Disposing single-layer and multiple-layer coatings on articles, e.g., by sputtering or the like, is known in the art. Current sputter-deposited low-E coatings are known in the industry as soft-coatings, as they typically are very easy to damage during normal handling. By way of example, standard sputter-coated low-E coatings suffer from a failure known as scratching and, in general, are considered soft coatings.
The potential for damage to coated articles is a disadvantage typical for many sputter-coated and/or otherwise disposed coatings. Indeed, the potential for damage often prompts manufacturers to take special care during the disposing of the coatings including the steps used therein. the transportation of intermediate and/or finished products, any finishing and/or installation steps, etc. These special measures increase the costs and time required for making coated articles. Even when a wide variety of special precautions are taken, the potential for damage, e.g., by marring is still present, and quite often yield is reduced.
Thus, it will be appreciated that there is a need in the art for techniques for protecting layer stacks disposed on articles.
The inventors of the instant application have realized that the ease with which soft-coatings may be scratched may be attributed, at least in part, to surface roughness of the coatings and also the weak nature of the bonds between the layer stack and the glass and/or the layers in a layer stack. Thus, the inventors of the instant application have discovered that the surface energy can be modified to reduce friction caused by surface roughness, thereby enhancing mar resistance. Indeed, the inventors of the instant application have discovered that by applying a “slippery” overcoat to pre-coated layer stacks, the propensity for scratch marring is reduced. In certain example embodiments, the overcoat may be applied via an evacuative process.
In certain example embodiments of this invention, a method of making a coated article by applying a mar reducing overcoat to an intermediate coated article is provided. The intermediate coated article is provided, with the intermediate coated article comprising a substrate with a single- or multi-layer stack disposed thereon. The mar reducing overcoat is applied to the intermediate coated article via an evacuative process, such that coated article with the mar reducing overcoat has a contact angle greater than, and a surface friction less than, a contact angle and a surface friction of the intermediate coated article.
According to certain example embodiments, the evacuative process may include the following steps. A low vapor pressure material may be provided in liquid form to a heatable vacuum compatible chamber connected to a coater, with a coater vent buffer being interposed between the heatable chamber and the coater. The heatable chamber may be evacuated as the coater pumps to the same pressure as the coater vent buffer. When vacuum is achieved, vapor in the heatable chamber may be built up. When the coater needs to be vented: the vent buffer is vented, and the heated chamber is purged to draw substantially all of the vapor into the coater vent buffer. When venting is complete, the vapor storage buffer is partially evacuated.
First and second valves may be provided to the heatable chamber, with the second valve being located between the heatable chamber and the coater vent buffer, and with the first value being located upstream of the heatable chamber. The evacuating step may comprise opening the second valve and closing the first valve, the building up step may comprise closing the second valve, the purging step may comprise opening the second valve and then opening the first valve, and the partially evacuating step may comprise closing the first valve, waiting a predetermined amount of time, and closing the second valve.
In certain example embodiments of this invention, a coated article is provided. A single- or multi-layer stack is supported by a substrate. A mar-reducing overcoat comprising an organic material is provided, directly or indirectly, on the single- or multi-layer stack opposite the substrate. The coated article including the mar-reducing overcoat has a contact angle greater than, and a surface friction less than, a contact angle and a surface friction of the single- or multi-layer stack supported by the substrate alone.
In certain example embodiments of this invention, an apparatus is provided. A chamber is connected to a coater, with a coater vent buffer being interposed between the heatable chamber and the coater, and with the chamber being configured to contain a low vapor pressure material in liquid form. A vacuum is configured to create vacuum conditions within the chamber. A heating mechanism is configured to selectively heat the chamber and vaporize the liquid form material located therein so as to build up vapor in the heatable chamber when vacuum is achieved. Evacuating means are provided for evacuating the chamber as the coater pumps to the same pressure as the coater vent buffer. Venting means are provided for venting the vent buffer and purging the heated chamber to draw substantially all of the vapor into the coater vent buffer when the coater needs to be vented, and for partially evacuating the chamber when venting is complete.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.