Method for producing water-absorbing polymer particles

US10179185B2 · kind B2 · utility

Assignee

• BASF SE

Inventors

• Markus Braun · Mannheim, DE
• Monica Haag · Ludwigshafen, DE
• Stephan Deuerlein · Ludwigshafen, DE
• Volker Klock · Ludwigshafen, DE
• Roland Krauss · Neustadt, DE

Key dates

• Filing date: May 7, 2015
• Grant date: Jan 15, 2019
• Expiry date: Jan 14, 2036

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08J2333/02
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A process for producing water-absorbing polymer particles is provided, comprising a) a polymerization step in which an aqueous monomer solution comprising at least one ethylenically unsaturated monomer M which bears acid groups and may have been at least partly neutralized and at least one crosslinker is polymerized to obtain an aqueous polymer gel; b) a pelletization step in which the aqueous polymer gel having a solids content of 35 to 70% by weight and a temperature of 75 to 125° C. is forced from a high-pressure zone through a die plate into a low-pressure zone and pellets are obtained, the pressure differential between the high-pressure zone and the low-pressure zone being 4 to less than 14 bar and the orifice ratio of the die plate being 30 to 80%; c) a drying step in which the pellets are dried to a moisture content of less than 10% by weight; d) a grinding step and a classifying step to obtain water-absorbing polymer particles; and e) surface crosslinking of the water-absorbing polymer particles. The water-absorbing polymer particles have a high swell rate and a high retention capacity combined with a favorable ratio of permeability of the swollen gel bed SFC to centrifuge …