JPH02310B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved method for manufacturing ceramic molded bodies, and more particularly to a method for easily manufacturing ceramic molded bodies ranging from very thin to extremely thick. Ceramic molded bodies are used as insulating materials for multilayer wiring boards for electronic circuits, dielectric materials for multilayer capacitors, and piezoelectric materials for piezoelectric buzzers. An example of an application that has recently attracted particular attention is multilayer wiring boards made of alumina ceramics, which are used to miniaturize electronic components or circuits. Ceramic molded bodies applied in these fields are obtained by molding ceramic raw materials into rods, tapes, or thin sheets, and typical molding methods include extrusion molding and doctor blade casting. . The former extrusion molding method involves mixing ceramic raw material powder with a water-soluble polymer as a binder and water as a medium, and molding this using a high-pressure or vacuum extruder. Since it is possible to mold the ceramic raw material using the minimum amount of water necessary, it is possible to obtain a molded product that is dense and has good dimensional stability. Therefore, it is especially used in dielectric materials such as capacitors. However, in the case of ceramic tape for multilayer wiring boards used in computers, extremely thin tape of about 0.1 to 0.3 mm is required, so when using the extrusion molding method, the parts that come into contact with both ends of the mold inevitably become distorted, resulting in a uniform It is difficult to form a tape with a certain thickness. On the other hand, a method that is more widely adopted than the extrusion method is the doctor blade casting method.
In this method, polyvinyl butyral, which has a high film strength, is used as the binder, and it is necessary to use butyl alcohol or chlorethylene-based solvents as the medium, which inevitably causes problems in terms of fire safety and environmental hygiene. . In this method, a slurry obtained by mixing ceramic raw material powder, a binder, and a solvent is poured onto a carrier sheet, stretched to a certain thickness with a doctor blade, and after drying, the tape is peeled off from the carrier sheet. This is the way to get it. Therefore, a tape with a wide width can be easily obtained, but due to the limited viscosity of the slurry, particle sedimentation is inevitably observed after casting.
It cannot be formed into a thick, uniform tape, and it is generally said that the maximum thickness is 1.2 mm. For this reason, there has been a strong desire in the industry to establish a method for producing any desired ceramic molded body, which is water-based and has high dimensional accuracy without causing any problems in terms of fire safety or environmental hygiene. The present invention was arrived at as a result of extensive research from this point of view, and consists of 100 parts by weight of ceramic raw powder, 1 to 10 parts by weight of a water-soluble binder, and polyoxyalkylene fatty acid ester or polyoxyalkylene styrene as a plasticizer. Phenyl ether 0.5~
This is a method for producing a ceramic molded article, which comprises mixing a composition consisting of 10 parts by weight and 5 to 30 parts by weight of water, and extrusion molding and/or roll molding. Ceramic raw material powders used in the method of the present invention include alumina, barium titanate, lead zirconate titanate, zirconia, titanium oxide, silicon nitride, silicon carbide, boron nitride, and the like. Although commonly used water-soluble resins can be used as the water-soluble binder, it is particularly preferable to use water-soluble polyvinyl alcohol and water-soluble cellulose ether. Among water-soluble polyvinyl alcohols, those with a degree of saponification of polyvinyl acetate of 70 mol% or more and a degree of polymerization of 500 or less are preferable, and among water-soluble cellulose, those with a degree of methoxy group substitution of 1.3 are preferable.
