JPH0130782B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Background of the Invention] Technical Field The present invention relates to a method for manufacturing tubular or rod-shaped ceramics. Specifically, the present invention provides a method for producing porous ceramics particularly useful in tubular or rod-shaped porous ceramics, which aims to shorten the drying time after molding, prevent deformation after molding, and improve product quality uniformity. The present invention also relates to a method for manufacturing rod-shaped ceramics.

Prior Art Ceramic is defined as a nonmetallic inorganic solid material manufactured by heat treatment, and is generally obtained by molding a powder raw material into a desired product shape and then firing it. However, in recent years, attention has been paid to the excellent electromagnetic, optical, mechanical, and thermal properties of ceramics, and functional ceramics that take advantage of these properties through rigorous ceramic synthesis, so-called fine ceramics, are being used in various fields. It has been developed and is on the rise.

Due to its high hardness, general machining of ceramics after firing is difficult, and in ceramic synthesis, the steps of molding the powder raw material into the desired product shape and solidifying the molded product are very important.
A major problem in the molding and solidifying process is how to impart shape-retaining properties to ceramic powder raw materials that do not have shape-retaining properties, thereby making it possible to mold them into desired shapes and solidifying them. In particular, as powder raw materials for fine ceramics these days, artificially synthesized non-plastic raw materials such as alumina, zirconia, and ferrite are preferred, rather than plastic raw materials such as clay, which can obtain sufficient moldability just by moistening with water. Because raw materials are important and many are used, the molding and solidification processes require even more technological sophistication.

As a molding method for manufacturing tubular or rod-shaped ceramics, currently generally used are a slurry casting method using a mold, a wet pressure molding method, or an extrusion molding method. However, in the case of the slurry casting method and the wet pressure molding method that use molds, various problems arise, such as a difference in composition between the surface and center portions, occurrence of deformation, and reduction in physical strength. On the other hand, in the case of extrusion molding using, for example, an auger extrusion device, it is possible to obtain a tubular or rod-shaped ceramic product with almost uniform composition and a uniform cross section, but it takes a long time to dry the extruded product. Therefore, deformation of the molded product during this period was unavoidable.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide an improved method for manufacturing tubular or rod-shaped ceramics. The present invention also provides a tubular or rod-shaped ceramic material which is particularly useful as a method for producing tubular or rod-shaped porous ceramics, which aims to shorten the drying time after molding, prevent deformation after molding, and improve product quality uniformity. The purpose is to provide an improved manufacturing method.

[Structure of the Invention] The above-mentioned objects are to prepare a ceramic molding raw material composition containing a photosensitive resin, and to continuously extrude the obtained preparation using an extrusion molding machine. This can be achieved by a continuous manufacturing method for tubular or rod-shaped ceramics, which involves irradiating the molded product with light to harden the surface of the molded product, then drying and cutting the molded product, and then firing the molded product.

The most important feature of the present invention is that a photosensitive resin is contained in the ceramic molding raw material, and that the molded product is irradiated with light immediately after extrusion molding to cause the photosensitive resin to react and to harden the surface of the molded product. This improves the shape retention of the molded product and shortens the drying time.

Next, a method for continuously manufacturing tubular or rod-shaped ceramics according to the present invention will be specifically explained with reference to the drawings. FIG. 1 is a production line diagram showing the steps from ceramic raw material to molding, drying, and cutting to a fixed length in one embodiment of the method for producing tubular or rod-shaped ceramic according to the present invention. A material receiver 2 of an extrusion molding machine 1 is supplied with a ceramic powder raw material, a plasticity imparting agent, and an inorganic binder as necessary from a raw material tank 3 at a constant mixing ratio. Various ceramic powder raw materials are used depending on the purpose of use, and are not limited in any way, such as aluminum oxide, zinc oxide, titanium oxide,
Oxide-based materials such as manganese ferrite, silicon nitride, aluminum nitride, boron nitride, silicon carbide,
Includes non-oxide systems (nitrides and carbides) such as boron carbide. Inorganic binders that are included as necessary are added only in special manufacturing cases such as porous ceramics, but examples include sodium silicate, calcium salts, magnesium salts, cullet, clay, and stone powder. used.

The plasticizing agent includes a photosensitive resin and, if necessary, a solvent and other organic resin.

Photosensitive resins include photocrosslinkable photosensitive resins,
Either photodegradable photosensitive resins or photopolymerizable photosensitive resins can be used.

Photocrosslinkable photosensitive resins include dichromates such as ammonium dichromate and potassium dichromate, and water-soluble polymers such as gelatin, glue, egg white, gum arabic, shellac, polyvinyl alcohol, and polyacrylamide. dichromate-based photosensitive resins, and cinnamic acids such as polyvinyl alcohol-cinnamic acid ester (polyvinyl cinnamate), polyvinyl alcohol-p-methoxycinnamic acid/succinic acid half ester, and styrene maleic anhydride-cinnamic acid ester. Included are photodimerizable photosensitive resins such as esters, benzalacetophenones such as benzalacetophenone, stilbazoles, and those in which anthracene or rhodanine derivatives are introduced into the polymer.

