US3954473A
Expired / Lapsed
US
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Method of bleaching metallic silver
Assignee: Polaroid Corp
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Filing: 1974-06-24
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Granted: 1976-05-04
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Expires: 1994-06-24
Abstract
Abstract This invention relates to a method of bleaching metallic silver by treating a preformed deposit of metallic silver with a silver complexing agent that forms a silver complex having a log stability constant of β 3 ≧ 10 18 in the presence of an electron acceptor. In a preferred embodiment, the silver complexing agent is an organic tertiary phosphine and the electron acceptor is an n or π type charge receptor having an electron affinity between 1 and 2 electron volts.
Inventors
- 👤 Ronald F. Lambert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:38
CPC Classifications
G; G03; G03C; G03C5/00; G03C5/26; G03C5/40; G03C5/44
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
90 words
A method of bleaching metallic silver present in a developed photosensitive silver halide element which comprises treating said metallic silver with an aliphatic tertiary organic phosphine in the presence of an electron acceptor selected from 3-nitrophthalic anhydride, 3-nitrophthalic acid, 2,5-dinitrobenzoic acid, 2,4-dinitrophenylacetic acid, 3-nitro-o-phthalic amide, mellitic acid, mellitic trianhydride, 2-hydroxyphenazine, benzoquinone, dichlorodicyano-p-benzoquinone, tetrachloro-p-benzoquinone, 2,6-dimethyl-p-benzoquinone, tetracyano-p-benzoquinone, pyrazine, p-phenylenediimine, 3,5-trifluoromethyl benzoic acid, and 3-carboxy-5-nitrobenzotrifluoride at a pH above 7, said phosphine and electron acceptor being used in equimolar proportions and in substantially excess proportions relative to the quantity of said metallic silver.
Claim 2
Independent Claim
90 words
A method of bleaching metallic silver present in a developed photosensitive silver halide element which comprises treating said metallic silver with an aliphatic tertiary organic phosphine in the presence of an electron acceptor selected from 3-nitrophthalic anhydride, 3-nitrophthalic acid, 2,5-dinitrobenzoic acid, 2,4-dinitrophenylacetic acid, 3-nitro-o-phthalic amide, mellitic acid, mellitic trianhydride, 2-hydroxyphenazine, benzoquinone, dichlorodicyano-p-benzoquinone, tetrachloro-p-benzoquinone, 2,6-dimethyl-p-benzoquinone, tetracyano-p-benzoquinone, pyrazine, p-phenylenediimine, 3,5-trifluoromethyl benzoic acid, and 3-carboxy-5-nitrobenzotrifluoride at a pH above 7, said phosphine and electron acceptor being used in equimolar proportions and in substantially excess proportions relative to the quantity of said metallic silver.
Claim 3
Dependent Claim
12 words
A method as defined in claim 1 wherein said phosphine is 3-aminopropyldimethylphosphine.
Claim 4
Dependent Claim
12 words
A method as defined in claim 1 wherein said phosphine is 5-aminopentyldimethylphosphine.
Claim 5
Dependent Claim
12 words
A method as defined in claim 1 wherein said phosphine is bis(2-carboxyethyl)methylphosphine.
Claim 6
Dependent Claim
13 words
A method as defined in claim 1 wherein said electron acceptor is 2-hydroxyphenazine.
Claim 7
Dependent Claim
14 words
A method as defined in claim 1 wherein said electron acceptor is 3-nitrophthalic anhydride.
Claim 8
Dependent Claim
14 words
A method as defined in claim 1 wherein said electron acceptor is 3,5-trifluoromethylbenzoic acid.
Claim 9
Dependent Claim
13 words
A method as defined in claim 1 wherein said electron acceptor is p-benzoquinone.
Claim 10
Dependent Claim
15 words
A method as defined in claim 1 wherein said phosphine is dissolved in aqueous solution.
Claim 11
Dependent Claim
19 words
A method as defined in claim 9 wherein said electron acceptor is dissolved in said solution of said phosphine.
Claim 12
Dependent Claim
22 words
A method as defined in claim 1 wherein said developed silver halide element includes an imagewise distribution of a photographic image dye.
Claim 13
Dependent Claim
22 words
A method as defined in claim 1 wherein said silver halide element includes a layer of silver for filtering light during exposure.
Claim 14
Independent Claim
84 words
A method of bleaching metallic silver which comprises treating a deposit of metallic silver with an aliphatic tertiary organic phosphine in the presence of an electron acceptor selected from 3-nitrophthalic anhydride, 3-nitrophthalic acid, 2,5-dinitrobenzoic acid, 2,4-dinitrophenylacetic acid 3-nitro-o-phthalic amide, mellitic acid, mellitic trianhydride, 2-hydroxyphenazine benzoquinone, dichlorodicyano-p-benzoquinone, tetrachloro-p-benzoquinone, 2,6-dimethyl-p-benzoquinone, tetracyano-p-benzoquinone, pyrazine, p-phenylenediimine, 3,5-trifluoromethyl benzoic acid, and 3-carboxy-5-nitrobenzotrifluoride at a pH above 7, said phosphine and electron acceptor being used in equimolar proportions and in substantially excess proportions relative to the quantity of said metallic silver.
Claim 15
Independent Claim
84 words
A method of bleaching metallic silver which comprises treating a deposit of metallic silver with an aliphatic tertiary organic phosphine in the presence of an electron acceptor selected from 3-nitrophthalic anhydride, 3-nitrophthalic acid, 2,5-dinitrobenzoic acid, 2,4-dinitrophenylacetic acid 3-nitro-o-phthalic amide, mellitic acid, mellitic trianhydride, 2-hydroxyphenazine benzoquinone, dichlorodicyano-p-benzoquinone, tetrachloro-p-benzoquinone, 2,6-dimethyl-p-benzoquinone, tetracyano-p-benzoquinone, pyrazine, p-phenylenediimine, 3,5-trifluoromethyl benzoic acid, and 3-carboxy-5-nitrobenzotrifluoride at a pH above 7, said phosphine and electron acceptor being used in equimolar proportions and in substantially excess proportions relative to the quantity of said metallic silver.
Claim 16
Independent Claim
65 words
A method of bleaching metallic silver which comprises treating a deposit of metallic silver with an aliphatic tertiary organic phosphine in the presence of atmospheric oxygen at a pH above 7, said phosphine being used in substantially excess proportions relative to the quantity of said metallic silver and said treated deposit being maintained in the presence of atmospheric oxygen at least until bleaching is effected.
Claim 17
Independent Claim
65 words
A method of bleaching metallic silver which comprises treating a deposit of metallic silver with an aliphatic tertiary organic phosphine in the presence of atmospheric oxygen at a pH above 7, said phosphine being used in substantially excess proportions relative to the quantity of said metallic silver and said treated deposit being maintained in the presence of atmospheric oxygen at least until bleaching is effected.
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) | 1979-05-04 | 1979-11-03 | 1980-05-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-04 | 1983-11-03 | 1984-05-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-04 | 1987-11-03 | 1988-05-04 | $7700.00 | Window Closed / Lapsed |