ARTIFICIAL TURF WITH TEXTURIZED AND NON-TEXTURIZED FIBERS

Abstract

In one embodiment, a method of manufacturing an artificial turf includes manufacturing a hot-texturized yarn by texturizing a first yarn at a first temperature; manufacturing a low-temperature-texturized yarn by texturizing a second yarn at a second temperature, the second temperature being lower than the first temperature; integrating the hot-texturized yarn, the low-temperature-texturized yarn and a non-texturized yarn into a carrier; cutting the integrated yarns to form low-temperature-texturized fibers, hot-texturized fibers and non-texturized fibers extending from the carrier; exposing the carrier with the texturized and non-texturized fibers to a third temperature to cause the hot-texturized fibers to shrink and the low-temperature-texturized fibers to expand; after exposition to the third temperature, providing the carrier with the texturized and non-texturized fibers as the artificial turf.

Claims

1. A method of manufacturing an artificial turf, the method comprising: manufacturing a hot-texturized yarn by texturizing a first yarn at a first temperature; manufacturing a low-temperature-texturized yarn by texturizing a second yarn at a second temperature, the second temperature being lower than the first temperature; integrating the hot-texturized yarn, the low-temperature-texturized yarn and a non-texturized yarn into a carrier; cutting the integrated yarns to form low-temperature-texturized fibers, hot-texturized fibers and non-texturized fibers extending from the carrier; exposing the carrier with the texturized and non-texturized fibers to a third temperature to cause the hot-texturized fibers to shrink and the low-temperature-texturized fibers to expand; after exposition to the third temperature, providing the carrier with the texturized and non-texturized fibers as the artificial turf.

2. The method of claim 1, wherein the exposure to the third temperature causes: the low-temperature-texturized fibers to expand to a length L2 which is similar to the length L3 of the non-texturized fibers, wherein in particular L2 is a length in the range of [L315%L3L3+15%L3], in particular a length in the range of [L310%L3L3+10%L3], and in particular a length in the range of [L35%L3L3+5%L3]; and/or the low-temperature-texturized fibers to expand to a length L2 which is shorter than the length L3 of the non-texturized fibers, wherein in particular L2 is a length according to: L2<L3 and L2>L315%L3, in particular according to L2<L3 and L2>L310%L3 and in particular according to L2<L3 and L2>L35%L3; and wherein the length L2 is longer than the length L1 of the hot-texturized fibers, wherein the lengths L1, L2 and L3 are fiber lengths after exposition to the third temperature.

3. The method of claim 1, wherein the texturizing of the first yarn comprises: injecting a fluid under pressure into a gas-dynamic yarn texturing apparatus, injecting the first yarn into the texturing apparatus via a yarn inlet port of the texturing apparatus, and subjecting, inside a gas-dynamic yarn texturing expansion chamber of the apparatus, the first yarn at the first temperature to a turbulent flow of the fluid so that the texturing of the first yarn occurs; and/or wherein the texturizing of the second yarn comprises: injecting a fluid under pressure into a gas-dynamic yarn texturing apparatus, injecting the second yarn into the texturing apparatus via a yarn inlet port of the texturing apparatus, and subjecting, inside a gas-dynamic yarn texturing expansion chamber of the apparatus, the second yarn at the second temperature to a turbulent flow of the fluid so that the texturing of the second yarn occurs.

4. The method of claim 3, wherein the fluid used for texturizing the second yarn is a hot gas and the pressure of the fluid is 3.0 to 4.0 bar, in particular 3.3 to 3.7 bar, in particular 3.4 to 3.6 bar; and/or wherein the fluid used for texturizing the first yarn is a hot gas and the pressure of the fluid is at least 4.5 bar, in particular 5.0 to 8.0 bar.

5. The method of claim 1, wherein the first temperature is at least 10 C. hotter than the second temperature, in particular at least 20 C. hotter than the second temperature; and/or wherein the third temperature is at least 10 C. hotter than the second temperature, in particular at least 20 C. hotter than the second temperature.

6. The method of claim 1, wherein the first temperature is a temperature of at least 70 C., in particular between 70 C. and 150 C., more particularly between 70 C. and 95 C.; and/or wherein the second temperature is a temperature between 50 C. and 74 C., in particular between 55 C. and 65 C.; and wherein the third temperature is a temperature above 70 C., in particular a temperature between 70 C. and 130 C., in particular a temperature between 80 C. and 90 C.

7. The method of claim 1, further comprising: after the cutting, applying a liquid mass onto a backside of the carrier, the backside being opposed to the side from which the artificial turf fibers extend; transporting the carrier with the applied liquid mass into an oven, wherein the exposing of the carrier with the texturized and non-texturized fibers to the third temperature comprises heating the carrier and the fibers and the applied mass in the oven to the third temperature to allow the mass to harden and to form a backing layer.

8. The method of claim 1, wherein the low-temperature-texturized yarn, the hot-texturized yarn and/or the non-texturized yarn respectively are made of a first and a second polymer and a compatibilizer, wherein the first and second polymers are immiscible.

9. A method of manufacturing an artificial turf, the method comprising: manufacturing a first texturized yarn by texturizing a first yarn at a first temperature; manufacturing a second texturized yarn by texturizing a second yarn at a second temperature, the second temperature being lower than the first temperature; integrating the first texturized yarn, the second texturized yarn and a non-texturized yarn into a carrier; cutting the integrated yarns to form first texturized fibers, second texturized fibers and non-texturized fibers extending from the carrier; exposing the carrier with the first and second texturized and the non-texturized fibers to a third temperature to cause the first texturized fibers to shrink and the second texturized fibers to expand; after exposition to the third temperature, providing the carrier with the texturized and non-texturized fibers as the artificial turf.

10. An artificial turf comprising: a carrier; artificial turf fibers integrated into and extending from the carrier, the artificial turf fibers comprising: first texturized fibers having a first length; second texturized fibers having a second length; non-texturized fibers having a third length; wherein the third length is longer than the first length.

11. The artificial turf of claim 10, wherein the second length is similar to the length (L3) of the non-texturized fibers, wherein in particular L2 is a length in the range of [L315%L3L3+15%L3], in particular a length in the range of [L310%L3L3+10%L3], and in particular a length in the range of [L35%L3-L3+5%L3]; and/or wherein the first length is less than 70% of the third length, in particular less than 60% of the third length.

12. The artificial turf of claim 10, wherein the artificial turf is an infill-less artificial turf.

13. The artificial turf of claim 10, further comprising a backing at least on the side of the carrier opposed to the side to which the artificial turf fibers extend, the backing fixing the artificial turf fibers in the carrier.

14. The artificial turf of claim 10, wherein the second texturized fibers have a higher thickness than the non-texturized fibers, wherein the artificial turf is in particular an artificial turf for sports; or wherein the second texturized fibers have a lower thickness than the non-texturized fibers, wherein the artificial turf is in particular an artificial turf for landscaping.

15. The artificial turf of claim 10, wherein the length (L3) of the non-texturized fibers is 4.0 to 8.0 cm, in particular 5.0 to 7.0 cm; and wherein the length (L2) of the second texturized fibers is 90% to 99.5% of the length of the non-texturized fibers, in particular 97% to 99.5% of the length of the non-texturized fibers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0112] In the following, examples are described in greater detail making reference to the drawings in which:

[0113] FIG. 1 is a flow chart of a method of manufacturing artificial turf;

[0114] FIG. 2 is a diagram illustrating the three types of fibers comprised in the turf;

[0115] FIGS. 3A and 3B are illustrations of the effect of the third temperature on the length of the different fibers;

[0116] FIGS. 4A, 4B and 4C are illustrations of artificial turfs with and without a secondary backing;

[0117] FIG. 5 is a block diagram of a manufacturing line for manufacturing artificial turf yarn;

[0118] FIG. 6 is an illustration of a cross-section of a gas-dynamic texturization apparatus;

[0119] FIG. 7 is an illustration of a three-phase polymer blend;

[0120] FIG. 8 is an illustration of the extrusion of a monofilament;

[0121] FIG. 9 is a cross-section of a segment the monofilament yarn after it is extruded and stretched;

[0122] FIG. 10 shows a plot illustrating the shrinkage effect of various temperatures on now-temperature-texturized yarn.

