Field of the invention

The present invention relates to the field of turfs and in particular to a hybrid turf.

Known art

As known, hybrid turfs are portions of soil comprising natural (grass) and synthetic fibers, suitably interspersed, to obtain portions of lawn. The reinforcement imparted to natural fibers (natural grass) by synthetic fibers (artificial grass) ensures stability and a uniform playing surface immediately after installation.

The grass crown (heart) is then located between the artificial fibers covered with sand, where it is protected from wear and tear damage.

In some cases, synthetic turfs are constrained in an open-weave backing, clogged with specific sand.

In other cases, synthetic turfs do not provide backing elements and are directly "sewn" into the soil.

The Applicant has observed that whenever a new hybrid turf mat is to be installed at a site of use, the synthetic components of the old worn-out hybrid turf mat must be completely removed from the soil before the new hybrid turf can be installed. Removing the worn-out hybrid turf mat may not be easy, as the hybrid turf mat is often strongly interconnected with the roots of natural herbaceous plants. The disposal of the worn-out hybrid turf mat is challenging because the mixture of natural grass, dirt and synthetic materials, if undivided and washed, cannot be recycled, is expensive to dispose of and, therefore, has a strong environmental impact.

The Applicant has therefore observed that an ever increasing number of producers of hybrid and artificial grass have begun to replace the conventional fibers and backing materials with biodegradable materials.

For example, the International Patent Application WO 2007/114686 describes the use of biodegradable synthetic fibers consisting of starch and polylactic acid.

The Applicant has however observed that the biodegradable fibers used to date do not allow a precise estimate of the biodegradability timings. In fact, biodegradation is a process that depends on a plurality of environmental factors and on the actual life expectancy of an artificial or hybrid turf mat.

The Applicant has posed the problem of implementing a hybrid turf which is easy and economical to replace and dispose of and whose disposal does not result in a great environmental impact.

The Applicant has also posed the problem of implementing a hybrid turf which has precise biodegradability timings.

The Applicant has also posed the problem of the environmental impact of the current plastics used for this application, since they are in direct contact with the soil and aquifers.

Summary of the invention

Therefore, the invention, in a first aspect thereof, relates to a hybrid turf comprising a plurality of synthetic fibers grouped in skeins, each comprising a plurality of filiform elements; characterized in that it comprises a first biodegradable net;

- said first biodegradable net and/or said filiform elements comprising a polymeric composition comprising a polymer selected from the group consisting of polyhydroxyalkanoate (PHA), copolymer of 1,4-butanediol, succinic acid and adipic acid (PBSA), polybutylene succinate (PBS) or mixtures thereof;

- said first net /or said filiform elements (12) comprising at least one nucleant selected from the group consisting of Boron Nitride, Talc, Hydroxyapatite, Zinc Stearate, Nanocrystalline Cellulose, Montmorillonite nano-clay, Single-wall carbon nanotubes, Multi -wall carbon nanotubes, Cyanuric acid, Fatty acids, Fatty acid esters, Fatty acid amines, Fatty acid metal salts, pentaerythritol, di-pentaerythritol, urea derivatives, sorbitol-based compounds, sodium benzoate and mixtures thereof;

- said first net and/or said filiform elements (12) comprise at least one functional additive selected from the group consisting of Pentaerythrole tetrakis(3-(3,5-di-tert-butyl- 4-hydroxyphenyl)propionate), Octadecyl 3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate, Tris(2,4-di-tert-butylphenyl)phosphite, 1,3,5-Trimethyl- 2,4,6-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,4-Bis[(octylthio)methyl)]-o- cresol, 2,2'-dihydroxy-4,4'-dimethoxy-benzophenone, Ethylene bis(oxyethylene)-bis-(3- (5-tert-butyl-4-hydroxy-m-tolyl)propionate), Octadecyl-[3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate, 2',3-Bis[[3-[3,5-di-tert-butyl-4- hydroxyphenyl]propionyl]]propionohydrazide, Beeswax, Carnauba wax, Candelilla wax, Sumac wax (Japanese wax), Berry wax, Paraffin wax, Silicone and its derivatives, and mixtures thereof.

The present invention, in the aforementioned aspect, can have at least one of the preferred characteristics hereinafter described.

