US4124406A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Setting retarder
Assignee: Evonik Operations GmbH
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Filing: 1976-09-14
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Granted: 1978-11-07
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Expires: 1996-09-14
Abstract
Abstract Gypsum plaster having a delayed setting time is made by adding a mixture of mesotartaric acid and l-tartaric acid or d,l-tartaric acid or a mixture of l-tartaric acid and d,l-tartaric acid to the gypsum plaster.
Inventors
- 👤 Helmut Knorre
- 👤 Manfred Langer
- 👤 Wolfgang Fischer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:49
CPC Classifications
C; C04; C04B; C04B24/00; C04B24/04; C04B24/06
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
104 words
Gypsum plaster having a mixture of tartaric acids therein to delay the setting time of the plaster, said tartaric acids consisting of a mixture of meso-tartaric acid with ( 1) l-tartaric acid, (2) d,l-tartaric acid or (3) both of l-tartaric acid and d,l-tartaric acid, said mixture of tartaric acids containing 5 to 80% of meso-tartaric acid by weight, said plaster containing 0.01 to 0.5% by weight of said mixture of tartaric acids, and when said mixture of tartaric acids is (2) or (3) the plaster has sufficient calcium hydroxide that a 5% aqueous paste of the plaster has a pH of at least 11.5.
Claim 2
Dependent Claim
104 words
Gypsum plaster having a mixture of tartaric acids therein to delay the setting time of the plaster, said tartaric acids consisting of a mixture of meso-tartaric acid with ( 1) l-tartaric acid, (2) d,l-tartaric acid or (3) both of l-tartaric acid and d,l-tartaric acid, said mixture of tartaric acids containing 5 to 80% of meso-tartaric acid by weight, said plaster containing 0.01 to 0.5% by weight of said mixture of tartaric acids, and when said mixture of tartaric acids is (2) or (3) the plaster has sufficient calcium hydroxide that a 5% aqueous paste of the plaster has a pH of at least 11.5.
Claim 3
Dependent Claim
19 words
Gypsum plaster according to claim 1 wherein said mixture of tartaric acids contains 20 to 60% of meso-tartatic acid.
Claim 4
Dependent Claim
19 words
Gypsum plaster according to claim 1 wherein the plaster contains 0.015 to 0.2% of said mixture of tartaric acids.
Claim 5
Dependent Claim
34 words
Gypsum plaster according to claim 3 wherein the plaster has sufficient calcium hydroxide that a 5% aqueous paste of the plaster has a pH of 12 up to the pH of saturated calcium hydroxide.
Claim 6
Dependent Claim
34 words
Gypsum plaster according to claim 1 wherein the plaster has sufficient calcium hydroxide that a 5% aqueous paste of the plaster has a pH of 12 up to the pH of saturated calcium hydroxide.
Claim 7
Dependent Claim
28 words
Gypsum plaster according to claim 1 wherein the plaster has sufficient calcium hydroxide that a 5% aqueous paste of the plaster has a pH of at least 11.5.
Claim 8
Dependent Claim
32 words
Gypsum plaster according to claim 6 wherein the mixture of tartaric acids consists of a mixture of meso-tartaric acid with either (1) d,l-tartaric acid or (2) both l-tartaric acid and d,l-tartaric acid.
Claim 9
Dependent Claim
22 words
Gypsum plaster according to claim 1 wherein the mixture of tartaric acids consists of a mixture of meso-tartaric acid and l-tartaric acid.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-11-06 | 1982-05-08 | 1982-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-11-06 | 1986-05-08 | 1986-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-11-06 | 1990-05-08 | 1990-11-07 | $7700.00 | Window Closed / Lapsed |