Artificial turf and production method

Abstract

The method includes creating a polymer mixture, wherein the polymer mixture includes a stabilizing polymer, a bulk polymer, a flame retardant polymer combination, and a compatibilizer. The stabilizing polymer and the bulk polymer are immiscible. The stabilizing polymer includes fibers surrounded by the compatibilizer within the bulk polymer. The stabilizing polymer is aramid. The flame retardant polymer combination is a mixture of triazin and melamine. The method further includes extruding the polymer mixture into a monofilament. The method further includes quenching the monofilament. The method further includes reheating the monofilament. The method further includes stretching the reheated monofilament to align the fibers relative to each other and to form the monofilament into an artificial turf fiber. The method further includes incorporating the artificial turf fiber into an artificial turf backing.

Claims

1. A method of manufacturing artificial turf, the method comprising: creating a polymer mixture, wherein the polymer mixture comprises a stabilizing polymer, a bulk polymer comprising a first polymer, a second polymer and a compatibilizer, and a flame retardant polymer combination, wherein the stabilizing polymer and the bulk polymer are immiscible, wherein the stabilizing polymer comprises fibers surrounded by the compatibilizer within the bulk polymer, wherein the stabilizing polymer is aramid, wherein the flame retardant polymer combination is a mixture of triazine and melamine, and wherein the first polymer, the second polymer and the stabilizing polymer are immiscible, wherein the first polymer forms polymer beads surrounded by the compatibilizer within the second polymer; extruding the polymer mixture into a monofilament; quenching the monofilament; reheating the monofilament; stretching the reheated monofilament to align the fibers relative to each other and to form the monofilament into an artificial turf fiber; and incorporating the artificial turf fiber into an artificial turf backing, wherein creating the polymer mixture comprises mixing the stabilizing polymer surrounded by the compatibilizer with the bulk polymer.

2. The method of claim 1, wherein the polymer mixture comprises any one of the following: less than or equal to 8% stabilizing polymer by weight, less than or equal to 10% stabilizing polymer by weight, less than or equal to 12% stabilizing polymer by weight, or less than or equal to 15% stabilizing polymer by weight.

3. The method of claim 1, wherein the polymer mixture comprises any one of the following: less than or equal to 20% flame retardant polymer combination by weight, less than or equal to 22% flame retardant polymer combination by weight, less than or equal to 25% flame retardant polymer combination by weight, less than or equal to 27% flame retardant polymer combination by weight, or less than or equal to 29% flame retardant polymer combination by weight.

4. The method of claim 1, wherein the ratio of triazine to melamine by weight in the flame retardant polymer combination is any one of the following: 1.8, 1.9, 2.0, 2.1, or 2.2.

5. The method of claim 1, wherein stretching the reheated monofilament deforms the polymer beads into threadlike regions having a diameter of less than 20 micrometer.

6. The method of claim 1, wherein the creating of the bulk polymer comprises: forming a first mixture by mixing the first polymer with the compatibilizer; heating the first mixture; extruding the first mixture; granulating the extruded first mixture; mixing the granulated first mixture with the second polymer; and heating the granulated first mixture with the second polymer to form the polymer mixture.

7. The method of claim 1, wherein the bulk polymer comprises any one of the following: 1 to 30 percent by weight the first polymer, 1 to 20 percent by weight the first polymer, or 5 to 10 percent by weight the first polymer.

8. The method of claim 1, wherein the first polymer is any one of the following: a polar polymer, a polyethylene terephthalate (PET) polymer, a polybutylene terephthalate (PBT) polymer, a polyolefin polymer, a thermoplastic polyolefin polymer, a polyethylene polymer, a polypropylene polymer, a polyamide polymer, a polyethylene polymer blend, or mixtures thereof.

9. The method of claim 1, wherein the second polymer is any one of the following: a non-polar polymer, polyethylene, polypropylene, or a mixture thereof.

