Note: Descriptions are shown in the official language in which they were submitted.
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Title
GOLF BALL HAVING A POLYURETHANE COVER
Technical Field
The present invention relates to a cover for a golf ball. More specifically,
the
present invention relates to a golf ball cover layer composed of a
polyurethane
formed from a blend of diisocyanate prepolymers.
Background Art
Conventionally golf balls are made by molding a cover around a core. The
core may be wound or solid, and there may be an intermediate layer. Materials
previously used as golf ball covers include balata (natural or synthetic),
gutta-percha,
ionomeric resins (e.g., DuPont's SURLYN~), and polyurethanes. Balata is the
benchmark cover material with respect to sound (i.e. the sound made when the
ball
is hit by a golf club) and feel (i.e. the sensation imparted to the golfer
when hitting
the ball). Natural balata is derived from the Bully Gum tree, while synthetic
balata
is derived from a petroleum compound. Balata is expensive compared to other
cover
materials, and golf balls covered with balata tend to have poor durability
{i.e. poor
cut and shear resistance). Gutta percha is derived from the Malaysian
sapodilla tree.
A golf ball covered with gutta percha is considered to have a harsh sound and
feel
as compared to balata covered golf balls.
Ionomeric resins, as compared to balata, are typically less expensive and tend
to have good durability. However, golf balls having ionomeric resin covers
typically
have inferior sound and feel, especially as compared to balata covers.
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A golf ball with a polyuretbane cover generally has greater durability than a
golf ball with a balata cover. The polyurethane covered golf ball generally
has a
better sound and feel than a golf ball with an ionomeric resin cover.
Polyurethanes may be thermosetting or thermoplastic. Polyurethanes are
formed by reacting a prepolymer with a polyfunctional curing agent, such as a
polyamine or a polyol. The polyurethane prepolymer is the reaction product of,
for
example, a diisocyanate and a polyol such as a polyether or a polyester.
Several
patents describe the use of polyurethanes in golf balls. However, golf balls
with
polyurethane covers usually do not have the distance of other golf balls such
as those
with covers composed of SURLYN~ materials.
Gallagher, U.S. Patent Number 3,034,791 discloses a polyurethane golf ball
cover prepared from the reaction product of poly(tetramethylene ether) glycol
and
toluene-2,4-diisocyanates (T'DI), either pure TDI or an isomeric mixture.
Hewitt, et al., U.S. Patent Number 4,248,432 ("the '432 patent") discloses a
thermoplastic polyesterurethane golf ball cover formed from a reaction product
of a
polyester glycol (molecular weight of 800-1500) (aliphatic diol and an
aliphatic
dicarboxylic acid) with a para-phenylene diisocyanate ("PPDI") or cyclohexane
diisocyanate in the substantial absence of curing or crosslinking agents. The
'432
patent teaches against the use of chain extenders in making polyurethanes. The
'432
patent states, "when small amounts of butanediol-1,4 are mixed with a
polyester ...
the addition results in polyurethanes that do not have the desired balance of
properties to provide good golf ball covers. Similarly, the use of curing or
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crosslinking agents is not desired ...."
Holloway, U.S. Patent Number 4,349,657 ("the '657 patent's discloses a
method for preparing polyester urethanes with PPDI by reacting a polyester
(e.g.
prepared from aliphatic glycols having 2-8 carbons reacted with aliphatic
dicarboxylic acids having 4-10 carbons) with a molar excess of PPDI to obtain
an
isocyanate-terminated polyester urethane (in liquid form and stable at
reaction
temperatures), and then reacting the polyester urethane with additional
polyester.
The '657 patent claims that the benefit of this new process is the fact that a
continuous commercial process is possible without stability problems. The '657
patent further describes a suitable use for the resultant material to be golf
ball covers.
Hebert, et al., U.S. Patent Number 5,885,172 ("the '172 patent") discloses a
multilayer golf ball giving a "progressive performance" (i.e. different
performance
characteristics when struck with different clubs at different head speeds and
loft
angles) and having an outer cover layer formed of a thermosetting material
with a
thickness of less than 0.05 inches and an inner cover layer formed of a high
flexural
modulus material.
