甲乙酮肟封闭聚氨酯预聚体的研究

Study on Polyurethane Prepolymer Blocked With Methyl Ethyl Ketoxime

首先用聚己二酸-1,4-丁二醇酯二醇和甲苯二异氰酸酯(TDI)制备端异氰酸酯预聚体,然后用甲乙酮肟封闭预聚体的异氰酸酯基团。用化学分析方法研究了封闭反应温度、反应时间以及物料的配比对异氰酸酯基团封闭率的影响,用红外光谱仪研究了封闭前、封闭后和加热解封后的预聚体异氰酸酯基团特征吸收峰的变化。实验结果表明:随反应温度的升高、反应时间的增加或N(活泼-H)/N(-NCO)增加,异氰酸酯基团封闭率增大;在80℃,N(活泼-H)/N(-NCO)=1.2,反应4 h的条件下,甲乙酮肟可完全封闭异氰酸酯基团;甲乙酮肟封闭的聚氨酯预聚体能在135℃下解封。

Isocyanat-terminated polyurethane prepolymer was synthesized from poly-1,4-butylene adipate glycol and toluene diisocynate （TDI）,then isocyanate-group of the prepolymer was blocked with methyl ethyl ketoxime as blocking agent. Effects of reaction temperature, reactant mole ratio and reaction time on the blocking reaction were studied by chemical analysis, and the change of characteristic absorption peak of the isocyanate groups before and after the blocking and after deblocking by heating was also studied by infiared spectrometer. The results show that, the blocking rate of isocyanate group increases with the increase of reaction temperature and reaction time. The isocyanate group can be completely blocked with methyl ethyl ketoneoxime under the condition of reaction temperature 80 ℃, -H/-NCO=1.2, reaction time 4 h; The blocked polyurethane prepolymer can be deblocked at 135 ℃.