US 12,239,947 B2
Method for the production of superabsorbents
Thomas Pfeiffer, Ludwigshafen (DE); Ruediger Funk, Ludwigshafen (DE); Marco Krueger, Ludwigshafen (DE); Karl Possemiers, Antwerp (BE); Juergen Schroeder, Ludwigshafen (DE); and Matthias Weismantel, Ludwigshafen (DE)
Assigned to BASF SE, Ludwigshafen (DE)
Appl. No. 17/264,093
Filed by BASF SE, Ludwigshafen (DE)
PCT Filed Aug. 9, 2019, PCT No. PCT/EP2019/071450
§ 371(c)(1), (2) Date Jan. 28, 2021,
PCT Pub. No. WO2020/038742, PCT Pub. Date Feb. 27, 2020.
Claims priority of application No. 18189715 (EP), filed on Aug. 20, 2018.
Prior Publication US 2021/0154637 A1, May 27, 2021
Int. Cl. B01J 13/00 (2006.01); A61L 15/60 (2006.01); C08F 2/01 (2006.01); C08F 2/16 (2006.01)
CPC B01J 13/0069 (2013.01) [A61L 15/60 (2013.01); B01J 13/0065 (2013.01); C08F 2/01 (2013.01); C08F 2/16 (2013.01)] 16 Claims
 
1. A process for producing superabsorbent particles by polymerizing a monomer solution comprising
a) at least one ethylenically unsaturated monomer which bears an acid group and has been neutralized to an extent of 50 to 85 mol %,
b) at least one crosslinker,
c) at least one initiator,
d) optionally one or more ethylenically unsaturated monomer copolymerizable with the monomers mentioned under a) and
e) optionally one or more water-soluble polymer,
comprising
i) continuously polymerizing the monomer solution on a continuous belt of a belt reactor,
ii) comminuting a polymer gel obtained in step i),
iii) rinsing the polymer gel obtained on the underside of the belt reactor into a separation unit with water,
iv) separating the polymer gel from the water in the separation unit and
v) recycling the polymer gel separated off in step iv) into step ii),
wherein the polymer gel has a swelling capacity in water of at least 100 g/g, a dwell time between step iii) and step iv) is less than 20 minutes, and the separation unit in step iv) has openings with a clear width of at least 1 mm.