Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Artificial turf comprising an agglomerate infill
Description
Field of the invention
The invention relates to artificial turf, in particular to artificial turfs
with infill and also
infill for artificial turf.
Background and related art
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Artificial turfs are known as a carpet structure resembling natural grass. The
structure consists of a fabric to which fibers are tufted and fixed at the
bottom side of
the fabric. The fibers are monofilamented or twisted yarns of polyethylene or
other
thermoplastic materials. The fabrics are woven goods made of polypropylene and
the fixing material which glues the fibers to the fabric are mixtures of SBR
latices
and fillers such as calcium carbonate or polyurethane-based adhesives.
Artificial turfs are used as sports fields whereas the carpets are laid onto a
substructure of rubber granules acting as a shock damping layer or onto a
substructure that comprises an elastic layer (e-layer). The carpet structure
is filled
with sand and rubber granules in order to keep the structure in place so that
the
carpet does not slip and the fibers stay in an upright position. The filling
material is
also referred to as infill or infill material. Typically in use is SBR-rubber
or EPDM-
rubber, both elastomeric materials in irregularly granulated form. The SBR-
rubber is
commonly sourced from used tires.
An advantage of using artificial turf is that it eliminates the need to care
for a grass
playing or landscaping surface, like regular mowing, scarifying, fertilizing
and
watering. Watering can be e.g. difficult due to regional restrictions for
water usage.
In other climatic zones the re-growing of grass and re-formation of a closed
grass
cover is slow compared to the damaging of the natural grass surface by playing
and/or exercising on the field. Artificial turf fields though they do not
require a similar
attention and effort to be maintained, may require some maintenance such as
having to be cleaned from dirt and debris and having to be brushed regularly.
This
may be done to help fibers stand-up after being stepped down during the play
or
exercise. Throughout the typical usage time of 5-15 years it may be beneficial
if an
artificial turf sports field can withstand high mechanical wear, can resist
UV, can
withstand thermal cycling or thermal ageing, can resist inter-actions with
chemicals
and various environmental conditions. It is therefore beneficial if the
artificial turf has
a long usable life, is durable, and keeps its playing and surface
characteristics as
well as appearance throughout its usage time.
The infill of synthetic turfs plays a predominant role concerning the
mechanical
properties of the complete turf structure. These properties determine the
damping of
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a bouncing ball and running or jumping athletes. It is also desirable that the
uppermost structure of a turf would not cause injuries of the athletes, such
as burns,
scratches, skin abrasions, etc. Filling a synthetic turf only with sand would
have an
unpleasant effect of energy-sapping, comparable to running on dry sand on a
beach. To avoid such uncomfortable attitudes infill systems are commonly in
use. At
least two layers built up such infill systems, whereas the sand layer is laid
first on
top of the carpet topping (the opposite side of the backing) and a second
layer or
elastomeric material laid onto the sand. The elastomeric material normally
consists
of ground rubber, whereas the particles are coarser than the sand grains. The
thickness of an infill system is such that only a small proportion of the
grass fibers
exceed the infill layer in height. The complete structure then resembles
freshly
mowed natural grass.
The FIFA (Federation Internationale de Football Associaton) has set up quality
standards in their 'Quality Concept for Football Turf, Handbook of
Requirements,
January 2012 Edition.' In this handbook, the standards are described as well
as the
test methods. For synthetic turf infill systems, the following holds:
- force reduction: 60 (:)/0 - 70 (:)/0
- vertical deformation: 4 mm ¨ 10 mm
- rotational resistance: 30 Nm ¨ 45 Nm
all of which in dry and wet condition and after simulated wear.
According to the FIFA standards the tests are carried out with a so-called
advanced
artificial athlete ¨ Triple A, a Lisport wear tester and a rotational
resistance tester.
Artificial turf or artificial grass is surface that is made up of fibers which
is used to
replace grass. The structure of the artificial turf is designed such that the
artificial
turf has an appearance which resembles grass. Typically, artificial turf is
used as a
surface for sports such as soccer, American football, rugby, tennis, golf, for
playing
fields, or exercise fields. Furthermore, artificial turf is frequently used
for landscaping
applications.
Artificial turf may be manufactured using techniques for manufacturing
carpets. For
example, artificial turf fibers which have the appearance of grass blades may
be
tufted or attached to a backing. Often times artificial turf infill is placed
between the
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artificial turf fibers. Artificial turf infill is a granular material that
covers the bottom
portion of the artificial turf fibers. The use of artificial turf infill may
have a number of
advantages. For example, artificial turf infill may help the artificial turf
fibers stand up
straight. Artificial turf infill may also absorb impact from walking or
running and
provide an experience similar to being on real turf. The artificial turf
infill may also
help to keep the artificial turf carpet flat and in place by weighting it
down.
