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Strings for racquetsRelated Patent Categories: Games Using Tangible Projectile, Player Held And Powered, Nonmechanical Projector, Per Se, For Projecting Aerial Projectile By Striking; Part Thereof Or Accessory Therefor, Racket Or Paddle; Accessory Therefor (e.g., A Tennis Racket, Tennis Racket Press, Etc.)Strings for racquets description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060084532, Strings for racquets. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND [0001] The present invention relates to strings for sporting applications, and particularly to strings for racquets such as tennis racquets, badminton racquets, squash racquets, racquetball racquets and the like. [0002] Racquet strings must satisfy competing requirements. In a tennis racquet, for example, the principal requirements are playability and durability and it is difficult to satisfy both requirements in a single racquet string type. String construction and material selection has heretofore required a compromise between acceptable playability and durability. [0003] During play, particularly in tennis, the ball is usually hit with some degree of spin. To generate spin, the strings are brushed against the ball to impart a tangential force to it. This brushing action causes the individual strings to slide over one another and wear against each other. The rubbing action of one string against another as well as the impact of the ball creates notches in the strings at the inter-string contact point. These notches are the primary reason for string breakage; as the notching becomes more severe, the tensile strength of the string weakens and eventually it breaks. The friction between the ball and the string during contact with the string surface also causes some string wear. [0004] Several materials have been used in racquet strings in order to achieve a balance of durability and playability. One material, natural gut, enjoys a reputation for unmatched playability. Unfortunately, gut strings have a short life due to notching and wear. Few recreational players use gut strings because they are expensive and wear quickly. Many synthetic string materials, sizes and constructions have been proposed as alternatives to gut. Such synthetics generally are more durable than gut, but are not as playable. [0005] The most common synthetic material is nylon. Although more modern fibers, such as PEEK and aramid fibers, such as Kevlar.RTM. are used in racquet strings, nylon multi-filament strings are generally accepted as among the most playable synthetic materials. Nylon strings demonstrate improved durability over gut, but even nylon strings are subject to frequent breakage by certain players, particularly power hitters and those who hit the ball with a lot of spin. [0006] Nylon strings have been proposed in many mono-filament and multi-filament constructions, the more durable strings being the mono-filaments and the more playable strings being the multi-filaments. Within the range of mono-filaments and multi-filaments there are a variety of constructions that have been used to either tailor the durability or the playability of the string. [0007] Coatings have been proposed to improve the abrasion resistance of strings. For example, strings have been dipped or coated with polytetrafluoroethylene in an attempt to reduce the friction between strings, which causes notching. Other attempts have included adding hard, abrasion resistant coatings to the exterior of a string. Such coatings have generally failed because they are inelastic and do not adhere well to the nylon surface as the string stretches in use. [0008] To improve the durability of nylon strings, the addition of high strength fibers such as aramids to multi-filament constructions has been proposed. However, the addition of stiff aramid fibers to a string matrix dramatically reduces the playability of the strings. Nomex, which has better elastic properties than other aramids, has been added to the core of nylon strings with some success with regards to durability, but with a significant tradeoff with regard to playability. [0009] An accepted measure of playabiltiy is dynamic modulus, which is the ratio between the increase of tension and the elongation of a string caused by dynamic impact. This is a measure of how stiff a string is under dynamic conditions similar to that of being struck with a tennis ball during play. To be playable, a racquet string must show elastic properties under dynamic conditions and deform under a given impact. Strings with low dynamic modulus are less stiff and therefore have better playability than strings with a high dynamic modulus, which do not stretch as much and therefore feel stiff. Gut strings may have a dynamic modulus of as low as 17-26 kN/m. In contrast, high strength fibers such as Kevlar may have a dynamic modulus of 88 kN/m to 140 kN/m or more. Nylon strings have a dynamic modulus in a range of about 25 kN/m to about 45 kN/m. [0010] Another factor affecting both durability and playabiltiy is string size, or gauge. For example, a 16 