JPH0450157A - Ceramic material for extrusion molding and process for extrusion molding of the material - Google Patents

Abstract

PURPOSE:To improve the density and strength of a ceramic material by mixing a ceramic material with a polysaccharide originated from microorganism, an acrylic acid oligomer, a specific plasticizer and water. CONSTITUTION:The objective ceramic for extrusion molding is produced by using (A) 100 pts.wt. of a ceramic material (e.g. SiC) having a purity of 2 99% and particle diameter of <=1mum, (B) 2-5 pts.wt. of a polysaccharide originated from microorganism (e.g. paramylon), (C) <=2 pts.wt. of an acrylic acid oligomer, (D) <=3 pts.wt. of at least one kind of plasticizer selected from wax, paraffin and stearic acid, (E) water and, as necessary, (F) <=3 pts.wt. of one or more kinds of binders selected from PVA, methylcellulose, CMC and hydroxypropyl methyl cellulose. The material is supplied through a feeding port 1 of a vented extruder 5 to a feeding channel 2, compressed with a screw 4 under an extrusion pressure of >=60kgf/cm<2> under deaeration and extruded through a die 3.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a ceramic material for extrusion molding and an extrusion molding method for obtaining a ceramic fired body having high density and high strength by extrusion molding. .

[Prior Art] Conventionally, as a ceramic material for extrusion molding, a cellulose compound such as methyl cellulose is generally used as a binder, a polyhydric hydroxy compound such as glycerin is used as a plasticizer, and these are contained in the ceramic material. It has been known. For example, JP-A-5B-1148
The one described in Publication No. 63 is known.

[Problems to be Solved by the Invention] However, with conventional extrusion-molding ceramic materials, the ceramic fired body obtained by extrusion-molding and firing does not have sufficient density and bending strength, and has a complex shape. Since it is unsuitable for manufacturing objects, there has been a strong desire for a ceramic material for extrusion molding to obtain ceramic fired bodies with high density and high bending strength, as well as complex shapes.

In view of the above, the present invention has been developed to produce a ceramic body for extrusion molding in which the fired ceramic body obtained by firing has high density and excellent properties of high strength, and has little variation in strength even when having a complex shape. The purpose of this invention is to provide a material and a method for extrusion molding the same.

[Means for Solving the Problems] The first aspect of the present invention is to add 2 to 5 parts by weight of polysaccharides of microbial origin, 2 parts by weight or less of acrylic acid oligomers, wax, paraffin, and stearic acid to 100 parts by weight of the ceramic material. A second aspect of the present invention is a ceramic material for extrusion molding containing a mixture of 3 parts by weight or less of at least one of these and a predetermined amount of water.
0 parts by weight, a total amount of 2 to 7 parts by weight of polysaccharides of microbial origin and at least one of polyvinyl alcohol, methylcellulose, carboxymethylcellulose, and hydroxypropylmethylcellulose, 2 parts by weight or less of acrylic acid oligomers, wax, paraffin, It is a ceramic material for extrusion molding containing a mixture consisting of 3 parts by weight or less of one type of stearic acid and a predetermined amount of water. , carboxymethyl cellulose, and hydroxypropyl methyl cellulose at the same mixing ratio, or it is desirable to mix more polysaccharides of microbial origin.

The ceramic material serving as the raw material powder may be any oxide-based ceramic powder material such as alumina, zirconia, mullite, and cordierite. In addition, oxide-based ceramic powder materials such as magnesia and zirconia, carbide-based ceramic powder materials such as silicon carbide and titanium carbide, and nitride-based ceramic powder materials such as silicon nitride and boron nitride, which have the above-mentioned materials as main components, and It may also be a mixture of It is desirable that the ceramic powder has a particle size as small as possible, particularly preferably a particle size of 1 μm or less, and more preferably a particle size of 0.5 μm or less. In addition, it is desirable that the purity of the ceramic material be as high as possible9.
It is preferably 9% or more, more preferably 99.9% or more.

