Infill for artificial turf

Abstract

The invention relates to an infill for artificial turf, more particularly, it relates to the use of a granule comprising wool fibre and a wax as infill for artificial turf. The invention also relates an artificial turf comprising said granule as infill and to the use of raw wool as artificial turf infill. The invention also relates to a granule comprising wool fibre and a wax and to a process for preparing it.

Description

[0001]

[0002] “Infill for artificial turf”

[0003] TECHNICAL FIELD

[0004] The present invention relates to an artificial turf and, more specifically, to an infill for an artificial turf.

[0005] BACKGROUND ART

[0006] Artificial turf or artificial grass is a surface used to replace grass. The primary components of artificial turf are a carpet comprising a backing material and artificial grass fibres attached to it, a base layer made from gravel or stone, optionally a shockpad between the base layer and the carpet, and one or more infill materials.

[0007] Artificial turf infill is a granular material that covers the bottom portion of the artificial turf fibres and mimics the role of soil in a natural grass system. It has several functions, for example, it helps to hold the grass fibres upright, it absorbs impact and provides cushioning, it helps to keep the artificial turf carpet flat and in place, and it may also help to reduce the artificial turf heating. Regarding these functions, one of the most important aspects in the mechanics of modern artificial turf is the compression and shear behaviour of the granular infill.

[0008] The infill is generally constituted of at least two layers, the bottom layer serving to weight down and stabilizing the carpets, whereas the top layer provides the required cushioning and mechanical properties. The bottom layer is often sand.

[0009] One of the most popular materials for the upper layers of infill are styrenebutadiene rubber (SBR) particles, which are readily available from recycled materials, particularly from waste tyres, providing an affordable option for infill, with good cushioning properties. Other types of rubber and thermoplastics are also used as infill materials.

[0010] An important drawback of rubber as infill material relates to the concerns raised in the last years about the health and environmental effects of toxic chemicals found in tire crumb, which may migrate into surrounding soil and water. These concerns have fuelled the research of alternative infills. Alternatives include a range of synthetic materials, as well as plant and mineral-based materials.

[0011] For example, plant-derived materials such as cork, coconut, or walnut shells, are at present also commonly used as alternative to crumb rubber.

[0012] The US patent application US-A-2021 / 0254290 discloses the use olive pit particles as infill for artificial turf. The international patent application WO-A-2020 / 120799 discloses a turf infill comprising a mixture of cork particles and rubber particles, wherein said cork and rubber particles are coated with a polymer and / or resin component.

[0013] The international patent application WO-A-2018 / 183756 discloses an infill material for an artificial turf system having a plurality of wood particles of certain dimensions.

[0014] Some proposals relate to the use of biodegradable polymers as infill material. For example, the international patent application WO-A-2022 / 144442 discloses the use of foamed polybutylene adipate terephthalate (PBAT) as infill material.

[0015] The international patent application WO-A-2022 / 008710 discloses an artificial turf infill consisting of granules comprising compostable polymer, a filler material and an oil. The compostable polymer is selected from polylactic acid (PLA), thermoplastic copolyester elastomer (TPC), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3- hydroxyvalerate) (PHBV), polyhydroxybutyrate (PHB), polyhydroxyalkanoate (PHA), polybutylene adipate terephthalate (PBAT).

[0016] Other solutions relate to the combination of hydrophilic fibres and elastomeric compounds. For example, in the international patent application WO-A-2018 / 019732 the infill comprises a water absorbent yarn that is covered with a jacket formed from an elastomeric compound, said jacked comprising at least one opening exposing the water absorbent yarn.

[0017] In the international patent application WO-A-2018 / 019733 an infill material is described comprising natural fibre, which is at least partially embedded in a vulcanized portion and wherein the natural fibre is selected from hemp, sisal, cotton, burlap, elephant grass or cellulose fibres.

[0018] In the international patent application WO-A-2018 / 019734, the artificial turf infill comprises said natural fibre mixed with rubber granulate.

[0019] In the international patent application WO-A-2018 / 019735 an infill material is described consisting of a natural fibre and at least one outer coating comprising a pigment and a polyurethane polymer.

[0020] Despite the proposals available so far in the state of the art, there remains a need for safe and environmentally friendly infill materials that provide good mechanical properties, while presenting high availability, and low cost.

[0021] SUMMARY OF THE INVENTION

[0022] The object of the present invention is the use of a granule comprising wool fibre and a wax as infill for artificial turf.

[0023] Another aspect of the invention is the use of raw wool for preparing an infill for artificial turf. Another aspect of the invention is an artificial turf infill granule.

[0024] Another aspect of the invention is a process for the manufacture of said granule.

[0025] Another aspect of the invention is an artificial turf comprising said granule as infill material.

[0026] DETAILED DESCRIPTION OF THE INVENTION

[0027] The object of the present invention is the use of a granule comprising wool fibre and a wax as infill for artificial turf.

[0028] The authors of the present invention have developed a new infill for artificial turf entirely based on wool, which fulfils all the expected requirements. Wool, particularly raw wool, is an inexpensive material which, surprisingly, has been found to provide outstanding performance as infill substance. Surprisingly, the authors of the present invention found that wool fibre provides remarkable mechanical properties to the infill, which make it suitable to be used in artificial turfs for sports, without the need to add any additional elastic material, in particular, without the need of any elastomer or any other plastic material.

[0029] Along the present description, as well as in the claims, singular expressions, generally preceded by the articles “a”, “an” or “the”, are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0030] The terms “about” or “approximately” referred to amounts, as used herein, are meant to include the exact amount and also a certain deviation around the stated amount, namely of ±5%.

[0031] The numerical ranges disclosed herein, generally expressed as “from ... to ...” or as “between ... and ...”, or using a hyphen (e.g. “20-30”) are meant to include any number falling within the ranges and also the lower and upper limits.

[0032] Use of wool granules as infill for artificial turf

[0033] The present invention relates to the use of a granule comprising wool fibre and a wax as infill for artificial turf.

[0034] More particularly, the present invention relates to the use of a granule comprising wool fibre and a wax as infill for artificial turf, wherein the granule does not contain any elastomer or any plastic material. That is, the granule comprises neither elastomer nor plastic material.

[0035] An elastomer, as is well known in the art, is a polymeric material which is viscoelastic and able to regain its shape after deformation. Non-limiting examples of elastomers that are excluded from the granules according to the present invention are natural rubber, which is a natural elastomer, or synthetic elastomers such as bromo butyl rubber (BUR), chloro butyl rubber (CIIR), chloroprene rubber (or polychloroprene or neoprene, CR), ethylene propylene diene rubber (EPDM), ethylene propylene rubber (EPM), fluoroelastomers (FKM), isobutylene isoprene rubber (or butyl rubber, HR), nitrile butadiene rubber (NBR), polybutadiene rubber (BR), polyisoprene rubber (IR), styrene butadiene rubber (SBR) or thermoplastic elastomers (TPE, such as thermoplastic polyurethane - TPU, thermoplastic olefin - TPO, or thermoplastic copolyester - TPC), among others, or derivatives thereof.

