Process to make ultrahigh contrast images
AssigneeAgfa-Gevaert
InventorReinhold Rüger
Life of this patent
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Abstract
A process to make ultrahigh contrast photographic negative images is disclosed. In known processes, particularly those using hydrazine compounds, developer solutions to increase contrast contain high concentrations of amino compounds that are volatile, have an annoying, unwholesome odor, and corrode the development machines. If development is conducted in the presence of onium compounds having both quaternary nitrogen and tertiary amine functions in the molecule, the process can operate with odor-free developers that do not release corrosive vapors. The invention can be used in reprography for steps preliminary to printing.
Claims10
A process to make ultrahigh contrast photographic negative images by developing in the presence of an onium compound a photosensitive recording material having at least one layer with a silver halide emulsion, characterized in that the onium compound comprises a cation having generic formulas (I), (II), (III)
- O+—X—NR1R2 (I)
- R1R2N—X—O+—Y—NR3R4 (II)
- R1R2N—X—O+—A—O1+—NR3R4 (III)
- wherein O+, O1+ are the same or different, selected from the group consisting of guaternary ammonium and iminium;
- X, Y, A are the same or different, selected from the group consisting of alkylene, hydroxyalkylene, alkylene oxyalkylene, alkylenethioalkylene, alkyleneaminoalkylene, and hydroxyalkyleneoxyalkylene, and a polyoxyalkylene chain and wherein Y is also selected from the group consisting of a single bond, an oxyalkylene, thioalkylene, and amino alkylene group if it links to a carbon atom of an imidazolium, thiazolium, or pyridinium group;
- R1R2R3R4 are the same or different, selected from the group consisting of an alkyl, alkoxy, alkylaryl, and phenyl, each of which may be unsubstituted or substituted, with R1 and R2 as well as R3 and R4 also being capable of forming a ring;
- and at least one anion required to balance the charge.
Dependencies are inferred from the claim text.