用大豆制备环保型木材胶粘剂的研究

Environment-friendly wood adhesive preparation from soy

采用分阶段、多种改性剂联用的方法提高大豆基木材胶粘剂的耐水胶合强度。试验结果表明:多亚甲基多苯基多异氰酸酯(PAPI)的用量和豆粉浓度对耐水胶合强度的影响较显著,最佳大豆粉的改性方案为:豆粉浓度21%、十二烷基硫酸钠浓度(SDS)1.0%、脲浓度1.5mol·L-1、乙酸酐用量1.2%、PAPI用量为20%。对复合改性大豆基木材胶进行压板工艺探讨的结果显示:热压温度对耐水胶合强度的影响较显著,最佳压板工艺为:热压温度140℃,单位压力1.2MPa,热压时间1.0min·mm-1。按最佳制胶方案和压板工艺进行重复压板试验,获得复合改性大豆基木材胶粘剂的平均耐水胶合强度为0.94MPa,达到Ⅱ类胶水平,可代替脲醛树脂胶使用。复合改性大豆基木材胶无游离甲醛释放,无毒环保,具有很好的社会效益和生态效益。红外光谱进一步验证了多阶段复合改性的大豆基木材胶粘剂耐水胶合强度的增强机理。

The authors selected several suitable modifiers to enhance the hydrophobic strength of soy adhesive at different phases. The technology of the pressing-board with composite modified soy adhesives is established and tested. The test results show that soy power and polyphenylene polyisocyanate（PAPI） are two more important factors affecting the hdrophobic strength of the soy adhesive. The best modification＇prescription is 21% soy powder, 1.0% sodium dodecyl sulfate（SDS） , 1.5 mol·L^-1 urea, 1.2% anhydride and 20% PAPI. The pressing-board technology shows that hot-press temperature is the most significant factor in determining the hydrophobic strength of adhesives. It is most efficient at a hot-press temperature of 140℃ , specific pressure of 1.2 MPa and hot-press duration of 1.0 min·mm^-1. The average hydrophobic strength of the modified soy adhesives is 0.94 MPa. It can serve as urea resin because it meets grade II glue and free formaldehyde waterproof requirement. Furthermore, the modified adhesives are harmless and environmentally friendly, with high marketability as well as socio-ecological benefits. Fourier transform infrared spectroscopy （FTIR） validates the principles of waterproof development and chemical mechanism of the compositely modified soy-based wood adhseive.