Artificial turf with anti-slip agent reservoir

Abstract

1. An artificial turf fiber comprising a polymeric material and an anti-slip agent disposed within the polymer, wherein the anti-slip agent has an effective rate of migration within the polymeric material and is provided in the polymeric material in an amount effective to provide an effective reduction in the fiber coefficient of friction at a surface of the fiber for at least one year, preferably at least two years, more preferably at least five years, and most preferably at least ten years.

Description

[Technical field]

[0001] The present invention relates generally to artificial turf fibers, and more particularly to artificial turf fibers having anti-slip agent reservoirs, artificial turf using said artificial turf fibers, and methods of making said artificial turf fibers. [Background technology]

[0002] The use of artificial turf for surfaces in sports arenas such as hockey, football, rugby, etc., has increased quite rapidly due to the convenience and economic efficiency of maintenance compared to natural turf. Existing artificial turf used in such sports arenas, particularly hockey arenas, requires frequent watering to keep the turf surface sufficiently cool and smooth according to established standards published by the governing bodies of these sports. Furthermore, the purpose of watering is to provide surface conditions that enable and maintain special playing characteristics. However, frequent watering is costly and leads to water waste. Thus, there is a need for more advanced artificial turf that can overcome these shortcomings of conventionally known turfs.

[0003] Lubricants in the artificial turf industry have been used extensively, but mainly during the processing steps for producing artificial turf fibers, or in the backing and infill materials of artificial turf. Also, the use of reflective pigments to keep artificial turf cool has been reported in the literature. For example, see US20170233956A1 and EP3936665A1, which describe artificial turf infill compositions using lubricants and reflective pigments.

[0004] Various attempts have been made to produce artificial turf that looks natural and at the same time does not change its performance characteristics in different weather conditions. For example, US Patent Application Publication No. 20220025587A1 describes an artificial turf that is said to have an improved natural grass look and feel. The '587 patent application describes producing turf fibers having a composite structure with a core made of a first polymer and a shell made of a second polymer. The shell is said to be made from an acrylic polymer. The '587 patent application describes the use of stearic acid as an emulsifier used in the processing of the first polymer for the turf fiber core.

[0005] U.S. Patent No. 9,309,630 B2 describes an artificial turf for sports that is said to change little with changes in moisture and temperature during play. The '630 patent uses a sheet of nonwoven fibers that are held together by being intertwined with one another. It is described that some of the fibers may have free ends, as well as some loops of fibers, extending over the sheet.

[0006] US Patent No. 8,691,906 B2 describes a process for producing at least one monofilament from a thermoplastic polymer material comprising at least one polyester material, nanoparticles, and optionally further additives including a lubricant. The process includes adding the components, either as a partial or complete mixture or separately, to an extruder, and first strand extruding the thermoplastic polymer material, cooling, stretching, and finally heat treating at a temperature ranging from 40 to 120°C for 0.01 to 10 minutes. The '906 patent describes that when the nanoparticles are highly branched polyesters and / or polycarbonates, the nanoparticles can be combined with UV stabilizers and lubricants.

[0007] Despite the above rather limited attempts to produce artificial turf that can perform equally well in hot or wet weather and maintain its properties over long periods of time, to date there is no practical solution that can significantly reduce the need to water artificial turf in hot weather, particularly for field surfaces used in sports such as hockey. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention overcomes the aforementioned limitations of existing artificial turf.

[0009] It is an object of the present invention to provide artificial turf fibres and artificial turf using these fibres which are particularly suitable for playing surfaces for sports such as hockey and which significantly reduce the need for frequent watering of the artificial turf.

[0010] Another object of the present invention is to provide an artificial turf having a surface that remains smooth and maintains its properties over the entire service life of the artificial turf.

[0011] Another object of the present invention is to provide an artificial turf that stays cooler in hot weather conditions.

[0012] Another object of the present invention is to provide an artificial turf with improved tribological properties. The fiber surface of the present invention exhibits similar tribological and / or mechanical properties whether wet or dry. In sports such as hockey, the turf feels like a wet / irrigated artificial turf to the player even when the turf is not irrigated at all, thus saving water.

[0013] Another object of the present invention is to provide an artificial turf which largely maintains its performance characteristics whether irrigated / wet (e.g. after a rain shower) or dry, especially in very hot and sunny weather. [Means for solving the problem]

[0014] The solution to the above object provided by the present invention is an artificial turf comprising a polymeric material and an anti-slip agent incorporated within the polymer, characterized in that the anti-slip agent has an effective rate of movement within the polymer and is provided in an amount sufficient to continue to provide an effective reduction in the fiber coefficient of friction at the surface of the fiber for at least one year, preferably at least two years, more preferably at least five years, and most preferably at least ten years. Thus, the artificial turf is installed on the field with a reservoir of anti-slip agent to continue to reduce the fiber coefficient of friction over the entire service life of the artificial turf in practice.

