MAT, IN PARTICULAR FOR SYNTHETIC TURF, SYNTHETIC TURF STRUCTURE INCLUDING THE MAT, AND MAT MANUFACTURING METHOD AND APPARATUS

TECHNICAL FIELD

The present invention relates to a mat, in particular for synthetic turf, and to a method and an apparatus for manufacturing said mat .

Since the mat is particularly indicated for use in a synthetic turf, the invention also relates to a synthetic turf structure including the mat .

BACKGROUND ART It is known that, in general terms, synthetic turfs, in particular for sports fields, consist of a mat formed by a primary substrate from which there extend vertically filaments that simulate a natural greensward . Normally, one or more layers of infill material of various nature, for example sand and/or polymeric granules , "clog" the mat .

The panorama regarding mats for synthetic turfs is very diversified, and manufacturers have different choice options from both the quality viewpoint and the price optimization viewpoint, above all as regards the choice of yarn for fabrication of the filaments . For example, it is known that the filaments can be produced with yarns having various chemical compositions ( for example, polypropylene, polyethylene, nylon, other polymeric fibres , etc . ) . It is likewise known that the yarns may be of different types or assume different structures ; for example, they could be fibrillated, single-stranded, curly, etc .

In particular, mats with so-called "fibrillated" yarns are known . Fibrillation is basically a method whereby the yarn is cut in a discontinuous way lengthwise and assumes a

conformation similar to a mesh . The peculiar characteristic of fibrillated yarn is that of withholding within the "mesh" the components of the infill, whether they are granules of sand or rubber . Said mesh prevents displacement of the infill within the mat above all in the event of heavy rainfall . Even though such mats are widely used throughout the world, they present a marked limit as regards duration over time, due principally to the continuation of the process of defibrillation of the individual strands of yarn, which, under the normal action of wear that occurs at their top ends , undergo fragmentation and inevitably lose their original texture .

In order to overcome the above drawbacks, other techniques have aimed at using "single-strand" yarns . Said yarns are made without any mesh but with a clean and continuous cut, which bestows upon the yarn the appearance of a thin strip or blade, very similar to a blade of natural grass . Said blade normally presents a greater thickness (measured in micron) , which guarantees, in addition to a considerably improved appearance, a longer duration of the original characteristics . However, the various tufts j oined together in various numbers, form a less effective barrier for the infill formed by the granules of sand or rubber, which for this reason is less stable and more "dynamic" . The use of single-strand yarns has hence overcome the problems of appearance and ■ duration, leaving, however, unsolved other problems of equal importance .

A number of known solutions have also attempted to combine the peculiar characteristics of fibrillated yarn and single-strand yarn . In accordance with these solutions, yarns of the two types are used, which are cut to the same height; then, the heat of the coating oven is used in order to cause retraction and hence decrease in height of one of the two yarns, so obtaining in effect one yarn that extends to a full height and one yarn that is curled over . This curling process is not, however, itself free from drawbacks . In the first place, the

process is far from viable from the economic standpoint, in so far as curling reduces the height of a filament which had, however, been made and cut to a larger height (the same as that of the other yarn) , so that the entire portion of strand that is curled is in actual fact wasted. In addition, even though the presence of the curl in part solves the problem of withholding the infill, it is compacted by being subj ected to treading, so that the mat becomes hard and loses its original elasticity .

DISCLOSURE OF INVENTION

One aim of the present invention is to provide a mat and a structure of synthetic turf comprising said mat which will enable the above highlighted drawbacks of the known art to be overcome .

A further aim of the invention is to provide a method and an apparatus for fabrication of the mat .

The present invention hence regards a mat, in particular for . synthetic turfs, as defined in the annexed Claim 1.

The mat according to the invention solves the problems highlighted previously of known techniques , in so far as it envisages combining two yarns and cutting them to two different heights . It is possible to use two yarns of different composition and/or different structural characteristics, and choose appropriately the two yarns , exploiting fully the peculiar characteristics thereof .

For example, it is possible to use a first fibrillated yarn that is cut to a first height and a second yarn (namely, a single-strand yarn) that is cut to a greater height .

The yarn that is cut shorter gives rise to filiform formations , which, thanks to the "mesh" typical of the

fibrillated yarn, withhold the infill and moreover facilitate the laying operations , enabling the right amount of filling to be achieved, without, however, being visible (and hence j eopardizing the overall appearance of the grass covering) or being directly subj ected to wear . In addition, the cut operation enables the part that in actual fact is not necessary not to be used, with considerable saving in terms of production costs .

