ビニルトリエトキシシランによる酸化チタンのカップリング処理 [in Japanese] Coupling Treatment of TiO_2 Pwoders with Venyltriethoxysilane [in Japanese]
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To obtain fundamental findings on providing an inorganic substrate with hydrophobic properties using a silane coupling agent by the dry method, which is often limited by an uneven product, a fundamental study was performed using TiO<sub>2</sub> and a vinyltriethoxysilane (VTES) system. The hydrophobicity afforded by VTES treatment were determined as a function of parameters such as the VTES/EtOH/Aq.CH<sub>3</sub>COOH ratio, pH of aqueous phase, duration of pretreatment with VTES solution, H<sub>2</sub>O/VTES ratio and heat treatment temperature of VTES treated product. It was found that the molar ratio of H<sub>2</sub>O/VTES, pH of aqueous phase, pretreatment duration of VTES solution, and heat treatment temperature are important parameter to determine coupling effect.<br>The principal findings obtained are as follows.<br>1. Optimum treatment of TiO<sub>2</sub> can be achieved using VTES solution containing a stoichiometric amount of H<sub>2</sub>O at aqueous phase pH 3.3 after storing for more than 36hrs.<br>2. The pH value in the aqueous phase is intimately related to hydrolysis and condensation reactions of VTES, and thus to the hydrophobic properties of TiO<sub>2</sub> treated with VTES solution.<br>3. Heat treatment of TiO<sub>2</sub> powders treated with VTES is essential to provide a hydrophobic property to TiO<sub>2</sub>. However an excessively high temperature causes evaporation of hydrolysis and condensation products of VTES, resulting in poor hydrophobicity.<br>4. The required amount of VTES can be calculated by applying a closed packing model of VTES to the TiO<sub>2</sub> substrate.
- Jitsumu Hyomen Gijutsu
Jitsumu Hyomen Gijutsu 50(1), 84-89, 1999-01-01
The Surface Finishing Society of Japan