INFILL MATERIAL FOR SYNTHETIC TURFS AND SYNTHETIC

TURFS SO OBTAINED

DESCRIPTION

Field of the invention The present invention relates to infill materials for synthetic turfs and to synthetic turfs obtained by using such infill materials.

The invention, furthermore, relates to a method for making such synthetic turfs.

Description of the prior art As known, a synthetic turf essentially consists of a mat made of plastic material to which blades of synthetic material, also called "bristles", are fixed in such a way to form a synthetic turf. The blades made of synthetic material are knitted to the mat by means of known processes that allow to obtain a warp of blades, which are close to each other according to the needs.

All around the blades made of synthetic material, an infill material is distributed, also simply called "infill". This is, usually, granular-shaped, and is selected both according to the kind of sport to which the synthetic turf is destined, for example soccer, hockey, cricket, rugby, but also according to the weather conditions that are more frequent where the synthetic turf is installed. As well known, the infill material provides a draining action by adjusting the drainage of rainwater or of irrigation water, protects the mat assuring to the synthetic turf a high duration, and especially gives to the turf mechanical, physical and technological features typical of the natural turf.

The most important features of an infill material are, in particular, the elasticity of the ground for the user, the rebound of the ball, the capacity of absorption of the hits when falling down, tensile and torque resistance to the force caused by the shoe, the resistance against the compression, to the penetration of external bodies, as well as the capacity of absorption and drainage of water in case of meteorological and environmental events.

The drainage action of the synthetic turf is, usually, carried out by a base portion, or "stabilizing infill", essentially constituted of sand. Instead, the elasticity of the synthetic turf is, usually, guaranteed by the presence of granules of rubber that are concentrated in the upper portion of the turf, or "performance infill". An example of a similar infill material is disclosed in CJS2002/081399.

However, the synthetic turfs of known type containing rubber and sand have many drawbacks. Firstly, owing to the compression caused by trampling, or by settling of the drainage water percolation, eventually the layer of sand tends to become compacted thus losing its drainage properties. Therefore, in particular in case of abundant rainfall, the synthetic turf is not able to drain away the rain water and is subjected to flooding. This causes a random and turbulent mixture of the infill material, in particular at the upper layers of the same, that is, therefore, shifted from the correct position within the infill. In particular, the infill material, in the time, provides zones where the material dragged by water concentrates, and other zones, instead, completely, or however impoverished of the same material. Therefore, the synthetic turf loses its original structure and, accordingly, the physical, mechanical and drainage features that it had at the moment of laying.

Another drawback of the synthetic turfs of prior art is strictly correlated with the presence of rubber. In particular, the presence of rubber, both in the most frequent case that it comes from waste materials, such as ground spent tyres, but also in the case in which it is rubber of first synthesis, mainly in the hotter seasons, quickly accumulates heat and reaches temperatures above 55 °C, with consequent troubles to the athletes if compared to natural turf fields. For this reason, the synthetic turf containing elastomeric materials must be periodically irrigated in order to avoid as much as possible the above mentioned overheating of the synthetic turf with consequent consumption of time and waste of water. Furthermore, the above disclosed irrigation and drainage cycles of the infill tends, with the passing of time, to compact the sand layer that, therefore, as above explained, performs an even less effective drainage action .

In addition to the above, the rubber, with the passing of time, tends to crumble and, therefore, the resulting fragments clog the empty spaces of the sand layer, thus, highlighting the above mentioned drawback of reducing the effectiveness of drainage at the stabilizing infill.

Summary of the invention

It is therefore an object of the present invention to provide an infill material for synthetic turfs, which is highly performance and that is able to solve the above mentioned drawbacks of the infill materials of prior art.

It is, in particular, object of the present invention to provide an infill material for synthetic turfs that is able to maintain in the time the structure that it had at the moment of laying.

It is, furthermore, an object of the present invention to provide an infill material for synthetic turfs that is able to perform an effective drainage of water.

These and other objects are achieved by an infill material for synthetic turfs, according to the invention, comprising :

a stabilizing infill comprising a predetermined quantity per unit surface area of vegetable material of rachis of cereal ear not coated by a layer, or film, of coating material, said predetermined quantity per unit surface area being set between 2 kg/m ² and 15 kg/m ² ;

a performance infill positioned above said stabilizing infill and constituted of polymeric material with elastomeric properties in granular form in a predetermined quantity per unit surface area.

