Note: Descriptions are shown in the official language in which they were submitted.
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GOLF BALL HAVING HIGH INITIAL VELOCITY
FIELD
[0001] The present disclosure relates generally to a golf ball that has a
plurality of layers. The layers are designed to have a specified relationship
of
coefficient of restitution and compression in order to achieve a high initial
velocity.
BACKGROUND
[0002] It is standard in the industry to manufacture golf balls having a
plurality of layers. Individual designers in the industry may feel that
certain
characteristics are more important than others, and may design a golf ball to
optimize certain characteristics. Individual golfers may also feel that
certain
characteristics are more important or desirable than others.
[0003] In many cases, golfers desire golf balls that provide as long a
drive as possible. Drive length is governed by many factors out of the
golfer's
control, such as the relative height of the tee box and the fairway, obstacles
on or
adjacent the fairway, wind speed, weather, and the like. Drive length is also
governed by the golfer's swing parameters, such as his or her club head speed,
his or her form, and the club he or she chooses to use for a particular drive.
Drive
length is also governed by the initial velocity at which the ball comes off
the driver.
[0004] In other cases, such as in the short game, golfers desire golf balls
that have a good feel and good spin/spinnability when hit. The feel of a golf
ball is
often governed by the material from which the cover layer or layers are made.
The
choice of cover material may also be based on durability, scuff resistance,
color,
and the like.
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[0005] Many golfers desire a balance between the length of the ball
trajectory and the feel of the ball. While some golfers want one or the other
exclusively, it is more likely that a golfer will want a balance of these
features.
[0006] It is desirable, therefore, to develop a ball that includes a
combination of the features of a good feel and a maximum initial velocity.
This
combination of features is generally deemed desirable by a golfer in playing a
ball.
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SUMMARY
[0007] In one embodiment, a golf ball is provided. The golf ball may
have a core and a cover surrounding the core. The core may comprise a highly
neutralized polymer. The cover may comprise a deadening material. The core
may have a first coefficient of restitution and the ball may have a second
coefficient of restitution. The difference between the first coefficient of
restitution
and the second coefficient of restitution is less than about 0.032.
[0008] In another embodiment, a golf ball is provided. The golf ball may
have a core and a cover surrounding the core. The core may have a compression
x. The coefficient of restitution of the ball may be given by the equation
.6511 -
0.024x2 + 0.1165x. The coefficient of restitution of the core may be given by
the
equation 0.7951 - 0.0121x2 + 0.416x. The coefficient of restitution for any
ball
made according to this trend line may be capped to produce a conforming ball.
Using the deadening material as the cover may allow a designer to produce a
conforming ball using a high energy core.
[0009] A golf ball can be designed with a particular relationship between
compression, coefficient of restitution, and initial velocity. The material
for and
coefficient of restitution of the core can be devised to create a higher than
expected initial velocity of a ball and/or spinnability of a ball. The
material for and
compression of the core can be devised to create a different coefficient of
restitution for the ball as a whole than expected. In particular, balls made
according to the invention will tend to have a higher initial velocity than
expected
for a given coefficient of restitution. This means that a golfer can have
sufficient
initial velocity to obtain a good driver distance while having increased
spinnability
due to the low coefficient of restitution in the short game, particularly on
half
wedge shots.
[0010] Balls that include high energy materials in the core, such as a
highly neutralized polymer, and deadening or dampening materials in the cover,
such as thermoplastic polyurethane, can achieve these benefits. A ball with a
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given high energy core can give a designer more cover choices in order to
achieve
desired ball performance parameters.
[0011] Other systems, methods, features and advantages of the
embodiments will be, or will become, apparent to one of ordinary skill in the
art
upon examination of the following figures and detailed description. It is
intended
that all such additional systems, methods, features and advantages be included
within this description and this summary, be within the scope of the
disclosure, and
be protected by the following claims.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The invention can be better understood with reference to the
following drawings and description. The components in the figures are not
necessarily to scale, emphasis instead being placed upon illustrating the
principles
of the invention. Moreover, in the figures, like reference numerals designate
corresponding parts throughout the different views.
