U.S. patent application number 11/986565 was filed with the patent office on 2008-09-04 for cushion tennis court surface.
Invention is credited to Michael Gasparovic.
Application Number | 20080213538 11/986565 |
Document ID | / |
Family ID | 39733269 |
Filed Date | 2008-09-04 |
United States Patent
Application |
20080213538 |
Kind Code |
A1 |
Gasparovic; Michael |
September 4, 2008 |
Cushion tennis court surface
Abstract
A padded surface for tennis courts (adhered over surface
foundation such as asphalt or concrete) that includes a soft
padding layer including granulated SBR rubber added to a
polyurethane elastomer, and a top wear layer with a sand
dispersion. The polyurethane elastomer is formed by mixing a first
component of polypropylene glycol, castor oil, silica, iron oxide
pigment, a molecular sieve, a UV stabilizer, and a catalyst, with a
second component formed of polypropylene glycol and methylene
diphenyl diisocyanate. The top wear layer comprises any one from
among a group consisting of a water-based urethane, acrylic, or
urethane-acrylic hybrid intermixed with sand in a dispersion. The
resulting tennis surface provides an optimum balance of physical
properties needed for the performance of the surface, despite a
wide range of temperatures, and the thickness can be varied as
desired to comply with ITF shock absorption rates of 13-20% and to
suit customer preferences.
Inventors: |
Gasparovic; Michael;
(Jacobus, PA) |
Correspondence
Address: |
Ober, Kaler, Grimes & Shriver;Attorneys at Law
120 East Baltimore Street
Baltimore
MD
21202-1643
US
|
Family ID: |
39733269 |
Appl. No.: |
11/986565 |
Filed: |
November 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60860313 |
Nov 21, 2006 |
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Current U.S.
Class: |
428/150 |
Current CPC
Class: |
E01C 13/065 20130101;
Y10T 428/2443 20150115 |
Class at
Publication: |
428/150 |
International
Class: |
E01C 13/06 20060101
E01C013/06 |
Claims
1. A padded surface for tennis courts, comprising: a surface
foundation; a soft poured-in-place polyurethane elastomer padding
layer applied over said surface foundation, said padding layer
including granulated SBR rubber added to a polyurethane elastomer,
said elastomer being formed by mixing a first component of
polypropylene glycol, castor oil, silica, iron oxide pigment, a
molecular sieve, a UV stabilizer, and a catalyst, with a second
component formed of polypropylene glycol and methylene diphenyl
diisocyanate; and a top wear layer applied over said padding layer,
said top wear layer comprising any one from among a group
consisting of a water-based urethane, acrylic, or urethane-acrylic
hybrid intermixed with sand in a dispersion.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] The present application derives priority from U.S.
provisional application Ser. No. 60/860,313 filed 21 Nov. 2006.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to synthetic sport surfaces
for tennis courts and, more specifically, to a two-layer padded
surface for tennis courts comprising a top wear layer applied over
a soft poured-in-place polyurethane elastomer (cushion) layer to
provide a combination of good wear-resistance and texture for
tennis.
[0004] 2. Description of the Background
[0005] A wide array of natural and artificial surfaces are
currently used in basketball and tennis courts, soccer and football
fields, and racing tracks. In each case it is necessary to finely
tune the surfacing to obtain particular surface characteristics
such as cushion or rebound, wear-resistance, or low construction
and maintenance costs.
[0006] Most conventional outdoor tennis courts are comprised of
asphalt pavement or concrete, but both materials are subject to the
development of cracks and degradation from weather, aging, and
normal wear and tear. Moreover, asphalt and concrete are unyielding
surfaces that frequently cause injuries.
[0007] There are also grass and synthetic grass tennis surfaces,
but in both cases the surfaces require significant maintenance and
fair poorly in cold climates.
[0008] Clay tennis surfaces use natural clay (i.e., naturally
occurring hydrated silicate materials). These are soft and easy to
play on, but expensive to install, difficult to maintain, and are
not useable at all in colder climates.
[0009] There are also a variety of Acrylic.TM. surfaces for both
indoor and outdoor tennis courts. For example, attempts have been
made to laminate foam with acrylic coatings. However, normal
seasonal, daily and hourly temperature changes cause undue tension
on seams and multiple wrinkles from contraction and expansion of
the foam. For example, TenniSphere, Inc. in Rome, Ga. sells a
surface comprising a polyethylene foam with an SBR (styrene
butadiene rubber) latex coating that is air dried in place, and
topped by multiple layers of a conventional acrylic latex mixture
(with or without sand and paint) to give the surface of the
material the feel and touch of a tennis court. This surface is also
subject to shrinkage when exposed to temperatures above about 50-60
degrees F. which results in cracks in the base around the outside
of the tennis court. Moreover, this and other Acrylic surfaces are
mainly used by large indoor and outdoor tennis installations and
clubs due to the high cost.
