US4332887A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for preparing photosensitive silver halide emulsions
Assignee: Polaroid Corp
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Filing: 1980-10-06
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Granted: 1982-06-01
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Expires: 2000-10-06
Abstract
Abstract Narrow grain size distribution silver halide emulsions are prepared by: 1. Forming photosensitive silver halide grains in the presence of a water-soluble thiocyanate compound with a halide/silver molar ratio ranging from not more than about 5% molar excess of halide to not more than about a 25% molar excess of silver; and 2. Growing said grains in the presence of said water-soluble thiocyanate compound for a time sufficient to grow said grains to a predetermined grain size distribution.
Inventors
- 👤 Arthur M. Gerber
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:55
CPC Classifications
G; G03; G03C; G03C1/00; G03C1/005; G03C1/015; G03C1/035; G03C2001/0357
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
134 words
The method for forming a photosensitive silver halide emulsion which comprises the steps of forming photosensitive silver halide grains in the presence of a water-soluble thiocyanate compound with a halide/silver molar ratio ranging from not more than about a 5% molar excess of halide to not more than about a 25% molar excess of silver; ripening said grains subsequent to the forming of said grains in the presence of said water-soluble thiocyanate compound wherein said water-soluble thiocyanate compound is employed at a level of about 0.015 to 1.5 moles per mole of silver, and substantially in the absence of any other ripening agent, for a time sufficient to grow said grains to a predetermined grain size distribution; removing said water-soluble thiocyanate compound subsequent to grain growth and removing any silver thiocyanate formed during precipitation.
Claim 2
Independent Claim
134 words
The method for forming a photosensitive silver halide emulsion which comprises the steps of forming photosensitive silver halide grains in the presence of a water-soluble thiocyanate compound with a halide/silver molar ratio ranging from not more than about a 5% molar excess of halide to not more than about a 25% molar excess of silver; ripening said grains subsequent to the forming of said grains in the presence of said water-soluble thiocyanate compound wherein said water-soluble thiocyanate compound is employed at a level of about 0.015 to 1.5 moles per mole of silver, and substantially in the absence of any other ripening agent, for a time sufficient to grow said grains to a predetermined grain size distribution; removing said water-soluble thiocyanate compound subsequent to grain growth and removing any silver thiocyanate formed during precipitation.
Claim 3
Dependent Claim
29 words
The method as defined in claim 1 wherein lithium bromide is added to said emulsion at the end of said ripening to dissolve any silver thiocyanate formed during precipitation.
Claim 4
Dependent Claim
16 words
The method of claim 1 wherein said precipitation takes place in a molar excess of silver.
Claim 5
Dependent Claim
18 words
The method of claim 3 wherein said silver excess is a 1 to 10% molar excess of silver.
Claim 6
Dependent Claim
15 words
The method of claim 3 wherein about a 5% molar excess of silver is employed.
Claim 7
Dependent Claim
24 words
The method of claim 1 wherein said water soluble thiocyanate compound is employed at a level of about 0.2 mole per mole of silver.
Claim 8
Dependent Claim
114 words
A photosensitive silver halide emulsion prepared by the method which comprises the steps of forming photosensitive silver halide grains in the presence of a water-soluble thiocyanate compound with a halide/silver molar ratio ranging from not more than about a 5% molar excess of halide to not more than about a 25% molar excess of silver; ripening said grains subsequent to the forming of said grains in the presence of said water-soluble thiocyanate compound, and substantially in the absence of any other ripening agent, for a time sufficient to grow said grains to a predetermined grain size distribution; removing said water-soluble thiocyanate compound subsequent to grain growth and dissolving any silver thiocyanate formed during precipitation.
Claim 9
Dependent Claim
114 words
A photosensitive silver halide emulsion prepared by the method which comprises the steps of forming photosensitive silver halide grains in the presence of a water-soluble thiocyanate compound with a halide/silver molar ratio ranging from not more than about a 5% molar excess of halide to not more than about a 25% molar excess of silver; ripening said grains subsequent to the forming of said grains in the presence of said water-soluble thiocyanate compound, and substantially in the absence of any other ripening agent, for a time sufficient to grow said grains to a predetermined grain size distribution; removing said water-soluble thiocyanate compound subsequent to grain growth and dissolving any silver thiocyanate formed during precipitation.
Claim 10
Dependent Claim
29 words
The emulsion of claim 7 wherein the silver halide grains range from about 0.6 to 1.5 μm with a geometric standard deviation of ranging from about 1.4 to 2.0.
Claim 11
Dependent Claim
21 words
The emulsion of claim 8 wherein said grain size is about 1.0 μm and said geometric standard deviation is about 1.7.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-05-31 | 1985-11-30 | 1986-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-31 | 1989-11-30 | 1990-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-31 | 1993-11-30 | 1994-06-01 | $7700.00 | Window Closed / Lapsed |