Photodegradable photosensitive resins include, for example, diazo resins produced by condensing aldehydes and diazonium salts, diazo polymers produced by making amino novolak resins from novolak-type phenolic resins, and diazotizing the resins.
N-(2,5-diethoxy-4-nitrophenyl)
Polymerize acrylamide to reduce the nitro group and then diazotize it and diazonium salt to ω,
Diazonium salt systems such as mixtures of diazonium salts with polymers, such as mixtures of N-alkoxymethylated products of polyamides of ω'-diamines and ω,ω'-dicarboxylic acids, as well as benzoquinone-(1,4)- Diazizo(4)-2-sulfonic acid-β
- Diazo photosensitive resins such as p-quinonediazides and p-iminoquinonediazides such as naphthylamide, and 4,4'-diazidostilbene,
4,4'-Diazidochalcone, 2,6-di-(4'-
azidobenzal)-cyclohexanone, 2,6-
Di-(4'-azidobenzal)-methylcyclohexanone, 6-azito-2-(4'-azidostyryl)-
Combinations of azide compounds such as benzimidazole with reduced rubbers, rubbers such as styrene-butadiene rubber, nylons (polyamides), polyacrylamides, and azide phthalates such as partially saponified polyvinyl acetate, partially saponified cellulose acetate, gelatin, etc. Azidobenzoate of partially saponified polyvinyl acetate, m-azidobenzyl alcohol ester of styrene-acetic anhydride maleic acid copolymer, polyvinyl-p-azidobenzoate, polyvinylazidobenzal, polyvinylazidoacetate, 4-diazodiphenylamine-2- Azitized diazo resin obtained by condensing sulfonic acid etc. with formaldehyde, soluble polymer obtained by reacting epoxy resin (bisphenol type) with chlorosulfonyl or chlorocarbonyl-substituted azide allyl compound, and polybutadiene and p -Azide-based photosensitivity such as an azide polymer in which an azide group is bonded to a polymer such as a reaction product with azidophenylsulfenyl chloride, a polycondensation polymer of bisphenol A and 5-azidoisophthaloyl chloride, etc. resins, as well as other polymers with nitro groups, such as mixtures of condensates of 2-nitro-5-oxybenzaldehyde and phthalic acid, and novolak-type phenolic resins, 1,2,3-thiadiazoles, etc. Thiadiazole and thiazolidone systems such as polymers combined with bisphenolic polyesters having hydroxyl groups in the chain, sulfur compound systems such as combinations of tetramethylthiuram disulfide and methyl methacrylate and polystyrene having dithiocarbamate or xanthate groups; Included are halogen compound systems such as a combination of 2,5-dimethyl-ω,ω,ω-tribromoacetophenone and polyvinyl alcohol.

Photopolymerizable photosensitive resins include vinyl monomer independent photopolymerizable compositions, vinyl monomer + its polymer type, vinyl monomer + cellulose derivative type,
Vinyl monomer + saturated polymer systems, such as vinyl monomer + polyvinyl alcohol derivative type, vinyl monomer + polyamide type, vinyl monomer + polyacrylate type, vinyl monomer + polyurethane type, and vinyl monomer + poly(halogen-substituted 1,3-butadiene) type. compositions, unsaturated polymer-based compositions such as unsaturated polyvinyl acetal-based, unsaturated polyamide-based and unsaturated polyester-based, and photosensitive resin compositions utilizing similar reactions.

Among these photosensitive resins, cinnamic acid esters, photopolymerizable photosensitive resins, etc. are usually used, and vinyl-based and acrylic-based resins are preferably used. Of course, known photosensitive resins other than those mentioned above may also be used as the plasticity imparting agent in the present invention. These photosensitive resins are mixed at least in an amount that can prevent deformation during drying of the extrusion molded product, and are also related to the porosity of ceramic fired products, but they are usually used as ceramic powder raw materials.
3 to 30 parts by weight, preferably 5 parts by weight per 100 parts by weight
~25 parts by weight is blended. Furthermore, it is also possible to add an appropriate sensitizer to the photosensitive resin to accelerate curing. For example, in the case of polyvinyl cinnamate, p-nitrodiphenyl, p-nitroaniline, 2,4-dinitroaniline, picramide, 2
-Chloro-4-nitroaniline, 2,6-dichloro-4-nitroaniline, p,p'-dimethylaminobenzophenone, p,p'-tetramethyldiaminobenzophenone, anthraquinone, 1,2-benzanthraquinone , anthrone or 3-methyl-1,3-diaza-1,9-benzanthrone significantly increases photosensitivity.

