Use of a spreading granulate as infill granulate for grass and artificial turf pitches, as well as grass or artificial turf pitches with such infill granulate.

Abstract

Use of a spreading granulate as infill granulate for grass and artificial turf pitches, wherein the infill granulate comprises a polymer matrix with a proportion of between 10 wt.% and 100 wt.% of at least one biodegradable polymer and at least one filler from the group of natural fillers embedded in the polymer matrix with the at least one biodegradable polymer, characterized in that the infill granulate comprises at least one filler from the group of crushed fruit kernels with a higher hardness than that of the polymer matrix.

Description

[0001] The invention relates to the use of a spreading granulate as infill for grass and artificial turf pitches, wherein the infill granulate comprises a polymer matrix with a proportion of between 10 wt.% and 100 wt.% of at least one biodegradable polymer and at least one filler from the group of natural fillers embedded in the polymer matrix with the at least one biodegradable polymer. Furthermore, the invention relates to a grass or artificial turf pitch on which such infill granulate is applied.

[0002] Grass and artificial turf pitches are widely used, particularly as sports fields, such as football, hockey, tennis, rugby, and the like. Furthermore, grass and artificial turf pitches are also commonly used for other purposes, such as riding arenas, equestrian facilities, dog parks, or areas generally used for animal husbandry.

[0003] The grass and artificial turf pitches must meet a wide range of requirements, with a high degree of environmental friendliness being of paramount importance. Furthermore, if the grass or artificial turf pitches are used as sports fields, their technical properties must be tailored to the specific sport and comply with relevant standards and regulations. For example, the energy dissipation for football must be between 55% and 65%, while the energy return must be between 38% and 43% to be eligible for subsequent certification. In addition, the vertical deformation must not exceed 9 mm. To minimize the risk of injury to users, the rotational resistance must be between 25 Nm and 50 Nm. The aforementioned values ​​can be found in relevant standards and testing regulations, such as...DIN 18035-7 "Sports fields - Part 7: Artificial turf systems" or DIN EN 14808 "Sports surfaces - Determination of force reduction". Also important is the maximum water infiltration rate of greater than 500 mm / h, which must be determined according to DIN EN 12616 "Sports surfaces - Determination of water infiltration rate".

[0004] Alongside natural grass pitches, artificial turf pitches have become increasingly important in recent years, particularly to save on the maintenance costs associated with natural grass and the associated resource consumption (such as water, fertilizer, etc.). Various synthetic turf systems are used in the construction of new sports fields, offering a low-maintenance and weed-free surface compared to natural grass. These surfaces require neither watering nor fertilizing and are largely weather-independent. Artificial turf pitches typically have a multi-layered structure consisting of various components, often with an elastic layer or a bonded elastic base layer following a sub-base (e.g., a subgrade, a base course, and possibly an asphalt layer).The elastic layer is followed by a stabilizing backing layer, on which the actual artificial turf is laid. The latter consists primarily of fibers woven into a carpet-like structure. Artificial turf pitches used in Germany are based on the standards DIN 18035-7 and DIN EN 15330-1. The fiber layer is generally filled with infill granules, such as sand and / or rubber granules, just as is the case with natural grass pitches.

[0005] The elastic layer of artificial turf pitches serves two purposes: firstly, to compensate for unevenness in the underlying subsoil, ensuring a completely level, water-permeable surface; and secondly, to absorb impact forces through cushioning during use. In Germany, such an elastic layer is mandatory for artificial turf pitches according to the aforementioned standard DIN 18035-7, with its thickness typically varying between approximately 30 mm and 35 mm. Outside of Germany, the thickness of the elastic layer is usually less, generally less than 25 mm, and in some cases, it is omitted entirely. In these instances, the lack of elasticity is compensated for by a larger quantity of infill granules. Currently, synthetic fibers, such as those used for the fiber component of artificial turf, are primarily employed.Polyethylene (PE) is used, with the option of adding a second, shorter fiber component as a support structure to ensure the actual fibers stand upright. Due to its higher strength, polypropylene (PP) or even PE is currently sometimes used as the support fiber. To produce the fiber component, fiber filaments are tufted onto a carrier fabric, which is then laid on the elastic layer.