United States patent application US 2010/0151158 discloses a method for
recycling
synthetic turf that includes agglomerating a plurality of synthetic turf
fragments and
extruding the agglomerated material. The method produces a recycled material
for
use as infill in a synthetic turf. The agglomerate is extruded and may be in a
spherical, cylindrical, oval, or football shaped. The pellets may also be of
an
irregular shape. The irregular shape may be used to aid tight packing of the
granules.
Summary
The invention provides for an artificial turf surface, a method, and the use
of an
agglomerate as infill for artificial turf. Embodiments are given in the
dependent
claims.
Examples may provide for an artificial turf infill that is at least partially
made from an
agglomerate comprising one or more non-elastomeric thermoplastics. The
agglomerate is formed into irregularly shaped grains. A "grain" as used herein
encompasses a small part or portion of a material that is hard.
Normally, non-elastomeric thermoplastics would be too hard and rigid to use as
an
artificial turf infill. However, forming them into grains that have fibrous
extensions
makes them flexible. When the grains are distributed in the pile of the
artificial turf,
the grains have a tendency to pack loosely because of the fibrous extensions.
This
produces voids or free space between the grains which makes the resultant
infill
more elastic although it has been manufactured from non-elastomeric
thermoplastics.
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In various examples, the agglomerate may be formed my one or more non-
elastomeric thermoplastics and an additional additives such as a pigment
powder.
In some examples, the artificial turf infill that is at least partially made
from an
5 agglomerate of at least two non-elastomeric thermoplastics.
In other examples, material used to form the artificial turf infill is
provided as an
agglomerate. An extrusion process or an agglomeration process is then used to
form the material into the grains with fibrous extensions.
In one aspect, the invention provides for an artificial turf surface
comprising an
artificial turf carpet with a pile. The artificial turf carpet comprises a
backing. The
artificial turf carpet further comprises artificial grass fibers. The
artificial grass fibers
are tufted into the backing. The artificial turf grass fibers form the pile.
The artificial
grass fibers are secured to the backing.
The artificial turf surface further comprises an artificial turf infill which
is distributed
within the pile. The artificial turf infill may also be described as being
distributed
between the artificial grass fibers. The artificial turf infill comprises
irregularly shaped
grains. The grains comprise an agglomerate comprising at least one type of non-
elastomeric thermoplastic. Alternatively the grains can be described as
comprising
an agglomerate comprising at least one type of non-elastomeric thermoplastic.
At
least a portion of the grains have fibrous extensions.
In some examples all or a majority of the grains have the fibrous extensions.
In
other examples at least 40% 50%, 60%, 70%, 80%, or 90% of the grains have the
fibrous extensions. A fibrous extension as used herein encompasses a region of
the grain that is substantially narrower than another portion of the grain.
The
material of the grain may be rigid, but the fibrous extension is narrow enough
that
the fibrous extension is able to flex or bend.
The use of the irregularly shaped grains as the artificial turf infill may
have several
benefits. One potential benefit is that the non-elastomeric thermoplastics can
be
used. Normally the artificial turf infill is made up of an elastomeric
material or
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material which is easily pushed aside so that the artificial turf surface has
lifelike
properties such as mimicking the give of a real turf surface which has dirt or
sand
within it. The irregularly shaped grains have the benefit that there may be
air
pockets and the packing ratio of the artificial turf infill is reduced. This
allows the
hard non-elastomeric thermoplastics to be used and still have the properties
which
realistically mimic a real turf surface.
In another embodiment, at least 50%, at least 60%, at least 70%, at least 80%,
at
least 90%, or at least 95% of the irregularly shaped grains have a curved
profile.
Increasing the proportion of irregularly shaped grains with a curved profile
may have
the effect of increasing the amount of cavities or voids formed within the
artificial turf
infill. This may in turn provide for better shock absorption by the artificial
turf infill.
In another embodiment, at least 40%, 50%, 60%, 70%, 80%, or 90% of the grains
have the fibrous extensions. This embodiment may be beneficial because
increasing the number or amount of fibrous extensions may provide for better
shock
absorption by the grains.
In another embodiment, in at least 50%, 70%, or 90% of the portion of the
grains the
fibrous extensions comprise at least 30% of the weight of the grains. This
embodiment may be beneficial because increasing the number or amount of
fibrous
extensions may provide for better shock absorption by the grains.