[0036] Plastic materials, or plastics, encompass a wide range of synthetic or semisynthetic materials composed primarily of polymers.

[0037] Plastics can be classified in thermoplastics and thermoset.

[0038] A thermoplastic, or thermosoftening plastic, as is well-known in the art, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.

[0039] The granules according to the present invention, in particular, do not contain any thermoplastic. Non-limiting examples of thermoplastics that are excluded from the granules according to the present invention include acrylonitrile butadiene styrene (ABS), high-density polyethylene (HDPE), low-density polyethylene (LDPE), maleic anhydride grafted polymers, nylon, polyacrylates, polyamides (PA), polybenzimidazole (PBI), polycarbonate (PC), polylactic acid (PLA), polyoxymethylene (POM), polypropylene (PP), polystyrene (PS), polytetrafluoroethylene (PFTE), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), styrene maleic anhydride copolymer (SMA), or thermoplastic polyurethane (TPU), among others, or a derivative thereof.

[0040] A thermoset, or thermosetting polymer, as is well-known in the art, is any plastic polymer material that forms an irreversible, cross-linked network upon curing and cannot be remelted.

[0041] The granules according to the present invention, in particular, do not contain any thermoset. Non-limiting examples of thermosets that excluded from the granules according to the present invention include epoxy resins or thermoset polyurethane (PU), among others.

[0042] Furthermore, in an embodiment, the granules according to the present invention also do not contain any compostable polymer. Non-limiting examples of compostable polymers that are preferably excluded from the granules according to the present invention include polylactic acid (PLA), thermoplastic copolyester elastomer (TPC), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polyhydroxybutyrate (PHB), or polyhydroxyalkanoate (PHA), among others, or a derivative thereof. In an embodiment of the invention, the artificial turf infill granule comprises at least 20 wt% of wool fibre, based on the weight of the granule on dry basis, and the weight ratio wool fibre:wax is comprised between 1.5:1 and 15:1.

[0043] In another embodiment of the invention, the artificial turf infill granule comprises between 20 wt% and 90 wt% of wool fibre, preferably between 25 wt% and 85 wt% of wool fibre, based on the weight of the granule on dry basis; and the weight ratio wool fibre:wax is comprised between 1.5:1 and 15:1 , preferably comprised between 2:1 and 10:1 , and more preferably comprised between 3:1 and 8:1.

[0044] Wool fibre is composed of complex, highly cross-linked keratin proteins. Wool fibre is obtained mainly from sheep wool, but also from other mammals, such goats, rabbits, and camelids. l / l / ax

[0045] Besides wool fibre, the infill granule according to the present invention also comprises a wax. The term “wax”, as is commonly understood in the field, defines lipophilic soft malleable solid organic compounds with melting points above about 40 °C. Typically, the waxes include two broad classes, namely, high molecular weight alkanes and lipids. They can be of animal or vegetal origin, while alkanes can also be synthetic, obtained from petroleum, coal or shale oil. Lipid waxes are typically esters of long chain fatty acids with long chain fatty alcohols, or other high molecular weight alcohols, such as sterols. Waxes may also be made up of compounds containing other functional groups such as ketone, aldehyde, carboxyl, alcohol and olefinic bond.

[0046] Natural waxes suitable to be used in the infill granules of the present invention include lanolin, beeswax, spermaceti, carnauba wax, candelilla wax, rice bran wax, ouricury wax, myrica wax, esparto wax, Chinese wax, shellac, and vegetable stearin, among others, and mixtures thereof. Suitable synthetic waxes include paraffin, microcrystalline wax, polyethylene wax, among others, and mixtures thereof.

[0047] In an embodiment the wax is selected from the group consisting of: lanolin, beeswax, spermaceti, carnauba wax, candelilla wax, rice bran wax, ouricury wax, myrica wax, esparto wax, Chinese wax, shellac, vegetable stearin, paraffin, microcrystalline wax, polyethylene wax, and mixtures thereof, preferably is selected from the group consisting of lanolin, beeswax, carnauba wax, candelilla wax, myrica wax, Chinese wax, shellac, vegetable stearin, paraffin, microcrystalline wax, polyethylene wax, and mixtures thereof, more preferably is selected from the group consisting of: lanolin, beeswax, carnauba wax, candelilla wax, paraffin and mixtures thereof, still more preferable is selected from the group consisting of lanolin, paraffin and mixtures thereof, and still more preferably is lanolin. Wool

[0048] A preferred wax for the infill granule according to the present invention is lanolin, which is the natural wax accompanying wool fibre in raw wool.

[0049] The wool directly obtained after sheep shearing is known as “raw wool” or “greasy wool”. Raw wool mainly consists of wool fibre and natural lipids from wool grease (or wool wax). In the present description the terms wool grease and wool wax are used interchangeably. Wool grease, usually known as lanolin, is secreted by the sebaceous glands of sheep and is made of a complex mixture of long chain waxy esters, mainly sterol esters.

[0050] Other components also commonly found in raw wool are dirt and suint, as well as a certain percentage of water.

[0051] Dirt refers to impurities acquired from sheep’s surroundings, which can be mineral or vegetable contaminants, including sand, seedpods, grass straw, and pieces of plant tissue, among others. Suint is a substance secreted from sweat glands of the sheep, which dries on the skin and wool fibre. Suint comprises a mixture of potassium salts of fatty acids, such as oleic and stearic acids, which are water soluble.

[0052] The amount of wool fibre in raw wool normally ranges from about 50 wt% to about 70 wt%, while the amount of wax normally ranges from about 5 wt% to about 25 wt%. The amount of dirt can range from about 8 wt% to about 20 wt%, while the amount of suint normally ranges from about 5 wt% to about 10 wt%. The amount of water is typically comprised between 10 wt% and 12 wt%. For example, the following average composition for raw wool is reported: 55 wt% of wool fibre, 16 wt% of grease, 14 wt% of dirt, 10 wt% of water and 5 wt% of suint (Saravanan et al., Preprocessing of wool fibers, Chapter 4 in: The Wool Handbook, Morphology, Structure, Properties, Processing and Applications, Elsevier, 2024, pg. 114).

[0053] The percentage of said components may also vary depending on the specific sheep breed. For example, the following average composition (in wt%) is reported for Merino: 49% fibre, 19% dirt, 6% suint, 16% grease and 10% water; while for Crossbred the following average composition is reported: 61% fibre, 8% dirt, 8% suint, 11% grease and 12% water (in: Textile Preparation and Dyeing, A. K. Roy Choudhury, editor, Science Publishers, 2006).

[0054] The term “clean wool” or “scoured wool” refers to wool obtained after scouring of raw wool, to at least partly remove the fat and other impurities found in raw wool. After scouring, the wool still contains water, and small quantities of wax and dirt, usually, about 0.5 wt% or less of residual grease and less than 1.5 wt% of mineral matter (dirt).

