JPH0479984B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a ceramic sheet that is less warped or deformed, has a smooth surface, and is dense. More specifically, ceramic sheets used in consumer or industrial electronic equipment or electric equipment, ceramic sheets used in tools, machines, parts, etc., ceramic sheets used in tone plates,
The present invention relates to a method for manufacturing ceramic sheets used as building materials such as heat insulating boards, or ceramic sheets used as far-infrared emitters or ultraviolet reflectors. [Prior art] JP-A-58-190867, JP-A-59-169970, and JP-A-Sho are methods for manufacturing dense ceramic sheets with less warping, cracking, and deformation and smooth surfaces.
60-42268, Japanese Patent Application Laid-open No. 60-239353, etc., disclose methods of manufacturing using specific organic binders. Also, JP-A-59-156960~2, JP-A-Sho
A method using a specific ceramic raw material powder is disclosed in Japanese Patent No. 60-54964 and the like. Furthermore, there are methods in which porcelain plates, frames, supports, etc. are stacked or placed on or around ceramic green sheets and then fired.
69276-7, JP-A-59-50079, JP-A-60-
It is disclosed in Publication No. 73291, etc. Furthermore, JP-A-58-99163, JP-A-61-
Publication No. 113220 and the like disclose a method of laminating or alternately stacking a release powder-containing film, metal oxide-containing paper, etc. on a green sheet and firing the green sheet. However, as a result of studies conducted by the present inventors, a green sheet with a smooth surface can be obtained by selecting an organic binder and ceramic raw material powder, but when this sheet is fired using a normal method, It was found that it did not have sufficient smoothness due to the effects of warping and cracking, and the unevenness of the surface of the floorboard and flooring powder. In addition, as mentioned above, various firing methods have been studied, and although it has a certain degree of smoothness, it does not meet the JIS standard.
Centerline average roughness Ra defined in B0601 is usually 0.2
~0.3μm or more, and since the green sheet is fired and sintered while applying weight, etc.
It was found that the quality was inferior due to problems of warping and cracking. [Problems to be Solved by the Invention] Therefore, the object of the present invention is to provide a surface that has excellent surface smoothness, specifically has Ra of 0.1 μm or less, is dense and has sufficient strength, and has a thickness of preferably 500 μm or less. teeth
The present invention provides a method for manufacturing a ceramic sheet having a thickness of 10 to 150 μm and also having translucency. [Means for Solving the Problems] The present invention involves adding an organic binder, a solvent, and, if necessary, a dispersant, a plasticizer, an antifoaming agent, etc. to ceramic powder, and kneading the resulting ceramic slurry for a required period of time. In this method, a green sheet is sandwiched between a plurality of fire-resistant plates with smooth surfaces and pre-fired at a temperature in the range of 400 to 1000°C,
The present invention provides a method for producing a ceramic sheet, characterized in that the pre-fired sheet is then fired at a temperature exceeding 1000°C. In other words, when pre-firing at a temperature in the range of 400 to 1000 degrees Celsius, the green sheet is placed between multiple smooth fire-resistant plates to give it smoothness and prevent warping and cracking. and then sintering causes rapid volumetric shrinkage.
When firing at temperatures exceeding 1000°C, the pre-fired sheet is removed from the gap between multiple refractory plates and fired to impart density and strength to the resulting ceramic sheet. In this case, the green sheet is placed between multiple smooth fireproof plates and heated to 1000℃.
When fired at a temperature exceeding
Distortion, warping, and cracking are more likely to occur. Also,
from room temperature without being placed between multiple plates.
If the sheet is fired by raising the temperature to a temperature exceeding 1000° C., sufficient smoothness will not be obtained and the sheet will warp, especially at the periphery, and sag at the center, which is undesirable. The ceramic powder used in the present invention includes alumina, zirconia, and
Oxides such as titania and their mixtures, or perovskite types such as barium titanate (BaTiO ₃ ), lead zirconate (PbZrO ₃ ), lead zirconate titanate (PZT), and lanthanum-doped lead zirconate titanate (PLZT) Complex oxides, spinel-type complex oxides such as magnesium aluminate, oxides such as mullite, cordierite, zircon, ferrite, silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ),
These include carbides and nitrides such as aluminum nitride (AlN). The shape of these ceramic powders is preferably spherical particles in order to improve the sliding property with the fire-resistant plate during pre-firing, and the alumina spherical fine particles disclosed in Japanese Patent Application No. 1982-42750 and the Japanese Patent Application No. 1983
Zirconia-based spherical fine particles disclosed in Japanese Patent No. 40085 are preferably used. In addition, as organic binders, esters of acrylic acid and methacrylic acid, amide polymers, copolymers, and emulsions, which are commonly used as binders for ceramic molded bodies, are used.Furthermore, cellulose derivatives, polyvinyl alcohol, polyvinyl butyral, water-based urethane resin,
Wax, styrene-maleic acid copolymer, etc. can also be used. However, since the green sheet is placed between two fire-resistant plates and pre-fired, it is preferable to use a material that is thermally decomposable, especially in a nitrogen atmosphere. , a methacrylic binder is preferably used. The smooth fire-resistant plate is best made of the same quality as the ceramic powder used to reduce the difference in coefficient of thermal expansion, but alumina, zirconia, or glass plates are generally used. In particular, in the present invention, the smoothness of the plate used is important, and the surface roughness Ra
The thickness is preferably 0.1 μm or less, particularly 0.01 μm or less, and a glass plate made of quartz is preferably used. As for the shape, a combination of flat plates or a combination of plates having a convex surface and a concave surface may be used. The temperature for pre-firing is preferably in the range of 400 to 1000°C, and does not exceed the temperature at which thermal decomposition of the organic binder is completely completed and volume change or sintering due to crystal transition of the ceramic powder begins.
