Elf Atochem S.a.

Shu R Rebre

Christian Collette

Andre Kowalik

Sandrine Denie

Thierry Guerin

Superabsorbent, high gel strength/short gel time acrylic polymers, well suited for the production of items of feminine hygiene/adult incontinence, are prepared by (a) inversely suspending an aqueous acrylic monomer phase in an organic solvent in the presence of an emulsifying agent having an HLB of from 8 to 12, the aqueous monomer phase also comprising a crosslinking agent therefor, (b) polymerizing the inverse suspension of acrylic monomer into a polymer gel, (c) absorbing a second charge of acrylic monomer into the polymer gel thus attained, the ratio of the amount of the second monomer charge to the amount of monomer in the beginning aqueous phase ranging from 1 to 1.2, (d) introducing a surfactant having an HLB of from 2 to 5 into the medium of polymerization, and (e) polymerizing the second monomer charge within the polymer gel.

Superabsorbent polymers

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

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 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, such acrylic monomer charge I having a degree of neutralization greater than that desired in the final superabsorbent polymer, (ii) next absorbing a second acrylic monomer charge II into the gel particles, such acrylic monomer charge II having a degree of neutralization less than that desired in the final superabsorbent polymer, and (iii) polymerizing in the gel particles the second acrylic monomer charge II.

Superabsorbent acrylic powders

Particulates of a superabsorbent polymer, e.g., an acrylic polymer such as polyacrylic acid, well suited for a variety of hygienic applications, are prepared by (i) suspending an aqueous solution of a water-soluble monomer charge I in a hydrocarbon medium by means of a polymerizable surfactant having the general formula:

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Shu R Rebre