酚化改性蔗渣硫酸盐木素制备酚醛树脂胶黏剂

Phenolation of Bagasse Kraft Lignin for Application in Lignin-based Phenol Formaldehyde Adhesives

关键词:  蔗渣硫酸盐木素  酚化改性  木素基酚醛树脂胶黏剂

Key Words:sugarcane bagasse kraft lignin  phenolation  lignin-based phenolic formaldehyde adhesive

摘要:本研究以蔗渣硫酸盐木素（KL）为原料，在酸性条件下对KL进行酚化改性，通过单因素实验和正交实验优化反应条件。以酚化改性硫酸盐木素（P-KL）酚羟基含量为响应值，确定最佳反应条件为：苯酚∶木素（质量比）=4∶1，催化剂（质量分数98%浓硫酸）用量4 %，反应时间2.5 h，反应温度110℃。利用凝胶渗透色谱（GPC）表征硫酸盐木素酚化改性前后相对分子质量的变化，结果表明，与KL相比，P-KL相对分子质量减小、分布变窄，酚羟基含量增加。分别用P-KL和KL代替质量分数60%的苯酚制取木素基酚醛树脂胶黏剂P-KLPF和KLPF。结果表明，P-KLPF中游离甲醛和游离酚含量均小于KLPF胶黏剂。由此可知，酚化改性能显著提高硫酸盐木素与甲醛的反应活性，降低木素基酚醛树脂胶黏剂中游离甲醛及苯酚的释放量。

Abstract:In this study， sugarcane bagasse kraft lignin(KL)was phenolated by using acid as a catalyst. The phenolation process was optimized by single-factor and orthogonal experimental design where the phenolic hydroxyl group content of lignin was used as response value. The optimal conditions were found as follows: phenol∶KL=4∶1(mass ratio）， t=2.5 h， T=110℃， the catalyst dosage(concentrated sulphuric acid of 98 wt%)was 4%. The structural changes of KL induced by phenolation were further characterized by 31P Nuclear Magnetic Resonance Spectroscopy(31P NMR）， and Fourier Transform infrared spectroscopy. The results indicated that the molecular weight and the polydispersity of phenolated bagasse kraft lignin（PKL)decreased. The phenolic hydroxyl group content increased. Eventually， P-KL and KL were respectively used to replace 60 wt % of phenol to produce phenolic formaldehyde(PF) adhesives as P-KLPF and KLPF. Compared to KLPF， less formaldehyde and phenol were released from P-KLPF which indicated that phenolation was an effective way to improve the reaction activity bagasse kraft lignin lignin and formaldehyde.