Aqueous Solution Containing Copolymers with Polyether Side Chains

Process for the preparation of an aqueous solution comprising 30 to 95% by weight of water and 5 to 70% by weight of a copolymer dissolved in the water by free radical solution polymerizations of an isoprenol polyether derivative with an acrylic acid derivative, so that the copolymer has

• i) 20 to 45 mol % of an isoprenol polyether derivative structural unit α) and
• ii) 55 to 80 mol % of an acrylic acid derivative structural unit β),
• the isoprenol polyether derivative structural unit α being represented by the following general formula (Ia)
• where
• A is identical or different and is represented by an alkylene group according to CxH2x where x=2, 3, 4 or 5,
• a is identical or different and is represented by an integer between 11 and 34,
• the acrylic acid derivative structural unit β being represented by the following general formulae (IIa) and/or (IIb)
• where
• X is identical or different and is represented by NH—(CnH2n) where n=1, 2, 3 or 4 or represented by O—(CnH2n) where n=1, 2, 3 or 4;
• R1 is identical or different and is represented by SO3H, PO3H2 OPO3H2 and/or C6H5—SO3H
• R2 is identical or different and is represented by OH, OM where M=Na, K, or Ca, and/or ONH4.