Method of making artificial turf and artificial turf made thereof

Abstract

A method for making an artificial turf, the method comprising: providing a carrier (308) and an artificial turf fiber (501) incorporated into the carrier such that a first portion of the artificial turf fiber (506) protrudes to a back side of the carrier, a second portion of the artificial turf fiber (302) protrudes to a front side of the carrier, and a third portion of the artificial turf fiber (504) is inside the carrier; preparing a polyurethane (PU) foam reaction mixture (210) containing a reactive foam stabilizer (RFS), applying the PU foam reaction mixture on the back side of the carrier (308) to cover the artificial turf fiber (506) protruding to the back side of the carrier (308) and hardening the PU foam reaction mixture to form a flexible PU backing securing the turf fiber in place.

Description

[0001] METHOD OF MAKING ARTIFICIAL TURF AND ARTIFICIAL TURF MADE THEREOF

[0002] Field of the invention

[0003] The invention relates generally to a method for making an artificial turf, and the artificial turf made by this method.

[0004] Background and related art

[0005] Use of artificial turf is increasing because it is easier to maintain than natural turf and its surface characteristics are in many respects better than those of natural turf. Typically, artificial turf is manufactured by extruding a thermoplastic resin to produce artificial turf fiber which is attached on a carrier via a process known as tufting. The polymer fibers on the surface of the artificial turf are in the form of loops or individual needles often referred to as blades or piles. Often, a polymer resin is applied on the back side of the carrier for enhancing the structural stability and the pile pulling characteristics of the artificial turf. Artificial turf is used in many applications including household floor matting, playing surface for sports such as soccer, football, rugby, tennis, golf, exercise fields, landscaping applications and the like.

[0006] Often, Polyurethane (PU) is used as a polymer resin that is applied on the back side of the carrier. The PU can be a reaction product of a polyol component and an isocyanate component. The polyol component can comprise bio-based polyols.

[0007] DE 199 47 563 Al relates to a method for preparing bio-based polyols utilizing either alkali metal hydroxide or alkaline earth metal hydroxide as a catalyst in a transesterification of castor oil with other vegetable oils.

[0008] DE 198 39 029 Al relates to a polyol mixture with 4 components, wherein transesterified or alkoxylated castor oil is one component. The transesterification of castor oil is carried out using dibutyltin dilaureat or an amine as a catalyst for the transesterification process.

[0009] The production of artificial turf fibers often turns out to be a technical challenge, as various problems can occur which may affect the quality of the artificial turf. Hence, further improvements are needed in the manufacturing process for providing artificial turf surfaces with satisfactory performance characteristics.

[0010] Summary of the Invention

[0011] The invention provides for a method of manufacturing an artificial turf and an artificial turf made by the manufacturing method as specified in the independent claims. Embodiments are given in the dependent claims. Embodiments and examples disclosed herein may be freely combined with each other if they are not mutually exclusive.

[0012] An aspect of the invention is directed to a method for making an artificial turf, the method comprising: providing a carrier and an artificial turf fiber incorporated into the carrier. The fiber may be preferably incorporated inside the carrier such that a first portion of the artificial turf fiber protrudes to a back side of the carrier, a second portion of the artificial turf fiber protrudes to a front side of the carrier, and a third portion of the artificial turf fiber is inside the carrier. The method further comprises preparing a polyurethane (PU) foam reaction mixture and applying the PU foam reaction mixture on the back side of the carrier to cover the artificial turf fiber (506) protruding to the back side of the carrier and allowing the PU foam reaction mixture to harden to form a flexible PU backing securing the turf fiber in place. The PU foam reaction mixture contains a reactive foam stabilizer (RFS) for stabilizing the PU foam reaction mixture.

[0013] The PU backing obtained by the inventive method may have the following advantages:

[0014] • improved tensile strength and improved tuft bind (also known as tuft lock), thus imparting improved properties for the artificial turf.

[0015] • satisfactory tuft bind with less PU backing.

[0016] • high dimensional stability, thus making a particularly dimensionally stable artificial turf that expands or contracts less with large temperature differences that occur frequently in outdoor areas.

[0017] • achieving a desired degree of dimensional stability or elasticity with significantly less PU mass, because the viscosity of the liquid PU reaction mixture, which is actually a foam, is significantly increased in this special formulation, so that the foam is better stabilized until it has hardened / cured / completed reacting into the PU-matrix. The foam does not collapse as quickly because of the increased viscosity.

[0018] Also, due to the improved stability of the PU reaction mixture foam until the PU reaction mixture hardens, more additives, especially pigments, can be added to the back coating without the foam collapsing. Furthermore, an improved, homogeneous mixing of the back coating reaction compound with the pigments is made possible and segregation of the heavy pigments because of gravity is significantly reduced or prevented. Use of the RFS further allows forming a stable PU reaction mixture foam even when the PU reaction mixture may comprise impurities or polyol compounds of the type which may destabilize the PU foam. This is particularly beneficial for allowing the use of bio-based polyols which have been observed to be linked to less stable PU foam;

[0019] The RFS may be bio-based and may be at least one of the following substances: a polyester polyol, in particular a polyester diol or polyester triol, based on soybean oil, and / or castor oil, and / or a fat in the form of an ester of a triol with a fatty acid, in particular a triglyceride, and more in particular castor oil, and / or soybean oil.

[0020] Although the inventors do not wish to be bound by theory, it is postulated that the RFS stabilizes the PU foam reaction mixture via hydrogen bonding. This way higher viscosity in the PU foam reaction mixture is possible without higher compound viscosity.

[0021] In an embodiment, the RFS may be chemically modified for increasing the number of hydroxyl groups so that more covalent bonds are created with the PU matrix.

[0022] The RFS may be added to the PU foam reaction mixture in one of the components of the PU foam reaction mixture including the polyol, the isocyanate, or an additive. Preferably, the RFS is added within a color paste additive that is added in the reaction mixture. More preferably, the RFS is added in the reaction mixture before the isocyanate component has been added in the reaction mixture. It has been found that adding the RFS in the reaction mixture before the isocyanate compound has been added in the reaction mixture is beneficial because it allows for improved control of the viscosity of the reaction mixture and may prevent an excessive increase in the viscosity of the reaction mixture.

[0023] In an embodiment, the color paste may comprise of 7% to 60 %, or 10% to 50%, or 15% to 45%, or 20% to 40%, or 25% to 30% by weight pigment (also referred to as color), and 40% to 93%, or 50% to 90%, or 55% to 85%, or 60% to 80%, or 70% to 75% RFS.

[0024] The PU foam reaction mixture applied to the carrier may comprise of 1 to 9, or 2 to 6, or 3-5 parts by weight of the color paste, 70 to 120, or 80 to 110, or 90 to 110 parts by weight of a polyol blend, and 7 to 21, or 10 to 18, or 12 to 16 parts by weight of isocyanate. Polyol blend refers to a polyol compounded with a filler and in some embodiments with a chain extender.

[0025] In an embodiment, the PU foam reaction mixture applied to the carrier may comprise 3 parts by weight of the color paste, 100 parts by weight of the polyol blend and 14 parts by weight of isocyanate.

[0026] The part ratios of the polyol component and isocyanate component may vary depending on the type of polyol or isocyanate used.

[0027] The polyol blend may comprise from 30 to 80 wt% filler and from 70 to 20 wt% polyol. In an embodiment, the polyol blend may comprise one part of a polyol and two parts filler. The polyol and the filler may be compounded together before added to the PU reaction mixture. In an embodiment, the polyol blend may further include a chain extender.

[0028] Preparing the PU foam reaction mixture may further comprise adding to the compounded polyol with the filler, a color paste with the RFS and an isocyanate to form a viscous mixture.

[0029] In an embodiment, the preparation of the PU foam reaction mixture may comprise first compounding the polyol with the filler, and then adding the color paste with the RFS dispersed in the color paste in a manifold of a polyurethane machine. The manifold may then unify the compounded material (polyol with the filler) with the added color paste (with the RFS) and optionally any added surfactant / catalyst (if appropriate). Pressurized air for mechanical foam creation (or frothing) may be injected in the manifold. The manifold may lead to a mixing head where the isocyanate is added to produce the PU foam reaction mixture.

[0030] One or more additives may be added in the mixture while mixing to form a homogeneous stable foam reaction mixture, and the homogeneous stable foam reaction mixture may be then applied on the back side of a carrier and allowed to solidify to form the backing of an artificial turf. The RFS is used in an effective amount to adequately stabilize the PU foam reaction mixture, thus forming a homogeneous PU backing that stays homogeneous till the hardening of the PU foam reaction mixture. The stabilized PU foam may also prevent any settling of any of the additives.

[0031] In an embodiment, the PU foam reaction mixture may further comprise a transesterified biobased polyester polyol component. The transesterified bio-based polyester polyol component may comprise a first fatty acid bound by an ester bound to an alcohol molecule backbone. The transesterified bio-based polyester polyol component may be an enzymatically transesterified derivative of a first natural fatty acid-containing ester. The first natural fatty acid-containing ester being in particular a triglyceride, in particular ricinolein.

[0032] In the following ricinolein is used as an example of the first natural fatty acid-containing ester. This is for illustrative purposes only and does not restrict the first natural fatty acid-containing ester to ricinolein.

[0033] Adding a transesterified bio-based polyester polyol component may be advantageous because it may enhance biodegradability and lower toxicity. Additionally, due to its narrow weight distribution and chemical uniformity, especially compared to physical mixtures of different polyols, the enzymatically transesterified derivative of a natural fatty acidcontaining ester may improve the consistency and predictability of the performance characteristics in the polyurethane foam and therefore of the artificial turf itself. This also holds true when compared to bio-based polyester polyols derived from a thermal transesterification that uses heat and / or non-enzymatic catalysts. Such thermal processes often lead to a broad range of heterogeneous mixture of products, where the distribution of product concentrations typically exhibits a broad Gaussian distribution rather than the narrow range of reaction products produced by enzymatic transesterification due to their high selectivity, which can be demonstrated, for example, by mass spectrometry. This uniformity is crucial for maintaining the quality and durability of the artificial turf across different batches and production runs. Moreover, the specific nature of the enzymatic transesterification allows for the creation of tailored polyester polyol molecules that can be engineered to optimize the physical properties of the artificial turf, such as elasticity, UV resistance, and wear resistance, thereby enhancing the overall user experience and lifespan of the artificial turf.

[0034] Using ricinolein, the triglyceride of ricinoleic acid and the chief constituent of castor oil, as the first natural fatty acid-containing ester, may particularly be advantageous, since it may provide the chemical functionality needed for polyurethane reactions due to its hydroxyl group on the ricinoleic acid chain. This hydroxyl group introduces additional reactivity, allowing for cross-linking possibilities which can enhance the mechanical strength and thermal stability of the resulting polyurethane.

[0035] In an embodiment, the reaction components of the enzymatic transesterification reaction of the first natural fatty acid-containing ester may include a second natural fatty acid-containing ester. The second natural fatty acid-containing ester being in particular a triglyceride, in particular a triglyceride comprised in soybean oil, linseed oil or tung oil. This may be advantageous because these oils are readily available in large quantities, thereby reducing costs. Additionally, it allows for introducing a diversity of fatty acids, which enables tailoring the properties of the resulting polyurethane without increasing toxicity, given the non-toxic nature of these oils.

[0036] In an embodiment to this, the first fatty acid comprises at least one hydroxyl group and throughout the enzymatic transesterification the first fatty acid is substituted with a second fatty acid of the second natural fatty acid-containing ester, wherein the second fatty acid comprises fewer hydroxyl groups than the first fatty acid. This may be advantageous because it reduces the total number of hydroxyl groups available for a cross-linking reaction, therefore potentially decreasing the cross-link density of the resulting polyurethane. This reduction in cross-link density can lead to a polyurethane that is more flexible and has improved elongation properties which are desirable characteristics for artificial turf where durability under physical stress is required. By adjusting the mixing ratio of, for example, castor oil and soybean oil, the soybean oil containing only fatty acids without hydroxyl groups, the total number of hydroxyl groups available for a cross-linking reaction and thus the cross-link density of the resulting polyurethane can be reliably controlled.

