改性纳米二氧化硅–丙烯酸酯聚氨酯乳液的制备及表征

Preparation and characterization of modified nano silica–acrylate polyurethane emulsions

以自制改性纳米Si O2水分散液、异佛尔酮二异氰酸酯(IPDI)、聚醚二元醇(N210)及甲基丙烯酸甲酯(MMA)等为原料,通过乳液聚合法制得改性纳米Si O2–丙烯酸酯聚氨酯乳液(Si O2–PUA)。通过傅里叶变换红外光谱、Zeta电位测试、热重分析和粒径分布测试等手段对乳液进行了表征,测试了漆膜的硬度、吸水率和耐醇性等性能,探讨了纳米Si O2添加量的影响。当纳米Si O2的添加量≤PUA含量的5%时,Si O2–PUA在469 cm-1处出现了明显的Si─O键弯曲振动峰,而PUA则没有,说明纳米Si O2与PUA可能发生了化学键合。添加5%改性纳米Si O2后,PUA乳液的Zeta电位由-46.5 m V变为-40.1 m V,绝对值减小,稳定性较好;热分解温度比PUA提高了35°C;胶粒平均粒径在纳米级,且Si O2粒子分散均匀;其漆膜硬度提高至4H,吸水率降为10.35%。

A modified nano SiO2-acrylate polyurethane （SiO2-PUA） emulsion was prepared by emulsion polymerization with home-made aqueous modified nano SiO2 dispersion, isophorone diisocyanate （IPDI）, polyether glycol （N210）, and methyl methacrylate （MMA） as raw materials, and characterized by Fourier-transform infrared spectroscopy, Zeta potential test, thermogravimetric analysis, and particle size distribution measurement. The hardness, water absorption, and alcohol resistance of its film were tested. The effect ofnano-SiO2 amount on the properties of emulsion and its film was studied. When the amount of SiO2 is not greater than 5wt% of PUA, the SiO2-PUA presents a Si-O bending vibration peak at 469 cm-1 which is not shown in PUA, indicating that nano SiO2 particles may have been grafted in the PUA chains. The Zeta potential of PUA changes from -46.5 mV to -40.1 mV after adding 5wt%modified nano-SiO2. The decrease in the absolute value ot Zeta potential implies that the emulsion has an improved stability. The thermal decomposition temperature of SiO2- PUA emulsion is increased by 35 ℃ as compared with the PUA. The SiO2-PUA emulsion has an average particle size in nanometer scale with well-dispersed SiO2 particles in it. The emulsion film has a hardness up to 4H and a water absorption of 10.35%.