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以对氯苯酚作为多亚甲基多苯基多异氰酸酯(PAPI)的封闭剂、二月桂酸二丁基锡和三乙胺作为复合催化剂,研究了催化剂、投料配比、加料方式、反应温度和反应时间等对封闭反应的影响。采用红外光谱(FT-IR)法和核磁共振(NMR)法对-NCO含量的变化情况进行分析,并采用FT-IR法测定解封闭温度。结果表明:对氯苯酚封闭PAPI的适宜反应条件为n(-OH)/n(-NCO)=1.03、n(二月桂酸二丁基锡)∶n(三乙胺)∶n(对氯苯酚)=0.2∶0.2∶100、反应温度为40℃、PAPI溶液滴加到对氯苯酚溶液中的滴加时间为1 h以及反应时间为1 h;对氯苯酚封闭异氰酸酯的解封闭温度为87℃。
Using p-chlorophenol as a sealant for polymethylene polyphenyl polyisocyanate (PAPI), dibutyltin dilaurate and triethylamine as a composite catalyst, the effects of catalyst, feeding ratio, feeding method, reaction temperature and reaction time Such as the impact of blocking reaction. The change of -NCO content was analyzed by FT-IR and NMR, and the solution temperature was determined by FT-IR. The results showed that the suitable reaction conditions for the blocking of PAPI with p - chlorophenol were n (-OH) / n (-NCO) = 1.03, n (dibutyltin dilaurate) 0.2: 0.2: 100, the reaction temperature was 40 ℃. The dropping time of PAPI solution to p-chlorophenol solution was 1 h and the reaction time was 1 h. The blocking temperature of p-chlorophenol blocked isocyanate was 87 ℃.