ARTIFICIAL TURF WITH ANTI-SLIP AGENT RESERVOIR

Abstract

An artificial turf fiber comprising a polymer material and an anti-slip agent disposed within the polymer, characterized in that the anti-slip agent has an effective rate of migration in the polymer material and is provided in the polymer material in an effective amount to provide effective reduction of the fiber friction coefficient on the surface of the fiber for at least one year, preferably for at least 2 years, more preferably for at least 5 years, and most preferably for at least 10 years.

Claims

1. An artificial turf fiber comprising a polymer material and an anti-slip agent incorporated/contained in the polymer, characterized in that the anti-slip agent has an effective rate of migration in the polymer material and is provided in the polymer material in an effective amount to provide effective reduction of the fiber friction coefficient on the surface of the fiber for at least one year, preferably for at least 2 years, more preferably for at least 5 years, and most preferably for at least 10 years.

2. The artificial turf fiber of claim 1, wherein the polymer material is selected from the group consisting of polyolefin homopolymers, polyolefin random copolymers, preferably polyethylene including low density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and/or high-density polyethylene (HDPE) and mixtures thereof.

3. The artificial turf fiber of claim 1, wherein the polymer material is a mixture of LDPE and LLDPE, or a mixture of LLDPE and HDPE, wherein preferably the amount of LLDPE in the polymer material mixture is greater than the amount of the LDPE or the amount of HDPE.

4. The artificial turf fiber of claim 1, wherein the polymer material is a mixture of LDPE, and LLDPE, wherein the LLDPE is preferably from 10 to 70 wt % of the polymer material, more preferably from 15 to 50% wt %, and more preferably from to 45% of the total amount of LDPE and LLDPE, wherein preferably the amount of LLDPE in the polymer material mixture is greater than the amount of the LDPE.

5. The artificial turf fiber of claim 1, wherein the polymer material is a mixture of HDPE and LLDPE, wherein the HDPE has a density of 0.952 to 0.957 g/cm.sup.3 and is in an amount of 5.0 to 18 wt %, preferably 12 to 17 wt % of the total amount of HDPE and LLDPE.

6. The artificial turf fiber of claim 1, wherein the anti-slip agent is selected from the group consisting of fatty acid amides, and stearates.

7. The artificial turf fiber of claim 1, wherein the anti-slip agent is used in an amount of from 0.05 to 1.0 wt %, preferably in an amount of from 0.1 to 0.7 wt %, and more preferably from 0.2 to 0.6 wt % based on the total weight of the fiber.

8. The artificial turf fiber of claim 1, wherein the anti-slip agent is erucic acid amide.

9. The artificial turf fiber of claim 1, further comprising reflective particles and or reflective pigments for preventing overheating of the fiber.

10. The artificial turf fiber of claim 1, wherein the fiber is texturized with at least 30% of the part of the fiber length which extends above the infill material having at least one of curl, or wave shape for enhanced softness and coverage.

11. An artificial turf comprising a plurality of the artificial turf fibers of claim 1 securely attached to a backing material, and wherein the plurality of artificial turf fibers form closed loops extending above a top surface of the backing.

12. The artificial turf of claim 1, wherein the fibers are texturized fibers, and wherein the density of the fibers is at least 60%, more preferentially at least 70% of the area covered by the artificial turf.

13. The artificial turf of claim 1, wherein the backing includes a biocide agent which is a zinc-based antimicrobial agent or a metal coordination complex with pyrithione, preferably pyrithione zinc.

14. The use of the artificial turf of claim 1 in a hockey field, wherein watering of the hockey field is reduced substantially or becomes totally needless.

