Patent Application
20070032320
The present disclosure relates, in various exemplary embodiments, to improving playability of sports balls, and in particular, the grippability of such balls when wet.
The ability to grip, or maintain contact with a sports ball is a significant factor. This is particularly so for sports balls that are used outdoors where external agents such as rain, snow, dirt, or mud can interfere with gripping the ball.
Efforts to improve grippability of sports balls have included the use of anti-slip coatings applied to the outer surface of the ball, the use of particular surface patterns such as pebbling, and the incorporation of cushioning or padding within the ball to facilitate gripping. Although satisfactory, a need remains for another strategy by which to improve grippability of a sports ball.
In accordance with one aspect of the present exemplary embodiment, an inflatable sports ball comprising a carcass and an outer cover layer disposed on the carcass is provided. The outer layer includes a thermoplastic elastomer having at least three properties selected from the group consisting of (i) a Shore A hardness of from about 2A to about 95A, (ii) a specific gravity of from about 0.80 to about 1.2, (iii) an ultimate tensile strength of from about 180 to about 2200 psi, (iv) a tear strength of from about 30 to about 320 psi, (v) a 100% tensile modulus strength from about 5 to about 1000 psi, and (vi) an ultimate elongation of from about 200% to about 1300%.
In another aspect of the present exemplary embodiment, an inflatable sports ball is provided comprising an outer cover layer having an outermost layer including a styrenic block copolymer thermoplastic elastomer. The thermoplastic elastomer of the outermost layer has at least three properties selected from the group consisting of (i) Shore A hardness from about 3A to about 90A, (ii) a specific gravity of from about 0.86 to about 1.18, (iii) an ultimate tensile strength of from about 200 to about 1330 psi, (iv) a tear strength of from about 40 to about 300 psi, (v) a 100% tensile modulus strength of from about 9 to about 990 psi, and (vi) an ultimate elongation of from about 210% to about 1290%.
In a further aspect, the exemplary embodiment provides an inflatable sports ball comprising an outer cover layer having an outermost layer including a vulcanizate thermoplastic elastomer having at least three properties selected from the group consisting of (i) Shore A hardness of from about 3A to about 75A, (ii) a specific gravity of from about 0.86 to about 1.11, (iii) an ultimate tensile strength of from about 250 to about 930 psi, (iv) a tear strength of from about 40 to about 180 psi, (v) a 100% tensile modulus strength of from about 9 to about 430 psi, and (vi) an ultimate elongation of from about 210% to about 1290%.
In yet another aspect, the present exemplary embodiment provides an inflatable sports ball comprising an outer cover having an outmost layer including a polyurethane thermoplastic elastomer having at least three properties selected from the group consisting of (i) Shore A hardness of from about 3A to about 75A, (ii) a specific gravity of from about 0.86 to about 1.19, (iii) an ultimate tensile strength of from about 250 to about 2000 psi, (iv) a tear strength of from about 40 to about 270 psi, (v) a 100% tensile modulus strength of from about 9 to about 430 psi, and (vi) an ultimate elongation of from about 210% to about 1290%.
These and other non-limiting characteristics of the embodiments of the present disclosure are more particularly discussed below.
The following is a brief description of the drawings which are presented for the purposes of illustrating the exemplary embodiments disclosed herein and not for the purposes of limiting the same.
The present disclosure provides a technique for improving not only the grip, feel, and performance of a sports ball, but also the “wet play characteristics” of such a ball. “Wet play characteristics” as used herein refers to the grippability characteristics of the ball under wet or humid conditions. Wet play characteristics are also important when the sports ball contacts perspiration, such as from players' hands.
The present discovery utilizes a unique class of thermoplastic elastomers having particular properties for an outer cover layer of a sports ball. The class of elastomers surprisingly impart excellent wet play characteristics to sports balls having cover layers or outer coatings formed from such thermoplastic elastomers.
Thermoplastic elastomers are generally lower modulus, flexible materials that can be stretched repeatedly to at least twice their original length at room temperature and are able to return to their approximate original length when stress is released.
The preferred thermoplastic elastomers for use in the preferred embodiment sports balls described herein can be categorized into two generic classes, block copolymers (styrenics, copolyesters, polyurethanes and polyamides) or thermoplastic/elastomer blends and alloys (thermoplastic polyolefins and thermoplastic vulcanizates).
Certain traditional thermoplastic elastomer types are known as two-phase systems. Essentially, a hard thermoplastic phase is coupled mechanically or chemically with a soft elastomer phase, resulting in a thermoplastic elastomer that has the combined properties of the two phases.
In addition to these thermoplastic elastomers, several other classes exist which may be suitable for incorporation in the preferred embodiment sports balls. The other classes of thermoplastic elastomers include, but are not limited to, metallocene-catalyzed polyolefin plastomers and elastomers, and reactor-made thermoplastic polyolefin elastomers.
The polyolefin plastomers (POP's) and polyolefin elastomers (POE's) are essentially very low molecular weight, linear low density polyethylenes (VLMW-LLDPE).
The preferred embodiment thermoplastic elastomers suitable for use as outer cover components for sports balls exhibit at least three, preferably four, more preferably five, and most preferably all six of the following characteristics: (i) Shore A hardness of from about 2A to about 95A, (ii) a specific gravity of from about 0.80 to about 1.2, (iii) an ultimate tensile strength (or tensile at break) of from about 180 to about 2200 psi, (iv) a tear strength of from about 30 to about 320 psi, (v) a 100% tensile modulus strength of from about 5 to about 1000 psi, and (vi) an ultimate elongation of from about 200% to about 1300%.
More specifically, the preferred embodiment sports balls utilize one or more styrenic block copolymer thermoplastic elastomers that exhibit at least three, preferably four, more preferably five, and most preferably six of the following characteristics: (i) Shore A hardness of from about 3A to about 90A, (ii) a specific gravity of from about 0.86 to about 1.18, (iii) an ultimate tensile strength of from about 200 to about 1300 psi, (iv) a tear strength of from about 40 to about 300 psi, (v) a 100% tensile modulus strength of from about 9 to about 990 psi, and (vi) an ultimate elongation of from about 210 to about 1290%.
The preferred embodiment sports balls can also utilize one or more thermoplastic vulcanizates that exhibit at least three, preferably four, more preferably five, and most preferably six of the following characteristics: (i) Shore A hardness of from about 3A to about 75A, (ii) a specific gravity of from about 0.86 to about 1.11, (iii) an ultimate tensile strength of from about 250 to about 930 psi, (iv) a tear strength of from about 40 to about 180 psi, (v) a 100% tensile modulus strength of from about 9 to about 430 psi, and (vi) an ultimate elongation of from about 210% to about 1290%.
The preferred embodiment sports balls can also utilize one or more thermoplastic polyurethanes that exhibit at least three, preferably four, more preferably five, and most preferably six of the following characteristics: (i) Shore A hardness of from about 3A to about 75A, (ii) a specific gravity of from about 0.86 to about 1.19, (iii) an ultimate tensile strength of from about 250 to about 2000 psi, (iv) a tear strength of from about 40 to about 270 psi, (v) a 100% tensile modulus strength of from about 9 to about 430 psi, and (vi) an ultimate elongation of from about 210% to about 1290%.
Shore A hardness is generally measured as follows. The most common instrument for measuring rubber or elastomer hardness is called a Shore durometer. The Shore A durometer has a blunt indenter and a moderate spring force. A spring is used to push a metal indenter into the surface of the material, measuring how far it penetrates. The instrument measures the depth penetration from zero to 0.100 inches. A zero reading on the scale means the indenter is at the maximum depth and a reading of 100 indicates that no penetration was detected. Shore durometers come in a variety of hardness ranges and degrees of automation.
Most materials will resist initial indenture but will yield further over time due to creep or relaxation. Durometer readings can either be taken instantaneously or after a specific delay time, which typically range between 5 and 10 seconds An instantaneous reading will typically give a higher (or harder) reading than the delayed readings. Delayed readings are more representative of not only the hardness of the material but the resiliency. A weak, less elastomeric material will creep more than a higher strength, more resilient material.
Accurate testing procedures are needed to ensure valid data. To obtain an accurate reading it is desirable to have a flat part surface as well as a part thick enough so the indenter is not affected by the support surface. The usual required thickness is 0.200 inches but hard compounds that experience less deformation can be accurately measured at lower thicknesses.
The “ultimate tensile strength” is a measurement also called “ultimate tensile” or “tensile at break.” In this test, a piece of elastomer is stretched until it breaks. The amount of force needed to break the material is then measured. Units are typically given in pounds per square inch (psi) or megapascals (MPa). Elastomers with high ultimate tensile properties will be more difficult to break by stretching than an elastomer with lower values in this test.
The “tear strength” test is performed the same way as the tensile at break test except the test bar is notched on one side to provide a propagation point. The material is stretched and the amount of force at which the test bar tears completely is reported. Units are typically given in psi or kN/m. This value describes how well the elastomer resists tearing.
In the “100% tensile modulus” test, the elastomer is stretched and the resistance to the stretching is measured over a range of elongation points. This is often reported as tensile at various percentages of the original length of elastomer, such as 50%, 100% and 300%. An elastomer might have a strong resistance to stretching initially but become weaker as it elongates (called “necking”).
“Ultimate elongation” does not measure how hard or easy the material is to stretch, but simply how far it will stretch before it breaks. This is reported in percentage of original length. Some soft elastomers will stretch to greater than 1000% of their original length before breaking. A soft elastomeric thermoplastic elastomer will typically have a much higher value than a hard rigid material.
Specific gravity refers to the density of the material after curing.
The preferred embodiment sports balls utilize particular thermoplastic elastomers having a particular combination of characteristics. Specifically, the preferred thermoplastic elastomers can include one or more of styrenic block copolymers, thermoplastic vulcanizates, and thermoplastic polyurethanes exhibiting various combinations of the noted characteristics.
Non-limiting examples of commercially available thermoplastic elastomers are those from GLS Corporation of McHenry, Ill.
Tables 1-5, set forth below list representative commercially available thermoplastic elastomers from GLS that are suitable for use in the preferred sports balls described herein. GLS supplies various styrenic block copolymers under the designation Kraton™. GLS also supplies styrenic block copolymers under the designation Dynaflex™. GLS also supplies styrenic block copolymers, thermoplastic vulcanizates, and thermoplastic polyurethanes under the designation Versaflex™. GLS supplies thermoplastic vulcanizates under the designation Versalloy™. And, GLS supplies thermoplastic polyurethanes under the designation Versollan™.
The preferred thermoplastic elastomers described herein can be utilized in nearly any sports ball where increased grippability or frictional characteristics of an outer surface are desired. Preferably, the thermoplastic elastomers are utilized in inflatable sports balls. Non-limiting examples of such inflatable sports balls include basketballs, footballs, soccer balls, and volley balls.
A preferred embodiment football is assembled in the following manner. The football cover panels containing the thermoplastic elastomer along their outer surface are cut in a generally oval shape and are coupled together at their edges by stitches and positioned over a bladder or carcass. Four essentially similarly shaped, generally oval shaped panels are normally utilized with the panels in abutment along their edges. Their edges are in-turned and stitched. The liner is formed from a plurality of components having the same shape and size as the cover panels. The liner components are stitched to the cover panels along their peripheries. The edges of the panels and liner components are then stitched together along their edges forming seams and creating a football-shaped shell for receiving a pre-molded bladder. The stitching is made while the panels and liner are inside out. A central extent along one seam is not stitched to thereby form an opening through which the bladder may be inserted during fabrication. A tongue and two patches are then sewn to the panels and liner in a conventional manner, with the patches spanning the unstitched opening. The tongue is sewn to a cover panel and liner along a short extent offset slightly from the patches. The panels and liner components are then turned inside out and the bladder is inserted. The opening is then closed by lacing with the tongue having an enlarged portion located between the bladder and the patches. The structure of the lacing and closure are further described in U.S. Pat. No. 5,098,097, the contents of which are incorporated herein by reference. A basketball, volleyball, softball, or other game ball of the disclosure can be assembled in a conventional manner.
Pebbling or other surface features may be produced by techniques known in the art such as by embossing. Alternately, or in addition, one or more cushioning layers can also be incorporated under or beneath the covers described herein.
The exemplary embodiment has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
