ARTIFICIAL TURF FIBER WITH UV PROTECTION SUBSTANCES

Abstract

The invention relates to a polymer-based artificial turf fiber comprising substances (216) adapted for protecting the fiber against UV radiation. The substances comprise a hindered amine light stabilizerHALS and a first and a second UV-absorbent substance. The molecular weights of the first and the second UV-absorbent substances differ from each other by at least 100 g/mol.

Claims

1. A polymer-based artificial turf fiber comprising substances adapted for protecting the fiber against UV radiation, the substances comprising: a hindered amine light stabilizerHALS; and a first UV-absorbent substance; and a second UV-absorbent substance, the molecular weights of the first and the second UV-absorbent substances differing from each other by at least 100 g/mol.

2. The artificial turf fiber of claim 1, the HALS being 1,3-propanediamine, N,N-1,2-ethanediylbis-, reaction products with cyclohexane and peroxidized N-butyl-2,2,6,6-tetramethyl-4-piperidinamine-2,4,6-trichloro-1,3,5-triazine reaction products.

3. The artificial turf fiber of claim 1, the HALS being an N-methyl-HALS, the HALS being in particular 1,6-Hexanediamine, N,N-bis(2,2,6,6-tetramethyl-4-piperidinyl)-, polymers with morpholine-2,4,6-trichloro-1,3,5-triazine.

4. The artificial turf fiber of claim 1, the first UV-absorbent substance having a molecular weight smaller than 800 g/mol, preferably smaller than 600 g/mol.

5. The artificial turf fiber of claim 1, the first UV-absorbent substance being a sterically hindered phenolic antioxidant, in particular octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate.

6. The artificial turf fiber of claim 1, the second UV-absorbent substance having a molecular weight higher than 800 g/mol, preferably higher than 1000 g/mol.

7. The artificial turf fiber of claim 1, the second UV-absorbent substance being a sterically hindered phenolic antioxidant, in particular pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate).

8. The artificial turf fiber of claim 1, further comprising an organophosphite antioxidant (210).

9. The artificial turf fiber of claim 8, the organophosphite antioxidant being tris(2,4-ditert-butylphenyl)phosphite.

10. The artificial turf fiber of claim 1, the artificial turf fiber comprising the organophosphite antioxidant by at least 0.01%, more preferably by at least 0.05%, more preferably by at least 0.15% of the fiber's weight.

11. The artificial turf fiber of claim 1, the artificial turf fiber comprising: the HALS by at least 0.4%, more preferably by at least 0.6%, more preferably by at least 0.8% of the fiber's weight; and/or the first UV-absorbent substance by at least 0.05%, more preferably by at least 0.1%, more preferably by at least 0.2% of the fiber's weight; and/or the second UV-absorbent substance by at least 0.01%, more preferably by at least 0.05%, more preferably by at least 0.15% of the fiber's weight.

12. The artificial turf fiber of claim 1, further comprising a booster of photocatalytic degradation of the polymer material of the fiber, the booster being a metal salt or metal oxide.

13. The artificial turf fiber of claim 12, the booster being TiO2.

14. An artificial turf comprising artificial turf fibers according to claim 1.

15. The artificial turf of claim 14, comprising: first artificial turf fibers according to claim 1, the first artificial turf fibers comprising the booster of photocatalytic degradation, the booster being in particular a metal salt or metal oxide, the booster of photocatalytic degradation being a first pigment having a white or bright color; second artificial turf fibers and/or third artificial turf fibers, wherein the second artificial turf fibers are free of the first pigment and comprise at least 10% less of each of the substances than the at least one first fiber, wherein the third artificial turf fibers are free of the first pigment and are free of one or more or all of the substances.

16. The artificial turf of claim 14, further comprising rubber infill, the rubber comprising a plasticizer.

17. A method of producing an artificial turf fiber comprising: creating a polymer mixture, the creation comprising mixing a polymer-based polymer and substances adapted for protecting the fibers against UV radiation, the substances comprising: a hindered amine light stabilizerHALS; and a first UV-absorbent substance; and a second UV-absorbent substance, the molecular weights of the first and the second UV-absorbent substances differing from each other by at least 100 g/mol; extruding the polymer mixture into a polymer film or into a monofilament; and processing the film or the monofilament for transforming the film or the monofilament into the artificial turf fiber.

18. The method of claim 17, further comprising: integrating first artificial turf fibers in the carrier, the first artificial turf fibers comprising the substances adapted for protecting the fibers against UV radiation and comprising a booster of photocatalytic degradation, the booster of photocatalytic degradation being in particular a metal salt or metal oxide, the booster of photocatalytic degradation being a first pigment having a white or bright color; integrating second artificial turf fibers and/or third artificial turf fibers in the carrier, the second artificial turf fibers being free of the first pigment, the second artificial turf fibers comprising at least 10% less of each of the substances than the first fibers, the third artificial turf fibers being free of the first pigment and being free of one or more or all of the substances.

19. A masterbatch adapted for producing an artificial turf fiber, the masterbatch comprising a polyol and substances adapted for protecting the fiber against UV radiation, the substances comprising: a hindered amine light stabilizerHALS; and a first UV-absorbent substance; and a second UV-absorbent substance, the molecular weights of the first and the second UV-absorbent substances differing from each other by at least 100 g/mol.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In the following, embodiments of the invention are explained in greater detail, by way of example only, making reference to the drawings in which:

[0084] FIG. 1 shows a flowchart which illustrates an example of a method of manufacturing a UV protection substance mixture and an artificial turf comprising UV resistant fibers;

[0085] FIG. 2 shows the components of a polymer mixture including the individual components of the UV protection substance mixture;

[0086] FIG. 3 shows a sports field comprising a mixture of first fibers and second fibers.

[0087] FIG. 4 shows artificial turf; and

[0088] FIG. 5 shows the creation of a polymer mixture using a masterbatch.

DETAILED DESCRIPTION

[0089] Like-numbered elements in these figures are either equivalent elements or perform the same function. Elements which have been discussed previously will not necessarily be discussed in later figures if the function is equivalent.

[0090] FIG. 1 shows a flowchart which illustrates an example of a method of manufacturing artificial turf comprising a long-term UV resistant fiber. The method will be described by making reference to the components of a UV protection substance mixture used for generating the polymer mixture depicted in FIG. 2.

[0091] First in step 102, one or more HALSs 204, a first UV absorbent substance 206 and a second UV absorbent substance 208 and, optionally, further substances like an organophosphite oxidant 210 are intermixed for creating a UV protection substance mixture 216.

[0092] The UV protection mixture may have the advantage that it can be added without further adaptation to a large number of different polymers or polymer compositions comprising different types and concentrations of polymer types and additives like softeners. This is because the effect of the HALS and the UV absorbent substances support, boost and complement each other in limiting photo induced polymer degradation, and because the different molecular weights of the first and second UV absorbent substances ensure that any depletion of the polymer material at the surface is compensated by UV absorbents migrating from inner regions of the polymer material to the outer regions where UV protection is required the most. The UV protection mixture is mixed thoroughly and may have granular or powder form. The individual components of the UV protection mixture 216 are depicted in FIG. 2 separately for illustrative purposes only.

[0093] In some embodiments, the UV-protection substance mixture is added to a master batch in an amount that ensures that the compound polymer to be generated from the master batch comprises the desired amounts of each of the UV-protection substances.

[0094] Next in step 104, the UV protection substance mixture (or the masterbatch comprising the UV protection substances) is mixed with one or more polymers 218, e.g. PE, PA, PP, or a mixture thereof. In the example depicted in FIG. 2, the polymer comprises a bulk polymer 214, e.g. PE, and droplets (beads) of a different polymer, e.g. PA. The PA droplets may be emulsified in the bulk polymer when both polymers are heated above their melding points. The UV protection mixture may be mixed with the one or more polymers when the polymers 212, 214 are in solid, granular form, or may be added to the liquid emulsion of the two polymers 212, 214. In some examples, the UV protection mixture is mixed into a master batch first and the master batch is then mixed with the polymers 212, 214. In other embodiments, the UV protection mixture is directly mixed into the complete polymer composition that is to be extruded into a monofilament or a film. According to some examples, the bead polymer is a polar polymer while the bulk polymer is an apolar polymer. Optionally, the polymer 218 may comprise a compatibilizer to stabilize the beads of the bead polymer within the bulk polymer. Steps 102 and 104 may also be performed in a single step by mixing all UV-protection substances and the polyol in a single step.

[0095] According to some embodiments, the polymer fraction 218 in addition comprises additional polymers that are also immiscible with the bulk polymer 214 and/or further additives, e.g. pigments, flame retardants, and the like.

[0096] The complete polymer mixture 200 is then thoroughly stirred and mixed to achieve a homogeneous distribution of all components of the polymer mixture. The mixing is typically performed at high temperatures to ensure that all polymers 212, 214 are in liquid phase and can be homogeneously mixed, whereby the emulsion of the stabilizing polymer in the bulk polymer is maintained.

[0097] In the next step 106, the mixture 200 is extruded into a monofilament or a film.

