Patent US4839461A successfully refreshed from Google Patents.
US4839461A
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Polyaspartic acid from maleic acid and ammonia
Assignee: Bayer AG
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Filing: 1987-08-03
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Granted: 1989-06-13
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Expires: 2007-08-03
Abstract
Abstract Polyaspartic acid and its salts, which can be obtained by reacting maleic acid and ammonia in a molar ratio of 1:1-1.5 at 120°-150° C. and , if appropriate, converting the acid into salts, are used for removing and preventing incrustations formed by the hardness constituents of water, or as a fertilizer.
Inventors
- 👤 Gunther Boehmke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:16
CPC Classifications
C; C08; C08G; C08G69/00; C02; C02F; C02F5/00; C02F5/08; C02F5/10; C02F5/12; C08G69/02; C08G69/08; C08G73/00; C08G73/06; C08G73/10; C08G73/1092; C11; C11D; C11D3/00; C11D3/16; C11D3/37; C11D3/3703; C11D3/3719
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
45 words
A process for the preparation of a salt of polyaspartic acid comprising reacting maleic acid and ammonia in a molar ratio of 1:1-1.5 at 120°-140° C., and converting the resultant acid into a salt by adding a metal hydroxide or ammonium hydroxide to the acid.
Claim 2
Dependent Claim
45 words
A process for the preparation of a salt of polyaspartic acid comprising reacting maleic acid and ammonia in a molar ratio of 1:1-1.5 at 120°-140° C., and converting the resultant acid into a salt by adding a metal hydroxide or ammonium hydroxide to the acid.
Claim 3
Dependent Claim
65 words
A process for the preparation of a salt of polyaspartic acid according to claim 1, wherein maleic acid and ammonia are heated to a temperature of 125°-135° C. in the course of 4-6 hours and are maintained at this temperature for up to 2 hours, and, after cooling to 100°-120° C., an aqueous solution or suspension of a metal hydroxide or ammonium hydroxide is added.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-06-12 | 1992-12-12 | 1993-06-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-12 | 1996-12-12 | 1997-06-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-12 | 2000-12-12 | 2001-06-13 | $7700.00 | Window Closed / Lapsed |