Patent US3655412A successfully refreshed from Google Patents.
US3655412A
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Process for the production of dispersions of colloidal silver
Assignee: Fujifilm Holdings Corp
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Filing: 1968-11-15
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Granted: 1972-04-11
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Expires: 1988-11-15
Abstract
Abstract Dispersions of colloidal silver having a neutral black or slightly bluish-black color are disclosed. The process for forming the above described dispersions in gelatin comprises mixing an aqueous alkaline gelatin solution with an aqueous solution of a water-soluble silver salt and from 0.005 to 0.7 moles of a water-soluble manganous salt per mole of said silver salt, and then reducing the silver salt by adding thereto at least 0.2 moles per mole of said silver salt of an alkali metal sulphite and an excess of a water-soluble silver salt reducing agent.
Inventors
- 👤 Akira Kumai
- 👤 Yasuhisa Ogawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 22:55
CPC Classifications
G; G03; G03C; G03C1/00; G03C1/76; G03C1/825; G03C1/8255
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
30 words
The method as in claim 1 wherein the water soluble organic compound capable of reducing silver salt to silver colloid is hydroquinone, toluhydroquinone, catechol, monomethylaminophenol, 1-phEnyl-3-pyrazolidone, paraphenylenediamine or ascorbic acid.
Claim 2
Dependent Claim
15 words
The method as claimed in claim 1 wherein the alkali metal sulfite is sodium sulfite.
Claim 3
Dependent Claim
14 words
The method as claimed in claim 1 wherein the manganese salt is manganese nitrate.
Claim 4
Dependent Claim
33 words
The method as claimed in claim 1 wherein the gelatin is deashed to an extent that the reduction mixture does not contain more than 0.001 gram ion of any alkali earth metal ions.
Claim 5
Independent Claim
149 words
A method of preparing a black dispersion of silver in gelatin which comprises mixing an aqueous alkaline solution of gelatin with an aqueous solution of silver nitrate and a manganese salt selected from the group consisting of manganese nitrate and manganese acetate in a ratio of from 340 to 1360 grams of gelatin per mole of silver nitrate and from 0.005 to 0.7 mole of said manganese salt per mole of silver nitrate; and reducing the silver nitrate by adding to the resulting mixture at least 0.2 mole, per mole of silver nitrate, of an alkali metal sulfite and from 0.25 to 1.5 moles, per mole of silver nitrate, of a water-soluble reducing agent selected from the group consisting of hydroquinone, toluhydroquinone, catechol, monomethylaminophenol, 1-phenyl-3-pyrazolidone, paraphenylenediamine and ascorbic acid, at a temperature of from 40* to 65* C. and within a pH range of from about 7 to 10.
Claim 6
Dependent Claim
74 words
A supported stable silver dispersion in gelatin prepared by the method as claimed in claim 1 wherein when said dispersion is coated on a support so as to yield a layer containing from about 0.65 to about 0.75 grams of silver per square meter, said layer having a transmission optical density of at least 0.8 as measured with light having wave lengths of the group consisting of 650 nm., 550 nm. and 440 nm.
References Cited (Backward Citations)
US2921914A
Cited
US3459563A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-04-11 | 1975-10-11 | 1976-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-11 | 1979-10-11 | 1980-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-11 | 1983-10-11 | 1984-04-11 | $7700.00 | Window Closed / Lapsed |