10. The method of claim 1, wherein the compatibilizer is any one of the following: a maleic acid grafted on polyethylene or polyamide; a maleic anhydride grafted on free radical initiated graft copolymer of polyethylene, SEES, EVA, EPD, or polypropylene with an unsaturated acid or its anhydride such as maleic acid, glycidyl methacrylate, ricinoloxazoline maleinate; a graft copolymer of SEBS with glycidyl methacrylate, a graft copolymer of EVA with mercaptoacetic acid and maleic anhydride; a graft copolymer of EPDM with maleic anhydride; a graft copolymer of polypropylene with maleic anhydride; a polyolefin-graft-polyamidepolyethylene or polyamide; or a polyacrylic acid type compatibilizer.

11. The method of claim 1, wherein the bulk polymer comprises 80 to 90 percent by weight the second polymer.

12. The method of claim 1, wherein the polymer mixture further comprises any one of the following: a wax, a dulling agent, a UV stabilizer, a flame retardant, an anti-oxidant, a pigment, or any combination thereof.

13. The method of claim 1, wherein the aramid is para-aramid.

14. The method of claim 13, wherein the para-aramid has a fiber length less than any one of the following: 135 μm, 125 μm, or 115 μm.

15. The method of claim 13, wherein the para-aramid has an average fiber length of any one of the following: between 65 μm and 35 μm, or 55 μm.

16. The method of claim 13, wherein the para-aramid has a density between any one of the following: 1.44 g/cm.sup.3 and 1.45 g/cm.sup.3, or 1.43 g/cm3 and 1.46 g/cm3.

17. The method of claim 13, wherein the para-aramid has a decomposition temperature of any one of the following: above 720 degrees, above 725 degrees, or 723 degrees Kelvin.

18. The method of claim 1, wherein creating the polymer mixture comprises: forming an initial mixture by mixing the stabilizing polymer with the compatibilizer; heating the initial mixture; extruding the initial mixture; granulating the extruded initial mixture; mixing the granulated initial mixture with the bulk polymer and the flame-retardant polymer combination; and heating the granulated initial mixture with the bulk polymer and the flame-retardant polymer combination to form the polymer mixture.

19. A method of manufacturing artificial turf, the method comprising: creating a polymer mixture, wherein the polymer mixture comprises a stabilizing polymer, a bulk polymer comprising a first polymer, a second polymer and a compatibilizer, and a flame retardant polymer combination, wherein the stabilizing polymer and the bulk polymer are immiscible, wherein the stabilizing polymer comprises fibers surrounded by the compatibilizer within the bulk polymer, wherein the stabilizing polymer is aramid, wherein the flame retardant polymer combination is a mixture of triazine and melamine, wherein the first polymer, the second polymer and the stabilizing polymer are immiscible, and wherein the first polymer forms polymer beads surrounded by the compatibilizer within the second polymer; extruding the polymer mixture into a monofilament; quenching the monofilament; reheating the monofilament; stretching the reheated monofilament to align the fibers relative to each other and to form the monofilament into an artificial turf fiber; and incorporating the artificial turf fiber into an artificial turf backing, wherein creating the polymer mixture comprises: forming a master batch including a first granulate of the bulk polymer, the stabilizing polymer and the compatibilizer; extruding a mixture of the first polymer and the compatibilizer for forming strands; and crushing the strands for forming a second granulate, wherein the first granulate and the second granulate form the polymer mixture.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following embodiments of the invention are explained in greater detail, by way of example only; making reference to the drawings in which:

(2) FIG. 1 shows a flowchart which illustrates an example of a method of manufacturing artificial turf;

(3) FIG. 2 shows a flowchart which illustrates one method of creating the polymer mixture;

(4) FIG. 3 shows a flowchart which illustrates a further example of how to create a polymer mixture;

(5) FIG. 4 shows a diagram which illustrates a cross-section of a polymer mixture;

(6) FIG. 5 shows a diagram which illustrates a cross-section of a further example of polymer mixture;

(7) FIG. 6 shows a diagram which illustrates a cross-section of a further example of polymer mixture;

(8) FIG. 7 illustrates the extrusion of the polymer mixture of FIG. 4 into a monofilament;

(9) FIG. 8 shows a cross-section of a small segment of the monofilament of FIG. 7;

(10) FIG. 9 illustrates the effect of stretching the monofilament of FIG. 8;

(11) FIG. 10 illustrates the extrusion of the polymer mixture of FIG. 5 or 6 into a monofilament;

(12) FIG. 11 shows a cross-section of a small segment of the monofilament of FIG. 10;

(13) FIG. 12 illustrates the effect of stretching the monofilament of FIG. 11;

(14) FIG. 13 shows an electron microscope picture of a cross-section of a stretched monofilament; and

(15) FIG. 14 shows an example of a cross-section of an example of artificial turf.

