Method for producing raw material for use in manufacturing artificial turf fibers, and method for producing fiber of said raw material and fibers obtained thereby

Abstract

Methods for producing a raw material for use in the manufacturing of artificial turf fiber, which raw material comprises reclaimed artificial turf fiber, which methods comprise separating a fiber fraction from an artificial turf and cleaning it by whirling the fiber fraction inside a flow chamber having an outer screen at a periphery of the flow chamber to obtain a purified fiber fraction, and filtrating the purified fiber fraction in a melt filter to provide a filtrate which is recovered as said raw material. The disclosure further relates to artificial fiber comprising reclaimed turf fiber and methods for producing such artificial fiber.

Description

[0001] Method for producing raw material for use in manufacturing artificial turf fibers, and method for producing fiber of said raw material and fibers obtained thereby

[0002] Field of Technology

[0003] The present invention relates to a method for producing raw material for producing artificial turf fibers which raw material comprises reclaimed artificial turf fibers. The invention further relates to a method for producing artificial fibers using reclaimed artificial turf fiber.

[0004] Background

[0005] Synthetic turf (artificial turf) has been used for many years as surfaces for football, baseball and soccer fields. In the recent years it has been used in other applications where an alternative to natural grass is desired. These applications include at least playgrounds, residential and commercial lawns and other landscaping, paths, paintball fields, tennis courts, putting greens, dog runs etc.

[0006] Typically, synthetic turf includes a grass-like fabric having a backing and a plurality of upstanding ribbons, also called face fibers, resembling grass. Many synthetic turf products also include an infill material dispersed among the upstanding ribbons, which may consist of sand, tire rubber crumb, or other particulates, either singularly or in combination with each other. The infill material simulates the soil in natural turf, acts as a ballast, and / or contributes to the physical properties of the turf, such as resiliency, that makes the turf suitable for a particular use. The face fibers, or turf fiber, is often made from polyethylene or polypropylene. Synthetic turf typically has a coating to attach the turf fiber to the backing, which coating is often polyurethane.

[0007] Synthetic turf has a limited life span, depending on the construction of the turf, the application for which it is used, weathering and how the turf is maintained.

[0008] As an example, a typical synthetic turf for use as an athletic field may have a useful life of from about 8 to 15 years. A large amount of synthetic turf is currently being used in hundreds of athletic fields and in other applications. Disposing of the turf is very expensive due to the composition of materials ranging from recycled rubber, sand to plastic. To avoid sending the turf to landfills at a substantial cost, recycling and reusing all or portions of the synthetic turf has been an explored option over recent years. Recycling and reusing synthetic turf involve separating the components of the synthetic turf in order to reclaim the components at a degree of purity sufficient for the intended use of the reclaimed component.

[0009] One separation process is described in W02010 / 075098 in which infill is separated from the backing and the grass like fibers followed by downsizing and further removal of infill followed by agglomeration. The granules of agglomerated turf fragments are placed into an extruder. The granules are extruded to form an extrudate, for example in the shape of a strand or ribbon. As only the infill is removed the granules obtained is a mixed material composed of multiple synthetic turf components, and thus of limited purity, which restricts the options for reusing the material.

[0010] A similar process is described in US2014 / 312526A1 disclosing separating the filler (infill) from the base (backing) and fiber of the artificial turf, crushing the base and fiber and forming a solid reproduction material therefrom by injection or extrusion. The solid reproduction material thus comprises both fiber and backing and is a mixed material of limited purity.

[0011] EP2096211B1 describes another method for disposing of synthetic grass in which grass fiber and backing are first separated from infill and additional components and then subsequently separated in a large number of steps. A grass fiber ("grass filament") portion is thus reclaimed and it is suggested that it may be recycled to produce new synthetic grass filaments however with no disclosure of such method.

[0012] EP2862688 deals with a dry separation process where the individual components are provided essentially pure. The method comprises three specific separation steps in a specific order hence the separation is based on size, specific gravity and specific gravity, size and shape. The process yields a grass fiber portion (turf fiber), sand portions, rubber portions and backing portions.

[0013] Hence, existing process can separate the components of synthetic turf thereby providing materials which in terms of recycling have a higher quality than mixed materials.

[0014] When recycling materials it is desirable to achieve closed-loop recycling where the product at the end of its lifetime is recycled to make the same product. Having once already made a material to meet the requirements of a specific product, recycling the material into the same product re-captures the value of the material.

[0015] However, recycled materials generally have less than acceptable physical properties at least in part due to wear and contamination arising during the life time. Hence, the extent to which such Post-Consumer-Recycled material (recycled material from a product after its use, as defined by ISO 14021:2016) can be used in a product is often limited. These general considerations also apply to synthetic turfs, where it for example is desirable to recycle reclaimed grass fiber into new artificial grass fiber. Hence, there has been an interest in making artificial grass fibers which include recycled grass fiber material and at the same time fulfills the requirements with regards to stability and appearance.

[0016] US2010 / 00622192 describes an artificial turf wherein the grass blades are partially formed of polyester of terephthalic acid from waste (PET or PBT). In a specific embodiment, the blades are a core-sheath type fiber and the core part of the fiber is formed from PET from waste, whereas the sheath is formed from virgin PET mixed with coloring agent and a UV stabilizer. The artificial turf is thus made partially from waste material, but the waste material used is PET which is typically used in plastic bottles, but not for artificial turf fibers which is commonly made of PE or PP.

[0017] More recently, WO2021 / 067534 described a filament and an artificial turf carpet including said filament. The filament includes a blend of virgin LLDPE and a post-consumer recycled material ("PCR") essentially consisting of LLDPE and LDPE. The PCR material is obtained from used packaging and poses challenges in terms of processability due to extrusion instability and filament breakages. However, by combining the PCR material with virgin LLDPE the blend becomes processable and has acceptable mechanical properties. Both monofilaments and core / sheath type filaments are made with the blend, where in the latter the core is made from the blend while the sheath is made from virgin LLDPE. Hence, there are artificial turf fiber solutions which allow for incorporation of recycled polymer material such as from packaging waste, but there is still a need for artificial turf fibers which include turf fiber reclaimed from artificial turfs in order to maintain the quality of the well-known and tested materials used for artificial turf. Artificial turf contains contaminants of a different nature and level than typically encountered in for example packaging waste, such as bottles.

[0018] Processes allowing for such recycling of turf fiber is a step towards closed- loop recycling of artificial turfs. This recycling of fiber however poses significant challenges in terms of the purity of the reclaimed artificial turf fibers as even small amounts of impurities pose a challenge for the extrusion process, such as sand blocking the extrusion die. Another problem is breakage of the extruded fiber due to contaminants, as even small amounts of contaminants cause significant local weakening of the thin fiber filament. While there are known methods for separating fiber from the remaining components of the artificial turf, achieving the desired purity of the separated fiber fraction for use as a raw material for high quality artificial turf fiber remains a challenge. The separation of fine particles, such as fine sand, from the reclaimed artificial turf fiber has proven to be a particularly challenging task, especially in an efficient manner without a prohibitive amount of processing steps and consumption of resources such as water.

[0019] Therefore, it is an object of the invention to provide a method for preparing a raw material for use in producing artificial turf fibers from reclaimed artificial turf fibers, and especially an efficient method for producing said raw material. Moreover, it is an object of the invention to provide an artificial turf fiber, such as a high-quality artificial turf fiber, which includes material from reclaimed artificial turf fiber.

[0020] Summary of the invention

[0021] These and further objects are achieved by a first aspect of the invention providing a method for preparing a raw material for use in the manufacturing of artificial turf fiber, which raw material comprises reclaimed artificial turf fiber, preferably polyolefin turf fiber, said method comprising the following steps: (a) separating a fiber fraction from an artificial turf,

[0022] (b) cleaning the fiber fraction by whirling the fiber fraction inside a flow chamber to form a vortex flow while keeping a material outlet of the flow chamber closed, which flow chamber has an outer screen arranged along at least a portion of a periphery of the flow chamber, the material outlet being connected to the flow chamber, to provide a heavy fraction at a bottom of the flow chamber, a purified fiber fraction inside the flow chamber, and a fines fraction on a side of the screen which side faces away from the flow chamber,

[0023] (c) filtering the purified fiber fraction in a melt filter to provide a filtrate, and

[0024] (d) recovering the filtrate as the raw material for producing artificial turf fibers, said raw material is optionally in granular form.

[0025] The initial separation of the fiber fraction in step (a) may be performed in a manner known to the skilled practitioner, e.g. by combination of agitation to dislodge infill, shredding of the turf material, separation by screening, separation by specific gravity and particle size e.g. in a cyclone or an air sifter. A suitable method is described EP2862688 to the same applicant and another preferred method is described PCT / EP2023 / 050214 both of which yield a turf fiber portion separated from an artificial turf.

[0026] The initial separation step (a) and preferred embodiments thereof are described in greater detail below. The term "fiber fraction" as used herein refers to the turf fiber portion of the artificial turf. The term "turf fiber" refers to fibers imitating grass in the artificial turf. The terms "grass fiber" and "turf fiber" may be used interchangeably. In addition to turf fiber, the fiber fraction may comprise additional material from the artificial turf, which is not turf fiber, but which is the same material as the turf fiber. This may be the case if for example part of the backing of the artificial turf is made of the same material as the grass fiber, as is often the case.

[0027] The fiber fraction obtained in step (a) is a thermoplastic material. The fiber fraction obtained in step (a) is preferably a polyolefin fraction, more preferably PE and / or PP.

[0028] According to the invention, the fiber fraction is then further cleaned in cleaning step (b) where the vortex flow of the fiber fraction in the flow chamber causes impurities such as sand and rubber particles to pass through the outer screen, thereby further cleaning the fiber fraction.

[0029] The fines fraction contains impurities passing through the screen, while the heavy fraction contains material which is not entrained in the vortex flow due to specific gravity. The heavy fraction may contain infill particles, debris such as stones, and larger organic particles, such as particles having a size greater than 0.2 mm in its longest dimension. The heavy fraction can sediment in the flow chamber and / or in an inlet ducting provided at the bottom of the flow chamber. In the flow chamber, impurities are effectively separated as the flow causes the particles to collide with each other and the outer screen, thereby efficiently dislodging impurities. The material outlet is for collecting the purified fiber fraction from the flow chamber. During operation i.e. step (b) the material outlet is kept closed thereby providing a batch operation.

[0030] Once cleaning step (b) is completed, the material outlet is opened to collect the purified fiber fraction from the flow chamber. A means for conveying the purified fiber fraction, e.g. by providing an airflow, through the material outlet may be provided to effect the collection of the purified fiber fraction. Additionally, or alternatively, the purified fiber fraction is collected while maintaining the vortex flow, but with the material outlet open. The material outlet may be connected to a collection means, such as cyclone in which the purified fiber fraction can sediment and be collected.

[0031] The outer screen can be provided along a portion or the entirety of the periphery of the flow chamber. The flow chamber may be a circular cylinder where the vortex flow is a rotational flow around a central axis of the flow chamber.

[0032] The purified fiber fraction is then filtrated using the melt filter of step (c), wherein the turf fiber material passes through the screen as a melt, and further impurities are retained by the filter. Impurities removed in the melt filter include higher melting polymers and residual sand if any. The term "higher melting" denotes materials having a higher melting temperature than the turf fiber material. Typically, the turf fiber is PE and / or PP which have a lower melting point than for example PET or other polyesters. Such higher melting polymers are often used in other parts of artificial turfs, as well as polyamides which are sometimes used in artificial turfs as well. The filtrate from the melt filter is recovered as the raw material. The recovery typically comprises obtaining the raw material in granular form, e.g., by using a pelletizer.

[0033] The specific cleaning operation according to the invention provides a fiber fraction which can be used as a raw material for extruding new artificial turf fiber at high quality. It will be appreciated that the raw material provided by the invention has sufficient purity allowing it to be extruded into a new fiber, but this does not limit the applications of the raw material. The raw material can also be used to make new fiber for other products than turf, or even non-fiber products.

[0034] In some embodiments, there is provided a method wherein step (b) is implemented in a cleaning unit comprising the flow chamber with the outer screen, a bladed rotor arranged at the bottom of the flow chamber, and an inlet connected to the flow chamber, and whereby step (b) comprises the steps of

[0035] (bl) feeding the fiber fraction to the flow chamber through the inlet

[0036] (b2) whirling the fiber fraction in the flow chamber by way of rotation of the bladed rotor while keeping the material outlet closed,

[0037] (b3) collecting the fines fraction from the side of the screen facing away from the flow chamber,

[0038] (b4) collecting the heavy fraction at the bottom of the flow chamber, and

[0039] (b5) opening the material outlet to collect the purified fiber fraction.

[0040] This type of cleaning unit is especially suited for the cleaning step (b) providing effective cleaning while being energy efficient. The bladed rotor can create the required vortex flow and turbulence for an effective cleaning. The bladed rotor may be a centrifugal fan, where rotor blades rotate to generate an air flow perpendicular to the axis of rotation. The bladed rotor has an axis of rotation of the bladed rotor which is parallel or co-axial, preferably co-axial, with a central axis of the flow chamber, whereby the generated air flow will cause a rotational air flow in the flow chamber around the central axis, i.e. a vortex flow.

[0041] As previously mentioned, the flow chamber may be a circular cylinder. The inlet may be provided as a duct connecting to the bottom of the flow chamberthrough an opening therein.

[0042] In some embodiments, step (bl) comprises feeding the fiber fraction by providing an air flow through the inlet. The air flow may be provided by a unit for generating an air flow from the inlet through to the flow chamber. The air flow may be provided by rotation of the bladed rotor. This may be achieved by arranging the inlet to the flow chamber in connection with the bladed rotor, e.g. as said duct connecting to the bottom of the flow chamber, and equipping the bladed rotor with a suction fan for pulling air and the fiber fraction through the inlet into the flow chamber. The suction fan may be combined with the aforementioned centrifugal fan of the bladed rotor, in which case the centrifugal fan is a first impeller of the bladed rotor and the suction fan is a second impeller of the bladed rotor.

[0043] In some embodiments, there is provided a method wherein the outer screen has a screen size in the range of 0.5 to 10 mm, preferably 0.55 to 6 mm, more preferably 1 to 5 mm, even more preferably 2 to 3 mm and most preferably 2.5 mm. Such screen sizes effectively clean the fiber fraction, removing fine contaminants while retaining as much fiber as possible in the purified fraction.

