METHOD OF PRODUCING PAPER OR CARDBOARD Russian patent published in 2023 - IPC D21H17/34 D21H17/45 D21H17/55 D21H21/10 C08L39/02 

FIELD: paper industry.

SUBSTANCE: invention relates to a method of producing a sheet of paper or cardboard. Before forming a sheet of paper or cardboard, at least one polymer of N-vinylformamide, partially hydrolyzed as an inverse emulsion and having an increase in cationicity, measured in meq g^-1 by colorimetric titration of a solution of 5 g l^-1 in polymer water, after shearing at 8,000 rpm compared to a non-shear solution, 30 to 150% is added at one or more injection points to the fiber suspension in the presence of an anti-gel agent. The reverse emulsion has a mass ratio of partially hydrolyzed N-vinylformamide polymer and anti-gelation agent in the range from 1,000,000/5,000 to 1,000,000/50,000.

EFFECT: provision of improved dewatering efficiency, fiber and fines retention, as well as filler retention.

15 cl, 4 tbl, 3 ex