U.S. patent application number 09/746826 was filed with the patent office on 2001-08-23 for golf ball containing high density fillers in the core and cover.
Invention is credited to Nealon, John L., Nesbitt, R. Dennis, Sullivan, Michael J..
Application Number | 20010016524 09/746826 |
Document ID | / |
Family ID | 26732563 |
Filed Date | 2001-08-23 |
United States Patent
Application |
20010016524 |
Kind Code |
A1 |
Sullivan, Michael J. ; et
al. |
August 23, 2001 |
Golf ball containing high density fillers in the core and cover
Abstract
The present invention is directed to improved golf ball
compositions in which the balls have low spin and excellent
distance. The balls contain tungsten or another high density filler
in a solid, central core in order to enhance coefficient of
restitution, and have very high quantities of whitening agent in
the outer cover layer to increase the moment of inertia and thus
reduce spin. This results in a golf ball exhibiting enhanced
distance while maintaining good durability.
Inventors: |
Sullivan, Michael J.;
(Chicopee, MA) ; Nesbitt, R. Dennis; (Westfield,
MA) ; Nealon, John L.; (Springfield, MA) |
Correspondence
Address: |
Associate Patent Counsel
Spalding Sports Worldwide, Inc.
425 Meadow Street
P.O Box 901
Chicopee
MA
01021-0901
US
|
Family ID: |
26732563 |
Appl. No.: |
09/746826 |
Filed: |
December 22, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09746826 |
Dec 22, 2000 |
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09110221 |
Jul 6, 1998 |
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60054049 |
Jul 14, 1997 |
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Current U.S.
Class: |
473/378 |
Current CPC
Class: |
A63B 37/0067 20130101;
A63B 2209/00 20130101; A63B 37/0066 20130101; A63B 37/0061
20130101; A63B 37/0075 20130101; A63B 37/04 20130101; A63B 37/0051
20130101; A63B 37/0004 20130101; A63B 45/00 20130101; A63B 37/0064
20130101; A63B 37/003 20130101; A63B 37/0034 20130101; A63B 37/0045
20130101; A63B 37/0046 20130101; A63B 37/0078 20130101; A63B
37/0033 20130101; A63B 37/0031 20130101; A63B 37/0047 20130101;
A63B 37/0074 20130101; A63B 37/12 20130101; A63B 37/0022
20130101 |
Class at
Publication: |
473/378 |
International
Class: |
A63B 037/12; A63B
037/14 |
Claims
What is claimed is:
1. A golf ball, comprising: a solid core comprising a rubber and
0.1-40 parts by weight of a filler material having a specific
gravity of at least 7 based upon 100 parts by weight of the rubber
material, and a dimpled cover layer comprising a resin and at least
2.5 parts by weight of a whitening agent selected from the group
consisting of titanium dioxide, barium sulphite, zinc sulfide white
based upon 100 parts by weight of the resin, the golf ball having a
coefficient of restitution of at least 0.750.
2. A golf ball according to claim 1, wherein the filler material is
tungsten.
3. A golf ball according to claim 1, wherein the filler material is
present in an amount of 10-30 parts by weight based upon 100 parts
by weight of the rubber material.
4. A golf ball according to claim 2, wherein the tungsten is
present in an amount of 17-23 parts by weight based upon 100 parts
by weight of the rubber material.
5. A golf ball according to claim 1, wherein the whitening agent is
present in an amount of 4-20 parts by weight based upon 100 parts
by weight of resin.
6. A golf ball according to claim 2, wherein the whitening agent is
present in an amount of 4-20 parts by weight based upon 100 parts
by weight of the resin.
7. A golf ball according to claim 1, wherein the whitening agent is
titanium dioxide.
8. A golf ball according to claim 2, wherein the whitening agent is
titanium dioxide.
9. A golf ball according to claim 4, wherein the whitening agent is
titanium dioxide.
10. A golf ball according to claim 6, wherein the whitening agent
is titanium dioxide.
11. A golf ball according to claim 1, wherein the resin comprises
ionomer.
12. A golf ball according to claim 2, wherein the resin comprises
ionomer.
13. A golf ball according to claim 8, wherein the resin comprises
ionomer.
14. A golf ball according to claim 1, further including a layer of
windings surrounding the solid core.
15. A golf ball according to claim 1, further including an inner
cover layer between the solid core and the dimpled inner layer.
16. A golf ball according to the claim 14, further including an
inner cover layer between the layer of windings and the dimpled
cover layer.
17. A golf ball, comprising: a solid core comprising a rubber
material and 0.1-40 parts by weight of tungsten based upon 100
parts by weight of the rubber material, and a dimpled cover layer
comprising a resin composition which includes ionomer, the cover
layer further including 2.5-20 parts by weight of titanium dioxide
based upon 100 parts by weight of the resin composition.
18. A golf ball according to claim 17, wherein the golf ball has a
coefficient of restitution of at least 0.750.
19. A golf ball according to claim 17, wherein the ball has a
coefficient of restitution of at least 0.780.
20. A golf ball comprising: a solid core comprising a rubber
material and 10-30 parts by weight of at least one member selected
from the group consisting of tungsten, bismuth and molybdenum based
upon 100 parts by weight of the rubber material, and a dimpled
cover layer comprising a resin composition which includes ionomer,
the cover layer further including 2.5-20 parts by weight of
titanium dioxide based upon 100 parts by weight of the resin
composition.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to golf balls and more
particularly to golf balls containing fillers.
BACKGROUND OF THE INVENTION
[0002] Golf balls utilized in tournament or competitive play today
are regulated for consistency purposes by the United States Golf
Association (U.S.G.A.). In this regard, there are five (5) U.S.G.A.
specifications which golf balls must meet under controlled
conditions. These are size, weight, velocity, driver distance and
symmetry.
[0003] Under the U.S.G.A. specifications, a golf ball can not weigh
more than 1.62 ounces (with no lower limit) and must measure at
least 1.68 inches (with no upper limit) in diameter. However, as a
result of the openness of the upper or lower parameters in size and
weight, a variety of golf balls can be made. For example, golf
balls are manufactured today which by the Applicant are slightly
larger (i.e., approximately 1.72 inches in diameter) while meeting
the weight, velocity, distance and symmetry specifications set by
the U.S.G.A.
[0004] Additionally, according to the U.S.G.A., the initial
velocity of the ball must not exceed 250 ft/sec. with a 2% maximum
tolerance (i.e., 255 ft/sec.) when struck at a set club head speed
on a U.S.G.A. machine. Furthermore, the overall distance of the
ball must not exceed 280 yards with a 6% tolerance (296.8 yards)
when hit with a U.S.G.A. specified driver at 160 ft/sec. (clubhead
speed) at a 10 degree launch angle as tested by the U.S.G.A.
Lastly, the ball must pass the U.S.G.A. administered symmetry test,
i.e., fly consistency (in distance, trajectory and time of flight)
regardless of how the ball is placed on the tee.
[0005] While the U.S.G.A. regulates five (5) specifications for the
purposes of maintaining golf ball consistency, alternative
characteristics (i.e., spin, feel, durability, distance, sound,
visibility, etc.) of the ball are constantly being improved upon by
golf ball manufacturers. This is accomplished by altering the type
of materials utilized and/or improving construction of the balls.
