Filler Granules for Artificial Turf Systems

Abstract

An artificial turf system comprising an artificial turf layer comprising a substrate and pile fibres upstanding from the substrate, and an infill layer disposed on the substrate and interspersed among the pile fibres. The infill layer comprises granules comprising at least 60% by weight of polybutylene adipate terephthalate (PBAT) and a pigment or a pigment masterbatch. The pigment may be dark in colour, such as dark green. One or more filler materials or additives such as additional polymers may also be used. The granules are compostable and have high flexibility. The granules may be shaped, for example, as cylindrical granules. The new infill has passed the highest performance and quality test by FIFA (FIFA Quality Pro) and is particularly useful as an infill for artificial football turf. The excellent properties correlate with the high pliability and softness of the material, reducing the need for infill (<8.5 kg / m 2 ). The spent granules can be further recycled towards a circular chemical economy without any harmful impact on the environment.

Description

[Technical Field]

[0001] The present invention relates to granules for use in artificial turf systems, and to artificial turf systems using such granules. [Background technology]

[0002] Artificial turf systems have been around for a long time and have evolved through several generations to their current form. In general, such systems have sought to achieve the same properties as their natural counterparts, but in certain areas may already have surpassed these properties, at least in terms of predictability of behavior.

[0003] Currently, a typical turf system comprises a backing layer having a top surface and an infill layer of soft granules disposed between the fibers. The backing layer may consist of a woven fabric in which artificial turf fibers are tufted to provide pile fibers oriented in an upward position and secured to the woven fabric by a latex or polyurethane backing layer. Installation of the turf system typically involves providing a layer of sand spread between the upright turf fibers, the weight of which holds the backing in place and supports the pile in an upward position. Granules are spread over this sand layer and between the artificial turf fibers to form a loose performance infill layer that provides the required sports performance. These performance characteristics vary depending on the intended use, but for most sports they include: rotational and linear grip; force reduction; vertical ball bounce; and rolling friction. This performance can be further supported by applying an impact padding layer directly beneath the backing layer.

[0004] Even though such artificial turf has now been proven to have properties equal to or even better than natural turf, the plastic materials used in such turf are environmentally problematic: they disperse and decompose into microplastics, causing environmental pollution.

[0005] Previously known artificial turf systems are known, for example, from U.S. Pat. No. 10,844,553, WO 2006 / 092337, WO 2006 / 025973, U.S. Patent Application No. 2008 / 0145574, U.S. Patent Application No. 2020 / 0224374 and U.S. Patent Application No. 2015 / 0191879.

[0006] However, there remains a need for environmentally friendly solutions for use in artificial turf that have properties equal to or better than natural turf and are environmentally friendly. Summary of the Invention [Problem to be solved by the invention]

[0007] It is therefore an object of the present invention to provide an artificial turf system and granules for use therein that alleviates all or at least some of the above-mentioned drawbacks of currently known systems.

[0008] These objects are achieved by an artificial turf system, and granules for use in such a system, as defined in the appended claims.

[0009] According to a first aspect of the present invention, there is provided an artificial turf system comprising an artificial turf layer comprising a substrate and pile fibers upstanding from the substrate, and an infill layer disposed on the substrate and interspersed between the pile fibers, wherein the infill layer comprises granules, the granules comprising at least 60% by weight of polybutylene adipate terephthalate (PBAT) and a pigment or pigment masterbatch.

[0010] According to another aspect of the present invention, there is provided granules for use as infill in an artificial turf system, the granules comprising at least 60% by weight of polybutylene adipate terephthalate (PBAT) and a pigment or pigment masterbatch.

[0011] The present invention addresses the environmental issue of persistent microplastic release from infill materials dispersed on artificial turf systems. Compared to conventional infill materials, the infill material of the present invention requires relatively small amounts of infill, which, combined with its biodegradable properties, prevents the release of persistent and harmful microplastics into the environment. Due to its high flexibility, this new infill, when combined with an appropriate artificial turf system, provides an ideal playing surface for a wide range of outdoor and indoor sports, including soccer, paddle, lacrosse, basketball, and field activities.

[0012] PBAT is fully compostable and highly flexible, making it sustainable. It has also been shown to perform extremely well as an infill material dispersed on artificial turf systems, providing an ideal playing surface for a variety of outdoor and indoor applications, including football. PBAT-based granules can be used to provide artificial turf systems with a fully compostable and highly flexible infill material. The new granules are highly flexible and can be made from fully compostable plastic. They can be molded into cylindrical granules, making them ideal for applications such as infill for artificial turf. The granules reduce the release of long-lived microplastics into the surrounding environment and nearby waterways. This new infill material has passed FIFA's highest performance and quality test (FIFA Quality Pro), making it particularly useful as an infill material for football artificial turf. These excellent properties correlate with the material's high flexibility and softness, reducing the need for infill (<8.5 kg / m). 2 ). The used granules can be further recycled towards a circular chemical economy without any harmful impact on the environment.

