US 12,467,204 B2
Method for on-site glyoxylation of polyacrylamide
Asko Karppi, Espoo (FI); and Matti Hietaniemi, Espoo (FI)
Assigned to KEMIRA OYJ, Helsinki (FI)
Appl. No. 17/906,359
Filed by KEMIRA OYJ, Helsinki (FI)
PCT Filed Mar. 17, 2021, PCT No. PCT/FI2021/050190
§ 371(c)(1), (2) Date Sep. 15, 2022,
PCT Pub. No. WO2021/186109, PCT Pub. Date Sep. 23, 2021.
Claims priority of application No. 20205273 (FI), filed on Mar. 18, 2020.
Prior Publication US 2023/0129116 A1, Apr. 27, 2023
Int. Cl. D21H 17/45 (2006.01); C08F 8/10 (2006.01); C08F 220/56 (2006.01); D21H 17/37 (2006.01); D21H 17/44 (2006.01); D21H 21/10 (2006.01); D21H 21/18 (2006.01)
CPC D21H 17/455 (2013.01) [C08F 8/10 (2013.01); C08F 220/56 (2013.01); D21H 17/375 (2013.01); D21H 17/44 (2013.01); D21H 21/10 (2013.01); D21H 21/18 (2013.01); C08F 2800/10 (2013.01)] 18 Claims
 
1. A method for on-site glyoxylation of polyacrylamide in a paper mill or board mill, where a discontinuous batch glyoxylation reaction of an aqueous reaction mixture is performed in a reactor vessel provided with a driven agitator to form an aqueous polymer composition comprising glyoxylated polyacrylamide for use in a manufacturing process of paper or board, the method comprising:
forming or obtaining the aqueous reaction mixture comprising polyacrylamide base polymer and glyoxal, wherein the polyacrylamide base polymer has a weight average molecular weight in a range of 50 000-300 000 g/mol;
determining alkali consumption of the reaction mixture;
adding to the reaction mixture, on the basis of the determined alkali consumption, a pre-determined amount of alkali which is needed for adjusting the reaction mixture's pH value within a range of 8-10;
optionally adjusting the aqueous reaction mixture's temperature to a temperature range of 15-40° C.;
allowing the on-site glyoxylation reaction of polyacrylamide base polymer in the reaction mixture to proceed;
measuring viscosity of the reaction mixture and/or a process variable that is related to the viscosity of the reaction mixture;
adding acid to the reaction mixture for lowering the pH value of the reaction mixture <8, when a predetermined end viscosity value is attained; and
removing the aqueous polymer composition comprising glyoxylated polyacrylamide from the reaction vessel.