Search

EP-4741546-A1 - HELICAL ARTIFICIAL TURF FIBER WITH ANTI-SPLICING AGENT

EP4741546A1EP 4741546 A1EP4741546 A1EP 4741546A1EP-4741546-A1

Abstract

Disclosed is a helical artificial turf fiber comprising an anti-splicing agent.

Inventors

  • Dr. SICK, Stephan
  • Dr. GROCHLA, Dario

Assignees

  • Polytex Sportbeläge Produktions-GmbH

Dates

Publication Date
20260513
Application Date
20241107

Claims (20)

  1. An artificial turf fiber (204, 502-510, 804, 902-906, 1500, 1602-1618) comprising an anti-splicing agent, the artificial turf fiber being under internal stress that causes the artificial turf fiber, upon receiving heat treatment, to assume a helical shape.
  2. A helical artificial turf fiber, comprising an anti-splicing agent.
  3. The artificial turf fiber of any one of the previous claims, wherein the helical artificial turf fiber has a 3D-helical shape characterized in that the fiber winds around a central cylinder, wherein the fiber maintains a distance from the cylinder axis as it rotates, and advances along the axis, resulting in a three-dimensional spiral curve.
  4. The artificial turf fiber of any one of the preceding claims, wherein the helical artificial turf fiber is a twisted fiber that is rotated around its own axis.
  5. The artificial turf fiber according to any one of the preceding claims, wherein the anti-splicing agent is or comprises a compatibilizer.
  6. The artificial turf fiber according to claim 5, wherein the compatibilizer is selected from a group comprising: an anhydride modified polyethylene, a maleic acid grafted on polyethylene or polyamide; a maleic anhydride grafted on free radical initiated graft copolymer of polyethylene, SEBS, EVA, EPD, or polypropylene with an unsaturated acid or it's an- hydride 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; Ethylene Ethyl Acrylate (EEA), Maleic Acide Anhydride grafted PE, a graft copolymer of polypropylene with maleic anhydride; a polyolefin-graftpolyamidepolyethylene or polyamide; and a polyacrylic acid type compatibilizer; and a combination of two or more of the aforementioned substances, wherein the compatibilizer is in particular Ethylene Ethyl Acrylate (EEA) or Maleic Acide Anhydride grafted PE.
  7. The artificial turf of claim 5 or 6, the fiber comprising the compatibilizer in an amount of 0.5- 5.0 weight %, in particular 0.5- 2.0 weight %, wherein in particular the compatibilizer is EEA or Maleic Acid Anhydride grafted PE.
  8. The artificial turf fiber according to any of the preceding claims, wherein the anti-splicing agent is or comprises a low-density polyethylene - LDPE.
  9. The artificial turf fiber according to claim 8, wherein the fiber comprises the LDPE polymer in an amount of 0.1-15 % by weight of the fiber, in particular in an amount of 5-8 % by weight of the fiber.
  10. The artificial turf fiber of any one of the preceding claims, wherein the artificial turf fiber has a longitudinal cross-sectional profile, in particular a cross-sectional profile with a central bulb and two wings extending in different directions.
  11. The artificial turf fiber according to any one of the preceding claims, wherein the fiber comprises a different polymer material at its core compared to its peripheral regions, wherein the polymer materials are selected such that the polymer material at the core exhibits greater shrinkage than the polymer material in the peripheral regions in response to heat treatment.
  12. The artificial turf fiber according to any one of the preceding claims, comprising: - 0.1-15%, in particular 5.0-8.0% by weight of low-density polyethylene (LDPE), and - optionally 0.1-15% by weight HDPE; and - 60-99% by weight of linear low-density polyethylene (LLDPE).
  13. The artificial turf fiber according to any one of the preceding claims, wherein at least 60% by weight of the fiber, preferably at least 75% by weight of the fiber, comprises one or more polymers having a density in the range of 0.910 to 0.928 g/cm 3 , more preferably in the range of 0.913 to 0.925 g/cm 3 .
  14. The artificial turf fiber according to any one of the preceding claims, wherein the fiber comprises an hydrophilization agent, in particular hydrophilic fumed silica.
  15. The artificial turf fiber according to any one of the preceding claims, wherein the fiber comprises a nucleating agent, wherein the nucleating agent is in particular an inorganic substance selected from a group comprising: - talcum; - kaolin; - calcium carbonate; - magnesium carbonate; - silicate; - silicic acid; - silicic acid ester; - aluminium trihydrate; - magnesium hydroxide; - meta- and/or polyphosphates; and - coal fly ash; - fumed silica; and/or wherein the nucleating agent is in particular an organic substance selected from a group comprising: - 1,2-cyclohexane dicarbonic acid salt; - benzoic acid; - benzoic acid salt; - sorbic acid; and - sorbic acid salt.
  16. An artificial turf, comprising: - a carrier - a plurality of helical artificial turf fibers according to any one of the previous claims 2-15, wherein the fibers are integrated into the carrier and extend to one side of the carrier.
  17. The artificial turf according to claim 16, - wherein the helical artificial turf fibers are texturized fibers, - wherein the artificial turf further comprises non-texturized fibers, wherein in particular the non-texturized fibers have approximately the same length or a larger length than the helical, texturized fibers.
  18. The artificial turf according to claim 16 or 17, further comprising: - an infill layer, - wherein the number of twists per fiber and the height of the infill is chosen such that in at least 80% of the helical fibers, the part of the helical fibers that protrudes above the infill layer makes at least 1.0 turns.
  19. A method for manufacturing an artificial turf fiber that is under internal stress, the method comprising: - creating (102) a polymer mixture, the mixture comprising an anti-splicing agent; - extruding (104) the polymer mixture into a monofilament; - quenching (106) the monofilament; - controlling (108) equipment for processing the monofilament such that a temperature gradient is formed reproducibly in the cross-section of the monofilament; - stretching (110) the monofilament while the temperature gradient is present to form the monofilament into the artificial turf fiber, thereby introducing the internal stress into the fiber, wherein the internal stress is adapted to cause the artificial turf fiber, upon receiving heat treatment, to assume a helical shape.
  20. A method for manufacturing a helical artificial turf fiber, comprising: - executing the method of claim 19; and - heating (112) the monofilament, thereby causing the artificial turf fiber change its 3D shape to form a helical artificial turf fiber.

