JPH06191923A - Plastic material for in-mold extrusion - Google Patents

Abstract

PURPOSE:To obtain a three-dimensional near-net-shape ceramic formed article having excellent mold-releasability by compounding ceramic powder with water and N-lauroyl-aspartic acid beta-lauryl ester. CONSTITUTION:This plastic material 1 for in-mold extrusion is produced by compounding 100 pts.wt. of ceramic powder with 0.5-2 pts.wt. of N-lauroyl- aspartic acid beta ester, a water-soluble binder and water. The plastic material 1 is filled in an extrusion cylinder 2. The extrusion cylinder 2, an extrusion piston 6 and a four-part mold 3 having a valveshaped cavity 3a are clamped between a base 4 and a mobile bed 5 and the extrusion piston 6 is lowered to extrude the plastic material 1 through the opening at the bottom of the extrusion cylinder 2 into the cavity 3a to obtain a formed article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic material for in-mold extrusion, and more particularly to a plastic material for obtaining a ceramic molded body by in-mold extrusion.

[0002]

2. Description of the Related Art An extrusion molding method is known as a conventional method for molding a ceramic molded body. A general extrusion molding method is to prepare a clay-like plastic material consisting of ceramic powder, water, a binder, a dispersant, a lubricant and a plasticizer, attach a die having a desired cross-sectional shape to the extruder, and from this die The plastic material is extruded to obtain a rod-shaped ceramic compact ("Ceramics Material Technology Collection", published in April 1979), "Fundamental and applied technology of binders for fine ceramics / metal powder molding", December 1988 10 issues).

[0003]

However, in the above-mentioned conventional extrusion molding method, it is possible to continuously mass-produce rod-shaped products such as pipes, honeycombs and plates whose cross-sectional shape does not change in the longitudinal direction. However, it is not possible to form a three-dimensional ceramics molded body whose cross-sectional shape changes in the longitudinal direction.

Further, in the conventional extrusion molding method, since a ceramic molded body is obtained by extrusion, the cavity is not filled with the plastic material, and the releasability of the plastic material has not been considered. Therefore, when in-mold extrusion into the cavity is performed to obtain a three-dimensional ceramics molded body using the plastic material used in the conventional extrusion molding method, the ceramics molded body sticks to the cavity surface and Cannot be easily removed from the mold. This is similar to the case where the ceramic powder is hardened by the adhesive in the plastic material in which only water and a water-soluble binder such as methylcellulose are added, and if this plastic material is extruded into the cavity, the water-soluble This is because the ceramic molded body adheres to the cavity surface due to the binder and is difficult to peel off.

Therefore, it is difficult to obtain a three-dimensional shaped near net shape ceramics molded body with excellent mold releasability using conventional plastic materials. The present invention has been made in view of the above conventional circumstances, and provides a plastic material for in-mold extrusion capable of obtaining a three-dimensional shape near net shape ceramics molded body under excellent mold releasability. The purpose is to

[0006]

The plastic material for in-mold extrusion of the present invention is extruded into a cavity having a three-dimensional shape, filled in the cavity by the pressure during extrusion, and shaped in the cavity. A plastic material for in-mold extrusion containing ceramic powder, water and a water-soluble binder, wherein the in-mold extrusion plastic material contains N-lauroyl / aspartic acid / β-lauryl ester. is there.

The amount of N-lauroyl / aspartic acid / β-lauryl ester is preferably 0.5 to 2 parts by weight with respect to 100 parts by weight of the ceramic powder contained in the in-mold extrusion plastic material.

[0008]

In the plastic material for in-mold extrusion of the present invention, the plastic material flows in the cavity and is filled in the three-dimensional cavity by the pressure during extrusion and is shaped in the cavity. Since the shaped plastic material contains N-lauroyl / aspartic acid / β-lauryl ester, the solvent is less likely to seep out between the mold and the ceramic molded body, so that the function as a water-soluble binder can be obtained. Easier to remove from the mold than conventional plastic materials.

