Classifications

• • E—FIXED CONSTRUCTIONS
  • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
  • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
  • E01C13/00—Pavings or foundations specially adapted for playgrounds or sports grounds; Drainage, irrigation or heating of sports grounds
  • E01C13/08—Surfaces simulating grass ; Grass-grown sports grounds

Definitions

• the present invention relates to an artificial turf structure comprising a backing sheet with an upper surface provided with synthetic fibres of a selected length, the fibres extending upwardly from the upper surface and an infill layer of a particulate material disposed between the fibres
• the present invention further relates to the use of a granulate having a defined shape as infill material in an artificial turf structure.
• Artificial turf structures made of synthetic fibres connected to a backing sheet and infill material dispersed between the fibres is for example known from EP-A-1389649.
• infill layer a granular material is disclosed with a grain size smaller than 5 mm.
• a disadvantage of this turf structure is that the granules compact together and are sticking together after several months.
• Other prior art artificial turf structures comprising e.g.
• rubber and sand infill also are not able to provide permanent good long term properties because of compaction of undefined shaped rubber particles and sand infill material, which results in a decrease of shock absorption and vertical deformation and an increase of the traction and vertical ball bounce.
• the problem of compaction is for example disclosed in WO-A-0198589, which describes an artificial turf structure based on a multilayer infill composition comprising a base layer of a mixture of hard and resilient granules and a top layer of exclusively resilient granules.
• the resilient granules are preferably crumb rubber particles having several grain sizes between 0.5-2.00 mm.
• the granules are substantially spherical and defined in terms of the Krumbein standard with a sphericity in the range of 0.5-0.99 to prevent compaction and to improve drainage.
• This multilayer infill has the disadvantage that it comprises at least two layers thereby making the construction of the artificial turf structure uneconomical. Despite the construction a further disadvantage is that the desired level of properties as for example shock absorption, vertical deformation, traction and vertical ball rebound is not reached and that the artificial turf structure still not provides the performance of natural turf.
• the object of the present invention is to overcome the above stated drawbacks and to provide an artificial turf structure, which reproduces the characteristics of a natural turf system for football or rugby, as required in respectively the FIFA 2 star (1 July 2004) and IRB regulations (April 2004) on artificial turf and which provides permanent good long term properties.
• the artificial turf structure comprises as particulate material a granulate having a cylindrical shape with a length/diameter (UD) ratio between 0.8-1.2 and having a substantially uniform particle size.
• UD length/diameter
• the uniform size and shape of the infill granules significantly affect the turf performance characteristics such as shock absorption, vertical deformation, vertical ball bounce and traction.
• an artificial turf structure comprising a granulate with a specified particle shape and size as infill material, that reproduces as faithfully as possible the characteristics of a natural turf system as applied for football or rugby. Even on the long term these characteristics are still fulfilling the FIFA two star requirements on shock absorption, vertical deformation, vertical ball bounce and traction.
• the artificial turf structure of the present invention fulfils the FIFA two star requirements and IRB requirements on shock absorption, vertical deformation, vertical ball bounce and traction imposed for an artificial turf system. These standards reproduce the characteristics of natural turf football or rugby.
• the artificial turf structure according to the present invention complies with the required specifications for shock absorption, vertical deformation, traction and vertical ball bounce. Moreover these properties still comply with the required specifications on the long term, which is proved by testing the turf system after 5000 cycles on a lisport test.
• the Lisport test is a standard procedure within the requirements of FIFA and the IRB.
• Good long term properties may be further supported by ageing tests of the infill granulates itself, which show no change in intrinsic material properties after oxidation and UV-resistance tests.