[0010] Polyurethanes are well known for their ability to maintain
physical properties over a wider range of temperatures. "Full pour"
polyurethane systems are known in the running world and there are
tracks that incorporate multiple layers of polyurethane coating and
rubber granules. Running tracks require shock absorption rates of
from 35-50%, and to achieve this in a "full pour" polyurethane
system the substrate must be foamed as it is poured (e.g., air is
incorporated in a polyurethane substrate either by chemical or
mechanical methods). One of the issues with an air entrapped system
is producing a uniform foam surface. Any irregularities in the
substrate surface are multiplied by the foam system, and this
causes surface irregularities. The foam system may also be
susceptible to adhesion problems to the substrate (typically
asphalt or concrete), because of the air entrapment. Conventional
polyurethane surfacing systems cannot compensate for irregularities
in the substrate surface, and such irregularities are unacceptable
in the tennis world. Moreover, the conventional surfaces cannot be
modified, adjusted or "tailored" to meet various performance
standards or customer needs.
[0011] The International Tennis Federation (ITF) prefers shock
absorption rates of 13-20%. It would be greatly advantageous to
provide a two-layer padded surface for tennis courts comprising a
urethane-based top wear layer applied over a soft poured-in-place
polyurethane elastomer (cushion) layer, the wear layer being
tunable for surface (friction) characteristics and the cushion
layer being adjustable to vary the shock absorption values within
the ITF range simply by adjusting the thickness.
SUMMARY OF THE INVENTION
[0012] It is therefore an object of the present invention to
provide a two-layer padded surface for tennis courts comprising a
urethane-based top wear layer applied over a soft poured-in-place
polyurethane elastomer (cushion) layer.
[0013] It is another object to provide a tennis court surface as
described above in which the wear layer is tunable for surface
(friction) characteristics and the padding layer is tunable in
thickness to vary the shock absorption values, thereby providing a
long term durable tennis surface that meets ITF performance
standards.
[0014] It is another object to provide an indoor/outdoor tennis
court surface that is soft enough to absorb the impact of a foot
strike, hard enough for competition, durable enough for prolonged
use, and weather-resistant with good drainage properties.
[0015] In accordance with the foregoing object, the present
invention is an improved padded surface for tennis courts that may
be overlayed a surface foundation such as asphalt or concrete. The
improved surface generally comprises a soft elastomer padding layer
applied over the surface foundation, the padding layer including
granulated SBR rubber added to a polyurethane elastomer. The
polyurethane elastomer is formed by mixing a first component of
polypropylene glycol, castor oil, silica, iron oxide pigment, a
molecular sieve, a UV stabilizer, and a catalyst, with a second
component formed of polypropylene glycol and methylene diphenyl
diisocyanate. The soft elastomer padding layer is applied by
squeegee and is set. Next, a top wear layer is applied over the
soft elastomer padding layer. The top wear layer comprises any one
from among a group consisting of a water-based urethane, acrylic,
or urethane-acrylic hybrid intermixed with sand in a dispersion.
The improved tennis surface provides an optimum balance of physical
properties needed for the performance of the surface, despite a
wide range of temperatures, and the thickness can be varied as
desired to comply with ITF shock absorption rates of 13-20% and to
suit customer preferences.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Other objects, features, and advantages of the present
invention will become more apparent from the following detailed
description of the preferred embodiment and certain modifications
thereof when taken together with the accompanying drawings in
which:
[0017] FIG. 1 is a front perspective view of a section of the
two-layer padded surface 1 for tennis courts comprising a top wear
layer 2 applied over a soft poured-in-place polyurethane elastomer
padding layer 4 according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] The present invention is a two-layer padded surface for
tennis courts comprising a urethane-based top wear layer applied
over a soft poured-in-place polyurethane elastomer padding layer,
the two-layer padded surface being applied over a concrete or
asphalt surface foundation.
[0019] FIG. 1 is a front perspective view of a section of the
two-layer padded surface 1 for tennis courts comprising a top wear
layer 2 applied over a soft poured-in-place polyurethane elastomer
base or cushion layer 4 according to the present invention.
[0020] The Base (Cushion) Layer 4 comprises a specially formulated
two-component polyurethane elastomer, mixed with finely ground SBR
rubber (from recycled tires). The Base (Cushion) Layer 4 preferably
formulated as a solid polyurethane elastomer that is relatively
soft (50-60 shore A).
[0021] The relative mix of polyurethane elastomer and SBR rubber is
as follows:
TABLE-US-00001 Preferred Acceptable Component Amt (Wt %) Range (Wt
%) Polyurethane elastomer 83.0% 65%-100% (two-component): SBR
rubber (recycled tires): 17.0% 0%-35%
[0022] The polyurethane elastomer comprises a specially formulated
two-component self-leveling polyurethane intermixed with the finely
ground SBR rubber granules.
