Inflated water polymer-mineral

A water-swellable polymeric mineral composite contains a bentonite clay and a linear polyanionic polymer taken in an amount giving a weight ratio of polymer to the title clay of 0.05 to 0.10. The preparation of the composite material is carried out by mixing a bentonite clay and a linear polyanionic polymer having a molecular weight of 10 to one sixth or more, taken in an amount to ensure a weight ratio of polymer to the title clay of 0.05 to 0.10 in the presence of water followed by drying the resulting water to obtain a final solid product. oh