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US4487749A
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Dicalcium phosphate dihydrate having improved monofluorophosphate compatibility and process for the preparation thereof
Assignee: Syensqo USA LLC
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Filing: 1983-07-08
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Granted: 1984-12-11
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Expires: 2003-07-08
Abstract
Abstract Dicalcium phosphate dihydrate compositions having improved monofluorophosphate compatibility are prepared by reacting a lime slurry with phosphoric acid to form a monocalcium phosphate solution, and then further reacting the monocalcium phosphate solution with additional lime slurry to a pH in the range of from above about 2.2 to below about 5.5.
Inventors
- 👤 Fawzy G. Sherif
- 👤 Helmut W. Majewski
- 👤 Francis A. Via
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:16
CPC Classifications
C; C01; C01B; C01B25/00; C01B25/16; C01B25/26; C01B25/32; C01B25/322; A; A61; A61K; A61K8/00; A61K8/18; A61K8/19; A61K8/24; A61Q; A61Q11/00
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
74 words
A process for preparing dicalcium phosphate dihydrate having improved monofluorophosphate compatibility which consists essentially of the steps of: (a) reacting a slaked lime slurry with phosphoric acid to form a monocalcium phosphate solution; (b) further reacting said monocalcium phosphate solution with additional slaked lime slurry to form a dicalcium phosphate dihydrate slurry having a final pH ranging from above about 2.2 to below about 5.5; (c) separating the dicalcium phosphate dihydrate from said slurry.
Claim 2
Dependent Claim
74 words
A process for preparing dicalcium phosphate dihydrate having improved monofluorophosphate compatibility which consists essentially of the steps of: (a) reacting a slaked lime slurry with phosphoric acid to form a monocalcium phosphate solution; (b) further reacting said monocalcium phosphate solution with additional slaked lime slurry to form a dicalcium phosphate dihydrate slurry having a final pH ranging from above about 2.2 to below about 5.5; (c) separating the dicalcium phosphate dihydrate from said slurry.
Claim 3
Dependent Claim
19 words
The process of claim 1 wherein an acid other than pyrophosphoric acid is added during or after step (b).
Claim 4
Dependent Claim
33 words
The process of claim 2 wherein said acid is an acid selected from the group consisting of orthophosphoric acid, polymeta phosphoric acid, tri and tetrameta phosphoric acids, sulfuric acid, triphosphoric and tetraphosphoric acids.
Claim 5
Dependent Claim
16 words
The process of claim 1 wherein said pH ranges from above about 3.0 to about 3.5.
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) | 1987-12-11 | 1988-06-11 | 1988-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-11 | 1992-06-11 | 1992-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-11 | 1996-06-11 | 1996-12-11 | $7700.00 | Window Closed / Lapsed |