TECHNICAL FIELD

The present invention relates to an artificial turf structure, in particular for sports fields, and a method for manufacturing the same. BACKGROUND ART It is known that, in general terms, artificial turfs, in particular for sports fields, consist of a synthetic mat formed by a sheet substrate from which there extend vertically filaments which simulate a natural greensward; infill materials are arranged between the filaments to form one or more filling layers; the infill materials most commonly used are sand and relatively resilient polymeric materials (mainly natural or synthetic rubber, but also thermoplastic materials of various types) , which are either mixed together or arranged in layers, according to various methods.

The known structures of this type are not free from drawbacks, mainly due to the typology of infill materials used and/or their arrangement in layers, thus resulting not very satisfactory in terms of performance, relatively high material costs, irritability to the eyes and ears of users, bad odours, poor drainage, high temperatures in summer and low

humidity retention.

Furthermore, the users, both professional athletes and amateurs, often manifest certain "mental" reservations about artificial fields, due precisely to the absence of the characteristic sensations

(olfactory, contact, humidity, etcetera) for which natural grass fields are appreciated instead.

There are known, on the other hand, sports fields made with "mixed" turfs, in which on the synthetic mat, having relatively sparse filaments with respect to the completely artificial turfs, it is arranged a cultivation substrate (natural soil added with fertilisers or growth promoters, suitable therefore for the growth of natural grass) which is sowed and on which natural grass therefore grows.

These structures are particularly complex and costly to construct and to maintain, requiring, in addition to particular constructive precautions of the synthetic mat, also all the care normally required by natural grass fields.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide an artificial turf structure, in particular for sports fields, and a method for manufacturing artificial turfs which are free from the drawbacks illustrated above.

In particular, it is an object of the invention to provide a structure which is entirely artificial (that

is does not require sowing and care of natural grass) and which essentially reproduces the features, from a point of view of performance and also from the sensorial point of view, of a natural turf. The present invention therefore relates to an artificial turf structure, in particular for sports fields, and to the method for manufacturing thereof, as defined in attached claims 1 and 20 respectively.

The structure according to the invention and the method for manufacturing thereof overcome the above mentioned drawbacks.

Indeed, the use of peat or other analogous material allows to make structures with entirely artificial greensward (that is free from natural grass) but which reproduces both the performance and sensorial features of a natural turf.

In particular, the use of peat allows to obtain particularly soft and elastic, not abrasive, filling layers with a high drainage capacity and capable of at the same time maintaining an adequate degree of humidity and therefore humid and cool in summer and in particularly hot and dry climates .

The users then advert the typical natural odour of peat or similar material, which replaces (or covers) the odour of the polymeric materials of the filling layer or of the turf itself.

The users therefore receive from the structure according to the invention the same sensations as a

natural grass field (softness, elasticity, low abrasiveness, right degree of humidity and coolness, odour) .

Besides, these results are due to the particular fibrous/filamentous structure typical of peat and analogous materials of prevalently vegetable origin, which although decomposed, partially carbonised or otherwise transformed, maintain some of the features of the original vegetable organisms. The fibrous/filamentous structure then incorporates and withholds possible particulate materials which are added to the filling layer, for example sand.

Also the costs of manufacturing of the structure according to the invention are considerably contained, because peat and analogous materials have generally low costs, usually lower than those of synthetic infill materials (elastomeric granules) .

Similar results, above all in terms of humidity ritention and draining capacity, may be obtained by using in the infill material, in addition to or instead of the peat and/or similar material, porous materials in granular form of volcanic origin, such as volcanic lapillus, pumice stone, etcetera, preferably with granulometry from about 0.2 to about 2.0 mm. The invention therefore also relates to the use of such materials as infill materials in an artificial turf structure .