[0013] FIG. 1 is a side view of a golf ball according to the present
disclosure;
[0014] FIG. 2 is a cross-sectional view of an embodiment of a ball
according to the present disclosure;
[0015] FIG. 3 is a cross-sectional view of another embodiment of a ball
according to the present disclosure;
[0016] FIG. 4 is a cross-sectional view of another embodiment of a ball
according to the present disclosure;
[0017] FIG. 5 is a chart comparing initial velocity when tested with a
driver and the coefficient of restitution of the ball;
[0018] FIG. 6 is a chart comparing the coefficient of restitution and the
compression for two balls and their corresponding cores; and
[0019] FIG. 7 is a chart showing various trend lines for the various cores
from FIGS. 5 and 6.
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DETAILED DESCRIPTION
[0020] A multi-layered ball is disclosed. Although the embodiments
discussed herein are limited to golf balls, the invention is not intended to
be so
limited. The technology described herein may be applicable to any layered
article,
particularly a projectile, ball, recreational device, or component thereof.
[0021] FIG. 1 is a side view of a ball 100 that may be manufactured in
accordance with the technology disclosed herein. FIGS. 1-4 show a generic
dimple pattern applied to an outer surface 102 of ball 100. While the dimple
pattern on ball 100 may affect the flight path of ball 100, no specific dimple
pattern
is critical to the use of the disclosed embodiments. A designer may select
from
any appropriate dimple pattern to be applied to ball 100.
[0022] FIG. 2 is a cross-sectional view of a first embodiment of ball 100
taken along line 2-2 of FIG. 1. As shown in FIG. 2, a ball 200 may have two
layers. Ball 200 may include a core 204 and a cover 206 surrounding core 204.
Any of the embodiments of golf balls described herein may be made according to
any known technique, such as compression and/or injection molding the core,
injection molding any outer layers, optionally adhering the layers of the golf
ball
together with an adhesive, and painting or coating the ball such as by
spraying,
brushing, dipping, and pad printing.
[0023] Core 204 may be made of a highly energy efficient material. A
highly energy efficient material is one that tends to collide in a highly
elastic
manner. Core 204 may, in some embodiments, be made primarily or entirely from
a highly neutralized polymer. In some embodiments, the highly neutralized
polymer may be HPF 1000 or HPF 2000, available from E.I. DuPont de Nemours
and Company. In some embodiments, core 204 may have a diameter between
about 38 and about 41 mm. Cover 206 may, in some embodiments, be made of a
less energy efficient or deadening material. A less energy efficient material
is one
that tends to collide in a less elastic manner. In some embodiments, cover 206
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may be made primarily or entirely of a thermoplastic urethane resin. In some
embodiments, cover 206 may have a thickness of at least 2.1 mm.
[0024] In some embodiments, one or more additional outer layers may
be included but are not illustrated in FIG. 2 or any of the remaining FIGS.
External to cover 206 in FIG. 2 may be a top coat. The top coat may be a coat
applied to improve or adjust the appearance of ball 200. For example, the top
coat
may be applied to change the color of ball 200 or to change the degree of
sheen
on ball 200. In another embodiment, an additional coat may take the form of
the
application of a logo or other printing on exterior surface 202 of ball 200.
Other
additional coats may also be applied external to cover 206. It will be
understood
by a person having ordinary skill in the art that such external coats may be
applied
to any of the embodiments described herein, and accordingly, this optional
coating
will not be further described in connection with the following embodiments. It
should be noted that golf balls are typically coated. All of the tested balls
discussed in this application were provided with coatings, such as paint and
protective coatings. While the coatings may have some impact on the
coefficient
of restitution of the ball, it is believed that this impact is negligible for
the
considerations of the present embodiments. However, if the coatings are made
sufficiently thick or from a very hard or very soft material, this impact may
be
significant for design purposes of embodiments according to the present
disclosure.