[0006] To comply with the aforementioned standards DIN 18035-7 and DIN EN 14808, infill granules are an important component for artificial turf pitches, as well as for natural grass pitches. They are particularly important for achieving the necessary force reduction, vertical deformation, and rotational resistance (see above). Furthermore, the infill granules significantly contribute to ball bounce and roll characteristics, which are essential when the (artificial) turf pitch is used for ball sports. Infill granules can also extend the lifespan of artificial turf pitches by reducing wear and tear during use. The infill granules should also be sufficiently weather- and UV-resistant to maintain their functionality over extended periods.

[0007] Regarding the types of infill granules currently used for grass and artificial turf pitches, primarily mineral granules are employed, as well as combinations of mineral and synthetically produced granules. The latter are composed of flexible, usually organic fillers. Quartz sand is often used as a mineral infill granule, increasing the rotational resistance and slip resistance of the grass. In the case of artificial turf, it adds weight and stabilizes the fibers. However, the typically sharp-edged sand particles pose a risk of skin abrasions, and such sands are very heavy, making both their transport and application on the (artificial) turf pitch complex.Synthetic infill granules, on the other hand, provide the necessary cushioning and, in the case of sports fields, the additional properties required to achieve the desired sporting functionality. This is intended to prevent injuries and provide a pleasant playing experience.

[0008] Currently available synthetic infill granules are primarily made from recycled styrene-butadiene rubber (SBR), derived from used tires, due to cost considerations. The dark color of these SBR granules increases the surface temperature of the turf pitches they cover, which is particularly problematic for artificial turf pitches, which often have a higher surface temperature than natural grass pitches. On hot summer days, with surface temperatures reaching approximately 40°C, artificial turf pitches covered with SBR granules have been found to reach temperatures of up to 75°C, making them practically unusable. Furthermore, the characteristic odor of SBR becomes dominant at relatively high temperatures, such as those prevalent during the summer, making cooling the artificial turf pitch essential in summer.To counteract this, SBR granules intended for use as infill have already been coated with lighter-colored polyurethane (PUR) coatings, which, however, wear off relatively quickly due to mechanical stress under intensive use. Besides SBR as the main component of such infill granules, known infill granules also contain additives such as various plasticizer oils, carbon black, antioxidants, and metallic components like zinc, copper, or chromium. Due to their health and environmental impacts, the use of recycled SBR as infill for (artificial) turf pitches has recently become a subject of controversial debate, with polycyclic aromatic hydrocarbons (PAHs) contained in the plasticizer oils playing a particularly significant role.

[0009] As an alternative to SBR, infill granules for (artificial) turf pitches based on ethylene propylene diene monomer (EPDM) rubber are also available. With the use of certain stabilizers, EPDM can also exhibit good weather resistance while maintaining largely consistent elasticity. Another advantage of EPDM over SBR recyclates is that the granule color can be freely chosen during production. However, in addition to a significantly higher price, a disadvantage is that EPDM—like SBR granules—is a cross-linked elastomer, meaning it cannot be remelted. This limits the range of applicable recycling technologies and thus its overall environmental friendliness.

[0010] As a further option, thermoplastic elastomers (TPEs) can be used for primarily elastic bedding granules. Their elastic component provides the necessary mechanical properties, while the thermoplastic component ensures that the polymer can be melted. This allows TPEs to be processed similarly to pure thermoplastics and offers better recyclability compared to SBR and EPDM. However, TPEs are not only by far the most expensive materials for bedding granules, but it has also been observed that the styrene-based TPEs currently used for bedding granules begin to soften at high ambient temperatures.This results in a sticky consistency of the TPE, which adheres to clothing and shoes when the (artificial) turf pitch is used and, in the case of artificial turf, also glues the individual fibers together, thus damaging the artificial turf pitch.

