Process for preparing hydrophobically modified low foaming copolymers, hydrophobically modified low foaming copolymers and their use as cement additives

摘要

The present invention refers to a process for the preparation of a copolymer containing structural units derived from alpha, beta unsaturated mono- or dicarboxylic acids and their salts, half-esters of dicarboxylic acids or salts thereof, an olefin and a hydrophobic moiety, said hydrophobic moiety being incorporated into the copolymer chain; said process comprises reacting a) at least one monomer selected from alpha, beta unsaturated mono-carboxylic acids and their salts; and alpha, beta unsaturated dicarboxylic acids, their halfesters and salts thereof; b) at least one monomer selected from olefins; and c) at least one hydrophobic compound free of olefinic unsaturation containing units of the formula: <CHEM> wherein R<1> is independently at each occurrence selected from hydrogen and C1-C4 alkyl with the proviso that at least one R<1> is selected from C1-C4 alkyl in an amount of 0.01 to 30 wt% based on the total amount of a), b) and c); at a temperature in the range of 25 DEG C-100 DEG C, and in the presence of a free-radical initiator in an amount of 1.5wt%-25wt% based on the total weight of a), b) and c), to copolymers obtainable therefrom and the use of these polymers as cement additives.