Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Two or more radiation-sensitive layers containing other than...
Reexamination Certificate
2000-11-14
2002-01-29
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Two or more radiation-sensitive layers containing other than...
C430S139000, C430S368000, C430S523000, C430S539000, C430S564000, C430S567000, C430S965000, C430S966000, C430S967000
Reexamination Certificate
active
06342338
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a black-and-white light-sensitive silver halide photographic film material, particularly suitable for use in radiography and a combination of one or two intensifying luminescent phosphor screen(s) and said film material comprising in the light-sensitive emulsion layers hexagonal {111} tabular emulsion grains.
BACKGROUND OF THE INVENTION
Since the early eighties practical use of light-sensitive tabular silver halide grains or crystals has become common knowledge for anyone skilled in the art of photography. 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 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. Reduction of thickness of the {111} tabular grains coated in a radiographic film material hitherto, although providing a higher covering power, remains unambiguously related indeed with the occurrence, after processing of such materials, of diagnostic images having an unacceptable reddish-brown image tone for radiologists as image tone and image quality are closely related with each other in the specific context of examination of diagnostic images. Providing tabular grains having a thickness of more than 0.20 &mgr;m, e.g. in the range from 0.21-0.23 &mgr;m, the preparation method of which has been described in EP-A 0 569 075 and in the corresponding U.S. Pat. No. 5,595,864, ensures a better image tone but this is at the cost of covering power as may be expected.
Measures taken in order to get a shift in image tone for whatever a grain thickness from reddish-brown to the desired bluish-black color of the developed silver, combined with a good covering power, 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 and problems related with criticality of generation of imagewise developed blue colored silver and preservation characteristics of the material.
It has however, untill now, been impossible to traverse the normally expected existing relationship between improved covering power and worse image tone.
OBJECTS OF THE INVENTION
It is a first object of the present invention to change the existing relationship between covering power and image tone as set forth hereinbefore, thus providing an increased covering power and an increased image tone independent from grain thickness.
It is a second object of the present invention to avoid negative influences on development kinetics, i.a. developability due e.g. to the presence of chemical compounds inhibiting development to an unacceptable extent when present in the layers of the photographic material.
It is a further object of the present invention to avoid negative influences on preservation characteristics for the material.
It is still a further object of the present invention to prevent loss in sensitometric characteristics, especially speed and gradation.
Further objects will become apparent from the description hereinafter.
SUMMARY OF THE INVENTION
Therefore a black-and-white silver halide photographic film material (especially for use in radiography) has been provided, wherein said material comprises a transparent film support having first and second major surfaces coated with a subbing layer, further coated adjacent thereto on one side (for a single-side coated material) or on both sides (for a duplitized material) of said film support, optionally in contact with a hydrophilic undercoat layer and overcoated with a protective antistress layer, a light-sensitive silver halide emulsion layer having chemically and spectrally sensitized {111} tabular hexagonal grains, accounting for at least 50%, more preferably at least 70% and still more preferably at least 90% of the total projective surface of all grains, with a mean equivalent volume diameter of from 0.3 &mgr;m up to 1.0 &mgr;m and an average grain thickness of less than 0.30 &mgr;m, wherein said film material is coated with a total amount of silver, expressed as an equivalent amount of silver nitrate of less than 7 g/m2, characterized in that said protective antistress layer(s) and/or said hydrophilic undercoat layer comprise(s) a compound according to general formula (I) in an amount of at least 0.5 mmole, more preferably, at least 1 mmole and up to 5 mmole per mole of coated silver halide. Said formula (I) and other formulae related with more specifically preferred compounds have been given hereinafter in the detailed description and in the claims.
DETAILED DESCRIPTION OF THE INVENTION
A silver halide photographic film material (especially for use in radiography) has thus been provided, wherein said material comprises a transparent film support having first and second major surfaces coated on each of the major surfaces of the support, with a light-sensitive emulsion layer having {111} tabular hexagonal silver halide emulsions, wherein said layer is overcoated with a protective antistress layer at one or both sides of the film support, leading to a single-side coated or double-side coated (duplitized) material.
Optionally the light-sensitive layer(s) is (are) in contact with a hydrophilic undercoat layer, e.g. a hydrophilic layer containing antihalation dyes and therefore called a “antihalation undercoat”.
It is an essential feature of the present invention to add to that (those) protective antistress layer(s) and/or said optionally present hydrophilic undercoat layer(s), besides the normally added components as illustrated in the Examples hereinafter, a compound according to the general formula (I) in an amount of at least 0.5 mmole per mole of coated silver halide, wherein said formula (I) is represented hereinafter:
wherein
A″ represents a (straight or branched) divalent linking moiety selected from the group consisting of unsubsituted or substituted arylene, heteroarylene, alkylene, alkenylene and alkynylene chain, wherein each of said arylene, heteroarylene, alkylene, alkenylene and alkynylene chain optionally contains heteroatoms, aliphatic or aromatic rings, and alkali soluble groups;
X1 represents atoms necessary to form a five-or six-membered aromatic or heterocyclic ring;
and wherein A′ is represented by a functional group.
Typical examples of compounds satisfying the structure as given in
De Baecke Govert Wim
Henderickx Freddy
Loccufier Johan August
Verbeeck Ann
Agfa-Gevaert
Breiner & Breiner L.L.C.
Schilling Richard L.
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