Process for retanning chrome-tanned leather with sulphite-containing acrylic oligomers

摘要

Oligomers having structural elements of formulae IMAGE and optionally IMAGE where X is -CN, -COOR, -OOCR or -CONHR Y1 is -COOH or -COOM Y2 is -CONH2, -CH2OCH, -OCH3 or -OC2H5 Z is -H, -CH3 or -C2H5 M is an amine, ammonium or alkali metal cation and R is alkyl, hydroxyalkyl or alkoxyalkyl having not more than 8 carbon atoms, are used in a process for retanning (aftertanning) chrome-tanned leather. The oligomers are prepared by copolymerising the acrylic acid comonomers corresponding to the structural elements of the indicated formulae in the presence of sulphites or bisulphites (hydrogen sulphites) of the formulae SO3(M)2 or HSO3M.