DETAILED DESCRIPTION

(16) 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.

(17) FIG. 1 shows a flowchart which illustrates an example of a method of manufacturing artificial turf. First in step 100 a polymer mixture is created. The polymer mixture comprises a bulk polymer, a stabilizing polymer, a flame retardant polymer combination, and a compatiblizer. In some instances the bulk polymer may be made of multiple components. The stabilizing polymer is immiscible in the bulk polymer, and therefore the stabilizing polymer is surrounded by the compatibilizer. The stabilizing polymer is formed from fibers of aramid.

(18) In some examples, the bulk polymer comprises a first polymer. The bulk polymer further comprises a second polymer and a compatibilizer. The first polymer and the second polymer are immiscible. In other examples there may be additional polymers such as a third, fourth, or even fifth polymer that are also immiscible with the second polymer. There also may be additional compatibilizers which are used either in combination with the first polymer or the additional third, fourth, or fifth polymer. The first polymer forms polymer beads surrounded by the compatibilizer. The polymer beads may also be formed by additional polymers which are not miscible in the second polymer. The polymer beads are also surrounded by the compatibilizer and are within the second polymer or mixed into the second polymer.

(19) In the next step 102 the bulk polymer is extruded into a monofilament. Next in step 104 the monofilament is quenched or rapidly cooled down. Next in step 106 the monofilament is reheated. In step 108 the reheated monofilament is stretched this causes the fibers of the stabilizing polymer to become aligned with each other which is in the direction that the fibers are stretched. If the bulk polymer comprises the polymer beads, the stretching deforms the polymer beads into thread-like regions and to form the monofilament into the artificial turf fiber.

(20) 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 110 the artificial turf fiber is incorporated into an artificial turf backing. Step 110 could for example be, but is not limited to, tufting or weaving the artificial turf fiber into the artificial turf backing. Then in step 112 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. Step 112 is an optional step. For example if the artificial turf fibers are woven into the artificial turf backing step 112 may not need to be performed.

(21) FIG. 2 shows a flowchart which illustrates one method of creating the bulk polymer. In this example the bulk polymer comprises the first polymer, a second polymer, and the compatibilizer. The bulk polymer may also comprise other things such as additives to color or provide flame or UV-resistance or improve the flowing properties of the bulk polymer. First in step 200 a first mixture is formed by mixing the first polymer with the compatibilizer. Additional additives may also be added during this step. Next in step 202 the first mixture is heated. Next in step 204 the first mixture is extruded. Then in step 206 the extruded first mixture is then granulated or chopped into small pieces. Next in step 208 the granulated first mixture is mixed with the second polymer. Additional additives may also be added to the bulk polymer at this time. Finally in step 210 the granulated first mixture is heated with the second polymer to form the bulk polymer. The heating and mixing may occur at the same time. The bulk polymer can be fabricated separately and then later added together to the stabilizing polymer and more compatibilizer, or the bulk polymer can be fabricated at the same time as the polymer mixture.

(22) FIG. 3 shows a flowchart which illustrates an example of how to create a bulk polymer 100. In this example the bulk polymer additionally comprises at least a third polymer. The third polymer is immiscible with The third polymer further forms the polymer beads surrounded by the compatibilizer with the second polymer. First in step 300 a first mixture is formed by mixing the first polymer and the third polymer with the compatibilizer. Additional additives may be added to the first mixture at this point. Next in step 302 the first mixture is heated. The heating and the mixing of the first mixture may be done at the same time. Next in step 304 the first mixture is extruded. Next in step 306 the extruded first mixture is granulated or chopped into tiny pieces. Next in step 308 the first mixture is mixed with the second polymer. Additional additives may be added to the bulk polymer at this time. Then finally in step 310 the heated first mixture and the second polymer are heated to form the bulk polymer. The heating and the mixing may be done simultaneously. The bulk polymer can be fabricated separately and then later added together to the stabilizing polymer and more compatibilizer, or the bulk polymer can be fabricated at the same time as the polymer mixture.

