Thermostable glazing

Details Thermostable glazing Thermostable glazing

1999-06-08

2004-10-19

McNeil, Jennifer (Department: 1775)

Stock material or miscellaneous articles

Composite

Of quartz or glass

C428S699000, C428S701000, C428S702000

Reexamination Certificate

active

06805960

ABSTRACT:

INTRODUCTION
The present invention is directed to glazing, such as automotive and architectural glazing, and the like, having a solar control coating on a surface of a substantially transparent substrate. More particularly, the present invention is directed to thermostable glazing having a thermostable solar coating on such substrate for anti-solar properties, as well as to methods of manufacturing such thermostable glazing.
BACKGROUND
Coated glazing products having anti-solar properties, that is, low transmittance of wavelengths in the infra-red range, are known to those skilled in the art. Also, low emissivity coatings for glazing products are disclosed, for example, in European patent application 0,104,870 to F. H. Hart entitled Low Emissivity Coatings On Transparent Substrates. That document discloses low emissivity silver coatings comprising a layer of silver and an overlying anti-reflective layer of metal oxide. Cathodic sputtering is disclosed for producing such low emissivity coatings having a small amount of an additional metal dispersed non-uniformly in the silver layer. Sputter deposition of a multi-layer, low emissivity coating is described, for example, in European Patent Application 0,418,435 to Nalepka. Similarly, a multi-layer low emissivity coating is disclosed in European patent application 0,418,435 to Hayward et al. The multi-layer coating of Hayward et al. is said to comprise a layer of sputtered zinc, tin, titanium, indium/tin or bismuth oxide, next a layer of sputtered silver or silver alloy, then a layer of sputtered titanium or stainless steel and finally a layer of zinc, tin, titanium, indium/tin or bismuth oxide. Such multi-layer film is said to have excellent visible light transmission while controlling both near infra-red solar energy and far infra-red reflected energy. A temperable coated article is suggested in U.S. Pat. No. 5,552,180 to Finley et al. The coated article of Finley et al. employs a metal-containing film such as titanium nitride which ordinarily oxidizes at the high temperatures encountered during glass tempering, along with an overcoating of a protective layer of a silicon compound and an undercoating with a stabilizing metal-containing layer. In U.S. Pat. No. 3,990,784 to Gelber a multi-layer coating for architectural glass is suggested, comprising first and second metal layers with a dielectric layer disposed between them. Gelber suggests that the transmission properties of the coating can be changed independent of its reflection properties, by varying the thickness of the metal layers while maintaining the ratio of their thicknesses constant.
In general, conventional low emissivity coating systems employ a first dielectric film or layer directly on a surface of a transparent substrate, followed by metal film and then a second dielectric film over the metal film. Where the metal film employs silver or other easily oxidized metal, a buffer film typically is positioned between the metal and the second dielectric films. The buffer film substantially inhibits migration to the metal film of oxygen or other reactive gas employed in the deposition of the second dielectric film. Conventional dielectric materials include, for example, oxides such as zinc oxide, tin oxide, zinc/tin oxide composites, indium/tin oxide, bismuth oxide, titanium oxide, etc., and nitrides such as tin nitride. Co-pending application U.S. Ser. No. 09/098,316 (Demiryont et al.) discloses a multi-layered coating in which tungsten oxide is employed as a dielectric material. The metal layer may be formed of silver, although other metal layers also are known to those skilled in the art. Suitable buffer layers for protecting a silver or other metal film have typically included, for example, a film formed of sub-oxide of chrome or chrome
ickel or nitride of silicon or titanium with a thickness of, e.g., 15 Å to 60 Å. The thickness of the metal film is selected to provide adequately low emissivity while maintaining sufficiently high transmittance of visible light to meet the requirements of the intended application. The thickness of the bottom and top dielectric films is selected typically to achieve adequate anti-reflectance for the metal film, whereby the entire multi-layer coating has improved transparency to visible light.
Various difficulties have been encountered by those skilled in the art in developing commercially suitable coatings for architectural and automotive glazing. Both architectural and automotive applications require materials able to withstand applied force, e.g., as caused by pressure or temperature gradients between the internal and external surfaces, changes in load resulting from building sway, road vibration, wind or direct impact Typically, window glass employed in vehicles or buildings is ‘tempered’ or ‘annealed’, a strengthening process which entails exposure to high temperatures followed by gradual cooling. In glazing for automobiles or trucks, such heating may also be required for bending the glazing (e.g., a windshield, sunroof or other view panel) into a desired shape. Prior art coatings cannot adequately withstand exposure to the high temperatures required for such bending or other heat treatment of a glass substrate, e.g., 570° C. to 610° C. for bending and 600° C.-650° C. for tempering soda-lime-silica glass, unless thermally shielded , e.g., by a protective layer such as a metal layer. That is, they would lose their characteristic solar control optical properties upon exposure to such thermal tempering, and therefore, such prior known solar coatings must be applied after tempering or shaping of the glass substrate. This is particularly disadvantageous in the coating of bent or curved glazing, since specialized equipment must be used in order to apply a coating to a non-flat surface. There is, therefore, need in this technology area for heat-stable or thermostable solar coating in order to allow the easy and inexpensive coating of stock, flat ‘blanks’ of glass or other transparent glazing material using standardized coating equipment, such that coated material may be produced and stored for future custom processing (i.e. tempering and/or bending).
There has long been need in the glazing industry for a solar coating which can be uniformly deposited by D.C. magentron sputtering onto large surface areas with fast deposition rates, low deposition power density, good film quality, including high film durability and long shelf life. As used here, large area deposition refers to deposition onto transparent substrates suitable in size for architectural and automotive glazing applications. Fast deposition rate is desirable, since it can reduce the time and cost of producing the coated articles. Long lasting source material to deposit reproducible films also is desirable. Low deposition power density is desirable both to reduce the cost of energy employed in manufacturing the coated article and to provide more uniform coating thickness and density. The reference here to a coated substrate having long shelf life is intended to mean, especially, that the coated surface can be exposed to air for hours or even days without substantial degradation of film quality, for example, due to migration of oxygen or moisture from the air into the coating to react with the coating materials. In that regard, in prior known manufacturing processes substantial production wastage occurs when a coating on a glazing panel deteriorates significantly if it is not immediately laminated or otherwise assembled into a multi-pane window which protects the coating from exposure to air. Increasing the time period during which a coated glazing panel can be stored prior to being laminated or assembled in this fashion provides significant production flexibility and consequent reduction in processing cost and complexity.
It is an object of the present invention to provide thermostable glazing meeting some or all of these long-felt industry needs. In particular, it is an object of at least certain preferred embodiments of the invention to provide thermostable glazing c

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