Preferably, the first net comprises at least one copolymer of 1,4-butanediol, succinic acid and adipic acid (PBSA) and polyhydroxyalkanoate.

Advantageously, said polyhydroxyalkanoate (PHA) is present in an amount by weight to the amount of total polymers.

Preferably, said polyhydroxy alkanoate (PHA) is present in an amount between 10 and 90% by weight to the total amount of polymers in the polymeric composition.

Conveniently, said first net or said filiform elements comprise at least one plasticizer selected from the group consisting of poly(ethylene glycol) (PEG), acetyl-tri- n-butyl citrate (ATBC), isosorbide diester (ISE), sorbitol, glycerol, Acetylated monoglycerides, Epoxidized soybean oil (ESBO), Triethyl citrate (TEC), tri(ethylene glycol)-bis-(2-ethyl hexanoate) (TEG-EH), Tributyl citrate (TBC), 1,3,2,4-dibenzylidene sorbitol, l,3-p-methylbenzylidene-2,4-benzylidene sorbitol, bis-(stearylureide) hexane, 1,3, 2, 4-di-(p-m ethylbenzylidene) sorbitol, 1,3,2,4-dibenzylidene sorbitol, and mixtures thereof.

Conveniently, said first net /or said filiform elements (12) comprise at least 80% by weight to the respective total weight of a polymeric composition comprising a polymer selected from the group consisting of polyhydroxyalkanoate (PHA), copolymer of 1,4- butanediol, succinic acid and adipic acid (PBSA), polybutylene succinate (PBS) or mixtures thereof.

Preferably, the first net /or said filiform elements comprise at least one nucleant selected from the group consisting of Boron Nitride, Nanocrystalline Cellulose, Montmorillonite nano-clay, pentaerythritol, di-pentaerythritol, and mixtures thereof. Advantageously, the first net and/or said filiform elements comprise at least one functional additive selected from the group consisting of Beeswax, Carnauba wax, Candelilla wax, Sumac wax (Japanese wax), and mixtures thereof.

Preferably, the first net and/or said filiform elements comprise at least one viscosity modifier and/or compatibilizer selected from the group consisting of DCP dicumyl peroxide, TBPB of tert-Butylperoxybenzoate, Hexamethylene diisocyanate (HMDI), Multi-functionalized styrene-co-glycidyl methacrylate oligomer (Joncryl®), Triglycidyl isocyanurate (TGIC), Benzoyl peroxide (BPO), Methylene diphenyl diisocyanate (MDI).

Conveniently, the hybrid turf comprises a backing element for the plurality of synthetic fibers; said backing element comprising at least one first layer comprising a second net that is made of natural organic material comprising meshes defining a plurality of openings configured so as to allow natural grass to take root therein, and at least one second layer, coupled to said first layer, said second layer comprising said first net.

Preferably, the hybrid turf comprises a plurality of grass blades interspersed with the plurality of synthetic fibers.

Conveniently, the second net includes meshes, each mesh being able to be inscribed in a square with side in the range between 0.2 cm and 2 cm.

Further characteristics and advantages of the invention will be more evident from the detailed description of some preferred, but not exclusive, embodiments of a hybrid turf according to the present invention.

Brief description of the drawings

Such description will be set forth herein with reference to the attached drawings provided for illustration purposes only and without limitation, in which:

- Figure 1 shows a schematic perspective view of a first embodiment of the hybrid turf according to the present invention, with a partially exploded part;

- Figure 2 shows a schematic side view of a skein of filiform elements comprising synthetic fibers;

- Figure 3 shows a schematic perspective view of a second embodiment of the hybrid turf according to the present invention; - Figure 4 shows Table 1 with 9 examples of the composition of the first net and/or filiform elements according to the present invention; and

- Figure 5 shows a series of biodegradability tests, performed on different samples of the first net and/or filiform elements according to the present invention.

Detailed description of embodiments of the invention

With reference to the figures, a turf, preferably a hybrid turf according to the present invention, is denoted by the numerical reference 10.

In Figure 1 is shown that a first embodiment of the hybrid turf 10 according to the present invention comprises a backing element 2 and a plurality of synthetic fibers 3 combined with the backing element 2.