Although the prior art has disclosed golf ball covers composed of many
different materials, none of these golf balls have proven completely
satisfactory.
Dissatisfaction, for example, remains with processing and manufacturing the
balls,
and with the balls' durability and performance.
Specifically, with respect to processing, prior materials are not user
friendly
because certain starting materials may be unhealthful, such as diamines and
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isocyanides. In addition, prior balls using such materials are generally wound
balls.
Wound balls have tolerances that are more difficult to control due to core
sizes
and/or windings sizes, and therefore, require thicker cover layers to account
for the
manufacturing tolerances. With respect to durability problems, prior
polyurethane
covered balls, because they are wound balls, tend to lose compression and
initial
velocity due to the windings relaxing over time and use. With respect to
performance problems, prior balls, as a general rule, tend to have smaller
cores that
result in shorter flight distances. Although many golf balls having a
polyurethane
cover have been provided by the prior art, these golf balls have failed to
capture the
sound and feel of balata while providing a golf ball with the durability of an
ionomer.
Disclosure of the invention
The present invention provides a golf ball that demonstrates the best overall
durability and distance as yet put forth by the golf industry while adhering
to all of
the rules for golf balls as set forth by the USGA and The Royal & Ancient Golf
Club of Saint Andrews. The golf bail of the present invention is able to
accomplish
this by providing a cover composed of a p-phenylene diisocyanate based
polyurethane prepolymer or a blend of polyurethane prepolymers including p-
phenylene diisocyanate based polyurethane prepolymer with a toluene
diisocyanate
based polyurethane prepolymer.
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BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 illustrates a perspective view of a golf ball of the present invention
including a cut-away portion showing a core, a boundary layer, and a cover.
5 FIG. 2 illustrates a perspective view of a golf ball of the present
invention
including a cut-away portion core and a cover.
Best Models) For Carrying Out The Invention
As illustrated in FIG. 1, the golf ball of the present invention is generally
indicated as 10. The golf ball 10 includes a core 12, a boundary layer 14 and
a cover
16. Alternatively, as shown in FIG. 2, the golf ball 10 may only include a
core 12
and a cover 16.
The cover 16 is a polyurethane cover having a predetermined hardness and a
predetermined durability as measured on a cover strike plate drop test as
further
described below. The polyurethane cover 16 is composed of a polyurethane
material formed from a PPDI-based polyurethane prepolymer and preferably a
blend
of diisocyanate prepolymers. The blend of diisocyanate prepolymers includes at
least one TDI-based polyurethane prepolymer and at least one other
diisocyanate-
based polyurethane prepolymer. In a preferred embodiment, the blend of
diisocyanate prepolymers includes at least one PPDI-based polyurethane
prepolymer
and at least one TDI-based polyurethane prepolymer. Alternative embodiments
have
a blend which includes at least two different PPDI-based polyurethane
prepolymer
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and at least one TDI-based polyurethane prepolymer. Yet fiuther embodiments
may
include at least one TDI-based polyurethane prepolymer and at least one MDI-
based
polyurethane prepolymer. Those skilled in the pertinent art will recognize
that
multiple variations of diisocyanate prepolymers may be utilized without
departing
from the scope and spirit of the present invention.
The polyurethane cover 16 encompasses a boundary layer 14, as shown in
FIG. 1, or alternatively the cover 16 may encompass the core 12 as shown in
FIG. 2.
The boundary layer 14 is composed of a thermoplastic material that has a
predetermined hardness. The boundary layer 14 will encompass the core 12. Each
component of the golf ball 10 of the present invention will be described below
in
greater detail.