[0013] The pigment forms a protective surface around the granules, protecting them from UV rays and thus extending the product's lifespan when used as an outdoor filler. The pigment is preferably a dark pigment, such as one with a dark green color. The pigment may be provided in the form of a pigment masterbatch. Here, masterbatch refers to a solid or liquid additive for plastics that contains a concentrated mixture of pigment encapsulated in a carrier, such as a resin made of polymer or wax. The masterbatch may contain 20 to 65% by weight of pigment.

[0014] The granules preferably comprise at least 70% by weight, preferably at least 80% by weight, and most preferably at least 90% by weight of PBAT, hi some embodiments, the PBAT content may be at least 95% by weight, or even at least 97% by weight.

[0015] PBAT is itself a well-known thermoplastic polymer and is known to be a tough copolyester with high flexibility.

[0016] The PBAT is preferably fossil-based or partially bio-based. Preferably, the PBAT is at least partially bio-based, i.e., a bio-PBAT.

[0017] The diameter of the granules is preferably in the range of 0.1 to 5 mm, preferably 0.5 to 5 mm, more preferably 1 to 5 mm, preferably 1.5 to 4 mm, and most preferably 1.5 to 3.5 mm, and the length is in the range of 1 to 15 mm, preferably 1.5 to 10 mm, and most preferably 1.5 to 5 mm. Thus, the average diameter of the granules is 2.5 mm ± 1.0 mm, and the length can vary between 1 and 15 mm. Lengths of less than 1 mm, such as down to 0.5 mm or even 0.1 mm, are also possible. Thus, the length can be in the range of 0.1 to 15 mm, 0.5 to 15 mm, 0.1 to 5 mm, 0.5 to 5 mm, 0.5 to 4 mm, etc.

[0018] The above-mentioned diameter and length can be used for cylindrical granules with a circular cross section. However, the same preferred diameter and length dimensions also apply to granules that form cylinders with non-circular cross sections and granules that are not cylindrical. Therefore, the diameter of a non-circular cross section is broadly interpreted and also includes the average cross-sectional dimension of a non-circular shape. The diameter of such a non-circular shape can be calculated, for example, based on the perimeter of the non-circular shape, and thus the diameter d can be calculated as d=p / π.

[0019] In a preferred embodiment, the granules are in the form of a cylinder. The cylinder has a uniform cross section along its entire length. In one embodiment, the cross section is circular, providing a cylinder. However, other cross-sectional shapes can be used, such as triangular, square, rectangular, and other polygonal shapes. The cross-sectional shape can also be oval, or other more complex shapes, such as star, crystal, three-leaf, or four-leaf clover.

[0020] In some embodiments, the granules may be formed into other three-dimensional shapes besides cylinders, such as discs, spheres, etc.

[0021] In some embodiments, the granules may be ellipsoidal in shape. An ellipsoid has three pairs of perpendicular symmetry axes that intersect at the center of symmetry, i.e., the center of the ellipsoid. The line segments that are separated on the symmetry axes of an ellipsoid are sometimes called major axes, or simply axes of the ellipsoid.

[0022] The granules may have the shape of an ellipsoid with three axes having different lengths, whereby the ellipsoid may be called a triaxial ellipsoid, the axes being uniquely defined.

[0023] The granules may have the shape of an ellipsoid, with two axes of equal length and a third axis of a different length. In this case, the ellipsoid is sometimes called a spheroid, i.e., a biaxial ellipsoid or spheroid. In this case, the ellipsoid is invariant to rotation about the third axis.

[0024] The third axis may be shorter than the other two, causing the ellipsoid to form an oblate ellipsoid, which can be viewed as an ellipse rotated about its minor axis, forming a flattened spheroid with a lentil-like shape.

[0025] Alternatively, the third axis can be longer than the other two, causing the ellipsoid to form a prolate spheroid, which can be viewed as an ellipse rotated about its major axis, forming the shape of an American football or rugby ball.

[0026] The three axes can also be of equal length, causing the ellipsoid to form a sphere.

[0027] The Shore D hardness of the granules is preferably 44 or less, preferably in the range of 25-44, more preferably 32-42, and most preferably 34-40.

[0028] In a preferred embodiment, the dark pigment is a dark green pigment.

[0029] The granules preferably have a flexural strength measured according to ISO 178:2019 in the range of 2 to 17 MPa, preferably 3 to 8 MPa, most preferably 4 to 6 MPa.