DETAILED DESCRIPTION

[0123] In the following, similar elements are denoted by the same reference numerals.

[0124] FIG. 1 shows is a flow chart of a method of manufacturing artificial turf.

[0125] In a first step 222, a hot-texturized yarn is manufactured. The manufacturing comprises a step of texturizing a first yarn at a first temperature, e.g., 80 C. The texturizing can be performed using a gas-dynamic texturizing apparatus, in particular a gas-dynamic texturizing apparatus employing heated compressed gas as illustrated, for example, in FIG. 6. The manufacturing process may comprise a plurality of additional processing steps such as extruding a polymer mass to form the first yarn and quenching the first yarn, e.g. in a water bath, and optionally stretching the yarn. An example workflow comprising various steps for manufacturing an artificial turf fiber which may be used as the first yarn is illustrated in FIG. 5.

[0126] The first yarn may be a synthetic polymer yarn made of or comprising one or more polymers such as, for example, a single-phase or multi-phase blend. An example of a polymer mixture comprising two different polymers and a compatibilizer is described with reference to FIGS. 7, 8 and 9.

[0127] It is also possible that the first yarn used for hot-texturization and/or the second yarn used for low-temperature-texturization can mainly comprise or consist of a single type of polymer such as, for example, polyethylene, polypropylene, polyamide, polyester, etc.

[0128] In a second step 224, a low-temperature-texturized yarn is manufactured. The manufacturing comprises a step of texturizing a second yarn at a second temperature, e.g., 60 C. The texturizing can be performed using the texturization apparatus as illustrated, for example, in FIG. 6. As for the hot-texturized yarn, the manufacturing process may comprise a plurality of additional processing steps such as extruding and quenching and optionally stretching the yarn.

[0129] The second yarn may be a synthetic polymer yarn made of or comprising one or more polymers such as, for example, a single-phase or multi-phase blend. An example of a polymer mixture comprising polyethylene as base polymer and further comprising polyamide and a compatibilizer is described with reference to FIGS. 7, 8 and 9.

[0130] The first and second yarns may have the same type of polymer or polymer blend or may have different types of polymers. The non-texturized yarn may be manufactured in a similar manner like the texturized yarn and as described for example with reference to FIG. 5, with the difference that no texturization step is performed on the non-texturized yarn.

[0131] The steps 222 and 224 may be performed simultaneously using different texturization apparatus, or sequentially using the same or different texturization apparatus. It is also possible that step 224 is executed before step 222.

[0132] The low-temperature-texturized yarn, the hot-texturized yarn and the non-texturized yarn are then transported to a machine configured to integrate these three types of yarn in step 226 into a carrier. The carrier can be, for example, a synthetic fabric and the machine may be, for example, a tufting machine. The integration can comprise weaving or tufting or inserting the respective yarn into the carrier.

[0133] If the yarns are integrated via tufting, the three yarns are fed through needles that punch the yarns into a carrier 202 also referred to as primary backing, thereby creating loops of fibers on the surface of the carrier. These loops from the tufting process provide the basic structure of the turf, with tuft knots at the positions where the fibers were punched through the carrier and with tuft rows formed by series of tuft knots.

[0134] Next in step 228, the loops are cut to form individual strands referred to herein as fibers. The fibers extending to one side of the carrier give the turf its grass-like appearance. At this stage, the artificial turf may also be referred to as greige good (unfinished artificial turf). Often, but not necessarily, a liquid, viscous mass is applied onto the side of the greige good opposed to the side from which the fibers extend. For example, a liquid latex or polyurethane reaction mixture may be applied. This mass has the function of firmly fixating the fibers upon hardening of the mass, because the mass will wetten at least some portions of the fibers which extend to the lower side of the carrier (see FIG. 4). Heating the greige good in an oven in step 230 or any other form of exposing the greige good to high temperatures referred herein as third temperature helps to cure and/or harden the secondary backing material, ensuring they properly bond and stabilize the tufted fibers. This process enhances the durability, stability, and longevity of the artificial turf. The heat applied in this step has the additional advantage of causing at least the texturized and often also the non-texturized fiber to change its length in a defined, desired manner. Hence, a single heating step may have a dual function of hardening the secondary backing and inducing a change in fiber length. However, it is possible that the manufactured turf is free of a secondary backing and step 230 is performed solely with the purpose of changing the length of the fibers in a defined manner.

[0135] Typically, the duration of exposing the greige good in step 230 ranges from a few minutes, e.g., 5 minutes, to 30 minutes, depending on various factors. For example, if the third temperature is applied (also) for the hardening of a PU-based liquid backing, the time in the oven may depend on the temperature, the reactivity and the thickness of the applied PU-reaction mixture. Typically, the time of exposure of the carrier with the integrated fibers to the third temperature is at least 2 minutes, preferably at least 5 minutes.

[0136] Next in step 232, the heated greige good, which may optionally in addition comprise a solidified backing, is provided as the finished artificial turf which may be inspected, rolled and prepared for delivery and installation.

[0137] Preferably, all three fiber types are stretched to their maximum length at the moment they are cut in step 228. This is to ensure that all three types of fibers have a well-defined and tightly controlled length: the stretching may ensure that some fibers are not ultimately longer than others of the same fiber type because they are less taut at the time of cutting. The measure also ensures that the lengths of cold and hot textured fibers after cutting are determined by the degree of texturization achieved in the respective texturing process and not by the fact that some fibers are tighter clamped in the tufting and cutting machine than other fibers of the same type at the moment of cutting. This measure may ensure that all fibers of the same type are approximately of the same length in the final product, ensuring a uniform distribution of mechanical and visual properties of the artificial turf.

[0138] FIG. 2 is a diagram illustrating the three types of fibers comprised in the finished artificial turf 200 after having exposed the turf to the third temperature in step 230. The artificial turf 200 comprises a plurality of hot-texturized fibers 204 all having approximately the same length L1 measured from the upper surface of the carrier 202 to the tip of the fiber 204. The turf also comprises a plurality of low-temperature-texturized fibers 206 all having approximately the same length L2 measured from the upper surface of the carrier 202 to the tip of the fiber 206. The turf also comprises a plurality of non-texturized fibers 208 all having approximately the same length L3 measured from the upper surface of the carrier 202 to the tip of the fiber 208.

[0139] Depending on the use of the artificial turf, the length L1, L2 and L3 and/or the organization of the different fiber types in tuft knots and tuft rows may differ. In some examples, the artificial turf 200 comprises tuft knots comprising a mixture of one or more fibers of each of the three fiber types 204, 206, 208. This may provide a particularly homogeneous distribution of the visual and mechanical properties caused by the different fiber types.

[0140] In other embodiments, two or three of the three different fiber types may be organized in tuft bundles and/or tuft rows solely comprising fibers of a single fiber type, whereby tuft knots and/or tuft rows of the different fiber types may change intermittently to ensure a homogeneous distribution of the visual and mechanical properties caused by the different fiber types. This may have the advantage that the tufting process may be facilitated, because often an artificial turf yarn may be provided as a pre-fabricated fiber bundle to the tufting machine.

[0141] The density (number of fibers per area) and/or the thickness of the fibers of the three fiber types may be identical or may be different in different types of artificial turf, allowing a fine-grained adaptation to the requirements of the intended use case scenario. It is also possible that in some examples, the artificial turf comprises one or more additional types of fibers.