The most important feature of the present invention is the durability of the
cover. A golf ball 10 is subjected to tremendous forces when impacted with a
golf
club during a "golf shot." The golf ball 10 of the present is capable of
enduring,
more than polyurethane covered golf balls of the prior art, slices or other
incorrect
hits by golfers. The unique polyurethane formulation for the cover 16 of the
present
invention provides this enhanced durability. Durability as defined herein is
objectively measured through comparative testing of available golf balls
versus the
golf ball 10 of the present invention. The testing methods and results will be
described below.
The polyurethane utilized in the present invention is preferably composed of
blend of a TDI-based prepolymer, a second diisocyanate-based polyurethane
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prepolymer and a curing agent. The TDI-based prepolymer is preferably formed
from TDI and a polyether polyol. The second diisocyanate-based polyurethane
prepolymer is preferably a PPDI-based prepolymer formed from PPDI and a
polyester polyol, preferably a polycaprolactone. The prepolymer blend is cured
with
a curing agent. The curing agent, or curative, may be a diol (e.g., 1,4 butane
diol,
trimethylpropanol), a mixture of diols (e.g., 1,4 butane diol and ethylene
glycol, or
other suitable glycols), a hydroquinone, a mixture of hydroquinones, a triol,
a
mixture of triols, a diamine, a mixture of diamines, an oligomeric diamine, a
triamine, or a blend of some or all of these materials. Preferably, the curing
agent is
a blend of a diamine and a mixture of diols.
In an alternative embodiment, the blend of prepolymers includes three
diisocyanate-based polyurethane prepolymers. In this embodiment, the TDI-based
prepolymer is preferably formed from TDI and a polyether polyol. The second
diisocyanate-based polyurethane prepolymer is preferably a PPDI-based
prepolymer
formed from PPDI and a polyester polyol, preferably a polycaprolactone. The
third
diisocyanate-based polyurethane prepolymer is a PPDI-based prepolymer formed
from PPDI and a polyether polyol. Preferably, the curing agent is a blend of a
diamine and a mixture of diols. As mentioned above, alternative embodiments
may
have variations of the dual blend or the tri-blend, and may use a TDI-based
polyurethane prepolymer with other non-PPDI-based polyurethane prepolymers.
An alternative embodiment has only a PPDI-based polyurethane prepolymer
that provides a polyurethane with a higher rebound at a lower hardness,
greater
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durability and improved sound and feel. However, although the use of only a
PPDI-
based polyurethane prepolymer provides greater durability for a polyurethane
cover,
the polyurethane cover 16 of the present invention is preferably formed from a
blend
of prepolymers to provide even greater durability.
The blending of a TDI-based prepolymer with other diisocyanate-based
polyurethane prepolymers lowers the viscosity of the mixture, lowers the
temperature of the exothermic reaction that occurs when the prepolymers are
reacted
with the curing agent, and increases the durability. The TDI-based prepolymer
may
range from 10 to 40 percent of the polyurethane prepolymer blend. Preferably,
the
TDI-based prepolymer is 30 percent of the polyurethane prepolymer blend. A
preferred TDI based prepolymer is a TDI terminated polyether prepolymer
available
from Uniroyal Chemical Company of Middlebury, Connecticut.
The dual blend and tri-blend formulations will preferably contain a PPDI
terminated polyester prepolymer and/or a PPDI terminated polyether prepolymer.
A
preferred PPDI terminated polyester prepolymer is available from Uniroyal
Chemical. A preferred PPDI terminated polyether prepolymer is available from
Uniroyal Chemical.
The polyurethane prepolymer blend may have 10 to 40 parts of a TDI
terminated polyether prepolymer blended with 60 to 90 parts of a PPDI
terminated
polyether prepolymer. Alternatively, the polyurethane prepolymer blend may
have
10 to 40 parts of a TDI terminated polyether prepolymer blended with 60 to 90
parts
of a PPDI terminated polyester prepolymer. Further, the polyurethane
prepolymer
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blend may have 10 to 40 parts of a TDI terminated polyether prepolymer blended
with 5 to 90 parts of a PPDI terminated polyether prepolymer and 5 to 90 parts
of a
PPDI terminated polyester prepolymer. More specific blend formulations are set
forth in the Examples below. The PPDI-based polyurethane prepolymer may be
polyether or polyester terminated.
