Patent Application
20200109524
The present invention relates to artificial turf, and particularly to turf infill comprised of polymer particles, granules or pellets. Artificial turf is typically used for sports and athletics surfaces, but may also be employed in other applications to simulate lawns and grass surfaces, such as playground turf, synthetic laws, landscapes, private installations, parks, commercial surfaces, municipal grounds, testing grounds and the like.
Artificial turf generally includes synthetic fibers or filaments that are tufted into a woven material with an adhesive backing that holds the fibers or filaments to simulate blades of grass as an upright synthetic grass layer. Natural and/or synthetic particulates, such as granules and pelletized matter, including for example one or more of rubbers, vinyls, sand, and a variety of polymers, are typically dispersed within the upright synthetic grass layer as infill, often referred to as turf infill. The type of infill provides performance characteristics to the artificial turf, such as shock absorbency, ball rebound, friction, ball rolling, weather resistance, and other traits specific to a particular synthetic turf construction.
Conventional synthetic infill materials are generally uniform in shape and size, such as synthetic infill of rubber, polymers, and similar materials that have the same spherical and cylindrical shape and size. U.S. Pat. Pub. No. US 2017/0233956 (the '956 Publication), incorporated herein by reference in its entirety, describes that infill pellets comprised of polyvinyl chloride (PVC) may be extruded and cut and provided in a number of different shapes (such stars, polygons, hearts, and triangles) to improve interlocking traction and performance characteristics of the artificial turf. Like other conventional infill materials, the '956 application contemplates only uniform regular shapes and sizes of infill.
Embodiments of the present invention provide improvements beyond traditional infill that has regular shapes with generally uniform sizes for infill particulate material. The present invention provides for non-uniform infill pellets, granules or particulates comprised of PVC in an installation of artificial and synthetic turfs.
In embodiments of the invention PVC infill pellets and granules that are dispersed as infill in artificial turf installation have a variety of multiple sizes and irregular shapes, such as non-symmetrical shapes, to impart improved performance characteristics to the artificial turf. In specific embodiments, such shapes include seed-like and droplet-like shapes of different sizes. In further embodiments, such shapes include generally elliptic, ovate and obovate shapes. In still further embodiments such shapes include generally biconvex and asymmetrically oval shapes (such as pumpkin seed-type and sunflower seed-type shapes with generally pointed ends). In still further embodiments such shapes include generally teardrop/lachrymiform shapes. It various embodiments any combinations of the foregoing different shapes can be provided with one another in various sizes as PVC infill granules, pellets and particulates in an artificial turf installation.
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In embodiments of the invention, the use of irregular, non-uniform and various-sized PVC particulates 5 imparts improved performance characteristics to artificial turf as compared to uniform particulates disclosed in the '956 application. In the Tables I-III test results subsequently described, uniform PVC-based infill particulates used in artificial turf according to the '956 application are referenced as “20s/50TPE_PriorArt”, non-uniform PVC infill particulates that have not been subjected to wear simulation used in artificial turf according to an embodiment of the present invention are referenced as “70/30 Pre-Wear”, and non-uniform PVC infill particulates used in artificial turf that have been subjected wear simulation machine with a Lisport-brand wear machine are referenced as “70/30 Post-Wear”.
To compare performance characteristics, each 20s/50TPE_PriorArt, 70/30 Pre-Wear and 70/30 Post-Wear particulates were provided in artificial turf and subjected to the following described tests. The 20s/50TPE_PriorArt particulates were provided in an artificial turf test system of 20 lbs sand/50 lbs thermoplastic elastomer (TPE) over 2½″ Turf. The 70/30 Pre-Wear particulates were provided in an artificial turf test system of 4.97 lbs per sq. ft. PVC, 2.13 lbs per sq. ft. Sand, 2.25″ slit film turf and no pad. The 70/30 Post-Wear particulates were provided in an artificial turf test system of 4.97 lbs per sq. ft. PVC, 2.13 lbs per sq. ft. Sand, 2.25″ slit film turf and no pad and subjected to 20,000 cycles of a Lisport wear machine.