[0011] A fundamental problem associated with synthetic infill granules of the aforementioned types lies in their unavoidable release into the environment. This occurs not only during the use of the (artificial) turf pitch, but also purely through environmental influences such as wind, rain, artificial irrigation, and the like. According to the German Federal Environment Agency's definition, such infill granules fall under the category of "microplastics," which refers to plastic particles up to 5 mm in size. A distinction is made between so-called primary and secondary microparticles. While primary microparticles are specifically manufactured for various applications, secondary microparticles arise unintentionally through physical, chemical, or biological degradation, as well as through the fragmentation of plastic components.Consequently, artificial turf pitches insulated with such granules inevitably release both primary microplastics in the form of the infill itself and secondary microplastics through fiber abrasion and / or fragmentation of the infill. The extent of this release depends on various factors, including the type, quantity, and age of the granules, the fiber structure and geometry, the length of the artificial turf, the type and intensity of use, maintenance, and upkeep of the pitch, the surrounding natural environment (e.g., in floodplains, wind corridors, etc.), and local weather events.The main pathways for the release of infill granules were identified as rain and wind, including artificial irrigation (approximately 70%), drainage (approximately 15%), snow removal (approximately 10%), and a significant amount carried on clothing and shoes. Within the European Union, the synthetic infill granules currently used for artificial turf systems are considered to be the largest source of intentionally introduced microplastics, with the European Chemicals Agency (ECHA) estimating that around 100,000 tons of infill granules are used annually. These infill granules also represent the largest source of microplastic release into the environment, with an estimated release of around 16,000 tons per year, resulting in a calculated release rate of approximately 16%.

[0012] However, the release of microplastics into the environment—whether into aquatic systems or soils—should be prevented as far as possible due to the environmental and health consequences for flora and fauna. For example, animals can mistake these particles for food and ingest them, leading to damage and irritation of the intestinal tract. If the particles are not excreted, the animal experiences a feeling of fullness, resulting in deficiencies or even starvation. Another problem is the migration of harmful components from the plastic, which can enter the food chain via this release, such as the plasticizer oils mentioned above, which are primarily found in SBR recyclates.The latter can contain polycyclic aromatic hydrocarbons (PAHs), some of which are classified as carcinogenic, mutagenic, and / or toxic to reproduction. Furthermore, PAHs can be persistent, meaning they remain in the environment for extended periods or degrade poorly. They are also capable of bioaccumulation, accumulating in the fatty tissue of humans and animals, which significantly amplifies their harmful effects on health. With regard to EPDM bedding granules, reduced plant growth and negative impacts on root systems have also been observed. Moreover, microparticles can directly affect soil organisms and, consequently, soil functionality. For example, reduced reproduction and shorter body lengths of nematodes have been observed as a result of microplastic exposure.Specifically regarding SBR recyclates from old tires, there is the additional risk that heavy metals, such as zinc, copper and chromium, can enter the environment, potentially causing limit values ​​in soil or water to be exceeded.

[0013] Recently, research has increasingly focused on alternatives to so-called "infill" materials, which can be used as infill granules for (artificial) turf pitches. These alternatives are not synthetic but based on natural resources. The most widespread of these natural, resilient infill granules is cork derived from cork oak trees, which can be reinforced with coconut fibers. For use specifically in artificial turf pitches, cork offers advantages such as its low density, high strength, low wear, and low heat absorption in sunlight. However, a disadvantage is the highly variable properties of cork under different weather conditions. For example, the cork granules can harden to varying degrees at very low temperatures, such as freezing. Furthermore, due to its low density, cork can easily be washed away in large quantities during heavy rain.In summer, however, cork granules tend to dry out, causing them to stick to clothing and shoes, forming dust and losing elasticity. Therefore, artificial irrigation of the (artificial) turf pitch is essential when using cork granules at higher temperatures. Compared to the synthetic infill granules described above, cork also has a much shorter lifespan, requiring frequent replacement.

[0014] US 2020 / 0165784 A1 describes an artificial turf sports field comprising a substrate of artificial turf fibers and an infill granulate made of bio-based and / or biodegradable plastic. Examples of such plastics include polylactic acid (PLA), polybutylene succinate (PBS), polycaprolactone (PCL), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polyethylene (PE), polypropylene (PP), or their derivatives. The polymer matrix of the bedding granules can be mixed with various fillers, including natural fillers such as starch, cork, coconut, hemp, grass, cellulose, reed, hay, straw or cardboard, as well as mineral fillers such as zeolites, CaCO3, SiO2, Al2O3, MgO, lime, kaolin or talc.

