Note: Descriptions are shown in the official language in which they were submitted.
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ARTIFICIAL TURF MAT AND METHOD FOR MANUFACTURE THEREOF
The invention relates to an artificial turf mat, comprising a woven backing
and a number of
artificial grass blades connected thereto. Such an artificial turf mat is
known in different forms.
The known artificial turf mat is formed by a rather dense weave, from which
artificial
grass blades protrude on one side. These artificial grass blades are attached
to the backing by
means of tufting or weaving. The side of the backing remote from the
protruding blades is
generally stabilized by a layer of latex or by another coating. This
additional layer also serves to fix
the artificial grass blades firmly in the backing.
The known artificial turf mat has the drawback that it is fully sealed on the
underside by
the layer of latex or the other coating, this adversely affecting the drainage
of the artificial turf
field.
US 2016/265170 Al describes an artificial turf mat with a flexible base layer
from which
long blades and shorter blades extend. The short blades serve to support the
longer blades, whereby
they have better shock-absorbing properties.
EP 3 029 198 Al describes a hybrid grass surface with a base sheet with
therein holes
through which roots of grass can protrude, and with grouped filaments which
are connected to the
base sheet by tufting.
JP 2005 015 972 A describes an artificial turf mat formed by coupling a number
filaments
to each other in strips and weaving therefrom a mat wherein yet other
filaments form pile threads.
The invention now has for its object to provide an artificial turf mat of the
above described
type wherein this drawback does not occur, or at least does so to lesser
extent. According to the
invention, this is achieved in such a mat in that the woven backing comprises
a leno weave of warp
and weft threads wherein at least some of the threads are formed by melting
threads, and wherein
the artificial grass blades are woven into the woven backing. By making use of
a leno weave,
which forms a much stronger connection than a conventional weave in that the
warp threads are in
a leno weave arranged twisted in pairs round the weft threads, and by here
also applying melting
threads for additional bonding, a woven backing is formed which has sufficient
intrinsic stability to
in principle be used without latex or other coating, and wherein the co-woven
artificial grass blades
are bonded very well. An artificial turf mat having a very open structure and
good drainage
properties can thus be formed.
Because the artificial grass fibres are woven into the backing, for instance
as warp or weft
threads forming pile threads, the artificial grass blades can be formed by
locally cutting these fibres
or pile threads. It is possible already to cut through the fibres during
weaving, for instance in the
manner as described in WO 2010/120174. It is possible to envisage here that
the artificial grass
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fibres are cut through such that the artificial grass blades formed thereby
have a pointed shape
which approximates the shape of natural blades of grass.
When the artificial grass blades protrude from the backing on both sides, a
two-sided
artificial turf mat is obtained which can also be placed vertically in order
to function for instance as
screen or partition.
At least some of the warp threads can further be formed by melting threads,
and/or at least
some of the weft threads can be formed by melting threads. In order to be able
to twist the warp
threads properly round the weft threads so as to form the leno weave it is
preferred for the warp
threads and/or the weft threads to have a substantially round cross-section.
In order to combine a good bonding with sufficient strength it is preferred
for each melting
thread to comprise a temperature-resistant thread core and a meltable coating
surrounding the
thread core. The melting thread can here as it were be welded to nearby
threads by the melting of
the coating.
The thread core can for this purpose comprise a plastic with a relatively high
melting
temperature, particularly polypropylene, while the coating can comprise a
plastic with a relatively
low melting temperature, particularly polyethylene.
In order to further increase the stability of the weave at least some of the
warp and/or weft
threads can be formed by shrinking yarns. By shrinking the yarns after
weaving, for instance by
heating them, surrounding threads are fixated extra firmly.
At least some of the warp and/or weft threads can in addition or instead be
formed by
spiral yarns. The surrounding threads can thus also be additionally fixated by
having the yarns curl
after weaving.
When at least some of the warp and/or weft threads are biodegradable, open
spaces can be
formed in the artificial turf mat, through which natural grass can grow. A
hybrid turf mat can thus
be formed.
At least some of the artificial grass blades can be manufactured from
biodegradable
material. The artificial grass blades can thus in the first instance support
natural grass blades
growing through the artificial turf mat. By the time this support is no longer
needed, the
biodegradable artificial grass blades decay and only the non-degradable
artificial grass blades and
the natural grass remain, these together forming a hybrid field.
An easily manufactured artificial turf mat is obtained when only a part of the
backing is
woven as leno weave. For the stability it often suffices to locally fixate
conventionally woven
zones by means of zones with leno weave.
