US4722886A
Expired / Lapsed
US
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Process for preparing a photographic emulsion containing tabular grains having narrow size distribution
Assignee: Agfa Gevaert NV
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Filing: 1986-10-10
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Granted: 1988-02-02
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Expires: 2006-10-10
Abstract
Abstract Process for preparing a photographic emulsion containing tabular silver halide grains which have narrow size distribution comprising: A. adding silver nitrate to a vessel containing dispersing medium/bromide mixture, initial bromide ion concentration is 0.08 to 0.25 N to form tabular seed grains; B. adding a basic silver halide solvent, e.g., ammonia, ammoniacal solution, etc. to achieve 0.02 N to 0.2 N of the solvent (e.g., after at least 2% by weight of total silver nitrate has been added); C. stopping silver nitrate addition for 0.5 to 60 minutes, e.g., bromide ion concentration is in the range of 0.005 to 0.05 N; D. neutralizing at least some of the basic silver halide solvent present; and E. adding additional silver nitrate and halide, i.e., Br- and BrI-, by balanced double jet procedure. The emulsions are used in photographic elements for x-ray, graphic arts, etc.
Inventors
- 👤 Robert W. Nottorf
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 22:40
CPC Classifications
G; G03; G03C; G03C1/00; G03C1/005; G03C1/0051; G03C1/015; G03C2001/0156; G03C1/035; G03C2001/03511; G03C2001/0357; G03C5/00; G03C5/16; G03C2005/168; G03C2200/00; G03C2200/43; Y; Y10; Y10S; Y10S430/00; Y10S430/167
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
163 words
A process for the preparation of a photographic emulsion containing tabular silver halide grains having a narrow size distribution comprising A. adding silver nitrate to a vessel containing a dispersing medium/bromide mixture wherein the initial bromide ion concentration is 0.08 to 0.25 normal whereby tabular seed grains are formed; B. adding a basic silver halide solvent solution to achieve 0.02 to 0.2 normal of the solvent after at least 2% by weight of the total silver nitrate has been added to said vessel; C. stopping silver nitrate addition for a time period of 0.5 to 60 minutes to permit the tabular seed grains to ripen wherein the bromide ion concentration is in the range of 0.005 to 0.05 normal; D. neutralizing at least some of the solvent that is present; and E. adding silver nitrate and halide taken from the group consisting of Br - and BrI - by balanced double jet addition whereby the tabular grains of narrow size distribution are formed.
Claim 2
Dependent Claim
163 words
A process for the preparation of a photographic emulsion containing tabular silver halide grains having a narrow size distribution comprising A. adding silver nitrate to a vessel containing a dispersing medium/bromide mixture wherein the initial bromide ion concentration is 0.08 to 0.25 normal whereby tabular seed grains are formed; B. adding a basic silver halide solvent solution to achieve 0.02 to 0.2 normal of the solvent after at least 2% by weight of the total silver nitrate has been added to said vessel; C. stopping silver nitrate addition for a time period of 0.5 to 60 minutes to permit the tabular seed grains to ripen wherein the bromide ion concentration is in the range of 0.005 to 0.05 normal; D. neutralizing at least some of the solvent that is present; and E. adding silver nitrate and halide taken from the group consisting of Br - and BrI - by balanced double jet addition whereby the tabular grains of narrow size distribution are formed.
Claim 3
Dependent Claim
16 words
A process according to claim 1 wherein substantially all the solvent is neutralized in Step D.
Claim 4
Dependent Claim
16 words
A process according to claim 1 wherein the basic silver halide solvent is an ammoniacal solution.
Claim 5
Dependent Claim
12 words
A process according to claim 3 wherein the ammoniacal solution is ammonia.
Claim 6
Dependent Claim
19 words
A process according to claim 1 wherein 2 to 30% of the silver nitrate is added in Step A.
Claim 7
Dependent Claim
19 words
A process according to claim 1 wherein 7 to 15% of the silver nitrate is added in Step A.
Claim 8
Dependent Claim
27 words
A process according to claim 1 wherein after Step E a thiocyanate salt ripening agent is added and the emulsion is ripened for 1 to 20 minutes.
Claim 9
Dependent Claim
14 words
A process according to claim 1 wherein the emulsion is chemically and spectrally sensitized.
Claim 10
Dependent Claim
165 words
A process for the preparation of a photographic emulsion containing tabular silver halide grains having a narrow size distribution comprising A. adding silver nitrate to a vessel containing a gelatino/bromide mixture wherein the initial bromide ion concentration is 0.1 to 0.2 normal whereby tabular seed grains are formed; B. adding an ammoniacal base solution to achieve 0.025 to 0.1 normal of the base after at least 2% of the total silver nitrate has been added to said vessel; C. stopping silver nitrate addition for a time period of 1 to 5 minutes to permit the tabular seed grains to ripen wherein the bromide ion concentration is in the range of 0.01 to 0.04 normal; D. neutralizing at least some of the base present with acid to a pH of 5.8 to 9.0; and E. adding silver nitrate and halide taken from the group consisting of Br - and BrI - by balanced double jet addition whereby the tabular grains of narrow size distribution are formed.
Claim 11
Dependent Claim
165 words
A process for the preparation of a photographic emulsion containing tabular silver halide grains having a narrow size distribution comprising A. adding silver nitrate to a vessel containing a gelatino/bromide mixture wherein the initial bromide ion concentration is 0.1 to 0.2 normal whereby tabular seed grains are formed; B. adding an ammoniacal base solution to achieve 0.025 to 0.1 normal of the base after at least 2% of the total silver nitrate has been added to said vessel; C. stopping silver nitrate addition for a time period of 1 to 5 minutes to permit the tabular seed grains to ripen wherein the bromide ion concentration is in the range of 0.01 to 0.04 normal; D. neutralizing at least some of the base present with acid to a pH of 5.8 to 9.0; and E. adding silver nitrate and halide taken from the group consisting of Br - and BrI - by balanced double jet addition whereby the tabular grains of narrow size distribution are formed.
Claim 12
Dependent Claim
24 words
A process according to claim 9 wherein substantially all the ammoniacal base solution is neutralized in Step D, the pH being 5.8 to 7.5.
Claim 13
Dependent Claim
27 words
A process according to claim 9 wherein after Step E a thiocyanate salt ripening agent is added and the emulsion is ripened for 1 to 20 minutes.
Claim 14
Dependent Claim
14 words
A process according to claim 9 wherein the emulsion is chemically and spectrally sensitized.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-02-01 | 1991-08-03 | 1992-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-01 | 1995-08-03 | 1996-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-01 | 1999-08-03 | 2000-02-02 | $7700.00 | Window Closed / Lapsed |