低甲醛释放脲醛树脂的合成温度与固化性能

针对低甲醛释放脲醛树脂固化速度慢的问题,在确定n(甲醛)∶n(尿素)=0.96∶1.00的优选合成工艺配方的基础上,采用正交试验优化低甲醛释放脲醛树脂不同反应阶段的合成反应温度,在兼顾胶黏剂胶接性能和环保性能的基础上,主要考查合成反应温度对低甲醛释放脲醛树脂胶黏剂固化速度的影响。结果表明:在合成低甲醛(F)/尿素(U)摩尔比脲醛树脂时,不同阶段的反应温度对树脂的固化速度有显著影响。当加成反应温度为90℃,缩聚前期反应温度为85℃,缩聚中期反应温度为75℃时合成的脲醛树脂胶黏剂,胶中游离甲醛质量分数在0.075%以下,固化速度明显加快,胶接性能优良,胶合板甲醛释放量为0.365 mg/L,达到GB/T 9846.3—2004中E0级要求,胶合板强度达到国家Ⅱ类板标准。

Temperature Processing Parameters and Curing Characteristics of Low-formaldehyde-emission Urea-formalde-hyde Resin

We studied the temperature of different stages affecting the curing characteristics of urea-formaldehyde using the or-thogonal test for decreasing the curing time of low-formaldehyde-emission urea-formaldehyde resin ( F/U=0.96) .The tem-perature had significant effect in different stages.The optimal synthetic conditions were under the addition stage of 90℃, prophase of condensation of 85℃, and condensation stage of 75℃.When the free formaldehyde content was under 0.075%, the curing time decreased substantially, the formaldehyde emission of the plywood was 0.365 mg/L in the requirement of E0 gradewood for GB/T 9846.3-2004, and the bonding strength of the plywood reached the National StandardⅡ.