[0030] The granules preferably have a flexural modulus measured according to ISO 178:2019 of 50 to 250 MPa, preferably 55 to 150 MPa, most preferably 60 to 90 MPa.

[0031] The granules preferably have an offset elongation (0.2%) measured according to ISO 178:2019 of 1 to 10 MPa, preferably 2 to 7 MPa, most preferably 3 to 6 MPa.

[0032] The granules may contain PBAT as the only polymer component. However, the granules may also contain a mixture of PBAT with one or more other thermoplastic polymers. In that case, the polymer portion of the mixture, excluding possible fillers, preferably contains at least 70% by weight of PBAT and no more than 30% by weight of other thermoplastic polymers. In other words, if other thermoplastic polymers are contained in the mixture in addition to PBAT, the total amount of these other thermoplastic polymers is preferably less than half the amount of PBAT.

[0033] The granules may further comprise 1 to 30% by weight of another compostable polymer, preferably at least one of polyethylene furanoate (PEF), polyhydroxyalkanoate (PHA), polylactic acid (PLA), polybutylene succinate (PBS), poly(butylene succinate-co-butylene adipate) (PBSA), polycaprolactone (PCL), thermoplastic starch (TPS), and starch, or a combination thereof. Such materials can be included in the mixture to adjust the hardness, flexibility, and other properties of the material.

[0034] The granules may contain 1 to 30% by weight of another bio-based polymer, preferably at least one of PLA, polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polyamide 11 (PA11), polyamide 1010 (PA1010), bio-polyethylene (Bio-PE), bio-polypropylene (Bio-PP), bio-polyvinyl carbonate (Bio-PVC), bio-polyethylene terephthalate (Bio-PET), and bio-polybutadiene (Bio-PBU), or a combination thereof. "Bio" here indicates that the material is derived from a living organism. Such materials may be added to make the granules more environmentally attractive.

[0035] The granules may further comprise a filler material, which may include at least one of chalk, talc, kaolin, wood fiber, bast fiber, lignocellulose, cellulose, hemicellulose, lignin, flax, and hemp, and combinations thereof. Such fillers may be added to improve other properties of the material or to facilitate other conditions and requirements. Fillers such as chalk may be added, for example, to reduce cost, increase specific gravity, or adjust other properties of the granules.

[0036] The total amount of filler material is preferably less than 40% by weight, and in some embodiments, may be less than 30%, 20%, 10%, or 5% by weight. In some embodiments, no filler material may be used. However, in other embodiments, the amount of filler material may be at least 1%, at least 5%, at least 10%, at least 20%, or at least 30% by weight. Thus, the amount of filler material may range from 0 to 40% by weight, preferably from 1 to 40% by weight, such as from 1 to 30%, 1 to 20%, or 1 to 10% by weight.

[0037] Regardless of whether the granules are formed solely from PBAT and pigment / pigment masterbatch, or whether other ingredients are added, such as other thermoplastic polymers, filler materials, etc., the materials are preferably mixed to form a homogeneous material. The granules are preferably made entirely of homogeneous material.

[0038] To produce granules, the materials are mixed into a masterbatch. They are then extruded to form strands that can be cut into granules using, for example, a strand pelletizer. In the strand pelletization process, the strands are fed from the extruder die into a cooling water bath, then cut and dried in a pelletizer. The result is smooth, greenish-gray extruded granules with a cylindrical shape, an average diameter of 2.5 mm ± 1.0 mm, and lengths that vary between 1.0 and 15 mm.

[0039] Non-cylindrical shapes can be produced in a similar manner, for example by using an underwater pelletizing process in an underwater pelletizer.

[0040] After use, the granules are fully compostable. In particular, preliminary tests have shown that the granules described above meet the disintegration requirements specified in the standard ISO 20200 (disintegration test).

[0041] The granules can also be recycled by collecting them, separating them from the dust, washing, drying and reprocessing them to increase biological sustainability.

[0042] The artificial turf system may further include a resilient layer including a shock pad structure below the substrate, and an additional particle layer between the shock pad structure and the infill layer. The additional particle layer may include at least one type of particles selected from the group consisting of sand, sandstone, rubber, cork, wood, elastomer, and plastic particles, or a combination thereof. In a preferred embodiment, the additional particle layer includes sand.