[0015] US patent 2018 / 0179711 A1 concerns another artificial turf pitch, which comprises a polymer-based artificial turf fiber substrate and an infill granulate. The infill granulate consists of composite particles containing between 10 and 90% by weight of a thermoplastic polymer and between 10 and 80% by weight of cellulose fibers. The polymer matrix of the infill granulate can consist of conventional synthetic polymers as well as bio-based and biodegradable polymers, such as starch-based polymers, polylactic acid (PLA), poly-3-hydroxybutyrate, or bio-based polyethylene.The cellulose fibers may contain additional filler particles or fibers, such as those from various soft and hardwoods, bamboo, rattan, rice and wheat straw, rice husks, bagasse, cotton straw, jute, hemp, flax, kenaf, milkweed, grass, banana plants, coconut, whale, pecan or other nutshells, and peanut shells. Furthermore, mineral fillers such as seashells or CaCO3 from other sources, mica, talc, barite, or ceramics may be used.

[0016] WO 2018 / 016956 A1 describes another artificial turf pitch for sports purposes, comprising a substrate with artificial grass fibers and an infill granulate. In this case as well, the polymer matrix of the granulate particles is made from bio-based and biodegradable polymers, such as polylactide and its derivatives, polybutylene succinate (PBS), polycaprolactone (PCL), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polyhydroxyalkanoate (PHA), or polyhydroxybutyrate (PHB). Furthermore, various fillers are also specified in this case.

[0017] Finally, US 2019 / 0316303 A1 describes another artificial turf pitch with an infill granulate containing between 10 and 40% by mass of natural fibers mixed into rubber, which are selected from the group of hemp, cotton, linen, sisal, elephant grass and / or cellulose fibers.

[0018] Regarding the fillers for the infill granules proposed in the aforementioned publications, these include, on the one hand, plant fibers such as wood, nutshell, or leaf fibers, which are soft compared to the polymer matrix of the granule particles and do not impart any greater hardness to the granule particles to adapt them to the respective sporting requirements. With respect to fillers that are harder than the polymer matrix of the granule particles, the aforementioned publications exclusively specify mineral fillers such as zeolites, CaCO3, SiO2, Al2O3, MgO, lime, kaolin, or talc, as well as shells or CaCO3, mica, talc, barite, or ceramics from other sources.

[0019] The invention is based on the objective of proposing a simple and cost-effective infill granulate suitable for use as granulate on grass and artificial turf pitches, while avoiding at least the aforementioned disadvantages to a large extent. This granulate should possess the greatest possible environmental compatibility and be particularly suitable for sports fields, as it meets the sports-related properties described above. Furthermore, it is directed towards a grass or artificial turf pitch onto which such infill granulate is applied.

[0020] The first part of this problem is solved according to the invention by using a scattering granulate as infill granulate for grass and artificial turf pitches, wherein the infill granulate comprises at least one filler with a higher hardness than the hardness of the polymer matrix from the group of crushed fruit kernels.

[0021] To solve this problem, the invention further provides that, in the case of a lawn or artificial turf pitch on which such infill granules are applied, the infill granules are such that they comprise at least one filler with a higher hardness than that of the polymer matrix from the group of crushed fruit kernels.

[0022] In accordance with the invention, the infill granules are spread onto the grass or artificial turf pitch in a manner known as such. They are sufficiently stable and largely water-insoluble to fulfill their function even after prolonged exposure to sunlight, precipitation, frost, and other external influences. Surprisingly, it was found that the infill granules according to the invention, which comprise at least one filler from the group of crushed fruit kernels with a higher hardness than that of the polymer matrix, are able to fully meet the sporting requirements not only for natural grass pitches but also, and especially, for artificial turf pitches. In the case of artificial turf pitches, they also provide the necessary stabilizing effect of the fiber layer.It can therefore perform the functions in an excellent way, to the same extent as the already known synthetic bedding granules. - the stability of artificial turf, - the protection of the backing layer of artificial turf, - stabilizing the fibers of artificial turf, - the optimization of force reduction, energy recovery and rotational resistance during the performance of any sport, as well as - the optimization of ball reflection when playing ball sports take over.

