含液化木質素水性PU樹脂之膠合及塗裝性能

Adhesion and Coating Performances of waterborne polyurethane resins containing liquefi ed lignin

本研究將脫鹼木質素以聚乙二醇／丙三醇混合液為溶劑，鹽酸為催化劑進行液化處理，並以此液化木質素（Liquefi ed lignin; LL）取代部分聚四甲基醚二醇（Polytetramethylene ether glycol; PTMG）而應用於水性聚胺基甲酸酯樹脂（Polyurethane resins; PU）製備，合成時採行預聚合法，其中LL/ PTMG之-OH/-OH莫耳比設定為0/10、3/7、4/6、5/5，所得水性PU樹脂評估其樹脂液及薄膜性質，並探討其做為膠合劑及塗料應用之可行性。由試驗結果顯示，水性PU樹脂屬於剪切致稀型之非牛頓流體（擬塑性流體），隨LL添加比例增加，其樹脂液之黏度提高，粒徑增大，乾燥薄膜之彈性模數提高，但拉伸強度及破壞伸長率則降低；含LL之水性PU樹脂可應用於木材／木材及木材／無孔性之膠合，並以LL/PTMG之-OH/-OH莫耳比4/6者有最佳之膠合性能；將此水性PU樹脂應用於塗裝時，其塗膜之抗彎曲性良好，隨LL添加比例增加，塗膜硬度提高，但耐磨耗性及附著性則降低。 In this study, dealkaline lignin was liquefi ed in polyethylene glycol/glycerol cosolvent with hydrochloric acid as a catalyst. The waterborne polyurethane resins (PU) were prepared with a prepolymer mixing process and part of the polytetramethylene ether glycol (PTMG) was replaced with liquefi ed lignin (LL). The molar ratios of -OH/-OH for LL and PTMG was set as 0/10, 3/7, 4/6 and 5/5. The properties of resin solution and dry fi lm of waterborne PU resins were evaluated as well as the feasibility of using them as adhesives and coatings were investigated. The result shows that the waterborne PU resins were nonNewtonian fluids with the behavior of shear-thinning (Pseudoplastic fluid). Increasing the rate of LL in waterborne PU resins, the viscosity and the particle diameter of liquid resins, and the elastic modulus of dried fi lms increased. However, the tensile strength and elongation at break decreased. Waterborne PU resins containing LL can be used for gluing wood to wood and wood to nonporous materials. It had the best gluing performance for that prepared with the -OH/-OH molar ratio of LL/PTMG as 4/6. All of the waterborne PU resins showed good bending resistance when used as coatings. The hardness of coatings increased, but the abrasion resistance and adhesion decreased as the rate of LL increasing.