羧甲基羟丙基瓜尔胶合成新工艺及性能

为解决羧甲基羟丙基瓜尔胶(CMHPG)合成过程中副产物多,容易糊化的问题.以丙酮为反应介质,甲醇钠为催化剂代替乙醇、异丙醇为介质,氢氧化钠为催化剂.探讨了工艺条件对产品的影响,找出了较佳工艺条件.结果表明,合成较佳工艺条件为:环氧丙烷与瓜尔胶质量比为0.2∶1、氯乙酸与瓜尔胶质量比为0.4∶1,反应时间为160 min；前者催化剂与瓜尔胶质量比为0.2∶1、反应温度为45～50℃,后者催化剂与瓜尔胶质量比为0.3∶1,反应温度为65～ 70℃.乙醇、异丙醇为介质,氢氧化钠为催化剂合成产品的羧甲基取代度为0.43,羟丙基取代度为0.36,粘度为1 120mPa·s；以丙酮为反应介质,甲醇钠为催化剂合成产品羧甲基取代度为0.48,羟丙基取代度为0.37,粘度为1 030 mPa·s.

New Synthesis Process and Performance of Carboxylmethylhydroxypropyl Guar Gum

In order to solve problems of many by-products and easily gelatinization in the synthesis process of carboxylmethylhydroxypropyl guar gum(CMHPG),acetone and sodium methylate were used as medium and catalyst respectively to replace ethanol and isopropanol,and sodium hydroxide.Effect of process conditions on products was investigated,suitable process conditions were obtained.The results show that the suitable synthesis condition is as follows: the mass ratio of propylene oxide and guar gum is 0.2︰1,and the mass ratio of chloroacetic acid and guar gum is 0.4︰1,the reaction time is 160 min.The mass ratio of catalyst and guar gum is 0.2︰1,and reaction temperature is 45～50 ℃ in the former.The mass ratio of catalyst and guar gum is 0.3︰1,temperature is 65～70 ℃ in the later.Substitution degree of carboxymethyl is 0.43,and that of hydroxypropyl is 0.36,the product viscosity is 1 120 mPa·s using ethanol,isopropanol as medium,sodium hydroxide as catalyst.The substitution degree of carboxymethyl is 0.48,and that of hydroxypropyl is 0.37,the product viscosity is 1 030 mPa·s using acetone as medium,sodium methylate as catalyst.