Patent US3887447A successfully refreshed from Google Patents.
US3887447A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of electrograining aluminium
Assignee: Alcan Research and Development Ltd
•
Filing: 1973-09-27
•
Granted: 1975-06-03
•
Expires: 1993-09-27
Abstract
Abstract In a process for electrograining aluminium by subjecting the aluminium to alternating current whilst immersed in an aqueous electrolyte containing 2 - 20 gms/litre hydrochloric acid the electrolyte is stabilised against the presence of sulphate ion contamination and the pit size is controlled to a value below about 10 microns by the addition to the electrolyte of defined quantities of phosphoric acid or chromic acid. Both for operational reasons and for avoidance of health hazards it is preferred to employ phosphoric acid in an amount of about 5 - 10 gms/litre.
Inventors
- 👤 Peter Geoffrey Sheasby
- 👤 Alan Martin Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:51
CPC Classifications
B; B41; B41N; B41N3/00; B41N3/08; B41N3/03; B41N3/034; C; C25; C25F; C25F3/00; C25F3/02; C25F3/04
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
67 words
IN THE PROCESS OF ELECTROGRAINING ALUMINUM FOR THE PRODUCTION OF LITHOGRAPHIC PRINTING PLATES WHICH COMPRISES SUBJECTING THE ALUMINUM TO ALTERNATING CURRENT WHILE IMMERSED IN AN AQUEOUS ELECTROLYTE CONTAINING 2-20 GMS/LITER HYDROCHLORIC ACID THE IMPROVEMENT WHICH COMPRISES THE ADDITION TO THE ELECTROLYTE OF 1.5 - 15 GMS/LITER PHOSPHORIC ACID WHEREBY TO MAINTAIN THE PIT SIZE BELOW ABOUT MICRONS IN THE PRESENCE OF CONTAMINANT SULPHATE ION IN THE ELECTROLYTE.
Claim 2
Dependent Claim
67 words
IN THE PROCESS OF ELECTROGRAINING ALUMINUM FOR THE PRODUCTION OF LITHOGRAPHIC PRINTING PLATES WHICH COMPRISES SUBJECTING THE ALUMINUM TO ALTERNATING CURRENT WHILE IMMERSED IN AN AQUEOUS ELECTROLYTE CONTAINING 2-20 GMS/LITER HYDROCHLORIC ACID THE IMPROVEMENT WHICH COMPRISES THE ADDITION TO THE ELECTROLYTE OF 1.5 - 15 GMS/LITER PHOSPHORIC ACID WHEREBY TO MAINTAIN THE PIT SIZE BELOW ABOUT MICRONS IN THE PRESENCE OF CONTAMINANT SULPHATE ION IN THE ELECTROLYTE.
Claim 3
Dependent Claim
70 words
In the process of electrograining aluminum for the production of lithographic printing plates which comprises subjecting the aluminum to alternating current while immersed in an aqueous electrolyte containing 2 - 20 gms/liter hydrochloric acid the improvement which comprises the addition to the electrolyte of 1.5 - 15 gms/liter phosphoric acid whereby to maintain the pit size below about 10 microns in the presence of contaminant sulphate ion in the electrolyte.
Claim 4
Dependent Claim
70 words
In the process of electrograining aluminum for the production of lithographic printing plates which comprises subjecting the aluminum to alternating current while immersed in an aqueous electrolyte containing 2 - 20 gms/liter hydrochloric acid the improvement which comprises the addition to the electrolyte of 1.5 - 15 gms/liter phosphoric acid whereby to maintain the pit size below about 10 microns in the presence of contaminant sulphate ion in the electrolyte.
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) | 1978-06-02 | 1978-12-02 | 1979-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-02 | 1982-12-02 | 1983-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-02 | 1986-12-02 | 1987-06-03 | $7700.00 | Window Closed / Lapsed |