For example, the proper choice of cover and core materials are
important in achieving certain distance, durability and playability
properties. Other important factors controlling golf ball
performance include, but are not limited to, cover thickness and
hardness, core stiffness (typically measured as compression), ball
size and surface configuration.
[0006] As a result, a wide variety of golf balls have been designed
and are available to suit an individual player's game. Moreover,
improved golf balls are continually being produced by golf ball
manufacturers with technologized advancements in materials and
manufacturing processes.
[0007] Two of the principal properties involved in a golf ball's
performance are resilience and compression. Resilience is generally
defined as the ability of a strained body, by virtue of high yield
strength and low elastic modulus, to recover its size and form
following deformation. Simply stated, resilience is a measure of
energy retained to the energy lost when the ball is impacted with
the club.
[0008] In the field of golf ball production, resilience is
determined by the coefficient of restitution (C.O.R.), the constant
"e" which is the ratio of the relative velocity of an elastic
sphere after direct impact to that before impact.
[0009] Golf balls are typically described in terms of their size,
weight, composition, dimple pattern, compression, hardness,
durability, spin rate, and coefficient of restitution (COR). One
way to measure the COR of a golf ball is to propel the ball at a
given speed against a hard massive surface, and to measure its
incoming and outgoing velocity. The COR is the ratio of the
outgoing velocity to the incoming velocity and is expressed as a
decimal between zero and one.
[0010] There is no United States Golf Association limit on the COR
of a golf ball but the initial velocity of the golf ball must not
exceed 250.+-.5 ft/second. As a result, the industry goal for
initial velocity is 255 ft/second, and the industry strives to
maximize the COR without violating this limit.
[0011] The resilience or coefficient of restitution (COR) of a golf
ball is the constant "e," which is the ratio of the relative
velocity of an elastic sphere after direct impact to that before
impact. As a result, the COR ("e") can vary from 0 to 1, with 1
being equivalent to a perfectly or completely elastic collision and
0 being equivalent to a perfectly or completely inelastic
collision.
[0012] COR, along with additional factors such as club head speed,
club head mass, ball weight, ball size and density, spin rate,
angle of trajectory and surface configuration (i.e., dimple pattern
and area of dimple coverage) as well as environmental conditions
(e.g. temperature, moisture, atmospheric pressure, wind, etc.)
generally determine the distance a ball will travel when hit.
[0013] The COR in solid core balls is a function of the composition
of the molded core and of the cover. The molded core and/or cover
may be comprised of one or more layers such as in multi-layered
balls. In balls containing a wound core (i.e., balls comprising a
liquid or solid center, elastic windings, and a cover), the
coefficient of restitution is a function of not only the
composition of the center and cover, but also the composition and
tension of the elastomeric windings. As in the solid core balls,
the center and cover of a wound core ball may also consist of one
or more layers.
[0014] The coefficient of restitution is the ratio of the outgoing
velocity to the incoming velocity. In the examples of this
application, the coefficient of restitution of a golf ball was
measured by propelling a ball horizontally at a speed of 125.+-.5
feet per second (fps) and corrected to 125 fps against a generally
vertical, hard, flat steel plate and measuring the ball's incoming
and outgoing velocity electronically. Speeds were measured with a
pair of Oehler Mark 55 ballistic screens available from Oehler
Research, Inc., P.O. Box 9135, Austin, Tex. 78766, which provide a
timing pulse when an object passes through them. The screens were
separated by 36" and are located 25.25" and 61.25" from the rebound
wall. The ball speed was measured by timing the pulses from screen
1 to screen 2 on the way into the rebound wall (as the average
speed of the ball over 36"), and then the exit speed was timed from
screen 2 to screen 1 over the same distance. The rebound wall was
tilted 2 degrees from a vertical plane to allow the ball to rebound
slightly downward in order to miss the edge of the cannon that
fired it. The rebound wall is solid steel 2.0 inches thick.
[0015] As indicated above, the incoming speed should be 125.+-.5
fps but corrected to 125 fps. The correlation between COR and
forward or incoming speed has been studied and a correction has
been made over the .+-.5 fps range so that the COR is reported as
if the ball had an incoming speed of exactly 125.0 fps.
[0016] The coefficient of restitution must be carefully controlled
in all commercial golf balls if the ball is to be within the
specifications regulated by the United States Golf Association
(U.S.G.A.). As mentioned to some degree above, the U.S.G.A.
standards indicate that a "regulation" ball cannot have an initial
velocity exceeding 255 feet per second in an atmosphere of
75.degree. F. when tested on a U.S.G.A. machine. Since the
coefficient of restitution of a ball is related to the ball's
initial velocity, it is highly desirable to produce a ball having
sufficiently high coefficient of restitution to closely approach
the U.S.G.A. limit on initial velocity, while having an ample
degree of softness (i.e., hardness) to produce enhanced playability
(i.e., spin, etc.).
[0017] PGA compression is another important property involved in
the performance of a golf ball. The compression of the ball can
affect the playability of the ball on striking and the sound or
"click" produced. Similarly, compression can effect the "feel" of
the ball (i.e., hard or soft responsive feel), particularly in
chipping and putting.
[0018] Moreover, while compression itself has little bearing on the
distance performance of a ball, compression can affect the
playability of the ball on striking. The degree of compression of a
ball against the club face and the softness of the cover strongly
influences the resultant spin rate. Typically, a softer cover will
produce a higher spin rate than a harder cover. Additionally, a
harder core will produce a higher spin rate than a softer core.
This is because at impact a hard core serves to compress the cover
of the ball against the face of the club to a much greater degree
than a soft core thereby resulting in more "grab" of the ball on
the clubface and subsequent higher spin rates. In effect the cover
is squeezed between the relatively incompressible core and
clubhead. When a softer core is used, the cover is under much less
compressive stress than when a harder core is used and therefore
does not contact the clubface as intimately. This results in lower
spin rates.
[0019] The term "compression" utilized in the golf ball trade
generally defines the overall deflection that a golf ball undergoes
when subjected to a compressive load. For example, PGA compression
indicates the amount of change in golf ball's shape upon
striking.
[0020] In the past, PGA compression related to a scale of from 0 to
200 given to a golf ball. The lower the PGA compression value, the
softer the feel of the ball upon striking. In practice, tournament
quality balls have compression ratings around 70-110, preferably
around 80 to 100.
[0021] In determining PGA compression using the 0-200 scale, a
standard force is applied to the external surface of the ball. A
ball which exhibits no deflection (0.0 inches in deflection) is
rated 200 and a ball which deflects {fraction (2/10)}th of an inch
(0.2 inches) is rated 0. Every change of 0.001 of an inch in
deflection represents a 1 point drop in compression. Consequently,
a ball which deflects 0.1 inches (100.times.0.001 inches) has a PGA
compression value of 100 (i.e., 200-100) and a ball which deflects
0.110 inches (110.times.0.001 inches) has a PGA compression of 90
(i.e., 200- 110).