The cover 16 of the golf ball 10 of the present invention is most preferably
composed of a polyurethane formed from a polyurethane prepolymer blend
composed of a TDI-based polyurethane prepolymer and a PPDI-based polyurethane
prepolymer, and cured with a mixture of curing agents such as a diamine and a
blend
of 1,4 butane diol and glycols. A suitable diamine is toluene ethylene
diamine.
Other agents which may be utilized during the curing process include
dimethylthio-
2,4-toluenediamine; trimethyl glycol di-p-aminobenzoate; cyclohexane
dimethanol;
hydroquinone-bis-hydroxyethyl ether; phenyldiethanol amine mixture; methylene
dianiline sodium chloride complex; and/or prionene amine. This list of
preferred
agents (including chain extenders, cross-linkers and curing agents) is not
meant to be
exhaustive, as any suitable (preferably polyfunctional) chain extender, cross-
linker,
or curing agent may be used.
The curing agent mixture for the cover 16 of the present invention may have
numerous variations. In a preferred embodiment, the curing agent is composed
of 30
to 70 parts of a diol blend to 70 to 30 parts of a diamine. Alternatively, the
diamine
component may be a blend of different diamines.
The ratio of the polyurethane prepolymer blend to curing agent is determined
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by the nitrogen-carbon-oxygen group ("NCO' content of the polyurethane
prepolymer blend. For example, the NCO content of the TDI-terminated polyether
or TDI-terminated polyester is preferably in the range of 4.0% to 9.0%, while
the
NCO content of the PPDI-terminated polyether is preferably in the range of
5.0% to
5 8.0%. The NCO content of the PPDI-terminated polyester is preferably in the
range
of 2.0% to 6.0%. The NCO content of the polyurethane prepolymer blend ranges
from 2% to 8% of the polyurethane prepolymer blend. The amount of curing agent
should correspond to 90% to 110% of the mol equivalence of the NCO content of
the polyurethane prepolymer blend. The weight ratio of the polyurethane
10 prepolymer blend to the curing agent is preferably in the range of about
10:1 to
about 30:1.
Prior to curing, the polyurethane prepolymer blend and curing agent are
preferably stored separately. The polyurethane is formed by first heating and
mixing
the polyurethane prepolymer blend with the curing agent in a mold, and then
curing
the mixture by applying heat and pressure for a predetermined time period.
Additionally, a catalyst (e.g. dibutyl tin dilaurate, a tertiary amine, etc.)
may be
added to the mixture to expedite the casting process.
The polyurethane prepolymer blend material is preferably degassed and
warmed in a first holding container prior to processing of the cover 16. The
processing temperature for the polyurethane prepolymer blend is preferably in
the
range of about 100-220°F, and most preferably in the range of about 120-
200°F.
The polyurethane prepolymer blend is preferably flowable from the first
holding
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container to a mixing chamber in a range of about 200-1100 grams of material
per
minute, or as needed for processing. In addition, the polyurethane prepolymer
blend
material may be agitated in the first holding container, in the range of 0-250
rpm, to
maintain a more even distribution of material and to eliminate
crystallization.
The curing agent is preferably degassed and warmed in a second holding
container prior to processing of the cover 16. The processing temperature for
the
curative is preferably in the range of about 50-230°F, and most
preferably in the
range of about 80-200°F. The curing agent is preferably flowable from
the second
holding container to the mixing chamber in the range of about 15-75 grams of
material per minute, or as needed. If a catalyst is used for processing the
cover 16,
then the catalyst is added to the curing agent in the second holding container
to form
a curative mixture. Suitable catalyst are described above. The curing agent
and
catalyst are agitated, in the range of about 0 to 250 rpm, to maintain an even
distribution of catalyst in the curative mixture in the second holding
container. It is
preferred that the catalyst is added in an amount in the range of about 0.25-
5% by
weight of the combined polyurethane prepolymer blend and curing agent.
