三氯苯酚与PAPI封闭反应的条件

Blocking Reaction of 2,4,6-trichlorophenol and PAPI

以2,4,6-三氯苯酚作为多亚甲基多苯基多异氰酸酯(PAPI)的封闭剂,获得了单组份聚氨酯.讨论了—OH与—NCO的摩尔比、反应温度、溶剂、反应时间、催化剂等因素对异氰酸酯封闭反应的影响,利用红外光谱分析手段进行了表征.结果表明:较适宜的封闭剂与异氰酸根的摩尔比为(1.1～1.2)∶1.0;升高温度有利于封闭反应的进行,较佳的反应温度为80℃;极性溶剂有利于封闭反应的进行,溶剂的极性越大,封闭反应越容易进行;延长反应时间,有利于提高封闭率,但到一定程度,反应趋于平衡;添加有机锡类催化剂能大大提高封闭反应的速率,缩短封闭反应时间.对封闭物进行了1HNMR表征.

One-component polyurethane was obtained by 2,4,6-trichlorophenol as a blocking reagent of polymethylene polyphenlene isocyanate（PAPI）.The effects of molar ratio of —OH/—NCO,reaction temperature,solvent,reaction time and catalyst on this blocking reaction were discussed.Fourier transform infrared（FTIR） was used to characterize these blocking adducts.Experimental results showed that it was propitious to the blocking reaction when the optimal molar ratio of —OH/—NCO was（1.1～1.2）∶1.0 and the optimal reaction temperature at 80 ℃.Meanwhile,experimental results also exhibited that the polar solvents could accelerate the blocking reaction and the reaction velocity was faster when the solvent polarity was stronger,and that it made for increasing blocking rate when the reaction time was prolonged,but to some extent,the reaction reached the equilibrium.In addition,experimental results also showed that the catalysts of organic tin could quicken significantly the blocking reaction velocity and reduced the blocking reaction time.TCP-blocked PAPI adduct was characterized by1HNMR.