Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-07-07
2004-05-04
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S572000, C430S574000
Reexamination Certificate
active
06730468
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a photographic light-sensitive material using a spectrally sensitized silver halide photographic emulsion.
BACKGROUND OF THE INVENTION
Heretofore, a great deal of efforts have been made for attaining high sensitivity of silver halide photographic light-sensitive materials. In silver halide photographic emulsions, a sensitizing dye adsorbed to the surface of a silver halide grain absorbs light entered into a light-sensitive material and the light energy is transmitted to the silver halide grain, thereby obtaining light sensitivity. Accordingly, in the spectral sensitization of silver halide, it is considered that by increasing the light absorption factor per the unit grain surface area of silver halide grains, the light energy transmitted to silver halide can be increased and in turn high spectral sensitivity can be achieved. The light absorption factor on the surface of the silver halide grain may be improved by increasing the amount of the spectral sensitizing dye adsorbed per the unit grain surface area.
However, the amount of the sensitizing dye adsorbed to the surface of a silver halide grain is limited and the dye chromophore cannot be adsorbed in excess of the single layer saturation adsorption (namely, one layer adsorption). Therefore, individual silver halide grains are obliged to show a low absorption factor for the quantum of incident light in the spectral sensitization region at present.
To solve these problems, the following methods have been proposed.
In
Photographic Science and Engineering,
Vol. 20, No. 3, page 97 (1976), P. B. Gilman, Jr. et al. disclose a technique where a cationic dye is adsorbed to the first layer and an anionic dye is adsorbed to the second layer using an electrostatic force.
In U.S. Pat. No. 3,622,316, G. B. Bird et al. disclose a technique where a plurality of dyes are adsorbed in multiple layers to silver halide and the Forster-type excitation energy transfer is allowed to contribute to the sensitization.
In JP-A-63-138341 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) and JP-A-64-84244, Sugimoto et al. disclose a technique of performing the spectral sensitization using the energy transfer from a light-emitting dye.
In
Photographic Science and Engineering
, Vol. 27, No. 2, page 59 (1983), R. Steiger et al. disclose a technique of performing the spectral sensitization using the energy transfer from a gelatin-substituted cyanine dye.
In JP-A-61-251842, Ikegawa et al. disclose a technique of performing the spectral sensitization using the energy transfer from a cyclodextrin-substituted dye.
Furthermore, in EP-A-0985964, EP-A-0985965 and EP-A-0985966, Richard Parton et al. disclose a technique where a combination of a cationic dye and an anionic dye is adsorbed in multiple layers with an attempt to attain high sensitivity using the energy transfer from the dye in the second or upper layer to the dye in the first layer.
In these methods, however, the degree of adsorption of sensitizing dyes in multiple layers on the surface of a silver halide grain is actually insufficient and neither the light absorption factor per the unit grain surface area of silver halide grains nor the sensitivity can be sufficiently highly increased. A technique capable of intensifying the interaction between dye molecules and thereby realizing practically effective multilayer adsorption is demanded.
On the other hand, when the interaction between molecules is intensified and the practically effective multilayer adsorption is realized, the following unexpected problems are found to occur:
(1) reduction of sensitivity and softening of contrast due to non-uniform distribution of the dye adsorbed amount among grains,
(2) reduction of sensitivity and deterioration of graininess due to island-like adsorption, and
(3) reduction of image quality due to small change in the absorption spectrum between before and after the photographic processing.
These phenomena are described below.
When the interaction between dye molecules is intensified so as to realize the multilayer adsorption, it is found that the distribution of the dye adsorbed amount is liable to be non-uniform among grains. In the ordinary single layer adsorption, as the amount of the sensitizing dye adsorbed increases, the distribution of the dye adsorbed amount becomes more uniform among grains, therefore, the above-described non-uniform distribution of the dye adsorbed amount in the case of multilayer adsorption is quite an unexpected result. Moreover, as compared with the single layer adsorption, the problems incurred by the non-uniform distribution of the dye adsorbed amount are extremely serious and this is also an unexpected phenomenon.
Also, when the interaction between dye molecules is intensified so as to realize the multilayer adsorption, it is found that the dyes in the second and upper layers do not grow in the layer form and fail to be present in the layer state but grow like islands and are present in the island state. In the ordinary single layer adsorption, it is known that as the amount of the sensitizing dye adsorbed increases, the dye grows in the layer form on a silver halide grains and is finally present in the layer state. Therefore, the behavior of the dyes in the second and upper layers in the case of multilayer adsorption such that they grow like islands and are present in the island state is a phenomenon not anticipated. Moreover, in the case where the dyes in the second and upper layers grow like islands and are present in the island state, it is found that not only the light absorption strength and the sensitivity are reduced but also the image quality is deteriorated, and these are problems beyond the expectation. The interaction for establishing the multilayer adsorption structure fundamentally includes two interactions, namely, (1) the interaction between the dye molecule in the first layer and the dye molecule in the second layer and (2) the interaction between dye molecules in the second layer. As a result of analysis, it is found that if the ratio of (b) the interaction between dye molecules in the second layer increases, the distribution of the dye adsorbed amount is broadened among the grains and also the island-like adsorption is liable to occur.
Furthermore, although the cause is not known, it is found that in the case of an emulsion grown through multilayer adsorption and having high light absorption strength, if the change in the absorption wave form between before and after the photographic processing is small, the image quality seriously decreases. These phenomena are not anticipated because they do not occur in the conventional single layer adsorption.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a silver halide photographic light-sensitive material having capability of complementing the entrance of incident photons by allowing a sensitizing dye to adsorb in multiple layers onto a surface of a silver halide grain and at the same time reduced in various problems accompanying the multilayer adsorption of a sensitizing dye.
As a result of extensive investigations, the above-described object can be attained by the following matters (1) to (21).
(1) A silver halide photographic emulsion comprising a silver halide grain having adsorbed on the surface thereof a sensitizing dye in multiple layers, wherein the variation coefficient of the light absorption strength distribution among the grains is 100% or less.
(2) A silver halide photographic emulsion comprising a silver halide grain having adsorbed on the surface thereof a sensitizing dye in multiple layers, wherein assuming that the maximum value of the spectral absorption ratio by the sensitizing dye is Amax, the variation coefficient of the wavelength distance distribution between the shortest wavelength and the longest wavelength out of the wavelengths showing 50% of the Amax among the grains is 50% or less.
(3) A silver halide photographic emulsion comprising a silver halide grain having adsorbe
Hioki Takanori
Kobayashi Katsumi
Yamashita Katsuhiro
Chea Thorl
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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