US Patent 7153647 Thermographic recording material with improved developability

A black and white thermographic recording material comprising a thermosensitive element and a support, the thermosensitive element containing at least one substantially light-insensitive organic silver salt, a binder and optionally photosensitive silver halide, characterized in that the thermosensitive element further contains deliberately added metal nano-particles in a molar ratio with respect to the total molar concentration of the at least one substantially light-insensitive organic silver salt in the range of 0.05:1 to 10−6:1; and the use for the purpose of increasing the ratio of Dmax to the quantity of said substantially light-insensitive organic silver salts per unit area of the above-mentioned thermographic recording material.