[0044] In some embodiments, there is provided a method wherein the bladed rotor of the cleaning unit has a rotational speed in the range of 10 to 1500 RPM. The motor driving the rotation of the bladed rotor may be torque controlled or not torque controlled. Using a torque controlled motor is preferred. The rotational speed of the bladed rotor is selected such that the fiber fraction whirls around in the flow chamber.

[0045] If the speed is too low the fiber fraction is not entrained in the vortex flow, and if the speed is too high the fiber fraction is forced too strongly towards the periphery of the flow chamber, thereby reducing friction and agitation and thus the effectiveness of the cleaning. The rotational speed will depend on the density and size of the particles in the fiber fraction being cleaned, where fibers with a higher dtex value will need a greater speed than fibers with a lower dtex value. In some embodiments, there is provided a method further comprising adding an air flow to the flow chamber, preferably at a rate in the range of 10 to 10000 Nm3 / hr. The air flow is supplied through one or more air inlets of the cleaning unit. The inlet connected to the flow chamber through which the fiber fraction is fed to the flow chamber may at the same time be an air inlet. The air flow may enter through the centrifugal fan of the bladed rotor. The airflow provided fluidizes the fiber fraction and entrains impurities which are carried through the outer screen, improving the cleaning of the fiber fraction.

[0046] In some embodiments, a heated air flow is provided to the flow chamber. The heated air flow may have a temperature greater than 40, 50, 60 or even 70 °C. The heated airflow has the effect of drying, further drying the fiberfraction or keeping the fiber fraction dry depending on the moisture content, which can reduce the proneness of the particles in the fiber fraction to stick together, thereby improving the cleaning of the fiber fraction. Separation step (a) may comprise drying the artificial turf and thus the fiber fraction, in which case drying of the fiber fraction by the heated air flow may not be necessary.

[0047] In some embodiments, the method comprises further cleaning the purified fiber fraction by repeating step (b) in a second flow chamber to provide a second heavy fraction, a further purified fiber fraction, and a second fines fraction, wherein step (c) comprises filtrating the further purified fiber fraction to provide filtrate.

[0048] In some embodiments it is at least a portion of the second heavy fraction which is recycled to the step of cleaning the fiber fraction.

[0049] Repeating cleaning step (b) in a second flow chamber may further improve the cleaning of the purified fraction. The second flow chamber is the same type as the aforementioned flow chamber, and features described herein in relation to the flow chamber also apply to the second flow chamber.

[0050] In embodiments where step (b) is repeated, the flow chamber used in the initial cleaning step (b) may be referred to as the first flow chamber. The second flow chamber may have dimensions that are different from the first flow chamber, hence it may suitably have a smaller capacity, as the volume of purified fiber fraction obtained from the first flow chamber is smaller than the volume of fiber fraction fed to the first flow chamber.

[0051] The outer screen of the second flow chamber may have a screen size which is different from the screen size of the first flow chamber used in the initial cleaning step. The screen size of the second flow chamber may preferably be smaller than the screen size of the first flow chamber. In such an embodiment, the second flow chamber provides for a polishing of the purified fiber fraction while the first flow chamber provides for an initial cleaning. Alternatively, the outer screen of the second flow chamber may have a screen size equivalent to that of the outer screen in the first flow chamber, i.e a screen size in the range of 0.5 to 10 mm, preferably 0.55 to 6 mm, more preferbaly 1 to 5 mm, even more preferably 2 to 3 mm and most preferably 2.5 mm.

[0052] In a further development of embodiments employing the aforementioned cleaning unit, the further cleaning by repeating step (b) is implemented in a second cleaning unit which comprises the second flow chamber, which is the same type as the aforementioned cleaning unit. Repeating step (b) in the second cleaning unit comprises performing steps (bl) to (b5) in the second cleaning unit. In this case, the aforementioned cleaning unit may be referred to as the first cleaning unit. The second cleaning unit is the same type as the first cleaning unit, and features described herein in relation to first cleaning unit also apply to the second cleaning unit, unless otherwise specified. The material outlet of the first cleaning unit is suitably in fluid communication with the inlet of the second cleaning unit, allowing the purified fiber fraction to be transferred to the second cleaning unit.

[0053] In a still furtherdevelopment of the abovementioned embodiments, at least a portion of the second heavy fraction is recycled to step (b), specifically step (b2) in embodiments using the cleaning unit, of cleaning the fiber fraction. Recycling the second heavy fraction has been found to increase a yield and purity of the further purified fiber fraction. Heavy non-fiber particles, such as infill particles and debris, are generally removed in the first cleaning (step (b) in the first flow chamber, but the second heavy fraction may contain fiber material and this fraction is in a preferred embodiment recycled to the initial cleaning step thereby increasing the yield. The amount of second heavy fraction may constitute 1 to 50 w / w % of the purified fiber fraction, such as 2 to 40 w / w %, 3 to 30 w / w%, 4 to 20 w / w %, or 5 to 10 w / w %. By recycling these amounts of purified fiber fraction, the purity of the further purified fiber fraction may be increased. Preferably, all of the second heavy fraction is recycled to the first cleaning step. Collecting and recycling the second heavy fraction may be achieved by providing suitable ducting and conveying means, e.g. means for providing an air flow. The second heavy fraction may also be collected manually by an operator and added to a fiber fraction which is to be cleaned in the first flow chamber.

[0054] In a still further development, there is provided a method wherein step (b) is repeated in the second cleaning unit wherein one or more of a rotational speed of a bladed rotor of the second cleaning unit, and an airflow to the second flow chamber is selected to provide a predetermined amount of second heavy fraction. The predetermined amount of second heavy fraction may be the amounts of the second heavy fraction mentioned in the preceding paragraph. . By adjusting the rotational speed of the bladed rotor of, and / or an air flow rate of the second cleaning unit, the magnitude of the second heavy fraction can be adjusted.

[0055] In some embodiments, there is provided a method wherein step (c) comprises filtrating in a laser melt filter and / or a screen melt filter, preferably both a laser melt filter and a screen melt filter. It is preferred that filtration step (c) comprises two filtrations steps, e.g. in a laser filter and in a screen melt filter.

[0056] The screen type melt filter has a mesh which is typically replaced during operation as it becomes fouled, e.g. upon reaching a feed pressure and / or pressure drop thresholds. The mesh may be a wire screen. The laser type melt filter has a metal plate with holes typically made by a laser or by drilling. In some embodiments, the holes in the metal plate are conical. A laser filter allows for continuous scraping of the inlet side of the laser filter to achieve continuous and steady operation and steady filtration pressure. Mesh filters are typically less capital intensive than laser filters, but the latter may prove more operationally efficient, as there is less downtime and manual intervention. Mesh filters may also yield slightly in the mesh structure, which may allow soft solid contaminants to pass, i.e. rubber, which is not the case for laser filters. In one embodiment which is presently considered advantageous, filtration step (c) comprises two filtration steps, first a laser filter step and secondly a mesh filter step downstream thereof, wherein each melt filter has a respective extruder feeding material to the melt filter. The laser filter may then retain a majority of the impurities, while the mesh filter (also termed screen filter) has a smaller screen size and provides a subsequent polishing filtration. Additional screen filters may be used, such as two screen filters downstream of the laser filter.

[0057] In some embodiments, there is provided a method wherein the melt filter comprises filter having a size in the range 5 to 450 pm, or 50 pm to 400 pm, with 10 to 300 pm being preferred and 50 to 200 pm even more preferred. This range of screen sizes have been found to be suitable for cleaning reclaimed turf fiber. Generally, as the screen size decreases the purity of the filtrate increases. However, filtration pressure may also increase while capacity decreases, making operation more complicated and costly. It has been found that using a screen size in the range 150 to 250 pm is suitable for most applications of the raw material, but smaller screens may be considered for applications requiring even greater purity, such fibers with a low dtex linear density. If the raw material is used in a compound with for example virgin polymer, the requirements for the purity of the raw material may also be reduced, in which case larger screen size may be suitable. In embodiments employing multiple melt filters in step (c), the upstream filter may have a greater screen size than the downstream filter. The filter size used may depend on the artificial turf being processed, in particular the particle size of any residual sand remaining in the purified fiber fraction. The melt filter advantageously removes any residual sand, hence selecting a filter size according to the particle size of the sand is advantageous.

[0058] In embodiments wherein the filtration step comprises a laser filter and one or more screen filters downstream of the laser filter, the laser filter may have a screen size in the range of 10 to 300 pm and more preferred in the range of 50 to 200 pm, and the subsequent screen filters may have a screen size in the range of 10 to 300 pm, and more preferred in the range of 50 to 200 pm.

[0059] A measure of the purity of the raw material can be provided by the filter pressure value (FPV) of the raw material. EN 13900-5 provides a method for determining the FPV.

[0060] Another measure of the purity of the raw material is the particle size of impurities in the raw material. A raw material may for example comprises impurities having particles sizes at or less than 10, 50, 100, 250 or 500 pm (in order of decreasing purity). As the particle size is used to compare the relative purities of raw materials, any particle size measurement may in principle be used. For example, the D50 particle size in a volume distribution may be used.

[0061] In some embodiments, there is provided a method wherein step (c) comprises controlling a pressure drop in the melt filter to a pressure set-point, which pressure set-point is constant. This may be referred to as a "constant pressure mode" of the melt filter. The pressure drop is the pressure across the filter in the melt filter, which is the difference between a pressure at an inlet side of the filter and a pressure at an outlet side of the filter. By "controlling to a pressure set-point" is understood that the melt filter is operated so as to maintain the pressure drop at the pressure setpoint. The pressure drop can be controlled by manipulating a feed flow rate to the melt filter, for example by adjusting the speed of an extruder screw which feeds purified fiber fraction to the melt filter. Hence, the constant pressure mode can be achieved by a feed-back control loop where the feed flow rate of purified fiber fraction is manipulated in response to a measured pressure drop compared to the pressure set-point. Operating the melt filter to control the pressure drop to the pressure set-point, provides constant pressure filtration, which may improve the purity of the filtrate. Typically, melt filters are operated at dynamic pressure but at a constant flow rate. In this typical operation, the pressure increases as the filter fouls during operating to maintain the flow rate of filtrate. Without being bound by theory, constant pressure filtration may provide improved purity of the filtrate as the purified fiber fraction may contain soft impurities, such as rubber from the infill, which soft impurities may be prone to deform when subjected to pressure, which deformation increases the risk of the soft impurities passing through the filter and into the filtrate. Soft impurities in the filtrate can lead to filament breakages when the raw material obtained from the filtrate is extruded to a fiber, which is discussed in greater detail below. By controlling the pressure drop, the risk of soft impurities passing the filter is reduced, leading to a more pure filtrate.

[0062] A laser filter are advantageously used in step (c), as these allow for continuous cleaning of the inlet side of the filter by a scraper which moves across the inlet side of the filter scraping off impurities and diverting the impurities to a discharge. This reduces fouling of the filter, which facilitates maintaining a constant pressure drop across the filter. Hence, laser filters are especially suitable when operating the filter as a constant pressure filtration. Constant pressure filtration may also be achieved in mesh filters, which typically comprises stopping the filtration when the filter is too fouled and the cleaning and / or exchanging the filter and / or manipulating the feed flow.

[0063] The pressure set-point for the pressure drop of the melt filter may in exemplary embodiments be 30 to 60 bar, such as 30 bar or 60 bar, but other pressure setpoints are conceivable. The pressure set-point may at least in part depend on the filter size, where a lower filter size will have a higher pressure drop. As discussed, the filter size used in the melt filter may depend on the desired purity of the filtrate.

[0064] In preferred embodiments, the pressure set-point for the pressure drop of the melt filter is 30 bar or less, which has been found to provide effective cleaning of the filtrate. The pressure set point may be at least 5, 10, 15, 20 or 25 bar.

[0065] In embodiments wherein step (c) comprises multiple melt filters, one or more of the melt filters may be operated as constant pressure filtrations as described above, and preferably all melt filters are operated as constant pressure filtrations. Hence, in one embodiment the first laser filter step is operated as a constant pressure filtration by controlling the pressure drop of the laser filter to a constant pressure setpoint. The subsequent second mesh filter step may then be operated in a dynamic pressure, but it is preferable to operate the second mesh filter step as a constant pressure filtration as well. In embodiments comprising both a laser filter and one or more screen filters downstream thereof, the pressure set-points of the laser filter and one or more screen filters are preferably 30 bar or less. In other embodiments, step (c) comprises controlling a pressure drop in the melt filter to be at or below an upper pressure threshold. The upper pressure threshold is preferably 30 bar. In some furtherdevelopments, the pressure drop is controlled to be above a lower threshold, which lower threshold may be 5, 10, 15, 20 or 25 bar.

[0066] Step (c) may suitably comprise controlling a pressure in the melt filter(s) to be 80 bar(a) or less, preferably 70 bar(a) or less, on an inlet side of the respective filters. Similarly, the temperature in the melt filters may suitably be controlled to be 225 °C or less. In some preferred embodiments, the melt filters (laser filters and possible downstream screen filter) are operated to maintain a pressure drop of 30 bar or less and a maximum pressure of 80 bar(a) or 70 bar(a) on the inlet side of the filter(s). The pressure drop may be controlled by controlling to the pressure set-point or to the upper pressure thresholds as described above.

[0067] The preferred pressure ranges for the pressure set-point or upper pressure threshold and pressure on the inlet side of the filters, suitably applies to laser filters having the preferred screen size in the range of 10 to 300 pm, more preferred 50 to 200 pm and screen filters having the preferred screen size in the range of 10 to 300 pm, more preferred 50 to 200 pm as described above.

[0068] It is contemplated, that filtering step (c) may comprise initially operating the melt filter in a dynamic pressure mode while the pressure drop of the melt filter is below a pressure threshold, which dynamic pressure mode comprises not controlling the pressure drop of the melt filter to a pressure set-point, and when the pressure drop of the melt filter reaches the pressure threshold, then operating the melt filter in a constant pressure mode, which constant pressure mode comprises controlling a pressure drop in the melt filter to a pressure set-point, which pressure set-point is constant. The pressure threshold may be the same as the pressure set-point. The dynamic pressure mode may comprise operating and constant flow rate, e.g. at constant extruder speed.

[0069] In some embodiments, there is provided a method wherein step (a) comprises separating the artificial turf (1) into the fiber fraction, into an infill portion and a backing material portion. It is preferred that the artificial turf is separated into the fiber fraction, the infill fraction and a backing material fraction prior to the cleaning in step (b). Suitably step (a) involves downsizing, sieving and separations by density and / or specific gravity, which can provide said fractions. Methods for separating may be according to EP2862688A1.