[0023] On the other hand, the invention makes it possible for the infill granules to decompose almost completely without residue into degradation and / or metabolic products that are both harmless to health and ecotoxicologically, given that—as mentioned above—a significant portion is always carried away from the (artificial) turf pitch. This ensures impeccable environmental friendliness without the introduction of long-term stable or even ecotoxicological microplastic particles. "Biodegradable" within the meaning of the invention means that at least one polymer of the infill granules can be completely degraded by microorganisms, such as bacteria and fungi, or by enzymes. The microorganisms use the polymer as food or as an energy source. During this metabolism, the polymers must be completely broken down under aerobic conditions into carbon dioxide (CO2), water (H2O), mineral salts, and new biomass.Without oxygen, i.e., under anaerobic conditions, complete conversion to carbon dioxide, mineral salts, biomass, and methane (CH4) must occur. The at least one biodegradable polymer of the bedding granules can preferably be compostable according to DIN EN 13432 or the US standard ASTM D6400, with composting representing a special case of biodegradability. In industrial composting, the compostable polymer must be completely degraded within a relatively short period of time, a maximum of two years, under controlled conditions (i.e., a temperature of approximately 60°C and a defined humidity level).

[0024] In an advantageous embodiment, the polymer matrix of the bedding granules can comprise a proportion of at least one biodegradable polymer of at least approximately 20 wt.%, in particular at least approximately 30 wt.%, preferably at least approximately 40 wt.%, and most preferably at least approximately 50 wt.%. Particularly preferred are proportions of at least approximately 60 wt.%, in particular at least approximately 70 wt.%, preferably at least approximately 80 wt.%, and most preferably at least 90 wt.%, wherein the proportion of the at least one biodegradable polymer can also be at least nearly 100 wt.%.

[0025] In a further advantageous embodiment, it can be provided that at least one biodegradable polymer of the polymer matrix of the bedding granules is selected from the group of bio-based polymers, which are polymers that can be produced entirely or partially from renewable raw materials, as explained in more detail below.

[0026] The polymer matrix of the bedding granules should preferably also have a water solubility of at most about 0.5 g / l, e.g. of at most about 0.3 g / l, in particular of at most about 0.1 g / l, so that the bedding granules are largely insoluble in water and remain dimensionally stable and do not dissolve under the influence of precipitation, such as rain or snow, for a longer period of time.

[0027] In order to ensure particularly flawless sporting technical properties, it is further advantageous if the polymer matrix of the bedding granules has an elastic modulus of 0.1 GPa to 8 GPa, in particular of 0.2 GPa to 5 GPa.

[0028] With regard to the biodegradable polymer used for the polymer matrix of the in-the-in-the-inventory bedding granules, it can be advantageously provided that at least one biodegradable polymer of the polymer matrix of the bedding granules is selected from the group of thermoplastic polymers, so that, on the one hand, simple production using known thermoplastic processing methods (e.g., by extrusion and comminution of the extrudate to form the bedding granules using a cutting tool, which can preferably be carried out underwater to produce largely spherical granule particles), and, on the other hand, easy recyclability of the bedding granules is ensured. Advantageous biodegradable polymers include, in particular, those according to the above-mentioned standard DIN EN 13432, especially from the group - the polyhydroxyalkanoates, in particular polyhydroxybutyrate (PHB), poly-4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), polyhydroxyacetic acid, poly (3-hydroxybutyrate-co-4-hydroxybutyrate), poly (3-hydroxybutyrate-co-4-hydroxybutyrate), poly (3-hydroxybutyrate-co-4-hydroxybutyrate), polyhydroxyhexanoate (PHH) and / or polyhydroxyoctanoate (PHO); - Polylactide (PLA); - Starch and / or its derivatives; - Polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS) and / or polybutylene succinate adipate (PBSA); - Polysaccharides and / or their derivatives; - Lignin and / or its derivatives; - Polycaprolactone (PCL); - Proteins and / or their derivatives, including their blends.