Arranged between two pairs of leno-woven warp threads can thus be a larger
number of
conventionally woven warp threads.
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In order to increase the stability of the artificial turf mat it can be
provided with at least one
secondary backing connected to the woven backing. This secondary backing can
also be a weave.
The at least one secondary backing can here be manufactured from a natural
fibre material,
particularly jute or viscose. This natural fibre material can decay once the
artificial turf mat has
been laid, since the stability is then provided by the ground surface.
The artificial turf mat can even be provided with a plurality of secondary
backings, which
are manufactured from different materials. The outer secondary backing can
here serve mainly to
protect the other layers when the artificial turf mat is heated in order to
melt the melting threads.
The invention also relates to a method for manufacturing an artificial turf
mat. A
conventional method comprises the steps of weaving a backing and connecting a
number of
artificial grass blades thereto.
The method according to the invention is distinguished from the conventional
method in
that at least a part of the backing is woven by interweaving a number of warp
and weft threads by
means of leno weaving, wherein at least some of the interwoven threads are
formed by melting
threads and wherein the artificial grass blades are woven into the woven
backing.
Preferably applied variants of the method according to the invention are
described in the
dependent claims 18-28.
The invention will now be elucidated on the basis of a number of embodiments,
wherein
reference is made to the accompanying drawings, in which:
Fig. 1 is a perspective view of an artificial turf mat according to a first
embodiment of the
invention on a ground surface, wherein some of the artificial grass blades
have been omitted,
Fig. 2 is a schematic top view of a leno weave as applied in the backing of
the artificial turf
mat according to the invention,
Fig. 3 is a cross-section through a melting thread for application in the
artificial turf mat
according to the invention,
Fig. 4A and 4B are respectively a side view of and a cross-sectional view
through a weft
thread embodied as melting thread and two warp threads of the leno weave
before and after
melting of the melting thread,
Fig. 5A and 5B are schematic perspective views showing the connection between
a weft
thread and two warp threads embodied as shrinking yarns of the leno weave,
before and after
heating of the shrinking yarns,
Fig. 6 is a schematic perspective view of a weft thread and two warp threads
twisted
therearound of a leno weave, wherein a number of threads is embodied as spiral
yarns,
Fig. 7 is a flow diagram with the most important steps of the method according
to the
invention, and
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Fig. 8 is a schematic bottom view of a backing of an artificial turf mat
according to a
second embodiment of the invention.
An artificial turf mat 1 (Fig. 1) comprises a woven backing 2 and a large
number of
artificial grass blades 3 connected thereto and protruding from the backing 2
on one side - the side
forming the upper side T in use. Backing 2 is woven from threads or yarns
which, just as artificial
grass blades 3, can themselves be manufactured from plastic. In order to form
a very stable backing
2 without use having to be made for this purpose of a coating or a layer of
latex, at least a part of
the weave of backing 2 is according to the invention a leno-weave. In such a
leno-weave the warp
threads 7a, 7b are arranged twisted in pairs round weft threads 8 (Fig. 2).
Due to this pairwise
twisting of warp threads 7a, 7b, the weft threads 8 are gripped tightly
therebetween, whereby
slippage of the threads relative to each other is prevented and a stronger
connection in the weave is
achieved than is possible with conventional weaving techniques.
In order to stabilize backing 2 still further the warp threads 7a, 7b and/or
the weft threads 8
are in any case partially formed by melting threads. By melting these threads
after the weaving the
weave is in fact "welded", whereby it is strengthened still further. Because
the weave of backing 2
is thus intrinsically stable, and can be used without coating or stabilizing
layer of latex, backing 2
is lighter and easier to handle than a conventional backing with coating,
while the eventual
artificial turf mat will in addition have an open structure owing to the
absence of the coating or the
layer of latex, and is thus for instance air-permeable and water-permeable.
Each melting thread can be formed by a temperature-resistant thread core 9 and
a meltable
coating 10 which encloses thread core 9 (Fig. 3). This meltable coating 10
provides for the
bonding, while the thread core 9 will not melt and thus guarantees the
strength and stability of the
weave. A plastic with relatively high melting temperature, such as
polypropylene, is for instance
suitable as material for the thread core 9. A plastic with a relatively low
melting temperature, such
as for instance polyethylene, could be chosen for coating 10. The difference
in melting temperature
between thread core 9 and coating 10 need otherwise not be exceptionally
great, as long as it is
sufficient to ensure that the mechanical properties of thread core 9 are not
affected, or hardly so,
when backing 2 is heated to a degree that coating 10 of the melting thread
melts. As can be seen,
the melting thread here has a round cross-section, whereby the leno weaving is
simplified. In the
case of other cross-sections, particularly flat cross-sections, the twisting
of warp threads 7a, 7b
around weft thread 8 results in deformation, whereby an irregular weave is
obtained.