[0022] In order to assist in the determination of compression,
several devices have been employed by the industry. For example,
PGA compression is determined by an apparatus fashioned in the form
of a small press with an upper and lower anvil. The upper anvil is
at rest against a 200-pound die spring, and the lower anvil is
movable through 0.300 inches by means of a crank mechanism. In its
open position the gap between the anvils is 1.780 inches allowing a
clearance of 0.100 inches for insertion of the ball. As the lower
anvil is raised by the crank, it compresses the ball against the
upper anvil, such compression occurring during the last 0.200
inches of stroke of the lower anvil, the ball then loading the
upper anvil which in turn loads the spring. The equilibrium point
of the upper anvil is measured by a dial micrometer if the anvil is
deflected by the ball more than 0.100 inches (less deflection is
simply regarded as zero compression) and the reading on the
micrometer dial is referred to as the compression of the ball. In
practice, tournament quality balls have compression ratings around
80 to 100 which means that the upper anvil was deflected a total of
0.120 to 0.100 inches.
[0023] An example to determine PGA compression can be shown by
utilizing a golf ball compression tester produced by OK Automation,
Sinking Spring, Pa. 19608. The value obtained by this tester
relates to an arbitrary value expressed by a number which may range
from 0 to 100, although a value of 200 can be measured as indicated
by two revolutions of the dial indicator on the apparatus. The
value obtained defines the deflection that a golf ball undergoes
when subjected to compressive loading. The OK Automation test
apparatus consists of a lower movable platform and an upper movable
spring-loaded anvil. The dial indicator is mounted such that it
measures the upward movement of the springloaded anvil. The golf
ball to be tested is placed in the lower platform, which is then
raised a fixed distance. The upper portion of the golf ball comes
in contact with and exerts a pressure on the springloaded anvil.
Depending upon the distance of the golf ball to be compressed, the
upper anvil is forced upward against the spring.
[0024] Alternative devices have also been employed to determine
compression. For example, Applicant also utilizes a modified Riehle
Compression Machine originally produced by Riehle Bros. Testing
Machine Company, Phil., Pa. to evaluate compression of the various
components (i.e., cores, mantle cover balls, finished balls, etc.)
of the golf balls. The Riehle compression device determines
deformation in thousandths of an inch under a fixed initialized
load of 200 pounds. The selection of an appropriate anvil for use
in making a measurement is based upon the diameter of the component
which is to be measured. Using such a device, a Riehle compression
of 61 corresponds to a deflection under load of 0.061 inches.
[0025] Additionally, an approximate relationship between Riehle
compression and PGA compression exists for balls of the same size.
It has been determined by Applicant that Riehle compression
corresponds to PGA compression by the general formula PGA
compression= 160-Riehle compression. Consequently, 80 Riehle
compression corresponds to 80 PGA compression, 70 Riehle
compression corresponds to 90 PGA compression, and 60 Riehle
compression corresponds to 100 PGA compression. For reporting
purposes, Applicant's compression values are usually measured as
Riehle compression.
[0026] Furthermore, additional compression devices may also be
utilized to monitor golf ball compression so long as the
correlation to PGA compression is know. These devices have been
designed, such as a Whitney Tester, to correlate or correspond to
PGA compression through a set relationship or formula.
[0027] Additionally, cover hardness and thickness are important in
producing the distance, playability and durability properties of a
golf ball. As mentioned above, cover hardness directly affects the
resilience and thus distance characteristics of a ball. All things
being equal, harder covers produce higher resilience. This is
because soft materials detract from resilience by absorbing some of
the impact energy as the material is compressed on striking.
[0028] Furthermore, soft covered balls are preferred by the more
skilled golfer because he or she can impact high spin rates that
give him or her better control or workability of the ball. Spin
rate is an important golf ball characteristic for both the skilled
and unskilled golfer. As just mentioned, high spin rates allow for
the more skilled golfer, such as PGA and LPGA professionals and low
handicap players, to maximize control of the golf ball. This is
particularly beneficial to the more skilled golfer when hitting an
approach shot to a green. Thus, the more skilled golfer generally
prefers a golf ball exhibiting high spin rate properties.
[0029] However, a high spin golf ball is not desired by all
golfers, particularly high handicap players who cannot
intentionally control the spin of the ball. Additionally, since a
high spinning ball will roll substantially less than a low spinning
golf ball, a high spinning ball is generally short on distance.
[0030] In this regard, less skilled golfers, have, among others,
two substantial obstacles to improving their game: slicing and
hooking. When a club head meets a ball, an unintentional side spin
is often imparted which sends the ball off its intended course. The
side spin reduces one's control over the ball as well as the
distance the ball will travel. As a result, unwanted strokes are
added to the game.
[0031] Consequently, while the more skilled golfer frequently
desires a high spin golf ball, a more efficient ball for the less
skilled player is a golf ball that exhibits low spin properties.
The low spin ball reduces slicing and hooking and enhances
distance. Furthermore, since a high spinning ball is generally
short on distance, such a ball is not universally desired by even
the more skilled golfer.
[0032] With respect to high spinning balls, up to approximately
twenty years ago, most high spinning balls were comprised of balata
or blends of balata with elastomeric or plastic materials. The
traditional balata covers are relatively soft and flexible. Upon
impact, the soft balata covers compress against the surface of the
club producing high spin. Consequently, the soft and flexible
balata covers provide an experienced golfer with the ability to
apply side spin to control the ball in flight in order to produce a
draw or a fade, or a backspin which causes the ball to "bite" or
stop abruptly on contact with the green.
[0033] Moreover, the soft balata covers produce a soft "feel" to
the low handicap player. Such playability properties (workability,
feel, etc.) are particularly important in short iron play with low
swing speeds and are exploited significantly by relatively skilled
players.
[0034] However, despite all the benefits of balata, balata covered
golf balls are easily cut and/or damaged if mis-hit. Golf balls
produced with balata or balata-containing cover compositions
therefore have a relatively short lifespan.
[0035] Additionally, soft balata covered balls are shorter in
distance. While the softer materials will produce additional spin,
this is frequently produced at the expense of the initial velocity
of the ball. Moreover, as mentioned above, higher spinning balls
tend to roll less.
[0036] As a result of these negative properties, balata and its
synthetic substitutes, transpolyisoprene and trans-polybutadiene,
have been essentially replaced as the cover materials of choice by
new synthetic materials. Included in this group of materials are
ionomer resins.
[0037] Ionomeric resins are polymers in which the molecular chains
are cross-linked by ionic bonds. As a result of their toughness,
durability and flight characteristics, various ionomeric resins
sold by E. I. DuPont de Nemours & Company under the trademark
"Surlyn.RTM." and more recently, by the Exxon Corporation (see U.S.
Pat. No. 4,911,451) under the trademarks "Escor" and"Iotek.RTM.",
have become the materials of choice for the construction of golf
ball covers over the traditional "balata" (transpolyisoprene,
natural or synthetic) rubbers. As stated, the softer balata covers,
although exhibiting enhanced playability properties, lack the
durability (cut and abrasion resistance, fatigue endurance, etc.)
properties required for repetitive play and are limited in
distance.
[0038] Ionomeric resins are generally ionic copolymers of an
olefin, such as ethylene, and a metal salt of an unsaturated
carboxylic acid, such as acrylic acid, methacrylic acid, or maleic
acid. Metal ions, such as sodium or zinc, are used to neutralize
some portion of the acidic group in the copolymer resulting in a
thermoplastic elastomer exhibiting enhanced properties, i.e.,
durability, etc., for golf ball cover construction over balata.
