Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2000-07-21
2002-02-12
Dixon, Merrick (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S195100, C428S198000, C428S339000
Reexamination Certificate
active
06346315
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to improved house wares including frangible wares such as personal-use glassware, plateware of earthenware and china, and to ceramic wares; and to a method for applying a decorative, protective and safety coating to the wares, and to providing wares having a protective coating, for decoration.
2. Description of the Prior Art
In the provision of personal use frangible wares, it is common practice to decorate the visible surfaces, frequently in plain colour, and also with a wide variety of patterns, printed matter,etc. In the case of glass-ware, such as drinking glasses, particular difficulty is experienced in providing low cost decoration, due to difficulties experienced in effecting transfer onto the surface of the glass of a durable, or readily protected image.
Existing methods of decoration include screen printing with inks containing ground glass, and transfer printing from a decal which has been printed with ground glass inks.
The printed glassware must then be fired in a Lehr type conveyorized oven or hand loading into a convection oven, and fired at 1200 F. degrees in order to fuse the ink.
A further drawback of existing systems for decorating personal use ceramic and other frangible wares are the imperative health laws, requiring the use solely of non-toxic material, (lead and cadmium being toxic) thereby precluding the use of a wide alternative range of available industrial coloured materials, which fall outside such legal requirements.
Concerning the matter of toxicity, while processes do exist in which lead glazes can be applied that are non-toxic, in the case of ceramic wares such as mugs that are obtained from sources over which effective manufacturing control cannot be exercised, the possibility exists that the glaze used may be a toxic lead glaze.
In the absence of a low cost, rapidly determinable toxicity test by which the glaze toxicity of such wares can be economically determined, there exists a need to be able to protectively coat the internal surfaces of such wares in a manner to effectively seal off the internal wetted surfaces, so that toxic leaching cannot occur.
The external coating of glass containers with plastic, for purposes of safety, is well known. Thus, U.S. Pat. No. 3,415,673 Dec. 10, 1968, Clock, incorporated by reference, teaches the coating of glass containers such as bottles with a thin plastic coating. Surface pre-treatment with a polyethylene imine to promote adhesion is followed by an application of a copolymer coating in the range of 0.002-0.150 inches, i.e. 2-150 mil. The copolymer comprises a major portion of ethylene, and an acidic co-monomer of a specified wide group of acids, being applied to a considerable thickness as an electrostatic powder spray. A varnish finish is then applied by dip coating.
Many other patents relate to the coating of frangible articles such as bottles etc., primarily for safety purposes.
U.S. Pat. No. 4,065,590 Dec. 27, 1977, teaches the application of a modified protective plastic coating to glass soft drink bottles for carbonated beverages, to diminish the likelihood of fracture of the plastic while increasing its glass-retentive capability, so as to secure, or at least localize the dispersal of glass shards and fragments, in the event of fracturing of the bottle. Subsequent attempts have been made by the present inventor to adapt the above-mentioned ('590) protective plastic coating for glass soft drink bottles to other uses, in which a further, polyurethane coating of heat resistant plastic was applied in protective relation over a first ('590) coating to form a combined coating, with the intention of protecting the patented coating against degradation within a hot environment, to thereby enable use of the vessel in a commercial dishwasher, operating at a temperature of 82 degrees C. or greater. These tests were unsuccessful as the very first dishwashing resulted in the peeling off of the combined coating.
U.S. Pat. No. 4,256,788 Gras, teaches the use of a urethane protective coating applied over a silane sub- coating, the coatings being applied as pastes. With irregularities in paste consistency, and in the absence of a suitable method for readily and evenly applying the paste coatings to the glass surfaces, product appearance is unacceptable, and the quantity of the paste applied is somewhat excessive (50-250 microns thick) and uneconomical. The glasses are greatly strengthened, but tests showed that the shards were not retained at or adjacent the point of impact, but were scattered. Also, the aesthetic appearance of the glasses was unacceptable, with diminished clearness and optical brightness, while the necessary thickness of plastic was a significant adverse cost factor.
Traditionally, glass and ceramics have been decorated by applying ceramic inks by way of screen printing or transfer printing, and fusing the ceramic inks at 1200 F. degrees.
Also well known is the application of precious metals, silver and gold that are applied by way of a coating wheel and then fired in the manner of ceramics. These metals are subject to tarnish, and tend ultimately to fail under normal dishwasher exposure.
Another new process, known as “sublimation”, now used solely on ceramic wares, generally white products having a clear polyester coating, involves the application of organic inks by a transfer process, followed by vaporization of the inks to embed them into the polyester coating. The use of such organic inks permits the provision of a wide range of colours. In the case of glassware, it has been found that due to the substantially non-adhesion of polyester to glass, the sublimation process cannot be used, being thus limited to use with ceramics. In such cases, the polyester has been found to be vulnerable to chipping, and when chipped, the polyester coating becomes vulnerable to separation on immersion in hot water. It appears significant that in the case of a number of prior patents that have been consulted, having teachings bordering on the present invention, none of those teachings appear to be directed to practicable products suitable for practical use, nor do the respective processes provide products that meet the needs of the glass or ceramic drinking or serveware market. Also, no attempt appears to have been made to solve the problems associated with providing protected wares suitable for use with commercial or domestic dishwashers.
SUMMARY OF THE INVENTION
The present invention provides a method of providing housewares, including frangible ware with a protective safety coating, and serving as a substrate suited to the application of decorative coatings.
The subject coating is aesthetically acceptable and commercially viable, being applied as a protective coat over a surface portion of a house ware, into which coat colour may be incorporated. The process consists of the steps of: applying to the subject ware a first organo-functional silicone coating as a coupling coating, to promote adhesion thereto of a subsequent coating; and applying the second (subsequent) coating, which is protective against physical, chemical and heat damage.
The second coating is particularly susceptible of receiving visual decoration, selected from the group consisting of colour and decoration, and combinations thereof and applied to the second coating. Such decorative application may form a part of the ongoing process, or may be applied subsequently, possibly elsewhere.
In some instances where decoration has been applied, a further outer protective plastic coating may be applied, the second and outer coating being selected from the group consisting of thermosetting plastics and thermoplastics and having a useful temperature of up to about 400 F. degrees.
The second coating, preferably a urethane coating, bonds securely to the coupling coating, even in the case of glass.
The urethane coating can be clear, tinted with dyes, or of a solid colour by the addition of organic pigments to the urethane, prior to the possible addition of furt
Dixon Merrick
Eggins D. W.
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