NL1026239C2 - Method for manufacturing a plastic fiber for use in an artificial grass sports field as well as such a plastic fiber. - Google Patents

Description

Brief description: Method for manufacturing a synthetic fiber for use in an artificial grass sports field and a / · ·,; such plastic fiber.

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5 DESCRIPTION

The invention relates to a method for manufacturing a plastic fiber for use in an artificial grass sports field comprising the steps of i) supplying a layer of plastic material; and ii) obtaining the plastic fiber from the layer of plastic material.

The invention also relates to such a plastic fiber and to an artificial grass mat suitable for sports fields, consisting of a carrier on which plastic fibers according to the invention are arranged.

Plastics are currently being used for all kinds of different purposes and in particular the use of all kinds of plastics in artificial grass mats for sports fields has undergone strong development in recent years.

The research has focused in particular on the development of plastic fibers for use in artificial grass mats for sports pitches, wherein the fiber of a certain length is attached to a support, for example by tufting. The development of synthetic turf fibers and synthetic turf sports fields derived therefrom has now taken such a large flight that it is currently possible to construct artificial turf sports fields which are virtually indistinguishable from sports fields with natural grass in appearance but in particular in terms of playing behavior.

In contrast to natural grass sports fields, artificial grass sports fields can be played longer and more intensively regardless of the weather conditions. The development of new artificial grass fibers is currently mainly aimed at obtaining a fiber, which further reduces the occurrence of injuries, for example scrapes and burns during slidings or the twisting of joints.

Existing fibers, specifically developed for artificial grass sports fields, are obtained, for example, by means of a cutting operation from a foil of plastic material. The foil plastic material can for instance consist of a mixture of different plastics, one plastic serving to give the fiber a certain rigidity (against breaking or splitting), while another plastic in the mixture gives the fiber a certain elasticity or flexibility or better sliding. 10 features.

A drawback of such existing plastic fibers is the fact that, due to the homogeneous construction, all (sub) properties of the fiber are homogeneously incorporated into the fiber. As a result, certain properties of the fiber may be less prominent than desired, while other properties also dominate too much than is desirable. Therefore, the current fibers are often standardized in composition and also often unnecessarily expensive in terms of manufacturing and material costs.

The invention therefore has for its object to provide a more versatile fiber, which on the one hand can be produced for a specific application and on the other hand is cost-saving in terms of manufacture and material costs. According to the invention, the layer of plastic material is composed of at least two layers of different plastics by means of co-extrusion.

The co-extrusion step achieves a decoupling of the different properties of the plastics used. As a result, it is possible to build up a layered layer through the plastic fiber, to give each layer a function-specific property, which property does not have to be present elsewhere or in a greatly reduced extent elsewhere in the fiber. This offers the possibility of choosing the formulation of the fiber specifically for a specific application, which in addition to a more efficient use of material also results in plastic fiber with greatly improved play and fiber properties than in the homogeneously constructed, known fibers.

According to the invention, the play properties of the plastic fiber can be considerably improved by stretching the fiber after co-extruding. In addition to a length increase, according to the invention it is precisely because of the choice of material after stretching that a fiber with such strength properties is obtained in the transverse direction, as a result of which it for instance splits less quickly. When used in an artificial grass sports field, such a fiber and therefore the artificial grass mat has a much longer lifespan, the artificial grass mat requires much less maintenance and thus remains playable longer. The chance of injuries among players is also considerably reduced.

According to the invention, the fiber may consist of at least one or several, twisted monoflments. Optionally, the fiber is formed as a tape, and more specifically, the tape fiber is formed as a fibrillated tape fiber.

In a first functional embodiment of the method according to the invention, the layer of plastic material 20 is composed of a core layer of a first plastic, which core layer is surrounded on both sides by one or more outer layers, each consisting of a different plastic.

Thus, functional decoupling of the different properties of the different plastics can be achieved, each layer of plastic having a function-specific property that is not needed elsewhere in the fiber or is not functional elsewhere in the fiber.