[0039] Historically, some of the advantages produced by ionomer
resins in increased durability were offset to some degree by
decreases produced in playability. This was because although the
ionomeric resins were very durable, they initially tended to be
very hard when utilized for golf ball cover construction, and thus
lacked the degree of softness required to impart the spin necessary
to control the ball in flight. Since the initial ionomeric resins
were harder than balata, the ionomeric resin covers did not
compress as much against the face of the club upon impact, thereby
producing less spin.
[0040] In addition, the initial, harder and more durable ionomeric
resins lacked the "feel" characteristic associated with the softer
balata related covers. The ionomer resins tended to produce a hard
responsive "feel" when struck with a golf club such as a wood,
iron, wedge or putter.
[0041] As a result of these difficulties and others, a great deal
of research has been and is currently being conducted by golf ball
manufacturers in the field of ionomer resin technology. There are
currently more than fifty (50) commercial grades of ionomers
available both from DuPont and Exxon, with a wide range of
properties which vary according to the type and amount of metal
cations, molecular weight, composition of the base resin (i.e.,
relative content of ethylene and methacrylic and/or acrylic acid
groups) and additive ingredients such as reinforcement agents, etc.
However, a great deal of research continues in order to develop
golf ball cover compositions exhibiting not only the improved
impact resistance and carrying distance properties produced by the
"hard" ionomeric resins, but also the playability (i.e., "spin",
"feel", etc.) characteristics previously associated with the "soft"
balata covers, properties which are still desired by the more
skilled golfer.
[0042] Consequently, a number of two-piece (a solid resilient
center or core with a molded cover) and three-piece (a liquid or
solid center, elastomeric winding about the center, and a molded
cover) golf balls have been produced by the Applicant and others to
address these needs. The different types of materials utilized to
formulate the cores, covers, etc. of these balls dramatically
alters the balls' overall characteristics.
[0043] One of the ways to affect spin of a golf ball is to transfer
weight toward or away from the center of the ball. A golf ball with
increased perimeter weighting has an increased moment of inertia
and/or a greater radius of gyration and thus generates lower
initial spin than a golf ball with increased weighting of the
center or core. A ball with increased perimeter weighting also has
greater spin retention than a ball with conventional weighting. The
present invention is directed to a high moment of inertia golf ball
which has a relatively low spin rate.
SUMMARY OF THE INVENTION
[0044] An object of the invention is to provide a low spin golf
ball with a high COR.
[0045] Another object of the invention is to provide a golf ball
which will travel a long distance.
[0046] A further object of the invention is to provide a method of
making a low spin golf ball.
[0047] Other objects will be in part obvious and in part pointed
out more in detail hereafter.
[0048] The invention in a preferred form is a golf ball comprising
a solid core formed from a rubber material and 0.1-40 parts by
weight of a filler material having a specific gravity of at least 7
based upon 100 parts by weight of the rubber material, and a
dimpled cover layer comprising an ionomeric resin and at least 2.5
parts by weight of a whitening agent selected from the group
consisting of titanium dioxide, barium sulfite, and zinc sulfide
white based upon 100 parts by weight of the resin, the golf ball
having a coefficient of restitution of at least 0.750. The core of
the golf ball preferably has 1-4 volume percent, and more
preferably 1-2.5 volume percent more rubber than a core which
contains zinc oxide filler in place of the high specific gravity
filler and has the same weight and Riehle compression.
[0049] In a particularly preferred form of the invention, the
filler material is tungsten. The whitening agent most preferably is
titanium dioxide. The whitening agent preferably is present in an
amount of 5-10 parts by weight based upon 100 parts by weight of
the resin. The dimpled cover layer preferably comprises
ionomer.
[0050] The solid core can have a cover layer formed directly
thereon or can be surrounded by a layer of windings. An inner cover
layer can be included beneath the dimpled cover layer.
[0051] Another preferred form of the invention is a golf ball
comprising a solid core formed from a rubber material and 0.1-40
parts by weight of tungsten based upon 100 parts by weight of the
rubber material, and a dimpled cover layer comprising an ionomeric
resin and at least 2.5 parts by weight of titanium dioxide based
upon 100 parts by weight of the resin. The resin used to form the
golf ball cover preferably comprises ionomer. The golf ball
preferably has a coefficient of restitution of at least 0.750.
[0052] Yet another preferred form of the invention is a golf ball
comprising a solid core comprising a rubber material and 10-30
parts by weight of at least one member selected from the group
consisting of tungsten, bismuth, and molybdenum based upon 100
parts by weight of the rubber material, and a dimpled cover layer
comprising a resin composition which includes ionomer and 2.5-20
parts by weight of titanium dioxide based upon 100 parts by weight
of the resin composition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] FIG. 1 shows a preferred embodiment of a two-layer golf ball
according to the present invention.
[0054] FIG. 2 shows a preferred embodiment of a multi-layer,
non-wound golf ball according to a preferred embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0055] The moment of inertia of a golf ball (also known as
rotational inertia) is the sum of the products formed by
multiplying the mass (or sometimes the area) of each element of a
figure by the square of its distance from a specified line such as
the center of a golf ball. This property is directly related to the
radius of gyration of a golf ball which is the square root of the
ratio of the moment of inertia of a golf ball about a given axis to
its mass. It has been found that the greater the moment of inertia
(or the farther the radius of gyration is from the center of the
ball) the lower the initial spin rate is of the ball.
[0056] The present invention is directed, in part, to increasing
the moment of inertia of two-layered and multi-layered golf balls
by varying the weight arrangement of the cover and the core
components. By varying the weight, size and density of the
components of the golf ball, the moment of inertia of a golf ball
can be increased. Such a change can occur in a multi-layered golf
ball, including a ball containing one or more cover layers and/or a
layer of windings, to enhance distance due to the production of
less side spin and improved roll.
[0057] Accordingly, the present invention is directed to an
improved golf ball exhibiting enhanced distance (i.e., improved
resilience, less side spin, improved roll) without adversely
affecting, and in many instances, improving the ball's abrasion and
scuff resistance characteristics.
[0058] Referring now to the Figures and first to FIG. 1, a
two-layer golf ball is shown and is designated as 10. The golf ball
includes a solid central core 12 and a dimpled cover 14 formed over
the core 12. A thin polyurethane coat 16 which may consist of more
than one layer is formed over the cover 14.
[0059] The core 12 contains polybutadiene rubber and 0.1-40 parts
by weight of tungsten or another heavy particulate material. As a
result of the use of a high-density material, such as tungsten,
only a very small volume needs to be added. Thus, this golf ball
core 12 has a particularly high polybutadiene content. In contrast,
prior known cores typically contain 5-30 parts by weight of zinc
oxide and/or 0-30 parts by weight of calcium carbonate fillers or
other heavy fillers such as barium sulfate (e.g. barytes). When at
least a portion of the zinc oxide and calcium carbonate is replaced
by tungsten, further quantities of rubber are added to result in
the same volume of core material.
[0060] The inventors have surprisingly found that the use of
tungsten in place of at least a portion of the zinc dioxide and
calcium carbonate results in an increase of coefficient of
restitution for the ball at a given core PGA compression. For
example, when a core has a PGA compression of 30-100, the use of
20.0 parts by weight of tungsten and additional polybutadiene
rubber material results in an increase in COR of ten points as
compared to a golf ball formed from a core which contains 5-30
parts by weight of zinc oxide and/or 0-30 parts by weight of
calcium carbonate. The inclusion on tungsten in the core can result
in an increase in the amount of rubber in an equal volume core in a
amount on the order of 1-4 volume percent at the same weight and
Riehle compression.
