活性硅醇基聚氨酯水分散体的合成及其防腐性能

Synthesis and anticorrosion performance of polyurethane aqueous dispersion based on active silanol

水玻璃作为一种廉价的矿物质,经提纯可得到活性硅醇,以其作为内交联剂可应用于聚氨酯的合成中。对不同活性硅醇添加量合成的聚氨酯水分散体粒径及其涂膜的吸水率、接触角、动电位极化曲线、热重和扫描电镜作了测试分析,结果表明当活性硅醇添加量为30%时,水分散体平均粒径最小,为28.83nm;随着活性硅醇添加量的增加,涂膜吸水率增大,接触角反而减小;动电位极化曲线拟合结果表明,当活性硅醇添加量为70%时,涂膜腐蚀电流密度最小且极化电阻最大;红外光谱和扫描电镜分别可以确定水分散体结构中含有Si—O—Si、Si—O—C的基团以及涂膜中含有二氧化硅粒子,说明活性硅醇在体系中不仅参与主链反应,还以无机粒子的形态存在于其中;热重分析表明活性硅醇的引入显著提高了涂膜的热稳定性。

Active silanol can be obtained from water glass by purification and be used as an internal crosslinking agent in the synthesis of polyurethane. Polyurethane aqueous dispersions with different amount of active silanol were investigated and analyzed by measuring their particle size,water absorption rate,contact angle,potentiodynamic polarization curves,thermogravimetry and scanning electron microscopy. The results showed that average particle size of the water dispersion reached the minimum of 28.83 nm,when the amount of active silanol was 30%. With the increase of the amount of active silanol,the water absorption rate of the coating increased,but the contact angle decreased. And the potentiodynamic polarization curves showed that when the amount of active silanol was 70%,the corrosion current density of the coating was the lowest and the polarization resistance was the highest. Infrared spectroscopy and scanning electron microscopy can respectively determine that structure of the dispersions contained Si—O—Si and Si—O—C groups and the coating contained silica particles,which indicated that active silanol took part in the chain reaction in the state of inorganic particles. Besides,thermogravimetric analysis demonstrated that the introduction of active silanol significantly improved the thermal stability of the coating.