Anti-glare performance of sol-gel-derived spray coatings prepared with various water-to-alkoxide ratios

Abstract

We fabricated anti-glare (AG) coatings on glass sheets by spraying alkoxide-derived silica sols and demonstrated that the water-to-alkoxide ratio is one of the key factors for improving AG performance and sol stability. We synthesized silica sols using tetraethylorthosilicate (TEOS), water, nitric acid, and denatured ethanol and sprayed them on sheets of chemically strengthened glass. The molar ratios of water to TEOS (r) were 3, 7, and 14. The sol with r = 7 provided a higher arithmetic-mean height (Sa), smaller autocorrelation length (Sal), and better optical properties (lower gloss, higher haze, and lower sparkle level) than the sol with r = 3. An excessive amount of water at r = 14 yielded a large Sal and a high sparkle level. As the storage time of the sols increased, higher r values caused a more pronounced increase in Sa. Although none of the sols showed noticeable temporal changes during dynamic light scattering measurements, solutions with higher r values exhibited a more remarkable reduction in the retention time during liquid chromatography with a styrene-divinylbenzene matrix. Hence, an excessive amount of water was thought to cause hydrophilization of the polymerized species during storage.