[0037] In an embodiment, the first natural fatty acid-containing ester is ricinolein and the second functional fatty acid is selectively introduced at the sn-1 position and / or the sn-3 position of the ricinolein. This selective substitution may be advantageous because it may precisely alter the functionality and reactivity of the polyester polyol due to the strategic placement of fatty acids with different chemical properties. By modifying these specific positions on the glycerol backbone, the resulting polyester polyol may exhibit tailored physical and chemical characteristics. This includes adjustments in the hydrophilic-hydrophobic balance, which can significantly influence the resulting polyurethane's water absorption, mechanical strength, and thermal stability. In particular, if the sn-2 position remains unsubstituted, the transesterified ricinolein can bond to the PU backbone during the polymerization reaction and act as a plasticizer due to weakening the intermolecular forces within the PU. Due to the covalent bond to the backbone of the PU, the probability of migration outside the PU matrix is drastically reduced or prevented, therefore leading to improved stability and longevity of the polyurethane under various environmental conditions. This advantage becomes even more apparent when this PU, equipped with side chains that act as plasticizers, is compared with a PU in which plasticizers are introduced in a non-covalently bound form and can, under certain conditions, leach from the PU due to migration, significantly altering the mechanical properties of the PU.

[0038] In an embodiment, the second fatty acid introduced has a chain length from 8 to 22 carbon atoms, in particular 10 to 20 carbon atoms, in particular 14 to 18 carbon atoms. This specific range of chain length may be advantageous, because it may keep the elasticity, flexibility and hardness of the resulting PU in a range which is favored for artificial turf. If the chains are longer, the increased van der Waals forces between the molecules could make the polyurethane too stiff, reducing its ability to cushion and absorb impacts effectively, which is critical for sports and recreational activities on artificial turf. Conversely, if the chains are too short, the material might not provide sufficient wear resistance and durability, leading to quicker degradation of the artificial turf under mechanical and environmental stress. Also, longer chains reduce the tendency to migrate in the PU if the respective triglyceride is not covalently bound to the backbone of the PU.

[0039] Besides the chain length, the physicochemical makeup of the fatty acids can be used to adjust the physical properties of the finished backing and its adhesion to different substrates. For instance, oleic or stearic acid could enhance tensile strength due to its ability to form denser, more uniform networks within the polyurethane matrix, while linoleic acid might improve elasticity due to its cis-double bonds which create kinks in the fatty acid chains, reducing intermolecular forces and increasing flexibility. Another example is palmitic acid which could increase the water resistance of the finished backing due to its saturated nature and long carbon chain, which provide a barrier effect against moisture penetration. Also, polar groups (e.g., carboxyl or ester groups) due to their ability to form hydrogen bonds with other polymer chains or substrates can increase the adhesion and cross-link density. For instance, double bonds in the fatty acids can influence the viscosity of the polyester polyol due to their kinks in the fatty acid chains, which can decrease the ability of the chains to pack closely, potentially decreasing viscosity by reducing intermolecular interactions, affecting the resulting polyurethanes flow and processing characteristics. By modifying the types and ratios of fatty acids comprised in the natural fatty acid-containing esters, the physical and chemical properties of the resulting polyurethane can be specifically tailored.

[0040] In an embodiment, the amount of the transesterified bio-based polyester polyol component is between 10 and 80 wt%, particularly between 20 and 60 wt%, particularly between 30 and 50 wt% of the total amount of all polyol components in the PU foam reaction mixture. This may be advantageous because it may further enhance biodegradability and lower toxicity of the artificial turf, reduce production costs due to the natural availability of vegetable oils, and reduce volatile organic compound (VOC) emissions during both production and the life of the product, compared to petrol-based polyols, without compromising the mechanical properties and durability of the resulting polyurethane. In an embodiment, the PU foam reaction mixture further comprises a polyether polyol, the polyether polyol being selected from the group containing polyethylene glycol (PEG), polypropylene glycol (PPG), in particular PPG 2000, polytetramethylene ether glycol (PTMEG), or combinations thereof. This may be advantageous, because due to their varying molecular weights and structural characteristics, in particular the number of hydroxyl groups, these polyether polyols can influence the physical properties of the resulting polyurethane, improving the ability to customize the polyurethane for the specific artificial turf. For example, PPG may contribute directly to the formation of crosslinked structures in the resulting PU, increasingthe material's rigidity and thermal stability due to the highercrosslink density in the resulting PU. On the other hand, PTMEG may provide flexible spacers within the polymer structure, improving the material's elastomeric properties and performance under dynamic stress. Combining different types of polyether polyols may allow for a tailored balance of mechanical properties, such as flexibility, impact resistance, and moisture interaction. In particular PPG 2000 may be used to increase the total number of hydroxyl groups available for crosslinking polyurethane chains.

[0041] Another aspect of the invention is directed to an artificial turf comprising a carrier and an artificial turf fiber incorporated into the carrier such that a first portion of the artificial turf fiber protrudes to a back side of the carrier, a second portion of the artificial turf fiber protrudes to a front side of the carrier, and a third portion of the artificial turf fiber is inside the carrier. The artificial turf further comprises a flexible polyurethane (PU) foam backing with a PU matrix being the reaction product of a PU polymerization reaction wherein an RFS was added in the polymerization reaction mixture, and wherein the PU backing covers the artificial turf fiber protruding to the back side of the carrier for securing the turf fiber in place.

[0042] According to another aspect of the present invention, an artificial turf polyurethane backing kit is provided comprising a polyol blend with filler and additives, an isocyanate component, and a color paste component, wherein one of the components, preferably, the polyol blend, or more preferably the color paste component contains an RFS selected from the group consisting of: a polyester polyol, in particular a polyester diol or polyester triol, in particular a polyester polyol based on soybean oil, and / or castor oil, and / or a fat in the form of an ester of a triol with a fatty acid, in particular a triglyceride, in particular castor oil and / or soybean oil.

[0043] The flexible polyurethane (PU) foam backing exhibits improved tensile strength, improved tuft bind, and improved dimensional stability.

[0044] The color paste may comprise any suitable pigment. Preferably, the color paste may comprise a green color pigment paste. Examples of a green color pigment include phthalocyanine green, chromium oxide green pigment, chrome green pigment, and mixtures thereof. Preferably, the color paste may also comprise an organic green pigment.

[0045] In some embodiments, the color pigment may include phthalocyanine green and / or phthalocyanine blue, preferably phthalocyanine green. Phthalocyanine green G is also known as phthalo green, viridian hue, pigment green 7 and its chemical formula is CszClieCuNs.

[0046] The PU backing may have any suitable thickness. In an embodiment the PU backing may have a thickness of 0.1 mm to 5.0 mm, or 0.1 mm to 4.0 mm, or 0.1 mm to 2.0 mm, and a tuft bind of at least 10 Newtons, or at least 15 Newtons, or 10 Newtons to 30 Newtons, or 15 Newtons to 30 Newtons.

[0047] The PU backing may comprise an enzyme or a characteristic fragment of the enzymatically active site of the enzyme, the enzyme being in particular an esterase, in particular a lipase. This may be advantageous, because the presence of such enzymes can catalyze the breakdown of ester bonds in the polyurethane structure, facilitating easier recycling or biodegradation of the material at the end of its lifecycle. The concentration of the free enzyme may be in the low ppm range. To identify characteristic enzyme fragments in an PU matrix, three key techniques can be utilized:

[0048] Western Blotting: This method involves extracting proteins from the PU matrix, separating them using SDS-PAGE, and transferring them to a membrane. Specific antibodies are then used to detect enzyme fragments, indicating their presence. Enzyme-Linked Immunosorbent Assay (ELISA): Similar to Western blotting, ELISA employs highly specific antibodies to quantify enzyme fragments. The technique involves an antibodybased detection that results in a measurable color change, reflecting the concentration of the fragments.

[0049] Mass Spectrometry (e.g. MALDI-TOF MS): Mass Spectrometry, e.g. Matrix-Assisted Laser Desorption / lonization Time-of-Flight MS, distinguishes protein fragments based on their mass-to-charge ratio. This highly sensitive method can detect minute quantities of enzyme fragments within complex mixtures, providing precise identification.

[0050] The turf fibers may be made of any suitable polymer material including, for example, polyamide, polypropylene, polyethylene, and various grades thereof. Preferably, the turf fibers may be made of hydrophobic polyethylene selected from the group consisting of polyethylene homopolymer, LLDPE, HDPE, polyethylene alloy, and polyethylene copolymer. The fibers may have different shapes and configurations such as, for example, monofilament, slit film, or fibrillated.

[0051] Incorporating the turf fibers into the carrier includes positioning the fiber so that a first portion of the fiber is located at the back side of the carrier (also referred to hereinafter as the back portion of the fiber), a second portion of the fiber is protruding to the front side of the carrier (also referred to hereinafter as the front portion of the fiber) and a third portion of the fiber is inside the carrier (referred to also as the middle portion of the fiber or the carrier portion of the fiber).

[0052] According to another aspect of the present invention a method for manufacturing a transesterified bio-based polyester polyol for use in the manufacturing of a polyurethane component in sports flooring is provided. The method comprises the following steps: providing a first bio-based fatty acid-containing ester, the first bio-based fatty acid-containing ester being in particular a triglyceride, in particular ricinolein; providing a second bio-based fatty acid-containing ester, the second bio-based fatty acid-containing ester being in particular a triglyceride, in particular a triglyceride comprised in soybean oil, linseed oil or tung oil; combining the first and the second bio-based fatty acid-containing ester to form a mixture of bio-based fatty acid-containing esters; and subjecting the mixture of bio-based fatty acid-containing esters to a transesterification catalyzing enzyme, in particular a lipase, wherein the enzyme catalyzes a transesterification reaction between the first and the second bio-based fatty acid-containing ester to form the transesterified bio-based polyester polyol component. The transesterified bio-based polyester polyol components obtained by this method may comprise prepolymers.

[0053] A commercially available bio-based polyester polyol is BiOH® 6305 POLYOL from Cargill Inc. This polyol is soy-based and produced via a thermal transesterification, which disadvantageously has a higher energy consumption than the enzymatic process described herein and additionally results in a more heterogeneous mixture of products compared to an enzymatic transesterification process.

[0054] In an embodiment, the transesterification is carried out a temperature from 20 °C to 80 °C, in particular from 30 °C to 70 °C, in particular from 50 °C to 60 °C. This may be advantageous because operating within this temperature range optimizes the activity of the transesterification enzyme, which may lead to more efficient and controlled reaction rates without compromising the stability of the enzyme.

[0055] In an embodiment, the first bio-based fatty acid-containing ester comprises a first fatty acid, the first fatty acid comprising at least one hydroxyl group, wherein the second bio-based fatty acid-containing ester comprises a second fatty acid, the second fatty acid comprising fewer hydroxyl groups than the first fatty acid. This may be advantageous because it reduces the total number of hydroxyl groups available for a cross-linking reaction, therefore potentially decreasing the cross-link density of the resulting polyurethane. This reduction in cross-link density can lead to a polyurethane that is more flexible and has improved elongation properties which are desirable characteristics for artificial turf where durability under physical stress is required. By adjusting the mixing ratio of, for example, castor oil and soybean oil, the soybean oil containing only fatty acids without hydroxyl groups, the total number of hydroxyl groups available for a cross-linking reaction and thus the cross-link density of the resulting polyurethane can be reliably controlled.

[0056] In an embodiment, the first natural fatty acid-containing ester is ricinolein and the second functional fatty acid is selectively introduced at the sn-1 position and / or the sn-3 position of the ricinolein. This selective substitution may be advantageous because it may precisely alter the functionality and reactivity of the polyester polyol due to the strategic placement of fatty acids with different chemical properties. By modifying these specific positions on the glycerol backbone, the resulting polyester polyol may exhibit tailored physical and chemical characteristics. This includes adjustments in the hydrophilic-hydrophobic balance, which can significantly influence the resulting polyurethane's water absorption, mechanical strength, and thermal stability. In particular, if the sn-2 position remains unsubstituted, the transesterified ricinolein can bond to the PU backbone and act as a plasticizer, wherein due to the covalent bond the probability of migration or leaching out of the triglyceride from the PU matrix is drastically reduced, therefore leading to improved stability and longevity of the polyurethane under various environmental conditions. This advantage becomes even more apparent when this PU, equipped with side chains that act as plasticizers, is compared with a PU in which plasticizer are introduced in a non-covalently bound form and can, under certain conditions, leach from the PU due to migration, significantly altering the mechanical properties of the PU, in particular decreasing the tensile strength and elasticity.