[0070] Preferred methods for separation are described in greater detail below and also in WO2023131668Alto the same applicant and as detailed in the claims.

[0071] As previously mentioned the raw material obtained by the method described above is sufficiently pure to be used in the production of new fiber for other products than turf, or even non-fiber products. For example, the raw material can be used in injection or blow moulding production processes to make non-fiber products. The raw material may also be used for other parts of an artificial turf than the turf fiber, such as in secondary backing which may be made wholly or in part from the raw material. A given raw material may be characterized and matched to a specific target application. For example, for use in artificial turf fiber, the raw material may need to meet criteria established by e.g. FIFA or KNVB, such as DSC peak (ISO 11357) or type and amount of polyolefins (DSC-FTIR).

[0072] A similar characterization may additionally be performed on the fiber fraction prior to processing into raw material, to pre-screen and select fiber fractions which will yield a raw material satisfying the criteria of the target application. Type and content of polyolefins (or other polymers) may be determined by DSC-FTIR, mineral content by ISO 3451, melt flow index ASTM D1238, density by ISO1183, and melting peak ISO 11357.

[0073] In a second aspect of the invention there is provided a method for producing a fiber, preferably a turf fiber for an artificial turf, from reclaimed artificial turf fiber, comprising the steps of

[0074] (e) providing a fiber raw material comprising reclaimed artificial turf fiber, optionally further comprising virgin polymer and / or one or more additives selected from antioxidants, and processing aids, and

[0075] (g) extruding the fiber raw material to form the fiber or to form a film which film is then processed to form a slit-film fiber. Using reclaimed turf fiber as a source for producing the fiber has substantial environmental benefit as the source material was originally made with properties suitable as turf fiber and re-using it in a fiber makes use of those properties once more, rather than downcycling the material into a product which does not benefit from the quality of the source material. In the context of fiber extrusion, the term "fiber" is sometimes used to denote a strand which is short in comparison to a "filament" which term is used to denote a continuous (i.e. long) strand. In the present disclosure, the terms fiber and filament are interchangeable.

[0076] The fiber raw material may be extruded directly to form a fiber, i.e. a monofilament type turf fiber. Alternatively, the fiber raw material can be extruded to form a film which can be processed to a slit-film type fiber. Slit-film type fibers are processed from the film by cutting to create individual fibrils. Various patterns of slit-film type fiber is known to the skilled person and the term "slit-flim fiber" is not limited to any specific pattern.

[0077] In some embodiments, the fiber raw material comprises virgin material. Mixed fiber raw material comprising both reclaimed turf fiber and virgin material may be preferred for some applications. In addition, or as an alternative to the virgin margin material, the fiber raw material may comprise post-industrial polymer material. The reclaimed turf fiber is thermoplastic and hence extrusion is suitable for producing the fiber. Suitable extrusion means for step (g) are known to the skilled person. Such fiber extrusions are sometimes referred to as extrusion spinning in the field of polymer fibers.

[0078] The fiber raw material may comprise additives such as antioxidants, processing aids, colorants, and UV-stabilizers.

[0079] Suitable anti-oxidants are octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)- propionate (CAS 2082-79-3), pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxy- phenyl]propionate (CAS 6683-19-8), Tris(2,4-ditert-butylphenyl) phosphite (CAS 31570-04-4). Processing aids and UV-stabilizers are known the skilled practitioner in the field of plastic processing.

[0080] In some embodiments, the fiber is a single-component fiber. The term single-component fiber refers to a fiber which through its cross-section is composed of one material, as opposed to bi-component fibers which are made of two materials which are distinct in the cross-section. A fiber which consists of a fiber raw material comprising reclaimed turf fiber and virgin polymer, where the reclaimed turf fiber and virgin polymer are the same type, e.g. polyolefins, are considered a single-component fiber. As the reclaimed turf material is a PCR material, it will be limited in some respects as it has already been designed with a specific application in mind. For example, it will typically have a green color which lends itself poorly for further coloring, hence a single-component fiber may be limited in some respects, such as color.

[0081] If further versatility is desired, the fiber may be a bi-component fiber. Hence, in some embodiments a method for producing a fiber is provided, wherein the fiber is a core-shell type fiber, further comprising the step of

[0082] (f) providing a shell material, which shell material comprises polymer material and additives, wherein the polymer material is selected from virgin polymer, PostIndustrial polymer material, Post-Consumer polymer material, or mixtures thereof, and the additives are selected from one or more of colorants, UV-stabilizers, and antioxidants and processing aids, and wherein step (g) comprises co-extruding the fiber raw material and the shell material to form the core-shell type fiber, the fiber raw material forming a core of the core-shell type fiber and the shell material forming a shell of the core-shell type fiber.

[0083] This provides a fiber where the shell provides the versatility, e.g. in coloring, of the virgin polymer material while the core material provides the benefits of recycling material. The shell material can be virgin polymer, Post-industrial material, Postconsumer polymer material or mixtures thereof. Post-Industrial material is material as defined in ISO 14021:2016. It will be appreciated that Post-industrial material is a substantially pure material. Recycling of post-industrial material into new products does not generally require substantial sorting and cleaning operations. This is unlike PCR materials which have often been mixed with other materials and / or contaminated during the lifespan of the product. Hence, if Post consumer polymer material I used for the shell material, it will typically, but not necessarily, be in a mixture further comprising virgin and / or post industrial waste.

[0084] The shell material may form between 1 % and 99 % of the fiber, where the percentage refers to the dtex linear density of the core-shell type fiber. At the same time the core may form between 1 % and 99 % of the fiber, referring to the dtex linear density.

[0085] In order to increase the amount of recycled material being use and reduce the amount of virgin material being used, it is preferred that core material forms at least 30 %, at least 35 %, at least 40 %, at least 50 %, at least 60 %, at least 70 % and even at least 80 % of the core-shell type fiber, where the percentage refers to the dtex linear density of the core-shell type fiber.

[0086] To the same end, it is preferred that the fiber raw material, which forms the core material, is at least 70 %, at least 80 %, at least 90 %, at least 95 % or at least 98 % by mass recycled artificial turf fiber. The remainder preferably does not comprise virgin polymer material (PE and / or PP), but is formed by additives. Such core materials may suitably be used for core-shell fibers wherein the core forms at least 40 % or at least 50 % of the fiber by linear density.

[0087] The shell forms an exposed surface of the fiber and may thus comprise UV- stabilizers, the use of which is known to the skilled practitioner.

[0088] An alternative bi-component fiber is a slit-film fiber, wherein the extruded film is a multilayer film. Slit film fiber is also referred to as "tape yarn" or "tape fiber", but all refer to fibers made by extruding a film or "tape" which is then cut to form individual fibers.

[0089] Hence, in some embodiments a method for producing a fiber is provided, wherein the fiber is a slit-film fiber, the method further comprising the step of

[0090] (f') providing a cover material, which cover material comprises polymer material and additives, wherein the polymer material is selected from virgin polymer, Post-Industrial, post-consumer polymer material, or mixtures thereof, and the additives are selected from one or more of colorants, UV-stabilizers, and anti-oxidants, and wherein step (g) comprises co-extruding the fiber raw material and the cover material to form a multilayer film, the fiber raw material forming a first layer and the cover material forming a cover layer of the multilayer film, which multilayer film is then processed into the slit-film fiber.

[0091] The multilayer film may comprise at least two layers: the first layer and the cover layer arranged there to cover one face of the first layer. However, it is preferred that that the multilayer comprises three layers, with cover layers arranged on opposite faces of the first layer. In this way the cover layers will form an exterior surface of the slit-film fiber formed from the multilayer film. Typically, the two cover layers will be formed of the same cover material, but in some applications different cover materials are contemplated. For example, cover layers of different color may be chosen for visual purposes. As discussed in relation to the shell material above, if the cover material comprises post-consumer polymer material, it will typically, but not necessarily, be in the form of a mixture with virgin or post-industrial polymer material.

[0092] In a preferred embodiment there is provided a method for producing a fiber, wherein the reclaimed artificial turf fiber is obtained using mechanical separation of artificial turf. The first aspect of the invention is a mechanical separation of artificial turf. Mechanical separation has the advantage of high capacity and comparatively low costs.

[0093] In a preferred embodiment, there is provided a method for producing a fiber, wherein the reclaimed artificial turf fiber is obtained a method according to the first aspect of the invention, including according to any of the embodiments of the method described herein.

[0094] In some embodiments, there is provided a method for producing a fiber reclaimed artificial turf fiber constitutes 25 w / w% or more of a total polymer content of the fiber, preferably 35 w / w% or more, more preferably 50 w / w% or more, most preferably 70 w / w% or more of the total polymer content, wherein the total polymer content is the mass sum of reclaimed artificial turf fiber, virgin polymer, and Post-Indus- trial polymer material in the fiber.

[0095] As previously described in relation to the first aspect of the invention, the obtained raw material preferably comprises polyolefin turf fiber, and more preferably PE turf fiber. Similarly, the fiber raw material used in the second aspect of the invention to produce fiber, preferably a turf fiber, preferably comprises reclaimed polyolefin turf fiber, more preferably reclaimed PE turf fiber. Accordingly, the raw material comprising polyolefin turf fiber, preferably PE turf fiber, obtained by the first aspect of the invention, may be (part of) the fiber raw material in the second aspect of the invention. When the reclaimed artificial turf fiber in the fiber raw material comprises polyolefins, and preferably comprises PE, then the other polymer materials used to produce fiber according to the second aspect of the invention may also comprise polyolefins, preferably PE, which other polymer materials refers to the virgin polymer, post-industrial polymer material or post-consumer polymer material used as part of the fiber raw material, of the shell material or of the cover material. In this way, both the reclaimed turf fiber material and the other polymer material, all comprise polyolefins, and preferably PE.

[0096] In a third aspect of the invention, there is provided a fiber comprising reclaimed artificial turf fiber, preferably wherein the fiber is a turf fiber for an artificial turf. The fiber is preferably obtained by a method according to the second aspect of the invention.

[0097] Turning now to the initial separation step (a) of the first aspect of the invention wherein a fiber fraction is obtained from the artificial turf. As previously described, step (a) preferably separates the artificial turf into the fiber fraction, the infill fraction and the backing portion, which may generally be achieved by combining downsizing, drying, sieving and separations by specific gravity.

[0098] In a preferred embodiment, the separation step (a) comprises a feeding and a downsizing section, an infill separation section and a turf and backing separation section, wherein said feeding and downsizing section is in fluid communication with the infill separation section and the turf and backing separation section, and wherein the feeding and downsizing section comprises the following steps: (al) feeding a moist artificial turf to the feeding and downsizing section, (a2) downsizing the moist artificial synthetic turf into a downsized turf material, preferably to no more than 120 by 120 mm, and feeding the downsized turf material to a drying unit,

[0099] (a3) drying the downsized turf material in the drying unit, for example in a drum drier, to a moisture content of no more than 5% w / w, preferably no more than 3% w / w, most preferably no more than 1% w / w, to a dried material,

[0100] (a4) separating the dried material by screening in a first sieving unit into at least a first fraction substantially comprising an infill material which is fed to the infill separation section and a second fraction substantially comprising turf fiber and backing components,

[0101] (a5) downsizing the second fraction substantially comprising turf fiber and backing components to at most 50 mm in the largest dimension in a downsizing unit and optionally feeding the further downsized fraction to a first screening unit, such as a drum screen having openings of 4 to 8 mm, preferably, 6 mm, to provide a small fraction and a large fraction,

[0102] (a6) feeding the further downsized fraction or if present, the large fraction obtained in step (a5) to a material hopper continuously supplying the fraction, optionally downsized further to at most 35 mm in the largest dimension, to the turf and backing separation section; and

[0103] (a7) further processing the first fraction obtained in step (a4) and the small fraction, if present, obtained in step (a5) in the infill separation section, wherein the turf and backing separation section comprises the steps of

[0104] (a8) separating the downsized fraction or large fraction obtained in step (a5) downsized further to at most 35 mm in the largest dimension, by specific gravity and size by providing an airflow directed upwards in a second separator configured to cause a swirling motion whereby a second lighter fraction is entrained upwards in the air flow and a second heavy fraction is allowed to fall downwards; where the second lighter fraction substantially comprises turf fiber components, and second heavy fraction substantially comprises a mixture of backing material and turf fiber component, and a9) recovering the second lighter fraction as the fiber fraction.

[0105] The drying air temperature of step (a 3) at the entry of the drying unit suitably has a temperature in the range of 125 to 250°C, preferably 150 to 230°C, the length of the drying unit is 8 to 15 m, preferably 10 to 12 m, and the downsized turf material is fed at a range of 6 to 10 tonnes per hour, preferably 8 tonnes / hour on a dry basis.

[0106] It is preferred that the components during the drying are not melted or agglomerated as this will deteriorate the quality of the end fractions. Hence, temperature, time and size of the components are important factors of the optimal drying that will enable the subsequent separation. Size is important since the feed to be dried is composed of sand and rubber but also the carpet which must be dry too to released integrated infill but without melting. Typically, the components of the carpet have the lowest melting temperature.

[0107] When the drying unit is a drum dryer, it is operated at a speed of 1200 to 1600 rpm, preferably 1400 rpm.

[0108] Once the feed has been suitably prepared by downsizing, drying and initial separation, it is possible in the subsequent sections to separate the distinct components to the required high purity and at a sufficient high yield to enable a cost-efficient process.

[0109] The infill separation section comprises the following steps:

[0110] I) feeding the first fraction obtained in step (a4) and the small fraction obtained in step (a5) to a main sieving unit having three sieving means, a first sieving means, a second sieving means having openings of 0.5 to 1.5 mm, and a third sieving means having openings of 0.1 to 6 mm, wherein the first sieving means is a grate type sieving means having perforations wherein the longest dimension of the perforations is 3 to 6 mm, thereby providing four fractions, an upper fraction, a first and second intermediate fraction and a lower fraction, wherein the first intermediate fraction is further processed for rubber recovery and the second intermediate fraction is further processed for sand recovery.

[0111] The main sieving step separates most of the sand from the rest of the components. Sand is by weight the largest component of the turf. The first sieving means further separates rubber from backing and turf. Hence, this step will enable the more difficult task of being able to provide pure rubber.