• a further advantage of the artificial turf structure according to the present invention is that no other infill or shock-absorbing layer such as an e-layer or lava-rubber mixture is required as a sub-base.
• Still another advantage of the present invention is that the specific choice of particulate infill granulates include an excellent behaviour in an artificial turf structure when slidings are performed during a football game.
• Another advantage of the present invention is that the particulate infill granules do not form dust after 5000 cycles on a Lisport test.
• the granules have a length/diameter (L/D) ratio between 0.8-1.2, preferably a L/D ratio between 0.9-1.1 and more preferably a L/D ratio about equal to 1.
• the L/D ratio is a typical indication for cylindrical shaped particles.
• the length and the diameter are defined as can be seen in figure 1.
• the unique characteristic of the shape and the uniform size of the granules of the present invention is that the granules are immediately searching for a packed structure. This packed structure is reached directly after installation and is stable during time because it cannot compact more than this. However, the particles are loose enough to move under influence of force. This results in a structure of the infill layer, which is responsible for a natural turf character.
• the extend to which a structure is packed can be expressed in terms of its relative density PR, being defined as the ratio of the bulk density (p ⁇ ) of the granulate and the specific density of the granulate (p s ).
• the relative density of the granulate is at least 0.5, more preferably at least 0.55 and most preferably at least 0.60.
• the bulk density of the granules measured in accordance with NEN-ISO 60 (1978) is generally between 0.5 and 1 , for materials with specific gravities of betweeni and 1.5 kg/dm 3 .
• the particle size of the granules is for example between 1 and 4 mm. Preferably betweeni and 2.5 mm. More preferably between 1.2 and 2.2 mm. Even more preferably the particle size is between 1.5 and 2.1 mm. Most preferably the particle size is between 1.6 and 2.1 mm. It has been found that the particle size below 1mm has a negative influence on the drainage. A particle size above4 mm has a negative influence on the homogeneous distribution of the granules between the fibers.
• the particle size of the granules is substantial uniform.
• a substantial uniform particle size is understood to be a particle length L having a relative standard deviation ( ⁇ L/L) of less than 0.5, preferably less than 0.3, more preferably less than 0.15, wherein ⁇ L is the standard deviation of the length L.
• the granules are for example manufactured of plastomers, vinyl based polymers, polyolefin based polymers, reactor TPO's, thermoplastic elastomers or dynamically vulcanised thermoplastic elastomers.
• the granules are manufactured from a vinyl based polymer, a thermoplastic elastomer or a plastomer or mixtures thereof.
• Examples of plastomers are ethylene/alpha-olefin copolymers with a density of less than about 0.93 g/cm 3 at a molecular weight (Mw) greater than about 20.000.
• Examples of ethylene/alpha-olefin copolymers include ethylene/1 -butene, ethylene/1 -pentene, ethylene/1 -hexene, ethylene/1 -octene, and ethylene/2- norbornene.
• Commercially available copolymers are for example EXACTTM or ENGAGETM.
• vinyl-based polymers examples include styrene-isobutylene-styrene (SIBS), styrene-isobutylene (SIB), styrene-ethylene-butylenes-styrene polymers (SEBS) or styrene-butadiene-styrene polymers abbreviated as (SBS) or ethylene vinyl acetate (EVA).
• SEBS is used as vinyl based polymer.
• polyolefin-based polymers are polyethylene, polypropylene or metallocene polymerised polyolefinics. Reactor TPO's are commercially available for example under the trade name Hifax®.
• thermoplastic elastomers are polyurethanes or polyethersters or polymers comprising a thermoplastic and a rubber.
• the thermoplastic may be chosen from polyethylene or polypropylene homo-or copolymers and polyisobutylene.
• the rubber may be chosen from ethylene-propylene copolymers, hereinafter called EPM, ethylene-propylene-diene terpolymers, hereinafter called EPDM, natural rubbers, styrene-butadiene rubber (SBR), nitrile-butadiene rubbers (NBR), polyisoprene, butyl rubber or halogenated butyl rubber.
• the rubber may be dynamically vulcanised by the use of a cross linking agent such as sulphur, sulphurous compounds, metal oxides, maleimides, siloxane compounds for example hydrosilane or vinylalkoxysilane, phenol resins or peroxides.
• a cross linking agent such as sulphur, sulphurous compounds, metal oxides, maleimides, siloxane compounds for example hydrosilane or vinylalkoxysilane, phenol resins or peroxides.