[0057] In an embodiment, the second fatty acid introduced has a chain length from 8 to 22 carbon atoms, in particular 10 to 20 carbon atoms, in particular 14 to 18 carbon atoms. This specific range of chain length may be advantageous, because it may keep the elasticity, flexibility and hardness of the resulting PU in a range which is favored for artificial turf. If the chains are longer, the increased van der Waals forces between the molecules could make the polyurethane too stiff, reducing its ability to cushion and absorb impacts effectively, which is critical for sports and recreational activities on artificial turf. Conversely, if the chains are too short, the material might not provide sufficient wear resistance and durability, leading to quicker degradation of the artificial turf under mechanical and environmental stress.

[0058] In an embodiment, the enzyme is immobilized on a solid support and the mixture of biobased fatty acid-containing esters is brought into contact with the solid support, in particular the mixture of bio-based fatty acid-containing esters is passed in a downflow manner through the solid support. This may be advantageous because immobilizing the enzyme improves the stability and reusability of the enzyme, allowing for multiple cycles of use without significant loss of activity. Additionally, the fixed position of the enzyme on a solid support facilitates the continuous processing of the ester mixture, leading to improved control over reaction conditions and more efficient conversion rates. This setup also simplifies separation of the product from the enzyme, reducing processing times and costs of the transesterified biobased polyester polyol associated with enzyme recovery and purification. Immobilizing the enzyme may result in a concentration of the free enzyme in the polyester polyol in the low ppm range, therefore minimizing potential contamination and the risk of unintended reactions. Additionally, this presence of enzymes, even in the low ppm range, enables differentiation of products derived from an enzymatic transesterification process from those obtained through traditional thermal transesterification, e.g., by High-Performance Liquid Chromatography (HPLC).

[0059] According to another aspect of the present invention a transesterified bio-based polyester polyol obtainable by a method for manufacturing a transesterified bio-based polyester polyol for use in the manufacturing of a polyurethane component in sports flooring according to the invention is provided.

[0060] According to yet another aspect of the present invention using or providing the transesterified bio-based polyester polyol for the manufacturing of a polyurethane component in sports flooring according to the invention is provided.

[0061] According to yet another aspect of the present invention a method for manufacturing a polyurethane reaction mixture for the manufacturing of a polyurethane component in sports flooring is provided. The method comprising the following steps: providing a transesterified bio-based polyester polyol component according to this invention; providing an isocyanate component, the isocyanate component being in particular MDI (methylene diphenyl diisocyanate), TDI (toluene diisocyanate), HDI (hexamethylene diisocyanate), or IPDI (isophorone diisocyanate); and combining the transesterified bio-based polyester polyol component with the isocyanate component to form a polyurethane reaction mixture. This method may be advantageous because on one hand, using a transesterified bio-based polyester polyol component in the polyurethane reaction mixture enhances the biodegradability and reduces the carbon footprint of the final product, making it more environmentally friendly and sustainable. On the other hand, the isocyanate component, such as MDI, TDI, H DI, or I PDI, ensures robust cross-linking within the polyurethane matrix, which improves the mechanical properties and durability of the sports flooring.

[0062] In an embodiment, the polyurethane reaction mixture further comprises at least one of the following: a filler component, the filler component particularly comprising ground limestone, chalk (precipitated calcium carbonate), China clay, coal fly ash, silicates (in particular zeolites), and combinations thereof; a color paste component, the color paste component particularly comprising phthalocyanine green, chromium oxide green, chrome green or phthalocyanine blue, and combinations thereof; a chain extending component, the chain extending component particularly comprising MEG (monoethylene glycol), DEG (diethylene glycol), TEG (triethylene glycol), MPG (monopropylene glycol), DPG (dipropylene glycol), TPG (tripropylene glycol), BDO (1,4-butanediol), butanetriol (also known as 1,2,4-butanetriol) or 1, 4 - cyclohexanedimethanol (CHDM), and combinations thereof.

[0063] This may be advantageous because the inclusion of the various components enhances the functional properties of the polyurethane. Filler materials like ground limestone, chalk, China clay, coal fly ash, and silicates improve the structural integrity and dimensional stability while potentially reducing costs and improving thermal properties. Adding color pastes improves the UV stability of the resulting polyurethane, important for durability in outdoor settings. Chain extenders like MEG, DEG, and BDO influence the molecular weight distribution and cross-link density of the polyurethane, affecting elasticity and tensile strength. This customization allows for tailoring specific properties of the polyurethane resulting from the reaction mixture, which may enable the sports flooring to meet specific performance and safety standards.

[0064] According to yet another aspect of the present invention a method for manufacturing sports flooring comprising a PU element is provided, the method comprising the following steps: providing a polyurethane reaction mixture obtainable by the methods according to this invention; initiating the reaction of the isocyanate component and the transesterified biobased polyester polyol component in the polyurethane reaction mixture, wherein the polyurethane of the PU element is formed; and assembling the sports flooring using the PU element.

[0065] According to yet another aspect of the present invention, a sports flooring obtainable by the method according to this invention is provided. An example of such a sports flooring comprising a PU element is described in European Patent 3 342 930 Al, wherein the PU element is the polyurethane polymer matrix of a gel layer or a primer layer below the PU gel layer.

[0066] In an embodiment, the PU element comprises an enzyme or a characteristic fragment of the enzymatically active site of the enzyme, the enzyme being in particular an esterase, in particular a lipase.

[0067] In an embodiment, the PU element of the sports flooring comprises a transesterified biobased polyester polyol component. This may be advantageous because the transesterified bio-based polyester polyol component in the PU element may improve flexibility and elasticity due to the enhanced segmental mobility of the polyol within the polyurethane matrix. This mobility helps the PU element absorb impacts more effectively and recover its shape quickly.

[0068] In an embodiment, the structure of the sports flooring comprises: a top layer that seals the sports flooring; and a PU gel layer comprised of a solid and a liquid component between a base material and the top layer, the solid component being a polyurethane polymer matrix, the liquid component being a plasticizer, wherein the PU element is the polyurethane polymer matrix or a primer layer below the polyurethane polymer matrix. This may have the advantage that a high shock absorption rate of 20% and more can be achieved while simultaneously reducing toxicity and production costs. Thus, very good balance of physical properties needed for the performance of a sports flooring, can be achieved over a wide range of temperatures and a wide range of substrate materials. High shock absorption rates are required for many types of sports flooring, in particular tennis courts and running tracks. Further advantages of the sports flooring and the method for manufacturing sports flooring are equivalent to those of the PU foam reaction mixture that comprises a transesterified biobased polyester polyol component, which is why a repetition of the advantages is omitted here.

[0069] A "transesterified bio-based polyol polyester" as used herein is the product of an enzymatic transesterification of a fatty acid-containing ester derived from natural sources such as plant oils. Specifically, this ester originates from triglycerides found in oils like castor oil, with ricinolein being a common example of such a triglyceride. The enzymatic transesterification process involves the selective substitution of fatty acids within these triglycerides by mixing two different fatty acid-containing ester in the presence of a transesterification catalyzing enzyme, in particular a lipase. The result of this process are molecules with fatty acid side chains that reflect the initial proportions of the fatty acids in the fatty acid-containing esters. This product of the enzymatic transesterification may also be referred to as an enzymatically transesterified derivative of an fatty acid-containing ester.

[0070] The term „bio-based" as used herein refers to the origin of a compound or composition, specifically the natural source from which a fatty acid-containing ester is derived, distinguishing it from petrol-based sources. The derivation from a natural source can be verified through a C14 radiocarbon analysis, as outlined e.g. by ASTM D6866. The radiocarbon analysis measures the ratio of C14 to C12 isotopes, which is significantly higher in living matter and recently dead biological material, termed „biomass", compared to petrolbased materials. C14, a radioactive isotope, decays over time and is absent in petroleum, which is geologically ancient and thus devoid of this isotope. Consequently, a „bio-based" material is identified as being isotopically rich in carbon 14, reflecting a higher C14 to C12 ratio than found in petroleum sources.

[0071] The "number of hydroxyl equivalents per weight" or "hydroxyl number" is a measure of the content of free hydroxyl groups in a chemical substance, expressed in units of the mass of potassium hydroxide (KOH) in milligrams equivalent to the hydroxyl content of one gram of the chemical substance These and other features and advantages of the present invention will become better understood from the following detailed description of the invention in conjunction with the accompanying drawings

[0072] Brief Description of the Drawings

[0073] Figures 1A and IB are flowcharts of a method of manufacturing of an artificial turf with an RFS in the polyurethane backing, according to an embodiment of the present invention.

[0074] Figure 2 illustrates a simplified block diagram of a process for forming a polyurethane reaction mixture for the backing of the artificial turf, according to an embodiment of the present invention.

[0075] Figure 3 illustrates a "knife over roll" polyurethane backing process, according to an embodiment of the present invention.

[0076] Figure 4 illustrates the extrusion of a polymer mixture into a monofilament, according to an embodiment of the present invention.

[0077] Figures 5a and 5b illustrate the tufting of an artificial turf fiber and illustrates first and second parts of the fiber, according to an embodiment of the present invention.

[0078] Figures 6a and 6b illustrate an artificial turf structure with portions of monofilaments and fibers embedded in a polyurethane backing, according to an embodiment of the present invention.

[0079] Figure 7 shows a back-side of an artificial turf with a homogeneously colored secondary backing.

[0080] Figure 8 illustrates the changes in the molecule structure of an exemplary transesterified biobased polyester polyol component throughout the enzymatic transesterification. Figure 9 shows a comparison of tensile strength of different polyurethanes that are a reaction product of a polymerization reaction in which different amounts of Example A, B and C have been added to the polyol component in the polyurethane reaction mixture.

[0081] Figure 10 illustrated an exemplary sports flooring with PU elements according to the invention.

[0082] Detailed Description of the Invention

[0083] Various embodiments of the present invention will be described in greater detail with reference to the accompanying drawings. Like numbered elements in the figures are either equivalent elements or perform the same function. Elements which have been discussed previously will not necessarily be discussed in later figures if the function is equivalent.

[0084] Referring to figure 1A, a method for manufacturing an artificial turf is provided, the method comprising preparing a first polyurethane reaction mixture (PU-RM) including a reaction foam stabilizer (RFS) dispersed in the polyurethane reaction mixture in step 102, incorporating an artificial turf fiber into a carrier in step 104, adding the fluid (viscous) polyurethane reaction mixture with the RFS on the back side of the carrier in step 106, and hardening the polyurethane reaction mixture in step 108 to form a polyurethane backing, wherein the method is characterized in that an effective amount of the RFS is added in the polyurethane reaction mixture for stabilizing the polyurethane foam reaction mixture. The stabilized PU reaction mixture may prevent the settling out of any additives added in the mixture before it is applied on the back side of the carrier and hardened. The RFS is added and dispersed via mixing inside the polyurethane reaction mixture before the polyurethane reaction mixture is applied on the back side of the carrier. Once the polyurethane reaction mixture is placed on the back side of the carrier, hardening of the polyurethane reaction mixture is performed to form a solid polyurethane backing with a portion of the turf fiber which protrudes out of the back side of the carrier being securely embedded inside the solid mass of the polyurethane backing. The polyurethane backing enhances the structural strength of the artificial turf and the fiber pulling characteristic of the turf fiber.

[0085] Referring now to figure IB the preparation of the polyurethane reaction mixture with the RFS may comprise mixing the RFS compound with a color paste in step 1022 to make a first mixture, compounding a solid component with a main polyol in step 1024 to make a second mixture, adding the first mixture and second mixture together in step 1026 to create a third mixture, and injecting pressurized air in step 1028 inside the third mixture for mechanically frothing the third mixture. The method further comprises adding an isocyanate in step 1029.

[0086] In the compounding step 1024 two or more solid components may be compounded together. For example, chalk as filler and zeolite as a drying agent may be added as the solid components. Up to 3 liquid components including the main polyol and in an embodiment a chain extender, catalyst / additive or similar compounds may be added. The step 1024 may be performed in a polyurethane machine comprising a manifold where the first mix (compounded material from step 1022 including the color, and the RFS) and a surfactant and a catalyst, if needed, are added and mixed. The pressurized air is added in step 1028 for foaming the mixture. The third mixture from the manifold is transferred to a mixing head where an isocyanate is added. Mixing in the mixing head with the addition of pressurized air produces a foam of the reactive polyurethane mixture mass.