15. A hockey field playing surface comprising the artificial turf of claim 1, wherein watering of the hockey field is reduced substantially or becomes totally needless and is substantially free of microbial infestation for the useful life of the artificial turf.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In the following, embodiments of the invention are explained in greater detail, by way of example only, making reference to the drawings in which:

[0060] FIG. 1 shows a flowchart which illustrates an example of a method of manufacturing artificial turf;

[0061] FIG. 2a shows a diagram which illustrates a cross-section of a polymer mixture;

[0062] FIG. 2b shows a further example of a polymer mixture;

[0063] FIG. 3 shows a further example of a polymer mixture;

[0064] FIG. 4 illustrates the extrusion of the polymer mixture into a monofilament;

[0065] FIG. 5 shows the tufting of an artificial turf fiber;

[0066] FIG. 6 illustrates first and second parts of the fiber; and

[0067] FIG. 7 shows the first parts and portions of second parts of the fibers embedded in the turf backing.

DETAILED DESCRIPTION OF THE INVENTION

[0068] The present invention provides an artificial turf fiber comprising a polymer material and an anti-slip agent incorporated/contained in the polymer material in an amount adequate to last for at a least one year of slow migration from the interior to the surface of the fiber. The fiber polymer material and the anti-slip agent are selected to allow slow diffusion of the anti-slip agent towards the surface of the artificial turf fiber, where they accumulate and replace the lost anti-slip agent due to normal wear and abrasion of the fiber. The anti-slip agent is added in the fiber in an effective amount designed to last reducing the friction coefficient of the fibers preferably for a period of at least 5 years, more preferably at least 10 years, and most preferably at least 15 years.

[0069] Although we do not wish to be bound by theory, key factors which are believed to control the diffusion of the anti-slip agent to the surface of the fiber include for the anti-slip agent, the type of the anti-slip agent, the size of the anti-slip agent, and the hydrophilicity of the anti-slip agent, while for the polymer material include the type, and density of the polymer material. Through extensive research and consideration of the above factors, the polymer material for the fiber, the anti-slip agent, and preferably the reflective agent and their relative amounts were selected.

[0070] In a specific embodiment the EEA is used in an amount of 0.5 wt % based on the total weight of the turf fiber. The turf fiber may be made of a mixture of 10 wt % LDPE and 90 wt % LLDPE of the holistic polymer weight. In another embodiment the EEA is used in an amount of 1.0 wt % based on the total weight of a turf fiber made of the mixture of LDPE and LLDPE. In yet another embodiment the EEA is used in an amount of 1.5 wt % based on the total weight of the mixture of LDPE and LLDPE. In yet another embodiment the EEA is used in an amount of 1.0 wt % based on the total weight of a turf fiber made of a mixture of 15 wt % HDPE (density of 0.955 g/cm.sup.3) and 85 wt % LLDPE (density of 0.920 g/cm.sup.3).

[0071] Preferably, the fiber also includes a reflective agent such as reflective particles, and/or reflective pigments for preventing overheating of the fiber.

[0072] The Artificial Turf

[0073] An example of a method for manufacturing the artificial turf comprises incorporating the artificial turf fiber into a carrier, and adding a viscous thermoset resin reaction mixture onto a back side of the carrier to form a thermoset resin backing. Various additives may be added in the thermoset reaction mixture including, for example, a biocide agent having antimicrobial, antibacterial and antifungal properties. Once the thermoset resin reaction mixture is placed on the back side of the carrier, hardening of the thermoset reaction mixture is performed to form a solid thermoset resin backing with a portion of the turf fiber which protrudes out of the back side of the carrier being securely embedded inside the solid mass of the thermoset resin backing. The thermoset resin may be any suitable resin. Preferably, the thermoset resin may be a polyurethane resin. In an embodiment, the polyurethane is the reaction product of first and second polyols with an isocyanate, wherein the first polyol is polyether polyol and/or polyester polyol having at least two (“2”) hydroxyl groups per molecule, wherein the second polyol is polybutadiene diol, wherein the isocyanate comprises isocyanate monomers, isocyanate polymers or isocyanate prepolymers or a mixture thereof, and wherein the isocyanate monomers, the isocyanate polymers and the isocyanate prepolymers have two or more isocyanate groups per molecule. The polybutadiene diol may be used in an amount of 0.5-10% by weight of a combination of the first polyol and the isocyanate, and may have a number average molecular weight in the range of 500 to 6000 g/mol, more preferably in the range of 1.500 to 4.500 g/mol. The polyurethane reaction mixture may further comprise a surfactant and other additives and fillers. The hardening of the fluid polyurethane mass can be performed, for example, by heating the polyurethane reaction mixture on the back side of the carrier to a temperature of 70-140° C.

