Patent US4946920A successfully refreshed from Google Patents.
US4946920A
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Polysilazanes, processes for their preparation, ceramic materials which contain silicon nitride and can be prepared from them, and preparation thereof
Assignee: Hoechst AG
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Filing: 1988-12-02
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Granted: 1990-08-07
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Expires: 2008-12-02
Abstract
Abstract The invention relates to novel polysilazanes, their preparation, their further processing to ceramic material containing silicon nitride and this material itself. To prepare the polysilazanes, Si,Si'-diorganyl-N-alkyl-tetrachloro-disilazanes of the formula RSiCl 2 -NR'-SiCl 2 R are reacted with ammonia. The polysilazanes can then be pyrolyzed to ceramic material containing silicon nitride. The polysilazanes according to the invention dissolve in the customary aprotic solvents.
Inventors
- 👤 Tilo Vaahs
- 👤 Hans-Jerg Kleiner
- 👤 Marcellus Peuckert
- 👤 Martin Bruck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 16:42
CPC Classifications
C; C08; C08G; C08G77/00; C08G77/42; C08G77/60; C08G77/62; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/589
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
73 words
A process for the preparation of a polymeric silazane, which comprises reacting a compound of the formula RSiCl 2 -NR'-SiCl 2 R, in which R is C 1 -C 4 -alkyl, vinyl or phenyl and R' is C 1 -C 4 -alkyl, with at least 6.7 moles of ammonia per mole of said compound of the formula RSiCl 2 -NR'-SiCl 2 R in a solvent at temperatures from -80° C. to +70° C.
Claim 2
Dependent Claim
73 words
A process for the preparation of a polymeric silazane, which comprises reacting a compound of the formula RSiCl 2 -NR'-SiCl 2 R, in which R is C 1 -C 4 -alkyl, vinyl or phenyl and R' is C 1 -C 4 -alkyl, with at least 6.7 moles of ammonia per mole of said compound of the formula RSiCl 2 -NR'-SiCl 2 R in a solvent at temperatures from -80° C. to +70° C.
Claim 3
Dependent Claim
19 words
The process as claimed in claim 1, wherein R is methyl, ethyl, vinyl or phenyl and R' is methyl.
Claim 4
Dependent Claim
15 words
The process as claimed in claim 1, wherein R is ethyl and R' is methyl.
Claim 5
Dependent Claim
20 words
The process as claimed in claim 1, wherein at least 7 moles of ammonia are used per mole of chlorodisilazane.
Claim 6
Dependent Claim
80 words
A polymeric silazane of the formula ##STR9## in which R, R* and R** can be identical or different and R, R*, R** and R*** are C 1 -C 4 -alkyl, vinyl or phenyl, R' is C 1 -C 4 -alkyl and x and y denote the molar fractions of the two structural units, x+y being 1 and x being 0.7-0.95 and wherein each (NH) 1/2 denotes a single NH group linked to the Si atom and a second Si atom.
Claim 7
Dependent Claim
80 words
A polymeric silazane of the formula ##STR9## in which R, R* and R** can be identical or different and R, R*, R** and R*** are C 1 -C 4 -alkyl, vinyl or phenyl, R' is C 1 -C 4 -alkyl and x and y denote the molar fractions of the two structural units, x+y being 1 and x being 0.7-0.95 and wherein each (NH) 1/2 denotes a single NH group linked to the Si atom and a second Si atom.
Claim 8
Dependent Claim
28 words
A polymeric silazane as claimed in claim 5, wherein, independently of one another, R, R*, R** and R*** are methyl, ethyl, vinyl or phenyl and R' is methyl.
Claim 9
Dependent Claim
20 words
A polymeric silazane as claimed in claim 5, wherein R, R*, R** and R*** are ethyl and R' is methyl.
Claim 10
Dependent Claim
12 words
A polymeric silazane as claimed in claim 5 wherein x is 0.85-0.95.
Claim 11
Dependent Claim
12 words
A polymeric silazane, obtainable by the process as claimed in claim 1.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-06 | 1994-02-05 | 1994-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-06 | 1998-02-05 | 1998-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-06 | 2002-02-05 | 2002-08-07 | $7700.00 | Window Closed / Lapsed |