[0112] Another challenge in recovering components of turf products is to be able to separate the components at a speed and volume over the sieving area available. Hence, in an embodiment one or more of the sieving means is provided with at least one baffle, preferably on the upper sieving means, such as the first sieving means. It is also contemplated that baffles are present on sieving means in other sieving units in addition to the main sieving unit.

[0113] The baffles will help the feed distribute over the whole are of the sieving means thereby improving the sieving capacity over the time the feed is transported through the various sieving means. It is preferred that the at least one baffle is positioned at an angle (a) in the range of 30 to 60°, preferably, 40 to 50°, such as 45° in relation to a horizontal plane of the sieving means, and that the at least one baffle is attached in the middle section of the sieving means, preferably on a horizontal line between % and % of the length of the sieving means. The angle a may be between the baffle and a line in the horizontal plane, which line is parallel with an edge of the sieving means. The edge may be the edge extending from the inlet to the outlet of the sieving means.

[0114] As the feed moves across the sieving means from the inlet to the outlet the natural movement of the flow will result in the material moving towards the edges of the sieving means. However, when baffles are placed at the specified angle in the specified area of the sieving means, the feed will be evenly distributed over the whole area thereby improving the overall separation.

[0115] It is contemplated that each sieving means has two or more baffles, such as 2, 3, 4 or 5 baffles. The number of baffles may be determined based on the area of the sieving means. Thus, the number of baffles needed for optimal separation increases with the area of the sieving means.

[0116] After the main sieving step, the first intermediate fraction is further processed for rubber recovery by the steps of

[0117] II) feeding the first intermediate fraction to a second sieving unit having three sieving means, a first sieving means having openings of 1.2 to 3.5 mm, a second sieving means having openings of 0.8 to 2.5 mm, and a third sieving means having openings of 0.5 to 2.0 mm, thereby providing four fractions;

[0118] III) feeding each of the four fractions obtained from the second sieving unit to a first set of four individual separating means, said means separating by specific gravity using air, to provide four low-density fractions comprising backing material and rubber and a combined high-density fraction comprising additional components, such as stones; in this first rubber recovery step, heavy material such as stones are separated from the mixed fraction. This will enable the more sophisticated separation of rubber from other materials. The stones, if free of rubber, can be reused and sold.

[0119] IV) feeding each of the four low density fractions to a second set of four individual separating means, said means separating by specific gravity using air, to provide a combined low-density fraction comprising backing material and a second combined high-density fraction comprising rubber, and further wherein the second combined high-density fraction comprising rubber is recovered or further processed in a rubber polishing unit; in this second rubber recovery step, the rubber now being the heavy fraction is separated from a mixed fraction comprising backing material. This will allow a further refined processing of the rubber into distinct rubber fractions of different size.

[0120] The combined low-density fraction comprising backing material is further subjected to the steps of

[0121] V) separating by specific gravity and size by providing an airflow directed upwards in a separator configured to cause a swirling motion whereby a lighter fraction is entrained upwards in the air flow and a heavy fraction is allowed to fall downwards; where the lighter fraction comprises backing material, and the heavy fraction comprises additional material, such as stones, the stone fraction may be mixed with the heavy fraction obtained in step V); in step VI) the lighter fraction comprising backing material is subjected to a third sieving step in a third sieving unit having two sieving means, a first sieving means having openings of 2 to 5 mm and a second sieving means having openings of 0.8 to 3 mm, thereby providing three fractions; an upper fraction comprising turf fiber, an intermediate fraction comprising backing and a lower fraction comprising rubber, optionally the upper fraction is returned to the third downsizing means and further processed in the turf and backing separation section; in step VII) each of the intermediate fractions and the lower fraction are fed to a third set of two individual separating means, said means separating by specific gravity using air, to provide a second combined low-density fraction comprising turf material and a third combined high-density fraction comprising a rubber and backing mix.

[0122] By adding these separation steps, turf fiber and rubber - two of the most valuable components for reuse - are provided in substantially pure quality. The additionally recovered turf fiber in the upper fraction can be recycled to turf and backing separation section, i.e. to step (a8). In this way the volume of fiber fraction recovered in step (a9) is increased.

[0123] The fraction substantially comprising sand is separated in the second part of the infill separation section in order to provide, in particular, pure sand. Hence, the method may further comprise the steps of processing the second intermediate fraction obtained in step I) further for sand and rubber separation by the steps of:

[0124] VIII) feeding the second intermediate fraction to a fourth sieving unit having four sieving means said sieving means having perforations in the range of 1.2 to 0.2 mm, where the size of the openings descends from top to bottom, to provide five fractions;

[0125] IX) feeding each of the five fractions to a fourth set of five individual separating means, said means separating by specific gravity using air, to provide a second set of low-density fractions comprising rubber, sand and / or fine fiber particles and a fourth combined high-density fraction comprising sand, wherein said fraction comprising sand is recovered.

[0126] Each of the second set of five low density fractions comprising rubber, sand and / or fine fiber particles are in step X) fed to a fifth set of five individual separating means, said means separating by specific gravity using air, to provide a low density fraction and a high density fraction as stipulated below. When 30% vol / vol or more of the second set of low-density fractions is rubber, a third combined light fraction comprising rubber is provided, and a fourth combined heavy fraction comprising a mix of sand and rubber is provided, said heavy fraction is recycled to the fourth sieving unit in step VIII); and when 30% vol / vol or less of the second set of low-density fractions is rubber, a fifth combined heavy fraction comprising sand is provided, and a fourth combined light fraction comprising a mix of rubber and sand is provided, wherein the sand is recovered, and the mix of rubber and sand may be further processed or discarded.

[0127] In the further step IX) sand is first recovered, and the next step is determined based on the presence of rubber in the fraction. In this way the process can flexibly be customized to compositions where the rubber is over or below 30% vol / vol. This has shown to result in the purest fraction of either sand or rubber. The remaining mix fraction may then either be discarded or can be further treated if the plant has capacity that is not utilised at a given point in time, such as in the infill after cleaning section.

[0128] This diverging of fractions is important since obtaining completely pure rubber is essential for being able to sell the fraction at a sustainable price.

[0129] The further processing and separation of the rubber may be performed by feeding one or more of the rubber fractions obtained throughput the process, such as the second combined high-density fraction obtained in step IV) and / or the third combined light fraction obtained in step X) when comprising rubber which is in embodiments where 30% vol / vol or more of the second set low-density fractions is rubber.

[0130] The fractions are further processed by the step of feeding one or more rubber fractions to a fifth sieving unit having three sieving means, a first sieving means having openings of 1.5 to 4 mm, a second sieving means having openings of 0.7 to 1.5 mm, and a third sieving means having openings of 0.2 to 0.7 mm, thereby providing three distinct rubber fractions and a dust fraction.

[0131] In a variation of the above, the fifth sieving step may be preceded by feeding one or more of the rubber fractions to a unit capable of beating fine particles loose from the rubber particles, such as a hammer mill and feeding the thus beaten mixture to the fifth sieving unit. In order to be able to run the entire process in a continuous manner at a certain speed, it may be desired to have buffer tanks at specific locations. Hence in an embodiment a buffer tank is in fluid communication with the unit capable of beating fine particles loose from the rubber particles, such as a hammer mill, is present, the buffer tank receives rubber fractions obtained throughout the process.

[0132] In order to increase the yield or minimize waste from the process, it is desirable to include an infill after cleaning section in the process and system. In the infill after cleaning section one or both of the heavy fraction comprising rubber, stone, and optionally sand which is obtained in step V) and the combined high density fraction obtained in step III) are processed further the section comprises the steps of:

[0133] XI) feeding one or both of the heavy fraction comprising rubber, stone, and optionally sand and the combined high-density fraction, to a sieving step in a sixth sieving unit having two sieving means, a first sieving means having openings of 0.4 to 3 mm and a second sieving means having openings of 0.2 to 2 mm, thereby providing three fractions; an upper fraction, an intermediate fraction and a lower fraction;

[0134] XII) feeding each of the three fractions to a sixth set of three individual separating means, said means separating by specific gravity using air to provide a fifth combined low-density fraction comprising rubber and a sixth combined high-density fraction comprising stone and sand, and further wherein the rubber is recovered or further processed in the rubber polishing section, such as by feeding to the buffer tank or mixing with one or all of the second combined high-density fraction obtained in step IV) and / or the third combined light fraction obtained in step X) when comprising rubber which is in embodiments where 30% vol / vol or more of the second set low- density fractions is rubber. Hence, by adding this step, the yield of the rubber fraction is further increased, and the waste of the overall process reduced.

[0135] In parallel with the infill separation route, the feeding and downsizing section is also connected to the turf and backing separation section where the large fraction obtained in step (a 6) in a step (a7) is downsized further to at most 35 mm in the largest dimension, and separated by specific gravity and size by providing an airflow directed upwards in a second separator configured to cause a swirling motion whereby a second lighter fraction is entrained upwards in the air flow and a second heavy fraction is allowed to fall downwards; where the second lighter fraction substantially comprises turf fiber components, and second heavy fraction substantially comprises a mixture of backing material and turf fiber component. In some embodiments, the second lighter fraction is further processed in a further step (a8.1), which is prior to step (a9), wherein the second lighter fraction substantially comprising turf fiber components is fed to a second screening unit, preferably a drum screen, having openings of 1 to 3 mm in the shortest dimension, to provide a final small fraction comprising backing and turf fiber waste and a final large fraction comprising turf fiber. The final large fraction comprising turf is then recovered in step (a9) as the fiber fraction.

[0136] The fiber fraction recovered in step (a9) can then be further processed in a turf cleaning section which comprises the steps (b) to (d) of the first aspect of the invention. The screening step (a8.1) in the second screening unit may alternatively be performed as part of the turf cleaning section in between steps (b) and (c). In such an alternative embodiment, the second screening unit receives the purified fiber fraction and the large fraction retained by the second screening unit is then passed to the melt filter in step (c).

[0137] According to all embodiments and steps, when using the separators configured to cause a swirling motion whereby the lighter fraction is entrained upwards in the air flow and the heavy fraction is allowed to fall downwards the unit is in preferred embodiments a cyclone separator or a zig-zag air sifter. When the separation is performed in a zig-zag air sifter the air is provided at a frequency of 18 to 27 Hz, more preferred 20 to 25 Hz. Tests were performed with various frequencies above and below the ranges above, and it was surprisingly found that the best separation was obtained within the ranges disclosed, and the best result was obtained at around 20 to 25 Hz.

[0138] The task of separating turf / grass fiber and backing becomes more and more difficult when the size of the mixed components becomes smaller and smaller. Thus, as the size becomes smaller the difference in weight of the individual components approximates. On the other hand, downsizing is a necessary means for being able to disintegrate the various components of the turf material. Therefore, downsizing at the specific points in the separation has turned out to be effective, since otherwise problematic components have substantially been separated off in the previous steps.

[0139] Also provided is a system for processing moist synthetic turf product in a continuous manner to provide individual components of synthetic turf product, said system comprising a feeding and a downsizing section an infill separation section and a turf and backing separation section, said feeding and downsizing section is in fluid communication with the infill separation section and the turf and backing separation section, wherein the feeding and downsizing section comprises an inlet for moist artificial turf product which is connected to downsizing unit such as a shredder, the outlet of the downsizing unit is connected to a drying unit, the outlet of the drying unit is connected to a first sieving unit which has two outlets, a first outlet which is connected to the infill separation section and a second outlet which is connected to a second downsizing unit capable of downsizing components to at most 50 mm in the largest dimension, the outlet of the second downsizing unit is connected to a material hopper, optionally through a first screening unit, such as a drum screen, having openings of 4 to 8 mm, preferably, 6 mm, said first screening unit has two outlets, a first outlet, a retentate, and a second outlet, a filtrate, where the first outlet is connected to the material hopper, which is continuously supplying the retentate fraction to a third downsizing unit, preferably a cutting mill, the outlet of the third downsizing unit is connected to the turf and backing separation section and the second outlet, the filtrate, is connected to the infill separation section.

[0140] The process and system are configured for continuous processing of the three main sections, the feeding and downsizing, the infill separation section and the turf and backing separation section. The infill after cleaning section can be connected to the infill separation section as required by enabling the flow of various fractions as described above.

[0141] Generally, the methods described herein can be performed in a single facility containing equipment for performing all method steps, which is considered advantageous. If expedient it is also possible to split the processes in two or more facilities, with suitable storage and transport in between. Similarly, it is possible that only part of a fraction obtained from a cleaning step under step (a) is sent to the subsequent method step. One example is steps (a) and (b) where it is possible that not all of the fiber fraction that can be obtained from step (a) is further cleaned in step (b). Step (b) is a further cleaning of the fiber fraction, which makes it suited for applications which require the additional purity. However, the demand for the further purified fiber fraction can be less than the production of fiber fraction is step (a), in which case it is possible to further clean only a portion of the fiber fraction from step (a). Similarly, it may be expedient to have steps (a) and (b) split in different facilities. This would also make it possible to collect fiber fractions obtained from multiple facilities performing step (a) and combining them for further cleaning in step (b).

[0142] Another split which is presently considered advantageous is to combine steps (a) and step (b) in a single facility or process line which produces the purified fiber fraction as an intermediate product. This intermediate product can then be sent for filtration in step (c) if needed. It may be advantageous to integrate the melt filtration step (c) with a fiber extrusion process, i.e. steps (e) to (g), as the melt filtration step is a more similar unit operation to those used in compounding fiber raw material and fiber extrusion. Accordingly, also disclosed herein is a method for producing a purified fiber fraction from an artificial turf, which method comprises steps (a) and (b) as described herein. In a preferred variation of this method, step (b) is provided following step (a8) and optionally followed by step (a8.1) as previously described. Such a method may conceivably be used to clean a non-thermoplastic intermediate product, which is then not subjected to a subsequent melt filtration.

[0143] Brief Description of the Drawings

[0144] In the following the invention will be described with reference to the exemplary drawings, where

[0145] Fig. 1 is a schematic diagram of a method of producing a raw material from reclaimed turf fiber and a subsequent method for producing core-shell type turf fiber from the raw material,

[0146] Fig. 2 shows a schematic drawing of a cleaning unit for step (b) of a method of producing a raw material,

[0147] Fig. 3a-b shows a cross-section of a core-shell type fiber and a multilayer film respectively,

[0148] Fig. 4 shows a schematic diagram of a process for processing an artificial turf and for recovering components thereof which includes separation of a fiber fraction from the artificial turf,

[0149] Figs. 5 to 9 shows details of an embodiment of the process in Fig. 4,

[0150] Figs. 10, lOa-b and 11 show details of embodiments of sieving means used in the processes in Fig. 4 to 9.