[0025] FIG. 3 is a cross sectional view of a second embodiment of ball
100 taken along line 2-2 of FIG. 1. As shown in FIG. 3, a ball 300 may have
three
layers. Ball 300 may include a core 304, an inner cover layer 308 surrounding
core 304, and an outer cover layer 310 surrounding inner cover layer 308.
[0026] Core 304 may be made of a highly energy efficient material.
Core 304 may, in some embodiments, be made primarily or entirely from a highly
neutralized polymer. In some embodiments, the highly neutralized polymer may
be HPF 1000 or HPF 2000, available from E. 1. DuPont de Nemours and Company.
Core 304 may have a diameter between about 38 mm and about 41 mm. In some
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embodiments any layer other than the cover layer(s) may include a highly
neutralized ionomer. In some embodiments, all of the layers other than the
cover
layer(s) may aggregate to a size between about 38 mm and 41 mm. In some
embodiments, all of the layers other than the cover layer(s) may aggregate to
about 38.6 mm.
[0027] Inner cover layer 308 and outer cover layer 310 may, in some
embodiments, be made of one or more less energy efficient or deadening
materials. In some embodiments, inner cover layer 308, outer cover layer 310,
or
both, may be made primarily or entirely of a thermoplastic urethane resin or a
thermoplastic polyurethane resin. In other embodiments, inner cover layer 308,
outer cover layer 310, or both, may be made primarily or entirely of an
ionomeric
resin. In some embodiments, the ionomeric resin may be SURLYN ,
commercially available from E.I. DuPont de Nemours and Company. In some
embodiments, the combined thickness of inner cover layer 308 and outer cover
layer 310 may be about 2.1 mm.
[0028] FIG. 4 is a cross-sectional view of ball 100 taken along line 2-2 of
FIG. 1. As shown in FIG. 4, a ball 400 may have four layers. A first layer 412
may
be an inner core layer. A second layer 414 may be an outer core layer and may
surround first layer 412. A third layer 416 may be an inner cover layer and
may
surround second layer 414. A fourth layer 418 may be an outer cover layer and
may surround third layer 416. First or inner core layer 412 and second or
outer
core layer 414 may together be considered and referred to as core 420. Third
or
inner cover layer 416 and fourth or outer cover layer 418 may together be
considered and referred to as cover 422.
[0029] Core 420 may be made of one or more highly efficient materials,
and each of first layer 412 and second layer 414 may be made of a different
formulation of highly efficient material. At least one layer of core 420 may,
in some
embodiments, be made primarily or entirely from a highly neutralized polymer.
In
some embodiments, the highly neutralized polymer may be HPF 1000 or HPF
2000, available from E.I. DuPont de Nemours and Company. Cover 422 may be
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made of a less efficient or deadening material. In some embodiments, third
layer
416, fourth layer 418, or both, may be made primarily or entirely of a
thermoplastic
urethane resin. In other embodiments, third layer 416, fourth layer 418, or
both,
may be made primarily or entirely of an ionomeric resin. In some embodiments,
the ionomeric resin may be SURLYN , commercially available from E.I. DuPont
de Nemours and Company. In some embodiments, the combined thickness of
inner cover layer 416 and outer cover layer 418 may be about 2.1 mm. In some
embodiments any layer other than the cover layer(s) may include a highly
neutralized ionomer. In some embodiments, all of the layers other than the
cover
layer(s) may aggregate to a size between about 38 mm and 41 mm. In some
embodiments, all of the layers other than the cover layer(s) may aggregate to
about 38.6 mm.
[0030] In FIG. 4, ball 400 has been described and illustrated as having a
plurality of layers. In some embodiments, an additional layer may be added.