Additives
may be added to the curative mixture as desired.
The polyurethane prepolymer blend and curative mixture are preferably added
to the common mixing chamber at a temperature in the range of about 160-
220°F. A
colorant material, such as, for example, titanium dioxide, barium sulfate,
and/or zinc
oxide in a glycol or castor oil carrier, and/or other additive materials) as
are well
known in the art, may be added to the common mixing chamber. The amount of
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colorant material added is preferably in the range of about 0-10% by weight of
the
combined polyurethane prepolymer blend and curative materials, and more
preferably in the range of about 2-8%. The entire mixture is preferably
agitated in
the mixing chamber in the range of about 1 to 250 rpm prior to molding.
Although the golf ball cover 16 of the present invention is preferably
manufactured in a casting process, the cover material may alternatively be
provided
as a thermoplastic polyurethane for injection molding of the cover 16 over the
boundary layer 14 and/or core 12. For a thermoplastic polyurethane, the PPDI-
based
prepolymer is formed by reacting a polyol with PPDI. The PPDI-based prepolymer
is then reacted with a chain extender, such as, for example, a diol or mixture
of diols,
a triol or mixture of triols, a diamine or mixture of diamines, etc. The
resulting
product is modified using conventional procedures to form a desired
thermoplastic
material for injection molding of the cover 16 over the boundary layer 16
and/or
core 12.
The PPDI-based polyurethane cover 16 of the present invention exhibits good
tensile strength, tear properties, and flexural modulus at lower hardnesses.
In
addition, because the preferred material is PPDI-based, the cover 16 has a tan
8
value lower than conventional (e.g. MDI- and TDI-based) thermoplastics and
thermosetting urethanes. Thus, the PPDI-based polyurethane cover 16 of the
present
invention loses less energy as heat upon a high distortion or impact event
(i.e.
hysteresis) compared to these other polyurethane materials. It is believed
that the
relative superior mechanical and physical properties of the PPDI-based
polyurethane
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cover 16 of the present invention is due to both the rigid rod-like structure
of PPDI
and the distribution of that structure throughout the poly~ethane.
The core 12 of the golf ball 10 is the "engine" for the golf ball 10 such that
the inherent properties of the core 12 will strongly determine the initial
velocity and
distance of the golf ball 10. A higher initial velocity will usually result in
a greater
overall distance for a golf ball. In this regard, the Rules of Golf, approved
by the
United States Golf Association ("USGA") and The Royal and Ancient Golf Club of
Saint Andrews, limits the initial velocity of a golf ball to 250 feet (76.2m)
per
second (a two percent maximum tolerance allows for an initial velocity of 255
per
second) and the overall distance to 280 yards (256m) plus a six percent
tolerance for
a total distance of 296.8 yards (the six percent tolerance may be lowered to
four
percent). A complete description of the Rules of Golf are available on the
USGA
web page at www.usga.org. Thus, the initial velocity and overall distance of a
golf
ball must not exceed these limits in order to conform to the Rules of Golf.
Therefore, the core I2 for a USGA approved golf ball is constructed to enable
the
golf ball 10 to meet, yet not exceed, these limits.
The core 12 of the golf ball 10 is generally composed of a blend of a base
rubber, a cross-linking agent, a free radical initiator, and one or more
fillers or
processing aids. A preferred base rubber is a polybutadiene having a cis-1,4
content
above 90%, and more preferably 98% or above.
The use of cross-linking agents in a golf ball core is well known, and metal
acrylate salts are examples of such cross-linking agents. Free radical
initiators are
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used to promote cross-linking of the base rubber and the cross-linking agent.
Suitable fi~ee radical initiators for use in the golf ball core I2 of the
present invention
include peroxides such as dicumyl peroxide, bis-(t-butyl peroxy) diisopropyl
benzene, t-butyl perbenzoate, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-5-
5 butylperoxy-hexane, 1,1-di (t-butylperoxy) 3,3,5-trimethyl cyclohexane, and
the
like, all of which are readily commercially available.
