合成革用高光高透水性聚氨酯的构效关系

Synthesis and Application of High Gloss and High Permeability Polyurethane for Synthetic Leather

基于水基聚氨酯(WPU)结构与涂层光泽和透度的构效关系,制备了可满足合成革的光学性能要求的高光泽、高透度的水基聚氨酯,研究了不同二异氰酸酯、多元醇、硬段含量、亲水基团含量、乳胶粒径及分布、交联度和结晶度等结构因素对水基聚氨酯涂层光学性能的影响。结果表明,聚合物中所含基团的折光指数是影响涂层光学性能的重要因素,高折光率的芳环、酯键、氨基甲酸酯基和脲基能提高涂层光泽;高的硬段含量导致大分子链中氨基甲酸酯键或脲键含量增加,也能提高光泽度;水基聚氨酯的聚集态结构也是影响涂层光学性能的重要因素,结晶性的软、硬段会降低涂层的透光率,而共聚、引入侧基和交联破坏了大分子的规整性和结晶性,能改善涂层的透光度。水基聚氨酯的粒径对涂层的光泽亦产生重要影响,较小的乳胶粒径(<50 nm)将使涂层表面更平整光滑,涂层的光泽度更高。

Based on the structure-activity relationship of waterborne polyurethane(WPU),a type of WPU with high gloss and transparency which can meet the optical requirements for synthetic leather coating was prepared,and the effects of different isocyanates,polyols,hard segment contents,hydrophilic group contents,cross-linking degrees and crystallinity of WPU on the optical properties of the coatings were investigated in detail.The results show that the refractive index of the functional groups contained in polyurethane influences the optical properties of the coatings,aromatic rings,ester bonds,urethane groups and urea groups with higher refractive index can significantly improve the gloss of the coatings.Simultaneously,high hard segment contents will increase the numbers of urethane bonds or urethane bonds,which also enhance the gloss of the coatings.What′s more,the aggregate structure of WPU is an important factor to affect the optical properties of the coatings.The crystalline soft and hard segments decrease the light transmission,which reduces the transparency.Conversely,the regularity and crystallinity of soft segments can be disrupted by the copolymerization,introducing pendant groups and chemical cross-linking,which obviously improve the transparency of the coatings.The particle size of WPU is another important factor to influence the gloss of the coatings,a smaller emulsion particle size(<50 nm)will result in smoother surface and higher gloss of the coatings.