PAPER-STRENGTHENING AGENT AND PAPER STRENGTHENING METHOD Russian patent published in 2000 - IPC

FIELD: paper-and-pulp industry. SUBSTANCE: invention relates to agent containing aqueous dispersion of polymer prepared by polymerization of (meth)acrylic acid-containing monomer composition and precipitation of polymer in the form of fine particles, which are then added to paper layer already formed. According to invention, concentration of (co)polymer of (meth)acrylic acid in polymer dispersion is below 5 wt %, average particle size is within a range of 1 to 100 mcm, and viscosity of polymer dispersion freshly prepared and 1 month later is equal to the value form 30 to 5000 mPa. Polymer particles can be identified when polymer dispersion is tenfold diluted with distilled water and diluted dispersion is observed under microscope with 400x magnification. Polymer particles are dissolved to form aqueous solution when pH of diluted dispersion is adjusted to 7.0 by addition of alkali. Agent thus prepared allows manufacturing paper with elevated strength when, diluted with water, it is applied to surface of dry or wet paper or impregnates paper, after which paper is dried. EFFECT: increased strength of paper. 13 cl, 5 tbl, 4 ex