The filiform formations of the second yarn, for example a single-strand yarn, are cut to a height greater than those of the first yarn so as to form the surface part of the mat . Said filiform formations, which come into direct contact with the players or athletes, bestow upon the mat longer duration, lower abrasion, and a better appearance, whereas the shorter filiform formations , in addition to withholding the infill , support the longer filiform formations, without being visible and without being subj ected to direct treading and hence to wear .

The technique according to the invention hence enables maximum exploitation of the various types and compositions of the yarns, exalting their peculiar characteristics and enabling at the same time a considerable economic saving .

To provide the first filiform conformation constituting the bottom part of the mat it is possible to use lower-quality yarns, rej ect stocks, yarns that have a wide range of different chemical compositions, in addition to yarns of different colours , thus providing the possibility of creating mats with two colours .

The invention moreover regards a method and an apparatus for manufacturing the mat that has been described in summary previously, which are defined in Claims 6 and 10 respectively.

Said method and apparatus enable a simple and economically advantageous fabrication of the mat according to the invention .

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will emerge clearly from the ensuing description of a non-limiting example of embodiment thereof, with reference to the figures of the annexed drawings, wherein: - Figure 1 is a schematic view of a synthetic turf structure including a mat according to the invention;

- Figure 2 is a schematic view of an apparatus for manufacturing the mat according to the invention; and

- Figure 3 is an enlarged scale view of a detail of the apparatus of Figure 2.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to Figure 1 , a synthetic turf structure 1 comprises a mat 2 , having a sheet-like substrate 3, from which there extend filiform formations 4A, 4B having at least two different heights .

The filiform formations 4A, 4B are anchored to the substrate 3 via respective attachment ends 5 and extend from a face 6 of the substrate 3 in a direction that is substantially orthogonal to the substrate 3 , terminating with respective free ends 7.

In particular, the mat 2 comprises a first plurality of filiform formations 4A and a second plurality of filiform formations 4B . The filiform formations 4A and 4B have, in their completely extended condition, respective different heights Hl and H2 measured starting from the substrate 3 (the heights Hl , H2 are in other words the lengths of the filiform formations 4A, 4B measured in their fully extended configuration between the face 6 of the substrate 3 and the

free ends 7 ) .

The filiform formations 4A and 4B are woven to the substrate 3 and, as will emerge clearly hereinafter, are cut at the two heights Hl , H2.

The filiform formations 4A and 4B are interspersed with respect to one another and are made using respective yarns 8A, SB, which are woven separately from one another to the substrate 3.

The yarns 8A, 8B are the same as one another or else differ as regards structure and/or composition. For example, the yarns 8A, 8B are made of synthetic fibre, such as polyethylene, polyamide, polypropylene, etc .

According to a preferred embodiment, the yarn 8A of which the filiform formations 4A of smaller height (i . e . , height Hl ) are made is a fibrillated or multistrand yarn, whereas the yarn 8B of which the filiform formations 4B of greater height (height H2 ) are made is a single-strand yarn .

The height of the filiform formations 4A and 4B and, hence, also the difference between the height Hl and the height H2 can be selected according to the requirements . Purely by way of example, the difference in height between the filiform formations 4A and 4B is comprised between approximately 10 mm and approximately 50 mm and preferably between approximately 20 mm and approximately 30 mm. For example, the height H2 of the filiform formations 4B is approximately 40 to 80 mm and preferably approximately 50 to 70 mm, and the height Hl of the filiform formations 4A is approximately 20 to 60 mm and preferably approximately 25 to 55 mm.

The substrate 3 is constituted by a layer or sheet of suitable plastic material, in particular a woven or a non-woven fabric

made of synthetic rubber, for example styrene-butadiene rubber ( SBR) .

The mat 2 is laid in use on a foundation 9, for example a foundation of tamped earth, on which one face 10 of the substrate 3 opposite to the face 6 from which the filiform formations 4A, 4B extend rests .

The structure 1 then comprises a particulate infill material 11 arranged between the filiform formations in one or more layers .

In particular, the infill material 11 forms a filling layer 12 , which has a height H, measured starting from the substrate 3 , smaller than or equal to the height Hl of the shorter filiform formations 4A.

In the example of Figure 1, the infill material 11 is substantially flush with the free ends 7 of the filiform formations 4A of smaller height, i . e . the filling layer 12 has a height H that is substantially the same as the height Hl of the filiform formations 4A.

According to an aspect of the invention, the infill material 11 comprises granules made with a mixture of a basic material, constituted by one or more recycled vulcanized elastomers (for example, recycled tyres) , finely ground or micronized, and by S.Z least one thermoplastic polymer, in particular a thermoplastic elastomer .

