Low-emissivity, soil-resistant coating for glass surfaces

Abstract

A glass article that has a water-sheeting coating and methods of applying coating to a substrate are described. In certain embodiments, a water-sheeting coating 20 comprising silica is sputtered directly over a pyrolytic dielectric film over a glass sheet. In some cases, the exterior face of this water-sheeting coating is substantially non-porous but has an irregular surface. The water-sheeting coating causes water applied to the coated surface to sheet, making the glass article easier to clean and helping the glass stay clean longer. One embodiment provides an IG unit having a low-emissivity coating on its #2 surface, and having on its #4 surface a sputtered silica film over a pyrolytic dielectric layer.

1 . A multi-pane insulating unit comprising spaced apart first and second panes, wherein the first pane has an interior face that bears a multiple-layer infrared-reflective coating and that is oriented toward the second pane, and wherein the second pane has an exterior face bearing a low-emissivity water-sheeting coating, the low-emissivity water-sheeting coating comprising a pyrolytically applied dielectric layer carried by said exterior face and an exterior layer of silica sputtered directly onto an outer surface of the pyrolytically applied dielectric layer.  
     
     
         2 . The multi-pane insulating unit of  claim 1  wherein the exterior layer of silica is substantially non-porous.  
     
     
         3 . The multi-pane insulating unit of  claim 1  wherein the exterior layer of silica has a median thickness of between about 15 angstroms and about 350 angstroms.  
     
     
         4 . The multi-pane insulating unit of  claim 3  wherein said median thickness is between about 15 angstroms and about 150 angstroms.  
     
     
         5 . The multi-pane insulating unit of  claim 1  wherein the low-emissivity water-sheeting coating reduces the contact angle of water on said coated exterior face to below about 25°.  
     
     
         6 . The multi-pane insulating unit of  claim 1  wherein the pyrolytically applied dielectric layer is a pyrolytic tin oxide.  
     
     
         7 . The multi-pane insulating unit of  claim 6  wherein the pyrolytic tin oxide comprises a layer of tin oxide deposited by reacting at a temperature of at least about 750° C. a reactant mixture comprising an organotin compound, water and oxygen.  
     
     
         8 . The multi-pane insulating unit of  claim 1  wherein the pyrolytically applied dielectric layer comprises a fluorine-doped metal oxide.  
     
     
         9 . The multi-pane insulating unit of  claim 8  wherein the fluorine-doped metal oxide comprises a fluorine-doped tin oxide deposited by reacting a reactant mixture comprising an organotin compound, HF, water and oxygen.  
     
     
         10 . The multi-pane insulating unit of  claim 1  wherein the multiple-layer infrared-reflective coating comprises, in sequence moving outwardly from said interior face, at least one dielectric layer, a reflective metal layer, and a second dielectric layer, the infrared reflective coating having a transmittance of at least about 70% in the visible spectrum.