[0055] Advantageously, the inventors found that raw wool, without any cleaning process, is particularly suitable for preparing the infill granules according to the present invention, as it provides the necessary amount of elastic fibre and the necessary amount of wax, and it was found that the accompanying substances (dirt, suint) do not hamper the performance of wool fibre as infill material. Therefore, the present invention provides not only an unexpensive source for artificial turf infill, but also a way or recycling raw wool, which at present is mostly a waste from sheep farming, with no economic value. Furthermore, raw wool is a natural, biodegradable alternative for infill, free of chemicals of concern for human health and environment.

[0056] Therefore, with regards to environmental impact of the infill granules of the present invention, advantageously, when they eventually would need to be replaced after certain period of time, they could be composted in composting plants.

[0057] Raw wool generally comprises wool fibre and lanolin in the amounts suitable to be used according to the present invention, without the need of any additional component.

[0058] The composition of the artificial turf infill granules of the present invention can be described based on the content of wool fibre and wax, referred to the weight of the granule on dry basis. Said granules also comprise a certain amount of water, typically ranging from about 5 wt% to about 15 wt%, which is the natural moisture of wool fibre. It is to be understood that this amount of water may vary when the infill is in use, when exposed either to rain or dry weather.

[0059] Alternatively, the composition of the artificial turf infill granules can be described based on the content of the components used in its preparation, e.g. clean or raw wool, added wax, and filler, referred to the total weight of the granule, meaning the sum of the weight of the components.

[0060] Another aspect of the invention is the use of raw wool for preparing an infill for artificial turf, wherein the infill does not contain any elastomer or any plastic material. Preferably, the infill also does not contain any compostable polymer.

[0061] Alternatively, clean wool, essentially composed by wool fibre, can also be used, and it can also provide an unexpensive raw material source of wool fibre for preparing the infill, particularly as a way of recycling used wool textiles, such as felt, made of clean wool.

[0062] When clean wool is used, an external wax, as hereinabove defined, must be added.

[0063] According to the use of the present invention, the granules, when prepared from raw wool, are typically made up of the raw wool components plus, optionally, an inorganic filler and / or an antimicrobial agent, without any additional ingredient.

[0064] When the granules are prepared using clean wool, they are also typically made up of the clean wool, a wax and, optionally, an inorganic filler and / or an antimicrobial agent, without any additional ingredient. Therefore, in an embodiment of the invention, the infill granule essentially consists of: i) raw wool, or a mixture of clean wool and a wax; ii) optionally, an inorganic filler; and iii) optionally, an antimicrobial agent.

[0065] In a particular embodiment, the granule essentially consists of: i) raw wool, or a mixture of clean wool and a wax; ii) an inorganic filler; and iii) optionally, an antimicrobial agent.

[0066] Inorganic filler

[0067] In an embodiment, the infill granules according to the present invention also contain an inorganic filler material, with the purpose of increasing the density of the granules. The use of a filler makes the weight of the granules to increase, and it helps the infill granules to remain in place, preventing them from being swept away while they are in use in an artificial turf, particularly, when subjected to strong wind or heavy rain.

[0068] The inorganic filler may be, for example, barium sulfate (barite), calcium carbonate, magnesium carbonate, magnesium oxide, silica, modified silica, silicates, chalk, china clay, talc, aluminosilicate, sand, calcium magnesium carbonate (dolomite), limestone, diatomaceous earth, among others, used alone or in combination. Preferred inorganic fillers are barium sulfate (barite), calcium carbonate, calcium magnesium carbonate (dolomite), and mixtures thereof.

[0069] The inorganic filler is made up of particles, typically having a volume median particle diameter (Dso) approximately comprised between 10 and 1000pm, as determined by light scattering measurements. The inorganic filler particles have preferably a density of at least 2.0 g / cm3, typically comprised between 2 g / cm3and 5 g / cm3. The filler particles are typically homogeneously distributed in the granule.

[0070] The inorganic filler may be added in an amount ranging from about 5 wt% to about 60 wt%, preferably from about 5 wt% to about 55 wt%, more preferably from about 10 wt% to about 50 wt%, and still more preferably from about 20 wt% to about 45 wt%, relative to the total weight of the granule..

[0071] It is therefore understood that the composition of the granules can vary depending, on the one hand, on the type of wool used as starting material, either raw wool, or clean wool; and for raw wool also depending on the specific sheep breed used; and, on the other hand, also depending on whether or not the granule also comprises a filler. In a particular embodiment of the invention, the artificial turf infill granule comprises:

[0072] 45-75 wt% of wool fibre; and

[0073] 10-25 wt% of wax; based on the weight of the granule, on the dry basis, typically corresponding to granules made of raw wool, without any additional ingredient, in particular, without any filler material.

[0074] In another particular embodiment of the invention, the artificial turf infill granule comprises:

[0075] 70-90 wt% of wool fibre; and

[0076] 10-30 wt% of wax; based on the weight of the granule, on the dry basis, typically corresponding to granules made of clean wool and a wax, without any filler material. Typically, the granule do not comprise any additional ingredient, and the granule essentially consists of wool fibre and wax, as above defined.

[0077] In another particular embodiment of the invention, the artificial turf infill granule comprises:

[0078] 20-70 wt% of wool fibre;

[0079] 5-20 wt% of a wax; and

[0080] 5-55 wt% of inorganic filler; based on the weight of the granule, on the dry basis, typically corresponding to granules made of raw wool and an inorganic filler.

[0081] In another particular embodiment of the invention, the artificial turf infill granule comprises:

[0082] 30-85 wt% of wool fibre;

[0083] 10-15 wt% of a wax; and

[0084] 5-55 wt% of inorganic filler; based on the weight of the granule, on the dry basis, typically corresponding to granules made of clean wool, a wax and inorganic filler. Typically, the granule does not comprise any additional ingredient, and the granule essentially consists of wool fibre, wax and inorganic filler, as above defined.

[0085] The shape and dimensions of the granules of the present invention is not critical and may vary, depending on the specific process and apparatus used in its manufacture. For example, the granules may be rounded, disk-shaped or cylindricalshaped, typically, having from about 2 mm to about 6 mm diameter and from about 2 mm to about 6 mm height.

[0086] Optionally, the infill granules according to the present invention can additionally comprise an antimicrobial agent, to provide antimicrobial protection. Any conventional antimicrobial or biocide can be employed, as are well known by the skilled in the art. When granules comprise an antimicrobial agent, it typically amounts to less than 5 wt%, relative to the total weight of the granule, preferably less than 4 wt%, and more preferably less than 3 wt%.

[0087] Wool infill granules

[0088] Another aspect of the present invention is a granule comprising wool fibre and a wax.

[0089] In an embodiment, the granule comprises wool fibre and a wax, wherein the granule does not contain any elastomer or any plastic material. In an embodiment, it also does not contain any compostable polymer.

