不同固化剂下低摩尔比脲醛树脂热行为及胶接胶合板性能

通过对3种固化剂下5种低摩尔比脲醛树脂进行热分析和胶合板制造实验,研究了摩尔比、游离甲醛含量、固化剂种类等对低摩尔比脲醛树脂胶粘剂固化反应起始温度、峰顶温度、终止温度和胶合板胶合强度及其甲醛释放量的影响。实验结果表明:1)与传统的氯化铵固化剂相比,过硫酸铵催化的脲醛树脂的热分析曲线的起始温度和峰顶温度都很低,显示出良好的固化促进作用;2)以过硫酸盐作固化剂时,低摩尔比脲醛树脂固化过程中起始温度和峰顶温度受摩尔比的影响较小;3)摩尔比为1．0的脲醛树脂胶接胶合板的胶合强度也能够满足GB／T 9846．3-2004Ⅱ类胶合板的要求;4)用过硫酸盐作固化剂制备的胶合板的甲醛释放量较低。

Thermal behavior of low molar ratio urea-formaldehyde resins and properties of the bonded plywood

This paper studies the effects of molar ratio,free formaldehyde content,and cure agents on onset temperature, peak temperature, and endset temperature of low molar ratio urea-formaldehyde (LUF)resins curing reaction and bonding strength and formaldehyde emission of plywood by analyzing thermal behavior of LUF resins and manufacturing plywood. The results indicate that:1)Compared with traditional cure agent-ammonium chloride, LUF resins catalyzed by ammonium persulphate have lower temperatures of exotherm,revealing much faster curing rate;2)0nset temperature and peak temperature of exotherms of LUF resins using persulphate salts as cure agents are less affected by molar ratio;3)Plywood prepared using LUF resins with 1.0 molar ratio can meet the GB/T 9846.3-2004 requirement;4)The formaldehyde emission of plywood using LUF resins catalyzed by persulphate salts is lower.