[0074] The making of the turf fiber includes forming a polymer material mixture inside a first container, preparing an additive mixture including the anti-slip agent, and preferably also the reflective agent and optionally various other additives for the fiber in a separate or a plurality of separate smaller containers, mixing the polymer material mixture with the additive mixture to form an extrusion feed mixture that is fed to an extruder to form a monofilament (in actuality, typically a plurality of monofilaments). The monofilament exiting from the extruder is quenched, for example, by passing it through a water bath, and upon exiting from the water bath the monofilament is reheated, for example, in an air oven. The reheated monofilament is oriented by stretching the reheated monofilament to form an oriented monofilament which is used as the artificial turf fiber either individually or after being combined with other monofilaments. For example, through a well-known process multiple monofilaments may be combined to form an artificial turf fiber which can be rolled into a yarn. The anti-slip agent and preferably also the reflective agent may be added in the additive mixture inside the smaller container. However, this is just an example, and it should be understood that the anti-slip agent can be added also in the larger container directly with the polymer material mixture or as a separate feed to the extruder feed. The polymer mixture may further comprise a nucleating agent for crystallizing the polymer within and at the surface of the monofilament anti UV agents, anti-flame agents and other optional additives. The artificial turf fiber is typically a bundle of at least 5 monofilaments.

[0075] The reflective agent (e.g., reflective particles and/or a reflective pigments) are used for counteracting the overheating of the turf. These reflective particles and reflective pigment have the advantage of cooling the artificial turf field, thereby compensating the missing cooling effect of the water when water is absent. Also, applicant has found that the type and amount of the reflective agent may affect the effective rate of migration of the anti-slip agent in the polymer material matrix of the fiber.

[0076] The polymer material mixture and the additive mixture including the anti-slip agent, preferably also the reflective agent may be blended using a blender or mixing device prior to add them to the extruder.

[0077] The term “tufting” as used herein refers to a method of incorporating a fiber into an existing carrier. Short U-shaped loops of fibers are introduced through the carrier from one side so that their ends point outside of the carrier in the other direction. Usually, the tuft yarns form a regular array of “dots” on the other side. On the one side of the carrier where the U-shaped loops are located, the tuft fibers may be tied for security, although they need not be. The ends of the tuft yarns can then optionally be frayed or otherwise processed, so that they will subsequently create a dense layer of fibers protruding from the carrier.

[0078] The term “weaving” as used herein is a method of incorporating an artificial turf fiber (which can be a monofilament or a bundle of monofilaments) into an existing carrier, whereby the artificial turf fiber and the fiber(s) that built the carrier are interlaced. The interlaced fibers and the mesh form a fabric like or cloth like structure. When an artificial tuft fiber is incorporated by weaving, the fiber interlaces a series of mesh fibers at least three times. Thus, when a fiber is incorporated by weaving rather than tufting, a higher fraction of the artificial turf fiber is interlaced in the carrier material. This may increase the resistance to wear and tear of the artificial turf.

[0079] According to embodiments, incorporating the artificial turf fiber into the carrier comprises: tufting the artificial turf fiber into the carrier. According to alternative embodiments, incorporating the artificial turf fiber into the carrier comprises weaving the artificial turf fiber into the carrier.