When the amount of N-lauroyl / aspartic acid / β-lauryl ester is 0.5 to 2 parts by weight based on 100 parts by weight of the ceramic powder contained in the plastic material for in-mold extrusion, demolding is easy. It also has good shape retention. When the amount of N-lauroyl / aspartic acid / β-lauryl ester is less than 0.5 parts by weight based on 100 parts by weight of the ceramic powder, the effect of improving the releasability is small,
If the amount exceeds 2 parts by weight, the number of bores increases after degreasing the ceramic molded body, the shape retention is likely to be impaired, and the density is unlikely to increase.

[0010]

EXAMPLES Examples 1 to 4 in which the plastic material for in-mold extrusion of the present invention is embodied and ceramic moldings are obtained by a kneading step and an in-mold extrusion step will be described together with Comparative Example 1 with reference to the drawings. (Example 1) {Kneading step} First, Si ₃ N ₄ powder (average particle size 0.2 μ)
m) 90 parts by weight, Y ₂ O ₃ powder (average particle size 0.2 μm)
6 parts by weight, MgAl ₂ O ₄ powder (average particle size 0.2 μm)
4 parts by weight are prepared. Y ₂ O ₃ powder and MgAl ₂ O
₄ powder is a sintering aid for Si ₃ N ₄ powder. These were mixed in ethanol and then passed through a sieve with a mesh opening of 10 μm to obtain a ceramic powder.

To 100 parts by weight of ceramic powder, 34 parts by weight of water, 0.7 parts by weight of polycarboxylic acid ammonium salt as a dispersant, and methyl cellulose as a water-soluble binder (SM4000 manufactured by Shin-Etsu Chemical Co., Ltd.) 0 parts by weight,
1.0 part by weight of glycerin as a plasticizer and N-lauroyl aspartic acid.
β-lauryl ester (C ₁₂ H ₂₅ NHC (CH ₂ COO
C ₁₂ H ₂₅ ) HCOOH and specific gravity: 1.0) 0.9 parts by weight are respectively added and sufficiently mixed and kneaded by a kneader to obtain a plastic material for in-mold extrusion. {In-mold extrusion step} As shown in FIG. 1, this plastic material 1
Is filled in the extrusion cylinder 2. In addition, as shown in FIG. 2, the stem diameter is 8 mm, the total length is 120 mm, and the umbrella diameter is 4.
A four-divided mold 3 having a 0 mm bulb-shaped cavity 3a is prepared.

By sandwiching the extruding cylinder 2, the extruding piston 6, and the mold 3 between the base 4 and the movable table 5 which can be moved up and down with respect to the base 4, and lowering the extruding piston 4, From the opening at the lower end of the extrusion cylinder 2, the molding pressure 60
The plastic material 1 is extruded into the cavity 3a at MPa. In this way, the plastic material 1 is filled and shaped in the cavity 3a.

After that, when the molds 3 were removed one by one,
The ceramic molded body does not stick to the surface of the cavity 3a,
In addition, the shape retaining property was also good, and the mold could be easily removed from the cavity 3a. Example 2 A plastic material for in-mold extrusion is obtained in the same manner as in Example 1 except that 0.5 part by weight of N-lauroyl / aspartic acid / β-lauryl ester is used. And Example 1
Kneading and in-mold extrusion are performed in the same manner as in.

Also in this plastic material, the ceramic molded body did not stick to the cavity surface and had a good shape-retaining property, and could be easily released from the cavity. (Example 3) As shown in FIG. 3, the diameter is 20 mm and the total length is 7
Four-divided mold 7 having 0 mm cylindrical cavity 7a
To prepare. The other conditions are the same as in Example 1.

Even when this mold 7 was used, the ceramic molded body did not stick to the cavity surface, had good shape retention, and could be easily removed from the cavity. (Embodiment 4) The same mold 7 as in Embodiment 3 is adopted, and the plastic material of Embodiment 2 is adopted. Then, kneading and in-mold extrusion are performed in the same manner as in Example 1.

