US4204869A
Expired / Lapsed
US
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Method for forming noble metal silver precipitating nuclei
Assignee: Polaroid Corp
•
Filing: 1978-04-04
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Granted: 1980-05-27
•
Expires: 1998-04-04
Abstract
Abstract Silver-precipitating nuclei are prepared by partially oxidizing a stannous salt reducing agent and then reducing a noble metal salt or complex with said reducing agent.
Inventors
- 👤 Charles H. Byers
- 👤 Robert W. Hausslein
- 👤 Mara O. Nestle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:48
CPC Classifications
G; G03; G03C; G03C8/00; G03C8/24; G03C8/26; G03C8/28
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
64 words
A method for forming noble metal silver-precipitating nuclei which comprises the steps of (a) forming an aqueous solution of a stannous salt; (b) contacting said solution with an oxidizing agent to partially oxidize said stannous ion to provide a ratio of Sn +4 to Sn +2 of about 2.5 to 10 to 5.5 to 10; and (c) adding a noble metal salt or complex.
Claim 2
Independent Claim
64 words
A method for forming noble metal silver-precipitating nuclei which comprises the steps of (a) forming an aqueous solution of a stannous salt; (b) contacting said solution with an oxidizing agent to partially oxidize said stannous ion to provide a ratio of Sn +4 to Sn +2 of about 2.5 to 10 to 5.5 to 10; and (c) adding a noble metal salt or complex.
Claim 3
Dependent Claim
12 words
The method of claim 1 wherein said aqueous solution includes a polymer.
Claim 4
Dependent Claim
10 words
The method of claim 2 wherein said polymer is gelatin.
Claim 5
Dependent Claim
15 words
The method of claim 3 wherein a second polymer is added subsequent to nuclei formation.
Claim 6
Dependent Claim
12 words
The method of claim 4 wherein said second polymer is hydroxyethyl cellulose.
Claim 7
Dependent Claim
12 words
The method of claim 4 wherein said second polymer is polyvinyl alcohol.
Claim 8
Dependent Claim
12 words
The method of claim 1 wherein said aqueous solution includes acetic acid.
Claim 9
Dependent Claim
16 words
The method of claim 1 which includes the step of coating said nuclei on a support.
Claim 10
Dependent Claim
12 words
The method of claim 1 wherein said stannous salt is stannous chloride.
Claim 11
Dependent Claim
11 words
The method of claim 1 wherein said noble metal is palladium.
Claim 12
Dependent Claim
11 words
The method of claim 1 wherein said oxidizing agent is oxygen.
Claim 13
Dependent Claim
11 words
The method of claim 1 wherein said oxidizing agent is air.
Claim 14
Dependent Claim
12 words
The method of claim 1 wherein said oxidizing agent is hydrogen peroxide.
Claim 15
Dependent Claim
25 words
The method of claim 1 wherein said steps are carried out under a blanket of nitrogen except for the step of oxidizing said stannous ion.
Claim 16
Dependent Claim
21 words
The method of claim 1 wherein said aqueous solution is nitrogen sparged prior to contacting said solution with an oxidizing agent.
Claim 17
Dependent Claim
17 words
The method of claim 1 wherein said ratio is 3 Sn +4 to 10 Sn +2 .
Claim 18
Independent Claim
63 words
A method for forming noble metal silver-precipitating element which comprises the steps of (a) forming an aqueous solution of acetic acid and gelatin; (b) adding to said solution stannous chloride; (c) sparging said solution with oxygen to provide a ratio of 3:10 Sn +4 :Sn +2 ; (d) adding palladous chloride to said solution; and (e) coating the thus-formed nuclei on a support.
Claim 19
Independent Claim
63 words
A method for forming noble metal silver-precipitating element which comprises the steps of (a) forming an aqueous solution of acetic acid and gelatin; (b) adding to said solution stannous chloride; (c) sparging said solution with oxygen to provide a ratio of 3:10 Sn +4 :Sn +2 ; (d) adding palladous chloride to said solution; and (e) coating the thus-formed nuclei on a support.
Claim 20
Independent Claim
49 words
A method for forming noble metal silver-precipitating nuclei which comprises the steps of (a) forming an aqueous solution of a stannous salt; (b) contacting said solution with an oxidizing agent to partially oxidize said stannous ion; and (c) adding a noble metal salt or complex under a nitrogen blanket.
Claim 21
Independent Claim
49 words
A method for forming noble metal silver-precipitating nuclei which comprises the steps of (a) forming an aqueous solution of a stannous salt; (b) contacting said solution with an oxidizing agent to partially oxidize said stannous ion; and (c) adding a noble metal salt or complex under a nitrogen blanket.
References Cited (Backward Citations)
US2543181A
Cited
US2726154A
Cited
US2861885A
Cited
US2944894A
Cited
US3536488A
Cited
US3647440A
Cited
US3615426A
Cited
US3615428A
Cited
US3615427A
Cited
US3615429A
Cited
US3894871A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-05-27 | 1983-11-26 | 1984-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-05-27 | 1987-11-26 | 1988-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-05-27 | 1991-11-26 | 1992-05-27 | $7700.00 | Window Closed / Lapsed |