JPS6022667B2 - Molding method for ceramic base material - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for forming ceramic substrates.

Conventional methods for molding ceramic substrates include: ■ Mixing a Z ceramic material such as alumina, cordierite, steatite, etc. with a thermoplastic resin, molding it under heating, and then cooling; ■ Mixing the ceramic material and urethane resin with a solvent. 1. A method of mixing Kibushi clay and water in the presence of a ceramic material and immediately contacting it with water to harden it; A method of performing this during freezing is known. However, in methods ① and ①, it is difficult to process the solvent used and the bran gas when molded products are assembled, and method ③ takes time to dry, so it takes a long time to dry after molding. This has the disadvantage that the molded product is deformed.

Although method (2) can suppress changes in the molded product during drying, it is not fully satisfactory in that it takes a long time to dry. The present inventors have conducted various studies to overcome the drawbacks of these conventional methods, and have found that in the method (2) above, when mountain bark, which has not been used at all in ceramic molding, is mixed with ceramic material and molded, the drying time under freezing is reduced. We found that it can be significantly shortened.

That is, the present invention is characterized in that a ceramic base material is used in which at least 2% in terms of solid content is husk, in a method for molding a ceramic base material in which the ceramic base material is kneaded with water, then frozen and dried. This is a method for molding ceramic substrates. In the present invention, the ceramic base material refers to a raw material that is mixed with water and kneaded with water to form a ceramic molded product.

The solid content of this ceramic base material is usually a mixture of the mountain skin alone or a mixture of the mountain skin, a ceramic material, and/or a substance that can be converted into ceramic by firing, but if necessary, binders, lubricants, mold release agents, etc. may be added as subcomponents. May contain. The mountain leather is a general term for clay minerals having a large number of active hydrogen groups on the surface, and is usually called mountain leather, mountain cork, mountain wood, etc.

These include sepiolite, which is a type of hydrated magnesium silicate, and attapuldiite, which is a type of hydrated magnesium alumina silicate. Meerschaum, which is used in pipes, and magnesium trisilicate, which is used as an antacid, are also types of mountain bark. The mountain bark used in the present invention may be in powder form, or may be in the form of a dispersion or paste dispersed in water or an organic solvent.

The ceramic material itself means a ceramic material, and examples thereof include cordierite,
Examples include steatite, forsterite, zirconia, alumina, barium titanate, ferrites, mullite, spinels, graphite, activated carbon, silicon nitride, and silicon.

In addition, instead of ceramic materials, materials that become ceramic through firing may be used, such as clays such as kaolin, pyrophyllite, bentonite, and kibushi clay, and carbonates such as dolomite, magnesite, and calcium carbonate. Examples include salt, hydroxides such as brucite, and bayerite. These ceramic materials, which become ceramic by firing, can be used alone or in combination of two or more. Subcomponents in the ceramic base material are binders, lubricants, and
The mold release agent used can be used as is.

Examples of binders include carboxymethylcellulose (CMC), methylcellulose, ethylcellulose, latex, polyvinyl alcohol, isobane (a copolymer of isobutylene and maleic anhydride), starch, caseinate, alginate, etc. Natural products can be used as lubricants such as ethylene glycol, polyethylene glycol, glycerin, trimethylolpropylene, polypropylene glycol, etc., and as additives such as vaseline, palmitic acid, oleic acid, stearic acid, etc. The combined solid content of the ceramic base material may be only mountain bark, but it may also be a mixture of mountain bark and ceramic materials and/or materials that become ceramic by firing, and if necessary, subcomponents may be added. May contain.

When using a mixture of mountain bark and ceramic materials and/or materials that become ceramic by firing, and optionally subcomponents, 2% or more of the solid content in the mixture must be mountain bark, but usually Mountain bark is 5-5% by weight
It is preferable that If the amount of ridges in the ceramic base material is less than a predetermined amount, it will take a long time to dry after molding, and the desired effect of the present invention will not be achieved. The ceramic base material used in the present invention may contain subcomponents such as a binder, a lubricant, and a mold release agent, if necessary, but excessive amounts of these subcomponents may have a negative effect on the molded product. The amount of subcomponents such as binders, lubricants, mold release agents, etc. mixed in is preferably at most 35% by weight or less in terms of solid content in the base material.
When molding a ceramic base material, it is preferable to adjust the moisture content in consideration of the physical properties of the base material during molding and the desired physical properties of the molded product after molding. Generally, when trying to increase the porosity in a molded product, it is sufficient to increase the amount of water, but if it is too large, the base material becomes liquid and the viscosity becomes too low, making it impossible to mold.

