32, and the ceramic green sheet process release paper 30 is continuously moved in contact with the roller conveyor 39. The roller conveyor 39 is a device in which a plurality of rotating rollers are fixed in a predetermined frame, spaced apart in the axial direction and parallel to each other, and the conveyed material is placed on top of it and moved.

[0109] In the manufacturing apparatus 3', a drying oven 35 is placed directly above the position where the lower surface of the roller conveyor 39 is exposed, and the slurry 33 is heated and dried at this position. The rotating rolls of the roller conveyor 39 are spaced apart in the axial direction, and this gap allows for ventilation. As a result, as shown by the arrows in Figure 4, the slurry 33 dries not only from the top surface by evaporation of the solvent, but also from the bottom surface in contact with the ceramic green sheet process release paper 30, through the gap between the ceramic green sheet process release paper 30 and the roller conveyor 39. Therefore, similar to the embodiment shown in Figure 3, the slurry 33 is dried from the bottom side as well, reducing the drying load and shortening the drying time.

[0110] In the embodiment shown in Figure 4, the ceramic green sheet process release paper 30 is supported in contact with the roller conveyor 39, so it is not necessary to support it with high tension between the twin rolls 31 and the winding roll 32, as in the embodiment shown in Figure 3. For this reason, for example, when the slurry 33 is applied thickly, it is not necessary to apply high tension to the ceramic green sheet process release paper 30, thus suppressing the tearing of the ceramic green sheet process release paper 30.

[0111] As a breathable base, in addition to the roller conveyor mentioned above, mesh or felt can be used. In the case of felt, it is advisable to support the underside of the felt with a frame or the like to maintain its shape. Alternatively, a floating mechanism may be used, or a conveying device combining these may be used.

[0112] (Ceramic Green Sheet) The present invention also relates to ceramic green sheets obtained by the above manufacturing method.

[0113] A ceramic green sheet is an unfired sheet (i.e., a green sheet) whose main solid component is ceramic.

[0114] Here, "main raw material" (main component) refers to a component that accounts for more than 50% by volume of the solid components. The proportion of the main raw material is preferably between 80% and 99% by volume. Examples of ceramic components that serve as the main raw material include metal oxides such as alumina and silica. Alumina particles are preferred.

[0115] The ceramic green sheet of the present invention can have high smoothness.

[0116] For example, when the process release paper for ceramic green sheets is peeled off from the ceramic green sheet obtained by the above manufacturing method, the arithmetic mean roughness Ra of the peeled surface of the ceramic green sheet can be set to 0.5 μm or more and 0.8 μm or less, and the maximum height Ry can be set to 4 μm or more and 6 μm or less.

[0117] Furthermore, the ceramic green sheet of the present invention makes it possible to approximate the surface state of one surface to that of the other.

[0118] For example, in the ceramic green sheet of the present invention, the arithmetic mean roughness Ra of one surface of the ceramic green sheet can be 0.5 μm or more and 0.8 μm or less, and the maximum height Ry can be 4 μm or more and 6 μm or less, while the arithmetic mean roughness Ra of the other surface of the ceramic green sheet can be 0.4 μm or more and 1.0 μm or less, and the maximum height Ry can be 3 μm or more and 8 μm or less. [Industrial applicability]

[0119] The process release paper for ceramic green sheets of the present invention is suitably usable in the manufacture of ceramic green sheets.

[0120] The ceramic green sheet obtained by the present invention can be used in the manufacture of ceramic substrates used in electronic component packages, wireless communication module substrates, control circuit boards, semiconductor testing equipment, and the like.

[0121] Since the paper layer, which is the base layer of the process release paper for the ceramic green sheet of the present invention, is composed of pulp, which is a carbon-neutral material, it has a small environmental impact and can suppress an increase in the amount of carbon dioxide in the atmosphere even when incinerated. Therefore, the process release paper for the ceramic green sheet of the present invention can address resource problems such as global warming due to an increase in carbon dioxide in the atmosphere and oil depletion.

Example

[0122] Hereinafter, the present invention will be described more specifically using examples and comparative examples, but the scope of the present invention is not limited to the examples.

[0123] 〔Example 1〕 NBKP (beating degree c.s.f. 450 ml) and LBKP (beating degree c.s.f. 450 ml) were mixed as pulp so that the amount of NBKP was 30 parts by mass and the amount of LBKP was 70 parts by mass to prepare a pulp slurry. To the pulp slurry, 0.1 part by mass of a polyamide-epichlorohydrin resin (manufactured by Starlight PMC Co., Ltd., product name "WS4024"), 0.05 part by mass of a polyacrylamide-based resin (manufactured by Starlight PMC Co., Ltd., product name "DA4112"), 0.07 part by mass of a rosin sizing agent (manufactured by Arakawa Chemical Industries, Ltd., product name "Size Pine N-771"), and an appropriate amount of sulfuric acid band were added to prepare a papermaking raw material. Next, when papermaking was performed using a Fourdrinier papermaking machine with the papermaking raw material, coating and drying were performed using a 2% aqueous solution of polyacrylamide (manufactured by Arakawa Chemical Industries, Ltd., product name "Polymer Set 305") using a size press coater, and a paper layer with a basis weight of 80 g / m 2 was obtained.