In addition, the polysaccharides originating from microorganisms are preferably glucan-based polysaccharides, and β-1,3-glucan containing β-1,3-glycoside such as paramylon, curdlan, and soufflenoglucan has good water retention and plasticity. It is more preferable from the viewpoint of

This polysaccharide of microbial origin is compatible with the ceramic powder and is used as a plasticizer and binder, and is used in an amount of 2 to 5 parts by weight per 100 parts by weight of the ceramic material. Also, polyvinyl alcohol, methyl cellulose,
Carboxymethyl cellulose and hydroxypropyl methyl cellulose are also used as binders, and a mixture of these and the above-mentioned polysaccharides of microbial origin is used to form ceramic material 1.
Add 2 to 7 parts by weight per 00 parts by weight. The above addition amount was limited to 2 to 5 parts by weight or 2 to 7 parts by weight because
If the amount added is less than this range, the shape will collapse during extrusion molding, making it impossible to obtain an extruded product, and if the amount added is too large, the ceramic fired product will have the high strength and high density that is the objective of the present invention. This is because it will not be possible to obtain Furthermore, in the embodiment of the second invention, the mixing ratio of the polysaccharide of microbial origin and at least one of polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, and hydroxypropyl methyl cellulose is the same, or the polysaccharide of microbial origin is blended in a larger amount. As a result, a fired ceramic body having superior strength and density and less variation in strength can be obtained.

In addition, by incorporating the mixture into the ceramic material according to the above formulation, the mixture is easily compatible with the ceramic material powder and other additives, so that the ceramic material for extrusion molding becomes uniform, and furthermore, the ceramic material for extrusion molding becomes uniform. By extrusion molding, by applying appropriate pressure, the gaps between the ceramic material powders are reduced and the ceramic material powders come closer to each other), and an extruded product with high density can be obtained, and furthermore, this can be fired. As a result, it is possible to obtain a fired ceramic body having a high density, and a product with little variation in strength.

Then, to the above mixture, 2 parts by weight or less of acrylic acid oligomer (not including 0) as a deflocculant, and 3 parts by weight or less of at least one of wax, stearic acid, and paraffin (preferably emulsion) as a lubricant (0 is not included). By adding (excluding) ceramic materials, it is possible to uniformly mold and extrude the ceramic material, and it is effective for extrusion molding of materials having complicated cross-sectional shapes, such as L angles, honeycomb materials, rectangular hollow materials, etc.

A third aspect of the present invention is to supply the ceramic material for extrusion molding according to the first aspect into the supply route from the supply port, and to direct the ceramic material to the nozzle provided at one end of the supply route for 60 kg.
This is an extrusion molding method of a ceramic material for extrusion molding, which pressurizes at an extrusion pressure of gf/c12 or more and molds an extrusion molded product from the die.

A fourth invention is a method of extrusion molding the ceramic material for extrusion molding according to the second invention by a method similar to the third invention.

Specifically, a ceramic material for extrusion molding according to the present invention is obtained, and this is supplied into the supply route 2 from the supply port 1 of the vacuum extrusion device 5 shown in FIG. 6 while degassing towards the cap 3 provided at one end.
Pressurize with the screw 4 at an extrusion pressure of 0 kgf/cm 2 or more.

Here, the extrusion pressure was set to 60 kgf/c12 or more.
This is because if extrusion is performed at a pressure lower than 0 kgr/Cm2, extrusion molding becomes difficult, and it becomes impossible to obtain a ceramic fired body having the density and bending strength that are the objectives of the present invention.

More preferably, by setting it to 60 kgf/c+a' or more, the molding density can be improved and higher strength and density can be achieved. Furthermore, by drying the extrusion molded product extruded from the die 3 and firing it, a ceramic fired body having a high density and high strength, with little variation in strength, and having a complex shape can be obtained. In addition, conventional products that use a cellulose compound as a binder and a polyhydric hydroxy compound as a plasticizer, and contain these in a ceramic material, usually have a yield of 50 to 60 kgf/c.
It is molded at an extrusion pressure of m2.

