Kabushiki Kaisha Komatsu Seisakusho

Hiroshi Ono

Takemori Takayama

Yoshitaka Ohyama

Masato Miyake

Katsuyoshi Saito

Kazuo Okamura

A water solvent extraction degreasing method capable of reducing degreasing time without consideration of abrupt decomposition/vaporization and swelling caused by heat. An organic binder is removed from a molded product that is produced by a powder material mixed with the organic binder and this organic binder contains at least one water-soluble organic compound and at least one water-insoluble thermoplastic resin. The degreasing step of this method includes a water solvent extraction step for extracting the water-soluble organic compound from the organic binder contained in the molded product, using water as a solvent.

Water solvent extraction degreasing method and molded products produced

A low-cost thermal decomposition degreasing method capable of drastically reducing the time required for a degreasing process which involves heating, vaporization and thermal decomposition, while assuring the shape retention property of an injection molded product during degreasing. The degreasing process comprises: (i) a first step wherein a molded product placed under a reduced pressure less than or equal to atmospheric pressure is heated at a temperature lower than the melting point of a thermoplastic binder so that the thermoplastic binder partially evaporates by 5 wt % or more, and then the molded product is further heated at a temperature lower than higher one of the melting points of a more volatile organic compound and a thermoplastic resin whereby the thermoplastic binder further evaporates by 10 wt % or more, and wherein the final temperature is set to 200.degree. C. or less; and (ii) a second step wherein the molded product is heated to a temperature higher than or equal to the highest one of the melting points of thermoplastic binder components at a pressure higher than or equal to atmospheric pressure in an atmosphere of gas inert relative to a powder material constituting the molded product.

Thermal decomposition degreasing method and molded products thereof

By the use of a binder comprising (a) 40 to 70 wt % of a water-soluble amide material and/or water-soluble amine material and (b) 25 to 60 wt % of a polyamide resin component substantially composed of a polyamide resin material having 10 carbon atoms or more on average between amido groups, a molded article is produced by metal powder injection molding. From such a molded article, the water-soluble amide material and/or water-soluble amine material is eluted by a water-based solvent and then, the polyamide resin component is removed by heating.

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Saitama, Japan

Hiroshi Ono