In another embodiment, the at least one type of non-elastomeric thermoplastic
is
viscoelastic at temperatures below 100 C.
In another embodiment, the at least one type of non-elastomeric thermoplastic
comprise recycled artificial turf fibers. Recycled artificial turf fibers are
equivalent to
artificial grass fibers. The recycled artificial turf fibers are artificial
turf fibers which
have been removed from a previously installed artificial turf surface. The use
of the
non-elastomeric thermoplastics from recycled artificial turf fibers may have
the
benefit that the reuse of the thermoplastic reduces the amount of waste which
is
deposited in landfills. It may also have the benefit that the recycled
artificial turf
fibers may have additives which would be useful for the artificial turf
infill. For
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instance, the recycled artificial turf fibers may be colored green. Having the
artificial
turf infill a green color may be beneficial in making the artificial turf
surface more
lifelike looking. It may also have the benefit that the recycled artificial
turf fibers have
other additives such as UV protection which will increase the longevity of the
artificial turf infill.
In another embodiment, the irregularly shaped grains have a longitudinally
stretched
out and curved volume expansion with ratios of length to diameter/cross
sectioned
within 1:2t0 1:50.
In another embodiment, the irregularly shaped grains have a longitudinally
stretched
out and curved volume expansion with ratios of length to diameter/cross-
section
within any one of the following: 1:4 to 1:50, 1:8 to 1:50, 1:16 to 1:50, and
1:32 to
1:50. This embodiment may be beneficial because as the irregualry shaped
grains
become narrower with respect to their length the irregularly shaped grains may
become more flexible.
In another embodiment, the irregularly shaped grains have a sieve size between
0.2
mm and 12 mm. In this embodiment the irregularly shaped grains have been
selected such that they pass through a first sieve with an opening of 12 mm or
less.
The irregularly shaped grains are further selected such that they are captured
by a
sieve with openings of 0.2 mm or greater. The opening of the first sieve
remains
greater than the opening of the second sieve.
In another embodiment the irregularly shaped grains have a sieve size below 12
mm. In this embodiment the irregularly shaped grains have been selected such
that
they pass through a sieve with an opening of 12 mm or less.
In another embodiment, the irregularly shaped grains have a thickness between
0.5
mm and 2 mm.
In another embodiment, the at least one type of non-elastomeric thermoplastic
comprise any one of the following: at least one thermoplastic polymer, a
polyolefin,
waste plastic, fibrous waste plastic, pre-consumer yarn, post-consumer yarn
recovered from synthetic sports fields, artificial turf fiber, recovered waste
plastic,
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recycled packaging material, poly ethylene food packaging, poly ethylene,
polypropylene, a poly ethylene and poly propylene mixture, LLDPE, HDPE, LDPE,
MDPE, PP, PE, a polyolefin, and combinations thereof. This embodiment may be
beneficial because thermoplastic which would normally be disposed of may be
used
for manufacturing a high quality artificial turf surface.
In another embodiment, the artificial turf surface further comprises a sand
layer
between the backing and the artificial turf infill. The use of the sand layer
between
the backing and the artificial turf infill may further serve to improve the
replication of
.. natural turf surface properties by the artificial turf surface. The use of
the sand layer
may also reduce the amount of artificial turf infill which is required to be
used.
In another embodiment, the majority of the irregularly shaped grains have a
curved
profile. The curved profile may be in a cross-sectional view of the
irregularly shaped
.. grain. Having a curved profile may be beneficial because it may reduce how
closely
the irregularly shaped grains can be packed next to each other. Having them
less
dense may be beneficial because the artificial turf infill will have a more
springy or
elastic profile although the agglomerate is made of a non-elastomeric
thermoplastic.
In another embodiment, the fibrous extensions of the irregularly shaped grains
interlock with any one of the following: the artificial grass fibers, the
fibrous
extensions of other irregularly shaped grains, and combinations thereof. This
embodiment may be beneficial because the interlocking of the fibrous
extensions
may serve to hold the irregularly shaped grains in the same position with
respect to
each other, and also possibly to help hold their position relative to the
artificial grass
fibers. This may for example have the benefit of reducing the splash effect
when a
ball hits an artificial turf surface. Splash is when the impact of a ball or
other object
causes artificial turf infill to fly up above the surface of the artificial
turf surface. It
resembles the splash of an object hitting a puddle of water.
In another embodiment, at least a portion of the fibrous extensions are
branched.
