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 Arc-extinguishing composition and articles manufactured therefromUSPTO Application #: 20060006144Title: Arc-extinguishing composition and articles manufactured therefrom Abstract: An arc-interrupting compound, such as melamine, and to a method of extinguishing an arc by disposing the composition along the path of the arc, for contacting the arc. In one embodiment, the binder, or at least a portion of the binder, is a polymer that contains a functional group that binds to a coupling agent that is included in the arc-extinguishing composition. The coupling agent ties the polymeric binder to the arc-extinguishing compound, e.g., melamine, to provide new and unexpected physical strength and stability to the composition. In this embodiment, the molded composition, including the arc-interrupting compound coupled to the binder, maintains excellent arc-interrupting capability, while providing chemical stability and electrical insulating properties as well as unexpected physical strength. (end of abstract) Agent: Marshall, Gerstein & Borun LLP - Chicago, IL, US Inventor: Jeffrey A. Moore USPTO Applicaton #: 20060006144 - Class: 218150000 (USPTO) Related Patent Categories: High-voltage Switches With Arc Preventing Or Extinguishing Devices, Arc Preventing Or Extinguishing Devices, Arc Chute Assembly, Material The Patent Description & Claims data below is from USPTO Patent Application 20060006144. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD [0001] The present invention relates to arc-quenching materials and articles fabricated therefrom for high-voltage electrical devices and equipment such as circuit interrupters wherein, under certain conditions of operation, a high-voltage electrical arc is produced that is either desirably, or by necessity, quenched. More particularly, the present invention relates to a composition to achieve arc-quenching and structural properties in devices such as circuit interrupters, high-voltage fuses, circuit breakers, and separable cable connectors. BACKGROUND AND PRIOR ART [0002] To provide effective circuit interruption in circuit interrupters, fuses, and the like, it is desirable to utilize an arc-quenching material or composition to quench and suppress arcing during electrical contact separation or fuse operation. Of necessity, the arc-quenching materials should include characteristics and properties sufficient for the particular application so as to be effective in quenching arcs via the rapid evolution of quenching gases. Of course, the evolved quenching gases should also be relatively nonconductive. In addition, it is also important that the arc-quenching materials are capable of being molded or otherwise fabricated into suitable articles and shapes having desirable structural properties, thermal stability, and environmental resistance to thermal cycling. [0003] In many circuit-interrupting devices, it is typical to utilize a trailer/liner configuration, as well known in the art, so that the arc is drawn into an annular space defined between the trailer and the liner, each of which is preferably fabricated from an arc-quenching composition. The action of the gases produced by the trailer and/or liner on the confined arc tends to deionize the arc and force its extinction. Examples of trailer/liner configurations are shown in the following U.S. Pat. Nos. 2,351,826; 2,816,980; 2,816,978; 2,816,985; 4,103,129; and 3,909,570 and in Descriptive Bulletin 811-30 of S&C Electric Company, Chicago, Ill. Similarly, in high-voltage fuses, which also can be characterized as circuit interrupters, a sleeve or liner surrounds the path of the arc during fuse operation with the sleeve or liner being fabricated from an arc-extinguishing material. Reference may be made to U.S. Pat. Nos. 3,629,767 and 4,307,369 for an example of fuses of this type surrounded by arc-extinguishing sleeves or liners. [0004] Typical arc-extinguishing materials and their properties are disclosed in the following U.S. Pat. Nos. 3,582,586; 3,761,669; 4,251,699; and 4,444,671. One composition in U.S. Pat. No. 3,582,586 includes melamine and polyethylene. While this composition is generally suitable for various applications and exhibits desirable arc-quenching properties, for many applications, it would be desirable to achieve a composition with improved mechanical characteristics and environmental resistance to thermal cycling while maintaining the desirable arc-quenching characteristics. [0005] One of the most effective arc-interrupting compounds used in this art for arc-quenching is melamine (C.sub.3N.sub.6H.sub.6) which is a white crystalline powder having a melting point of about 350.degree. F. and sublimes at its melting temperatures and below. Other, related nitrogen-containing compounds are also recognized in the prior art as arc-quenching or arc-interrupting compounds and are disclosed in Amundson et al U.S. Pat. No. 2,526,448. Melamine and its related compounds have excellent arc-interrupting characteristics but suffer from extreme structural weakness, so that they cannot be molded or pressed into satisfactory structural shapes except in combination with a suitable binder. [0006] For a binder to be most effective in an arc-quenching or arc-interrupting composition it should volatilize or decompose in the presence of an electric arc, as does melamine. The binder, however, does not necessarily have to provide any arc-interrupting or arc-extinguishing characteristics to the composition, since, in some cases, the arc-interrupting characteristics of the melamine included in the composition is sufficient for arc-interrupting