Silver halide photographic material

Details Silver halide photographic material Silver halide photographic material

2002-01-30

2004-07-06

Letscher, Geraldine (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Radiation sensitive product

Silver compound sensitizer containing

C430S570000, C430S581000, C430S582000, C430S583000, C430S584000, C430S600000, C430S603000

Reexamination Certificate

active

06759186

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a silver halide photographic material. More particularly, the present invention relates to a silver halide photographic material which exhibits a high sensitivity and leaves little undesired color unextinguished (i.e., little residual color) even after rapid process.
BACKGROUND OF THE INVENTION
A great effort has heretofore been made to enhance the sensitivity of silver halide photographic light-sensitive materials and allow the silver halide photographic materials to leave less undesired color unextinguished (i.e., less residual color) after processing. In addition to photographic requirements for higher sensitivity and image quality, there has been a growing demand for the enhancement of photographic processing speed, reduction of the amount of waste liquid under the necessity of meeting environmental protection, etc. It has thus been desired to develop a technique for spectrally sensitizing silver halide grains to a high degree without having adverse effects such as fog and color remaining (i.e., residual color).
It has been known that sensitizing dyes for use in spectral sensitization have a great effect on the properties of silver halide photographic materials. Even a small structural difference between sensitizing dyes has a great effect on photographic properties such as sensitivity, fog, storage stability and color remaining after processing. Further, the combined use of two or more sensitizing dyes, too, have a great effect on photographic properties. It is difficult to predict these effects. Many researchers have heretofore synthesized a large number of sensitizing dyes. Many researchers have also made studies of combined use of a large number of sensitizing dyes and efforts to examine the photographic properties. However, it is the status quo that the photographic properties cannot still be predicted.
A tabular silver halide grain has a great surface area per volume (specific surface area) and thus is advantageous for spectral sensitization because it can adsorb a large amount of a sensitizing dye. Such a tabular silver halide grain is also useful in the improvement of sensitivity/graininess. However, it accordingly causes more dye color remaining (i.e., dye-residual color). This color remaining problem is more severe than caused by regular grains.
On the other hand, it has been desired to reduce the photographic processing time. However, when the processing time is reduced, the emulsion leaves more sensitizing dyes unprocessed, causing more severe color remaining problem. In some photofinishing laboratories, photographic light-sensitive materials are processed with processing solutions having varied formulations or rinsed at low temperatures, occasionally causing severe color remaining. It has thus been keenly desired to develop a technique for lessening color remaining of sensitizing dyes.
The occurrence of color remaining of sensitizing dyes depends greatly on the hydrophobicity of the dyes. In other words, the more hydrophilic is a dye, the less occurs color remaining. On the other hand, however, the dye exhibits a reduced adsorptivity to the surface of silver halide grains, having adverse effects on photographic properties such as sensitivity drop and deterioration of preservability. Thus, it is not desired to render a dye excessively hydrophilic. In short, in order to lessen color remaining while keeping desired photographic properties, it is necessary to select the hydrophilicity or hydrophobicity of a dye appropriately. The inventors disclose in Japanese Patent Application (Laid-Pen) No. 2001-75224 that the optimum selection of various substituents on sensitizing dyes makes it possible to attain both desired photographic properties and minimization of color remaining.
However, the recent trend is that factors such as rise of aspect ratio of tabular silver halide grains and further rise of the added amount of sensitizing dyes cause another problem. In other words, it has been made obvious that when a large amount of a sensitizing dye is added to a tabular grain, the sensitizing dye adsorbed at a high percent coverage causes gelatin to lose its function as a protective colloid. In particular, tabular grains having a high aspect ratio are subject to contact of main planes and coalescence of grains and hence agglomeration, causing side effects such as increased occurrence of fog or sensitivity drop during aging of emulsion in the form of solution and deterioration of graininess. As a countermeasure against these difficulties there has been known a method as disclosed in Japanese Patent Application (Laid-Open) No. 1994-332091 involving the addition of a fine emulsion of substantially insoluble silver bromoiodide grains during or after the chemical sensitization of a silver halide emulsion. However, this approach cannot be applied to all emulsions. It has been desired to provide a substitute for this approach.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a silver halide photographic material which exhibits a high sensitivity and leaves little undesired color unextinguished (i.e., little residual color) even after rapid processing or processing under severe conditions.
As a result of extensive studies, the object of the present invention was accomplished by the following aspects (1) to (11) of the present invention:
(1) A silver halide photographic material comprising at least one silver halide emulsion layer provided on a support, the emulsion layer comprising a silver halide emulsion containing at least two sensitizing dyes represented by the following general formula (I):
wherein X represents an oxygen atom, sulfur atom, selenium atom or NR′; R and R′ each represent a substituted or unsubstituted alkyl, aryl or heterocyclic group; D represents a group required to form a methine dye; M represents a counter ion; and m represents a number of not smaller than 0 required to neutralize the electric charge in the molecule.
(2) The silver halide photographic material according to the above item (1), wherein the two sensitizing dyes each are a cyanine dye.
(3) The silver halide photographic material according to the above item (1) or (2), wherein the two sensitizing dyes each are represented by the following general formula (II):
wherein X
1
and X
2
each represent an oxygen atom, sulfur atom, selenium atom or NR
3
; R
1
, R
2
and R
3
each represent a substituted or unsubstituted alkyl, aryl or heterocyclic group; Y
1
represents a condensed ring which may have substituents; L
1
, L
2
and L
3
each represent a methine group; n
1
represents 0, 1, 2 or 3, with the proviso that when n
1
is 2 or 3, the plurality of L
2
's and L
3
's each may be the same or different; M
1
represents a counter ion; and m
1
represents a number of not smaller than 0 required to neutralize the electric charge in the molecule.
(4) The silver halide photographic material according to the above item (3), wherein n
1
in the two sensitizing dyes are the same.
(5) The silver halide photographic material according to the above item (3), wherein X
1
and X
2
each are selected from the group consisting of oxygen atom and sulfur atom.
(6) The silver halide photographic material according to any one of the above items (1) to (5), wherein the two sensitizing dyes each have at least two dissociative groups.
(7) The silver halide photographic material according to the above item (6), wherein the sensitizing dyes each have at least one —SO
3
H group and at least one dissociative group other than —SO
3
H.
(8) The silver halide photographic material according to the above item (7), wherein the dissociative group other than —SO
3
H is selected from the group consisting of —COOH, —CONHSO
2
Z, —SO
2
NHCOZ, —SO
2
NHSO
2
Z and —CONHCOZ in which Z represents an alkyl group, aryl group, heterocyclic group, alkoxy group, aryloxy group, heterocyclyloxy group or amino group.
(9) A silver halide photographic material comprising at least one silver halide emulsion layer provided on a support, the emulsion l

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