~2.2 methylcellulose is preferred. Polyoxyalkylene fatty acid esters used as plasticizers are obtained by addition polymerizing alkylene oxides such as ethylene oxide (EO), propylene oxide (PO), butylene oxide (BO) to fatty acids having 8 to 24 carbon atoms, or by polymerizing fatty acids and polyoxyalkylene oxides. It is obtained by an esterification reaction with glycol, and monofatty acid esters, difatty acid esters, or mixtures thereof can be used. Further, polyoxyalkylene styrenated phenyl ether can be obtained by addition polymerizing EO, PO or BO to styrenated phenol. Both of these plasticizers show good performance, especially those with HLB values of 9 to 15. The fatty acids having 8 to 24 carbon atoms constituting the polyoxyalkylene fatty acid ester include caprylic acid,
Capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, oleic acid, linoleic acid,
These include linolenic acid and ricinoleic acid. Further, as the styrenated phenol constituting the polyoxyalkylene styrenated phenyl ether, mono-, di- or tristyrenated phenols or mixtures thereof can be used. Polyoxyalkylene fatty acid ester and polyoxyalkylene styrenated phenyl ether are nonionic surfactants, and adding them lowers the viscosity during mixing, making it easier to mix ceramic raw material powder and water-soluble binder. Mixing becomes easier and a uniform dispersion is obtained. In addition, when extrusion molding is performed, thixotropy is imparted, so that it flows out easily from the mold, and distortion of the ceramic molded body at the portions that come into contact with both ends of the mold is less likely to occur. Furthermore, the mold releasability is good, and the kneaded material does not adhere to the rolling roll during tape molding, and the physical properties of the molded ceramic sheet are excellent, resulting in a sheet with good strength and flexibility. The blending ratio of polyoxyalkylene fatty acid ester or polyoxyalkylene styrenated phenyl ether as a water-soluble binder and plasticizer to the ceramic raw material powder is 1 to 10 parts by weight of the water-soluble binder to 100 parts by weight of the ceramic raw material powder. ,
Preferably 3 to 8 parts by weight, polyoxyalkylene fatty acid ester or polyoxyalkylene styrenated phenyl ether 0.5 to 10 parts by weight,
Preferably it is 3 to 6 parts by weight. Further, the amount of water added is 5 to 30 parts by weight. The optimum amount to be added varies within the above range depending on the particle size and shape of the ceramic raw material powder and the type of water-soluble binder, but if the apparent density of the ceramic raw material powder is high and the viscosity of the water-soluble binder is low, On the other hand, if the apparent density of the ceramic raw material powder is low or the viscosity of the water-soluble binder is high, it is necessary to add a relatively large amount of water. In the production method of the present invention, it is necessary to thoroughly mix, knead, and ripen the raw material mixture. The water-soluble binder, polyoxyalkylene fatty acid ester or polyoxyalkylene styrenated phenyl ether, and water may be added to the ceramic raw material powder at the same time, but the water-soluble binder must be dissolved in water beforehand. A method in which polyoxyalkylene fatty acid ester or polyoxyalkylene styrenated phenyl ether is added to the powder, or a water-soluble binder and polyoxyalkylene fatty acid ester or polyoxyalkylene styrenated phenyl ether are dissolved or dispersed in water. The method of adding the powder to the ceramic raw material powder makes it easy to mix and knead the ceramic raw material powder, and a uniform dispersion can be obtained. Since the method of the invention produces ceramic molded bodies in an aqueous system using water-soluble binders, the fire safety and environmental health problems associated with the use of organic solvents are completely avoided. When the composition of the present invention is molded by extrusion molding, the parts that come into contact with the mold are less affected by distortion and a uniform ceramic molded product can be obtained, and when tape molding is performed using rolling rolls, the clearance between the rolls can be adjusted. Since it can be formed into a tape of any thickness with just a single step, tapes with a thickness of 0.3 mm or less, which could only be obtained by casting, can be easily formed. Moreover, due to the problem of sedimentation of ceramic raw powder particles in the casting method, the diameter is approximately 1.2 mm.
It is possible to form such thick tapes, whereas it is not possible to obtain tapes with thicknesses greater than . Furthermore, in casting, a porous tape is inevitably obtained due to the evaporation of the solvent, but in the method of the present invention, when roll forming is performed after a pre-kneading process such as extrusion molding, the tape is dense, strong, and dimensionally stable. A tape with good quality can be obtained. Ceramic tapes are sometimes printed with patterns before sintering, and in this case, the permeability of the printing ink becomes a problem, but since the present invention uses a water-soluble polymer as a binder, there is no possibility of bleeding or dripping of the printing ink. There is no problem, and fine printing can be easily performed. Next, examples of the present invention will be given. Example 1 Alumina powder (average particle size 4μ) 100 parts by weight Talc powder 6 parts by weight Clay powder 2 parts by weight Poval UMR-10H (product of Unitika Kasei Co., Ltd., degree of saponification of polyvinyl acetate 70-95 mol%, polymerization Every time
100% polyvinyl alcohol) 6 parts by weight Plasticizer 4 parts by weight Water 20 parts by weight In the above composition, the nonionic surfactant polyoxyalkylene fatty acid ester or polyoxyalkylene styrenated phenyl ether used in the present invention as a plasticizer. In addition, other polyoxyethylene-based nonionic surfactants were used for comparison purposes. First, an aqueous solution of poval and a plasticizer dissolved in water is added to the specified amounts of alumina powder, talc powder, and clay powder, thoroughly kneaded, and put into a vacuum extrusion molding machine to form a product with a thickness of 10 mm and a width of 500 mm.
