U.S. patent application number 09/767519 was filed with the patent office on 2001-07-12 for combined turf.
Invention is credited to de Vries, Hugo.
Application Number | 20010007700 09/767519 |
Document ID | / |
Family ID | 19763962 |
Filed Date | 2001-07-12 |
United States Patent
Application |
20010007700 |
Kind Code |
A1 |
de Vries, Hugo |
July 12, 2001 |
Combined turf
Abstract
The invention relates to a base layer for a combined synthetic
and natural turf comprising a fabric of which at least a part of
the weft and/or warp threads is manufactured from a biodegradable
material and/or is wholly absent so that the fabric contains
apertures, and synthetic turf fibers which are least partially
cowoven with the fabric and of which one or both ends form
synthetic grass blades. These ends only protrude from the fabric at
those locations where the non-degradable warp and weft threads
intersect. The base layer is used in combined synthetic and natural
turfs comprising a foundation, optionally a first layer of growth
substrate and a base layer according to the invention which is
provided with a second layer of growth substrate in which grass
plants grow. The invention further relates to a method for laying a
combined turf using the base layer of the invention.
Inventors: |
de Vries, Hugo; (GS
Ridderkerk, NL) |
Correspondence
Address: |
AKIN GUMP STRAUSS HAUER & FELD
1900 FROST BANK PLAZA
816 CONGRESS AVENUE
AUSTIN
TX
78701
|
Family ID: |
19763962 |
Appl. No.: |
09/767519 |
Filed: |
January 23, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09767519 |
Jan 23, 2001 |
|
|
|
09320776 |
May 27, 1999 |
|
|
|
09320776 |
May 27, 1999 |
|
|
|
PCT/NL97/00659 |
Dec 1, 1997 |
|
|
|
Current U.S.
Class: |
428/17 |
Current CPC
Class: |
D10B 2505/202 20130101;
E01C 2013/086 20130101; Y10T 428/23979 20150401; E01C 13/08
20130101; E01C 13/083 20130101 |
Class at
Publication: |
428/17 |
International
Class: |
A41G 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 29, 1996 |
NL |
1004656 |
Claims
What is claimed is:
1. Base layer for a combined synthetic and natural turf,
comprising: a fabric formed by a plurality of mutually
substantially parallel warp threads and a plurality of mutually
substantially parallel weft threads intersecting the warp threads,
said fabric comprising a plurality of apertures, and a plurality of
synthetic grass fibers connected at least partially to the fabric,
at least one of the ends of each fiber protruding outside the
fabric and forming a synthetic grass blade, characterized in that
the apertures are formed by enlarged spaces between adjacent warp
and/or weft threads, and the fiber ends forming the synthetic grass
blades protrude from the fabric at location where the weft threads
and the warp threads intersect.
Description
[0001] This application is a continuation application of copending
international application PCT/NL97/00659 filed Dec. 1, 1997, which
claims priority to NL 1004656, filed Nov. 29, 1996. The patent
applications are incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates to a base layer for a combined
synthetic and natural turf, comprising:
[0003] a fabric formed by a plurality of mutually substantially
parallel warp threads and a plurality of mutually substantially
parallel weft threads intersecting the warp threads, said fabric
comprising a plurality of apertures, and
[0004] a plurality of synthetic grass fibers connected at least
partially to the fabric, at least one of the ends of each fiber
protruding outside the fabric and forming a synthetic grass blade.
Such a base layer is known, for instance from WO-A-9400639.
BACKGROUND OF THE INVENTION
[0005] Up until a number of years ago a large number of sports were
practiced on natural turf. Natural turf has the advantage that it
is relatively soft and wounds and injuries are thereby seldom
caused during falls, sliding tackles and the like. The great
drawback of natural turf however is that it can deteriorate
significantly in quality due to intensive use and/or weather
conditions. What remains is a badly damaged field with large, bare
(sand) surfaces which cannot be played on, or only with difficulty,
and which have an unattractive appearance.
[0006] Synthetic grass surfaces have therefore already existed for
a number of years, in particular for hockey, tennis and the like.
Synthetic grass surfaces require less maintenance and withstand a
more intensive use than natural turfs. However, the drawback of
synthetic turf is that the frictional resistance is so high that
wounds and/or injuries can be caused in the case of sliding tackles
and undesired falls.
