Description:

The application pertains to an artificial turf and to a process for manufacturing such an artificial turf.

Artificial turf is generally manufactured by tufting artificial turf fibers into a primary backing having a first surface and a second surface. Alternatively, artificial turf fibers may be (connected to a primary backing) by a weaving or a knitting process. The primary backing generally is a woven fabric, in particular a polypropylene woven fabric (but can also be produced of polyethylene, polyamide or polyester for example), or may be a combination of two (or more) woven fabrics, possibly further including a further layer, such as for example a reinforcement layer and/or a nonwoven layer of polypropylene staple fibers. The Artificial turf may include further layers, such as for example a secondary backing.

US 2019/0360160 A1 discloses a method for securing tufted filaments in a primary backing by melting particles into a discontinuous film and wherein the molten particles at least partially flow into the primary backing and into the loop backs of the tufted filaments.

US 2003/0044549 A1 discloses a base formed from particles of a thermosetting polymer compound mixed with a particle binding agent, wherein the base is tufted with a tufting material.

WO 2021/214229 A1 discloses an artificial turf comprising a damping layer made of a particle foam made of expanded beads.

The artificial turf fibers are generally composed of a thermoplastic polymer, and may for example be composed of a polyamide polymer, a polyester polymer or a polyolefin polymer, such as a polyethylene polymer or a polypropylene polymer, or a combination of different polymers combined in the turf or even combined within the same turf fiber. The polymers can be virgin polymers or polymers which are (partly or completely) recuperated via a recycling step.

The primary backing comprising the artificial turf fibers extending from a first surface of the primary backing is generally coated on the second surface of the primary backing with a styrene-butadiene latex (SBR latex). The styrene-butadiene latex is generally applied as an aqueous emulsion, which has to be dried to evaporate the water. Alternatively, a polyurethane (Pll) coating can be used to reduce energy consumption as there is no need to evaporate water.

At the end-of-life of artificial turf fields, often artificial turf fields are disposed into landfills or are fed into waste burning facilities. There is an increasing awareness that corporate social responsibility requires other solutions to be found for recycling or reusing artificial turf fields at their end-of-life.

For that the artificial turf industry is working hard to find such solutions. One solution is to manufacture artificial turf which is based on manufacturing artificial turf, which is composed of polymers of a single polymer family, for example composed of polyolefin polymers only, to simplify recycling.

Artificial turf comprising a SBR latex or a polyurethane coating, and artificial turf composed of polymers of a single polymer family or of polymers of different polymer families can for example be recycled into flower pots and other low-end applications.

A “single polymer family” artificial turf composed of polymers of a single polymer family may comprise artificial turf fibers composed of a polyethylene and/or a polypropylene polymer and a woven primary backing composed of a polypropylene polymer. On the second surface of the backing a polyolefin coating is applied. The polyolefin may be applied as a polyolefin dispersion, for example as available from the Dow Chemical Company under the tradename HYPOD 2000. Alternatively, for example, a polyolefin coating powder or a polyolefin film may be applied to the second surface of the backing and melted onto the second surface of the backing.

A polyolefin coating can be applied at a much lower weight as compared to a SBR latex or a Pll coating while providing sufficient tuft lock. The lower weight of the polyolefin coating aids in reducing the amount of plastics in the artificial turf end product and enables to limit the price increase associated with the application of the polyolefin dispersion to an acceptable level.

However, artificial turfs having such a polyolefin coating have the disadvantage that the artificial turf end product has a completely different feel and way of handling compared to artificial turf end products comprising a SBR latex or a Pll coating. An artificial turf comprising a polyolefin coating applied at such a much lower weight is sometimes observed to be more difficult to cut properly providing a clean cut as compared to artificial turf end products comprising a SBR latex or a Pll coating.

Also, the dimensional stability of artificial turf having such a polyolefin coating does not always fulfill the requirements for the intended use, in particular when the artificial turf is to be used in a sports field. When an infill is applied onto and/or into an artificial turf field comprising artificial turf comprising a polyolefin coating applied at such a much lower weight, the artificial turf may exhibit some undesired movement when transporting a relatively high weight of infill over the artificial turf field. When creating an artificial turf field comprising artificial turfs comprising a polyolefin coating applied at such a much lower weight it may sometimes require more efforts to properly align two artificial turfs adjacent to each other.