[0142] FIG. 3 is an illustration of the effect of the third temperature on the length of the different fibers. Hence, FIG. 3 may be considered as a schematic illustration of the length changes induced in an oven heated to the third temperature, e.g., 100 C. When the unfinished artificial turf 203, also referred to as greige good, enters the oven, the hot-texturized fiber 204 may have an initial length L1i, the low-temperature-texturized fiber 206 may have an initial length L2i, and the non-texturized fiber 208 may have an initial length L3i. After having exposed the unfinished turf 203 to the third temperature to the above-mentioned duration, the finished artificial turf 200 is removed from the oven. The lengths L1i, L2i of the hot-texturized and low-temperature-texturized fibers will have changed significantly, and also the length L3i may have changed (typically shrunk) in some examples, but typically not as much as the length of the other fiber types. In some examples, the length of the non-texturized fibers may not change at all (meaning L3i=L3). As illustrated in FIG. 3, the exposure to the third temperature results in a significant shrinkage of the length of the hot-texturized fiber 204, an in an elongation of the low-temperature-texturized fibers 206. In other words: L1<L1i, and L2>L2i.

[0143] Although the length L1i, L1, L2i, L2, L3i, L3 may differ in different examples of the artificial turf, according to preferred examples, the hot-texturized fibers form a stabilizing layer whose height L1 is significantly, typically 1.0-3.0 cm shorter than the height L2, L3 of the low-temperature-texturized and the non-texturized fibers which together may form a performance layer. The stabilizing layer may have the function of providing mechanical stability to the fibers, and stabilizing or substituting infill. The fibers 206 and 208 together may be responsible for the visual properties of the turf 200, in particular the absence of grain, while the low-temperature-texturized fiber provides additional mechanical stability, slows the ball movement and prevents the footing problem.

[0144] According to example 1, the final artificial turf has the following lengths: L3=7.0 cm; L2=6.9 cm; L1=4 cm.

[0145] According to example 2, the final artificial turf has the following lengths: L3=6.0 cm; L2=5.7 cm; L1=3.5 cm.

[0146] According to example 3, the final artificial turf has the following lengths: L3=6.2 cm; L2=5.8 cm; L1=1.5 cm.

[0147] According to example 4, the final artificial turf has the following lengths: L3=6.5 cm; L2=5.5 cm; L1=2.5 cm.

[0148] According to example 5, the final artificial turf has the following lengths: L3=4.5 cm; L2=4.4 cm; L1=2.0 cm.

[0149] According to example 6, the final artificial turf has the following lengths: L3=4.3 cm; L2=4.4 cm; L1=2.5 cm.

[0150] According to example 7, the final artificial turf has the following lengths: L3=7.8 cm; L2=7.7 cm; L1=4.5 cm.

[0151] According to example 8, the final artificial turf has the following lengths: L3=6.8 cm; L2=7.0 cm; L1=4.2 cm.

[0152] According to example 9, the final artificial turf has the following lengths: L3=6.0 cm; L2=6.2 cm; L1=3.5 cm.

[0153] According to example 10, the final artificial turf has the following lengths: L3=6.2 cm; L2=6.4 cm; L1=1.5 cm.

[0154] FIG. 4 is an illustration of artificial turfs with and without a secondary backing. To ease the understanding, only the tuft loops of a single fiber type, in this case, of the non-texturized fibers, are shown in FIGS. 4A-C.

[0155] FIG. 4A shows the carrier 202, the fibers 302 extending a length 304 from the carrier to the fiber tips from the carrier to the upper side which have been formed by cutting tuft loops facing towards the upper side of the carrier, and a series 306 of tuft knots (non-cut tuft loops on the lower side of the carrier). FIG. 4A shows an artificial turf which does not comprise a secondary backing.

[0156] FIG. 4B illustrates an example of an artificial turf comprising a secondary backing 308 solely on the lower side of the carrier. For example, the backing 308 may be made from latex or PU.

[0157] FIG. 4C illustrates an example of an artificial turf comprising a secondary backing 308 on the lower side and on the upper side of the carrier. For example, the backing 308 may have initially been applied as a liquid, viscous mass to the lower side of the carrier like in FIG. 4B, and may then have migrated through openings in the carrier fabric to the upper side. This may provide a particularly firm fixation of the fibers in the carrier. The artificial turf examples shown in FIGS. 4A-C may in addition comprise the low-temperature-texturized and hot-texturized fibers as illustrated in FIG. 3, but these fibers are not shown to ease the understanding of the functionality of the secondary backing.

[0158] FIG. 5 is a block diagram of a manufacturing line for manufacturing artificial turf yarn. The manufacturing process may comprise a gas-dynamic texturizing process employing heated compressed gas in order to texturize artificial turf yarn. This process may also be referred to as bulked continuous filament texturizing as described, for example, in Chapter 4.12.6 BCF (Bulked Continuous Filament) Texturizing in Synthetic Fibers by Franz Fourn, Carl Hanser Verlag Gmbh & Co, 1999, ISBN 10:3446160728/ISBN 13:9783446160729, pp. 456-460). The patents EP0282815B1 and EP0163039B1 also disclose a texturing apparatus for gas-dynamic texturizing of endless filament threads. Also, the patent applications WO2019/096490 A1 and WO 2021/028471 describe examples of a gas-dynamic texturization process and systems and apparatus which can be employed for conducting a gas-dynamic texturization process. These documents are enclosed herein by reference in their entirety, and in particular with respect to the texturization processes and texturization systems described therein.

[0159] Manufacturing and utilization of textured (curled) yarns in artificial turf systems may provide for the above-mentioned benefits. Textured yarns are different from flat monofilament yarns in that they are irregularly crimped. The textured yarns exhibit a zig-zag shape having at least one of the characteristic features such as kinks, jogs, bends, crinkles, buckling, and curls. These features make the textured yarns more voluminous and soft when manufactured into artificial turf, compared to flat monofilament fibers. The textured yarn may also be advantageous over flat yarn concerning the capability of holding infill material in its place, i.e. reducing the splash of infill material when, e.g. a ball hits the ground.

[0160] In order to texturize a synthetic yarn, a gas-dynamic texturing apparatus may be used. For example, a gas-dynamic texturing system may be employed that comprise a texturing apparatus comprising an inlet for a fluid under pressure for gas-dynamic texturing of the artificial turf yarn in the texturing device. The fluid has a temperature above ambient temperature. The system may further comprise an apparatus heating device being configured to heat the texturing apparatus by electromagnetic induction or through physical contact with the texturing apparatus. The fluid can be for instance hot air. The apparatus heating device configured to heat the texturing apparatus through physical contact can be an electrical resistance heater. The artificial turf yarn can be a monofilament yarn. Electromagnetic induction heating can heat electrically conducting components of the texturing apparatus by electromagnetic induction, through heat generated in the components by eddy currents. An apparatus heating device configured to heat the texturing apparatus by electromagnetic induction can comprise an electromagnet and an electronic oscillator that passes a high-frequency alternating current (AC) through the electromagnet. The rapidly alternating magnetic field penetrates the texturing device, generating electric currents (eddy currents) inside the electrically conducting components. The eddy currents flowing through the resistance of the material heat it by Joule heating. In ferromagnetic (and ferrimagnetic) materials like iron, heat may also be generated by magnetic hysteresis losses.

[0161] In some examples, the texturing system can provide for an advanced process control. When the texturing apparatus is not used, the fluid parameters such as flow and temperature have to be tuned such that the texturing apparatus has the desired process temperature and the flow of the fluid in the texturing apparatus (e.g. in a yarn channel of the texturing apparatus and/or in an expansion chamber of the texturing apparatus) has optimal gas-dynamic properties for the texturing process. This is not the case when the apparatus heating device is employed. In this case the heating of the texturing apparatus is primarily provided by the apparatus heating device, whereas the flow of the fluid can be tuned primarily (or only) for the purpose of achieving optimal gas-dynamic properties of the fluid flow in the texturing apparatus.