• a cross linking agent such as sulphur, sulphurous compounds, metal oxides, maleimides, siloxane compounds for example hydrosilane or vinylalkoxysilane, phenol resins or peroxides.
• the granules are made of a thermoplastic elastomer for example Terra XPSTM which is commercially available by DSM DTE.
• the granules are made of a dynamically vulcanised thermoplastic elastomer or a vinyl- based polymer.
• the above polymers may be mixed with each other as long as the shore A hardness of the mixture is between 45-90.
• the granules according to the present invention may also comprise for example reinforcing and non-reinforcing fillers, plasticizers, antioxidants, UV-stabilizers, antistatic agents, waxes, foaming agents, lubricants or flame retardants as described in for example the Rubber World Magazine Blue Book.
• the granulate may include a suitable pigment and can be provided in any colour. Preferred is a lighter colour for example a brown, green, or beige colour because if a lighter colour is used sun light is more reflected which results in a lower temperature of the pitch.
• fillers are clay, talc, CaCO3.
• plasticizers are aromatic, naphtalenic or paraffinic oil, preferably oil with a low aromatic and sulphur content.
• An example of an UV stabiliser is a HALS compound.
• the granules according to the present invention may be manufactured by microgranulation of the extruded melt through a die plate with a diameter of holes in the range of 0.8 to 2.5 mm. For example the micro granulation can be conducted with commercial available underwater pelletizers.
• the thickness of the infill layer comprising the particulate material is for example between 10-30 mm, preferably between 20 and 25 mm. Not necessary but possible a layer of sand may be used having a thickness up to 15 mm.
• the backing sheet may consist of a sheet of plastic material such as, for example, a non-woven fabric, which is impregnated with for instance latex, such as for example SBR latex. Extending upwardly from the upper surface of the backing sheet a large number of upstanding fibres is present.
• the length of the fibres is selected depending upon the depth of the infill material and the desired resilience of the completed artificial turf structure.
• the depth of the infill layer is less than the length of the fibres.
• the length of the fibres is for example below 50 mm. Preferably the length of the fibres is below 45 mm.
• the fibres are preferably synthetic fibres composed of polyethylene, polypropylene or nylon.
• the fibres are for example single fibres or multiple fibres but also a mixture of multiple fibres and single fibres may be used.
• the thickness of the fibres may vary. However also a mix of thick and thin fibres is possible. This causes a ball to roll in a more predictable manner depending on the resistance of the fibres to the ball during play.
• the general criteria for making the backing sheet and the fibres are known in the art, and hence do not require a detailed description.
• the artificial turf structure must stand extremely high forces and pressures. As the infill material takes care of the most of these forces, it must be of enough strength to prevent permanent deformation and/or "melting" of the granules together.
• ISA Sport has developed a special test in which an amount of infill is pressurized at 2 N/mm2 for 72 hrs. After this time, the pressure is released and it is checked if the infill granules are still loose from each other and return back in their original shape.
• the present invention further relates to the use of a granulate with binder systems, such as polyurethane, as anti-slip floorings for example in boats or swimming pools, floorings for housing and commercial area's, as shock absorbing material in running tracks for horses, for tennis courts, for football or rugby turf pitches, for recreation and playing area's or for athletics tracks.
• binder systems such as polyurethane
• the present invention further relates to the use of a granulate having a defined shape as infill material in artificial turf structures. The description of the granulate is given above. The added value of the shape of the granules is further supported by an experiment in which an infill layer of specific infill material is installed without an artificial pitch.
• the granulate according to the present invention may be used in e- layers or shock pad's, safety tiles for recreation and playing area's but may also be used as infill material in artificial turf pitches for American football, artificial turf pitches for korfball, artificial turf for landscaping, artificial turf golf courses, artificial turf pitches for hockey. Moreover it can be used in safety artificial turf as infill between the of artificial turf system and recreation and playing area's or in artificial turf tennis courts as infill material between the artificial turf fibres.