The branching of the fibrous extensions may be beneficial because it may make
the
fibrous extensions more flexible. The branching may also produce hook like
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structures that enable the irregularly shaped grains to better interlock
either with
themselves or artificial grass fibers.
In another embodiment, the artificial turf surface further comprises a top
infill layer.
The irregularly shaped grains are between the backing and the top infill
layer.
In another embodiment, the top infill layer comprises regularly shaped
granules. The
regularly shaped granules may for example have round, oval, a rounded, or bead
shaped appearance. The use of the regularly shaped granules may be beneficial
.. because it may have the effect of reducing the friction between an object
sliding on
the artificial turf surface and the irregularly shaped grains.
In another embodiment, the regularly shaped granules comprises at least 50%,
70%, 90%, or 95% of the top infill layer by weight. This embodiment may be
beneficial because as the amount of the regularly shaped granules increases in
the
top infill layer the friction between an object sliding on the artificial turf
surface is
further reduced.
In another embodiment, the top infill layer consists of the regularly shaped
granules.
For example, the regularly shaped grains could be made from an agglomerate
that
is similar or has an equivalent composition to the irregularly shaped grains.
In other
examples the regularly shaped granules could be made from a elastomeric
compound such as crumb rubber or other materials conventionally used as
artificial
turf infill. For example, the elastomeric granulates used for artificial turf
infill could be
placed on the surface artificial turf infill formed by the irregularly shaped
grains. This
may reduce the amount of elastomeric granulates that are used. As a smaller
amount of the elastomeric granulate is used, it may reduce the splash effect
when a
ball or other object impacts the artificial turf surface.
In another embodiment, the regularly shaped granules comprise any one of the
following: a least one thermoplastic polymer, a polyolefin, waste plastic,
fibrous
waste plastic, pre-consumer yarn, post-consumer yarn recovered synthetic
sports
fields, artificial turf fiber, recovered waste plastic, recycled packaging
material, poly
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ethylene food packaging, EPDM, LLDPE, HDPE, LDPE, MDPE, PP, PE, a
polyolefin, an elastomeric compound, rubber, crumb rubber, and combinations
thereof.
5 In another embodiment, the top infill comprises elongated granules. In
some
examples, the elongated granules may comprise an elastic or flexible material.
The
use of the elongated granulates in the top infill may have several advantages.
First,
the elongated shape may help the top infill to remain above or covering the
infill
made from the irregularly shaped grains. The elongated shape may, in some
10 examples, result in less friction between a person or object sliding on
the artificial
turf. The use of the elongated granules may also reduce the splash effect when
a
ball or other object impacts the artificial turf surface.
In another embodiment, the elongated granulate are formed from any one of the
following: an elastomeric compound, shavings from a block of an elastomeric
compound, rubber, crumb rubber, EPDM, and combinations thereof.
In another embodiment the elongated granulate are shavings formed from a block
of
an elastomeric compound. The use of the shavings from an elastomeric compound
may make the artificial turf surface appear more realistic. The use of
shavings from
an elastomeric compound may also make the shaving have a fiber like structure
that
helps to keep them in place and reduce the splash effect.
In another embodiment, the top infill comprises at least 40%, 50%, 60%, 70%,
80%,
90%, or 95% of the elongated granules by weight. This embodiment may be
beneficial because it may provide for an artificial turf surface that is less
likely to
damage or irritate the skin of a player when sliding on the playing surface.
The
reduction of the splash effect may also increase with a larger proportion of
the
elongated granules in the top infill.
In another embodiment, the top infill consists of the elongated granules. This
embodiment may have the benefit of further reducing the splash effect.
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In another embodiment, the artificial turf surface further comprises a sand
layer
between the backing and the artificial turf infill. The artificial turf
surface further
comprises a top infill layer, wherein the irregularly shaped grains are
between the
backing and the top infill layer. The top infill comprises irregularly shaped
granulate.
.. The irregularly shaped granulate comprises shavings from a block of an
elastomeric
compound. This embodiment may be beneficial because the irregularly shaped
granulate may provide shock absorbency and also may reduce the friction
between
an object sliding on the artificial turf surface and the irregularly shaped
grains.
In another aspect, the invention provides for a method of manufacturing an
artificial
turf system. An artificial turf system as used herein encompasses the
components
which are supplied to manufacture an artificial turf surface.
The method comprises providing an artificial turf carpet with a pile. The
artificial turf
carpet comprises a backing. The artificial turf carpet further comprises
artificial grass
fibers. The artificial grass fibers are tufted into the backing. The
artificial grass fibers
form the pile surface. The artificial grass fibers are secured to the backing.