This is because if the pressure is lower than this range, a product with good shape retention may not be obtained, and in some cases, extrusion molding may not be possible, and if the pressure is higher than this range, dry cracking of the extruded product becomes noticeable.

[Example] The present invention will be specifically described below with reference to Examples. Particle size 1
100 parts by weight of alumina powder below μ-, 2 parts by weight of polysaccharide of microbial origin whose main component is curdlan, 2 parts by weight of methyl cellulose, 0.5 parts by weight of paraffin, 1 part by weight of acrylic acid oligomer, 17. A mixture of 5 parts by weight was thoroughly kneaded using a kneader, and the obtained ceramic material for extrusion molding was extruded using a vacuum extruder at a pressure of 60 kg.
Extrusion molding was carried out in a degassing atmosphere of 750+a+aHg or more under the conditions of f/cm2 and extrusion speed of 300 to 400+ni/win to obtain an extruded product. After sufficient degreasing (additive thermal decomposition) at a temperature of 300 to 400°C, 1600°C
A ceramic fired body was obtained by firing at normal pressure for 2 hours.

The alumina powder used above was 99% α-
Alumina was used as an extrusion mold (die) of a vacuum extrusion device using an asymmetrical solid material, 40 x 20 mm, single angle material mold (wall thickness: 5 mm).

For comparison, 100 parts by weight of alumina powder with a particle size of 1 μm or less, 2.5 parts by weight of glycerin, and 7 parts by weight of methyl cellulose were added.
．． 5 parts by weight of acrylic acid oligomer, 1 part by weight of acrylic acid oligomer, and 25 parts by weight of ion-exchanged water were kneaded in a mixer, extrusion molded under suitable conditions, and fired to obtain a ceramic fired body. Note that the alumina powder, vacuum extrusion device, and extrusion die used are the same.

The density and bending strength of the ceramic fired body obtained as described above were measured.

According to the measurement results, the density of the comparative example is 3.72 grams.
', whereas in the case of the present invention, it is 3,92g/cm
3, and the bending strength of the comparative example is 257 MPa.
In contrast, the pressure of the present invention is as high as 421 MPa,
Furthermore, when we created a Weibull probability distribution (shown in Figure 2) of the bending strength of the fired ceramic body according to the present invention, it was found that the Weibull coefficient was as high as 21, indicating that the strength had little variation and was excellent in uniformity.

Figure 3.4 shows the results of measuring the density and bending strength of the fired ceramic body as a result of varying the amounts of polysaccharide of microbial origin and methyl cellulose in the above formulation.

Note that the other blending amounts except for ion-exchanged water are the same as above.

As shown in Figure 3.4, only polysaccharides of microbial origin are
5 parts by weight or 2 to 6 parts by weight of polysaccharides of microbial origin and methylcellulose, and the mixing ratio of polysaccharides of microbial origin and methylcellulose is the same, or the polysaccharide of microbial origin is blended in a larger amount. It can be seen that the material has excellent density and bending strength.

Furthermore, as a result of conducting similar experiments on other complex cross-sectional shapes with the same composition as above, similar density, bending strength, and Weibull coefficient were obtained for honeycomb materials, rectangular hollow materials, etc., and the present invention By using the ceramic material for extrusion molding, it is possible to obtain ceramic fired bodies having high density and high strength, and with little variation in strength, not only with simple cross-sectional shapes but also with complicated cross-sectional shapes.

In addition, 100 parts by weight of the above alumina powder with a particle size of 1μ or less, 2 parts by weight of polysaccharide of microbial origin whose main component is curdlan, 2 parts by weight of methylcellulose, 0.5 parts by weight of paraffin, 1 part by weight of acrylic acid oligomer, and ions. Exchange water 17
．． The bending strength of the fired ceramic body against extrusion pressure was measured using a mixture of 5 parts by weight, and the results are shown in FIG. Extrusion pressure 60kgf 7c as shown in Figure 5
When the extrusion pressure is 60 kgf/c+++2 or less, the bending strength tends to be stabilized. It is also seen that the bending strength aimed at by the present invention can be obtained at an extrusion pressure of about 60 kgf/cm2.