It was extruded into a sheet. Table 1 shows the situation and the condition of the sheet. From Table 1, the products using polyoxyalkylene fatty acid ester or polyoxyalkylene styrenated phenyl ether as a plasticizer have excellent extrusion conditions and sheet conditions.
It is clear that those using polyoxyalkylene fatty acid esters or polyoxyalkylene styrenated phenyl ethers exceeding HLB9 are particularly excellent. After thoroughly kneading the compositions No. 1 and No. 2 in Table 1, they were put into a vacuum extrusion molding machine to a thickness of 10 mm.
The alumina tape was extruded into a sheet with a width of 500 mm, and then passed through rolls with clearances of 5 mm, 2 mm, and 1 mm in order to obtain an alumina tape with a thickness of 0.2 mm. The surface condition of each tape was uniform and glossy. The ceramics of these tapes were fired in a reducing flame at about 1450°C and were in good condition.

[Table] Example 2 Lead zirconate titanate powder 100 parts by weight Metrose SM-4000 (Shin-Etsu Chemical Co., Ltd. product,
Methyl cellulose) 3 parts by weight Plasticizer 2 parts by weight Water 10 parts by weight In the above composition, the same nonionic surfactant as in Example 1 was used as the plasticizer. An aqueous solution of methyl cellulose and a plasticizer was added to a specified amount of lead zirconate titanate powder, thoroughly kneaded, and then extruded into a rod shape using a flow tester. Table 2 shows the extrusion conditions and rod conditions. According to Table 2, those using polyoxyalkylene fatty acid ester or polyoxyalkylene styrenated phenyl ether as a plasticizer have excellent extrusion conditions and rod conditions, and HLB9
It is clear that the results are particularly good when using materials exceeding . After thoroughly kneading the compositions No. 13 and No. 15 in Table 2, they were put into a vacuum extrusion molding machine to a thickness of 10 mm.
The tape was extruded into a sheet with a width of 500 mm and then passed between rolls with clearances of 5 mm, 2 mm, and 1 mm to obtain a lead zirconate titanate ceramic tape with a final thickness of 0.3 mm. The surface condition of each tape was uniform and glossy. The ceramics obtained by firing these tapes in a reducing flame at about 1450°C were also in good condition.

【table】

Claims (1)

[Claims] 1. 100 parts by weight of ceramic raw powder, 1 to 10 parts by weight of a water-soluble binder, 0.5 to 10 parts by weight of polyoxyalkylene fatty acid ester or polyoxyalkylene styrenated phenyl ether as a plasticizer, and 5 to 10 parts by weight of water. 1. A method for producing a ceramic molded article, which comprises mixing a composition comprising 30 parts by weight and extrusion molding and/or rolling roll molding. 2. The method for producing a ceramic molded article according to claim 1, wherein the water-soluble binder is water-soluble polyvinyl alcohol or water-soluble cellulose ether. 3. The method for producing a ceramic molded article according to claim 2, wherein the water-soluble polyvinyl alcohol has a degree of saponification of polyvinyl acetate of 70 mol% or more and a degree of polymerization of 500 or less. 4. The method for producing a ceramic molded article according to claim 2, wherein the water-soluble cellulose ether is methyl cellulose with a degree of methoxy group substitution of 1.3 to 2.2. 5. The method for producing a ceramic molded article according to claim 1, wherein the polyoxyalkylene fatty acid ester is an ester of polyoxyalkylene glycol and a fatty acid having 8 to 24 carbon atoms. 6. The method for producing a ceramic molded article according to claim 1 or 5, wherein the polyoxyalkylene fatty acid ester or polyoxyalkylene styrenated phenyl ether has an HLB value of 9 to 15.