TECHNICAL FIELD

The present invention relates to artificial turf, in particular for landscaping.

BACKGROUND OF THE INVENTION

Artificial turf is a surface of synthetic fibers made to look like natural grass. It is often used as a sportsfield, a playground, a residential lawn or for landscaping purposes.

Artificial turf comes in various qualities, from low-end mats with limited quality to high- end mats with a more natural look or improved comfort and quality for sports. The cheapest qualities typically are low-pile mats wherein the synthetic fibers are flat- shaped tapes. These mats have a reduced lifetime and beyond the fact that they are green, do not resemble real grass.

The high-end qualities come in different forms, depending on the use of the mats. For sports, the mats are configured to provide sufficient comfort (shock-absorption), resiliency and elasticity (e.g. for good ball bouncing effect), and may comprise infills. Professional sports-turf is moreover bound to specific requirements, set by sports federations such as FIFA. For residential lawns and landscape, the requirements are somewhat different, with the biggest requirement that they look like natural grass.

Despite the many efforts to make artificial turf look more natural, there is still a need for further improvement.

It is therefore an object of the present invention to provide artificial turf that looks more natural than artificial turf available today.

It is a further object of the present invention to provide high-pile natural-looking grass that can be made in an economical way. SUMMARY OF THE INVENTION

The present invention relates to artificial turf comprising a. a backing having an upper and a lower surface; and

b. a plurality of first synthetic grass fibers attached to and extending upward from the upper surface of said backing; and

c. a plurality of second synthetic grass fibers attached to and extending upward from the upper surface of said backing; characterised in that the height of the first synthetic grass fibers is higher than the height of the second synthetic grass fibers.

DRAWINGS

Fig 1 shows an artificial turf (100) according to an embodiment of the present invention, comprising a backing (200), a plurality of first synthetic grass fibers (300), and a plurality of second synthetic grass fibers (400). The first synthetic grass fibers (300) are longer than the second synthetic grass fibers (400).

Fig. 2 shows an another embodiment of an artificial turf (100) of the present invention, comprising thatch yarns (500).

DETAILED DESCRIPTION OF THE INVENTION Artificial turf according to the present invention comprises a backing. The term "backing" as used herein refers to a substrate, preferably a thermoplastic substrate, which can be woven or nonwoven. The backing has an upper and a lower surface, and the backing is configured for supporting synthetic grass fibers.

The term "synthetic grass fibers" as used herein, refers to elongated objects which are attached to the backing. When attached to the backing, the synthetic grass fibers protrude from the upper surface of the backing, and form the grass surface. Synthetic grass fibers include synthetic extruded fibers (monofilaments) and (slit-film) tapes. Preferably, the artificial fibers are arranged in bundles, preferably in bundles of monofilaments. The synthetic grass fibers preferably have a dtex from 250-2500, and one bundle may contain 4 to 20 fibers.

The synthetic grass fibers are manufactured from materials chosen from the list comprising polypropylene (PP); any variant of polyethylene (PE) including low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE)); polyester (PET); and polyamide (PA). Preferably, the synthetic grass fibers are manufactured from LLDPE to provide more softness and improved resiliency. The synthetic grass fibers used in the artificial turf of the present invention may further comprise additives selected from, but not limited to, the group of infrared reflectants, UV stabilisers, fire-retardants, matting agents, luminescent compounds (phosphorescent or fluorescent compounds), fillers (e.g. chalk, talk).

The synthetic grass fibers may have a cross-section selected from, but not limited to, a rectangular, a diamond-shape, a round, an elliptical, a multilobal (Y, X), a C-shaped, a V-shaped, a W-shaped, a S-shaped or a Ω-shaped cross-section, and have dimensions of e.g. 50-500 μιτι thickness and 0.5-5.0 mm width. The synthetic grass fibers may further comprise a backbone nerve, and/or a micro-textured surface to resemble grass blade nerves to further improve the resemblance to natural grass blades. The synthetic grass fibers are typically in a green colour e.g. a uni-colour or a mixed shade of green and other colours.

The synthetic grass fibers may be tufted or woven through the backing. Preferably, the fibers are tufted through the backing. In some embodiments, the synthetic grass fibers may be formed in loop piles or cut piles. The synthetic grass fibers are preferably arranged in bundles of fibers. Typically, 6-10 and preferably 8 monofilaments are present per bundle.

The artificial turf of the present invention comprises first and second synthetic grass fibers which are attached to, and extend upward from the upper surface of the backing. The height of the plurality of first synthetic grass fibers is higher than the height of the plurality of second synthetic grass fibers. Preferably, the average difference between the height of the plurality of first and second synthetic grass fibers is at least 6 mm, in some embodiments at least 10 mm, but typically less than 20 mm (but greater height differences are not excluded). The first synthetic grass fibers preferably have a height from 20 mm to 80 mm. The height of the second synthetic grass fibers is preferably from 10 mm to 70 mm. The height is determined from the upper surface of the backing to the top of the extended fibers, in a normal state of the turf. As there may be some variation in height between individual fibers, the height of the first and second synthetic grass fibers can be determined by taking the average height of 10 of each of the first and second fibers of the turf.

Various height combinations for first and second artificial fibers are possible, some of which are described hereinafter.

In one embodiment, the artificial turf is a high-pile turf and comprises first artificial fibers having a height from 35 mm to 80 mm, and second artificial fibers having a height from 25 mm to 65 mm. The difference in height between first and second synthetic grass fibers is at least 6 mm, but is preferably at least 10 mm. This embodiment is a very economical way of creating a high-pile carpet, yet using a lot less material.

In another embodiment, the artificial turf is a low-to-mid pile turf and comprises first artificial fibers having a height from 20 mm to 40 mm, and wherein the second artificial fibers have a height from 10 mm to 34 mm. The difference in height between first and second synthetic grass fibers is at least 6 mm, and for a low-to-mid pile turf the difference in height is preferably not more than 10 mm.

In yet another embodiment, the artificial turf has first artificial fibers and second artificial fibers having a more extreme height difference. For example the first artificial fibers may have a height from 50-80mm or even 60-80mm, while the second artificial fibers have a height from 10-30mm, or even 10-20mm.

In some embodiments, the artificial turf may further comprise a plurality of third, or even fourth, synthetic grass fibers, wherein the height of the plurality of third and/or fourth synthetic grass fibers lies in-between the heights of the first and second synthetic grass fibers. The use of third and/or fourth synthetic grass fibers would further improve the natural look of the artificial grass. The third and fourth synthetic grass fibers may have an average height difference versus the first and second synthetic grass fibers, respectively, of 3-10 mm.

The higher, first (and optional third) synthetic grass fibers are preferably monofilaments as these are most prominently visible and more resemble real grass blades. This may be less of importance for the lower, second (and optional fourth) synthetic grass fibers as these are less visible to the human eye. The selection of the lower synthetic grass fibers may further depend on other aspects, such as providing support to the higher artificial grass fibers. However, in a highly preferred embodiment, all synthetic grass fibers of the artificial turf of the present invention are monofilaments.

In a preferred embodiment, at least the first (and optional third) synthetic grass fibers, and more preferably all synthetic grass fibers of the artificial turf of the present invention, are upright-oriented cut-pile fibers, and even more preferably, the synthetic grass fibers are arranged in bundles of synthetic grass fibers.

The first, second and optional third or fourth, synthetic grass fibers may be the same in composition, shape, cross-section, resiliency, colour, and/or colour hue. However, to improve the natural look and feel of the artificial turf, the various first, second, and optional third and fourth synthetic grass fibers may be different in composition, shape, cross-section, resiliency, colour, and/or colour hue. Even more preferably, within one bundle of artificial grass fibers, fibers with different properties may be combined. For example, synthetic grass fibers with a different composition, cross-section, colour and/or colour hue are present in a given bundle of fibers. In one embodiment, the synthetic grass fibers may be totally randomized within a given bundle of fibers. For example, synthetic grass fibers may be used which have an irregularly-shaped cross-section along their length, as described in co-pending European patent application n° 15202837.9, entitled "Artificial Turf Monofilaments". In preferred embodiments of the artificial grass of the present invention, variations between the high (first and optionally third) and the low (second and optionally fourth) artificial grass fibers may be present:

- resiliency: low fibers are preferably more resilient than high fibers. The low fibers will better support the high fibers.

- shape: high fibers preferably have a cross-section which resembles more the natural grass fibers, for example diamond-, S- or V-shape.

- dtex: low fibers preferably have a lower dtex than high fibers.

- colour: through colour variations, the age of artificial turf can be created. For example, low fibers may be lighter, resembling young growing grass leaves. In another example, the low fibers may be darker resembling older cut grass leaves. Preferably, high fibers are lime green and low fibers are olive green.