For
example, in some embodiments, a mantle layer may be added between core 420
and cover 422. In other embodiments, an intermediate cover layer may be
inserted between inner cover layer 416 and outer cover layer 418. In other
embodiments, an intermediate core layer may be inserted between inner core
layer 412 and outer core layer 414.
[0031] It will also be apparent to a person having ordinary skill in the art
that similar modifications may be made to any of the embodiments, based on the
specific desires of a designer without departing from the intention of the
present
embodiments. For example, a four layer ball could include an inner core layer,
an
intermediate core layer, an outer core layer, and a single cover layer.
Likewise, a
ball four layer ball could include a single core layer and an inner cover
layer, an
intermediate cover layer, and an outer cover layer. Balls having other numbers
of
intermediate layers would also be apparent to a person having ordinary skill
in the
art. The embodiments illustrated, therefore, are exemplary in nature, rather
than
intended to be limiting.
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[0032] Turning now to FIG. 5, there is shown a chart that demonstrates
a difference between the disclosed embodiments and balls currently
commercially
available. These balls are described in greater detail below. The values on
the
left side y-axis are the initial velocity of the ball when tested with a
driver. Each
ball was hit with the same condition (head speed, angle of attack, etc.) with
a 9.5
loft angle Nike SQ driver.
[0033] The initial velocity is shown in the chart by the height of each bar
on the bar graph. The initial velocity as shown in the bar chart is shown in
miles
per hour. An initial velocity of 150 miles per hour equates to about 220 feet
per
second. An initial velocity of about 170 miles per hour equates to about 250
feet
per second.
[0034] The values on the right side of the chart reflect the coefficient of
restitution (coefficient of restitution) of the ball as a whole. In order to
measure the
coefficient of restitution of an object, the object is fired by an air cannon
at an initial
velocity of about 40 meters per second. A steel plate is positioned about 1.2
meters from the cannon, and a speed monitoring device is located at a distance
of
about 0.6 to about 0.9 meters from the cannon. The object is fired from the
air
cannon, passes through the speed monitoring device to determine an initial
velocity. The object then strikes the steel plate and rebounds back through
the
speed monitoring device to determine the return velocity. The coefficient of
restitution is the ratio of the return velocity over the initial velocity. The
coefficient
of restitution for each ball is shown by the line 544 that appears on the
chart.
[0035] The x-axis identifies the balls tested. Each ball tested was tested
for initial velocity and coefficient of restitution. The first nine balls
(numbered 1-9)
are commercially available golf balls. Each of these golf balls has a core
made of
a butadiene rubber compound that has a diameter about 40 mm. For each ball,
the precise formulation of the core is slightly different. The core of each
ball is
made of butadiene rubber with different additives or different sizes that
create
different compressions and coefficient of restitution. It is believed that
there is a
correlation, potentially a strong correlation, between coefficient of
restitution and
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core size, so that minor variations in core size may have a non-negligible
impact
on coefficient of restitution. The cover of each of the balls is about 1.4 mm
thick
and is made primarily of SURLYN .
[0036] The ball labeled 10, on the other hand, is a ball made according
to the present embodiments. The ball labeled ball 10 instead has a core made
of
primarily of a highly neutralized polymer resin that is about 38 mm in
diameter.
The diameter of the core may be as large as about 41 mm. The cover of the ball
is about 2.1 mm thick, but may be as thin as about 0.9 mm thick. If desired, a
mantle layer may be included to ensure that the ball conforms to minimum USGA
size regulations of 42.67 mm (1.680 inches).
[0037] In comparing the relationship of initial velocity and coefficient of
restitution, it is noted that for balls 1-9, there is a general correlation
between
coefficient of restitution and initial velocity. For example, for balls 1, 2,
4, and 5,
where the coefficient of restitution is below 0.795, the initial velocity
drops to below
about 150.2. For balls 3, 6, 7, and 8, where the coefficient of restitution is
above
0.800, the initial velocity is above about 150.8. For ball 9, where the
coefficient of
restitution is about 0.800, the initial velocity is about 150.5. The chart,
therefore,
shows a general correlation between the coefficient of restitution and the
initial
velocity.
