Abstract:
The invention relates to a process for producing unmeltable polysilane-polycarbosilane copolymers which are soluble in inert solvents, comprising the steps of providing the product of a disproportionation of a methylchlorodisilane of the composition Si2MenCl6-n in which n = 1 to 4, or of a mixture thereof, wherein the disproportionation was effected with a Lewis base as a catalyst, wherein this product is a chlorinated crude polysilane/oligosilane containing hydrocarbon groups, and thermally postcrosslinking the crude polysilane/oligosilane to a polysilane-polycarbosilane copolymer, characterized in that the chlorine content of the polysilane-polycarbosilane copolymer is lowered by reacting the crude polysilane/oligosilane with a substitution agent by which chlorine bound therein is replaced by a chlorine-free substituent. Using this process, it is possible to produce green fibers and low-oxygen/oxygen-free ceramic fibers with a very low chlorine content.
Abstract:
Die Erfindung betrifft ein Verfahren zur Herstellung von unschmelzbaren, in indifferenten Lösemitteln löslichen Polysilan-Polycarbosilan-Copolymeren, umfassend die Schritte Bereitstellen des Produkts einer Disproportionierung eines oder eines Gemischs mehrerer Methylchlordisilane der Zusammensetzung Si 2 Me n Cl 6-n worin n = 1-4 ist, wobei die Disproportienierung mit einer Lewis-Base als Katalysator erfolgte, wobei dieses Produkt ein chlorhaltiges, Kohlenwasserstoffgruppen enthaltende Roh-Polysilan/Oligosilan ist, und thermisches Nachvernetzen des Roh-Polysilans/Oligosilans zu einem Polysilan-Polycarbosilan-Copolymer, dadurch gekennzeichnet, dass der Chlorgehalt des Polysilan- Polycarbosilan-Copolymer dadurch gesenkt wird, dass das Roh-Polysilans/Oligosilan mit einem Substitutionsmittel umgesetzt wird, durch welches darin gebundenes Chlor durch einen chlorfreien Substituenten ersetzt wird. Unter Einsatz dieses Verfahrens lassen sich Grünfasern und sauerstoffarme/-freie Keramikfasern mit einem sehr geringen Chlorgehalt herstellen.
Abstract:
The invention relates to a process for producing unmeltable polysilane-polycarbosilane copolymers which are soluble in inert solvents, comprising the steps of providing the product of a disproportionation of a methylchlorodisilane of the composition Si2MenCl6-n in which n = 1 to 4, or of a mixture thereof, wherein the disproportionation was effected with a Lewis base as a catalyst, wherein this product is a chlorinated crude polysilane/oligosilane containing hydrocarbon groups, and thermally postcrosslinking the crude polysilane/oligosilane to a polysilane-polycarbosilane copolymer, characterized in that the chlorine content of the polysilane-polycarbosilane copolymer is lowered by reacting the crude polysilane/oligosilane with a substitution agent by which chlorine bound therein is replaced by a chlorine-free substituent. Using this process, it is possible to produce green fibers and low-oxygen/oxygen-free ceramic fibers with a very low chlorine content.