The layers can herein have different thicknesses depending on the desired function-specific properties of the plastic fiber to be obtained.

In a first embodiment, the first plastic 1026239-1, 4 consists of a mixture of a polymer and a plastomer, wherein in particular the ratio of the plastomer in the core layer is 30-80% by weight and more particularly the ratio of the plastomer in the core layer is 35-50% by weight. This results in a fiber with a core layer that exhibits a very favorable non-splitting behavior in function-specific terms.

In another embodiment, at least one of the other plastics may comprise a hydrophilic additive. The artificial grass fiber thus obtained has the function-specific characteristic that the moisture (water) 10 can bind. As a result, the synthetic turf sports field in question remains moist for longer, which has a positive influence on playing behavior (slidings, etc.). When playing the field, the bound moisture is released, just like natural grass.

An example of a hydrophilic additive that can be used as the top or outer layer of the co-extrusion fiber is ethylene-vinyl-alcohol-copolymer. This polymer is capable of absorbing a lot of water depending on the amount of vinyl alcohol in the copolymer.

Another embodiment of a hydrophilic additive is the use of poly-hydroxy-ethyl methacrylate.

In yet another embodiment, at least one of the other plastics may comprise an anti-static additive. As a result, any static electricity generated when playing may flow off. Usually, the infill material between the fibers, which are used in many synthetic turf sports fields, is statically charged during playing and thereby migrates upwards into the field. Thus, by playing, the granular infill material can be spread through the air, which is less pleasant during the game.

The anti-static additive also ensures that no static discharges take place via the players.

More specifically, the anti-static additive can be a polymer, in particular a permanent antistatic, such as a polyamide or polyether block amide. In another embodiment, the additive is a polyester block copolymer.

j; The invention will be explained in more detail with reference to a drawing: explained, which drawing shows in: figures 1A-1D different embodiments of a plastic fiber according to the invention;

Figures 2A and 2B schematically show some embodiments of an artificial grass sports field provided with a plastic fiber obtained with the method according to the invention.

Figures 1A-1D disclose various embodiments of a plastic fiber according to the invention, as obtained by the method according to the invention.

The fibers (10, 20, 30, 40) are obtained from a foil plastic material, which foil is composed by means of co-extrusion of at least two layers of different plastics (11, 12) as shown in figure IA. In contrast to the currently known plastic fibers in which the fiber is composed of a homogeneous mixture of plastics, the layered structure of the plastic fiber (10, 20, 30, 40) according to the invention makes it possible to form any layer (here the partial layer). 11 and 12) give a function-specific property. This achieves that through the use of a plastic with a specific property in a certain part of the plastic fiber, this plastic and the associated function-specific property need not be present elsewhere in the fiber or to a greatly reduced extent.

For example, it is possible to use a plastic for the sublayer 11, which in principle gives the plastic fiber the mechanical strength (and stiffness) and in particular has such non-split properties, as a result of which the plastic fiber for the artificial grass sports field used does not play due to playing splits.

In another embodiment as shown in figure 1B

the plastic fiber 20 is made up of three layers of three different plastics indicated by the reference numerals 21, 22, 23. The middle layer 21 is made of an inexpensive plastic which must give the fiber 20 its mechanical strength, while the outer layers 22 and 23 can be made of different plastics, each having a different function-specific property, which property is best shown on the outside of the plastic fiber and not in the middle.

For example, the outer layers 21, 22 may have such an elastic property as opposed to the inner layer 21 which gives the fiber a certain stiffness (against breaking or splitting), which elastic property of the outer layer 21 or 22 has the effect of playing positively influenced the artificial grass sports field.

While in the embodiment in Figure 1B the outer layers 22 and 23 can be made of different plastics, Figure 1 shows an embodiment in which the outer layers 32A and 32B consist of the same plastic.

