US3959090A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Continuous electrolyte coloring of a pre-anodised aluminum foil or strip
Assignee: Rio Tinto Switzerland AG
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Filing: 1975-07-28
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Granted: 1976-05-25
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Expires: 1995-07-28
Abstract
Abstract Continuous process for anodizing and subsequent electrolytic coloring of an aluminium strip or foil with A.C. in which the strip after leaving the anodistaion unit passes through an aqueous acidic contacting electrolyte, e.g. dilute sulfuric acid, and then through the aqueous acidic coloring electrolyte containing metal ions and in which the A.C. source is connected to inert electrodes dipping in the contacting and in the coloring electrolyte respectively.
Inventors
- 👤 Gunter Hollrigl
- 👤 Ladislav Sandera
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:19
CPC Classifications
C; C25; C25D; C25D11/00; C25D11/02; C25D11/04; C25D11/18; C25D11/20; C25D11/22
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
138 words
A continuous process for anodic oxidation of an aluminum strip or foil to form an oxide layer and subsequent electrolytic coloring of the oxide layer by means of alternating current, said process comprising the steps of: subsequent to the anodic oxidation, passing said aluminum through an aqueous contacting electrolyte; thereafter, passing said aluminum through an aqueous coloring electrolyte comprising metal ions, said contact and coloring electrolytes being separated from each other; disposing a first inert electrode in said contacting electrolyte; disposing at least a second inert electrode in said coloring electrolyte; and applying an alternating current to said first and second electrodes to precipitate said metal ions without any direct physical contact with said aluminum, the potential difference between said first electrode and said aluminum being less than the potential difference between said aluminum and said second electrode.
Claim 2
Dependent Claim
138 words
A continuous process for anodic oxidation of an aluminum strip or foil to form an oxide layer and subsequent electrolytic coloring of the oxide layer by means of alternating current, said process comprising the steps of: subsequent to the anodic oxidation, passing said aluminum through an aqueous contacting electrolyte; thereafter, passing said aluminum through an aqueous coloring electrolyte comprising metal ions, said contact and coloring electrolytes being separated from each other; disposing a first inert electrode in said contacting electrolyte; disposing at least a second inert electrode in said coloring electrolyte; and applying an alternating current to said first and second electrodes to precipitate said metal ions without any direct physical contact with said aluminum, the potential difference between said first electrode and said aluminum being less than the potential difference between said aluminum and said second electrode.
Claim 3
Dependent Claim
36 words
The process as claimed in claim 1, wherein the potential difference between said first electrode and said aluminum is less than about 10 per cent of the total potential difference between said first and second electrodes.
Claim 4
Dependent Claim
28 words
The process as claimed in claim 2, wherein said contact electrolyte is an acid which permits further oxidation to occur in the anodic phase of the alternating current.
Claim 5
Dependent Claim
26 words
The process as claimed in claim 3, wherein said contact electrolyte includes dilute sulphuric acid having a concentration of from about 5 to about 300 g/l.
Claim 6
Dependent Claim
23 words
The process as claimed in claim 4, wherein a concentration of the dilute sulphuric acid is from about 10 to about 30 g/l.
Claim 7
Dependent Claim
25 words
The process as claimed in claim 2, wherein said contact electrolyte is a strong acid of the kind used for the anodic oxidation of aluminum.
Claim 8
Dependent Claim
31 words
The process as claimed in claim 1, further comprising the step of adjusting the duration of said aluminum in said coloring electrolyte, whereby a predetermined coloring of said aluminum is obtained.
Claim 9
Dependent Claim
61 words
The process as claimed in claim 7, wherein the duration of contact of said aluminum in said coloring electrolyte is ensured by adjusting the length of the path of said aluminum in said electrolyte in accordance with the transfer velocity of said aluminum and changing the relative position of said electrodes accordingly, whereby a predetermined coloring of said aluminum is obtained.
Claim 10
Dependent Claim
16 words
The process as claimed in claim 1, wherein said first and second electrodes are graphite electrodes.
Claim 11
Dependent Claim
30 words
The process as claimed in claim 1, wherein said coloring electrolyte is strongly acidic and said metal ions are selected from the group consisting of copper, tin, silver and thallium.
Claim 12
Dependent Claim
32 words
The process as claimed in claim 10, wherein the metal salts are of thallium and said coloring electrolyte has a concentration of from about 2 to about 10 g/l of thallium sulphate.
Claim 13
Dependent Claim
30 words
The process as claimed in claim 1, wherein said coloring electrolyte is weakly acidic and said metal ions are selected from the group consisting of nickel, cobalt, cadmium and iron.
Claim 14
Dependent Claim
28 words
The process as claimed in claim 10, further comprising the step of changing the relative position of said electrodes, whereby a predetermined coloring of said aluminum is obtained.
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) | 1979-05-25 | 1979-11-24 | 1980-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-25 | 1983-11-24 | 1984-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-25 | 1987-11-24 | 1988-05-25 | $7700.00 | Window Closed / Lapsed |