PERFORMANCE INFILL FOR GRASS FIELDS, PROCESS FOR THE PRODUCTION THEREOF, AND GRASS FIELDS COMPRISING SAID PERFORMANCE INFILL

Abstract

Performance infill for grass fields is disclosed, as well as a process for the production of performance infill, and to grass fields including such performance infill.

Description

This application claims priority to Italian Patent Application No. 102022000020259 filed on Oct. 3, 2022.

TECHNICAL FIELD

The infill system is an aspect of primary importance for any artificial grass field: it represents a necessary condition for the safety of the athletes and establishes the performance levels; as a matter of fact, the infill provides appropriate damping and shock absorption, and it creates the physical-mechanical conditions for the development of the game.

BACKGROUND

Infilling a grass turf substantially means filling it with granular inert material having the double task of:

• • stabilising the turf on the ground; and
  • improving the play performance thereof.

SUMMARY

Two different types of infill are used to achieve these objects:

I) Stabiliser

As stabiliser infill for fields subject to possible approval—due to its chemical-physical properties—washed, dried and dedusted silica sand (quarziferous)—typically with particle-size comprised between 0.4 and 1.25 mm—should be used.

In the presence of high-filament turfs, the sand represents the first filling layer and it is called “stabiliser” given that its main task is to ballast the grass turf to the ground and stabilise the surface.

Although it serves the same purpose in turfs with low fibres, in this case it is the only required infill, therefore excluding the rubber layer, with the task of obtaining from the surface higher play speed and ball-control evenness (for example in tennis, football/soccer, hockey).

II) Performance

Performance infill represents the second layer of artificial grass and it consists of microgranules which can be of various types. Therefore, the main tasks to be performed by this kind of infill are:

• • saturating the surface and the spaces between the fibres which would otherwise be “empty” (filler); and
  • creating the best physical-mechanical conditions for the development of the game and the performance of the athletes (performance).

The state-of-the-art of artificial turfs lies in grass infilled not only with sand but also with elastic granules which improve play performance.

Various types of granular material are allowed for approval purposes:

• • 1) Virgin EPDM rubber made of granules, where the raw material cannot be lower than 22% (the other requirements as for thermoplastic rubber).
  • 2) Virgin thermoplastic rubber made of granules, free of dust, without recycled post-consumption components or scrap material deriving from works relating to other fields of use.
  • 3) Mixture of organic material (particles, filaments and granules of plant origin) with painted SBR rubber, or thermoplastic or virgin EPDM granules, not exceeding 30% by weight of dried product.
  • 4) Mixtures of 100% plant organic material (particles, filaments and granules), without added rubber granules.
  • 5) Granules made of vulcanised rubber, coloured and encapsulated with polyurethane resin (obtained from PFU, old tyres): the granules must be washed, without dust, metal parts and textile, painted and encapsulated with a film made of pollutant-free special polyurethane resin which maintains the elasticity and resistance characteristics typical of secondary raw material.
  • 6) Synthetic organic material made of extruded elastomeric granules together with a plant component: the latter should be at least equal to 20%.

Each of the type of infill has its advantages, and the choice may depend on the cost, or the balance between duration, elasticity, comfort, as well as the maintenance required to refill the material possibly washed out by rain.

Currently, the new European regulations prohibit the production of performance infill made of thermoplastic elastomers and vulcanised rubbers, and require that infill producers find alternative and strictly eco-friendly solutions. All plant material currently used in performance infill for artificial fields (for example made of ground coconut fibres, ground cork, corn) deteriorate rapidly over time due to their fragility and their low specific weight. They generally have the disadvantage of having to be refilled every two years.

Advantageously, and surprisingly, the present invention overcomes the disadvantages mentioned above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: image showing a sample of a grass turf comprising the performance infill of the present invention.

FIGS. 2.a-2.e: images showing the samples of a grass turf comprising the performance infill of the present invention, before and after the treatments applied with the tests carried out.

FIGS. 3.a, 3.b, 3.c and 3.d: FTIR: ATR spectrophotometric analysis:

• • 3a: sample of the present invention;
  • 3b: sample of the present invention comprising pigment and calcium carbonate;
  • 3c: sample of the present invention comprising renewable raw material and calcium carbonate;
  • 3d: unique representation of 3a, 3b and 3c (indicated as X, Y, Z).