[0038] However, the chart shown in FIG. 5 indicates that the initial
velocity of ball 10 deviates from the anticipated initial velocity of a
conventional ball
with a coefficient of restitution of 0.774. For ball 10, the coefficient of
restitution
has a value of about 0.774. Instead of the initial velocity being under 150
miles
per hour, as would be predicted from conventional balls 1-9, the initial
velocity of
ball 10 remains at 150.8, which is almost as high as the initial velocity of
balls
having a coefficient of restitution that is much higher than ball 10.
Accordingly, by
using the ball structure indicated above, the ball coefficient of restitution
can
remain relatively low for better feel and spinnability in the short game,
while
maintaining an adequately high initial velocity for longer distance with a
driver.
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[0039] This is especially important for the half wedge shots. With a
lower coefficient of restitution ball, the golfer will tend to hit the ball
harder, i.e.,
with a higher club head speed, to achieve the same distance as a ball with
higher
coefficient of restitution. The harder hit (higher club head speed) imparts
more
spin to the ball. Therefore, a golfer can have a lower coefficient of
restitution ball
with good initial velocity and driver distance, but increased spinnability in
the short
game.
[0040] An additional feature that may be compared between existing
balls and the ball of the present disclosures may be seen in FIG. 6. FIG. 6 is
a
chart showing the relationship between compression and coefficient of
restitution
for various balls and ball cores. The values on the x-axis represent the
compression of the inner core layer of the ball. The compression is determined
in
a manner well-known in the art. The spherical core and/or ball is placed under
an
initial load of 10 kg. A measurement of the diameter of the ball, typically in
millimeters, is taken at one or more points, such as at the pole(s), the seam,
or a
random point. Either a single value or the average of the values is recorded.
The
load is increased to 130 kg and a second measurement of the diameter of the
ball,
also in millimeters, is taken at the same point or points. The single value or
the
average of the values under the greater load is recorded. The difference
between
the recorded values, in millimeters, is the compression.
[0041] The values on the y-axis represent the coefficient of restitution
(coefficient of restitution) for each of the four items considered. Line 650
represents the relationship between the compression and coefficient of
restitution
for a core that is about 38 mm in diameter and that is made of a butadiene
rubber
compound. The equation for this rubber core trend line is given by
y = 0.7531 - 0.0128x2 + 0.055x Eq. 1
where x is the inner core compression and y is the corresponding
coefficient of restitution.
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[0042] Line 660 represents the relationship between the compression
and coefficient of restitution for a ball that includes a cover that covers
the core
shown in line 650. The equation for this line is given by
y = 0.6794 - 0.0179x2 + 0.0831x Eq. 2
where x is the compression of the core and y is the coefficient of
restitution of the ball as a whole. The difference between the relative
coefficient of
restitution of the core and the coefficient of restitution of the ball ranges
between
about 0.035 and about 0.037.
[0043] However, a comparison of the relative coefficient of restitution for
the ball including a core made primarily or entirely of a highly neutralized
polymer
shows a distinct difference. Line 670 represents the relationship between the
compression and coefficient of restitution for a core that is about 38 mm in
diameter and that is made primarily or entirely of a highly neutralized
polymer.
The equation for this line is given by
y = 0.7951 - 0.0121x2 + 0.0416x Eq. 3
where x is the compression of the core and y is the corresponding
coefficient of restitution.
[0044] Line 680 represents the relationship between the compression
and coefficient of restitution for a ball that includes a cover that covers
the core
shown in line 670. The cover is the same cover structure as the cover of the
ball
governed by line 650. The equation for this line is given by
y = 0.6511 - 0.024x2 + 0.1165x Eq. 4
where x is the compression of the core and y is the coefficient of
restitution of the ball as a whole. The difference between the relative
coefficient of
restitution of the core and the coefficient of restitution of the ball ranges
between
about 0.026 and 0.031.
