覆膜砂用苯并恶嗪树脂软化-固化性质

Properties of Soften-cured of Benzoxazines Used for Precoated Sand

通过测试苯并恶嗪树脂的聚合速度和软化点,优选了覆膜砂用苯并恶嗪树脂的合成工艺为95℃保温3h。测试了该树脂90℃的熔融粘度-时间曲线,熔融粘度稳定在0.5Pa.s。分别研究了该树脂加促进剂和不加促进剂两种情况下温度与聚合速度的关系,并测试了树脂的DSC曲线。结果表明,该树脂在200℃存在一个明显放热峰。200℃的树脂固化度高于90%,当温度高于200℃时,树脂的聚合速度变化开始变缓。合成的苯并恶嗪树脂的软化和固化特性都可以满足目前覆膜砂的制备要求。

The benzoxazines used for precoated sand were optimally synthesized at 95℃ for three hours by measuring its gel time and soften point.The results reveal that molten viscosity keeps about 0.5 Pa·s by measuring molten viscosity-gel time curves at 90 ℃.The relationship between temperature and gel time of the benzoxazines with and without accelerating agent was investigated.In addition,the DSC curves of benzoxazines were examined.It was found that there exists a apparent thermo-positive peak,and the cured degree of the pre-coated sand is more than 90% at 200 ℃.The gel time of the resin becomes slow with temperature more than 200 ℃.The soften and cured properties of synthesized benzoxazines can meet the preparing requirement of pre-coated sand.