Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-11-30
2001-11-13
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S569000, C430S605000, C430S550000
Reexamination Certificate
active
06316178
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a gold-sensitized silver halide emulsion having a high silver chloride content, and a light-sensitive material using the same. In particular, such a silver halide emulsion having a high silver chloride content is preferably used for a color photographic light-sensitive material having a reflective support.
BACKGROUND OF THE INVENTION
High-speed light-sensitive silver chloride emulsions have not been developed sufficiently, because the intrinsic absorption of the silver chloride emulsion is small, and adsorption of a spectral sensitizing dye onto the silver chloride grains is weak. Consequently, investigation into gold sensitization of a silver chloride emulsion has not been made thoroughly, even though gold sensitization has been applied to a silver bromide- or silver iodobromide-based emulsion, as a matter of course.
However, recently both the demand for high-speed light-sensitive material and the need for realization of more rapid development resulting from compatibility of finely grained silver halide and advances in high speed thereof, are growing. As a prior art relative to gold sensitization concerning the need for such as compatibility of finely grained silver chloride-based silver halide and advances in high speed thereof, there are, for example, JP-A-11-218870 (“JP-A” means unexamined published Japanese patent application), JP-A-11-217388, JP-A-9-118685, JP-A-9-15771, JP-A-9-5922, JP-A-3-151648, JP-A-4-335338, JP-A-6-347944, JP-A-8-62763, Japanese published searched patent publication No. 6-501789, and U.S. Pat. Nos. 5,756,278 and 5,912,112.
However, ionic conductance of the silver chloride-based silver halide emulsion is low, and therefore the supply of silver ions is slow in latent image formation upon exposure to light. Accordingly, the silver chloride-based silver halide emulsion has such an inefficiency that the latent image is considered to hardly grow. It is well known that this defect is particularly related to a property that the so-called high illumination intensity reciprocity law failure is easily caused. On the other hand, it is also well known that gold sensitization is an important technique to solve this problem, since gold sensitization is effective in reducing the minimum size of a latent image that can be developed. However, up to the present time, the effect has been insufficient for the silver chloride-based silver halide emulsion, since the high illumination intensity reciprocity law failure occurs when the kind and amount of a sulfur sensitizer and a gold sensitizer are increased or decreased (mostly, increased) to enhance the sensitivity for a middle illumination intensity exposure to light.
Further, it is also well known that a spectrally sensitized silver chloride-based silver halide emulsion causes a problem of the so-called latent image regression, which means that desensitization occurs, resulting from the latent image being destroyed for a short time after exposure. It is also known that this problem can be overcome by gold sensitization, whereby oxidation-resistance is improved. However, when the kind and amount of a sulfur sensitizer and a gold sensitizer were increased or decreased (mostly, increased) for advances in high speed, the latent image regression still became conspicuous. Consequently, even though various methods were tried, coexistence of improvement in high speed and prevention of latent image regression was difficult to attain sufficiently.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an emulsion having a high silver chloride content, which has high sensitivity and low fogging, and further which is low in both high illumination intensity reciprocity characteristics and regression of latent image. Another object of the present invention is to provide a light-sensitive material using the same.
Other and further objects, features, and advantages of the invention will appear more fully from the following description.
DETAILED DESCRIPTION OF THE INVENTION
As a result of an intensive investigation in consideration of the above-mentioned objects, the present inventors have discovered that the foregoing objects are accomplished by an emulsion containing silver halide grains in which the proportion of metal gold among gold existing on the part of the silver halide grains after gold sensitization is in the fixed range. The present invention has been made on the basis of this new knowledge.
Namely, the following silver halide emulsion and a silver halide color photographic light-sensitive material are provided according to the present invention.
(1) A silver halide emulsion comprising gold-sensitized silver halide grains having a silver chloride content of 95 mole % or more, wherein from 8% to 50% of the amount of gold existing on the part of the silver halide grains is in the state of metal gold.
(2) The silver halide emulsion as described in (1), wherein the amount of gold existing on the part of the silver halide grains in the emulsion is in the range of 40% to 80%, based on the total amount of gold in the emulsion.
(3) The silver halide emulsion as described in (1) or (2), wherein the total amount of gold in the emulsion is in the range of 0.05A×10
−4
mole to 1.2A×10
−4
mole per mole of silver halide, assuming that A (&mgr;m) is the side length of a cube whose volume is equal to the volume of the silver halide grain (the equivalent cube side length).
(4) A silver halide color photographic light-sensitive material having a support and having thereon at least one silver halide emulsion layer comprising the silver halide emulsion described in (1), (2), or (3).
The term “gold existing on the part of the silver halide grains” as used herein means gold that exists on the surface and/or inside of the silver halide grains. In other words, it means gold or ions thereof that are detected together silver halide grains when a silver halide emulsion is divided into the silver halide grain part and other component part.
In the present invention, the silver chloride content of the silver halide grains is from 95 mole % to 100 mole %, preferably from 98 mole % to 100 mole %. Further, it is preferable that silver bromide and/or silver iodide may be present outside the foregoing range.
The silver bromide content is preferably in the range of 0.01 mole % to 5 mole %, more preferably from 0.1 mole % to 1 mole %. The silver iodide content is preferably in the range of 0.01 mole % to 1 mole %, more preferably from 0.06 mole % to 0.1 mole %.
The silver bromide, the silver iodide, or the mixed crystals composed of silver chloride and silver bromide and/or silver iodide, may be used preferably inside the grain without any limitation of the position to be incorporated. However, it is preferable that they are incorporated particularly after 50% of grain formation has been accomplished. It is also preferable that they are used in the localized phase of the surface and the vicinity thereof, and/or the near surface.
In the present invention, a silver bromide-rich phase is preferably provided to the silver halide grains having a silver chloride content of 95 mole % or more. Preferably the silver bromide-rich phase is prepared by epitaxially growing a localized phase having a silver bromide content of 10 mole % or more in terms of the content (percentage) of total silver bromide in the silver bromide-rich phase.
The silver bromide content of the silver bromide-rich phase is preferably 10 mole % or more in total. However, if the silver bromide content excessively high, the silver bromide-rich phase sometimes imparts unpreferable characteristics against the photographic light-sensitive material, such that when a pressure is applied to a light-sensitive material, desensitization occurs, and that sensitivity and/or gradation are substantially altered by fluctuation in the composition of a processing solution. Taking these points into consideration, the silver bromide content of the silver bromide-rich phase is preferably in the range of 10 mole % to 60 mo
Fuji Photo Film Co. , Ltd.
Schilling Richard L.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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