FAS在杉木CTMP漂白中的应用研究

Brightness and Shade Improvement of China Fir CTMP Pulps by Using FAS Bleaching in Multi-stage Processes

对杉木CTMP组合漂白中的FAS漂白进行了研究。结果表明,FAS漂白中m(NaOH)∶m(FAS)的最佳值为0.5,FAS适宜进行高温短时间漂白,90℃、30min时漂白效果良好。FAS与H2O2结合的两段漂白可以将浆料漂白至更高的白度,其中FAS漂白置于H2O2漂白之后,可获得更好的漂白效果,与FAS漂白置于H2O2漂白之前相比,白度可提高1～2个百分点。以FAS漂白为结束段的三段漂白,浆料色相得到改善,白度达到82.8%,且其废水污染负荷和色度较低。FAS漂白对漂白浆料强度性能无不良影响,与未漂浆相比,含FAS的三段组合漂白浆的抗张指数(28.2N·m/g)、撕裂指数(4.70mN·m2/g)和耐破指数(1.62kPa·m2/g)分别提高了100%、22%和70%。

The bleached China fir CTMP pulp is difficult to reach a high brightness level of more than 78% ISO by only using single stage hydrogen peroxide bleaching and has an obvious yellowish shade. To obtain a higher brightness target and remove the yellowish shade, two- or multi-stage bleaching processes, with FAS bleaching （F） included, were investigated in this paper. For single stage F bleaching, the better brightness of the bleached CTMP pulp of China fir was achieved at the ratio of NaOH to FAS being 1 ： 2. A brightness of 1 - 2 more points could be achieved by using F bleaching under the operation conditions of 90℃, 30 minutes comparing with the conditions of 30℃, 180 minutes. While comparing the bleaching efficiency of the two stage process （ FP and PF） ,the PF sequence,with a final brightness of 80.5% ISO, was 1 - 2 points higher than the FP sequence. The CTMP pulp of China fir could be bleached to a high brightness level of 82.8% ISO and had good brightness stability by using the three-stage bleaching process of PPF. Its strength property remained in a better level （ a tensile index of 28.2 N- m/g, a tear index of 4.70 mN·m2/g and a burst index of 1.62 kPa· m2/g） in comparison to that of the unbleached pulp （ a tensile index of 14.1 N·m/g, a tear index of 3.87 mN·m2/g and a burst index of 0. 94 kPa·m2/g）.