The synthetic grass fibers are preferably arranged as bundles of fibers. The first, second, and optional third or fourth, synthetic grass fibers are preferably arranged in separate rows. For each type of fibers (first, second, optional third and fourth), a separate bar is used with x number of positions along the width of the turf, to insert the fibers through the backing. During production, the respective bars and thus the resulting rows of fibers are perpendicular to the machine direction.

In one embodiment, rows of first (high "H") artificial fibers are alternated with rows of second (low "L") synthetic grass fibers. This leads to a LHLHLHLH ... arrangement.

However, in a more preferred embodiment, the rows of first and second synthetic grass fibers are arranged in a more random pattern, to further improve the natural look of the artificial turf. This leads to arrangements such as e.g. LLLHHLHHHLLLHLLHHL... In this more random arrangement, it is however highly preferred that there is at least one row of first synthetic grass fibers after not more than 3, and preferably not more than 2, rows of second synthetic grass fibers, to prevent unwanted stripes to be visually present. Overall, it is preferred that there are more rows of lower height fibers. This has the additional advantage that an artificial turf can be created with good natural look while using less material. Accordingly, in some preferred embodiments, rows of first and second synthetic grass fibers are arranged in a random pattern, with the provision that a row of first synthetic fibers is present after not more than 3 rows of second synthetic grass fibers.

Preferably, the distance between fibers or between bundles of fibers in a given row (stitches) is from 6-32, preferably from 10-18, per 10cm. The distance between consecutive rows of fibers (gauge) is preferably ¾, 3/8, 3/16 or 5/16 inch.

In other embodiments, it may be envisaged to omit (by not tufting fibers) certain positions in a given row, especially for the high artificial fibers. Alternatively, it may be envisaged to tuft the high fibers only at selected positions by means of computer controlling (randomizer). This would lead to differentiation/randomisation of the artificial turf also in the cross-machine direction, thereby further improving the natural look of the turf. Accordingly, in some embodiments, the first synthetic grass fibers are randomly tufted across the artificial turf.

In another embodiment, an artificial turf is created with alternating areas of dark and light green fibers, as is typically present on sports fields. This can be effected by tufting rows of dark green first grass synthetic fibers, alternated with rows of lighter green synthetic grass fibers.

In a further embodiment, the artificial turf of the present invention may comprise thatch yarns, which extend upward from the upper surface of the backing. Thatch yarns are made of monofilaments or slit film tapes which have been textured (curled), and simulate grass roots or moss. Preferably, thatch yarns are inserted together with other fibers in a given bundle of fibers. As such, they are not present as separate rows between the rows of synthetic grass fibers. Preferably, the thatch yarns are incorporated in the bundles of the lowest synthetic grass fibers, i.e. the bundles of second synthetic grass fibers. Preferably, thatch yarns are inserted in random bundles of synthetic grass fibers, or only in certain areas of the turf

In some embodiments, the artificial turf of the present invention is provided on a roll for installation. In some embodiments, the width of the artificial turf is from at least 2 m to at most 4 m and the length of the artificial turf is from at least 10 m to at most 30 m. Alternatively, the artificial turf may be provided in the form of tiles for installation, which may comprise interlocking pieces. The interlocking means may be part of a backing onto which the artificial turf is attached.

In some embodiments, the artificial turf may further comprise additional backing layers (attached to the lower surface of the backing, to protect the synthetic grass fiber attachments) and/or a cushioning layer for improved walking comfort. The backing and additional backing layers may be translucent or transparent, and may be combined with one or more light sources which may be integrated in-between backing layers or positioned underneath the backing layers. This would allow to create artificial turf which during the day would resemble real grass, but also allow aesthetic creations at night using light.

The artificial grass of the present invention is preferably used for residential lawn or landscaping purposes. However, other uses such as sportsfields and playgrounds may also be possible.

EXAMPLE

Artificial turfs according to the present invention are made according to the following parameters:

Fibers are tufted through a polypropylene woven backing and finished at the back side with a black latex to protect the tufts.

Example 1 Example 2 Example 3

Height first artificial 31 mm 35 mm 40 mm

grass fiber

Height second 18 mm 23 mm 28 mm

artificial grass fibers

Height thatch yarns 15 mm 18 mm 24 mm Properties of the fibers:

Rows of first artificial fibers are alternated with rows of second artificial fibers with a gauge of 3/16". Within a given row, fibers are arranged in bundles of fibers with 8 monofilaments per bundle and 120 stitches per 10 cm.