[0007] In the present application the terms "grass surface" and
"turf" are used interchangeably.
[0008] Therefore a hybrid turf or combination turf has already been
proposed in the above mentioned patent document WO-A-9400639, in
which the advantages of both types of turf are combined. This
combination turf is formed by a conventional synthetic grass
surface constituting a base layer on which a layer of growth
substrate is strewn. Grass seed is sown into this growth substrate,
so that the crowns of the grass lay between the synthetic grass
fibers and are protected thereby. The synthetic grass is formed by
a backing and a great number of upright synthetic grass fibers
connected therewith. The synthetic grass fibers are regularly
spaced, and may be connected to the backing by tufting or weaving.
The backing is perforated, so as to allow water and roots of the
natural grass to pass therethrough. As backing a coarse woven
material is for instance proposed, wherein apertures are formed
between the warp and weft threads. It is further proposed to
construct the backing from two layers, an apertured top layer
carrying the synthetic fibers and a bottom layer stabilizing the
top layer with the fibers and preventing the fibers from becoming
unstuck during handling of the synthetic grass. The bottom layer
may be made from a biodegradable material, so that this will
gradually disappear after the turf has been laid, leaving only the
perforated top layer with the synthetic grass fibers.
[0009] In this known combination turf the emphasis is mainly on the
synthetic grass, and there is relatively little room for growing a
robust natural grass turf. Furthermore, the cost of the known
combination turf is relatively high.
SUMMARY OF THE INVENTION
[0010] It is therefore the object of the present invention to
provide a combination turf comprising a relatively high percentage
of natural grass and which may be constructed and laid for a
relatively moderate cost. This is achieved according to the
invention by making use for the combined synthetic and natural turf
of a base layer as described above, in which the fiber ends forming
the synthetic grass blades protrude from the fabric at location
where the weft threads and the warp threads intersect. By forming
the synthetic grass blades exclusively at the intersections of the
warp and weft threads, and not at those locations where only warp
threads or weft threads are present, a base layer is obtained in
which there is relatively much room for arranging natural grass.
Furthermore, since the synthetic grass fibers protrude from the
fabric at the intersections of warp and weft threads, the loads are
transmitted to the base layer at those locations where this is
strongest. It is preferable to have the synthetic grass fibers
woven into the fabric, whereby a very strong connection is
formed.
[0011] The apertures in the base layer may be formed immediately
during manufacture thereof by enlarged spaces between adjacent warp
and/or weft threads, but it is also possible to form the apertures
only during use of the base layer by decomposition of warp and/or
weft threads made from a biodegradable material.
[0012] The above-described base layer may be arranged between two
layers of growth substrate, with grass being sown in the top layer.
Due to the apertures, which are present from the start or are
created in the course of time by decay or decomposition of the
biodegradable threads, the roots of the natural grass plants have
the opportunity to grow through the base layer and to become
anchored in the bottom layer of growth substrate and possibly also
at least partially in the base layer. Optimal rooting hereby
becomes possible while the additional strength of the remaining
fabric threads and synthetic grass blades is still retained.
[0013] Alternatively, it is also possible to suffice with one layer
of growth substrate which is arranged on the base layer placed on a
foundation. The roots can then become anchored in the layer of
growth substrate, the foundation and/or the base layer.
[0014] In particular, the present invention provides a base layer
for a combined synthetic and natural turf, the base layer
comprising: a fabric formed by a plurality of mutually
substantially parallel warp threads and a plurality of mutually
substantially parallel weft threads intersecting the warp threads,
said fabric comprising a plurality of apertures, and a plurality of
synthetic grass fibers connected at least partially to the fabric,
at least one of the ends of each fiber protruding outside the
fabric and forming a synthetic grass blade, characterized in that
the apertures are formed by enlarged spaces between adjacent warp
and/or weft threads, and the fiber ends forming the synthetic grass
blades protrude from the fabric at location where the weft threads
and the warp threads intersect. In another aspect, the invention
provides such a base layer further characterized in that the
synthetic grass fibers are woven into the fabric.