[0043] These and other features and advantages of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. [Brief explanation of the drawings]

[0044] The invention will now be described in more detail, by way of example only, with reference to embodiments illustrated in the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic diagram of granules for use as infill for artificial turf according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an artificial turf according to one embodiment of the present invention. [Figure 3a-g] 3a-g are schematic illustrations of cylindrical granules having other geometric shapes according to other embodiments of the present invention. [Figure 4a-d] 4a-d are schematic illustrations of non-cylindrical granules having other geometric shapes according to other embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0045] In the following detailed description, preferred embodiments of the present invention will be described. However, it should be understood that, unless otherwise specified, the features of different embodiments are interchangeable between the embodiments and can be combined in different ways. In the following description, many specific details are set forth to provide a more complete understanding of the present invention, but it will be apparent to those skilled in the art that the present invention can be practiced without these specific details. In some cases, well-known structures or functions are not described in detail to avoid obscuring the present invention.

[0046] An embodiment of a granule for use as infill in an artificial turf system is shown schematically in Figure 1. Here, the granule has a cylindrical shape with a circular cross section, i.e., a cylindrical shape. The diameter can be in the range of 0.1 to 5 mm, preferably 0.5 to 5 mm, more preferably 1 to 5 mm, more preferably 1 to 4 mm, and most preferably 1.5 to 3.5 mm, and the length can be in the range of 1 to 15 mm, preferably 1 to 10 mm, and most preferably 1 to 5 mm.

[0047] The above-mentioned diameters and lengths can be used not only for non-cylindrical granules, but also for granules having a cylindrical shape with a non-circular cross section, as exemplified in more detail below. In such cases, the diameter of the non-circular cross section relates to the average cross-sectional dimension. The diameter of such a non-circular shape can be calculated, for example, based on the perimeter of the non-circular shape, whereby the diameter d can be calculated as d = p / π.

[0048] However, the granules may have other cylindrical shapes with other cross sections. Such alternative shapes are shown schematically in Figures 3a-i. For example, a cylinder may have a crystalline cross section as shown in Figure 3a. Here, the crystalline shape is generally two overlapping squares rotated 45 degrees relative to each other. However, other crystalline shapes are also possible. The cross section may be triangular as shown in Figure 3b, square as shown in Figure 3d, or rectangular as shown in Figure 3e. However, other polygonal shapes, such as a star, are also possible, as shown in Figure 3c. Here, the star has five radiating points, but it may have fewer radiating points, such as three or four, or more radiating points, such as six or seven. The polygon may have relatively sharp corners, as in the example of Figure 3d, or rounded corners, as in the example of Figure 3e. The cross-sectional shape may be elliptical, or more complex, such as a three- or four-leaf clover, as shown in Figure 3f.

[0049] A cylinder may have a length greater than its diameter, as in the illustrative example of Figure 1. However, a cylinder may have a diameter that is essentially the same as its length. A cylinder may have a diameter greater than its length, as in the illustrative example of Figure 3g.

[0050] In some embodiments, the granules may be formed into other three-dimensional shapes besides a cylindrical shape, such as in the form of spheres as shown schematically in Figure 4a, or in the form of disks as shown schematically in Figure 4b, etc. The disk shape here is generally a flat cylinder but with a curved convex base.

[0051] In some embodiments, the granules may be ellipsoidal in shape. An ellipsoid has three pairs of perpendicular symmetry axes that intersect at the center of symmetry, i.e., the center of the ellipsoid. The line segments that are separated on the symmetry axes of an ellipsoid are sometimes called major axes, or simply axes of the ellipsoid.

[0052] The granules may have the shape of an ellipsoid with three axes having different lengths, whereby the ellipsoid may be called a triaxial ellipsoid, the axes being uniquely defined.

[0053] As shown in Figures 4c and 4d, the granule may have the shape of an ellipsoid, with two axes x and y having the same length a and a third axis z having a different length c. In this case, the ellipsoid may be called a spheroid, i.e., a biaxial ellipsoid or spheroid. In this case, the ellipsoid is invariant to rotation about the third axis.

[0054] The third axis, z, or length c, may be shorter than the other two axes, or radius a, so that the ellipsoid forms an oblate ellipsoid, as shown in Figure 4c. An oblate ellipsoid can be viewed as an ellipse with its minor axis rotated inversely, forming a flattened spheroid with a lentil-like shape. Here, the length of the granule is c, and the diameter is 2*a, where c <aである。

[0055] Alternatively, the third axis z, i.e., length c, can be longer than the other two axes, i.e., radius a, so that the ellipsoid forms a prolate ellipsoid, as shown in Figure 4d. A prolate ellipsoid can be viewed as an ellipse rotated about its major axis, forming the shape of an American football or rugby ball. Here, the length of the granule is c and the diameter is 2*a, where c>a.

[0056] The three axes can also be of equal length, causing the ellipsoid to form a sphere, as in the illustrative example of Figure 4a.

[0057] The aforementioned shapes, particularly the cylindrical and spheroidal shapes, provide granules that reach a compacted structure immediately after placement as an infill layer in an artificial turf system. This compacted structure is reached immediately after introduction and is stable for a long time, as it cannot be further compacted. However, the particles are loose enough to move under the influence of forces. This creates a compacted layer structure that is characteristic of natural turf.