Figure 1D shows yet another more complex layered structure of a plastic fiber according to the invention. By co-extruding different plastics, a layered plastic fiber is obtained built up from a center core 41 and surrounded by different outer layers 42A-42B and 43A-43B, respectively.

The essence of the method according to the invention and the plastic fibers obtained therewith according to the invention lies in the fact that the plastic fiber, unlike the known plastic fibers, does not have a homogeneous structure in which all different plastics and the properties associated therewith are homogeneously incorporated in the fiber . Due to the homogeneous structure or composition of the existing artificial grass sports fibers, certain properties of the fiber may be less prominent than desired, while other properties now dominate too much than that is desired.

Using the method according to the invention 1026239-7, plastic fibers with a specific formulation can be obtained which, in contrast to the standardized fibers, exhibit a function-specific property for certain parts of the fiber that is not considered necessary or desirable elsewhere in the fiber.

As a result, the different materials / plastics can be used more efficiently, which not only has a cost-reducing effect, but moreover a more versatile plastic fiber according to the invention is obtained with considerably improved play and fiber properties than that with the homogeneously constructed known fibers. In this specific embodiment, the inner layer 11, 21, 31, 41 can be made of a cheaper plastic which in principle gives the fiber a certain strength against breaking or splitting. The outer layers 12, 22, 32, 32A-32B, 42A-42B and 43A-43B can be constructed from a plastic which does not necessarily have to be present in the core of the fiber.

A specific embodiment may in this case consist of an outer layer that is built up of an anti-static additive. The anti-static additive prevents the fiber from being charged by means of static electricity generated by playing the artificial grass sports field. In contrast to the anti-static additive, it now precisely ensures that the generated static electricity can flow away from the artificial grass sports field and does not discharge itself through, for example, the players, which can lead to unpleasant experiences.

In addition, a granular infill material is used in most synthetic turf sports fields (usually of a rubber-like material) which, due to the generated static electricity, migrates up into the artificial turf sports field and is spread through the air as a result of playing. The granular infill material flying through the air has a disruptive effect on the players.

The antistatic additive is in particular a permanent antistatic, and may be a polymer, such as a polyamide or polyether blockamide. In another embodiment, the additive is a polyester 1026239-8 block copolymer.

In another embodiment, one of the outer layers (or both outer layers) (12, 22-23, 32a-32b, 43a-43b) may comprise a ti (1 hydrophilic additive. The artificial grass fiber thus obtained has the following: 5 function-specific characteristic that the moisture (water) from the atmosphere can bind, such as for example rain.This means that the artificial grass sports field in question remains moist for a longer time, just like with a natural grass sports field, which has a positive influence on playing behavior, especially during slidings etc. playing on the field releases the bound moisture just like with 10 natural grass.

An example of a hydrophilic additive that can be used as the top or outer layer (12, 22-23, 32a-32b, 43a-43b) of the co-extrusion fiber is ethylene-vinyl-alcohol-copolymer. This polymer is capable of absorbing much water depending on the amount of vinyl alcohol in the copolymer.

The middle layer (11, 21, 31, 41) in this case gives the strength to the fiber while the relatively thin top layer (12, 22-23, 32a-32b, 43a-43b) absorbs water. This water can be bound from the air (in the form of rain, fog, etc.), but can also be supplied by an active sprinkler system. Synthetic turf sports fields are often sprayed shortly before playing.

During playing, the bound water is released again, reducing the risk of injury, for example during slidings. Moreover, the temperature of the field remains lower due to the absorbed water, since an artificial grass sports field can be heated by the sun, in unfavorable cases up to 70 ° C.

Another embodiment of a hydrophilic additive as an outer layer (12, 22-23, 32a-32b, 43a-43b) is using poly-hydroxy-ethyl methacrylate. To problem adhesion problems with the middle layer (11, 21, 31, 41), a five-layer co-extrusion configuration is required, as shown in Figure 1D. The layers 32a-42b are 1026239-9 adhesive layers for the hydrophilic layer 43a-43b on the middle layer 41.

