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US3650859A
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Regeneration of chromic acid etching solutions
Assignee: MacDermid Inc
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Filing: 1969-09-12
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Granted: 1972-03-21
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Expires: 1989-09-12
Abstract
Abstract A spent chromic acid etching solution, which has been used, for example, to etch plastic substrates, is regenerated by adding, with mixing, an alkali metal permanganate, such as potassium permanganate, and separating the resulting sludge which forms. During the regeneration process trivalent chromium in the etchant is oxidized to hexavalent chromium. The regenerated etching solution, thus recovered, is utilized as an etchant per se or it may be reconstituted with added sulfuric acid and/or chromic acid as required.
Inventors
- 👤 Eugene D D Ottavio
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:35
CPC Classifications
C; C23; C23C; C23C18/00; C23C18/16; C23C18/1601; C23C18/1617; Y; Y10; Y10T; Y10T428/00; Y10T428/31
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
26 words
The process of claim 1 wherein the said concentration of the regenerated etching soLution is adjusted by adding additional quantities of sulfuric acid and chromium trioxide.
Claim 2
Dependent Claim
22 words
The process of claim 1 wherein the said regenerated solution is recovered by decantation after the sludge has been allowed to settle.
Claim 3
Dependent Claim
14 words
The process of claim 1 wherein the said alkali metal permanganate is potassium permanganate.
Claim 4
Dependent Claim
12 words
The process of claim 1 wherein the said plastic substrate is polypropylene.
Claim 5
Dependent Claim
12 words
The process of claim 1 wherein the said plastic substrate is ABS.
References Cited (Backward Citations)
US2890944A
Cited
US3317330A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-03-21 | 1975-09-20 | 1976-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-21 | 1979-09-20 | 1980-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-21 | 1983-09-20 | 1984-03-21 | $7700.00 | Window Closed / Lapsed |