[0124] A pigment slurry for the release layer was prepared by mixing aragonite columnar calcium carbonate (manufactured by Okutama Kogyo Co., Ltd., product name "Tamapearl TP123-CS") and kaolin (manufactured by Shiraishi Calcium Co., Ltd., product name "Kaogloss") as a clay mineral in a ratio of 40:60. To 100 parts by mass of the solid content of the pigment slurry, 5 parts by mass of specially modified tapioca starch (manufactured by Ingredion Co., Ltd., product name "FILMKOTE370") and 15 parts by mass of acrylic emulsion (manufactured by Mitsui Chemicals, Inc., product name "Bonlon XHS-50") as binders, and 30 parts by mass of emulsion-added silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KM-3951") as a silicone compound were added, and the slurry was diluted with water to a solid content concentration of 40% by mass.

[0125] Next, this paint is applied to one side of the paper layer using an air knife coater, with a solid content of 20 g / m². 2 The coating is applied in this manner, and while the coating layer is still wet, a mirror finish is achieved using the wet casting method at a speed of 60 m / min and a casting drum temperature of 70°C to create a release layer with a basis weight of 100 g / m². 2 We obtained a process release paper for ceramic green sheets.

[0126] [Example 2] A process release paper for ceramic green sheets was obtained in the same manner as in Example 1, except that the method for forming the release layer was changed to a method in which a polyethylene terephthalate (PET) film was laminated onto the coating layer while the coating layer was still wet, the coating layer was dried to form a film, and then the polyethylene terephthalate (PET) film was peeled off to obtain the release layer.

[0127] [Comparative Example 1] A process release paper for ceramic green sheets was obtained in the same manner as in Example 1, except that the mixing ratio of calcium carbonate and kaolin in the pigment slurry was set to calcium carbonate:kaolin = 100:0.

[0128] [Comparative Example 2] A process release paper for ceramic green sheets was obtained in the same manner as in Example 1, except that the mixing ratio of calcium carbonate and kaolin in the pigment slurry was set to calcium carbonate:kaolin = 0:100.

[0129] For each of the ceramic green sheet process release papers in Examples 1 and 2, and Comparative Examples 1 and 2, the Gurley air permeability was measured. Furthermore, the Wang-Gan smoothness, peel strength, arithmetic mean roughness, and maximum peak height of the surface of the release layer of the process release paper were measured. The measurement methods for each characteristic are as follows.

[0130] Air permeability: Measured in accordance with the Gurley testing method of JIS P8117. Smoothness: Measured in accordance with JIS P8155. Peel strength: Tesa Tape 7475 (manufactured by Tesa Tape Co., Ltd.) was applied, a load of 200 kgf / cm was applied at room temperature, and after standing for about 10 minutes, the Tesa Tape 7475 was pulled at a 180-degree angle and peeling speed of 0.3 m / min using a Tensilon universal testing machine (manufactured by A&D Company, Limited, RTC-1210), and the force required to peel it off (N / 25 mm) was measured. Arithmetic mean roughness (Ra): Measured in accordance with ISO 25178. Maximum peak height (Rp): Measured in accordance with ISO 25178.

[0131] The results are shown in Table 1 below. [Table 1]

[0132] The process release papers of Examples 1 and 2, which correspond to the ceramic green sheet process release papers of the present invention, can combine good breathability and high smoothness. They can also have appropriate peel strength. On the other hand, the process release paper of Comparative Example 1 has high breathability but poor surface smoothness, and the process release paper of Comparative Example 2 has high smoothness but poor breathability.

[0133] [Example 3] A slurry prepared by mixing alumina powder, a sintering aid, a dispersant, a plasticizer, a butyral resin binder, and an organic solvent such as toluene was formed into a sheet on the ceramic green sheet process release paper of Example 1 using a stainless steel shim with a diameter of 50 mm and a thickness of 1 mm. The formed slurry sheet was placed on a wire mesh 20 mm above the heating surface of a hot plate while still loaded onto the ceramic green sheet process release paper of Example 1, and dried for 10 minutes until the measured temperature of the slurry reached approximately 40°C. After that, the dried sheet slurry was removed from the hot plate and air-dried for 48 hours or more to obtain a ceramic green sheet.