[0087] The RFS may be a bio-based polyol based on natural vegetable oil, preferably, soybean oil, or castor oil, or mixtures thereof with a nominal functionality of 2 or greater. The bio-based polyol can be used in its natural form or may be modified.

[0088] Polyester polyol based on soybean oil and / or castor oil refers to a polyester polyol formed from the soybean oil, and / or the castor oil via a transesterification reaction wherein the triglycerides in the soybean oil, and / or the castor oil are reacted with a polyhydric alcohol such as glycerol or pentaerythrol to produce polyester polyols. The transesterification reaction breaks down the triglycerides, and the fatty acids are exchanged for hydroxyl (OH) groups from the polyhydric alcohol, resulting in the formation of polyester polyols.

[0089] The castor oil or soybean oil may be extracted from plant material essentially without introducing chemical modifications by crushing or pressing the castor bean seeds or the soybean seeds respectively. The process may include mixing the crushed seeds with a solvent that dissolves the castor oil present in the seeds creating a mixture of castor oil and solvent. The mixture is then separated by passing it through a distillation column where the solvent is evaporated and the castor oil is retrieved as liquid from the bottom of the column. The retrieved oil may then be refined through well-known refining processes.

[0090] Castor oil is a triglyceride with a glycerol backbone with each of its three hydroxyl groups esterified with a fatty acid. The main fatty acid is ricinoleic acid which is a unique fatty acid found almost exclusively in castor oil and accounts for about 85 to 95% of the total fatty acids in the oil. Other fatty acids present in the castor oil are oleic acid, linoleic acid, and stearic acid.

[0091] The chemical structure of soybean oil triglycerides is represented as follows:

[0092] R1

[0093] I

[0094] O - CH2 - CH - R2

[0095] I

[0096] O - CH2 - CH - R3

[0097] I

[0098] R4

[0099] In this structure, Rl, R2, and R3 represent different fatty acid chains, and the glycerol backbone is represented as R4.

[0100] Since soybean oil contains a mixture of fatty acids, the triglycerides present in the oil will have different combinations of these fatty acids. The proportions of the different fatty acids in soybean oil may vary depending on factors like the soybean variety and processing methods used to extract the oil. The major fatty acids found in soybean oil include oleic acid, linoleic acid, palmitic acid, and stearic acid.

[0101] In other embodiments, the castor oil and soybean oil may be chemically modified. Chemical modification may include transesterification with polyols with high functionality and high OH#. Suitable polyols for such modification may include glycerol, trimethylopropane (TMP), pentaerythritol (PER) sorbitol, sucrose, and the like, and the reaction may take place in the presence of an alkali alcoholate catalyst such as sodium methoxide or potassium methoxide. Transesterification of castor oil may generate mono, di and triglycerides of ricinoleic acid having a much higher OH# than the castor oil. Chemistry and Technology of Polyols for Polyurethanes, 2ndEdition, Volume 2, pages 168-169.

[0102] According to an embodiment, the transesterification reaction can be performed in the form of a thermal transesterification or an enzymatic transesterification. Using enzyme-based transesterification may have the advantage that the transesterification reaction is highly specific and a defined type of ester will be obtained from defined educts. Thermal transesterification often generates a heterogeneous mixture of products, but has the advantage of being more robust against proteases, heat and other factors which may have a negative impact on enzymatic activity.

[0103] The addition of the bio-polyol over the color is advantageous because it allows controlling the rate of crosslinking / plasticization while also improving foam stability without having to change the process layout. It also prevents processing problems because of excessive viscosity.

[0104] Preferably, the polyurethane reaction mixture enters inside the carrier structure before it is fully solidified. Depending on the structure of the carrier, the viscosity of the polyurethane reaction mixture, and the rate of the solidification of the polyurethane reaction mixture, the polyurethane reaction mixture can enter deeper inside the carrier to better secure the turf fibers in place. The backing may further include various agents such as antimicrobial agents or cooling agents (e.g., a phase change material) and allowing the PU reaction mixture to enter deeper into the carrier may be beneficial for allowing these agents to also be distributed within the carrier. In some other embodiments the polyurethane reaction mixture, before it is fully solidified, may enter through the carrier to also form a thin coating on a front side of the carrier, thus fully covering both the back side and the front side of the carrier and also filling any voids inside the carrier. Figure 2 illustrates multiple tanks and mixers comprising educts for creating the polyurethane reaction mixture according to an example. A first mixing unit 201 (also referred to as first tank or first container) is used for creating a first mixture 202 (also referred to as the polyol blend) comprising the polyether polyol or the polyester polyol. For example, the first mixture 202 comprises a polyether-polyol, e.g., a polyether-polyol having a number average molecular weight of about 4000 Da, e.g., a polyol based on polymerized propylene oxide. The polyether polyol may be obtained e.g., in the form of a ready-made polyol.

[0105] The first mixture 202 may be a polyether polyol and / or a polyester polyol having at least 2 hydroxyl groups per molecule. Examples of polyether polyols may include polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene ether glycol (PTMEG). Examples of polyester polyols may include polyethylene adipate, polycaprolactone polyol, and polybutylene adipate terephthalate. The first mixture 202 may further include a chain extender. The chain extender may be, for example, MEG (monoethylene glycol), DEG (diethylene glycol), TEG (triethylene glycol), MPG (monopropylene glycol), DPG (dipropylene glycol), TPG (tripropylene glycol), BDO (1,4-butanediol), butanetriol (also known as 1,2,4- butanetriol), 1, 4 - cyclohexanedimethanol (CHDM), and the like. The chain extender may be used in an amount of 5 to 50 wt% of the total amount of the first mixture 202.

[0106] In an embodiment, the first mixture 202 may comprise PPG 450 to 6000 Da, and a chain extender in an amount of 5 to 50 wt% of the total amount of the polyol blend.

[0107] In an embodiment, the first mixture 202 may comprise the following polyols: 85% polyethylene glycol 4000 Da (or polyethylene glycol 2000 Da) and 15% dipropylene glycol (DPG), and a chain extender in an amount of 5 to 50 wt% of the total amount of the polyol blend.

[0108] In an embodiment, the first mixture 202 may comprise a filler material. Adding a filler may reduce the cost and / or help to achieve a particular look or weight. Fillers can be, for example selected from the group ground limestone, chalk (precipitated calcium carbonate), China clay, coal fly ash, silicates and other inert material including non-reactive liquids. Moreover, fillers with flame retardant and / or intumescent efficiency like aluminum hydroxide (AI(OH)s) or ammonium polyphosphate (NH4PO3]n(OH)2) may be used or mixtures of the aforementioned fillers. In an embodiment the filler may be chalk.

[0109] The first mixture may optionally include other substances such as a catalyst, anti-settling agent, wetting agent, dispersing agent, drying agent such as zeolite.

[0110] For example, the first mixture 202 may comprise a catalyst for boosting the polyaddition reaction that generates the polyurethane. The catalyst can be, for example, amine compounds and metal-organo complexes. Traditional amine catalysts have been tertiary amines such as triethylenediamine (TEDA, l,4-diazabicyclo[2.2.2]octane or DABCO), dimethylcyclohexylamine (DMCHA), and dimethylethanolamine (DMEA). Metal-organo complexes used as polyurethane catalysts can be based, for example, on mercury (e.g., mercury carboxylates), lead, tin (e.g., alkyl tin carboxylates and oxides), bismuth, and zinc (e.g., bismuth and zinc carboxylates). The first mixture is then stored in the first tank 201, e.g., a day tank, i.e., a tank sized to provide a day's worth of usage.

[0111] For example, a mixture of tin organic and an amine catalyst may be used. Suitable amines include, for example, Cyclohexyldimethylamine, 2-dimethylaminoethanol, 4- ethylmorpholine, N,N,4-trimethylpiperazine-l-ethylamine, 1,4-dimethylpiperazine, 3- aminopropyldimethylamine, 2,2'-iminodiethanol, 1-methylimidazole, 1,2- dimethylimidazole, 2-[[2-(dimethylamino)ethyl]methylamino]ethanol, N-[3- (dimethylamino)propyl]-N,N',N'-trimethylpropane-l,3-diamine, formic acid, compound with 2,2'-oxybis[N,N-dimethylethylamine] (2:1), l,l'-[[3-(dimethylamino)propyl]imino]bispropan- 2-ol, + 2-[(2-[2-(dimethylamino)ethoxy]ethyl)methylamino]ethanol, Benzyldimethylamine 4- methylmorpholine, N,N,N',N'-tetramethylhexamethylenediamine, 2-[2-

[0112] (dimethylamino)ethoxy]ethanol, 1,4-diazabicyclooctane, Bis(2- dimethylaminoethyl)(methyl)amine, N,N,N',N'-tetramethyl-2,2'-oxybis(ethylamine, 2,2'- dimorpholinyldiethyl ether, l,8-diazabicyclo[5.4.0]undec-7-ene, N'-[3- (dimethylamino)propyl]-N,N-dimethylpropane-l,3-diamine, N,N,N',N',N",N"-hexamethyl- l,3,5-triazine-l,3,5(2H,4H,6H)-tripropanamine, and N,N-bis[3-(dimethylamino)propyl]- N',N'-dimethylpropane-l,3-diamine. In an embodiment, the polyurethane may be the reaction product of first and second polyols with an isocyanate, wherein the first polyol is polyether polyol and / or polyester polyol having at least 2 hydroxyl groups per molecule, wherein the second polyol is polybutadiene diol (PBD), wherein the isocyanate comprises isocyanate monomers, isocyanate polymers or isocyanate prepolymers or a mixture thereof, and wherein the isocyanate monomers, the isocyanate polymers and the isocyanate prepolymers have two or more isocyanate groups per molecule.

[0113] The second mixture 204, i.e., the isocyanate monomer / polymer / prepolymers mixture, e.g., MDI, is stored in a second tank 203 that is preferably also a day tank. A further container 205 that is typically of a smaller size than the first and second tanks comprises a third substance mixture 206 including the RFS, preferably dispersed within the color paste ("Color").

[0114] In the embodiment illustrated in figure 2, PBD may optionally also be added in the third substance mixture 206, however, it should be understood that in other embodiments no PBD is added.

[0115] Optionally other agents and substances such as an antimicrobial agent, a wetting agent, pale oil and / or one or more further additives may be added. The one or more further additives may be, for example, flame retardants, extenders, cross linkers, blowing agents and the like. The containers 201, 203, and 205 may be part of or coupled to a mixing head 208. The mixing head 208 may receive the first mixture 202 from the first container 201, the second mixture 204 from the second container 203 and the color paste with the RFS, optionally the PBD and the one or more optional substances (wetting agent, pale oil and / or further additives) from the third container 205. The mixing head 208 may blend the first, second and third mixtures received from the respective containers (or tanks) in suitable amounts for forming a polyurethane reaction mixture 210 having substance concentrations within the ranges specified herein for the various embodiments of the invention. For example, the first, second and third mixtures are blended such that the number of OH groups in the first polyol molecules in the first mixture in combination with the number of OH groups in the PBD molecules in the third mixture will roughly correspond (e.g., in a range of ratios ranging from "0.9:1" to "1:0.9") to the number of NCO groups in the isocyanate molecules (monomers and prepolymers).

[0116] In an embodiment, the color paste may comprise of 7% to 60 %, or 10% to 50%, or 15% to 45%, or 20% to 40%, or 25% to 30% by weight pigment, and 40% to 93%, or 50% to 90%, or 55% to 85%, or 60% to 80%, or 70% to 75% RFS and may be added by the mixing head 208 to the reaction mixture 210 in such an amount that it may comprise 0.5. to 9, or 1 to 6, or 2 to 4 parts by weight of the color paste, 70 to 120, or 80 to 110, or 90 to 110 parts by weight of the polyol blend and 7 to 21, or 10 to 18, or 12 to 16 parts by weight of isocyanate.

[0117] In an embodiment, the PU foam reaction mixture applied to the carrier may comprise 1 part by weight of the color paste, 80 parts by weight of the polyol blend and 7 parts by weight of isocyanate.