FIGS. 4.a, 4.b and 4.c: Differential scanning calorimetry (DSC):

• • 4a: sample of the present invention;
  • 4b: sample of the present invention comprising pigment and calcium carbonate;
  • 4c: sample of the present invention comprising renewable raw material and calcium carbonate;

FIGS. 5.a, 5.b and 5c: thermogravimetric analysis (TGA):

• • 5a: sample of the present invention;
  • 5b: sample of the present invention comprising pigment and calcium carbonate;
  • 5c: sample of the present invention comprising renewable raw material and calcium carbonate;

Below is the detailed description of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to performance infill for artificial turf, wherein said performance infill comprises:

• • I) mineral filler selected from the group consisting of: talc, calcium carbonate, silica, barite, preferably calcium carbonate, wherein said filler is comprised in the range from 5-50% by weight, preferably 20-50% by weight;
  • II) plant component selected from the group consisting of: cellulose and derivatives, lignin, hemicellulose, sisal, cotton and mixtures thereof, wherein
    • said plant component is comprised in the range from 0-50% by weight, preferably 20-50% by weight; and
    • said plant component is in extruded and/or loose form;
  • III) renewable raw material, preferably polylactic acid (PLA), wherein said renewable raw material is comprised in the range from 0-50% by weight, preferably 0.5-50% by weight;
  • IV) coloured pigment comprised in the range from 0-1% by weight,
  • wherein
    • the sum of said I), II), III) and IV) is equal to 100% by weight; and
    • wherein said performance infill always comprises at least the components II) and/or III) and/or mixtures thereof.

The performance infill of the present invention has a diameter comprised in the range from 0.5-3.15 mm, according to the official FIFA requirements.

Said renewable raw material may be obtained from various sources, such as for example trees, rice, corn, preferably ground corn, sugar beet, glucose.

The expression “Sisal” is used to indicate a plant fibre obtained from the Mexican agave, a succulent plant of the Agavaceae family, originating from Yucatan in Mexico, which is very resistant, sound-insulating, anti-static.

The expression “plant component in loose form, preferably loose lignin” is used to indicate a ground plant component, preferably ground lignin.

In another embodiment, the present invention refers to use of polylactic acid (PLA) for the production of performance infill.

In another embodiment, the present invention refers to the use of lignin for the production of performance infill, wherein said lignin is loose.

Advantageously, and surprisingly, the Applicant found that the performance infill of the present invention overcomes the disadvantages of the state of the art mentioned above. Advantageously, the performance infill of the present invention is fully vegetable, eco-friendly, according to the European directives, but at the same time it does not deteriorate rapidly like the performance infill currently available on the market.

Advantageously, the performance infill of the present invention shows excellent properties in terms of elasticity, resistance to wear and bouncing of the ball, contrary to the eco-friendly products known currently.

Advantageously, the performance infill of the present invention does not require refilling in the short and long-term, thus offering the grass field comprising said performance infill a continuous efficiency and durability until normal end of useful life thereof.

Furthermore, the performance infill of the present invention, not worn out, may be recovered and regenerated through an extrusion process so as to be laid on the new grass field.

In another embodiment, the present invention relates to an extrusion process for the production of performance infill, wherein said process comprises the steps of:

