Radiation imagery chemistry: process – composition – or product th – Post imaging processing – Developing
Reexamination Certificate
2000-11-09
2002-08-13
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Post imaging processing
Developing
C430S488000
Reexamination Certificate
active
06432625
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a processing method of exposed light-sensitive black-and-white silver halide materials having silver halide grains in their light-sensitive hydrophilic layers.
BACKGROUND OF THE INVENTION
Since the early eighties practical use of light-sensitive silver halide grains or crystals has become common knowledge for anyone skilled in the art of photography. Besides cubic grains having [100] crystal faces, tabular grains having {100} or a {111} crystal habit are well-known. From Eastman Kodak's basic patents relied thereupon those related with the preparation of {111} tabular silver halide grains, sensitivity increase by spectral and chemical sensitization, and coating in a light-sensitive silver halide photographic material, more particularly in a forehardened duplitized radiographic material showing improved covering power for tabular grains having a thickness of less than 0.20 &mgr;m as described in U.S. Pat. No. 4,414,304 and in the patents corresponding therewith in Japan and in the European countries, it becomes clear that problems encountered by making use of such grains are related with image tone and developability as has also been set forth in U.S. Pat. No. 5,595,864. In radiographic applications the film materials are coated with relatively high amounts of silver, in order to provide a suitable sensitometry even if a low radiation dose is applied to the patient as is always desirable. Although the use of {111} tabular silver halide grains permits coating of lower amounts of silver, if compared e.g. with grains having a more globular shape like cubic grains as applied before practical application of said tabular grains, there remains the need to provide an acceptable image tone after development of materials having light-sensitive silver halide layers containing said tabular grains, optionally containing cubic grains.
More particularly if image tone after processing materials having silver bromide cubic grains are compared with materials having silver chloride cubic grains, it becomes clear that cubic grains rich in silver chloride provide a colder bluish-black image tone after processing than do cubic grains rich in silver bromide, showing a warmer reddish-brown image tone as has e.g. been clearly illustrated in Example 1, Table 1 in EP-A 0 794 456 and in the corresponding U.S. Pat. No. 5,712,081.
Otherwise disadvantages encountered with the use of tabular grains coated in a radiographic film material are hitherto unambiguously related indeed with the occurrence, after processing of such materials, of diagnostic images having an unacceptable reddish-brown image tone, which, for radiologists, remains undesired and unpleasant in the context of examination of diagnostic images.
Measures taken in order to get a shift in image tone from reddish-brown to the desired bluish-black color of the developed silver, well-known from the state-of-the-art, are hitherto unsatisfactory. Coating light-sensitive emulsion layers on a blue base as in U.S. Pat. No. 5,800,976 makes increase minimum density, a phenomenon which is interpreted by the radiologist as an undesired increase of “fog density”. Incorporation in the other layers of the film material of such dyes or dye precursors providing blue color directly or indirectly (by processing and oxidative coupling reactions) are e.g. known from U.S. Pat. Nos. 5,716,769 and 5,811,229 and EP-A 0 844 520, and JP-A 10-274 824 respectively and causes the same problems as set forth hereinbefore, moreover showing, in the worst cases, staining of the screens with blue dyes diffusing from the material onto the screen, with residual color of dyes due to uncomplete removal of said dyes in, nowadays desired, rapid processing steps and problems related with criticality of generation of imagewise developed blue colored silver and preservation characteristics of the material.
Other complicated solutions laying burden on reproducibility due to a rather complicated layer arrangement have been proposed e.g. in EP-A 0 770 909.
Therefore there remains a stringent demand to get a desired blue-black image tone of diagnostic images without disturbing residual color obtained after processing of the radiographic light-sensitive silver halide film material having stored the latent image of the subject to be examined.
OBJECTS OF THE INVENTION
Therefore it is an object of the present invention to provide a processing method for radiographic film materials (single-side as well as duplitized or double-side) coated in its light-sensitive layer(s) with one or more spectrally sensitized silver halide emulsion(s) in order to get a diagnostic image having a desired cold blue-black image tone.
It is a further object of the present invention to get the desired contrast in diagnostic imaging making use of (intensifying) screen-film combinations wherein single-side coated as well as double-side coated materials comprising said silver halide grains are coated, in combination with one or two screens respectively.
It is moreover a preferred object of the present invention to get a diagnostic image with an improved image tone for each processed material as obtained after exposure and processing, without the need to change anything in the layer composition and/or layer arrangement of materials having silver halide grain emulsions as set forth hereinafter in the statement of the invention.
Further objects and advantages of the present invention, which may be obtained by specific embodiments, will become apparent from the description hereinafter.
SUMMARY OF THE INVENTION
In order to reach the objects of the present invention a processing method has thus been provided for an exposed black-and-white silver halide photographic film material comprising in one or more hydrophilic light-sensitive layer(s) thereof a binder and silver halide grains being {111} or {100} tabular silver bromo(chloro)iodide or silver chloro(bromo)iodide grains having an average aspect ratio of from 1.2 to 50 and having silver iodide in an amount of less than 5 mole %, and more preferably less than 3 mole % based on silver (with at least part of it-at their grain surface), said method comprising the steps of developing in a developer, fixing in a fixer, rinsing and drying, characterized in that in said developing step the developer comprises an alkali soluble agent or compound having preventing silver dissolution properties, wherein said alkali soluble compound, as presented in the description hereinafter and in the claims, is a mercapto-azole compound having alkali soluble groups.
DETAILED DESCRIPTION OF THE INVENTION
While the present invention will hereinafter be described in connection with preferred embodiments thereof, it will be understood that it is not intended to limit the invention to those embodiments.
The above mentioned objects are thus realized by providing a method of processing of a light-sensitive black-and-white silver halide photographic material containing emulsion grains having a silver iodide content of less than 3 mole %, and even more preferred of less than 1 mole % based on silver, with at least part of said silver iodide at their grain surface, wherein said method comprises the steps of developing, fixing, rinsing and drying, wherein during said processing said developer comprises, besides one or more developing agent(s), one or more agent(s) preventing oxidation thereof and agent(s) providing pH buffering in running equilibrium conditions during said processing, at least one alkali soluble agent or compound preventing silver dissolution, according to the general formula (I)
wherein said agent stands for a mercapto azole compound, having at least one alkali soluble group, selected from the group consisting of carboxylic acid, sulphonic acid and phosphonic acid, wherein Z represents an atom capable of closing a 5- or 6-membered ring, differing from a thiadiazole ring, and wherein M is selected from the group consisting of a group providing a thiolate anion under a
De Baecke Govert Wim
Elst Kathy Gaby
Hendrickx Freddy
Loccufier Johan August
Roefs André Cornelius
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