Process for the preparation of poly(disilyl)silazane polymers and the polymers therefrom
AssigneeDow Corning Corporation
InventorJohn H. Gaul, Jr.
Life of this patent
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Abstract
What is disclosed is a process for preparing R'.sub.3 SiNH-containing silazane polymers by contacting and reacting chlorine-containing disilanes with {R'.sub.3 Si}.sub.2 NH where R' is vinyl, hydrogen, an alkyl radical of 1-3 carbon atoms or the phenyl group. The silazane polymers are useful as chemical intermediates to produce silicon-containing chemical compounds. They are also useful in the formation of silicon carbide-containing ceramic materials.
Claims89
A process for preparing an R'.sub.3 SiNH--containing silazane polymer which consists of contacting and reacting in an inert, essentially anhydrous, atmosphere, a chlorine-containing disilane or a mixture of chlorine-containing disilanes, of the general formula
- (Cl.sub.a R.sub.b Si).sub.2
- with a disilazane having the general formula
- (R'.sub.3 Si).sub.2 NH
- at a temperature in the range of 25.degree. C. to 300.degree. C. while distilling by-produced volatile products, wherein
- R is vinyl, an alkyl group of 1-3 carbon atoms or the phenyl group;
- R' is vinyl, hydrogen, an alkyl group of 1-3 carbon atoms or the phenyl group;
- a has a value of 0.5-3;
- b has a value of 0-2.5 and the sum of a+b is equal to three.
A composition of matter which is an R'.sub.3 SiNH--containing silazane polymer which is prepared by contacting and reacting in an inert, essentially anhydrous, atmosphere a chlorine-containing disilane or a mixture of chlorine-containing disilanes, of the general formula
- (Cl.sub.a R.sub.b Si).sub.2
- with a disilazane having the general formula
- (R'.sub.3 Si).sub.2 NH
- at a temperature in the range of 25.degree. C. to 300.degree. C. while distilling by-produced volatile products, wherein
- R is vinyl, an alkyl group of 1-3 carbon atoms or the phenyl group;
- R' is vinyl, hydrogen, an alkyl group of 1-3 carbon atoms or the phenyl group;
- a has a value of 0.5-3;
- b has a value of 0-2.5 and the sum of a+b is equal to three.
A method for preparing a silicon carbide ceramic material which consists of heating an R'.sub.3 SiNH-- containing silazane polymer in an inert atmosphere or in a vacuum to at least a temperature of 750.degree. C. until the silazane polymer is converted to silicon carbide ceramic material, which silazane polymer is obtained by a process which consists of contacting and reacting in an inert, essentially anhydrous, atmosphere, a chlorine-containing disilazne or a mixture of chlorine-containing disilanes, wherein the number of diorgano-substituted silicon atoms does not exceed the number of monoorgano-substituted silicon atoms, of the general formula
- (Cl.sub.a R.sub.b Si).sub.2
- with a disilazane having the general formula
- (R'.sub.3 Si).sub.2 NH
- at a temperature in the range of 125.degree. C. to 300.degree. C. while distilling by-produced volatile products, wherein
- R is vinyl, an alkyl group of 1-3 carbon atoms or the phenyl group;
- R' is vinyl, hydrogen, an alkyl group of 1-3 carbon atoms or the phenyl group;
- a has a value of 0.5-3;
- b has a value of 0-2.5 and the sum of a+b is equal to three.
A method for preparing a silicon carbide containing ceramic article which consists of
- (A) forming an article of the desired shape from an R'.sub.3 SiNH-- containing silazane polymer;
- (B) heating the article formed in (A) in an inert atmosphere or in a vacuum to an elevated temperature of at least 750.degree. C. until the silazane polymer is converted to silicon carbide containing ceramic, which silazane polymer is obtained by a process which consists of contacting and reacting in an inert, essentially anhydrous, atmosphere, a chlorine-containing disilane or a mixture of chlorine-containing disilanes, wherein the number of diorgano-substituted silicon atoms does not exceed the number of monoorgano-substituted silicon atoms, of the general formula
- (Cl.sub.a R.sub.b Si).sub.2
- with a disilazane having the general formula
- (R'.sub.3 Si).sub.2 NH
- at a temperature in the range of 125.degree. C. to 300.degree. C. while distilling by-produced volatile products, wherein
- R is vinyl, an alkyl group of 1-3 carbon atoms or the phenyl group;
- R' is vinyl, hydrogen, an alkyl group of 1-3 carbon atoms or the phenyl group;
- a has a value of 0.5-3;
- b has a value of 0-2.5 and the sum of a+b is equal to three.
A method for preparing an article coated with ceramic which consists of
- (A) coating a substrate with an R'.sub.3 SiNH-- containing silazane polymer,
- (B) heating the coated substrate in an inert atmosphere or in a vacuum to an elevated temperature of at least 750.degree. C. until the coating is converted to a silicon carbide ceramic material, whereby a silicon carbide-containing ceramic coated article is obtained, which silazane polymer is obtained by a process which consists of contacting and reacting in an inert, essentially anhydrous, atmosphere, a chlorine-containing disilane or a mixture of chlorine-containing disilanes, wherein the number of diorgano-substituted silicon atoms does not exceed the number of monoorgano-substituted silicon atoms, of the general formula
- (Cl.sub.a R.sub.b Si).sub.2
- with a disilazane having the general formula
- (R.sub.3 Si).sub.2 NH
- at a temperature in the range of 125.degree. C. to 300.degree. C. while distilling by-produced volatile products, wherein
- R is vinyl, an alkyl group of 1-3 carbon atoms or the phenyl group;
- R' is vinyl, hydrogen, an alkyl group of 1-3 carbon atoms or the phenyl group;
- a has a value of 0.5-3;
- b has a value of 0-2.5 and the sum of a+b is equal to three.
A process for preparing an R'.sub.3 SiNH-- containing silazane polymer which consists of contacting and reacting in an inert, essentially anhydrous atmosphere, a disilazane having the general formula
- (R'.sub.3 Si).sub.2 NH
- with
- (i) a mixture of a chlorine-containing disilane having the general formula
- (Cl.sub.a R.sub.b Si).sub.2
- and a chlorine-containing monosilane having the general formula
- R'.sub.n SiCl.sub.4-n ;
- (ii) a mixture of chlorine-containing disilanes lhaving the general formula
- (Cl.sub.a R.sub.b Si).sub.2
- mixed with a chlorine-containing monosilane having the general formula
- R'.sub.n SiCl.sub.4-n
- or
- (iii) a mixture of chlorine-containing disilanes having the general formula
- (Cl.sub.a R.sub.b Si).sub.2
- mixed with a mixture of chlorine-containing monosilanes having the general formula
- R'.sub.n SiCl.sub.4-n
- at a temperature in the range of 25.degree. C. to 300.degree. C. while distilling by-produced volatile products, wherein
- R is vinyl, an alkyl radical of 1-3 carbon atoms or the phenyl group;
- R' is vinyl, hydrogen, an alkyl group of 1-3 carbon atoms or the phenyl group;
- a has a value of 0.5-3;
- b has a value of 0-2.5;
- n has a value of 0, 1, 2 or 3 and the sum of a+b is equal to three.
Dependencies are inferred from the claim text.