As discussed in detail in the following, the presence of rachis of cereal ear in the stabilizing infill allows to avoid the above mentioned drawbacks of synthetic turfs of prior art. The material constituted of rachis of cereal ear, preferably corn-cob of maize, has, in particular, the property of absorbing high quantity of water "swelling", and then of releasing, in the drier and hotter seasons, the absorbed moisture in the surrounding environment. Consequently, the rachis of cereal ear acts as a "lung" for the synthetic turf, which incorporates it, because, as anticipated above, it absorbs the water, or the moisture, in excess, increasing its volume, and then gradually reducing it by releasing the moisture, when the climatic conditions return drier and the ambient temperature increases. The rachis of cereal ear provides, in fact, a high porosity and is subjected to alternating cycles of expansion, and of compression, or in any case of reduction of volume. Therefore, the whole infill material, and in particular the performance infill, is subjected to a decompacting action that allows to keep the infill material tilled, and preserving substantially intact in the time the physical properties of the infill. In addition to the above, the material constituted of rachis of cereal ear, in particular corn-cob, is able to absorb a high quantity of moisture, for example during rain and irrigation interventions, and, then, to release the above mentioned moisture in the hotter seasons, thus obtaining a thermal balance of the turf. In particular, corn-cob has a water absorption capacity that is about 138%. Such properties avoid excessive heating of the performance infill, in particular of the above mentioned plastic material having elastomeric properties, during the hotter seasons .

Other features of the invention are defined in the dependent claims.

Advantageously, the stabilizing infill, furthermore, comprises a predetermined quantity per unit surface area of sand.

In particular, the stabilizing infill can provide a mixture of a predetermined percentage by volume of said vegetable material of rachis of cereal ear and a predetermined percentage by volume of sand.

More in particular, the mixture of vegetable material of rachis of cereal ear and sand has the following composition :

between 25% and 90% by volume of the above mentioned material of rachis of cereal ear;

between 10% and 75% by volume of sand.

In particular, the infill material can comprise a predetermined quantity per unit surface area of the above mentioned mixture, said predetermined quantity per unit surface area being set between 2.5 kg/m ² and 15 kg/m ² .

Preferably, the vegetable material constituted of rachis of cereal ear is corn-cob, i.e. rachis of maize. This solution is particularly advantageous because corn cob, i.e. the rachis of maize, has a size that is normally higher than the size of the rachis of other cereals and has, therefore, better physical properties, in particular in terms of capacity of expanding and reducing in size, with respect to the other cereals.

In an embodiment of the invention, the stabilizing infill of the infill material can comprise:

a first layer of sand;

a second layer positioned on said first layer of sand and constituted of the above mentioned vegetable material of rachis of cereal ear.

In particular, the first layer can be constituted of a predetermined quantity per unit surface area of sand, said predetermined quantity being set between 10 kg/m ² and 25 kg/m ² .

More in particular, the second layer can be constituted of a predetermined quantity per unit surface area of the above mentioned vegetable material of rachis of cereal ear, said predetermined quantity per unit surface area being set between 2 kg/m ² and 5 kg/m ² .

Advantageously, the above mentioned plastic material having elastomeric properties in granular form of the performance infill is selected from the group consisting of: styrene-butadiene rubber, or "SBR", a thermoplastic material, an ethylene-propylene-diene monomer, or rubber "EPDM", polyvinyl chloride, or "PVC", a synthetic organic material, or a combination thereof.

In particular, the above mentioned synthetic organic material is a mixture of a plastic material with elastomeric properties, and an organic material of vegetable origin, preferably selected from the group comprised of coconut and cellulose.

Advantageously, the vegetable material constituted of rachis of cereal ear, in particular corn-cob, has a granulometry set between 0.3 mm and 5.0 mm.

In particular, with the term "sand" it is to be understood a material having a mineralogical composition, for example siliceous sand, sand of pumice, sand of lapillus, zeolite, vermiculite, etc.

In another alternative embodiment of the invention, the performance infill can be constituted of only vegetable material of rachis of cereal ear in a predetermined quantity per unit surface area set between 2 kg/m ² and 8 kg/m ² .

