POLYMER MATERIAL WITH FLAME RETARDANT

Abstract

The invention provides for an artificial turf fiber comprising or consisting of polymer material. The polymer material comprises a first flame retardant. The first flame retardant is a salt having a positive enthalpy of solution in water.

Claims

1. An artificial turf fiber comprising or consisting of a polymer material, the polymer material comprising a first flame retardant, the first flame retardant being a salt having a positive enthalpy of solution in water.

2. The artificial turf fiber of claim 1, the polymer material comprising at least 30% of its weight a hydrocarbon that combusts into CO2 and water.

3. The artificial turf fiber of claim 1, the first flame retardant being potassium iodide.

4. The artificial turf fiber of claim 1, the polymer material comprising a second flame retardant, the second flame retardant being a reducing agent.

5. The artificial turf fiber of claim 4, the reducing agent being a reducing agent that reacts with oxygen at temperatures above a threshold temperature, the threshold temperature being 100 C. or higher.

6. The artificial turf fiber of claim 4, the reducing agent being an elementary metal.

7. The artificial turf fiber of claim 6, the elementary metal being tungsten.

8. The artificial turf fiber of claim 4, the polymer material comprising at least 1%, preferably at least 8% by its weight of the reducing agent.

9. The artificial turf fiber of claim 1, the polymer material comprising at least 1%, preferably at least 8% by its weight of the first flame retardant.

10. The artificial turf fiber of claim 1 , the polymer material comprising a third flame retardant, the third flame retardant being a hindered amine light stabilizer (HALS).

11. The artificial turf fiber of claim 10, the HALS light stabilizer 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.

12. The artificial turf fiber of claim 10, the polymer material comprising at least 1%, preferably at least 2% by its weight the HALS light stabilizer.

13. The artificial turf fiber of claim 10, the polymer material comprising the HALS light stabilizer in an amount of 5%-15% by the weight of the polymer material, more preferably in an amount of 7%-13% by the weight of the polymer material.

14. A method of producing an artificial turf fiber comprising: creating a mixture, the creation comprising mixing a polymer and a first flame retardant, the first flame retardant being a salt having a positive enthalpy of solution in water; extruding the mixture into a polymer film or into a monofilament; and processing the film or the monofilament or a fibrillated tape generated from the film for transforming the film or the monofilament or the fibrillated tape into the artificial turf fiber.

15. The method of claim 14, wherein at least 30% by weight of the mixture is made of the polymer, the polymer being a hydrocarbon that combusts into CO2 and water.

16. The method of claim 14, the creation of the mixture further comprising: intermixing a second flame retardant in the mixture, the second flame retardant being a reducing agent; and/or intermixing a third flame retardant in the mixture, the third flame retardant being a HALS light stabilizer.

17. The method of claim 14, the mixture being extruded into the monofilament, the method further comprising: quenching the monofilament; reheating the monofilament; stretching the reheated monofilament; forming the monofilament into an artificial turf fiber; the mixture being extruded into the film, the method further comprising: transforming the film into a fibrillated tape; forming the fibrillated tape into the artificial turf fiber; the method further comprising incorporating the artificial turf fiber into an artificial turf backing.

18. A silage film, a tent tarpaulin, truck tarpaulin, boat cover, sunscreen or synthetic hybrid turf fiber comprising or consisting of a polymer material, the polymer material comprising a first flame retardant, the first flame retardant being a salt having a positive enthalpy of solution in water.

19. A method of producing a sheet-like or filamentary polymer material, the method, the method comprising: creating a mixture, the creation comprising mixing a polymer and a first flame retardant, the first flame retardant being a salt having a positive enthalpy of solution in water; and extruding the mixture into a polymer film or into a monofilament.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In the following, embodiments of the invention are explained in greater detail, by way of example only, making reference to the drawings in which:

[0057] FIG. 1 shows a flowchart which illustrates an example of a method of manufacturing a hardly inflammable polymer material; and

[0058] FIG. 2 shows a corresponding polymer mixture comprising three different flame retardants.

DETAILED DESCRIPTION

[0059] 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.

[0060] FIG. 1 shows a flowchart which illustrates an example of a method of manufacturing artificial turf. In several steps 102, 104, 106, a polymer mixture such as depicted in FIG. 2 is created. The method will be described by making reference to the generated polymer mixture depicted in FIG. 2.

[0061] First in step 102 a first flame retardant 202, a salt having a positive enthalpy of solution in water, e.g., KI, is added to one or more polymers 208. The polymer 208 can be a single-type polymer or a polymer comprising additives or a blend of multiple different polymers, e.g., a blend of LLDPE and HDPE. In the example depicted in FIG. 2, the polymer fraction 208 of the mixture 200 is an emulsion of droplets 210 of a stabilizing polymer within a bulk polymer 212. Optionally, the polymer fraction 208 can comprise a compatibilizer (not shown). In some instances the stabilizing polymer 210 may be immiscible in the bulk polymer 212 ,and therefore the stabilizing polymer droplets are surrounded by the compatibilizer. According to embodiments, the stabilizing polymer is a polar polymer, e.g., polyamide, and the bulk polymer is an non-polar polymer, e.g., PE. According to some embodiments, the polymer fraction 208 in addition comprises fibers of aramid (not shown). In other examples there may be additional polymers in the polymer phase 208 that are also immiscible with the bulk polymer 212. There also may be additional compatibilizers which are used either in combination with the stabilizing polymer 210 or the additional third, fourth, or fifth polymer. The stabilizing polymer forms polymer beads (or droplets) 210 surrounded by the compatibilizer. The polymer beads may also be formed by additional polymers which are not miscible in the bulk polymer. The polymer beads are also surrounded by the compatibilizer and are within the bulk polymer or mixed into the bulk polymer.

