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Article having a scratch resistant lubricated glass surface and its method of manufacture
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Inventors: Scholes, Addison B.;
Assignee: Ball Corporation (Muncie, IN)
Primary Examiner: Lindsay, Jr.; Robert L.
Assistant Examiner:
Attorney, Agent or Firm: Alberding; Gilbert E.
A method of increasing the abrasion resistance of glass articles is disclosed. It has been found that by providing a vitreous substrate with a micro-roughened surface and an overlayer of dry lubricious organic coating, substantially increased lubricity and abrasion resistance is obtained. When the micro-roughened surface is provided by bonding a discontinuous distribution of discrete particulate material to the surface, a substantial increase in abrasion resistance and lubricity is realized even without the overlayer of dry lubricious coating thereby making the present invention particularly adaptable to use in the hot end of a glassware manufacturing process. Further, when the particulate material is fusible at about the annealing temperature of the glassware and is applied at the hot end, the particulate material will protect the glass surface through the hot end by bearing the major part of any loads created by contact between the glassware and other objects in its transport through the hot end. Upon being annealed, the particulate material will fuse and self-heal itself of any damage caused by such contact. In the preferred embodiment, glass frit of a low-fusing temperature having a size range of between under 1 micron to about 100 microns is applied over between 5 percent and 85 percent of the surface area of glassware. The frit is then fused to the glassware and upon cooling, an overlayer of dry lubricious organic coating is applied. The frit is preferably applied electrostatically while the glass is hot through dry powder deposition or with a liquid carrier. Great uniformity in applying minute amounts of particulate material has been achieved by on-site grinding the particulate material to an air-carriable size with a fluid energy mill. The particulate material is air exhausted from the mill and directly applied thereby avoiding problems presented by agglomeration of the low micron range particles. |
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DETAILED DESCRIPTION OF THE INVENTION In accordance with the invention, a scratch-resistant lubricated glass surface is manufactured by providing a charged spray of fine particles of a solid material, such as glass particles having a size of minus 200 mesh capable of adhesion to the glass surface; depositing the fine particles on the glass surface which can be treated for adhesion of the fine particles; and applying to the glass surface, with its adhering fine particles of solid material, a dry lubricious outer coating such as an organic polyolefin like polyethylene.
The fine particles of solid material may be suspended in water which is atomized to form a spray of droplets of liquid carrier including the fine particles of solid material.
The spray can be deposited, preferably electrostatically, on the glass surface which is heated to its annealing temperature and maintained at a spray-attracting potential.
The water will be vaporized, and the fine particles of solid material will be bonded to the glass surface.
Upon cooling of the glass surface below the degradation temperature of the dry lubricious organic materials, it is provided with a coating of such a material.
By such methods, an article having a glass surface comprising a distribution of finely divided particles, such as glass particles having a size of minus 200 mesh, with an over coating of lubricious organic material such as polyethylene, can be manufactured and provided with a desirable scratch resistance and a lubricated coating.
Glassware manufactured with this method exhibit dry surface lubricity and scratch resistance that exceeds commercial standards.
In a commercial glassware production line where the ware is formed, initially cooled, and then annealed, the particulate material is advantageously applied immediately after forming and prior to annealing thereby providing hot end protection.
Preferably such material is fusible, such as glass frit, and has a fusing temperature below the annealing temperature of the glassware
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Optical Systems 
