1983 Volume 37 Issue 6 Pages 530-536
In order to modify thermomechanical pulp (TMP) a study was made of NaOCl·H2O2 and NaOCl·O3 bleaching under mild conditions. The results obtained were as follows.
(1) Under the optimum conditions, TMP prepared from mixed soft woods was soaked in a 4% available chlorine-contained NaOCl solution (pH 11) for 10 min. at room temperature, and then after removing excess NaOCl solution, bleached with H2O2 solution (H2O2, 15% per pulp) for 1 hour at 50°C.
The brightness of TMP bleached under the above conditions increased from 40% to 70% GE. The yield of bleached pulp was 93%. The water retention value and the sheet density of TMP also increased by bleaching. The tensile strength, burst factor and tear factor of TMP after bleaching were 2.7 km, 1.2 and 81, respectively.
(2) A new bleaching of TMP by NaOCl·H2O2 system was clarified to be more effective method than NaOCl·O3 system for bleaching without decreasing the mechanical properties.
