Manufacture of cellulosic pulp sheets

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.

主权项

1. A pulp making process comprising:
pulping a fibrous cellulosic material to form an aqueous suspension comprising the cellulosic material, draining the suspension through a screen to form a pulp sheet, and drying the pulp sheet to form a dry market pulp, wherein a water soluble cationic polymer is added to the suspension as a sole drainage aid wherein the water soluble cationic polymer is the only drainage aid added to the suspension in the process, and wherein the water-soluble cationic polymer is: a copolymer comprising between 1 and 70 mole % (meth)acrylamide and between 30 and 99 mole % (meth)acryloyloxyethyltrimethyl ammonium chloride with an intrinsic viscosity of between 5 and 9 dl/g.