[0090] In an embodiment, the granule comprises wool fibre, a wax and an inorganic filler.

[0091] In an embodiment the granule comprises wool fibre, a wax, and an inorganic filler, wherein the granule does not contain any elastomer or any plastic material. In an embodiment, it also does not contain any compostable polymer.

[0092] The shape and dimensions of the granules are not critical, and are preferably as hereinabove defined according to the use of the present invention.

[0093] In an embodiment, the granule essentially consists of: i) raw wool or a mixture of clean wool and a wax; ii) an inorganic filler; and iii) optionally, an antimicrobial agent.

[0094] In a particular embodiment, the granule essentially consists of: i) raw wool, in an amount comprised in the range 40-95 wt%, preferably in the range 45-95 wt%, more preferably in the range 50-90 wt%, and still more preferably in the range 55-80 wt%; ii) an inorganic filler, in an amount comprised in the range 5-60 wt%, preferably in the range 5-55 wt%, more preferably in the range 10-50 wt%, and still more preferably in the range 20-45 wt%; and iii) an antimicrobial agent, in an amount comprised in the range 0-4 wt%, wherein the percentages are relative to the total weight of the granule, and wherein sum of all percentages amounts to 100%.

[0095] In a particular embodiment, the granule essentially consists of: i) clean wool, in an amount comprised in the range 35-80 wt%; ii) a wax, in an amount comprised in the range 10-30 wt%; iii) an inorganic filler, in an amount comprised in the range 10-55 wt%; and iv) an antimicrobial agent, in an amount comprised in the range 0-4 wt%, wherein the percentages are relative to the total weight of the granule, and wherein the sum of all percentages amounts to 100%.

[0096] The characteristics of the granule, including the wax component and the inorganic filler component are the same as hereinabove defined, according to the use of the present invention.

[0097] In another embodiment, the granule essentially consists of: i) a mixture of clean wool and a wax; and ii) optionally an antimicrobial agent.

[0098] In a more particular embodiment, the wax is selected from the group consisting of beeswax, spermaceti, carnauba wax, candelilla wax, rice bran wax, ouricury wax, myrica wax, esparto wax, Chinese wax, shellac, vegetable stearin, paraffin, microcrystalline wax, polyethylene wax, and mixtures thereof.

[0099] In a particular embodiment, the granule essentially consists of: i) clean wool, in an amount comprised in the range 60-90 wt%, preferably in the range 70-85 wt%; ii) a wax, in an amount comprised in the range 10-40 wt%, preferably in the range 15-30 wt%; and iii) an antimicrobial agent, in an amount comprised in the range 0-4 wt%, wherein the percentages are relative to the total weight of the granule, and wherein sum of all percentages amounts to 100%.

[0100] In a more particular embodiment, the wax is selected from the group consisting of beeswax, spermaceti, carnauba wax, candelilla wax, rice bran wax, ouricury wax, myrica wax, esparto wax, Chinese wax, shellac, vegetable stearin, paraffin, microcrystalline wax, polyethylene wax, and mixtures thereof.

[0101] Granule manufacture

[0102] Another aspect of the present invention is a process for the manufacture of the artificial turf infill granule according to the present invention.

[0103] Another aspect of the invention is the granule obtainable according to this process.

[0104] Another aspect of the invention is the use of the obtained granule as infill for artificial turf. The process comprises pelletizing a mixture comprising wool fibre, a wax and water.

[0105] For optimal granule formation, a certain content of water is required, for example, from about 5 wt% to about 15 wt%.

[0106] Raw wool provides the necessary amount of wool fibre and wax, necessary for manufacturing the granules. Conveniently, raw wool also typically provides the suitable amount of moisture, associated to the protein fibres, and, consequently, also no extra water is usually required for preparing the granules.

[0107] In a preferred embodiment of the invention, therefore, the granules are prepared using raw wool as starting material.

[0108] Therefore, in an embodiment of the invention, the process comprises pelletizing raw wool.

[0109] Raw wool can be, for example, from Merino or Crossbred sheep breeds, among many other possible wool sources. Any raw wool comprising at least 30 wt% wool fibre can be suitable to prepare the infill according to the present invention.

[0110] In an embodiment, raw wool is from Merino.

[0111] In another embodiment clean wool is used as starting material. Clean wool also typically contains the necessary moisture for the pelletizing process, but in this case an external wax must be added.

[0112] Therefore, in another embodiment, the process comprises pelletizing a mixture comprising clean wool and a wax.

[0113] In a particular embodiment, the process comprises pelletizing a mixture essentially consisting of: i) clean wool, in an amount comprised in the range 60-90 wt%, preferably in the range 70-85 wt%; ii) a wax, in an amount comprised in the range 10-40 wt%, preferably in the range 15-30 wt%; and iii) an antimicrobial agent, in an amount comprised in the range 0-4 wt%, wherein the percentages are relative to the total weight of the granule, and wherein sum of all percentages amounts to 100%.

[0114] The term clean wool refers to scoured raw wool, i.e., where fat and other impurities of raw wool have been removed and is mainly composed of wool fibre. The term clean wool includes the wool directly obtained after scouring raw wool, as well as processed wool fabrics, i.e., recycled wool from wool consumer products.

[0115] In another embodiment, the granules according to the present invention additionally contain an inorganic filler. In this case, and depending on the proportion of filler, external water and / or additional wax may be needed to prepare the granules. In an embodiment, the process comprises pelletizing a mixture comprising wool fibre, a wax, an inorganic filler and water.

[0116] In a particular embodiment, the granules according to the present invention comprise an inorganic filler and are prepared using raw wool and, wherein the process comprises pelletizing a mixture comprising raw wool and an inorganic filler.

[0117] In a particular embodiment, the process comprises pelletizing a mixture consisting of raw wool, an inorganic filler, optionally water, optionally a wax and optionally an antimicrobial agent.

[0118] In a particular embodiment, the process comprises pelletizing a mixture essentially consisting of: i) raw wool, in an amount comprised in the range 40-95 wt%, preferably in the range 45-95 wt%, more preferably in the range 50-90 wt%, and still more preferably in the range 55-80 wt%; ii) an inorganic filler, in an amount comprised in the range 5-60 wt%, preferably in the range 5-55 wt%, more preferably in the range 10-50 wt%, and still more preferably in the range 20-45 wt%; and iii) an antimicrobial agent, in an amount comprised in the range 0-4 wt%, wherein the percentages are relative to the total weight of the granule, and wherein sum of all percentages amounts to 100%.

[0119] In another embodiment, the granules according to the present invention comprise an inorganic filler and are prepared using clean wool, wherein the process comprises pelletizing a mixture comprising clean wool, a wax, and an inorganic filler.

[0120] In a particular embodiment, the process comprises pelletizing a mixture consisting of clean wool, a wax, an inorganic filler, optionally water and optionally an antimicrobial agent.