[0015] The term "anti-slip agent" as used herein means an agent that allows the coefficient of friction of the artificial turf fibers to be controlled within a desired range in both wet and dry conditions, thus preventing excessive slippage of players on the artificial turf surface in rainy / wet conditions, or too little slippage in dry, sunny conditions. Anti-slip agents may also be referred to as traction control agents, since they are designed to control the traction of the artificial turf within a desired range.

[0016] The anti-slip agent is incorporated into the polymer fiber and migrates to the surface by its diffusion coefficient, maintaining an equal distribution of the anti-slip agent concentration within the volume. At the surface of the polymer fiber, it modifies the surface chemistry, i.e., the coefficient of friction, thus reducing the tribological interactions and thus providing protection of the fiber from friction, wear and abrasion.

[0017] By effective travel speed is meant a speed that allows the anti-slip agent to continue to provide an effective reduction in the fiber coefficient of friction for a particular period of time.

[0018] Effective reduction of the fiber coefficient of friction means having a sufficient amount of anti-slip agent on the surface of the fiber to reduce the fiber coefficient of friction by at least 5%, preferably by at least 10%, and more preferably by at least 15% but not more than 25%.

[0019] The polymeric material affects the ability of the turf to store the anti-skid agent by slowing down the rate of migration of the anti-skid agent. It is selected from the group consisting of polyolefin homopolymers, polyolefin random polymers, preferably polyethylene homopolymer fibers, polyethylene alloy fibers, polyethylene copolymer fibers, and polyethylene impact copolymer fibers. In one embodiment, the fibers include LDPE, LLDPE, and / or HDPE, and mixtures thereof. LDPE has a viscosity of 0.905 g / cm 3 ~0.920g / cm 3 and LLDPE has a density of 0.914 g / cm 3 ~0.928g / cm 3 and HDPE has a density of 0.92 to 0.98 g / cm 3 The density may be

[0020] In one embodiment, the polymeric material for the fibers is a blend of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE).

[0021] In one embodiment, the polymeric material for the fibers is high density polyethylene (HDPE).

[0022] In another embodiment the polymeric material for the fibres is a blend of LDPE and HDPE, the LLDPE preferably being 10-70% by weight of the polymeric material, more preferably 15-50% by weight, more preferably 25-45% of the total amount of LDPE and HDPE.

[0023] In another embodiment the polymeric material for the fibres is a mixture of LDPE and LLDPE, the LLDPE preferably being 10-70% by weight of the polymeric material, more preferably 15-50% by weight, more preferably 25-45% of the total amount of LDPE and LLDPE.

[0024] In another embodiment, the LLDPE may be a random copolymer of polyethylene and at least one of butene, hexene, and octene.

[0025] In a preferred embodiment, the polymer material for the fibers is a mixture of LLDPE and HDPE, the LLDPE being based on hexene or octene comonomers and having a viscosity of 0.916 to 0.920 g / cm 3 whereas HDPE has a density of 0.952-0.957g / cm 3 and in an amount of 5-18% by weight of the total polymer mixture, more preferably about 15% by weight.

[0026] In another preferred embodiment, the polymeric material comprises 80-84 wt%, particularly 81.75 wt%, of LLDPE-C6, wherein at least 85 wt% of the LLDPE-C6 is bio-based; HDPE, wherein at least 90% by weight of the HDPE is bio-based, between 8.0 and 12.0% by weight, particularly 10.0% by weight; 6 to 10% by weight, particularly 8% by weight, of the masterbatch; 0.1 to 0.5 wt. %, in particular 0.25 wt. %, of a processing aid; and 0.25% to 0.5% by weight of erucamide. The masterbatch may also include color pigments and UV stabilizers. The masterbatch may include color pigments with a polyethylene carrier and UV stabilizers, such as UV stabilizers including 1,6 hexanediamine, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate, and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate). Other suitable UV stabilizers may also be used, such as those disclosed in European Patent No. 3762451 to Sick et al., entitled "Artificial Turf Fibers with UV Protective Material."

[0027] Suitable anti-slip agents are fatty acid amides and stearates, ie salts and esters of stearic acid, commonly called stearates, or organosilicone products, such as siloxanes of the polydimethylsiloxane type.

[0028] Preferred fatty acid amides as anti-slip agents are erucic acid amide (hereinafter also known as EAA, erucamide), lauramide, stearamide, oleamide, elaideamide, linoleamide, behenamide, palmitamide, N,N-ethylene-bis-oleamide, decanamide, etc., and mixtures thereof, more preferred are EAA, oleamide, linoleamide, and elaideamide.

[0029] Suitable stearic acid esters and salts include, for example, methyl stearic acid ester, ethyl stearic acid ester, and N-hydroxysuccinimide stearic acid ester (C 22 H 39 NO 4 ), sodium stearate, potassium stearate, and calcium stearate.

[0030] The anti-slip agent is used in an amount of 0.05 to 1.0% by weight, preferably 0.1 to 0.7% by weight, and more preferably 0.2 to 0.6% by weight, based on the total weight of the artificial turf fiber.