[0080] Referring now to FIG. 1 a flowchart is provided which illustrates an example of a method of manufacturing artificial turf. First in step 102 a polymer mixture such as the mixture 200 depicted in FIG. 2a is created. The polymer mixture 200 comprises at least one polymer 204, an anti-slip agent 202, and preferably a reflective agent 208 (e.g., reflective particles 208) for providing continuous reduction of the friction coefficient of the fibers for at least one year, preferably at least 5 years, more preferably at least 10 years, and most preferably at least 15 years.

[0081] The polymer mixture may be created by putting all of the components that make it up together at once. For instance, the at least one polymer 204, the anti-slip agent 202, the reflective agent 208 and the optional additives 206 could be all added together at the same time. The polymer mixture could be thoroughly mixed for instance by using a mixer device. The desired distribution of the components can be achieved by using the proper rate or amount of mixing. The generated mixture could be forwarded to a one-screw feed or a two-screw feed for the extrusion.

[0082] Additional optional substances may be added. Also, a reflective pigment 302 may be used in addition or instead of the reflective particles as shown in FIG. 3.

[0083] In step 104, the polymer mixture is extruded into a monofilament 506 as illustrated in FIG. 4. Next in step 106 the monofilament is quenched or rapidly cooled down. In step 108 the monofilament is reheated and in step 110 the reheated monofilament is stretched to form a monofilament that can directly be used as an artificial turf fiber or that can be bundled with additional monofilaments into an artificial turf fiber. Additional steps may also be performed on the monofilament to form the artificial turf fiber. For instance, the monofilament may be spun or woven into a yarn with desired properties. Next in step 112 the artificial turf fiber is incorporated into an artificial turf backing. The incorporation comprises a step 114 of arranging a plurality of the artificial turf fibers on a carrier 704 (see FIGS. 6 and 7). The carrier may be a textile plane, for example. The artificial turf fibers are arranged such that first parts 706 of the monofilaments are exposed to a bottom side of the carrier and second parts 702 of said monofilaments are exposed to a top side of the carrier. The arranging could be accomplished by tufting or weaving the artificial turf fiber into the carrier, but other methods of arranging the fibers within the carrier are also possible.

[0084] Then in step 116 a resin reaction fluid mixture is added on the bottom side of the carrier such that at least the first parts become embedded in the fluid. Finally, in step 118, the fluid mixture is caused to solidify into a film. The film surrounds and thereby mechanically fixes at least the first parts 706 (and optionally also some portions 804 of the second parts 702) of the monofilaments in the film. The film, i.e., the solidified fluid, constitutes the backing 802.

[0085] FIG. 2a shows a cross section of a polymer mixture 200 comprising at least a first polymer 204, preferentially a non-polar polymer such as polyethylene, and an anti-slip agent 202 such as EEA. The polymer mixture may further comprise additives 206 such as a dye for coloring the fiber, a biocide for adding antimicrobial property, a nucleating agent, and the like. The anti-slip agent 202 is added in an adequate amount and should have a slow migration rate within the polymer material matrix of the fiber so that it can last replenishing the surface of the fiber with the anti-slip agent for at least one year, preferably at least 5 years, more preferably at least 10 years and most preferably at least 15 years. In the illustrated example, the at least one polymer is a mixture of LDPE, and LLDPE, wherein the LDPE is 10 wt % and LLDPE is 90 wt % of the total polymer mixture of LDPE and LLDPE. The anti-slip agent 202 is, for example, EEA and is used in an amount of 0.5 wt % based on the total weight of the fiber, i.e., including the polymer, the anti-slip agent, and the additives.

[0086] FIG. 2b shows a polymer mixture 250 comprising all the components of the mixture 200 of FIG. 2a and in addition a reflective agent 208. The reflective agent 208 is, for example, titanium dioxide and is used in an amount of 1.0 wt % based on the total amount of the polyethylene, the EEA, and the optional additives. Said reflective agent 208 prevents overheating of the fiber and thus further reduce the need for frequent watering of the turf. Although, the precise mechanism is not well understood, the presence of the reflective agent (i.e., the reflective pigment and or the reflective particles) in the polymer matrix of the fiber and their respective amounts may affect the migration rate of the anti-slip agent inside the polymer matrix of the fiber. Thus, the amount of the reflective agent in the fiber is controlled for obtaining a migration rate for the anti-slip agent that ensures that the anti-slip agent can last reducing the friction coefficient of the fibers, most preferably, for the useful life of the artificial turf. This is a rather unexpected and surprising synergistic effect between the anti-slip agent and the reflective agent.

