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采用TEMPO/NaBr/NaClO体系将机械浆长纤维糖基单元中的伯羟基选择性氧化成羧基来提高纸浆纤维羧基的含量。研究了TEMPO、NaBr和NaClO的用量以及浆浓对纸浆纤维氧化的影响,同时研究了羧基含量对机械浆长纤维性能的影响。结果表明,在氧化过程中,随着TEMPO和NaBr用量的增加,反应速度提高,而氧化后的纸浆纤维羧基含量没有增加,随着NaClO用量的增加,纸浆纤维的羧基含量上升。随着纸浆纤维浓度的增加,羧基含量先上升后下降,浆浓在1.3%时,羧基含量达到最高值。随着纸浆纤维羧基含量的增多,浆料抄片的抗张指数和耐破指数上升,撕裂指数下降,氧化的纸浆纤维对细小纤维的留着率下降;浆料的保水值上升而游离度下降;浆纤维的卷曲和扭曲系数降低。研究还发现,低羧基含量的纤维能够吸附部分有机溶解物以及其他物质,使得白水中的有机溶解物和总有机碳的含量下降,这种吸附性能随着羧基含量的增加而下降。
The TEMPO / NaBr / NaClO system was used to selectively oxidize the primary hydroxyl groups in the long fiber glycosyl units of the mechanical pulp into carboxyl groups to increase the carboxyl content of pulp fibers. The effects of the amount of TEMPO, NaBr and NaClO and the pulp consistency on pulp fiber oxidation were investigated. The effect of carboxyl content on the mechanical properties of long fiber pulp was also studied. The results showed that with the increase of TEMPO and NaBr, the reaction rate increased while the carboxyl content of the oxidized pulp fiber did not increase with the increase of the amount of NaClO. The carboxyl content of pulp fiber increased with the increase of the dosage of TEMPO and NaBr. With the increase of pulp fiber concentration, the carboxyl content first increased and then decreased, and the content of carboxyl reached the highest value when the pulp consistency was 1.3%. With the increase of the carboxyl content of the pulp fiber, the tensile index and burst index of the pulp sheet increase, the tear index decreases, the retention of the oxidized pulp fiber to the fine fibers decreases; the water retention of the pulp increases and the degree of freeness Decreased; the crimp and twist coefficient of the pulp fiber decreased. The study also found that the low carboxyl content of fiber can absorb some of the organic dissolved matter and other substances, making white water organic matter content and total organic carbon decreased, the adsorption properties with the carboxyl content increases.