反应介质对合成双酚A-苯胺型苯并噁嗪的影响

Influence of Reaction Media on Synthesis of Bisphenol-A-Aniline Based Benzoxazine

以多聚甲醛、苯胺和双酚A为原料,固定加料方式和反应温度等反应条件,改变溶剂种类和NaOH的用量,合成了双酚A-苯胺型苯并噁嗪树脂。采用1H NMR、凝胶化时间测试、DSC等方法对苯并噁嗪的结构、环化率和热固化行为进行了表征,研究了反应介质对苯并噁嗪合成反应的影响。实验结果表明,溶剂的介电常数越低或溶剂对原料双酚A或产物苯并噁嗪的溶解性越好,越有利于提高苯并噁嗪树脂的环化率和纯度;另外,随溶解多聚甲醛时所用NaOH用量的增加,苯并噁嗪的环化率、凝胶化时间和固化峰值温度都呈现先升高后降低的趋势,当NaOH质量分数(基于双酚A)为0.26%时,产物的环化率最高、凝胶化时间最长、固化峰值温度最高。

A series of bisphenol-A-aniline based benzoxazines were synthesized from paraformaldehyde, aniline and bisphenol-A by fixing feeding mode and reaction temperature, and changing solvents and NaOH solution dosage. The structure, oxazine ring content and thermal curing behavior of the benzoxazines were characterized by means of ^1H NMR, gelation time and DSC to study the influence of reaction media on the synthesis. It was found that the solvents with low dielectric constant or good solubility for the raw materials or products could improve the oxazine ring content and purity of the synthesized benzoxazines. With increasing NaOH dosage, which was used in dissolving paraformaldehyde, the oxazine ring content, gelation time and peak temperature of the DSC curves first increased and then decreased, and reached the maximum when 0.26%（w） NaOH was used.