Photothermographic materials with opaque crossover control means

A black-and-white aqueous-based,

• symmetric photothermographic material that comprises a transparent support having on both sides thereof:
• a) one or more thermally developable imaging layers each comprising a hydrophilic binder that is gelatin, a gelatin derivative, a poly(vinyl alcohol), or a cellulosic material, or is a water-dispersible polymeric latex, and in reactive association,
• a preformed photosensitive silver bromide, silver iodobromide, or a mixture thereof, provided predominantly as tabular grains, said tabular grains being spectrally sensitized to a predetermined wavelength within the predetermined range of wavelengths of from about 360 to about 420 nm, and a mercaptotriazole toner,
• a non-photosensitive source of reducible silver ions that includes one or more organic silver salts at least one of which is a silver salt of benzotriazole,
• an ascorbic acid reducing agent for said non-photosensitive source of reducible silver ions, and
• b) optionally, an outermost protective layer disposed over said one or more thermally developable imaging layers,
• c) optionally, an antihalation layer on both sides of said support, said antihalation layer being interposed between said support and said one or more thermally developable imaging layers,
• said material comprising in either one of said thermally developable imaging layers on both sides of said support or in said optional antihalation layer, opaque polymeric microcapsules filled with water that become transparent when heated to at least 120° C., which microcapsules are comprised of a polymer derived from a styrene or acrylate monomer, or both, said polymeric microcapsules being dispersed within gelatin, a gelatin derivative, a poly(vinyl alcohol), or a cellulosic material, or a water-dispersible polymeric latex, and
• said material further comprising in said support, a crossover control agent in an amount sufficient to reduced crossover to less 25%,
• said crossover control agent being composition comprising a hydroxyphenylbenzotriazole being one or both of the following compounds:

A black-and-white photothermographic material comprising a support having on a frontside thereof,

• a) one or more frontside thermally developable imaging layers comprising a hydrophilic polymer binder or water-dispersible polymer latex binder, and in reactive association, a photosensitive silver halide that is spectrally sensitized to a predetermined wavelength within a predetermined range of wavelengths, a non-photosensitive source of reducible silver ions that includes a silver salt of a heterocyclic compound containing an imino group, an ascorbic acid or reductone reducing agent for said non-photosensitive source reducible silver ions, and
• said material comprising on the backside of said support, one or more backside thermally developable imaging layers comprising a hydrophilic polymer binder or a water-dispersible polymer latex binder, and in reactive association, a photosensitive silver halide that is spectrally sensitized to a predetermined wavelength within a predetermined range of wavelengths, a non-photosensitive source of reducible silver ions that includes a silver salt of a heterocyclic compound containing an imino group, and an ascorbic acid or reductone reducing agent for said non-photosensitive source reducible silver ions, and
• b) optionally, an outermost protective layer disposed over said one or more thermally developable imaging layers on either or both sides of said support, and
• wherein said one or more thermally developable imaging layers, or said one or more protective layers if present, on both sides of said support have the same or different composition, and
• said material further comprising in a layer on both sides of said support, an opaque material that becomes transparent when heated to at least 120° C., said opaque material comprising polymeric microspheres that are derived from at least one styrene or acrylate monomer, or both, and having an average diameter of from about 0.1 to about 1 μm, said polymeric microspheres being filled with water and being dispersed within a hydrophilic binder or a water-dispersible polymer latex.