[0061] The cover 14 of the golf ball preferably comprises ionomer,
and may also include a number of other materials, including but not
limited to polyurethane polyester, polyether amide, polyamide,
styrene butadiene styrene, SBES, olefins and blends thereof. The
cover is different from prior known covers in that it contains a
very high quantity of whitener which serves the dual function of
both providing the cover with excellent whiteness and providing
outer perimeter weighting to the ball. While golf balls typically
contain 0.3-2.3 parts by weight of titanium dioxide in the outer
cover layer, the golf balls of the present invention contain at
least 2.5 parts by weight of whitener based upon 100 parts by
weight of resin composition, more preferably 3.5-10 parts by weight
of whitening agent, and most preferably 2.5-5.0 parts by weight of
whitening agent. The whitening agent preferably includes at least
one member selected from the group consisting of titanium dioxide,
barium sulfite, and zinc sulfide white. The use of this quantity of
whitening agent results in an increase of 0.15 grams to the cover
of the ball. As a result, the core of the ball has a weight
reduction of roughly the same amount, i.e., 0.15 grams.
[0062] Referring now to FIG. 2, a multi-layer, non-wound golf ball
according to the invention is shown and is designated as 110. The
golf ball includes a solid central core 112, an inner cover layer
114, and a dimpled outer cover layer 116. A thin polyurethane coat
117 which may consist of more than one layer is formed over the
outer cover layer 116.
[0063] The core 114 can be generally identical to core 14 of the
embodiment shown in FIG. 1 except the diameter is usually less. The
inner cover layer 114 preferably comprises ionomer, and more
preferably comprises high acid ionomers such as 35-50 wt. % Iotek
1002 and 50-65 wt. % Iotek 1003. The outer cover layer 116 is
similar to cover 14 of the FIG. 1 embodiment in that it can be
formed form the same cover materials as cover 14 and in that it
contains at least 2.5 parts by weight of whitening agent based upon
100 parts by weight of resin. This results in a weight transfer
from the core or inner cover layer to the outer cover layer,
thereby increasing the moment of inertia of the ball.
[0064] In a particularly preferred form of a two layer ball, the
core has a diameter of 1.52-1.57 in., and the cover has a thickness
of 0.06-0.07 in. In a particularly preferred multi-layer embodiment
such as that shown in FIG. 2, the core has a diameter of 1.54-1.58
in., the inner cover layer has a thickness of 0.04 to 0.08 in., and
the outer cover layer 116 has a thickness of 0.04-0.07 in.
[0065] Additional materials may be added to the cover compositions
(both inner and outer cover layer) of the present invention
including dyes (for example, Ultramarine Blue sold by Whitaker,
Clark and Danieis of South Plainsfield, N.J.) (see U.S. Pat. No.
4,679,795); pigments such as zinc oxide, and UV absorbers;
antioxidants; antistatic agents; and stabilizers. Further, the
cover compositions of the present invention may also contain
softening agents, such as plasticizers, processing aids, etc., as
long as the desired properties produced by the golf ball covers are
not impaired.
[0066] The specially produced solid core compositions and resulting
non-wound or wound centers according to the present invention are
manufactured using relatively conventional techniques. In this
regard, the core compositions of the invention may be based on
polybutadiene, and mixtures of polybutadiene with other elastomers.
It is preferred that the base elastomer have a relatively high
molecular weight. The broad range for the molecular weight of
suitable base elastomers is from about 50,000 to 500,000. A more
preferred range for the molecular weight of the base elastomer is
from about 100,000 to about 500,000. As a base elastomer for the
core composition, cis-polybutadiene is preferably employed, or a
blend of cis-polybutadiene with other elastomers may also be
utilized. Most preferably, cis-polybutadiene having a
weight-average molecular weight of from about 100,000 to about
500,000 is employed. Along this line, it has been found that the
high cis-polybutadiene manufactured and sold by Shell Chemical Co.,
Houston, Tex., under the tradename Cariflex BR-1220 and the high
cis-polybutadiene sold by Bayer Corp. under the designation Taktene
220.
[0067] The unsaturated carboxylic acid component of the core
composition (a co-crosslinking agent) is the reaction product of
the selected carboxylic acid or acids an oxide or carbonate of a
metal such as zinc, magnesium, barium, calcium, lithium, sodium,
potassium, cadmium, lead, tin, and the like. Preferably, the oxides
of polyvalent metals such as zinc, magnesium and cadmium are used,
and most preferably, the oxide is zinc oxide.
[0068] Exemplary of the unsaturated carboxylic acids which find
utility in the present core compositions are acrylic acid,
methacrylic acid, itaconic acid, crotonic acid sorbic acid, and the
like, and mixtures thereof. Preferably, the acid component is
either acrylic or methacrylic acid. Usually, from about 15 to about
25, and preferably from about 17 to about 21 parts by weight of the
carboxylic acid salt, such as zinc diacrylate, is included in the
core composition. The unsaturated carboxylic acids and metal salts
thereof are generally soluble in the elastomeric base, or are
readily dispersible.
[0069] The heavyweight filler in the core has a specific gravity of
7 or more. Preferred fillers include the following:
1 material spec. grav. tungsten 19.35 bismuth 9.78 nickel 8.90
molybdenum 10.2 iron 7.86 copper 8.94 brass 8.2-8.4 bronze
8.70-8.74 cobalt 8.92 tin 7.31 zinc 7.14
[0070] The filter is present in an amount of 0.1-40 parts by weight
and more preferably 10-30 parts by weight based upon 100 parts by
weight of rubber material.
[0071] The free radical initiator included in the core composition
is any known polymerization initiator (a co-crosslinking agent)
which decomposes during the cure cycle. The term "free radical
initiator" as used herein refers to a chemical which, when added to
a mixture of the elastomeric blend and a metal salt of an
unsaturated, carboxylic acid, promotes crosslinking of the
elastomers by the metal salt of the unsaturated carboxylic acid.
The amount of the selected initiator present is dictated only by
the requirements of catalytic activity as a polymerization
initiator. Suitable initiators include peroxides, persulfates, azo
compounds and hydrazides. Peroxides which are readily commercially
available are conveniently used in the present invention, generally
in amounts of from about 0.1 to about 10.0 and preferably in
amounts of from about 0.3 to about 3.0 parts by weight per each 100
parts of elastomer.
[0072] Exemplary of suitable peroxides for the purposes of the
present invention are dicumyl peroxide; n-butyl 4,4'-bis
(butylperoxy) valerate; 1,1-bis(t-butylperoxy)-3,3,5-trimethyl
cylcohexane; di-t-butyl peroxide; 2,5-di-(t-butylperoxy)-2,5
dimethyl hexane and the like, as well as mixtures thereof. It will
be understood that the total amount of initiators used will vary
depending on the specific end product desired and the particular
initiators employed.
[0073] Examples of such commercially available peroxides are
Luperco 230 or 231 XL sold by Atochem, Lucidol Division, Buffalo,
N.Y., and Trigonox 17/40 or 29/40 sold by Akzo Chemie America,
Chicago, Ill. In this regard Luperco 230 XL and Trigonox 17/40 are
comprised of n-butyl 4,4-bis (butylperoxy) valerate; and, Luperco
231 XL and Trigonox 29/40 are comprised of 1,1-bis
(t-butylperoxy)-3,3,5-trimethyl cyclohexane. The one hour half life
of Trigonox 29/40 is about 129.degree. C.
