Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
1998-09-24
2001-02-06
Huff, Mark F. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S569000, C430S605000
Reexamination Certificate
active
06183946
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a silver halide emulsion having excellent high-illuminance reciprocity law failure characteristics, reduced in change of sensitivity and change of gradation due to changing in the time after exposure until processing and small in the reduction of sensitivity on exposure at a high humidity, a production process thereof and a silver halide color photographic light-sensitive material using the same.
BACKGROUND OF THE INVENTION
In recent years, requirements for the capabilities of a color printing paper, such as high sensitivity, processing stability, high-quality image and rapid processability in the development processing step are increasing. On the other hand, as a result of recent popularization of laser scanning exposure apparatuses, suitability for short-time and high-illuminance exposure is one of the important capabilities. The laser scanning exposure is advantageous in that high-speed exposure is attained and the resolution is improved. However, for applying this to a color printing paper, suitability for unusually very short-time (specifically, 10
−6
second) and high-illuminance exposure is required.
In order to improve the reciprocity law failure of the silver halide emulsion at such high-illuminance exposure, a method of doping a metal compound represented by iridium to the base grain is well known in the art.
The improvement of the reciprocity law failure of the silver halide emulsion by iridium is described, for example, in B. H. Carroll, Iridium Sensitization: A Literature Review of
Photographic Science and Engineering,
Vol. 24, No. 6 (1980), and R. S. Eachus,
The Mechanism of Ir
3
+ Sensitization
(
International Meeting
1982
of Photographic Science).
On the other hand, it is also known that the silver halide emulsion having added thereto iridium has a very undesired characteristic such that the photographic capabilities (for example, sensitivity, gradation) change in the time passing after the exposure until the processing. This characteristic is described in H. Zwicky, On the Mechanism of the Sensitivity Increase With Iridium in Silver Halide Emulsions of
The Journal of Photographic Science,
Vol. 33, pp. 201-203 (1985). According to the methods hitherto proposed, the high-illuminance reciprocity law failure is surely improved but the sensitivity very greatly changes due to changing in the time after exposure until processing and the practical use is not expected at all.
A silver halide emulsion having a high silver chloride content has a purpose of rapid processing in the color development but is deficient in that high-sensitivity high-contrast gradation cannot be obtained by usual chemical sensitization. A large number of attempts have been made to achieve high sensitivity of a high silver chloride emulsion. Among those, a technique of forming a silver bromide-rich phase in the vicinity of the grain apex of a silver halide host grain to thereby achieve high sensitivity is disclosed in JP-A-64-26837 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”). Further, JP-A-5-61136 discloses a technique of forming a silver bromide-rich phase in the vicinity of the grain apex of a silver halide host grain through multiple stages. According to these techniques, however, the high-illuminance reciprocity law failure is not improved. U.S. Pat. Nos. 5,284,745, 5,391,471, 5,415,991, 5,043,256 and 5,627,020 disclose a method of doping a metal compound represented by Ir to the inside of a silver bromide-rich phase of a high silver chloride base grain. Further, European Patent Publication 0568091A, U.S. Pat. No. 5,356,770 and JP-A-6-35147 disclose a method of adding a bromide to a high silver chloride grain simultaneously with or after the addition of iridium. According to these methods, the change of sensitivity due to changing in the time after exposure until processing is suppressed and the high-illuminance reciprocity law failure is improved, however, the effect is still not sufficient in the case of a high-illuminance exposure for a very short time, such as laser scanning exposure. In addition, reduction in the sensitivity occurred on exposure at a high humidity is not prevented.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a silver halide emulsion having excellent reciprocity law failure characteristics on short-time high-illuminance exposure, reduced in change of sensitivity due to changing in the time after exposure until processing and small in the reduction of sensitivity on exposure at a high humidity.
Another object of the present invention is to provide a process for producing the silver halide emulsion.
A still another object of the present invention is to provide a silver halide color photographic light-sensitive material using the silver halide emulsion.
A further object of the present invention is to provide a method for forming an image using the silver halide emulsion.
As a result of extensive investigations, the present inventors have found that the above-described objects can be effectively achieved by the following methods (1) to (7).
(1) A silver halide emulsion which is a silver chlorobromide or silver chloroiodobromide emulsion having a silver chloride content of 90 mol % or more,
wherein the silver halide grain in said emulsion has a silver bromide-rich phase containing an iridium compound in the vicinity of the grain surface and
the silver bromide-rich phase comprises an inner side part region and an outer side part region, wherein the inner side part region has a higher iridium compound density than the outer side part region has.
(2) The silver halide emulsion as described in (1), wherein the silver halide grain is a cubic or tetradecahedral grain.
(3) The silver halide emulsion as described in (1), wherein 50% or more of the entire projected area of all grains in the silver halide emulsion is occupied by tabular grains having {100} faces as major faces and having an average aspect ratio of 2 or more or tabular grains having {111} faces as major faces and having an average aspect ratio of 2 or more.
(4) A process for producing a silver halide emulsion, comprising forming a silver bromide-rich phase containing an iridium compound in the vicinity of the grain surface of a silver halide grain in a silver chlorobromide or silver chloroiodobromide emulsion having a silver chloride content of 90 mol % or more, wherein the formation process for forming the silver bromide-rich phase comprises at least two stages and the molar amount of the iridium compound added in one formation process based on the silver added is higher than the molar amount of the iridium compound added in any one of the formation processes subsequent thereto based on the silver added.
(5) The process for producing a silver halide emulsion as described in (4), wherein the silver bromide-rich phase is formed by adding at least twice a silver bromide fine grain emulsion or silver chlorobromide fine grain emulsion having a grain size smaller than that of a silver halide emulsion comprising a silver chlorobromide or silver chloroiodobromide host grains.
(6) A silver halide color photographic light-sensitive material comprising a support having thereon at least one blue-sensitive silver halide emulsion layer, at least one green-sensitive silver halide emulsion layer and at least one red-sensitive silver halide emulsion layer,
wherein at least one of said blue-sensitive silver halide emulsion layer, green-sensitive silver halide emulsion layer and red-sensitive silver halide emulsion layer contains a silver chlorobromide or silver chloroiodobromide emulsion having a silver chloride content of 90 mol % or more,
wherein the silver halide grain in said emulsion has a silver bromide-rich phase containing an iridium compound in the vicinity of the grain surface and
the silver bromide-rich phase comprises an inner side part region and an outer side part region, wherein the inner side part region has a higher iridium compound d
Burns Doane , Swecker, Mathis LLP
Fuji Photo Film Co. , Ltd.
Huff Mark F.
Walke Amanda C.
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