[0118] In another embodiment, the PU foam reaction mixture applied to the carrier may comprise

[0119] 3 parts by weight of the color paste, 100 parts by weight of the polyol blend and 14 parts by weight of isocyanate.

[0120] In another embodiment, the PU foam reaction mixture applied to the carrier may comprise

[0121] 4 parts by weight of the color paste, 110 parts by weight of the polyol blend and 16 parts by weight of isocyanate.

[0122] In another embodiment, the PU foam reaction mixture applied to the carrier may comprise 7 parts by weight of the color paste, 115 parts by weight of the polyol blend and 18 parts by weight of isocyanate.

[0123] The mixing head 208 may be equipped to produce a desired mixing ratio of the first, second and third mixtures and means for injecting pressurized air ("PRES. AIR") to cause mechanical frothing of the foam polyurethane reaction mixture. The ratios of the various materials, reactants, and products and their distribution may be driven by computer assisted equipment and controlled centrally via CPU. Addition of the RFS in an effective amount, allows stabilization of the foam, prevents settling out of the various additives, and adjusts the viscosity of the polyurethane reaction mixture 210 such that the polyurethane reaction mixture enters deeply into the tufts of artificial grass, and wets the textile carrier and the monofilaments contained therein for allowing better tuft bind with even less polyurethane material.

[0124] For example, in an embodiment, the thickness of the PU backing may be reduced, and may be at least 25%, preferably at least 30%, more preferably at least 40% less than the thickness of a conventional backing when all other parameters are kept the same except for the addition of the RFS in the PU foam reaction mixture.

[0125] With the inventive PU foam reaction formulation which includes the RFS the thickness of the PU backing may be as little as 0.1 mm.

[0126] In an embodiment, a polyethylene fiber artificial turf may be made with the inventive PU backing having a thickness of 2.0 mm and an adequate tuft bind of at least 10 Newtons, or at least 15 Newtons, or 20 to 30 newtons.

[0127] In an embodiment, a polyethylene fiber artificial turf may be made with the inventive PU backing having a thickness of 1.0 mm and an adequate tuft bind of at least 10 Newtons, or at least 15 Newtons, or 20 to 30 newtons.

[0128] In an embodiment, a polyethylene fiber artificial turf may be made with the inventive PU backing having a thickness of 0.5 mm and an adequate tuft bind of at least 10 Newtons, or at least 15 Newtons, or 20 to 30 newtons.

[0129] In an embodiment, a polyethylene fiber artificial turf may be made with the inventive PU backing having a thickness of 0.1 mm and an adequate tuft bind of at least 10 Newtons, or at least 15 Newtons, or 20 to 30 newtons.

[0130] The polyurethane reaction mixture 210 generated by the mixing head 208 is fed to a container 212 which may have the form of a hose. The container 212 (or chamber) has an opening 214 that leads to a coater, e.g., a "knife over roll" backing assembly as depicted, for example, in figure 3. Typically, the reaction mixture output by the mixing head 208 reaches the opening 214 being part of the backing assembly within 30 seconds. At this point, the polyaddition reactions resulting in the generation of the liquid polyurethane reaction mixture used for backing a carrier textile of a piece of artificial turf will largely have been completed already, but some reactions may still continue during the backing process.

[0131] According to an embodiment, the first polyol(s), (optionally the PBD) and the isocyanate in total constitute at least 25%, according to other embodiments at least 40%, or even more than 95% of the total amount of the total reaction mix used for generating the liquid polyurethane reaction mixture that - after a curing process - is used as the artificial turf backing. In a specific example, the reaction mixture comprises in weight percentages about 21.5% isocyanate, 0.5 % PBD, 21.5 % polyethylene glycol, 2.1% catalyst, 1.5 % RFS, and 2.5 % additives like dyes, flame retardants, and the remainder is filler material.

[0132] In another specific example, the reaction mixture comprises in weight percentages about 20% isocyanate, 0.1% PBD, 20 % polyethylene adipate, 2.1% catalyst, 2.5 % RFS, 2.0 % additives like dyes, flame retardants, and the remainder is filler material.

[0133] In yet another specific example, the reaction mixture comprises in weight percentages about 20% isocyanate, 0.1% PBD, 20 % polyethylene glycol, 2.1% catalyst, 7.0 % RFS, 2.0 % additives like dyes, flame retardants, and the remainder is filler material.

[0134] Figure 3 illustrates a "knife over roll" polyurethane backing process and a corresponding backing assembly. The liquid, viscous reaction mixture 210, (also referred to as liquid polyurethane reaction mixture), upon leaving the opening 214 of the container 212, is applied on a carrier 308. A plurality of artificial turf fibers 501 protrude from the front side of the carrier. The liquid polyurethane reaction mixture 210 is applied on the back side of the carrier. The polyurethane reaction mixture is applied continuously while a roll 306 (also referred to as the carrier reel or drum) causes the carrier 308 to move in a direction indicated by the arrows. A "knife" 304 shown in cross section view is located at a defined distance above the carrier 308 and ensures that the viscous polyurethane reaction mixture 210 passing the space between the knife 304 and the carrier 308 has a defined height.

[0135] The high viscosity of the polyurethane reaction mixture, according to an embodiment, of the invention and the configuration and dimensions of the opening 214 and the speed of the polyurethane reaction mixture flow through this opening are chosen such that a defined amount of polyurethane reaction mixture builds up and accumulates on the front side of the knife 304. This ensures that the thickness of the polyurethane backing of the generated piece of artificial turf is constant. The presence of the RFS in the reaction mixture facilitates the controlling of the viscosity of the polyurethane mixture and stabilizes the foam so that a more homogeneous application of the reaction mixture is facilitated.

[0136] After the polyurethane reaction mixture 210 is homogeneously applied on the back side of the carrier 308, the polyurethane reaction mixture is hardened (increase of viscosity) by keeping the coated piece of artificial turf for about 10 minutes at room temperature. Typically, the polyurethane backing may become fully solid in only a few minutes, preferably less than two minutes after its application on the carrier.

[0137] In an embodiment, to speed up the solidification, the artificial turf once the polyurethane reaction mixture is placed on the back side of the artificial turf may be exposed to an elevated temperature around 100°C. Typically, after 90 seconds at elevated temperature, 90 to 95% of the polyurethane reaction mixture is "cured" (is in solid state). The heating may be performed, for example, in an oven. For example, the backing assembly, for example via the carrier drum may automatically transport the coated piece of artificial turf in an oven.

[0138] Figure 4 illustrates a liquid polymer mixture 400 for producing a monofilament 412 in an extrusion process. The polymer is a polyolefin, e.g., a polyethylene mixture. The polymer mixture 400 comprises additives 404, 406 such as UV-stabilizers, pigments, flame retardants or the like. A screw, piston or other device is used to force the polymer mixture 400 through a hole 410 in a plate 408. This causes the polymer mixture 400 to be extruded into a monofilament 412.

[0139] In an embodiment, the polymer mixture may comprise polymer beads of a more rigid polymer, e.g., polyamide. Due to flow dynamics during the extrusion process, the beads will tend to concentrate in the center of the monofilament 412. This may lead to a concentration of rigid, thread-like PA regions in the core region of the monofilament while the surface of the monofilament almost completely consists of the hydrophobic PE. Thus, a fiber with increased resilience is provided which has a soft PE surface that protects against injuries and skin burns which, however, has a very hydrophobic surface and may therefore easily detach from a polar polyurethane backing.

[0140] Thus, the monofilament is produced by feeding the polymer mixture 400 into a fiber producing extrusion line. The melt mixture is passing the extrusion tool, i.e., a spinneret plate or a wide slot nozzle, forming the melt flow into a filament or tape form, is quenched or cooled in a water spin bath, dried and stretched by passing rotating heated godet rollers with different rotational speed and / or a heating oven. The monofilament or fiber may later be annealed online in a second step passing a further heating oven and / or set of heated godet rollers.

[0141] According to an embodiment, manufacturing an artificial turf fiber (which may comprise one or more monofilaments 412 comprises forming the stretched monofilament into a yarn. Multiple, for example 4 to 8 monofilaments, could be formed or finished into a yarn.

[0142] According to an embodiment, the extrusion is performed at a pressure of 40-140 bars, more preferably between 60-100 bars. The polymer mixture may be created by adding polymer granules to a solid polymer composition that is mixed and heated until all polymer is melted. For example, the polymer mixture may be heated to reach at the time of extrusion a temperature of 190-260°C, more preferably 210-250°C.

[0143] According to an embodiment, the stretching comprises stretching the reheated monofilament according to a stretch factor in the range of 1.1-8, more preferably in the range of 3-7.

[0144] According to an embodiment, the quenching is performed in a quenching solution having a temperature of 10 - 60°C, more preferably between 25°C - 45°C. According to an embodiment, the incorporation of the artificial turf fiber into the carrier comprises tufting or weaving the artificial turf fiber into the carrier.

[0145] According to an embodiment, the quenching solution, e.g., a water bath, has a temperature (right after the extrusion nozzle or hole(s)) of 10 - 60°C, more preferably between 25°C - 45°C, and even more preferably between 32°C - 40°C.

[0146] According to an embodiment, the extrusion is performed at a pressure of 80 bar, the polymer mixture at time of extrusion has a temperature of 230°C, the stretch factor is 5 and the quenching solution, e.g., a water bath, has a temperature of 35°C.

[0147] Referring to Figures 5a, and 5b the incorporating of the turf fiber 501 into the carrier 308 includes positioning the fiber 501 so that a first portion of the fiber 302 is protruding to the front side of the carrier (also referred to hereinafter as the front portion of the fiber), a second portion 506 of the fiber is located at the back side of the carrier (also referred to hereinafter as the back portion of the fiber), and a third portion of the fiber 504 is inside the carrier (referred to also as the middle portion of the fiber).

[0148] Figure 5a illustrates the tufting of an artificial turf fiber and how a plurality of artificial turf fibers can be arranged in a carrier 308, e.g., a textile plane, by tufting. The carrier 308 may be a textile made of a hydrophobic polymer, e.g., PE. Tufting is a type of textile weaving in which an artificial tuft fiber 501 (that may be a monofilament 412 or a bundle of multiple monofilaments) is inserted on a carrier 308.

[0149] A "monofilament" as used herein is a filament generated by extruding a liquid polymer mixture through a single opening or is a slice of a polymer tape generated in accordance with the slit film technique.

[0150] After the inserting is done, as depicted in figure 5a, short U-shaped loops of the fiber point outside of the carrier's surface. Then, one or more blades cut 502 through the loops. As a result of the cutting step, two artificial turf fiber ends per loop and monofilament point out from the carrier and a grass-like artificial turf surface is generated as depicted in figure 5b. Thereby, first portions 506 of the monofilaments (corresponding to first portions of the artificial turf fibers) which have been inserted in the carrier 308 are exposed to a bottom side (back side) of the carrier and second portions 302 of said monofilaments are exposed to a top side of the carrier. Some portions 504 of the monofilaments / fibers are located within the carrier. Fibers or fiber bundles may protrude in loops 503 outside of the back side of the carrier. The piece of artificial turf generated in the tufting process may be forwarded to the backing assembly depicted in Figure 3 for applying the polyurethane reaction mixture 210 on the back side of the carrier.

[0151] Figures 6a and 6b show portions of monofilaments and fibers which are embedded in the polyurethane backing. Reference number 600 refers to the total height of a piece of artificial turf having been coated with the polyurethane reaction mixture 210 generated according to an embodiment of the invention.

[0152] Figure 6a illustrates a piece of artificial turf made from a highly viscous polyurethane reaction mixture and / or with a close meshed carrier 308 that prevents the polyurethane reaction mixture from penetrating and transgressing the carrier 308. In this embodiment, second portions 302 of the fibers 501 protrude from the carrier 308 to the front side of the artificial turf and are not embedded in a polyurethane film as the liquid polyurethane reaction mixture 210 was not able to reach the front side of the carrier during the backing process. Also, the fiber portions 504 within the carrier are not wetted by the polyurethane reaction mixture in this embodiment. However, the back side portions 506 of the fibers are embedded in the liquid polyurethane reaction mixture 210 during the backing process. Although the length of these back side portions is comparatively small, the high hydrophobicity and the improved wetting of the fibers by the polyurethane reaction mixture 210 ensure that the fibers are firmly fixed by Van-der-Waals forces in the backing and that a slip stick effect further protects the fibers against tuft withdrawal forces.

