Elf Atochem S.a.

Sandrine Denie

Christian Collette

Shu R Rebre

Rosangela Pirri

Bernadette Charleux

Jean-Pierre Vairon

Muriel Lansalot

A process for the emulsion polymerization in the presence of a stable free radical of at least one monomer which can be polymerized by the radical route, which emulsion comprises a liquid aqueous phase and a liquid organic phase, the aqueous phase comprising at least 50% by weight of water and the liquid organic phase comprising more than 50% by weight of monomer(s) to be polymerized. The invention results, by a rapid controlled polymerization process, in a latex of polymer particles, it being possible for the polymer to comprise acrylate and/or methacrylate blocks.

Emulsion polymerization in the presence of a stable free radical

Particulates of a superabsorbent partially, neutralized acrylic polymer, e.g., polyacrylic acid, having a mean particle size ranging from 100 to 500 .mu.m, essentially monodisperse and essentially devoid of fines having a particle size of less than 100 .mu.m, having a nonuniformly surfaced spheroidal particle morphology and containing less than 50 ppm of residual monomer, well suited for a variety of hygienic applications, are prepared by (i) polymerizing a suspension of an acrylic monomer charge I in an organic medium and producing a suspension of acrylic polymer gel particles, (ii) next absorbing a second acrylic monomer charge II into the gel particles, (iii) polymerizing in the gel particles the second acrylic monomer charge II, (iv) azeotropically dehydrating the acrylic polymer particulates thus obtained, (v) then treating the dehydrated particulates with hydrogen peroxide, and (vi) drying the superabsorbent particulates thus treated.

Superabsorbent acrylic powders having low residual monomer content

Growing community of inventors

Paris, France

Sandrine Denie