[0151] Detailed Description

[0152] Figure 1 is a schematic diagram of the method according to the first aspect of the invention comprising step (a) where a fiber fraction 33, 35 is separated from an artificial turf 1, turf cleaning section 500 comprising steps (b) to (d) where the fiber fraction 35 is processed into a raw material 506 suitable for making artificial turf fiber, and fiber extrusion section 600 comprising steps (e) to (f) where the raw material 506 is processed into an artificial turf fiber 607 which comprises the reclaimed artificial turf fiber 35.

[0153] In an initial step (a) there is provided an artificial turf 1, which has been retrieved from an installation site, e.g. a sports field, at the end of its lifespan, and a fiber fraction 35 is separated from the artificial turf 1. As the artificial turf 1 has been used for its intended purpose, the fiber fraction 35 separated from it is a Post-Con- sumer-recycled (PCR) material as defined as ISO 14021:2016.

[0154] Separation step (a) may be any process by which turf fibers are separated from the artificial turf 1. In general, these processes are multistep processes which comprise downsizing steps, sieving steps and separation by specific gravity and size. As the turf fibers are comparatively large particles with a low density compared to the other components, infill, of the artificial turf 1, turf fibers can be recovered as the large fraction of an initial sieving step followed a separation by specific gravity, such as by an air sifter (zig-zag sifter), or more generally a separation unit where an upwards air flow entrains the turf fiber while components with higher density fall down. Prior to the initial sieving the artificial turf may be downsized to a size no greater than 120 mm in its longest dimension and dried if the artificial turf is wet. Following the initial sieving, but prior to the separation by specific gravity and size, the large fraction is suitably downsized further, preferably to a size of at most 35 mm in the longest dimension. In the embodiment in figure 1, the separation step (a) further provides a backing portion 34, and an infill portion provided as separate rubber portions 29a-c and sand 23. The aforementioned separation by specific gravity and size yields the backing portion 34 as the high-density fraction not entrained in the airflow. Sand 23 and rubber 29a-c collectively form the infill of the artificial turf 1, which will pass collectively through the initial sieving step as the small fraction and can be separated into rubber and infill by sieving and separation by specific gravity. A preferred embodiment of the initial separation step (a) is discussed in greater detail below with reference to figures 4 to 11. This process can separate the fiber fraction 33, 35 from the artificial turf 1 and further provide backing portion 34 and infill portions 29a-c, 23. While fiber fraction 33, 35 thus obtained comprises substantially fiber material, some impurities remain and even low levels of impurities can cause issues if the fiber fraction 35 is used in extrusion of a fiber, e.g., when making artificial turf fiber. Hence, further cleaning in turf cleaning section 500 is needed to enable re-use of the fiber fraction 35 in new fibers.

[0155] Turning now to the first step of the cleaning section 500, namely step (b) where the fiber fraction 35 is cleaned by whirling it inside a flow chamber (not shown) to form a vortex flow as the first step in turf cleaning section 500. The flow chamber has an outer screen along at least a portion of a periphery of the flow chamber and the flow inside the flow chamber will force the material being cleaned against the outer screen whereby a fines fraction 502 passes through the outer screen. The fines fraction generally comprises fine fiber particles, rubber and inorganic contaminants such as sand. The inorganic contaminants may be about 50 % of the fines fraction, which can be determined measuring the ash content. That step (b) removes rubber is beneficial as rubber can sometimes pass through a melt filter, as the rubber is soft in the melt. Rubber contaminants in the raw material 506 can disrupt the fiber extrusion in section 600, as the rubber can provide a section of the fiber which has a different elasticity than the surrounding material, which can lead to breakage when the fiber is subjected to strain.

[0156] The material in the flow chamber will impact itself and the flow chamber walls, which in combination with the significant turbulence in the flow chamber, will dislodge contaminants from the fiber particles, thereby cleaning of the fiber fraction 33, 35. The cleaning also provides a heavy fraction 502 generally recovered at a bottom of the flow chamber, which heavy fraction 502 does not enter the vortex flow. The term vortex flow is used to denote a rotational flow around a central axis of the flow chamber, whereby the material being cleaned experiences a centrifugal force. It is understood that the flow pattern in the flow chamber can simultaneously have other flow components than the rotational flow component (vortex), such as an axial flow component where the material being cleaned moves up and down in the flow chamber, and a radial flow component moving toward and away from the central axis of the flow chamber. The flow chamber is typically a circular cylinder where the periphery is the cylindrical surface. The outer screen can extend along a part of the periphery as an outer screen section or along the entirety of the periphery. Having an outer screen section simplifies construction. It is also conceivable to have multiple outer screen sections. Whirling the fiber fraction in the flow chamber may suitably be achieved by a rotating member provided at the bottom of the flow chamber, such as a bladed rotor. The cleaning in step (b) is a batch operation, where the fiber fraction 33, 35 remains in the flow chamber during the cleaning until sufficiently cleaned and the cleaning step is terminated. The flow chamber generally has a material inlet and a material outlet where the fiber fraction 35 enters and purified fiber fraction 503 exits the flow chamber respectively. The material outlet is closed during the cleaning step so that a batch of fiber fraction can be cleaned. Step (b) may comprise repeating the cleaning in a second flow chamber operating equivalently to provide the purified fiber fraction 35. Cleaning units suitable for step (b) and repetitions thereof are discussed in greater detail below with reference to figure 2.

[0157] The purified fiber fraction 503 obtained from step (b) has a lower content of sand, rubber and backing material than the fiber fraction 35 obtained by step (a).

[0158] Subsequently, the purified fiber fraction 503 is filtrated in a melt filter where a filtrate 505 passes through the melt filter screen while retaining impurities 504. The retained impurities 504 comprise sand particles as well as polymer components which have not been melted. Typically, the purified fiber fraction 35 is fed to the melt filter by an extruder (single or double) which transports and melts the purified fiber fraction 35. The filtration step (c) may comprise more than one melt filter. The melt filtration step may also entail a degassing of the melt, e.g. by a vacuum degassing unit.

[0159] In step (d) the filtrate 505 is recovered as a raw material 506 for use in manufacturing artificial turf fiber. This raw material 506 has a purity allowing it to be extruded into a fiber. When the raw material does not have sufficient purity, the extruded fiber may be prone to break due to imperfections in the filament caused by contaminants. Similarly, solid particles such as sand may block the extrusion die and thereby interrupt the production process. The raw material may be recovered in forms known to the skilled practitioner, such as in granulates / pellets using a pelletizer, e.g. an underwater pelletizer. A pelletizer may be coupled to the melt filter of step (c), for example using a strand pelletizer system.

[0160] A fiber extrusion section 600 is shown in Figure 1 comprising steps (e) to (g). In this embodiment the fiber extrusion section 600 is for producing core-shell type fiber including both a core material 603 and shell material 606, but in alternative embodiments the fiber extrusion section 600 is for producing a single-component fiber from the raw material 506. The term single-component fiber refers to fiber which through its cross-section is made from one component. In such an alternative embodiment, step (f) in Figure 1 and shell material 606 are omitted. As the raw material 506 is made from reclaimed artificial turf fiber, it will have an existing color, which limits the color options of the raw material. Hence, a single-component fiber made from the raw material 506 may have limited color options, whereas the core-shell type fiber has, among others, the advantage of a broad range of color options by coloring the shell material 606. In yet another alternative, the fiber extrusion section is for producing a film or multilayer film from which a slit film-type fiber can be made.

[0161] Turning now to Figure 2 which shows a cross-sectional view of a schematic view of cleaning unit 510 for cleaning the fiber fraction 35 in step (b). In embodiments where step (b) is repeated in a second cleaning unit, a cleaning unit of the same type as the cleaning unit 510 shown in Figure 2 is also used. The cleaning unit 510 will be described in general, and unless otherwise specified the description applies both to a first cleaning unit cleaning the fiber fraction and to any subsequent further cleaning of the purified fiber fraction in second or further cleaning units. The cleaning unit 510 comprises a flow chamber 511 which is formed as a circular cylinder having central axis 511c where an outer screen 512 extends along part of a periphery of the flow chamber 511. In the embodiment shown, the outer screen 512 is provided on both sides of the cross-section, which can be achieved by one outer screen extending continuously along the periphery or as multiple outer screen sections. Alternatively, the outer screen 512 could be only on one side as a single outer screen section of the periphery. Suitably, the outer screen 512 extends in a section of about 30 to 90 degrees of the periphery, measured as a central angle. A single outer screen 512 extending in a section of the periphery is preferred, as it simplifies construction and maintenance. Embodiments employing one or more such outer screen sections are provided with a solid wall(s) extending along the periphery and between the outer screen section^). On a side 512s of the outer screen 512 which is opposite to the flow chamber 511 and thus faces away from the flow chamber, there is a chamber into which the fines fraction 502 passes. The chamber has an outlet (not shown) through which air and the fines fraction 502 exits continuously. The fines can be collected by suitable means such as a cyclone or a bag filter unit (not shown). The cleaning unit 510 further has a hot air inlet 516 placed centrally in the flow chamber through which hot air can be added if the fiber fraction is wet in order to dry or further dry the fiber fraction. A further optional inner screen 517 is provided around the hot air inlet 516. A material outlet 514 is connected to the flow chamber 511, shown in a closed position where the fiber fraction 35 is kept in the flow chamber. When it is open, the material outlet 514 allows the purified fiber fraction to be collected from the flow chamber. A means for conveying the purified fiber fraction from the flow chamber 511 through the material outlet 514 is be provided, such as suction fan connected to the material outlet 514. Additionally, or alternatively, the flow in the flow chamber 511 can be used to convey the purified fiber fraction through the material outlet 514 when the latter is opened while maintaining the vortex flow.

[0162] A bladed rotor 513 is provided at a bottom 511b of the flow chamber. Rotation of the bladed rotor 513 causes the fiber fraction to be whirled around in the flow chamber 511, creating a vortex flow in which the fiber fraction is entrained. The flow causes mutual impact of fiber particles as well as friction against the outer screen 512, thereby cleaning the fiber fraction. Centrifugal force forces particles through the outer screen 512, separating the fines fraction from the fiber fraction. The bladed rotor 513 is described in greater detail below. In the embodiment shown, an inlet 515 in the form of a duct is provided below the flow chamber 511 connecting to the flow chamber through the bladed rotor 513. A blowing unit 516a is provided to generate an air flow for conveying the fiber fraction 35 to the flow chamber 511. In addition to the blowing unit 516a or as an alternative thereto, the bladed rotor 513 may have a suction fan 513b mounted proximally to the bottom 511b, so as to pull in the fiber fraction 35. Conceivably, the fiber fraction could be fed to the flow chamber in an alternative manner (not shown), e.g. via a duct provided in the same manner as the material outlet 514, through which material could be added pneumatically or manually. Adding the fiber fraction 35 through the inlet 515 as shown in Figure 2 has the advantage that a heavy fraction 501 which is not entrained in the flow into the flow chamber 511 will collect in the inlet duct 515 at the bottom 513b of the flow chamber and be collected therefrom. An additional heavy fraction (not shown) may be recovered inside the flow chamber 511, as material not entrained in the vortex flow will sediment to the bottom 511b. Prior to said sedimentation, said heavy fraction may be caught in the flow in the flow chamber and forced against the periphery of the flow chamber due to centrifugal force, but remain at the periphery due its specific gravity. Hence, this additional heavy fraction does not re-enter the vortex flow in the flow chamber and will sediment towards the bottom 511b, at least upon termination of the vortex flow. Accordingly, the purified fiber fraction 35 is advantageously collected while maintaining the vortex flow by opening the material outlet 514, thereby collected the material which is entrained in the vortex flow as the purified fiber fraction. The heavy fraction (not shown) which has sedimented in the flow chamber 511 may then be collected. The heavy fraction 501 collected in the inlet 515 at the bottom 511b and the heavy fraction sedimented at the bottom 511b may collectively be considered to be the heavy fraction obtained from the cleaning unit 510. In the event that the heavy fraction is recycled from a downstream cleaning unit to an upstream cleaning unit, the heavy recycled heavy fraction can either be the heavy fraction 501 collected in the inlet, orthe heavy fraction sedimented in the flow chamber, or both collectively. It is presently considered advantageous only to recycle the heavy fraction collected in the inlet. The air flow through the inlet and / or the rotational speed of the bladed rotor may be selected so to provide a predetermined amount of heavy fraction in the inlet 515, which may then be recycled to the upstream cleaning unit.

[0163] Turning now to the bladed rotor 513 of the cleaning unit 510 which is shown in a schematic manner in Figure 2. The function of the bladed rotor 513 is to effect rotational flow in the flow chamber 511 around the central axis 511c, i.e. the vortex flow. This can be achieved by bladed rotor 513 having a first impeller 513a for generating an airflow perpendicular to its rotational axis, i.e. a centrifugal fan impeller. The centrifugal fan type impeller 513a, denoted first impeller, can have radial blades, forward curved blades or backwards curved blades. The first impeller 513a may be in open communication with the flow chamber, i.e. not housed in a housing serving to direct the air flow as is typical in construction of conventional centrifugal fans. The blades of the first impeller 513a may each be provided with a perpendicular portion (not shown) at a distal end of each blade, which perpendicular portions extend perpendicularly to the axis of rotation. The distal end of the blade is the end extending the furthest into the flow chamber 511 seen in an axial direction. Each perpendicular portion extends toward an adjacent blade of the first impeller 513a but with a gap to the adjacent blade. In this way the perpendicular portions collectively form a partially closed surface facing the flow chamber. This may improve the flow in the flow chamber. The perpendicular sections may widen in the radial direction, having their widest point furthers from the central axis 511c. One or more of the perpendicular portions of the blades of the first impeller 513a may be provided with an axially extending baffle. Such baffles may reduce back-flow into the bladed rotor. The bladed rotor 513 may have further a function, namely to pull the fiber fraction 35 into the flow chamber through the inlet 515. To this end, the bladed rotor 513 may be provided with second impeller 513b, which in figure 2 is provided proximally to the bottom 511b of the flow chamber. The second impeller 513b is a suction fan which will pull material through the inlet 515 and into the flow chamber. The first impeller 515a and second impeller 515b, if present, are separated by a partition wall, thereby forming semi-closed impellers at a transition between the impellers.