[0058] The granules can be used as infill material in an artificial turf system. Such an artificial turf system is shown diagrammatically in FIG. 2. Here, the artificial turf system includes an artificial turf layer including a substrate 21 and pile fibers 22 upstanding from the substrate. The substrate 21 functions as a backing sheet and may include a sheet of plastic material, such as a nonwoven fabric, impregnated with an exemplary latex, such as SBR latex. A large number of upstanding fibers 22 extend upward from the upper surface of the substrate. The length of the fibers is selected depending on the depth of the infill material and the desired resilience of the finished artificial turf structure. The depth of the infill layer is shallower than the length of the fibers. The length of the fibers is, for example, less than 50 mm. Preferably, the length of the fibers is less than 45 mm.

[0059] The fibers may be synthetic fibers made of polyethylene, polypropylene or nylon. The fibers may be, for example, monofilament or multifilament, although mixtures of multifilament and monofilament fibers may also be used. The thickness of the fibers may vary. However, it is also possible to mix thick and thin fibers. The general criteria for producing backing sheets and fibers are known in the art and do not require a detailed description.

[0060] The packed bed 25 containing the above-mentioned granules is placed on the substrate 21. The packed bed 25 has a density of 5 to 12 kg / m 2 , preferably 6 to 10 kg / m 2 , most preferably 7 to 8.5 kg / m 2 range, for example, about 8 kg / m 2 or approximately 8.5 kg / m 2 The weight of the packed bed is preferably 8.5 kg / m 2 is less than.

[0061] The infill layer can be deep enough to adequately support the pile fibers over a significant portion of their length, depending on the length of these fibers and the desired free pile. In preferred embodiments, the infill layer has a depth of at least 10 mm. In other embodiments, the infill layer may be at least 20 mm deep, or even greater than 30 mm deep. It will be understood that the final depth will also depend on whether the infill layer is the only layer on the substrate supporting the pile fibers and whether impact padding or other forms of resilient layer are applied. In preferred embodiments, the infill layer has a depth in the range of 10 to 25 mm, preferably 15 to 20 mm, e.g., about 17 mm. Depending on the nature of the sport, the pile fibers may extend at least 10 mm, or at least 15 mm, or even 20 mm or more from the level of the infill material.

[0062] The system may also include one or more additional particle layers disposed on the substrate below the infill layer. The additional particle layers may have various functions including shock absorption, pile stabilization, drainage, filler, etc., and may be selected from the group including sand, sandstone, rubber particles, elastomeric particles, thermoplastic particles, and other particles that do not meet the definition of infill granules. As an illustrative example, the additional particle layer 24 includes sand, such as silica sand.

[0063] Here, the additional particle layer 24, which is sand, has a density of 10 to 20 kg / m 2 , or preferably 12 to 17 kg / m 2 , for example, about 15 kg / m 2 The additional particle layer may have a depth of 5 to 15 mm, for example about 10 mm.

[0064] Beneath the substrate 21 may be provided an elastic layer 23 including a shock pad structure. The shock pad may be formed, for example, from PE closed cell foam. The shock pad may have a thickness in the range of 8-15 mm, preferably 10-13 mm, for example 12 mm, and may have a resistance of 25-75 kg / m 3 , e.g., 50 kg / m 3 The density may be

[0065] The granules are preferably formed from a homogeneous material comprising at least 60% by weight of polybutylene adipate terephthalate (PBAT) and a pigment or pigment masterbatch. The pigment is preferably a dark pigment, such as a dark green pigment. The pigment protects the granules from degradation by ultraviolet light and also increases the heat absorption of the granules.

[0066] The granules preferably contain at least 70% by weight, preferably at least 80% by weight, and most preferably at least 90% by weight of PBAT. In some embodiments, the PBAT content may be at least 95% by weight, or even at least 97% by weight.

[0067] PBAT may be fossil-based, but is preferably at least partially bio-based, and in some embodiments may be solely bio-based, ie, bio-PBAT.