[0015] In other embodiments, the invention provides such base
layers further characterized in that the apertures are formed
during use of the base layer by warp and/or weft threads made from
a biodegradable material. In other embodiments, such base layers
(further characterized in that the fabric is formed by a plurality
of series of non-biodegradable weft threads and a plurality of
series of biodegradable weft threads alternating with these series
and a plurality of series of non-biodegradable warp-threads
intersecting the weft threads and a plurality of series of
biodegradable warp threads alternating with these series, and in
that the ends of the synthetic grass fibers protrude from the
fabric at the intersections of these series of non-biodegradable
warp threads and non-biodegradable weft threads) are provided by
the invention. In related embodiments, the invention provides such
base layers comprising biodegradable threads further characterized
in that the biodegradable material is chosen from jute, sisal,
coconut fiber, or biodegradable polymers.
[0016] In another aspect, the invention provides such base layers
further characterized in that the artificial grass fibers are
monofilament fibers. In other related aspects, the invention
provides such base layers further characterized in that at least
part of the synthetic grass fibers has at least one colour other
than green, which, in some embodiments, may be furthered
characterized in that the synthetic grass fibers having different
colours form a pattern like lines of a sportsfield or a club
logo.
[0017] Base layers noted previously as being provided by the
invention, in some embodiments, may be further characterized in
that at least part of the fabric is impregnated or coated with
fertilizers. Similarly, base layers noted previously as being
provided by the invention, in other related embodiments, may be
furthered characterized in that at least part of the non
biodegradable threads comprise melting threads.
[0018] In other embodiments, combined synthetic and natural turf,
comprising a foundation, a base layer (noted previously as being
provided by the invention) arranged thereon, and a layer of growth
substrate in which grass plants may grow arranged on the base
layer, is provided by the invention. In related embodiments, the
invention provides such combined synthetic and natural turf further
characterized in that the thickness of the layer of growth
substrate on the base layer is chosen such that the synthetic grass
blades of the base layer protrude thereabove. In related
embodiments, the invention provides such combined synthetic and
natural turf (the thickness of the layer of growth substrate on the
base layer being chosen such that the synthetic grass blades of the
base layer protrude, or do not protrude, thereabove) further
characterized by a layer of growth substrate arranged between the
foundation and the base layer. In other related embodiments, the
invention also provides such combined synthetic and natural turf (a
layer of growth substrate being arranged, or not being arranged,
between the foundation and the base layer) further characterized in
that the growth substrate consists of "infertile leaf mould", a
mixture of sand and an organic material, or top layer mixtures
applied in natural grass turfs. In additional related embodiments,
the invention also provides such combined synthetic and natural
turf (a layer of growth substrate consisting of, or not consisting
of, "infertile leaf mould", a mixture of sand and an organic
material, or top layer mixtures applied in natural grass turfs)
further characterized in that the turf is used as sportsfield or as
grass turf in gardens, playgrounds, (recreational) parks or golf
courses.
[0019] In another aspect, the invention provides method for
creating a combined turf as described in the preceding paragraph,
comprising the steps of:
[0020] a. arranging a base layer as noted previously as being
provided by the invention on a foundation;
[0021] b. arranging a layer of growth substrate and grass seeds
sown therein over the base layer, in such manner that the synthetic
grass blades rise at least partially above the layer of growth
substrate,
[0022] c. causing the grass seed to germinate and raising grass
plants, and
[0023] d. mowing the natural grass to a length which is greater
than the length of the synthetic grass blades.
[0024] The invention further provides such method, further
characterized in that prior to arranging the base layer on the
foundation a layer of growth substrate is arranged thereon. In an
additional aspect, the invention provides such method (a layer of
growth substrate being arranged, or not being arranged, on the
foundation prior to arranging the base layer on the foundation)
furthered characterized in that the step of arranging a layer of
growth substrate including grass seeds over the base layer
comprises the intermediate steps of:
[0025] b1. at least partially working or strewing the growth
substrate into the base layer,
[0026] b2. sowing the grass seed into the growth substrate, and
[0027] b3. arranging the remainder of the growth substrate over the
grass seed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The present invention will be further elucidated on the
basis of the annexed drawings in which corresponding reference
numerals refer to corresponding components and in which:
[0029] FIG. 1 shows a perspective detail view of a base layer
according to the invention with separated parts;
[0030] FIG. 2 shows a perspective detail view of a base layer
according to the invention;
[0031] FIG. 3 is a partly broken away perspective detail view of a
part of a combined turf according to the invention with grass which
is just germinating; and
[0032] FIG. 4 is a partly broken away perspective detail view of a
part of a combined turf according to the invention with a number of
adult grass plants.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] FIG. 1 and FIG. 2 show a base layer 1 consisting of a fabric
2 of series of non-degradable warp threads 3 and weft threads 4
alternating with series of biodegradable warp threads 5 and weft
threads 6.
