Abstract: The curing reaction of bisphenol A epoxy resin and isocyanate was carried out and the curing mechanism was investigated.Differential scanning calorimetry(DSC)and Fourier transform infrared spectroscopy(FTIR)were used to monitor and analyze quantitatively the decrease of the groups of isocyanate，epoxy group and generation of new groups of isocyanurate and oxazolidone.The DSC results showed that three reactions mainly occurred during the curing process of epoxy/isocyanate system corresponding to three exothermic peaks.The FTIR results indicated that when reaction temperature was below 140℃ trimerization of isocyanate groups into isocyanurate was observed；when temperature was up to 200℃ the formation of oxazolidone ring by the reaction between epoxy and isocyanate occurred；when temperature was above 230℃ the transformation reaction of isocyanurate with epoxide group to oxazolidone occurred.The curing reaction time dependence of the conversions of epoxide，isocyanate，isocyanurate，oxazolidone groups at different temperature were studied.

Key words: isocyanate, epoxy, isocyanurate, oxazolidone, curing mechanism

摘要： 详细研究了异氰酸酯/环氧树脂体系的固化反应和固化机理。采用差示扫描量热法（DSC）和红外光谱法（FTIR）跟踪了异氰酸酯/环氧树脂固化反应过程，定量分析了异氰酸酯、环氧基团和新生成的异氰脲酸酯和口恶唑烷酮的变化。DSC分析结果表明，DSC曲线上出现3个放热峰，说明固化过程中存在至少3种反应；FTIR分析结果表明，在140℃以下固化体系主要发生异氰酸酯的三聚反应生成三嗪环（异氰脲酸酯）；在200℃下，异氰酸酯—NCO基团与环氧基团开环反应生成口恶唑烷酮；在230℃ 下，三嗪环（异氰脲酸酯）进一步与环氧基团开环反应生成口恶唑烷酮。研究了不同温度下环氧基团、异氰酸酯基团、异氰脲酸酯基团、口恶唑烷酮基团随反应时间的变化规律。

关键词: 异氰酸酯, 环氧树脂, 异氰脲酸酯, 口恶唑烷酮, 固化机理