The method further comprises agglomerating the at least one type of non-
elastomeric plastic into an agglomerate for forming irregularly shaped grains
to
provide an infill for the artificial turf carpet.
In another embodiment, the agglomeration of the at least one type of non-
elastomeric thermoplastic into the agglomerate and the forming of the
irregularly
shaped grains form the agglomerate is performed using an agglomerator. An
agglomerator as used herein is a device which applies heat and pressure to
agglomerate multiple thermoplastics into a single structure. The agglomerator
may
also cut or break the agglomeration into the irregularly shaped grains.
The use of an agglomerator may be beneficial because it may provide for an
inexpensive means of manufacturing irregularly shaped grains.
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In another embodiment, the agglomerator is a friction agglomerator. The
friction
agglomerator may have one or more moving portions which use friction to
generate
the heat necessary to form the agglomerate.
In another embodiment, the agglomerator is a disc agglomerator. The disc
agglomerator may have one or more rotating discs which receive the heated non-
elastomeric thermoplastic and agglomerate them into the agglomerate and form
the
irregularly shaped grains at the same time.
In another embodiment, the forming of the irregularly shaped grains from the
agglomerate is performed using an extruder. The use of an extruder may be
beneficial because the properties of the irregularly shaped grains may be
precisely
controlled. An extruder as used herein encompasses a device which heats the at
least one type of non-elastomeric thermoplastic and then forces them through
an
orifice to extrude them. There may also be a device which cuts the extruded
agglomerate into the irregularly shaped grains. The material extruded from the
extruder may be referred to as an extrudate. However, the extrudate is the
agglomerate.
In another embodiment, the extruder comprises any one of the following: an
underwater pelletizing system, a water ring pelletizing system, a strand
pelletizing
system, and a hot-cut pelletizing system.
In another embodiment, the extruder optionally comprises a pelletizer or
granulation
system to additionally form the shape of the irregularly shaped trains.
In another embodiment, the forming of the irregularly shaped grains is
performed
using an extruder. The use of an extruder may be beneficial because it may
allow
for precise control of the properties of the irregularly shaped grains such as
the
length, the amount of curvature of the grain, and the relative size
distribution.
In another embodiment, the extruder comprises an extrusion die plate. The
extrusion die plate has at least one orifice for extruding the agglomerate.
The at
least one orifice has a first portion and an opposing portion. The first
portion is
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rough. The opposing portion is smooth to form irregularly shaped grains that
have a
curved profile. The first portion, which is rough, causes a breaking or
slowing effect
as the agglomerate is extruded. This causes the resulting irregularly shaped
grain to
have a curved profile. This may be beneficial in that it may cause the
irregularly
shaped grains to pack less densely. This may cause them to have a more elastic
behavior although they are made from a non-elastomeric thermoplastic.
In another embodiment, the extruder comprises multiple orifices. The multiple
orifices have at least two distinct sizes. This embodiment may be beneficial
because
the size distribution of the irregularly shaped grains and their relative
frequency can
be precisely controlled.
In another embodiment, the multiple orifices may have an irregular shape or
profile.
The use of the irregular shape or profile may have the benefit of producing
grains of
agglomerate that are irregularly shaped.
In another embodiment, the extruder comprises a cutting system for cutting
irregularly shaped grains.
In another embodiment, the cutting system of the extruder is configured for
producing irregularly shaped grains with varying lengths. This may for
instance be
achieved by controlling how often the cutting system cuts off extrudate (the
agglomerate) that is being extruded. By varying the times between when the
agglomerate is cut or choosing a distribution of times the relative size
distribution of
the irregularly shaped grains can be controlled.
In another embodiment, the method further comprises mixing at least one
additive
into the agglomerate before forming the irregularly shaped grains. This may be
beneficial in adding various properties to the irregularly shaped grains such
as flame
retardants, UV protection, or dyes to color to change the appearance of the
artificial
turf infill.
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In another embodiment, the at least one additive comprises any one of the
following:
a colorant or dye, a UV stabilizer, a flame retardant, a filler, a blowing
agent, an anti-
seize agents, a lubricant, compatibilizer, a binding agent, and combinations
thereof.
In another embodiment, the method further comprises recycling used artificial
turf to
provide the at least one of the at least one type of non-elastomeric
thermoplastic.
This may be beneficial in that it may reduce the environmental impact of
installing a
new artificial turf surface. It may also have the benefit that the
thermoplastic
recovered from the used artificial turf may have additives such as colorants
or UV
stabilizers or flame retardants that are already present. This may reduce the
cost of
manufacturing a new artificial turf surface.