In particular, the basic material is a recycled material or a material that has been discarded from other production processes , for example obtained from very finely ground

(micronized) tyres, and hence an SBR-based material, mixed with a suitable amount of thermoplastic elastomer, for instance a styrene-butadiene-styrene (SBS) rubber .

Even though a structure 1 has been illustrated in which the mat 2 is used together with the infill material 11, owing to its characteristics the mat 2 is suitable for being used as synthetic turf even without infill . In this case, underneath the substrate 3 a mat of elastomeric material can be laid in order to bestow greater elasticity upon the structure 1.

On the other hand, the infill material 11 is suited for use in structures of synthetic turfs different from the one described herein, i . e . , with mats other than the mat 2.

Figures 2 and 3 illustrate an apparatus 15 for the fabrication of the mat 2.

The apparatus 15 comprises means 16 for supporting and moving the sheet-like substrate 3 and which define a working surface F and a feed direction D of the substrate 3, a loom 17 having a first plurality of needles 2OA and a second plurality of needles 2OB and a reference block 21 , and one first feed assembly 22A and one second feed assembly 22B, which are independent of one another, for feeding respective yarns 8A, 8B to the first plurality of needles 2OA and to the second plurality of needles 20B respectively, possibly with a rate of feed regulated independently of one another .

A first hook-earring bar 24A and a second hook-earring bar 24B, provided with respective pluralities of hooks 25A, 25B set alongside each other, are arranged underneath the working surface P substantially parallel to one another and to the working surface P and orthogonal to the feed direction D of the substrate 3 for co-operating with the needles 2OA and the needles 2OB respectively.

The hook-earring bars 24A, 24B are associated to respective blade-earring bars 27A, 27B provided with respective

pluralities of blades or knives 28A, 28B in such a way that each hook 25A, 25B is associated to a blade 28A, 28B .

The hook-earring bars 24A, 24B are arranged at different distances Dl, D2 from the working surface, and hence the hooks 25A work at a different distance from the hooks 25B with respect to the working surface P . Also the blade-earring bars 27A, 27B, associated and arranged in the proximity of the respective hook-earring bars 24A, 24B, are consequently arranged at different distances from the working surface P, and the blades 28A work at a different distance from the blades 28B with respect to the working surface P .

The needles 2OA, 2OB are moved by the loom 17 in the vertical direction through a reed 29 carried by the reference block 21 and through the substrate 3, in order to weave the yarns 8A, 8B separately from one another to the substrate 3.

The hook-earring bars 24A, 24B and the blade-earring bars 28A, 28B are movable so as to impart upon the hooks 25A, 25B and the blades 28A, 28B a reciprocating motion in a direction substantially orthogonal to the movement of the needles 2OA, 2OB and parallel to the feed direction D of the substrate 3.

Operation of the apparatus 15 implementing the method of fabrication of the mat 2 according to the invention is described in what follows .

The substrate 3 is fed in the feed direction D to the loom 17. The needles 2OA, 2OB, in reciprocating vertical motion, cooperate with the hooks 25A and the hooks 2OB, respectively, in order to weave the filiform formations 4A and 4B separately from one another to the substrate 3.

The blades 28A co-operate with the hooks 25A in order to cut the filiform formations 4A to the height Hl, given by the

distance Dl at which the hook-earring bar 24A and the blade- earring bar 27A are located from the working surface P . Likewise, the blades 28B co-operate with the hooks 25B for cutting the filiform formations 4B to the height H2 , given by the distance D2 at which the hook-earring bar 24B and the blade-earring bar 27B are located from the working surface P . In this way, the substrate 3 is provided with filiform formations 4A, 4B at the two different heights Hl , H2.

It is understood that modifications and variations can be made to what is described and illustrated herein without thereby departing from the scope of the annexed claims .

For example, according to a variant of the structure 1 shown in Figure 1 , the filiform formations 4A of smaller height are made of a rubber thread, i . e . , a thread made of elastomeric material having, for example, a circular or flattened ribbon- like section. The filiform formations 4A can be made of either cross-linked or vulcanized elastomeric material or of thermoplastic elastomeric material .

The mat 2 made according to the above variant possesses an intrinsic elasticity, due precisely to the filiform formations 4A made of elastomeric material, so that it is possible to reduce or avoid altogether the use of elastomeric components in the infill material 11. Also the use of a mat of elastomeric material underneath the substrate 3 is rendered superfluous .

The filiform formations 4A can be made of a thread cut to the desired height, or else can be a boucle thread.