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Tarnish resistant compositions and methods of using sameRelated Patent Categories: Stock Material Or Miscellaneous Articles, Hollow Or Container Type Article (e.g., Tube, Vase, Etc.)Tarnish resistant compositions and methods of using same description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20050287316, Tarnish resistant compositions and methods of using same. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] This invention relates to tarnish resistant compositions and methods of using same. More particularly, this invention relates to materials such as fabrics having at least finely divided colloidal metal particles such as copper or silver particles therein. When used to protect silver and/or gold articles, the compositions and methods of the invention provide superior tarnish resistance. BACKGROUND OF THE INVENTION [0002] Copper, nickel, silver and gold containing articles such as jewelry, tableware and the like, tarnish in a short period of time under ordinary conditions of storage. The tarnish is caused by certain gases in the atmosphere such as sulfur containing compounds, hydrogen sulfide gas, halogens, halogen containing vapors and the like, which cause discoloration or tarnish. For example, hydrogen sulfide gas reacts with silver articles to produce a film of silver sulfide on the articles. This film quickly turns into a black coating on the article. This coating is the discoloration known as tarnish. [0003] Some materials and methods have been developed to address the problem include providing a protective coating on the surface of the silver, providing various storage containers, or combinations thereof, to block access of corrosive gases to the articles. However, each of the available materials and methods still suffer significant shortcomings. [0004] It is known to provide a coating of volatile organic corrosion inhibitor (VCI) on articles made of sensitive metals. The VCI, for example, cyclohexamine ammonium benzoate, evaporates, coats the metal to be protected, resulting in corrosion resistance. A limitation to the use of VCI's is that they are unable to maintain efficacy over a sufficiently long period of time. The protection only lasts as long as the corrosion inhibitor continues to evaporate. [0005] U.S. Pat. No. 4,944,916 to Franey discloses a polymeric storage bag, such as polyethylene, that is formed in the presence of a scavenger such as copper or aluminum. When metal articles are placed in the bag the scavenger particles attract the sulfide gases away from the metal article before the sulfides can reach the metal articles. An inherent problem with these metals is that copper reacts somewhat with atmospheric carbon dioxide to form surface carbonates and aluminum immediately reacts with atmospheric oxygen to form surface oxides. These surface coatings impede reaction with sulfide gas and diminish scavenging performance. [0006] It has long been known to store silverware in treated fabrics so as to reduce the formation of tarnish. U.S. Pat. No. 1,766,646 to Grinnell discloses a material impregnated with a silver composition which acts as a scavenger for sulfur containing compounds. The fabric is impregnated by passing fabric through a bath containing silver nitrate solution followed by a bath containing sodium carbonate solution which precipitates the silver onto the fabric. The mechanism of action is as described previously, with the scavenger competing with the metal article for the sulfide so as to preferentially absorb the sulfide before the metal article absorbs it. Silverware stored in the fabric or in boxes lined with such fabric is protected from tarnish to a certain degree. [0007] The inventor has performed experiments duplicating the methods of U.S. Pat. No. 1,766,646 and has found that this technique does not result in an significantly different result than zinc acetate treated fabric. One possible reason for this result is that, during the liquid treatment process with sodium carbonate, the silver particle surface is inactivated by reaction with the carbonate solution. [0008] Additional compounds which have been shown to provide some protection against tarnish include activated carbon, natural and synthetic zeolites, silica gel and activated alumina. However, the protection provided by the known compounds is neither complete nor long lasting. Use of presently available tarnish inhibiting compositions still results in some tarnish, although to a lesser extent than if no protection is used. However, conventional tarnish resistant compositions are also less effective over time. As the scavenger is used up, the tarnish resistant compositions become less effective and ultimately must be replaced. [0009] There is a present and long standing need for compositions that resist tarnish that does not suffer the disadvantages of the prior art. Specifically, it would be advantageous to have a tarnish resistant composition that provides substantially complete tarnish resistance over an extended period of time. SUMMARY OF THE INVENTION [0010] The present invention provides a tarnish resistant composition including a plurality of colloidal metal particles including at least one of colloidal: copper, silver, zinc and nickel particles, and a porous material containing the colloidal particles. [0011] Also provided is a container for storing tarnishable articles, including a plurality of colloidal metal particles including copper and/or silver colloidal particles, a porous material containing the colloidal particles and a solid sided box having one or more interior surfaces lined with the porous material. BRIEF DESCRIPTION OF THE DRAWINGS [0012] FIGS. 1A and 1B are perspective views of an embodiment of the invention in which a storage box lined with a tarnish resistant composition of the invention. [0013] FIGS. 2A, 2B and 2C are perspective views of an alternative embodiment of the invention which is a multi-compartment jewelry box lined with a tarnish resistant composition of the invention. [0014] FIG. 3 is a perspective view of an alternative embodiment of the invention which is a fabric pouch including a tarnish resistant composition of the invention. [0015] FIGS. 4A and 4B are perspective views of an alternative embodiment of the invention which is a fabric pouch including a tarnish resistant composition of the invention. [0016] FIG. 5 is a perspective view of an alternative embodiment of the invention which is a sachet containing a porous material loaded with colloidal metal. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0017] The inventor has surprisingly found that use of finely divided particles applied to a porous material provides heretofore unprecedented resistance to tarnish. Although not intending to be limited to any one particular theory of operation, it has been established that the extraordinarily large surface area of the finely divided particles is at least in part responsible for the effectiveness of the compositions of the invention. The large surface area provides much greater reactivity of the colloidal particle with potentially tarnishing agents as compared to known tarnish resistant compositions. This greater reactivity translates into far superior tarnish resistance than is currently available. Furthermore, the greater surface area allows for the superior tarnish resistance to occur for unprecedented extended periods of time without diminishing. [0018] One might assume that colloidal metal particles in dry, fine powder form, would have a tendency to fall off of a fabric surface. Surprisingly, this has not been the case. Although not intending to be limited to any particular theory, it is believed that the particles are so fine that they adhere to or become entrapped among the fibers of the fabric, and can withstand handling, cutting, and the like, without appreciable loss from the fabric. [0019] Compositions of the Invention Continue reading about Tarnish resistant compositions and methods of using same... 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