木材溶液中羟基与异氰酸酯反应的研究

以涂料工业广泛应用的新型助剂二元酸酯 (DBE)为液化试剂 ,盐酸为催化剂 ,将苯甲基化木材溶液化后 ,与不同结构的异氰酸酯反应 .利用FT IR及1 3C NMR分析液化苯甲基木质纤维素与不同结构异氰酸酯得到了聚氨酯树脂 ,证明了木材中羟基可以用来作为聚醚多元醇与异氰酸酯制备聚氨酯材料 .通过准确测量体系中游离的NCO含量 ,从而得出不同结构异氰酸酯与木材溶液中羟基的反应规律 .实验结果表明 ,异氰酸酯的存在大大促进了木材结构中羟基的释放 ,由于不同异氰酸酯的活性不同 ,使得羟基值变化亦不相同 ,其顺序为IPDI>HDI>TDI .为了保证最终的材料性能 ,选择TDI和IPDI作为木材溶液制备聚氨酯树脂的异氰酸酯组份较好

STUDY ON THE REACTION BETWEEN ISOCYANATES AND HYDROXYLS IN WOOD SOLUTIONS

The benzylated wood was liquefied using HCL as a catalyst and a mixed dibasic ester (DBE) as a novel liquefaction reagent,which has been applied extensively in coating industry because of its higher solubility and less toxicity.Then the solution obtained reacted with different isocyanates.By FT-IR and 13C-NMR analysis of the polyurethane resins prepared from liquefied benzylated cellulose,it was proved that the wood solution could be used as the polyols component to prepare polyurethane materials.On the other hand,by measuring the free NCO content in each system of polyurethanes from the wood solution,the changes of active hydroxy numbers in the wood solution can be calculated in the presence of different isocyanates.The results showed that isocyanates greatly stimulated the release of hydroxyl in wood,but the different structure and activity of isocyanates led to the different changes of hydroxyl in an order as follows:IPDI>HDI>TDI.In order to guarantee the resultant properties of polyurethanes materials,TDI and IPDI should be selected as the isocyanate component in the preparation of polyurethanes using wood wastes.