Novel photosensitive elements and method of stabilizing said elements
AssigneePolaroid Corporation
InventorsT. Nelson Baker, III, Bernard Zuckerman
Life of this patent
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Abstract
Photosensitive silver halide emulsions for use in diffusion transfer processes are stabilized without adversely affecting spectral sensitization by the following steps: (a) spectrally sensitizing the silver halide grains; (b) lowering the pH of the emulsion from a first pH of the emulsion subsequent to chemical ripening to a pH of about 5.5 to 4.0 and/or increasing the Br ion/Ag ratio to at least 5 mg Br ion/gAg and, subsequent to steps (a) and (b), (c) adding 5-80 mg/gAg to said emulsion of a stabilizer selected from the group consisting of an hydroxy triazaindene, an amino triazaindene, an hydroxy tetrazaindene, an amino tetrazaindene, an hydroxy pentazaindene and an amino pentazaindene.
Claims34
A method for stabilizing a photosensitive silver halide emulsion for use in a photographic duffusion transfer process which comprises the following steps:
- (a) spectrally sensitizing the silver halide grains with at least a first spectral sensitizing dye;
- (b) lowering the pH of the sensitized emulsion from a first pH of the emulsion subsequent to chemical ripening in excess of about 6 to a second pH of about 5.5 to about 4.0 and/or increasing the Br ion/Ag ratio to at least 5 mg Br/gAg;
- and, subsequent to steps (a) and (b),
- (c) adding to said emulsion about 5 to 80 mg/gAg of a stabilizer selected from the group consisting of an hydroxy triazaindene, an amino triazaindene, an hydroxy tetrazaindene, an amino tetrazaindene, an hydroxy pentazaindene and an amino pentazaindene.
A photosensitive element comprising a support carrying at least one stabilized silver halide emulsion layer spectrally sensitized with at least a first spectral sensitizing dye, said emulsion having a pH of about 5.5 to 4.0 and/or a Br ion/Ag ratio of at least 5 mg Br ion/g AG wherein said emulsion layer has been stabilized by:
- (a) lowering the pH of said emulsion from a first pH of the emulsion subsequent to chemical ripening in excess of about 6 to a second pH of about 5.5 to 4.0 and/or increasing the Br ion/Ag ratio to at least 5 mg Br ion/g Ag and subsequent to step (a),
- (b) adding 5-80 mg/gAg to said emulsion of a stabilizer selected from the group consisting of an hydroxy triazaindene, an amino triazaindene, an hydroxy tetrazaindene, an amino tetrazaindene, an hydroxy pentazaindene and an amino pentazaindene.
A photographic film unit which comprises, in combination:
- a photosensitive element having a diffusion transfer image-receiving element affixed at least one edge thereof, said photosensitive element comprising a support carrying:
- (a) a red-sensitive silver halide emulsion spectrally sensitized with at least one spectral sensitizing dye and having associated therewith a cyan dye developer;
- (b) a green-sensitive silver halide emulsion spectrally sensitized with at least one spectral sensitizing dye and having associated therewith a magenta dye developer;
- (c) a blue-sensitive silver halide emulsion spectrally sensitized with at least one spectral sensitizing dye and having associated therewith a yellow dye developer;
- wherein at least one of said silver halide emulsions has been stabilized by:
- (a) lowering the pH of said emulsion from a first pH of said emulsion subsequent to chemical ripening in excess of about 6 to a second pH of about 5.5 to 4.0 and/or increasing the Br ion/Ag ratio to at least 5 mg Br/gAg;
- and
- (b) adding 5-80 mg/gAg to said emulsion of a stabilizer selected from the group consisting of an hydroxy triazaindene, an amino triazaindene, an hydroxy tetrazaindene, an amino tetrazaindene, an hydroxy pentazaindene and an amino pentazaindene, wherein said photosensitive element and said image-receiving layers are adapted to be superposed, the support layers of each comprising the extremities of the superposed structure.
A photosensitive silver halide emulsion spectrally sensitized with at least a first spectral sensitizing dye, wherein said emulsion is stabilized by:
- (a) lowering the pH of said emulsion from a first pH of the emulsion subsequent to chemical ripening in excess of about 6 to a second pH of about 5.5 to 4.0 and/or increasing the Br ion/Ag ratio to at least 5 mg Br ion/gAg;
- and subsequent to step (a),
- (b) adding 5-80 mg/gAg to said emulsion of a stabilizer selected from the group consisting of an hydroxy triazaindene, an amino triazaindene, an hydroxy tetrazaindene, an amino tetrazaindene, an hydroxy pentazaindene and an amino pentazaindene.
Dependencies are inferred from the claim text.