For artificial turf having such a polyolefin coating it is extremely difficult to provide sufficiently strong seams, as required for some sports applications, to connect different rolls of artificial turf to each other, as a polyolefin coating does not provide sufficient adhesion to a glue, such as a polyurethane glue, or a tape used to make such seams. Therefore, there is a need for an artificial turf which improves the ability to be recycled at the end-of-life while satisfying requirements for the intended use of the artificial turf.

There is a need to provide an artificial turf field which can be recycled at the end- of-life, which gives good stability, satisfying requirements for the intended use and comprising an artificial turf which can be connected to another roll of artificial turf by a sufficiently strong seam.

An object of the invention is to provide an artificial turf field which can be recycled at the end-of-life and which has sufficiently strong seams.

The object of the invention is achieved by the artificial turf field according to claim 1.

An artificial turf field comprising an artificial turf comprising primary backing comprising a nonwoven and/or a woven fabric and having a first surface and a second surface and artificial turf fibers connected to the primary backing, the artificial turf fibers extending from the first surface of the primary backing, and a material layer adhered to the second surface of the primary backing, wherein the material layer comprises particles composed for at least 75 wt.% of one or more polymers enables to improve the seam strength between two adjacent artificial turfs, preferably to a seam strength of at least 70 N/100 mm after ageing. When creating an artificial turf field multiple rolls of artificial turf are unrolled adjacent to each other and the artificial turfs are to be connected to each other by a seam. In a complete artificial turf field multiple seams will be present as generally a roll of artificial turf has a width of about 4 meters. The seam strength between two artificial turfs is determined in accordance with the FIFA Quality Programme - Handbook of Requirements for Football Turf version 3.1 of March 16 ^th 2020 - test method EN 13744 and EN 12228 method 2, wherein the seam strength after ageing is determined on artificial turf samples which have been immersed in water of 70°C for a period of two weeks. After removal of the samples containing the seams from the water, the artificial turf samples are allowed to cool to room temperature and then the seam strength is determined on the wet samples.

In an embodiment, the particles comprised in the material layer are composed for at least 75 wt.% of one or more thermoplastic polymers.

The artificial turf fibers can be connected to the primary backing by weaving, knitting or tufting. The process for manufacturing an artificial turf may comprise any one of these three processes. It is however preferred for production efficiency that the artificial turf fibers are connected to the primary backing by tufting.

The primary backing comprised in the artificial turf advantageously comprises a nonwoven and/or a woven fabric for providing sufficient dimensional stability. In an embodiment, the primary backing consists of one or more nonwovens and/or one or more woven fabrics.

For clarification, it is understood that the material layer adhered to the second surface of the primary backing is located below the artificial turf fibers extending from the first surface of the primary backing, as the primary backing is first tufted with artificial turf fibers and the material layer is applied after tufting.

The particles comprised in the material layer adhered to the second surface of the primary backing may have an average size in the range of 100 pm to 1500 pm, preferably in the range of 200 pm to 1000 pm, most preferably in the range of 250 pm to 750 pm.

In an embodiment, the particles have an average size less than 500 pm.

The particles comprised in the material layer adhered to the second surface of the primary backing of the artificial turf may be formed of any suitable polymer or combination of polymers, preferably of any suitable thermoplastic polymer or a combination of thermoplastic polymers, including one or more polyolefin polymers, such as polyethylene, polypropylene or copolymers thereof, one or more polyester polymers, such as polyethylene terephthalate, polybutylene terephthalate or copolymers thereof, and/or one or more polyamide polymers, such as polyamide- 6, polyamide 6,6 or copolymers thereof. Preferably, the particles comprised in the material layer adhered to the second surface of the primary backing of the artificial turf are formed of one or more polyolefin polymers, in particular polyethylene and/or polypropylene and/or copolymers thereof, i.e. copolymers of polyethylene and polypropylene. As is known to the skilled person, a polyolefin polymer is a polymer with the general formula (CH2-CH-R) _n wherein R is an alkyl group.

