Artificial turf incorporating a hybrid backing for improved dimensional stability

Abstract

An artificial turf incorporates a backing with low thermal expansion and therefore provides an artificial turf that does not buckle or wrinkle when exposed to high temperatures. The backing is a woven tapes instead of yarns and these tapes are more dimensionally stable than yarns or multifilament yarns that can more easily slip and slide over each other and warp or wrinkle. The tapes form a high contact area between them and the flat planar surfaces of the tapes and makes them less likely to slide or move due to temperature changes. The backing may include polyester (PET) weft tapes and lower cost polypropylene (PP) warp tapes.

Description

ARTIFICIAL TURF INCORPORATING A HYBRID BACKING FOR IMPROVEDDIMENSIONAL STABILITYCross Reference to Related Applications

[0001] This application claims the benefit of priority to U.S. Provisional patent application No. 63 / 594,137, filed on October 30, 2023; the entirety of which is hereby incorporated by reference herein.BACKGROUND OF THE INVENTIONField of the Invention

[0002] The invention relates to an artificial turf with a hybrid backing for improved dimensional stability by reduction in thermal expansion.Background

[0003] Artificial turf includes a tufted backing material, a backing material with the turf fibers tufted thereto to make the turf. The tufted fibers simulate the grass or turf, and the backing material gives the rolled-good stability. Artificial turf may be exposed to the elements and wide temperature ranges from well below freezing such as 23°C (10°F) to very hot, such as 50°C (122°F). The artificial turf may thermally expand when heated and this may cause buckling or wrinkles in the field of play that can be dangerous for the athletes. The turf may be secured to a ground surface and thermal expansion between these anchored locations can result in a loose turf that slides and wrinkles.

[0004] Temperature differences during installation can greatly impact the dimension of the artificial turf and may result in the turf being too tight or too loose upon changes in the temperatures after installation. Certainly, if the turf rolls are installed in the winter when the temperatures are cold versus during a hot summer afternoon, the dimension of the turf may be greatly different. This may make it difficult for proper installation and maintaining straight and proper tensioned turf on the field.

[0005] After the artificial turf is positioned on a ground surface, a fill is spread over the turf, such as sand or small particles which help to hold down the artificial turf and provides some additional softness and traction.SUMMARY OF THE INVENTION

[0006] The invention is directed to an artificial turf having a backing that has low thermal expansion and therefore provides an artificial turf that does not buckle or wrinkle when exposed to high temperatures. An exemplary backing may incorporate tapes instead of yarns and these tapes when woven into a backing may be more dimensionally stable than yams or multifilament yams that can more easily slip and slide over each other and warp or wrinkle. An exemplary backing made of woven tapes has higher contact area of the warp tapes and weft tapes than a yam backing and therefor the warp and weft tapes are less likely to slide or move due to temperature changes. An exemplary backing may include or consist of polymer tapes that are woven together to form a woven backing that can then be tufted to couple the turf strands thereto. The backing may include two different polymer tapes in the warp and weft directions to provide suitable strength for tufting and effectively low thermal expansion to prevent wrinkling. A first polymer tape may be made of a first polymer that has a melt temperature that is at least 10°C different from the melting temperature of a second tape. One of the warp or weft tapes may be a polyester (PET) tape, such as recycled polyester (rPET) tape. The other tape may be a polypropylene tape. In an exemplary embodiment, the artificial turf includes PET tapes as only one of the warp or weft tapes and it may be more desirable to include weft PET tapes and lower cost polypropylene (PP) warp tapes. A backing made with both PET warp tapes and PET weft tapes may be cost prohibitive for turf applications.

[0007] An exemplary hybrid backing incorporates flat extruded tapes, woven in x-y, “warp” and “weft” direction, with polypropylene tapes woven in the warp (machine direction) and polyester tape woven in the weft (width or cross-direction) to improve turf stability during installation. Polyester is not typically used in backing applications due to the increased difficulty of extruding PET tapes.

