小粒径酚醛树脂微球的制备

以苯酚(P)、甲醛(F)为原料，氢氧化钠(C)为催化剂，Span-80为表面活性剂，(NH₄)₂S₂O₈为添加剂，采用W/O静置反相乳化法合成酚醛树脂微球。研究了添加剂(NH4)2S2O8、表面活性剂Span-80、催化剂氢氧化钠的用量及原料液中水溶性酚醛树脂的体积分数对微球形貌和平均直径的影响。结果表明,(NH₄)₂S₂O₈的加入能够调节聚合反应速率；微球的平均直径随着(NH₄)₂S₂O₈和Span-80用量的增加而增大；降低原料液中水溶性酚醛树脂的体积分数能有效减小微球的粒径。当合成条件为n_P∶n_F=1∶2，n_C/n_P=0.05，过硫酸铵与2mL原料液中氢氧化钠的物质的量比3.6∶1，原料液中水溶性酚醛树脂的体积分数66.67%，Span-80 2g，乳化比1/14时，室温磁力搅拌1h，超声3min，合成温度为100℃，反应12h就能得到形貌好、平均直径为1.13μm的酚醛树脂微球。

Preparation of small sized phenolic resin microspheres

Phenolic resin microspheres have been prepared from the polymerization of phenol and formaldehyde by a reverse emulsion method using sodium hydroxide and Span-80 as the catalyst and surfactant, respectively. The factors that affect the morphology and average size, such as the amount of ammonium persulphate, Span-80, sodium hydroxide and the volume fraction of soluble phenolic resin in the raw solution were studied. The results showed that amount of ammonium persulphate affected the rate of polymerization, and the particle size increased with increasing amounts of ammonium persulphate and Span-80, but decreased with decreasing volume fraction of soluble phenolic resin in raw solution. When the molar ratio of phenol to formaldehyde was 1 to 2, the molar ratio of catalyst to phenol was 0.05, the molar ratio of ammonium persulphate to catalyst in 2mL of water soluble phenolic resin was 3.6 to 1, the volume fraction of soluble phenolic resin in raw solution was 66.67%, the amount of Span-80 was 2g, and the volume ratio of raw solution to oil was 1 to 14, with stirring for 1h, ultrasonication for 3min and heating for 12h at 100℃. The resulting phenolic resin microspheres had good morphology, with an average size of 1.13μm.