Other organic resins, which may be included as plasticizers as needed, are included when the photosensitive resin is not sufficient to dry and harden the extruded product when it is dried. These other organic resins include polyvinyl alcohol, vinyl acetate resin, acrylic resin, styrene resin, epoxy resin, polyester resin, urethane resin, and the like. Further, gum arabic, starch paste, wax, carboxymethyl cellulose, etc. may also be used. Although these are related to the porosity of fired ceramic products, they are usually added in an amount of 1 to 25 parts by weight, preferably 2 to 20 parts by weight, per 100 parts by weight of ceramic raw material powder.

Further, other solvents that may be included as plasticizers as required depend on the properties of the photosensitive resin and other organic resins.

The raw materials supplied from the material receiver 2 into the extrusion molding machine 1 are mixed by a screw in the extrusion molding machine.
It is degassed and extruded from an extrusion die 4.
Note that the extrusion die 4 can be arbitrarily changed depending on the desired cross-sectional shape and diameter of the tube or rod-shaped molded product. Molded product 9 extruded from extrusion die 4
The entire surface is immediately irradiated with light by the light source lamp 5. As a result, the photosensitive resin contained in the irradiated surface of the molded article 9 reacts and hardens, and the entire surface of the molded article 9 is solidified to become a surface-hardened molded article 9'. As the light source lamp 5, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a carbon arc lamp, an ultraviolet fluorescent lamp, a xenon lamp, etc. can be used, but usually a low-pressure mercury lamp and a high-pressure mercury lamp are mainly used.
The surface-hardened molded product 9' is then introduced into the heating and drying oven 6 without changing its shape. The molded product 9' introduced into the heating drying oven 6 is cured by the action of heat to harden the uncured photosensitive resin, other organic resins, and solvent contained in the molded product 9' and vaporize it to solidify it to the center. The drying molded product 9'' is then dried to form a dried molded product 9''.A large number of hot air outlets 12 are provided on the entire inner surface of the heating drying oven 6, so that the molded product 9' can be uniformly heated and dried.The dried molded product 9'' is cut by a cutting machine. After being cut into a certain size by 8, it is introduced into a firing furnace 11 as shown in FIG. The dry molded product 9'' cut to a certain size is heated and fired in a firing furnace 11 at a firing temperature of, for example, 1300°C to 1600°C by a conventional method to form a rod-shaped or tubular ceramic product 9.
becomes.

[Specific Effects of the Invention] As described above, the present invention enables the manufacture of tubular or rod-shaped ceramics by incorporating a photosensitive resin into the ceramic molding raw material composition, and then extruding the obtained preparation into an extrusion molding machine. Extrusion molding is carried out continuously in a machine, the extruded molded product is irradiated with light to harden the surface of the molded product, and then the molded product is dried, cut, and fired, so that the molded product can be molded immediately after extrusion. The shape of the molded product can be kept constant, and ceramic products of uniform quality can be obtained without deformation of the molded product during the drying stage. In addition, the light irradiation step is carried out before the heat drying step to harden the photosensitive resin, which is more reactive than conventional plasticizers, making it possible to shorten drying time and continuously forming tubular or rod-like shapes. Ceramic products can be manufactured. In particular, when a tubular or rod-shaped ceramic product has a small diameter or a thin wall thickness, the manufacturing method according to the present invention has a great effect. Even tubular products can be manufactured with high quality, and this effect is particularly noticeable in the case of porous ceramics.

[Brief explanation of drawings]

Fig. 1 shows a production line from ceramic raw material to molding, drying, and cutting to a fixed length in an embodiment of the method for producing tubular or rod-shaped ceramics according to the present invention, and Fig. 2 shows a production line for producing tubular or rod-shaped ceramics according to the present invention. A ceramic firing line in one embodiment of the method is shown, and FIG. 3 is a longitudinal sectional view of a heating drying furnace. 1...Extrusion molding machine, 2...Raw material receiver, 3...
Raw material tank, 4... Extrusion die, 5... Light source lamp, 6... Heat drying oven, 7... Molded product take-up device, 8... Cutting machine, 9, 9', 9''... Ceramic molded product, 9 ... Ceramic fired product, 10 ... Cart, 11 ... Ceramic firing furnace, 12 ... Hot air outlet.

Claims (1)

[Claims] 1 Prepare a ceramic molding raw material composition by incorporating a photosensitive resin, continuously extrude the obtained preparation using an extrusion molding machine, and irradiate the extruded molded product with light to change the surface of the molded product. 1. A continuous manufacturing method for tubular or rod-shaped ceramics, which comprises curing, drying the molded product under heat, cutting, and firing the molded product.