On the other hand, if the water content is reduced, a product with low porosity and high density can be obtained, but if it is too small, the viscosity becomes high and molding becomes impossible. The water content is usually 1 to 80% by weight, preferably 8% by weight.
It is preferable to set it to 4% by weight. Note that a mixed solvent of water and an organic solvent such as an alcohol or a ketone may be used instead of water. When preparing the ceramic base material, any means for mixing the components may be used; however, since the powder can be present in the form of powder, paste, or dispersion, it is necessary to mix the components in any form. Powder or paste of the ingredients may be added by an appropriate means.

When the resulting composition is in powder form, 40~
Add about 80% water or an organic solvent (for example, alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, amides such as dimethylacetamide and dimethylformamide, and chlorinated solvents such as methylene chloride and trichloride). Since it becomes plastic when kneaded well, it can be molded using any forming method such as casting or extrusion. In addition, an aqueous dispersion of mountain bark is prepared, powders of other ingredients are added thereto and co-dispersed, and a stringable polymer flocculant is added to this to coagulate and precipitate the dispersoids. It is also possible to collect only the raw material and make a mud-like plastic material with a moisture content of 80% or less.

When preparing an aqueous dispersion of mountain bark, generally about 10 to 5 ribs of mountain bark are used, and the concentration of mountain bark is usually 0.00.
1 to 5% by weight, preferably 0.1 to 5% by weight.

This aqueous dispersion can be prepared by placing mountain bark in water and mixing it with Takaazuka using an appropriate means.
When polyhydric alcohols such as glycols, glycerin, and bran are applied to mountain bark, they can easily be dispersed in water. Also, use hot water instead of water, alcohol,
A hydrophilic organic solvent such as ketones may be added.
Any mixing method may be used for dispersion, but for dispersion liquids with a concentration of 1% or less, for example, a high-speed mixer is used, and for high concentrations of 5% or more, a three-roller is used. For medium concentrations of 1 to 5%, a dispersion method such as a papermaking clay dispersion machine that performs mixing and kneading at the same time, a Z or speed line mill that passes between two rotating grindstones, or Agitators can be used. The stringable polymer flocculants include anionic polymers (e.g., sodium polyacrylate, salts of partial hydrolysates such as polyZ acrylamide, salts of maleic acid copolymers), cationic polymers (e.g., Vinyl pyridine hydrochloride, vinyl pyridine copolymer salt, polyacrylamide partial hydrolyzate), nonionic polymer (
For example, diaryldimethylammonium chloride polymer, polyacrylamide, polyvinyl alcohol) or egg white.

Also included are natural stringy polymers commonly referred to as fuchin, such as loaoi and okra fruit mucilage. When these are dissolved in water or an organic solvent to form a liquid, any viscous steel can be used to pull a thread, and its molecular weight is 5000.
Above, preferably 10,000 to 500×1 pi.
Among these, anionic polymers such as acrylic soda, tri-nonionic polymers such as polyethylene oxide, and molasses mallow are particularly preferred. The amount of stringable polymer flocculant added is approximately 0.0001 of the dry weight of mountain bark.
% to 50%. This flocculant may be in powder form,
It may also be a liquid that has been dissolved in an organic solvent in advance. Further, in order to make the material more soluble in a solvent, it may be pretreated if necessary. For example, in order to make polyethylene oxide more easily soluble in water, it may be treated with an alcohol such as isopropanol and then dissolved in water. The thus obtained water-kneaded ceramic base material is molded into a desired shape by a conventional method such as casting, potter's wheel molding, or extrusion molding.

In addition, if you want to obtain a paper-like composition, prepare a dispersion of Ichikatsuyamapi and a ceramic material and/or a material that becomes ceramic by firing, and if necessary, add powders of other subcomponents and co-disperse them. A paper-like composition can be obtained by making a pulp into a pulp and then making paper from it. The molded article thus formed is then frozen and dried.

In order to prevent the molded product from deforming, it is best to rapidly cool and freeze it immediately after molding. Methods for rapid freezing include liquid nitrogen, liquid air, liquefied ammonia, dry ice, dry ice cryogens, and other freeze-drying methods used in the food industry. Simple methods include, for example, injecting liquid nitrogen from above, and placing the molded product in dry ice coolant dissolved in alcohol, acetone, ether, etc. If the molded product is in a frozen state, drying does not need to be carried out while cooling the molded product, and it is sufficient to prevent silk fog. Normally, it is sufficient to leave the molded product in dry air, but in order to speed up drying, it is better to perform the drying under reduced pressure. Further, if the drying progresses and the molded product no longer deforms, the temperature of the molded product may be raised by flooding. For example, when it comes to ceramic honeycombs, thin plates, columns, rods, etc., this cannot be said unconditionally, depending on the moisture content of the ceramic base material, the thickness of the molded product, the content of mountain skin, etc., but dry air should be sent after cooling sufficiently. can be dried to the extent that it does not become deformed. The ceramic molded article obtained by the method of the present invention may be fired, if necessary. This firing can be carried out according to the conventional method for producing ceramic molded articles. According to the present invention, the drying time of the molded product is short, and even if the moisture content in the ceramic base material is as high as 99%, it can be molded and a molded product with high porosity can be obtained.

