Sensitizers for photographic emulsions-by reaction of silver salts wi - andsilver complexing agents

摘要

Sensitizers for photographic emulsions contains, as recurring units, groups, identical or different, of formula -Ag-S-R, in which R is an organic radical 1 to 6 C atoms, pref. 2 to 4, substituted by one or more hydrophilic groups chosen so that the sum of charges of the polymer are 0 or, pref. positive and esp. organic radicals substituted by -NH2-, -OH, quanidino- and/or carboxy groups, particularly 2-aminoethyl. The sensitizers are made by reacting a water soln. of a silver salt with, pref. a slight excess of a water soln. of a mercaptan of formula RSH, in the presence of a cpd. pref. NH4OH or tris-hydroxy-methyl-amino methane, capable of forming a complex with silver.