JP2502628B2 - Ceramic material for extrusion molding - Google Patents

Description

TECHNICAL FIELD The present invention relates to an extrusion-molding ceramic material, and more particularly, to an extrusion-molding ceramic material which provides a sintered body having no pore defect, which is useful as a ceramic molding for electronic materials. It is about.

(Prior art and its problems) A conventional method for manufacturing a ceramic extruded body is to mix, calcinate, and pulverize a ceramic main material into a non-plastic ceramic powder, and a binder for imparting plasticity to this powder. , Water for dissolving the binder, and if necessary, plasticizer, lubricant, etc., and kneading (mixing while tearing with a roll mill, continuous kneader, etc.) to form a clay, which is extruded After that, it is a method of firing to form an element body, but especially when producing an element body such as a ceramic sheet for electronic materials that requires high quality, enhance the water retention and shape retention of the soil, In order to impart a plasticity suitable for extrusion molding with a small amount, a water-soluble cellulose derivative such as methyl cellulose having a methoxy group is widely used as a binder. However, when an extrusion molding material is prepared using such a cellulose derivative, this aqueous dispersion becomes a hard jelly at a high concentration of 10% or more, so that the cellulose derivative is homogeneous in the ceramic powder. Often, the powder did not disperse and remained in a hydrated or swollen state.

To solve this problem, a method has been adopted in which the cellulose derivative is dissolved in water and then sufficiently kneaded with the ceramic powder. However, the cellulose derivative is an ether- or ester-substituted one in order to make water-insoluble natural cellulose soluble in water, and the substitution reaction is a solid-liquid reaction between a cellulose solid and an etherification or esterifying agent. However, in industrial scale production, the reaction tends to be non-uniform, and it becomes difficult to dissolve in water in the low substitution degree parts. If this is used for extrusion molding of ceramics, empty space of several μm will be present in the molded body after sintering. Pores were formed. These holes are not suitable for preparing an IC substrate in which a circuit is formed by printing an electrokinetic layer and an insulating layer having a thickness of about 10 to 20 μm on a sintered substrate, and a ceramic ceramic for a dielectric such as a capacitor is used. Even in the case of a bonded body, the voids deteriorate the withstand voltage characteristics, and therefore development of such a defect-free substrate has been desired.

(Means for Solving Problems) As a result of extensive studies based on this requirement, the present invention has these problems when the amount of the water-insoluble fibrous substance in the cellulose derivative binder to be added is set to a certain value or less. It was completed by finding that the can be solved.

That is, in the extrusion molding ceramic material according to the present invention, the cellulose dielectric containing the molding binder as the molding binder is 8 μm or more present in 2 cc of the 0.1 wt% aqueous solution.
The gist is that the number of undissolved fibers of 200 μm or less is 1,000 or less.

Hereinafter, to explain the details of the present invention, the cellulose derivative used as a binder for extrusion molding in the present invention, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl ethyl cellulose, hydroxyethyl. Water soluble cellulose dielectrics such as ethyl cellulose, ethyl cellulose, carboxymethyl cellulose and the like can be mentioned.

The present invention, as described above, uses this cellulose dielectric of 0.
8 μm or more and 200 μm existing in 2 cc of 1 wt% aqueous solution
The following amount of undissolved fiber is characterized in that it is kept in the range of 1,000 or less, but in order to achieve this amount range of undissolved fiber, a sufficient amount in the usual method for producing a cellulose derivative is used. This can be achieved by adopting conditions under which uniform and sufficient reaction is performed, such as using a reaction chemical and selecting and using a necessary solvent. In addition, this quantity is 1,000 or more 10,
If it is less than 000, although it has some effect on the reduction of the number of pores in the ceramic sintered body, it is necessary to make the defect rate extremely small in order to provide a ceramic product for electronic materials intended by the present invention. However, the above is not enough, and it is essential to keep this to 1,000 or less. Also, the smaller the amount, the more desirable, but it is extremely difficult and expensive to produce such a binder, so that there is a limit in itself.

On the other hand, when the particle size of the undissolved fiber is less than 8 μm, the diameter of the pores in the ceramic sintered body obtained from this is also less than 8 μm, so the conductive layer and the insulating layer of about 10 to 20 μm are printed on the sintered body. There is no fear of impairing the withstand voltage characteristics of the dielectric ceramic material such as the IC substrate and the capacitor,
On the other hand, those having a particle size of 200 μm or more are not a problem because they are removed by a screen having an opening of about 200 μm used in ordinary ceramic extrusion molding.

In addition, the measurement method of this undissolved fiber is that the electrolyte solution for Coulter counter ISOTON II (manufactured by Nikkaki Co., Ltd., trade name) is first placed in a 20 ° C thermostat so that the water-soluble cellulose derivative has a concentration of 0.1%. Dissolved and present in this solution 8
Using the aperture tube with a diameter of 400 μm, Coulter Coulter TA II
It can be performed by counting with a mold (manufactured by Nikkaki Co., Ltd., trade name) or a Multisizer machine.

The extrusion molding material according to the present invention is used by mixing the cellulose derivative binder with ceramic powder, water, and if necessary, additives such as a plasticizer and a lubrication aid. Alumina, barium titanate, PZT, zirconia, zinc oxide,
In almost all ceramic materials such as silicon nitride and silicon carbide, it can be used as a powder having an arbitrary shape with a particle size of about 0.1 to 20 μm.

Also, as various additives to be added as necessary,
Examples thereof include plasticizers such as polyethylene glycol, glycerin, propylene glycol, ethylene glycol and 1,4-butanediol, and lubricating aids such as wax and wax emulsion.

The components may be mixed by mixing the cellulose derivative binder and the ceramic powder in advance and then adding other components. Alternatively, the cellulose derivative binder may be dissolved in water and a plasticizer in advance and then mixed with the ceramic powder. In any case, the effects of the present invention may not be impaired by kneading so that the binder after mixing is sufficiently evenly dispersed and then extruding.

Hereinafter, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Examples 1 to 5 and Comparative Examples 1 to 2 6 of each cellulose derivative binder having the properties shown in the attached table
Part by weight is mixed with 100 parts by weight of alumina LS-200 (manufactured by Nikkei Kako Co., Ltd.), 4 parts by weight of talc high filler (manufactured by Matsumura Sangyo Co., Ltd.), 8 parts by weight of glycerin, 20-22 parts by weight of water. Then
It was extruded as an alumina ceramic sheet and dried and sintered. The cross section of the obtained molded body is polished and then examined by a microscope.
The number of pores of several μm or more per 1 mm diameter was counted and listed in another table.

From this, it has been found that the present invention can significantly reduce the pores of the ceramic molded body.

EFFECTS OF THE INVENTION According to the present invention, since the extrusion molding material does not contain undissolved fibers having a particle size of 8 μm or more, pores of about several μm are not formed in the sintered body, and the electronic material A ceramic sintered compact suitable for use can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhisa Hayakawa 28-1 Nishi-Fukushima, Chugiki-mura, Nakakubiki-gun, Niigata Prefecture Shin-Etsu Chemical Co., Ltd., Synthetic Technology Research Laboratory (56) , A)

Claims (1)

(57) [Claims] 1. A cellulose derivative contained as a molding binder is present in 2 cc of a 0.1% by weight aqueous solution thereof.
A ceramic material for extrusion molding, characterized in that the number of undissolved fibers having a size of μm to 200 μm is 1,000 or less.