Patent US4401473A successfully refreshed from Google Patents.
US4401473A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Use of dimethylphosphinylalkanephosphonic acid as a setting retarder in gypsum
Assignee: Hoechst AG
•
Filing: 1982-02-23
•
Granted: 1983-08-30
•
Expires: 2002-02-23
Abstract
Abstract The invention relates to dimethylphosphinylalkanephosphonic acids of the general formula I, in which n is 1 or 2, which are used as setting retarders for gypsum. ##STR1##
Inventors
- 👤 Hans-Jerg Kleiner
- 👤 Volker Knittel
- 👤 Gerhard Debus
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:12
CPC Classifications
C; C04; C04B; C04B24/00; C04B24/003; C07; C07F; C07F9/00; C07F9/02; C07F9/28; C07F9/50; C07F9/53; C07F9/5304; C07F9/5308; C07F9/5312
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
22 words
Gypsum containing, as a setting retarder, a dimethylphosphinylalkanephosphonic acid of the general formula I ##STR13## in which n is 1 or 2.
Claim 2
Dependent Claim
22 words
Gypsum containing, as a setting retarder, a dimethylphosphinylalkanephosphonic acid of the general formula I ##STR13## in which n is 1 or 2.
References Cited (Backward Citations)
US3646133A
Cited
US3925456A
Cited
US3941772A
Cited
US3960888A
Cited
US4260422A
Cited
US4225361A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-08-29 | 1987-02-28 | 1987-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-29 | 1991-02-28 | 1991-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-29 | 1995-02-28 | 1995-08-30 | $7700.00 | Window Closed / Lapsed |