Although the particles comprised in the material layer may be formed of, or include, one or more virgin polymers, the particles are preferably formed of, or include, one or more waste polymers, more preferably formed by transforming a waste artificial turf into the particles.

In an embodiment, the particles comprised in the material layer are preferably formed by transforming a waste artificial turf into the particles, wherein the waste artificial turf is composed of one or more polymers of a single polymer family, for example of a polyolefin polymer family, of a polyester polymer family, or of a polyamide polymer family. Preferably, the particles comprised in the material layer are preferably formed by transforming a waste artificial turf into the particles, wherein the waste artificial turf is composed of one or more polymers of the polyolefin polymer family.

The term one or more polymers of a single polymer family is understood to mean that monomers comprised in each of the one or more polymers are connected by the same type of chemical bond, as is known to the person skilled in the art. For example, when in a polymer two monomers are connected by an ester unit, i.e. an ester-bond, and in another polymer two monomers are connected by an ester- bond, then these polymers are one or more polymers of the polyester polymer family. When, for example, in a polymer two monomers are connected by an amide unit, i.e. an amide-bond, and in another polymer two monomers are connected by an amide-bond, then these polymers are one or more polymers of the polyamide polymer family. Preferably, at least 50% of the chemical bonds between monomers in each of the one or more polymers are the same chemical bonds. More preferably, at least 75% of the chemical bonds between monomers in each of the one or more polymers are the same chemical bonds. More preferably, at least 90% of the chemical bonds between monomers in each of the one or more polymers are the same chemical bonds. Even more preferably, at least 95% of the chemical bonds between monomers in each of the one or more polymers are the same chemical bonds. Most preferably, at least 98% of the chemical bonds between monomers in each of the one or more polymers are the same chemical bonds.

The material layer adhered to the second surface of the primary backing comprises particles composed for at least 75 wt.% of one or more polymers, preferably of one or more thermoplastic polymers. However, the material layer adhered to the second surface of the primary backing preferably comprises particles composed for at least 90 wt.% of one or more polymers, more preferably composed for at least 95 wt.% of one or more polymers, preferably of one or more thermoplastic polymers.

In an embodiment, the material layer adhered to the second surface of the primary backing comprises particles consisting of one or more polymers, preferably of one or more thermoplastic polymers.

Although the particles comprised in the material layer adhered to the second surface of the primary backing are preferably composed of one or more polymers to a percentage as high as possible, the particles may comprise up to 25 wt.%, preferably up to 10 wt.%, more preferably up to 5 wt.% based on the total weight of the particles, of commonly used additives, such as for example flame retardant materials, UV inhibitors, heat stabilizers, antimicrobial additives, antistatic agents, colouring agents or any combination thereof. The particles may also contain some contaminants, in particular when the particles are formed of, or include, one or more waste polymers, more preferably formed by transforming a waste artificial turf into the particles, provided that the particles are composed for at least 75 wt.% of one or more polymers, preferably one or more thermoplastic polymers.

The material layer adhered to the second surface of the primary backing comprising the particles may be composed for at least 75 wt.% of one or more polymers, preferably one or more thermoplastic polymers, based on the total weight of the material. However, the material layer comprising the particles is preferably composed for at least 90 wt.% of one or more polymers, more preferably composed for at least 95 wt.% of one or more polymers, preferably one or more thermoplastic polymers.

In an embodiment, the material layer adhered to the second surface of the primary backing comprising the particles consists of one or more polymers, preferably one or more thermoplastic polymers.

The material layer adhered to the second surface of the primary backing preferably comprises the particles in a matrix material, the matrix material preferably being composed of one or more polyolefin polymers, in particular when the particles comprised in the material layer adhered to the second surface of the primary backing are formed of one or more polyolefin polymers, in particular polyethylene and/or polypropylene and/or copolymers thereof, i.e. copolymers of polyethylene and polypropylene.

Preferably, the material layer adhered to the second surface of the primary backing comprises the particles in a matrix material, wherein the particles are homogeneously distributed in the matrix material.

The particles comprised in the material layer adhered to the second surface of the primary backing preferably have not been molten, i.e. the particles have not been subjected to a temperature and/or a pressure at which the particles would melt. The material layer comprising the particles does not comprise a particle foam or particles made of an expanded polymer. The particles comprised in the material layer are preferably solid particles.

