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羧甲基纤维素钠(CMC)是一种能改善纸张强度的重要纸机湿部添加剂。以桑枝皮纤维为原料制备2种取代度(DS)的CMC,并将其与聚丙烯酰胺(CPAM)一起添加到针叶木浆中,研究不同取代度桑枝皮CMC及其用量对纸张强度的影响,探讨桑枝皮CMC和CPAM 2种助剂在纸机湿部的协同效应。结果显示桑枝皮CMC能改善纸张的强度,但其效果因桑枝皮CMC取代度及用量不同而有所差异。添加DS为0.97的桑枝皮CMC时,当用量占绝干浆质量0.4%～0.8%的范围内均可使纸页的抗张强度显著提高,其中用量为绝干浆质量的0.8%时达最大;当桑枝皮CMC的添加量低于绝干浆质量的0.4%时,对纸张耐破度、撕裂度和耐折度等强度指标影响不大,纸张强度改善主要是CPAM添加的作用。在纸机湿部添加DS为0.52的桑枝皮CMC时,对纸张的强度改善效果不明显。研究结果提示,应用阴离子桑枝皮CMC和阳离子CPAM作为纸机湿部添加剂改善纸张强度,须将桑枝皮CMC的取代度和用量控制在合适范围内才能发挥2种添加剂的协同作用。
Sodium carboxymethyl cellulose (CMC) is an important paper machine wet-end additive that improves paper strength. Two kinds of CMC (DS) were prepared from mulberry bark fiber, and were added into softwood pulp together with polyacrylamide (CPAM) to study the effects of different degrees of substitution mulberry bark CMC and its dosage on paper strength The synergistic effect of the two kinds of additives of mulberry bark CMC and CPAM on the wet part of paper machine was discussed. The results showed that mulberry bark CMC can improve the strength of the paper, but the effect of mulberry bark CMC substitution degree and the amount of different. When the mulberry bark CMC with DS of 0.97 was added, the tensile strength of the paper was significantly improved when the amount of dry mulberry pulp was 0.4% ~ 0.8%, and the dosage was 0.8% Maximum; when the mulberry bark CMC added less than the quality of dry pulp 0.4%, the paper burst strength, tear and folding resistance and other strength index has little effect, paper strength improvement is mainly the role of CPAM . When adding wet mulberry bark CMC whose DS is 0.52 in the wet part of the paper machine, the effect of improving the strength of the paper is not obvious. The results suggest that the application of anionic mulberry bark CMC and cationic CPAM as a wet paper machine additives to improve paper strength, the mulberry bark CMC should be controlled in the appropriate degree of substitution and dosage within the synergy can play two additives.