(23) FIG. 4 shows a diagram which illustrates a cross-section of a polymer mixture 400. The polymer mixture comprises a number of stabilizing polymer 402. These are shown as being in the form of aramid fibers. The bulk of the polymer mixture 400 is shown as being the bulk polymer 404. Each of the stabilizing polymer 402 fibers is surrounded by a compatibilizer 406. This enables the stabilizing polymer 402 to be mixed with the bulk polymer 404. The flame-retardant polymer is not shown but may be considered to be mixed into the bulk polymer 404.

(24) FIG. 5 shows a further example of a cross-section of a polymer mixture 500. In this example the bulk polymer is made up of two different polymers. It is made up of a non-polar second polymer 504 and a polar first polymer 502. There is less of the first polymer 502 than the second polymer 504. The first polymer 502 is shown as also being surrounded by the compatibilizer 406 so that it is able to be mixed into the second polymer 504. The first polymer 502 surrounded by the compatibilizer 406 forms a number of polymer beads 508. The polymer beads 508 may be spherical or oval in shape or they may also be irregularly-shaped depending up on how well the polymer mixture is mixed and the temperature. The compatibilizer 406 separates the first polymer 402 from the second polymer 406.

(25) FIG. 6 shows a further cross-section of an additional polymer mixture. The polymer mixture 600 in FIG. 6 has a bulk polymer which is made up of the second polymer 504 and the first polymer 502 as shown in FIG. 5 but in addition there is a third polymer 602 which is also immiscible with the second polymer 504. The third polymer 602 is also shown as being surrounded by the compatibilizer 406 so that it can be mixed with the second polymer 504. Some of the polymer beads 508 are now comprised of the third polymer 602.

(26) In this example the same compatibilizer 506 is used for both the first polymer 502 and the third polymer 602. In other examples a different compatibilizer 506 could be used for the first polymer 502 and the third polymer 602.

(27) FIG. 7 illustrates the extrusion of the polymer mixture 400 into a monofilament. Shown is an amount of bulk polymer 404. Within the polymer mixture 400 there is a large number of fibers 402 of the stabilizing polymer. A screw, piston or other device is used to force the polymer mixture 400 through a hole 704 in a plate 702. This causes the polymer mixture 400 to be extruded into a monofilament 706. The monofilament 706 is shown as containing the fibers 402 also. The fibers 402 may tend to concentrate in the center of the monofilament 706. This may lead to desirable properties for the final artificial turf fiber as this may lead to a concentration of the thread-like regions in the core region of the monofilament 706,

(28) FIG. 8 shows a cross-section of a small segment of the monofilament 706. The monofilament is again shown as comprising the bulk polymer 404 with the fibers 402 mixed in. The fibers 402 are separated from the bulk polymer 404 by compatibilizer which is not shown. To form the thread-like structures a section of the monofilament 706 is heated and then stretched along the length of the monofilament 706. This is illustrated by the arrows 800 which show the direction of the stretching.

(29) FIG. 9 illustrates the effect of stretching the monofilament 706. In FIG. 8 an example of a cross-section of a stretched monofilament 706 is shown. The fibers 402 in FIG. 8 have been aligned with each other or in the direction of the stretching 800.

(30) FIG. 10 shows a Fig. that is similar to that of FIG. 7 except in FIG. 10 the polymer mixture 500 of FIG. 5 or the polymer mixture 600 of FIG. 6 is used in place of the polymer mixture 400. The polymer mixture can be seen as containing the polymer beads 508 and the stabilizing polymer 402 fibers mixed into the second polymer 504. The polymer mixture 500 or 600 is extruded in the same way into the monofilament 706.