The hybrid turf 10 further comprises a plurality of grass blades 15 which are alternated with the synthetic fibers 3, so as to make a substantially continuous mat of grass blades 15 and synthetic fibers 3.

When installed, the backing element 2 may have a substantially planar configuration comprising at least one first layer 4 made of a second net 5 made of a natural organic material, preferably cotton.

Preferably, the second net 5 comprises meshes defining a plurality of openings configured so as to allow the natural grass blades 15 to root inside it.

For this purpose, the second net 5 comprises meshes 8 being able to be inscribed in a square with side in the range between 0.1 cm and 2 cm.

In the embodiment shown in Figure 1, the backing element 2 also comprises a second layer 6 made of a first net 7 made of a biodegradable polymeric composition.

Preferably, the biodegradable polymeric composition making the first net 7 is the same as the synthetic fibers 3.

The first net 7 comprises meshes 9 defining a plurality of openings.

For this purpose, the first net 7 comprises meshes 9 being able to be inscribed, in plan view, in a square with side in the range between 0.2 cm and 2 cm.

In the embodiment shown in Figure 1, the first layer 4 is combined with the second layer 6.

Preferably, the first layer 4 is combined with the second layer 5 by hot-melt gluing. Even more preferably, the first layer 4 is combined with the second layer 6 by a hot-lamination process.

In production, during the step of combining the first layer 4 with the second layer 6, there is substantial overlap between the meshes 8 of the second net 5 with the meshes 9 of the first net 7, so as to leave the openings adapted to allow the natural grass to cross the layers and take root thereunder.

In the embodiment shown in Figure 1, a plurality of synthetic fibers 3 made of a biodegradable compound, which is described in more detail below, are constrained to the backing element 2 constituted by the first 4 and second 6 layers combined together.

The synthetic fibers 3 are grouped into skeins 11 evenly distributed on the turf 10.

The synthetic fibers 3 are grouped into skeins 11 evenly distributed on the hybrid turf 10, so as to form a fiber density per m ² (square meter) in the range between 45000 fibers/m ² and 80000 fibers/m ² .

Each skein 11, better shown in Figure 2, comprises a plurality of filiform elements 12 made of a biodegradable compound, described in more detail below.

The synthetic fibers 3 are thus depicted by the filiform elements 12.

Each skein 11 comprises a number of filiform elements 12 or synthetic fibers 3 ranging from five to fifteen, preferably from six to twelve.

In each skein 11, the filiform elements 12 have the same extent ranging from 2 to 20 cm, including extremes.

In each skein 11, the filiform elements 12 are twisted together for at least a length T of their extent.

Preferably, in every skein 11, the filiform elements 12 are twisted together for at least 1/3 of their extent.

Preferably, in every skein 11, the filiform elements 12 are twisted together for at least 2/3 of their extent.

In the embodiment shown in figure 1, the skeins 11, suitably folded on themselves, preferably so as to form a “V”, are combined with the backing element 2 by means of sewing.

Preferably, in the embodiment shown in figure 1, the skeins 11, suitably folded on themselves, preferably so as to form a “V”, are combined with the backing element 2 by means of a sewing process referred to as “tufting”.

As previously mentioned, the synthetic fibers 3 and/or the first net 7, preferably both, are made of a biodegradable polymeric composition comprising a polymer selected from the group consisting of polyhydroxyalkanoate (PHA), copolymer of 1,4-butanediol, succinic acid and adipic acid (PBSA), polybutylene succinate (PBS) or mixtures thereof.

Preferably, the synthetic fibers 3 and/or the first net 7, preferably both, comprise at least one copolymer of 1,4-butanediol, succinic acid and adipic acid (PBSA) and polyhydroxy alkanoate.

Advantageously, said polyhydroxyalkanoate (PHA) is present in an amount by weight to the amount of total polymers.

Preferably, the polyhydroxyalkanoate (PHA) is present in an amount between 10 and 90% by weight to the total amount of polymers in the polymeric composition.

In particular, with reference to the examples in the table 1. A PHA mixture refers to a mixture of PHB and PHBH.

Preferably, PHA of a preferred embodiment has a weight average molecular weight (M) that can range from 10,000 to 1,000,000.

