| 摘要 |
Newsprint or fluting medium is made from an aqueous suspension of cellulosic fibres, the suspension having improved drainage and retention properties. In the suspension is included 0.005 to 0.1% dry weight based on the dry weight of the suspension of a water-soluble, high molecular weight substantially non-ionic polymer selected from a group consisting of polyethylene oxides and polyacrylamides containing not more than 10 mole % anionic groups and not more than 10 mole % cationic groups and having a molecular weight above 100 000. Also included in the suspension is 0.02 to 2% dry weight based on the dry weight of the suspension of bentonite-type clay to give an aqueous suspension consisting essentially of pulp, water, the polymer and fillers. The suspension is, however, substantially free of filler. The bentonite-type clay is added to the aqueous suspension and the polymer is subsequently added. The aqueous suspension is formed from pulp having a cationic demand of at least 0.1%; this demand being the amount of polyethyleneimine cationic polymer that has to be added to give a significant increase in fibre retention and improvement in drainage.
|
