JPS60118663A - Manufacture of dewaxing agent for ceramic injection formation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing a degreasing material for ceramic injection molding.

[Prior art]

Injection molding is used as a method for mass producing ceramic structures. This injection molding was originally developed as a type of plastic molding method, in which the molding material is heated and melted in the injection cylinder of an injection molding machine, and then the fluidized molding material is inserted into a mold that is tightly closed in advance by an injection plunger. It is injected into the mold cavity to completely fill it, and then cooled and solidified or hardened to form a molded product.

In manufacturing a ceramic structure, first, ceramic powder is mixed with an organic binder, and the mixture is injection molded to form a ceramic injection molded body of a predetermined shape. Next, a degreasing treatment is performed to cause organic components to flow out and scatter from the ceramic injection molded body, and then the ceramic injection molded body is heated to a predetermined temperature and sintered to obtain a desired ceramic structure.

By the way, in the manufacturing process of the above ceramic structure,
Degreasing is an important step and is usually carried out by placing the ceramic injection molded body in a degreasing furnace and heating it in an inert atmosphere at a temperature increase rate of 1 to 5°C/hr. At this time, a degreasing material (pad material) may be used to help drain and scatter organic components such as degreased from the ceramic injection molded body. This degreasing material is usually made of a porous ceramic material and assists in the smooth removal of organic components from the ceramic injection molded body.

Conventionally, as such a degreasing material, commercially available particles iM 0.1μ~
10μ fine particle degreasing material, or particle size 10μ~1000p
A coarse degreasing material is used. However, this Q degreasing material is not sufficient, and according to the present inventor, the particle size is 0.
It was confirmed that a degreasing material having a particle size of 50 μ to 2000 μ and having an aggregate structure in which fine particles of 1 μ to 100 μ are gathered together is suitable for degreasing treatment.

As a manufacturing method for such a degreasing material, initially 0.1
A spray dryer method is used in which primary particles of μ~10011 are placed in a 0.1~0.3% polyvinyl alcohol solution, stirred thoroughly, and then put into a spray dryer for granulation. Add water, granulate while rotating, and sieve to a grain size of 5,071 to 2,000. , u, and dry it in a dryer 1'['100~200
A sieve-separation method was used to dry at ℃ for 10 to 20 hours.

However, the degreasing material manufactured by such a manufacturing method has a problem that, although it has sufficient strength against heat, once it is used, it becomes difficult to reuse due to thermal deterioration.

Further, there is a problem that particle size control is difficult and the yield is poor.

Furthermore, there is a problem in that the packing density of the degreasing material is not properly controlled, resulting in variations in porosity, strength, etc.

[Purpose of the invention]

The present invention was made to solve the problems of the prior art described above, and an object of the present invention is to provide a method for producing a degreasing material for ceramic injection molding that has excellent heat resistance through desired particle size and packing density.

[Structure of the invention]

Such purpose, according to the invention, is achieved by reducing the particle size from 0.1μ to 100μ
Particle size of 50μ~ from primary particles made of μ ceramic
A method for producing a degreasing material for ceramic injection molding having a particle size of 2000μ, the method comprising: (a)-particle size of 0.17Z;
A step of preparing primary particles consisting of ceramic particles of ~100μ, (b) a step of mixing at least 1 part by weight of these primary particles with 1 part by weight of an organic binder to obtain a mixture, (c) a step of obtaining a mixture of A step of extruding the extruded molded product to a suitable diameter size within the range of 50μ to 2000μ, (d) a step of cutting the extruded molded product into a size with a bulk of 50μ to 2000μ, and (e) a step of cutting the cut molded product This is accomplished by a step of heating to remove organic components, and then a step of calcining the degreased material from which the organic components have been removed at a temperature in the range of 800°C to 1400°C.

In the present invention, the materials used in the method for producing a degreasing material for ceramic injection molding include nitrides such as silicon nitride (Si, N4), aluminum nitride (A7!N), and 1iII+ element nitride (BN), and silicon carbide (SiC). , titanium carbide (T i C
), alumina (Al2O2), zirconia (
Oxides such as ZrO2), titanium oxide (TiO, ), barium oxide (BaO), titanium boride (T i B
z) Borides such as RE-modified lysirconium ZrB2),
Oxynitrides such as Sialon, activated carbon, etc. can be used. At this time, it is desirable to use the same material 1'l as the ceramic material constituting the degreasing material for ceramic injection molding or a similar material.