PHA is preferably produced by microbial fermentation of an organic substrate, e.g., carbohydrate or other fermentable substrates such as glycerol, by a strain of microorganisms capable of producing PHA, and subsequent recovery of PHA from the cell mass.

In particular, the PHA production can be obtained by fermentation of suitable substrates, processing plants, e.g., juice, molasses, pulp from processing of sugar beet and sugar cane. These substrates generally contain, in addition to sucrose and other carbohydrates, organic growth factors, nitrogen, phosphorus and/or other minerals useful as nutrients for cell growth. An alternative is glycerol, a cheap source of organic carbon, being a by-product of biodiesel production, which can optionally be used in a mixture with levulinic acid.

PBSA refers to a copolymer of 1, 4-butanediol, succinic acid and adipic acid.

PBSA is prepared by adding adipic acid to the starting materials during PBS synthesis. Although usually synthesized from fossil fuels, it is also possible that the monomers that make up PBSA are produced from biomaterial feedstocks based on PBSA that degrades faster than PBS, but PBS and PBSA biodegrade more slowly than PHA.

PBS refers to a polybutylene succinate polymer preferably semi-crystalline and preferably produced by bacterial fermentation. According to a preferred embodiment, the biodegradable net comprises a polymeric composition comprising at least one polymer selected from the group consisting of: polymers based on polyhydroxyalkanoate (PHA), copolymer of 1,4-butanediol, succinic acid and adipic acid (PBSA) or polybutylene succinate (PBS). In the following, when percentages are given, they refer to percentages by weight to the total weight of the composition.

According to an even more preferred embodiment, the synthetic fibers 3 and/or the first net 7, preferably both, comprise at least 80% by weight of a polymeric composition of one or more polymers selected from the group consisting of: polymers based on polyhydroxyalkanoate (PHA), copolymer of 1,4-butanediol, succinic acid and adipic acid (PBSA) or polybutylene succinate (PBS) together with one or more additives.

According to an even more preferred embodiment, the synthetic fibers 3 and/or the first net 7, preferably both, are made of a polymeric composition of one or more polymers selected from the group consisting of: polymers based on polyhydroxyalkanoate (PHA), copolymer of 1, 4-butanediol, succinic acid and adipic acid (PBSA) or polybutylene succinate (PBS) together with one or more additives.

Additives refer to substances that improve some of the mechanical or chemical characteristics of the composition. Among PHAs, polyhydroxybutyrate (PHB) is preferred, even more preferably a mixture of PHB and poly (3-hydroxybutyrate-co-3- hydroxyhexanoate) (PHBH) is used.

Process additives and stabilizers are added to the polymeric composition. Preferably a mixture of PHA and PBSA is used, and even more preferably in this case PBSA is added in amounts of 0.06% to 49% by weight.

Preferably, the polymeric composition does not comprise PLA or polylactic acid.

Preferably, the polymeric composition is added in an amount of 50.00% to 99.95% by weight to the total weight of all net components.

Preferably the synthetic fibers 3 and/or the first net 7, preferably both, comprise at least one plasticizer selected from the group consisting of polyethylene glycol) (PEG), acetyl-tri-n-butyl citrate (ATBC), isosorbide diester (ISE), sorbitol, glycerol, Acetylated monoglycerides, Epoxidized soybean oil (ESBO), Triethyl citrate (TEC), tri(ethylene glycol)-bis-(2-ethyl hexanoate) (TEG-EH), Tributyl citrate (TBC), 1,3,2,4-dibenzylidene sorbitol, l,3-p-methylbenzylidene-2,4-benzylidene sorbitol, bis-(stearylureide) hexane, 1,3, 2, 4-di-(p-m ethylbenzylidene) sorbitol, 1,3,2,4-dibenzylidene sorbitol, and mixtures thereof. Preferably, the plasticizer is added in an amount of 0 to 50% by weight. More preferably between 5 and 30% by weight, even more preferably between 0 and 10% by weight.

Preferably, the first net 7 /or said filiform elements 12 comprise at least one nucleant selected from the group consisting of Boron Nitride, Talc, Hydroxyapatite, Zinc Stearate, Nanocrystalline Cellulose, Montmorillonite nano-clay, Single-wall carbon nanotubes, Multi -wall carbon nanotubes, Cyanuric acid, Fatty acids, Fatty acid esters, Fatty acid amines, Fatty acid metal salts, pentaerythritol, di-pentaerythritol, urea derivatives, sorbitol-based compounds, sodium benzoate and mixtures thereof.

