US 12,257,567 B2
Process for preparation of superabsorbent polymer
Paresh Vithaldas Talati, Mumbai (IN); and Prashant Vasant Kini, Mumbai (IN)
Assigned to UPL LTD, Haldia (IN)
Appl. No. 17/422,831
Filed by UPL LTD, Haldia (IN)
PCT Filed Jan. 28, 2020, PCT No. PCT/IB2020/050640
§ 371(c)(1), (2) Date Jul. 14, 2021,
PCT Pub. No. WO2020/157643, PCT Pub. Date Aug. 6, 2020.
Claims priority of application No. 201931003588 (IN), filed on Jan. 29, 2019.
Prior Publication US 2022/0097022 A1, Mar. 31, 2022
Int. Cl. B01J 20/26 (2006.01); C08F 8/12 (2006.01); C08F 220/44 (2006.01); C08F 251/00 (2006.01); C08J 3/12 (2006.01); C08K 3/22 (2006.01); C08K 5/01 (2006.01); C08K 5/02 (2006.01); C08K 5/103 (2006.01)
CPC B01J 20/265 (2013.01) [C08F 8/12 (2013.01); C08F 220/44 (2013.01); C08F 251/00 (2013.01); C08J 3/12 (2013.01); C08K 3/22 (2013.01); C08K 5/01 (2013.01); C08K 5/02 (2013.01); C08K 5/103 (2013.01); B01J 2220/68 (2013.01); C08J 2300/14 (2013.01); C08J 2303/04 (2013.01)] 5 Claims
 
1. A method for preparing a superabsorbent polymer of starch-g-poly-(2-propenamide-co-2-propenoic acid) or its salt, comprising:
a) hydrating the pre-gelatinized starch with water at a temperature in the range of 25-35° C. and adding ammonium-cerium nitrate to the hydrated starch solution as an initiator for activation;
b) adding acrylonitrile to the activated mixture and holding the resulting mixture at 30-45° C. while stirring to obtain a starch-grafted polymer;
c) saponifying the starch-grafted polymer in the presence of a solvent selected from chlorinated hydrocarbons, aliphatic hydrocarbons, aromatic hydrocarbons, or mixtures thereof, using polysorbate as a nonionic surfactant, and a base solution at 50-100° C.; to create the superabsorbent polymer suspended in the solvent, wherein the base in the base solution is selected from a group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide (Sr(OH)2) or barium hydroxide (Ba(OH)2);
d) obtaining the superabsorbent polymer; and wherein the obtained superabsorbent polymer has a water absorbing capacity above 500 grams per gram.