In another embodiment the agglomerate at least comprises 80%, 90%, 95%, or 99%
by weight the at least one type of non-elastomeric thermoplastic. In other
words the
agglomerate is at least 80%, 90%, 95%, or 99% (by weight) made from the at
least
one non-elastomeric thermoplastic. Increasing the amount of the non-
elastomeric
thermoplastic may have the benefit of increasing the mechanical stability of
the
fibrous extensions. If other materials such as sand or elastomeric materials
are
mixed into the agglomerate the irregularly shaped grains may be structurally
compromised.
In another embodiment the agglomerate consists of the at least one type of non-
elastomeric thermoplastic. This embodiment may be beneficial because the
agglomerate is completely made from the at least one type of non-elastomeric
thermoplastic. Although the agglomerate is made from the non-elastomeric
thermoplastic it is flexible due to the fibrous extensions. The fibrous
extensions are
less likely to break apart when formed entirely from the at least one type of
non-
elastomeric thermoplastic.
In another embodiment the irregularly shaped grains consist of the
agglomerate.
This may provide for better structural integrity of the irregularly shaped
grains.
In another aspect, the invention provides for a method of manufacturing an
artificial
turf surface. The method comprises a method of manufacturing an artificial
turf
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system according to an embodiment. The method further comprises installing the
artificial turf carpet. The method further comprises distributing the
irregularly shaped
grains within the pile and between the artificial grass fibers to form the
artificial turf.
5 In another embodiment, the method of manufacturing the artificial turf
surface
comprises distributing a sand layer within the pile before distributing the
irregularly
shaped grains.
In another aspect, the invention provides for use of an agglomerate as infill
for
10 artificial turf. The agglomerate comprises irregularly shaped grains
formed for at
least one type of non-elastomeric thermoplastic. At least a portion of the
grains may
have fibrous extensions.
It is understood that one or more of the aforementioned embodiments of the
15 invention may be combined as long as the combined embodiments are not
mutually
exclusive.
Brief description of the drawings
In the following embodiments of the invention are explained in greater detail,
by way
of example only, making reference to the drawings in which:
Fig. 1 illustrates an example of an artificial turf surface;
Fig. 2 illustrates a further example of an artificial turf surface;
Fig. 3 illustrates an examples of an irregularly shaped grains;
Fig. 4 illustrates an example of an agglomerator;
Fig. 5 illustrates an example of an extruder;
Fig. 6 illustrates an example of an extrusion die plate;
Fig. 7 illustrates an example of an artificial turf system;
Fig. 8 illustrates a further example of an artificial turf surface;
Fig. 9 illustrates a further example of an extrusion die plate; and
Fig. 10 illustrates a further example of an artificial turf surface.
Detailed Description
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Like numbered elements in these figures are either equivalent elements or
perform
the same function. Elements which have been discussed previously will not
necessarily be discussed in later figures if the function is equivalent.
Fig. 1 shows an example of an artificial turf surface 100. The artificial turf
surface
100 is formed by an artificial turf carpet 102 that has a pile 104. The
artificial turf
carpet 102 comprises a backing 106. Into the backing there are artificial
grass fibers
108 that are tufted 110 into the backing 106. The pile 104 is formed from the
artificial grass fibers 108. The artificial grass fibers 108 may for instance
be formed
from a thermoplastic yarn or artificial grass. The backing 106 may be placed
onto a
base layer 112. The base layer may take different forms in different examples.
In
one example the base layer is simply the ground. The artificial turf carpet
102 may
simply be placed on the ground. In other examples the base layer 112 may have
different components for providing drainage, and absorption of shock from
athletes
or other users of the artificial turf surface 100.
Within the pile 104 and between the artificial grass fibers 108 is spread an
artificial
turf infill 114. In this case the infill 114 comprises irregularly shaped
grains 116. The
irregularly shaped grains are formed from an agglomerate comprising at least
one
type of non-elastomeric thermoplastic. The non-elastomeric thermoplastics may
also
be thermoplastic polymers. The use of the irregularly shaped grains causes
voids
118 between a number of the irregularly shaped grains 116. These voids provide
give and elasticity to the irregularly shaped grains 116 that are made of what
is
considered normally a rigid thermoplastic. This enables a material which would
normally be unsuitable for making artificial turf infill function well. The
artificial turf
infill 114 may provide for helping the artificial grass fibers 108 to stay
rigid and in the
correct position. They may also provide for shock absorption or other physical
properties which help the artificial turf surface 100 more approximate the
properties
of a real turf surface.