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will be apparent in the description of the following non-limitative examples of embodiments, with reference to the accompanying drawings, in which: - figure 1 schematically shows a first embodiment of the artificial turf structure according to the invention;

- figure 2 schematically shows a second embodiment of the artificial turf structure according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION With reference to figure 1, an artificial turf structure 1 for sports fields comprises a synthetic mat 2, having a sheet substrate 3 from which grass- resembling filaments 4 project, and a filling layer 5 formed by infill material arranged between the filaments 4. The mat 2 is placed on a foundation base 7, for example a tamped earth bed.

The substrate 3 consists of a sheet or tape of suitable plastic materials, in particular a fabric, a non-woven fabric or a felt made of synthetic rubber, for example styrene-butadiene rubber (SBR) , or of synthetic fibres, for example polypropylene or similar, possibly spread or coated with suitable polymeric reinforcement layers. The filaments 4, made of suitable yarns, for example polyethylene, polyamide, polypropylene, etcetera, are sewn or woven on the substrate 3.

The filling layer 5 comprises peat and/or other similar natural organic material derived from vegetable residues .

Hereinafter, peat "similar material" is referred to a natural organic material with fibrous/filamentous structure of prevalently vegetable origin, in particular essentially or prevalently derived from decomposition, carbonising or other kind of transformation of vegetable residues, such as indeed peat, vegetable topsoil, vegetable based composting materials, etcetera.

Advantageously, the peat and/or similar material are present in the filling layer 5 in ground, chopped or shredded form. Preferably, the filling layer 5 also comprises a rigid particulate material, namely sand in granular form which is commonly used as filling material for artificial turfs.

The peat and/or similar material and the rigid particulate material (sand) may be mixed together and arranged in layers (each layer being formed by only one of the materials or by their mixture) to form the filling layer 5.

In the example in figure 1, the filling material forming the filling layer 5 is a mixture of peat and/or similar material and rigid particulate material (sand) .

Preferably, the filling layer 5 contains peat or similar material in a quantity from about 10 to about

90% by volume.

The filling layer 5 also comprises a germination inhibitor and/or herbicide substance, adapted to avoid the growth of natural grass, and an antifreeze additive, of any known type and dispersed in the infill material and in particular in the peat or similar material. For example, the filling layer 5 comprises salt (sodium chloride) , which prevents the growth of natural grass and at the same time lowers the ice forming temperature, and which is dispersed in the peat and/or similar material.

The filling layer 5 also optionally comprises a resilient particulate material, such as rubber, of any type usually employed for infilling artificial turfs (for example natural or synthetic rubber, thermoplastic elastomers, etcetera) and in any appropriate amount to obtain the specific elastic characteristics of the filling layer 5.

The peat and/or similar material may be replaced, partially or entirely, by a volcanic origin porous material in granular form, for example volcanic lapillus, pumice stone, etcetera, having a granulometry from about 0.2 to about 2.0 mm.

The peat and/or similar material and the resilient particulate material, and possibly the rigid particulate material (sand) and/or the porous volcanic material if present, may be mixed together or arranged in layers (each layer being formed by only one of the

materials or by their mixture) to form the filling layer 5.

The filling layer 5 may indeed comprise a plurality of layers, each having different composition, for example layers formed essentially or prevalently of rigid particulate material (sand) ; of peat and/or similar material; of mixtures of peat and/or similar material and sand; of mixtures of peat and/or similar material and resilient particulate material (rubber) ; etcetera.

For example, in the preferred embodiment shown in figure 2, the filling layer 5 comprises a layer 11 of rigid particulate material (sand) , positioned immediately over the substrate 3, and a layer 12 superimposed on the layer 11 and comprising peat and/or similar material.

In particular, the layer 11 essentially or prevalently consists of sand granules and constitutes from about 10% to about 30% by volume the entire filling layer 5, having for example a thickness from approximately 10 to approximately 40 mm and preferably of approximately 20-30 mm; the layer 12 is made of a mixture of peat and/or similar material and sand in granules and has a thickness from approximately 30 to approximately 80 mm and preferably approximately 40-50 mm, and such that it leaves uncovered a terminal length of approximately 3-7 mm of the filaments 4. Preferably, the layer 12 contains peat or similar material in a

quantity from about 10 to about 90% by volume.

