PROCESSES FOR PREPARING MECHANICAL PULPS HAVING HIGH BRIGHTNESS

摘要

The present invention provides a process for preparing bleached mechanical pulp having high brightness from wood chips consisting essentially of the steps, in order, of impregnating wood chips having low bleachability with a chemical liquor consisting essentially of an aqueous solution of an alkaline inorganic compound and a chelating agent at a pH range of 7 to 12 and then removing said impregnating chemical liquor from said chips, next followed by the sequential steps, in order, of (a) defibration by primary refining, bleaching, and beating by secondary refining, or (b) defibration by primary refining, beating by secondary refining and bleaching.