[0068] The granules may contain PBAT as the only polymeric component. However, the granules may also contain a mixture of PBAT and one or more other thermoplastic polymers. In this case, the polymer portion of the mixture, excluding possible fillers, preferably contains at least 70% by weight of PBAT and no more than 30% by weight of the other thermoplastic polymers. In other words, if other thermoplastic polymers are included in the mixture in addition to PBAT, the total amount of these other thermoplastic polymers is preferably less than half the amount of PBAT. For example, the granules may contain 1 to 30% by weight of another compostable polymer, preferably at least one of polyethylene furanoate (PEF), polyhydroxyalkanoate (PHA), polylactic acid (PLA), polybutylene succinate (PBS), poly(butylene succinate-co-butylene adipate) (PBSA), polycaprolactone (PCL), thermoplastic starch (TPS), and starch, or a combination thereof. Such materials can be included in the mixture to adjust the hardness, flexibility, and other properties of the material. Additionally or alternatively, the granules may contain 1-30 wt. % of another bio-based polymer, preferably at least one of PLA, polyhydroxyalkanoate (PHA), polyhydroxybutyric acid (PHB), polyamide 11 (PA11), polyamide 1010 (PA1010), bio-polyethylene (Bio-PE), bio-polypropylene (Bio-PP), bio-polyvinyl carbonate (Bio-PVC), bio-polyethylene terephthalate (Bio-PET) and bio-polybutadiene (Bio-PBU), or a combination thereof.

[0069] The granules may further comprise a filler material, which may include at least one of chalk, wood fiber, lignocellulose, cellulose, hemicellulose, lignin, bast fiber, flax, and hemp, and combinations thereof. The total amount of filler material is preferably less than 40% by weight, and in some embodiments may be less than 30%, 20%, 10%, or 5% by weight. In some embodiments, no filler material may be used. However, in other embodiments, the amount of filler material may be at least 1%, at least 5%, at least 10%, at least 20%, or at least 30% by weight. Thus, the amount of filler material may be in the range of 0 to 40% by weight, preferably in the range of 1 to 40% by weight, for example, in the range of 1 to 30%, 1 to 20%, or 1 to 10% by weight.

[0070] To produce granules, the materials are mixed into a masterbatch. They are then extruded to form strands, which can be cut into granules using, for example, a strand pelletizer. In this process, the strands are fed from the extruder die into a cooling water bath, then cut and dried in a pelletizer. The result is smooth, greenish-gray extruded granules with a cylindrical shape and an average diameter of 2.5 mm ± 1.0 mm, with lengths varying between 1.0 and 15 mm.

[0071] For the production of non-cylindrical shapes such as spheres and spheroids, die face cutter pelletizing can be used, where the melt is cut directly at the opening of a die before a cooling medium, usually air but more often water, transports the freshly cut granules, cooling them in the process. Underwater pelletizing can be used to form such granules.

[0072] After use, the granules are fully compostable. In particular, they are deemed to meet the disintegration requirements specified in the ISO 20200 standard (disintegration test).

[0073] It can also be recycled after use by collecting the granules, separating them from dust, washing, drying and reprocessing, thereby increasing biological sustainability. [Example]

[0074] A number of tests were conducted to evaluate the new granules. In these tests, granules containing over 90% by weight of PBAT were used in combination with a dark green pigment. The granules had a cylindrical shape with an average diameter of 2.5 mm ± 1 mm and a length of approximately 1 to 5 mm.

[0075] First, the hardness and bending properties of the granules were tested using standardized methods using 3 mm thin plastic plates made by pressing the granules together under high pressure at 200°C. The plates were then heat-conditioned at 23°C for 3 hours before testing. As discussed in US 10844553, compared to existing filler materials, such as polyethylene (PE), the new granules were significantly softer, with a Shore D hardness of 37 measured by a Bareiss Digitest apparatus according to ISO 48-4 on two layers of plastic plates.

[0076] It was concluded that the granules should preferably have a Shore D hardness of 44 or less, preferably in the range of 25-44, more preferably 32-42, and most preferably 34-40.

[0077] The flexural properties of the granules were measured using a Tinius Olsen H5ST instrument equipped with a three-point bending test fixture according to ISO 178:2019. Compared to the harder reference plastics (PP and PC), the new granules had a low flexural strength (5.2 MPa) and flexural modulus (75.7 MPa), similar to the flexible LDPE reference (see Table 1). Therefore, the flexural modulus of the new granules was in the low end range of semi-rigid plastics (70-700 MPa), compared to tests on the harder, less flexible reference materials (PP and PC), which ultimately reached the rigid region (>700 MPa).

[0078] [Table 1]

[0079] It was concluded that the new granules preferably have a flexural strength measured according to ISO 178:2019 in the range of 2-17 MPa, preferably 3-8 MPa, and most preferably 4-6 MPa.

[0080] It was further concluded that the granules preferably have a flexural modulus, measured according to ISO 178:2019, of 50 to 250 MPa, preferably 55 to 150 MPa, and most preferably 60 to 90 MPa.

[0081] It was further concluded that the granules preferably have an offset elongation (0.2%) measured according to ISO 178:2019 of 1 to 10 MPa, preferably 2 to 7 MPa, most preferably 3 to 5 MPa.