[0029] Biodegradable polymers can therefore be those synthesized from monomers. As mentioned above, these biodegradable polymers can advantageously be bio-based, such as preferably polylactic acid (PLA), polyhydroxyalkanoates (PHA), e.g., polyhydroxybutyrate (PHB), starch and / or lignin, including their derivatives, etc., as well as non-bio-based polymers, such as polybutylene adipate terephthalate (PBAT), polycaprolactones (PCL), etc. Furthermore, biodegradable polymers can also be partially bio-based, as in the case of polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA). Examples of polysaccharide derivatives include those in which functional groups of the natural polymer, e.g., the OH and / or NH₂ groups, are partially or completely substituted, as in the case of cellulose esters (such as...).Cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate etc.), starch esters (such as starch acetate, acetylated distarch adipate etc.) or partially deacetylated chitin and its derivatives.

[0030] In this process, several biodegradable polymers can be used in the form of a blend or polymer mixture, which can be bio-based, non-bio-based, and / or partially bio-based. This can also prove advantageous because some biodegradable polymers are difficult to process on conventional thermoplastic processing machines, such as single- or twin-screw extruders, and / or the properties of the pure polymers alone are unsatisfactory. However, if several polymers are physically blended in the melt, for example, starch-PBAT blends or PLA-PBAT blends can be generated, which are readily processable.In addition to the possible addition of additives, fillers and the like (see below), the advantages of various biodegradable polymers can be combined in this way and any disadvantages, such as a dominant brittleness of a blend partner, can be compensated for.

[0031] Furthermore, particularly when using the infill granules for sports fields, it is preferable to select at least one biodegradable polymer from the group of elastomeric polymers in the polymer matrix of the infill granules, especially from the natural rubber group (e.g., from rubber plants and / or dandelion sap), to give the infill granules the desired elasticity. The elastomeric polymers can be mixed with one or more of the aforementioned thermoplastic polymers to achieve the desired elasticity. In this way, a pleasant and safe playing surface can be provided, especially on a grass or artificial turf field used for sports, by modifying the mechanical properties of the infill granules through the selection of the proportion of each blending partner in its polymer matrix.Furthermore, covalent integration of a soft phase into at least one biodegradable polymer of the bedding granules is also conceivable in order to adjust the damping or compliant elastic properties. Examples of such a soft phase include the integration of low-molecular-weight polyethylene glycols (PEG), which are biodegradable up to an average molar mass of approximately 1,500 g / mol.

[0032] Furthermore, the polymer matrix of the bedding granules should have a melting point of at least about 70°C, in particular at least about 80°C, preferably at least about 90°C, e.g. at least about 100°C, in order to prevent the bedding granules from partially or completely melting even at very high ambient temperatures and / or direct sunlight.

[0033] The at least one filler with a higher hardness than the hardness of the polymer matrix from the group of crushed fruit kernels can be, for example, olive kernel flour, cherry kernel flour, apricot kernel flour and the like.

[0034] In a further advantageous embodiment, the bedding granules may include at least one additional filler embedded in the polymer matrix containing at least one biodegradable polymer. This additional filler may be essentially powdery, particulate, or fibrous, and preferably of natural origin and biodegradable. Examples of possible fillers include, in particular, fibrous or flour-like natural materials such as cellulose, lignin, wood, reeds, miscanthus, hemp, seagrass, nutshells, and the like, but also, for example, mineral substances such as ash.

[0035] Furthermore, additives known as such may be added to the polymer matrix of the bedding granules, such as processing aids, UV stabilizers, flame retardants, dyes and pigments, environmentally safe plasticizers, such as natural oils or waxes, and the like.

[0036] As already mentioned, in many applications of infill granules, it can be advantageous for them to have rounded, and especially essentially spherical, granule particles. This is particularly true for use on grass and artificial turf pitches in sports fields, in order to ideally meet the technical requirements of sports and to prevent the risk of injury caused by sharp-edged granule particles, such as skin abrasions. As also already mentioned, such essentially round granule particles can be produced, for example, by cutting the extrudates, e.g., using a die assembly of a single- or multi-screw extruder, into granule particles underwater, for example, by cutting them underwater with a rotating cutting tool.

