Thermographic recording process

Abstract

A recording process, wherein an organic reducing compound being present in a supported or self-supporting layer and corresponding to one of the following general formulae (I) and (II): ##STR1## wherein: R 1 represents hydrogen, an aliphatic group of a cycloaliphatic group, and R 2 represents an aliphatic oxy group, a cycloaliphatic oxy group, an aryloxy group, an amino group of the formula ##STR2## in which R 3 and R 4 (same or different) represent hydrogen, an aliphatic, a cycloaliphatic or an aromatic group or R 3 and R 4 represent together the necessary atoms to close a heterocyclic nitrogen containing nucleus; ##STR3## wherein R 5 represents an aliphatic, cycloaliphatic, aromatic or heterocyclic group, is caused to effect in said layer under the influence of information-wise heating an information-wise reduction of a reducible reaction partner.

We claim: 
     
       1. A recording process, which comprises exposing to a heat pattern a support carrying an organic reducing compound corresponding to one of the following general formulae: ##STR23## wherein: R 1  represents hydrogen, an aliphatic group containing up to about four carbon atoms; and R 2  represents an alkoxy group containing up to 18 carbon atoms, an aryloxy group, an amino group of the formula ##STR24## in which R 3  and R 4  (same or different) represent hydrogen, an aliphatic group or an aromatic group, or R 3  and R 4  represent together the necessary atoms to close a 5- or 6-membered heterocyclic nitrogen containing nucleus; and ##STR25## wherein: .[.R 5  represents an aliphatic group containing up to 18 carbon atoms, an aromatic group or a 5- or 6-membered heterocyclic group;.]. .Iadd.R 5  is an aromatic group,.Iaddend.and a reducible noble metal salt of an aliphatic carboxylic acid, said organic reducing compound being present in an effective amount to reduce said noble metal salt and said heat pattern having a temperature of at least about 60° C. and sufficient to initiate said reduction. 
     
     
       2. A recording process according to claim 1, wherein R 2  is the group ##STR26## and R 3  and R 4  represent together the necessary atoms to close a piperidine nucleus. 
     
     
       3. A recording process according to claim 1, wherein R 2  is the group ##STR27## and R 3  represents hydrogen and R 4  an alkyl group. 
     
     
       4. A recording process according to claim 1, wherein the reaction partner is a noble metal salt which upon reduction yields free metal. 
     
     
       5. A recording process according to claim 1, wherein the reaction partner is a silver salt, which in the temperature range of 50° to 200° C. is generally non-light-sensitive. 
     
     
       6. A recording process according to claim 5, wherein the silver compound is a silver salt of an aliphatic carboxylic acid containing a thioether group. 
     
     
       7. A recording process according to claim 5, wherein the silver compound is a silver salt of an aliphatic carboxylic acid containing at least 13 carbon atoms. 
     
     
       8. A recording process according to claim 7, wherein the silver salt is silver behenate or silver stearate. 
     
     
       9. A recording process according to claim 4, wherein the organic reducing agent is used in an amount of at least 0.25 mole per mole of noble metal salt. 
     
     
       10. A recording process according to claim 1, wherein the organic reducing compound and noble metal salt are present in a sheet material and are heated information-wise in a temperature range of 60° to 200° C. 
     
     
       11. The process of claim 1, wherein said noble metal salt undergoes a visible color change when reduced.