Chlorine-containing silazane polymers, process for their preparation, ceramic material containing silicon nitride which can be prepared from them, and their preparation

US5100975A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Tilo Vaahs · Kelkheim, DE
• Marcellus Peuckert · Hofheim, DE
• Martin Bruck · Hofheim, DE

Key dates

• Filing date: Apr 17, 1991
• Grant date: Mar 31, 1992
• Expiry date: Apr 17, 2011

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G77/60
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

The invention relates to novel chlorine-containing silazane polymers, to their preparation, their further processing to ceramic material containing silicon nitride, and this material itself. In order to prepare the chlorine-containing silazane polymers, oligosilazanes of the formula (I) ##STR1## in which a >0, b.gtoreq.0 and n is about 2 to about 12, are reacted with at least one of the chlorosilanes Cl.sub.2 R.sup.4 Si--CH.sub.2 --CH.sub.2 --SiR.sup.4 Cl.sub.2, Cl.sub.3 Si--CH.sub.2 --CH.sub.2 --SiR.sup.5 Cl.sub.2, R.sup.6 SiCl.sub.3 or R.sup.7 SiHCl.sub.2 at 30.degree. C. to 300.degree. C., where, independently of one another, PA1 R.sup.1 and R.sup.2 =H, C.sub.1 -C.sub.6 -alkyl or C.sub.2 -C.sub.6 -alkenyl, PA1 R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 =C.sub.1 -C.sub.6 -alkyl or C.sub.2 -C.sub.6 -alkenyl and where if b=0 the reaction with R.sup.7 SiHCl.sub.2, if R.sup.7 =C.sub.1 -C.sub.6 -alkyl and none of the other chlorosilanes is present, is to be excluded. The chlorine-containing silazane polymers according to the invention can be converted by reaction with ammonia into polysilazanes, which in their turn can be pyrolysed to form ceramic materials containing silicon nitr…