Zinc oxide is also preferably included in the core formulation. Zinc oxide
may primarily be used as a weight adjusting filler, and is also believed to
participate
in the cross-linking of the other components of the core (e.g. as a coagent).
Additional processing aids such as dispersants and activators may optionally
be
included. In particular, zinc stearate may be added as a processing aid (e.g.
as an
activator). Any of a number of specific gravity adjusting fillers may be
included to
obtain a preferred total weight of the core 12. Examples of such fillers
include
tungsten and barium sulfate. All such processing aids and fillers are readily
commercially available
In the present invention, the core components are mixed and compression
molded in a conventional manner known to those skilled in the art. In a
preferred
' form, the finished core I2 has a diameter of about I .35 to about 1.64
inches for a
golf ball 10 having an outer diameter of 1.68 inches. The core weight is
preferably
maintained in the range of about 32 to about 40 g. The core PGA compression is
preferably maintained in the range of about 50 to 90, and most preferably
about 55
to 80.
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As used herein, the term "PGA compression" is defined as follows:
PGA compression value =180 - Riehle compression value
The Riehle compression value is the amount of deformation of a golf ball in
inches
under a static load of 200 pounds, multiplied by 1000. Accordingly, for a
5 deformation of 0.095 inches under a load of 200 pounds, the Riehle
compression
value is 95 and the PGA compression value is 85.
As is described above, the present invention preferably includes at least one
boundary layer 14 that preferably is composed of a thermoplastic (e.g.
thermoplastic
or thermoplastic elastomer) or a blend of thermoplastics (e.g. metal
containing, non-
10 metal containing or both). However, the golf ball 10 may have several
boundary
layers 14 disposed between the core 12 and the cover 16. Most preferably the
boundary layer 14 is composed of at least one thermoplastic that contains
organic
chain molecules and metal ions. The metal ion may be, for example, sodium,
zinc,
magnesium, lithium, potassium, cesium, or any polar metal ion that serves as a
15 reversible cross-linking site and results in high levels of resilience and
impact
resistance. Suitable commercially available thermoplastics are ionomers based
on
ethylene copolymers and containing carboxylic acid groups with metal ions such
as
described above. The acid levels in such suitable ionomers may be neutralized
to
control resiliency, impact resistance and other like properties. In addition,
other
fillers with ionomer carriers may be used to modify (e.g. preferably increase)
the
specific gravity of the thermoplastic blend to control the moment of inertia
and other
like properties. Exemplary commercially available thermoplastic materials
suitable
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for use in a boundary layer 14 of a golf ball 10 of the present invention
include, for
example, the following materials and/or blends of the following materials:
HYTREL~ and/or HYLENE~ products from DuPont, Wilmington, Delaware,
PEBAX~ products from Elf Atochem, Philadelphia, Pennsylvania, SURLYN~
products from DuPont, and/or ESCOR~ or IOTEK~ products from Exxon
Chemical, Houston, Texas.
The Shore D hardness of the boundary layer 14 should be about 65 or less. It
is preferred that the boundary layer 14 have a hardness of between about 50-65
Shore D. In a preferred embodiment, the boundary layer 14 has a Shore D
hardness
in the range of about 57-65. One reason for preferring a boundary layer 14
with a
Shore D hardness of 65 or lower is to improve the feel of the resultant golf
ball.
Examples
Twelve golf balls of the present invention were compared to a Maxfli
REVOLUTION, a Titlelist PROFESSIONAL, a Titlelist DT-2, and a Bridgestone
PRECEPT. All of the golf balls were subjected to a durability test to
determine the
durability of the golf balls in an objective manner. The durability tests were
conducted on a cover shear apparatus as known in the golf industry. The
apparatus
includes a ten pound metal block with a strike plate on its bottom, mounted on
a
frame. A golf ball is placed within a holder and held by a set of pins. The
strike
plate is angled at 54 degrees from vertical. The strike plate is dropped from
six
inches above the golf ball.