[0162] The apparatus heating device may be configured to hold the temperature of the texturing apparatus at the desired temperature.

[0163] The temperature of the fluid can be set to the first temperature for texturizing the first yarn, and can be set to the second temperature for texturizing the second yarn. For example, in order to texturize the first yarn, the temperature of the fluid can be set in the range of 50-150 degrees Celsius, preferably in the range 70-130 degrees Celsius, more preferably in the range of 70-90 degrees Celsius. The apparatus heating device can be configured to heat the texturing apparatus such that its temperature differs from the temperature of the fluid less than 10%, preferably less than 5%, more preferably less than 0.5%.

[0164] In one example, the temperature used for conducting the hot-texturization is determined using differential scanning calorimetry, DSC, data of a sample of the polymer or polymer blend to be used for manufacturing the fiber to be texturized.

[0165] Utilization of the DSC data may be advantageous, because it may provide for a melting temperature of the polymer (or its particular polymorphic modification) in the polymer blend. The texturing (curling) of the monofilament yarn may be performed within the temperature range, in which at least a portion of a crystalline fraction (or of a polymorphic modification) of at least one of the polymers of the polymer blend remains in a solid state. Thus, the knowledge of the melting temperatures determined using DSC data may provide for the temperature range that may be optimal for the texturing (curling) process.

[0166] In another embodiment, the temperature for texturizing the first yarn to provide the hot-texturized yarn is determined such that a portion of a crystalline fraction of the polymer blend is in a solid state when the gas-dynamic texturing is performed and another portion of the crystalline fraction of the polymer blend is in a molten state when the gas-dynamic texturing is performed.

[0167] This embodiment may be advantageous because it may provide for an optimal process temperature, wherein at least a portion of each of the polymers (or their polymorphic modifications) of the polymer blend is in a molten state. The portion of the crystalline fraction that is molten can be more than 10% (preferably 25%) by weight of the entire crystalline fraction. The portion of the crystalline fraction that remains solid can be more than 10% (preferably 25%) by weight of the entire crystalline fraction.

[0168] With reference to FIG. 5, the system of manufacturing of a textured (curled) yarn 122 (or textured artificial turf yarn) comprises: an extruder 100 (e.g. a screw-extruder) and a texturing (curling) system. The system can further comprise one or more drawing devices 115, 118, one or more thermosetting (or heating) devices (e.g. godets, ovens) 117, one or more cooling devices (e.g. godets, bathes with cooling liquid) 116, 120, 97, and one or more rollers 121.

[0169] The extruder 100 comprises at least one hopper 101 for feeding components of a monofilament yarn (e.g. a blend of polymers) into the extruder and one outlet 102 for the monofilament yarn. The outlet 102 can be implemented as a wide slot nozzle or a spinneret. A polymer melt formed in a chamber of the extruder is pressed through the outlet 102 to form a monofilament yarn of a specific shape.

[0170] The monofilament yarn can be cooled down after the extrusion using the cooling device 97. When the cooling device is implemented as a godet, it can comprise two rollers 99 and 98 for winding the monofilament yarn 119. The cooling process can be implementing by maintaining a temperature of the rollers 99 and 98 within the specified range and/or by air cooling and/or by water cooling. A temperature of water (or air) can be kept within a specified range as well. Alternatively, the cooling device can be a bath with a cooling liquid (e.g. water) in which the monofilament yarn is cooled. The monofilament yarn is cooled down using the cooling device 97 to a temperature where crystallization can take place. In the crystallization process the crystallites are forming to a percentage, which depends on the cooling rate. The higher the cooling rate, the less is the crystallinity and vice versa.

[0171] The monofilament yarn can be further drawn using the drawing device 115. The drawing device can comprise three rollers 104, 103, 105. The drawing ratio is defined as the ratio of linear speeds of a pair of rollers 103 and 104 (or 104 and 105). The drawing device 115 can be operable for heating the monofilament yarn 119 during or before the drawing process. This can be implemented by heating one or more the rollers in order to keep their temperature within a predetermined temperature range and/or by air heating, wherein the hot air has a temperature within a predetermined temperature range. The elongation of the monofilament yarn in the drawing device can force the macromolecules of the monofilament yarn to parallelize. This results in a higher degree of crystallinity and increased tensile strength, compared with undrawn monofilament yarn.

[0172] According to an alternative example not depicted in a figure, the drawing device may comprise one or more feeding rollers, an oven, and one or more receiving rollers. The one or more feeding rollers are configured to feed the monofilament yarn 119 into the oven. The one or more receiving rollers are configured to receive the monofilament yarn from the oven. The oven is configured to heat the monofilament yarn. The drawing ratio is determined by a ratio of the linear speeds of the feeding roller being the last roller before the oven and the receiving roller being the first after oven. The thermosetting process (drawing process) is performed in the oven 80, in which the monofilament yarn in stretched and heated simultaneously.

[0173] The monofilament yarn can be further cooled using the cooling device 116. The cooling device, when implemented as a cooling godet can have rollers 106 and 107. The cooling device can be built and/or function in the same way as the cooling device 97. Afterwards the monofilament yarn can be further drawn using the drawing device 118 having rollers 110, 111, and 112. The drawing device 118 can be built and/or function in the same way as the drawing device 115.

[0174] The monofilament yarn can be further heated using one or more heating devices or elements (e.g. device 117). The heating device comprises a heater (or a heating element) and a temperature sensor for sensing a temperature of the heater (or the heating element). The heater can be implemented as an electrical resistance heater. The heating device is controlled by a controller (e.g. controller 152) such that the temperature of the heater is kept at a desired temperature (this temperature is mentioned herein as the third desired temperature as well). The controller comprises a computer processor 153 and memory 154 comprising instructions executable by the computer processor. The controller is communicatively coupled to the heating device and the temperature sensor configured to sense a temperature of the heating device. The communicative coupling can be implemented via a computer network 155.

[0175] The controller is operable to hold an actual temperature of the heating device at the desired temperature. The desired temperature can be selected such that the yarn cooled during a transportation from the heater to the texturing apparatus (e.g. distance 156) has a temperature of the texturing process when it enters the texturing apparatus 114, or its inlet port 124 for receiving the yarn. In this case the desired temperature is higher than the temperature of the texturing process. The execution of the computer instructions by the computer processor 153 causes the controller to hold the process temperature at the desired temperature.

[0176] The control of the process temperature can be implemented as follows. The controller reads out the temperature of the heater sensed by the temperature sensor. The temperature of the heater is used as a feedback signal for setting the temperature of the heating device 117 in order to provide the heating of the monofilament yarn to the desired temperature. The functioning of this feedback loop can be implemented using a proportional-integral-derivative algorithm. The desired temperature can be specified as a temperature range. In this case the holding of the actual temperature at the desired temperature comprises keeping the actual temperature within the specified range, in particular the actual temperature is kept as close as possible to a middle temperature of the temperature range. The middle temperature is equal to an average of a lower boundary of the temperature range and an upper boundary of the chosen temperature range.

[0177] The heating device 117, when implemented as a godet, comprises a pair of rollers 108 and 109. The heating of the monofilament yarn can be made by keeping a temperature of the rollers within a predetermined temperature range and/or by hot air having a temperature within a predetermined temperature range. For instance the roller 109 can be equipped with a heater 150 and a temperature sensor 151 both communicatively coupled to the controller 152.

[0178] A controller 70 is configured to control a temperature of the texturing apparatus 114. The controller 70 comprises a computer processor 72 and memory 73 comprising instructions executable by the computer processor. The controller is communicatively coupled to the temperature sensor 158 configured to sense a temperature of the texturing apparatus 114, and a heating device, 129. The heating device can be configured to heat the texturing device through physical contact between the texturing device and the heating device or by electromagnetic induction. The physical contact can be a direct physical contact or a contact in which a thermally conductive paste is used between the heating device 129 and the texturing apparatus 114.

