Radiation imagery chemistry: process – composition – or product th – Silver halide colloid tanning process – composition – or product
Reexamination Certificate
2002-01-07
2003-06-03
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Silver halide colloid tanning process, composition, or product
C430S265000, C430S598000
Reexamination Certificate
active
06573021
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to high contrast photographic silver halide materials containing a combination of hydrazide nucleating agents and in particular to those materials of the graphic arts type.
BACKGROUND OF THE INVENTION
In the field of graphic arts, an ultrahigh contrast photographic material is 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 image formation system providing ultrahigh contrast where the gamma (contrast) exceeds 10 has been provided conventionally in a material wherein silver halide bearing a surface latent image is developed in the presence of a hydrazine (also known as a nucleating agent), specifically an acylhydrazine, which 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, typically 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 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 the developer is exhausted or through the course of time, for example as the pH of the developer varies and in particular as the pH is lowered. The pH of the developer can vary for a number of reasons: for example, exhaustion and absorption of carbon dioxide causes 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 and give rise to process unevenness or variability during the processing run. There is an overall effect that shows up as a change to the developer component levels in solution but there is also a local effect that 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 EP-A-0 333435. A nucleator containing both a hydrazide moiety and a nicotinamide moiety is disclosed in U.S. Pat. No. 5,288,590. However the use of these nucleating agents does not entirely remove sensitivity to both bromide and pH.
A nucleating agent which 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 EP-A-1 008 902. A nucleating agent comprising (a) two nicotinamide moieties, which may be the same or different, which 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 EP Patent application No. 01201989.9. U.S. Pat. Nos. 4,988,604 and 4,994,365 describe aryl sulfonamidophenyl hydrazide nucleating agents that are capable of high contrast development.
Developer solutions with these low pHs 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, 4,975,354 or EP-A-0 364166. Compounds bearing different functionalities e.g. phosphonium and pyridinium, have also been shown to be active, as described in U.S. Pat. No. 5,744,279.
The design of nucleators and boosters is continuing to develop by varying their structures to fine tune the performance of the system and to enhance image quality and process stability during the running of a process. U.S. Pat. No. 5,328,801 describes the use of an inhibitor releasing redox compound suitable for nucleated systems. The problems associated with processing unevenness are described in U.S. Pat. No. 5,882,841.
PROBLEM TO BE SOLVED BY THE INVENTION
The problem is therefore to provide nucleators for incorporation into a photographic material which has improved processing evenness through a reduced sensitivity to variations in the developer pH and bromide level which occur in the film during development and which exhibits greater tolerance to a wider range of developers.
It has been found that these objectives can be achieved by the use of a combination of nucleating agent(s) of formulae (I) and/or (II) with a nucleating agent of formula (III), in which the nucleating agent of formula (I) comprises (a) two nicotinamide moieties, which may be the same or different, which are linked by a linking group, and (b) a hydrazide moiety linked to only one of those nicotinamide moieties; the nucleating agent of formula (II) 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 moiety and a nicotinamide moiety; and the nucleating agent of formula (III) comprises an aryl sulfonamido aryl hydrazide.
Such a combination of nucleating agents can lead to high contrast nucleation providing excellent processing evenness in a developer whose pH is variable and can give greater tolerance to a wide range of developer solutions.
SUMMARY OF THE INVENTION
According to the present invention therefore there is provided an ultrahigh contrast photographic material comprising a support bearing a silver halide emulsion layer, containing a combination of two or more hydrazide nucleating agents in the emulsion layer and/or a hydrophilic colloid layer, characterised in that the combination comprises a nucleating agent(s) of formulae (I) and/or (II) with a nucleator of formula (III), in which the nucleating agent of formula (J) comprises (a) two nicotinamide moieties, which may be the same or different, which are linked by a linking group, and (b) a hydrazide moiety linked to only one of those nicotinamide moieties; the nucleating agent of formula (II) 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 moiety and a nicotinamide moiety; and the nucleating agent of formula (III) comprises an aryl sulfonamido aryl hydrazide.
In another aspect of the invention there is provided an ultrahigh contrast photographic material, as hereinbefore defined, which also contains in the emulsion layer or a hydrophilic colloid layer, a booster compound, as hereinafter defined.
In yet another aspect of the invention there is provided a process of forming a photographic image having ultrahigh
Baker Julie
Barford Ian
Coldrick Philip J.
Jenkins Dawn J.
Piggin Roger H.
Eastman Kodak Company
Kluegel Arthur E.
Schilling Richard L.
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