An example of the two-component polyurethane elastomer used for the
Base Layer 4 follows:
Two Component Polyurethane:
TABLE-US-00002 [0023] Preferred Range Amt (Wt. %) (Wt %) (Part A)
Components Polypropylene glycol (polyether) 2000 MW: 40.8% 20-60%
Castor oil: 10.2% 5-20% 1,4-butane diol: 1.8% 0-5% Silica: 37.0%
30-50% Iron oxide pigments: 3.6% 1-6% Molecular Sieve: 4.0% 0-8% UV
stabilizer: 0.5% 0-2% Catalyst: 0.2% 0-1% (Part B) Components
Polypropylene glycol (polyether) 2000 MW: 35.0% 25-45% Methylene
Diphenyl Diisocyanate: 65.0% 50-80%
[0024] Above two-component polyurethane is mixed at an NCO index of
1.15. The optimum-range has been found to be (1.00-1.25). Thus, for
example, Part A may be mixed with Part B at an 8(A) to 1(B) volume
ratio, which gives and NCO/OH index of 1.20. The finely ground SBR
rubber is added to the two-component polyurethane and intermixed
with a commercial mixing.
[0025] The overall shock absorption of the polyurethane elastomer
can be adjusted by changing the thickness of the Base (Cushion)
Layer 4. This allows the manufacturer to offer a series of shock
absorbency to customers.
[0026] The top layer is comprised of a specially formulated
water-based urethane coating intermixed with sand. The coating may
also utilize an acrylic based or urethane-acrylic hybrid based
dispersion. The sand must be comprised of high-grade uniform
cylindrical sand although the mesh size used will be dependent on
the texture desired. Below is a suitable mix ratio for the wear
layer 2.
TABLE-US-00003 Component Preferred Amt Range Waterbased urethane or
acrylic coating: 1 gallon 1/2-2 gal Sand: 8 lbs. 4-11 lbs.
Example of Waterbased Urethane Coating:
[0027] The following is a suitable example of a Waterbased urethane
coating for the top wear layer 2:
TABLE-US-00004 Preferred Range (Part A) Components Amt (Wt. %) (Wt
%) Bayhydrol 110 (from Bayer Corporation) 91.2% 60-98% Titanium
Dioxide 1.4% 0-6% Iron Oxide Pigment 7.0% 2-12% Thixotrope Additive
0.5% 0-2%
[0028] Note that Bayhydrol 110 is a waterbased urethane dispersion.
Other commercially available products can be used in its place.
Bayhyrdrol 110 is based on an aliphatic polycarbonate dispersion.
Acrylic dispersions are also suitable for this application.
[0029] Method of Application
[0030] The polyurethane elastomer and SBR rubber for the base layer
4 mixed on site and applied with trowels to ensure that proper
thickness of 4-6 mm is achieved. The material is self-leveling in
nature and allows for ease of installation.
[0031] Depending on the substrate a primer may be required prior to
application of base layer 4 to the asphalt or concrete
substrate.
[0032] The finely ground SBR rubber is added to the two-component
polyurethane and intermixed with a commercial mixing machine
pursuant to the above-referenced weight ratios.
[0033] Next, the wear layer 2 is similarly mixed, and this mixture
is squeegee, raked, or spray applied to the cushion base layer
4.
[0034] Once the tennis surface 1 is fully set the result will be
will be a seamless court surface with no chances of separation of
seams which may be found in other conventional products. The use of
a polyurethane poured-in-place cushion layer 4 provides an optimum
balance of physical properties needed for the performance of the
surface, despite a wide range of temperatures, and the thickness
can be varied as desired to comply with ITF shock absorption rates
of 13-20% and to suit customer preferences. Moreover, the surface
characteristics can be varied by the mesh of sand in the wear layer
2 to make sure they are in line with the ITF recommendations.
[0035] Alternatives
[0036] For present purposes the above-described Base (Cushion)
Layer 4 provides an acceptable range of softness, despite being a
solid elastomer, since it is formulated on the softer side (50-60
shore A). If greater softness, or a greater range of softness is
desired, it is also possible to use a poured-in-place
micro-cellular polyurethane foam layer as the Base (Cushion) Layer
4. One skilled in should understand that additional layers such a
poured-in-place micro cellular foam layer as the Base (Cushion)
Layer 4 are within the scope and spirit of the present
invention.
[0037] Having now fully set forth the preferred embodiments and
certain modifications of the concept underlying the present
invention, various other embodiments as well as certain variations
and modifications thereto may obviously occur to those skilled in
the art upon becoming familiar with the underlying concept. It is
to be understood, therefore, that the invention may be practiced
otherwise than as specifically set forth herein.
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