Preferably, in the artificial turf, each of the primary backing, the artificial turf fibers and the material layer is composed for at least 75 wt.% of one or more polymers of the same polymer family, preferably for at least 90 wt.%, more preferably for at least 95 wt.% of one or more polymers of the same polymer family, such as of the polyolefin polymer family, of the polyester polymer family, or of the polyamide polymer family, preferably of one or more polymers of the polyolefin family.

In an embodiment, in the artificial turf, each of the primary backing, the artificial turf fibers and the material layer consists of one or more polymers of the same polymer family, such as of the polyolefin polymer family, of the polyester polymer family, or of the polyamide polymer family, preferably of one or more polymers of the polyolefin family.

Preferably, the artificial turf is composed for at least 75 wt.% of one or more polymers of the same polymer family, preferably for at least 90 wt.%, more preferably for at least 95 wt.% of one or more polymers of the same polymer family, such as of the polyolefin polymer family, of the polyester polymer family, or of the polyamide polymer family, preferably of one or more polymers of the polyolefin family.

In an embodiment, the artificial turf consists of one or more polymers of the same polymer family, such as of the polyolefin polymer family, of the polyester polymer family, or of the polyamide polymer family, preferably of one or more polymers of the polyolefin family.

The material layer adhered to the second surface of the primary backing may comprising the particles in an amount in the range of 100 g/m ² to 1000 g/m ² , preferably in the range of 150 g/m ² to 750 g/m ² , more preferably in the range of 200 g/m ² to 500 g/m ² , to further increase the seam strength. The material layer adhered to the second surface of the primary backing including the particles may have a weight in the range of 150 g/m ² to 1300 g/m ² , preferably in the range of 200 g/m ² to 900 g/m ² , more preferably in the range of 250 g/m ² to 700 g/m ² , based on the dry weight of the material layer, to enable that the artificial turf has a similar look and feel as prior art artificial turf and/or to enable that the artificial turf has a good dimensional stability. Furthermore, the material layer adhered to the second surface of the primary backing having such a weight enables to provide an improved cut, facilitates more efficient application of infill, and/or enables easier alignment two artificial turfs adjacent to each other due to reduced warping of the artificial turf upon unrolling a roll of the artificial turf.

The material layer adhered to the second surface of the primary backing may comprise the particles in a matrix material, wherein the particles are preferably homogeneously distributed in the matrix material. Preferably, the matrix material forms a continuous phase in the material layer adhered to the second surface of the primary backing.

The material layer adhered to the second surface of the primary backing may comprise the particles in a weight ratio to the matrix material of at least 40/60, preferably at least 50/50, more preferably at least 60/40, even more preferably at least 70/30, most preferably at least 80/20, based on the dry weight of the material layer.

The artificial turf may have a dimensional stability in the range of -0.5% to 0.5%, as determined in accordance with EN13746 (2004), wherein a sample of 40 cm x 40 cm is cut out. After 48 hours of conditioning at 23°C ⁺ /- 2°C and 50 ⁺ /- 5% RH the dimensions of the sample are measured (original dimensions). The sample is subsequently subjected to the following treatments: for 24 hours in water, for 24 hours in a freezer at -18°C, for 72 hours in an oven at 70°C, and for 48 hours at conditioning at 23°C ⁺ /- 2°C and 50 ⁺ /- 5% RH. The dimensions of the sample are measured after each treatment. The dimensions of the artificial turf may deviate from the original dimensions in the range of -0.5% to 0.5% after each of the treatments. Preferably, the artificial turf has a dimensional stability in the range of -0.4% to 0.4%, more preferably in the range of -0.3% to 0.3%, most preferably in the range of -0.2% to 0.2%.

The material layer adhered to the second surface of the primary backing including the particles may have a thickness in the range of 1 mm to 9 mm, preferably in the range of 1.25 mm to 7.5 mm, more preferably in the range of 1.5 mm to 5 mm, most preferably in the range of 2 mm to 3 mm, which can be determined using a caliper.

An artificial turf field comprising one or more artificial turf rolls according to any of the embodiments described above can be provided with sufficiently strong seams of at least 70 N after ageing.