Advantageously, the predetermined quantity per unit surface area of polymeric material with elastomeric properties in granular form, of the infill material, is set between 8 kg/m ² and 18 kg/m ² .

According to another aspect of the invention, a synthetic turf comprises: a mat having a first face and a second face opposite to the first face;

a plurality of blades made of synthetic material fixed to said mat, said plurality of blades made of synthetic material protruding from said second face in such a way to form a synthetic turf;

an infill material, as above described, distributed on said second face of said mat.

According to a further aspect of the invention, a method for making a synthetic turf comprises the steps of:

disposing a mat to which a plurality of blades made of synthetic material is fixed, said mat providing a first face and a second face opposite to the first face, said plurality of blades made of synthetic material protruding from said second face;

distributing on said second face of said mat an infill material, thus obtaining a synthetic turf, said infill material comprising:

a stabilizing infill comprising a predetermined quantity per unit surface area of vegetable material of rachis of cereal ear not coated with a film, or layer, of coating material, said predetermined quantity per unit surface area being set between 2 kg/m ² and 15 kg/m ² ;

- a performance infill positioned above the above mentioned stabilizing infill and constituted of polymeric material with elastomeric properties in a predetermined quantity per unit surface area. In an alternative embodiment, the blades made of synthetic material can comprise smooth blades, or wavy blades, or smooth blades alternating to wavy blades.

In particular, the mat can provide a plurality of holes arranged to put in communication said first face and said second face, in such a way to allow the water to flow under the mat.

According to another aspect of the invention, a stabilizing infill for infill materials for synthetic turfs comprises:

- between 10% and 75% by volume of sand;

- between 25% and 90% by volume of vegetable material of rachis of cereal ear.

Brief description of the drawings The invention will now be shown with the following description of its exemplary embodiments, exemplifying but not limitative, with reference to the attached drawings in which :

Fig. 1 diagrammatically shows a cross sectional view of a possible exemplary embodiment of a synthetic turf obtained by using the infill material, according to the invention;

Fig. 2 diagrammatically shows a cross sectional view of an alternative embodiment of synthetic turf of figure 1;

Fig. 3 diagrammatically shows a cross sectional view of a possible alternative embodiment of synthetic turf of figure 1; Fig. 4 diagrammatically shows a front elevational perspective view provided with a portion removed of a possible embodiment of a sack containing a mixture, according to the invention, that can be used for making the stabilizing infill;

Fig. 5 diagrammatically shows an enlargement of the mixture contained within the sack of figure 4 in order to highlight some characteristics.

Detailed description of some exemplary embodiments of the invention

With reference to figure 1, a synthetic turf 1, according to the invention, comprises a mat 2, which provides a face 2a, which, in use, is arranged adjacent to the surface to be coated, and a face 2b opposite to face 2a. The synthetic turf 1 comprises, furthermore, a plurality of blades, or bristles, 3 made of synthetic material that are fixed to mat 2, for example by means of gluing, or stitching. Above the face 2b of mat 2 is, furthermore, present an infill material 10 arranged all around the blades 3 made of synthetic material.

The infill material 10 provides a lower portion, or stabilizing infill 11, and an upper portion, or performance infill 12 positioned above the stabilizing infill 11. In all the embodiments shown in the figures, and disclosed in detail in the following, the performance infill 12 is essentially constituted of a plastic material having elastomeric properties, preferably selected between styrene-butadiene rubber, or "SBR", a thermoplastic material, an ethylene-propylene-diene monomer, or "EPDM" rubber, polyvinyl chloride, or "PVC", a synthetic organic material, or a combination thereof.

In particular, the above mentioned synthetic organic material can be a mixture of a plastic material having elastomeric properties, and of an organic material of vegetable origin, preferably selected between coconut and cellulose, or a combination thereof. The above mentioned mixture is appropriately extruded in order to obtain granules of the above mentioned synthetic organic material .

More in particular, the above mentioned plastic material having elastomeric properties in granular form can be of black colour, or of a different colour, or can provide a mixture of two, or more colours.