(31) Shown is an amount of 500 or 600. Within the bulk polymer 500 or 600 there is a large number of polymer beads 508. The polymer beads 508 may be made of one or more polymers that is not miscible with the second polymer 504 and is also separated from the second polymer 504 by a compatibilizer, which is not shown. A screw, piston or other device is used to force the bulk polymer 500 or 600 through a hole 704 in a plate 702. This causes the 500 or 600 to be extruded into a monofilament 706. The monofilament 706 is shown as containing polymer beads 508 also in addition to the fibers 402. The second polymer 504, the fibers 402, and the polymer beads 508 are extruded together. In some examples the second polymer 504 will be less viscous than the polymer beads 508 and the polymer beads 508 will tend to concentrate in the center of the monofilament 706. This may lead to desirable properties for the final artificial turf fiber as this may lead to a concentration of the thread-like regions in the core region of the monofilament 706.

(32) FIG. 11 is similar to FIG. 8 except the monofilament 706 of FIG. 10 is used instead. The monofilament 706 is shown before being stretched in the direction 800. The fibers of the stabilizing polymer 402 are shown as being in more or less random directions and the polymer beads 508 are oddly-shaped and have not yet been formed into the threadlike structures. To form the thread-like structures a section of the monofilament 706 is heated and then stretched along the length of the monofilament 706. This is illustrated by the arrows 800 which show the direction of the stretching.

(33) FIG. 12 shows the monofilament 706′ after it has been stretched in the direction 800 illustrated in FIG. 11. The stretching motion causes the fibers of the stabilizing polymer 402 to roughly align with the stretching direction 800 and also the polymer beads 508 of FIG. 11 have been stretched into threadlike structures 1200. FIG. 12 illustrates the effect of stretching the monofilament 606. In FIG. 8 an example of a cross-section of a stretched monofilament 606 is shown. The polymer beads 408 in FIG. 7 have been stretched into thread-like structures 1200. The amount of deformation of the polymer beads 408 would be dependent upon how much the monofilament 706′ has been stretched.

(34) Examples may relate to the production of artificial turf which is also referred to as synthetic turf. In particular, the invention relates to the production of fibers that imitate grass. The fibers are composed of first and second polymers that are not miscible and differ in material characteristics as e.g. stiffness, density, polarity and a compatibilizer.

(35) In a first step for manufacturing the bulk polymer, a first polymer is mixed with the a compatibilizer. Color pigments, UV and thermal stabilizers, process aids and other substances that are as such known from the art can be added to the mixture.

(36) In a second step for manufacturing the bulk polymer, the second polymer is added to the mixture whereby in this example the quantity of the second polymer is about 80-90 mass of the bulk polymer or the polymer mixture, the quantities of the first polymer being 5% to 10% by mass and of the compatibilizer being 5% to 10% by mass. Using extrusion technology results in a mixture of droplets or of beads of the first polymer surrounded by the compatibilizer that is dispersed in the polymer matrix of the second polymer.

(37) In a practical implementation a so called master batch including granulate of the bulk polymer, the stabilizing polymer, and the compatibilizer is formed. The master batch may also be referred to as a “polymer mixture” herein. The granulate mix is melted and a mixture of the first polymer and the compatibilizer is formed by extrusion. The resulting strands are crushed into granulate. The resultant granulate and granulate is then used in a second extrusion to produce the thick fiber which is then stretched into the final fiber.

(38) The melt temperature used during extrusions is dependent upon the type of polymers and compatibilizer that is used. However the melt temperature is typically between 230° C. and 280° C.

(39) A monofilament, which can also be referred to as a filament or fibrillated tape, is produced by feeding the mixture into an fiber producing extrusion line. The melt mixture is passing the extrusion tool, i.e., a spinneret plate or a wide slot nozzle, forming the melt flow into a filament or tape form, is quenched or cooled in a water spin bath, dried and stretched by passing rotating heated godets with different rotational speed and/or a heating oven.

(40) The monofilament or type is then annealed online in a second step passing a further heating oven and/or set of heated godets.

