Patent US3837928A successfully refreshed from Google Patents.
US3837928A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Conversion coating on metal
Assignee: Dulux Australia Ltd
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Filing: 1972-09-12
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Granted: 1974-09-24
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Expires: 1992-09-12
Abstract
Abstract The quality of a crystalline zinc phosphate conversion coating deposited on a ferrous or zinciferous surface from an aqueous, acidic, non-gassing phosphating solution is improved by the addition thereto of a polymeric additive which is an addition copolymer of an unsaturated carboxylic acid and a selected ethylenic monomer.
Inventors
- 👤 A Morrison
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 14:38
CPC Classifications
C; C23; C23C; C23C22/00; C23C22/05; C23C22/06; C23C22/07; C23C22/08; C23C22/12
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
25 words
An improved process according to claim 1 wherein the concentration of dissolved polymeric additive in the phosphating liquid is 0.25 - 0.5 gm per litre.
Claim 2
Dependent Claim
19 words
An improved process according to claim 1 in which monomer (a) is selected from maleic anhydride and maleic acid.
References Cited (Backward Citations)
US3728163A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |