Patent Publication Number: US-10323361-B1

Title: Synthetic turf system made with antistatic yarns and method of making

Description:
PRIORITY CLAIM AND RELATED APPLICATIONS STATEMENT 
     Priority under 35 U.S.C. § 119(e) is claimed to U.S. provisional application entitled “SYNTHETIC TURF SYSTEM MADE WITH ANTISTATIC YARNS AND METHOD OF MAKING,” filed on Jun. 27, 2011 and assigned U.S. provisional application Ser. No. 61/501,722; and to U.S. provisional application entitled “SYNTHETIC TURF SYSTEM MADE WITH ANTI STATIC YARNS AND METHOD OF MAKING,” filed on Jul. 12, 2011 and assigned U.S. provisional application Ser. No. 61/506,951. The entire contents of this provisional patent application are hereby incorporated by reference. 
    
    
     BACKGROUND 
     Synthetic turf sometimes has an undesirable tendency to build up static charge in itself as well as the persons who walk or play on it. This may cause static electrical shocks to the body. Surprisingly, static charge build up is known to occur even in high humidity environments such as found in regions like Florida during the summer months. 
     Static charge is particularly problematic on playgrounds where playground equipment is often constructed of insulating materials that also have a propensity to build up static charge. Synthetic turf can act as insulator so that even when a static charge is created on a piece of playground equipment such as a slide it is not dissipated as a person walks across the turf until a conductive ground, such as a metal pole, is touched. 
     Conventional ways to solve the static problem in synthetic turf have not worked. For instance Brunswick Corporation U.S. Pat. No. 4,356,220 describes an artificial grass product comprising: a pile fabric with yarn comprised of a plurality of fibers made of a polymeric material. This patent teaches that additives, such as antistatic agents, can be dispersed in the fibers. 
     Meanwhile, U.S. Pat. No. 4,672,005 issued in the name of Dyer describes a process for improving the hygroscopic and soil release properties of a polymer substrate in which the substrate is contacted with a suitable aqueous mixture containing a water soluble vinyl monomer and a hydrophobic vinyl monomer. This patent alleges that antistatic properties with this process are improved. 
     Antistatic polymer additives have been used to solve this problem but have been found to be ineffective because they may cause a deterioration of fiber extrusion performance and fiber physical properties. In addition, static dissipation of the turf is inadequate to render a noticeable benefit. 
     Antistatic topical additives such as glyceryl monostearate or octadecylbis (2-hydroxyethyl) amine, sold under the tradenames Armostat™ 1000 beads, and Armostat™ by Akzo Nobel Polymer Chemicals B.V. of the Netherlands which may be applied to fiber during manufacture have also been used. But these have also been found to be ineffective as they are not substantive solutions for outdoor environments, especially in the presence of rain. 
     Other ways of solving this problem have been the topical application of antistatic chemicals, such as Staticide™ sold by Amstat Industries of Glenview, Ill., directly to the synthetic turf. While effective in some situations, this solution is limited since topically applied chemicals are not substantive solutions for outdoor environments, especially in the presence of rain. 
     Meanwhile, the problem of static shock has been addressed in carpet by incorporating an electrically conductive fiber into pile yarn used to make the carpet. U.S. Pat. No. 3,971,202 issued in the name of Windley for instance describes cobulking electrically conductive sheath-core filaments such as those disclosed in U.S. Pat. No. 3,803,453 issued in the name of Hull with nonconductive filaments to form a crimped, bulky carpet yarn. This carpet yarn may dissipate static electricity charges which are annoying to people who walk on nonconductive carpets when humidity is low. In this instance the, conductive filaments are tangled with the carpet tufts so that they extend the full length of the carpet tuft. 
     U.S. Pat. No. 4,612,150 issued in the name of De Howitt describes introducing spin-oriented electrically conductive bicomponent filaments into a quench chimney wherein nonconductive filaments are melt spun and cooled, combining the conductive and nonconductive filaments at a puller roll, drawing and cobulking the combined yarn and then winding up the yarn. 
     These conventional approaches are problematic with synthetic turf since it is not practically possible to cobulk electrically conductive filaments with nonconductive filaments. This is because turf fibers are typically monofilament or slit tape. Because synthetic turf fibers are large, it is not possible to combine the antistatic yarn with synthetic turf fiber in such a way that the two yarns are intimately entangled as is characteristically done in carpet. 
     Another problem in the art which is unique to synthetic turf is the use of infill. Synthetic turf incorporates the use of infill. This is a particulate material that is incorporated onto the turf face between tufts. The purpose of infill is to hold tufts upright and to provide a cushion on which to play. These materials are typically all insulators and thus exacerbate static electricity as understood by one of ordinary skill in the art. 
     SUMMARY 
     A synthetic turf system and method includes turf tufted from monofilament fibers of a thermoplastic polymer where about 1 in about 32 tuft rows comprise at least one antistat filament per tuft. Each antistat filament has a nonconductive polymeric component coextensive with a component of an electrically conductive material dispersed in a polymeric matrix. One or more of the antistat filaments substantially reduces static electrical discharge within the turf. The thermoplastic polymer for each fiber may comprise at least one of nylon, polyethylene, polypropylene, and polyester. Each tuft of the tufted turf may be twisted and each tuft may be slit to form multiple ends. The turf system may comprise stitched turf. Each antistat filament may comprise a carbon sheath and a ratio of the antistat filament per number of tuft rows may comprise at least one of 1:2, 1:4, 1:8, and 1:16. 
     Specifically, according to one exemplary embodiment, an improved durable antistatic synthetic turf includes combining an antistatic fiber such as with a monofilament polyethylene or a slit tape polyethylene by twisting the two yarns together into combined yarns. The twisted yarn is then tufted so as to place at least one antistat filament combination in about each 32 rows of tufted rows. This means that for every 31 tufts of standard yarn (no antistat filament) there is one tuft having standard yarn combined with an antistat filament. Similarly, in other exemplary embodiments, at least one antistat filament combination may be provided in about every second row, or every fourth row, or every eighth row, or every sixteenth row, as set forth in Appendix A. 
     This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the Figures, like reference numerals refer to like parts throughout the various views unless otherwise indicated. For reference numerals with letter character designations such as “100A” or “100B”, the letter character designations may differentiate two like parts or elements present in the same figure. Letter character designations for reference numerals may be omitted when it is intended that a reference numeral to encompass all parts having the same reference numeral in all figures. 
         FIG. 1  is side view of one exemplary embodiment of a turf system in which yarn is in a twisted form when it is tufted through a fabric backing; 
         FIG. 2  is a side view of an exemplary embodiment of a sports turf system which includes a base that establishes the contour of a playing surface; 
         FIG. 3  illustrates a turf system with a black and white digital photograph of another exemplary embodiment having a second set of crimped, thatch-like fiber yarn which may be smaller than the grass-like fiber yarn of the prior exemplary embodiments and that may be combined with the grass-like fiber yarn; 
         FIGS. 4A and 4B  illustrate a perspective view and a close-up view, respectively, of a single antistat filament placed in every stitch row in an exemplary turf system corresponding to  FIG. 1 ; 
         FIG. 5  illustrates a package (tube) of textured yarn that is used to make the turf thatch exemplary embodiment of  FIGS. 4A-4B ; 
         FIG. 6 , illustrates an exemplary package of antistatic yarn according to one exemplary embodiment; 
         FIG. 7  illustrates a tufting needle according to one exemplary embodiment; 
         FIG. 8  illustrates a tufting process that includes a tufting needle used to push the yarn bundle having the antistatic yarn and a companion yarn through a backing material; 
         FIG. 9A  illustrates exemplary needle set ups for a tufting machine that include an antistatic fiber in every needle (1/1); 
         FIG. 9B  illustrates an antistatic fiber in every second needle (1/2) according to one exemplary embodiment; 
         FIG. 9C  illustrates an antistatic fiber in every fourth needle (1/4) according to one exemplary embodiment; 
         FIG. 9D  illustrates an antistatic fiber in every eighth needle (1/8) according to one exemplary embodiment; 
         FIG. 9E  illustrates an antistatic fiber in every sixteenth needle (1/16) according to one exemplary embodiment; 
         FIG. 10  illustrates a flow chart of exemplary steps for an antistatic yarn/grass yarn combining process for forming grass; 
         FIG. 11  illustrates a flow chart of exemplary steps for an antistatic yarn/thatch yarn combining process for forming thatch; and 
         FIG. 12  illustrates a flow chart of exemplary steps for a tufting process for a turf system. 
     
    
    
     DETAILED DESCRIPTION 
     The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as exclusive, preferred or advantageous over other aspects. 
     Referring now to the figures,  FIG. 1  is side view of one exemplary embodiment of a turf system  10 A in which yarn  90  is in a twisted form when it is tufted through a fabric backing  86 . Each tuft of yarn  90  may form two bundles  29  of grass blade ends  92  containing an antistat filament  33  in which the bundles  29  are surrounded by an infill layer  82  The antistat filament  33  has been illustrated with a parallel line hatching. The antistat filament  33  may comprise conductive materials, such as, but not limited to, a core made from carbon. 
     Specifically, the antistat filament  33  may comprise a non-conductive outer sheath or layer that encapsulates a central core, which may also be made from a conductive material, such as carbon. The antistat filament  33  has a nonconductive polymeric component coextensive with a component of carbon dispersed in a polymeric matrix. It has been discovered that the antistat filament  33  may substantially reduce and in some situations, eliminate, static electrical discharges within the turf system  10 . 
     In  FIG. 1 , each tuft or twisted yarn  90  is shown with two ends having an antistat filament  33 . One of ordinary skill in the art recognizes that these two antistat filaments  33  illustrated for each tuft or twisted yarn  90  is the same, single antistat filament  33 . That is, only one antistat filament  33  is used in each yarn  90  that is illustrated in  FIG. 1 . The single antistat filament  33  was not shown present along the entire length of each twisted yarn  90  for brevity. Further details about the antistat filament  33  and infill layer  82  will be described below in connection with other exemplary embodiments of the turf system  10 . 
       FIG. 1  also illustrates the tufting machine stitching direction with arrows which run parallel to the length dimension of the fabric backing  86  ( FIG. 1  shows the length and height dimensions of one exemplary embodiment of the turf system  10 A). As illustrated in  FIG. 1 , the individual monofilaments, fibrillated or slit filaments with grass blade ends  92  are twisted together near the stitched end and come apart at the top. The preferred turf system  10 A includes a twisted fiber of yarn  90 . 
       FIG. 1  illustrates an improved durable antistatic synthetic turf system  10  which includes combining an antistat filament  33  such as with a monofilament polyethylene or a slit tape polyethylene by twisting the two structures together by placing about 0.25 to about 2.0 twists per inch (TPI) of twist into the combined structure. 
     The twisted yarn is then tufted so as to place at least one antistat filament combination (tuft with standard yarn and antistat filament  33 ) in about every 32 rows of tufted rows. This means that for every 31 tufts of standard yarn (no antistat filament  33 ) there is one tuft having standard yarn combined with an antistat filament  33 . Similarly, in other exemplary embodiments, at least one antistat filament combination may be provided in about every second row, or every fourth row, or every eighth row, or every sixteenth row, as set forth in the test data section listed below. Meanwhile,  FIG. 1  (as well as  FIG. 2 ) illustrates an antistat filament  33  present in every tuft row (1:1 ratio). 
     The turf system  10 A may have many types of applications. It may be used for both commercial and residential landscapes. The turf system  10 A may also be used for an athletic field and for playgrounds. 
     Referring now to  FIG. 2 , a sports turf system  10 B is illustrated which includes a base  84  that establishes the contour of a playing surface. The base  84  may comprise compacted crushed stone, concrete or asphalt pavement or compacted clay and gravel rolled into ordinary dirt. Although not shown, a slight slope or grade in the base  84  is preferable to facilitate surface water drainage. 
     The synthetic surface of the system  10 B, as shown in  FIG. 2 , has a thin, flexible, fabric backing  86  with parallel rows of vertical grass blade ends  92  projecting upwardly from the fabric backing  86 . A relatively thick layer  82  of infilled particulate material is provided on the backing  86  supporting the grass blade ends  92  in a relatively upright position on the fabric backing  86 . 
     The grass-like yarns  90  with ends  92  may comprise a monofilament fiber or slit tape fiber. Strands of yarn  90  may comprise from about 3.0 to about 50.0 or more individual filaments. The yarn  90  may be combined with an antistat filament  33  which will be described in further detail below. Similar to  FIG. 1 , the antistat filament  33  has been illustrated with a parallel line hatching. As will be described below, the antistat filament  33  may comprise a non-conductive outer sheath or layer that encapsulates a conductive central core, made from carbon. 
     Each yarn  90  may be made from, e.g., about 1/16 inch (which is about 0.16 cm) wide polyethylene monofilament and having a thickness of about five mils. This yarn  90  may be slit and twisted to form a plurality of thin filaments or grass blade ends  92 , is tufted or stitched through the fabric backing  86 . The exemplary embodiment illustrated in  FIG. 2  does not show the yarn  90  to be twisted. 
     The yarn  90  may comprise a thermoplastic polymer, such as a polyethylene monofilament described above. In other exemplary embodiments, the thermoplastic polymer may comprise at least one of nylon, polypropylene, and polyester. 
     If the yarn  90  is fibrillated, the thin filaments forming the grass blade ends  92  remain connected at certain points so that the yarn  90  when stretched apart creates a honeycombed mesh. Strands of yarn  90  can comprise from about three to about fifty or more individual filaments with the grass blade ends  92 . The individual grass blade ends  92  may stack one on top of the other. 
     Typical tufts or stitches include about four to about twelve yarns  90  per inch (2.5 cm) that may be used with conventional carpet tufting or stitching machines. The height of the yarn  90  with ends  92  (i.e., grass blades) can vary but are typically between about 1.0 inch to about 2⅝ inches (about 2.5 to about 6.7 cm) high. The machines typically produce rows of tufts that are commonly about ⅜ inch to about ¾ inch (about 0.93 to about 1.87 cm) apart. 
     Tufting, stitching. knitting or weaving different types of yarns into a standard carpet by threading different yarns into a plurality of laterally aligned needles is understood by one of ordinary skill in the art. The underside of the fabric backing  86  can be coated with a resinous coating  88  that secures the tufts in place. The coating  88  usually increases the dimensional stability of the fabric backing  86  as well as the moisture resistance of the fabric backing  86 . 
     A preferred manner of coating the fabric backing  86  is to contact the back of the fabric backing  86  with a solution of polyurethane polymer and then subject the fabric backing  86  to a heat treatment to cure the polyurethane polymer coating. Conventional polyvinyl chloride, polyvinyl acetate or natural or synthetic rubber latex coatings may also be employed. 
     In sports applications, after laying and adhering the synthetic turf  80  to the base  84 , turf installers typically infill or infuse a layer  82  of compacted material having a mixture of resilient particles and fine sand between the synthetic grass blades. Turf installers have been known to use a variety of different resilient materials, such as, but not limited to: (i) granulated cork; (ii) rubber particles including natural rubber or synthetic rubber; (iii) beads of synthetic polymers such as vinyl chloride, vinyl ethers, vinyl acetate, acrylates and methacrylates, polyvinylidene chloride, urethanes, polyamids and polyesters; (iv) synthetic polymer foam particles; (v) vinyl foams such as polyvinyl chloride foams, polyvinyl ether foams, foamed polystryene, foamed polyurethanes and foamed polyesters; and (vi) foamed natural rubber. For example, rubber such as Ethylene Propylene Diene Monomer (EPDM) and ground tire rubber may be used, while plastics such as like Thermoplastic Elastomers (TPE) may also be used for the infill layer  82 . 
     Turf installers also at times add fine sand to the infill to fill the interstices between the resilient particles to thereby form a more densely compacted infill layer  82 . In sports applications, the sand is generally smaller in size than 30 U.S. screen mesh size and is preferably between about 40 and 200 U.S. screen mesh size. Fine sand also feels less abrasive to players when they contact the turf  80 . 
     In typical sports applications, the turf installer provides an infill layer  82  from about fifty percent of the height of the grass blade ends  92  to substantially even with the top of the grass blade ends  92 . In sports applications, turf installers typically prefer a projection of a synthetic blade between ⅛ inch and ⅜ inch (0.31 and 0.93 cm) above the infill layer. Turf installers maintain an infill layer  82  substantially to the top of the grass blade ends  92  to prevent a playing surface from having a noticeable grain. Normally, the grass blade ends  92  have a characteristic grain (i.e., a tendency to lay in a given direction related to the direction in which the material passed through the production machinery). The infill layer  82  counteracts this tendency and prevents the playing surface from having an easily noticeable grain. 
     A relatively high infill layer  82  having a top surface  94  that includes resilient materials also absorbs much of the shock of an object impacting the playing surface and improves the footing of a player running or walking across the surface, particularly when making cuts or sharp turns. The non-abrasive character of the infill  82  and the controlled and diminished synthetic blade height projecting above the infill  82  make a playing surface much less likely to produce rug burns or abrasions when players contact the surface. 
     The infill layer  82  preferably is a usually a material that characteristically or inherently retards plant and animal life, absorbs water and enables it to drain through to the fabric backing  86  and the secondary backing  88  and provides a firm and stable foundation for the yarns  90 . The infill layer  82  includes any material having these characteristics including, but not limited to: rock, sand, concrete, plastic, fiberglass, rubber, ceramic material, cork, or any combination or derivative thereof. 
     The infill layer  82  is may preferably comprise crushed rock or sand, and most preferably, it may comprise washed sand. In certain instances, e.g., in the rainy Northwest, the infill layer includes being ¼ inch (0.62 cm) minus crushed rock (i.e., ¼ inch (0.62 cm)) average diameter rock down to rock particles) to enhance drainage. 
     As noted above, in sport applications, the sand is preferably fine sand between about 40 and about 200 U.S. screen mesh size to feel less abrasive to players who contact the turf. The size of the sand in the infill  82  preferably includes bigger sand particles that vary between about 4 and about 70 U.S. screen mesh size. The sand is preferably in a range of sizes, which facilitates better compaction. 
     The preferred turf  80  includes a compacted infill layer  82  of variable sand particles. A four-ton double drum roller may be used to make one or more passes over the preferred turf  80 . The length L, which is the average distance between the tips of the grass blade ends  92  and a top surface  94  of the infill layer  82 , is preferably about ⅛ to about 5.00 inches (about 0.31 to about 12.50 cm) given that the contemplated variable turf height of the grass blade ends  92 , k, above the primary backing  86  includes being about ½ inch to about 6.00 inches (about 1.25 to about 15 cm). 
     The turf having the grass blade ends  92  may project between about 0.5 inch to about 2.0 inches above the infill surface  94 , wherein the free ends of the grass blade ends  92  may shield the sand infill  82  from the weather. Thus, in an application wherein the grass blade ends  92  are preferably about 2.0 inches (about 5.0 cm) high, the infill layer  82  is preferably about 1.75 inches (about 4.44 cm) high, leaving a distance I of preferably about 0.25 inch (about 0.63 cm). 
     To look like grass, the polyethylene yarn is pigmented green. While synthetic turf has made use of a green pigment, other applications of polyethylene employ different colors. 
       FIG. 2  further illustrates one stitch row for the turf system  10 B. Every single, 2nd, 4th, 8th, 16th or 32nd stitch row (or any row in-between these rows or about the 32nd row) may contain an antistat filament  33  as shown with parallel black line shading. The thickness of the antistat filament  33  has been exaggerated in order to show its placement within each tuft that forms a set of two bundles  29  of grass blade ends  92 . Generally, the antistat filament  33  may have the same thickness or less thickness relative to the other monofilaments forming each yarn  90  that is tufted. 
     In the exemplary embodiment of  FIG. 2 , one end of the antistat filament  33  is shown being combined with a plurality of monofilaments (typically about 4 to about 12) to form a single tuft. Two bundles  29  of grass blade ends  92  are formed by one tuft of yarn  90 . Approximately, one antistat filament  33  will be in one yarn  90  that is tufted or every two grass blade bundles  29 . Like  FIG. 1 , in  FIG. 2 , each yarn  90  that is tufted is shown with two ends having an antistat filament  33 . One of ordinary skill in the art recognizes that these two antistat filaments  33  illustrated for each yarn  90  is the same, single antistat filament  33 . That is, only one antistat filament  33  is used in each yarn  90  that is tufted that is illustrated in  FIG. 2 . The single antistat filament  33  was not shown present along the entire length of yarn  90  that is tufted for brevity. 
     The turf system  10 B, such as about a twelve or about fifteen feet (about 3.6 or about 4.5 m) roll of the preferred flexible turf  80 , includes a fabric backing  86  preferably of double woven polypropylene and a flexible coating  88 , which is preferably polyurethane. The thickness of the fabric backing  86  is preferably provided by the manufacturer. The thickness of the flexible coating  88  is preferably between about 10 and about 20 mils. 
     The preferred turf  80  includes a plurality of yarns  90 , which are tufted or stitched into the primary backing  86 . According to this exemplary embodiment of  FIG. 2 , the yarns  90  are not twisted like those as illustrated in  FIG. 1 . 
     The secondary backing  88 , applied after tufting or stitching, covers some or all of the stitch depending on the thickness of the secondary backing  88 . The preferred turf includes about 19 tufts or stitches per about every 3.75 inches (about 7.5 cm). 
     The yarns  90  are preferably polyethylene, between about 3500 and about 11000 denier, and about 40 to about 72 ounces per square yard. In other exemplary embodiments, the height of the grass blade ends  92 , having a dimension k, above the bottom of the secondary backing  88  preferably is between about 0.50 inch to about 6.00 inches (about 1.25 to about 15.00 cm), and specifically about 1.00 to about 2.50 inches (about 2.54 to about 6.25 cm) and most preferably about 2.00 inches (about 5.0 cm). 
     In other exemplary embodiments, the height of the grass-like strands with ends  92 , having a dimension l, relative to the infill layer  82  preferably is between about 0.25 inch to about 4.00 inches (about 0.60 to about 10.20 cm), and most preferably between about 0.50 inch to about 2.00 inches (about 1.30 to about 5.10 cm). 
     Referring now to  FIG. 3 , this figure is a computer enhanced black and white digital photograph which illustrates a turf system  10 B having a second set of crimped, thatch-like fiber yarn  93 , which may be smaller than the grass blade ends  92  of the prior exemplary embodiments. This thatch-like fiber yarn  93  may be combined with the grass blade ends  92 . 
     The crimped thatch-like fiber yarn  93  after incorporation into the turf system  10 B will retract considerably so as to be below the surface of the vertically oriented grass blade ends  92 . The grass-like fiber yarn with grass blade ends  92  may be monofilament fibers. Strands of yarn forming the thatch-like fiber yarn  93  may comprise from about 3.0 to about 50.0 or more individual filaments. The thatch-like fiber yarn  93  may be combined with an antistat filament  33  as will be described in detail below. 
     In  FIG. 3 , one antistat filament  33  may be present in every other stitch row of the turf system  10 B that has a thatch make-up from thatch-like fiber yarn  93  (which are not grass blade ends  92  alone as illustrated in  FIGS. 1 and 2 ). The antistat filament  33  of the thatch turf system  10 B is presented with without any shading in this black and white digital photograph. Because the antistat filament  33  has been mechanically textured, the antistat filament  33  is separated into individual filaments and combined with the thatch-like fiber yarn  93 . 
     The antistat filament  33  may also be added every single row, or every 2nd, 4th, 8th 16th, or 32nd row (or any row in-between these rows or about the 32nd row) as will be described below. It is further noted that some lead lines for some reference characters, like reference characters  33  and  93  of this figure have been depicted without any shading so that they are more readily visible in the black and white digital photograph illustrating one exemplary embodiment of the turf system  10 B. 
       FIGS. 4A and 4B  illustrate a perspective view and a close-up view, respectively, of a single antistat filament  33  placed in every stitch row in an exemplary turf system  10 A corresponding to  FIG. 1 . The antistat filament  33  is not presented with any shading to set it apart from the ends  92  of the yarn  90 . 
       FIG. 5  illustrates a package (tube)  500  of textured yarn that is used to make the thatch-like fiber yarn  93  exemplary embodiment of  FIGS. 4A-4B . One end of an antistat filament  33  is added to the textured yarn of tube  500  in the texturizing process. The antistat filament  33  is illustrated with the absence of color for clarity purposes. At this stage, the antistat filament  33  will be tangled and separated into antistat filaments  33  as illustrated in  FIGS. 4A-4B . 
     The antistat filament  33  may be entangled with a grass yarn bundle (not illustrated). In that case, the antistat filament  33  usually would NOT be tangled and separated in to individual filaments. 
     Referring now to  FIG. 6 , a package  600  of antistat filament  33  is illustrated. The package  600  may comprise Negastat™ brand of 140 denier antistat filament  33 . Negastat™ brand of antistat filament  33  is sold by W. Barnet &amp; Son LLC, of Arcadia, S.C. The antistat filament  33  may comprise a plurality of sheath core carbon/polyester multifilament fibers. The antistat filament  33  may comprise about 24.0 filaments. 
     The antistat filament  33  may comprise a filament, bi-component yarn having a conductive core, such as carbon, surrounded by a sheath of nonconducting material, like polyester. The linear mass density or denier of the antistat filament  33  may comprise at least one of 35d-f6, 70d-f12, and 140d-f24. 
     The antistat filament  33  may be added to the yarn  90  at twisting or texturing. A bundle of grass monofilament fibers (typically about 4 to about 12 filaments of nylon, polyethylene, polypropylene or polyester) are usually twisted less than about 1 turn per inch (tpi) in order to create a bundle  29  that will more easily feed through a tufting needle  700  (as illustrated in  FIG. 7 ). 
     The antistat filament  33  may be added to a bundle  29  of grass fibers at the point of twisting. Alternatively, the antistat filament  33  may be added to a bundle  29  of thatch fibers (typically about 4 to about 12 filaments of nylon, polyethylene, polypropylene or polyester) that may be textured using an air jet, stuffer box or some other means to impart crimp and fiber entanglement. 
     The yarns  90  may be textured to provide a thatch aesthetic and to cause the fiber to draw down below the surface of the grass monofilament fibers. The antistat filament  33  may also be added to a companion yarn  90  such as a polyester yarn of a similar denier by twisting the two yarns together. This process provides additional strength to the antistat filament  33  so that it can be more easily added into synthetic grass fiber or into synthetic thatch fiber without breaking. 
     This is done since off-the-shelf antistat filaments  33  are usually relatively weak fibers, such as having about 3.3 gms/denier. Usually, the antistat filaments  33  should have a strength of at least about 2.7 gms/denier. In other exemplary embodiments, antistat filaments  33  having at least 3.5 gms/denier have been found to yield favorable results. 
       FIG. 8  illustrates a tufting process  800  that includes a tufting needle  700  used to push the yarn bundle having the antistat filament  33  and companion yarn  90  through a backing  86 . 
       FIG. 9A  illustrates exemplary needle set ups for a tufting machine (not shown) that include an antistat filament  33  in every needle (1/1). Such a needle set up in  FIG. 9A  will yield at least one antistat filament  33  per yarn  90  that is tufted.  FIG. 9B  illustrates an antistat filament  33  in every second needle (1/2) for another exemplary needle set up. Such a needle set up in  FIG. 9B  will yield where about 16 in about 32 tuft rows comprise at least one antistat filament  33  per yarn  90  that is tufted. 
       FIG. 9C  illustrates an antistat filament  33  in every fourth needle (1/4) while  FIG. 9D  illustrates an antistat filament  33  in every eighth needle (1/8) for another exemplary needle set up. Such a needle set up in  FIG. 9C  will yield where about 8 in about 32 tuft rows comprise at least one antistat filament  33  per yarn  90  that is tufted. Such a needle set up in  FIG. 9D  will yield where about 4 in about 32 tuft rows comprise at least one antistat filament  33  per yarn  90  that is tufted. 
       FIG. 9E  illustrates an antistat filament  33  in every sixteenth needle (1/16) for another exemplary needle set up. Such a needle set up in  FIG. 9E  will yield where about 2 in about 32 tuft rows comprise at least one antistat filament  33  per yarn  90 . At a minimum, turf  10  tufted from monofilament fibers of a thermoplastic polymer will usually have about 1 in about 32 tuft rows that comprise at least one antistat filament  33  per yarn  90 , where each antistat filament  33  has a nonconductive polymeric component coextensive with a component of carbon dispersed in a polymeric matrix. 
       FIG. 10  illustrates a flowchart for a method  1000  for combining an antistat filament with turf yarn to form grass according to an exemplary embodiment of the invention. Block  1005  is the first step of method  1000 . 
     In block  1005 , an antistat filament  33  may be provided or supplied. As described previously, the antistat filament  33  may comprise a filament bi-component yarn having a conducting core, such as carbon, surrounded by a sheath of nonconducting material, such as polyester. The linear mass density or denier of the antistat filament  33  may comprise at least one of 35d-f6, 70d-f12, and 140d-f24. As of this writing, one brand of antistat filament  33  is sold under the brand name NEGASTAT™ sold by W. Barnet &amp; Son LLC of Arcadia, S.C. 
     Next, in decision block  1010 , it is determined whether the antistat filament  33  needs to be reinforced in order to increase its strength for a particular grass application. If the inquiry to decision block  1010  is positive, then the “YES” branch is followed to block  1015 . If the inquiry to decision block  1010  is negative, then the “NO” branch is followed to block  1020 . 
     In block  1015 , a reinforcing fiber, such as 150 denier polyester, may be supplied. However, other types of reinforcing fibers such as nylon, polypropylene, cellulose acetate, polyethylene, or polyethylene terephthalate (PET), may be used. 
     Next, in block  1025 , the antistat filament  33  and the reinforcing fiber supplied in block  1015  are twisted together. Next, in block  1030 , as a result of the twisting of block  1025 , a reinforced yarn  90  is formed. 
     Subsequently, in block  1040 , monofilament grass bundles that have between about 4 and about 12 fibers may be supplied. In block  1050 , the monofilament grass bundles may be twisted together with the antistat filament  33 /PET combination produced from block  1030 . After the twisting operation in block  1050 , a grass monofilament bundle with 1 PET/antistat filament  33  has been formed and may be supplied to a tufting creel in block  1060 . 
     Returning back to the negative output to decision block  1010 , in which reinforcement of the antistat filament  33  is not desired, in block  1020 , like block  1040 , monofilament grass bundles that have between about 4 and about 12 fibers may be supplied. Next in block  1035 , the antistat filament  33  and the monofilament grass bundles are twisted together like block  1050 . As a result, in block  1045  a grass monofilament bundle having antistat filament  33  is formed and may be supplied to a tufting creel in block  1060 . 
       FIG. 11  illustrates a flowchart for another method  1100  for combining an antistat filament with turf yarn to form grass according to an exemplary embodiment of the invention. Block  1105  is the first step of method  1100 . 
     In block  1105 , an antistat filament  33  may be provided or supplied. As described previously, the antistat filament  33  may comprise a filament bi-component yarn having a conducting core surrounded by a sheath of nonconducting material, such as polyester. The linear mass density or denier of the antistat filament may comprise at least one of 35d-f6, 70d-f12, and 140d-f24. As of this writing, one brand of antistat filament  33  is sold under the brand name NEGASTAT™ sold by W. Barnet &amp; Son LLC of Arcadia, S.C. 
     Next, in decision block  1110 , it is determined whether the antistat filament  33  needs to be reinforced in order to increase its strength for a particular grass application. If the inquiry to decision block  1110  is positive, then the “YES” branch is followed to block  1115 . If the inquiry to decision block  1110  is negative, then the “NO” branch is followed to block  1120 . 
     In block  1115 , a reinforcing fiber, such as 150 denier polyester, may be supplied. However, other types of reinforcing fibers such as nylon, polypropylene, cellulose acetate, polyethylene, or polyethylene terephthalate (PET) may be used. 
     Next, in block  1125 , the antistat filament  33  and the reinforcing fiber supplied in block  1115  are twisted together. Next, in block  1130 , for as a result of the twisting of block  1025 , a reinforced yarn  90  is formed. 
     Subsequently, in block  1140 , monofilament thatch bundles that have between about 4 and about 12 fibers may be supplied. In block  1150 , the monofilament thatch bundles may be air entangled and/or mechanically crimped with the antistat filament  33 /PET combination produced from block  1130 . After the entangle/crimping operation in block  1150 , a thatch monofilament bundle with 1 PET/antistat filament  33  has been formed and may be supplied to a tufting creel in block  1160 . 
     Returning back to the negative output to decision block  1110 , in which reinforcement of the antistat filament  33  is not desired, in block  1120 , like block  1140 , thatch grass bundles that have between about 4 and about 12 fibers may be supplied. Next in block  1135 , the antistat filament  33  and the thatch grass bundles are air entangled and/or mechanically crimped together like block  1150 . As a result, in block  1145 , a thatch monofilament bundle having antistat filament  33  is formed and may be supplied to a tufting creel in block  1160 . 
       FIG. 12  illustrates a flowchart for a method  1200  for tufting to form the turf systems  10  of  FIGS. 1-4  illustrated above according to an exemplary embodiment of the invention. Block  1205  is the first step of method  1200 . 
     In block  1205 , the yarn used to create the turf systems  10  are hung in a creel. Specifically, depending upon the type of turf system  10  desired, such as the grass system  10 A or thatch system  10 B, then block  1205  may correspond with block  1060  and or  1160  of  FIGS. 11-12 . 
     In block  1210 , a grass monofilament yarn having about 4 to about 12 fibers per bundle without (in absence of) any antistat filament  33  may be supplied. Alternatively, in block  1060 , a grass monofilament yarn that has been combined with an antistat filament  33  having about 4 to about 12 fibers per bundle in addition to an antistat filament  33  may be supplied. This block  1060  corresponds to block  1060  of  FIG. 10 . 
     Alternatively, in block  1215  a thatch monofilament yarn having about 4 to about 12 fibers per bundle without (absence of) any antistat filament  33 . Or alternatively, in block  1160  a thatch monofilament yarn having an antistat filament  33  with about 4 to about 12 thatch yarns in addition to an antistat filament  33  may be supplied on the creel. Block  1160  corresponds to block  1160  of  FIG. 11 . 
     Next, in block  1220 , the yarns supplied on the creels and blocks  1210  or  1215  may be combined in needles such as illustrated in  FIG. 8  and without any antistat filament  33  at about 480 needles for about three-eighths inch gauge at about fifteen feet width. 
     Alternatively, or in parallel to block  1220 , in block  1225 , the yarns supplied on the creels of block  1210 ,  1060 ,  1215 , or  1160  may be combined in needles with an antistat filament  33  at 480, 240, 120, 60, or 30 needles for about three-eighths inch gauge at about fifteen feet width. 
     Next, in block  1230 , the yarns may be tufted into a backing  86  such as illustrated in  FIG. 8  with an antistat filament  33  in every first, second, fourth, eighth, or sixteenth stitch row as illustrated in  FIGS. 9A-9E . Next, in block  1235  the backing  86  may be coated with a coating  88  such as illustrated in  FIG. 2  in order to lock in the fibers into the turf system  10 . The method  1200  then ends. 
     Testing of Turf System  10   
     It has been discovered that conventional approaches for reducing or eliminating static issues such as used for carpet will not work. Notably, laboratory testing confirms such as Test Method 134-2006 Electrostatic Propensity of Carpets Developed in 1969 by American Association of Textile Chemists and Colorists (AATCC) Committee RA32 conducted on turf with incorporated antistat filament  33  shows no benefit versus testing of synthetic turf that has no antistat filament  33 . Other testing such as the AATCC 13-2006 after the turf  10  has been carefully washed to remove topical surfactants applied during the manufacturing process shows similar results. 
     Exemplary Test Results are provided in Appendix A—Test Data. The results provided in Appendix A were greater than those which would have been expected from the prior art to an unobvious extent, and these results are of a significant, practical advantage, as described above and below. The evidence of the test data section listed below establishes that the differences in results are in fact unexpected and unobvious and have both statistical and practical significance. 
     It has been discovered that surprisingly and unexpectedly when antistat filament  33 , such as between about 50.0 to about 200.0 denier, and in some exemplary embodiments of about 140.0 denier, and the antistat filament  33 , comprising a sheath of polyester and a core of carbon, is loosely twisted with nylon, polyethylene, polypropylene, or polyester monofilament fibers and tufted into synthetic turf  10  where about 1 in about 32 tuft rows comprise at least one antistat filament  33  per tuft (as well as turf  10  having antistat filament  33 : tuft ratios of 1:2/1:4/1:8/and 1:16 as set forth in the test data section listed below), such turf  10  significantly and unexpectedly eliminates all static shock developed on a control side which does not have any antistat filaments- 33 . 
     This difference is manifested on turf  10  that is tufted such that about ½ of the width of the turf contains antistat filament  33  and the remaining about ½ of the width of the turf contains no antistat filament  33 . When the turf  10  is placed outdoors in a use environment there is initially no static (or substantially nominal) charge build up on the test or control areas (which do not have any antistat filament  33 ). 
     Over time and exposure to the outdoor environment static can be generated on the control or untreated area by scuffing normal athletic shoes over the surface of the conventional side of the turf. A similar static build up is not realized on the treated turf system  10  having any one of the antistat filament/tuft ratios (B-F listed in the test data section listed below). 
     Surprisingly and unexpectedly, once a static charge is generated on the control side and the test subject walks from the control side to the test side, the static charge does not transfer. In fact, no static shock is realized once the subject touches a metal pole while standing on the test side of the inventive turf system  10  having the antistat filament: tuft row ratios (B-F) listed in the test data section listed below. One of ordinary skill in the art would expect that the inventive turf system  10  with one of the ratios (B-F) may substantially reduce some static discharge. However, the turf system  10  having any one of five antistat filament: tuft row ratios (B-F) substantially eliminates all static discharge developed on the control (conventional) side of the test turf  10 . 
     Certain steps in the processes or process flows described in this specification naturally precede others for the invention to function as described. However, the invention is not limited to the order of the steps described if such order or sequence does not alter the functionality of the invention. That is, it is recognized that some steps may performed before, after, or parallel (substantially simultaneously with) other steps without departing from the scope and spirit of the disclosure. In some instances, certain steps may be omitted or not performed without departing from the invention. Further, words such as “thereafter”, “then”, “next”, etc. are not intended to limit the order of the steps. These words are simply used to guide the reader through the description of the sample methods described herein. 
     Although only a few embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. 
     In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. § 112, sixth paragraph for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function. 
     Test Data Section 
     A turf was constructed on Jan. 4, 2011 such the width of the turf contained the following test constructions: 
     A—No antistat filament 
     B—1 out of every 2 stitch rows contained 1 antistat filament 
     C—1 out of every 4 stitch rows contained 1 antistat filament 
     D—1 out of every 8 stitch rows contained 1 antistat filament 
     E—1 out of every 16 stitch rows contained 1 antistat filament 
     F—1 out of every 32 stitch rows contained 1 antistat filament 
     Boundaries between the samples A-F were carefully marked. 
     Then among the dates of Jan. 17, 2001 (test I), Jan. 19, 2011 (test II), and Feb. 24, 2011 (test III): 
     The single piece of turf containing the six test constructions (A-F) was placed outdoors and a test subject, wearing sneakers made with an elastomeric sole, walked across each sample in a lengthwise direction so as not to contact adjacent samples. After the subject walked across the turf in a careful and controlled manner for 30 seconds a grounded metal pole was touched to discharge any static charge that has developed. Humans can typically sense a static charge of 2 kV and above.
 
In the first test (I), the turf tested immediately after laying it on the ground. The results are summarized in Table 1.
 
In the second test (II), the turf was thoroughly washed so as to remove any oils or surfactants that may be present from the manufacturing process. The results of this test are summarized in Table 1.
 
In the third test (III), the turf was left outdoors, exposed to the elements for 2 months. The results of this test are summarized in Table 1.
 
The test was repeated and the results were confirmed.
 
                     TABLE 1                  TEST DATA                                         Test III After           Test I       2 months of       Antistat   Immediately   Test II After   Exposure       filament   After   Rinsing with   to the       Content   Installation   Water   Elements               None   No Shock   No Shock   Shock       (Conventional                   Art)                   1 antistat   No Shock   No Shock   No Shock       filament in 1 out                   of every 2 stitch                   rows                   1 antistat   No Shock   No Shock   No Shock       filament in 1 out                   of every 4 stitch                   rows                   1 antistat   No Shock   No Shock   No Shock       filament in 1 out                   of every 8 stitch                   rows                   1 antistat   No Shock   No Shock   No Shock       filament in 1 out                   of every 16                   stitch rows                   1 antistat   No Shock   No Shock   No Shock       filament in 1 out                   of every 32                   stitch rows                    
Hypothesis on why test I and test II did not yield any shock for the control section which did not have any antistat filament: The results of test I and II on control section (no-antistat filament) may be attributed to the presence of fiber lubricants which frequently include nonionic, and sometimes, ionic surfactants, both which can act as non-substantive antistat components. The entire turf (including both the anti-stat sections and the single non-antistat section) was rinsed after manufacture The purpose of the water rinse is to remove any surfactants that might be present from manufacturing. That there was no shock after the water rinse for the control section (having no anti-stat filament) is perplexing but is consistent with the laboratory testing that was also conducted. One possible, but weak, explanation is that the water rinse was insufficient to remove the surfactants. This may be the reason in the case of low HLB surfactants. Over time, with outdoor exposure, and after weathering, it is conceivable that these “difficult to remove” surfactants were removed completely.