Abstract: A kind of blocked isocyanate adduct was synthesized by using methylparaben as blocking agent and N,N'-dimethylformamide (DMF) as solvent. The effects of molar ratio of blocking agent and toluene-2,4-diisocyanate (TDI)，mass percent of catalyst，reaction temperature and reaction time on the blocking reaction were investigated. A high conversion of 99.81% for —NCO group was obtained，when molar ratio of blocking agent and TDI was 3.0∶1，reaction temperature was 80 ℃，reaction time was 3 h and mass percent of catalyst was 0.5% (based on total mass of blocking agent and TDI). Fourier transform infrared spectrometry (FTIR) and nuclear magnetic resonance (NMR) were used to determine the structure of the adduct. Differential scanning calorimetry (DSC) results showed that the adduct began to deblock at 80 ℃ while deblocking peak temperature was 124.7 ℃ and throughout deblocking temperature was 130 ℃.

Key words: methylparaben, isocyanate reaction, blocking agent preparation, deblocking reaction

摘要： 用N,N'-二甲基甲酰胺（DMF）作溶剂，对羟基苯甲酸甲酯作封闭剂，研究了其封闭甲苯-2,4二异氰酸酯（TDI）中封闭剂与TDI摩尔比、催化剂用量、反应温度与时间对封闭反应的影响。研究发现：当封闭剂与TDI摩尔比为3.0∶1、添加0.5%（基于TDI与封闭剂总质量）催化剂、反应温度80 ℃、反应3 h时能够获得99.81%的高封闭率。DSC测试显示，封闭产物在80 ℃以后即开始出现解封闭，但解封的高峰温度在124.7 ℃，完全解封的温度为130 ℃；利用红外光谱和核磁共振测试确定了封端产物的结构。

关键词: 对羟基苯甲酸甲酯, 异氰酸酯反应, 封闭剂制备, 解封反应