| abstract |
Process for the discontinuous production of crosslinked, finely divided, water-absorbing polymers by copolymerizing monomer mixtures containing 0 per 100 parts by weight of 0 to 100 mol% neutralized with alkali metal or ammonium bases acrylic acid or methacrylic acid, acrylamide, methacrylamide or N-vinylpyrrolidone , 01 to 5 parts by weight of a monomer containing at least two ethylenically unsaturated double bonds as a crosslinking agent in 20 to 80% by weight aqueous solution in the presence of initiators in a multi-stage process in a continuously operating mixing device with constant mixing in all stages, whereby in the first stage, the aqueous monomer solution was copolymerized at temperatures from 45 to 95 ° C. and a pressure from 0.1 to 0.8 bar with partial distillation of water, in the second stage the copolymerization at temperatures from 100 to 170 ° C. under a Pressure up to 8 bar and completed in the third stage the water content of the finely divided copolymers thus produced is reduced to 0.5 to 10% by weight under reduced pressure. |