环氧氯丙烷接枝改性脱脂豆粉增强豆胶耐水胶合力的机理研究

Improving water resistance of soy-based adhesives (SBAs) is a key point of the SBAs as wood adhesives. The aim of this project was to improve water-resistant gluability of SBAs by inducing epoxy groups into its raw materials --- defatted soy flour (DSF). Biological and chemical approaches will be used to targeted modification the functional groups in DSF, and then epoxy groups were introduced by grafting epichlorohydrin onto the targeted modified functional groups in DSF. The molecular structure and phys-chemical phenomenon of the products formed during targeted modification and grafting process of functional groups in DSF were characterized by NMR, XPS, DSC, IR, TEM, and SEM. Based on these characterization results and overall studies on water-resistant gluability of the developed SBAs, the active conditions of functional groups in DSF, grafting mechanism of epichlorohydrin, and the mechanism of improved water-resistant gluability of SBAs via grafting epichlorohydrin onto the DSF were finally exploited. The project intends to provide new ideas for preparing a boiling-water resistant eco-biomass-based adhesive and other bio-based adhesives for wood industry.

提高大豆基胶黏剂的耐水性是木材胶黏剂研究的重点和热点。本项目采用生物和化学方法对脱脂豆粉组分中的官能团进行定向修饰；再设计环氧氯丙烷接枝定向修饰后的官能团，引入环氧基，增强活性，提高大豆基胶黏剂的耐水胶合力；借助NMR、XPS、DSC、IR、TEM、SEM等表征手段剖析脱脂豆粉组分中官能团在定向修饰及接枝过程中产物的结构特征、理化现象；阐明脱脂豆粉中官能团的活化条件，解析在官能团上引入环氧基的有利机制，探索脱脂豆粉环氧化后对豆胶耐水性的影响规律，揭示环氧氯丙烷接枝改性脱脂豆粉提高大豆基胶黏剂耐水胶合力的机理，为环保型耐沸水大豆基胶黏剂及类似生物质基木材胶黏剂的研究提供新思路。

针对制备从原料到产品都绿色环保的高耐水性大豆基胶黏剂问题。课题利用生物柴油制备中的副产转化物——环氧氯丙烷，与活化的脱脂豆粉组分中含活泼氢官能团发生接枝反应而引入环氧基，制备含环氧基的大豆基胶黏剂，提高其耐水胶合力。脱脂豆粉经半纤维素酶处理后，还原糖和葡萄糖含量分别提高了168.8%和2555.1%，而蔗糖和粗纤维分别下降了4.9%和38.3%。酸处理的脱脂豆粉表现出较好的流变性能。以酶联合酸盐碱处理脱脂豆粉的碳水化合物组分与单纯酶处理差别不大，但前者粘接性能提高了11%；固化后的胶层显示出更好的耐水性，溶胶率下降了7.3%。研究实现了大豆基胶黏剂固化后组分间的自增强。环氧氯丙烷接枝脱脂豆粉组分过程主要发生了脱脂豆粉组分中的羧基和羟基与环氧氯丙烷环氧基反应生成了羧酸酯和醚；形成的环氧基主要接枝于蛋白质的氨基酸残基上。大豆基胶黏剂固化过程中环氧基开环，主要与氨基、羧基、羟基等基团发生了化学反应，羧酸酯和醚结构增多，羟基含量下降，导致胶黏剂固化后形成致密的交联网络结构，热稳定性及耐水性提高。当环氧氯丙烷接枝条件为pH6.3、温度70℃、时间40min时，接枝率为78.99%；以此条件制备的大豆基胶黏剂的粘度、固含量、胶合强度均随环氧氯丙烷用量增加而提高。环氧氯丙烷添加量为脱脂豆粉10%时，胶合强度为0.96 MPa，达到GB/T 17657-1999中I类胶合板的要求。研究阐明了将脱脂豆粉组分活化提高官能团含量后，利用环氧氯丙烷引入环氧基，提高大豆基胶黏剂耐水胶合力的机理，为类似生物质基胶黏剂的研究提供了参考。项目研究过程发表了7篇论文，其中SCI收录4篇，EI收录2篇，中文核心收录1篇；申请了6件发明专利，授权3件；在国内外学术会议上做了6次会议报告；参与培养博硕士生3名。