Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-03-09
2004-01-13
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S569000, C430S618000, C430S620000
Reexamination Certificate
active
06677111
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to silver halide emulsion, a production process thereof, and a silver halide photographic light-sensitive material and a photothermographic material each having a layer comprising the emulsion.
BACKGROUND OF THE INVENTION
Silver halide as a photosensitive element of photographic light-sensitive materials can be formed to have a grain size of 0.01 &mgr;m or more by appropriately designing the preparation process in a photographic gelatin. However, silver halide grains having a grain size of from 0.005 to 0.1 &mgr;m undergo physical ripening with the passing of time, where small grains dissolve to grow into large grains. As a result, the grain size disadvantageously becomes large.
In order to prevent the growing of silver halide grains into large grains, a stabilizer for stabilizing the photographic performance, such as tetrazaindenes and mercaptothiazoles, has been conventionally used. However, if the stabilizer is added in an amount large enough to fix the grain size, a spectral sensitizing dye does not adsorb to the grain surface and a photographic light-sensitive material using the emulsion cannot have a desired sensitivity. Thus, it has been difficult to attain results in both the grain size and the photographic performance. In particular, silver chloride fine grain has high solubility and the physical ripening thereof is hard to prevent. If the grain size of this silver halide fine grain can be maintained, various advantages can be provided, for example, the storability of emulsion can be increased or a large number of grains can be obtained with the same silver amount.
These advantages can be applied to photothermographic materials. In the photothermographic material, the silver halide grain works as a photosensitive element and by forming the silver halide grains as fine grains, the silver amount can be reduced and thereby the storability can be improved. The photothermographic material is described below.
In the medical diagnosis field, reduction in the amount of processing waste solution is keenly demanded in recent years from the viewpoint of environmental conservation and space savings. To cope with this demand, technology is required relating to photothermographic materials for use in medical diagnosis or graphic art or other photographic use, which can be effectively exposed by a laser image setter or a laser imager and can form a sharp black image having high resolution and sharpness. These photothermographic materials can dispense with processing chemicals of solution system and afford users a more simple heat-developing system which does not impair the environment.
The same is also demanded in the field of general image-forming materials, however, the image for medical diagnosis use must be finely drawn, therefore, must have a high image quality with good sharpness and excellent graininess. Furthermore, in view of diagnostic convenience, an image of blue black image tone is preferred. At the present, various hard copy systems using a pigment or a dye are commercially available, such as ink jet printer and electrophotography, however, these are not a satisfactory output system for the image in medical use.
On the other hand, (photo)thermographic systems using a silver salt of an organic acid are described, for example, in U.S. Pat. Nos 3,152,904 and 3,457,075, D. Klosterboer,
Thermally Processed Silver Systems
, and J. Sturge, V. Walworth and A. Shepp (compilers),
Imaging Processes and Materials
, 8th ed., chapter 9th, page 279, Neblette (1989). In particular, photothermographic materials generally have a light-sensitive layer comprising a binder matrix having dispersed therein a catalytic amount of a photocatalyst (for example, silver halide), a reducing agent, a reducible silver salt (for example, a silver salt of an organic acid) and if desired, a toner for controlling the silver tone. The photothermographic material after image exposure is heated at a high temperature (for example, 80° C. or more) to cause an oxidation-reduction reaction between the silver halide or reducible silver salt (acting as an oxidizing agent) and the reducing agent and thereby form a black silver image. The oxidation-reduction reaction is accelerated by the catalytic action of a silver halide latent image produced by the exposure. Therefore, the black silver image is formed in the exposed area. This is disclosed in a large number of publications including U.S. Pat. No. 2,910,377 and JP-B-43-4924 (the term “JP-B” as used herein means an “examined Japanese patent publication”) The (photo) thermographic system using a silver salt of an organic acid can provide an image satisfied in the image quality and the tone for medical diagnosis uses.
Silver halide emulsions produced by adding a hexacyano metal complex during or after the formation of silver halide grains are described in
Research Disclosure
, Vol. 176, No. 17643, Item IA (1978) and Vol. 367, Item 36736 (1994), JP-A-2-20853 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) and JP-A-2-20854. In these publications, a technique of incorporating (doping) a hexacyano metal complex into the inside of a silver halide grain. However, these silver halide emulsions are not yet satisfied in the sensitivity and the storability and still in need of improvements.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a silver halide grain emulsion having a small grain size.
Another object of the present invention is to provide a silver halide photographic light-sensitive material having high sensitivity and excellent image preservability against light.
A still another object of the present invention is photothermographic material having high sensitivity and excellent image preservability against light.
The above-described objects can be attained by the following means.
(1) A silver halide emulsion comprising at least a dispersion medium and silver halide grains, wherein the silver halide grains have an average grain size of from 0.005 to 0.1 &mgr;m and a hexacyano metal complex represented by formula (I) is present on the outermost surface of the silver halide grain:
[M(CN)
6
]
n−
(I)
wherein M represents Fe, Ru, Os, Co, Rh, Ir, Cr or Re, and n represents 3 or 4.
(2) The silver halide emulsion as described in (1) above, wherein the silver halide grain contains in the inside thereof a coordination metal complex or metal ion containing a metal belonging to the elements of Group III to Group XIV of the Periodic Table.
(3) The silver halide emulsion as described in (2) above, wherein the coordination metal complex contained in the inside of the silver halide grain is a compound represented by formula (III):
[M1(CN)
6
]
n1−
(III)
wherein M1 represents Fe, Ru, Os, Co, Rh, Ir, Cr or Re, and n1 represents 3 or 4.
(4) The silver halide emulsion as described in (2) or (3) above, wherein the coordination metal complex contained in the inside of the silver halide grain is an iridium complex.
(5) The silver halide emulsion as described in any one of (1) to (4) above, wherein the silver halide emulsion is chalcogen sensitized.
(6) The silver halide emulsion as described in any one of (1) to (5) above, wherein the silver halide grains are formed in the presence of an oxidizing agent for silver.
(7) The silver halide emulsion as described in any one of (1) to (6) above, wherein the silver halide emulsion is chemically sensitized in the presence of a spectral sensitizing dye.
(8) A method for producing a silver halide emulsion comprising silver halide grains having an average grain size of from 0.005 to 0.1 &mgr;m, wherein a hexacyano metal complex represented by the following formula (I) is added after the addition of an aqueous silver nitrate solution used for the grain formation is completed but before starting the chemical sensitization process:
[M(CN)
6
]
n−
(I)
wherein M represents Fe, Ru, Os, Co, Rh, Ir, Cr or Re, and n represents 3 or 4.
(9) A silver hali
Baxter Janet
Birch Stewart Kolasch & Birch
Walke Amanda C.
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