[0121] In a particular embodiment, the process comprises pelletizing a mixture essentially consisting of: i) clean wool, in an amount comprised in the range 35-80 wt%; ii) a wax, in an amount comprised in the range 10-30 wt%; iii) an inorganic filler, in an amount comprised in the range 10-55 wt%; and iv) an antimicrobial agent, in an amount comprised in the range 0-4 wt%, wherein the percentages are relative to the total weight of the granule, and wherein the sum of all percentages amounts to 100%.

[0122] The necessary amounts of each ingredient will be easily adjusted, to obtain the granules of the invention, as hereinabove defined.

[0123] Suitable filler and wax materials are hereinabove disclosed. The granules may be prepared using a suitable equipment for compressing wool, and other possible additional components, into discrete granules. In particular, a pellet mill may be used.

[0124] Pellet mills are well known in the art, and are commercially available, for example, from the companies CPM (California Pellet Mill Company, Crawfordsville, IN, USA), Andritz, Buhler Holding AG (Uzwil, Switzerland), or Kovo Novak (Cetonice, Czech Republic).

[0125] A pellet mill typically comprises a die, with holes of certain size; one or more rollers, which press wool pieces into the die; and a knife, for cutting pellets of the desired length at the die output. The size of the die holes will determine the size of the obtained granules. Typically, holes of a diameter of from about 2 mm to about 6 mm is used.

[0126] Before pelleting in the pellet mill, the wool material is typically first cut (crushed) into small pieces of regular size, suitable for pelleting, typically, about the same range of the diameter of the holes of the pelleting machine die. This shearing of the wool can be carried out in a wool cutter or wool crusher, as are commercially available, for example, from the company Kovo Novak (Cetonice, Czech Republic).

[0127] When the pellets are made up of raw wool only, the crushed raw wool can be directly fed into the pellet mill. When additional ingredients are required (filler, wax, and / or water), the components are first mixed in a suitable mixer and then sent to the pellet mill.

[0128] The pellets formed are generally warm and soft and typically are spread out on a cooling rack to cool and harden.

[0129] When the pellets are prepared with raw wool, the process may optionally comprise a step of sterilization by heat, either of the pellets once obtained, or of the raw wool material before pelletizing. Said sterilization may be done, for example, with hot air, at about 80°C - 90°C.

[0130] Artificial turf

[0131] The present invention relates to the use of wool granules as infill for artificial turf, i.e. , to be used as infill material in an artificial turf carpet.

[0132] The infill according to the invention can be used in any standard carpet, typically made from polyethylene or polypropylene fibres, for example, and typically having fibre length ranging from about 35 mm to about 60 mm. The wool granules of the invention are particularly suitable to be used as upper infill layer, over a lower sand infill layer. A shockpad can be optionally included beneath the carpet.

[0133] Therefore, another aspect of the invention is an artificial turf comprising the wool infill granules as hereinabove defined. Artificial turf is used for replacing grass, and has therefore the same applications of grass, including landscaping applications, as well as surface for sports, such as football, rugby, tennis, or golf, for example.

[0134] For its use as surface for sports, artificial turf must fulfil some mechanical requirements related to athlete-surface interaction, which are important for sport performance and for the safety of players. Some well-known tests are available to assess the mechanical properties of artificial turf, to reproduce athlete’s contact to the ground.

[0135] Shock absorption (SA, also known as impact absorption or force reduction), vertical deformation (VD) and energy restitution (ER) are the three main attributes of artificial turf, which are considered as measures of impact attenuation. These attributes are of high importance because they are considered to improve player safety in the collision with the ground while walking, running or jumping. These properties are found in the standards enforced by specific sports federations, such as FIFA and World Rugby (WR), as well as in other general standards, for example, the European standard EN-15330-1.

[0136] Shock absorption relates to the peak impact force from a controlled energy falling mass and is expressed as a percent reduction relative to a rigid concrete surface. Vertical deformation relates to the deflection of the surface during the impact. Energy restitution reflects the dynamic interaction between the player and the surface, meaning the energy returned to the individual after the impact.

[0137] The “Artificial Athlete” (or AA) or “Advanced Artificial Athlete” (or AAA) are standard drop tests methods that attempt to reproduce the impact of an athlete’s heel on the surface while running. The Artificial Athlete device typically comprises a release mechanism, a falling mass, an accelerometer, a calibrated linear spring and an impactor. Impact attenuation is performed to obtain measurements of acceleration, which allow to calculate surface parameters such as SA, VD and ER.

[0138] Another useful property of artificial turf is the rotational resistance, which evaluates the turf’s grip, balancing the need for traction without risking player injury from excessive force. The rotational resistance measurement calculates the torque necessary to rotate a loaded object in contact with the surface system being measured. The apparatus used consists of a test foot (a metal disc) with six equally spaced football studs on the base loaded to a mass and using a calibrated torque to record the peak torque moment generated by the surface from manually rotating the disc (in Newton meters, Nm).

[0139] Said apparatuses and test methods are well known in the art, as described, for example, in ASTM F3189-17 (ASTM, 2017), FIFA Test Methods (FIFA, 2015, 2019), CEN / TS 16717 (CEN, 2015) or EN 15330-1 (CEN, 2013) standards, or in Fleming et al., Mechanical testing and characterisation of sports surfaces, in: S.J. Dixon, P. Fleming, I. James, M. Carre (Eds.), The Science and Engineering of Sport Surfaces, 2015, pp. 26-69. The requirements in these tests may differ, according to the different standards, as shown, in the following table for three different standard bodies:

[0140] Concrete soil provides 0% SA, 0% VD and 100% ER. Therefore, it is expected for an artificial turf to increase shock absorption and vertical deformation, and to reduce energy restitution.

[0141] As shown in Tables 1 and 2 of Example 6, the wool infill granules according to the present invention (columns A and B) provide substantial increase in SA and VD and decrease in ER compared to an artificial turf with only silica as infill material (Ref). It is also notable that, in terms of vertical deformation and energy restitution, the infill alone, without shockpad, is sufficient to provide values inside EN 15330-1 and FIFA standards. Furthermore, the infill material performs even better while in use, after simulated rain conditions (column B), compared to the original, dry material (A).

[0142] Surprisingly, the infill according to the present invention, entirely based on wool fibre for providing elasticity, performs outstandingly well and provides the required mechanical properties for infill materials, analogously to those provided by rubber.

[0143] Tables 3 and 4 of Example 7 show the results of mechanical properties testing for an artificial turf comprising infill granules of the invention, comprising an inorganic filler material. Table 3 shows that, with a shockpad, the values of all tested properties (SA, VD and ER) comply with EN 15330-1 and FIFA standards. Even without the shockpad, notably good results were obtained in the rain-simulated conditions, where the values for VD and ER comply with said standards.

[0144] Therefore, another aspect of the invention is the use of wool fibre as the unique elastic material in an artificial turf infill.

