Black-and-white aqueous photothermographic materials containing mercaptotriazole toners

A black-and-white aqueous-based photothermographic material that comprises a support having thereon one or more thermally-developable imaging layers comprising a hydrophilic binder and in reactive association, a preformed photosensitive silver halide, a non-photosensitive source of reducible silver ions that is an organic silver salt other than a silver carboxylate, and a reducing agent composition for said non-photosensitive source reducible silver ions, and

• in one or more of said thermally developable imaging layers, one or more mercaptotriazoles represented by the following Structure I as toner(s):
• wherein R1 and R2 independently represent hydrogen, a substituted or unsubstituted alkyl group of from 1 to 7 carbon atom, a substituted or unsubstituted alkenyl group having 2 to 5 carbon atoms in the chain, a substituted or unsubstituted cycloalkyl group having 5 to 7 carbon atoms forming the ring, a substituted or unsubstituted aromatic or non-aromatic heterocyclyl group having 5 to 6 carbon, nitrogen, oxygen, or sulfur atoms forming the aromatic or non-aromatic ring, an amino or amide group, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms forming the aromatic ring, or a substituted or unsubstituted Y1—(CH2)k— group wherein Y1 is a substituted or unsubstituted aryl group having 6 to 10 carbon atoms in the aromatic ring, or a substituted or unsubstituted aromatic or non-aromatic heterocyclyl group as defined above for R1, and k is 1-3,
• or R1 and R2 taken together can form a substituted or unsubstituted, saturated or unsaturated 5- to 7-membered aromatic or non-aromatic nitrogen-containing heterocyclic ring comprising carbon, nitrogen, oxygen, or sulfur atoms in the ring,
• or still again, R1 or R2 can represent a divalent linking group linking two mercaptotriazole groups, and R2 may further represent carboxy or its salts, and
• M is hydrogen or a monovalent cation,
• provided that:
• 1) R1 and R2 are not simultaneously hydrogen,
• 2) when R1 is substituted or unsubstituted phenyl or benzyl, R2 is not substituted or unsubstituted phenyl or benzyl,
• 3) when R2 is hydrogen, R1 is not an allenyl, 2,2-diphenylethyl, α-methylbenzyl, or a phenyl group having a cyano or a sulfonic acid substituent,
• 4) when R1 is an unsubstituted benzyl or phenyl group, R2 is not substituted 1,2-dihydroxyethyl, or 2-hydroxy-2-propyl,
• 5) when R1 is hydrogen, R2 is not 3-phenylthiopropyl, and
• 6) said one or more thermally developable imaging layers has a pH less than 7.