复合疏水扩链剂对聚氨酯乳液性能的影响

Effect on The Properties of Waterborne Polyurethane Emulsion Modified by Hydrophobic Chain Extension Agent Complex

以聚己二酸丁二醇酯(PBA)、异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙酸(DMPA)为主要原料,环氧树脂(E44)、1,4-环己烷二甲醇(CHDM)及异佛尔酮二胺(IPDA)为疏水扩链改性剂,经丙酮自乳化法制备了改性水性聚氨酯(E-WPU)乳液,并使用FTIR、TG、附着力、硬度和塔菲尔极化曲线方法对改性前后乳液涂层性能进行了考察。结果表明:当预聚体中R值〔R=n(—NCO)/n(活性氢)〕为1.2,w(E44)=7%、w(CHDM)=2%和w(IPDA)=3%时,E-WPU综合性能最好,其涂膜吸水率为3.75%,硬度为HB-H,附着力为0级,而未改性的WPU涂膜吸水率为17.85%,硬度为2B,附着力为3级,E44、CHDM、IPDA的加入显著提高了E-WPU涂膜的耐水性、硬度及对金属附着力。改性后的涂膜腐蚀电位为-0.660 8 V,腐蚀电流密度为9.778×10-7A/cm2。

The modified waterborne Polyurethane emulsion（E-WPU） was synthesized based acetone on self-emulsified process by using of Polybutylene adipate（PBA）,isophorone diisocyanate（IPDI） and dimethylol propionic acid（DMPA） as main raw materials,epoxy resin（E44）,1,4-cyclohexane dimethyl（CHDM） and isophorone ketone diamine（IPDA） as hydrophobic chain extension modifier.Modified and unmodified emulsion coating properties were characterized by the FTIR,Tg,adhesion,hardness and Tafel polarization curves. The results showed that using of E44/IPDA/CHDM had significantly improved the water resistance,hardness and adhesion on the metal of the E-WPU coating.When the mass fraction of E44,CHDM and IPDA were respectively 7%,2% and 3% in the prepolymer,and the molar ratio of the —NCO and the active hydrogen of the —OH/—NH/—NH2group in the prepolymer（R） was 1. 2,the coating had the best comprehensive performance. The water absorption rate,the hardness and the adhesion on metal surface were respectively 3. 75%,HB-H and grade zero,contrast with 17. 85%,2B and grade 3 of WPU. The corrosion potential of E-WPU coating was-0. 660 8 V,and the corrosion current density was 9. 778 × 10-7A/cm2.