For the purpose of heating the melting threads use can be made of any desired
heating
technique, such as for instance heating by irradiation with infrared
radiation. It is also possible to
envisage guiding the weave along a heated roller and thus heat the melting
threads. In that case it
can be advantageous to protect the backing 2 on the side facing toward the
heated roller with an
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additional backing which is manufactured from a non-meltable material, for
instance a natural fibre
material or a biodegradable material.
As can be seen by comparing Fig. 4A and Fig. 4B, when weft thread 8 is
embodied as
melting thread, the warp threads 7a, 7b will sink slightly into coating 10 of
weft thread 8, and
5 tightly enclose thread core 9, when coating 10 of weft thread 8 is
melted. The material of meltable
coating 10 will here flow around warp threads 7a, 7b so that they become
wholly or partially
embedded therein. When the temperature is then once again reduced and meltable
coating 10'
solidifies again, a very strong welded connection (shown in broken lines) will
be created between
weft thread 8 and warp threads 7a, 7b.
Although weft thread 8 is embodied as melting thread in this example, it is of
course
equally possible to envisage, in addition to or instead of weft thread 8, one
of the warp threads 7a,
7b or even both of the warp threads 7a, 7b being embodied as melting thread.
It is additionally or instead possible to achieve a particularly strong
connection between
the warp and weft threads 7, 8 when some of these threads are formed by
shrinking yarns. When
warp threads 7a, 7b are for instance formed by shrinking yarns, they can in
the first instance be
interwoven in twisted manner with weft threads 8 in order to thus form a leno
weave (Fig. 5A),
after which warp threads 7a, 7b can shrink by heating and are thus pulled even
more tightly around
weft threads 8 (Fig. 5B). When weft threads 8 are here once again embodied as
melting threads, an
even stronger connection is formed.
Another way of achieving an additional strengthening of the leno weave is
shown in Fig. 6,
where the weft thread 8 and warp threads 7a, 7b are all embodied as spiral
yarns. Owing to the
spiral form of the warp and/or weft threads 7, 8 they engage even more tightly
in each other than is
the case with smooth yarns, since the spiral yarns as it were hook into each
other. This counteracts
slippage of the threads relative to each other still further.
The backing 2, which is formed as a leno weave and the warp and/or weft
threads 7, 8 of
which are embodied as melting threads, can be applied for the purpose of
forming an artificial turf
mat 1. The artificial grass blades 3 are for this purpose woven into backing
2. Some of the warp or
weft threads 7, 8 are brought out of a main plane of the weave of backing 2 in
loops in order to
there form the artificial grass blades 3. The loops can optionally be cut
through so that each loop
forms two individual artificial grass blades 3. This cutting can already take
place during the
weaving, as described in WO 2010/120174. Because the combination of leno weave
and the use of
melting threads results in a very stable backing 2 with artificial grass
blades 3 co-woven therein, a
relatively large mesh width of the weave can be chosen. A relatively open
structure is thus formed,
which is very well water-permeable and thus results in an artificial turf
field with good drainage
properties. The structure is also air-permeable and thereby suitable for
ventilation and/or heating of
the artificial turf field.
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It can be useful to make the leno weave of backing 2 on the basis of shrinking
yarns,
because the artificial grass blades 3 are thereby very tightly enclosed or
gripped. In that case it can
further be useful to apply a secondary backing 4 (Fig. 1) in order to prevent
deformation of the
primary backing 2 when the shrinking yarns shrink. The secondary backing 4 can
ensure that
primary backing 2 remains flat. Secondary backing 4 can be manufactured from a
natural fibre
material, such as jute or viscose. As stated, an additional secondary backing
(not shown here),
which serves mainly to protect primary backing 2 and secondary backing 4 from
overheating
during heating of the melting threads, can in addition also be provided. This
additional backing can
be manufactured from a biodegradable material so that it eventually decays
once artificial turf mat
1 has been laid on a ground surface 5. The secondary backing 4 and/or the
additional backing can
further serve to support and fixate a filler layer (to be discussed below)
when an artificial turf field
11 is installed on the basis of artificial turf mat 1.
