反应条件对GUF树脂合成及动态热机械性能的影响研究

选用乙二醛(G)部分取代甲醛(F)与尿素(U)反应制备乙二醛-尿素-甲醛(GUF)共缩聚树脂，探究不同反应条件对所合成GUF树脂基本性能的影响规律，用动态热机械性能分析方法(DMA)对人造板的热压过程进行模拟和树脂的固化过程进行监测，并以此为依据优化GUF树脂的合成条件，用优化条件下合成的GUF树脂制备胶合板并测定其力学性能及甲醛释放量。结果表明：GUF树脂的较优合成条件为乙二醛与尿素先在pH为4.0~5.0，于70~80 ℃保温反应1 h，乙二醛、尿素、甲醛的物质的量比n_G:n_U:n_F为0.7:1.0:0.7，再加入甲醛于pH为5.0~6.0保温反应2 h；在优化条件下合成的GUF树脂固化后其储存模量达到13 976 MPa，以其胶合的胶合板胶合强度能满足国标GB/T 9846.3—2004对Ⅲ类胶合板干状胶合强度的要求，甲醛释释放量也能满足国标GB/T 9846.3—2004对E0级胶合板的要求，可以直接用于室内并在干燥状态下使用。

Effects of Reaction Conditions on Synthesis and Dynamic Thermo-mechanical Properties of GUF Resin

Glyoxal (G) partially substituted for formaldehyde (F) and urea (U) to prepare GUF co-condensed resin. The effects of synthesis conditions on the basic properties of the GUF resins were studied. Dynamic thermo-mechanical analysis(DMA)was used to simulate the hot press process of the GUF-bonded plywood panels and investigate the curing property of the GUF resins. Then the mechanical properties and formaldehyde emission of the plywood panels bonded with the GUF resins prepared under the optimized condition were studied. And these results indicated that the optimum synthesis condition of GUF resin was that glyoxal and urea react was 70-80 ℃ for 1 hour when its pH value was 4.0-5.0, then adding formaldehyde and react for 2 h when its pH value was 5.0-6.0 and nG:nU:nF is 0.7:1.0:0.7. Under the optimized conditions, the dry internal bond strength and formaldehyde emission of the GUF-bonded plywood panels could meet the relative requirement of China national standard GB/T 9846.3-2004, and the panels could be directly used indoor under dry conditions.