JPH0257611A - Thermoplastic molding material - Google Patents

Abstract

PURPOSE:To obtain the thermoplastic molding material having the good shape holdability of a degreased product by using the metal of a specific volume percentage obtd. by compounding secondary fine particles of a specific grain size at a specific ratio with spheroidal primary powder of a specific grain size as the compd. of the resin. CONSTITUTION:The secondary fine particles adjusted to <=10mum average grain size are compounded at <=20vol.% with the spheroidal primary powder adjusted in average grain size to <=75mum. The above-mentioned secondary fine particles are packed into the spacings among the primary powder particles in this way, by which the volume percentage of the entire metal powder is adjusted to 50-70%. The thermoplastic molding material is obtd. by compounding this metal with the resin. The above-mentioned material has good flowability at the time of injection molding. The shape holdability of the product at the time of degreasing is improved by using the metal powder having the high packing ratio. The high-density sintered material which shrinks less and has good dimensional accuracy is obtd. by sintering this degreased product.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) In general powder sintering, metal powder and resin such as wax polyethylene, polystyrene, E\'A, acrylic, etc. are heated and kneaded. A gold a-based composite material is injection molded or compression molded into a predetermined shape, degreased, and then sintered. By increasing the volume content of metal powder while ensuring flowability during molding, Kitamei can improve shape retention during degreasing and reduce shrinkage during sintering. 1. Concerning thermoplastic molding materials (Prior art) Conventionally, compounds used for injection molding are usually made of metal powders such as carbonyl Fe, Ni, Co, etc. with an average particle size of about 5 μm and a culm of 55% by volume. For degreasing after molding, the heating rate may be slow (1 to 11 b/l), or the shape of the part may be maintained by embedding it in ceramic powder or using a jig. Ensures sex.

(Problems to be Solved by the Invention) In the conventional technology described above, since the degreasing process is complicated, poor productivity has been a major factor in increasing costs. In addition, if it is embedded in ceramic powder and degreased, a step is required to remove the ceramic lath powder before starting the next sintering process, and depending on the shape of the molded product, it may not be possible to completely remove it. It was difficult. Therefore, there were problems in terms of quality, such as increased variation in density and shape after sintering due to residual ceramic/lath powder.

(Means for Solving the Problems) The present invention provides r! ! This was done to solve the problem, and in the (1) tg = tt term, for spherical primary powder whose average particle size is adjusted to 75 pm or less, the average particle size is 1 (bm or less). tA-conditioned secondary particles are blended in an amount of 20% or less, and the volume percentage of the total metal powder is 50-70%? By using the material, in the Ji Ji term of (2), the 1 of the above (1)
This can be achieved by using a thermoplastic molding material made of a compound of titanium fat and a metal containing three non-metals such as SiC and C for the purpose of alloying the desired thermoplastic molding material after sintering. be able to.

(for 1 yen) FIG. 3 shows the relationship between particles in the present invention.

In the third step, the gap 1 is placed in the gap 1a between the large primary metal powder particles 1 whose average particle size is adjusted to 75 pm or less.
By filling the secondary metal powder particles 2 smaller than a, the deformation resistance during degreasing is enhanced.

In addition, since the secondary metal powder particles 2 are filled in the gaps 1a between the large primary metal powder particles 1, the filling rate of metal in the compound can be increased.

In the present invention, the average particle size of the primary metal powder particles l is 75+
+m or less is considered to be the maximum particle size that can achieve high density during sintering, and the average particle size of the secondary metal powder particles 2 is set to be lo+m or less because the primary metal The value was determined to be smaller than the gap diameter of 1u1 of powder particles and within a range that does not significantly inhibit IQ tL during injection molding. In addition, the reason why the 12 large/l powder is made into a spherical shape is to ensure the flowability of the compound during molding such as injection molding.

(Real'MVH) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Primary iron powder 1 has a large powder particle size, while 2 has a small powder particle size.
Mixture V and powder containing 15% by weight of iron powder 2 were prepared. The primary iron powder was obtained by air-classifying water atomizer (Kobe i4 Atmel U+OO) to an average particle size of 25a.
Secondary 'it' using powder classified into m, the average particle size of the powder is 3p
TA carbonyl iron powder was blended with 10% by weight of 4 metals. M-part system binder: 1 Chukyo Yushi injection molding binder E
Fig. 1 shows the results of examining the mixing torque at 140°C using 914 at 140°C using a Laboplasto mill with varying ratios of metal powder and light oil. It was found that it is possible to increase the filling rate of metal powder by about 10% by volume or more compared to the conventional method, while maintaining the flowability during molding at 11i. -You can see it from the inside-) to maintain the color retention of the product.

The degreasing time was painfully shortened. In addition, since it is important to ensure the flowability of the compound in injection molding, it is necessary to use particles with a large particle size that are close to spherical. In this example, water atomized iron powder was classified to a specified particle size. Although I used oil atomized general metallurgical metal powder, it is fine. Of course, it is also possible to select iron powder that is more nearly spherical from iron powder produced by other methods, or to use iron powder that has been subjected to a bispheroidal treatment.

(Effects of the Invention) As detailed above, when using the thermoplastic molding material of the present invention, by increasing the filling rate of metal powder to 60% or more, the cedar retention of the product during degreasing can be significantly improved. The process from degreasing to sintering can be continuous.
Productivity will be significantly improved7

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the amount of metal powder added and kneading torque, Figure 2 is a diagram showing the relationship between degreasing time and temperature, and Figure 3 is a diagram showing the relationship between particles in the present invention. . Primary iron powder. la... Gap. ...Secondary iron powder

Claims (2)

[Claims] (1) For spherical primary powder whose average particle size is adjusted to 75 μm or less, 2 particles whose average particle size is adjusted to 10 μm or less
A thermoplastic molding material comprising a metal and resin compound in which the following fine particles are blended in an amount of 20% by volume or less and the volume fraction of the total metal powder is adjusted to 50 to 70%. (2) In item (1), a thermoplastic molded material consisting of a compound of metal and resin to which non-metals such as SiC and C are mixed and added for the purpose of alloying after sintering.