Furthermore, the layer 12 contains germination inhibitor and/or herbicide substances and antifreeze additives, for example salt, as already described with reference to figure 1.

Also in this case, moreover, the layer 12 may contain, in partial or complete replacement of the peat and/or the similar material, a porous material of volcanic origin in granular form, such as volcanic lapillus, pumice stone, etcetera, always with a granulometry from about 0.2 to about 2.0 mm.

The structure 1 according to the invention is made using the following method.

After having prepared the foundation base 7 in the known way, it is placed on the foundation base 7 the synthetic mat 2 formed by the substrate 3 and by the filaments 4.

The infill material comprising peat and/or similar material is prepared; in the infill material preparation step, the peat and/or the similar material are ground, chopped or shredded, then mixed with the rigid particulate material (sand) and, optionally, with the resilient particulate material such as rubber, in the appropriate amounts; the infill material is also added with the germination inhibitor and/or the herbicide substance and the antifreeze additive.

If the peat and/or the similar material is at least partially replaced by porous material of volcanic

origin, the preparation step of the infill material comprise the addition of such material, which has been preventively ground to obtain the required granulometry. The infill material thus prepared is then sprinkled onto the substrate 3 between the filaments 4 to form the filling layer 5.

If the structure 1 comprises several layers with different composition, as described above, the layers are applied in sequence one on top of the other (after having possibly prepared the mixtures of materials forming the various layers) .

Finally, it is understood that changes and variations can be made to that described and shown herein without departing from the scope of the annexed claims .

For example, according to a further embodiment of the invention, the filling layer 5 also comprises a coconut-based vegetable material or other similar vegetable material in fibrous, ground and/or shredded form, wherein it is hereinafter intended for "vegetable material" an essentially not decomposed vegetable material, obtained by vegetable organisms of recent formation and not yet subject to degenerative processes, such as decomposition, rotting, degrading, fossilisation, carbonising, etcetera (and which is therefore distinguished from peat and similar materials as defined above, which are of vegetable origin but

which have undergone substantial transformation processes, such as decomposition, carbonisation, fossilisation, etcetera) .

In particular, the infill material comprises parts of the coconut plant (for example the bark) and/or the nut (shell, hull, pulp, etcetera of the coconut); preferably, the infill material comprises coco fibres and/or the so-called coco peat, obtained as known from the coconut shells, and/or other similar vegetable materials, such as for example: vegetable materials derived from the bark of bushes and plants and/or natural fibres made from vegetables, in particular agave fibres (particularly sisal) and hemp fibre.

According to a preferred embodiment, the infill layer is formed by a mixture of approximately one part of peat, one part of sand and one part of coconut.

It is however understood that the filling layer may be formed by mixtures of components previously indicated in any percentage, according also to the features of softness, elasticity and compactness to be conferred to the structure 1; it is also understood that all the indicated components can be mixed together and arranged in layers and that the filling layer 5 may therefore comprises a plurality of layers, each having different composition and/or thickness.

According to a further embodiment, the infill material, possibly formed by a mixture of components previously shown, is used in the form of compact

granules. In particular, the various components of the filling layer 5 are, before being sprinkled on the substrate 3, subjected to a mixing, densification and granulation process, in which the various components, initially in ground or shredded form, are mixed, densified with possible elimination of part of the humidity, and then compacted in the form of granules having dimensions in the order of a few millimetres.

In this way, it is greatly simplified the installation step of the filling layer 5, because the infill material (regardless of its composition) is applied to the substrate 3 in granular form, thus avoiding the formation and sprinkling of powders; the granules of infill material are then dampened with water so as to dissolve the granules and release the components in the original form.

It is also possible to comprise in the granules all the components needed for the formation of infill material, without therefore requiring the use during installation of different material; it is also possible to comprise in the granules possible further additives, for example colorants to confer to the granules a particular colour, substances adapted to make the granules fireproof, substances adapted to prevent the formation of moulds, fungi, bacteria, etcetera.