• Force reduction is a measure for the shock absorbency of a field.
• the force reduction is measured in accordance with the Football-Related Technical
• the test method is referred to in the FIFA test manual and the specification is between 60 and 70%.
• the shock absorption of the artificial turf structure is at least 60%.
• Vertical deformation is determined by allowing a mass to fall onto a spring that rests, via a load cell and test food, on to a test specimen and the deformation of the surface under standard force is measured.
• the test method is referred to in the FIFA test manual and the specification is between 4 and 8 mm.
• the vertical deformation of the artificial turf according to the present invention is found to be between 4-8 mm.
• Rotational friction is determined by measuring the torque that is required to rotate a loaded studded disk in contact with the top surface of the specimen.
• the test method is referred to in the FIFA test manual and the specification is 30-45Nm.
• the rotational friction of the artificial turf structure according to the present invention is found to be between 30-45 Nm.
• Ball rebound is determined as follows: a FIFA test ball is released from 2 m above the surface of the specimen and the height of the rebound from the top surface is calculated. The specification is 60-90 cm. The ball rebound of the artificial turf structure according to the present invention is between 60-90 cm.
• a Lisport test stands for two cylinders with described positioned studs, which are moving with friction over a test piece of the turf system.
• One of the two cylinders is running with the same speed as the driving speed and the other cylinder is moving faster or slower, therefore causing a certain friction.
• After 5000 cycles (one way and back) the turf system is abraded to an equivalent of more then 5 years.
• the abrasion resistance of the fibres and infill material can be checked, but also the amount of compaction of the infill material (see figure 2).
• the invention will be illustrated by the following examples without being restricted thereto.
• An artificial turf structure was construed as follows, a carpet like pile fabric provided with upstanding artificial fibres representing turf blades (number of fibres per square meter was 8820). The length of the fibres was 45 mm. Then a layer of
• the thickness of the infill layer of the particulate material was 12.5 mm. Also a sand layer of 12.5 mm was applied as infill material. The distance between the top surface of the infill layer and the top surface of the turf blades was 20 mm.
• An artificial turf structure was construed as explained in example 1 with the difference that no sand infill layer was used.
• a layer of Terra XPS 1001 01 infill material was applied (weight per unit area 15 kg/m 2 ).
• the thickness of the infill layer of the particulate material was 22.5 mm.
• Example 3 An artificial turf structure was construed as explained in example 2.
• a layer of Terra XPS 1001 01 infill material was applied (weight per unit area 20 kg/m 2 ).
• the thickness of the infill layer of the particulate material was 30 mm.
• the artificial turf structure complied with all the requirements of the FIFA two star on shock absorption, vertical deformation, traction and vertical ball bounce as set out in the FIFA test manual.
• An artificial turf structure was construed as explained in example 4.
• a layer of Terra XPS infill material was applied (weight per unit area 20 kg/m 3 ' ).
• the thickness of the infill layer of the particulate material was 30 mm.
• An artificial turf structure was construed as explained in example 4.
• a layer of Terra XPS infill material was applied (weight per unit area 20 kg/m 2 ).
• the thickness of the infill layer of the particulate material was 30 mm.
• the shock absorption was measured in accordance with the UEFA standard for the Force Reduction on in an artificial turf system as described in Example 2 comprising Terra XPS granules with different L/D ratio's and compared with EPDM and grounded rubber of car tires.

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Cited By (10)

Citations (3)

• 2006
  • 2006-03-01 WO PCT/EP2006/002065 patent/WO2006092337A1/en not_active Application Discontinuation
  • 2006-03-01 EP EP06723263A patent/EP1853765A1/de not_active Withdrawn

Patent Citations (3)

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