脲醛树脂胶粘剂~(13)C核磁共振分析

采用常规化学分析和13C核磁共振相结合的方法,分析研究了脲醛树脂胶粘剂性能与结构的关系。结果表明:在摩尔配比F:U=1.2:1时,粘度越高,游离尿素的含量越低,羟甲基的含量越低,游离甲醛含量降低; 树脂产品的粘度低,聚合度也低,羟甲基的含量偏高,粘接性能下降,同时游离甲醛含量上升,而适量苯酚的添加可改善树脂结构,是一种优化树脂的途径。当增大摩尔配比到F:U=1.4:1时,尿素含量下降,游离甲醛含量上升。因此,摩尔配比的选择在很大程度上影响脲醛树脂的性能。

13C NMR spectra analysis of urea-formaldehyde resin

The routine chemical analysis means and 13CNMR spectra were employed to learn the relations of structure and quality of UF resin. The results show that under low mole ratio (F:U), if the resin had high viscosity and high solid-content it would have low contents of free urea, hydroxymethyl and free formaldehyde; if its degree of polymerization was small and the viscosity was low, then the contents of hydroxymethyl and free formaldehyde would be high, and at the same time the agglutinative intension of the UF resin would not be good. However, the resin can be improved by adding just the right amount phenol. With the F:U mole ratio increasing to 1.4:1, the free urea dropped down and free formaldehyde went up. So the ratio influences the quality of the UF resin in a great deal.