摘要： 用异氰酸酯三聚体与二羟甲基丙酸(DMPA)先进行扩链反应,再用3,5-二甲基吡唑(DMP)将剩余的异氰酸酯基封闭,然后用二甲基乙醇胺(DMEA)中和成盐,制得可水分散型封闭异氰酸酯固化剂(WBI),并讨论了封闭比例[n(—H)∶n(—NCO)]、DMPA用量、反应温度、反应时间对制备水分散型封闭异氰酸酯固化剂的影响。采用傅里叶变换红外光谱(FT-IR)和差示扫描量热法(DSC)对封闭固化剂的结构进行了表征及分析,结果表明得到了预定结构产物,并且制备的封闭型多异氰酸酯固化剂可在较低温度(130～150℃)实现解封。用合成的封闭异氰酸酯与环氧改性丙烯酸树脂制备了水性玻璃烘烤涂料,并对涂膜性能作了初步探讨。

关键词: 3,5-二甲基吡唑, 封闭多异氰酸酯, 固化剂

Abstract: A waterborne blocked polyisocyanate(WBI) curing agent was prepared by chain extension reaction of isocyanate trimer with dimethylol propionic acid ( DMPA), then the remaining -NCO groups were blocked with 3,5-dimethylpyrazole(DMP), and then neutralized with N,N-dimethylethanolamine(DMEA). The effects of mole ratio[n(—H): n(—NCO)], dosage of dimethylol propionic acid, reaction temperature and time on the blocking reaction were studied. The structure of blocked polyisocyanate was characterized by Fourier transfer infrared(FT-IR). Differential scanning calorimeter( DSC)was employed to investigate the unblocking temperature of WBl Results showed that blocked polyisocyanate could be unblocked at low temperature (130~150 ℃). The obtained WBI was mixed with waterbome epoxy modified acrylic resin to form aqueous baking coating for glass. The typical properties of the film were studied preliminarily.

Key words: 3, 5-dimethylpyrazole, blocked polyisocyanate, curing agent