水性聚氨酯改性环氧树脂乳液的涂膜性能研究

Study on Coating Properties of Waterborne Polyurethane Modified Epoxy Resin Latex

制备不同粒径的水性聚氨酯,并分析添加不同粒径和掺量的水性聚氨酯对环氧乳液成膜拉伸性能、断裂伸长率的影响,同时测试了涂膜的抗冲击、柔韧性、耐腐蚀性、光泽度等性能。结果发现:粒径为55nm的水性聚氨酯掺量为5%时对水性环氧树脂的增韧效果最好,改性涂膜的拉伸强度、断裂伸长率和断裂能比未改性环氧涂膜分别提高了30%、62%和143%,而弹性模量基本不降低。SEM结果表明:掺加聚氨酯后环氧涂膜在受到外力作用时可使应力分散,断口表面条纹多且层次丰富,呈现韧性断裂的特点,形成涂膜的抗冲击、柔韧性、耐酸碱、光泽度等性能也有显著改善。

Waterborne polyurethanes with diverse particle sizes were prepared first.Then,the influence of adding waterborne polyurethanes with diffe-rent particle sizes and amounts in epoxy resin latex on the tensile properties and elongation at break of the modified epoxy resin film were investigated.The impact properties,flexibility,corrosion resistance,gloss and other properties of the modified epoxy resin coating were analyzed.The results indicated that the modified epoxy resin with the best toughening effect was prepared by adding 5%waterborne polyurethane with particle size of 50 nm.Compared to the epoxy coating without modification,the modified epoxy resin coating exhibited the increase of 30%,62%,and 143%in tensile strength,elongation at break,and fracture energy,while the modulus of elasticity of the modified coating did not decrease.It could be observed from SEM results that fracture surface of the modified coating was rich in stripes and layers,showing the characteristics of ductile fracture.This might be explained by the addition of waterborne polyurethane that made the stress on the modified epoxy resin coa-ting be effectively dispersed when subjected to external force.In addition,the properties of the coating,including impact resistance,flexibility,glossiness,acid resistance and alkali resistance,were also improved evidently.