The golf balls are measured on a cover shear criteria. The scale for each is
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from 1 to 5, with 1 being poor, 2 being below average, 3 being average, 4
being
above average and 5 being excellent. The cover shear criteria is as follows: 1-
portion
of the cover has been completely sheared off and dimples have been greatly
reduced
or removed; 2-the cover material has been sheared to the extent that the flaps
of the
cover are visible, and severe bunching or peeling back of the cover material
is
evident; 3-there is moderate cutting of the cover material to the extent that
internal
portions of the cover are exposed, but the cover is intact; 4-indentations in
the cover
are evident, but there is no bunching of the cover material ; 5-groove marks
are
difficult to see and slight score marks may or may not be visible, and there
is no
deformation of the cover material.
Table One sets forth data for each of the twelve overall golf balls 10 and
each
of the cores 12. The weight of each of the golf balls 10 varies from 45.65
grams to
45.92 grams. The PGA compression of each of the golf balls 10 vanes from 92 to
101. The average diameter of each of the golf balls 10 is consistently 1.684
inches.
The core diameter of each of the cores 12 is 1.489 inches or 1.515 inches. The
PGA compression of each of the cores 12 varies between 60 and 75 points.
The twelve example golf balls of the present invention each had a boundary
layer 14 composed of an ionomer blend with a thickness varying from 0.0525 and
0.058 inches, and a Shore D hardness varying between 58 and 62. Additionally,
golf
balls 10, each having a cover 16 composed of a single PPDI-based polyurethane
prepolymer were produced and subjected to the durability test to measure cover
shear. These single PPDI-based polyurethane prepolymer cover materials ranged
in
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thickness from 0.0265 inch to 0.038 inch, had a tensile strength range of 6500
to
7900 pounds per square inch, a specific gravity of 1.142 to 1.220, a Bayshore
Rebound range of 5-65 percent, a Shore D hardness of 47 to 53 and a flexural
modulus greater than 10,000 psi. The shear rating for each of these golf balls
was
3Ø
TABLE ONE
Ball Ball Ball Average Core Core
Weight Compression Diameter Diameter
Compression
(grams) (points) (inches) {inches) (points)
1 45.65 92 1.684 1.489 60
2 45.86 98 1.684 1.515 70
3 45.92 I01 1.684 1.515 75
4 45.82 94 1.684 1.489 60
5 45.83 99 1.684 1.489 65
6 45.90 99 1.684 1.489 65
7 45.86 96 1.684 1.515 70
8 45.84 100 1.684 1.515 75
9 45.84 101 1.684 1.515 75
10 45.89 98 1.684 1.515 65
11 45.83 95 1.682 1.515 65
12 45.84 97 1.681 1.515 69
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--
TABLE
TWO
Ball Polyurethane Thicla~essShore
prepolymer D
Ex. TDI PPDI-1 PPDI-2 PPDI-3 PPDI-4 ~"'cb~I Hardness
No.
1 30 70 0.0375 47
2 30 20 SO 0.0300 53
3 30 70 0.0300 47
4 30 70 0.0375 47
30 50 20 0.0375 47
6 30 70 0.0375 47
7 30 50 20 - 0.0300 47
8 30 20 50 0.0300 53
9 30 70 0.0300 53
20 80 0.0300 47
11 30 70 0.0300 47
12 30 70 0.0300 47
Table Two sets forth the properties of each of the cover layers 16 for each of
the twelve golf balls 10. The number of parts of each polyurethane prepolymer
for
each of the cover layers 16 is provided in columns 2 through 6. Column 2
includes
5 the number of parts of the TDI-terminated polyether prepolymer. Column 3
includes the number of parts of the first PPDI terminated polyether
prepolymer.