[0153] Figure 6b illustrates a piece of artificial turf made from a less viscous polyurethane reaction mixture (compared to the embodiment of figure 6a) and / or with a wide-meshed carrier 308. The carrier may be a textile mesh or another type of material that comprises perforations that allow the polyurethane reaction mixture 210 to enter the carrier and reach the front side of the artificial turf. Thus, the front portion 302 of the fibers in figure 6b comprises an outer portion 604 which is not embedded in the polyurethane film 210 and an inner portion 602 which is embedded in the polyurethane film 210.2 which has entered the carrier. The polyurethane film is an example of a PU element in sports flooring. In addition, portions 504 and 506 are wetted by and are embedded in the liquid polyurethane reaction mixture 210. Thus, the carrier, portions of the fibers inserted in the carrier and further portions 602 of the fibers at the front side of the carrier may become embedded in the polyurethane backing in addition to the portions 506 on the back side of the carrier. This embodiment of FIG. 6B is advantageous in that the RFS containing PU foam reaction mixture penetrates through the carrier and can form a PU backing layer on the front side of the carrier as well. This may further increase the tuft bind.

[0154] The liquid polyurethane reaction mixture 210 added in the backing process on the back side of the carrier surrounds and thereby mechanically fixes at least some portions of the monofilaments of the arranged artificial turf fibers. Then, the liquid polyurethane mixture 210 solidifies into a polyurethane artificial turf backing 210' at room temperature or in an oven. The solid film acts as the artificial turf backing. In some examples, additional backing layers may be added on the bottom of the artificial turf backing. The polyurethane artificial turf backing 210' is an example of a PU element in sports flooring.

[0155] Examples

[0156] As shown in Table 1 below, it has been found that small amounts of castor oil used as the RFS in the PU reaction mixture at amounts of 3,5 pphr (parts for hundred resin in Example 1) and 5.0 pphr (example 2) increase the tenacity and tear resistance of the PU backing. The percent elongation at 3.5 pphr increased compared to the reference and at 5.0 pphr was lowered near the value of the reference example. The reference example PU backing was prepared as described above with a PU reaction mixture comprising in weight percentages about 21.5% isocyanate, 0.5 % PBD, 21.5 % PEG, 2.1% catalyst, and 2.5 % additives like dyes, flame retardants, and the remainder filler material (chalk). Table 1

[0157] Moreover, addition of the RFS over the color in the PU machine allows for appropriate dosing without changing the compounding process. Exemplary dosing rates are given in the following table 2:

[0158] Table 2 Process: Viscosity and foam stability

[0159] Importantly, addition of the RFS can be done without adjustment to production layout on all common machine. A benefit of adding the RFS is low viscosity during compounding and processing. In particularly, bio-polyols from castor oil or soybean oil have higher viscosity than comparable petrol-based polyols as it can be seen from the following Table 3 which includes examples of petrol-based polyols and bio-based polyols.

[0160] Table 3

[0161] High viscosity petrol-based components increase the viscosity of the compound mixture and, thus increase the load on the pumps during processing. By contrast, it has been found that using bio-based polyols over the color circumvents the associated viscosity increase during the processing. Moreover, the addition of the isocyanate preferably in the mixing head lowers the viscosity. Therefore, a late introduction of the bio-based polyol has no process related draw backs.

[0162] Hence, the addition of the RFS such as the castor oil, soybean oil and or polyols based on castor oil and / or soybean oil provides higher foam stability. More specifically, the higher viscosity is associated with the higher foam stability by hindering the foam to coalesce. Moreover, late addition of the RFS, preferably as part of the color paste, further improves the stability of the foam and allows proper mixing without increasing the compound viscosity.

[0163] It has been further found that mixing the RFS in the color paste with phthalocyanine green (Phthalocyanine green G) and / or phthalocyanine blue (also known as cupper phthalocyanine, phthalo blue, or CuPc), and preferably with the phthalocyanine green pigment is particularly advantageous because it prevents migration or leaching out of the pigment from the turf fiber. This effect is particularly pronounced with the phthalocyanine green pigment. It is postulated that this may be because phthalocyanine green contains many chlorine atoms which may create hydrogen bonds with the hydrogen atoms of the RFS thus creating a much bigger complex with reduced mobility in the fiber.

[0164] Figure 7 shows the back-side of an artificial turf with a homogeneously colorized secondary backing. The pigment used for creating a petrol-like color comprised phthalocyanine green mixed with a bio-based polyol from castor oil. Using an RFS allowed to stabilize a homogeneous distribution of this pigment within the PU reaction mass until the secondary backing had cured completely.

[0165] Figure 8 illustrates the changes in the molecule structure of an exemplary transesterified biobased polyester polyol component 702 throughout the enzymatic transesterification, wherein this transesterified bio-based polyester polyol component is part of the polyurethane reaction mixture 210. Using such a transesterified bio-based polyester polyol component improved the processability of the polyurethane reaction mixture due to its narrow weight distribution and chemical uniformity in particular compared to physical mixtures of different polyols. In figure 8 the first natural fatty acid 704 is ricinoleic acid which is bound at the positions sn-1, sn-2 and sn-3 to the alcohol backbone of the triglyceride ricinolein (shown at the top left under item 1.), the ricinolein being the first natural fatty acidcontaining ester 706.

[0166] As an example of a second natural fatty acid-containing ester 710, the structure of a triglyceride statistically found in soybean oil is shown under item 5. This triglyceride contains different second natural fatty acids 708, namely linoleic acid and oleic acid (both labeled "Rnew" in items 2., 3. and 4. after the transesterification has been performed). Depending on the initial ratio of ricinolein and the second natural fatty acid-containing ester 710 a specific number of ricinoleic acid molecules at positions sn-1 or sn-3 are replaced leading to the substitution patternd shown under items 2. 3. and 4. Due to the high selectivity of the enzymatic process, substitution occurs only at sn-1 and sn-3 (if there is an excess of the second natural fatty acid-containing ester, also the ricinoleic acid at position sn-2 of the ricinolein may also be substituted), where the likelihood of substitution at either position in unmodified ricinolein is equally probable. The higher the ratio of the second natural fatty acid-containing ester 710, the greater the degree of substitution. Under item 6. a transesterified derivate of the triglyceride of item 5. is shown. In this example, the linoleic acid at position sn-3 has been substituted with a ricinoleic acid from the ricinolein, where the linoleic acid was introduced for example at the sn-3 position of the ricinolein (cf. item 3.). The fatty acids that were located at position sn-3 respectively were exchanged between the two triglycerides.

[0167] Depending on the initial ratio, mixing the triglyceride shown under item 5. and ricinolein in the presence of an enzyme suited for catalyzing a transesterification, will result in a mixture of monools, diols and triols where linoleic acid and oleic acid from the soybean oil triglyceride have replaced the ricinoleic acid at the sn-1 and / or the sn-3 positions of ricinolein. This reduces the total number of hydroxyl groups available for a cross-linking reaction, since in contrast to ricinoleic acid, linoleic acid and oleic acid do not contain hydroxyl groups. This reduction in cross-link density may lead to a polyurethane that is more flexible and has improved elongation properties which are desirable characteristics for artificial turf where durability under physical stress is required.

[0168] For example, in the case the reaction product of the transesterification reaction will contain only diols, the reaction of the transesterified bio-based polyester polyol component with an isocyanate component would result in a linear polyurethane. If at both, the sn-1 and sn-3, positions (cf. item 4.), the ricinoleic acids are replaced with fatty acids that lack hydroxyl groups, the resulting transesterified triglyceride cannot integrate into the PU backbone during polymerization. This is because it has only one hydroxyl group available to react with an isocyanate group from the isocyanate component to form a urethane linkage. The reaction between this singular hydroxyl group and the isocyanate results in the triglyceride being covalently bound to the PU backbone as a side chain. This structure acts as a plasticizer, enhancing the flexibility of the polyurethane, while the stability of the urethane links prevents it from migrating or leaching from the PU matrix.

[0169] If the triglyceride is not covalently bound to the PU, the longer the chain of the fatty acids comprised in the triglyceride, the lower the tendency of migration inside the PU matrix. Similarly, adjusting the polarity of the fatty acids through functional groups that are not hydroxyl groups, such as ether groups, affects the migration tendency and the plasticizing effect of the triglyceride. A high polarity reduces the tendency to migrate and increases the plasticizing effect since polar groups of the triglycerides interact more strongly with the polar groups in the PU, particularly the urethane groups, thereby weakening the intermolecular interactions.

[0170] A commercially available example of a lipase that selectively catalyzes the substitution at the positions sn-1 and sn-3 is Lipozyme® TL IM from Novo Nordisk A / S.

[0171] Although the substitution at the positions sn-1 and sn-3 is described herein, depending on the specific application other substitution patterns including the substitution at sn-2 are thinkable. For this other lipase may be utilized that are known to also show activity at the sn- 2 position of triglycerides, termed "non-specific lipases". Examples for these non-specific lipases are Candida rugosa lipase or rhizopus oryzae lipase.

[0172] Apart from the non-specific lipases, it is also thinkable to use lipases that predominantly or exclusively targeting the sn-2 position of triglycerides. These enzymes are termed "sn-2 specific lipases" or "regiospecific lipases." One well-known example is pancreatic lipase- related protein 2 (PLRP2), which is highly specific for the sn-2 position of triglycerides.

[0173] Further examples

[0174] In table 4 the composition of the reaction mixture of Example A for the enzymatically transesterification of castor oil with soybean oil and linseed oil is shown. The nominal OH functionality refers to the number of hydroxyl groups statistically comprised in one molecule of the component. Hydroxyl equivalents per weight (labeled OH Eq Wt in the rightmost column) refers to the amount of the component, required to provide one equivalent of hydroxyl groups. It is a measure to calculate the functionality of polyols in terms of their ability to contribute hydroxyl groups to a reaction. The hydroxyl equivalent weight is calculated as the molecular weight of the component divided by the number of hydroxyl groups it contains.

[0175] Table 4 (Example A)

[0176] In tables 5 and 6 below, the reaction mixtures of Example B and Example C are shown. In contrast to Example A the reaction mixture also comprises PPG2000 to increase the number of hydroxyl equivalents per weight.

[0177] Table 5 (Example B)

[0178] As shown in table 6, the reaction mixture of Example C does not contain any linseed oil.

[0179] Table 6 (Example C)

[0180] The ratio by weight of castor oil to the total amount of linseed oil and soybean oil may be kept at a value of 1:1 or higher to ensure that the number of triglycerides in the resulting transesterified polyester polyol component with no hydroxyl groups is kept at a minimal level.

[0181] Figure 9 shows the comparison of tensile strength of different polyurethanes that are a reaction products of the polymerization reaction in which different amounts of Example A, B and C have been added to the polyol component in the polyurethane reaction mixture. It has been found, that the tensile strength of the most polyurethanes does not decrease significantly up to a ratio of 41.5 parts of a total 100 parts of polyester polyol in the polyurethane reaction mixture. Example C however shows a tensile strength which is almost equivalent to a PU produced without any bio-based polyester polyol in the PU reaction mixture up to a ratio of 83 parts. Given this outcome, it becomes clearthat partially replacing petroleum-based polyester polyols in the polyol component of the PU reaction mixture with enzymatically transesterified bio-based polyols leads to PU that shows similar mechanical properties, in particular tensile strength, as those made entirely with petroleum-based polyols. This shows that the integration of enzymatically transesterified bio-based polyester polyols, even at higher ratios (as demonstrated by Example C), does not compromise the structural integrity of the resulting polyurethane. In particular, keeping the amount of the transesterified bio-based polyester polyols between 20 and 30 wt% of the total polyol components ensures that the mechanical properties, water absorption, and viscosity of the resulting PU are comparable to those produced using entirely petroleum-based polyols. However, higher amounts of transesterified bio-based polyester polyols are possible without drastically diminishing the respective properties of the resulting PU. Depending on the specific PU component of the sports flooring, amounts of up to 80 wt% or even higher are thinkable.