[0031] To prevent overheating of the fibers in hot weather conditions and thus further reduce the need to water the turf, preferably the fibers also include reflective agents, such as reflective particles, and / or reflective pigments. These reflectors and pigments have the advantage of reducing the heat on the artificial turf field, thereby further reducing the need to water the artificial turf. Suitable reflective agents include titanium dioxide, zinc sulfide (ZnS), tin oxide, aluminum oxide (AlO 3 ), zinc oxide, calcium sulfate, barium sulfate, calcium carbonate, antimony oxide, sodium silicate, aluminum silicate, silica, mica, clay, etc.

[0032] In a preferred embodiment, the IR reflector is rutile (MeO 2 ), Hematite (Me 2 O 3 ), or spinel (Me 3 O 4 ) type of mixed metal oxide.

[0033] The reflector is used in an amount of 0.01% to 8.0% by weight, preferably 0.3% to 5.0% by weight, and more preferably 0.3% to 3.0% by weight, based on the total weight of the fiber.

[0034] Another aspect of the invention relates to an artificial turf comprising a plurality of artificial turf fibres securely attached to a backing. Preferably, at least a proportion of the plurality of artificial turf fibres form closed loops extending above the upper surface of the artificial turf backing. In a more preferred embodiment, all of the plurality of artificial turf fibres form closed loops extending above the upper surface of the artificial turf backing. It has been found that closed fibre loops are particularly suitable for further enhancing the smoothness of the turf fibres, and are particularly suitable for the surface of sports fields such as hockey.

[0035] In another preferred embodiment, the fibers are textured to further enhance the fiber's ability to dissipate heat and to improve overall appearance and mechanical properties, such as overall smoothness.

[0036] According to embodiments, the fibers are highly textured, thereby increasing the smoothness of the artificial turf surface and making the surface more similar to a wet artificial turf surface, even when water is not present. "Textured" fibers are fibers that have a shape memory that returns to a non-linear, e.g., coiled, wrinkled, folded, and / or twisted, shape when released.

[0037] According to an embodiment, the artificial turf fibers are incorporated into the backing and have a density (number of fibers per area of ​​artificial turf) and / or degree of texturing such that, from a bird's-eye view, at least 60%, more preferably at least 70% of the size of the area covered by the artificial turf consists of fibers, the remainder consisting of backing or infill. In a preferred embodiment, the turf structure is typically similar to a water-filled high pile weight hockey no infill.

[0038] In yet another preferred embodiment, the portion of the fiber extending over the backing is fully or partially textured. Textured fiber means that at least a portion of the fiber extending over the backing is not straight, but has at least one of a curl or wave. The curl or wave can be generated mechanically or chemically during the manufacture of the fiber.

[0039] The artificial turf backing is made from a thermosetting polymeric material, which may include, for example, a polyurethane resin.

[0040] In yet another aspect of the present invention, there is provided a method of producing an artificial turf, the method comprising: forming a polymer mixture including at least one polymer, an anti-slip agent, and preferably also reflective particles; feeding the polymer mixture into an extruder to form a monofilament; cooling the monofilament; and reheating the monofilament; and drawing the reheated monofilament to form a monofilament; bundling a plurality of the monofilaments to form an artificial turf fiber; and incorporating the artificial turf fibers into a backing to form the artificial turf.

[0041] In one embodiment, incorporating the grass fibers into the carrier includes arranging the fibers such that a first fraction of the fibers is located on the back side of the carrier (hereinafter also referred to as the back fraction of the fibers), a second fraction of the fibers protrudes on the front side of the carrier (hereinafter also referred to as the front fraction of the fibers), and a third fraction of the fibers is inside the carrier (hereinafter also referred to as the middle fraction of the fibers or the carrier portion of the fibers).

[0042] According to certain preferred embodiments, the artificial turf backing includes a biocide (also called an antimicrobial agent) that is a zinc-based antimicrobial agent or a metal coordination complex with pyrithione. The use of a biocide in the artificial turf backing prevents microbial infestation of the turf, which, combined with the reduced watering requirements of the artificial turf fibers of the present invention, provides a significant improvement over existing artificial turf for hockey fields that require extensive watering and are therefore susceptible to microbial infestation.

[0043] Examples of suitable metal coordination complexes with pyrithione that can function as antibacterial agents include zinc pyrithione, manganese pyrithione, copper pyrithione, and sodium pyrithione. Examples of suitable zinc-based antibacterial agents other than zinc pyrithione include zinc oxide nanoparticles and zinc-glucose-citrate complex. Particularly preferred is zinc pyrithione (often also commonly referred to as zinc pyrithione).

[0044] Zinc pyrithione is used as the antimicrobial agent in an amount of 0.05% to 1.5% by weight of the polyurethane reaction mixture, preferably in an amount of 0.08% to 0.7% by weight of the polyurethane reaction mixture. More preferably, zinc pyrithione is used as the antimicrobial agent in an amount of 0.1% to 0.5% by weight of the polyurethane reaction mixture. The use of zinc pyrithione in artificial turf backings is described in commonly assigned co-pending U.S. patent application having application serial number 63 / 345,549, filed with the U.S. Patent and Trademark Office on May 25, 2022, which is incorporated herein for its disclosure of the use of biocides in polyurethane backings of artificial turf.

