Synthesis of Phenol-Urea-Formaldehyde Cocondensed Resins and Their Application

提出了一种新的合成酚醛脲醛共缩合树脂的方法，即将苯酚本身与一种甲醛与尿素摩尔比较高的脲醛树脂“uf浓缩物”反应。用C-13核磁共振光谱和凝胶渗透色谱对产物进行了分析。结果表明，在碱性条件下制备uf浓缩物，其缩合率和树脂中苯酚的掺入量均有所增加。对在酸性条件下制备的共凝树脂进行碱化处理，可以合成一种解析型共凝树脂。通过扭转编织分析研究了解析型缩合树脂的固化过程和热性能。溶胶型共凝树脂的固化性能和耐热性与商用树脂几乎相同。通过测定凝胶时间对温度的依赖关系得到的表观活化能与树脂的基本相同，而与UF树脂的差异较大。通过胶合板试验、循环沸水试验和72 h沸水试验对其粘接性能进行了评价。结果发现，它们可以通过特殊等级结构胶合板的JAS值。

A new synthetic method to obtain phenol-urea-formaldehyde cocondensed resins was developed by reacting phenol itself with so-called "UF-concentrate", which was a kind of urea-formaldehyde resins prepared with higher molar ratio of formalhyde to urea. The products were analyzed with C-13 NMR spectroscopy and gel permeation chromatography. The ratio of cocondensation and the amount phenol incorporated into cocondenced resin were found to increase, when the UF-concentrate was prepared under alkaline conditions. It was also found that a resol-type cocondensed resins can be synthesized by alkaline treatments of the cocondensed resins which were prepared under acidic conditions.Curing process and thermal properties of the resol-type cocondenced resins were investigated by torsional braid analysis. The resol-type cocondensed resins displayd almost the same curing behaviors and heat-resistance as a commercial resol. Their apparent activation energies determined by measuring temperature dependence of gel time were almost identical with that of resol, and quite different from that of UF resin. Their adhesive performances were evaluated by plywood test with a cyclic boiling test and a 72 hrs boiling test. It was found that they can pass a JAS value for the special grade structural plywood.