[0182] Figure 10 shows an exemplary sports flooring with PU elements. The PU matrix of the gel layer as well as the primer layer are examples of a PU element comprised in sports flooring.

[0183] An manufacturing of such an exemplary sports flooring is described in the following. A PU reaction mixture is applied on top of a base material, e.g. a concrete floor. The PU reaction mixture comprises a plasticizer and the transesterified bio-based polyester polyol according to the invention. The PU reaction mixture is applied directly on the base material or can be applied on a primer layer that was applied on the base material before and has already hardened. The applied reaction mixture is allowed to form a PU gel layer. The PU gel layer comprises a solid component and a liquid component. The solid component is a matrix of cells made of polyurethane polymers. The liquid component is the plasticizer. For example, a composition of vegetable oils is used as the plasticizer, whereby the composition of the oils is chosen such that the oils remain liquid over a broad temperature range. Preferentially, the typical temperature range of the geographic region where the sports flooring is constructed is taken into account. For example, the composition of the vegetable oils is chosen such that the fraction of unsaturated oils negatively correlates with the temperature: the lower the temperature, the higher the fraction of unsaturated vegetable oils for ensuring that the oils remain liquid. After the formation of the PU gel layer has completed, a top layer is applied on top of the PU gel layer. The top layer seals the floor sports flooring on top of the PU gel layer, thereby preventing rain from penetrating the structure. Optionally, before the primer has dried, silica sand or other forms of granules having the size of silica sand is applied on the primer layer for increasing the surface roughness of the primer layer. After the primer layer has dried, the PU reaction mixture is applied on top of the primer layer as described above for embodiments of the invention.

[0184] Preferentially, a barrier layer is applied on top of the gel layer when the applied reaction mixture has finished forming the PU gel layer. The application of the top layer comprises: after the barrier layer has solidified, applying the top layer on top of the barrier layer.

[0185] According to some embodiments, the substances used for generating the sports flooring are provided in the form of a sports surfacing system that can be customized to different temperature ranges, different appearance and different use case scenarios.

[0186] For example, the top layer is a 100% acrylic emulsion consisting of pigments and PU polymers that are blended into a highly concentrated form that is highly wear resistant. The PU polymer may comprise the transesterified bio-based polyester polyol according to the invention.

[0187] A more concrete example of a possible composition of the barrier layer and the top layer is given below.

[0188] Barrier layer composition (liquid state)

[0189] Acrylic latex solution (dry matter: 60%) 66 %

[0190] Water 22 %

[0191] Ethylene glycol (compatibilizer) 1 %

[0192] Further additives (fungicides, etc.) 11 %

[0193] When the barrier layer has dried and the water (including the water of the acrylic latex solution and of the additives, if any) has evaporated, the barrier layer comprises acrylic latex in an amount of more than 70 % by its weight. It strongly adheres to the polyurethane matrix of the gel layer.

[0194] When the top layer has dried and the water has evaporated, the major weight component of the top layer may consist of the filler material (chalk). In particular, in case the top layer comprises sand in addition to chalk, the top layer may comprise sand and chalk in an amount of more than 60 % by its weight. Thus, the fraction of acrylic latex in the top layer is comparatively small. Nevertheless, as the top layer is preferentially applied not directly on the gel layer but rather on the barrier layer with the compatibilizer, it is ensured that the top layer does not delaminate.

[0195] The primer layer can comprise, for example, about 65 % of a PU prepolymer, about 25% of solvent naphtha (Mixtures of light aromatic hydrocarbons obtained from coal tar or petroleum) and about 10% of Propylene glycol methyl ether acetate (PGMEA, l-methoxy-2- propanol acetate) (an adhesive). For instance, the primer is applied to asphalt, clay or properly prepared concrete.

[0196] The generated sports flooring is a resilient, multi-layered application designed to give added comfort and cushioning for an enjoyable playing experience.

[0197] For example (not shown), the sports flooring comprises EPDM (ethylen-propylen-dien) rubber particles application designed to increase shock-absorbing properties of the structure for. Preferentially, the EPDM rubber particles are embedded in a top layer that consists of non-foamed polyurethane that is directly applied onto the gel layer.

[0198] Before the surfacing system is applied the base material, e.g. concrete or asphalt, needs to be prepared properly, e.g. must be cleaned from dust and moisture. Asphalt and concrete substrates shall be allowed to cure a minimum of 30 days before application of any coatings. The primer can be applied to 5- day old concrete substrates. The base material shall be clean and dry before the different layers are applied. The surface of the substrate shall be inspected and made sure to be free of grease, oil, dust, dirt and other foreign matter before any coatings are applied. Preferentially, the surface and air temperatures should be at least 50 °F (10 °C) and rising for applying the individual layers. Once the surface has been thoroughly cleaned and is free of all loose material, dirt, or dust, the court shall be flooded and allowed to drain a minimum of 30 minutes and a maximum of 1 hour. Any area that holds water in depth greater than 1 / 15 inch shall be outlined and patched with the primer.

[0199] According to embodiments, the primer is mixed by pouring the "B" component into the "A" component (B and A components refer to the isocyanate and polyol components of the PU reaction mixture) and mixing using a low speed jiffy mixer (400 to 600 rpm) for 2 minutes. The mixed primer is applied on the base material using a medium nap rollerto achieve a total coverage of approximately 0.0 30 gal / yd 2 (0.15 kg / m 2 - 300 ft 2 / gal). Optionally, 40 to 60 mesh silica sand is applied onto the wet primer at the rate of 5 pounds per 100 sq. ft. (0.24 kg / m 2) to create e a rough texture. Allow 5 to 6 hours drying time before proceeding with applying additional layers on top of the primer layer.

[0200] The polyurethane reaction mixture may comprise the liquid plasticizer and is applied to a ground in one or more lanes using a vehicle. The polyurethane reaction mixture can be applied directly on the ground or can be applied on top of a primer layer that has been applied previously to seal the ground.

[0201] In case multiple lanes of the gel layer are applied, the lanes are arranged adjacent to each other and a side edge of a first lane is in contact with a side edge of an adjacent second lane of the reaction mixture that generates a PU polymer matrix soaked with the plasticizer as the PU gel layer.

[0202] For example, the PU reaction mixture that is applied on top of the base materials (or the primer layer) is obtained by a method according to the invention. The reactive components comprise a isocyanate component and a polyol component.

[0203] In case multiple lanes are applied, a side edge of the second lane gets in contact with a side edge of the first lane. The process parameters for mixing the polyurethane reactive components are determined so that the PU gel layer and its PU polymer matrix of the first lane is not cured before applying the foam of the second lane.

[0204] The curing time of the polyurethane (PU) matrix may depend on various conditions: in particular the environmental conditions. For example, high temperatures, direct sunlight or low relative humidity may accelerate the curing process.

[0205] The plasticizer is preferentially incorporated into the cells of the forming PU polymer matrix by whisking the liquid plasticizer into the polyurethane reaction mixture or into one of the components of the reaction mixture, e.g. the polyol component. For example, the cellular polyurethane polymer matrix is generated by the oscillation of a tube or pipe reactor fed with the PU mass and the liquid plasticizer and compression and expansion effects are achieved by the oscillation of the tube. The tube is constructed such that air is prohibited from filling the PU matrix cells.

[0206] For example the used PU formulation comprises an MDI based NCO terminal prepolymer, produced from an isomeric mixture of 2,4'; 4,4' and 2,2' MDI monomer based prepolymer with an NCO content of 1.5- 18 weight % with 2,2 MDI between 1 and 40%. A part of the polyol component being either standard or endcapped, activated polyether polyols like polypropylene glycol of the average molecular weight ranging from 100 up to 6000. For example, a high molecular weight primary hydroxyl terminated diol of the molecular weight 2000- 4000 with hydroxylnumbers of 25-60 mg KOH / g is used to produce the NCO terminal prepolymer. Reactivity may be adjusted by using typically suitable metal-organic catalyst like e.g. dibutyltin or dilaurate.

[0207] For example, the NCO terminal prepolymer and the OH terminal polyol are chilled at 10 - 25 °C and pumped in a prefixed ratio through a static mixer, transported to a mixing unit - as e.g. the aforementioned oscillating reaction pipe.

[0208] To avoid undesired excessive foaming a water-adsorbing additive like a zeolite or any other molecular sieve or desiccant can be used. In an embodiment the desiccant can have a pore size of 3-5 angstrom and is used in the range of 0,1 - 3 weight % of the polyol weight, in a very preferred embodiment between 0,5 - 2% of the polyol weight.

[0209] In order to improve the controlling of the curing time, additional polyurethane forming ingredients may be added to the reaction mixture. The type and the quantity of the polyurethane forming ingredients depends e.g. on measured environmental data or on the type of plasticizer used. The additional polyurethane forming ingredients may include one or more of the following: additives, frothing agents or other known additives for polyurethane floorings.

[0210] Preferentially, the components of the PU reaction mixture are chosen such that the generated PU polymer matrix cells more or less completely encapsulate the liquid plasticizer contained in the cells. Thereby, the totality of PU polymer cells largely prevent the plasticizers to escape to other cells or into an inter-cellular space when mechanical pressure is applied on the gel layer.

[0211] The produced PU polymer matrix may be stabilized by a silicone high sheer foam stabilizer enhancing cell stabilization at polymer matrix densities (without the plasticizer) of 200- 400 kg / m3, preferablylOO- 600 kg / m3. For example, the silicone stabilizer is used at 0,1% - 4 weight % , preferably between 1% and 2 %. Furthermore, diverse pigments and fillers can be used like calcium carbonate, bentonite to stabilize the foam further and strengthen its structure. For example, the gel layer may render high elastomeric resilience and good damping properties (achieving a shock absorbance of e.g. > 40% at temperatures of 15°C). According to embodiments, the position and / or the speed of a vehicle for applying the foam to the ground may be measured and the process parameters and the type and the quantity of PU gel layer forming ingredients are adjusted depending on the position and the speed of the vehicle.

[0212] Although the invention has been described in reference to specific embodiments, it should be understood that the invention is not limited to these examples only and that many variations of these embodiments may be readily envisioned by the skilled person after having read the present disclosure.

[0213] List of Reference Numerals

[0214] 102-104-106-108-1022-1024-1026-1028-1029 method steps

[0215] 201 first tank for first mixture

[0216] 202 first mixture

[0217] 203 second tank for second mixture

[0218] 204 second mixture

[0219] 205 third tank or container for third mixture

[0220] 206 third mixture

[0221] 208 mixing head

[0222] 210 polyurethane reaction mixture

[0223] 210' polyurethane backing with RFS

[0224] 212 hose of backing assembly

[0225] 214 opening of hose

[0226] 302 fibers protruding from carrier

[0227] 304 knife

[0228] 306 roll

[0229] 308 carrier, e.g., textile mesh

[0230] 400 polymer mixture for fiber creation

[0231] 402 hydrophobic fiber polymer

[0232] 404 additive

[0233] 406 additive

[0234] 408 plate

[0235] 410 opening of extrusion nozzle

[0236] 412 extruded monofilament

[0237] 501 artificial turf fiber

[0238] 502 cutting step

[0239] 503 fiber loop

[0240] 504 fiber portion within carrier

[0241] 506 fiber portion protruding to the back side of the carrier

[0242] 600 artificial turf 602 fiber portion protruding to the front side of the carrier being embedded in the polyurethane reaction mixture

[0243] 604 fiber portion protruding to the front side of the carrier not being embedded in the polyurethane reaction mixture

[0244] 702 transesterified bio-based polyester polyol component

[0245] 704 first natural fatty acid

[0246] 706 first natural fatty acid-containing ester

[0247] 708 second natural fatty acid

[0248] 710 second natural fatty acid-containing ester

[0249] PU Polyurethane

[0250] RFS Reaction Foam Stabilizer

Claims

CLAIMS1. A method for making an artificial turf, the method comprising: providing a carrier (308) and an artificial turf fiber (501) incorporated into the carrier such that a first portion of the artificial turf fiber (506) protrudes to a back side of the carrier, a second portion of the artificial turf fiber (302) protrudes to a front side of the carrier, and a third portion of the artificial turf fiber (504) is inside the carrier; preparing a polyurethane (PU) foam reaction mixture (210) containing a reactive foam stabilizer (RFS), wherein the RFS is a substance adapted to stabilize the PU foam reaction mixture; and applying the PU foam reaction mixture on the back side of the carrier (308) to cover the artificial turf fiber (506) protruding to the back side of the carrier (308) and allowing the PU foam reaction mixture to harden to form a flexible PU backing securing the turf fiber in place.

