硬杂木硫酸盐浆的少氯漂白

Less Chlorine Bleaching of Mixed Hardwoods Kraft Pulp

对硬杂木硫酸盐浆的少氯漂白进行了研究。HHP三段漂与HP两段漂对比研究结果表明，HP两段漂浆料的黏度随H段有效氯用量的增大而降低，H段漂后浆料白度越高，经P段漂后浆料白度增值越低；在次氯酸盐段总有效氯用量相同时，HHP漂后浆料的白度均高于HP漂；HHP三段漂白的第1段有效氯用量3％、第2段有效氯用量2％、H2O2用量3％时，硬杂木KP可漂到78％～80％的白度。红外光谱分析结果表明，H2O2漂白主要使浆料中的共轭羰基减少或苯环结构的破坏与溶出。

In this paper, less chlorine bleaching of mixed hardwoods kraft pulp was investigated. The results of HP bleaching showed that the higher KMnO4 value of the hypochlorite bleached pulp the lower brightening efficiency（△ ISO/△KMnO4） of peroxide stage. Furthermore, the higher brightening efficiency of peroxide stage was obtained when the KMnO4 value of the hypochlorite bleached pulp was in the range of 1.8 to 3.0. On the other hand, the viscosity of peroxide bleached pulp was decreased with the increase of the active chlorine dosage at hypochlorite stage. The brightness gain of peroxide stage was lower when the pulp brightness was higher at the hypochlorite stage. In addition, the comparison of liP and HHP bleaching results indicated that the brightness of the pulp after HI-IP bleaching was higher than that of liP bleaching when the charges of active chlorine at the hypochlorite stage and H2O2 at P stage were 6% and 3% respectively. By using HHP bleaching sequence the mixed hardwoods kraft pulp could be bleached to about 80%ISO brightness when the charges of active chlorine of the first and the second hypochlorite stage were 3% and 2% respectively and the charge of H2O2 was 4% at P stage. FT-IR results showed that part of lignin and conjugate carbonyl group were degraded and dissolved during the peroxide bleaching process.