More preferably, the temperature is in the range of 600 to 900°C. After pre-firing, the sheet is heated to a temperature above 1000℃, preferably
A ceramic sheet is obtained by firing at a temperature exceeding 1200℃. [Example] The present invention will be explained in detail in the following example,
The present invention is not limited to this embodiment. Example 1 100 parts of spherical alumina fine particles with an average particle diameter of 0.7 μm,
20 parts of an acrylic binder consisting of a copolymer of ethyl acrylate, methacrylic acid, etc., and 0.2 parts of Aquaric NL (manufactured by Nippon Shokubai Chemical Industry Co., Ltd.) as a dispersant.
and 70 parts of water into a ball mill.
It was kneaded for 23.5 hours. 0.1 part of Nobuco 8034 (manufactured by San Nobuco Co., Ltd.) as an antifoaming agent was added to the obtained slurry, and the mixture was kneaded in a ball mill for an additional 0.5 hours. After kneading, the slurry was filtered through a degreased 200-mesh stainless wire mesh, aged while stirring at a speed of 40 rpm, and then defoamed with a vacuum pump to adjust the viscosity to 10 poise. This slurry was drawn into a sheet using a doctor blade adjusted to a gap of 0.15 mm, and heated at 30°C.
A green sheet was obtained by drying at an elevated temperature of 80°C. Cut this sheet into a square with sides of 150 mm.
It was placed between two pieces of quartz glass with a side of 160 mm and a thickness of 2 mm of less than Ra 0.01 μm, placed horizontally in an electric furnace, and pre-fired at 800°C. Subsequently, the two quartz glasses were removed and the pre-fired sheet was placed on an alumina plate and fired at 1600°C to obtain an alumina sheet. Example 2 Average particle size containing 3 mol% ittria
100 parts of 0.3 μm spherical zirconia fine particles and an acrylic binder 30 made of a copolymer of butyl acrylate, 2-hydroxyethyl acrylate, etc.
1 part, 0.8 parts of Aquarik NL (manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd.) as a dispersant, and 60 parts of toluene were charged into a ball mill and kneaded for 16 hours. Thereafter, a green sheet was obtained in the same manner as in Example 1. Cut out this sheet into a square with sides of 150 mm.
Installed vertically in an electric furnace in the same manner as in Example 1.
Preliminary firing was performed at 900℃. Next, the two glass plates were removed and the pre-fired zirconia sheet was inserted.
It was placed on a zirconia plate with Ra of 0.1 μm, placed horizontally in an electric furnace, and fired at 1400°C to obtain a zirconia sheet. Example 3 A green sheet was obtained in the same manner as in Example 1 using barium titanate powder having an average particle diameter of 1 μm. This sheet was preliminarily fired at 700°C in the same manner as in Example 1, and then fired at 1050°C to obtain a sheet. Example 4 A green sheet obtained in the same manner as in Example 1 was placed between two semi-cylindrical pieces of quartz glass having convex and concave surfaces, placed horizontally in an electric furnace, and heated at 800°C. Fired. Next, the convex and concave quartz glasses were removed and fired at 1600°C to obtain a semi-cylindrical alumina sheet. Comparative Example 1 A green sheet obtained in the same manner as in Example 1 was placed on an alumina plate, placed horizontally in an electric furnace, and fired at 1600°C to obtain an alumina sheet. Comparative Example 2 A green sheet obtained in the same manner as in Example 2 was placed between two zirconia plates, vertically placed in an electric furnace, and fired at 1400°C to obtain a zirconia sheet. Example 5 The characteristics of the ceramic sheets obtained in Examples 1 to 3 and Comparative Examples 1 to 2 were investigated and summarized in Table 1. Note that the warp of the sheet was calculated by calculating the maximum depth (mm) of the concave curved surface in terms of the size of a 50 x 50 mm square. 【table】

Claims (1)

[Scope of Claims] 1. A ceramic slurry obtained by adding an organic binder, a solvent, and if necessary a dispersant, a plasticizer, an antifoaming agent, etc. to ceramic powder and kneading it for a required period of time is formed into a sheet, which is then dried. In a method of producing ceramic sheets by firing, a green sheet is sandwiched between a plurality of fire-resistant plates with smooth surfaces,
1. A method for producing a ceramic sheet, which comprises pre-firing at a temperature in the range of 400 to 1000°C, and then firing the pre-fired sheet at a temperature exceeding 1000°C. 2. Claim 1, wherein the ceramic powder is spherical alumina fine particles or spherical zirconia fine particles.
Method described. 3. The method according to claim 1, wherein the refractory plate is quartz glass. 4. The method according to claim 1, 2 or 3, characterized in that the green sheet is sandwiched between a plurality of fire-resistant plates having smooth convex and concave surfaces.