PAPER AND CARDBOARD MANUFACTURE PROCESS Russian patent published in 2005 - IPC

FIELD: paper-and-pulp industry.

SUBSTANCE: process comprises preparation of paper pulp, flocculation of pulp, drainage of pulp on the screen to form sheet, and subsequent drying of sheet. Flocculation involves flocculation system including clay and water-soluble anionic branched polymer. The latter is prepared using water-soluble anionic ethylenically-unsaturated monomer or monomer mixture and ramification-forming agent. Polymer is characterized by intrinsic viscosity above 1.5 dl/g and/or Brookfield viscosity in salt solution above about 2.0 mPa·s, rheological oscillation delta tangent value at 0.005 Hz above 0.7, and/or reduced viscosity in deionized water at least thrice exceeding reduced viscosity in salt solution of corresponding nonbranched polymer obtained in absence of ramification-forming agent.

EFFECT: improved drainage, retention, and formation process.

20 cl, 10 tbl, 8 ex