[0082] The density of the new granular material is 1.25g / cm 3 The melting point was measured to be 110°C, well above the application requirements.

[0083] Accelerated weathering tests conducted using an ATLAS Ci5000 Weather-Ometer instrument according to the SAE J1960 method showed no visible attack or color change in the exposed materials at various temperatures, relative humidity and UV light intensities.

[0084] Preliminary tests on the compostability of the new material were also carried out, which showed that the granules met the requirements for compostability according to ISO 20200.

[0085] The use of granules as infill material in artificial turf systems was also tested. Testing was carried out by SPORTS LABS according to the highest playing performance protocol (FIFA Quality Pro). 40mm monofilament turf was applied at 15kg / m².2 8 kg / m as filler to a depth of about 17 mm on a thin layer of silica sand equivalent to about 10 mm 2 The carpet was made of the above granules with a thickness of 12 mm and a density of 50 kg / m². 3 PE closed cell foam was used.

[0086] Excellent playing performance was observed in all tests in both dry and wet conditions, as shown in Table 2. The combination of the new granular infill, silica sand, carpet and impact pads has produced an artificial turf system that is highly suitable for both outdoor and indoor applications and fully meets the requirements of FIFA Quality Pro.

[0087] [Table 2]

[0088] Thus, the new granules were found to meet all of the requirements for both FIFA Quality and FIFA Quality Pro in both dry and wet conditions when used as an infill material in artificial turf systems.Without being bound by any theory, it is believed that these excellent results are at least in part due to the relatively low hardness and high elasticity, as evidenced by the measured flexural properties of the material.

[0089] The present invention has been described above with reference to specific embodiments. It should be noted that the above-described embodiments are illustrative rather than limiting of the present invention, and that those skilled in the art can design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the scope of the claims. The word "comprises" does not exclude the presence of other elements or steps than those stated in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

Claims

1. An artificial turf layer comprising a substrate and pile fibers standing upright from the substrate; a filler layer disposed on the substrate and interspersed among the pile fibers; An artificial turf system comprising: the packed bed comprises granules, the granules comprising at least 60 wt. % polybutylene adipate terephthalate (PBAT) and a pigment or pigment masterbatch; The artificial turf system, wherein the granules have a Shore D hardness of 44 or less, preferably in the range of 25 to 44, more preferably 32 to 42, and most preferably 34 to 40.

2. 2. The artificial turf system of claim 1, wherein the granules comprise at least 60% by weight, preferably at least 70% by weight, and most preferably at least 90% by weight of PBAT.

3. 3. The artificial turf system of claim 1 or 2, wherein the PBAT is fossil-based or partially bio-based.

4. 4. The artificial turf system according to any one of claims 1 to 3, wherein the granules have a diameter in the range of 0.1 to 5 mm, preferably 0.5 to 5 mm, more preferably 1 to 5 mm, more preferably 1.5 to 4 mm, and most preferably 1.5 to 3.5 mm, and a length in the range of 1 to 15 mm, preferably 1.5 to 10 mm, and most preferably 1.5 to 5 mm.

5. The artificial turf system of any one of claims 1 to 4, wherein the pigment is a dark green pigment.

6. 6. The artificial turf system according to any one of the preceding claims, wherein the flexural strength of the granules, measured according to ISO 178:2019, is in the range of 2 to 17 MPa, preferably 3 to 8 MPa, most preferably 4 to 6 MPa.

7. 7. The artificial turf system according to any one of the preceding claims, wherein the flexural modulus of the granules, measured according to ISO 178:2019, is between 50 and 250 MPa, preferably between 55 and 150 MPa, and most preferably between 60 and 90 MPa.

8. 8. The artificial turf system according to any one of claims 1 to 7, wherein the granules further comprise 1 to 30% by weight of another compostable polymer, preferably at least one of PEF, PHA, PLA, PBS, PBSA, PCL, TPS and starch, or a combination thereof.

9. 9. The artificial turf system of any one of claims 1 to 8, wherein the granules further comprise 1 to 30% by weight of another bio-based polymer, preferably at least one of PLA, PHA, PHB, PA11, PA1010, Bio-PE, Bio-PP, Bio-PVC, BIO-PET, Bio-PBU, or a combination thereof.

10. 10. The artificial turf system of any one of claims 1 to 9, wherein the granules further comprise a filler material, the filler material comprising at least one of chalk, talc, kaolin, wood fibers, lignocellulose, cellulose, hemicellulose, lignin, bast fibers, flax and hemp, and combinations thereof.

11. 11. The artificial turf system of any one of claims 1 to 10, further comprising a resilient layer including an impact pad structure below the substrate, and an additional layer of particles between the impact pad structure and the infill layer.

