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选用弱酸-弱碱-弱酸-弱碱工艺制备脲醛树脂(UF)胶粘剂,研究了n[甲醛(F)]∶n[尿素(U)]、初始p H、反应温度和三聚氰胺(M)掺量对游离F含量和胶接强度的影响。研究结果表明:当n(F)∶n(U)=1.2∶1.0、起始p H为6.5、反应温度为85℃和w(M)=6%(相对于U总质量而言)时,UF胶粘剂的游离F含量(0.17%)符合国家标准要求(≤0.3%),胶合板的F释放量(1.17 mg/L)达到GB/T 9846.3—2004标准中E1级指标要求(≤1.5 mg/L),胶接强度(从0.46 MPa提高到0.97 MPa)达到了国家标准中II类胶合板的指标要求,耐水性也明显提高。
UF adhesive was prepared by weak acid - weak base - weak acid - weak base technology. The effects of n [formaldehyde (F)]: n [urea], initial p H, reaction temperature and the content of melamine On the content of free F and the bonding strength. The results show that when n (F): n (U) = 1.2:1.0, the initial p H is 6.5, the reaction temperature is 85 ℃ and w (M) = 6% with respect to the total mass of U, The free F content (0.17%) of UF adhesive meets the requirements of national standard (≤0.3%) and the release amount of plywood (1.17 mg / L) reaches the E1 grade index of GB / T 9846.3-2004 (≤1.5 mg / L ), The bonding strength (from 0.46 MPa to 0.97 MPa) reached the national standard of class II plywood index requirements, water resistance is also significantly improved.