Inverse emulsion thickeners

Abstract

An inverse emulsion copolymer composition comprises (A) an aqueous phase comprising a cross-linked hydrophilic polyelectrolyte copolymer (A') obtained by the free radical copolymerisation of: (i) at least one anionic ethylenically unsaturated monomer bearing a negatively charged group and one polymerisable C═C double bond, or at least one cationic ethylenically unsaturated monomer bearing a positively charged group and one polymerisable C═C double bond, and (ii) at least one non-ionic ethylenically unsaturated cross-linking monomer bearing at least two polymerisable C═C double bonds, and (iii) optionally, one or more hydrophilic non-ionic ethylenically unsaturated monomers bearing one polymerisable C═C double bond, (B) an oil phase comprising a carrier oil (C), (D) (i) at least one water-in-oil emulsifying surfactant, and (D) (ii) at least one oil-in-water emulsifying surfactant; characterised in that the carrier oil component (C) of the oil phase comprises from 75% to 100%, by weight of the said carrier oil component (C), of farnesane (2, 6, 10-trimethyldodecane). The compositions are effective for use as thickeners for thickening aqueous solutions, including solutions which contain dissolved salts. The compositions also show excellent thickening in acidic solutions than counterpart compositions containing paraffinic oils.