Evonik Stockhausen Gmbh

Evonik Degussa Gmbh

Arndt Selbach

Torsten Balduf

Jürgen Mosler

Andreas Sabbagh

Jürgen Kohn

Günther Bub

Stefan Nordhoff

Axel Kobus

Wilfried Uhlich

Dennis Thong Yu-Chiang

Ludwig Papajewski

Hans-Günter Sparenberg

The invention relates to producing a superabsorbent polymer comprising (I) producing a (meth)acrylic acid comprising the steps of (a) synthesizing a crude (meth)acrylic acid phase; (b) distillatively working-up the crude (meth)acrylic acid phase to obtain a (meth)acrylic acid phase and a dimer phase comprising (meth)acrylic acid dimers and/or (meth)acrylic acid oligomers; (c) splitting at least a part of the (meth)acrylic acid dimers or of the (meth)acrylic acid oligomers or both from the dimer phase to obtain a (meth)acrylic acid-comprising a low boiling phase and a high boiling phase comprising less (meth)acrylic acid than the low boiling phase; (d) separating at least a part of the (meth)acrylic acid from the low boiling phase by forming crystals to obtain a pure (meth)acrylic acid, and a residue; (II) polymerizing a monomer phase comprising the pure (meth)acrylic acid to obtain a polymer phase; and (III) working-up the polymer phase to obtain the polymer.

Superabsorbent polymers and methods of making the same

The present invention relates to a process for producing a superabsorbent a polymer comprises (I) producing a pure (meth)acrylic acid comprising the steps of (a) synthesizing a crude (meth)acrylic acid phase; (b) distillatively working-up the crude (meth)acrylic acid phase to obtain a (meth)acrylic acid phase and a dimer phase comprising (meth)acrylic acid dimers or (meth)acrylic acid oligomers or both; (c) splitting at least a part of the (meth)acrylic acid dimers or of the (meth)acrylic acid oligomers or both from the dimer phase to obtain a (meth)acrylic acid-comprising low boiling phase and a high boiling phase comprising less (meth)acrylic acid than the low boiling phase; (d) separating at least a part of the (meth)acrylic acid from the low boiling phase to obtain a pure (meth)acrylic acid, and a residue; (II) polymerizing a monomer phase comprising the pure (meth)acrylic acid to obtain a polymer phase; and (III) working-up the polymer phase to obtain the polymer.

A process for production of (meth)acrylic acid is disclosed. The process includes synthesizing and distillatively working-up a crude (meth)acrylic acid phase to obtain a (meth)acrylic acid phase and a dimer phase including (meth)acrylic acid dimers and/or (meth)acrylic acid oligomers. At least a part of the (meth)acrylic acid dimers and/or of the (meth)acrylic acid oligomers from the dimer phase is split to obtain a (meth)acrylic acid including a low-boiling phase and a high-boiling phase including less (meth)acrylic acid than the low-boiling phase. At least a part of the (meth)acrylic acid from the low-boiling phase is separated by forming of one or more crystals to obtain a pure (meth)acrylic acid and a residue. Also disclosed is a device for production of (meth)acrylic acid, a process for production of a polymer as well as chemical products based on or including (meth)acrylic acid or a polymer as well as the use of (meth)acrylic acid or polymers in chemical products.

Process for production of (meth)acrylic acid with high boiling fraction work-up by means of crystallization

The present invention relates to a process for production of (meth)acrylic acid, whereby first a crude (meth)acrylic acid is produced and this crude (meth)acrylic acid is then continuously purified, whereby the continuous purification of the crude (meth)acrylic acid comprises the following process steps: a) in a composition comprising (meth)acrylic acid and impurities, precipitating the impurities in crystalline form from the composition; and b) separating the crystalline impurities precipitated from the composition. The invention also relates to the (meth)acrylic acid obtainable by this process, a device for production of (meth)acrylic acid, the use of the device or of a purification device for production of (meth)acrylic acid, (meth)acrylic acid, water-absorbing polymers, the use of water-absorbing polymers as well as fibers, sheets, foams and composites.

Method for the purification of (meth)acrylic acid

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Dirmstein, Germany

Arndt Selbach