[0074] The core compositions of the present invention may
additionally contain any other suitable and compatible modifying
ingredients including, but not limited to, metal oxides, fatty
acids, and diisocyanates and polypropylene powder resin. For
example, Papi 94, a polymeric diisocyanate, commonly available from
Dow Chemical Co., Midland, Mich., is an optional component in the
rubber compositions. It can range from about 0 to 5 parts by weight
per 100 parts by weight rubber (phr) component, and acts as a
moisture scavenger. In addition, it has been found that the
addition of a polypropylene powder resin results in a core which is
too hard (i.e., exhibits low compression) and thus allows for a
reduction in the amount of crosslinking agent utilized to soften
the core to a normal or below normal compression.
[0075] Furthermore, because polypropylene powder resin can be added
to core composition without an increase in weight of the molded
core upon curing, the addition of the polypropylene powder allows
for the addition of higher specific gravity fillers (if desired),
such as mineral fillers. Since the crosslinking agents utilized in
the polybutadiene core compositions are expensive and/or the higher
specific gravity fillers are relatively inexpensive, the addition
of the polypropylene powder resin substantially lowers the cost of
the golf ball cores while maintaining, or lowering, weight and
compression.
[0076] The polypropylene (C.sub.3H.sub.5) powder suitable for use
in the present invention has a specific gravity of about 0.90
g/cm.sup.3, a melt flow rate of about 4 to about 12 and a particle
size distribution of greater than 99% through a 20 mesh screen.
Examples of such polypropylene powder resins include those sold by
the Amoco Chemical Co., Chicago, Ill., under the designations "6400
P", "7000 P" and "7200 P". Generally, from 0 to about 25 parts by
weight polypropylene powder per each 100 parts of elastomer are
included in the present invention.
[0077] Various activators may also be included in the compositions
of the present invention. For example, zinc oxide and/or magnesium
oxide are activators for the polybutadiene. The activator can range
from about 2 to about 50 parts by weight per 100 parts by weight of
the rubbers (phr) component. The amount of activation utilized can
be reduced in order to lighten the weight of the core.
[0078] Moreover, reinforcement agents may be added to the
composition of the present invention. As noted above, the specific
gravity of polypropylene powder is very low, and when compounded,
the polypropylene powder produces a lighter molded core. Further,
when a lesser amount of activation is used, the core is also
lighter. As a result, if necessary, higher gravity fillers may be
added to the core composition so long as the specific core weight
limitations are met. The amount of additional filler included in
the core composition is primarily dictated by weight restrictions
and preferably is included in amounts of from about 0 to about 100
parts by weight per 100 parts rubber.
[0079] Exemplary fillers include mineral fillers such as limestone,
silica, mica, barytes, calcium carbonate, or clays. Limestone is
ground calcium/magnesium carbonate and is used because it is an
inexpensive, heavy-filler.
[0080] As indicated, ground flash filler may be incorporated and is
preferably 20 mesh ground up center stock from the excess flash
from compression molding. It lowers the cost and may increase the
hardness of the ball.
[0081] Fatty acids or metallic salts of fatty acids may also be
included in the compositions, functioning to improve moldability
and processing. Generally, free fatty acids having from about 10 to
about 40 carbon atoms, and preferably having from about 15 to about
20 carbon atoms, are used. Exemplary of suitable fatty acids are
stearic acid and linoleic acids, as well as mixtures thereof.
Exemplary of suitable metallic salts of fatty acids include zinc
stearate. When included in the core compositions, the fatty acid
component is present in amounts from about 1 to about 25,
preferably in amounts from about 2 to about 15 parts by weight
based on 100 parts rubber (elastomer).
[0082] Diisocyanates may also be optionally included in the core
compositions when utilized, the diisocyanates are included in
amounts of from about 0.2 to about 5.0 parts by weight based on 100
parts rubber. Exemplary of suitable diisocyanates is
4,4'-diphenylmethane diisocyanate and other polyfunctional
isocyanates known to the art.
[0083] Furthermore, the dialkyl tin difatty acids set forth in U.S.
Pat. No. 4,844,471, the dispersing agents disclosed in U.S. Pat.
No. 4,838,556, and the dithiocarbamates set forth in U.S. Pat. No.
4,852,884 may also be incorporated into the polybutadiene
compositions of the present invention. The specific types and
amounts of such additives are set forth in the above identified
patents, which are incorporated herein by reference.
[0084] The core compositions of the invention are generally
comprised of 100 parts by weight of a base elastomer (or rubber)
selected from polybutadiene and mixtures of polybutadiene with
other elastomers, 10 to 40 parts by weight of at least one metallic
salt of an unsaturated carboxylic acid, 0.1-40 parts by weight of a
filler material having a specific gravity of at least 7, and 0.1 to
10 parts by weight of a free radical initiator.
[0085] As indicated above, additional suitable and compatible
modifying agents such as particulate polypropylene resin, fatty
acids, and secondary additives such as Pecan shell flour, ground
flash (i.e., grindings from previously manufactured cores of
substantially identical construction), barium sulfate, zinc oxide,
etc. may be added to the core compositions to adjust the weight of
the ball as necessary in order to have the finished molded ball
(core, cover and coatings) to closely approach the U.S.G.A. weight
limit of 1.620 ounces.
[0086] In producing golf ball cores utilizing the present
compositions, the ingredients may be intimately mixed using, for
example, two roll mills or a Banbury.RTM. mixer until the
composition is uniform, usually over a period of from about 5 to
about 20 minutes. The sequence of addition of components is not
critical. A preferred blending sequence is as follows.
[0087] The elastomer, polypropylene powder resin (if desired),
fillers, zinc salt, metal oxide, fatty acid, and the metallic
dithiocarbamate (if desired), surfactant (if desired), and tin
difatty acid (if desired), are blended for about 7 minutes in an
internal mixer such as a Banbury.RTM. mixer. As a result of shear
during mixing, the temperature rises to about 200.degree. F. The
initiator and diisocyanate are then added and the mixing continued
until the temperature reaches about 220.degree. F. whereupon the
batch is discharged onto a two roll mill, mixed for about one
minute and sheeted out.
[0088] The sheet is rolled into a "pig" and then placed in a
Barwell preformer and slugs are produced. The slugs are then
subjected to compression molding at about 320.degree. F. for about
14 minutes. After molding, the molded cores are cooled, the cooling
effected at room temperature for about 4 hours or in cold water for
about one hour. The molded cores are subjected to a centerless
grinding operation whereby a thin layer of the molded core is
removed to produce a round core having a diameter of 1.3 to 1.7
inches (preferably about 1.45 to about 1.60 inches and most
preferably, 1.52 to 1.57 inches) for a two-piece ball.
Alternatively, the cores are used in the as-molded state with no
grinding needed to achieve roundness.
[0089] The mixing is desirably conducted in such a manner that the
composition does not reach incipient polymerization temperatures
during the blending of the various components.
