Patent ID: 6337303
Filing Date: 2002-01-08
Classification: G03C

Abstract:
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 said at least one stabilizer is represented by formula (I):R1â€”(O&boxH;C)â€”R2â€”(C&boxH;O)â€”R3â€ƒâ€ƒ(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 &boxH;O, &boxH;S, &boxH;CR4R5, an alkyl group, a cycloalkyl group, a hydroxy group, a thiol group, a â€”(C&boxH;O)R6 group or two of said 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, â€”(C&boxH;O)R7 group or R4 and R5 together may form a closed carbocyclic or heterocyclic group; R1 and R3 are a hydroxy group or together form an oxygen atom of an anhydride group; R6 and R7 are independently a hydroxy or â€”NHR8 group ; R8 is hydrogen or a hydroxy, alkyl, aryl or â€”SO2R9 group; R9 is an alkyl, cycloalkyl, heterocyclic, aryl, heteroaryl, an â€”OR10, or a â€”NR11R12 group; R10 and R11 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 said at least one stablizer and said &agr;,&ohgr;-alkyldicarboxylic acid, if present, is together at least 20 mol % with respect to said organic silver salts.