[0087] FIG. 3 shows a cross section of a polymer mixture 300 comprising at least a first polymer 204, e.g., the LDPE/LLDPE mixture described above, and the anti-slip agent 302.

[0088] FIG. 4 illustrates the extrusion of the polymer mixture into a monofilament 506. Shown is a schematic simplified cross-sectional view of an amount of the polymer mixture 200. Within the polymer mixture 200 there is dispersed the anti-slip agent 202 (e.g., EEA) in an effective amount and optionally also additional additives 206. Preferably, the additives 206 also include a reflection agent as discussed above. A screw, piston or other device is used to force the polymer mixture 200 through a hole 502 in a plate 504. This causes the polymer mixture 200 to be extruded into a monofilament 506. The monofilament 506 is shown as containing the anti-slip agent 202 and the additives 206 (preferably also including the reflective agent) also.

[0089] FIGS. 5 and 6 show how a plurality of artificial turf fibers can be arranged in a carrier 704, e.g., a textile plane, by means of tufting. Tufting is a type of textile weaving in which an artificial turf fiber 701 (that may be a monofilament 506 or a bundle of multiple monofilaments) is inserted on a carrier 704. After the inserting is done, as depicted in FIG. 5, short U-shaped loops of the fiber point outside of the carrier's surface. Then, one or more blades cut 602 through the loops. As a result of the cutting step, two artificial turf fiber ends per loop and monofilament point out from the carrier and a grass-like artificial turf surface is generated. Thereby, first parts 706 of the monofilaments of the artificial turf fibers having been inserted in the carrier 704 are exposed to a bottom side of the carrier and second parts 702 of said monofilaments are exposed to a top side of the carrier.

[0090] In a preferred embodiment for artificial turf for hockey fields the cutting step 602 is omitted and the artificial turf is made with the U-shaped loops forming the top surface of the turf.

[0091] FIG. 7 depicts the carrier 704 with the inserted filaments having been embedded within (FIG. 7a) or next to a surface of (FIG. 7b) an artificial turf backing 802. This is performed by adding a fluid in step 116 (see FIG. 1) on the carrier 704 such that the first parts 706 of the monofilaments become embedded in the fluid (FIG. 7a) or the first parts and some portions 804 of the second parts 702 of the monofilaments (FIG. 7b) become embedded in the fluid. The carrier may be a textile mesh or may comprise perforations that allow the fluid 802.2 at the bottom side of the carrier to flow to the upper side of the carrier and vice versa, thereby creating a portion 802.1 of the backing on top of the carrier. Thus, the carrier and parts of the fibers inserted in the carrier may become embedded in the backing 802. The artificial turf fibers 701 are shown as extending a distance 806 above the carrier 704. The distance 806 is essentially the height of the pile of the artificial turf fibers 701.

[0092] For example, the fluid may be a styrene-butadiene suspension that solidifies into a latex backing or, preferably, may be a mixture of polyols and polyisocyanates that solidifies into a polyurethane backing or any other kind of fluid that is capable of solidifying after a defined time period into a solid film. The fluid solidifies into a film 802, e.g., by a drying process or by a chemical reaction resulting in a solidification of the fluid. Such a chemical reaction can be, for example, a polymerization. The film surrounds and thereby mechanically fixes at least the first parts of the monofilaments of the arranged artificial turf fibers. The solid film acts as the artificial turf backing. In some examples, additional coating layers may be added on the bottom of the artificial turf backing.