purposes. The binder, therefore, is primarily included for purposes of providing the melamine-containing composition with sufficient moldability and to provide a molded structure of sufficient physical strength, physical and chemical stability, and electrical insulating properties to provide a structurally sound, molded product. The physical strength of the molded product is most evident in its tensile strength, its percent elongation, and the amount of energy required to break the molded structure, or impact strength. [0007] Structural damage, i.e., cracks have been found in prior art devices containing polyethylene as its primary binder material, and such damage is unacceptable in this art, since the break point allows another air space for the gases and arc to fill, thereby significantly lessening the arc-interrupting properties of the arc-interrupting device. Further, failed arc extinguishing compositions that contain melamine usually fail because the pressure wave associated with the arc causes the composition to physically break before it has an opportunity to extinguish the arc. The arc-extinguishing compositions described herein extinguish the arc without physically breaking. Thermoplastic polymeric binders have been found to be the most useful in arc-interrupting compositions based upon melamine or similar compounds, since the thermoplastic binders volatilize or decompose in the presence of an electric arc at lower power conditions than necessary to sublime melamine thereby producing large volumes of gas to drive the melamine into the core of the arc and to extinguish the arc under a wide range of power conditions. Further, the thermoplastic binders provide compositions with good molding characteristics, stability and electrical insulating properties. [0008] Typical thermoplastic polymeric resins known to be useful as binders in melamine-based arc-interrupting compositions include polyethylene, polypropylene, polytetrafluoroethylene, acrylics, polystyrene, cellulosics polyamides (nylons), polyacetals (DELRIN), polyphenylene oxides, blends such as ABS, and polyimides. Other binders, such as thermosetting resins, epoxy resins, polyester resins, phenolic resins, and the like, also are known to be useful as binders in arc-interrupting compositions. It is also known to include elastomeric, rubber-like materials as a portion of the binder in melamine-based arc-interrupting compositions such as butyl compounds, isoprene-based compounds, neoprene-based compounds and other synthetic elastomers. [0009] In this assignee's U.S. Pat. No. 4,975,551, there is disclosed a binder comprising a carboxylic acid group-containing polymer, particularly a copolymer of two different monomers, at least one of which contains a carboxylic acid moiety, such as an ethylene acrylic acid copolymer. As disclosed, the carboxylic acid functionalities of the binder interact with arc-extinguishing compounds having carboxylic acid-active sites, such as amine, thiol, alcohol, halogen, and the like sites, to provide added physical strength and stability to the composition. The molded composition, including the arc-interrupting compound and the binder, maintains excellent arc-interrupting capability, chemical stability and electrical insulating properties as well as increased physical strength. SUMMARY [0010] In brief, the present invention is directed to a new and improved arc extinguishing composition including, a new and improved binder for compositions containing an arc-interrupting compound, such as melamine, and to a method of extinguishing an arc by disposing the composition along the path of the arc, for contacting the arc. In one embodiment, the binder, or at least a portion of the binder, is a polymer that contains a functional group that binds to a coupling agent that is included in the arc-extinguishing composition. The coupling agent, which may be a polymer that is compatible with the binder, contains a functional group that binds to the arc-extinguishing compound to tie the polymeric binder to the arc-extinguishing compound, e.g., melamine, to provide new and unexpected physical strength and stability to the composition. In this embodiment, the molded composition, including the arc-interrupting compound coupled to the binder, maintains excellent arc-interrupting capability, while providing chemical stability and electrical insulating properties as well as unexpected physical strength. [0011] In other embodiments of the arc-extinguishing compositions and articles described herein, the melamine or other arc-extinguishing compound provides unexpectedly better results when incorporated into the composition in finely divided form; and improved results are provided by combining a plasticizer for the polymeric binder. [0012] At least three embodiments of the arc-quenching materials and articles are described herein--each embodiment providing improved mechanical properties and/or arc-extinguishing results either alone or in combination with one or both of the other embodiments. Each of these three individual embodiments can be included alone in the materials and articles described herein or any two or three of these embodiments can be combined to further improve the materials and articles described herein. [0013] In brief, the three embodiments are as follows: [0014] (1) Incorporating a coupling agent into the arc-extinguishing composition that interacts mechanically and/or chemically with both the arc-extinguishing material and the polymeric binder to improve the mechanical properties and/or the arc-extinguishing properties of the composition and articles described herein. [0015] (2) Incorporating