Patent ID: 9631319
Date: 2017-04-25
CPC Classifications: D21H

Claim:
1. A method of making paper, board or paperboard, said method comprising shearing a cellulosic thin stock in one or more stages to provide a sheared product, draining the sheared product on a moving screen to form a sheet, drying the sheet to produce the paper, board or paperboard, wherein a treatment is applied to the thin stock, said treatment system comprising a) a cationic organic polymer with a charge density of greater than 4 mEq/g and a molar mass Mw of up to 3 million Daltons, b) a cationic polymer with an average molar mass Mw of at least 500,000 Daltons and a charge density not exceeding 3.0 mEq/g, and c) a microparticulate material, and components (b) and (c) are added to the cellulosic thin stock after a last shear stage but before a head box, and component (a) is added to the cellulosic thin stock before said last shear stage.