Fig. 2 shows a further example of an artificial turf surface 200. The
artificial turf
surface 200 is similar to the artificial turf surface 100 shown in Fig. 1.
However, in
this example there is additionally a layer of sand between the backing and the
infill
114. The example shown in Fig. 2 may further approximate the properties of
real turf
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more accurately. The use of the infill 114 with the irregularly shaped grains
116 may
provide a more lifelike and elastic surface than when sand 202 is used alone.
Fig. 3 shows a photograph of a number of irregularly shaped grains 116. The
irregularly shaped grains comprise at least one non-elastomeric polymer. The
photograph shows that at least some of the irregularly shaped grains comprise
fibrous extensions 302. Not all of the fibrous structure of the extensions is
visible in
the photograph. Some of the grains also show fibrous extensions 302 with a
branched structure 304. Some of the fibrous extensions 302 also have a hook
like
structure 306. The branched structure 304 or hook like structure 306 may help
the
irregularly shaped grains interlock with themselves and/or artificial grass
fibers.
thermoplastics.
The irregularly shaped grains in Fig. 3 were tested as artificial turf infill.
Although
made from rigid thermoplastics they exhibited shock absorbency. Recycled SBR
rubber infill was compared to irregularly shaped grain infill of two different
sizes. The
first size of irregularly shaped grain infill had a characteristic dimension
of less than
2.5 mm. The second size had a characteristic dimension greater than 2.5 mm. A
sieve with a 2.5 mm screen was used to separate the two. In the experiment the
force reduction of a soccer ball hitting the surface was measured for three
consecutive hits at the same location for each hit. The results are summarized
in the
table below
SBR infill agglomerate agglomerate
As benchmark <2.5 mm > 2.5 mm
Force reduction 1st hit 32.8% 40.3% 36.6%
Force reduction 2nd hit 19.3% 9.8% 25.7%
Force reduction 3rd hit 15.8% 6.1% 19.8%
In the above table it can be see that the agglomerate infill made from the
irregularly
shaped grains has a shock absorbency that is comparable to the SBR infill made
from recycled black crumb rubber. In fact, the larger grains (greater than 2.5
mm)
surprisingly showed shock absorbency that was greater than the SBR infill
material
for all three impacts.
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Fig. 4 shows an example of an agglomerator 400. The agglomerator has a hopper
402 for receiving waste thermoplastic 404. A feeder 406 then feeds the waste
thermoplastic 404 into a an agglomerator 408 which comprises a rotating disc
and
a stationary portion The agglomerator 408 may heat and compress the waste
thermoplastic 404. The rotating disc 408 may have veins or gear-like surfaces
which
compress and cut the waste thermoplastic 404 into the irregularly shaped
grains
116.
Fig. 5 shows an example of an extruder 500. The extruder again has a hopper
for
receiving waste thermoplastic 404. The waste thermoplastic is then fed by a
feeder
406 which heats and forces the waste thermoplastic through an orifice through
an
extrusion die plate 504. A cutting system 506 then cuts agglomerate that is
extruded
from the orifice 502 into the irregularly shaped grains 116. The rate at which
the
cutting system 508 cuts the agglomerate will control the length of the
irregularly
shaped grains 116. The rate of the cutting system 506 can be varied to produce
a
distribution of lengths of irregularly shaped grains 116.
Fig. 6 shows an example of an extrusion die plate 504 with an orifice 502. The
orifice 502 has a first portion 600 and an opposing portion 602. The first
portion 600
is rough and the opposing portion 602 is smooth. This modification will cause
material extruded from the orifice 502 to have a curvature to it.
Fig. 7 shows a flowchart which illustrates a method of manufacturing an
artificial turf
system. First in step 700 an artificial turf carpet 102 such as shown in Figs.
1 or 2 is
provided. Next in step 702 irregularly shaped grains 116 are manufactured
using the
machine such as is illustrated in Fig. 4 or 5. At least one type of non-
elastomeric
thermoplastic is either provided as an agglomerate or formed with another
material
such as a second elastomeric thermoplastic or a dye in power form. The
agglomerate is then forced into the irregularly shaped grains 116. In some
examples, the agglomeration process is used to form the irregularly shaped
grains.
In other examples, an extruder or agglomerator is used to form the agglomerate
into
the irregularly shaped grains.
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Fig. 8 shows a further example of an artificial turf surface 800. The
artificial turf
surface 800 is similar to the artificial turf surface 200 shown in Fig. 2.
