聚羧酸系减水剂大单体最佳酯化条件的确定

Determination of the Optimal Esterification Condition of Macromonomer for Polycarboxylate Superplasticizer

采用聚乙二醇单甲醚(MPEG)和甲基丙烯酸(MAA)为原料,对甲苯磺酸(PTSA)为催化剂,吩噻嗪(PTZ)为阻聚剂,在通氮气赶水的条件下通过酯化反应制备聚羧酸系减水剂大单体聚乙二醇单甲醚甲基丙烯酸酯(MPEGMA)。采用单因素试验方法,以酯化率为衡量指标,考察了酸醇物质的量比(n(MAA)∶n(MPEG))、催化剂用量、阻聚剂用量、酯化温度和酯化时间对酯化反应的影响,得出最佳酯化条件:n(MAA)∶n(MPEG)为2.5,催化剂用量为MAA和MPEG总质量的3%,阻聚剂用量为MAA质量的2.5%,酯化温度为120℃,酯化时间为6 h,产物酯化率可达95.65%。采用正交试验对上述结论进行了验证,试验结果具有较好的一致性和可行性。大单体的红外分析结果进一步说明酯化效果较好,为目标产物。

The macromonomer,methoxy polyethylene glycol methacrylate ester（MPEGMA） used for preparation of polycarboxylate superplasticizer was prepared by esterification of methacrylic acid（MAA） and methoxy polyethylene glycol（MPEG）,using p-toluene sulfonic acid（PTSA） as catalyst and phenothiazine（PTZ） as inhibitor,under the condition that water formed in the reaction was removed by nitrogen.The effects of mole ratio of MAA to MPEG（n（MAA）∶n（MPEG））,amount of catalyst and inhibitor,esterification temperature and time on esterification reaction were investigated with the esterification rate as measurement index through single factor experiments.The esterification ratio reaches 95.65% under the optimum experiment conditions that n（MAA）∶n（MPEG） is 2.5,the amount of catalyst is 3% according to the mass of MAA and MPEG,the amount of inhibitor is 2.5% according to the mass of MAA,the esterification temperature is 120 ℃ and the esterification time is 6 h.In addition,a proper orthogonal test was designed to confirm the above conclusion.The result reveals that the orthogonal trial consequent has an agreement with the outcome of single factor tests,which further proves the consistency of the test results.The infrared analysis of macromonomer shows that the esterification production has preferably prepared as having a higher rate of esterification.The researching results have a reference meaning in the preparation of macromonomer used for polycarboxylate superplasticizer as well as a certain guiding significance on the practical application.