[0008] An exemplary backing was made using a weave of polypropylene warp tape with a polyester weft tape. The dimensions and weight of the warp tape and weft tape are provided in Table 1 .Table 1

[0009] The ratio of the coverage area of the weft tape to the warp tape in the backing may be 1 :1 or more, such about 1 .10:1 .0 or more, about 1 .20:1 or more, about 1 .30 or more. The weft tape has a width of 2.1 , so the ratio when the pick count (picks / 10cm) of the weft and warp tapes are 72 and 110 respectively, the ratio of coverage area of the weft tape to the warp tape is 1 .37:1 .0. This ratio of about 1 :1 to about 1 .5:1 or less may be effective for providing effective strength for processing while also providing effectively low thermal shrinkage. The polyester weft tapes may have less thermal shrinkage than the polypropylene warp tapes due to a higher melting temperature. The backing made of planar thin tapes with a width at least 10 times and preferably 20 times the thickness provides increased surface area between he warp and weft tapes in the weave. This increased surface area over a multifilament yarn greatly improves dimensionally stability. Yams, and multifilament yarns in particular, have a round cross-section versus rectangular and are easily deformable due to the filaments being able to move with respect to each other. An exemplary backing incorporating tapes and preferably consisting of rectangular cross-section tapes with a width that is at least 10 times a thickness may be more dimensionally stable than yams or multifilament yams. The tapes may be monofilament polymeric or polymer tapes meaning that they consist of a single film of polymer tape, such as an extrusion or slit film of polymer.

[0010] The tapes of the backing may have the properties as detailed in Table 2. The tensile properties were measured according to EN ISO 2062-2010. The tenacity in cn / dtex and elongation are reported in Table 2. A Testrite Shrinkage Tester, model Mk?? (Testrite Ltd., West Yorkshire, England) was used for the shrinkage tests. This test conforms with ASTM D5591 and also conforms to EN 13844.Table 2*130°C for PP **190°C for PET

[0011] The tenacity for each of the warp and weft tapes was greater than 3.5cN / dtex with an elongation of 30% or less. The thermal shrinkage of each of the warp and weft tapes (PP and PET tapes), was less than 5% or about 4% or less.

[0012] The polypropylene warp tape was UV-stabilized, however the polyester tape, a recycled PET weft tape was not UV-stabilized. It is well known however that polyester has a higher UV-stability than polypropylene

[0013] The fabric made from these woven tapes may have effectively high tensile properties and effectively low thermal shrinkage to prevent buckling and distortion of the turf due to temperature changes. Table 3 provides mechanical modulus of the backing in the warp and weft directions and also the thermal shrinkage according toTable 3

[0014] The weft pick count was changed from 60 in Example 1 to 64 in Example 2 and 72 in Example 3, while maintaining the pick count of the warp tape to 110. The tensile strength of the backing was greater than 900N / 5cm (force per 5cm) in the warp direction and greater than 450N / 5cm in the weft direction for each of the Examples. The warp direction was about twice the strength of the weft direction and this may be important for processing including the tufting process and for maintaining dimensional stability. The elongation was less than 30% in the warp direction and less than 20%, or less than 15% in the weft direction for each of the Examples. The Testrite shrinkage test yielded less than 4% shrinkage in both the warp and weft andless than 2% and actually less than 1 .5% in the weft direction, a very low amount of shrinkage. An exemplary backing may have a tensile strength according to EN ISO 13934-1-2013 of more than 900N / 5cm in the warp direction and greater than 400N / 5cm or 450N / 5cm in the weft direction while having an elongation of less than 30 in each of the warp and weft directions. The areal weight of Example 1 was 107g / m2, Example 2 110g / m2and Example 3, 118g / m2. The areal weight of a backing may be about 80g / m2to about 130g / m2or preferably from about 90g / m2to about 120g / m2.

[0015] An exemplary hybrid artificial turf may further include a foam coupled to the backing layer, opposite the turf side of the hybrid artificial turf and this foam may aid thermal dimensional stability of the hybrid artificial turf. The foam layer may be bonded to the warp tapes and / or the weft tapes and may therefore provide resistance to any movement of these tapes with respect to other tapes in the backing. The foam may be bonded or attached to the backing by melting to one or more of the warp and weft tapes. In an exemplary embodiment, the foam is only bonded to the polyester weft tapes, such as by melt lamination. The foam may have a skin layer on an attached side and / or an exposed side and this skin layer(s) may further improve the dimensional stability of the foam and hybrid artificial turf.