[0164] Turning now to figure 3a, which shows a core-shell type fiber 607 in a transverse cross-sectional view. The core-shell type fiber 607 has core 603 made from reclaimed turf fiber, which core is encapsulated in shell 606. As the shell 606 defines an exposed surface of the fiber 607, the shell 606 advantageously contains UV-stabilizers and colorants to provide the core-shell fiber with the desired stability and visual properties. This allows for a fiber with the desired properties, which at the same time contains a significant amount of recycled material in the form of the core. Core-shell type fiber is sometimes referred to as core-sheath fiber. In figure 3a the cross-section of the fiber 607 has rhombus shape, but the fiber can have any shape, such as circular, oval, rectangular, nor does the cross-section of the fiber need to be symmetrical. Similarly, the relative volumes and thicknesses of the core and sheath in Fig. 3a are schematic.

[0165] Figure 3b shows the cross-section of a multi-layer film 607' which can be used to provide an alternative bi-component fiber, namely one of the slit-film type. In this embodiment, the multilayer film 607' has a first layer 603' made from reclaimed turf fiber and two cover layers 606', 606" arranged on either side of the first layer. The multilayer film 607' can be cut to form a slit-film type fiber for an artificial turf (not shown). In this way, the cover layers 606', 606" define an exposed surface of the fiber 607', and the cover layers advantageously contain UV-stabilizers and colorants to provide the slit-film fiber with the desired stability and visual properties. In an alternative to the embodiment in figure 3b, the multilayer film only as one cover layer leaving the opposite face of the first layer exposed, which two layers may be sufficient for some applications. The layers 603', 606' 606" are shown in a schematic representation, and do not necessarily have the same thickness or properties.

[0166] Melt filters and extruders for step (e) as well as equipment for fiber extru- sion / spinning and material compounding in steps (e) to (g) are common unit operations in the thermoplastic processing industry and suitable equipment is commercially available. Exemplary suppliers are STC-Spinnzwirn in Chemnitz Germany and Reiffen- hauser Group Germany.

[0167] Suitable cleaning units can be obtained from Maschinen- und Anlagen- bau Schulz GmbH.

[0168] The preceding detailed description was concerned with methods for producing a raw material for use in the manufacturing of artificial turf fiber and to the manufacture of artificial turf fiberfrom said raw material. The initial step of these methods is to separate the fiber fraction from the artificial turf, which fiber fraction is then cleaned to provide the raw material for use in the manufacturing of artificial turf fiber. In the following, details of preferred embodiments of the initial separation step (a) is presented, and these are referred to as processes and systems for processing an artificial turf and for recovering components thereof.

[0169] The process for processing artificial turf will now be described in further details with reference to figure 4 where the sections of the system and process are illustrated in their most general form.

[0170] The method and system for processing artificial turf comprise a feeding and downsizing section 100, an infill separation section 200, the infill separation section comprising two parts, and the method and system comprise a turf and backing separation section. Sections 100, 200 and 300 are connected as further detailed herein. Processing in section 100 may occur independent of sections 200 and 300 and processing in sections 100 and 200 may occur independent of section 100 and 300. The system further comprises an infill after cleaning section 400 following infill separation section 200 and a turf after processing section which is here turf cleaning section 500 following turf and backing separation section 300, which turf and backing section 300 provides the fiber fraction separated from the artificial turf. The turf cleaning section 500 comprises steps (b) and onward of the method for producing a raw material for use in manufacturing artificial turf fiber. However, the processing in the feeding and downsizing section is essential as a feed for the ability of the following sections to provide fractions at the yield and purity sought. The feeding and downsizing section 100, the infill separation section 200 and the turf and backing separation sections are designed such that the process and system can process material in a continuous manner. For this purpose, buffer tanks may be located to allow for feedback of certain fractions from a downstream part of the process to certain parts upstream. Hence the system and process are designed specifically for enabling such continuous processing in order to provide a cost-efficient process that is able to run throughout day and night if material is available. The after-cleaning sections 400 and 500 may be used as part of the continuous separation process or used to increase the yield of various intermediate fractions and run as batch processes.

[0171] Further referring to figure 4, the feeding and downsizing section 100 generally comprises a first downsizing step / unit 101, a drying step / unit 102, a first sieving step / unit 103, a second downsizing step / unit 104, a first optional screening step / unit 105 and an optional third downsizing step 106. An embodiment of the feeding and downsizing section is shown in more details in figure 5.

[0172] The purpose of the feeding and downsizing section is to reduce the size of the artificial turf rolls to a manageable size that can be dried sufficiently to enable the subsequent sections of the process, the separations, without adversely affecting the polymers. This is a critical balance since the large amounts of sand present is capable of absorbing heat that can adversely affect the plastic and rubber. Also, the turf product has components of very different sizes and therefore it can be difficult to dry the various components sufficiently. Hence, the present invention solves the problem of the balancing act between size, type of material, time and temperature needed to be able to provide fractions to the subsequent sections that can be separated as desired.

[0173] The infill separation section 200 in the first part, see figure 6, generally comprises a main screening sieving step / unit 201, a second sieving step / unit 202, a first density separation step / set of density units 203 (203_l to 4), a second density step / set of density units 204 (204_l to 4), a first step / means for separating by specific gravity and size 205 (such as a zig zag sieve), a third sieving step / unit 206 and a third density separation step / set of two density units 207 (207_l and 2).

[0174] The infill separation section 200 in the second part, see figure 7, generally comprises a fourth sieving step / unit 208, a third density step / set of five density units 209 (209_l-5), a fourth density separation step / set of five density units 210 (210_l- 5), the second part may also include a step / means for shaking the rubber fraction 211, such as a hammer mill, and a fifth sieving step / unit 212.

[0175] In its broadest sense the process and system for processing artificial turf comprises the feeding and downsizing section, 100, the infill separation section, 200 and the turf and backing separation section, 300, connected as illustrated in figure 4. This process separates artificial turf into infill, backing and fiber. The infill is further separated into sand and rubber. In some embodiments, the system may also include an infill after cleaning section 400. The fiber fraction obtained from the turf and backing section (300) is fed to turf cleaning section 500, where it is processed according to the method for producing a raw material for use in manufacturing of artificial turf fiber.

[0176] An embodiment of the infill separation section is shown in more de-tails in figures 6 and 7.

[0177] The purpose of part 1 of the infill separation section is to screen and separate stone from rubber, rubber from turf and backing from rubber. The focus is to provide clean rubber material as well as removing stones from the turf fiber material that is recycled to the third downsizing step / unit 106.

[0178] The second part of the infill separation step has two purposes. The first is to separate the rubber from the sand in order to provide clean sand and potentially increase the yield of rubber. The second purpose is to separate the clean rubber into distinct now upcycled sellable fractions, and to eliminate contamination with small particles that are unwanted in the final product, as there is no market for these.

[0179] The turf and backing separation section 300 requires the third down-sizing step 106 to be mandatory and generally comprises, a second step / means for separating by specific gravity and size 301 (such as a zig zag sieve) and a second screening step / unit 302. An embodiment of the turf and backing separation section is shown in more details in figure 9.

[0180] The purpose of the turf and backing separation section 300 is to separate the turf and backing from each other, while removing any fine particles. This will provide fractions of distinct plastic types of different quality that can be upcycled for different purposes.

[0181] The infill after cleaning section 400 generally comprises a seventh sieving step / unit 401 and a fourth density separation step / set of density units 402 (402_l-3). An embodiment of the infill after cleaning section is shown in more details in figure 8.

[0182] The purpose of the infill after cleaning section 400 is to further extract valuable materials out of unfinished products, that would otherwise be non-separable. e.g., Rubber, stone and sand. Thus, the main purpose of this section is to increase the yield of the fractions.

[0183] The processes will now be explained in even further details with reference to figures 5 to 9. It is under-stood that while figures 5 to 9 will be described referring to a process, all descriptions equally apply to the system.

[0184] Figure 5 is a detailed depiction of an embodiment of the feeding and downsizing section 100.

[0185] In a first step, the artificial turf product 1 is fed and downsized in a first downsizing step 101, which in the embodiment shown is a shredder 101, downsizing the turf product to a size of approximately 120 by 120 mm. The downsized turf material 2 is fed to a drying unit 102, which in the embodiment shown is a drum dryer 102. It is contemplated that further already downsized material may also be fed to the drum drier as illustrated as feed stream l_b. A suitable means, such as a material hopper, is suitably used to ensure feeding of material at the volume and speed needed for operating the drying unit 102 in the desired way.

[0186] For the best results the downsized turf material 2 is fed at a speed of 6 - 10 tonnes per hour, preferably 8 tonnes per hour on a dry basis. The length of the drying unit 102 is 8 to 15 meters, preferably 10 to 12 m. When the drying unit is a drum dryer, it is operated at a speed of 1200 to 1500 rpm, preferably 1400 rpm. The temperature at the entry of the drying unit is in a range of 125 to 250°C, preferably 150 to 230°C.

[0187] The moisture content of the dried material 3 after the drying step is at the most 5% w / w, preferably no more than 3% w / w and even more preferred no more than 1% w / w. Having such a low moisture content in all process-es / units downstream from the drying unit 102 is essential for being able to achieve a successful separation, in particular of sand and rubber.

[0188] The dried material 3 is screened through a first sieving unit 103 suitably having openings of 5 to 7 mm, preferably 6 mm, whereby two fractions are provided; a first fraction 4a substantially comprising infill material and a second fraction 4b substantially comprising a mixture of turf and backing material where the length of the largest dimension is at or above 5 to 7 mm, such as at or above 6 mm.

[0189] After this initial separation, the first and second fractions, 4a and 4b, are further processed independently.

[0190] The first fraction, 4a, substantially comprising infill is further processed in the infill separation section 200 which will be explained in more detail with reference to figures 6 and 7. It is contemplated that a silo, for adding additional dry infill to the first fraction 4a before feeding to the infill separation section, is present, as is shown in figure 5. Such material may come from downstream processes.

[0191] The second fraction, 4b, is in the embodiment shown further downsized, in this embodiment in a granulator 104 to give smaller fractions 5 where the size of the largest dimension is at most 50 mm. This step may be preceded by an iron removal step as is shown in figure 5, whereby magnetic metal entrapped in the carpet is removed. The thus further downsized fraction 5 may optionally be subjected to a heavy waste separation step 107 whereby heavy contaminants such as stones, may be removed from the turf and backing material. Such step may be separation by specific gravity and size in a zig zag sieve or air sifter 107. The further downsized fraction 5 is then screened in a first screening unit 105 which is illustrated as a drum screen to provide a small fraction 6a comprising remaining infill and a large fraction 6b comprising turf and backing, which is fed to the turf and backing separation section 300. The small fraction 6a is fed to the infill separation section, optionally mixed with the first fraction 4a as shown in figure 5. The first screening unit 105 is not mandatory, and it is contemplated that the further downsized fraction 5 may be fed directly to the turf and backing separation section or to a third downsizing step in a cutting mill 106 as described below.

[0192] The first screening unit, the drum screen 105, has openings of 4 - 8 mm, preferably 6 mm. As illustrated in the embodiment, the large fraction 6b is fed to a material hopper which can ensure a continuous supply of turf and backing. It is also contemplated, as illustrated, that the large fraction 6b is further downsized in a third downsizing step 106, which in the embodiment shown is a cutting mill, in order to provide a turf and backing fraction 7 of at most 35 mm in the largest dimension. It is contemplated that turf and backing fractions from downstream processes may be recycled and mixed with the large fraction 6b before the cutting mill 106 as illustrated in figure 5, such as from the infill separation section as will be described in relation to figure 6. This recycle however is optional and may be omitted.

[0193] In preferred embodiments the first screening step / unit 105 is omitted. If the optional first screening unit 105 is omitted, it is contemplated that the further downsizing step 104 downsize directly to at most 35 mm in the largest dimension, replacing the third downsizing step 105.

[0194] With reference to figure 6 an embodiment of part one of the infill separation section 200 will now be described in further details.

[0195] In the embodiment illustrated, the first fraction 4a and the small fraction 6a if present, optionally premixed, are in some embodiments as illustrated fed to an infill buffer tank for holding infill in order to enable a continuous feed of streams through the entire process. From the optional infill buffer tank, the infill separation feed fraction 8 is fed to a main sieving unit, 201, having three sieving means 201_a - c. The first sieving means 201_a has perforations wherein the length of the longest dimension is 3 to 6 mm, the first sieving means is preferably a grate type sieving means which is further illustrated in figures 10, lOab and 10b. The second sieving means 201_b has openings of 0.5 to 1.5 mm and the third sieving means has perforations of 0.1 to 6 mm. Four main sieving fractions are provided (9a to 9d) where a lower fraction 9d, a dust fraction, passes through all sieving means 201_a to 201_c and is collected. An upper fraction 9a is retained by the first sieving means 201_a and is further processed for rubber, turf and backing separation starting in separator unit 205. A second intermediate fraction 9c as retained by the third sieving means 201_c is further processed in the second part of the infill separation section as detailed with reference to figure 7. The first intermediate section 9b is retained by the second sieving means 201_b and is further processed for rubber recovery starting at sieving unit 202 but also in the second part of the infill separation section, the rubber polishing part 200a, shown in figure 7.

[0196] The first sieving means 201_a of the main sieving unit 201 is preferably provided with at least one baffle designed to ensure an even distribution of the material to be sieved over the whole are of the sieve. This is important in order to keep the speed of the continuous separation. Each sieving means is preferably provided with 1, 2, 3 or 4 baffles. Each baffle is positioned at an angle a, of 30 to 60°, preferably 40 to 50° even more preferred 45° relative to a horizontal plane of the sieving means framework, see also figure 11 and the associated description.

[0197] The one or more baffles are positioned in the middle section of the sieving means, preferably between % and % of the length of the sieving means. This is important since the natural flow of the infill, due to the slight inclination of the sieving means of around 5 to 10 degrees, will be to moved towards the edges of the sieving means in the middle section of sieving di-rection. Therefore, for optimal flow the baffles are positioned at horizontal planes in the middle 50% of the length of the sieving means. The length of the baffles is typically 3 / 4 of the length of the sieving means and % of the breadth of the sieving means. The form and position of the baffles will be described in more detail in the below, with particular reference to figure 11.

[0198] It is also contemplated that further sieving means or all sieving means of the main sieving unit 201 and further sieving units are provided with such baffles.