[0090] Usually the curable component of the composition will be
cured by heating the composition at elevated temperatures on the
order of from about 275.degree. F. to about 350.degree. F.,
preferably and usually from about 290.degree. F. to about
325.degree. F., with molding of the composition effected
simultaneously with the curing thereof. The composition can be
formed into a core structure by any one of a variety of molding
techniques, e.g. injection, compression, or transfer molding. When
the composition is cured by heating, the time required for heating
will normally be short, generally from about 10 to about 20
minutes, depending upon the particular curing agent used. Those of
ordinary skill in the art relating to free radical curing agents
for polymers are conversant with adjustments of cure times and
temperatures required to effect optimum results with any specific
free radical agent.
[0091] After molding, the core is removed from the mold and the
surface thereof, preferably treated to facilitate adhesion thereof
to the covering materials. Surface treatment can be effected by any
of the several techniques known in the art, such as corona
discharge, ozone treatment, sand blasting, brush tumbling and the
like. Preferably, surface treatment is effected by grinding with an
abrasive wheel.
[0092] The various cover composition layers of the present
invention may be produced according to conventional melt blending
procedures. In the case of the outer cover layer, when a blend of
hard and soft, low acid ionomer resins are utilized, the hard
ionomer resins are blended with the soft ionomeric resins and with
a masterbatch containing the desired additives in a Banbury.RTM.
mixer, two-roll mill, or extruder prior to molding. The blended
composition is then formed into slabs and maintained in such a
state until molding is desired. Alternatively, a simple dry blend
of the pelletized or granulated resins and color masterbatch may be
prepared and fed directly into the injection molding machine where
homogenization occurs in the mixing section of the barrel prior to
injection into the mold. If necessary, further additives, may be
added and uniformly mixed before initiation of the molding process.
A similar process is utilized to formulate the ionomer resin
compositions used to produce the inner cover layer.
[0093] The golf balls of the present invention can be produced by
molding processes currently well known in the golf ball art.
Specifically, the golf balls can be produced by injection molding
or compression molding the relatively thick inner cover layer about
solid molded cores or wound centers with a solid central core to
produce an intermediate golf ball having a diameter of about 1.3 to
1.7 inches. The outer layer (preferably 0.015 inches to 0.110
inches in thickness) is subsequently molded over the inner layer to
produce a golf ball having a diameter of 1.680 inches or more.
[0094] In compression molding, the inner cover composition is
formed via injection at about 380.degree. F. to about 450.degree.
F. into smooth surfaced hemispherical shells which are then
positioned around the core in a mold having the desired inner cover
thickness and subjected to compression molding at 200.degree. to
300.degree. F. for about 2 to 10 minutes, followed by cooling at
50.degree. to 70.degree. F. for about 2 to 7 minutes to fuse the
shells together to form a unitary intermediate ball. In addition,
the intermediate balls may be produced by injection molding wherein
the inner cover layer is injected directly around the core placed
at the center of an intermediate ball mold for a period of time in
a mold temperature of from 50.degree. F. to about 100.degree. F.
Subsequently, the outer cover layer is molded about the core and
the inner layer by similar compression or injection molding
techniques to form a dimpled golf ball of a diameter of 1.680
inches or more.
[0095] After molding, the golf balls produced may undergo various
further processing steps such as buffing, painting and marking as
disclosed in U.S. Pat. No. 4,911,451.
[0096] The finished golf ball of the present invention possesses
the following general features:
[0097] Two-layer Ball:
[0098] A. Core (preferably a solid core)
[0099] 1. Weight, from about 30 to 42 grams, preferably, 35 to 38.5
grams, most preferably 35 to 37 grams.
[0100] 2. Size (diameter), 1.3 to 1.7 inches, more preferably from
about 1.45 to 1.60 inches, most preferably 1.52 to 1.57 inches.
[0101] 3. Specific gravity, from about 1.02 to 1.25, preferably
1.10 to 1.22, most preferably 1.15-1.20.
[0102] 4. Compression (Riehle), from about 50 to about 150,
preferably 70 to 120, most preferably 85-95.
[0103] 5. Coefficient of Restitution (C.O.R.), from about 0.750 to
about 0.820, preferably 0.760 to 0.805, most preferably 0.770 to
0.790.
[0104] B. Cover Layer and Core
[0105] 1. Weight, from about 44.0 to 45.9 grams, preferably, 44.8
to 45.7 grams, most preferably 45.4 to 45.6 grams.
[0106] 2. Size (diameter), from about 1.68 to 1.80 inches,
preferably, 1.68 to 1.74 inches, most preferably 1.68 to 1.72
inches.
[0107] 3. Cover Thickness (outer cover layer), from about 0.03 to
about 0.20 inches, preferably 0.05 to 0.10 inches, most preferably
0.06 to 0.07 inches.
[0108] 4. Compression (Riehle), from about 50 to about 120,
preferably 60 to 100, most preferably 70 to 80.
[0109] 5. Coefficient of Restitution (C.O.R.), from about 0.750 to
about 0.820, preferably 0.780 to 0.817, most preferably 0.805 to
0.812.
[0110] 6. Shore C/D Cover Hardness, from about 45/30 to about
97/72, preferably Shore D 65-75, most preferably Shore D 69-72.
[0111] 7. Moment of Inertia, from about 0.4 to about 0.5,
preferably 0.42 to 0.48, most preferably 0.45-0.47.
[0112] Multi-layer Ball:
[0113] A. Core (preferably a solid core)
[0114] 1. Weight, from about 30 to 42 grams, preferably, 35 to 38.5
grams, most preferably 35-37 grams.
[0115] 2. Size (diameter), from about 1.3 to 1.6 inches,
preferably, 1.35 to 1.58 inches, most preferably 1.54 to 1.58
inches.
[0116] 3. Specific gravity, from about 1.10-1.30, preferably 1.13
to 1.26, most preferably 1.16 -1.22.
[0117] 4. Compression (Riehle), from about 60 to about 1 60,
preferably 80 to 130, most preferably 90 to 120.
[0118] B. Inner Cover Layer (Mantle) and Core
[0119] 1. Weight, from about 26 to 43 grams, preferably, 29 to 40
grams, most preferably 36-40 grams.
[0120] 2. Size (diameter), from about 1.38 to 1.68 inches,
preferably, 1.50 to 1.67 inches, most preferably 1.55-1.59
inches.
[0121] 3. Thickness of inner cover layer, from about 0.01 to about
0.20 inches, preferably 0.025 to 0.125 inches, most preferably
0.04-0.08 inches.
[0122] 4. Specific gravity (inner cover layer only), from about
0.96 to 1.8, preferably 1.0 to 1.3, most preferably 1.05.
[0123] 5. Compression (Riehle), from about 55 to about 155,
preferably 75 to 125, most preferably 85-115.
[0124] 6. Shore C/D Inner Cover Hardness, from about 87/60 to about
> 100/100, preferably 92/65 to > 100/85, most preferably
Shore D 69-72.
[0125] C. Outer Cover Layer, Inner Cover Layer and Core
[0126] 1. Weight, from about 44.0 to 45.9 grams, preferably, 44.8
to 45.7 grams, most preferably 45.5 grams.
[0127] 2. Size (diameter), from about 1.680 to 1.80 inches,
preferably, 1.680 to 1.740 inches, most preferably 1.68-1.72
inches.
[0128] 3. Cover Thickness (outer cover layer), from about 0.02 to
about 0.20 inches, preferably 0.025 to 0.100, most preferably
0.04-0.07 inches.