Examples

[0093] In Example 1 0.5 wt % of EEA anti-slip agent was added in a polymer mix of 60 wt % LDPE and 40 wt % LLDPE. The LDPE had a density of 0.905 g/cm.sup.3 and the LLDPE had a density of 0.918 g/cm.sup.3 and was a copolymer of polyethylene and butene. No reflective agent was added. Additives such as color pigments, flame retardants were also added and the mixture was extruded in a conventional extrusion equipment to form an artificial turf fiber which was then added in an artificial turf structure having a polyurethane backing as described above with reference to the figures.

[0094] In examples 2-5 the same process was repeated with the key parameters shown in Table 1. In examples, 2-5 the fiber was texturized to have a top at least about 30% of its length which extends above the backing and any infill material in the shape of a wave. Compared to example 1 which comprised straight fibers, the turf made with the texturized fibers of examples 2 and 5 showed significant improvement in its overall smoothness and coverage.

[0095] The same process was repeated in total 5 times with the key compounds added each time shown in Table 1 below.

TABLE-US-00001 TABLE 1 Ex. 1 EX. 2 Ex. 3 Ex. 4 Ex. 5 Polymer 1 LLDPE LLDPE HDPE LLDPE LLDPE Polymer 1 density 0.918 0.918 0.94 0.918 0.918 Polymer 1 WT % 60 20 100 70 30 Polymer 2 LLDPE LLDPE — HDPE HDPE Polymer 2 density 0.920 0.920 — 0.94 0.94 Polymer 2 Wt % 40 80 — 30 70 anti-slip agent EEA EEA EEA EEA EEA Anti-slip agent 0.5 0.5 0.5 0.5 0.5 amount wt % Reflective Agent NO TITANIUM TITANIUM Mixed metal Mixed metal DIOXIDE DIOXIDE oxide oxide Reflective agent 1.0 1.0 1.0 1.0 amount wt % Fiber texturization NO Yes, type Yes, type Yes, type Yes, type waves 30% waves 30% waves 30% waves 30%

[0096] The above formed fibers in examples 1-5 were tested and compared with the comparative examples 6-10.

[0097] Significant improvement in the overall smoothness and tribological characteristics was observed between the examples 1-5 and their corresponding comparative examples 6-10. A significant reduction in the friction coefficient was observed in the examples 1-5 compared to their corresponding comparative examples 6-10 of at least 10%. In addition, it has been found, rather unexpectedly, that the above formed fibers with the EEA prevent excessive slippage in rain/wet conditions while providing a sufficiently smooth surface in dry/sunny conditions. Thus, not only the need for watering the artificial turf is eliminated but also excessive slippage is prevented even in rain/wet conditions. Surprisingly slippage is not or not substantially increased with respect to dry conditions when the artificial turf becomes wet such as due to rainy weather.

[0098] In comparative examples 6-10 the same fiber compositions as in examples 1-5 were used except that no anti-slip agent was used in the polymer mixtures.

[0099] Although the invention has been described in reference to specific embodiments, it should be understood that the invention is not limited to these examples only and that many variations of these embodiments may be readily envisioned by the skilled person after having read the present disclosure which do not fall outside the scope of the invention as defined by the claims.

LIST OF REFERENCE NUMERALS

[0100] 102-118 process steps [0101] 200 put in the mixture [0102] 202 anti-slip agent [0103] 204 polymer [0104] 206 further additive substances [0105] 208 reflective particles or reflective pigment [0106] 300 polymer mixture [0107] 502 hole in a plate [0108] 504 plate [0109] 506 monofilament of artificial turf fiber [0110] 602 cutting artificial turf fibers during tufting [0111] 701 artificial turf fiber [0112] 702 second parts of fibers [0113] 704 carrier [0114] 706 first parts of fibers first parts of fiber [0115] 800 artificial turf (cross-section) [0116] 802 backing made from solidified fluid [0117] 804 portions of the second parts of the fibers embedded in the fluid [0118] 806 distance <carrier-surface−upper ends of fibers>