Thermographic recording materials with improved image tone
摘要:
A substantially light-insensitive black and white thermographic recording material comprising a thermosensitive element and a support, the thermosensitive element containing at least one substantially light-insensitive organic silver salt, at least one organic reducing agent therefor in thermal working relationship therewith, a binder, at least one stabilizer and optionally an &agr;,(&ohgr;-alkyldicarboxylic acid with a straight chain alkyl group having at least 4 carbon atoms which may be substituted, however neither including 3,5-dihydroxybenzoic acid as acidic reagent nor di-tert-butyl-p-cresol as a sole organic reducing agent, wherein the at least one stabilizer is represented by formula (I): R1—(O═C)—R2—(C═O)—R3  (I) wherein R2 is a divalent straight chain saturated hydrocarbon group with 2 or 3 carbon atoms which may be substituted with one or more of ═O, ═S, ═CR4R5, an alkyl group, a cycloalkyl group, a hydroxy group, a thiol group, a —(C═O)R6 group or two of the substituents of R2 may together form a closed non-aromatic carbocyclic or heterocyclic ring; R4 and R5 are independently hydrogen or an alkyl, hydroxy, thiol, —(C═O) R7 group or R4 and R5 together may form a closed carbocyclic or heterocyclic group; R1, R3, R6 and R7 are independently a hydroxy or —NHR8 group or R1 and R3 together is an oxygen atom forming an anhydride group; R8 is hydrogen or a hydroxy, alkyl, aryl or —SO2R9 group; R9 is an alkyl, cycloalkyl, heterocyclic, aryl, heteroaryl, an —OR10, or a —NR11R12 group; R10 and R1 are independently an alkyl, cycloalkyl, or aryl group; R12 is hydrogen or an alkyl, cycloalkyl or aryl group; and R11 and R12 may together form a closed carbocyclic or heterocyclic group; and wherein the concentration of the at least one stablizer and the (&agr;,&ohgr;-alkyldicarboxylic acid, if present, is together at least 20 mol % with respect to the organic silver salts; and a recording process therefor.
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