Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
1999-03-03
2001-10-23
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S569000
Reexamination Certificate
active
06306569
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a silver halide emulsion and the like and, more particularly, to a silver halide emulsion and the like characterized by a silver halide grain chemical sensitization method.
To improve the graininess of images of color photosensitive materials, particularly color reversal sensitive materials often used by professional photographers, it is necessary to minimize the size of emulsion grains contained in each color sensitive layer. However, the sensitivity generally lowers when the grain size is decreased, so a sensitivity increasing technique is required to compensate for this lowering of the sensitivity. U.S. Pat. Nos. (hereinafter also referred to as U.S.) 4,434,226, 4,439,520, 4,414,310, 4,433,048, 4,414,306, and 4,459,353 have disclosed sensitivity increasing techniques by which the color sensitization ratio by spectral sensitization dyes is improved by increasing the surface area of grains for receiving light by the use of tabular silver halide grains, compared to a case wherein grains of the same size are used. The present inventors have examined grains having an aspect ratio of 2 or more and found that as the aspect ratio is increased, it is possible to use larger amounts of sensitizing dyes and improve the spectral sensitivity.
BRIEF SUMMARY OF THE INVENTION
The present inventors obtained an unexpected result that no desired sensitivity can be obtained even when the aforementioned tabular grains are optimally chemically sensitized if the aspect ratio of the grains is increased. When the aspect ratio is increased, a large color sensitization increase is obtained. However, the intrinsic sensitivity of an emulsion is lower than this increase. It is estimated that this low sensitivity is caused by a factor which makes the rearrangement (aggregation) process (D. J. Cash, J. Photogr. Sci. 20, 19(1972)) insufficient which occurs subsequently to the formation of chalcogen silver in the chemical sensitization process. Accordingly, an epoch-making chemical sensitization method which increases the sensitivity/graininess ratio by suppressing this inefficiency is being demanded.
It is, therefore, an object of the present invention to provide a silver halide emulsion having a high sensitivity/graininess ratio, a method of manufacturing the emulsion, a silver halide photosensitive material containing the emulsion, and a method of processing the sensitive material.
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have made extensive studies to obtain a tabular photographic emulsion having a high sensitivity/graininess ratio and an aspect ratio of 2 or more. Consequently, the present inventors have found that the sensitivity can be increased when chemical sensitization is performed by ripening or digesting silver halide grains by the addition of (1) fine silver halide grains smaller than the silver halide grains, (2) a solution containing silver ions, (3) a solution containing halide ions and a solution containing silver ions, or (4) a fine silver halide grain emulsion and a solution containing silver ions (in either case, the amount of the addition in terms of silver is 0.05 to 8 mol % per mol of silver in the silver halide grains) after the reaction of chemical sensitizers has proceeded to some extent during the chemical sensitization process. This technique is found to have another advantage of being able to decrease the amounts of sensitizers used. Additionally, it is surprising that the effect is particularly notable when the average projected area diameter of grains is 0.5 &mgr;m or less. Accordingly, it is possible to provide tabular grains having both a high aspect ratio and a high sensitivity/graininess ratio.
The present inventors have also confirmed that a similar effect can be obtained when the above chemical sensitization method is applied to regular crystal grains other than tabular grains.
The above object, therefore, is achieved by silver halide emulsions, a method of manufacturing the emulsions, a silver halide photosensitive material containing the emulsions, and a method of developing the material.
(1) A silver halide emulsion containing chemically sensitized silver halide grains, wherein the silver halide grains are prepared by ripening the grains by the addition of (1) fine silver halide grains smaller than the silver halide grains, (2) a solution containing silver ions, (3) a solution containing halide ions and a solution containing silver ions, or (4) a fine silver halide grain emulsion and a solution containing silver ions (in either case, the silver ion content is 0.05 to 8 mol % per mol of silver in the silver halide grains) after 40% or more of the reaction of chalcogen sensitizers are complete and before the silver halide grains are optimally ripened during the chemical sensitization process.
(2) The silver halide emulsion described in item (1) above, wherein the silver halide grains are tabular silver halide grains having an aspect ratio of 2 to 30 and the variation coefficient of the aspect ratio is 30% or less.
(3) The silver halide emulsion described in item (1) or (2) above, wherein the average silver iodide content of the silver halide grains is 0.5 to 10 mol %.
(4) The silver halide emulsion described in any one of items (1) to (3) above, wherein the silver halide grains are subjected to gold-sulfur-selenium sensitization.
(5) The silver halide emulsion described in any one of items (1) to (4) above, wherein the fine silver halide grains or solution containing halide ions to be added during the chemical sensitization process. contains 20 mol % or less of iodide ions.
(6) The silver halide emulsion described in any one of items (1) to (5) above, wherein the fine silver halide grains or solution containing halide ions to be added during the chemical sensitization process contains 10 mol % or less of chloride ions.
(7) A method of manufacturing a silver halide emulsion containing chemically sensitized silver halide grains, wherein the silver halide grains are prepared by ripening the grains by the addition of (1) fine silver halide grains smaller than the silver halide grains, (2) a solution containing silver ions, (3) a solution containing halide ions and a solution containing silver ions, or (4) a fine silver halide grain emulsion and a solution containing silver ions (in either case, the amount of the addition in terms of silver is 0.05 to 8 mol % per mol of silver in the silver halide grains) after 40% or more of the reaction of chalcogen sensitizers are complete and before the silver halide grains are optimally ripened during the chemical sensitization process.
(8) A silver halide photosensitive material having at least one light-sensitive silver halide emulsion layer on a support, wherein the light-sensitive silver halide emulsion layer contains the silver halide emulsion described in any one of items (1) to (6) above.
(9) A silver halide photosensitive material developing method of image-wise exposing and developing the silver halide photosensitive material described in item (8) above, wherein the method comprises a processing step performed in a developer in which a solution physical development occurs.
The present invention will be described in detail below.
In the present invention, optimum ripening indicates the state after the sensitivity rises with the ripening or digesting time and immediately before the sensitivity starts falling when chemical sensitization is performed with a given chemical sensitizer amount. In the present invention, therefore, optimum ripening of silver halide grains means the state after the sensitivity of emulsion containing the silver halide grains rises with the ripening time and immediately before the sensitivity starts falling when predetermined amounts of chemical sensitizers are added.
In the present invention, chalcogen sensitization is chemical sensitization performed by using at least one of a sulfur sensitizer, selenium sensitizer, and tellurium sensitizer (to be described later).
The reaction rate of chalocogen sensitization used in the in
Ikeda Hideo
Morimura Kimiyasu
Fuji Photo Film Co. , Ltd.
Le Hoa Van
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