[0098] In step 108, the monofilament or film is further processed for generating an artificial turf fiber. For example, the monofilament can be further processed for generating a monofilament or monofilament assembly that can be used as an artificial grass fiber. The film can be further processed to form tent or truck tarps or other sheet-like plastic material. The film can also be split into slices that are further processed for generating artificial turf fibers. The extrusion process may stretch the stabilizing polymer beads, if any, into threadlike regions which increase the resilience of the generated monofilaments.

[0099] For example, the processing of a monofilament can comprise quenching or rapidly cooling the extruded monofilament. Then, the cooled monofilament is reheated and the reheated monofilament is stretched. This causes the molecules of the stabilizing polymer to become aligned with each other in the direction that the fibers are stretched. The stretching deforms the polymer beads into thread-like regions.

[0100] Additional steps may also be performed on the monofilament to form the artificial turf fiber. For instance, the film can be processed for generating a fibrillated tape and/or the fibrillated tape or the monofilament may be spun or woven into a yarn with desired properties.

[0101] Finally, the stretched monofilament is formed into the artificial turf fiber that may be integrated in a backing to form the artificial turf.

[0102] The integration of the fiber can comprise, but is not limited to, tufting or weaving the artificial turf fiber into a carrier and applying a liquid backing, e.g. a PU or latex backing, on the lower side of the carrier such that at least portions of the artificial turf fibers are surrounded by the artificial turf backing. According to other embodiments, the artificial turf fibers may be glued or held in place by a coating or other material.

[0103] By stating that the stabilizing polymer and the bulk polymer are immiscible, it is meant that the stabilizing polymer is immiscible with at least a majority of the components that make up the bulk polymer. For example, the bulk polymer could be made of one polymer that is immiscible with the stabilizing polymer and then have a smaller portion of the bulk polymer made from a second polymer that is or may be at least partially immiscible with the stabilizing polymer.

[0104] According to embodiments, the polymer mixture 200 to be extruded and to form the polymer material is a combination of a mixture or blend of polymers of different types, e.g., of polar polymers (e.g., PA) and apolar polymers (e.g., PE). The bulk polymer can be an non-polar polymer or a combination of both polar and non-polar polymers. The bulk polymer may have a compatibilizer to enable the non-polar and polar polymers to be mixed. In the case where the bulk polymer is made of a mixture of non-polar and polar polymers, the majority of the bulk polymer by weight is non-polar, e.g., PE-based. In another embodiment, the bulk polymer comprises any one of the following: a non-polar polymer, a polyolefin polymer, a thermoplastic polyolefin polymer, a polyethylene polymer, a polypropylene polymer, a polyamide polymer, a polyethylene polymer blend, and mixtures thereof.

[0105] In another embodiment, the polymer bulk comprises a first polymer, a second polymer, and the compatibilizer. The first polymer and the second polymer are immiscible. The first polymer forms polymer beads surrounded by the compatibilizer within the second polymer. The terms polymer bead and beads may refer to a localized region, such as a droplet, of a polymer that is immiscible in the second polymer. The polymer beads may in some instances be round or spherical or oval-shaped, but they may also be irregularly shaped. In some instances, the polymer bead will typically have a size of approximately 0.1 to 3 micrometers, preferably 1 to 2 micrometers in diameter. In other examples, the polymer beads will be larger. They may, for instance, have a size with a diameter of a maximum of 50 micrometers.

[0106] In one embodiment, the polymer bulk by weight comprises more second polymer than first polymer.

[0107] In another embodiment, the second polymer is a non-polar polymer and the first polymer is a polar polymer. This embodiment may be beneficial because it may provide a way of tailoring the texture and feel of the monofilaments used to make the artificial turf.

[0108] In another embodiment, stretching the reheated monofilament deforms the polymer beads into thread-like regions. In this embodiment, the stretching of the monofilament not only aligns the PA fibers but also stretches the polymer beads into thread-like regions which may also aid in changing the structure of the monofilament.

[0109] According to embodiments, the thread-like regions generated by the extrusion and stretching steps can have a diameter of less than 20 micrometers, in some embodiments less than 10 micrometers. In another embodiment, the thread-like regions have a diameter of between 1 and 3 micrometers. In another embodiment, the artificial turf fiber extends a predetermined length beyond the artificial turf backing. The thread-like regions have a length less than one half of the predetermined length. In another embodiment, the thread-like regions have a length of less than 2 mm.

[0110] FIG. 2 shows a polymer mixture 200 generated by mixing one or more polymers 212, 214, optional additives like pigments, flame retardants and the like (not shown), and a UV-protection mixture 216 with each other. The individual components of the UV-protection substance mixture 216 are homogeneously mixed with each other and with the polymer 212, 214 and depicted separately in FIG. 2 merely for illustration. The polymer mixture 200 can be extruded to form a monofilament. One or more of the monofilaments can be used as an artificial turf fiber.

[0111] Depending on the embodiments, the substances 204, 206, 208, 210 may be added to the final polymer mixture that is to be extruded individually or in the form of an already premixed UV-protection substance mixture.

[0112] Alternatively, the UV-protection substances 204, 206, 208, 210 can be added to a masterbatch individually or as an already premixed UV-protection substance mixture, and the masterbatch can be mixed with the pure polymer(s) optionally comprising a compatibilizer for generating the polymer mixture to be extruded as depicted in FIG. 5.

[0113] The polymer mixture is separated into different components for illustrations only. In fact, the share of the UV-protection substances in the extruded polymer mixture is much smaller.

[0114] FIG. 3 shows a sports field made of an artificial turf comprising a mixture of first fibers and second fibers. The first fibers 302 comprise TiO2 used as a white pigment and constitute the fibers of the line markings. The second fibers 304 are free of the white pigment, they comprise a green pigment instead which does not boost photocatalytic degradation. The fibers 302, 304 of the artificial turf 300 show a homogeneous distribution of UV stability for all fiber types, because the first fibers 302 comprise the UV-protection substances while the second fibers 304 are either free of the UV-protection substances or comprise some or all of them in a significantly smaller amount.

[0115] FIG. 4 shows artificial turf 400 comprising artificial turf fibers 406 having been tufted into a carrier structure 402. The artificial turf fibers are firmly fixed into the carrier structure by a backing layer 404 made of polyurethane or latex that is applied in liquid state onto the lower side of the carrier and that fixes the U-shaped fiber portions when the liquid backing hardens. The artificial turf further comprises infill granules 408, e.g. rubber granules comprising a plasticizer. The artificial turf is installed on a base layer 410, e.g. a concrete, stone, sand or clay layer.

[0116] FIG. 5 shows the creation of a polymer mixture 500 that is extruded through an extrusion nozzle. A masterbatch 502 comprising the UV-protection substances and optional further additives such as pigments and/or flame retardants is mixed with a pure polymer or pure polymer mixture 504. For example, the polymer 504 can be pure PE or a mixture of PE/PA or any other type of polymer. The polymer 504 is typically free of any additives. Typically, the masterbatch constitutes about 6-12% by weight of the polymer mixture 500 that is finally extruded into the artificial turf fiber, the rest of the mixture 500 consists of the polyol 504.

[0117] According to some embodiments, the polymer mixture 200 is created by combining 6% of the masterbatch 502 and 94% of the polyol 504. According to other embodiments, the polymer mixture 200 is created by combining 10% of the masterbatch 502 and 90% of the polyol 504.

[0118] The masterbatch 502 is adapted for producing an artificial turf fiber 406 as shown, for example, in FIG. 4. The masterbatch comprises a polyol (typically of the same type as the polyol component 504) and substances 216 adapted for protecting the fiber against UV radiation. The substances comprise a hindered amine light stabilizerHALS 204, a first UV-absorbent substance 206, and a second UV-absorbent substance 208. The molecular weights of the first and the second UV-absorbent substances differ from each other by at least 100 g/mol.

[0119] According to an embodiment, the master batch comprises [0120] at least 4%, more preferably at least 6%, more preferably at least 8% by its weight the HALS; and/or [0121] at least 0.5%, more preferably at least 1%, more preferably at least 2% by its weight the first UV-absorbent substance; and/or [0122] at least 0.1%, more preferably at least 0.5%, more preferably at least 1.5% by its weight the second UV-absorbent substance; and/or [0123] at least 0.1%, more preferably at least 0.5%, more preferably at least 1.5% by its weight the organophosphite antioxidant.

LIST OF REFERENCE NUMERAL

[0124] 102-110 steps

[0125] 200 polymer mixture

[0126] 204 HALS

[0127] 206 first UV absorbent substance

[0128] 208 second UV absorbent substance

[0129] 210 organophosphite antioxidant

[0130] 212 bulk polymer (PE)

[0131] 214 polyamide (PA) beads

[0132] 216 UV protection mixture

[0133] 218 Polymer (PE/PA polymer emulsion)

[0134] 300 sports field made of artificial turf

[0135] 302 first fibers comprising TiO2

[0136] 304 second fibers being free of TiO2

[0137] 400 artificial turf

[0138] 402 carrier structure

[0139] 404 backing

[0140] 406 artificial turf fiber

[0141] 408 infill granules

[0142] 410 base layer

[0143] 500 polymer mixture

[0144] 502 masterbatch

[0145] 504 (pure) polymer(s)