[0034] Synthetic grass fibers 7, preferably in a bundle 8, are
co-woven such that the ends 9 and 10, which form grass blades,
extend from the fabric at intersections 11 of non-degradable warp
and weft threads. At each intersection the blades of for instance
two successive bundles 8a and 8b extend outward. In an alternative
embodiment of the invention, the threads 5 and 6 can be omitted,
whereby apertures are already created immediately in the
fabric.
[0035] FIG. 3 shows a first layer of growth substrate 12 onto which
base layer 1 is placed. The foundation or substructure for the
whole construction is not shown in detail. In a second layer of
growth substrate 13 are sown grass seeds 14, only a few of which
are shown for the sake of clarity. In the situation shown, the
seeds have just germinated. In FIG. 4 the grass plants 15 are adult
and their roots 16 extend into the lower layer of growth substrate.
The natural grass blades 17 are longer than synthetic grass blades
18. In FIG. 3 the biodegradable threads 5, 6 are still present. In
FIG. 4 they have decomposed or have never been present, thereby
resulting in apertures 19.
[0036] The base layer according to the invention is simple to
manufacture and easy to use. The grass surfaces produced therewith
moreover have all the advantages of natural grass and synthetic
grass, while the most important drawbacks of both are avoided.
[0037] The base layer according to the invention preferably has a
grid pattern. In such a case, the base layer consists of a fabric
of a plurality of series of non-degradable weft threads and a
plurality of series of biodegradable weft threads alternating with
these series, as well as a plurality of series of non-degradable
warp threads intersecting the weft threads and a plurality of
series of biodegradable warp threads alternating with these series,
and the ends of the synthetic grass fibers protrude from the fabric
at locations where the series of non-degradable weft threads and
non-degradable warp threads intersect. Relatively robust pieces of
fabric thus remain at the intersections of the non-degradable weft
and warp threads. In the course of time holes will occur at
intersections of biodegradable weft and warp threads. The thus
resulting coarse-mesh network is held in place by a layer of growth
substrate arranged thereon.
[0038] The biodegradable material is for instance jute, coconut
fiber, sisal or biodegradable polymers. As additional benefit, many
biodegradable threads such as jute and the like have the advantage
that they retain moisture well. This is of particular importance,
certainly in the initial stages of the development of the turf.
Both the biodegradable threads and the non-degradable threads can
optionally be impregnated or coated with fertilizers.
[0039] It is particularly recommended that the artificial grass
fibers are monofilament fibers. In contrast to the fibrillated
yarns normally used in synthetic grass surfaces, such monofilament
fibers look more like grass blades. If desired however, fibrillated
yarns or combinations of different types of yarn can also be used
in the base layer according to the present invention.
[0040] Synthetic grass fibers are of course usually green. It is
however possible according to the present invention for at least a
part of the synthetic grass fibers to have at least one colour
other than green. A pattern, such as the lines of a playing field
or a club logo, can hereby be formed in the synthetic grass part of
the combined turf. An advertizing message can also be envisaged
here. Fibers with a colour other than green will become
particularly clear when the playing field is damaged. Coloured
fibers can optionally be used at the location of the pattern which
are the same length as the natural grass and planted more densely
in the foundation. The pattern is thus also visible when the
natural grass is intact. Repeated application of new chalk lines
for playing field lines in particular is thus avoided.
[0041] In order to promote growth of the natural grass preferably
at least part of the fabric of the base layer is impregnated or
coated with fertilizers.
[0042] For extra strength at least some of the non-degradable
threads could be melting threads. During manufacture of the base
layer these melting threads can be heated, whereby they fuse
together at the intersections of weft and warp threads.
[0043] The length of the synthetic grass fibers can be chosen as
desired and depends for instance on the distance over which the
fiber is co-woven with the fabric and on the thickness of the layer
of growth substrate arranged on the base layer as well as on the
desired length of the protruding synthetic grass blades.