The following laboratory tests were conducted on each of the particulates/artificial turf system samples. Technical guidelines of the Synthetic Turf Council (STC) are incorporated herein by reference. EN references are to European Standards which are also incorporated herein by reference.
Force Reduction (%)—(STC Advanced Artificial Athlete Protocol test) Measures the impact absorption provided by a surface to a player under foot as they run. A lower value describes a surface that is harder underfoot. The results are compared to the STC performance guidelines of 57% to 68% for a Community Field and 62% to 68% for a Stadium Field.
Vertical Deformation (mm)—(STC Advanced Artificial Athlete Protocol test) Measures the amount a surface compresses as an athlete runs across it. This value is often related to speed of play and surface stability. The results are compared to the STC performance guidelines of 6 mm to 11 mm for a Community Field and 6 mm to 10 mm for Stadium Field. Vertical Deformation typically will reduce over time as a field receives use.
Energy Restitution (%)—(STC Advanced Artificial Athlete Protocol test) Measures the energy returned as a percentage of the energy of applied. This can be thought of as the springiness of the surface. This value relates to the feel underfoot as well as the speed of play. Although this measurement is not a part of the official standard, it is a useful measure. The recommended range is 20% to 50%.
ASTM F355A Gmax/HIC Impact Attenuation (Flat Faced Drop Missile) (G's (Units of Gravity))—The ASTM F355A Impact Hardness is the official device/method for assessing the hardness of synthetic turf athletic fields. It is used to gauge impact attenuation based on a predetermined head/body impact. This is a 20 Ib “missile” with a tri-axial accelerometer dropped from a height of 24 in. The STC recommends that the Gmax values be less than 165.
EN 1177—HIC Impact Attenuation (Hemispherical Drop Missile) (Critical Fall Height (m))—The EN 1177—Impact attenuating play surfacing determination of critical fall height method is similar to the method commonly used for assessing playground surfacing in the United States. Internationally it is the primary method for both synthetic turf and playground surfacing. This device calculates the Head Injury Criteria (HIC). This is used to gauge the probability of head injury potential resulting from a surface impact. This device is a hemispherical 10 lb “missile” with a tri-axial accelerometer. The hemisphere is dropped from (4) different heights to determine the height at which the HIC would be 1000. This height is referred to as the critical fall height. It is recommended that the critical fall height values be greater than 1.3 meters.
Rotational Resistance—EN15301 (Newton Meters (n))—Rotational Resistance measures the interaction between the cleat sole and the surface relating to the ability of a player to change direction. Higher values can relate to a surface that resists the rotation of a foot when a player is changing direction and increase the potential for lower extremity injury. STC guidelines recommend the results being 30 n to 45 n.
Vertical Ball Rebound—EN 12235 (Meters (m))—Measures how high the ball bounces when falling vertically onto a synthetic turf field. A ball is released from 2 m and the height of its rebound from the surface is calculated. The ball is first calibrated on a level concrete surface to 1.35 m. STC recommends from 0.60 to 0.85 m.
Following Tables I-III provide the test results, conducted indoors, for each of the compared particulates in the respective artificial turf system:
The results of tests set forth in Tables I-III indicate that embodiments of the invention using PVC infill pellets and granules having a variety of multiple sizes and irregular shapes, such as non-symmetrical shapes, that are dispersed as infill in artificial turf installations impart improved performance characteristics to the artificial turf over convention artificial turf installations.
Various embodiments of the invention have been described. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the exemplary embodiments as set forth in the claims. This specification is to be regarded in an illustrative rather than a restrictive sense.
This application claims the benefit of priority of U.S. provisional application No. 62/742,539 filed Oct. 8, 2018, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62742539 | Oct 2018 | US |
