Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
1999-11-01
2002-06-11
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S569000, C430S600000, C430S604000, C430S605000
Reexamination Certificate
active
06403294
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a silver halide photographic material and, more particularly, to a high speed silver halide photographic material utilizing the technique of dopants.
BACKGROUND OF THE INVENTION
As one of the techniques of modifying silver halide grains to bring about as much improvement as is expected in the properties of a silver halide photographic material as a whole, there is known a technique of incorporating a substance (dopant) other than silver and halide ions into silver halide grains. This technique is referred to as “a doping technique”. In particular, many researches on the techniques of doping transition metal ions have been made. As a result, it is generally recognized that the transition metal ions incorporated as a dopant into silver halide grains can effectively modify photographic properties even when the amount thereof is minute.
Besides the technique of doping transition metal ions, there is known the technique of doping silver halide grains with transition metal complexes having cyanide ions as ligands to heighten the sensitivity of silver halide emulsions. In particular, many disclosures have been made about the emulsions having sensitivities increased by doping with the group VIII metal complexes containing 6 cyanide ions as ligands. As the dopants containing cyanide ions, for instance, a hexacyanoferrate (II) complex and a hexacyanoferrate(III) complex are disclosed in JP-B-48-35373 (the term“JP-B” as used herein means an “examined Japanese patent publication”). However, the invention cited above regards the sensitivity increasing effect as being limited to the cases of complex salts containing iron ion and having no relation to the species of ligands. Many other cases are known where high sensitivity can be conferred on emulsions by doping them with hexacyanoferrate(II) complexes. Such cases are disclosed, e.g., in JP-A-5-66511 (the term “JP-A” as used herein means an “unexamined published Japanese application”) and U.S. Pat. No. 5,132,203. There are also known the emulsions which are doped with cyano-complexes of metals other than iron to obtain high sensitivity. For instance, JP-A-2-20853 discloses that silver halide emulsions can acquire high sensitivity by comprising silver iodochloride doped with a rhenium, ruthenium, osmium or iridium complex. Many of other metal ion complexes are also used as dopant, and can produce not only the sensitivity increasing effect but also various effects, such as an improvement in reciprocity failure and an increase in contrast. For instance, U.S. Pat. No. 2,448,060 discloses the emulsions sensitized by doping them with a platinum or palladium(III) complex having halogen ions as ligands. And U.S. Pat. No. 3,790,390 discloses the emulsions doped with cyano-cobalt (III) complexes in addition to the emulsions doped with cyano-iron(II) or cyano-iron(III) complexes, wherein spectral sensitizing dyes are also contained. Further, the silver halide grains formed in the presence of a rhodium(III) complex containing 3, 4, 5 or 6 cyanide ions as ligands are disclosed in U.S. Pat. No. 4,847,191. Those patent prove that the high intensity failure can be diminished by dopants. In European Patents 0335425 and 0336426 and JP-A-2-20854 are disclosed the silver halide emulsions doped with rhenium, ruthenium, osmium or iridium complexes having at least 4 cyano-ligands. Therein, it is described that the doped emulsions are improved in storage stabilities of sensitivity and gradation and reduced in low intensity failure. European Patent 0336427 and JP-A-2-20852 disclose the silver halide emulsions respectively using vanadium, chromium, manganese, iron, ruthenium, osmium, rhenium and iridium complexes having the coordination number of 6 and containing nitrosyl or thionitrosyl ligands, wherein the low intensity reciprocity failure is improved without attended by lowering of medium illumination sensitivity. As the dopants other than transition metal ions, the emulsions doped with bismuth or lead ions are disclosed in U.S. Pat. No. 3,690,888, and the emulsions containing the group XIII or XIV metal ions are disclosed in JP-A-7-128778.
With respect to the ligands of complexes used as dopant, the cyanide ions are regarded as most popular, but halide ions are also used frequently. As examples of a dopant having the structure of [MCl
6
]
n−
wherein M is a metal, mention may be made of the hexachlororuthenium, hexachloroiridium and hexachlororhenium complexes disclosed, e.g., in JP-A-63-184740, JP-A-1-285941, JP-A-2-20852 and JP-A-2-20855. Further, the six-coordinated rhenium complexes having halogeno, nitrosyl, thionitrosyl, cyano, aquo or/and thiocyano ligands are disclosed as dopants in European Patent 0336689 and JP-A-2-20855. In addition, the emulsion containing a six-coordinated transition metal complex having one carbonyl ligand and the emulsion containing a six-coordinated transition metal complex having two oxo ligands are disclosed as those having useful photographic properties in JP-A-3-118535 and JP-A-3-118536 respectively. Furthermore, the cases of using as dopant the complexes containing heterocyclic compounds as ligands are disclosed in U.S. Pat. Nos. 5,360,712, 5,457,021 and 5,462,849, European Patent 0709724, JP-A-7-72569 and JP-A-8-179452.
However, the complexes used as dopant in U.S. Pat. No. 5,360,712 require that at least half of the coordination sites of the central metal ion be occupied with halogen or pseudo-halogen ions. On the other hand, the cases of using as dopant the complexes wherein neither halogen nor pseudo-halogen ions are bound to the coordination sites of their respective metal ions, such as [Fe(EDTA)]
2−
(wherein EDTA represents ethylene-diaminetetraacetic acid) and [Ir(C
2
O
4
)
3
]
3−
, are disclosed in U.S. Pat. No. 3,672,901, JP-A-2-259749 and JP-A-4-336537. However, U.S. Pat. No. 5,360,712 cited above describes that those complexes are not effective as dopants. In addition, the technique of including groups capable of adsorbing to silver halide grains in the organic compounds used as ligands is disclosed in JP-A-11-102042. No cases but the above-recited ones are yet known where the complexes having neither halogen nor pseudo-halogen ions bound to their coordination sites are used as dopants.
In order that the emulsions acquire high speed, they are required to undergo chemical sensitization besides the addition of dopants. In the case where the emulsion doped with a cyano-complex is subjected to gold sensitization as typical of chemical sensitization, as described, e.g., in JP-A-8-62761, the cyanide ions liberated from the complex are adsorbed to the silver halide grain surface and form a cyano-gold complex together with the gold ion added as a gold sensitizer, thereby inhibiting the formation of sensitized center by the gold sensitizer. In order to effect gold sensitization of the emulsion containing a cyano-complex as dopant, it is required to keep the cyano groups away from the silver halide grain surface, e.g., by making the cyano-complex dope the sub-surface of silver halide grains as described in U.S. Pat. No. 5,132,203 and European Patent 0508910. As another preventive against the inhibition of gold sensitization, there is known the method of adding zinc ion or the like as disclosed in JP-A-6-308653. As mentioned above, a further measure must be taken in order to achieve both an increase of photographic speed by the dopant and gold sensitization.
Most of the dopants hitherto known to enable the increase of photographic speed are cyano-complexes. These cyano-complexes still have a toxicity problem common to cyan compounds even if their problem of inhibiting gold sensitization can be overcome. Therefore, new dopants containing no cyanide ions and capable of imparting high speed to emulsions have been awaited.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a silver halide photographic material containing no cyanide ions but having a higher photographic speed than ever.
The foregoing ob
Fuji Photo Film Co. , Ltd.
Schilling Richard L.
Sughrue & Mion, PLLC
Walke Amanda C.
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