[0044] Synthetic grass fibers are per se known. Synthetic grass
fibers are made for instance from polyolefins, polyamides or fibers
of natural or non-natural material. The materials used are
preferably resistant to wear under mechanical load and to UV
radiation. Synthetic grass fibers are obtainable for instance under
the brand names THIOLON.TM., TROFIL.TM. etc.
[0045] The invention also relates to a combined synthetic and
natural turf comprising a foundation, a base layer as described
above arranged thereon and a layer of growth substrate in which
grass plants grow arranged on the base layer. As discussed above,
the thickness of the layer of growth substrate arranged on the base
layer is preferably chosen such that synthetic grass blades of the
base layer remain protruding thereabove. However, in order to
achieve the advantages of natural grass it is recommended that the
natural grass blades be longer than the synthetic grass blades.
These latter then only appear when the natural grass has wholly or
partially disappeared due to use or poor weather conditions. In
this way the turf will still retain a green appearance, in any case
from a distance. In addition, the fibers give the top layer extra
stability and protection, whereby intensity of use can be
increased.
[0046] Also between the foundation and the base layer may be
arranged a layer of growth substrate, in which the roots of the
grass plants may become anchored.
[0047] The foundation can be any foundation used for natural grass
or synthetic grass surfaces, such as soil, sand, or a substructure,
foundation etc. If desired, shock-absorbing means such as layers of
rubber can be applied to a substructure or foundation of for
instance concrete. A skilled person in the field of natural and/or
synthetic grass surfaces is very well capable, without inventive
work, of choosing the foundation suitable for a particular
situation. In this application the term "foundation" will be used
for any suitable base on which the combined turf according to the
invention is used or which forms part of the surface.
[0048] The growth substrate can consist for instance of "infertile
leaf mould", a mixture of sand and organic material, or of other
top layer mixtures applied for natural grass surfaces. Such growth
substrates are generally known.
[0049] Although a surface manufactured by means of the base layer
according to the invention is particularly suitable as
sports-field, it can of course also be applied at other locations
if desired, for instance in gardens, playgrounds and (recreational)
parks, golf courses and the like. Precisely because the turf is in
principle a natural grass surface, the applicability thereof is
very wide-ranging.
[0050] The synthetic grass fibers can be implanted in the base
layer according to the invention at a limited density per unit area
because the natural grass forms the larger part of the combination
turf. However, greater densities are also possible in determined
conditions.
[0051] The base layer according to the invention can be supplied
for instance on a roll and is therefore simple to use. The base
layer can be unrolled onto the desired foundation of growth
substrate and cut or trimmed to size. No complex installations are
required during laying of the turf for insertion of the synthetic
grass blades, because the base layer is prefabricated and already
contains the synthetic grass blades.
[0052] Manufacture of the base layer can also take place in simple
manner on a weaving machine. Co-weaving of the synthetic grass
fibers is carried out by gripper machines, bar looms or twin looms.
Such techniques are generally known.
[0053] The invention further provides a method for laying a
combined turf according to the invention, comprising the steps
of:
[0054] a. arranging a base layer as described above on a
foundation;
[0055] b. arranging a layer of growth substrate and grass seeds
sown therein over the base layer, in such manner that the synthetic
grass blades rise at least partially above the layer of growth
substrate,
[0056] c. causing the grass seed to germinate and raising grass
plants, and
[0057] d. mowing the natural grass to a length which is preferably
greater than the length of the synthetic grass blades.
[0058] In order to provide a good nutrient medium for the roots of
the grass plants, prior to arranging the base layer on the
foundation a layer of growth substrate may be arranged thereon.
[0059] The step of arranging a layer of growth substrate including
grass seeds over the base layer may further comprise the
intermediate steps of:
[0060] b1. at least partially working or strewing the growth
substrate into the base layer,
[0061] b2. sowing the grass seed into the growth substrate, and
[0062] b3. arranging the remainder of the growth substrate over the
grass seed.
[0063] According to the invention the method may therefore include
a number of variants. It is thus possible to place the base layer
directly onto the foundation or onto a layer of growth substrate
arranged on the foundation. Depending on the chosen option, the
grass seed can then be sown directly onto the base layer, in a
layer of growth substrate arranged on the base layer or on this
layer of growth substrate. If desired, combinations can be applied.
It is also possible, if desired, to sow in the foundation or the
layer of growth substrate under the base layer. This is not
recommended however, because the grass seeds will then usually lie
too deep.
* * * * *