Elf Atochem S.a.

Andre Kowalik

Christian Collette

Manuel Hidalgo

Emmanuel Puchois

Shu R Rebre

Paul Mallo

Jean-Marc Corpart

Shu-Rong Rebre

Fabienne Lebendenko

Certain mixtures of two superabsorbent powders having very different capillary suctions exhibit a resulting capillary suction which approaches the higher value. The resulting mixtures simultaneously exhibit a high capillary suction and a high intrinsic absorption capacity.

Superabsorbent powders of high absorption and high capillary suction

Rapidly dissolving/absorbing free-flowing powders of hydrophilic/superabsorbent (co)polymers, having irregular nonspherical morphology and a particle size distribution ranging from 100 .mu.m to 800 .mu.m, are prepared by (a) phase inversion (co)polymerizing stirred admixture of (i) a hydrocarbonic solution of at least one surfactant having an HBL ranging from 8 to 12 and (ii) an aqueous solution of at least one hydrophilic unsaturated monomer, in the presence of an effective amount of a radical polymerization initiator and at a predetermined temperature of (co)polymerization, (b) next introducing into the medium of (co)polymerization, after (co)polymerization of the at least one hydrophilic unsaturated monomer, a second aqueous solution of at least one hydrophilic unsaturated monomer, (c) then (co)polymerizing the second aqueous solution, and (d) thence extracting the hydrocarbonic phase and water from the resulting (co)polymerizate and drying same, with the proviso (e) that the second aqueous monomer solution is introduced at a temperature of about the predetermined temperature of (co)polymerization and the volumetric ratio of aqueous phase to hydrocarbonic phase ranges from 0.6 to 1.2.

Preparation of rapidly dissolving/absorbing powders of hydrophilic/super

Shell/core distortion-resistant particulates of a partially crosslinked superabsorbent polymer, the gradient of partial crosslinking of which being to such extent that the shells are harder and less flexible than the cores thereof, have a capacity to absorb 0.9% saline water of at least 50 g/g and the modulus of which is at least 35,000 Pa; a bed of a saline water gel of the subject particulates has a saline water absorption of at least 20 g/g and a porosity of at least 500 g.

Shell/core particulates of superabsorbent polymers

The process consists in the agglomeration of fine particles of superabsorbent polymer, carried out by introducing an aqueous solution of monomer into a slurry of aqueous polymer dispersed within a hydrocarbon liquid, this introduction being performed directly at the temperature and in conditions of polymerization of the monomer. A superabsorbent product is thus obtained in a very good yield, in the form of aggregates of particles such that the fraction passing through a 100-micron screen is less than 1%.

Process for obtaining polymers which are superabsorbent for water and

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.

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Gouvieux, France

Andre Kowalik