(41) By this procedure the beads or droplets of polymer 1, surrounded by the compatibilizer are stretched into longitudinal direction and form small fiber like, linear structures which stay however completely embedded into the polymer matrix of the second polymer.

(42) FIG. 13 shows a microscopic picture of a cross-section 1300 of a stretched monofilament to illustrate the thread like structures. The fibers of the stabilizing polymer are not shown. The horizontal white streaks within the stretched monofilament 706 are the thread-like structures 1200. Several of these thread-like structures are labeled 1200. The thread-like structures 1200 can be shown as forming small linear structures of the first polymer within the second polymer.

(43) The resultant fiber that contains the thread like structures may have multiple advantages, namely softness combined with durability and long term elasticity. In case of different stiffness and bending properties of the polymers the fiber can show a better resilience (this means that once a fiber is stepped down it will spring back) In case of a stiff first polymer, the small linear fiber structures built in the polymer matrix are providing a polymer reinforcement of the fiber.

(44) Delimitation due to the composite formed by the first and second polymers is prevented due to the fact that the short fibers of the second polymer are embedded in the matrix given by the first polymer. The same is true for the fibers of the stabilizing polymer. Moreover, complicated coextrusion, requiring several extrusion heads to feed one complex spinneret tool is not needed.

(45) The first polymer can be a polar substance, such as polyimide, whereas the second polymer can be a non-polar polymer, such as polyethylene. Alternatives for the first polymer are polyethylene terephthalate (PET) or polybutylene terephthalate (PBT) for the second polymer polypropylene. Finally a material consisting of 3 polymers is possible (e.g. PET, PA and PP, with PP creating the matrix and the other creating independent from each other fibrous linear structures. The compatibilizer can be a maleic anhydride grafted on polyethylene or polyamide.

(46) FIG. 14 shows an example of a cross-section of an example of artificial turf 1400. The artificial turf 1400 comprises an artificial turf backing 1402. Artificial turf fiber 1404 has been tufted into the artificial turf backing 1402. On the bottom of the artificial turf backing 1402 is shown a coating 1406. The coating may serve to bind or secure the artificial turf fiber 1404 to the artificial turf backing 1402. The coating 1406 may be optional. For example the artificial turf fibers 1404 may be alternatively woven into the artificial turf backing 1402. Various types of glues, coatings or adhesives could be used for the coating 1406. The artificial turf fibers 1404 are shown as extending a distance 1408 above the artificial turf backing 1402. The distance 1008 is essentially the height of the pile of the artificial turf fibers 1404. In some examples, the length of the thread-like regions within the artificial turf fibers 1404 is half of the distance 1408 or less.

LIST OF REFERENCE NUMERALS

(47) 100 create a bulk polymer 102 extrude the bulk polymer into a monofilament 104 quench the monofilament 106 reheat the monofilament 108 stretch the reheated monofilament 110 incorporate the artificial turf fiber into an artificial turf carpet 112 optionally bind the artificial turf fibers to the artificial turf carpet 200 form a first mixture by mixing the first polymer with the compatibilizer 202 heat the first mixture 204 extrude the first mixture 206 granulate the extruded first mixture 208 mix the granulated first mixture with the second polymer 210 heat the granulated first mixture with the second polymer to form the bulk polymer 300 form a first mixture by mixing the first polymer and the third polymer with the compatibilizer 302 heat the first mixture 304 extrude the first mixture 306 granulate the extruded first mixture 308 mix the first mixture with the second polymer 310 heat the mixed first mixture with the second polymer to form the bulk polymer 400 polymer mixture 402 stabilizing polymer 404 bulk polymer 406 compatibilizer 500 polymer mixture 502 first polymer 504 second polymer 406 compafibilizer 508 polymer bead 600 polymer mixture 602 third polymer 700 bulk polymer 702 plate 704 hole 706 monofilament 706′ stretched monofilament 800 direction of stretching 1200 threadlike structures 1400 artificial turf 1402 artificial turf carpet 1404 artificial turf fiber (pile) 1406 coating 1408 height of pile