Infill material for synthetic turfs and synthetic turfs so obtained

Abstract

Synthetic turf (1) comprising a mat (2) equipped with a first face (2a), which in use is arranged next to a surface (50) to coat, and with a second face (2b) opposite to the first face (2a). The synthetic turf (1) comprises, furthermore, a plurality of filaments (3) knitted to the mat (2) and made of a synthetic material. Above the second face (2b) of the mat (2), furthermore, an infill material (10) is present that is arranged all around the filaments (3) of artificial material. The infill material (10) comprises, in particular at least one layer (15) consisting of a mixture of a predetermined amount of cereal husks, such as rice husks, husks of wheat, husks of rye, husks of oat, husks of spelt, or a combination thereof, and of at least one defibrated arboreus material which is resistant to microbial digestion, such as a loose final product from raw material based on coir, or sawdust of a wood obtained by a raw material with high content of lignin, such as Teck sawdust, Mahogany sawdust, Iroko sawdust, or a combination thereof.

Claims

1. An infill material installed on a synthetic turf, the infill material consisting of: a lower layer of sand having a volume set between 8% and 30% of the overall volume of the infill material, the sand having a size set between 0.4 mm and 2.0 mm; an upper layer consisting of a mixture obtained by mixing: between 1% and 10% in a percent volume of cereal husks selected from the group consisting of rice husks, oat husks, spelt husks, and combinations thereof; between 55% and 80% in a percent volume of a loose product from raw material based on coconut coir, which is resistant to microbial digestion, and which forms, in the presence of moisture, a three-dimensional reticular structure trapping the cereal husks within, and preventing release of the cereal husks from the synthetic turf, wherein the size of the loose product from raw material based on coconut coir is larger than 500 m for 90% by weight obtained by sieving a starting raw material based on coconut; and between 15% and 40% in a percent volume of a loose final product from raw material based on ground cork up to a total percentage volume of 100% of the mixture.

2. A synthetic turf consisting of: a synthetic mat having a substrate from which synthetic grass filaments project, an infill material, according to claim 1.

3. The infill material according to claim 1, wherein said raw material based on coconut coir is present in a percent volume of between 65% and 85%.

4. The infill material according to claim 1, wherein said cereal husks have a moisture content of between 5% and 15%.

5. The infill material according to claim 1, wherein said loose product from raw material based on coconut coir obtained by sieving has the following grain size: among 20% and 40% by weight is between 0.8 mm and 1.25 mm; among 15% and 35% by weight is between 1.25 mm and 1.60 mm; and among 50% and 70% by weight is larger than 1.6 mm.

6. The infill material according to claim 1, wherein said loose final product from raw material based on ground cork is present in a volume of between 20% and 35% of the overall volume of said infill material.

7. The infill material according to claim 1, wherein the percent volume of the cereal husks with respect to the total volume of the mixture is about 6%.

8. A synthetic turf for sports or recreational activities comprising a synthetic mat having a substrate from which synthetic grass filaments project, comprising an infill material according to claim 1.

9. The synthetic turf according to claim 8, wherein said synthetic grass filaments comprise: a first group of longer filaments, said first group of filaments protruding from said infill material; and a second group of shorter filaments, said second group of filaments arranged within the infill material without protruding from it, or protruding minimally from it.

10. The synthetic turf according to claim 9, wherein said filaments of said second group of filaments has a twisted shape.

11. A method for making a synthetic turf comprising the steps of: preparing a synthetic mat having a substrate from which synthetic grass filaments project; distributing, on said mat, an infill material obtaining a synthetic turf; said infill material consisting of: a lower layer of sand having a volume set between 8% and 30% of the overall volume of the infill material, the sand having a size set between 0.4 mm and 2.0 mm; an upper layer consisting of a mixture obtained by mixing: between 1% and 10% in a percent volume of cereal husks selected from the group consisting of rice husks, oat husks, spelt husks, and combinations thereof, wherein said cereal husks are obtained by subjecting a cereal to a semi-milling process carried out by two horizontal discs coated with an abrasive material; between 55% and 80% in a percent volume of a loose product from raw material based on coconut coir, which is resistant to microbial digestion, and which forms, in the presence of moisture, a three-dimensional reticular structure trapping the cereal husks within, and preventing release of the cereal husks from, the synthetic turf, wherein the size of the loose product from raw material based on coconut coir is larger than 500 m for 90% by weight obtained by sieving a starting raw material based on coconut, and between 15% and 40% in a percent volume of a loose final product from raw material based on ground cork up to a total percentage volume of 100% of the mixture.

