METHOD FOR PRETREATING WOOD CHIP AND METHOD FOR PRODUCING KRAFT PULP OF HIGH WHITENESS

摘要

PROBLEM TO BE SOLVED: To provide a method for pretreating wood chips by which the digestibility can be improved at a low cost in a short time when slightly digestible and slightly bleachable single wood chips of the genus Eucalyptus or mixed wood chips containing the wood of the genus Eucalyptus are pulped with a kraft digesting liquor and to provide a technique for producing the kraft pulp of high whiteness at the low cost by TCF (totally chlorine free) bleaching or ECF (elemental chlorine free) bleaching of unbleached kraft pulp produced by the method for pretreatment. SOLUTION: The slightly digestible and slightly bleachable single wood chips of the genus Eucalyptus or mixed wood chips containing the wood of the genus Eucalyptus are subjected to a pretreatment for treating the chips in a hot water extracting step and then an alkali extracting step. Thereby, the digestibility and bleachability can simultaneously be improved at the low cost and the kraft pulp of high whiteness can be produced. COPYRIGHT: (C)2004,JPO&NCIPI