Polymethacrylic acid-polyalkylene oxide block copolymers, process for their preparation and their use as dispersants

摘要

Block copolymers of general formula (I) or (II) are new: R1 = alkyl, alkaryl, alkenyl or sulphopropyl; m 3; p = 1-6; n = 2-18; o 1; and X = cation). Production of the block copolymers is also claimed and comprises: (a) re-esterifying polymers of formula (V) (where R is from chain regulator of type ROC(O)(CH2)p, where R = H or 1-2C alkyl), with polymers of formula HOÄCnH2nOÜoR1 or HOÄCnH2n-OÜoH in mole ratio 1.1-1:1-1.1 (to prepare AB-block copolymers) or 1.1-1:0.5-0.55 (to prepare ABA-block copolymers) with addition of known catalysts, optionally in the presence of an inert solvent; and (b) converting the polymers obtained of formula (III) and (IV) at above 60 degrees C in the presence of acid as catalyst and optionally a solvent or above 160 degrees C without catalyst with splitting of isobutene into the desired block copolymers of formula (I) and (II); and (c) optionally converting into alkali or ammonium salt in the known way. Also claimed are the intermediate copolymers of formula (III) and (IV).