US20200109524A1

US20200109524A1 - Non-uniform artificial turf infill

Info

Publication number: US20200109524A1
Application number: US16/517,231
Authority: US
Inventors: Eric STOFFER
Original assignee: Westlake Compounds LLC
Current assignee: Westlake Compounds LLC
Priority date: 2018-10-08
Filing date: 2019-07-19
Publication date: 2020-04-09
Also published as: EP3864201A4; CA3115265A1; EP3864201A1; TW202021767A; CN113366160A; JP2022508654A; WO2020076767A1; MX2021003979A; AR116720A1

Abstract

An artificial turf simulating grass including a layer of dispersed non-uniform, polyvinyl chloride-based particulates having non-symmetrical shapes and different sizes.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

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.

BACKGROUND OF THE INVENTION

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.

SUMMARY OF THE INVENTION

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.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph of PVC infill pellets having different irregular shapes and different sizes in an embodiment of the invention.

FIG. 2 is a front view of a multi-hole extrusion die having different size holes for producing PVC infill pellets as shown in FIG. 1 in an embodiment of the present invention.

FIG. 3 is a front partial and magnified view of a multi-hole extrusion die of FIG. 2 in an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As shown in one embodiment in FIG. 1, PVC-based particulates 5 for artificial turf infill include a variety of non-uniform shapes and sizes. Generally, the particulates are irregular, such as non-symmetrical shapes that resemble seeds and/or liquid droplets. PVC-based particulates 5 preferable for use in embodiments of the invention include such PVC granules and pellets having compositions as described in the '956 Publication, which is incorporated herein by reference. Further, the PVC-based particulates 5 may be manufactured in accordance with conventional extrusion, pelletizing and molding methods. In embodiments of the invention, PVC granules and pellets may be manufactured in accordance with methods described and/or referenced in the '956 Publication.
In one embodiment, an extrusion die 20 as shown in FIGS. 2 and 3 may be used to produce PVC particulates 5 having multiple shapes and sizes in accordance with the invention. It will be appreciated by those skilled in the relevant art of extruding, pelletizing and molding of PVC compositions that the manufacturing parameters, such as run rate, temperature settings, and the like, for optimally producing PVC pellets, granules and particulates as in the present invention will depend on a number of factors such as particular machine being used, the particular environment for manufacturing, the precise composition of PVC-based material, and similar variables. Arriving at desirable results as part of the manufacturing process for PVC-based infill shaped and sized in accordance with the invention will therefore be well within the scope of a person skilled in the relevant art and are not considered critical to the present invention.
In one embodiment shown in FIGS. 2 and 3, the extrusion die 20 includes numerous rings of different sized holes, such as a ring of first holes 30, a ring of second holes 32, a ring of third holes 34 and a ring of fourth holes 36. The holes are of different sizes so that a variety of non-uniform irregularly shaped and various-sized PVC particulates 5 may be produced. It will be appreciated that configurations for holes, number of holes, shapes of holes, distance between holes and alignment of holes (whether rings, grids or other patterns) may be varied from the depicted embodiment while still supporting the production of irregular, non-uniform and various-sized PVC particulates 5 in other embodiments of the invention.
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:

TABLE I

		20s/	70/30	70/30
TEST	UNITS	50TPE_PriorArt	Pre-Wear	Post-Wear

Force Reduction	%	66	59	57
Vertical Def	mm	9	8	7.9
Energy Restit	%	23	26	26
355A “Flat” Gmax	G	108	133	137
355A “Flat” HIC		269	374	401
Critical Fall Height	m	1.2	1	1
Rotational	n		30	32	30
Resistance
Ball Rebound	m	0.9	0.92	0.70

TABLE II

					Relative
			70/30 Pre-	Absolute	Diff./	% Difference
TEST	UNITS	20 s/50TPE_PriorArt	Wear	Difference	Comment	(Decimal)

