Producing sintered articles from thermoplastic compositions containing polyoxymethylene binder

US5695697A · kind A · utility

Assignee

• BASF SE

Inventors

• Peter Trubenbach · Ludwigshafen, DE
• Graham E. McKee · Ludwigshafen, DE
• Hans Wohlfromm · Ludwigshafen, DE

Key dates

• Filing date: Nov 7, 1994
• Grant date: Dec 9, 1997
• Expiry date: Nov 7, 2014

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B22F2998/00
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

The process for the producing improved shaped sintered articles by first shaping a) a mixture of a ceramic or metallic powder or mixtures thereof with a moldable thermoplastic composition containing b) a thermoplastic polyoxymethylene binder and c) a second moldable and essentially inert thermoplastic polymer having a melting point between 90.degree. and 220.degree. C., such as a polyether of bisphenol A and an aliphatic diol. The binder is then removed from the shaped article by exposure to a gaseous acid-containing atmosphere, preferably below its softening temperature, while the second inert thermoplastic polymer is retained as a source of elemental carbon in which the ceramic or metallic powder is finely dispersed. This retained polymer is then pyrolyzed under an inert gas at elevated temperatures of at least 600.degree. C. for conversion to a finely dispersed elemental carbon. The resulting pyrolyzed preformed product is then sintered to obtain the desired high density ceramic and/or metallic article as the final product in which elemental carbon is uniformly and finely distributed. The process provides a simpler and more easily controlled method of incorporating elemental car…