Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2002-06-12
2003-12-16
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S599000, C430S605000
Reexamination Certificate
active
06664037
ABSTRACT:
TECHNICAL FIELD
The present invention belongs to the technical fields of silver halide photographic emulsion and method for chemical sensitization thereof, in particular, the technical fields of silver halide photographic emulsion of which sensitivity, fog and storability are improved by controlled chalcogen sensitization and method for chemical sensitization of such an emulsion.
RELATED ART
In silver halide photographic light-sensitive materials, silver halide emulsions subjected to chemical sensitization using various kinds of chemical substances are generally used in order to obtain desired sensitivity, gradation and so forth. As typical methods for that purpose, there are known various sensitization techniques including chalcogen sensitization such as sulfur sensitization, selenium sensitization and tellurium sensitization, noble metal sensitization such as gold sensitization, reduction sensitization using a reducing agent and so forth, which are used each alone or in combination. In recent years, the requirements for higher sensitivity, superior granularity, gradation or high sharpness, good storability, quick development with accelerated progress of development and so forth for silver halide photographic light-sensitive materials are increasingly become severer.
Among the aforementioned techniques, the chalcogen sensitization is a technique indispensable to high sensitivity silver halide photographic emulsions, and various researches have been conducted for many years aiming at further higher sensitivity. However, higher sensitivity invites, in particular, increase of fog, and long term storage always invites sensitivity fluctuation and increase of fog. Therefore, there have been strongly desired ameliorations of these problems. As for these problems, there has hitherto been attempted to solve them by addition of antifoggants or stabilizers, improvement of chalcogen sensitizers and so forth. However, these attempts have been made mainly on trial and error basis to provide improvements, and any universal technique has not been established. On the other hand, although noble metal sensitization that utilizes a transition metal for chemical sensitization is known for many years, any method of realizing effective action of chemical sensitization with a transition metal by combination with chalcogen sensitization has not been known at all.
SUMMARY OF THE INVENTION
The present invention was accomplished in view of all the aforementioned problems, and the first object of the present invention is to provide a silver halide emulsion showing high sensitivity and low fog. The second object of the present invention is to provide a silver halide emulsion showing superior storability. The third object of the present invention is to provide a method for chemical sensitization that provides a silver halide emulsion showing high sensitivity without degrading fog and storability.
In order to achieve the aforementioned objects, the inventor of the present invention paid attention to the relationship between crystallinity of silver chalcogenide or gold silver chalcogenide produced by chalcogen sensitization and characteristics of the obtained emulsion, and conducted various researches on the relationship. As a result, he found that, if at least a part of silver chalcogenide or gold silver chalcogenide produced by chalcogen sensitization is amorphous, an emulsion showing superior characteristics could be obtained, and accomplished the present invention based on this finding.
In order to achieve the aforementioned objects, the silver halide emulsion of the present invention is a silver halide emulsion containing silver chalcogenide or gold silver chalcogenide produced by chemical sensitization, wherein at least a part of the silver chalcogenide or gold silver chalcogenide is amorphous.
In the present invention, intensity of a maximum X-ray diffraction peak of the silver chalcogenide or gold silver chalcogenide is preferably ½ or less of intensity of a maximum X-ray diffraction peak of silver chalcogenide or gold silver chalcogenide that is not amorphized.
Further, in order to achieve the aforementioned objects, the method for chemical sensitization of a silver halide emulsion of the present invention is a method for chemical sensitization of a silver halide emulsion comprising a sensitization step of subjecting the silver halide emulsion to chemical sensitization with a chalcogen compound or a chalcogen compound and a gold compound to produce silver chalcogenide or gold silver chalcogenide, wherein the chemical sensitization is performed under such conditions that at least a part of the silver chalcogenide or gold silver chalcogenide produced in the sensitization step should be amorphized.
In the chemical sensitization method of the present invention, the chemical sensitization is preferably performed in the presence of transition metal ions of at least one metal selected from the metals of Group IB, Group IIB, Group VIA, Group VIIA and Group VIII. Further, in the chemical sensitization method of the present invention, the maximum X-ray diffraction peak intensity of silver chalcogenide or gold silver chalcogenide obtained for a standard model as defined in the following (a) (Intensity A) and the maximum X-ray diffraction peak intensity of silver chalcogenide or gold silver chalcogenide obtained by applying the chemical sensitization conditions of the chemical sensitization step to a simplified model as defined in the following (b) (Intensity B) preferably satisfy the relational equation defined in the following (c):
(a) silver chalcogenide or gold silver chalcogenide produced by mixing 20 mL of 0.01 mol/L silver nitrate aqueous solution, 20 mL of 0.01 mol/L solution of the chalcogen compound in water or an alcohol and, when a gold compound is also used in the chemical sensitization, 0.01 mol/L solution of the gold compound in water or an alcohol in such an amount that the gold compound and the chalcogen compound should exist in the same molar ratio as that used for the chemical sensitization at the temperature used for the chemical sensitization,
(b) silver chalcogenide or gold silver chalcogenide produced by mixing the chalcogen compound or the chalcogen compound and the gold compound with 20 mL of 0.01 mol/L silver nitrate aqueous solution under the same conditions as those of the chemical sensitization, except that the silver halide emulsion does not exist, the chalcogen compound is added as 0.01 mol/L solution in water or an alcohol and the other additives are added in such amounts that molar ratios of the additives with respect to the chalcogen compound should be the same as those used for the chemical sensitization,
(c) B/A≦½.
According to the present invention, there can be provided a silver halide emulsion showing high sensitivity, low fog and superior storability. According to the present invention, there can also be provided a method for chemical sensitization of a silver halide emulsion, which provides a silver halide emulsion showing high sensitivity while obviating increase of fog and degradation of storability.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be explained in detail hereafter. In the following description, ranges indicated with “-” mean ranges including the numerical values before and after “-” as the minimum and maximum values.
The silver halide emulsion of the present invention contains silver chalcogenide or gold silver chalcogenide produced by chemical sensitization. It is sufficient that the silver halide emulsion of the present invention be chemically sensitized by using at least a chalcogen compound (henceforth referred to as “chalcogen sensitization”), and it may be chemically sensitized by a combination of chalcogen sensitization and another type of sensitization. As the other type of sensitization, gold sensitization is preferred. When chalcogen sensitization and gold sensitization are used in combination, gold silver chalcogenide is formed by chalcogen sensitization. The chalcogen sensitization include sulfur sensiti
Fuji Photo Film Co., LTD
Le Hoa Van
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