聚氨酯丙烯酸酯共聚乳液的合成及其涂膜性能

Synthesis of Polyurethane-Acrylate Copolymeric Emulsion and Properties of the Coating

传统的合成乳液,综合性能差。不使用有机溶剂,合成了高tg(20.2℃)、低成膜温度(13.2℃)、力学性能较好的聚氨酯丙烯酸酯(PUA)共聚乳液,研究了n(NCO)/n(OH)、固化剂等因素对涂膜性能的影响。傅立叶红外光谱(FT-IR)证实,聚氨酯(PU)和聚丙烯酸酯(PA)发生了共聚反应。TEM和粒径分布测试表明,PUA乳液粒径为200 nm左右,分布较均匀。DSC分析表明:涂膜中PU链的硬段及PA分子链之间具有一定的相容性和共混程度。力学测试及涂膜综合性能测试显示,当n(NCO)/n(OH)为1.2～1.3,固化剂质量分数为1.2%～2.0%时,涂膜的力学性能、耐盐雾性能以及耐老化性能优异。

Polyurethane-acrylate copolymeric emulsion ( PUA) of high tg (20.2 ℃) , low film-forming temperature (13.2 ℃) and good mechanical properties was synthesized in the absence of organic solvents. The influence of n(NCO)/n( OH) and curing agents on the properties of the PUA coatings was studied. The chemical bonding feature of the coatings was analyzed by means of Fourier transformation infrared spectrometry (FTIR). The grit size and distribution of the emulsion was analyzed using a transmission electron microscope. The thermal behavior of the PUA coatings was examined by means of differential scanning colorimetry. Moreover, the mechanical properties, corrosion resistance, and aging behavior of the coatings were also investigated. It was found that chemical bond was formed between hard segment of PU and PA chain via copolymerization. The PUA emulsion had a particle size of around 200 nm and uniform size distribution as well. The PA chain and hard segment of PU chain had good compatibility in the PUA coating and a certain degree of blending. Moreover, at an n( NCO)/n(OH) value of 1.2-1.3 and curing agent content of 1.2%-2.0% , the coatings had significantly increased mechanical properties and good resistance to saline-fog and aging.