Coating glass or ceramic substrate with anti-reflective layer using sol-gel process, employs e.g. silicon-aluminum mixed oxide with adsorbed hydrophobe present in sol-gel binder

摘要

The porous anti-reflective layer comprises a metal, metal oxide, zinc oxide, tin oxide, aluminum oxide and/or their mixtures. It is especially a silicon-aluminum mixed oxide. A hydrophobic substance is deposited on the anti-reflective layer, at least locally. It is introduced into pores of the layer, forming a coating and/or total-area internal coating. The hydrophobe, especially being a silica sol, is present as a component of the sol-gel binder. The anti-reflective layer includes porous nanoparticles. Their grain size is preferably about 8 nm. The porosity of the nanoparticles amounts to 10%-60% of the total volume of the layer. Coating onto the substrate is by a spraying, immersion, wiping, painting or spreading process. The layer is fired, preferably at a temperature between 430[deg]C and 560[deg]C for about 60 minutes. The surface is thermally-prestressed following heating, by further heating, preferably to about 670[deg]C for about 4 minutes. The hydrophobe is applied or introduced into the heated layer including porous nanoparticles. Before applying the sol-gel layer, the surface of the substrate is activated by corona discharge, flaming, ultraviolet treatment, plasma activation, sand blasting, and/or chemical treatment such as etching. Bonding agents are applied first, from the gas or liquid phase. The hydrophobe is applied by immersion, capillary techniques, centrifugation, spraying, painting, rolling and/or flooding. The hydrophobe is heated preferably for 1 hour, to e.g. 150[deg]C. Its coated thickness lies between that of a molecular monolayer and about 130 nm. The profile and duration of process parameters are adjusted for application of the sol-gel layer together with the hydrophobe, preferably by spraying or immersion.