The artificial turf field may comprise any of the artificial turf described above.

Preferably, the artificial turf field comprises at least two of any of the artificial turfs described above, which are preferably connected to each other by one or more seams, preferably having a seam strength of at least 70 N after ageing.

An object of the invention is to provide a process for manufacturing an artificial turf field which can be recycled at the end-of-life and which can be connected to another roll of artificial turf by a sufficiently strong seam.

The object of the invention is achieved by the process for manufacturing an artificial turf field according to claim 10.

A process for manufacturing an artificial turf comprising the steps of providing a primary backing comprising a nonwoven and/or a woven fabric, having a first surface and a second surface and having artificial turf fibers connected to the primary backing, the artificial turf fibers extending from the first surface of the primary backing, and adhering a material layer to the second surface of the primary backing, wherein the material layer comprises particles composed for at least 75 wt.% of one or more polymers enables to improve the seam strength between two adjacent artificial turfs, preferably to a seam strength of at least 70 N after ageing.

The process may include the step of aligning two artificial turfs adjacent to each other. The process may include the step of connecting at least two artificial turfs by one or more seams, the seams preferably having a seam strength of at least 70 N after ageing.

In the process, the particles comprised in the material layer being adhered to the second surface of the primary backing may have an average size in the range of 100 pm to 1500 pm, preferably in the range of 200 pm to 1000 pm, most preferably in the range of 250 pm to 750 pm.

In an embodiment, the particles have an average size less than 500 pm.

In the process, the particles comprised in the material layer being adhered to the second surface of the primary backing of the artificial turf may be formed of any suitable polymer or combination of polymers, preferably of any suitable thermoplastic polymer or a combination of thermoplastic polymers, including one or more polyolefin polymers, such as polyethylene, polypropylene or copolymers thereof, one or more polyester polymers, such as polyethylene terephthalate, polybutylene terephthalate or copolymers thereof, and/or one or more polyamide polymers, such as polyam ide-6, polyamide 6,6 or copolymers thereof. Preferably, the particles comprised in the material layer adhered to the second surface of the primary backing of the artificial turf are formed of one or more polyolefin polymers, in particular polyethylene and/or polypropylene and/or copolymers thereof, i.e. copolymers of polyethylene and polypropylene.

Although the particles comprised in the material layer being adhered to the second surface of the primary backing of the artificial turf may be formed of, or include, one or more virgin polymers, the particles are preferably formed of, or include, one or more waste polymers, more preferably formed by transforming a waste artificial turf into the particles. In an embodiment of the process, the particles comprised in the material layer being adhered to the second surface of the primary backing of the artificial turf are preferably formed by transforming a waste artificial turf into the particles, wherein the waste artificial turf is composed of one or more polymers of a single polymer family, for example of a polyolefin polymer family, of a polyester polymer family, or of a polyamide polymer family. Preferably, the particles comprised in the material layer are preferably formed by transforming a waste artificial turf into the particles, wherein the waste artificial turf is composed of one or more polymers of the polyolefin polymer family.

In an embodiment of the process, the material layer being adhered to the second surface of the primary backing comprises particles composed for at least 75 wt.% of one or more polymers, preferably of one or more thermoplastic polymers. However, the material layer being adhered to the second surface of the primary backing preferably comprises particles composed for at least 90 wt.% of one or more polymers, more preferably composed for at least 95 wt.% of one or more polymers, preferably of one or more thermoplastic polymers.

In an embodiment of the process, the material layer being adhered to the second surface of the primary backing comprises particles consisting of one or more polymers, preferably of one or more thermoplastic polymers.

Although, in the process the particles comprised in the material layer being adhered to the second surface of the primary backing are preferably composed of one or more polymers to a percentage as high as possible, the particles may comprise up to 25 wt.%, preferably up to 10 wt.%, more preferably up to 5 wt.% based on the total weight of the particles, of commonly used additives, such as for example flame retardant materials, UV inhibitors, heat stabilizers, antimicrobial additives, antistatic agents, colouring agents or any combination thereof. The particles may also contain some contaminants, in particular when the particles are being formed of, or include, one or more waste polymers, more preferably being formed by transforming a waste artificial turf into the particles, provided that the particles are composed for at least 75 wt.% of one or more polymers, preferably of one or more thermoplastic polymers.