[0145] Or, in other words, the present invention provides for use of wool fibre as artificial turf infill, wherein the infill does not contain any additional elastic material, in particular, it does not contain any elastomer.

[0146] The present invention is defined by the following embodiments:

[0147] 1.- Use of a granule comprising wool fibre and a wax as infill for artificial turf, wherein the granule does not contain any elastomer or any plastic material. 2.- Use according to embodiment 1 , wherein the granule does not contain any compostable polymer.

[0148] 3.- Use according to embodiments 1 or 2, wherein the granule essentially consists of: i) raw wool, or a mixture of clean wool and a wax; ii) optionally, an inorganic filler; and iii) optionally, an antimicrobial agent.

[0149] 4.- Use according to embodiment 3, wherein the granule essentially consists of: i) raw wool, or a mixture of clean wool and a wax; ii) an inorganic filler; and iii) optionally, an antimicrobial agent.

[0150] 5.- Use according to any one of embodiments 1 to 4, wherein the granule comprises at least 20 wt% of wool fibre, based on the weight of the granule on dry basis, and wherein the weight ratio wool fibre:wax is comprised between 1.5:1 and 15:1.

[0151] 6.- Use according to embodiment 5, wherein the granule comprises between 20 wt% and 90 wt% of wool fibre, preferably between 25 wt% and 85 wt% of wool fibre, based on the weight of the granule on dry basis, and wherein weight ratio wool fibre:wax is comprised between 1.5:1 and 15:1 , preferably comprised between 2:1 and 10:1 , and more preferably comprised between 3:1 and 8:1.

[0152] 7.- Use according to any one of embodiments 1 to 6, wherein the wax is selected from the group consisting of lanolin, beeswax, spermaceti, carnauba wax, candelilla wax, rice bran wax, ouricury wax, myrica wax, esparto wax, Chinese wax, shellac, vegetable stearin, paraffin, microcrystalline wax, polyethylene wax, and mixtures thereof.

[0153] 8.- Use according to embodiment 7, wherein the wax is selected from the group consisting of lanolin, beeswax, carnauba wax, candelilla wax, paraffin and mixtures thereof, and preferably is selected from the group consisting of lanolin, paraffin and mixtures thereof.

[0154] 9.- Use according to embodiment 8, wherein the wax is lanolin.

[0155] 10.- Use according to any one of embodiments 1 to 9, wherein the granule also comprises an inorganic filler. 11.- Use according to embodiment 10, wherein the granule comprises from about 5 wt% to about 60 wt% of an inorganic filler, preferably from about 5 wt% to about 55 wt% of an inorganic filler, more preferably from about 10 wt% to about 50 wt% of inorganic filler, still more preferably from about 20 wt% to about 45 wt% of inorganic filler, relative to the total weight of the granule..

[0156] 12.- Use according to embodiments 10 or 11 , wherein the inorganic filler is selected from the group consisting of barium sulfate (barite), calcium carbonate, magnesium carbonate, magnesium oxide, silica, modified silica, silicates, chalk, china clay, talc, aluminosilicate, sand, calcium magnesium carbonate (dolomite), limestone, diatomaceous earth, and combinations thereof.

[0157] 13.- Use according to embodiment 12, wherein the inorganic filler is selected from the group consisting of barium sulfate (barite), calcium carbonate and calcium magnesium carbonate (dolomite).

[0158] 14.- Use according to any one of embodiments 1 to 3 or 5 to 9, wherein the granule comprises:

[0159] 45-75 wt% of wool fibre; and

[0160] 10-25 wt% of wax; based on the weight of the granule on the dry basis.

[0161] 15.- Use according to any one of embodiments 1 to 3 or 5 to 9, wherein the granule comprises:

[0162] 70-90 wt% of wool fibre; and

[0163] 10-30 wt% of a wax; based on the weight of the granule on the dry basis.

[0164] 16.- Use according to any one of embodiments 10 to 13, wherein the granule comprises:

[0165] 20-70 wt% of wool fibre;

[0166] 5-20 wt% of a wax; and

[0167] 5-55 wt% of inorganic filler; based on the weight of the granule on the dry basis.

[0168] 17.- Use according to any one of embodiments 10 to 13, wherein the granule comprises: 30-85 wt% of wool fibre; 10-15 wt% of a wax; and

[0169] 5-55 wt% of inorganic filler; based on the weight of the granule on the dry basis.

[0170] 18.- Use of raw wool for preparing an infill for artificial turf, wherein the infill does not contain any elastomer or any plastic material.

[0171] 19.- Use of wool fibre as the unique elastic material in an artificial turf infill.

[0172] 20.- Use according to embodiments 1 or 2, wherein the granule comprises raw wool.

[0173] 21.- Artificial turf infill granule comprising wool fibre, a wax, and an inorganic filler, wherein the granule does not contain any elastomer or any plastic material.

[0174] 22.- Artificial turf infill granule according to embodiment 21 , wherein the granule does not contain any compostable polymer.

[0175] 23.- Artificial turf infill granule according to embodiments 21 or 22, wherein the granule essentially consists of: i) raw wool or a mixture of clean wool and a wax; ii) an inorganic filler; and iii) optionally, an antimicrobial agent.

[0176] 24.- Artificial turf infill granule according to any one of embodiments 21 to 23, wherein the granule essentially consists of: i) raw wool, in an 40-95 wt%, preferably in the range 45-95 wt%, more preferably in the range 50-90 wt%, and still more preferably in the range 55-80 wt%; ii) an inorganic filler, in an amount comprised in the range 5-60 wt%, preferably in the range 5-55 wt%, more preferably in the range 10-50 wt%, and still more preferably in the range 20-45 wt%; and iii) an antimicrobial agent, in an amount comprised in the range 0-4 wt%, wherein the percentages are relative to the total weight of the granule, and wherein the sum of all percentages amounts to 100%.

[0177] 25.- Artificial turf infill granule according to any one of embodiments 21 to 23, wherein the granule essentially consists of: i) clean wool, in an amount comprised in the range 35-80 wt%; ii) a wax, in an amount comprised in the range 10-30 wt%; iii) an inorganic filler, in an amount comprised in the range 10-55 wt%; and iv) an antimicrobial agent, in an amount comprised in the range 0-4 wt%, wherein the percentages are relative to the total weight of the granule, and wherein the sum of all percentages amounts to 100%.

[0178] 26.- Artificial turf infill granule according to any one of embodiments 21 to 25, wherein the inorganic filler is selected from the group consisting of barium sulfate (barite), calcium carbonate, magnesium carbonate, magnesium oxide, silica, modified silica, silicates, chalk, china clay, talc, aluminosilicate, sand, calcium magnesium carbonate (dolomite), limestone, diatomaceous earth, and mixtures thereof.

[0179] 27.- Artificial turf infill granule according to embodiment 26, wherein the inorganic filler is selected from the group consisting of barium sulfate (barite), calcium carbonate and calcium magnesium carbonate (dolomite), and mixtures thereof.

