Improvement in the preparation of superabsorbant polyacrylates

摘要

Charges of acrylic acid monomer which are overneutralised and underneutralised in relation to the degree of neutralisation of the final polymer are employed successively for the preparation of superabsorbent powders consisting of partially neutralised polyacrylic acid by a process including the formation of a polymer gel by a first polymerisation of monomer in inverse suspension followed by the polymerisation of a second monomer charge absorbed in this gel. The powders thus obtained consist of particles of spheroidal shape. It is very advantageous to conduct this process with the aid of emulsifiers which are suitably chosen to enable the stage of absorption of monomer by the intermediate gel to be carried out at temperatures of the order of 35-45 DEG C.