[0199] The first intermediate fraction 9b is then fed to a second sieving unit 202 having three sieving means, a first sieving means having openings of 1.2 to 3.5 mm which retains a fraction 10a, a second sieving means having openings of 0.8 to 2.5 mm which retains a fraction 10b, and a third sieving means having openings of 0.5 to 2.0 mm which retains a fraction 10c and through which a fraction lOd passes, thereby providing four fractions 10a to lOd. Each of the four fractions 10a to lOd are fed to a first set of four individual separating means 203_l-4, said means separating by specific gravity using air, to provide four low-density fractions 11a to lid comprising backing material and rubber and a combined high-density fraction 12 comprising additional components, such as stones. Each of the four low density fractions 11a to lid are fed to a second set of four individual separating means 204_l to 4 separating by specific gravity using air, to provide a combined low-density fraction 13 comprising backing material and a combined high-density fraction 14 comprising rubber, the combined high-density fraction 14 comprising rubber is recovered or further processed in a rubber polishing unit 200a, which will be described with reference to figure 7.

[0200] The combined low-density fraction 13 comprising backing material is separated by specific gravity and size by providing an airflow directed up-wards in a separator 205 configured to cause a swirling motion, in the embodiment shown it is a zig zag air sifter 205. Here the lighter material 15 is entrained upwards in the air flow and the heavy material is allowed to fall downwards; the lighter fraction 15 comprises rubber, backing and turf material, and the heavy fraction 16 comprises additional material, such as stones and may be combined with high density fraction 12 as illustrated. The stones may either be sold as they are. If, however the stone fraction, 12+16, comprises rubber components, the fractions 12 and 16 will be fed to the infill after processing section 400, described with reference to figure 8.

[0201] The lighter fraction, 15, comprising rubber, backing and turf material is sieved in a third sieving unit, 206, having two sieving means, a first sieving means having openings of 2 to 5 mm and a second sieving means having openings of 0.8 to 3 mm, thereby providing three fractions; an upper fraction 17 comprising grass fiber retained by the sieving means, an intermediate fraction 18 comprising backing retained by the second sieving means and a lowerfraction 19 comprising rubber passing through the second sieving means. In the embodiment shown the upper fraction 17 is returned to the cutting mill 106 and further processed in the turf and backing separation unit 300 which increases the yield of turf fiber. Each of the intermediate fraction 18 and the lower fraction 19 are fed to a third set of two individual separating means 207_l and 207_2, said means separating by specific gravity using air, to provide a second combined low-density fraction 20 comprising turf material and a third combined high-density fraction comprising a rubber backing mix.

[0202] With reference to figure 7 an embodiment of part two of the infill separation section 200 will now be described in further details. In part two, the second intermediate fraction 9c obtained from sieving in the main sieving unit 201 is further processed for sand and rubber separation. The second intermediate fraction 9c is separated in a fourth sieving unit 208 having four sieving means said sieving means having openings in the range of 1.2 or 0.8 to 0.2 mm where the size of the openings descends from top to bottom.

[0203] The specific choice of openings of the various sieving means in this and the other sieving units may be chosen using the method described in WO2021 / 048214 to the same applicant for optimal separation.

[0204] The sieving in sieving unit 208 provides five fractions 21a to 21e in descending size order. Each of the five fractions 21a to 21e are fed to a fourth set of five individual separating means 209_l to 5, said means separating by specific gravity using air, to provide a second set of low-density fractions 22a to 22e comprising rubber, sand and / or fine fiber particles and a fourth combined high-density fraction 23 comprising sand. The sand is collected and reused as appropriate. Afterthe first separation of sand from the rubber and sand fraction in separating means 209_l to 5, each of the five low density fractions 22a to 22e comprising rubber, sand and / or fine fiber particles are fed to a fifth set of five individual separating means 210_l to 5, said means separating by specific gravity using air, to provide a second low density fraction and a second high density fraction.

[0205] According to the method the flow is directed such that when 30% vol / vol or more of the low-density fractions 22a to 22e is rubber, the density separation results in a third combined light fraction 24 comprising rubber which is sent to the rubber polishing unit 200a for further sorting optionally premixed with the rubber fraction 14 which is obtained from the first part of the infill separation section 200 as illustrated in the embodiment.

[0206] A fourth combined heavy fraction 25 comprising a mix of sand and rubber is also provided. This second heavy fraction 25 is recycled to the fourth sieving unit 208 as part of the particle flow.

[0207] On the other hand, when 30% vol / vol or less of the second set of low-density fractions 22a to 22e is rubber, a second heavy fraction 26 comprising sand is provided. This sand is collected and reused as appropriate suitably mixed with the fifth combined high-density fraction 23 comprising sand. In addition, a fourth combined light fraction, 27, comprising a mix of rubber and sand is provided. This mix of rubber and sand may be further processed, for example in the infill after cleaning unit, held in a buffer tank or discarded as appropriate to ensure the continuous flow of material.

[0208] The diversion of steams to the appropriate conveying means is achieved by having diverting means such as valves positioned at the outlets of the second set of density separation means. Suitable valves are standard switch valves either mechani- ca I ly / electrica I ly or manually operated.

[0209] In the rubber polishing part 200a of the infill separation section, rubber is separated in distinct sizes. The rubber fractions, 14 and 24, are in the embodiment shown fed to a unit 211 capable of beating fine particles loose from the rubber particles, in the embodiment shown a hammer mill 211. The effect of this step is to beat the fine particles loose of the rubber particles. Given the moisture content of the material the fine particles will be released from the rubber resulting in a beaten mixture 28 of rubber and floating fine sand particles. The beating step may be preceded by an iron removal unit indicated as magnetic drum. It is also preferable that an intermediate buffer tank 213 is positioned before the hammer mill 211 to cater for the continuous processing of material. Hence, the buffer tank, when present, is in fluid communication with the unit capable of beating fine particles loose from the rubber particles

[0210] 211, here a hammer mill, and the buffer tank receives rubber fractions obtained throughout the process, such as the rubber fractions 14 and 24 obtained up-stream.

[0211] It is contemplated that both the buffer tank and unit capable of beating fine particles loose from the rubber particles are omitted. This is preferred for a simpler separation. In this embodiment the rubber feed is fed directly to a fifth sieving unit

[0212] 212.

[0213] Thus, the optionally beaten rubber and fine sand particles mixture 28 is then fed to a fifth sieving unit 212 having three sieving means, a first sieving means having openings of 1.5 to 4 mm which retains rubber fraction 29a, a second sieving means having openings of 0.7 to 1.5 mm which retains rubber fraction 29b, and a third sieving means having openings of 0.2 to 0.7 mm which retains rubber fraction 29c and through which a dust fraction 30 passed, thereby providing three distinct rubber fractions 29a to 29c which are collected and reused as appropriate.

[0214] When one or more of the fractions 12 and 16 comprise rubber, the fractions, optionally combined, are further treated for recovering stone and rubber for further end use. This processing takes place in the infill after processing section 400 shown in figure 8. This section is not always part of the continuous flow but can be included if and when there is a need for further separation of stone and rubber. In down time, the section may be used to separate fractions in various so-called waste fractions generated throughout the process, in order to increase the yield, thus minimizing the total waste of the process.

[0215] In the embodiment shown in figure 8, the combined high-density fraction 12 and the heavy fraction 16 both obtained from the first part of the infill separation section 200 show in figure 6, are fed to a sixth sieving unit 401 having two sieving means, a first sieving means having openings of 0.4 to 3 mm and a second sieving means having openings of 0.2 to 2 mm, thereby providing three fractions 31a to 31c; an upper fraction 31a retained by the first sieving means, an intermediate fraction 31b retained by the second sieving means and a lower fraction 31c passing through the . Each of the three fractions 31a to 31c are fed to a sixth set of three individual separating means 402_l to 402_3, said means separating by specific gravity using air, to provide a fifth combined low-density fraction 32 comprising rubber and a sixth combined high-density fraction 33 comprising stone and sand. The rubber fraction 32 is recovered or further processed in the rubber polishing section 200a, see figure 7.

[0216] Turning now to figure 9 where the turf and backing is separated in the turf and backing separation section 300. The separation is achieved by feeding the large fraction 7 obtained in the feeding and downsizing section in figure 4, downsized further to at most 35 mm in the largest dimension, to a second separator, where it is separated by specific gravity and size by providing an airflow directed upwards in a second separator 301 configured to cause a swirling motion whereby a second lighter fraction 33 is entrained upwards in the air flow and a second heavy fraction is allowed to fall downwards; where the second lighter fraction 33 substantially comprises grass fiber components, and the second heavy fraction 34 substantially comprises a mixture of backing material and grass fiber component. Then the grass fiber, which is the plastic of highest upcycle quality is further enriched by feeding the second lighter fraction 33 substantially comprising grass fiber components to a second screening unit 302, preferably a drum screen, having openings of 1 to 3 mm in the shortest dimension, to provide a final small fraction comprising 36 backing and grass fiber waste and a final large fraction 35 comprising turf. The final large fraction 35 comprising turf is recovered and is the fiber fraction separated from artificial turf, which may then be further cleaned in the turf cleaning section 500, where it is further processed into a raw material for producing artificial turf fiber. In an alternative embodiment (not shown), the second screening unit 302 is omitted, whereby the second lighter fraction 33 is fed directly to the turf cleaning section 500. In a further variation (not shown), the screening unit 302 is moved downstream into the turf cleaning section 500 downstream of the flow chamber in step (b). In this variation the second lighter fraction 33 is recovered as the fiber fraction and then cleaned in the flow chamber of step (b) to provide the purified fiber fraction, which purified fiber fraction is then fed to screening unit 302 and the final large fraction obtained from the screening units is filtrated in step (c).

[0217] The openings of the second screening unit 302 are in preferred embodiments elongated. This will further enrich and purify the larger grass fiber fractions.

[0218] In all the descriptions above where a separator is configured to cause a swirling motion whereby the lighter fraction is entrained upwards in the air flow and the heavy fraction is allowed to fall downwards it is preferred that the unit is a cyclone separator or a zig-zag air sifter, and wherein when the separation is performed in a zig-zag air sifter the air is provided at a frequency of 18 to 27 Hz, more preferred 20 to 25 Hz. In a zig-zag air sifter, material being separated is introduced into a channel which channel follows a zig-zag path defined by walls of the channel. The heavy fraction falling down the channel and lighter fraction entrained upwards in the channel impact the walls of the channels, which aids in the separation of the material, with the driving force of the separation beings based on the 2ndlaw of Newton.

[0219] Two embodiments of the grate like sieving means 700 are illustrated further in figure 10 and enhanced views figure 10a and 10b. Referring first to figures 10 and 10a, it is seen that a grating slot is formed between two sections at each perforation 701 of the grate like sieving means 700, in that a lower section of the perforation in figure 7a protrudes downwards relative to a general plane defined by the grate like sieving means and an upward section protAN142669rudes upwards to the general plane such that the grating slot formed at each perforation 701 is symmetrical around an axis lying in the general plane of the grate like sieving means 700. In the other embodiment, shown in figure 10b, the upward section is formed in substantially the same manner as in the embodiment of figure 10a; however, the lower section extends substantially in the general plane of the grate like sieving means 700.

[0220] The positioning of the grate like sieving means 700 within the system is indicated in Fig. 6, in which one grate like sieving means 700 of a stack of sieving means 201_a to 201_c is shown in the main sieving unit 201. The slight inclination of the grate like sieving means 700 is also indicated in Fig. 6. The configuration of the individual sieving means of the various sieving units of the system may be selected as described.

[0221] While the sieving means have been referred to as grate like sieving means 700, having for instance features as described in the above and shown in figures 10, 10a and 10b, other configurations of the sieving means are conceivable.

[0222] One example of such a general sieving means 800 is shown in figure 11, in which also the form and position of the above-mentioned baffles, here indicated as three baffles 801, are shown. In the embodiment shown, the angle a formed between each baffle 801 and a respective line in the horizontal plane of the sieving means 800 is around 45°.

[0223] Also indicated in figure 11 is the formation of a stack of sieving means, shown in dashed lines below the sieving means 800. As in the embodiments described in the above, the sieving means 800 may be positioned with a slight inclination in the flow direction. The inclination may vary between the sieving means of the various the sieving units, just as the inclination may be selected individually for the sieving means of a stack in a sieving unit.

[0224] In a further aspect a system for separating synthetic or artificial turf product is provided, the system is configured as detailed in the process for processing an artificial turf and for recovering components thereof above. In its most general sense, the system is for processing moist synthetic turf product in a continuous manner to provide individual components of synthetic turf product, said system comprising a feeding and a downsizing section 100 an infill separation section 200 and a turf and backing separation section 300, said feeding and downsizing section 100 is in fluid communication with the infill separation section 200 and the turf and back-ing separation section 300, wherein the feeding and downsizing section 100 comprises an inlet for moist artificial turf product 1 which is connected to downsizing unit 101 such as a shredder, the outlet of the downsizing unit 101 is connected to a drying unit 102, the outlet of the drying unit is connected to a first sieving unit 103 which has two outlets, a first outlet which is connected to the infill separation section 200 and a second outlet which is connected to a second downsizing unit 104 capable of downsizing components to at most 50 mm in the largest dimension, the outlet of the second downsizing unit 104 is connected to a first screening unit 105, such as a drum screen having openings of 4 to 8 mm, preferably, 6 mm, said first screening unit has two outlets, a first outlet a re- tentate and a second outlet a filtrate, where the first outlet is connected to a material hopper continuously supplying the retentate fraction to a third downsizing unit 106, preferably a cutting mill, the outlet of the third downsizing unit 106 is connected to the turf and backing separation section 300 and the second outlet the filtrate is connected to the infill separation section 200.

[0225] All embodiments and variations described with reference to the process processing an artificial turf and for recovering components thereof equally apply to the system and vice versa.

[0226] Key to the process and system is the order of separation steps and in further embodiments the parameters of the separation steps. Different orders of separation, combination of units and parameters resulted in an inferior end product, i.e., fractions comprising substantial amounts of other constituents and / or contaminants, which makes the fraction less usable as a high grade recycling product.

[0227] Hence, the process processing an artificial turf and for recovering components thereof also provides recycled components of an artificial turf product and more specifically recycled sand, recycled rubber, recycled grass fiber components and recycled backing material obtained or obtainable by the process according to the invention.

[0228] The components are characterized by a purity of more than 95% (w / w) of the fraction. Even more preferred more than 96% (w / w), more than 97% (w / w), more than 98% (w / w), more than 99% (w / w), or approximately 100% of the fraction.

