MANUFACTURE OF DRY MARKET PULP USING WATER-SOLUBLE CATIONIC POLYMER AS SOLE DRAINAGE AID

摘要

A pulp making process in which fibrous cellulosic material is pulped to form an aqueous suspension of cellulosic material, the suspension is drained through a screen to form a pulp sheet and that the pulp sheet is dried to form a dry market pulp, in which a water soluble cationic polymer is added to the suspension as the sole drainage aid wherein the water-soluble cationic polymer is either, i) a copolymer comprising (a) between 1 and 70 mole % (meth) acrylamide and (b) between 30 and 99 mole % (meth) acryloyloxyethyl- trimethyl ammonium chloride with an intrinsic viscosity between 5 and 9 dl/g; or ii) a hydrolysed homopolymer of vinylformamide comprising between 1 and 100 mole% vinyl amine units and having a K value of between 45 and 240. The process of the invention provides improved drainage time and solids content of the dewatered pulp.