[0180] 28.- Artificial turf infill granule essentially consisting of: i) a mixture of clean wool and a wax; and ii) optionally an antimicrobial agent.

[0181] 29.- Artificial turf infill granule according to embodiment 28, wherein the granule essentially consists of: i) clean wool, in an amount comprised in the range 60-90 wt%, preferably in the range 70-85 wt%; ii) a wax, in an amount comprised in the range 10-40 wt%, preferably in the range 15-30 wt%; and iii) an antimicrobial agent, in an amount comprised in the range 0-4 wt%, wherein the percentages are relative to the total weight of the granule, and wherein the sum of all percentages amounts to 100%.

[0182] 30.- Artificial turf infill granule according to any one of embodiments 21 to 29, wherein the wax is selected from the group consisting of lanolin, beeswax, spermaceti, carnauba wax, candelilla wax, rice bran wax, ouricury wax, myrica wax, esparto wax, Chinese wax, shellac, vegetable stearin, paraffin, microcrystalline wax, polyethylene wax, and mixtures thereof.

[0183] 31.- Artificial turf infill granule according to embodiment 30, wherein the wax is selected from the group consisting of lanolin, beeswax, carnauba wax, candelilla wax, paraffin and mixtures thereof, and preferably is selected from the group consisting of lanolin, paraffin and mixtures thereof.

[0184] 32.- Artificial turf infill granule according to embodiment 31, wherein the wax is lanolin.

[0185] 33.- Artificial turf infill granule according to embodiments 28 or 29, wherein the wax is selected from the group consisting of beeswax, spermaceti, carnauba wax, candelilla wax, rice bran wax, ouricury wax, myrica wax, esparto wax, Chinese wax, shellac, vegetable stearin, paraffin, microcrystalline wax, polyethylene wax, and mixtures thereof.

[0186] 34.- Artificial turf comprising the infill granules as defined in any one of embodiments 1 to 17

[0187] 35.- Artificial turf comprising the infill granules according to any one of embodiments 21 to 33.

[0188] 36.- Process for the preparation of the artificial turf infill granule according to any one of embodiments 21 to 33, wherein the process comprises pelletizing a mixture comprising wool fibre, a wax and water.

[0189] 37.- Process for the preparation of the artificial turf infill granule according to any one of embodiments 21 to 27 and 30 to 32, wherein the process comprises pelletizing a mixture comprising wool fibre, a wax, an inorganic filler and water.

[0190] 36.- Process according to embodiment 35, wherein the process comprises: a) pelletizing a mixture comprising raw wool and an inorganic filler; or b) pelletizing a mixture comprising clean wool and a wax; or c) pelletizing a mixture comprising clean wool, a wax and an inorganic filler.

[0191] Examples

[0192] Example 1.- Infill granules prepared with raw wool

[0193] Granules were prepared using raw wool from Merino sheep as unique ingredient.

[0194] The raw wool was first cut into pieces using a wool cutter SG2028W and vacuum FT101 (Kovo Novak, Cetonice, Czech Republic) and the granules were prepared using a pellet mill equipment BN 100W (Kovo Novak, Cetonice, Czech Republic). The diameter of holes in the die of the pelleting machine was 6.0 mm.

[0195] The dimensions of obtained granules were 4-6 mm diameter and 4-6 mm long.

[0196] The obtained granules were subjected to thermogravimetric analysis (TGA). The samples were conditioned at 50% relative humidity and 20°C prior to analysis. TGA was performed in a Mettler-Toledo TGA / SDTA 840 using samples of about 5 mg placed in completely open aluminium pans. Tests were conducted from 25°C to 850°C at 10°C / min, first under N2, and changing to O2 at 600 °C, at a flux of 60 mL / min. The results of the test are shown in the following table:

[0197] The results of the TGA test match those expected, according to the composition of Merino wool.

[0198] Example 2.- Infill granules prepared with clean wool

[0199] Granules were prepared using clean wool from Merino sheep. Thermogravimetric analysis of clean wool was performed, in the same conditions discussed above in Example 1 . The results are shown in the following table:

[0200] The results of the TGA test match the expected higher proportion of wool protein fibres and minimum amount of impurities.

[0201] The granules were prepared according to the following composition:

[0202] The same cutter and mill equipment described in Example 1 were used for preparing the granules. In this case, clean wool was first cut into pieces, mixed with lanolin, and the mixture was introduced in the pellet mill. The dimensions of the obtained granules were 4-6 mm diameter and 4-6 mm long. Example 3.- Infill granules prepared with raw wool and barium sulfate

[0203] Granules were prepared using raw wool from Merino sheep and barium sulfate (Thermo Fisher Scientific) as inorganic filler.

[0204] The granules were prepared according to the following composition:

[0205] The same cutter and pellet mill equipment described in Example 1 were used for preparing the granules. The raw wool was first cut into pieces and introduced in the pellet mill. The dimensions of obtained granules were 4-6 mm diameter and 4-6 mm long.

[0206] Example 4.- Infill granules prepared with clean wool and barium sulfate

[0207] Granules were prepared using clean wool from Merino sheep, as in Example 2. In this case, barium sulfate (Thermo Fisher Scientific) was added as inorganic filler.

[0208] The granules were prepared according to the following composition:

[0209] The same cutter and pellet mill equipment disclosed in Example 1 were used for preparing the granules. Clean wool was first cut into pieces, mixed with lanolin and barium sulfate, and introduced in the pellet mill. The dimensions of obtained granules were 4-6 mm diameter and 4-6 mm long.

[0210] Example 5.- Infill granules prepared with raw wool and filler

[0211] Granules were prepared using raw wool from Merino sheep and either barium sulfate (barite, density 4.4 g / cm3, Thermo Fisher Scientific) or calcium magnesium carbonate (dolomite, density 2.8 g / cm3, Thermo Fisher Scientific).

[0212] Granules were prepared according to the following composition: Raw wool was first cut into pieces, in the same way as described in Example 1 . The crushed wool was mixed with the inorganic filler, and the mixture was pelletized using the same pellet mill equipment described in Example 1.

[0213] The dimensions of the obtained granules were 4-6 mm diameter and 4-6 mm long.

[0214] Example 6.- Performance of the infill according to the invention (Example 1}

[0215] Several mechanical properties of an artificial turf comprising the infill according to the present invention were assessed.

[0216] To this end, several artificial turf samples were prepared using an artificial turf carpet (RGF XM7 60-10.5 Field Turf), and having a surface of a DinA4 (0.062 m2). Each artificial turf sample was filled with 1.5 Kg of silica (Silica Sand RP-0508, Euroarce, Spain), as the first layer infill. Additionally, to each sample, an upper infill layer was added, composed of:

[0217] - A: 200 g of the infill granules prepared in Example 1

[0218] B: 200 g of the infill granules prepared in Example 1 , treated with 300 mL of water (5 L / m2), and allowed to dry for 5 days.

