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1. (WO2012055681) METHOD FOR PRODUCING IMPROVED ABSORBING POLYMERS BY MEANS OF CRYOGENIC GRINDING

Pub. No.:    WO/2012/055681    International Application No.:    PCT/EP2011/067348
Publication Date: Fri May 04 01:59:59 CEST 2012 International Filing Date: Thu Oct 06 01:59:59 CEST 2011
IPC: C08F 6/00
A61L 15/22
A61L 15/60
C08J 3/12
C08J 3/24
Applicants: EVONIK DEGUSSA GMBH
LOICK, Christoph
GARTZ, Dominik
WATTEBLED, Laurent
HARREN, Jörg
Inventors: LOICK, Christoph
GARTZ, Dominik
WATTEBLED, Laurent
HARREN, Jörg
Title: METHOD FOR PRODUCING IMPROVED ABSORBING POLYMERS BY MEANS OF CRYOGENIC GRINDING
Abstract:
The invention relates to a method for producing a water-absorbing polymer, comprising the following steps: (i) mixing (a1) 0.1 to 99.99 wt.%, preferably 20 to 98.99 wt.%, and particularly preferably 30 to 98.95 wt.% of polymerized, ethylenically unsaturated, acid-group-containing monomers or the salts thereof, or polymerized, ethylenically unsaturated monomers containing a protonated or quarternized nitrogen, or the mixtures thereof, wherein mixtures containing at least ethylenically unsaturated, acid-group-containing monomers, preferably acrylic acid, are particularly preferred, optionally partially neutralized, (a2) 0 to 70 wt.%, preferably 1 to 60 wt.%, and particularly preferably 1 to 40 wt.% of polymerized, ethylenically unsaturated monomers that can be copolymerized with (a1), (a3) 0.001 to 10 wt.%, preferably 0.01 to 7 wt.%, and particularly preferably 0.05 to 5 wt.% of one or more cross-linking agents, (a4) 0 to 30 wt.%, preferably 1 to 20 wt.%, and particularly preferably 5 to 10 wt.% of water-soluble polymers, and (a5) 0 to 20 wt.%, preferably 0.01 to 7 wt.%, and particularly preferably 0.05 to 5 wt.% of one or more auxiliary substances, wherein the sum of the weights (a1) to (a5) is 100 wt.%; (ii) radically polymerizing, with cross-linking, so as to form a water-insoluble, aqueous untreated hydrogel polymer; (iii) coarsely comminuting the untreated hydrogel polymer into pieces having a diameter in the range of 0.1 mm to 5.0 cm; (iv) cooling the pre-comminuted untreated hydrogel polymer and grinding the cooled untreated hydrogel polymer; (v) drying the comminuted untreated hydrogel polymer after grinding at a temperature in the range of 85ºC to 260ºC and sifting the dried pieces in the range of 150 µm to 850 µm; (vi) post-crosslinking the hydrogel polymer; and (vii) drying and packaging the water-absorbing polymer. The invention further relates to the use thereof.