[0045] In a preferred embodiment, the fibers used are textured monofilaments with a degree of texture of 25-40% after 5 minutes at 90°C.

[0046] In the most preferred embodiment, the monofilament fibers have a degree of texturization of 32-37% after 5 minutes at 90° C. and are selected from triangular, square or elliptical morphologies and mixtures thereof.

[0047] According to some embodiments, the artificial turf does not include infill.

[0048] In a further embodiment, the artificial turf is either covered with sand or filled with sand.

[0049] In a further embodiment, the artificial turf is filled with an elastomeric material selected from the group of thermoplastic elastomers (TPEs) such as styrene-butadiene rubber, natural butadiene rubber, styrene block copolymers, whereby the infill may preferably contain a reflective agent based on mixed metal oxides.

[0050] Yet another aspect of the invention relates to the use of artificial turf in hockey fields that comply with the standards of the International Hockey Federation, known by the acronym FIH.Due to the continuous decrease in the fiber friction coefficient of the surface of the artificial turf fibers, watering of the surface of the artificial turf field can be substantially reduced or even become unnecessary.

[0051] Although the exact mechanism of migration of the anti-slip agent in the polymeric material and its interaction with the reflective particles is not fully understood, it has rather surprisingly been found that the anti-slip agent, particularly erucic acid amide and similar types of fatty acid amides, slowly migrates from the interior of the fiber to the surface, where it accumulates and replaces the anti-slip agent lost through normal wear and abrasion of the fiber over an unexpectedly long period of time. For the claimed combination of polymeric material, anti-slip agent, and preferably reflective agent, the reduction in the coefficient of friction of the fiber can last for the typical service life of an artificial turf, which can range from 10 to 15 years.

[0052] These and other features and advantages of the present invention will become better understood from the following detailed description of the invention taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0053] Embodiments of the invention will now be described in more detail, by way of example only, with reference to the drawings, in which:

[0054] [Figure 1] 1 is a flowchart showing an example of a method for manufacturing an artificial turf. [Figure 2a] FIG. 2 shows a cross section of a polymer mixture. [Figure 2b] FIG. 1 shows further examples of polymer mixtures. [Diagram 3] FIG. 1 shows further examples of polymer mixtures. [Figure 4] FIG. 1 illustrates the extrusion of a polymer mixture into a monofilament. [Diagram 5] FIG. 1 illustrates tufting of artificial turf fibers. [Figure 6] FIG. 2 shows a first and second portion of a fiber. [Figure 7] FIG. 2 illustrates a portion of a first portion and a second portion of fiber embedded in a turf backing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] The present invention provides an artificial turf fiber comprising a polymeric material and an anti-slip agent incorporated / contained in the polymeric material in an amount sufficient to sustain a slow migration from the interior of the fiber to the surface for at least one year. The fiber polymeric material and anti-slip agent are selected to allow slow diffusion of the anti-slip agent toward the surface of the artificial turf fiber where they accumulate and replace the anti-slip agent lost due to normal wear and abrasion of the fiber. The anti-slip agent is added to the fiber in an effective amount designed to continue to reduce the coefficient of friction of the fiber for a period of preferably at least 5 years, more preferably at least 10 years, and most preferably at least 15 years.

[0056] Without wishing to be bound by theory, important factors believed to control the diffusion of anti-slip agents to fiber surfaces include, for anti-slip agents, the type of anti-slip agent, the size of the anti-slip agent, and the hydrophilicity of the anti-slip agent, while for polymeric materials, the type and density of the polymeric material. Through extensive study and consideration of the above factors, the polymeric material, anti-slip agent, and preferably the reflective agent, and their relative amounts for the fiber were selected.

[0057] In a particular embodiment, the EAA is used in an amount of 0.5% by weight based on the total weight of the grass fiber. The grass fiber may be made from a mixture of 10% LDPE and 90% LLDPE by weight of the overall polymer weight. In another embodiment, the EAA is used in an amount of 1.0% by weight based on the total weight of the grass fiber made from a mixture of LDPE and LLDPE. In yet another embodiment, the EAA is used in an amount of 1.5% by weight based on the total weight of the ...5% by weight of HDPE (density 0.955 g / cm 3 ) and 85% by weight of LLDPE (density 0.920 g / cm 3 ) is used in an amount of 1.0% by weight based on the total weight of the grass fiber produced from the mixture.

[0058] Preferably, the fibers also include reflective agents, such as reflective particles and / or pigments, to prevent overheating of the fibers.

