Radiation imagery chemistry: process – composition – or product th – Silver halide colloid tanning process – composition – or product – Process using lithographic infectious developer
Reexamination Certificate
2003-06-19
2004-09-14
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Silver halide colloid tanning process, composition, or product
Process using lithographic infectious developer
C430S264000, C430S267000, C430S436000, C430S440000, C430S441000
Reexamination Certificate
active
06790585
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for developing an exposed high contrast photographic silver halide material, said photographic material comprising a support bearing at least one silver halide emulsion layer, containing at least one hydrazide nucleating agent in said emulsion layer and/or in a hydrophilic colloid layer.
BACKGROUND OF THE INVENTION
In the field of graphic arts, ultrahigh contrast photographic materials are required for achieving satisfactory halftone dot reproduction of a continuous tone or reproduction of a line image in the process of making a lithographic printing plate.
For many years, these ultrahigh contrast photographic images were obtained by developing a “lith” emulsion (usually high in silver chloride content) in a hydroquinone, low sulphite, “lith” developer by the process known as infectious development.
However, such low sulphite developers are inherently unstable and are particularly inappropriate for machine processing.
More recently, an imaging formation system providing ultrahigh contrast, where the gamma (contrast) exceeds 10 has been provided conventionally in a material wherein silver halides bearing a surface latent image are developed in the presence of a hydrazine (also known as a nucleating agent), specifically an acylhydrazine, that can be incorporated into the photographic material or into the developer. The pH of the developer solution is usually in the range 10.0 to 12.3, about 11.5, and the developer includes conventional amounts of sulphite, hydroquinone and possibly Metol® or a pyrazolidone.
While such a process is better than the low sulphite “lith” process, the developer still has a high pH requirement for it to function correctly. Such a developer solution is not as stable as is desirable. Additionally, high pH solutions are environmentally undesirable because of the care needed in handling and disposing of the effluent.
Unfortunately, light sensitive materials whose contrast is enhanced by the presence of a hydrazine nucleating agent show large variations in their photographic properties as, for example, the developer is exhausted or as the developer pH value varies in time, and in particular, reduces. The pH of the developer can vary for a number of reasons: for example, exhaustion and absorption of carbon dioxide cause the pH to drop whilst air oxidation causes the pH to rise, as can concentration through evaporation.
Also during development of silver halide materials, particularly those which use chlorobromide emulsions, there is a release of bromide locally into area of the development as a consequence of the development process to convert silver halide to elemental silver. Both of these effects can influence the development rate of the film give rise to process unevenness or variability during the processing run.
There is an overall effect which shows up as a change to the developer component levels in solution, but there is also a local effect which occurs within the developing layer and is exposure dependent. These effects can also depend on the formulation of the developer used and overcoming these problems can increase tolerance to a wider range of developer formulations.
It is also known that a developer solution having a pH below 11 can be employed by using certain hydrazides active at this pH. Hydrazides proposed for such use are described, for example, in U.S. Pat. Nos. 4,278,748; 4,031,127; 4,030,925; 4,323,643; 4,988,604 and 4,994,365 and in European Patent Application EP-A-0 333 435. A nucleating agent containing both a hydrazide moiety and a nicotinamide moiety is disclosed in U.S. Pat. No. 5,288,590. However the use of such a nucleating agent does not entirely remove sensitivity to both bromides and pH.
A nucleating agent that comprises a dimeric molecule comprising two monomers linked by a linking group, each monomer of which (a) may be the same or different and (b) comprises a hydrazide and a nicotinamide moiety, has been disclosed in U.S. Pat. No. 6,228,566. A nucleating agent comprising (a) two nicotinamide moieties, that may be the same or different, that are linked by a linking group, and (b) a hydrazide moiety linked to only one of those nicotinamide moieties, either alone or together with the nucleating agent comprising the dimeric molecule, has been described in U.S. Pat. No. 6,245,480. A nucleating agent as described in either of these two U.S. Patents in combination with a “conventional” aryl sulfonamido aryl hydrazide is described in European Patent Application EP-A-1 229 383. U.S. Pat. Nos. 4,988,604 and 4,994,365 describe aryl sulfonamidophenyl hydrazide nucleating agents which are capable of high contrast development.
Developer solutions with pHs below 11 can also be used by the introduction of a contrast-promoting agent (commonly called a booster) to give adequate activity. The booster can be incorporated into the photographic layer or may be dissolved in the developer solution. The booster may be, for example, one of the boosters as described in U.S. Pat. No. 5,316,889 or an amine booster as described in U.S. Pat. Nos. 4,269,929; 4,668,605, 4,740,452 or in European Patent Application EP-A-0 364 166. Compounds bearing different functionalities, for example phosphonium and pyridinium, have also been shown to be active, as described in U.S. Pat. No. 5,744,279.
In the non-imaged areas on the processed film unwanted small dots can appear and this is called “pepper fog”. This is due to unintentionally fogged grains developing and being amplified by the nucleation process and being rendered visible. Nucleating agents which are unstable or more active and diffuse more rapidly can result in more and larger pepper fog spots. In high contrast materials therefore a balance needs to be achieved between vigorous development and pepper fog.
Another factor to be considered is the chemical spread (or image spread) which is a measure of the increase in size of developed dots or lines produced by nucleation of the edge of the image area causing development of the image boundary beyond the original exposed edge. This spread is small but measurable and can reduce the resolution of very fine lines.
A further consideration is the efficiency of synthesis of the nucleating agents and the robustness of the chemical processes used for their synthesis. It is desirable that the nucleating agents and their intermediates are formed rapidly and efficiently at all stages of the synthesis since heating and/or prolonged reaction times can have an adverse effect on their purity.
Furthermore, while it may be desirable from the costs point of view to prepare a mixture of nucleating agents (as in U.S. Pat. No. 6,245,480) without the need for purification or separation of the nucleating agents, for regulatory purposes it is mandatory to provide a mixture wherein the proportions of components are within defined limits. When a chemical reaction produces a mixture of nucleating agents and impurities, it is not always possible to ensure that the various components will be within the defined limits and thus the process, although cost effective when successful, is less robust and consistent than desired.
SUMMARY OF THE INVENTION
The present invention is a method for developing an exposed high contrast photographic material, said photographic material comprising a support bearing at least one silver halide emulsion layer, containing at least one hydrazide nucleating agent, characterized in that
a) said nucleating agent has the formula (I):
wherein
each A
1
and each A
2
is independently selected from the class consisting of a hydrogen atom, or a substituted or unsubstituted acyl group, and an alkyl- or aryl-sulfonyl group;
each Y is independently selected from a substituted or unsubstituted aryl or heterocyclic ring or ring system;
each X is independently selected from S═O, C, C—NH and C—O;
each L′ is independently selected from a substituted or unsubstituted alkylene group; or a substituted or unsubstituted aryl or heterocyclic ring or ring system linked to Z via a substituted or unsubstitute
Goddard John D.
Leyshon Llewellyn J.
Roussilhe Jacques
Tsoi Siu C.
Eastman Kodak Company
Hawley J. Jeffrey
Le Hoa Van
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