酚化木质素-糠醛胶黏剂及其复合腻子研究

Study on Preparation of Phenolic Lignin-Furfural Adhesive and Composite Putty

研究利用高反应活性酚化木质素制备高性能酚化木质素-糠醛胶黏剂。木质素酚化后,在756 cm~(-1)和695 cm~(-1)处新增了两个峰,证实了木质素侧链位的羟基和酚环的活性位点发生了取代反应。在糠醛和苯酚的摩尔比为1.4/1,糠醛和木质素的质量比为0.05/1,缩合时间为3.5 h,氢氧化钠的用量为11%条件下,所制备的酚化木质素-糠醛胶黏剂各项性能良好。该胶黏剂的固体含量为56.25%,pH为11.2,黏度为1 525 m Pa·s,游离糠醛含量为0.04%,游离苯酚含量为0.05%,胶合强度为1.67 MPa。采用六亚甲基四胺优化,胶层均匀分布,与木材面紧密结合,有效胶钉较多,改善了胶合强度。该酚化木质素-糠醛胶黏剂与桉木粉复配所得复合腻子,应用于胶合板表面缝隙填充和平整度调控,不含甲醛,与胶合板相容性好,干燥速度快,耐水性好,打磨性好,粘结强度高,为胶合板可直接饰面和提高饰面高光性提供了技术支撑。

High performance phenolic lignin-furfural adhesive was prepared by using highly reactive phenolic lignin.Two new peaks appeared at 756 cm-1 and 695 cm-1 after phenolization of lignin,which confirmed the substitution reaction between hydroxyl group atαposition of lignin side chain and the active site of phenolic ring.Under the molar ratio of furfural and phenol of 1.4/1,the mass ratio of furfural and lignin of 0.05/1,the condensation time of 3.5 h,and the amount of sodium hydroxide of 11%,a phenolic lignin-furfural adhesive with good performance was obtained(solid content of 56.25%,pH of 11.2,viscosity of 1525 mPa·s,free furfural content of 0.04%,free phenol content of 0.05%,adhesive strength of 1.67 MPa).After the optimization of hexamethylenetetramine,the adhesive layer was evenly distributed and closely combined with the wood surface,and there were many effective adhesive nails,proving that the adhesive strength was effectively improved.The composite putty obtained from the mixture of phenolic lignin-furfural adhesive and eucalyptus powder can be used for gap filling and flatness control of plywood surface.It had the advantages of no formaldehyde,good compatibility with plywood,fast drying speed,good water resistance,good grinding property,high bonding strength.It provides technical support for the direct finishing of plywood and improving the gloss of the finish.