木质素-PEI胶黏剂的制备及其在刨花板中的应用研究

Preparation of Lignin-PEI Adhesive and Its Application in Particleboard

为了消除刨花板中的有毒甲醛,利用高碘酸钠氧化针叶材硫酸盐木质素(SKL)制备氧化木质素(OL),与聚乙烯亚胺(PEI)反应,合成出一种新型的无甲醛氧化木质素-PEI(OLP)胶黏剂,以杨木刨花为基材制备刨花板。利用傅里叶变换红外光谱仪(FTIR)和核磁共振波谱仪(NMR)分析OL与PEI的反应机理。研究刨花板的最佳制备工艺条件,对刨花板的抗水性、热稳定性和表面形貌进行表征。结果表明:高碘酸钠可以选择性氧化木质素产生邻醌结构,OL中的邻醌可以进一步与PEI中的氨基反应,制备OLP胶黏剂。在OL/PEI质量比为1∶1,胶黏剂用量为10%,热压温度为180℃,热压时间为13 min的最佳制备条件下,得到的刨花板具有较高的强度、抗水性能和热稳定性。文章提供了一种制备无甲醛木材胶黏剂的新方法,也为工业木质素的应用提供了新的思路。

In order to eliminate toxic formaldehyde in particleboard,sodium periodate was used to oxidize softwood kraft lignin(SKL)to prepare oxidized lignin(OL).A new formaldehyde-free oxidized lignin-PEI(OLP)adhesive was synthesized by reacting OL with polyethyleneimine(PEI),and particleboard was prepared with poplar particle as substrate.The reaction mechanism of OL and PEI was analyzed by Fourier transform infrared spectroscopy(FTIR)and nuclear magnetic resonance spectroscopy(NMR).The optimum preparation conditions of particleboard were studied,and the water resistance,thermal stability and surface morphology of particleboard were characterized.The results show that sodium periodate can selectively oxidize lignin to produce ortho-quinone structure,and ortho-quinone in OL can further react with the amino group in PEI to prepare OLP adhesive.Under the optimal preparation conditions of OL/PEI mass ratio of 1∶1,adhesive dosage of 10%,hot pressing temperature of 180℃and hot pressing time of 13 min,the obtained particleboard has high strength,water resistance and thermal stability.It provides a new method for preparing formaldehyde-free wood adhesives,and also provides a new idea for the application of industrial lignin.