12. 12. The artificial turf system of claim 11, wherein the additional particle layer comprises particles of at least one of sand, sandstone, rubber, cork, wood, elastomer and plastic particles, or a combination thereof, preferably sand.

13. The artificial turf system according to any one of claims 1 to 12, wherein the granules have a cylindrical shape.

14. 14. The artificial turf system of claim 13, wherein the granules have a circular cross-section perpendicular to their length.

15. 14. The artificial turf system of claim 13, wherein the granules have a non-circular cross-section perpendicular to their length.

16. The artificial turf system of claim 1 , wherein the granules have an ellipsoid shape.

17. 17. The artificial turf system of claim 16, wherein the ellipsoid has three axes of different lengths, thereby forming a triaxial ellipsoid.

18. 17. The artificial turf system of claim 16, wherein the ellipsoid has two axes of the same length and a third axis of a different length, thereby forming a spheroid.

19. 20. The artificial turf system of claim 18, wherein the third axis is shorter than the other two axes, thereby forming an oblate ellipsoid.

20. 20. The artificial turf system of claim 18, wherein the third axis is longer than the other two axes, thereby forming a prolate spheroid.

21. 17. The artificial turf system of claim 16, wherein the ellipsoid has three axes of equal length, thereby forming a sphere.

22. 1. A granule for use as an infill material in an artificial turf system, the granule comprising at least 60% by weight of polybutylene adipate terephthalate (PBAT) and a pigment or pigment masterbatch, the granule having a Shore D hardness of 44 or less, preferably in the range of 25 to 44, more preferably in the range of 32 to 42, and most preferably in the range of 34 to 40.

23. 23. The granule of claim 22, wherein the granule comprises at least 70% by weight of PBAT.

24. 23. The granule of claim 22, wherein the granule comprises at least 90% by weight of PTAB.

25. A granule according to any one of claims 22 to 24, wherein the PBAT is fossil-based or partly bio-based.

26. Granules according to any one of claims 22 to 25, wherein the diameter of the granules is in the range of 0.1 to 5 mm, preferably 0.5 to 5 mm, more preferably 1 to 5 mm, more preferably 1.5 to 4 mm, most preferably 1.5 to 3.5 mm, and the length is in the range of 1 to 15 mm, preferably 1.5 to 10 mm, most preferably 1.5 to 5 mm.

27. Granules according to any one of claims 22 to 26, wherein the pigment is a dark green pigment.

28. Granules according to any one of claims 22 to 27, wherein the flexural strength of the granules, measured according to ISO 178:2019, is in the range of 2 to 17 MPa, preferably 3 to 8 MPa, most preferably 4 to 6 MPa.

29. Granules according to any one of claims 22 to 28, wherein the flexural modulus of the granules, measured according to ISO 178:2019, is between 50 and 250 MPa, preferably between 55 and 150 MPa, most preferably between 60 and 90 MPa.

30. 30. The granule according to any one of claims 22 to 29, wherein the granule further comprises 1 to 30 wt.% of another compostable polymer, preferably at least one of PEF, PHA, PLA, PBS, PBSA, PCL, TPS and starch, or a combination thereof.

31. 31. The granule according to any one of claims 22 to 30, wherein the granule comprises 1 to 30 wt% of another bio-based polymer, preferably at least one of PLA, PHA, PHB, PA11, PA1010, Bio-PE, Bio-PP, Bio-PVC, BIO-PET, Bio-PBU, or a combination thereof.

32. 32. The granule of any one of claims 22 to 31, wherein the granule further comprises a filler material, the filler material comprising at least one of chalk, talc, kaolin, wood fibers, lignocellulose, cellulose, hemicellulose, lignin, bast fibers, flax and hemp, and combinations thereof.

33. Granules according to any one of claims 22 to 32, wherein the granules have a cylindrical shape.

34. 34. A granule according to claim 33, wherein the granule has a circular cross-section perpendicular to its length.

35. 34. A granule according to claim 33, wherein the granule has a non-circular cross-section perpendicular to its length.

36. Granules according to any one of claims 22 to 32, wherein the granules have an ellipsoidal shape.

37. 37. A granule according to claim 36, wherein the ellipsoid has three axes of different lengths, thereby forming a triaxial ellipsoid.

38. 37. A granule according to claim 36, wherein the ellipsoid has two axes of the same length and a third axis of a different length, thereby forming a spheroid.

39. 39. A granule according to claim 38, wherein the third axis is shorter than the other two axes, thereby forming an oblate ellipsoid.

40. 39. A granule according to claim 38, wherein the third axis is longer than the other two axes, thereby forming a prolate spheroid.

41. 37. A granule according to claim 36, wherein the ellipsoid has three axes of equal length, thereby forming a sphere.

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