Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
1999-06-07
2001-09-25
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S567000
Reexamination Certificate
active
06294319
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to silver halide photographic emulsions, and in particular to a preparation method of silver halide photographic emulsions with superior sensitivity and graininess and a silver halide light sensitive photographic materials by use thereof.
BACKGROUND OF THE INVENTION
Recently, along with the increased popularity of picture-taking instruments such as cameras, there increase picture-taking chances by use of a silver halide light sensitive photographic material (hereinafter, also referred to as a photographic material). As a result, further enhancement in sensitivity and image quality has been desired by the public.
One dominant factor for enhancing sensitivity and image quality of the photographic material concerns silver halide grains, and there has been on going development of silver halide grains aimed at enhancement of sensitivity and image quality. As is well recognized in the art, however, in conjunction with decreasing the silver halide grain size for enhancing image quality, the sensitivity tends to be lowered, and enhancing both sensitivity and image quality has its limits.
JP-A5-323487, 6-11781, 6-11782, 6-27564, 6-250309, 6-250310, 6-250311, 6-250313 and 6-242527 each disclose techniques for achieving enhanced sensitivity and improved fog and pressure resistance by the use of an iodide ion-releasing compound during grain formation.
However, the prior art described above is limited in achieving enhancement of both sensitivity and image quality and insufficient for satisfying requirements in recent photographic materials, therefore, development of a technique superior to the prior art is desired.
SUMMARY OF THE INVENTION
An object of the present invention relates to a preparation method of a silver halide photographic emulsion and particularly to a method of uniformly supplying, among silver halide grains, halide ions other than an iodide ion, which are to be included in the interior and exterior of silver halide grains, leading to characteristic localization of silver halide composition in the interior and exterior of the grain.
Thus, it is an object of the present invention to provide a method for preparing a silver halide emulsion with superior sensitivity and graininess and a silver halide light sensitive photographic material by use thereof.
The above object of the invention can be accomplished by the following constitution:
a method for preparing a silver halide emulsion comprising the steps of:
(1) forming a silver halide grain emulsion,
(2) subjecting the formed silver halide emulsion to desalting to remove soluble salts,
(3) subjecting the silver halide emulsion to spectral and/or chemical sensitization, and
(4) preparing a coating solution using the spectrally and/or chemically sensitized silver halide emulsion, wherein in any of the steps (1) to (4), a compound represented by the following formula (I) is incorporated into the silver halide emulsion:
formula (I)
{X—(L
1
)
n1
)}
n2
—L
2
—(SOL)
m
wherein X represents a chlorine atom or a bromine atom; L
1
and L
2
each represent a bivalent linkage group; SOL represents a water-solubilizing group; n1 is 0 or 1; and m and n2 each are an integer of 1 to 4.
DETAILED DESCRIPTION OF THE INVENTION
The compound for use in silver halide photographic materials relating to the invention can reduce inhomogeniety of the bromide or chloride content among silver halide grains, leading to enhanced relationship between speed and granularity. Comparing cases of forming an iodide by use of an iodide releasing compound, the compound has little adverse effect on photographic performance, such as development restraining and is broadly applicable to high chloride silver halide emulsions.
The process of preparing a photographic emulsion and a silver halide photographic material comprises the steps of formation of silver halide grains, desalting, spectral sensitization, chemical sensitization, preparation of coating solutions, coating, and drying. The compound for use in photographic materials, characterized in that the compound contain a substituent capable of releasing a bromide or chloride ion (hereinafter, also denoted as a compound of the invention), can be used in at least one step from the start of forming silver halide grains to the start of coating photographic material.
The formation of silver halide grains includes formation of silver halide nucleus grains (nucleation), crystal growth of the nucleus grains and physical ripening of the grains; therefore it includes any process prior to emulsion washing to remove soluble salts.
The compound of the invention can be used at any stage of the process for preparing a silver halide emulsion, preferably at a step after forming 80% of final grains, based on silver. Thus, the compound is used preferably at the latter stage of silver halide grain formation, desalting, spectral sensitization, chemical sensitization stages and the stage of preparing a coating solution. Further, the compound is incorporated more preferably at the step after desalting and prior to spectral sensitization and/or chemical sensitization, or at the stage after completion of spectral sensitization and/or chemical sensitization and before completion of preparing of a coating solution.
When the compound of the invention is added in the process of preparing a silver halide emulsion, the compound may be directly dispersed in an emulsion or dissolved in a single or mixed solvent, such as water, methanol or ethanol, and any method known in the art of adding an additive to a silver halide emulsion can be applicable. The compound can be added preferably in an amount of 1×10
−7
to 30 mol %, and more preferably 1×10
−5
to 5 mol % per mol of silver halide.
The compound of the invention may be used by adding to the silver halide emulsion and after addition, optionally allowed to release a bromide or chloride ion upon reaction with a base and/or a nucleophilic agent. The base and nucleophilic agent may be used in combination thereof. Examples of the nucleophilic agent usable in the invention include a hydroxide ion, a sulfite ion, hydroxyamines, hydroxamic acids, a metabisulfite ion, a thiosulfate ion, oximes, mercaptans, a sulfinate, a carboxylate, an ammonium compound, an amine compound, phenols, alcohols, thioureas, ureas, hydrazines, sulfides and phosphines. Of these, an alkali metal hydroxide is preferred. Timing or the rate of releasing a bromide or chloride ion can be controlled by the method of adding the nucleophilic agent or base, the concentration or the reaction temperature. The concentration of the base and/or nucleophilic agent is preferably 1×10
−7
to 50 M (molar concentration, mol/l), more preferably 1×10
−5
to 10 mol, and still more preferably 1×10
−3
to 5 mol. The temperature is preferably 20 to 90° C., more preferably 30 to 85° C., and still more preferably 35 to 80° C. In cases where a base is used for releasing a bromide or chloride ion, the pH may be controlled. The pH is preferably 7 to 12, and more preferably 8 to 11. The released bromide or chloride ion is preferably 0.001 to 30 mol % and more preferably 0.01 to 10 mol %, based on silver halide. A compound which contains a adsorption group onto silver halide and a substituent capable of releasing a halide ion, may release all or a part of halide atom(s) contained in the compound. The compound is one releasing a bromide ion or chloride ion, and preferably a bromide ion or iodide ion, and preferably a chloride ion releasing compound. The compound may be used alone or in combination.
The compound which intramolecularly contains a substituent capable of releasing a bromide or chloride ion, is preferably represented by the following formula (I):
{X—(L
1
)
n1
}
n2
—L
2
—(SOL)
m
formula (I)
wherein X represents a chlorine or bromine atom; L
1
and L
2
each represent a bivalent linkage group; SOL represents a water-solubilizing group; n1 is 0 or 1; m and n2 each are an integer of 1 to 4.
Further, L
1
of for
Kondo Toshiya
Miura Norio
Baxter Janet
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Konica Corporation
Walke Amanda C.
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