Toning agents for use in substantially light-insensitive recording materials

Abstract

A black and white monosheet substantially light-insensitive thermographic recording material comprising a support and a thermosensitive element, the thermosensitive element containing a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal working relationship therewith, a binder and at least one toning agent, wherein the at least one toning agent is selected from compounds represented by formula (I):wherein Ris an alkyl group optionally substituted with a hydroxy, carboxy, carboxy ester, acyl or carbonato group; X is S, O or N—R; Ris an optionally substituted alkyl group; R, R, Rand Rindependently represent a hydrogen atom, a halogen atom or an alkyl, an alkoxy, a thio-alkoxy, a nitro, a cyano, a carboxy, a carboxy ester, an acyl, an aldehyde, an acylamido, a sulphonamido, an acylamino, a carbonato, a hydroxy or an aryl group or at least one of Rand R, Rand Rand Rand Rindependently represent the atoms necessary to form a carbocyclic or heterocyclic group or at least one of Rand Rand Rand Rindependently represent the atoms necessary to form a heterocyclic ring; and compounds represented by formula (II):wherein Ris an optionally substituted alkyl group; Y is S, O or N—R; Ris an optionally substituted alkyl group; Rand Rindependently represent a hydrogen atom, a halogen atom or an alkyl, an alkoxy, a thio-alkoxy, a nitro, a cyano, a carboxy, a carboxy ester, an acyl, an aldehyde, an acylamido, a sulphonamido, an acylamino, a carbonato, a hydroxy or an aryl group or Rand Rrepresent the atoms necessary to form a heterocyclic or a non-aromatic carbocyclic ring or at least one of Rand Rand Rand Rindependently represent the atoms necessary to form a heterocyclic ring; and both Rand Rcannot both be an alkyl group.