Process for producing (meth)acrylic acid with treatment of the high-boiling fraction by crystallisation

• Main Author: BALDUF TORSTEN,BUB GUENTHER,MOSLER JUERGEN,YUIANG DENNIS THONG,SABBAGH ANDREAS,LEISTNER JOERG,NORDHOFF STEFAN,KOHN JUERGEN,SELBACH ARNDT
• Format: Patent
• Language: English
• Published: 21.02.2007
• Subjects: ACYCLIC OR CARBOCYCLIC COMPOUNDS; CHEMISTRY; METALLURGY; ORGANIC CHEMISTRY

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.