According to the present invention, the stabilizing infill 11, comprises a vegetable material of rachis of cereal ear not coated of a film, or layer, of coating material, in a predetermined quantity per unit surface area. In particular, the above mentioned predetermined quantity per unit surface area of the above mentioned vegetable material of rachis of cereal ear is set between 2 kg/m ² and 15 kg/m ² , in function of the height of the synthetic grass. In a possible embodiment the cereal can be maize and, therefore, the rachis of cereal ear is

"corn-cob" . In particular, the vegetable material of rachis of cereal ear is not coated with a film of coating material in order to be able to absorb and to release moisture and, therefore, to alternate the above mentioned cycles of increasing and of reduction of volume that, as above disclosed, are fundamental in order to avoid an excessive heating of the material of which the performance infill is constituted.

In the embodiment of figure 1, the stabilizing infill 11 provides a single layer constituted only of vegetable material of rachis of cereal ear. In this case, a distribution step is advantageously provides of a predetermined quantity per unit surface area of the stabilizing infill set between 2 kg/m ² and 8 kg/m ² on the above mentioned mat 2. In this way, thanks to its above mentioned properties, in particular the capacity of increase its volume in presence of water and of decreasing its volume with drier climatic conditions, the material of rachis of cereal ear carries out an auto-decompacting action that allows to keep the stabilizing infill tilled, and of preserving substantially intact in the time, the physical features, in particular the drainage capacity.

In the embodiment of the invention of figure 2, the stabilizing infill 11 provides, instead, a lower layer 11a of sand, above of which is positioned a layer lib of the above mentioned material of rachis of cereal ear, preferably corn-cob. As can be easily understood, the above mentioned predetermined quantity per unit surface area of sand of the stabilizing infill will be mainly concentrated, in this case, in the first layer, i.e. in the lower layer 11a, whilst the above mentioned predetermined quantity per unit surface area of vegetable material constituted of rachis of cereal ear will be mainly concentrated in the second layer, i.e. the upper layer lib. In this case, the material of rachis of cereal ear prevents the sand layer 11a and, therefore, the whole stabilizing infill 11 and, therefore, the synthetic turf, from being compacted.

More precisely, the first layer 11a is constituted of a predetermined quantity per unit surface area of sand set between 10 kg/m ² and 25 kg/m ² . The second layer is, instead, constituted of a predetermined quantity per unit surface area of the above mentioned vegetable material of rachis of cereal ear set between 2 kg/m ² and 5 kg/m ² .

In the alternative embodiment of figure 3, instead, the infill material 10 provides for the stabilizing infill 11 a single layer constituted, in this case, of a mixture of sand and the above mentioned material of vegetable constituted of rachis of cereal ear. In particular, the above mentioned mixture of vegetable material of rachis of cereal ear and sand is constituted for a percentage by volume set between 25% and 90% of material of rachis of cereal ear, and for a percentage by volume set between 10% and 75% of sand.

More in detail, the predetermined quantity per unit surface area of the mixture of vegetable material of rachis of cereal ear and sand is set between 2.5 kg/m ² and 15 kg/m ² .

The combined use of sand and vegetable material of rachis of cereal ear allows to obtain a highly draining synthetic turf and, thanks to the properties of the vegetable material of rachis of cereal ear, to avoid that the sand, which is present in the stabilizing infill, can be compacted and, therefore, that the synthetic turf following to the irrigation, or to the rain, can flood. In other words, the presence of vegetable material of rachis of cereal ear guarantees that, in the time, the effectiveness of the drainage action of the sand layer is maintained.

With reference to figures 1 to 3, at the end of the distribution of infill material, the blades, or bristles,

3 of synthetic material provide an upper portion protruding of a determined height from the upper surface 10b of the infill material, for example protruding of about 2-10 cm.

Furthermore, as shown in detail in figure 3, the mat, or support, 2 can provide drainage holes 4, having sizes such that they allow the outflow of the percolated water obtained by the drainage action of the stabilizing infill 11. In figure 4 a sack 100 is shown, by way of example, containing a predetermined quantity of a mixture 20 of sand and vegetable material of rachis of cereal ear in the above disclosed percentage by volumes. As shown in detail in figure 5, the mixture 20 is substantially "homogeneous" in the sense that the granules of the two components, that is to say of sand and of vegetable material of rachis of cereal ear, are dispersed one in the other such that it is not easily visible to the naked eye. The mixture 20 can be used, in particular, for obtaining the embodiment of infill material 10 of the synthetic turf of figure 3.

The foregoing description exemplary embodiments of the invention will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such embodiment without further research and without parting from the invention, and, accordingly, it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realize the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation .