U.S. patent application number 16/958035 was filed with the patent office on 2021-03-04 for artificial turf system.
The applicant listed for this patent is Dow Global Technologies LLC. Invention is credited to Eduardo Alvarez, Joseph L. Deavenport, Kurt A. Koppi, David Lopez, Viraj K. Shah.
Application Number | 20210062436 16/958035 |
Document ID | / |
Family ID | 1000005264392 |
Filed Date | 2021-03-04 |
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United States Patent
Application |
20210062436 |
Kind Code |
A1 |
Lopez; David ; et
al. |
March 4, 2021 |
Artificial Turf System
Abstract
Artificial turf system (10) including a primary backing layer
(12) and a shock absorption component (20). The primary backing
layer (12) has a plurality of artificial turf yarns (14) projecting
upwardly from the primary backing layer (12). The shock absorption
component (20) is composed of a sheet of three-dimensional random
loop material 3DRLM (30). The sheet of 3DRLM (30) is in contact
with the primary backing layer (12). The shock absorption component
(20) includes (i) a cushioning layer (40) and (ii) a shockpad (50).
The 3DRLM (30) in the cushioning layer (40) has an apparent density
that is greater than the apparent density of the 3DRLM (30) in the
shockpad (50).
Inventors: |
Lopez; David; (Tarragona,
ES) ; Alvarez; Eduardo; (Tarragona, ES) ;
Deavenport; Joseph L.; (Freeport, TX) ; Shah; Viraj
K.; (Lake Jackson, TX) ; Koppi; Kurt A.;
(Midland, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Global Technologies LLC |
Midland |
MI |
US |
|
|
Family ID: |
1000005264392 |
Appl. No.: |
16/958035 |
Filed: |
December 28, 2018 |
PCT Filed: |
December 28, 2018 |
PCT NO: |
PCT/US2018/067821 |
371 Date: |
June 25, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D10B 2403/033 20130101;
D02G 3/34 20130101; E01C 13/02 20130101; E01C 13/08 20130101 |
International
Class: |
E01C 13/08 20060101
E01C013/08; E01C 13/02 20060101 E01C013/02; D02G 3/34 20060101
D02G003/34 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2017 |
EP |
17382915.1 |
Claims
1. An artificial turf system comprising: a primary backing layer
having a plurality of artificial turf yarns projecting upwardly
from the primary backing layer; a shock absorption component
composed of a sheet of three-dimensional random loop material
(3DRLM) and in contact with the primary backing layer, the shock
absorption component comprising (i) a cushioning layer; and (ii) a
shockpad; and the 3DRLM in the cushioning layer has an apparent
density that is greater than the apparent density of the 3DRLM in
the shockpad.
2. The artificial turf system of claim 1 wherein the cushioning
layer is integral to the shockpad.
3. The artificial turf system of claim 2 wherein the 3DRLM
comprises a plurality of multiple loops formed by a plurality of
continuous fibers composed of polymeric material; and at least two
continuous fibers extend from the shockpad to the cushioning
layer.
4. The artificial turf system of claim 1 wherein the shockpad has a
thickness, measured in millimeters, from 2 times to 300 times
greater than the thickness of the cushioning layer.
5. The artificial turf system of claim 4 wherein the apparent
density of the cushioning layer is from 2 times to 400 times
greater than the apparent density of the shockpad.
6. The artificial turf system of claim 1 wherein the shockpad has
an apparent density from 0.010 g/cc to 0.400 g/cc.
7. The artificial turf system of claim 6 wherein the cushioning
layer has an apparent density from 0.030 g/cc to 1.000 g/cc.
8. The artificial turf system of claim 1 wherein the 3DRLM is
composed of an ethylene-based polymer.
9. The artificial turf system of claim 1 comprising an infill
material.
10. The artificial turf system of claim 9 wherein the turf yarn,
the primary backing layer, the 3DRLM, and the infill material each
is composed of an olefin-based polymer.
Description
BACKGROUND
[0001] Interest in artificial turf in recent years has been
explosive. Artificial turf (otherwise known as "pitch") is
increasingly used to replace natural grass on playing surfaces, in
particular on sports fields and playgrounds. Artificial turf also
finds application in landscaping and leisure settings.
[0002] In "third generation artificial turf, or "3G turf," the
artificial grass blades (the "pile") is supported by a thin base
layer of sand, and by an infill of rubber crumb. The pile height
ranges from 40 millimeters (mm) to 65 mm depending upon the primary
sport to be played on the surface. Most 3G pitches consist of
polyethylene (PE) yarns tufted to a primary backing. Typically,
tuft lock is achieved by applying a polyurethane (PU) secondary
backing coating or a styrene-butadiene-latex secondary backing
coating. Infill is then spread between yarn fibers to stabilize the
fiber vertical position, provide traction to players, and
contribute to shock absorption of the system. In combination with
suitable infill, a foamed PU shockpad layer is also installed under
the system to optimize the shock absorption.
[0003] Artificial turf systems are used in contact sport pitches in
order to improve player safety and to improve game consistency. A
significant feature of artificial turf is its ability to absorb
shocks. The shock absorption element of artificial turf includes
the infill material and the shock pad. However, the use of these
components presents a number of drawbacks.
[0004] Infill is disadvantageous because infill requires constant
maintenance--uniform distribution of the infill granules is
required to reduce risk of player injury. In addition, the shock
absorption capability of the infill degrades over time, requiring
replenishment of the infill and adding to the cost.
[0005] Use of crumb rubber and/or sand infill granules, alone or in
combination with a PU shockpad makes incumbent artificial turf
systems difficult to recycle leading incineration or disposal
costs.
[0006] The art recognizes the need for alternative artificial turf
systems with improved shock absorption capability alone or in
combination with improved recyclability.
SUMMARY
[0007] The present disclosure provides an artificial turf system.
In an embodiment, the artificial turf system includes a primary
backing layer and a shock absorption component. The primary backing
layer has a plurality of artificial turf yarns projecting upwardly
from the primary backing layer. The artificial turf system also
includes a shock absorption component. The shock absorption
component is composed of a sheet of three-dimensional random loop
material (3DRLM). The sheet of 3DRLM is in contact with the primary
backing layer. The shock absorption component includes (i) a
cushioning layer and (ii) a shockpad. The 3DRLM in the cushioning
layer has an apparent density that is greater than the apparent
density of the 3DRLM in the shockpad.
[0008] An advantage of the present disclosure is an artificial turf
system having a 3DRLM shock absorption component that is a single
unitary component whereby the shockpad is integral to the
cushioning layer. The integration of the shockpad and the
cushioning into a single unitary shock absorption component
eliminates the need for a secondary backing layer.
[0009] An advantage of the present disclosure is an artificial turf
system with an integrated shockpad and cushioning layer that
reduces the amount of infill material necessary for player
safety.
[0010] An advantage of the present disclosure is an artificial turf
system that is readily recyclable.
DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a cutaway perspective view of an artificial turf
system in accordance with an embodiment of the present
disclosure.
[0012] FIG. 1A is an enlarged view of area 1A of FIG. 1.
[0013] FIG. 2 is a perspective view of a shock absorption component
in accordance with an embodiment of the present disclosure.
DEFINITIONS
[0014] All references to the Periodic Table of the Elements herein
shall refer to the Periodic Table of the Elements, published and
copyrighted by CRC Press, Inc., 2003. Also, any references to a
Group or Groups shall be to the Groups or Groups reflected in this
Periodic Table of the Elements using the IUPAC system for numbering
groups. Unless stated to the contrary, implicit from the context,
or customary in the art, all components and percents are based on
weight. For purposes of United States patent practice, the contents
of any patent, patent application, or publication referenced herein
are hereby incorporated by reference in their entirety (or the
equivalent US version thereof is so incorporated by reference).
[0015] The numerical ranges disclosed herein include all values
from, and including, the lower value and the upper value. For
ranges containing explicit values (e.g., 1, or 2, or 3 to 5, or 6,
or 7) any subrange between any two explicit values is included
(e.g., 1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6; etc.).
[0016] Unless stated to the contrary, implicit from the context, or
customary in the art, all components and percents are based on
weight, and all test methods are current as of the filing date of
this disclosure.
[0017] "Blend," "polymer blend" and like terms is a composition of
two or more polymers. Such a blend may or may not be miscible. Such
a blend may or may not be phase separated. Such a blend may or may
not contain one or more domain configurations, as determined from
transmission electron spectroscopy, light scattering, x-ray
scattering, and any other method known in the art. Blends are not
laminates, but one or more layers of a laminate can comprise a
blend.
[0018] "Composition" and like terms is a mixture of two or more
materials. Included in compositions are pre-reaction, reaction and
post-reaction mixtures, the latter of which will include reaction
products and by-products as well as unreacted components of the
reaction mixture and decomposition products, if any, formed from
the one or more components of the pre-reaction or reaction
mixture.
[0019] The terms "comprising," "including," "having," and their
derivatives, are not intended to exclude the presence of any
additional component, step or procedure, whether or not the same is
specifically disclosed. In order to avoid any doubt, all
compositions claimed through use of the term "comprising" may
include any additional additive, adjuvant, or compound, whether
polymeric or otherwise, unless stated to the contrary. In contrast,
the term, "consisting essentially of" excludes from the scope of
any succeeding recitation any other component, step or procedure,
excepting those that are not essential to operability. The term
"consisting of" excludes any component, step or procedure not
specifically delineated or listed.
[0020] An "ethylene-based polymer" is a polymer that contains more
than 50 weight percent polymerized ethylene monomer (based on the
total weight of polymerizable monomers) and, optionally, may
contain at least one comonomer. Ethylene-based polymer includes
ethylene homopolymer, and ethylene copolymer (meaning units derived
from ethylene and one or more comonomers). The terms
"ethylene-based polymer" and "polyethylene" may be used
interchangeably. Nonlimiting examples of ethylene-based polymer
(polyethylene) include low density polyethylene (LDPE) and linear
polyethylene. Nonlimiting examples of linear polyethylene include
linear low density polyethylene (LLDPE), ultra low density
polyethylene (ULDPE), very low density polyethylene (VLDPE),
multi-component ethylene-based copolymer (EPE),
ethylene/.alpha.-olefin multi-block copolymers (also known as
olefin block copolymer (OBC)), single-site catalyzed linear low
density polyethylene (m-LLDPE), substantially linear, or linear,
plastomers/elastomers, and high density polyethylene (HDPE).
Generally, polyethylene may be produced in gas-phase, fluidized bed
reactors, liquid phase slurry process reactors, or liquid phase
solution process reactors, using a heterogeneous catalyst system,
such as Ziegler-Natta catalyst, a homogeneous catalyst system,
comprising Group 4 transition metals and ligand structures such as
metallocene, non-metallocene metal-centered, heteroaryl,
heterovalent aryloxyether, phosphinimine, and others. Combinations
of heterogeneous and/or homogeneous catalysts also may be used in
either single reactor or dual reactor configurations.
[0021] "High density polyethylene" (or "HDPE") is an ethylene
homopolymer or an ethylene/.alpha.-olefin copolymer with at least
one C.sub.4-C.sub.10 .alpha.-olefin comonomer, or C.sub.4-C.sub.8
.alpha.-olefin comonomer and a density from greater than 0.94 g/cc,
or 0.945 g/cc, or 0.95 g/cc, or 0.955 g/cc to 0.96 g/cc, or 0.97
g/cc, or 0.98 g/cc. The HDPE can be a monomodal copolymer or a
multimodal copolymer. A "monomodal ethylene copolymer" is an
ethylene/C.sub.4-C.sub.10 .alpha.-olefin copolymer that has one
distinct peak in a gel permeation chromatography (GPC) showing the
molecular weight distribution. A "multimodal ethylene copolymer" is
an ethylene/C.sub.4-C.sub.10 .alpha.-olefin copolymer that has at
least two distinct peaks in a GPC showing the molecular weight
distribution. Multimodal includes copolymer having two peaks
(bimodal) as well as copolymer having more than two peaks.
Nonlimiting examples of HDPE include DOW.TM. High Density
Polyethylene (HDPE) Resins (available from The Dow Chemical
Company), ELITE''' Enhanced Polyethylene Resins (available from The
Dow Chemical Company), CONTINUUM''' Bimodal Polyethylene Resins
(available from The Dow Chemical Company), LUPOLEN.TM. (available
from LyondellBasell), as well as HDPE products from Borealis,
Ineos, and Exxon Mobil.
[0022] An "interpolymer" is a polymer prepared by the
polymerization of at least two different monomers. This generic
term includes copolymers, usually employed to refer to polymers
prepared from two different monomers, and polymers prepared from
more than two different monomers, e.g., terpolymers, tetrapolymers,
etc.
[0023] "Low density polyethylene" (or "LDPE") includes ethylene
homopolymer, or ethylene/.alpha.-olefin copolymer comprising at
least one C.sub.3-C.sub.10 .alpha.-olefin, preferably
C.sub.3-C.sub.4 .alpha.-olefin the LDPE having a density from 0.915
g/cc to 0.940 g/cc and containing a long chain branching with broad
MWD. LDPE is typically produced by way of high pressure free
radical polymerization (tubular reactor or autoclave with free
radical initiator). Nonlimiting examples of LDPE include
MarFlex.TM. (Chevron Phillips), LUPOLEN.TM. (LyondellBasell), as
well as LDPE products from Borealis, Ineos, ExxonMobil, and
others.
[0024] "Linear low density polyethylene" (or "LLDPE") is a linear
ethylene/.alpha.-olefin copolymer containing heterogeneous
short-chain branching distribution comprising units derived from
ethylene and units derived from at least one C.sub.3-C.sub.10
.alpha.-olefin comonomer or at least one C.sub.4-C.sub.8
.alpha.-olefin comonomer, or at least one C.sub.6-C.sub.8
.alpha.-olefin comonomer. LLDPE is characterized by little, if any,
long chain branching, in contrast to conventional LDPE. LLDPE has a
density from 0.910 g/cc, or 0.915 g/cc, or 0.920 g/cc, or 0.925
g/cc to 0.930 g/cc, or 0.935 g/cc, or 0.940 g/cc. Nonlimiting
examples of LLDPE include TUFLIN.TM. linear low density
polyethylene resins (available from The Dow Chemical Company),
DOWLEX.TM. polyethylene resins (available from the Dow Chemical
Company), and MARLEX.TM. polyethylene (available from Chevron
Phillips).
[0025] "Ultra low density polyethylene" (or "ULDPE") and "very low
density polyethylene" (or "VLDPE") each is a linear
ethylene/.alpha.-olefin copolymer containing heterogeneous
short-chain branching distribution comprising units derived from
ethylene and units derived from at least one C.sub.3-C.sub.10
.alpha.-olefin comonomer, or at least one C.sub.4-C.sub.8
.alpha.-olefin comonomer, or at least one C.sub.6-C.sub.8
.alpha.-olefin comonomer. ULDPE and VLDPE each has a density from
0.885 g/cc, or 0.90 g/cc to 0.915 g/cc. Nonlimiting examples of
ULDPE and VLDPE include ATTANE.TM. ultra low density polyethylene
resins (available form The Dow Chemical Company) and FLEXOMER.TM.
very low density polyethylene resins (available from The Dow
Chemical Company).
[0026] "Multi-component ethylene-based copolymer" (or "EPE")
comprises units derived from ethylene and units derived from at
least one C.sub.3-C.sub.10 .alpha.-olefin comonomer, or at least
one C.sub.4-C.sub.8 .alpha.-olefin comonomer, or at least one
C.sub.6-C.sub.8 .alpha.-olefin comonomer, such as described in
patent references U.S. Pat. Nos. 6,111,023; 5,677,383; and
6,984,695. EPE resins have a density from 0.905 g/cc, or 0.908
g/cc, or 0.912 g/cc, or 0.920 g/cc to 0.926 g/cc, or 0.929 g/cc, or
0.940 g/cc, or 0.962 g/cc. Nonlimiting examples of EPE resins
include ELITE''' enhanced polyethylene (available from The Dow
Chemical Company), ELITE AT.TM. advanced technology resins
(available from The Dow Chemical Company), SURPASS.TM. Polyethylene
(PE) Resins (available from Nova Chemicals), and SMART.TM.
(available from SK Chemicals Co.).
[0027] "Single-site catalyzed linear low density polyethylenes" (or
"m-LLDPE") are linear ethylene/.alpha.-olefin copolymers containing
homogeneous short-chain branching distribution comprising units
derived from ethylene and units derived from at least one
C.sub.3-C.sub.10 .alpha.-olefin comonomer, or at least one
C.sub.4-C.sub.8 .alpha.-olefin comonomer, or at least one
C.sub.6-C.sub.8 .alpha.-olefin comonomer. m-LLDPE has density from
0.913 g/cc, or 0.918 g/cc, or 0.920 g/cc to 0.925 g/cc, or 0.940
g/cc. Nonlimiting examples of m-LLDPE include EXCEED.TM.
metallocene PE (available from ExxonMobil Chemical), LUFLEXEN.TM.
m-LLDPE (available from LyondellBasell), and ELTEX.TM. PF m-LLDPE
(available from Ineos Olefins & Polymers).
[0028] "Ethylene plastomers/elastomers" are substantially linear,
or linear, ethylene/.alpha.-olefin copolymers containing
homogeneous short-chain branching distribution comprising units
derived from ethylene and units derived from at least one
C.sub.3-C.sub.10 .alpha.-olefin comonomer, or at least one
C.sub.4-C.sub.8 .alpha.-olefin comonomer, or at least one
C.sub.6-C.sub.8 .alpha.-olefin comonomer. Ethylene
plastomers/elastomers have a density from 0.870 g/cc, or 0.880
g/cc, or 0.890 g/cc to 0.900 g/cc, or 0.902 g/cc, or 0.904 g/cc, or
0.909 g/cc, or 0.910 g/cc, or 0.917 g/cc. Nonlimiting examples of
ethylene plastomers/elastomers include AFFINITY''' plastomers and
elastomers (available from The Dow Chemical Company), EXACT'''
Plastomers (available from ExxonMobil Chemical), Tafmer.TM.
(available from Mitsui), Nexlene.TM. (available from SK Chemicals
Co.), and Lucene.TM. (available LG Chem Ltd.).
[0029] An "olefin-based polymer," as used herein, is a polymer that
contains more than 50 weight percent polymerized olefin monomer
(based on total amount of polymerizable monomers), and optionally,
may contain at least one comonomer. Nonlimiting examples of
olefin-based polymer include ethylene-based polymer and
propylene-based polymer.
[0030] A "polymer" is a compound prepared by polymerizing monomers,
whether of the same or a different type, that in polymerized form
provide the multiple and/or repeating "units" or "mer units" that
make up a polymer. The generic term polymer thus embraces the term
homopolymer, usually employed to refer to polymers prepared from
only one type of monomer, and the term copolymer, usually employed
to refer to polymers prepared from at least two types of monomers.
It also embraces all forms of copolymer, e.g., random, block, etc.
The terms "ethylene/.alpha.-olefin polymer" and
"propylene/.alpha.-olefin polymer" are indicative of copolymer as
described above prepared from polymerizing ethylene or propylene
respectively and one or more additional, polymerizable
.alpha.-olefin monomer. It is noted that although a polymer is
often referred to as being "made of" one or more specified
monomers, "based on" a specified monomer or monomer type,
"containing" a specified monomer content, or the like, in this
context the term "monomer" is understood to be referring to the
polymerized remnant of the specified monomer and not to the
unpolymerized species. In general, polymers herein are referred to
has being based on "units" that are the polymerized form of a
corresponding monomer.
[0031] A "propylene-based polymer" is a polymer that contains more
than 50 weight percent polymerized propylene monomer (based on the
total amount of polymerizable monomers) and, optionally, may
contain at least one comonomer.
Test Methods
[0032] Apparent density. A sample material is cut into a square
piece of 38 cm.times.38 cm (15 in.times.15 in) in size. The volume
of this piece is calculated from the thickness measured at four
points. The division of the weight by the volume gives the apparent
density (an average of four measurements is taken) with values
reported in grams per cubic centimeter, g/cc.
[0033] Ball rebound: A ball is released from 2 meters and the
height of its rebound from the surface is calculated. Results are
reported in meters (m).
[0034] Bending Stiffness. The bending stiffness is measured in
accordance with DIN 53121 standard, with compression molded plaques
of 550 .mu.m thickness, using a Frank-PTI Bending Tester. The
samples are prepared by compression molding of resin granules per
ISO 293 standard. Conditions for compression molding are chosen per
ISO 1872-2007 standard. The average cooling rate of the melt is
15.degree. C./min. Bending stiffness is measured in 2-point bending
configuration at room temperature with a span of 20 mm, a sample
width of 15 mm, and a bending angle of 40.degree.. Bending is
applied at 6.degree./second (s) and the force readings are obtained
from 6 to 600 s, after the bending is complete. Each material is
evaluated four times with results reported in Newton millimeters
("Nmm").
[0035] .sup.13C Nuclear Magnetic Resonance (NMR)
[0036] Sample Preparation
[0037] The samples are prepared by adding approximately 2.7 g of a
50/50 mixture of tetrachloroethane-d2/orthodichlorobenzene that is
0.025M in chromium acetylacetonate (relaxation agent) to 0.21 g
sample in a 10 mm NMR tube. The samples are dissolved and
homogenized by heating the tube and its contents to 150.degree.
C.
[0038] Data Acquisition Parameters
[0039] The data is collected using a Bruker 400 MHz spectrometer
equipped with a Bruker Dual DUL high-temperature CryoProbe. The
data is acquired using 320 transients per data file, a 7.3 sec
pulse repetition delay (6 sec delay+1.3 sec acq. time), 90 degree
flip angles, and inverse gated decoupling with a sample temperature
of 125.degree. C. All measurements are made on non-spinning samples
in locked mode. Samples are homogenized immediately prior to
insertion into the heated (130.degree. C.) NMR Sample changer, and
are allowed to thermally equilibrate in the probe for 15 minutes
prior to data acquisition.
[0040] Crystallization Elution Fractionation (CEF) Method
[0041] Comonomer distribution analysis is performed with
Crystallization Elution Fractionation (CEF) (PolymerChar in Spain)
(B Monrabal et al, Macromol. Symp. 257, 71-79 (2007)).
Ortho-dichlorobenzene (ODCB) with 600 ppm antioxidant butylated
hydroxytoluene (BHT) is used as solvent. Sample preparation is done
with autosampler at 160.degree. C. for 2 hours under shaking at 4
mg/ml (unless otherwise specified). The injection volume is 300
.mu.m. The temperature profile of CEF is: crystallization at
3.degree. C./min from 110.degree. C. to 30.degree. C., the thermal
equilibrium at 30.degree. C. for 5 minutes, elution at 3.degree.
C./min from 30.degree. C. to 140.degree. C. The flow rate during
crystallization is at 0.052 ml/min. The flow rate during elution is
at 0.50 ml/min. The data is collected at one data point/second. CEF
column is packed by the Dow Chemical Company with glass beads at
125 .mu.m+6% (MO-SCI Specialty Products) with 1/8 inch stainless
tubing. Glass beads are acid washed by MO-SCI Specialty with the
request from The Dow Chemical Company. Column volume is 2.06 ml.
Column temperature calibration is performed by using a mixture of
NIST Standard Reference Material Linear polyethylene 1475a (1.0
mg/ml) and Eicosane (2 mg/ml) in ODCB. Temperature is calibrated by
adjusting elution heating rate so that NIST linear polyethylene
1475a has a peak temperature at 101.0.degree. C., and Eicosane has
a peak temperature of 30.0.degree. C. The CEF column resolution is
calculated with a mixture of NIST linear polyethylene 1475a (1.0
mg/ml) and hexacontane (Fluka, purum, >97.0, 1 mg/ml). A
baseline separation of hexacontane and NIST polyethylene 1475a is
achieved. The area of hexacontane (from 35.0 to 67.0.degree. C.) to
the area of NIST 1475a from 67.0 to 110.0.degree. C. is 50 to 50,
the amount of soluble fraction below 35.0.degree. C. is <1.8 wt
%. The CEF column resolution is defined in the following
equation:
Resolution=Peak temperature of NIST 1475a-Peak Temperature of
Hexacontane/Half-height Width of NIST 1475a+Half-height Width of
Hexacontane [0042] where the column resolution is 6.0.
[0043] Density is measured in accordance with ASTM D 792 with
values reported in grams per cubic centimeter, g/cc.
[0044] Differential Scanning calorimetry (DSC). Differential
Scanning calorimetry (DSC) is used to measure the melting and
crystallization behavior of a polymer over a wide range of
temperatures. For example, the TA Instruments Q1000 DSC, equipped
with an RCS (refrigerated cooling system) and an autosampler is
used to perform this analysis. During testing, a nitrogen purge gas
flow of 50 ml/min is used. Each sample is melt pressed into a thin
film at about 175.degree. C.; the melted sample is then air-cooled
to room temperature (approx. 25.degree. C.). The film sample is
formed by pressing a "0.1 to 0.2 gram" sample at 175.degree. C. at
1,500 psi, and 30 seconds, to form a "0.1 to 0.2 mil thick" film. A
3-10 mg, 6 mm diameter specimen is extracted from the cooled
polymer, weighed, placed in a light aluminum pan (ca 50 mg), and
crimped shut. Analysis is then performed to determine its thermal
properties. The thermal behavior of the sample is determined by
ramping the sample temperature up and down to create a heat flow
versus temperature profile. First, the sample is rapidly heated to
180.degree. C., and held isothermal for five minutes, in order to
remove its thermal history. Next, the sample is cooled to
-40.degree. C., at a 10.degree. C./minute cooling rate, and held
isothermal at -40.degree. C. for five minutes. The sample is then
heated to 150.degree. C. (this is the "second heat" ramp) at a
10.degree. C./minute heating rate. The cooling and second heating
curves are recorded. The cool curve is analyzed by setting baseline
endpoints from the beginning of crystallization to -20.degree. C.
The heat curve is analyzed by setting baseline endpoints from
-20.degree. C. to the end of melt. The values determined are peak
melting temperature (Tm), peak crystallization temperature (Tc),
onset crystallization temperature (Tc onset), heat of fusion (Hf)
(in Joules per gram), the calculated % crystallinity for
polyethylene samples using: % Crystallinity for PE=((Hf)/(292
J/g)).times.100, and the calculated % crystallinity for
polypropylene samples using: % Crystallinity for PP=((Hf)/165
J/g)).times.100. The heat of fusion (Hf) and the peak melting
temperature are reported from the second heat curve. Peak
crystallization temperature and onset crystallization temperature
are determined from the cooling curve.
[0045] Elastic Recovery. Resin pellets are compression molded
following ASTM D4703, Annex A1, Method C to a thickness of
approximately 5-10 mil. Microtensile test specimens of geometry as
detailed in ASTM D1708 are punched out from the molded sheet. The
test specimens are conditioned for 40 hours prior to testing in
accordance with Procedure A of Practice D618.
[0046] The samples are tested in a screw-driven or
hydraulically-driven tensile tester using flat, rubber faced grips.
The grip separation is set at 22 mm, equal to the gauge length of
the microtensile specimens. The sample is extended to a strain of
100% at a rate of 100%/min and held for 30 s. The crosshead is then
returned to the original grip separation at the same rate and held
for 60 s. The sample is then strained to 100% at the same 100%/min
strain rate.
[0047] Elastic recovery may be calculated as follows:
Elastic Recovery = ( Initial Applied Strain - Permanent Set )
Initial Applied Strain .times. 100 % ##EQU00001##
[0048] Energy restitution: A mass with a spring attached falls onto
the turf. The energy restitution is given by the comparison of
energy of the falling mass before and after impact on the test
specimen. Results are reported in percentage (%).
[0049] Indentation Load Deflection (ILD) is a measure of firmness
for a material. In general, the higher the ILD value, the more firm
the material; the lower the ILD value, the less firm the material.
ILD measurement is performed in the sample thickness direction. The
test protocol is in accordance with ASTM standard D 3574.
[0050] For ILD testing, a square bottom plate and a round top plate
are aligned with their centers coincident. The bottom plate is
13.times.13 in, and the top plate's diameter is 8 inches. Each test
specimen is 12 inches.times.12 inches.
[0051] The ILD test is performed on an Instron material testing
system in displacement-control mode. The bottom plate stays
stationary, and the top plate is actuated to move up or down as an
indenter. The indenter is lowered towards the bottom plate until
the load cell just starts to register some compression, which means
that there is physical contact between the two plates. The indenter
position is recorded as the origin d.sub.0. With the test specimen
sitting on the bottom plate, the indenter is lowered again until
the load cell registers about 4.5 N of compression force. The
indenter position is recorded as d. The specimen thickness is the
difference between the two readings (d-d.sub.0).
[0052] The test procedure consists of two steps: pre-flexing and
actual ILD measurements. In the pre-flexing step, the indenter is
driven into the specimen between 75% and 80% of the thickness for
two cycles (based on the initial thickness measurement obtained
with the protocol specified in paragraph above. The
loading/unloading rate is 250 mm/min. Then the specimen is left to
recover for 6 minutes before the second step starts. The objective
of pre-flexing is to eliminate structural hysteresis for an
accurate thickness measurement. In the second step, the specimen
thickness is measured again. The indenter is programmed to compress
the specimen with 25% of the thickness (based on the second time
thickness measurement). The indenter holds its position for 60
seconds to allow specimen relaxation until the force reading is
recorded as 25% ILD. The indenter continues to move downwards for
another 40% thickness to reach 65% of the specimen thickness. The
position is held for 60 seconds before the 65% ILD is recorded. The
loading/unloading rate is 50 mm/min.
[0053] Each specimen is tested three times. Between tests,
specimens rested for at least 40 minutes as a precaution to allow
specimen recovery. ILD results are reported in Newtons (N).
[0054] Melt flow rate (MFR) is measured in accordance with ASTM D
1238, Condition 280.degree. C./2.16 kg (g/10 minutes).
[0055] Melt index (MI) is measured in accordance with ASTM D 1238,
Condition 190.degree. C./2.16 kg (g/10 minutes).
[0056] Molecular weight distribution (Mw/Mn) is measured using Gel
Permeation Chromatography (GPC). In particular, conventional GPC
measurements are used to determine the weight-average (Mw) and
number-average (Mn) molecular weight of the polymer and to
determine the Mw/Mn. The gel permeation chromatographic system
consists of either a Polymer Laboratories Model PL-210 or a Polymer
Laboratories Model PL-220 instrument. The column and carousel
compartments are operated at 140.degree. C. Three Polymer
Laboratories 10-micron Mixed-B columns are used. The solvent is
1,2,4 trichlorobenzene. The samples are prepared at a concentration
of 0.1 grams of polymer in 50 milliliters of solvent containing 200
ppm of butylated hydroxytoluene (BHT). Samples are prepared by
agitating lightly for 2 hours at 160.degree. C. The injection
volume used is 100 microliters and the flow rate is 1.0
ml/minute.
[0057] Calibration of the GPC column set is performed with 21
narrow molecular weight distribution polystyrene standards with
molecular weights ranging from 580 to 8,400,000, arranged in 6
"cocktail" mixtures with at least a decade of separation between
individual molecular weights. The standards are purchased from
Polymer Laboratories (Shropshire, UK). The polystyrene standards
are prepared at 0.025 grams in 50 milliliters of solvent for
molecular weights equal to or greater than 1,000,000, and 0.05
grams in 50 milliliters of solvent for molecular weights less than
1,000,000. The polystyrene standards are dissolved at 80.degree. C.
with gentle agitation for 30 minutes. The narrow standards mixtures
are run first and in order of decreasing highest molecular weight
component to minimize degradation. The polystyrene standard peak
molecular weights are converted to polyethylene molecular weights
using the following equation (as described in Williams and Ward, J.
Polym. Sci., Polym. Let., 6, 621 (1968)):
M.sub.polypropylene=0.645(M.sub.polystyrene).
[0058] Polypropylene equivalent molecular weight calculations are
performed using Viscotek TriSEC software Version 3.0.
[0059] "Porosity" is the percent of open volume for the 3DRLM. The
mass and the dimensions of a 3DRLM sample are measured and the bulk
density is calculated. The percent of open volume for the 3DRLM
sample is the ratio of the volume of a 3DRLM sample to the volume
of a solid polymer of the same mass, using the polymer solid
density. Results for porosity are reported in percent (%).
[0060] Shock Absorption: A mass with a spring attached falls onto
the artificial turf system. The shock absorption is calculated by
comparing the maximum force on the turf with the reference for
impact on concrete. Results are reported in percentage (%).
[0061] Tensile Strength is measured using a hybrid of ASTM D638
(Rigid Plastics) and ASTM D882 (Films). The samples are sheets of
3DRLM shockpad SAC1 with dimensions 203 mm by 31.7 mm (8 inches
long and 1.25 inches wide). The gauge length between the test grips
is set at 127 mm (5 inches) and the pull speed used is 50
mm/min.
[0062] Vertical deformation: A mass with a spring attached falls
onto the turf. The vertical deformation is calculated by the
displacement of the falling mass into the test specimen after its
impact on it. Results are reported in millimeters (mm).
DETAILED DESCRIPTION
[0063] The present disclosure provides an artificial turf system.
In an embodiment, the artificial turf system includes a primary
backing layer with a plurality of artificial turf yarns projecting
upwardly from the primary backing layer. The artificial turf system
also includes a shock absorption component. The shock absorption
component is composed of a sheet of three-dimensional random loop
material (3DRLM). The 3DRLM sheet is in contact with the primary
backing layer. The shock absorption component includes (i) a
cushioning layer and (ii) a shockpad. The 3DRLM in the cushioning
layer has an apparent density that is greater than the apparent
density of the 3DRLM in the shockpad.
[0064] FIG. 1 shows an embodiment of the present artificial turf
system 10 having a primary backing layer 12, with an plurality of
artificial turf yarns 14 projecting upwardly therefrom. The term
"artificial turf," as used herein, is a carpet-like cover having
substantially upright, or upright, polymer strands of the
artificial turf yarn 14 projecting upwardly from a substrate which
is the primary backing layer 12. The artificial turf system 10 also
includes a shock absorption component 20. The shock absorption
component 20 contacts the bottom side of the primary backing layer
12. The shock absorption component 20 is composed of a
three-dimensional random loop material 30. The shock absorption
component 20 includes (i) a cushioning layer 40 and (ii) a shockpad
50. The shock absorption component 20 is an integral structure as
will be described below.
[0065] The "primary backing layer" is one or more sheets onto which
the artificial turf yarn is sewn or woven such that the artificial
turf yarn extends outwardly from the top side of the primary
backing layer. The primary backing layer may be a polymeric sheet
of woven fabric or a polymeric sheet of non-woven fabric. The
primary backing layer provides dimensional stability for the
artificial turf system.
[0066] Nonlimiting examples of suitable polymeric material for the
primary backing layer include styrene-butadiene rubber (SBR) and
propylene-based polymer. In an embodiment, the primary backing
layer is composed of an olefin-based polymer, such as a
propylene-based polymer. In a further embodiment, the primary
backing layer is composed of propylene homopolymer.
[0067] The present artificial turf system 10 includes a plurality
of artificial turf yarns 14 projecting upwardly from the primary
backing layer 12. The term "artificial turf yarn" or hereafter
"yarn," as used herein, includes fibrillated tape yarn, co-extruded
tape yarn, monotape yarn and monofilament yarn. A "fibrillated
tape" or "fibrillated tape yarn," is a cast extruded film cut into
tape (typically about 1 cm width), the film stretched and long
slits cut (fibrillated) into the tape giving the tape the
dimensions of grass blades. A "monofilament yarn" is extruded into
individual yarn or strands with a desired cross-sectional shape and
thickness followed by yarn orientation and relaxation in hot ovens.
The artificial turf yarn forms the polymer strands for the
artificial turf. Artificial turf requires resilience (springback),
toughness, flexibility, extensibility and durability. Consequently,
artificial turf yarn excludes yarn for fabrics (i.e., woven and/or
knit fabrics).
[0068] The yarn 14 is composed of a polymeric material. Nonlimiting
examples of suitable polymeric material for the yarn include
olefin-based polymer (such as propylene-based polymer and/or
ethylene-based polymer), polyester, nylon, and combinations
thereof. In an embodiment, the yarn 14 is composed of an
ethylene-based polymer.
[0069] The artificial turf system 10 includes the shock absorption
component 20. The shock absorption component 20 is composed of a
sheet 22 of three-dimensional random loop material 30. As shown in
FIG. 2, a "three-dimensional random loop material" (or "3DRLM") is
a mass or a structure of a multitude of loops 32 formed by allowing
continuous fibers 34, to wind, permitting respective loops to come
in contact with one another in a molten state and to be
heat-bonded, or otherwise melt-bonded, at most of the contact
points 36. Even when a great stress to cause significant
deformation is given, the 3DRLM 30 absorbs the stress with the
entire net structure composed of three-dimensional random loops
melt-integrated, by deforming itself; and once the stress is
lifted, elastic resilience of the polymer manifests itself to allow
recovery to the original shape of the structure. When a net
structure composed of continuous fibers made from a known
non-elastic polymer is used as a cushioning material, plastic
deformation is developed and the recovery cannot be achieved, thus
resulting in poor heat-resisting durability. When the fibers are
not melt-bonded at contact points, the shape cannot be retained and
the structure does not integrally change its shape, with the result
that a fatigue phenomenon occurs due to the concentration of
stress, thus unbeneficially degrading durability and deformation
resistance. In certain embodiments, melt-bonding is the state where
all contact points are melt-bonded.
[0070] A nonlimiting method for producing 3DRLM 30 includes the
steps of (a) heating a molten olefin-based polymer, at a
temperature 10.degree. C.-140.degree. C. higher than the melting
point of the polymer in a typical melt-extruder; (b) discharging
the molten interpolymer to the downward direction from a nozzle
with plural orifices to form loops by allowing the fibers to fall
naturally (due to gravity). The polymer may be used in combination
with a thermoplastic elastomer, thermoplastic non-elastic polymer
or a combination thereof. The distance between the nozzle surface
and take-off conveyors installed on a cooling unit for solidifying
the fibers, melt viscosity of the polymer, diameter of orifice and
the amount to be discharged are the elements which decide loop
diameter and fineness of the fibers. Loops are formed by holding
and allowing the delivered molten fibers to reside between a pair
of take-off conveyors (belts, or rollers) set on a cooling unit
(the distance therebetween being adjustable), bringing the loops
thus formed into contact with one another by adjusting the distance
between the orifices to this end such that the loops in contact are
heat-bonded, or otherwise melt-bonded, as they form a
three-dimensional random loop structure. Then, the continuous
fibers, wherein contact points have been heat-bonded as the loops
form a three-dimensional random loop structure, are continuously
taken into a cooling unit for solidification to give a net
structure. Thereafter, the structure is cut into a desired length
and shape. The method is characterized in that the olefin-based
polymer is melted and heated at a temperature 10.degree.
C.-140.degree. C. higher than the melting point of the interpolymer
and delivered to the downward direction in a molten state from a
nozzle having plural orifices. When the polymer is discharged at a
temperature less than 10.degree. C. higher than the melting point,
the fiber delivered becomes cool and less fluidic to result in
insufficient heat-bonding of the contact points of fibers.
[0071] Properties, such as, the loop diameter and fineness of the
fibers constituting the cushioning net structure provided herein
depend on the distance between the nozzle surface and the take-off
conveyor installed on a cooling unit for solidifying the
interpolymer, melt viscosity of the interpolymer, diameter of
orifice and the amount of the interpolymer to be delivered
therefrom. For example, a decreased amount of the interpolymer to
be delivered and a lower melt viscosity upon delivery result in
smaller fineness of the fibers and smaller average loop diameter of
the random loop. On the contrary, a shortened distance between the
nozzle surface and the take-off conveyor installed on the cooling
unit for solidifying the interpolymer results in a slightly greater
fineness of the fiber and a greater average loop diameter of the
random loop. These conditions in combination afford the desirable
fineness of the continuous fibers of from 100 denier to 100000
denier and an average diameter of the random loop of not more than
100 mm, or from 1 millimeter (mm), or 2 mm, or 10 mm to 25 mm, or
50 mm. By adjusting the distance to the aforementioned conveyor,
the thickness of the structure can be controlled while the
heat-bonded net structure is in a molten state and a structure
having a desirable thickness and flat surface formed by the
conveyors can be obtained. Too great a conveyor speed results in
failure to heat-bond the contact points, since cooling proceeds
before the heat-bonding. On the other hand, too slow a speed can
cause higher density resulting from excessively long dwelling of
the molten material. In some embodiments the distance to the
conveyor and the conveyor speed should be selected such that the
desired apparent density of 0.005-0.1 g/cc or 0.01-0.05 g/cc can be
achieved.
[0072] In an embodiment, the 3DRLM 30 has, one, some, or all of the
properties (i)-(iii) below: [0073] (i) a fiber diameter from 0.1
mm, or 0.5 mm, or 0.7 mm, or 1.0 mm or 1.5 mm to 2.0 mm to 2.5 mm,
or 3.0 mm; and/or [0074] (ii) a thickness (machine direction) from
0.5 cm, or 1.0 cm, 2.0 cm, or 3.0, cm, or 4.0 cm, or 5.0 cm, or 10
cm, or 20 cm, to 50 cm, or 75 cm, or 100 cm, or more. It is
understood that the thickness of the 3DRLM 30 will vary based on
target application for the artificial turf system.
[0075] The 3DRLM 30 is formed into a three dimensional geometric
shape to form a sheet (i.e., a prism). The 3DRLM 30 is an elastic
material which can be compressed and stretched and return to its
original geometric shape. An "elastic material," as used herein, is
a rubber-like material that can be compressed and/or stretched and
which expands/retracts very rapidly to approximately its original
shape/length when the force exerting the compression and/or the
stretching is released. The three dimensional random loop material
30 has a "neutral state" when no compressive force and no stretch
force is imparted upon the 3DRLM 30. The three dimensional random
loop material 30 has "a compressed state" when a compressive force
is imparted upon the 3DRLM 30. The three dimensional random loop
material 30 has "a stretched state" when a stretching force is
imparted upon the 3DRLM 30.
[0076] The three dimensional random loop material 30 is composed of
one or more olefin-based polymers. The olefin-based polymer can be
one or more ethylene-based polymers, one or more propylene-based
polymers, and blends thereof.
[0077] In an embodiment, the ethylene-based polymer is an
ethylene/.alpha.-olefin copolymer. Ethylene/.alpha.-olefin
copolymer may be a random ethylene/.alpha.-olefin polymer or an
ethylene/.alpha.-olefin multi-block polymer. The .alpha.-olefin is
a C.sub.3-C.sub.20 .alpha.-olefin, or a C.sub.4-C.sub.12
.alpha.-olefin, or a C.sub.4-C.sub.8 .alpha.-olefin. Nonlimiting
examples of suitable .alpha.-olefin comonomer include propylene,
butene, methyl-1-pentene, hexene, octene, decene, dodecene,
tetradecene, hexadecene, octadecene, cyclohexyl-1-propene (allyl
cyclohexane), vinyl cyclohexane, and combinations thereof.
[0078] In an embodiment, the ethylene-based polymer is a
homogeneously branched random ethylene/.alpha.-olefin
copolymer.
[0079] "Random copolymer" is a copolymer wherein the at least two
different monomers are arranged in a non-uniform order. The term
"random copolymer" specifically excludes block copolymers. The term
"homogeneous ethylene polymer" as used to describe ethylene
polymers is used in the conventional sense in accordance with the
original disclosure by Elston in U.S. Pat. No. 3,645,992, the
disclosure of which is incorporated herein by reference, to refer
to an ethylene polymer in which the comonomer is randomly
distributed within a given polymer molecule and wherein
substantially all of the polymer molecules have substantially the
same ethylene to comonomer molar ratio. As defined herein, both
substantially linear ethylene polymers and homogeneously branched
linear ethylene are homogeneous ethylene polymers.
[0080] The homogeneously branched random ethylene/.alpha.-olefin
copolymer may be a random homogeneously branched linear
ethylene/.alpha.-olefin copolymer or a random homogeneously
branched substantially linear ethylene/.alpha.-olefin copolymer.
The term "substantially linear ethylene/.alpha.-olefin copolymer"
means that the polymer backbone is substituted with from 0.01 long
chain branches/1000 carbons to 3 long chain branches/1000 carbons,
or from 0.01 long chain branches/1000 carbons to 1 long chain
branches/1000 carbons, or from 0.05 long chain branches/1000
carbons to 1 long chain branches/1000 carbons. In contrast, the
term "linear ethylene/.alpha.-olefin copolymer" means that the
polymer backbone has no long chain branching.
[0081] The homogeneously branched random ethylene/.alpha.-olefin
copolymers may have the same ethylene/.alpha.-olefin comonomer
ratio within all copolymer molecules. The homogeneity of the
copolymers may be described by the SCBDI (Short Chain Branch
Distribution Index) or CDBI (Composition Distribution Branch Index)
and is defined as the weight percent of the polymer molecules
having a comonomer content within 50 percent of the median total
molar comonomer content. The CDBI of a polymer is readily
calculated from data obtained from techniques known in the art,
such as, for example, temperature rising elution fractionation
(abbreviated herein as "TREF") as described in U.S. Pat. No.
4,798,081 (Hazlitt et al.), or in U.S. Pat. No. 5,089,321 (Chum et
al.) the disclosures of all of which are incorporated herein by
reference. The SCBDI or CDBI for the homogeneously branched random
ethylene/.alpha.-olefin copolymers is preferably greater than about
30 percent, or greater than about 50 percent.
[0082] The homogeneously branched random ethylene/.alpha.-olefin
copolymer may include at least one ethylene comonomer and at least
one C.sub.3-C.sub.20 .alpha.-olefin, or at least one
C.sub.4-C.sub.12 .alpha.-olefin comonomer. For example and not by
way of limitation, the C.sub.3-C.sub.20 .alpha.-olefins may include
but are not limited to propylene, isobutylene, 1-butene, 1-hexene,
4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, and 1-decene,
or, in some embodiments, 1-butene, 1-hexene, 4-methyl-1-pentene and
1-octene.
[0083] In an embodiment, the homogeneously branched random
ethylene/.alpha.-olefin copolymer consists of ethylene and a
C.sub.4-C.sub.8 .alpha.-olefin comonomer and has one, some, or all
of the following properties (i)-(iii) below: [0084] (i) a melt
index (I.sub.2) from 1 g/10 min, or 5 g/10 min, or 10 g/10 min, or
20 g/10 min to 30 g/10 min, or 40 g/10 min, or 50 g/10 min, and/or
[0085] (ii) a density from 0.75 g/cc, or 0.880 g/cc, or 0.890 g/cc
to 0.90 g/cc, or 0.91 g/cc, or 0.920 g/cc, or 0.925 g/cc; and/or
[0086] (iii) a molecular weight distribution (Mw/Mn) from 2.0, or
2.5, or 3.0 to 3.5, or 4.0.
[0087] In an embodiment, the ethylene-based polymer is a
heterogeneously branched random ethylene/.alpha.-olefin
copolymer.
[0088] The heterogeneously branched random ethylene/.alpha.-olefin
copolymer differs from the homogeneously branched random
ethylene/.alpha.-olefin copolymer primarily in the branching
distribution. For example, heterogeneously branched random
ethylene/.alpha.-olefin copolymers have a distribution of
branching, including a highly branched portion (similar to a very
low density polyethylene), a medium branched portion (similar to a
medium branched polyethylene) and an essentially linear portion
(similar to linear homopolymer polyethylene).
[0089] Like the homogeneously branched random
ethylene/.alpha.-olefin copolymer, the heterogeneously branched
random ethylene/.alpha.-olefin copolymer may include at least one
ethylene comonomer and at least one C.sub.3-C.sub.20 .alpha.-olefin
comonomer, or at least one C.sub.4-C.sub.12 .alpha.-olefin
comonomer. For example and not by way of limitation, the
C.sub.3-C.sub.20 .alpha.-olefins may include but are not limited
to, propylene, isobutylene, 1-butene, 1-hexene, 4-methyl-1-pentene,
1-heptene, 1-octene, 1-nonene, and 1-decene, or, in some
embodiments, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene.
In one embodiment, the heterogeneously branched
ethylene/.alpha.-olefin copolymer may comprise greater than about
50% by wt ethylene copolymer, or greater than about 60% by wt., or
greater than about 70% by wt. Similarly, the heterogeneously
branched ethylene/.alpha.-olefin copolymer may comprise less than
about 50% by wt .alpha.-olefin monomer, or less than about 40% by
wt., or less than about 30% by wt.
[0090] In an embodiment, the heterogeneously branched random
ethylene/.alpha.-olefin copolymer consists of ethylene and a
C.sub.4-C.sub.8 .alpha.-olefin comonomer and has one, some, or all
of the following properties (i)-(iii) below: [0091] (i) a density
from 0.900 g/cc, or 0.0910 g/cc, or 0.920 g/cc to 0.930 g/cc, or
0.094 g/cc; [0092] (ii) a melt index (I.sub.2) from 1 g/10 min, or
5 g/10 min, or 10 g/10 min, or 20 g/10 min to 30 g/10 min, or 40
g/10 min, or 50 g/10 min; and/or [0093] (iii) an Mw/Mn from 3.0, or
3.5 to 4.0, or 4.5.
[0094] In an embodiment, the 3DRLM 30 is composed of a blend of a
homogeneously branched random ethylene/.alpha.-olefin copolymer and
a heterogeneously branched ethylene/.alpha.-olefin copolymer, the
blend having one, some, or all of the properties (i)-(v) below:
[0095] (i) a Mw/Mn from 2.5, or 3.0 to 3.5, or 4.0, or 4.5; [0096]
(ii) a melt index (I.sub.2) from 3.0 g/10 min, or 4.0 g/10 min, or
5.0 g/10 min, or 10 g/10 min to 15 g/10 min, or 20 g/10 min, or 25
g/10 min; [0097] (iii) a density from 0.895 g/cc, or 0.900 g/cc, or
0.910 g/cc, or 0.915 g/cc to 0.920 g/cc, or 0.925 g/cc; and or
[0098] (iv) an I.sub.10/I.sub.2 ratio from 5 g/10 min, or 7 g/10
min to 10 g/10 min, or 15 g/10 min; and/or [0099] (v) a percent
crystallinity from 25%, or 30%, or 35%, or 40% to 45%, or 50%, or
55%.
[0100] According to Crystallization Elution Fractionation (CEF),
the ethylene/.alpha.-olefin copolymer blend may have a weight
fraction in a temperature zone from 90.degree. C. to 115.degree. C.
or about 5% to about 15% by wt., or about 6% to about 12%, or about
8% to about 12%, or greater than about 8%, or greater than about
9%. Additionally, as detailed below, the copolymer blend may have a
Comonomer Distribution Constant (CDC) of at least about 100, or at
least about 110.
[0101] The present ethylene/.alpha.-olefin copolymer blend may have
at least two, or three melting peaks when measured using
Differential Scanning calorimetry (DSC) below a temperature of
130.degree. C. In one or more embodiments, the
ethylene/.alpha.-olefin copolymer blend may include a highest
temperature melting peak of at least 115.degree. C., or at least
120.degree. C., or from about 120.degree. C. to about 125.degree.
C., or from about from 122 to about 124.degree. C. Without being
bound by theory, the heterogeneously branched
ethylene/.alpha.-olefin copolymer is characterized by two melting
peaks, and the homogeneously branched ethylene/.alpha.-olefin
copolymer is characterized by one melting peak, thus making up the
three melting peaks.
[0102] Additionally, the ethylene/.alpha.-olefin copolymer blend
may comprise from about 10 to about 90% by weight, or about 30 to
about 70% by weight, or about 40 to about 60% by weight of the
homogeneously branched ethylene/.alpha.-olefin copolymer.
Similarly, the ethylene/.alpha.-olefin copolymer blend may comprise
from about 10 to about 90% by weight, about 30 to about 70% by
weight, or about 40 to about 60% by weight of the heterogeneously
branched ethylene/.alpha.-olefin copolymer. In a specific
embodiment, the ethylene/.alpha.-olefin copolymer blend may
comprise from about 50% to about 60% by weight of the homogeneously
branched ethylene/.alpha.-olefin copolymer, and 40% to about 50% of
the heterogeneously branched ethylene/.alpha.-olefin copolymer.
[0103] Moreover, the strength of the ethylene/.alpha.-olefin
copolymer blend may be characterized by one or more of the
following metrics. One such metric is elastic recovery. Here, the
ethylene/.alpha.-olefin copolymer blend has an elastic recovery,
Re, in percent at 100 percent strain at 1 cycle of between 50-80%.
Additional details regarding elastic recovery are provided in U.S.
Pat. No. 7,803,728, which is incorporated by reference herein in
its entirety.
[0104] The ethylene/.alpha.-olefin copolymer blend may also be
characterized by its storage modulus. In some embodiments, the
ethylene/.alpha.-olefin copolymer blend may have a ratio of storage
modulus at 25.degree. C., G' (25.degree. C.) to storage modulus at
100.degree. C., G' (100.degree. C.) of about 20 to about 60, or
from about 20 to about 50, or about 30 to about 50, or about 30 to
about 40.
[0105] Moreover, the ethylene/.alpha.-olefin copolymer blend may
also be characterized by a bending stiffness of at least about 1.15
Nmm at 6 s, or at least about 1.20 Nmm at 6 s, or at least about
1.25 Nmm at 6 s, or at least about 1.35 Nmm at 6 s. Without being
bound by theory, it is believed that these stiffness values
demonstrate how the ethylene/.alpha.-olefin copolymer blend will
provide cushioning support when incorporated into 3DRLM fibers
bonded to form a cushioning net structure.
[0106] In an embodiment, the ethylene-based polymer is an
ethylene/.alpha.-olefin interpolymer composition having one, some,
or all of the following properties (i)-(v) below: [0107] (i) a
highest DSC temperature melting peak from 90.0.degree. C. to
115.0.degree. C.; and/or [0108] (ii) a zero shear viscosity ratio
(ZSVR) from 1.40 to 2.10; and/or [0109] (iii) a density in the
range of from 0.860 to 0.925 g/cc; and/or [0110] (iv) a melt index
(I.sub.2) from 1 g/10 min to 25 g/10 min; and/or [0111] (v) a
molecular weight distribution (Mw/Mn) in the range of from 2.0 to
4.5.
[0112] In an embodiment, the 3DRLM 30 is composed of an
ethylene/C.sub.4-C.sub.8 .alpha.-olefin copolymer that is an
elastomer. An "elastomer," as used herein, refers to a rubber-like
polymer that can be stretched to at least twice its original length
and which retracts very rapidly to approximately its original
length when the force exerting the stretching is released. An
elastomer has an elastic modulus of about 10,000 psi (68.95 MPa) or
less and an elongation usually greater than 200% in the
uncrosslinked state at room temperature using the method of ASTM
D638-72. In an embodiment, the 3DRLM 30 is composed of an
"ethylene-based elastomer" which is an elastomer composed of least
50 wt % units derived from ethylene.
[0113] In an embodiment, the 3DRLM 30 is composed of an
ethylene/C.sub.4-C.sub.8 .alpha.-olefin copolymer with a Comonomer
Distribution Constant (CDC) in the range of from greater than 45 to
less than 400, the ethylene/C.sub.4-C.sub.8 .alpha.-olefin
copolymer having less than 120 total unsaturation unit/1,000,000 C
(hereafter referred to as "CDC45-ethylene copolymer"). Nonlimiting
examples of suitable CDC45-ethylene copolymer are found in U.S.
Pat. Nos. 8,372,931 and 8,829,115, the entire content of each
incorporated by reference herein.
[0114] In an embodiment, the CDC45-ethylene copolymer has one,
some, or all of the following properties (i)-(iv) below: [0115] (i)
a density from 0.86 g/cc, or 0.87 g/cc to 0.88 g/cc, or 0.89 g/cc;
and/or [0116] (ii) a zero shear viscosity ratio (ZSVR) of at least
2; and/or [0117] (iii) less than 20 vinylidene unsaturation
unit/1,000,000 C; and/or [0118] (iv) a bimodal molecular weight
distribution.
[0119] FIG. 2 shows the shock absorption component 20 includes the
cushioning layer 40 and the shockpad 50. The cushioning layer 40
and the shockpad 50 each is composed of the 3DRLM 30.
[0120] As best seen in FIG. 1A and FIG. 2, the shock absorption
component 20 is a single integral structure whereby the
sub-components, cushioning layer 40 and shockpad 50, are
essentially inseparable, or are inseparable, and constitute a
single, unitary component--namely, the shock absorption component
20. The cushioning layer 40 and the shockpad 50 are formed
simultaneously, in a single extrusion process, such that many
(10's, or 100's, or 1000's) of 3DRLM fibers extend from the
cushioning layer 40 and into the shockpad 50 and vice versa. In
other words, the shock absorption component 20 is an integral
structure whereby no intervening layer, and/or no intervening
structure, and/or no intervening composition is present between the
cushioning layer 40 and the shockpad 50.
[0121] The 3DRLM 30 of the shock absorption component 20 is
composed of a plurality of multiple loops. The multiple loops are
formed by a plurality of continuous fibers composed of polymeric
material as previously disclosed. At least 2, or 3 or 4, or 5, or
6, or 7, or 8, or 9, or 10, or more continuous fibers 34 extend
from the shockpad 50 to the cushioning layer 40 and vice versa. In
an embodiment, hundreds, or thousands, of continuous fibers extend
across the cushioning layer 40 and into the shockpad 50 and vice
versa.
[0122] In an embodiment, the shock absorption component 20 includes
cushioning layer 40, shockpad 50, and a second cushioning layer
(not shown) integral with the shockpad 50. The 3DRLM in the second
cushioning layer has an apparent density that is greater than the
apparent density of the 3DRLM in the shockpad 50. The cushioning
layer 40 and the second cushioning layer sandwich the shockpad 50.
The second cushioning layer is located on the side opposite the
cushioning layer 40. In other words, the cushioning layer 40 and
the second cushioning layer are substantially parallel to, or
parallel to, each other. The second cushioning layer is similar to
the cushioning layer 40 in that that second cushioning layer is
composed of the same continuous fibers as the continuous fibers in
the shockpad 50 and/or is composed of the same continuous fibers in
the cushioning layer 40. The apparent density of the second
cushioning layer can be the same as, or different than, the
apparent density of the cushioning layer 40. The thickness of the
second cushioning layer can be the same as, or different than, the
thickness of the cushioning layer 40.
[0123] In an embodiment, the shockpad has a thickness, measured in
millimeters (mm) that is from 2 times, or 3 times, or 10 times, or
15 times to 50 times, or 100 times, or 200 times, or 300 times
greater than the thickness of the cushioning layer. In a further
embodiment, the shockpad has a thickness from 3 times, or 5 times,
or 8 times to 10 times, or 12 times, or 15 times greater than the
thickness of the cushioning layer.
[0124] The 3DRLM in the cushioning layer 40 has an apparent density
that is greater than the apparent density of the 3DRLM in the
shockpad 50. FIG. 1A and FIG. 2 show the continuous fibers 34 in
the cushioning layer 40 are more densely packed compared to the
loosely packed continuous fibers 34 in the shockpad 50. This
difference in fiber packing results in the cushioning layer 40
having an apparent density that is greater than the apparent
density of the shockpad 50.
[0125] In an embodiment, the apparent density of the cushioning
layer 40 is from 2 times, or 3 times, or 10 times, or 15 times to
50 times, or 100 times, or 200 times, or 300 times, or 400 times
greater than the apparent density of the shockpad 50. In a further
embodiment, the apparent density of the cushioning layer 40 is from
2 times, or 3 times, or 5 times or 8 times to 10 times, or 15
times, or 20 times greater than the apparent density of the
shockpad 50.
[0126] In an embodiment, the shockpad 50 has an apparent density
from 0.010 g/cc, or 0.016 g/cc, or 0.020 g/cc, or 0.050 g/cc, or
0.070 g/cc, or 0.100 g/cc, or 0.150 g/cc to 0.200 g/cc, or 0.250
g/cc, or 0.300 g/cc, or 0.330 g/cc, or 0.400 g/cc.
[0127] In an embodiment, the cushioning layer 40 has an apparent
density from 0.030 g/cc, or 0.032 g/cc, or 0.050 g/cc, or 0.070
g/cc, or 0.100 g/cc, or 0.159 g/cc to 0.200/cc, or 0.250 g/cc, or
0.300 g/cc, or 0.400, or 0.500 g/cc, or 0.600 g/cc, or 0.700 g/cc,
or 0.800 g/cc, or 0.900/cc, or 0.960 g/cc, or 1.000 g/cc.
[0128] In an embodiment, the shockpad 50 has an apparent density
from 0.010 g/cc, or 0.016 g/cc, or 0.020 g/cc, or 0.050 g/cc, or
0.070 g/cc, or 0.100 g/cc, or 0.150 g/cc to 0.200 g/cc, or 0.250
g/cc, or 0.300 g/cc, or 0.330 g/cc, or 0.400 g/cc and the
cushioning layer 40 has an apparent density from 0.030 g/cc, or
0.032 g/cc, or 0.050 g/cc, or 0.070 g/cc, or 0.100 g/cc, or 0.159
g/cc to 0.200/cc, or 0.250 g/cc, or 0.300 g/cc, or 0.400, or 0.500
g/cc, or 0.600 g/cc, or 0.700 g/cc, or 0.800 g/cc, or 0.900/cc, or
0.960 g/cc, or 1.000 g/cc with the proviso that the apparent
density of the 3DRLM in the cushioning layer 40 is greater that the
apparent density of the 3DRLM in the shock pad 50.
[0129] The shock absorption component 20 contacts the primary
backing layer 12. More specifically, the exposed surface of the
cushioning layer 40 contacts the bottom surface of the primary
backing layer 12. The contact between the cushion layer 40 and the
primary backing layer 12 may be by way of (i) direct contact or
(ii) indirect contact.
