Thermally developable materials with improved speed and contrast and methods of use

A black-and-white photothermographic material that comprises a support having thereon one or more thermally developable imaging layers comprising:

• a binder,
• a photosensitive silver halide,
• a non-photosensitive source of reducible silver ions, and
• a reducing agent composition for said non-photosensitive source reducible silver ions, said reducing agent composition comprising:
• a) a hindered phenol reducing agent, and b) a thermally-releasable p-phenylenediamine co-developer, that is represented by the following Structure 1:
• R—NH-BLOCK (I)
• wherein R—NH— is a p-phenylenediamine group and BLOCK is a blocking group that is cleaved upon exposure to at least 120° C. for at least 5 seconds and comprises one or more of the following thermally cleavable groups:
• —CONH—, —COO—, —CONHSO2—, —PO3—, —SO2—, —COCH2NHCO—, or —COS—, and BLOCK is directly linked to R—NH— through one of said thermally cleavable groups.

A black-and-white photothermographic material that comprises a support having thereon:

• a) one or more thermally developable imaging layers each comprising a hydrophobic binder, and in reactive association,
• a photosensitive silver bromide or silver iodobromide,
• a non-photosensitive source of reducible silver ions that includes one or more silver carboxylates at least one of which is silver behenate,
• a reducing composition for said non-photosensitive source of reducible silver ions that includes at least one bis-phenol reducing agent and a thermally-releasable p-phenylenediamine co-developer that is represented by the following Structure II:
• wherein R1 is an amino group, R2 is hydrogen, or a substituted or unsubstituted alkyl, alkenyl, alkoxy, thioalkyl, or halo group, m is 0, 1, or 2, and BLOCK is any of the following groups BLOCK-1 through BLOCK-8:
• BLOCK-1 —CONH—R3 (ureido group) BLOCK-2 —COO—R3 (carbamoyl group) BLOCK-3 —CONHSO2—R3 BLOCK-4 BLOCK-5 —SO2—R3 BLOCK-6 —PO—(OR3)2 (phosphate group) BLOCK-7 —COCH2NHCO—R3 BLOCK-8 —COS—R3
• wherein R3 is an alkyl, alkenyl, aryl, cycloalkyl, or heterocyclyl group,
• wherein the molar ratio of said bis-phenol reducing agent to said thermally-releasable p-phenylenediamine co-developer is from about 5:1 to about 1:1, said bis-phenol reducing agent is present in an amount of from about 0.5 to about 1.5 g/m2, and said thermally-releasable p-phenylenediamine co-developer is present in an amount of from about 0.25 to about 1.0 g/m2, and
• b) a protective overcoat disposed over said one or more thermally-developable imaging layers, an antihalation layer on the backside, or both said protective layer and said antihalation layer.

An imaging assembly comprising a thermally developable material arranged in association with a phosphor intensifying screen,

• said thermally developable material comprising a support having thereon one or more thermally developable imaging layers comprising:
• a binder,
• a photosensitive silver halide,
• a non-photosensitive source of reducible silver ions, and
• a reducing agent composition for said non-photosensitive source of reducible silver ions, said reducing agent composition comprising:
• a) a hindered phenol reducing agent, an aromatic di- or tri-hydroxy compound, or mixtures thereof, and b) a thermally-releasable p-phenylenediamine co-developer that is represented by the following Structure I:
• R—NH-BLOCK (I)
• wherein R—NH— is a p-phenylenediamine group and BLOCK is a blocking group that is cleaved upon exposure to at least 120° C. for at least 5 seconds and comprises one or more of the following thermally cleavable groups:
• —CONH—, —COO—, —CONHSO2—, —PO3—, —SO2—, —COCH2NHCO—, or —COS—, and BLOCK is directly linked to R—NH— through one of said thermally cleavable groups.