[0219] Sample “Ref” (reference) contained no additional upper layer infill, but only silica.

[0220] Shock absorption (SA), vertical deformation (VD) and energy restitution (ER) tests were performed with an Advanced Artificial Athlete device (Deltec Equipment, Segment 23 6921 RC Duiven, The Netherlands). The device was provided with a 20 Kg dropping mass, falling from a 56 mm height as described in EN 15330-1.

[0221] Rotational resistance test was performed with a Rotational Traction Athlete (RTA) apparatus provided by (Labosport Group, Le Mans, France).

[0222] Concrete was also directly evaluated, providing 0% impact absorption, 0% of vertical deformation, and 100% of energy of restitution.

[0223] Table 1 shows the results of the assays performed when a shockpad (ProPlay Sport, Schmitz Foam Products, of 23 mm) was placed below the artificial turf samples.

[0224] Table 2 shows the results of the assays when the samples were directly placed on the concrete floor, without any shockpad in between.

[0225] For impact absorption, vertical deformation and energy restitution, 3 measures were performed for each sample, excluding the first measure and calculating the average of the second and third measure.

[0226] 'ABLE 1

[0227] 'ABLE 2

[0228] Example 7.- Performance of the infill according to the invention (Example 5)

[0229] The mechanical properties of an artificial turf comprising the infill granules prepared in Example 5 (Examples 5-a and 5-b, with different proportions of dolomite) were assessed.

[0230] 4 artificial turf samples were prepared using an artificial turf carpet (RGF XM7 60-10.5 Field Turf), and having a surface of a DinA4 (0.062 m2). Each artificial turf sample was filled with 1.5 Kg of silica (Silica Sand RP-0508, Euroarce, Spain), as the first layer infill. Additionally, to each sample, an upper infill layer was added, composed of:

[0231] C: 270 g of the infill granules of Example 5-a

[0232] D: 270 g of the infill granules of Example 5-a, treated with 300 mL of water (5 L / m2), and allowed to dry for 10 days

[0233] E: 400 g of the infill granules of Example 5-b

[0234] F: 400 g of the infill granules of Example 5-b, treated with 300 mL of water (5 L / m2), and allowed to dry for 10 days

[0235] Shock absorption (SA), vertical deformation (VD) and energy restitution (ER) tests were performed with an Advanced Artificial Athlete device (Deltec Equipment, Segment 23 6921 RC Duiven, The Netherlands). The device was provided with a 20 Kg dropping mass, falling from a 56mm height as described in EN 15330-1. Table 3 shows the results of the assays performed when a shockpad (ProPlay Sport, Schmitz Foam Products, of 23 mm) was placed below the artificial turf samples.

[0236] Table 4 shows the results of the assays when the samples were directly placed on the concrete floor, without any shockpad in between.

[0237] 3 measures were performed for each sample, excluding the first measure and calculating the average of the second and third measure.

[0238] TABLE 3 It can be observed that all the samples, either dry or wet, fulfilled EN 15330-

[0239] 1 and FIFA standards.

[0240] TABLE 4 In this case, without the shockpad, wet samples (samples D and F) fulfilled the standards for VD and ER.

Claims

1 .- Use of a granule comprising wool fibre and a wax as infill for artificial turf, wherein the granule does not contain any elastomer or any plastic material.2.- Use according to claim 1 , wherein the granule consists of: i) raw wool, or a mixture of clean wool and a wax; ii) optionally, an inorganic filler; and iii) optionally, an antimicrobial agent.3.- Use according to claims 1 or 2, wherein the granule comprises between 20 wt% and 90 wt% of wool fibre, preferably between 25 wt% and 85 wt% of wool fibre, based on the weight of the granule on dry basis, and wherein weight ratio wool fibre:wax is comprised between 1.5:1 and 15:1 , preferably comprised between 2:1 and 10:1 , and more preferably comprised between 3:1 and 8:1.4.- Use according to any one of claims 1 to 3, wherein the wax is selected from the group consisting of lanolin, beeswax, spermaceti, carnauba wax, candelilla wax, rice bran wax, ouricury wax, myrica wax, esparto wax, Chinese wax, shellac, vegetable stearin, paraffin, microcrystalline wax, polyethylene wax, and mixtures thereof, and preferably is lanoline.5.- Use according to any one of claims 1 to 4, wherein the granule also comprises an inorganic filler.6.- Use according to claim 5, wherein the granule comprises from 5 wt% to 55 wt% of an inorganic filler, preferably from 10 wt% to 50 wt% of inorganic filler, more preferably from 20 wt% to 45 wt% of inorganic filler, relative to the total weight of the granule.7.- Use according to claims 5 or 6, wherein the inorganic filler is selected from the group consisting of barium sulfate (barite), calcium carbonate, magnesium carbonate, magnesium oxide, silica, modified silica, silicates, chalk, china clay, talc, aluminosilicate, sand, calcium magnesium carbonate (dolomite), limestone, diatomaceous earth, and combinations thereof.8.- Use of raw wool for preparing an infill for artificial turf, wherein the infill does not contain any elastomer or any plastic material.9.- Artificial turf infill granule comprising wool fibre, a wax, and an inorganic filler, wherein the granule does not contain any elastomer or any plastic material.10.- Artificial turf infill granule according to claim 9, wherein the granule consists of: i) raw wool or a mixture of clean wool and a wax; ii) an inorganic filler; and iii) optionally, an antimicrobial agent.11.- Artificial turf infill granule according to claims 9 or 10, wherein the granule consists of: i) raw wool, in an amount comprised in the range 45-95 wt%, preferably in the range 50-90 wt%, and more preferably in the range 55-80 wt%; ii) an inorganic filler, in an amount comprised in the range 5-55 wt%, preferably in the range 10-50 wt% and more preferably in the range 20-45 wt%; and iii) an antimicrobial agent, in an amount comprised in the range 0-4 wt%, wherein the percentages are relative to the total weight of the granule, and wherein the sum of all percentages amounts to 100%.12.- Artificial turf infill granule according to claims 9 or 10, wherein the granule consists of: i) clean wool, in an amount comprised in the range 35-80 wt%; ii) a wax, in an amount comprised in the range 10-30 wt%; iii) an inorganic filler, in an amount comprised in the range 10-55 wt%; and iv) an antimicrobial agent, in an amount comprised in the range 0-4 wt%, wherein the percentages are relative to the total weight of the granule, and wherein the sum of all percentages amounts to 100%.13.- Artificial turf infill granule according to any one of claims 9 to 12, wherein the wax is selected from the group defined in claim 4 and the inorganic filler is selected from the group defined in claim 7.14.- Process for the preparation of the artificial turf infill granule according to any one of claims 9 to 13, wherein the process comprises pelletizing a mixture comprising wool fibre, a wax, an inorganic filler and water.15.- Artificial turf comprising the infill granules as defined in any one of claims 1 to 7 or the infill granules of any one of claims 9 to 13.

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