In the present invention, tN￥ of degreasing material for ceramic injection molding
It is preferable that the binding has a thickness of 5011 to 2000μ, and 10
0 to 300 metres is preferable.

In addition, this degreasing material for ceramic injection molding with a particle size of 50μ to 2000μ has a particle size of 0
．． 1 μ~! It is necessary for the primary tb, F of 0011 to form a so-called aggregate structure in which the primary tb and F of 0011 are strongly bonded while retaining much of their original shape.

As a method for producing a degreasing material for ceramic injection molding having such an aggregate structure, first, primary particles made of ceramic with a particle size of 0.1 μm to 100 μm are prepared, and then an organic material is added to give them a predetermined shape. Mix with binder.

The organic binder is added to bind the ceramic powder to form a predetermined shape, and is generally composed of a thermoplastic resin, a lubricant, and a plasticizer.

As the thermoplastic resin, polypropylene, polyethylene, polystyrene, etc. can be used, as the lubricant, paraffin, wax, stearic acid, etc. can be used, and as the plasticizer, dioxyphenylene, diethylphenylene, etc. can be used.

For 1 part by weight of the organic binder, the ceramic primary particles are
Mix 1 part by weight or more. It is desirable to mix 4 to 5 parts by weight of ceramic primary particles to 1 part by weight of the organic binder.

Next, the mixture of the above-mentioned primary particles and organic binder was mixed with a particle size of 5.
A molded product with a particle size of 50 to 2000p is obtained by extrusion molding to a suitable diameter within the range of 0 to 2000μ, and then cutting to a length of 50 to 2000μ.

Next, this molded body is heated to remove the organic binder. At this time, heating is usually carried out to about 500°C.

Heating in the atmosphere is fine, but there is no leakage from the molded product.
It is desirable to carry out the process in an inert atmosphere so that the scattered organic components do not react with oxygen or the like.

Finally, the molded body is calcined at a temperature in the range of 800°C to 1400°C, preferably in the range of 1000°C to 1300°C. At this time, the calcination may be performed in the air, but preferably in an inert atmosphere.

[Function and effect of the invention]

According to the method for producing a degreasing material for ceramic injection molding according to the present invention, the following effects are achieved.

(a) According to the production method of the present invention, 800°C to 1400°C
Because it is calcined at ℃, the bonds between the primary particles become stronger, increasing the strength of the degreasing material and improving its heat resistance. Therefore, even if it is used for degreasing, it is unlikely to be damaged (it can be reused and is extremely economical).

(b) Since the organic binder and ceramic primary particles are mixed to form a predetermined shape, by changing the ratio of the organic binder and the primary particles, the packing density, particle size, and even porosity of the degreasing material can be adjusted. It can be easily controlled to a desired value. Therefore, the quality is more stable than before.

〔Example〕

Next, the practical side of the present invention will be explained with reference to the drawings.

FIG. 1 is a process diagram showing an embodiment of the method for producing a degreasing material for ceramic injection molding of the present invention.

First, 2 parts of an organic binder are added to primary particles 1, which are made by adding 10 parts of spinel to 90 parts of silicon nitride powder with an average particle size of 0.9 to 1.0 μm.
Prepare 20 parts of atactic polypropylene as shown in Fig. 1 (A)), mix this and use a pressure kneader 3 to make 1
30 parts Kneaded at 3°C for 30 minutes (Figure 1 (B))
. Thereafter, the kneaded material was put into the pelletizer 4, and pellets 5 with an average particle size Q of 3 inches were prepared (Fig. 1 (C)).
). This pellet 5 is charged into a degreasing furnace 6, and in nitrogen gas,
Under 1 atm, the temperature was raised from the greenhouse to 450°C at a heating rate of 10°C/hr to remove organic binder 2 (first
Figure (D)). After cooling, the pellet 5 was charged into a firing furnace 7 and calcined at 1200° C. for 4 hours in nitrogen gas at 1 atm (FIG. 1(E)). In this way, a pellet-shaped degreasing material was produced.

