聚羧酸类减水剂活性大单体合成工艺

以聚乙二醇单甲醚-1200(MPEG 1200)与甲基丙烯酸(MAA)为原料,通过直接酯化反应制得聚羧酸类减水剂活性大单体聚乙二醇单甲醚甲基丙烯酸酯(MPEGMA 1200).通过正交实验,评价酸醇摩尔比、反应温度、催化剂质量分数(以聚乙二醇单甲醚质量计)、携水剂质量分数(以反应总质量计)、阻聚剂质量分数(以甲基丙烯酸质量计)、酯化时间对酯化率和双键摩尔分数的影响,确定合成MPEGMA 1200的最佳工艺条件,即酸醇摩尔比为2.0∶1,阻聚剂质量分数为2.5%,催化剂质量分数为4%,携水剂质量分数为40%,反应温度为130℃,反应时间为6h.在此条件下,其酯化率达到98.9%,双键摩尔分数为91.1%.

Research of the Synthesis Process of Polycarboxylate Water-Reducer Active Macromonomer

The active macromonomer,methoxy polyethylene glycol methacrylate-1200(MPEGMA 1200),used for polycarboxylate high performance water-reducer,was synthesized by direct esterification taking methacrylic acid(MAA) and methoxy polyethylene glycol-1200(MPEG 1200) as raw materials.Through the orthogonal experiments,comprehensive evaluation of mole ratio of MAA to MPEG,dosage of catalyst,polymerization inhibitor and water-carrying agent,reaction temperature and time on esterification were investigated with the esterification rate and double bond mol fraction as measurement indexes.The optimum conditions of synthesizing MPEGMA 1200 were confirmed as follows: mole ratio of MAA to MPEG was 2.0∶1,dosage of polymerization inhibitor was 2.5% of MAA quality,dosage of catalyst was 4% of MPEG quality,dosage of water-carrying agent was 40% of the total reactant quality,the reaction time was 6 h,and reaction temperature was 130 ℃.Under these conditions,the esterification rate was 98.9% and the double bond mol fraction was 91.1%.