[0016] A foam layer may also ensure that the fill remains between the foam and the turf, or tufted fibers which may further aid keeping the hybrid artificial turf flat and dimensionally stable. The fill particles will effectively fill in voids between the backing tapes and may prevent the warp tapes and weft tapes from moving with respect to each other. Also, the weight of the fill resting on the foam may more effectively hold down the hybrid artificial turf versus fill that can fall through the backing layer.

[0017] The foam may bond to only one of the warp tapes or weft tapes or to only tapes made of polyester and not to the polypropylene. In an exemplary embodiment, the warp tapes are made of PP and the weft tapes are made of PET and the foam is bonded only to the PET weft tapes. The bond may be a thermal bond wherein heat and an effective amount of pressure is applied to bond the foam to the tape.

[0018] A foam may be a synthetic foam, such as polyurethane and may have a thickness of about 5mm or from about 2mm to about 10mm. The foam may be a synthetic foam, such as a polyurethane foam and may have a durometer of about 30 shore OO or more to about 40 shore A. The foam may have a skin layer, a thin filmlayer on the surface and this skin layer may be on the backing side and ground side of the foam.

[0019] The warp tape, which may be a polypropylene tape may have a dtex value or weight in grams per 10,000 linear meters (dtex) of about 300 or more, about 400 or more, about 450 or more, about 500 or more, or about 550 or less or any range between and including the dtex values provided, such as from about 300dtex to about 550dtex. The warp tape may be rectangular in shape having a width of about 0.5mm or more, about 0.75mm or more, about 1mm or more, about 1 ,25mm or more, about 1 ,5mm or more and any range between and including the width values provided. The thickness of the warp tape may be about 25pm or more, about 50 pm or more, about 75 pm or more, about 100 pm or more or any range between and including the thickness values provided.

[0020] The weft tape, which may be a polyester (PET) tape may have a dtex value or weight in grams per 10,000 linear meters (dtex) of about 700 or more, about 800 or more, about 900 or more, about 1 ,000 or more, about 1 ,100 or more, or about 1 ,200 or less or any range between and including the dtex values provided, such as from about 700dtex to about 1 ,200dtex. Note that the weft tape may be heavier than the warp tape by a factor of about 1 .5 or more, about 1 .75 or more, about 2.0 or more, about 2.5 or more, or even about 3.0 or more or any range between and including the ratios provided. In an exemplary embodiment, the warp tape has about a 500dtex and the weft tape has about a 1 ,000dtex value, or about 2.0 ratio to the warp tape. The weft tape may be rectangular in shape having a width of about 1 .0mm or more, about 1 ,5mm or more, about 1 ,75mm or more, about 2.0mm or more, about 2.5mm or more, about 3.0mm or less and any range between and including the width values provided, such as from about 1 ,0mm to about 3.0mm.

[0021] Again, the width of the weft tape may be wider than the width of the warp tape by a ratio of about 1.5 or more, about 2.0 or more, about 2.5 or more or even 3.0 or more. In an exemplary embodiment, the warp tape has a width of about 1 ,0mm and the weft tape has a width of about 2.0mm, a ratio of 2.0:1 . The thickness of the weft tape may be about 20pm or more, about 30pm or more, about 40pm or more, about 50pm or more or any range between and including the thickness values provided. The thickness of the weft tape may be less than the thickness of the warp tape. In an exemplary embodiment, the warp tape has a thickness of about 48pm and the weft tape has a thickness of about 32pm.

[0022] A blend of polypropylene and polyester as the tapes in the backing may be important for processing as a backing made only of PET tapes may become too brittle for the tufting process. An example was made with both the warp and weft tapes made of PET and it did not perform well during tufting and became ripped.

[0023] The polyester tapes (warp and / or weft) may have a higher melting temperature than the polypropylene tapes (warp and / or weft), wherein the melt temperature of polypropylene is typically about 160°C to 170°C and the melt temperature of polyester is typically about 220°C or more, such as around 240°C or higher, or even about 250°C. The polyester used to make the warp tape or weft tape may be a recycled polyester.