12. The method according to claim 11, wherein the loose product from raw material based on coconut coir is obtained by sieving a starting raw material based on coconut, up to a grain size larger than 500 m for 90% by weight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be made clearer with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings in which:

(2) FIG. 1 diagrammatically shows a cross sectional view of a first exemplary embodiment of an infill material for synthetic turfs, according to the invention;

(3) figures from 2 to 4 show diagrammatically transversal cross sections of some exemplary embodiments of the infill material for synthetic turfs of FIG. 1.

DESCRIPTION OF SOME PREFERRED EXEMPLARY EMBODIMENTS

(4) With reference to FIG. 1, a synthetic turf 1, according to the invention, comprises a mat 2 equipped with a face 2a, which in use is arranged next to a surface 50 to coat, and a face 2b opposite to face 2a. The synthetic turf 1 comprises, furthermore, a plurality of filaments 3 knitted to mat 2 and made of a synthetic material. above face 2b of mat 2, furthermore, an infill material 10 is present all around the filaments 3 of artificial material.

(5) According to the invention and as shown in FIG. 1, the infill material 10 comprises at least one layer 15 consisting of a mixture of at least one measured amount of a defibrated arboreus material which is resistant to microbial digestion and of a predetermined amount of cereal husks. For example, the cereal husks can be rice husks, husks of wheat, husks of rye, husks of oat, husks of spelt, or a combination thereof. In particular, the husks comprise a by-product deriving from cereal transformation and is the set of the bracts, or hulls, which enclose the kernel. More precisely, in case of cereal such as wheat and rye, the husks do not adhere to the kernel, also called caryopsis, and therefore their separation is carried out directly during the threshing. In case of cereals like rice, oat and spelt that have, instead, husks stuck to the kernel have to be semi-milled by two horizontal discs, so-called hullers, coated with abrasive material through which the kernel is decorticated removing the husks and the glumelle. The waste deriving from semi-milling for example from brown rice, i.e. from raw rice, after threshing, gives origin to the husks known also as rice hull, or rice chaff.

(6) The cereal husks, and, in particular, the rice husks, have a high elasticity against bending of the hulls. More in detail, the cereal husks are substantially lens-shaped comprising concave portions and convex portions with rather high concavity. For these particular morphological features the cereal husks, and, in particular, the rice husks, occupy a high volume, but have a high void ratio. from which on the one hand a high elasticity derives and on the other hand a high draining action is achieved by the mixture that contains them.

(7) The defibrated arboreus material which is resistant to microbial digestion can be, instead, a loose final product of raw material based on coir, or alternatively, sawdust of a wood obtained from a raw material with high content of lignin, such as Teck sawdust, Mahogany sawdust, Iroko sawdust, or a combination thereof. In particular, the above described defibrated arboreus material which is resistant to microbial digestion, in the presence of humidity form a three-dimensional reticular pulp that holds the lighter parts of infill material 10, in particular the cereal husks, trapping them and avoiding that they can get free from the turf infill and scatter in the environment. This makes it possible to exploit fully the physical characteristics of the cereal husks, in particular its high elasticity, and to avoid at the same time that it can hamper players during sports matches.

(8) The infill material 10 can also comprise a predetermined amount of a loose final product from raw material based on ground cork. This way, mixing the ground cork to the cereal husks and to the defibrated arboreus material which is resistant to microbial digestion the physical characteristics of the infill material are further improved.

(9) In an exemplary embodiment, the infill material 10 has a composition comprising between about 1% and about 15% v/v of cereal husks, between about 55% and 85% of raw material based on coconut ground and between about 20% and 35% of ground cork. The infill material 10 can comprise, furthermore, a predetermined amount of selected sand with controlled grain size, for example set between 0.4 mm and 2.0 mm.

(10) In the exemplary embodiment shown in FIG. 2, the infill material 10 is made distributing a layer of sand 11 on face 2b of mat 2 before laying layer 15 consisting of the above described mixture of loose material of vegetable natural origin.

(11) In the exemplary embodiment of FIG. 3, the infill material 10 is obtained distributing in turn four layers of different material. In particular, a first layer 11 of sand and three layers 15a-15c, at least one of which consisting of a mixture of cereal husks with at least one defibrated arboreus material which is resistant to microbial digestion.