• • i) loading—into a forced supply silos—a mixture comprising
    • i.1) mineral filler selected from the group consisting of: talc, calcium carbonate, silica, barite, preferably calcium carbonate, wherein said filler is comprised in the range from 5-50% by weight, preferably 20-50% by weight;
    • i.2) plant component selected from the group consisting of: cellulose and derivatives, lignin, hemicellulose, sisal, cotton and mixtures thereof,
    • wherein
      • said plant component is comprised in the range from 0-50% by weight, preferably 20-50% by weight and
      • said plant component is in extruded and/or loose form;
    • i.3) renewable raw material, preferably polylactic acid (PLA), wherein said renewable raw material is comprised in the range from 0-50% by weight, preferably 0.5-50% by weight;
    • i.4) coloured pigment comprised in the range from 0-1% by weight,
    • wherein the sum of said i.1), i.2), i.3) and i.4) is equal to 100% by weight, and wherein said mixture always comprises at least the components i.2) and/or i.3) and/or mixtures thereof;
  • ii) extrusion of the mixture obtained from step i), wherein said extrusion comprises the steps of:
    • ii.a) forced thrust of the mixture of step i) into an input chamber,
    • ii.b) thrust—through an extrusion screw—and heating the mixture obtained from ii.a) to a temperature lower than the melting of the mixture;
    • ii.c) thrust—through an extrusion screw—and melting the mixture obtained from ii.b), wherein said mixture obtained from ii.b) is molten to 60% of the total amount of the mixture;
    • ii.d) thrust—through an extrusion screw—and total melting of the mixture obtained from ii.c), amalgamating the mixture and recovering the extruded product;wherein the temperature of steps ii.a), ii.b), ii.c) and ii.d) is comprised in a range from 100-315° C.

Preferably: said temperature of step ii.a) is comprised in the range from 235-290° C.

Preferably, said temperature of steps ii.b) and ii.c) is comprised in the range from 240-295° C.

Preferably, said temperature of step ii.d) is comprised in the range from 255-315° C.

The performance infill obtained with the process of the present invention has a diameter comprised in the range from 0.5-3.15 mm, in compliance with the official FIFA requirements, and it has the advantages mentioned above, overcoming the disadvantages of the prior art.

In another embodiment, the present invention refers to artificial grass fields comprising the performance infill of the present invention for sports activities, play and sports surfaces. Preferably, said sports activities are selected from the group consisting of: football/soccer, hockey, tennis, padel, golf, rugby, artificial mixed football/soccer, natural football/soccer.

Preferably, said artificial grass field comprises:

• • Artificial grass turf;
  • Stabilising infill;
    • Performance infill according to the present invention;
  • Shock absorbing turf.

Below are some non-limiting examples aimed at showing the advantages of the present invention.

EXAMPLES

Test (and Test Conditions) Conducted on the Samples of the Present Invention

• • EN 15306:2014 (Test not subject to certification by Accredia) Surfaces for outdoor sports areas—Exposure of artificial grass to wear simulation: Conditioning of the sample for a minimum of 24 hours at 23° C.±2° C. Test conducted at a temperature of 23° C.±2° C. and 50%±5% RH (relative humidity).
  • FIFA 04a:2020 test method—Surfaces for sports areas—Shock absorption capacity: Conditioning of the sample not required. Test conducted at a temperature of 23° C.+2° C.
  • FIFA 05a:2020 test method—Surfaces for sports areas—Vertical deformation: Conditioning of the sample not required. Test conducted at a temperature of 23° C.±2° C.
  • FIFA 13:2020 test method—Surfaces for sports areas—Return of energy: Conditioning of the sample not required. Test conducted at a temperature of 23° C.±2° C.

Extended Uncertainty

• • FIFA 04a:2020 test method—Surfaces for sports areas—Shock absorption capacity: Extended uncertainty is calculated as 1.5%. Extended uncertainty is calculated with a coverage factor (k) equal to 2, corresponding to a 95% confidence.
  • FIFA 05a:2020 test method—Surfaces for sports areas—Vertical deformation: Extended uncertainty is calculated as 0.7 mm. Extended uncertainty is calculated with a coverage factor (k) equal to 2, corresponding to a 95% confidence.
  • FIFA 13:2020 test method—Surfaces for sports areas—Return of energy: Extended uncertainty is calculated as 1.6%. Extended uncertainty is calculated with a coverage factor (k) equal to 2, corresponding to a 95% confidence.

Characteristics of the Sample of the Present Invention

System made of artificial grass consisting of:

• • Artificial grass turf: straight, single-filament and two-coloured with blade height 40 mm;
  • Stabilising infill: silica sand with particle-size 0.4-1.25 mm; Filling dose 15 kg/m²;
  • Performance infill: entirely plant-green; capacity 5 kg/sqm;
  • Shock absorbing turf—EPP with total thickness of 22 mm. FIG. 1 shows an image of such sample.

