NUCLEATED HIGH CONTRAST PHOTOGRAPHIC ELEMENTS CONTAINING SUBSTITUTED THIOUREAS WHICH ENHANCE SPEED AND INCREASE CONTRAST

摘要

The invention relates to photographic elements based on silver halide, which are capable of high contrast development and are especially useful in the field of graphic arts. In these elements, which contain silver halide grains in high chloride forming latent images of surface have been incorporated a hydrazine compound functioning as a nucleating agent, an amino compound that functions as incorporated accelerator, as well as a combination of a gold compound and a thiourea compound that functions as a chemical sensitizer. The compounds of thiourea provided for this purpose are substituted thioureas having one or two acyl substituents or having three alkyl or aryl having a substituent and two alkyl substituents.