低共熔离子液体催化活化木质素改性胶黏剂的研究

Alkali lignin of wheat-straw from black liquor of pulping is as potential renewable resources . The utilization of renewable resources as an alternative to oil products for synthetic adhesive can reduce the consumption of oil resources, and thus, help protect resources and environment. However, alkali lignin possesses inherently complex structure, ununiform molecular weight distribution, and lower reactivity. If using alkali lignin as a raw material of wood adhesive, there was low bonding strength, poor water resistance, high energy consumption and other issues. So far, the utilization of alkali lignin has not been generalized in adhesive industry. Deep Eutectic Solvents, a new type green solvent, are composed of two or more components of the eutectic mixture, with the typical characteristics of ionic liquids: vapour pressure, high conductivity, stable chemical property, zero saturation vapor pressure, are liquid and high conductivity at room temperature, and the preparation process is simple, easy availability of raw material, low cost. It is a kind of environmental friendly solvent, is expected to become a new research focus of green chemistry and chemical engineering. However, there is very limited studied have examined the effects on the degradation of alkali lignin of wheat-straw. Ionic liquids，are widely applied in dissolution and catalytic pyrolysis of cellulose and lignin with their particular physicochemical properties. The objectives of this project is to design and synthesis a kind of deep eutectic ionic liquid with the function of dissolution, degradation and catalytic, and pretreat wheat alkali lignin with the deep eutectic solvents to make macromolecules fragment, increase the activite point of reaction and improve the reaction activity of Alkali lignin. Afterwards, the resultant products without separation, will be used directly as an alternative to phenol in phenol-formaldehyde resins, urea-formaldehyde resins, and lignin adhesive. A comprehensive system of utilizatiing waste lignin will be established throughtout this project. This project will reduce the cost of adhesive and decrease the emission of formaldehyde and phenol, protect environment. And then find the route of comprehensive utilization of Alikali lignin which is simple and feasible process,environment friendly,turn the waste lignin into treasure chemicals provide technical support and theoretical basis for the application of industrial lignin in future.

麦草碱木素来自于制浆造纸工业废液,是极具潜力的可再生资源,利用其代替石油产品作为合成胶粘剂的原料是发展趋势。但由于木质素分子量分布不均,结构复杂,反应活性低,用其做胶粘剂存在胶合强度低，耐水性差且生产能耗大等问题无法推广。低共熔离子液体是由两种或多种成分组成的低共熔混合物，其合成原料均为很常见的化合物，来源丰富且价格低廉、易生物降解、无环境副作用，已成为绿色化学化工领域新的研究热点。本项目通过分子结构设计，将固体有机分子和离子型化合物按照一定比例混合，得到室温下呈液态的集溶解、降解及催化作用于一体的低共熔离子液体，用其将麦草碱木素大分子碎片化，增加反应活性点，提高反应活性，并不经分离将其直接用于木材胶粘剂的改性研究中。旨在从理论上找到绿色环保、简单可行的废液木素综合利用的突破口，降低胶粘剂的生产成本，减少游离醛与游离酚污染，充分实现变废为宝的目的，为其今后的产业化应用理论依据。

项目针对木质素结构与性能的复杂性，通过设计不同分子结构的低共熔离子液体（DES），筛选出熔点较低，具有集溶解、降解、催化于一体的多功能DES，并用其对不同的木质素进行结构控制，阐明其木质素碎片化的实质，从而有效控制酚羟基数量和可交联的游离空位（邻、对位）的数量，阻止游离酚羟基的絮聚，优化其使用性能。结果发现针对不同的木质素，采用不同的DES的作用机理完全不同，回收得到的木质素的性能也发生了不同的变化，其应用方式也有所不同：（1）尿素/氯化锌DES改性后的麦草碱木质素结构基本被破坏，回收的木质素与大量的ZnO相连接，因此将其用于酚醛树脂的固化促进剂，可明显缩短PF树脂的凝胶时间，增加树脂的耐热性；（2）乙酰胺/氯化锌、氯化胆碱/氯化锌、氯化胆碱/尿素、氯化胆碱/丙三醇等四种DES体系可将木质素部分碎片、活化，用其可代替部分苯酚用于PF 树脂的合成，其中经氯化胆碱/氯化锌体系处理后的木质素的替代量可达40%；（3）借助乙酰胺/氯化锌、ChCl/苯酚DES的溶剂化、催化、活化等多重协同作用，处理木质素后可不经分离直接代替部分苯酚与甲醛加成，减少了木质素的分离与再生步骤，制备工艺简单，反应易于控制，所制备的树脂仍具有良好的性能；（4）氯化胆碱/丙三醇DES体系处理木质素磺酸钠可用于水性环氧树脂的乳液分散剂、用氯化胆碱/尿素DES处理酶解木质素可充分利用其胺基和羟基实现对环氧树脂多重协同固化剂作用等。另外项目还围绕DES溶解生物质原料的特点展开了提取丝瓜络纤维素和虾壳中甲壳素的研究。项目的研究结果从多角度推动低共熔离子液和工业木质素应用的发展，促进制浆造纸废液污染治理。项目已发表第一标注学术论文15篇，其中SCI收录5篇，EI收录1篇，SCD收录9篇，申请国家发明专利6项，其中已授权国家发明专利2项，出版学术编著1部，参加学术会议20人次，并做口头报告10次。另外尚有4篇SCI和1篇中文论文已投稿待发表。