2. The method of claim 1, wherein the RFS is bio-based and is at least one of the following substances: a polyester polyol, in particular a polyester diol or polyester triol, based on soybean oil, and / or castor oil, and / or a fat in the form of an ester of a triol with a fatty acid, in particular a triglyceride, in particular castor oil, and, or soybean oil, and wherein the RFS stabilizes the PU foam reaction mixture by increasing the viscosity of the PU foam reaction mixture via hydrogen bonding.

3. The method of any one of the previous claims, wherein the RFS is chemically modified for increasing the number of hydroxyl groups so that more covalent bonds are created with the PU matrix.

4. The method of any of the claims 1 to 3,wherein the RFS is added to the PU foam reaction mixture in one of the components of the reaction mixture or preferably within a color paste additive added in the PU foam reaction mixture.

5. The method of any of the claims 1 to 4, wherein the RFS is added in the reaction mixture before the isocyanate component has been added in the reaction mixture for preventing an excessive increase in the viscosity of the reaction mixture.

6. The method of claim 5, wherein the RFS is added in the color paste additive, and wherein the color paste additive comprises 7% to 60 %, or 10% to 50%, or 15% to 45%, or 20% to 40%, or 25% to 30% by weight pigment, and 40% to 93%, or 50% to 90%, or 55% to 85%, or 60% to 80%, or 70% to 75% by weight RFS, and wherein the PU foam reaction mixture applied to the carrier comprises 1 to 9, or 2 to 6, or 3-5 parts by weight of the color paste, 70 to 120, or 80 to 110, or 90 to 110 parts by weight of a polyol blend comprising a polyol and a filler, and 7 to 21, or 10 to 18, or 12 to 16 parts by weight of an isocyanate.

7. The method of any of the preceding claims, wherein the preparing of the PU foam reaction mixture comprises preparing the polyol blend comprising from 30 to 80 wt% filler and from 70 to 20 wt% polyol, and wherein the polyol comprises a polyether polyol and / or a polyester polyol having at least 2 hydroxyl groups per molecule.

8. The method of claim 7, wherein the polyol blend further comprises a chain extender in an amount from 5 to 50 wt% of the polyol blend, the chain extender comprising at least one of monoethylene glycol, diethylene glycol, triethylene glycol, monopropylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, 1,2,4-butanetriol, and 1, 4 - cyclohexanedimethanol (CHDM), andwherein the polyol is at least one of polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene ether glycol (PTMEG), polyethylene adipate, polycaprolactone polyol, and polybutylene adipate terephthalate; and9. The method of claim 8, wherein the polyol comprises 85% polyethylene glycol 4000 Da, or polyethylene glycol 2000 Da and 15% dipropylene glycol, or wherein the polyol comprises polypropylene glycol 450 to 6000 Da.

10. The method of any of the claims 5 to 9, wherein the color pigment comprises an organic pigment, preferably phthalocyanine green and / or phthalocyanine blue, and more preferably phthalocyanine green.

11. The method of any of the claims 1 to 5, wherein the PU foam reaction mixture further comprises a modified bio-based polyol component (702), the transesterified bio-based polyester polyol component comprising a first fatty acid (704) bound by an ester bound to an alcohol molecule backbone, wherein the transesterified bio-based polyester polyol component is an enzymatically transesterified derivative of a first natural fatty acid-containing ester (706), the first natural fatty acid-containing ester being in particular a triglyceride, in particular ricinolein.

12. The method of claim 11, wherein the reaction components of the enzymatic transesterification reaction of the first natural fatty acid-containing ester include a second natural fatty acid-containing ester (710), the second natural fatty acid-containing ester being in particular a triglyceride, in particular a triglyceride comprised in soybean oil, linseed oil or tung oil.

13. The method of claims 11 or 12, wherein the first fatty acid comprises at least one hydroxyl group, andwherein throughout the enzymatic transesterification the first fatty acid is substituted with a second fatty acid (708) of the second natural fatty acid-containing ester, wherein the second fatty acid comprises fewer hydroxyl groups than the first fatty acid.

14. The method of claim 12, wherein the first natural fatty acid-containing ester is ricinolein, and wherein the second functional fatty acid is selectively introduced at the sn-1 position and / or the sn-3 position of the ricinolein.

15. The method of the claims 12 to 14, wherein the second fatty acid introduced has a chain length from 8 to 22 carbon atoms, in particular 10 to 20 carbon atoms, in particular 14 to 18 carbon atoms.

16. The method of any of the claims 11 to 15, wherein the amount of the transesterified bio-based polyester polyol component is between 10 and 80 wt%, particularly between 20 and 60 wt%, particularly between 30 and 50 wt% of the total amount of all polyol components in the PU foam reaction mixture.

17. The method of any of the claims 11 to 16, wherein the PU foam reaction mixture further comprises a polyether polyol, the polyether polyol being selected from the group containing polyethylene glycol (PEG), polypropylene glycol (PPG), in particular PPG 2000, polytetramethylene ether glycol (PTMEG), or combinations thereof.

18. An artificial turf obtained by the method of any of the preceding claims.

19. An artificial turf comprising: a carrier (308) and an artificial turf fiber (501) incorporated into the carrier such that a first portion of the artificial turf fiber (506) protrudes to a back side of the carrier, asecond portion of the artificial turf fiber (302) protrudes to a front side of the carrier, and a third portion of the artificial turf fiber (504) is inside the carrier; and a flexible polyurethane (PU) foam backing (210') formed on the back side of the carrier securing the artificial turf fiber (506) by covering the second portion of the artificial turf fiber (302), wherein the flexible polyurethane (PU) foam backing (210') comprises covalent bonds of at least one of oleic acid, linoleic acid, stearic acid, palmitic acid, or ricinoleic acid, preferably, palmitic acid or ricinoleic acid, and more preferably ricinoleic acid with carbon atoms of an isocyanate used in the formation of the polyurethane backing.

20. The artificial turf of claims 15 or 16, wherein the PU backing has a thickness of 0.1 mm to 5.0 mm, or 0.1 mm to 4.0 mm, or 0.1 mm to 2.0 mm, and a tuft bind of at least 10 Newtons, or at least 15 Newtons, or 10 Newtons to 30 Newtons, or 15 Newtons to 30 Newtons.

21. The artificial turf of any of the claims 17 to 19, wherein the PU backing comprises an enzyme or a characteristic fragment of the enzymatically active site of the enzyme, the enzyme being in particular an esterase, in particular a lipase.

22. An artificial turf polyurethane backing kit comprising a polyol blend with filler and additives, an isocyanate component, and a color paste component, wherein one of the components, preferably, the polyol blend, or more preferably the color paste component contains an RFS selected from the group consisting of: a polyester polyol, in particular a polyester diol or polyester triol, in particular a polyester polyol based on soybean oil, and / or castor oil, and / or a fat in the form of an ester of a triol with a fatty acid, in particular a triglyceride, in particular castor oil and / or soybean oil.

23. Use of color paste containing an RFS for the production of a flexible foam backing for artificial turf, wherein the RFS is selected from the group consisting of:a polyester polyol, in particular a polyester diol or polyester triol, based on soybean oil, and / or castor oil, and / or a fat in the form of an ester of a triol with a fatty acid, in particular a triglyceride, in particular castor oil and / or soybean oil.

24. A method for manufacturing a transesterified bio-based polyester polyol for use in the manufacturing of a polyurethane component in sports flooring, the method comprising: providing a first bio-based fatty acid-containing ester, the first bio-based fatty acidcontaining ester being in particular a triglyceride, in particular ricinolein; providing a second bio-based fatty acid-containing ester, the second bio-based fatty acid-containing ester being in particular a triglyceride, in particular a triglyceride comprised in soybean oil, linseed oil or tung oil; combining the first and the second bio-based fatty acid-containing ester to form a mixture of bio-based fatty acid-containing esters; subjecting the mixture of bio-based fatty acid-containing esters to a transesterification catalyzing enzyme, in particular a lipase, wherein the enzyme catalyzes a transesterification reaction between the first and the second bio-based fatty acid-containing ester to form the transesterified bio-based polyester polyol component.

25. The method of claim 23, wherein the transesterification is carried out a temperature from 20 °C to 80 °C, in particular from 30 °C to 70 °C, in particular from 50 °C to 60 °C.

26. The method of claims 23 or 24, wherein the first bio-based fatty acid-containing ester comprises a first fatty acid, the first fatty acid comprising at least one hydroxyl group, and wherein the second bio-based fatty acid-containing ester comprises a second fatty acid, the second fatty acid comprising fewer hydroxyl groups than the first fatty acid.

27. The method of any one of claim 25, wherein the first bio-based fatty acid-containing ester is ricinolein, andwherein the second functional fatty acid is selectively introduced at the sn-1 position and / or the sn-3 position of the ricinolein.

28. The method of any one of claims 23 to 26, wherein the second fatty acid introduced has a chain length from 8 to 22 carbon atoms, in particular 10 to 20 carbon atoms, in particular 14 to 18 carbon atoms.

29. The method of any one of claims 23 to 27, wherein the enzyme is immobilized on a solid support and the mixture of bio-based fatty acid-containing esters is brought into contact with the solid support, in particular the mixture of bio-based fatty acid-containing esters is passed in a downflow manner through the solid support.

30. A transesterified bio-based polyester polyol obtainable by the method of any of claims 23 to 29.

31. A transesterified bio-based polyester polyol comprising an enzyme or a characteristic fragment of the enzymatically active site of the enzyme, the enzyme being in particular an esterase, in particular a lipase.

32. Using or providing the transesterified bio-based polyester polyol according to claim 30 or 31 for the manufacturing of a polyurethane component in sports flooring.

33. A method for manufacturing a polyurethane reaction mixture for the manufacturing of a polyurethane component in sports flooring, the method comprising: providing a transesterified bio-based polyester polyol component according to claim 30 or 31; providing an isocyanate component, the isocyanate component being in particular MDI (methylene diphenyl diisocyanate), TDI (toluene diisocyanate), HDI (hexamethylene diisocyanate), or IPDI (isophorone diisocyanate); combining the transesterified bio-based polyester polyol component with the isocyanate component to form a polyurethane reaction mixture.

34. The method of claim 34, wherein the polyurethane reaction mixture further comprises at least one of the following: a filler component, the filler component particularly comprising ground limestone, chalk (precipitated calcium carbonate), China clay, coal fly ash, silicates (in particular zeolites), and combinations thereof; a color paste component, the color paste component particularly comprising phthalocyanine green, chromium oxide green, chrome green or phthalocyanine blue, and combinations thereof; a chain extending component, the chain extending component particularly comprising MEG (monoethylene glycol), DEG (diethylene glycol), TEG (triethylene glycol), MPG (monopropylene glycol), DPG (dipropylene glycol), TPG (tripropylene glycol), BDO (1,4-butanediol), butanetriol (also known as 1,2,4-butanetriol) or 1, 4 - cyclohexanedimethanol (CHDM), and combinations thereof.

35. A method for manufacturing sports flooring comprising a PU element, providing a polyurethane reaction mixture obtainable by the method of claims 33 or 34; initiating the reaction of the isocyanate component and the transesterified biobased polyester polyol component in the polyurethane reaction mixture, wherein the polyurethane of the PU element is formed; assembling the sports flooring using the PU element.

36. A sports flooring obtainable by the method of claim 35.

37. The sports flooring of claim 36, wherein the PU element comprises an enzyme or a characteristic fragment of the enzymatically active site of the enzyme, the enzyme being in particular an esterase, in particular a lipase.

38. A sports flooring of claim 36,wherein the PU element comprises the transesterified bio-based polyester polyol component.

39. The sports flooring of any one of claims 36 to 38, wherein the structure of the sports flooring comprises:- a top layer that seals the sports flooring; and- a PU gel layer comprised of a solid and a liquid component between a base material and the top layer, the solid component being a polyurethane polymer matrix, the liquid component being a plasticizer, wherein the PU element is the polymer matrix of the PU gel layer or a primer layer below the PU gel layer.

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