Values Obtained Before 20200 Lisport Cycles

Example 1—FIFA 04a:2020 TEST METHOD—Surfaces for Sports Areas—Shock Absorption Capacity

The tests (Test 1, Test 2, Test 3) were conducted at a temperature of 23.2° C. and a relative humidity of 51.3%.

	Shock absorption
	Test 1	Test 2	Test 3
	69.4%	68.9%	69.4%
	Average of three tests	69.2%

Example 2—FIFA 05a:2020 Test Method—Surfaces for Sports Areas—Vertical Deformation

The tests were conducted at a temperature of 23.2° C. and a relative humidity of 51.3%.

	Vertical deformation
	Test 1	Test 2	Test 3
	10.0 mm	10.0 mm	10.0 mm
	Average of three tests	10.0 mm

Example 3—FIFA 13:2020 Test Method—Surfaces for Sports Areas—Return of Energy

The tests were conducted at a temperature of 23.2° C. and a relative humidity of 51.3%.

	Shock absorption
	Test 1	Test 2	Test 3
	34.3%	33.7%	35.2%
	Average of three tests	34.4%

Example 4—EN 15306:2014 Surfaces for Outdoor Areas—Exposure of Artificial Grass to Simulated Wear

The tests were carried out at a temperature of 23.0° C.±2° C.

After the wear cycle, the infill has whitened due to friction with sand, but with a very limited generation of dust. This is clearly visible in the series of images shown in FIGS. 2.a-2.e, and in particular in FIG. 2.e (referring to infill only).

The artificial grass blade of the turf has whitened for the same reason as the infill, given that it is in contact with the silica sand during the cycles. In any case, the artificial grass blades seemed flattened due to the pressure of the embosses mounted on the rollers.

Only a few artificial grass blades broke, as observable in the last series of images relating to the turf with filler (FIG. 2.d).

The new sample and the sample after wear show the same system performance, if not almost identical. This is due to the presence of the performance infill of the present invention, which guarantees high shock absorption value.

Values Obtained after 20200 Lisport Cycles

Example 5—FIFA 04a:2020 Test Method—Surfaces for Sports Areas—Shock Absorption Capacity

Tests were carried at a temperature of 22.9° C. and a relative humidity of 52.6%

	Shock absorption
	Test 1	Test 2	Test 3
	68.6%	68.3%	68.8%
	Average of three tests	68.6%

Example 6—FIFA 05a:2020 Test Method—Surfaces for Sports Areas—Vertical Deformation

Tests were carried at a temperature of 22.9° C. and a relative humidity of 52.6%

	Vertical deformation
	Test 1	Test 2	Test 3
	10.0 mm	9.0 mm	9.5 mm
	Average of three tests	9.5 mm

Example 7—FIFA 13:2020 Test Method—Surfaces for Sports Areas—Return of Energy

Tests were carried at a temperature of 22.9° C. and a relative humidity of 52.6%

	Shock absorption
	Test 1	Test 2	Test 3
	34.9%	34.9%	33.8%
	Average of three tests	34.5%

Examples 8-9-10

For EXAMPLES 8-9-10, provided below, measurement uncertainties are expressed as extended uncertainty, obtained by multiplying the uncertainty type by the coverage factor K corresponding to an about 95% confidence level. Such factor K is equal to 2.

Example 8—FTIR Analysis: ATR Spectrophotometric Analysis

Identification of the nature of sample through surface reflection analysis using FTIR Perkin Elmer series SPECTRUM ONE provided with Universal ATR kit (resolution 4 cm-1, single reflection on ZnSe crystal, 4 additive scans).

FIGS. 3.a-3.d show the spectrum of a sample of the present invention (3.a), a spectrum of a sample comprising a pigment and calcium carbonate (3.b), a spectrum of a plant sample comprising renewable raw materials and calcium carbonate (3.c), and a spectrum of comparison between the previous ones (3.a, 3.b and 3.c).

The IR analysis of the three samples shows a high correlation index between the sample of the present invention and the other two.