[0130] In an embodiment, the cushioning layer 40 directly contacts
the bottom surface of the primary backing layer 12. The term
"direct contact," as used herein, is the spatial relationship
whereby the cushioning layer 40 touches the bottom of the primary
backing layer 12 such that no intervening layer, and/or no
intervening structure, and/or no intervening composition is present
between the cushioning layer 40 and the primary backing layer
12.
[0131] In an embodiment, the cushioning layer 40 indirectly
contacts the bottom surface of the primary backing layer 12. The
term "indirect contact," as used herein, is the spatial
relationship whereby an intervening layer, and/or an intervening
structure, and/or an intervening composition is present between the
cushioning layer 40 and the primary backing layer 12. The
intervening layer/structure/composition may or may not be
coextensive with the exposed surface of the cushioning layer 40. In
a further embodiment, the cushioning layer 40 indirectly contacts
the bottom surface of the primary backing layer 12 whereby an
adhesive layer attaches, or otherwise bonds, the exposed surface of
the cushioning layer 40 to the bottom surface of the primary
backing layer 12.
[0132] In an embodiment, the artificial turf system 10 and/or the
shock absorption component 20 is void of foam.
[0133] In an embodiment, the shock absorption component 20 is void
of foam.
[0134] In an embodiment, the artificial turf system 10 is void of a
secondary backing layer.
[0135] In an embodiment, the artificial turf system 10 includes an
infill material 60. The infill is a particulate material and is
arranged between individual turf yarns. Infill material 60 performs
one, some, or all of the following: [0136] (1) keeps individual
turf yarns upright; and/or [0137] (2) protects the primary backing
layer from direct sunlight, thereby increasing the lifespan of the
primary backing layer; and/or [0138] (3) increases the ballast to
prevent matting, ensuring the individual yarns spring back after
heavy traffic.
[0139] Nonlimiting examples of suitable materials for the infill
material 60 include sand (silica), coated silica sand, SBR (styrene
butadiene rubber), recycled rubber from car tires, EPDM
(ethylene-propylene-diene monomer), other vulcanised rubbers or
rubber recycled from belts, thermoplastic elastomers (TPEs) and
thermoplastic vulcanizates (TPVs), crumb rubber, and any
combination thereof.
[0140] Nonlimiting examples of other suitable materials for the
infill material 60 include organic material such as natural cork,
ground fibers from the outside shell of the coconut, and any
combination thereof.
[0141] In an embodiment, the artificial turf system 10 includes a
drainage component 70. The drainage component allows water to be
removed from the artificial turf and prevents the artificial turf
yarns from becoming saturated with water. Nonlimiting examples of
suitable drainage components include stone-based drainage systems,
EXCELDRAIN Sheet 100, EXCELDRAIN Sheet 200, AND EXCELDRAIN EX-T
STRIP (available from American Wick Drain, Monroe, N.C.).
[0142] In an embodiment, the shock absorption component 20 has
dimensions of 305 mm.times.305 mm.times.54 mm (shockpad 48 mm,
cushioning layer 6 mm) (hereafter SAC1 as shown in Table 1). SAC1
has one, some, or all of the following properties (i)-(ix): [0143]
(i) a shockpad tensile strength from 10N, or 30 N, or 40 N to 80 N,
or 300 N, or 500 N; and/or [0144] (ii) a shock absorption component
tensile strength from 30 N, or 50 N, or 100 N to 250 N, or 600 N,
or 800N; and/or [0145] (iii) a shockpad ILD (25%) from 20 N, or 30
N, or 60 N to 130 N, or 400 N, or 500N; and/or [0146] (iv) a shock
absorption component ILD (25%) from 30 N, or 50 N, or 100 N to 250
N, or 600 N, or 800N; and/or [0147] (v) a shockpad ILD (65%) from
50 N, or 100 N, or 200 N to 300 N, or 400 N, or 600 N; and/or
[0148] (vi) a shock absorption component ILD (65%) from 75 N, or
150 N, or 250 N to 700 N, or 1000 N, or 1200 N; and/or [0149] (vii)
a shockpad porosity from 80%, or 90%, or 93% to 99.5%, or 97%, or
99%; and/or [0150] (viii) a cushioning layer porosity from 0%, or
greater than 0%, or 50%, or 70% to 80%, or 90%, or 95%; and/or
[0151] (ix) a shock absorption component porosity from 80%, or 85%,
or 90% to 95%, or 99%, or 99.5%
[0152] The present artificial turf system 10 advantageously
provides the following benefits.
[0153] (1) Improved drainage. The open loop structure of the
cushioning layer 40 and the shockpad 50 provides a high capacity
for drainage of rain water both vertically and horizontally due to
the open three-dimensional structure of the shock absorption
component 20 composed of 3DRLM 30.
[0154] (2) Infill reduction. The shock absorption component 20
increases the shock absorption and resiliency of the artificial
turf system 10, reducing the amount of infill material 60 needed.
The reduction of infill material usage enables lower maintenance
work, lower risk of injury due to inhomogeneous distribution of
granules, and lowers cost of the overall artificial turf
system.
[0155] (3) Improved recyclability. An all-polyolefin artificial
turf system is enabled by present artificial turf system 10 with
the inclusion of (i) the primary backing layer 12 that is a
propylene-based polymer, (ii) the shock absorption component 20
that is composed of an ethylene-based polymer, and (iii) an
elastomeric polymer infill material that is an ethylene-based
polymer. The "all-polyolefin" artificial turf system 10 can be
recycled in one single polymeric stream, rather than treating
separately the polyethylene yarn, the PU/SB latex secondary
backing, as is the case with incumbent artificial turfs--i.e.,
artificial turf with SBR/sand infill and a polyurethane shock
pad.
[0156] (4) Reduction in manufacturing cost. The integration of
shock pad 50 and cushioning layer 40 in one single integral shock
absorption component 20 eliminates the production step of applying
a secondary backing layer to the system, creating production
efficiency and lowering the overall cost of the present artificial
turf system 10.
[0157] By way of example, and not limitation, some embodiments of
the present disclosure will now be described in detail in the
following Examples.
Examples
1. Materials
[0158] A shock absorption component having a cushioning layer
integral with the shock pad is produced on a C-ENG line
(Duralastic, US). The formant shock absorption component has the
structure of the shock absorption component 20 shown in FIG. 2 with
cushioning layer 40 and shock pad 50. The 3DRLM of the formant
shock absorption component is continuous fibers composed of an
ethylene/octene .alpha.-olefin copolymer having a density of 0.905
g/cc.
[0159] Table 1 below provides the properties for the formant shock
absorption component (hereafter referred to as SAC1).
TABLE-US-00001 TABLE 1 SAC1 properties Nominal Dimensions = 305 mm
.times. 305 mm .times. 54 mm SAC1 Mass Thickness Volume Density
Porosity SAMPLE (g) (mm) (cc) (g/cc) (%) Shock 310.1 54 5016.8
0.0618 93.17% Absorption Component Shock 187.9 48 4459.3 0.0421
95.34% Pad Cushioning 122.2 6 557.4 0.2192 75.78% Layer Control
0.0626 93.08% 3DL Sample 0.905 0.00% Solid PE
2. Testing
[0160] The performance of SAC1 is compared to a control
(comparative sample, or CS). The control sample is the shockpad
shown in Table 1 above. In other words, the control sample is
composed of the same 3DRLM as SAC1, the difference being that the
control sample is the shockpad only; the control sample has
cushioning layer cut off and physically removed. SAC1 includes both
the shockpad and the cushioning layer.
[0161] The control sample and SAC1 sample, are prepared for ILD
testing and tensile strength testing. The sample for the shock
absorption component is 381 mm.times.381 mm.times.54 mm. From this
sample, a test sample is cut with dimensions 305 mm.times.305
mm.times.54 mm for compression testing. The compression test is
non-destructive. After the compression test for the shock
absorption component, specimens are prepared for tensile strength
testing. Four samples are cut from the 381 mm.times.381 mm.times.54
mm sample of the shock absorption component. The specimens used for
the tensile test are 203 mm long and 32.7 mm wide. The tensile test
is a destructive test. Two of these tensile specimens are measured
for the shock absorption component (cushioning layer integral to
shockpad). For the two other tensile specimens, the cushioning
layer is cut from the shockpad, and the shockpad alone (control) is
subjected to the tensile test.
[0162] The results are provided in Table 2 below.
TABLE-US-00002 TABLE 2 ILD and tensile test results ILD (N) ILD (N)
Tensile 25% compress 65% compress strength (N) Control CS* 87.6 228
66 SAC1 (inventive) 133 424 158 *shockpad only, cushioning layer
removed from shock absorption component
[0163] Applicant discovered that the 3DRLM shock absorption
component with integral cushioning layer and shockpad (i.e., SAC1)
unexpectedly exhibits improved shock absorption (ILD 65% 424 SAC1
vs 228 control) and improved tensile strength (158N SAC1 vs 66N
control) when compared to 3DRLM shockpad only.
[0164] It is specifically intended that the present disclosure not
be limited to the embodiments and illustrations contained herein,
but include modified forms of those embodiments including portions
of the embodiments and combinations of elements of different
embodiments as come within the scope of the following claims.
* * * * *