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Column 4 includes the number of parts of the first PPDI terminated polyester
(polycaprolactone) prepolymer. Column 5 includes the number of parts of the
second PPDI terminated polyether prepolymer. The difference between the first
and
second PPDI terminated polyether prepolymers is the NCO content and the
5 molecular weight of the polyol (ether) backbone, with the first having a NCO
content in the range of approximately 5.45% to approximately 5.75%, and the
second having a NCO content in the range of approximately 5.6% to
approximately
6.2%. Column 6 includes the number of parts of the second PPDI terminated
polyester (polycaprolactone) prepolymer. The difference between the first and
10 second PPDI terminated polyester (polycaprolactone) prepolymers is the NCO
content, with the first having a NCO content in the range of approximately
3.55% to
approximately 3.85%, and the second having a NCO content in the range of
approximately 4.45% to approximately 5.05%. Each of the polyurethane
prepolymer blends for examples 1-9 and 11-12 were cured with a blend of curing
15 agents. The blend of curing agents was composed of 50 parts of a diamine
curing
agent and 50 parts of a blend of a 1,4 butane diol and glycol. Example 10 of
the golf
balls 10 of the present invention was cured with a blend of 70 parts of a
diamine and
parts of a 1,4 butane diol and glycol. The thickness of the cover layer 16 for
each of the twelve golf balls 10 of present invention is either 0.0300 inches
or
20 0.0375 inches. The shore D hardness of the cover layer 16 for each of the
twelve
golf balls 10 of present invention is either 47 degrees or 53 degrees.
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TABLE THREE
Ball Shear 1 I O mph Driver 90 mph Driver 79 mph
5-Iron
(1-5) Carry Total Carry Total C
(Yds) (Y~) (Y~) {Y~) (Y~)
Revolution 5 251.5 269.6 194.5 218.6 158.1
Precept 4 253.1 270.6 196.2 220.4 162.7
EV
Professional4 248.2 266.1 190.3 216.0 158.4
DT 2-piece 1 256.1 274.7 197.1 222.8 164.8
1 4.25 253.9 271.1 195.7 220.6 161.2
2 4.0 255.5 274.1 196.7 222.4 163.2
3 4.0 257.3 272.2 199.2 221.8 162.0
4 4.0 253.9 269.7 197.0 220.4 160.4
5 4.0 254.3 274.1 198.2 220.4 159.1
6 4.25 254.4 269.4 197.4 220.6 160.1
7 4.25 255.9 271.4 198.3 221.9 161.6
8 3.75 257.2 273.2 198.2 222.7 163.6
9 3.75 256.8 273.6 197.2 222.7 163.8
10 3.75 256.7 275.5 197.5 222.6 161.3
11 4.5 255.5 273.3 196.8 222.5 160.9
12 4.5 257.3 274.2 196.8 221.5 161.1
Table Three illustrates the comparison testing between the twelve sample
golf balls 10 of the present invention, and the four well-known and well-
played golf
balls. All of the golf balls in Table Three were subjected to the afore-
mentioned
shear test and rated. The golf balls were also subject to a standard robot
swing test
at 110 miles per hour ("mph") using a BIG BERTHA~ HAWKEYE ~ driver, at 90
mph using a BIG BERTHA~ HAWKEYE ~ driver, and at 79 mph using a BIG
BERTHA~ X-12~ five iron. Although the REVOLUTION~ had the best shear
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rating, its carry and total distance was only better than the Titlelist
PROFESSIONAL~. Example 12 of the golf balls 10 of the present invention had a
durability rating of 4.5, and it had a carry six yards better than the
REVOLUTION at
110 mph using a BIG BERTHA~ HAWKEYE ~ driver. The best distance at 110
mph using a BIG BERTHA~ HAWKEYE ~ driver was example 10 of the golf
balls 10 of the present invention which had a carry yardage of 256.7 yards and
a total
distance of 275.5 yards with a durability of 3.75. The next closest golf ball
in
distance was the DT-2, however, it only had a durability of 1. Table Three
demonstrates that the golf ball 10 of the present invention provides
objectively the
best overall durability with the best overall distance.