[0179] At least a portion of the texturing device can be placed inside or in the proximity of the electromagnet of the heating device configured to heat the texturing device by electromagnetic induction. The heating device can be implemented as an electrical resistance heater. Further heating devices and temperature sensors can be operated by the controller 70 (or other controllers). The communicative coupling can be implemented via a computer network 71. The controller is operable to hold an actual temperature of the texturing apparatus at a desired temperature which can be the temperature required for the texturing process. The desired temperature can be specified as a temperature range. In this case the holding of the actual temperature at the desired temperature comprises keeping the actual temperature within the specified range, in particular the actual temperature is kept as close as possible to a middle temperature of the temperature range. The middle temperature is equal to an average of a lower boundary of the temperature range and an upper boundary of the chosen temperature range. The execution of the computer instructions by the computer processor 72 causes the controller to hold the texturing apparatus temperature at the desired temperature.

[0180] The control of the texturing apparatus temperature can be implemented as follows. The controller reads out the temperature of the texturing apparatus sensed by the temperature sensor 158. The temperature of the texturing apparatus is used as a feedback signal for setting the temperature of the heating device 129 in order to provide the heating of the texturing apparatus to the desired temperature. The functioning of this feedback loop can be implemented using a proportional-integral-derivative algorithm.

[0181] The texturing apparatus 114 has an inlet 130 for a fluid under pressure used for the texturing process. The fluid can be hot air, i.e. air above ambient temperature. The hot fluid under pressure can be produced by a compressor 166 and a heating element 165 for heating the fluid. The heating element can be implemented as an electrical resistance heater. A temperature of the fluid entering the texturing apparatus can be controlled by controller 162 comprising a computer processor 163 and a memory 164 storing processor executable instructions. The controller 162 is communicatively coupled to the heating element 165 and to a temperature sensor 131 configured to sense a temperature of the fluid in the texturing apparatus (or in the inlet 130). The communicative coupling can be implemented via a computer network 167. The controller is operable to hold an actual temperature of the fluid at a desired temperature which can be the temperature required for the texturing process (this desired temperature is mentioned as the second desired temperature herein as well). The desired temperature can be specified as a temperature range. In this case the holding of the actual temperature at the desired temperature comprises keeping the actual temperature within the specified range, in particular the actual temperature is kept as close as possible to a middle temperature of the temperature range. The middle temperature is equal to an average of a lower boundary of the temperature range and an upper boundary of the chosen temperature range. The execution of the computer instructions by the computer processor 163 causes the controller 162 to hold the temperature of the fluid at the desired temperature. The control of the fluid temperature can be implemented as follows. The controller reads out the temperature of the fluid sensed by the temperature sensor 131. The temperature of the fluid is used as a feedback signal for setting the temperature of the heating element 165 in order to provide the heating of the fluid to the second desired temperature. The functioning of this feedback loop can be implemented using a proportional-integral-derivative algorithm.

[0182] The desired temperature of the texturizing apparatus 114 may be the first temperature for texturizing the first yarn to provide the hot-texturized yarn and may be the second temperature for texturizing the second yarn for providing the low-temperature-texturized yarn.

[0183] After the heating using one or more heating devices 117 the monofilament yarn is textured (curled) in the texturing apparatus 114. The textured (curled) monofilament yarn 122 is cooled using a cooling godet 120. The cooling can be performed by keeping a temperature of a roller 120 of the cooling godet within a predetermined temperature range and/or by air having a temperature within a predetermined temperature range. The textured monofilament yarn 122 can be forwarded further to another roller 121 for further processing.

[0184] The sequence of optional processing units, i.e. the cooling godet 97, the drawing device 115, the cooling godet 116, the drawing device 118, the heating godet 117, can be different. It depends on particular processing steps required for preprocessing steps before the texturing (curling) process. Additional drawing devices, and/or heating devices, and/or cooling devices can be included. For instance several heating devices can be used instead of the single heating device 117 depicted in FIG. 1 in order to provide for a gradual heating of the monofilament yarn 119. Alternatively, the preprocessed monofilament yarn can be used for the texturing (curling). In this case there can be no need of the extruder 100, the cooling devices 97 and 116, and the drawing device 115. When drawing process can be executed in several steps, several drawing devices 115 can be used in series.

[0185] At least some of the processing units of the system depicted on FIG. 1 can be operated as stand-alone processing units (or groups of units), wherein each of the units (or groups of units) is configured to perform a particular operation, such as extruding, drawing, or texturing. In this case the process can be implemented as reel-to-reel process, wherein yarn is winded on a reel after completion of the operation and winded off the reel for processing the yarn in the next operation. For instance, the extruding process can be performed using the extruder 100 and the cooling device. The texturing process can be executed using a texturing system comprising the texturing apparatus 114 equipped with the heating device 129 and the temperature sensor 158 configured to sense the temperature of the texturing apparatus. In addition the texturing process can be executed using fluid heating element 165 controlled by the controller 162 and/or the yarn heating element 150 controller by the controller 152.

[0186] The processing units can be configured such that they process/produce several filaments in parallel. For instance, several filaments can be extruded in parallel using the extruder 100. In this case the spinneret has several holes. The drawing device 115 can be configured to process several filaments in parallel. For instance, the rollers 103-105 can be made broad enough to process several filaments in parallel. The same approach can be used for the other units 116, 118, 117, equipped with rollers 81-86, 106, 107, 110-112, 108, 109. The texturing apparatus 114 can be configured to process several filaments in parallel as well. The filaments can be fed into the texturing apparatus through the inlet port 124 of the texturing apparatus 114. After the texturing the filaments can be cooled down using the cooling godet 120.

[0187] At least some of processing units of the system depicted on FIG. 1 can be components of a system for manufacturing of an artificial turf. In addition the system for manufacturing of the artificial turf comprises a system for attaching of a textured artificial turf yarn to a backing of the artificial turf. The textured artificial turf yarn can be manufactured using the texturing system. The system for attaching of the textured artificial turf yarn to the backing can comprise a tufting machine being configured to tuft the textured artificial turf yarns through the backing (e.g. stitch/knit the yarns into a sheet of a woven material). The system can further comprise a coating system configured to coat the backing on its back side to adhere the textured artificial turf yarns to the backing. The coating may comprise at least one of acrylic, polyurethane, latex or some combination thereof to assist in preventing the yarns from undesirably detaching from the artificial turf with extended use. The system for attaching of the textured artificial turf yarn to the backing can further comprise another system configured to produce an infill layer of a particular material atop the backing and dispersed among the artificial turf yarn such that portions of the textured artificial turf yarn extend above the infill layer. Utilization of either the backside coating or the infill layer can be optional.

[0188] FIG. 6 depicts a cross-section of a texturization apparatus 114 according to one possible example in greater detail. The texturing apparatus comprises a housing 123. The housing can be a hollow elongated member, which can be implemented as pipe. The pipe may have a length of 0.15 m and a diameter of 0.015 m. The inlet port (injector jet) 124 for yarn ingress is arranged on one end of the elongated member, whereas an expansion chamber 147 is arranged on another end of the elongated member. The expansion chamber may have a tubular form having one or more adjacent hollow cylindrical shapes. An inlet 130 for the fluid under pressure used for the texturing process is arranged on a side wall of the elongated member, wherein the inlet 130 is configured for infeed of the fluid inside the housing. The inlet 130 can be a pipe, wherein one end of the pipe has an opening arranged for connecting to the gas pipe line 161 and another end of the pipe has another opening connecting the interiors pipe with the housing. The temperature sensor 131 for sensing the temperature of the fluid can be located in the inlet 130 (or in the pipe of the inlet 130).