Next, in order to confirm the effect of this degreasing material, the degreasing material -F was used in the manufacture of pulleys. That is, the average particle size is 0.9
~1. To 100 parts of Op silicon nitride powder, 180 parts of polyethylene, 12 parts of ethyl vinyl alcohol, and 3 parts of dioxyphenylene as a plasticizer were put into a kneader set at 5°C, and stirred for about 40 minutes. It was taken out from the kneader and coarsely powdered using a pelletizer. Next, 140 parts of the coarse pellets were subjected to twin-screw extrusion at 2° C. to produce injection molding pellets I. Thereafter, a pulley was injection molded using an injection molding machine at an injection temperature of 180° C., a mold temperature of 50° C., an injection pressure of 900 ktr/ctn, and an injection rate of 4 QcC/sec.

Next, this injection molded body was placed in a degreasing furnace, and the above-mentioned degreasing material was filled around the injection molded body. Next, the inside of the degreasing furnace was heated and the temperature was raised from 50° C. to 500° C. at a rate of 4° C./hr in a nitrogen gas atmosphere of 1 atm to perform degreasing. After that, 1
Firing was performed at 1750° C. in a nitrogen gas atmosphere at atmospheric pressure.

The quality of the pulleys obtained as a result was 100% (
However, N = 100). The manufacture of such a pulley was repeated 10 times using the same degreasing material. Fig. 2 shows the firing rate (%) of non-defective products at this time, and Fig. 3 shows the change in particle size (dragon) of the degreasing material.

(Comparative example) As a degreasing material, silicon nitride powder with an average particle size of 1 μ (showing a particle size distribution in the range of 0.1 μ to 10 μ) was used as primary particles,
Pulleys were manufactured under exactly the same conditions as in the example except that particles of 11,100 μm to 400 μm were used using a spray dryer method.

The quality of the pulleys obtained as a result was 99% (N=100). This pulley was manufactured 10 times using the same degreasing material in the same manner as in the examples. The baked good product rate (%) at this time is shown in FIG. 2 as in the example, and the change in particle size of the degreasing material (II) is not shown in FIG. 3 either.

As is clear from Figures 2 and 3, when using the conventional degreasing material produced by the spray dryer method, the particle size of the degreasing material decreases significantly after one use, and some of it becomes dust. However, the degreasing material produced according to the present invention showed almost no change in particle size even after repeated use 10 times, and the yield rate of non-defective products decreased significantly from around the fourth time. I haven't.

This shows that the degreasing material produced according to the present invention has improved strength and heat resistance, and can withstand reuse.

In addition, the particle size could be controlled extremely easily and with high precision.

[Brief explanation of drawings]

Fig. 1 is a process diagram showing an example of the method for producing a degreasing material for ceramic injection molding of the present invention, Fig. 2 is a graph showing the firing rate of good products in an example of the present invention and a comparative example, and Fig. 3 is a graph showing the firing rate in the example of the present invention and a comparative example. 1 is a graph showing changes in particle size of degreasing materials in Examples and Comparative Examples. 1-...-Ceramic primary particles 2---Organic binder 3---1 Pressure seconder 4--11--Beletizer device 5-11-- Pellet 6 ---- Fat refining furnace 7...-1---Kilning furnace Applicant Toyo; D) (E)

Claims (1)

[Claims] (1) A method for producing a degreasing material for ceramic injection molding having an aggregate structure with a particle size of 50 μm to 2000 μm from primary particles made of ceramic with a particle size of 0.1 μm to 100 μm, which comprises the following steps. (a) A step of preparing primary particles made of ceramic having a particle size of 0.1 μm to 100 μm. (b) A step of mixing 1 part by weight or more of the missing particles with 1 part by weight of the organic binder to obtain a mixture. (c) A step of extruding this mixture to a suitable diameter within the range of 50 μm to 2000 μm (d) A step of cutting the extruded molded product into lengths of 50 μm to 2000 μm. (e) A step of heating the cut molded product to remove the organic binder. (f) Next, a step of calcining the degreasing material from which the organic binder has been removed in a range of 800°C to 1400°C.