[0037] Depending on the intended use, the bedding granules may also preferably have a granule particle size of - at least approximately 1.0 mm, in particular at least approximately 1.5 mm, preferably at least approximately 2.0 mm, and / or - have a particle size of at most approximately 5.0 mm, in particular of at most approximately 4.5 mm, preferably of at most approximately 4.0 mm, wherein the particle size can be adjusted, for example, by the selected nozzle cross-section of a single or multi-screw extruder, and by the rotational speed of a rotating cutting blade.

[0038] In a lawn or artificial turf pitch according to the invention, the infill granules can preferably be applied with an average filling height of between about 1.0 mm and about 2.5 mm, in particular between about 1.3 mm and about 2.0 mm.

[0039] According to a further development of a grass or artificial turf pitch according to the invention, it can also be provided with an antimicrobial finish to delay the biodegradation of the infill granules on the grass or artificial turf pitch. This allows the biodegradation of the infill granules to occur primarily when the infill granules have been removed from the (artificial) turf pitch, whereas on the (artificial) turf pitch itself, the properties of the infill granules remain largely unchanged over a long period despite environmental influences. For this purpose, the (artificial) turf pitch can, for example, be sprayed with non-toxic antimicrobial agents and / or disinfectants, or, particularly in the case of an artificial turf pitch, antimicrobial finishes can be applied to its fibers and / or its elastic layer, e.g.in the form of silver ions or the like incorporated into their polymer matrix.

Claims

[1] Use of a spreading granulate as infill granulate for grass and artificial turf pitches, wherein the infill granulate comprises a polymer matrix with a proportion between 10 wt.% and 100 wt.% of at least one biodegradable polymer and at least one filler from the group of natural fillers embedded in the polymer matrix with the at least one biodegradable polymer, characterized by that the bedding granules contain at least one filler from the group of crushed fruit kernels with a higher hardness than that of the polymer matrix. [2] Use according to claim 1, characterized by that the polymer matrix of the bedding granules contains a proportion of at least 20% by mass of at least one biodegradable polymer. [3] Use according to claim 1 or 2, characterized by, that at least one biodegradable polymer of the polymer matrix of the bedding granules is selected from the group of bio-based polymers. [4] Use according to any one of claims 1 to 3, characterized by that the polymer matrix of the bedding granules has a water solubility of at most 0.5 g / l. [5] Use according to any one of claims 1 to 4, characterized by , that the polymer matrix of the bedding granules has an elastic modulus of 0.1 GPa to 8 GPa. [6] Use according to any one of claims 1 to 5, characterized by , that at least one biodegradable polymer of the polymer matrix of the bedding granules is selected from the group of thermoplastic polymers. [7] Use according to any one of claims 1 to 6, characterized by , that at least one biodegradable polymer of the polymer matrix of the bedding granules is selected from the group of elastomeric polymers, in particular from the group of natural rubber. [8] Use according to claim 6 or 7, characterized by that the polymer matrix of the bedding granules has a melting point of at least 70°C. [9] Use according to any one of claims 1 to 8, characterized by , that at least one of the fillers consists of crushed fruit kernels in the form of olive kernel, cherry kernel or apricot flour. [10] Use according to any one of claims 1 to 9, characterized by that the bedding granules contain at least one further filler from the group of natural fillers embedded in the polymer matrix with at least one biodegradable polymer. [11] Use according to any one of claims 1 to 10, characterized by that the bedding granules have rounded, in particular essentially spherical, granule particles. [12] Use according to any one of claims 1 to 11, characterized by that the bedding granules have a granule particle size of - at least 1.0 mm and / or - maximum 5.0 mm exhibits. [13] A grass or artificial turf pitch on which an infill granulate has been applied, characterized by , that the bedding granules are those according to one of claims 1 to 12. [14] Grass or artificial turf pitch according to claim 13, characterized by , that the bedding granules are applied with an average fill height between 1.0 mm and 2.5 mm. [15] Grass or artificial turf pitch according to claim 13 or 14, characterized by that it is equipped with antimicrobial equipment to delay the biological degradation of the infill granules on the grass and artificial turf pitch.