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高邻位苯酚-甲醛树脂是当今应用较广泛的一种酚醛树脂。作者用Mg~(2+)、Zn~(2+)、Mn~(2+)、Ca~(2+)和Cu~(2+)等二价金属离子为催化剂,模拟工业上生产热塑性酚醛树脂的前阶段(回流期)定期测定苯酚及甲醛消失速率、pH值变化和GPC谱分析。结果表明镁离子催化速率比锌离子高,pH值在3.5至6.5范围内二价金属离子催化速率与pH无关,苯酚反应程度为0.2-0.6时反应遵循二级反应。导出了总反应的二级速率常数K_总和相应的活化能E_总。
High-ortho phenol-formaldehyde resin is now widely used as a phenolic resin. The author used divalent metal ions such as Mg2 +, Zn2 +, Mn2 +, Ca2 + and Cu2 + as catalysts to simulate the production of thermoplastic phenolic Pre-Resin Stage (Reflux Period) The phenol and formaldehyde disappearance rates, pH changes, and GPC spectral analyzes were periodically measured. The results show that the catalytic rate of magnesium ion is higher than that of zinc ion. The catalytic rate of divalent metal ion is independent of pH in the range of pH 3.5 to 6.5. The reaction follows the second order reaction when the phenol reaction degree is 0.2-0.6. The total activation energy E_ total of the second order rate constant K_ of the total reaction is derived.