Preferably, the nucleant is added in percent by weight between 0.05 and 1.5% by weight, more preferably between 0.05 and 1%, e.g., 0.5% by weight.

Preferably the first net 7 and/or said filiform elements 12 comprise at least one functional additive selected from the group consisting of Pentaerythrole tetrakis(3-(3,5- di -tert-butyl -4- hydroxyphenyl)propionate), Octadecyl 3 -(3, 5 -di -tert-butyl -4- hydroxyphenyl)propionate, Tris(2,4-di-tert-butylphenyl)phosphite, 1,3,5-Trimethyl- 2,4,6-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,4-Bis[(octylthio)methyl)]-o- cresol, 2,2'-dihydroxy-4,4'-dimethoxy-benzophenone, Ethylene bis(oxyethylene)-bis-(3- (5-tert-butyl-4-hydroxy-m-tolyl)propionate), Octadecyl-[3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate, 2',3-Bis[[3-[3,5-di-tert-butyl-4- hydroxyphenyl]propionyl]]propionohydrazide, Beeswax, Carnauba wax, Candelilla wax, Sumac wax (Japanese wax), Berry wax, Paraffin wax, Silicone and its derivatives, and mixtures thereof. More preferably, the functional additive is selected from the group consisting of Bees Wax, Carnauba Wax, Candelilla Wax, Sumac Wax (Japanese wax) that made it possible to achieve particularly useful results in the nets. Each functional additive is preferably added in a percentage by weight between 0.05 and 5%, more preferably between 0.05 and 1% by weight.

Preferably, the first net 7 and/or the filiform elements 12 comprise at least one viscosity modifier and/or compatibilizer selected from the group consisting of DCP dicumyl peroxide, TBPB of tert-Butylperoxybenzoate, Hexamethylene diisocyanate (HMDI), Multi-functionalized styrene-co-glycidyl methacrylate oligomer (Joncryl®), Triglycidyl isocyanurate (TGIC), Benzoyl peroxide (BPO), Methylene diphenyl diisocyanate (MDI).

Preferably, they are viscosity modifiers and compatibilizers added in a percentage between 0.001 and 1% by weight individually and overall between 0.05 and 2% by weight. Table 1 in Figure 4 shows 9 different compositions according to the present invention of the first net 7 and/or filiform elements 12 with their most relevant mechanical properties for making nets, e.g., elongation and flexural modulus.

It can be easily observed that the use of a material selection according to the present invention allows the chemical components to be appropriately modulated according to the desired mechanical properties, while maintaining a high degree of biodegradability as confirmed by the samples tested in Figure 5.

When the hybrid turf is planted on already prepared soil, it is filled with sand 14 so that the latter has a depth of at least 10 cm relative to the backing element 2, preferably a depth of at most 30 cm relative to the backing element 2.

Sands 14 suitable for the purpose are silica sands of various grain sizes, preferably USGA certified.

Once filled with sand 14, the hybrid turf 10 is sown so that the grass blades 15 can take root and develop between a skein 11 and the next one.

As the roots of the grass blades 15 grow, they pass through the meshes of the backing element 2, thus constraining the hybrid turf 10 to the underlying soil.

An alternative embodiment of the hybrid turf 10 according to the present invention is shown in Figure 3. In particular, the hybrid turf 10 of figure 3 is completely similar to the hybrid turf of figure 1, except that it does not have any backing element 2 and that the skeins 11 can have a larger dimension.

According to this embodiment, the skeins 11, suitably folded on themselves, preferably so as to form a “V”, are not combined with the backing element 2 (which is not present) but with the soil through suitable “sewing” machines.

This hybrid turf, as evident from the above description, has the following advantages:

- it allows to reduce the environmental impact of the disposal compared to conventional hybrid turfs; - it allows to reduce or eliminate disposal costs;

- construction simplicity combined with high reliability;

- precise timings of biodegradability.

Several changes can be made to the embodiments described in detail, all anyhow remaining within the protection scope of the invention as defined by the following claims.