Because the artificial turf mat 1 already has sufficient strength and
stability even without
coating, latex layer or secondary backing, it is also suitable to be suspended
vertically, for instance
in order to form a screen or partition. In that case the pile threads can be
brought out of the main
plane of the weave and cut on both sides, so that protruding artificial grass
blades 3 are formed on
both sides of backing 2. A two-sided artificial turf mat 1 is then thus in
fact formed.
As can be seen in Fig. 8, it is not necessary to embody the whole backing 2 as
leno weave,
but it is possible to suffice with several zones 12 formed by leno weaving,
whereby zones 13 with
conventional weave are fixated and stabilized. In the shown example the
backing is formed by
strips 13 of conventional weave, which are finished on both sides with one or
more pairs of warp
threads 7a, 7b which are interwoven in twisted manner with weft threads 8 for
the purpose of
forming a local leno weave 12. These local leno weaves 12 hold in place the
warp threads of the
conventional weave 13 arranged therebetween. Otherwise also formed between
woven strips 12, 13
in this example are strips 14, where no warp threads are present and the weft
threads 8 thus lie
loosely. A very open backing 2 is thus created.
The different steps of the method for manufacturing the artificial turf mat
according to the
invention are shown in Fig. 7. The method starts with providing warp threads 7
(step 100) and weft
threads 8 (step 101). The warp threads (7) and/or the weft threads 8, or at
least some of these
threads, can here be embodied as melting threads. The warp and weft threads 7,
8 or some of these
threads can also be embodied as shrinking yarns and/or spiral yarns.
In a subsequent step 102 the warp and weft threads 7, 8 are interwoven by
making use of a
leno weaving technique, wherein the warp threads 7 are intertwined. In step
103 the artificial grass
blades 3 can then be connected to the woven backing 2. Since the artificial
grass blades 3 are here
connected to backing 2 by weaving, the steps 102 and 103 in fact coincide, as
shown schematically
by the dotted block 102a.
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After artificial grass blades 3 have been woven into backing 2 a secondary
backing 4 can
optionally be connected to the leno weave backing 2 (step 104). This step is
optional and could be
skipped. Secondary backing 4 can be glued to primary backing 2, but it is also
possible to envisage
these backs 2, 4 being connected to each other by for instance double weaving
or any other type of
connecting technique. In addition to a secondary backing 4 which, as stated,
could be
manufactured from natural fibre material it is possible to arrange another
additional backing, for
instance a backing which functions as protective layer during heating and
which can be
manufactured from a biodegradable material. This backing can also be connected
to the other
backings in different ways.
In a subsequent step 105 the artificial turf mat 1 formed in the foregoing
steps is fixated by
being heated. The melting threads will here partially melt, whereby welded
connections are formed
with the surrounding threads, also including the pile threads forming the
artificial grass blades 3.
The heating can take place by radiation, for instance infrared radiation, or
by guiding artificial turf
mat 1 over a heated roller. The additional backing is especially important in
this latter case.
Finally, artificial turf mat 1 is wound onto a roll (step 106) and is ready to
be transported to
a location where an artificial turf field 11 has to be installed.
The artificial turf field 11 formed using the above described artificial turf
mat 1 comprises
in conventional manner a ground surface 5 on which the backing 2 (in the shown
example with the
secondary backing 4 thereunder) is placed. The artificial grass blades 3
protrude above the backing
2 on the upper side T. The space between the artificial grass blades 3 can
then be filled with a filler
material or "infill" 6, which ensures on the one hand that the artificial
grass blades are supported
and in addition serves for resilience and damping. Rubber granules, cork and
other materials,
generally in combination with sand, are suitable as filler material 6. When
backing 2 and/or
artificial grass blades 3 are manufactured partially from a biodegradable
material, and the artificial
turf mat 1 is thus intended to form a hybrid field, the ground surface 5 can
be seeded with grass
seed (not shown here) prior to artificial turf mat 1 being laid. It is also
possible to envisage the
grass seed being sown in the layer of filler material 6 when this filler layer
6 comprises a natural
material in which the grass can grow.
The invention thus provides an artificial turf mat which is lighter and
cheaper than existing
artificial turf mats, and is easier to handle. The artificial turf mat
according to the invention further
has greatly improved mechanical properties, while in addition enabling a
better drainage and
ventilation than existing artificial turf mats.
Although the invention is described above with reference to a number of
embodiments, it
will be apparent that it is not limited thereto but can be varied in many
ways. The warp and weft
threads 7, 8 can thus for instance have other cross-sectional forms than shown
here. It is also
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possible to apply materials other than those stated here, both for the
synthetic fibres and for the
natural fibres. The scope of the invention is therefore defined solely by the
following claims.