Even when this mold 7 was used and this plastic material was used, the ceramic molded body did not stick to the cavity surface, had good shape retention, and could be easily released from the cavity. (Comparative Example 1) A plastic material for in-mold extrusion is obtained in the same manner as in Example 1 except that N-lauroyl / aspartic acid / β-lauryl ester is not added. Then, kneading and in-mold extrusion are performed in the same manner as in Example 1.

With this plastic material, it was possible to fill the cavity, but the plastic material stuck to the cavity surface, and the mold could not be released from the cavity unless the shape of the ceramic molded body was destroyed. Therefore, the plastic materials of Examples 1 and 2 contain N-lauroyl / aspartic acid / β-lauryl ester, which facilitates demolding, has good shape retention, and has a three-dimensional valve shape or It can be seen that a cylindrical near net shape ceramics compact can be obtained.

As the ceramic powder, Si is used.₃N
_FourIn addition to powder, SiO₂Powder, Al ₂O₃Adopt powder etc.
can do. Water is 100% by volume of ceramic powder
On the other hand, it is preferable that the content is 100 to 130% by volume.
Yes. 100 bodies of water for 100% by volume of ceramic powder
If it is less than the product%, the plastic material is unlikely to be clay-like.
Water is 130% by volume with respect to 100% by volume of ceramic powder
If it exceeds, the shape retention of the ceramic molded body is poor. Water is
105-120 bodies per 100% by volume of ceramic powder
More preferably, it is contained in a volume percentage.

As the water-soluble binder, starch, dextrin, glue, casein, gelatin, etc. can be adopted in addition to celluloses such as methyl cellulose.
Here, the water-soluble binder is preferably contained in an amount of 1 to 15% by volume based on 100% by volume of the ceramic powder. If the water-soluble binder is less than 1% by volume with respect to 100% by volume of the ceramic powder, the ceramic molded body tends to crack after drying. Water-soluble binder is 100 ceramic powder
If it exceeds 15.0% by volume with respect to the volume%, the water-soluble binder is likely to agglomerate and a strength defect is likely to occur in the sintered ceramic.

The plastic material may contain a dispersant. As the dispersant, polycarboxylic acid ammonium salt, acrylic acid oligomer NH ₄ salt, polyacrylic acid soda, copolymer oligomer NH ₄ salt of 70% by weight of acrylic acid and 30% by weight of methyl acrylate, and the like can be adopted. . Here, the dispersant is preferably contained in an amount of 1 to 8% by volume with respect to 100% by volume of the ceramic powder.

The extrusion pressure, extrusion speed, extrusion time and the like of the plastic material can be selected depending on the thixotropy of the plastic material and the shape of the cavity.

[0022]

As described above in detail, with the plastic material of the present invention, a ceramic molded body corresponding to a cavity having a three-dimensional shape can be obtained, so that a molded article having a complicated shape can be formed as compared with the conventional extrusion molding method. It will be possible. Since this plastic material contains N-lauroyl / aspartic acid / β-lauryl ester, it is possible to obtain a near-net-shape ceramic molded body having a three-dimensional shape with excellent releasability.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a step of a molding method of Examples 1 and 2 and Comparative Example 1.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a schematic cross-sectional view showing the steps of the molding method of Examples 3 and 4.

FIG. 4 is a sectional view taken along the line BB of FIG.

[Explanation of Codes] 3a, 7a ... Cavity 1 ... Plastic material for in-mold extrusion

Claims (1)

[Claims] 1. In-mold extrusion including a ceramic powder, water and a water-soluble binder, which is extruded into a cavity having a three-dimensional shape, is filled in the cavity by pressure during extrusion, and is shaped in the cavity. A plastic material for in-mold extrusion, wherein the plastic material for in-mold extrusion contains N-lauroyl / aspartic acid / β-lauryl ester.