E_1级胶合板用改性脲醛树脂胶粘剂的制备方法研究

Study on preparation method of modified urea-formaldehyde resin adhesive for E_1 grade plywood

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。

The urea-formaldehyde resin（UF）adhesive was prepared by weak acid-weak alkali-weak acid-weak alkali technology,the influences of molar ratio of n[formaldehyde（F）]∶n[urea（U）],initial p H value,reactiontemperature and melamine（M）content on free F content and bonding strength were investigated. The researchresults showed that the free F content（0.17%）of UF adhesive could meet the requirement of national standard（nomore than 0.3%）,the F emission（1.17 mg/L）in plywood reach the index requirement of E1grade（no more than1.5 mg/L）in GB/T 9846.3—2004 standard,bonding strength（increased from 0.46 MPa to 0.97 MPa）reach theindex requirement of II-class plywood in national standard,and the water resistance was obviously improved whenmolar ratio of n（F）∶n（U）was 1.2∶1.0,initial p H value was 6.5,reaction temperature was 85 ℃ and mass fractionof M was 6% in total U.