In an embodiment of the process, the material layer being adhered to the second surface of the primary backing comprising the particles may be composed for at least 75 wt.% of one or more polymers, preferably of one or more thermoplastic polymers based on the total weight of the material. However, the material layer comprising the particles is preferably composed for at least 90 wt.% of one or more polymers, more preferably composed for at least 95 wt.% of one or more polymers, preferably of one or more thermoplastic polymers.

In an embodiment, the material layer being adhered to the second surface of the primary backing comprising the particles consists of one or more polymers, preferably of one or more thermoplastic polymers.

In an embodiment of the process, the material layer being adhered to the second surface of the primary backing comprises the particles in a matrix material, the matrix material preferably being composed of one or more polyolefin polymers, in particular when the particles comprised in the material layer being adhered to the second surface of the primary backing are being formed of one or more polyolefin polymers, in particular polyethylene and/or polypropylene and/or copolymers thereof, i.e. copolymers of polyethylene and polypropylene.

Preferably, the material layer being adhered to the second surface of the primary backing comprises the particles in a matrix material, wherein the particles are being homogeneously distributed in the matrix material.

Preferably, the process comprises the step of mixing the particles into a polyolefin dispersion.

In an embodiment of the process, each of the primary backing, the artificial turf fibers and the material layer is composed for at least 75 wt.% of one or more polymers of the same polymer family, preferably for at least 90 wt.%, more preferably for at least 95 wt.% of one or more polymers of the same polymer family, such as of the polyolefin polymer family, of the polyester polymer family, or of the polyamide polymer family, preferably of one or more polymers of the polyolefin family.

In an embodiment of the process, each of the primary backing, the artificial turf fibers and the material layer consists of one or more polymers of the same polymer family, such as of the polyolefin polymer family, of the polyester polymer family, or of the polyamide polymer family, preferably of one or more polymers of the polyolefin family.

In an embodiment of the process, the artificial turf is composed for at least 75 wt.% of one or more polymers of the same polymer family, preferably for at least 90 wt.%, more preferably for at least 95 wt.% of one or more polymers of the same polymer family, such as of the polyolefin polymer family, of the polyester polymer family, or of the polyamide polymer family, preferably of one or more polymers of the polyolefin family.

In an embodiment of the process, the artificial turf consists of one or more polymers of the same polymer family, such as of the polyolefin polymer family, of the polyester polymer family, or of the polyamide polymer family, preferably of one or more polymers of the polyolefin family.

In an embodiment of the process, the material layer being adhered to the second surface of the primary backing comprises the particles in an amount in the range of 100 g/m ² to 1000 g/m ² , preferably in the range of 150 g/m ² to 750 g/m ² , more preferably in the range of 200 g/m ² to 500 g/m ² , to further increase the seam strength.

In an embodiment of the process, the material layer being adhered to the second surface of the primary backing including the particles may have a weight in the range of 150 g/m ² to 1300 g/m ² , preferably in the range of 200 g/m ² to 900 g/m ² , more preferably in the range of 250 g/m ² to 700 g/m ² , based on the dry weight of the material layer, to enable that the artificial turf has a similar look and feel as prior art artificial turf and/or to enable that the artificial turf has a good dimensional stability. The artificial turf may have a dimensional stability in the range of -0.5% to 0.5%, preferably in the range of -0.4% to 0.4%, more preferably in the range of -0.3% to 0.3%, most preferably in the range of -0.2% to 0.2%.

In an embodiment of the process, the material layer being adhered to the second surface of the primary backing including the particles may have a thickness in the range of 1 mm to 9 mm, preferably in the range of 1 .25 mm to 7.5 mm, more preferably in the range of 1.5 mm to 5 mm most preferably in the range of 2 mm to 3 mm.

In an embodiment of the process, the process excludes a step wherein the particles comprised in the material layer being adhered to the second surface of the primary backing would have been molten, i.e. the particles are not being subjected to a temperature and/or a pressure at which the particles melt.

In an embodiment of the process, the process excludes a step of providing a particle foam or particles made of an expanded polymer.