Note: Descriptions are shown in the official language in which they were submitted.
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ARTIFICIAL TURF
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.
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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.
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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.
io 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 0-shaped cross-section, and have
dimensions
of e.g. 50-500 pm 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.
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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
io 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
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
20 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
25 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
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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,
5 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
io 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".
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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
lo 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.
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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 3/4, 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
io 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.
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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
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Properties of the fibers:
First artificial grass Second artificial Thatch yarns
fibers grass fibers
material LLDPE LLDPE LLDPE
cross-section diamond shape diamond shape rectangular shape
colour Lime green Olive green Beige/Brown
dtex 875 1050 625
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.