[0024] The warp tapes and weft tapes may be in a woven configured in the backing with a pick rate or number of tapes per unit length of 10cm. The pick rate may be about 40 or more, about 50 or more, about 60 or more, about 70 or more, about 80 or more or any range between and including the pick rates provided such as from about 40 to 80 and preferably from about 50 to 70.

[0025] As shown in Table 2, three different backing Examples were made to form a hybrid backing with polypropylene warp tapes and rPET weft tapes.Table 2

[0026] As shown in Table 2, the pick count for the PP warp tape was 110 / 10cm and the pick count for the rPET weft tape ranged from 60 / 10cm to 72 / 10cm. The areal weight varied from 107g / m2 to 118g / m2.

[0027] The warp tapes may have a higher modulus than the weft tapes and this difference in stiffness may aid in manufacturing. The stronger and stiffer warp tapes may enable less stretch in the machine direction which may be required for effective tufting of the turf. The weft tape, the PET tape may have a lower modulus and therefore, the weft tapes may be larger in cross-sectional area, wider as describedherein than the warp tapes, to provide effective strength for processing including the tufting process and for dimensional stability.

[0028] A tape, as used herein, is made of single film of polymer and has a width that is at least 10 times greater than a thickness and may have a rectangular shape.

[0029] The foam may bond through melt lamination to the polyester tapes as opposed to the polypropylene tapes. The chemistry of the polyester may be more suitable for bonding to the foam during melting.

[0030] A tape, warp or weft tape may be made of polyester, polyethylene, polypropylene, polystyrene, polyamide and / or nylon, or a combination thereof.

[0031] The summary of the invention is provided as a general introduction to some of the embodiments of the invention and is not intended to be limiting. Additional example embodiments including variations and alternative configurations of the invention are provided herein.BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0032] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.

[0033] Figure 1 shows a perspective view of a hybrid artificial turf having a backing that includes warp tapes and weft tapes woven together and having a foam layer bonded thereto on a foam side and turfed strands extending from a turf side of the backing.

[0034] Figure 2 shows perspective views of a warp tape and weft tape for comparison of the thickness and width.

[0035] Figure 3 shows a side cross-sectional view of a hybrid artificial turf.

[0036] Figure 4 shows a perspective view of a foam layer having a backing side and an exposed side.

[0037] Corresponding reference characters indicate corresponding parts throughout the several views of the figures. The figures represent an illustration of some of the embodiments of the present invention and are not to be construed as limiting the scope of the invention in any manner. Some of the figures may not show all of the features and components of the invention for ease of illustration, but it is to beunderstood that where possible, features and components from one figure may be included in the other figures. Further, the figures are not necessarily to scale, some features may be exaggerated to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to employ the present invention.DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0038] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Also, use of "a" or "an" are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

[0039] Certain exemplary embodiments of the present invention are described herein and are illustrated in the accompanying figures. The embodiments described are only for purposes of illustrating the present invention and should not be interpreted as limiting the scope of the invention. Other embodiments of the invention, and certain modifications, combinations and improvements of the described embodiments, will occur to those skilled in the art and all such alternate embodiments, combinations, modifications, improvements are within the scope of the present invention.

[0040] As shown in FIG. 1 a hybrid artificial turf 10 has a backing 20 that includes warp tapes 30 and weft tapes 40 woven together and a foam layer 50 bonded thereto on a foam side 25 and turfed strands 60 extending from a turf side 26 of the backing. The warp direction 13 and weft direction 14 are indicated by the bold arrows. The backing 20 has backing apertures 23, the space between the warp tapes 30 and weft tapes 40. As described herein, a filler may rest in these backingapertures and further stabilize the backing and the hybrid artificial turf from dimensional changes, such as due to thermal expansion.

[0041] As shown in FIG. 2, a weft tape 40 is wider than the warp tape 30. The width 43 of the weft tape may be about double the width 33 of the warp tape. The thickness 48 of the weft tape may be less than the thickness 38 of the warp tape, as shown and as described herein.

[0042] As shown in FIG. 3, the turf strand 60 have a connected end 66 and extend from the backing 20 to an extended end 65. The turf stands may be configured in a strand bundle 61 as shown in FIG. 1.