[0059] artificial grass

[0060] An example of a method for producing artificial turf includes incorporating artificial turf fibers into a carrier and adding a viscous thermosetting resin reaction mixture to the backside of the carrier to form a thermosetting resin backing. For example, various additives may be added to the thermosetting reaction mixture, including biocides with antimicrobial, antibacterial and antifungal properties. Once the thermosetting reaction mixture is placed on the backside of the carrier, the thermosetting reaction mixture is cured to form a solid thermosetting resin backing with the portion of the turf fibers protruding from the backside of the carrier firmly embedded within the solid mass of the thermosetting resin backing. The thermosetting resin may be any suitable resin. Preferably, the thermosetting resin may be a polyurethane resin. In one embodiment, the polyurethane is a reaction product of a first and a second polyol with an isocyanate, the first polyol being a polyether polyol and / or polyester polyol having at least two hydroxyl groups per molecule, the second polyol being a polybutadiene diol, and the isocyanate comprising an isocyanate monomer, an isocyanate polymer or an isocyanate prepolymer or mixtures thereof, the isocyanate monomer, the isocyanate polymer and the isocyanate prepolymer having two or more isocyanate groups per molecule. The polybutadiene diol may be used in an amount of 0.5-10% by weight of the combination of the first polyol and the isocyanate, and may have a number average molecular weight in the range of 500-6000 g / mol, more preferably in the range of 1500-4500 g / mol. The polyurethane reaction mixture may further comprise surfactants and other additives and fillers. Curing of the fluid polyurethane mass may be carried out, for example, by heating the polyurethane reaction mixture on the backside of the carrier to a temperature of 70-140°C.

[0061] The manufacture of turf fibers includes forming a polymeric material mixture in a first container, preparing an additive mixture in a separate or multiple separate smaller containers, including an anti-slip agent for the fiber, preferably a reflective agent, and optionally various other additives, and mixing the polymeric material mixture with the additive mixture to form an extrusion feed mixture that is fed to an extruder to form a monofilament (in practice, typically multiple monofilaments). The monofilaments exiting the extruder are cooled, for example, by passing through a water bath, and after exiting the water bath, the monofilaments are reheated, for example, in an air oven. The reheated monofilaments are oriented by drawing to form oriented monofilaments that are used as artificial turf fibers, either individually or after being combined with other monofilaments. For example, multiple monofilaments may be combined to form an artificial turf fiber that can be wound into a yarn, through well-known processes. Anti-slip agents and preferably reflective agents may also be added to the additive mixture in the smaller containers. However, it should be understood that this is merely an example and that the anti-slip agent can be added directly with the polymeric material mixture in a larger container or as a separate feed to the extruder feed. The polymeric mixture may further include nucleating agents to crystallize the polymers within and on the surface of the monofilaments, anti-UV agents, flame retardants and other optional additives. Artificial turf fibers are typically bundles of at least five monofilaments.

[0062] Reflective agents (e.g., reflective particles and / or reflective pigments) are used to counteract overheating of the turf. These reflective particles and pigments have the advantage of cooling the artificial turf field, thereby compensating for the loss of cooling effect of water when water is not present. Applicant has also found that the type and amount of reflective agent can affect the effective rate of migration of the anti-slip agent in the polymeric material matrix of the fiber.

[0063] The polymeric material mixture and the additive mixture, which also includes the anti-slip agent, preferably a reflective agent, may be blended using a blender or mixing device prior to addition to the extruder.

[0064] The term "tufting" as used herein refers to a method of incorporating fibers into an existing carrier. Short U-shaped loops of fibers are introduced through the carrier from one side with their ends pointing out of the carrier in the other direction. Usually, the tufted threads form a regular array of "dots" on the other side. On the side of the carrier where the U-shaped loops are located, the tufted fibers may be knotted for fixation, but need not be. The ends of the tufted threads can then be optionally frayed or otherwise treated so that they will subsequently produce a dense layer of fibers protruding from the carrier.

[0065] The term "weaving" as used herein refers to a method of incorporating artificial turf fibers (which may be monofilaments or bundles of monofilaments) into an existing carrier, whereby the artificial turf fibers and the fiber(s) that make up the carrier are interwoven. The interwoven fibers and mesh form a woven or cloth-like structure. When artificial tufted fibers are incorporated by weaving, the fibers interweave a series of mesh fibers at least three times. Thus, a higher percentage of the artificial turf fibers are interwoven into the carrier material when the fibers are incorporated by weaving rather than tufting. This may increase the resistance of the artificial turf to wear and tear.

[0066] According to an embodiment, incorporating the artificial grass fibers into the carrier comprises tufting the artificial grass fibers into the carrier. According to an alternative embodiment, incorporating the artificial grass fibers into the carrier comprises weaving the artificial grass fibers into the carrier.

[0067] 1, a flow chart illustrating an example of a method for manufacturing artificial turf is provided. First, in step 102, a polymer mixture is made, such as mixture 200 shown in FIG. 2a. The polymer mixture 200 includes at least one polymer 204, an anti-slip agent 202, and preferably a reflective agent 208 (e.g., reflective particles 208) for providing a continuous reduction in the fiber's coefficient of friction for at least 1 year, preferably at least 5 years, more preferably at least 10 years, and most preferably at least 15 years.

[0068] The polymer mixture can be made by combining all of its constituent components at once. For example, at least one polymer 204, anti-slip agent 202, reflective agent 208, and optional additives 206 can all be added together at the same time. The polymer mixture can be thoroughly mixed, for example, by using a mixer device. The desired distribution of the components can be achieved by using the appropriate speed or amount of mixing. The resulting mixture can be sent to a single screw feed or twin screw feed for extrusion.

