Brightness Reversion of Mechanical Pulps XI: Photostabilization of High-Yield Pulps by Thiosulfinates

Abstract

A series of eleven cyclic and acyclic thiosulfinates was synthesized and applied onto hardwood BCTMP (bleached chemithermomechanical pulp) testsheets. Treated and untreated testsheets were photoaged and their optical property were monitored. The results of these photoaging experiments indicated that cyclic thiosulfinates were relatively ineffective at retarding brightness reversion, whereas most acyclic additives were effective photostabilization agents for BCTMP. The use of acyclic thiosulfinates in combination with UV absorbers provided a very effective means of retarding the photoaging process of mechanical pulps.