(12) For example, above the layer 11 of sand a layer of cork 15a is distributed, above which a layer of cereal husks 15b is made mixed to a loose product based on coconut. Furthermore, a further layer 15c can be provided comprising about exclusively a loose product based on coconut coir.

(13) In the two exemplary embodiments above described the layer of sand 11 has draining function and is, furthermore, capable of adjusting the microclimate of the synthetic turf 1. The infill material 10 has, instead, mainly the function of adjusting the outflow and the drainage of the rainwater, or irrigation water, and to ensure a suitable rate of moisture of the playground.

(14) As above described, the presence of the rice husks confers to the synthetic turf 1 appropriate physical and mechanical characteristics, necessary for the sports or recreational activities. The rice husks has, in fact, a high elasticity both if they are entire and fragmented. Furthermore, the rice husks ensure a correct drainage of water from the turf infill owing to a reduced water retention, allowing an adjustment of the outflow of water from the synthetic turf 1.

(15) In a further exemplary embodiment shown in FIG. 4, the infill material 10 provides a single heterogeneous layer consisting of a mixture of sand, cork, rice husks and loose product based on coconut ground in a determined percentage v/v. Even in this case the sand, even if mixed with the other components making up the infill material, carries out an effective draining action that avoids flooding the synthetic turf in case of strong rainfall.

(16) As shown, for example in FIG. 3, the filaments 3 of synthetic material knitted on mat 2 can comprise at least one first group of longer filaments 3, which protrude from the infill material 10 and at least one second group of filaments 3, shorter, in order to result within the infill material 10 without protruding from it, or protruding minimally from it, for example 2-3 mm. This second group of filaments 3 may have twisted shape in order to confer higher support to the infill material 10.

(17) The following are not limitative examples of the components of the infill material, according to the invention:

(18) 1) Sand

(19) Composition: siliceous sand and/or quartz with single, or aggregate crystal quartz. Minimum content of SiO2: 70% Physical state: solid Form: crystalline pH: 58 Grain size: 0.4-0.9 mm Density: 1500-1700 kg/m.sup.3
2) Organic material of vegetable origin: Composition: Vegetable natural material deriving from defibrated arboreus plant parts, biodegradable, free from extraneous material: Form: irregular Color: brown Odor: odorless Grain size: 12 mm pH: 5.06.5 Electric conductivity: 0.63 uS/cm to 25 C. Content of moisture: 5.0/20.0%.
3) Rice husks: Composition: the husks or chaff of rice, or also hulls is the waste deriving from the semi-milling of the brown rice, the raw rice obtained after threshing. The ratio of the husks on the raw rice changes according to the variety, and is set between 17 and 23 percent. Colour: brown-beige, Consistency: hard, Density: 132140 kg/m.sup.3, Features: imputrescible and not attackable by insects, Composition: proteins: 3.3% fats: 1.1% cellulose: 45%, ashes: 17%, average calorific value: 14 MJ/kg.
4) Loose product of raw material based on coconut coir: Grain size: larger than 500 micron (m) for 90% by weight,

(20) Furthermore, hereafter a table is indicated of a standard composition of infill material, according to the invention.

(21) TABLE-US-00001 Percent volume Component min max Loose product based on 55% 85% coconut coir Rice husks 1% 15% Ground cork 15% 35% Siliceous sand 0% 30%

(22) In particular, the composition of the infill material given in the table can be adjusted within the range indicated responsive to the type of weaving and of density of the filaments (tufting), of the fibers used for making the synthetic turf, as well as responsive to the environmental features and of the ground that bears the turf, providing a customized distribution of the three components.

(23) The infill material can be subject to changes concerning the succession of layers of the material, or the possible mixing of two, or all the components. For each specific case of stratification and succession, or mixing, of the material in any case is preferable to respect the percentage by weight of each element as indicated in the table 1 relative to a standard infill material standard.

EXAMPLE

(24) an infill for artificial soccer fields, comprising a layer of sand of about 8% v/v of siliceous sand and 92% of vegetable natural material.

(25) The vegetable natural material comprises 6% rice husks, 22% ground cork and 72% coconut coir from which the powder part has been removed.

(26) A similar composition, with about 6% of rice husks, about 22% ground cork and about 72% of coconut coir from which the powder part has been removed has been used successfully also with different proportions of sand from the above indicated range, and even without sand.

(27) The foregoing description of a specific embodiment 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 an embodiment without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiment. 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 employed herein is for the purpose of description and not of limitation.