Quantitative evaluation of hydrolysis ratio and content of silicic ester on film surface by X-ray photoelectron spectroscopy

摘要

silicic ester,an oligomer of tetraalkoxysilane in an additive of coatings for giving hydrophilicity to the coated film surfaces.However,its mechanism of hydrophilization is not yet clear.Because silicic ester can be persumed to be hydrolyzed after migrating to the film surface based on its hydrophobic nature,it the silicic ester content onthe surface and the hydrolysis ratio can be determined separetely,they wil provide usefull informatiion for an elucidation of the mechanism.We found out that only alkoxy group of silicic ester in coated films was specifically decomposed on irradition of nonmonochromatized Mg K_(#alpha#) X-rays.The individual determining methods of the silicic ester content and the hydrolysis ratio of the surface using this phenomenon were developed.These methods were applied to the acryl-urethane coating which containing a silicic ester.It was found that the hydrolysis of silicic ester on the film surface was proceeding gradually after curing.A good correlation was obtained between silicic ester content and water contact angle on the surface of the film.In addition,the silicic ester content and the hydrolysis ratio of the surface indicated a good correlation to the water contact agnle.Consequently,these methods are usefull for evaluatioh of hydrophilization of coating surfaces.