However, in
this example there is additionally a top infill layer (801) that comprises
regularly
shaped granules 802. The top infill layer (801) is on top of the irregularly
shaped
grains 114. The use of the regularly shaped granules 802 have the advantage of
reducing the friction when something slides on the surface of the artificial
turf
surface 800. The regularly shaped granules 802 may be made of several
different
materials. In one example the regularly shaped granules are made from a
agglomerate comprising at least one type of non-elastomeric thermoplastic. In
another example the regularly shaped granules are made from an elastomer.
Fig. 9 illustrates another example of an extrusion die plate (504) similar to
that
shown in Fig. 6. The extrusion die plate has a number of orifices 502' for
extruding
the irregularly shaped granules. The orifices have a variety of different
sizes. The
relative sizes of the orifices can be used to generate a distribution of
grains with
different sizes. The shape or profile of the orifices can also be modified to
aid in
providing the grains with an irregular shape.
Fig. 10 shows a further example of an artificial turf surface 1000. The
artificial turf
surface 1000 is similar to the artificial turf surface 800 shown in Fig. 8.
However, in
this example the top infill layer comprises either elongated granules 1002
and/or
irregularly shaped granulate 1002 on top of the irregularly shaped grains 114.
The
use of the elongated granules 1002 and/or irregularly shaped granulate 1002
may
have the advantage of reducing the friction when something slides on the
surface of
the artificial turf surface 1002. The elongated granules 1002 and/or
irregularly
shaped granulate 1002 may be made of several different materials. In one
example
the elongated granules 1002 and/or irregularly shaped granulate 1002 may for
example be manufactured from an elastomeric compound or other flexible
material.
The following examples are several possible practical examples of artificial
turf
surfaces that use the irregularly shaped grains as artificial turf infill.
Artificial turf infill
made from irregularly shaped grains is referred to as "polymer agglomerate."
All
weights refer to the amount of material distributed on the surface of an
artificial turf
carpet. The polymer agglomerate is placed on top of the sand layer. The term e-
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layer refers to a substructure made of a shock absorptive layer of rubber
granulate,
matting, or other material under the artificial turf carpet.
Example 1 (artificial turf carpet with a 40 mm high pile):
5 Polymer agglomerate: 5 kg/m2
Sand: 15 kg/m2
e-layer: 25 mm
Example 2 (artificial turf carpet with a 40 mm high pile):
10 Polymer agglomerate: 7,5 kg/m2
Sand: 12.5 kg/m2
e-layer: 25 mm
Example 3 (artificial turf carpet with a 40 mm high pile):
15 Polymer agglomerate: 5 kg/m2
Sand: 15 kg/m2
e-layer: 30 mm
Example 4 (artificial turf carpet with a 40 mm high pile):
20 Polymer agglomerate: 5 kg/m2
Size distribution: 0 - 2.5 mm (sorted by sieve size)
Sand: 15 kg/m2
e-layer: 25 mm
Example 5 (artificial turf carpet with a 40 mm or 60 mm high pile):
Polymer agglomerate: 5 kg/m2
Size distribution: 2.5- 12.5 mm (sorted by sieve size)
Sand: 15 kg/m2
e-layer: 25 mm
In the 5 above examples, the numerical values may be varied by up to 10%, 20,
or
30% to produce alternative examples.
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In examples 1 through 3, so size distribution of the polymer agglomerate is
given. It
is understood that any sieve size between 1 and 12,5 mm may be used to sort
agglomerate for these two examples.
In examples 4 and 5: Grains that pass through the 2,5 mm sieve are used for
example 4. The grains that are caught by the 2.5 mm sieve, but pass through a
12.5
mm sieve are used for example 5.
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List of reference numerals
100 artificial turf surface
102 artificial turf carpet
104 pile
106 backing
108 artificial grass fibers
110 tufting
112 base layer
114 infill
116 irregularly shaped grains
118 void
200 artificial turf surface
202 sand
302 fibrous extensions
304 branched structure
306 hook like structure
400 agglomerator
402 hopper
404 waste thermoplastic
408 agglomerator disk
500 extruder
502 orifice
502' orifice
504 extrusion die plate
506 cutting system
600 first portion
602 opposing portion
700 provide an artificial turf carpet with a pile,
702 form an agglomerate comprising least one type of
non-
elastomeric thermoplastic into irregularly shaped grains
to provide an infill for the artificial turf carpet
800 artificial turf surface
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801 top infill layer
802 regularly shaped granules
1000 artificial turf surface
1002 elongated granules or irregularly shaped granulate
