硅溶胶改性水性聚氨酯丙烯酸酯复合乳液的性能研究

Research on Properties of Colloidal Silica Modified Waterborne Acrylic Polyurethane Composite Emulsions

采用异氰酸酯基团封端的聚氨酯预聚体与硅溶胶混合的方法,制备出了水性聚氨酯丙烯酸酯/硅溶胶纳米复合乳液,探究了分散在聚氨酯预聚体中的硅溶胶颗粒的粒径和复合漆膜中硅溶胶的含量对漆膜性能的影响。研究发现,分散在聚氨酯预聚体中的19 nm小粒径硅溶胶颗粒容易团聚,漆膜性能较差;相比之下,91 nm的硅溶胶无机粒子在乳液中具有良好的分散稳定性。复合漆膜中硅溶胶的含量对漆膜的吸水率和力学性能有明显影响,但对漆膜硬度、附着力和光泽的影响较小。结果表明,硅溶胶粒子粒径为91 nm,加入量为复合乳液质量的30%时漆膜性能最佳,吸水率为2.67%,铅笔硬度为3H,拉伸强度为5.77 MPa,断裂伸长率为564.58%,硅溶胶与树脂基质相容性最好。并且与未改性的聚氨酯丙烯酸酯漆膜相比,复合漆膜的耐水性和热稳定性显著提高。

Waterborne acrylic polyurethane/colloidal silica nanocomposite emulsions were prepared by mixing isocyanate groups terminated polyurethane prepolymers with colloidal silica.We investigated the effect of the different nanosilica sizes and amounts of colloidal silica on the film properties.The characterization indicated that the small size silica around 19 nm in the organic polyurethane matrix tended to agglomerate and brought the poor properties in the dry films.In comparison,the silica of approximately 91 nm inhibited the aggregation of particles and retained the good dispersion stability of composite emulsions.Besides,the contents of silica in nanocomposites films had a great influence on water absorption and mechanical properties,but hardly effected the hardness,adhesion and glossiness of coating.The results showed that adding colloidal silica with 91 nm size and 30%content of emulsions was the best choice to significantly improve films properties with 2.67%water resistance,3H hardness,5.77 MPa tensile strength and 564.58%elongation at break.Compared with pure acrylic polyurethane films,the water resistance and thermal stability of modified films were significantly improved.