[0062] In the next step 104, a second flame retardant, a reducing agent, e.g., elementary tungsten 204, is added to the mixture 200.

[0063] In the next step 106, a third flame retardant, a HALS light stabilizer 206, is added to the mixture 200. The order of adding the flame retardants 204, 206, 202 to the mixture is irrelevant, so all flame retardants can be mixed with the polymer fraction 208 simultaneously or in a different order than described above.

[0064] In addition, pigments and/or further additives can be added to the mixture. The mixture is then thoroughly stirred and mixed to achieve a homogeneous distribution of all components of the mixture. The mixing is typically performed at high temperatures to ensure that all polymers 210, 212 are in liquid phase and can be homogeneously mixed, whereby the emulsion of the stabilizing polymer in the bulk polymer is maintained.

[0065] In the next step 108, the mixture 200 is extruded into a monofilament or a film. 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 can be 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.

[0066] 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.

[0067] 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.

[0068] Finally, the stretched monofilament is formed into the artificial turf fiber that may be tufted or otherwise integrated in a backing to form the artificial turf.

[0069] The integration of the fiber could be, but is not limited to, tufting or weaving the artificial turf fiber into an artificial turf backing. Then the artificial turf fibers are bound to the artificial turf backing. For instance, the artificial turf fibers may be glued or held in place by a coating or other material.

[0070] 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.

[0071] According to some embodiments, the stabilizing polymer is aramid. The polymer aramid has very good structural and temporal temperature stability. Aramid is a polar molecule. Some variants of aramid are also known by the trade name of Kevlar.

[0072] According to embodiments, further flame retardants are added to the polymer mixture 200, e.g., triazine and/or melamine. Both triazine and melamine are non-polar molecules. Triazine and melamine are therefore immiscible with the bulk polymer. In the case of fire, the triazine and melamine combination forms an intumescence layer on the surface of a monofilament which extinguishes the fire. The combination of the first, second and/or third flame retardants with said additional flame retardants and/or with the flame retardant stabilizing polymer aramid increases the fire resistance of fibers formed from the polymer mixture. This is because the aramid has extremely good thermal stability and even if the bulk polymer is melting or burning, the aramid will retain its shape and prevent any fibers from deforming or losing their shape and melting completely. The intumescence layer covers the surface of any artificial turf fibers or monofilaments and thus if the monofilament or fibers used to make the artificial turf melt, then the intumescence layer is less effective in stopping a fire. The stabilizing polymer therefore increases the effectiveness of the intumescence layer in stopping a fire. The first, second and/or third flame retardants reduce the temperature, thereby reducing the availability of polymers in the gas phase, and reduce the oxygen concentration in the air, thereby preventing any fire from spreading.

[0073] 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.

[0074] 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.

[0075] In one embodiment, the polymer bulk by weight comprises more second polymer than first polymer.

[0076] 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.

[0077] 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 aramid fibers but also stretches the polymer beads into thread-like regions which may also aid in changing the structure of the monofilament.

[0078] 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.

[0079] FIG. 2 shows a mixture 200 comprising 12% potassium iodide 202 as the first flame retardant, 10% elementary tungsten 204 as the second flame retardant, and 10% HALS light stabilizer as the third flame retardant. The rest, about 68% per weight of the mixture 200, consists of a polymer component 208 which may comprise some further additives, e.g., pigments, fungicides, and the like. In the depicted example, the polymer fraction is an emulsion of a polar stabilizing polymer 210, e.g., aramid or PA, in an non-polar bulk polymer, e.g., PE.

[0080] Various methods and standards exist for testing and quantifying the flame retardant properties of a particular material. For example, ASTM D635 specifies a standard test method for the rate of burning and/or the extent and time of burning of plastics in a horizontal position. ASTM D3801 specifies a standard test method for measuring the comparative burning characteristics of solid plastics in a vertical position.

[0081] Testing the flame retardant properties of materials allows comparing the rate of burning or extent and time of burning characteristics, or both, of different materials, e.g. for the purpose of controlling manufacturing processes, or as a measure of deterioration or change in these burning characteristics prior to or during use. In general, it is recommended to compare test data only for specimens of similar thickness because the rate of burning and other burning phenomena will vary with thickness. Burning tests typically require that further variables are also fixed, for example, energy source and application time. Some tests comprise determining the relative linear rate of burning or extent and time of burning, or both, of plastics in the form of bars, molded or cut from sheets, plates, or panels. Thereby, the tested materials may be oriented in horizontal or vertical position depending on the respective test.

LIST OF REFERENCE NUMERALS

[0082] 102-108 steps [0083] 200 polymer mixture [0084] 202 first flame retardant [0085] 204 second flame retardant [0086] 206 third flame retardant [0087] 208 polymer portion of the polymer mixture [0088] 210 stabilizer polymer