Bleaching of Colored Broke by Elemental Chlorine Free (ECF) and Totally Chlorine Free (TCF) Processes

摘要

Six different colored broke samples were bleached by Elemental Chlorine Free (ECF) and Totally Chlorine Free (TCF) bleaching processes. Broke samples were bleached either individually or in blends. Some of the colored grokes were mixed with brownstock and bleached, EIE's L~*a~*b~* numbers were usd to rank the efficiency of various bleaching processes. Single-stage TCF bleaching with hydrogen peroxide, oxone or formamidine sulfinic acid (FAS) did not provide bright pulp suitable for use in premium grade papers like Laser Jet, etc. Chlorine dioxide is very effective in bleaching colored brokes and their blends, as is hypochlorite. Single stage bleaching of broke in many instances provided Lightness (L~*) value of 90.0 but failed to meet the "chroma" specification of .