弱酸性起始条件合成聚乙烯醇改性脲醛树脂胶黏剂的工艺及性能研究

Study on the Process and Properties of Urea-formaldehyde Resin Adhesive Modified by Synthesized Polyvinyl Alcohol under Initial Weak Acidity Condition

用聚乙烯醇(PVA)作为改性剂,在不同的弱酸性条件下合成脲醛树脂(UF),并用正交实验法得出了弱酸性起始条件合成聚乙烯醇改性脲醛树脂的最优工艺为:最终n(甲醛):n(尿素)=1.2:1、起始pH值为6.5、碱性阶段反应温度85℃、PVA加入量占尿素总量1%。用该工艺制备的PVA改性UF的游离甲醛含量、胶合强度均能满足GB/T 14732-2006标准要求,并且相应胶合板的甲醛释放量为4.80mg/L,达到了GB/T 9846.3-2004标准中E_2级指标要求。

With polyvinyl alcohol（PVA） as modifier,the synthesis technology of urea-formaldehyde resin（UF） under different initial weak acidity conditions was studied through an orthogonality experiment.The results indicated that the UF resin modified by PVA satisfied the standard of GB/T 14732—2006 and the formaldehyde emission（4.80mg/L） of corresponding plywood reached the E_2 level index requirement in GB/T9846.3—2004 standard when final molar ratios of n（F）：n（U） was 1.2：1.the initial pH was 6.5.the temperature of alkaline stage reaction was 85℃ and mass fractions of PVA was 1%in total urea.