a plasticizer for a base binder polymer (e.g., caprolactam for a nylon base polymer) into the arc-extinguishing composition to enhance elongation and other mechanical properties, especially reducing brittleness of the arc-extinguishing composition; and [0016] (3) Incorporating a finely divided arc-quenching material into the arc-extinguishing composition. Preferably, the arc-quenching material is selected from the group consisting of melamine, guanidine, guanidine acetate, guanidine carbonate, 1,3-diphenylguanidine, cyanurates, melamine cyanurates, hydantoin, allantoin, urea, urea phosphate, benzoguanamine, dithioammelide, ammeline, and a cyanuric halide, and/or derivatives and/or mixtures thereof. In accordance with this embodiment, the arc-quenching material should have a particle size distribution such that at least 90% by weight of the particles have a particle size less than about 200 .mu.m, preferably less than about 150 .mu.m, more preferably less than about 100 .mu.m, and most preferably less that about 50 .mu.m. To achieve the full advantage of this embodiment, at least 95% by weight of the arc-quenching particles having a particle size less than about 50 .mu.m. [0017] The arc-quenching compositions described herein are suitable for deionizing and extinguishing a high-voltage electrical arc. The compositions include effective amounts of an arc-extinguishing material, such as melamine, and sufficient binding polymer to achieve the desired combination of arc-extinguishing properties and structural characteristics, such as tensile strength, elongation, environmental resistance to thermal cycling, and the like. Additionally, the composition for various applications and uses may include additives, fillers or fibrous materials. [0018] The composition is homogenized by compounding the constituents using dry blending, roll mill, extrusion and/or other plastic compounding techniques to obtain the molding resin compositions. The molding resin then is molded into articles of the desired shape using plastic processing techniques, such as injection molding, extrusion, and the like. In a preferred composition, for example, to form a trailer for an interrupter, a nylon base polymer binder is combined with melamine and an anhydride-functional coupling agent to achieve the desired arc-extinguishing and mechanical characteristics by virtue of the bonding and/or miscibility between the melamine, nylon, and the anhydride-functional coupling agent. [0019] In other embodiments, as outlined above, the composition includes non-functionalized base polymeric binder(s) with or without the coupling agent and contains a finely divided arc-extinguishing material and/or a plasticizer for the base polymeric binder(s). [0020] Accordingly, one aspect of the compositions, articles and methods described herein is to provide a new and improved arc-quenching composition comprising effective proportions of an arc-extinguishing compound, such as melamine, and a polymeric binder containing coupling agent-interactive moieties, such as an ethylene maleic anhydride polymer, and a suitable coupling agent capable of chemically and/or mechanically attaching the arc-extinguishing compound to the coupling agent and coupling the arc-extinguishing compound to the polymeric binder to achieve improved strength and desirable environmental resistance to thermal cycling. [0021] Another aspect of the compositions, articles, and methods described herein is to provide a new and improved arc-extinguishing composition with improved mechanical characteristics, when molded, while exhibiting at least the same desirable electrical arc-extinguishing characteristics of previously available arc-extinguishing compositions and articles. [0022] Another aspect of the compositions, articles and methods described herein, is to provide a new and improved arc-extinguishing composition including an arc-interrupting compound and a polymeric binder wherein the binder is a polymer, or copolymer formed from two different monomers, including coupling agent reactive groups or moieties for coupling the binder to the arc-interrupting compound through a coupling agent. [0023] Another aspect of the compositions, articles and methods described herein, is to provide a new and improved arc-extinguishing composition including an arc-extinguishing compound having at least one site reactive with a coupling agent-contained functional group; or a polymeric binder material including a plurality of reactive coupling agent contained functional moieties, such that when the composition is molded under heat and pressure, the arc-extinguishing compound and the polymeric binder will chemically bond (including ionic and/or covalent bonds) to the coupling agent to provide new and unexpected physical strength in the molded composition. [0024] Still another aspect of the compositions, articles and methods described herein, is to provide a new and improved arc-interrupting composition including an arc-interrupting compound having at least one reactive amine site in its molecule, such as melamine, and a thermoplastic resin binder material containing an amine-reactive site and a binder-reactive site; together with a suitable coupling agent for coupling the arc-interrupting compound to the polymeric binder through the coupling agent. Continue reading... Full patent description for Arc-extinguishing composition and articles manufactured therefrom Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Arc-extinguishing composition and articles manufactured therefrom patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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