Silver halide emulsion and silver halide photographic light...

Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing

Reexamination Certificate

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Reexamination Certificate

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06235460

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to silver halide emulsions and silver halide photographic light sensitive materials and in particular to silver halide emulsions superior in sensitivity, graininess, pressure resistance and image sharpness and to silver halide photographic light sensitive materials by use thereof.
BACKGROUND OF THE INVENTION
To achieve improvements in basic photographic characteristics such as photographic speed, graininess and pressure resistance of silver halide emulsions and silver halide photographic light sensitive materials, there have been made attempts to provide silver halide grains characterized in halide composition, specifically, iodide distribution within the grain.
U.S. Pat. No. 4,668,614 discloses a technique of double structure grains comprising a high iodide core and a low iodide shell, thereby enhancing sensitivity and graininess. U.S. Pat. No. 4,614,711 discloses a technique of triple structure grains comprising a low iodide core, a high iodide intermediate shell and a low iodide shell, whereby sensitivity, graininess and pressure resistance are enhanced. European Patent 202784B discloses a technique of quadruple structure grains, in which between a high iodide inner shell and a low iodide outer shell, an intermediate shell having an intermediate iodide content is further provided between the iodide contents of inner and outer shells, thereby enhancing the sensitivity/fog ratio and graininess. JP-A 7-244345 (herein the term, JP-A refers to an unexamined and published Japanese Patent Application) discloses a technique of silver halide grains comprising an internal core containing 1 mol % or less iodide, a first covering layer containing 2 to 20 mol % iodide, a second covering layer containing 3 mol % or less iodide and a high iodide phase formed during and after formation of the second covering layer, thereby enhancing pressure resistance, sensitivity, latent image stability and incubation resistance. JP-A 8-314040 and 9-197593 and U.S. Pat. No. 5,728,515 also disclose similar techniques. However, still further enhanced sensitivity, graininess and pressure resistance are desired. Furthermore, these techniques produced problems such as deteriorated sharpness, so that a technique for solving such problems is desired.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to enhance sensitivity, graininess and pressure resistance as well as sharpness, thereby providing silver halide emulsions superior in such characteristics and silver halide photographic light sensitive materials by use thereof.
The object of the invention can be accomplished by the following constitution:
(1) A silver halide emulsion comprising silver halide grains and a dispersing medium, wherein each of the silver halide grains comprises a first high-iodide phase and a second high-iodide phase, said first and second high-iodide phases each accounting for 0.5 to 5% of the grain, based silver, and said first and second high-iodide phases each having an iodide content of more than 40 mol %;
(2) The silver halide emulsion described in (1), wherein the grain further comprises an intermediate phase located between the first high-iodide phase and the second high-iodide phase, said intermediate phase having an average iodide content of 0 to 10 mol %;
(3) The silver halide emulsion of (2), wherein the intermediate phase has an iodide content of 0 to 10 mol %;
(4) The silver halide emulsion of (3), wherein at least one of the first and second high-iodide phases accounts for 1 to 4% of the grain in terms of silver amount;
(5) The silver halide emulsion of (3), wherein the intermediate phase accounts for 15 to 50% of the grain, based on silver;
(6) The silver halide emulsion of (3), wherein the grain further comprises an internal phase located inside the first and second high-iodide phases, the internal phase accounting for 5 to 60% of the grain, based on silver, and having an average iodide content of 0 to 10 mol %;
(7) The silver halide emulsion of (6), wherein the internal phase has an iodide content of 0 to 10 mol %;
(8) The silver halide emulsion of (7), wherein the grain further comprises a shell phase located outside the first and second high-iodide phases, the shell phase occupying 10 to 50% of the grain, based on silver;
(9) A silver halide emulsion comprising silver halide grains and a dispersing medium, wherein each of the silver halide grains comprises, from inside to outside of the grain, an internal phase accounting for 5 to 60% of the grain, based on silver, and having an average iodide content of 0 to 10 mol %, a first high-iodide phase occupying 0.5 to 5.0% of the grain, based on silver, and having an average iodide content of more than 40 mol %, an intermediate phase accounting for 10 to 70% of the grain, based on silver, and having an average iodide content of 0 to 10 mol %, a second high-iodide phase occupying 0.5 to 5% of the grain, based on silver, and having an average iodide content of more than 40 mol %, and a shell phase occupying 10 to 50% of the grain, based on silver, and having an average iodide content of 0 to 10 mol %;
(10) The silver halide emulsion of (9), wherein at least one of the first and second high-iodide phases accounts for 1 to 4% of the grain, based on silver;
(11) The silver halide emulsion of (10), wherein the intermediate phase accounts for 15 to 50% of the grain, based on silver;
(12) The silver halide emulsion of (11), wherein the shell phase accounts for 20 to 40% of the grain, based on silver and has an average iodide content of 0 to 6 mol %;
(13) The silver halide emulsion of (12), wherein the internal phase has an average iodide content of 0 to 3 mol %;
(14) A silver halide emulsion comprising silver halide grains and a dispersing medium, each of the silver halide grains comprising a high-iodide phase accounting for 1 to 3.5% of the grain, based on silver, and having an average iodide content of more than 40 mol %, wherein the grain further comprises dislocation lines located inside the high-iodide phase;
(15) The silver halide emulsion of (13), wherein the grain further comprises dislocation lines inside either of the first or second high-iodide phase;
(16) The silver halide emulsion of (15), wherein the grain comprises dislocation lines located inside and outside of either of the first or second high-iodide phase;
(17) The silver halide emulsion of (9), wherein at least 50% of total grain projected area is accounted for by tabular grains having an aspect ratio of at least 3;
(18) The silver halide emulsion of (9), wherein at least 50% of total grain projected area is accounted for by grains having at least 10 dislocation lines in the fringe portion;
(19) The silver halide emulsion of (9), wherein a variation coefficient of thickness of the grains in the emulsion is 25% or less;
(20) A silver halide emulsion comprising silver halide grains and a dispersing medium, wherein each of the silver halide grains comprises, from inside to outside of the grain, an internal phase accounting for 5 to 60% of the grain, based on silver, and having an iodide content of 0 to 10 mol %, a first high-iodide phase accounting for 0.5 to 5.0% of the grain, based on silver, and having an iodide content of more than 40 mol %, an intermediate phase accounting for 10 to 70% of the grain, based on silver, and having an iodide content of 0 to 10 mol %, a second high-iodide phase occupying 0.5 to 5% of the grain, based on silver, and having an iodide content of not less than 40 mol %, and a shell phase accounting for 10 to 50% of the grain, based on silver, and having an iodide content of 0 to 10 mol %;
(21) The silver halide emulsion of (20), wherein at least one of the first and second high-iodide phases accounts for 1 to 4% of the grain, based on silver;
(22) The silver halide emulsion of (21), wherein the intermediate phase accounts for 15 to 50% of the grain, based on silver;
(23) The silver halide emulsion of (22), wherein the shell phase occupies 20 to 40% of the grain, based on silver and has an iodide content of

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