[0229] Turf products often comprise components of different colors, hence the resulting fractions may be evaluated visually for assessment of purity. Purity of e.g. rubber and grass fiber may be evaluated using standard tests in the art such as D5603 and E1131-08 from ASTM International for testing the purity of the rubber and plastics. In addition, the purity may be determined by manually or mechanically separating portions of the components and determine the weight-% and extrapolate.

[0230] The products or fractions obtained by the process for processing an artificial turf and for recovering components thereof are useful as starting materials in a number of industries such as but not limited to rubber molding industry, construction industry, the synthetic turf industry and the plastic extrusion industry.

[0231] The separator operating by separating by specific gravity and size by providing an airflow directed upwards configured to cause a swirling motion may be any suitable means in the art such as a cyclone separator, e.g. Hovex De-Sanding Cyclone from Gea AG, a zigzag air sifter, e.g. ZZS Air sifter from Trenn- und Sortiertechnik GmbH, or similar separating means

[0232] The zig zag sieve may be an air sifter type ZZS180 / 800 obtainable from Trenn- und Sortiertechnik GmbH in which the swirling motion is caused by injecting an air flow, a, into zig zag channels within the sorting channel. The air is provided at a frequency of 25 Hz. Other suppliers of zig zag sieves are available such as Hamos GmbH, Penzberg, Germany. In the test below, the zig zag sieve / air sifter separator was a ZZS air sifter obtainable from Trenn- und Sortiertechnik GmbH in which the swirling motion is caused by zig zag channels within the sorting channel, hence the name.

[0233] Suitable separation means usable for separating by specific gravity (density separation) are obtainable from Trenn- und Sortiertechnik GmbH or Guidetti S.r.l., Renazzo, Italy.

[0234] Suitable sieving units are TTS Separating Tables No. TTSS900 / 1000 / 1 and TTS600 / 1000 / 1 obtainable from Trenn- und Sortiertechnik GmbH.

[0235] A suitable downsizing means is a cutting mill of the type H500 / R2-2000, available from Hosokawa Alpine AG, but may be obtained from other suppliers such as Amis Maschinen Vertriebs GmbH, Zuzenhausen, Germany.

[0236] Suitable shredders and drum screens are components generally known in the art, the choice of specific units are within the skill of the art. The specific shredder used for the tests was a model H500 / R2-2000 obtainable from Erdwich Zerk- leinerungs-Systeme GmbH. It is also contemplated that magnets are inserted at various point of the process for removing magnetic components or contaminants, and preferably, the magnets are positioned before the various cutting steps in order to avoid destruction of the blades. It is to be understood that the process and system for processing an artificial turf and for recovering components thereof also includes necessary means for transporting, feeding, holding, directing, opening and closing fractions etc. some of these but not all are illustrated in the drawings but the invention should not be limited to these specific units or locations unless otherwise stated. These are standard means known in the art.

[0237] The method and system for processing an artificial turf and for recovering components thereof can process around 8 tonnes / hour to 192 tonnes / hour, 24 hours a day.

[0238] Example I

[0239] In this example a fiber fraction separated from artificial turf was cleaned according to step (b) of the invention. The starting material was a PE and PP fiber fraction obtained from the applicant's turf separation facility. The fiber fraction was obtained by the method described in EP2862688. The fiber fraction was then cleaned in a cleaning unit as shown schematically in Fig. 2. A first and second cleaning unit was employed with a recycle of the second heavy fraction. Two tests were run using screen size 2 and 3 mm outer screens respectively. Both the first and second cleaning unit had the same screen size. The collected fractions were weighed and the results are shown in Table I and Table II. The fines fractions contained about 50 w / w% ash (sand and other inorganic matter) and about 30 w / w% PET. The cleaning step removed substantially all PET from the fiber fraction, although larger strands remained. The larger PET strands will be removed in the melt filtration step.

[0240] Table I

[0241] Table II Example II

[0242] In this example a fiber fraction was cleaned and used to make a core-shell fiber. The starting material was a PE and PP fiber fraction obtained from the applicant's turf separation facility. The fiber fraction was cleaned according to step b) using two cleaning units with a recycle of the second heavy fraction as described herein. Both cleaning units had a 2.5 mm screen.

[0243] The purified fraction thus obtained was then filtered in melt filters using a laser filter with a screen size of 130 pm and two downstream screen filters having a screen size of 100 pm. The feed side pressure during the filtration was maintained below 80 bar(a) and the pressure drop was controlled to a set point of 30 bar. The resulting filtrate was granulated by underwater pelleting.

[0244] A 2000 dtex core-shell fiber was extruded using the obtained granulate as the core material. The core was 98 % granulate and 2 % antioxidant and formed 50 % of the volume of the core-shell fiber. The remaining 50 % of the volume was the shell material which was made of commercially available virgin polymer used in conventional turf fiber production. The fiber was made on manufacturing system with two extruders, a core-shell die-head and a three oven system with direct winding. The standard protocol of the manufacturing system was used.

[0245] The produced fiber was very smooth, without visible gel formation nor any big black spots indicative of rubber particles.

Claims

C L A I M S1. A method for producing a raw material (506) for use in the manufacturing of artificial turf fiber, which raw material (506) comprises reclaimed artificial turf fiber, preferably polyolefin turf fiber, said method comprising the following steps:(a) separating a fiber fraction (33, 35) from an artificial turf (1),(b) cleaning the fiber fraction (33, 35) by whirling the fiber fraction (2) inside a flow chamber (511) to form a vortex flow while keeping a material outlet (514) of the flow chamber closed, which flow chamber has an outer screen (512) arranged along at least a portion of a periphery of the flow chamber (511), the material outlet(514) being connected to the flow chamber (511, to provide a heavy fraction (501) at a bottom (511b) of the flow chamber, a purified fiber fraction (503) inside the flow chamber, and a fines fraction (502) on a side (512s) of the screen (512) which side faces away from the flow chamber (511),(c) filtering the purified fiber fraction (503) in a melt filter to provide a filtrate (505), and(d) recovering the filtrate (505) as the raw material (506) for producing artificial turf fibers, said raw material is optionally in granular form.

2. The method according to claim 1, wherein step (b) is implemented in a cleaning unit (510) comprising the flow chamber (511) with the outer screen (512), a bladed rotor (513) arranged at the bottom (211b) of the flow chamber, and an inlet(515) connected to the flow chamber (511), and step (b) comprises the steps of(bl) feeding the fiber fraction (33, 35) to the flow chamber (511) through the inlet (515),(b2) whirling the fiber fraction (33, 35) in the flow chamber (511) by way of rotation of the bladed rotor (513) while keeping the material outlet closed (514),(b3) collecting the fines fraction (501) from the side (512s) of the screen (512) faces away from the flow chamber (511),(b4) collecting the heavy fraction (502) at the bottom (511b) of theflow chamber, and(b5) opening the material outlet (514) to collect the purified fiber fraction (503).

3. The method according to claim 1 or 2, wherein the outer screen (512) has a screen size in the range of 0.5 to 10 mm, preferably 0.55 to 6 mm or 1 to 5 mm, more preferably 2 to 3 mm.

4. The method according to claim 2 and optionally claim 3, wherein the bladed rotor (513) of the cleaning unit (510) has a rotational speed in the range of 10 till 1500 RPM.

5. The method according to any one of the preceding claims, wherein step (b) further comprises adding an air flow to the flow chamber, preferably at a rate in the range 10 to 10000 Nm3 / hr.

6. The method according to any one of the preceding claims, comprising further cleaning the purified fiber fraction (503) by repeating step (b) in a second flow chamber to provide a second heavy fraction, a further purified fiber fraction, and a second fines fraction, wherein step (c) comprises filtrating the further purified fiber fraction to provide the filtrate (505), optionally wherein the further cleaning of the purified fiber fraction (505) is implemented in a second cleaning unit, which second cleaning unit is of the same type as the cleaning unit (510).

7. The method according to claim 6, wherein at least a portion of the second heavy fraction is recycled to the step of cleaning the fiber fraction.

8. The method according to claim 7, wherein step (b) is repeated in the second cleaning unit wherein one or more of a rotational speed of a bladed rotor of thesecond cleaning unit, and an air flow to the second flow chamber is selected to provide a predetermined amount of the second heavy fraction, such as a second heavy fraction which constitutes 1 to 50 w / w % of the purified fiber fraction (35).

9. The method according to any one of the preceding claims, wherein step (c) comprises filtrating in a laser filter and / or a screen melt filter, preferably a laser filter and a screen melt filter and more preferably filtration step (c) comprises two filtration steps.

10. The method according to any one of the preceding claims, wherein the melt filter comprises a filter having a size in the range 5 pm to 450 pm, preferably 10 to 300 pm, more preferably 50 to 200 pm.

11. The method according to any one of the preceding claims, wherein step (c) comprises controlling a pressure drop in the melt filter to a pressure set-point, which pressure set-point is constant, or controlling the pressure drop in the melt filter to be at or below an upper pressure threshold.

12. The method according to claim 11, wherein the pressure set-point is 30 bar or less or the upper pressure threshold is 30 bar.

13. The method according to any one of the preceding claims, wherein step (c) further comprises controlling a pressure on an inlet side of the melt filter to be 80 bar(a) or less.

14. The method according to any one of the preceding claims, wherein step (a) comprises separating the artificial turf (1) into the fiber fraction (33, 35), into an infill portion (23, 29a-c) and a backing material portion (34).

15. The method according to claim 14, wherein step (a) comprisesa feeding and a downsizing section (100) an infill separation section (200) and a turf and backing separation section (300), wherein said feeding and downsizing section (100) is in fluid communication with the infill separation section (200) and the turf and backing separation section (300), and wherein the feeding and downsizing section (100) comprises the following steps:(al) feeding a moist artificial turf product (1) to the feeding and downsizing section (100),(a2) downsizing the moist artificial synthetic turf product (1) into a downsized turf material (2), preferably to no more than 120 by 120 mm, and feeding the downsized turf material to a drying unit (102),(a3) drying the downsized turf material (2) in the drying unit (102), for example in a drum drier, to a moisture content of no more than 5% w / w, preferably no more than 3% w / w, most preferably no more than 1% w / w, to a dried material (3)(a4) separating the dried material (3) by screening in a first sieving unit (103) into at least a first fraction (4a) substantially comprising an infill material which is fed to the infill separation section (200) and a second fraction (4b) substantially comprising turf fiber and backing components,(a5) downsizing the second fraction (4b) substantially comprising turf fiber and backing components to at most 50 mm in the largest dimension in a downsizing unit (104) and optionally feeding the further downsized fraction (5) to a first screening unit (105), such as a drum screen having openings of 4 to 8 mm, preferably, 6 mm, to provide a small fraction (6a) and a large fraction (6b),(a 6) feeding the further downsized fraction (5) or if present, the large fraction (6b), obtained in step (a5) to a material hopper continuously supplying the fraction, optionally downsized further to at most 35 mm in the largest dimension, to the turf and backing separation section (300); and(a7) further processing the first fraction (4a) obtained in step (a4) andthe small fraction (6a), if present, obtained in step (a5) in the infill separation section (200), wherein the turf and backing separation section (300) comprises the steps of(a8) separating the downsized fraction (5) or large fraction (7) obtained in step (a5) downsized further to at most 35 mm in the largest dimension, by specific gravity and size by providing an airflow directed upwards in a second separator (301) configured to cause a swirling motion whereby a second lighter fraction (33) is entrained upwards in the air flow and a second heavy fraction (34) is allowed to fall downwards; where the second lighter fraction (33) substantially comprises turf fiber components, and second heavy fraction substantially comprises a mixture of backing material and turf fiber component, and a9) recovering the second lighter fraction (33) as the fiber fraction (35).

16. A method for producing a fiber (607), preferably a turf fiber for an artificial turf, from reclaimed artificial turf fiber, comprising the steps of(e) providing a fiber raw material (603) comprising reclaimed artificial turf fiber (506), optionally further comprising virgin polymer (601) and / or one or more additives (602) selected from antioxidants, and processing aids, and(g) extruding the fiber raw material (603) to form the fiber (607) or to form a film (607') which film is then processed to form a slit-film fiber.

17. A method according to claim 16, wherein the fiber is a bicomponent fiber.

18. The method according to claim 17, wherein the fiber (607) is a core-shell type fiber, further comprising the step of(f) providing a shell material (606), which shell material comprises polymermaterial (604) and additives (605), wherein the polymer material (604) is selected from virgin polymer, Post-Industrial polymer material, post-consumer polymer material or mixtures thereof, and the additives (605) are selected from one or more of colorants, UV-stabilizers, and anti-oxidants, and wherein step (g) comprises co-extruding the fiber raw material (603) and the shell material (606) to form the core-shell type fiber (607), the fiber raw material forming a core of the core-shell type fiber (607) and the shell material forming a shell of the core-shell type fiber.

19. The method according to claim 17, wherein the fiber (607) is a slit-film fiber, further comprising the step of(f') providing a cover material (606), which cover material comprises polymer material (604) and additives (605), wherein the polymer material (604) is selected from virgin polymer, Post-Industrial polymer material, post-consumer polymer material or mixtures thereof, and the additives (605) are selected from one or more of colorants, UV-stabilizers, and anti-oxidants, and wherein step (g) comprises co-extruding the fiber raw material (603) and the cover material (606) to form a multi-layer film (607'), the fiber raw material forming a first layer (603') and the cover material forming a cover layer (606') of the multilayer film (607'), which multilayer film (607') is then processed into the slit-film fiber.

20. The method according to any one of claims 16 to 19, wherein the reclaimed artificial turf fiber is obtained using mechanical separation of artificial turf.

21. The method according to claim 20, wherein the mechanical separation is a method according to any one of claims 1 to 15.

22. A method for producing a fiber according any one of claims 16 to 21, wherein reclaimed artificial turf fiber constitutes 25 w / w% or more of a total polymercontent of the fiber, preferably 35 w / w% or more, more preferably 50 w / w% or more, most preferably 70 w / w% or more of the total polymer content, wherein the total polymer content is the mass sum of reclaimed artificial turf fiber, virgin polymer, and Post-Industrial polymer material in the fiber.

23. A fiber comprising reclaimed artificial turf fiber, preferably wherein the fiber is a turf fiber for an artificial turf.

24. The fiber according to claim 23 obtained by a method according to any one of claims 16 to 21.

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