[0189] A yarn channel 126 is arranged within the housing. The yarn channel can be implemented as a hollow elongated member, e.g. a pipe or conduit. An end portion 125 of the yarn channel has an increasing inner diameter such that an end of the yarn channel has a bigger diameter than a diameter of the yarn channel outside the end portion. The end portion 125 can be funnel shaped. The inlet port 124 is arranged such that it has a threaded bushing 177 for regulating its position in the housing. The inlet port has a channel 178 for infeed of yarn 119 into the yarn channel 126. The inlet has a conical shape 159 adjacent to a portion of the inlet which has the threaded bushing 177. A surface of the conical shape and an inner wall of the end (funneled) portion constitute a channel 176 for infeed of the fluid into the yarn channel 126. The surface of the conical shape and the inner wall of the end portion can be parallel to each other. The inlet port 124 is arranged such that rotation of the threaded bushing 177 results in a change in a distance between the surface of the conical shape and the inner wall of the (funneled) end portion, i.e. in a change in a cross-section of the channel 176. This functionality can be used for tuning of the fluid flow in the yarn channel 126 towards the expansion chamber 147.

[0190] The texturing apparatus 114 is arranged such that an inner wall of the housing 123 and an outer wall of the yarn channel 126 constitute a channel 127 for guiding the fluid from the inlet 130 into the yarn channel 126 via the channel 176. A temperature sensor 128 for sensing the temperature of the fluid can be positioned in the channel 127. The temperature sensor 128 can be used instead temperature sensor 130 for controlling the temperature of the fluid by the controller 162.

[0191] The texturing apparatus comprises means for entraining of the yarn 119 (e.g. artificial turf yarn or yarn for textile manufacturing) so that it runs concurrently with the fluid in the yarn channel 126. These means can be constituted by the channel 176 in the end (funnel) portion of the yarn channel 126, the channel 178 of the inlet port 124, wherein the channel 178 has an opening in the end (funnel) portion 159 as well. The fluid guided by the channel 176 enters the yarn channel 126 and entrains the yarn 119 into the yarn channel 126, whereas the yarn is fed into the texturing apparatus 114 via the channel 178 of the inlet port 124. In other words, the yarn is transported downstream the yarn channel by the intake of the fluid. Both, the yarn and the fluid move downstream to the expansion chamber 147 of the texturing apparatus 114. The fluid stream exerts a tractive force on the monofilaments (yarn strands) such that they are aspirated into the channel 178 of the inlet port (injector jet) 124.

[0192] The expansion chamber 147 leads out of the yarn channel 126 downstream thereof. A downstream circular outlet opening of the yarn channel 126 is adjacent to a circular inlet opening 182 of an inlet 171 of the expansion chamber 147, wherein a center of the downstream circular outlet opening of the yarn channel 126 coincides with a center of the circular inlet opening 182 of the inlet 171 of the expansion chamber and a diameter of the downstream circular outlet opening of the yarn channel 126 is less than a diameter of the circular inlet opening 182 of the inlet 171 of the expansion chamber. Such a configuration of the yarn channel 126 and the expansion chamber constitute a discrete increase in diameter downstream the fluid flow, which acts as a diffuser for the fluid flow.

[0193] The texturing apparatus has a release mechanism for attachment/detachment of the expansion chamber 147 to the texturing apparatus, in particular to its housing 123. The release mechanism can be implemented in various ways. The expansion chamber 147 may be positioned partially within the housing 123, in particular at least a portion of the inlet 171 of the expansion chamber is positioned within the housing 123, when the expansion chamber 147 is attached to the housing 123. Such a configuration may enable non-positive or frictional connection (e.g. spigot-socket fitting connection) of the expansion chamber to the housing. In the example depicted in FIG. 6 the inlet 171 (i.e. a spigot) of the expansion chamber 147 has an outer diameter which tightly fits into a tubular end section (i.e. a socket) of the housing. The tight fitting may generate sufficient friction force providing attachment of the expansion chamber 147 to the housing 123. The fitting may be threaded or unthreaded. Alternatively, the release mechanism can be implemented as a clamping mechanism. The clamping mechanism depicted in FIG. 6 is implemented as a thread 133 in the tubular end section of the housing 123 and a screw 160. The screw 160, when screwed in the thread 133, exerts a clamping force on the inlet 171 that keeps the expansion chamber 147 attached to the housing 123. In order to avoid deformation of the inlet 171 by the clamping force, the inlet can be manufactured out of a material, which has a higher degree of hardness, than material out which the porous sidewall of an expansion chamber section 170 adjacent to the inlet 171. The inlet 171 can be made solid or have a lower porosity than the sidewall, because the inlet 171 is positioned within the tubular end section housing which is impermeable for the fluid.

[0194] When the yarn and the fluid enter the expansion chamber 147 the flow of the fluid is separated from the wall and outer layers of the flow build vortices or eddies with areas of reversed flow, i.e. the fluid builds a turbulent flow near a surface of the expansion chamber. Inside the expansion chamber the yarn follow the direction of the fluid flow and are thereby deformed. In a downstream portion of the expansion chamber 147 the deformed (textured) yarn is further deformed by the turbulent flow, in addition it is decelerated and forms a yarn plug. The yarn plug is disintegrated in the lower end of the expansion chamber. A portion of the fluid 149 and the textured yarn 122 of the disintegrated plug egress through a downstream outlet 181 of the expansion chamber 147. The textured yarn egressing though the downstream outlet 181 is guided by the guide tube 148 to the cooling device 120. The guide tube 148 may be connected to the expansion chamber 147 in a similar way as the expansion chamber 147 is connected to the housing 123 using another release mechanism. For instance, the connection of the guide tube 148 to the expansion chamber 147 may be a releasable spigot-socket fitting, friction, clamping, or non-positive connection. The fitting may be threaded or unthreaded. In the example depicted in FIG. 6, the downstream outlet 172 (i.e. a socket) of the expansion chamber 147 has a an inner diameter in which an outer surface of an upper/upstream section (i.e. a spigot) of the guide tube 148 fits tightly.

[0195] The downstream outlet 181 and the inlet 182 are connected by an inner channel 169 of the expansion chamber 147. The inner channel may have a constant diameter throughout its length. Alternatively, the inner channel may have a tapering in a direction from the downstream outlet 172 of the expansion chamber to the inlet 171 of the expansion chamber, i.e. a diameter of the inner channel may decrease in this direction.

[0196] The expansion chamber 147 comprises fluid exhaust means for egress of the fluid from the expansion chamber independently of egress of the artificial turf yarn. These means are needed because the cross-section of the expansion chamber is effectively blocked by the yarn plug. The exhaust means comprise a side wall of at least a section 170 of the expansion chamber 147. The side wall is porous to provide egress of a portion 135 of the fluid. The sidewall may constitute a section of the aforementioned inner channel. A fluid permeability of the sidewall may increase in the direction from the inlet to the downstream outlet of the expansion chamber.

[0197] FIGS. 7, 8 and 9 illustrate the extrusion of the polymer mixture, also referred to as polymer blend, into a monofilament. Shown is an amount of polymer blend 400. In some examples the polymer blend can have different compositions.

[0198] According an example of a polymer blend depicted in FIG. 7, within the polymer blend 400 there is a large number of portions of a first polymer 402 of the polymer blend being at least partially embedded in a second polymer 408 of the polymer blend 400. The portions of a first polymer 402 may have the form of beads. The polymer beads may be made of one or more polymers that is not miscible with the second polymer 408 and is also separated from the second polymer by a compatibilizer 406. These three items form the phases of a three-phase system. If there are additional polymers or compatibilizers added to the system then the three-phase system may be increased to a four, five, or more phase system. The first polymer and the second polymer are immiscible. The first polymer forms polymer beads surrounded by the compatibilizer within the second polymer.

[0199] According to some examples, the first polymer (which forms beads within the second polymer) is one of polyamide, polyethylene terephthalate, polybutylene terephthalate, polyester, and polybutyrate adipate terephthalate, and/or the second polymer (also referred to as base polymer or main polymer of a polymer mixture) is any one of polyethylene, polypropylene, and a mixture thereof.