Example 9—Differential Scanning Calorimetry (DSC)

The analysis was conducted using the DSC technique with TA Instruments Q2000 setting the scans in the presence of an approximately 50 ml/min nitrogen flow:

• • 1^st heating: from 40° C. to 300° C. with gradient of 10° C./min;
  • cooling: from 300° C. to 40° C. with gradient of −10° C./min;
  • 2^nd heating: from 40° C. to 300° C. with gradient of 10° C./min.

Analysis conducted according to the ASTM D3418-21 standard. FIGS. 4.a-4.c show the spectra.

The DSC analysis shows that the sample of the present invention has characteristic melting peaks observed and comparable even in the thermograms obtained from the analysis of the other samples; specifically at 83.3° C. like in the sample with pigment (84.7° C.) and 126.5° C./157.3° C. like in the Plant sample from renewable materials (125.0° C./152.5° C.).

Example 10—TGA: Thermogravimetric Analysis

Thermogravimetric analysis conducted to quantitatively determine the weight loss of the sample when heating and verifying the presence of mineral load present in the tested sample.

The test was conducted in the presence of a 50 ml/min nitrogen flow, starting from 30° C. up to 900° C., using a heating ramp of 20° C./min with a TA INSTRUMENTS TGA550 instrument.

FIGS. 5.a-5.b and 5.c show the spectra.

The TGA analysis shows that the sample of the present invention has thermal decomposition excursions observed and comparable even in the thermograms obtained from the analysis of the other two samples.

Claims

1) A performance infill for artificial turf, wherein said performance infill comprises: I) mineral filler selected from the group consisting of: talc, calcium carbonate, silica, barite, wherein said filler is comprised in the range from 5-50% by weight;II) plant component selected from the group consisting of: cellulose and derivatives, lignin, hemicellulose, sisal, cotton and mixtures thereof,wherein said plant component is comprised in the range from 0-50% by weight, andsaid plant component is in extruded or loose form;III) renewable raw material, wherein said renewable raw material is comprised in the range from 0-50% by weight;IV) coloured pigment comprised in the range from 0-1% by weight,wherein the sum of said I), II), III) andIV) is equal to 100% by weight; andwherein said performance infill always comprises at least the components II) or III) or mixtures thereof.

2) The performance infill according to claim 1, wherein said performance infill has a diameter comprised in the range from 0.5-3.15 mm.

3) A process for the production of performance infill, wherein said process comprises the steps of: i) loading—into a forced supply silos—a mixture comprisingi.1) mineral filler selected from the group consisting of: talc, calcium carbonate, silica, barite, wherein said filler is comprised in the range from 5-50% by weight;i.2) plant component selected from the group consisting of: cellulose and derivatives, lignin, hemicellulose, sisal, cotton and mixtures thereof, wherein said plant component is comprised in the range from 0-50% by weight, andsaid plant component is in extruded or loose form;i.3) renewable raw material, wherein said renewable raw material is comprised in the range from 0-50% by weight;i.4) coloured pigment comprised in the range from 0-1% by weight,wherein the sum of said i.1), i.2), i.3) and i.4) is equal to 100% by weight, and whereinsaid mixture always comprises at least the components i.2) and/or i.3) or mixtures thereof.ii) extrusion of the mixture obtained from step i),wherein said extrusion comprises the steps of: ii.a) forced thrust of the mixture obtained from step i) into an input chamber,ii.b) thrust—through an extrusion screw—and heating the mixture obtained from ii.a) to a temperature lower than the melting of the mixture;ii.c) thrust—through an extrusion screw—and melting the mixture obtained from ii.b), wherein said mixture obtained from ii.b) is molten to 60% of the total amount of the mixture;ii.d) thrust—through an extrusion screw—and total melting of the mixture obtained from ii.c), amalgamating the mixture and recovering the extruded product;

4) The process according to claim 3, wherein: said temperature of step ii.a) is comprised in the range from 235-290° C.;said temperature of steps ii.b) and ii.c) is comprised in the range from 240-295° C.;said temperature of step ii.d) is comprised in the range from 255-315° C.

5) An artificial grass field comprising performance infill according to claim 1 for sports activities, play grounds and sports surfaces.

6) The artificial grass field according to claim 5, wherein said sports activities are selected from the group consisting of: football/soccer, hockey, tennis, padel, golf, rugby, artificial mixed football/soccer, natural football/soccer.