gauge string generally has a larger diameter than a 17 gauge string. Accordingly, the 16 gauge string may last longer. But string size is critical to playability, and thinner strings play better. [0011] Higher gauge strings or thinner diameter strings play better in part because they are more effective at imparting spin to a ball, such as a tennis ball, because thin strings cut deeply into the felt cover of a tennis ball, gripping it to impart the spin necessary for player control. Thicker strings do not penetrate the ball cover as deeply. Thinner strings also deflect more for a given impact. This increase in deflection reduces the shock that the player feels and returns more energy to the ball giving the player more power. Furthermore, thick strings increase wind resistance to racquet swing to a surprising degree. [0012] While the dynamic modulus of an individual string is indicative of its playability, racquets are actually strung with a crossed pattern of strings called a string bed. The strings extending from top to bottom of the racquet head are called the main strings, while those crossing the racquet head are called the cross strings. When the strings move within the string bed, the main strings slide and rub against the cross strings. The resultant friction between strings causes energy loss. This energy loss may also affect playability. SUMMARY [0013] The present invention includes improved strings for racquets and methods for making the same. [0014] The string of the present invention may employ a conventional string, such as a string having a center core comprising gut or synthetic material such as nylon, and a polymer cover impregnated with adhesive. The adhesive may be low temperature adhesive. The polymer cover covers the string along at least a portion of the length of the string. As the term "adhesive" is used herein it is intended to mean a material that will form a bond between the polymer cover and the base string. As the term "low temperature adhesive" is used herein it is intended to designate any adhesive that will either form a bond when processed at a temperature less than about 300.degree. C. More preferably, the low temperature adhesive comprises any adhesive that will either cure or form a durable bond at less than about 275, 250, 225, 200, 175, 150, 125, 100, 75, 50, or 25.degree. C. [0015] In one aspect, the invention provides a string, and a composite comprising a polymeric membrane having at least some porosity and an adhesive disposed within the at least some porosity, the composite covering at least a portion of the string. [0016] In another aspect, the polymer cover has at least some porosity. In another aspect of the invention, at least some of the porosity is filled with an adhesive by applying the adhesive to one or more surfaces of the polymer cover. In an alternative embodiment of the invention, at least some of the porosity is filled, for example, by imbibing or impregnating the porous polymer cover, with adhesive. [0017] In a still further aspect, the adhesive is applied to at least one surface of the polymer cover and at least some of the porosity is filled with an adhesive. [0018] In an alternative embodiment of the invention, the adhesive is a low temperature adhesive. [0019] In yet another aspect of the invention, a suitable low temperature adhesive can be applied to at least one surface of the polymer cover and the low temperature adhesive may form a durable bond between the string and cover material. In this aspect, the adhesive may be continuous or discontinuous. [0020] In order to provide the highest compatibility with a wide variety of underlying string materials, it may be desirable to provide an adhesive material that can be applied, and if necessary cured, at or near room temperature, such as through use of pressure sensitive adhesives, radiation curable adhesives, or the like. Thus, in another aspect of the invention an adhesive is provided that is cured through exposure to ultraviolet light (hereinafter "UV" light) or an electron beam (hereinafter "EB"). [0021] In yet another aspect of the invention, the polymer cover comprises ePTFE. [0022] In another aspect, the composite has a thickness of less than about 5% of the racquet string diameter. Preferably, the composite has a thickness of less than about 3% of the racquet string diameter. Most preferably, the composite has a thickness of less than about 1% of the racquet string diameter. Continue reading about Strings for racquets... Full patent description for Strings for racquets Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Strings for racquets 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. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Strings for racquets or other areas of interest. ### Previous Patent Application: Tennis racket having a primarily rectangular shape Next Patent Application: Table-tennis bat(pen-holding type) Industry Class: Games using tangible projectile ### FreshPatents.com Support Thank you for viewing the Strings for racquets patent info. 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