[0200] For example, the first polymer comprises or consists of polyamide (PA) and the second polymer comprises or consists of polyethylene (PE). Stretching the polyamide will cause an increase in the crystalline regions making the polyamide stiffer. This is also true for other semi-crystalline plastic polymers. The first polymer may comprise at least 90 weight percent of PA. The second polymer can comprise at least 90 weight percent of PE. The polymer mixture can comprise at least 30 weight percent of PE and/or at least 30 weight percent of PA.

[0201] The compatibilizer may be any one of the following: a maleic acid grafted on polyethylene or polyamide; a maleic anhydride grafted on free radical initiated graft copolymer of polyethylene, SEBS, EVA, EPD, or polyproplene with an unsaturated acid or its anhydride such as maleic acid, glycidyl methacrylate, ricinoloxazoline maleinate; a graft copolymer of SEBS with glycidyl methacrylate, a graft copolymer of EVA with mercaptoacetic acid and maleic anhydride; a graft copolymer of EPDM with maleic anhydride; a graft copolymer of polypropylene with maleic anhydride; a polyolefin-graft-polyamidepolyethylene or polyamide; and a polyacrylic acid type compatibilizer.

[0202] In another embodiment, the first polymer comprises (or consists of) polyester and the second polymer comprises (or consists of) PE. The first polymer may comprise at least 90 weight percent of polyester. The second polymer can comprise at least 90 weight percent of PE. The polymer mixture can comprise at least 30 weight percent of PE and/or at least 30 weight percent of polyester.

[0203] In another embodiment, the first polymer comprises (or consists of) polyester and the second polymer comprises (or consists of) polypropylene (PP). The first polymer may comprise at least 90 weight percent of polyester. The second polymer can comprise at least 90 weight percent of PP. The polymer mixture can comprise at least 30 weight percent of PP and/or at least 30 weight percent of polyester.

[0204] In another embodiment, the first polymer comprises (or consists of) PA and the second polymer comprises (consists of) PP. The first polymer may comprise at least 90 weight percent of PA. The second polymer can comprise at least 90 weight percent of PP. The polymer mixture can comprise at least 30 weight percent of PP and/or at least 30 weight percent of PA.

[0205] These embodiments related to the polymer blends/mixtures may be advantageous because it may enable utilization of a broader spectrum of polymers for manufacturing of the monofilament yarn such that the properties of the artificial turf fiber can be tailored. As it is mentioned above different polymers of the polymer blend can provide for different properties of the textured yarn. One polymer can provide for the stability and/or the resilience (e.g. the ability to spring back after being stepped or pressed down), while another polymer can provide for the softness (e.g. the softer or a grass-like feel).

[0206] These embodiments related to the polymer blends/mixtures may have a further advantage that the second polymer and any immiscible polymers may not delaminate from each other. The thread-like regions can be embedded within the second polymer. It is therefore impossible for them to delaminate.

[0207] A further advantage may possibly be that the thread-like regions are concentrated in a central region of the monofilament during the extrusion process. This may lead to a concentration of the more rigid material in the center of the monofilament yarn and a larger amount of softer plastic on the exterior or outer region of the monofilament yarn. This may further provide for an artificial turf fiber with more grass-like properties, when the artificial turf fiber is made of the low-temperature-texturized or hot-texturized monofilament yarn.

[0208] A further advantage may be that the artificial turf fibers made of the low-temperature-textured or hot-textured monofilament yarn have improved long term elasticity. This may require reduced maintenance of the artificial turf and less brushing of the fibers because they more naturally regain their shape and stand up after mechanical use.

[0209] In another embodiment the polymer blend is at least a four phase system, wherein the polymer blend comprises at least a third polymer, wherein the third polymer is immiscible with the second polymer, wherein the third polymer further forms the polymer beads surrounded by the compatibilizer within the second polymer. This embodiment may be advantageous because it may enable utilization of an even broader spectrum of polymers for manufacturing of the monofilament yarn. As it is mentioned above different polymers of the polymer blend can provide for different properties of the textured yarn. One polymer can provide for the stability, while another polymer can provide for the softness. This particular embodiment can provide for combining in a final product properties of at least three polymers.

[0210] According to one example, the low-temperature-texturized and the hot-texturized fibers are made of a three phase polymer mend, e.g., a PE-PA blend with a compatibilizer described above, and the non-texturized fiber is made of a single polymer type, e.g., PE.

[0211] The blend 400 may be formed by mixing the first polymer and the third polymer with the compatibilizer to form a first blend, heating the first blend; extruding the first heated blend; granulating the extruded first blend; mixing the first blend with the second polymer; and heating the mixed first blend with the second polymer to form the polymer blend 400. This may be advantageous because it may provide for an effective procedure for manufacturing of the polymer blend comprising multiple polymers. As an alternative the first polymer could be used to make a granulate with the compatibilizer separately from making the third polymer with the same or a different compatibilizer. The granulates could then be mixed with the second polymer to make the polymer mixture. As another alternative to this the polymer mixture could be made by adding the first polymer, a second polymer, optionally a further polymer and the compatibilizer all together at the same time and then mixing them more vigorously. For instance a two-screw feed could be used for the extruder.

[0212] According to embodiments, the low-temperature-texturized, and/or the hot-texturized and/or the non-texturized fibers comprise: [0213] the first polymer (comprised in threadlike-regions 904 depicted in FIG. 9) in an amount of 1 to 30 percent by weight of the fiber; and/or [0214] the compatibilizer in an amount of 1 to 30 percent by weight of the fiber; and/or [0215] the second polymer in an amount of 50-80 percent by weight of the artificial turf fiber.

[0216] The mentioned percentage ranges may allow for choosing an optimal material combination where, for instance, the requirements for fiber resilience, surface smoothness, and economic surface-to-mass ratio are balanced.

[0217] FIG. 8 shows the extrusion of a polymer blend through a hole of an extrusion plate 602. The polymer blend may be the blend 400 depicted in FIG. 7 or another polymer or polymer blend.

[0218] A plurality of beads of a first polymer 402 of the polymer blend 400 is at least partially embedded in a second polymer 408 of the polymer blend. A screw, piston or other device of the extruder 100 is used to force the polymer mixture through a hole 604 in a plate 602. This causes the polymer blend to be extruded into a monofilament yarn 606. The second polymer 408 and the polymer beads 402 are extruded together. In some examples the second polymer 408 will be less viscous than the polymer beads and the polymer beads will tend to concentrate in the center of the monofilament yarn. This may lead to desirable properties for the final artificial turf fiber as this may lead to a concentration of the thread-like regions in the core region of the monofilament yarn.

[0219] In another embodiment the creating of the polymer blend comprises the steps of: forming a first blend by mixing the first polymer with the compatibilizer; heating the first blend; extruding the first heated blend; granulating the extruded first blend; mixing the granulated first blend with the second polymer; and heating the granulated first blend with the second polymer to form the polymer blend. This particular method of creating the polymer mixture may be advantageous because it enables very precise control over how the first polymer and compatibilizer are distributed within the second polymer. For instance, the size or shape of the extruded first mixture may determine the size of the polymer beads in the polymer mixture.

[0220] This embodiment may be advantageous, because a so called single-screw extrusion method may be used. As an alternative to this, the polymer blend may also be created by putting all of the components that make it up together at once. For instance, the first polymer, the second polymer and the compatibilizer could be all added together at the same time. Other ingredients such as additional polymers or other additives could also be put together at the same time. The amount of mixing of the polymer blend could then be increased for instance by using a twin-screw feed for the extrusion. In this case the desired distribution of the polymer beads can be achieved by using the proper rate or amount of mixing.