Moreover, since mountain bark becomes steatite, forsterite, cordierite, etc. by firing, the object of the present invention, which is fired and bonded, has greater physical strength than conventional ceramic molded products. The present invention will be explained in more detail with reference to Examples below.

Example 1 Ceramic base material A is prepared by uniformly mixing 9 parts of mountain bark, 5 parts of cordierite chamotte, 1 part of polyethylene oxide, and 4 parts of water.

Separately, 1 part of Kibushi clay, 5 parts of cordierite chamots, and 4 parts of water are uniformly mixed to prepare a base material B. Each is extruded into a long and slender column with a diameter of 5 ribs,
It was dropped into liquid nitrogen, frozen, and left at an environmental temperature of 20 qo and a reduced pressure of *6 mercury. The changes in temperature and moisture content over time at this time are as follows. From the above results, the ceramic base material A containing 10% mountain bark remains cool for a long time, and dries water approximately twice as quickly as the ceramic base material B containing Kibushi clay.

In the above experiment, the ceramic substrate A was dried without any deformation, but the ceramic substrate B was deformed 100 minutes after the start of drying. Example 2 63 parts of silicon nitride, 3 parts of mountain bark, 3 parts of kaolin, 0.5 part of polyethylene oxide, 0.5 part of glycerin, and 3 parts of water
The base portion is thoroughly kneaded to produce a plastic, water-kneaded ceramic base material (water content: 35% by weight).

This was put into a clay kneading machine and extruded to form a cylinder with a thickness of 1 side diameter of 3 cm and a length of 5 arcs. Then, this was frozen with liquid nitrogen, and then dry nitrogen gas was sent around the cylinder. is kept at about -1oo0. After about 30 minutes, the water content will be 10
% or less, and no matter which diameter of the cylinder was measured, it was 0.1 mm and no deformation was observed. When the mixture was placed in a furnace and heated to 1000 oo and fired for about 2 hours, a thin cylinder of silicon nitride sintered with kaolin and mountain bark was obtained. Example 3 5 parts of cordierite chamotte 5 parts of mountain bark, 4 parts of aluminum hydroxide, 1 part of methyl cellulose and 4 parts of water were thoroughly kneaded to prepare a cordierite ceramic material (moisture: 4 parts).
(wt%) (sample 1).

On the other hand, cordierite chamotte 5 parts, kibushi clay 1
The anchor part and the water sparse part are thoroughly kneaded to make a ceramic base material (water content 4% by weight) (Sample 2). After putting each sample into a syringe, extrude it to make a thin syringe with a diameter of one side. Immediately put this in a cryogen and freeze it.
I observed how the stick sagged by lying it on two fulcrums spaced apart from each other. The treatment that was applied is as shown in the table below. If the rod did not sag or bend during this treatment, it is marked as ○, and if it was bent even slightly, it is marked as ×.
, Those in which bending was observed only after the molded product was sintered at 1200 qo were rated △. There are 12 samples after each treatment.
When it was fired at 00x0, it solidified into a thin rod of cordierite, and even when heated to 1200 qo and immersed in water, it did not crack or crumble and maintained its thin rod shape.

Example 4 50 μm of an aqueous dispersion containing 30% purified mountain bark
5% ammonia water 1. After adding the cone r, add the Ferrite 45 mochi to it and mix well.

To this, 25 nails of water-soluble polymer Isoban 10 manufactured by Kuraray were added, approximately 10 cc of water was added, and the mixture was braised again and left overnight to form a ceramic base material (moisture content: 35% by weight). This is formed into a ring-shaped object with a thickness of 5 fences, 3 arcs in diameter, and 1 arc in height using a Dokyo machine, and after cooling it sufficiently in liquid nitrogen, dry air is poured into it for 1 hour.
When the moisture content is reduced to 8% or less over time and sintered at 85,000 for 4 hours, a ferrite ring coagulated with mountain skin is obtained.
When placed in this electromagnet and magnetized, a magnet is obtained. No deformation was observed in this molded product either. Example 5 An aqueous dispersion containing 30% of purified mountain bark was put into a clay bran machine at room temperature and extruded to form a cylinder with a diameter of 5.

Claims (1)

[Claims] 1. A ceramic base material characterized by using a ceramic base material whose solid content is at least 2% husk, in a method of molding a ceramic base material in which the ceramic base material is kneaded with water, then frozen and dried. molding method.