For illustrative purposes, the different layers of the artificial grass fiber (as shown in Figures 1A-1D) are shown with different thicknesses. However, the thicknesses shown do not show any similarity with the actual thicknesses of the manufactured artificial grass fibers.

In the embodiment in Figure 1D, the adhesive layer 42a-42b is considerably thinner than shown, and is usually 1% -5% of the total fiber thickness, and the other layers 41-43a-43b are considerably thicker. When using polyethylene as the middle layer 11-21-31-41, ethylene-vinyl-alcohol-copolymer as a hydrophilic additive will adhere to the middle layer without filling adhesive layers.

Figures 2A and 2B show a few embodiments of an artificial grass sports field in which a plastic fiber according to the invention can be used. In the two figures, the artificial grass sports field is provided with a carrier 1, on which a plurality of synthetic fibers 2, as obtained on the basis of the method according to the invention, are provided at the reference point 3, for example by tufting. The plastic fiber 2 is obtained from a layer of plastic material, which material is composed of at least two different plastics by means of co-extrusion. The plastic fiber can be applied separately to the support or as a bundle of fibers 2a-2c, which are twisted into each other, for example. More in particular, the fiber obtained by co-extrusion can be a fibrillated tape fiber.

In another embodiment, as shown in Figure 2B

the plastic fiber according to the invention can be a monofilament. Here too, several monofilaments can be bundled by twisting, after which each bundle is applied to the support 1. In Fig. 2B, the carrier has an open structure and is composed of a grid of 30 support wires 1a-1b, on which the plastic fibers 2 are arranged.

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Claims (21)

A method for manufacturing a plastic fiber for I I; application in an artificial grass sports field comprising the steps of: i) supplying a layer of plastic material; and ii) obtaining the plastic fiber from the layer of plastic material, characterized in that the layer of plastic material is composed of at least two layers of different plastics by co-extrusion. Method according to claim 1, characterized in that the layer of plastic material is stretched after step i). Method according to claim 1, characterized in that the fiber is stretched after step ii). 4. Method according to one or more of claims 1-3, characterized in that the fiber consists of at least one monofilament. Method according to claim 4, characterized in that the fiber consists of several, twisted monofilaments. Method according to one or more of claims 1-3, characterized in that the fiber is shaped like a tape. The method according to claim 6, characterized in that the tape fiber is formed as a fibrillated tape fiber. 8. Method as claimed in one or more of the claims 1-7, characterized in that the layer of plastic material is composed of a core layer of a first plastic, which core layer is surrounded on both sides by one or more outer layers, each consisting of another plastic. The method according to claim 8, characterized in that the layers have different thicknesses. 10. Method according to one or more of the preceding claims, characterized in that the first plastic consists of a mixture of a polymer and a plastomer. 1026239- The method according to claim 10, characterized in that the ratio of the plastomer in the core layer is 30-80% by weight. A method according to claim 11, characterized in that the ratio of the plastomer in the core layer is 35-50% by weight. Method according to one or more of the preceding claims, characterized in that at least one of the other plastics comprises a hydrophilic additive. A method according to claim 13, characterized in that the hydrophilic additive is an ethylene-vinyl-alcohol-copolymer. Method according to claim 13, characterized in that the hydrophilic additive is a poly-hydroxy-ethyl methacrylate. Method according to one or more of the preceding claims, characterized in that at least one of the other plastics comprises an antistatic additive. A method according to claim 16, characterized in that the anti-static additive is a polymer, in particular a polyamide or polyether blockamide. Plastic fiber obtained by the method according to one or more of the preceding claims. 19. Artificial grass mat suitable for sports fields provided with plastic fibers according to one or more of the preceding claims. An artificial grass mat according to claim 19, characterized in that the mat comprises a carrier on which the plastic fibers are applied. 21. Synthetic turf according to claim 19 or 20, characterized in that a granulate material is interspersed between the synthetic fibers. 30 '1026239-