Force Reduction	%	66	59	Increase	Decrease	0.106
				7%	over 10%
Vertical Def	mm	9	8	Decrease	Decrease	0.111
				1 mm	over 10%
Energy Restit	%	23	26	Increase	Increase	0.130
				3%	about 13%
355A “Flat”	G	108	133	Increase	Increase	0.231
Gmax				25	about 23%
355A “Flat” HIC		269	374	Increase	Increase	0.390
				105	about 40%
Critical Fall	m	1.2	1	Decrease	Decrease	0.167
Height				0.2 m	over 15%
Rotational	n		30	32	Increase	Increase	0.067
Resistance				2 n	over 5%
Ball Rebound	m	0.9	0.92	Increase	Increase	0.022
				0.02 m	about 2%

TABLE III

					Relative
		70/30 Pre-	70/30 Post-	Absolute	Diff./	% Difference
TEST	UNITS	Wear	Wear	Difference	Comment	(Decimal)

Force Reduction	%	59	57	Decrease	Decrease	0.15254
				2%	of 15%
Vertical Def	mm	8	7.9	Decrease	Decrease	0.13750
				0.1 mm	over 10%
Energy Restit	%	26	26	None	None	0.000
355A “Flat”	G	133	137	Increase	Increase	0.03008
Gmax				4	3%
355A“Flat”HIC		374	401	Increase	Increase	0.07219
				27	7%
Critical Fall	m	1	1	None	None	0.000
Height
Rotational	n
	32	30	Decrease	Decrease	0.06250
Resistance				2 n	about 6%
Ball Rebound	m	0.92	0.79	Decrease	Decrease	0.14130
				0.13 m	about 14%

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.

Claims

What is claimed is:

1. An artificial turf comprising synthetic filaments or fibers simulating grass adhered to a backing and an infill having a layer dispersed as a layer of non-uniform, polyvinyl chloride-based particulates between the filaments or fibers, wherein the particulates include non-symmetrical shapes and different sizes.

2. The artificial turf of claim 1, wherein the particulates are at least one of pellets and granules.

3. The artificial turf of claim 2, wherein the particulates include at least three different sizes.

4. The artificial turf of claim 3, wherein at least some of the particulates include an elliptic shape.

5. The artificial turf of any claim 3, wherein at least some of the particulates include an ovate shape.

6. The artificial turf of claim 3, wherein at least some of the particulates include an obovate shape.

7. The artificial turf of claim 3, wherein at least some of the particulates include a biconvex shape.

8. The artificial turf of claim 3, wherein at least some of the particulates include an asymmetrically oval shape.

9. The artificial turf of claim 3, wherein at least some of the particulates include a lachrymiform shape.

10. The artificial turf of claim 3, wherein the particulates include a plurality of different shapes selected from the group consisting of an elliptic shape, ovate shape, obovate shape, biconvex shape, asymmetrically oval shape, and lachrymiform shape.

11. The artificial turf of claim 2, wherein at least some of the particulates include an elliptic shape.

12. The artificial turf of claim 2, wherein at least some of the particulates include an ovate shape.

13. The artificial turf of claim 2, wherein at least some of the particulates include an obovate shape.

14. The artificial turf of claim 2, wherein at least some of the particulates include a biconvex shape.

15. The artificial turf of claim 2, wherein at least some of the particulates include an asymmetrically oval shape.

16. The artificial turf of claim 2, wherein at least some of the particulates include a lachrymiform shape.

17. The artificial turf of claim 2, wherein the particulates include a plurality of different shapes selected from the group consisting of an elliptic shape, ovate shape, obovate shape, biconvex shape, asymmetrically oval shape, and lachrymiform shape.

18. The artificial turf of claim 1, wherein the particulates include a plurality of different shapes selected from the group consisting of an elliptic shape, ovate shape, obovate shape, biconvex shape, asymmetrically oval shape, and lachrymiform shape.

19. The artificial turf of claims 18, further comprising a layer including sand underlying the layer of polyvinyl chloride-based particulates.

20. The artificial turf of claim 1, further comprising a layer including sand underlying the layer of polyvinyl chloride-based particulates.