Basf Aktiengesellschaft

Basf Se Corporation

Stefan Wickel

Heinrich Hartmann

Thomas Daniel

Wilfried Heide

Manfred Niessner

Juergen Beck

Reinhold Schwalm

Klaus Joachim Mueller-Engel

Gerhard Nestler

Thomas Jaworek

Rainer Koeniger

J&uuml;rgen Hofmann

Walter Schneider

Thomas Meyer

Uwe Stüven

Joachim Nilges

Lothar Wolf

Gabriele Hartmann

Andreas H Kemna

Rainer Königer

The invention relates to a cross-linked, water-swellable polymer that contains polymerized into it moieties of The polymer according to the invention has a balanced property profile as regards absorptivity, gel strength, absorption speed and extractable componenents and can be advantageously produced by a continuous method.

Cross-linked, water-swellable polymer and method for producing the same

This invention relates to a process for preparing a low-odor hydrogel-forming acrylic acid polymer, which comprises the steps of: a) preparing a polymeric hydrogel by free-radically polymerizing a monomer composition comprising at least 50% by weight of acrylic acid in an aqueous polymerization medium and converting said hydrogel into a particulate hydrogel or into hydrogel-forming powder; and optionally b) treating said particulate hydrogel or said hydrogel-forming powder with a crosslinking substance which, actually or latently, contain at least two functional groups capable of reacting with the carboxyl groups on the addition polymer; characterized by the acrylic acid used in step a) containing less than 400 ppm of acetic acid and propionic acid. It further relates to the hydrogel-forming addition polymers obtainable by the process and to their use.

Method for producing low-odor hydrogel-forming polymers

Unsaturated acids are esterified with polyalcohols. The resulting reaction mixtures have utility.

Method for the production of esters of polyalcohols

A process for continuous production of crosslinked fine particles of polymer gel by copolymerizing a) water-soluble monoethylenically unsaturated monomers, b) from 0.001 to 5 mol % based on the monomers (a) of monomers containing at least two ethylenically unsaturated double bonds, and c) from 0 to 20 mol % based on the monomers (a) of water-insoluble monoethylenically unsaturated monomers in from 20 to 80% by weight aqueous solution in the presence of an initiator at from 0 to 140&deg; C. by feeding the aqueous solution of the monomers together with the initiator and an inert gas continuously into a mixing kneader having at least two axially parallel rotating shafts equipped with a plurality of kneading and transporting elements which convey the substances introduced at the upstream end of the mixing kneader in the axial direction toward the downstream end of the mixer, comprises the fraction of heat being removed by evaporation of water from the reaction mixture being not less than 5% of the heat of reaction and the fraction of heat being removed by product discharge being not less than 25% of the heat of reaction and the rest of the heat being removed via cooling of the reactor walls.

Method for continuously producing cross-linked fine-particle geleous polymerizates

Finely divided, water-soluble polymers are prepared by polymerization of water-soluble, monoethylenically unsaturated monomers in not less than 20% strength by weight aqueous solution in the presence of a polymerization initiator in a kneader by a process in which from 0.1 to 10% by weight, based on the total monomers, of a surfactant are used in the polymerization, the polymerization initially being carried out to a conversion of the monomers of not less than 60% in the absence of the surfactant or in the presence of not more than 50% of the amount of surfactant, and the remaining amount of surfactant then being added to the reaction mixture and the polymerization completed. The addition of surfactant causes the polymer gel to disintegrate with formation of fine particles.

Preparation of finely divided, water-soluble polymers

The water absorption capacity of crosslinked, water-swellable polymers is improved by a process in which a water-containing, finely divided polymer gel having a solids content of from 20 to 65% by weight is treated with steam at not less than 50.degree. C., the solids content of the water-containing polymer gel increasing by not more than 30% by weight, and the polymer gel is then dried in a conventional manner.

Improving the water absorption capacity of crosslinked, water-swellable

Finely divided, gel-like, water-swellable copolymers are prepared by copolymerizing

Preparation of finely divided, gel-like, water-swellable copolymers

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Bissersheim, Germany

Stefan Wickel