[0221] FIG. 9 depicts a not to scale cross-section of a segment the monofilament yarn 900 after it is extruded and stretched in the drawing device 115. Before the drawing process the fragments of the first polymer can have an arbitrary shape, e.g. a shape of beads. The fragments of the first polymer are at least partially incorporated in the second polymer 408, 902. After the drawing process the fragments 904 of the first polymer 402 have elongated shape in comparison to the fragments of the first polymer before the drawing process. The drawing (stretching) of the extruded artificial turf yarn may stretch the yarn to a factor of 4-6.5.

[0222] Using a blend of immiscible polymers may be advantageous because it may provide for an increase in crystallinity of the artificial turf yarn (e.g. an increase in crystallinity of at least one of the polymers of the polymer blend used for the manufacturing of the artificial turf yarn). In the other words, the size of crystalline portions of the artificial turf yarn (or at least one of the polymers of the polymer blend) is increased relative to the size of amorphous portions of the artificial turf yarn. As a result, the artificial turf yarn or at least of the polymers of the polymer blend become more rigid. The stretching of the artificial turf yarn can further cause reshaping of fragments (e.g. beads) of one of the polymers of the polymer blend used for the manufacturing of the monofilament yarn such that they have thread like regions, which can make impossible delamination of different polymers in the monofilament yarn from each other, in particular when immiscible polymers are used in the polymer blend. This embodiment may also be advantageous, because the drawing (stretching) process of the monofilament yarn can give rise to polymorphism, i.e. crystallographic unit cell modification. For instance, the drawing process can result in forming triclinic crystal modification of polyethylene in addition to orthorhombic crystal modification of polyethylene formed after extruding and cooling. In particular, the use of a multiple-phase polymer blend resulting in the formation of thread-like region may ensure a particularly long-lasting and stable texturization.

[0223] FIG. 10 shows a plot 950 illustrating the shrinkage effect of various temperatures on a polyethylene yarn used for manufacturing artificial turf fiber.

[0224] According to some examples, the non-texturized, the hot-texturized and the non-texturized fibers comprise, e.g. by at least 50% of their weight, or consist of material that shrinks upon being exposed to heat if the material has not been texturized.

[0225] Several polymers can shrink when exposed to heat due to their molecular structure. Examples of such polymers include: polyolefins such as PE and PP, polyvinyl chloride (PVC), and polyester (PET).

[0226] The temperatures shown in the plot may hence be considered as examples of the third temperature applied to the greige good. This shrinkage effect is an effect caused by the material and will occur within the material of the hot-texturized, the low-texturized and the non-texturized yarns. However, selectively in the low-temperature-texturized yarns, the heat exposure will trigger an elongation/expansion process which will overcompensate the shrinkage effect, resulting in a net-expansion and elongation of the low-temperature-textured yarn, while both the non-texturized and the hot-texturized yarns (or fibers) will shrink.

[0227] The low-temperature-textured fibers will expand due to the release of internal tensions that are introduced during texturization process, optionally followed by further processing steps such as stretching and cooling. When reheated, the low-temperature-texturized yarn reverts to its original, more elongated state, at least approximately.

[0228] In the hot-texturized yarn, crystallites and molecular chains which have been generated and oriented during the texturization process, are microstructurally fixed, and are therefore largely retained during subsequent exposure to the third temperature. As a consequence, the hot-texturized fibers will shrink even more when being heat-exposed to the third temperature.

[0229] The properties described for the first yarn likewise apply to the hot-texturized fibers and the first texturized fibers and vice versa, unless this property is associated with the texturization process, because the hot-texturized fibers and the first texturized fibers are made from the first yarn. The properties described for the second yarn likewise apply to the low-temperature-texturized fibers and the second texturized fibers and vice versa, unless this property is associated with the texturization process, because the low-temperature-texturized fibers and the second texturized fibers are made from the second yarn.

[0230] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed examples.

REFERENCE SIGNS LIST

[0231] 70 Controller for the texturing apparatus [0232] 71 Computer network for communicative coupling [0233] 72 Computer processor in the controller for the texturing apparatus [0234] 73 Memory in the controller for the texturing apparatus [0235] 80 Oven for thermosetting process [0236] 97 Cooling device [0237] 98 Roller in the cooling device [0238] 99 Roller in the cooling device [0239] 100 Extruder [0240] 101 Hopper [0241] 102 Outlet [0242] 103 Roller in the drawing device [0243] 104 Roller in the drawing device [0244] 105 Roller in the drawing device [0245] 106 Roller in the cooling device [0246] 107 Roller in the cooling device [0247] 108 Roller in the heating godet [0248] 109 Roller in the heating godet [0249] 110 Roller in the drawing device [0250] 111 Roller in the drawing device [0251] 112 Roller in the drawing device [0252] 114 Texturing apparatus [0253] 115 Drawing device [0254] 116 Cooling device [0255] 117 Heating device [0256] 118 Drawing device [0257] 119 Monofilament yarn [0258] 120 Cooling godet [0259] 121 Roller for further processing the monofilament yarn [0260] 122 Textured (curled) monofilament yarn [0261] 123 Housing of the texturing apparatus [0262] 124 Inlet port (injector jet) for yarn ingress in the texturing apparatus [0263] 125 End portion of the yarn channel in the texturing apparatus [0264] 126 Yarn channel in the texturing apparatus [0265] 127 Channel for guiding fluid in the texturing apparatus [0266] 128 Temperature sensor in the channel for guiding fluid in the texturing apparatus [0267] 129 Heating device for the texturing apparatus [0268] 130 Inlet for fluid under pressure in the texturing apparatus [0269] 131 Temperature sensor for sensing the temperature of the fluid [0270] 133 Thread in the tubular end section of the housing for clamping [0271] 147 Expansion chamber in the texturing apparatus [0272] 148 Guide tube for textured yarn from the expansion chamber [0273] 149 Portion of the fluid in the expansion chamber [0274] 150 Heater for roller [0275] 151 Temperature sensor for roller [0276] 152 Controller for the heating device [0277] 153 Computer processor in the controller for the heating device [0278] 154 Memory in the controller for the heating device [0279] 155 Computer network for communicative coupling [0280] 156 Distance for yarn transportation from heater to texturing apparatus [0281] 158 Temperature sensor for the texturing apparatus [0282] 159 Conical shape in the inlet port [0283] 160 Screw for clamping mechanism [0284] 161 Gas pipe line for fluid [0285] 162 Controller for fluid temperature [0286] 163 Computer processor in the controller for fluid temperature [0287] 164 Memory in the controller for fluid temperature [0288] 165 Heating element for fluid [0289] 166 Compressor for fluid [0290] 167 Computer network for communicative coupling [0291] 169 Inner channel of the expansion chamber [0292] 170 Section of the expansion chamber with porous sidewall [0293] 171 Inlet of the expansion chamber [0294] 172 Downstream outlet of the expansion chamber [0295] 176 Channel for infeed of fluid into the yarn channel [0296] 177 Threaded bushing for regulating position in the housing [0297] 178 Channel for infeed of yarn into the yarn channel [0298] 181 Downstream outlet of the expansion chamber [0299] 182 Circular inlet opening of the expansion chamber [0300] 200 Finished artificial turf [0301] 202 Carrier or primary backing [0302] 204 Hot-texturized fibers [0303] 206 Low-temperature-texturized fibers [0304] 208 Non-texturized fibers [0305] 222-232 steps [0306] 302 Fibers extending from the carrier [0307] 304 Length of fibers extending from the carrier to the fiber tips [0308] 306 Series of tuft knots [0309] 308 Secondary backing [0310] 203 Unfinished artificial turf (greige good) [0311] 400 Polymer blend [0312] 402 first polymer [0313] 406 Compatibilizer [0314] 408 Second polymer [0315] 800 polymer mixture [0316] 602 plate [0317] 604 hole [0318] 606 monofilament [0319] 900 stretched monofilament [0320] 902 Second polymer in the monofilament yarn [0321] 904 Elongated beads of the first polymer [0322] 950 plot