阳离子羟乙基瓜尔胶的合成及其造纸湿部应用

对一步泥浆法合成新型助留助滤剂———阳离子羟乙基瓜尔胶(CEG),及将其用于废新闻纸浆的抄造过程进行了探讨。悬浮于醇/水体系中的瓜尔胶,先与阳离子单体发生醚化反应,然后与氯乙醇在微过量碱催化剂存在下进行羟乙基化反应,阳离子中间产物不必分离。重点研究了阳离子醚化产物的黏度及氮质量分数的影响因素,确定了阳离子化反应优化条件为:m(阳离子单体)∶m(瓜尔胶)=0.4∶1,m(NaOH)∶m(瓜尔胶)=0.25∶1,反应温度60℃,反应时间2.5 h。经红外光谱分析,证实了接枝产物中季铵阳离子基团的存在。由于CEG分子结构同时含有季铵阳离子和非离子的活性羟基,CEG常温水合作用进一步强化,w(CEG)=1%的水溶液的透光率增加到80%。当以w(CEG)=0.2%(以绝干浆计)的用量添加到废新闻纸浆中,细小组分的单程留着率提高了40%,打浆度减少了37%。

Synthesis of Cationic Hydroxyethyl Guar Gum and Its Application in Wet-end Process of Papermaking

A new type drainage and retention aid—cationic hydroxyethyl guar gum(CEG) was synthesized in one-step and its application in the papermaking process of recycled newspaper pulp was discussed.Suspended in alchol/water solution,guar gum(GG)was grafted at first with quarternary-ammonium cationic monomer,and then reacted with chlorohydrin in the presence of tiny-excessive alkali catalyst.Optimal parameters of the cationic graft reaction were m(cationic monomer)∶m(GG)=0.4∶1,m(NaOH)∶m(GG)=0.25∶1,reaction temperature 60 ℃ and reaction time 2.5 hours.Infrared spectroscopy showed the modified guar gum carrying cationic group.Due to the quarternary-ammonium group as well as the active hydroxyl nonionic group,CEG was much easier to dissolve in water as compared with unmodified guar gum.The w(CEG)=1% aqueous solution exhibited good clarity with light transmittance of 80% at 625 nm and good viscosity stability.At the dosage of w(CEG)=0.2%(relative to dried pulp)in the paper pulp suspensions of recycled newspaper,the first past retention(FPR) was improved by 40%,and the drainage degree was reduced by 37%.