[0069] Additional optional materials may be added, and reflective pigments 302 may be used in addition to or instead of the reflective particles, as shown in FIG.

[0070] In step 104, the polymer mixture is extruded into a monofilament 506, as shown in FIG. 4. Then, in step 106, the monofilament is cooled or quenched. In step 108, the monofilament is reheated, and in step 110, the reheated monofilament is stretched to form a monofilament that can be used directly as an artificial turf fiber or can be bundled with additional monofilaments into an artificial turf fiber. Additional processes may be performed on the monofilament to form an artificial turf fiber. For example, the monofilament may be spun or woven into a yarn having desired properties. Then, in step 112, the artificial turf fiber is incorporated into an artificial turf backing. Incorporation includes step 114 of placing a plurality of artificial turf fibers on a carrier 704 (see FIG. 6 and FIG. 7). The carrier may be, for example, a woven fabric plane. The artificial turf fiber is positioned such that a first portion 706 of the monofilament is exposed on the bottom side of the carrier and a second portion 702 of the monofilament is exposed on the top side of the carrier. The placement may be accomplished by tufting or weaving the artificial turf fibers into the carrier, although other methods of placing the fibers within the carrier are possible.

[0071] Then, in step 116, a resin reactive fluid mixture is added to the bottom side of the carrier such that at least a first portion is embedded in the fluid. Finally, in step 118, the fluid mixture is solidified into a film. The film surrounds and thereby mechanically fixes at least the first portion 706 (and optionally some portions 804 of the second portion 702) of the monofilaments within the film. The film, i.e., the solidified fluid, constitutes the backing 802.

[0072] FIG. 2a shows a cross-section of a polymer blend 200 including at least a first polymer 204, preferably a non-polar polymer such as polyethylene, and an anti-slip agent 202, such as EAA. The polymer blend may further include additives 206, such as dyes to color the fiber, biocides to add antimicrobial properties, nucleating agents, etc. The anti-slip agent 202 should be added in an appropriate amount and have a slow migration rate within the polymer material matrix of the fiber, so that the surface of the fiber can continue to be replenished with the anti-slip agent for at least 1 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 blend of LDPE and LLDPE, where the LDPE is 10% by weight of the total polymer blend of LDPE and LLDPE, and the LLDPE is 90% by weight. The anti-slip agent 202 is, for example, EAA, and is used in an amount of 0.5% by weight based on the total weight of the fiber, i.e., the total weight including polymer, anti-slip agent, and additives.

[0073] FIG. 2b shows a polymer mixture 250 that includes all the components of the mixture 200 of FIG. 2a, plus a reflective agent 208. The reflective agent 208 is, for example, titanium dioxide, used in an amount of 1.0% by weight based on the total amount of polyethylene, EAA, and any additives. Said reflective agent 208 prevents overheating of the fibers, thus further reducing the need to water the turf frequently. Although the exact mechanism is not well understood, the presence of the reflective agent (i.e., reflective pigments and / or reflective particles) in the polymer matrix of the fibers and their respective amounts may affect the migration rate of the anti-slip agent inside the polymer matrix of the fibers. Thus, the amount of reflective agent in the fibers is controlled to obtain a migration rate of the anti-slip agent that ensures that the anti-slip agent can continue to reduce the coefficient of friction of the fibers, most preferably during the service life of the artificial turf. This is a rather unexpected and surprising synergistic effect between the anti-slip agent and the reflective agent.

[0074] FIG. 3 shows a cross-section of a polymer blend 300 that includes at least a first polymer 204 , such as the LDPE / LLDPE blend discussed above, and an anti-slip agent 302 .

[0075] FIG. 4 illustrates the extrusion of a polymer mixture into a monofilament 506. A schematic simplified cross-sectional view of a quantity of polymer mixture 200 is shown. Dispersed within the polymer mixture 200 is an effective amount of an anti-slip agent 202 (e.g., EAA), and optionally an additional additive 206. Preferably, the additive 206 also includes a reflective agent, as described above. A screw, piston, or other device is used to force the polymer mixture 200 through holes 502 in a plate 504. This extrudes the polymer mixture 200 into a monofilament 506. The monofilament 506 is shown as containing the anti-slip agent 202 and the additive 206 (preferably also including a reflective agent).

[0076] 5 and 6 show how multiple artificial grass fibers can be placed on a carrier 704, e.g., a textile plane, by tufting. Tufting is a type of textile weaving in which an artificial grass fiber 701 (which may be a monofilament 506 or a bundle of multiple monofilaments) is inserted onto a carrier 704. After the insertion is made, a short U-shaped loop of fiber is oriented outwardly of the surface of the carrier, as shown in FIG. 5. Then, one or more blades cut the loop (602). As a result of the cutting process, two artificial grass fiber ends per loop and monofilament are oriented outwardly from the carrier, creating a grass-like artificial grass surface. This results in a first portion 706 of the monofilament of the artificial grass fiber inserted into the carrier 704 being exposed on the bottom side of the carrier, and a second portion 702 of the monofilament being exposed on the top side of the carrier.

[0077] In a preferred embodiment of the artificial turf for a hockey field, the cutting step 602 is omitted and the artificial turf is created with U-shaped loops forming the top surface of the turf.

[0078] FIG. 7 shows a carrier 704 with inserted filaments embedded in (FIG. 7a) or adjacent to (FIG. 7b) the artificial turf backing 802. This is done in step 116 (see FIG. 1) by adding fluid onto the carrier 704 such that the first portion 706 of the monofilament is embedded in the fluid (FIG. 7a) or some portions 804 of the first and second portions 702 of the monofilament are embedded in the fluid (FIG. 7b). The carrier may be a woven mesh or may be provided with perforations that allow the fluid 802.2 on the bottom side of the carrier to flow to the top side of the carrier and vice versa, thereby creating a portion of the backing 802.1 on the top of the carrier. Thus, the carrier and some of the fibers inserted in the carrier can 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 pile height of the artificial turf fibers 701.

[0079] For example, the fluid may be a styrene-butadiene suspension that solidifies on a latex backing, or preferably a mixture of polyol and polyisocyanate that solidifies on a polyurethane backing, or any other type of fluid that can solidify into a solid film after a predetermined time. The fluid solidifies into the film 802, for example, by a drying process or by a chemical reaction that results in the solidification of the fluid. Such a chemical reaction may be, for example, polymerization. The film surrounds and thereby mechanically fixes at least a first portion of the monofilaments of the disposed artificial turf fibers. The solid film acts as a backing for the artificial turf. In some examples, an additional coating layer may be added to the bottom of the artificial turf backing.

[0080] Working Example

[0081] In Example 1, 0.5 wt. % of the EAA anti-slip agent was added to a polymer blend of 60 wt. % LDPE and 40 wt. % LLDPE. The LDPE had a viscosity of 0.905 g / cm. 3and LLDPE has a density of 0.918 g / cm 3 The mixture had a density of 1000 nm and was a copolymer of polyethylene and butene. No reflective agent was added. Additives such as color pigments, flame retardants, etc. were also added and the mixture was extruded in conventional extrusion equipment to form artificial turf fibers which were then added to an artificial turf structure having a polyurethane backing as described above with reference to the figures.

[0082] In Examples 2-5, the same process was repeated with the main parameters shown in Table 1. In Examples 2-5, the fibers were textured such that the top of at least about 30% of their length extended in a wave shape over the backing and any infill material. Compared to Example 1, which contained straight fibers, the turf made with the textured fibers of Examples 2 and 5 showed a significant improvement in its overall smoothness and coverage.

[0083] The same process was repeated a total of five times with the key compounds added each time as shown in Table 1 below.

[0084] [Table 1]

[0085] The above formed fibers of Examples 1-5 were tested and compared to Comparative Examples 6-10.

[0086] Significant improvements in overall smoothness and tribological properties were observed between Examples 1-5 and their corresponding Comparative Examples 6-10. A significant reduction in the coefficient of friction of at least 10% was observed in Examples 1-5 compared to their corresponding Comparative Examples 6-10. Furthermore, it was rather unexpectedly found that the above formed fibers with EAA prevent excessive slippage under rainy / wet conditions while providing a sufficiently smooth surface under dry / sunny conditions. This not only eliminates the need to water the artificial turf, but also prevents excessive slippage under rainy / wet conditions. Surprisingly, slippage does not increase or does not increase substantially when the artificial turf becomes wet due to rainy weather or the like, relative to dry conditions.

[0087] Comparative Examples 6-10 used the same fiber compositions as Examples 1-5, except that no anti-slip agent was used in the polymer mixture.

[0088] In Example 11, LLDPE and HDPE were used with an effective amount of erucamide (EAA) according to the following composition: LLDPE-C6: 81.75% by weight; HDPE: 10% by weight; Masterbatch: 8 wt%; Calcium stearate as a processing aid: 0.25% by weight; and Erucamide: 0.25% by weight. The LLDPE-C6 was 85 wt% bio-based, and the HDPE was 90 wt% bio-based. In Examples 12 to 16, the amount of erucamide was changed to 0.30% by weight in Example 12, 0.35% by weight in Example 13, 0.40% by weight in Example 14, 0.45% by weight in Example 15, and 0.5% by weight in Example 16. The amount of the master batch was adjusted accordingly. The erucamide was mixed into the master batch and added to the polymer together as part of the master batch.

[0089] Bio-based polyethylene materials are produced from ethylene derived from sugarcane-based bioethanol and are fully recyclable. The bio-based materials had some impurities, as well as calcium stearate added as a processing aid by the material's manufacturer. Thus, bio-based LLDPE and HDPE are chemically different from gasoline-based LLDPE and HDPE, respectively.