Further, similar measurements were performed on formulations of the present invention different from those described above, and almost the same results were obtained.

[Effects of the Invention] As described above, according to the present invention, by obtaining a ceramic material for extrusion molding containing a mixture consisting of the above-mentioned formulation in the ceramic material, the ceramic fired body obtained by firing has a high density, In addition, it has excellent properties of high strength, and even products with complicated shapes can be obtained with little variation in strength.

Moreover, by the extrusion molding method of the ceramic material for extrusion molding described above, a fired ceramic body having such excellent properties can be easily obtained even if it has a complicated shape.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanatory diagram of the present invention, FIG. 2 is a diagram showing the Weibull probability distribution of the ceramic fired body according to the present invention, and FIG.
．． FIG. 4 is a diagram showing the measurement results of density and bending strength for each formulation, and FIG. 5 is a diagram showing the measurement results of bending strength with respect to extrusion pressure. ■... Supply port, 2... Supply route, 3... Cap, 4
...Screw 5...Extrusion device.

Claims (6)

[Claims] (1) For 100 parts by weight of the ceramic material, 2 to 5 parts by weight of polysaccharides of microbial origin, 2 parts by weight or less of acrylic acid oligomers, and 3 parts by weight or less of at least one of wax, paraffin, and stearic acid are specified amounts. A ceramic material for extrusion molding containing a mixture of water and water. (2) Total amount of microbial-originated polysaccharides and at least one of polyvinyl alcohol, methylcellulose, carboxymethylcellulose, and hydroxypropylmethylcellulose, based on 100 parts by weight of the ceramic material
7 parts by weight of an acrylic acid oligomer, 2 parts by weight or less of an acrylic acid oligomer, 3 parts by weight or less of at least one of wax, paraffin, and stearic acid, and a predetermined amount of water. (3) A claim in which the polysaccharide of microbial origin and at least one of polyvinyl alcohol, methylcellulose, carboxymethylcellulose, and hydroxypropylmethylcellulose are mixed in the same ratio, or the polysaccharide of microbial origin is blended in a larger amount ( 2) The ceramic material for extrusion molding described above. (4) A predetermined amount of 2 to 5 parts by weight of polysaccharide of microbial origin, 2 parts by weight or less of acrylic acid oligomer, and 3 parts by weight or less of at least one of wax, paraffin, and stearic acid per 100 parts by weight of the ceramic material. A ceramic material for extrusion molding containing a mixture of water and water is supplied into the supply route from the supply port, and is heated to an extrusion pressure of 60 kgf/cm^2 or more toward the nozzle provided at one end of the supply route. 1. A method for extrusion molding a ceramic material for extrusion molding, characterized in that a molded product is formed by pressurizing the ceramic material using the die and extruding it from the die. (5) Total amount of at least one of polysaccharides of microbial origin and polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, and hydroxypropyl methyl cellulose, based on 100 parts by weight of the ceramic material, 2 to 2 parts by weight
7 parts by weight of acrylic acid oligomer, 2 parts by weight or less of acrylic acid oligomer, 3 parts by weight or less of at least one of wax, paraffin, and stearic acid, and a predetermined amount of water. The product is supplied into a supply route, pressurized with an extrusion pressure of 60 kgf/cm^2 or more toward a nozzle provided at one end of the supply route, and extruded from the nozzle to form a molded product. Extrusion molding method of ceramic material for extrusion molding. (6) Claim (5) wherein the polysaccharide of microbial origin and at least one of polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, and hydroxypropyl methyl cellulose are mixed in the same ratio or the polysaccharide of microbial origin is blended in a larger amount. ) Extrusion molding method of the ceramic material for extrusion molding described.