Description

FIELD OF THE INVENTION The invention relates to the field of artificial turf, and methods of manufacturing the same. BACKGROUND Artificial turf is a surface made of synthetic fibers designed to resemble natural grass. It is commonly used in sports fields, residential lawns, and commercial landscaping, offering low maintenance, durability, and the ability to withstand heavy use and varying weather conditions. Helical artificial turf fibers offer several advantages over straight fibers in terms of durability, aesthetics, and performance: The helical structure allows the fibers to spring back more easily after being compressed, making the turf more durable in places where there is frequent foot traffic, such as sports fields or playgrounds. This resilience is critical for maintaining the appearance and functionality of artificial turf over time, as straight fibers are more likely to flatten or break down under constant pressure. Furthermore, the helical design gives artificial turf a more natural look and feel, mimicking the way natural grass blades appear at different angles. Straight fibers tend to reflect more sunlight, creating an unnatural shiny appearance. Helical fibers help diffuse light, reducing glare and providing a more matte finish, which enhances the natural look of the turf. The helical nature of these fibers also provides better grip and traction. This can be particularly important for sports fields, where players need a stable surface to run and play without slipping. The Korean patent KR102535359B1 describes a method of manufacturing spiral or spring-shaped artificial turf yarn. US patent US 10,760,225 B2 1 describes a system for manufacturing helix-shaped artificial turf filaments, wherein the system comprises a first and a second air drawn oven downstream of an extrusion spinneret consecutively heat artificial turf filaments to a first and then a second temperature, wherein the second temperature is higher than the first temperature. SUMMARY OF THE INVENTION It is an objective to provide for an improved helical artificial turf fiber and for a method of manufacturing the same. The objectives underlying the invention are solved by the features of the independent claims. Embodiments of the invention can freely be combined with each other unless they are mutually exclusive. In one aspect, the invention relates to an artificial turf fiber comprising an anti-splicing agent. The artificial turf fiber is under internal stress that causes the artificial turf fiber, upon receiving heat treatment, to assume a helical shape. The internal stress may be introduced, for example, during the post-processing of the artificial turf fiber after extrusion, such as by stretching and/or compressing the fiber while a temperature gradient is present in the fiber's cross-section. For example, this type of fiber may be sold as intermediary product on the market and may allow manufacturers of artificial turf to trigger the formation of the helical shape simply by heat-treating these fibers. For example, the heat-treatment step can be a step of applying a liquid backing, e.g., a liquid latex or polyurethane reaction mixture, onto a greige good (i.e., a carrier into which the artificial turf fibers have been integrated e.g. via tufting or weaving or knitting) and heating the greige good with the liquid backing in an oven to solidify or cure the liquid backing. This heating step in the oven may in addition trigger the formation of the helical shape which has been invisibly structurally imprinted in the material of the fiber e.g. by creating a temperature gradient in the fiber cross section and applying mechanical forces (stretching and/or compressing the fiber) while the temperature gradient is present. The internal stress may be tensile and/or compressive stress and may be manifested in the fiber material in the form of stress fields. The internal stress may also be referred to as material-immanent stress, because it is also present when no external force is currently exerted on the material. In a further aspect, the invention relates to a helical artificial turf fiber, comprising an anti-splicing agent. For example, this helical fiber may be the product of applying a heat treatment step on the above-mentioned fiber. An example for this would be the step of heating a liquid backing in an oven in order to solidify the backing. For example, the heat treatment may comprise heating the artificial turf fiber (or the artificial turf or greige good comprising the same) to 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. Applicant has observed that helical fibers typically have a higher risk of splicing, i.e., splitting in longitudinal direction, over time compared to straight fibers. The process of introducing stress into the material for ultimately manufacturing a helical fiber may comprise introducing tensile and/or compressive stress within the