[0129] 4. Compression (Riehle), from about 59 to about 160,
preferably 80 to 96, most preferably 76 to 85.
[0130] 5. Coefficient of Restitution (C.O.R.), from about 0.750 to
about 0.830, preferably 0.770 to 0.810, most preferably 0.780 to
0.810.
[0131] 6. Shore C/D Outer Cover Hardness, from about 35-20/92-65 to
about 40/25 to 90/60, more preferably Shore D 54-58.
[0132] 7. Moment of Inertia, from about 0.390 to about 0.480,
preferably 0.430 to 0.460, most preferably 0.44 to 0.45.
[0133] As used herein, the terms "Shore D hardness" and "Shore C
hardness" are measurements of golf ball cover hardness taken
generally in accordance with ASTM D-2240, with the exception that
all measurements are made on the curved surface of the cover of a
ball, rather than on a flat sample of cover material in the form of
a flat plaque. In these measurements, the golf ball is completely
intact with the cover in place surrounding the core. To make the
measurement of Shore hardness as uniform as possible, the
measurements are taken at "land" areas of a dimpled golf ball
cover, i.e., on portions of the cover between the dimples.
[0134] The present invention is further illustrated by the
following examples in which the parts of the specific ingredients
are by weight. It is to be understood that the present invention is
not limited to the examples, and various changes and modifications
may be made in the invention without departing from the spirit and
scope thereof.
EXAMPLE 1
[0135] A number of golf ball cores were made incorporating
tungsten, bismuth or molybdenum fillers, which are all high
specific gravity materials. Furthermore, a set of control cores was
made using zinc oxide. Tungsten has a specific gravity of 19.35,
bismuth has a specific gravity of 9.78, molybdenum has a specific
gravity of 10.2, and zinc oxide has a specific gravity of 5.57. The
core formulations are shown below on Table 1.
[0136] To estimate the relative distance each of the balls would
travel if they were covered with the same type of core, the Riehle
compression and coefficient of restitution (.times.1000) were added
together. The highest number is believed to represent the longest
ball. The tungsten-containing core is therefore believed to be the
longest, followed by the bismuth-containing core, the
molybdenum-containing core, and, lastly, the zinc oxide-containing
core. Thus, it appears that by replacing a portion of the zinc
oxide filler with a higher specific gravity filter, a more
efficient golf ball center can be formed.
2TABLE 1 Filled Golf Ball Cores 1-1 1-2 1-3 1-4 Cariflex BD-1220 70
70 70 70 Taktene 220 30 30 30 30 Zinc Oxide 31.5 6.0 6.0 6.0 T.G.
Regrind 16 16 16 16 Zinc Stearate 16 16 16 16 Zinc diacrylate (ZDA)
21.5 21.5 21.5 21.5 Tungsten Powder -- 20 -- -- Bismuth Powder --
-- 21 -- Molybdenum Powder -- -- -- 21 Luperco 231 XL peroxide 0.90
0.90 0.90 0.90 185.90 180.40 181.40 181.40 Size (in.) 1.496 1.496
1.496 1.496 Weight (g.) 34.6 34.4 34.3 34.3 Riehle Compression 107
116 116 116 COR (.times. 1000) 769 770 767 766 COR (.times. 1000) +
Riehle Comp. 876 886 883 882
EXAMPLE 2
[0137] A set of tungsten-containing golf ball cores was formed and
covered with an inner cover layer having a thickness of 0.050
inches, and a composition of 50 parts by weight Iotek 1002 and 50
parts by weight Iotek 1003. The inner cover layer was subsequently
covered with an outer cover layer having a thickness of 0.055
inches, and containing 42 parts by weight Iotek 7510, 42 parts by
weight Iotek 7520, 7.3 parts by weight Iotek 7030, 8.7 parts by
weight Iotek 8000, and a whitener package containing 2.3 parts by
weight of Unitane 0-110, 0.025 parts by weight Eastobrite OB1,
0.042 parts by weight Ultramarine Blue, and 0.004 parts by weight
Santanox R. The properties of the molded cores, glebared cores and
finished balls are shown on Table 2, along with the properties of
control balls which have the same type of inner and outer cover as
the tungsten-containing balls. The results show that the inclusion
of tungsten results in a slightly higher COR even if the ball has a
slightly softer compression. It is believed that the COR of the
tungsten ball would be even higher if the tungsten-containing ball
had the same Riehle compression as the control.
3TABLE 2 Tungsten-Containing Golf Balls v. Control Core (parts)
Control Tungsten Cariflex 70 70 Taktene 30 30 Zinc oxide 31.5 5.7
T.G. Regrind 16 16 Zinc stearate 16 16 ZDA 21.5 23.0 Tungsten --
20.0 Red Blue Luperco 231 XL peroxide 0.90 0.90 185.90 181.60
Molded Size (in) 1.493 1.492 Weight (g) 34.6 34.3 Comp (Riehle) 102
106 COR (.times. 1000) 773 779 Glebared Size (in) 1.469 1.469
Weight (g) 32.7 32.4 Comp (Riehle) 102 105 COR (.times. 1000) 771
777 Finished ball (avg 2 doz each) Size (in) 1.681 1.680 Weight (g)
45.45 45.28 Comp (Riehle) 82 84 COR (.times. 1000) 786 790 Selected
for Distance Testing Size (in) 1.681 1.680 Weight (gi 45.38 45.33
Comp (Riehle) 82 83 COR (.times. 1000) 786 789
EXAMPLE 3
[0138] A number of two-layer balls were formed containing tungsten
in the core and containing high quantities of titanium in the form
of titanium dioxide in the cover layer. The composition and
properties of the golf balls are shown below on Table 3.
[0139] The invention has been described with reference to the
preferred embodiment. Obviously, modifications and alterations will
occur to others upon reading and understanding the proceeding
detailed description. It is intended that the invention be
construed as including all such modifications and alterations
insofar as they come within the scope of the appended claims or the
equivalents thereof.
4TABLE 3 Titanium-Tungsten Golf Balls Materials Flex Modulus PHR
PHR Cariflex 1220 70 70 Taktene 220 30 30 Zinc Oxide 21.91 21.91 TG
Regrind 20 20 Zinc Stearate 20 20 ZDA 24 24 Tungsten Powder 0.35
0.35 Disco Red Masterbatch 0.2 0 (MB) Green MB 0 0.16 Blue MB 0
0.16 Luperco 231 XL (perox.) 0.9 0.9 Core Data Size (in.) 1.545
1.545 Weight (g.) 36.5 36.5 Riehle Comp. 90 90 COR 780 780 COVER
DETAILS lotek 1002 (18%, Na) 380 MPa 29.73 29.73 lotek 1003 (18%,
Zn) 147 MPa 55.26 55.26 lotek 7030 (15%, Zn) 155 MPa 15.01 15.01
Titanium Dioxide 4.76 4.76 Ultramarine Blue 0.0921 0.0921
Eastobrite OB-1 0.0262 0.0262 Santonox R 0.0076 0.0076 Blend
Modulus (Wgt Avg) 217 MPa 217 MPa Blend % Acid (Wgt Avg) 17.6%
17.6% Thickness (in.) 0.0675 0.0675 Shore C/D hardness 97/71 97/71
Ball Data Size (in.) 1.68 1.68 Weight (g.) 45.5 45.5 Riehle Comp.
76 76 COR 810 810
* * * * *