聚醚二元醇与异氰酸酯封端反应的研究

Study on the Blocking of Polyetherglycols and Isocyanate

以聚醚二元醇和二苯甲烷二异氰酸酯(MDI)为原料合成预聚体,分别以丙酮肟、甲乙酮肟、丁二酮肟和硝基甲烷作为封闭剂,制备了二苯甲烷二异氰酸酯固化剂。用于阴极电泳涂料,以降低固化温度。利用化学滴定、红外光谱和热重分析(TG)等分析手段对预聚体和异氰酸酯固化剂进行了表征和分析。实验结果表明解封反应时间及解封温度与封闭剂种类有关,甲乙酮肟封闭的异氰酸酯固化剂的解封温度最低,为130℃,解封时间为20 min。

Prepolymers were synthesized from polyether diol and MDI.Acetone oxime,methyl ethyl ketoxime,dimethylglyoxime and nitromethane were used as blocking agent to prepare MDI curing agents,which can be used for cathodic electrophoretic coatings to reduce curing temperature.The structures of prepolymers and isocyanate curing agents were characterized by chem-titrimetry,IR spectroscopy and TG.The results showed that the deblocking time and deblocking temperature depeaded on the blocking agent.Deblocking temperature of MDI curing agent with methyl ethyl ketoxime as blocking agent was the lowest.It deblocked at 130 ℃ after 20 min.