[0134] [Example 4] A ceramic green sheet was obtained in the same manner as in Example 3, except that the process release paper for ceramic green sheets from Example 2 was used.

[0135] [Comparative Example 3] A ceramic green sheet was obtained in the same manner as in Example 3, except that the process release paper for ceramic green sheets of Comparative Example 1 was used.

[0136] As shown in Figure 3, the ceramic green sheet 36 was divided into two parts: the part in contact with the ceramic green sheet release paper 30 was designated as the release surface 37, and the other part not in contact with the ceramic green sheet release paper 30 was designated as the non-release surface 38. The arithmetic mean roughness (Ra) and maximum height (Ry) of the release surface 37 and the non-release surface 38 of the ceramic green sheet after separation from the ceramic green sheet release paper 30 were measured. Arithmetic mean roughness (Ra): Measured in accordance with ISO 25178. Maximum height (Ry): Measured in accordance with ISO 25178.

[0137] The results are shown in Table 2. [Table 2]

[0138] Figure 5 shows the peeled surfaces of the ceramic green sheets of Examples 3 and 4, and Figure 6 shows the peeled surface of the ceramic green sheet of Comparative Example 3. As shown in Figure 6, irregularities can be seen on the peeled surface of the ceramic green sheet of Comparative Example 3, but as shown in Figure 5, the irregularities on the peeled surfaces of the ceramic green sheets of Examples 3 and 4 are suppressed compared to Figure 6.

[0139] Furthermore, the arithmetic mean roughness (Ra) and maximum height (Ry) of the peeled surface of the ceramic green sheets in Examples 3 and 4 are approximately equal to the arithmetic mean roughness (Ra) and maximum height (Ry) of the non-peeled surface of the ceramic green sheet, thus the surface structure of the ceramic green sheet approaches front-to-back symmetry. This eliminates constraints arising from the combination of printable and laminateable sheet surfaces in subsequent sheet processing processes such as printing and lamination, thereby improving the freedom of process design. [Explanation of symbols]

[0140] 1.2 Process release paper for ceramic green sheets 11·21 Paper layer 12.22 Exfoliation layer 3·3' manufacturing equipment 30 Process release paper for ceramic green sheets 31 Double Roll 32 reel rolls 33 Slurry 34 Liquid reservoir 35 Drying oven 36 Ceramic Green Sheet 37 Peeling surface 38 Non-peelable surface 39 Roller conveyor

Claims

1. Paper layer, and, Exfoliation layer Process release paper for ceramic green sheets, comprising: The aforementioned peeling layer (1) Calcium carbonate and clay minerals, (2) Silicone compounds, and (3) Binder resin Process release paper for ceramic green sheets, including...

2. The process release paper for ceramic green sheets according to claim 1, wherein the calcium carbonate is light calcium carbonate.

3. The process release paper for ceramic green sheets according to claim 1, wherein the clay mineral is kaolin.

4. The process release paper for ceramic green sheets according to claim 1, wherein the silicone compound is an addition-curing type silicone.

5. The process release paper for ceramic green sheets according to claim 1, wherein the binder resin is an acrylic resin.

6. The process release paper for ceramic green sheets according to claim 1, wherein the release layer further comprises starch and / or modified starch.

7. The process release paper for ceramic green sheets according to claim 1, wherein the release layer is a coating layer.

8. The process release paper for ceramic green sheets according to claim 1, comprising only the paper layer and the release layer.

9. A step of applying a ceramic green sheet slurry onto a release paper for ceramic green sheets according to any one of claims 1 to 8, and The process of drying the slurry to obtain a ceramic green sheet. A method for manufacturing a ceramic green sheet containing [the specified material].

10. A method for manufacturing a ceramic green sheet according to claim 9, further comprising the step of peeling off the ceramic green sheet process release paper from the ceramic green sheet.

11. A ceramic green sheet obtained by the manufacturing method described in claim 10.

12. The ceramic green sheet according to claim 11, wherein the arithmetic mean roughness Ra of the peeled surface of the ceramic green sheet exposed when the process release paper for the ceramic green sheet is peeled off from the ceramic green sheet is 0.5 μm or more and 0.8 μm or less, and the maximum height Ry is 4 μm or more and 6 μm or less.

13. The arithmetic mean roughness Ra of one side of the ceramic green sheet is 0.5 μm or more and 0.8 μm or less, and the maximum height Ry is 4 μm or more and 6 μm or less. A ceramic green sheet having an arithmetic mean roughness Ra of the other surface of the ceramic green sheet of 0.4 μm or more and 1.0 μm or less, and a maximum height Ry of 3 μm or more and 8 μm or less.

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