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[0045] As is clearly shown in FIG. 6, therefore, for a given inner core
compression, a ball with a rubber core will have a lower coefficient of
restitution
than a ball with an HNP core. Also, to maximize the effects of the deadening
material, the difference between the coefficient of restitution of the core
and the
coefficient of restitution of the ball should be at least 0.026, but may be
significantly higher, such as 0.037, 0.05, 0.1 or even higher. The lower the
coefficient of restitution of the ball, the more spinnable the ball may be, so
a ball
with a higher coefficient of restitution difference, such as at least 0.037 or
at least
0.05, may be desirable. The relatively high coefficient of restitution of the
cores
made according to the invention as discussed above allows for significant
flexibility
in selecting cover materials, as the coefficient of restitution of the ball as
a whole
may still be within top performance ranges when provided with a deadening
cover.
[0046] These benefits are shown more simply in FIG. 7, where rubber
core trend line 762 shows a consistently lower inner core compression for a
given
coefficient of restitution than HNP core trend line 760. HNP core ball trend
line
764 (the trend line for a full ball with an HNP core) is shown for reference.
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[0047] Accordingly, substituting a resin core with a specified coefficient
of restitution for a rubber core with the same specified coefficient of
restitution
allows for a dramatic difference in the relative coefficient of restitution of
the ball
and the core. This is particularly true when the resin core coefficient of
restitution
exceeds the coefficient of restitution given by the rubber core trend line and
where
the ball has a coefficient of restitution less than the coefficient of
restitution given
by the equation
y = -0.0103x + 0.8419 Eq. 5
where y is the coefficient of restitution and x is an inner core
compression.
[0048] This can typically be achieved by making at least one
interior/non-cover layer from a highly neutralized ionomer/polymer. The
properties
of the cover need not change between the butadiene rubber core and the highly
neutralized polymer core. However, the difference in coefficient of
restitution
between the core and the ball is at least about 0.004 less when the highly
neutralized polymer core is used. This allows for a ball with a higher
coefficient of
restitution to be made with the same cover materials.
[0049] When following the coefficient of restitution trend lines discussed
above for highly neutralized polymer cores and balls made with highly
neutralized
polymer cores, other limitations may need to be observed. For example, a
conforming ball will have a coefficient of restitution which is lower than the
trend
given by Eq. 5 or, more conservatively, by the equation
y = -0.0103x + 0.8299 Eq. 6
where y is the coefficient of restitution and x is an inner core compression.
Therefore, a designer may want to cap the coefficient of restitution of a ball
which
follows Eq. 4 so that the coefficient of restitution does not exceed the
coefficient of
restitution given by Eq. 6.
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[0050] A ball made within the scope of the disclosure above is believed
to have improved properties. Such a ball is believed to have a higher initial
velocity than may be expected. Such a ball may also allow for a greater
variety of
cover materials, particularly including those that have a lower cost. Such a
ball
may provide a golfer with a less expensive ball that has a longer trajectory
than
other balls.
[0051] Alternate constructions of the layered article may also be possible
to enhance these benefits. For example, a golf ball may be made according to
the
teaching of both this disclosure and the article described in U.S. Patent
Application
Serial Number 12/860,785, entitled "Golf Ball Having Layers with Specified
Moduli
and Hardnesses", and filed on August 20, 2010.
[0052] While various embodiments of the invention have been
described, the description is intended to be exemplary, rather than limiting
and it
will be apparent to those of ordinary skill in the art that many more
embodiments
and implementations are possible that are within the scope of the disclosure.
Accordingly, the disclosure is not to be restricted except in light of the
attached
claims and their equivalents. Also, various modifications and changes may be
made within the scope of the attached claims.
16
