| abstract |
The invention relates to a method for producing water-soluble or water-swellable polymers, containing a) 5 to 98 mol. %, preferably between 20 and 80 mol. % of one or more recurrent structural units of formula (1), n n n n n n n n n n where R 1 , R 2 and R 3 represent hydrogen, methyl or ethyl, Y represents a chemical bond, O, CH 2 , C(CH 3 )H, C(O)NR 2 , A represents a chemical bond, O, arylene, phenylene, linear or branched C 1 -C 12 -alkylene, a linear mono-hydroxyalkylene group with 2 to 6 carbon atoms or a linear or branched di-hydroxyalkylene group with 3 to 6 carbon atoms, D stands for S(O), POH, POR 3 or PO-Q + , Q + stands for H + , Li + , Na + , K + , 1/2 Ca ++ , 1/2 Mg ++ , 1/2 Zn ++ , 1/3 Al +++ , 1/4 Zr ++++ or for mixtures of these ions, and b) 2 to 95 mol. %, preferably 20 to 80 mol. % of one or more mutually-independent recurrent neutral structural units, characterised in that the monomers from which the structural units a) and b) are derived undergo free radical polymerisation in precipitation in a polar solvent or solvent mixture, providing that a second polar organic solvent is present if the polar solvent or solvent mixture contains 2-methyl-2-propanol, a ketone or both. |