Process for producing improved absorbent polymers by means of cryogenic grinding

US8859701B2 · kind B2 · utility

Assignee

• EVONIK DEGUSSA GMBH · DE

Inventors

• Christoph Loick · Duisburg, DE
• Dominik Gartz · Viersen, DE
• Laurent Wattebled · Düsseldorf, DE
• Jorg Harren · Baesweiler, DE

Key dates

• Filing date: Oct 5, 2011
• Grant date: Oct 14, 2014
• Expiry date: Nov 6, 2031

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08J2333/00
• WIPO field: Medical technology
• WIPO sector: Instruments

Abstract

A process for producing a water-absorbing polymer comprises: (i) mixing (α1) 0.1-99.99% by weight of ethylenically unsaturated monomers containing acid groups or salts thereof, or ethylenically unsaturated monomers including a protonated or quaternized nitrogen, or mixtures thereof, (α2) 0-70% by weight of ethylenically unsaturated monomers copolymerizable with (α1), (α3) 0.001-10% by weight of one or more crosslinkers, (α4) 0-30% by weight of water-soluble polymers, and (α5) 0-20% by weight of one or more assistants, where the sum of the weights (α1) to (α5) is 100%; (ii) free-radical polymerization with crosslinking to form an untreated hydrogel polymer; (iii) coarse comminution of the untreated hydrogel polymer to give pieces having a diameter from 0.1 mm to 5.0 cm; (iv) cooling and grinding the untreated hydrogel polymer; (v) drying the untreated hydrogel polymer after grinding at a temperature from 85° C. to 260° C.; (vi) postcrosslinking the hydrogel polymer and (vii) drying the water-absorbing polymer.