Ozone Bleaching of Kraft Pulp
Ozone Bleaching of Kraft Pulp
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牛皮纸浆的臭氧漂白
DOI：
10.2524/jtappij.51.1908
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
S. Hosoya
中科院分区：
文献类型：
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作者：
K. Magara;I. Takano;S. Hosoya
近年来，全世界纸浆和造纸工业最关心的问题之一是使用氯基漂白化学品的漂白厂排放的有机氯化合物。尽管目前对有机氯化合物的毒性还存在一些争论，但硫酸盐浆漂白技术的发展趋势是向少氯或无氯漂白方向发展，其中臭氧作为一种强有力的脱木素剂已被公认。然而，臭氧漂白的缺点之一被认为是其对纤维素的非选择性降解，这导致纸浆的粘度下降。在这种情况下，它是由Union Camp公司使用高浓臭氧漂白，即使在漂白过程中降低纸浆粘度，纸浆保持可接受的强度性能，但粘度的值没有显示由作者为了确认粘度下降和强度性能的关系，使用中浓混合器进行硫酸盐浆臭氧漂白。阔叶木硫酸盐浆（LKP）和氧漂阔叶木硫酸盐浆（LKOP）在1%臭氧用量下可漂至卡伯值小于3，粘度大于20mPa.s，针叶木硫酸盐浆（NKP）和氧漂针叶木硫酸盐浆（NKOP）在过量臭氧用量下可漂至卡伯值小于4，粘度大于13mPa.s。臭氧漂白浆的强度性能优于氯漂浆。另外，臭氧漂白的纸浆，即使在粘度不理想的情况下，也能保持较好的强度性能，而甲醇的加入可以防止纸浆粘度的急剧下降，使纸浆的粘度保持在30mPa·s以上。然而，在强度性能上没有发现任何优势，从这些结果中，我们认为纸浆粘度和强度性能的臭氧漂白纸浆与氯漂白纸浆不同的关系。因此，似乎臭氧能够漂白硫酸盐浆而不添加任何纤维素保护剂。
Recently, one of the greatest concerns of the world wide pulp and paper industries has been organo-chloro compounds discharged from bleach plants which use chlorine based bleaching chemicals. Although there are some debates on toxicities of organo-chloro compounds, we can find a distinct tendency in developing kraft pulp bleaching technologies which are facing toward less-chlorine or non-chlorine bleaching.Among them, ozone has been recognized as a powerful delignifying reagent. However, one of the drawbacks of ozone bleaching is considered to be its non-selective degradation of cellulose, which leads to the viscosity drops of the pulps. In this situation, it was revealed by Union Camp corporation using high consistency ozone bleaching that even if the pulp viscosities were reduced during the bleaching, the pulps maintained acceptable strength properties, but the values of the viscosities were not shown by the authors.To confirm the relationship of viscosity drops and strength properties, ozone bleaching of kraft pulps was carried out using a medium consistency mixer. Hardwood kraft pulps (LKP) and oxygen-bleached hardwood kraft pulps (LKOP) were successfully bleached to the kappa number below 3 keeping the viscosity above 20 mPa.swith 1% ozone charge.Softwood kraft pulp (NKP) and oxygen-bleached softwood kraft pulp (NKOP) could also be bleached to the kappa number below 4 keeping the viscosity above 13 mPa.s with excess ozone charge. It was also shown that ozone-bleached pulps kept enough strength properties compared to those of the chlorine-bleached pulps. Furthermore, even the pulps which were bleached with an excess amount of ozone maintained the acceptable strength properties although the viscosities were unacceptable level.On the other hand, the severe viscosity reduction could be protected with addition of methanol and the viscosities were kept above 30mPa-s. However, no advantage in strength properties over the non-protected pulps was found.From these results, we consider that the relationship between pulp viscosities and the strength properties of ozone-bleached pulps differs from that of chlorine-bleached pulps. Therefore, it seems that ozone is capable of bleaching kraft pulps without addition of any cellulose protector.