[0043] As shown in FIG. 4, a foam layer 50 has a thickness 58 from a backing side 57 to a ground side 59 which may be about 2mm to about 10mm, such as about 10mm or less, about 8mm or less or about 6mm or less and any range between and including the thickness values provided. The backing side 57 is bonded to the backing and may have a skin layer 52, a film layer which may solid thin film layer. The ground side 59 is configured for placement on a ground surface or ground and may also have a skin layer 52’. The foam layer 50 has porosity or pores 54 that reduces the density of the foam and provides resilience when compressed.

[0044] It will be apparent to those skilled in the art that various modifications, combinations and variations can be made in the present invention without departing from the scope of the invention. Specific embodiments, features and elements described herein may be modified, and / or combined in any suitable manner. Thus, it is intended that the present invention cover the modifications, combinations and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:1 . A hybrid artificial turf comprising: a) a backing comprising: i) a foam side; ii) a turf side; iii) warp tapes extending in a warp direction across the backing; wherein the warp tape is a first polymer; iv) weft tapes extending in a weft direction across the backing; wherein the weft tape is a second polymer, different from said first polymer; b) turf strands coupled to the backing and extending from said turf side of the backing to an extended end; c) a foam coupled to the foam side of the backing.

2. The hybrid artificial turf of claim 1 , wherein the first polymer is polypropylene.

3. The hybrid artificial turf of claim 2, wherein the first polymer is polyester.

4. The hybrid artificial turf of claim 3, wherein the polyester is recycled polyester.

5. The hybrid artificial turf of claim 3, wherein the melt temperature of the first polymer is at least 10C different than the melt temperature of the second polymer.

6. The hybrid artificial turf of claim 5, wherein the foam is melt laminated to the backing.

7. The hybrid artificial turf of claim 6, wherein the foam is melt laminated to the second polymer.

8. The hybrid artificial turf of claim 6, wherein the foam is melt laminated to only the second polymer.

9. The hybrid artificial turf of claim 3, wherein a ratio of the coverage area of the weft tape to the warp tape in the backing between 1 :1 to 1 .5:1 .

10. The hybrid artificial turf of claim 9, wherein a dtex ratio between the weft tape and the warp tape is 1 .5: 1 or more.11 . The hybrid artificial turf of claim 9, wherein a dtex ratio between the weft tape and the warp tape is 2.0:1 or more.

12. The hybrid artificial turf of claim 9, wherein the weft tape has a width that is at least 1.5 times a width of the warp tape.

13. The hybrid artificial turf of claim 9, wherein the weft tape has a width that is at least 2.0 times a width of the warp tape.

14. The hybrid artificial turf of claim 9, wherein a shrinkage percentage of the warp tape and the weft tape according to Testrite test method is less than 4%.

15. The hybrid artificial turf of claim 1 , wherein the weft tape has a width that is at least 1.5 times a width of the warp tape.

16. The hybrid artificial turf of claim 1 , wherein the weft tape has a width that is at least 2.0 times a width of the warp tape.

17. The hybrid artificial turf of claim 1 , wherein a shrinkage percentage of the warp tape according to Testrite test method is less than 4%.

18. The hybrid artificial turf of claim 1 , wherein a shrinkage percentage of the weft tape according to Testrite test method is less than 4%.

19. The hybrid artificial turf of claim 1 , wherein a dtex ratio of between the weft tape and the warp tape is 1 .5: 1 or more.

20. The hybrid artificial turf of claim 1 , wherein a dtex ratio of between the weft tape and the warp tape is 2.0:1 or more.21 .The hybrid artificial turf of claim 1 , wherein the foam is a polyurethane foam.

22. The hybrid artificial turf of claim 1 , wherein the backing has a tensile strength in the warp direction of more than 900N / 5m according to test method EN ISO 113934-1-2013.

23. The hybrid artificial turf of claim 22, wherein the backing has a tensile strength in the weft direction of more than 450N / 5m according to test method EN ISO 113934-1-2013.

24. The hybrid artificial turf of claim 23, wherein the elongation for the backing in both the warp and weft is less than 30% according to test method EN ISO 113934-1- 2013.

25. The hybrid artificial turf of any one of claims 1 to 24, wherein the backing consists of warp tapes and weft tape each having a rectangular cross section with a width that is at least 10 times greater than a thickness and is made from a monofilament of polymer.

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