[0090] The masterbatch was 50% color pigment with a polyethylene carrier and 50% UV stabilizer including 1,6 hexanediamine, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate). Comparative Example 17 used the same composition as Example 11, except that no erucamide was used. Significant improvements in overall smoothness and tribological properties were observed between Examples 11-16 and Comparative Example 17. Significant reductions in coefficient of friction of at least 10% were observed over an extended period of at least one year in Examples 11-16 compared to Comparative Example 10. Furthermore, the above formed fibers having the above amounts of EAA prevent excessive slippage in rainy / wet conditions while providing a sufficiently smooth surface in dry / sunny conditions. This not only eliminates the need to water the artificial turf, but also prevents excessive slippage in rainy / wet conditions. Surprisingly, slippage does not increase or does not increase substantially when the artificial turf becomes wet due to rainy weather or the like, relative to dry conditions.

[0091] Although the present invention has been described with reference to specific embodiments, it is to be understood that the invention is not limited to these examples, and that, after reading this disclosure, many variations of these embodiments can be easily envisioned by those skilled in the art that do not depart from the scope of the invention as defined by the claims. [Explanation of symbols]

[0092] 102-118 Process Steps 200 Add to the mixture 202 Anti-slip agent 204 Polymer 206 Further Additives 208 Reflective particles or pigments 300 Polymer Mixture 502 Plate Hole 504 Plate 506 Artificial turf fiber monofilament 602 Cutting artificial turf fibers during tufting 701 Artificial turf fiber 702 Second part of the fiber 704 Career 706 First part of fiber 800 Artificial grass (cross section) 802 Lining made from solidifying fluid 804 A portion of the second portion of the fiber embedded in the fluid. 806 Distance <carrier surface - top of fiber>

Claims

1. 1. An artificial turf fiber comprising a polymeric material and an anti-slip agent selected from the group consisting of fatty acid amides and stearates incorporated / contained in the polymer, the anti-slip agent has an effective migration rate in the polymeric material and is provided in the polymeric material in an amount of 0.05 to 1.0 wt. % of the total weight of the fiber to provide a reduction in the fiber coefficient of friction at the surface of the fiber for at least 1 year, preferably at least 2 years, more preferably at least 5 years, and most preferably at least 10 years; the polymeric material is selected from the group consisting of polyolefin homopolymers and polyolefin random copolymers; The anti-slip agent controls the coefficient of friction of the artificial turf fibre within a desired range in both wet and dry conditions to prevent players from slipping too much on the artificial turf surface in rainy / wet conditions, or too little in dry, sunny conditions.

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

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

4. 2. The artificial turf fibre of claim 1, wherein the polymeric material is a mixture of LDPE and LLDPE, and the LLDPE preferably represents 10-70% by weight of the polymeric material, more preferably 15-50% by weight, more preferably 25-45% of the total amount of the LDPE and the LLDPE, and preferably the amount of the LLDPE in the polymeric material mixture is higher than the amount of the LDPE.

5. The polymeric material is a mixture of HDPE and LLDPE, the HDPE having a viscosity of 0.952 to 0.957 g / cm ３ and in an amount of 5.0-18% by weight, preferably 12-17% by weight of the total amount of the HDPE and the LLDPE.

6. 2. The artificial turf fiber of claim 1, wherein the anti-slip agent is a fatty acid amide.

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

8. The anti-slip agent is erucamide and the polymeric material is LLDPE-C6, wherein at least 85% by weight of the LLDPE-C6 is bio-based, between 80 and 84% by weight, in particular 81.75% by weight, HDPE, wherein at least 90% by weight of the HDPE is bio-based, between 8.0 and 12.0% by weight, particularly 10.0% by weight, 6 to 10% by weight, in particular 8% by weight, of the masterbatch; 0.1 to 0.5 wt. %, in particular 0.25 wt. %, of a processing aid; 0.25% to 0.5% by weight of erucamide; 10. The artificial turf fiber of claim 1, wherein the masterbatch comprises a color pigment and a UV stabilizer.

9. 10. The artificial turf fiber of claim 1, further comprising reflective particles and / or reflective pigments to prevent overheating of the fiber.

10. 10. The artificial turf fiber of claim 1, wherein the fiber is textured such that at least 30% of the portion of the fiber length that extends above the infill material has at least one of curl or wave to enhance flexibility and coverage.

11. 13. An artificial turf comprising a plurality of the artificial turf fibers of claim 1 securely attached to a backing, the plurality of artificial turf fibers forming a closed loop extending above a top surface of the backing.

12. 12. The artificial turf of claim 11, wherein the fibers are textured fibers and the density of the fibers is at least 60%, more preferably at least 70% of the area covered by the artificial turf.

13. 12. The artificial turf of claim 11, wherein the backing comprises a biocide which is a zinc-based antimicrobial or metal coordination complex with pyrithione, preferably zinc pyrithione.

14. Use of the artificial turf according to any one of claims 11 to 13 in a hockey field, wherein watering of said hockey field is substantially reduced or completely eliminated.

15. 14. A hockey field playing surface comprising the artificial turf of any one of claims 11 to 13, wherein watering of the hockey field is substantially reduced or completely eliminated and the hockey field playing surface is substantially free of microbial infestation during the useful life of the artificial turf.

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