Method of tanning hides and retanning chrome-tanned leather

摘要

Solo tanning of pelts and retanning of chrome-tanned leather by using a water-soluble condensation product of A) 1 mol of melamine, dicyandiamide, urea or thiourea or a mixture thereof, B) 0.5 to 12 mol of glyoxylic acid or of an aliphatic dialdehyde having up to 6 carbon atoms or of a mixture thereof, C) 0 to 3 mol of a cocondensable compound having at least one phenolic hydroxyl group or at least one alcoholic hydroxyl group, and D) 0 to 3 mol of a cocondensable compound having an amide or amine group, or the alkali metal or ammonium salts of these condensation products.