EFFECTS OF LONG-FIBER ENHANCEMENT ON RADIATA PINE TOPLOG NEWSPRINT

Screening and selective long fibre refining of radiata pine toplog pre ssurized refiner mechanical pulp, at mass reject rates of 24 and 43%, reduced its energy consumption to a given freeness, relative to whole pulp refining. When compared at a common freeness, these screened and long fibre refined pulps had similar tensile strength, higher sheet de nsity and improved optical properties. Screening and long fibre refini ng at mass reject rates of 24, 43 and 60% gave increased opacity and r eduction in print-through. Sulfonation of The long fibre, prior to ref ining, at the 60% reject rate, gave pulps that had high tensile streng th, but poor smoothness,,optical and printability properties, relative To those prepared from untreated long fibre.