Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02283788 1999-09-09
WO 98/43709 PCTIUS98I06159
NOVEL DUAL CORES FOR GOLF BALLS
Cross References to Related Ar~plications
. This application is a continuation-in-part of
U.S. Application Serial No. 08/926,872 filed on
September 10, 1997, which is a divisional of U.S.
Application Serial No. 08/631,613 filed on April 10,
1996, which in turn is a continuation-in-part of U.S.
Application Serial No. 08/591,046 filed on January 25,
1996, and U.S. Application Serial No. 08/542,793 filed
on October 13, 1995, which in turn is a continuation-in-
part of U.S. Application 08/070,510 filed June 1, 1993.
This application is also a continuation-in-part of U.S.
Application Serial No. 08/870,585 filed on June 6, 1997,
which is a continuation of U.S. Application Serial No.
08/556,237 filed on November 9, 1995, which is a
continuation-in-part of U.S. Application Serial No.
08/542,793 filed October 13, 1995, which is a
continuation-in-part of U.S. Application Serial No.
08/070,510 filed on June 1, 1993. This application also
claims priority on U.S. provisional patent Application
Serial No. 60/042,439 filed March 28, 1997.
Field of the Invention
The present invention relates to golf balls
and, more particularly, to improved gold balls
comprising multi-layer covers which have a comparatively
hard inner layer and a relatively soft outer layer, and
a unique dual core configuration. The improved multi-
layer golf balls provide for enhanced distance and
durability properties over single layer cover golf balls
while at the same time offering enhanced ~~feel~~ and spin
characteristics generally associated with soft balata
and balata-like covers of the prior art.
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98143709 PCT/US98/06159
- 2 -
Background of the Invention
Traditional golf ball covers have been
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 a 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. 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.
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.
As a result of this negative property, balata
and its synthetic substitutes, transpolybutadiene and
transpolyisoprene, have been essentially replaced as the
cover materials of choice by new cover materials
comprising ionomeric resins.
Ionomeric resins are polymers containing
interchain ionic bonding. 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~" and more
recently, by the Exxon Corporation (see U.S. Patent No.
4,911,451) under the trademarks "ESCORT" and the trade
name "Iotek," have become the materials of choice for
the construction of golf ball covers over the
traditional "balata" (transpolyisoprene, natural or
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCTIUS98/06159
- 3 -
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
. 5 for repetitive play.
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 malefic 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. However, some of the
advantages gained in increased durability have been
offset to some degree by the decreases produced in
playability. This is because although the ionomeric
resins are very durable, they tend to be very hard when
utilized for golf ball cover construction, and thus lack
the degree of softness required to impart the spin
necessary to control the ball in flight. Since the
ionomeric resins are harder than balata, the ionomeric
resin covers do not compress as much against the face of
the club upon impact, thereby producing less spin. In
addition, the harder and more durable ionomeric resins
lack the "feel" characteristic associated with the
softer balata related covers.
As a result, while 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., a great
deal of research continues in order to develop a golf
ball cover composition exhibiting not only the improved
SUBSTITUTE SHEET (RULE 26)
i
CA 02283788 1999-09-09
WO 98/43709 PCTIUS98/06159
- 4 -
impact resistance and carrying distance properties
produced by the "hare" 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.
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 to address these needs. the different
types of materials utilized to formulate the cores,
coves, etc. of these balls dramatically alters the
balls' overall characteristics. In addition, multi-
layered covers containing one or more ionomer resins
' have also been formulated in an attempt to produce a
golf ball having the overall distance, playability and
durability characteristics desired.
This was addressed by Spalding & Evenflo
Companies, Inc., the assignee of the present invention,
in U.S. Patent No. 4,431,193 where a multi-layered golf
ball is produced by initially molding a first cover
layer on a spherical core and then adding a second
layer. The first layer is comprised of a hard, high
flexural modules resinous material such as type 1605
Surlyn~ (now designated Surlyn~ 8940). type 1605 Surlyn
(Surlyn~ 8940) is a sodium ion based low acid (less than
or equal to 15 weight percent methacrylic acid) ionomer
resin having a flexural modules of about 51,000 psi. An
outer layer o.~ a comparatively soft, low flexural
modules resinous material such as type 1855 Surlyn° (now
designated Surlyn° 9020) is molded over the inner cover
layer. Type 1855 Surlyn~ (Surlyn~ 9020) is a zinc ion
based low acid (10 weight percent methacrylic acid)
ionomer resin having a flexural modules of about 14,000
psi.
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCTlUS98/06159
The '193 patent teaches that the hard, high
flexural modulus resin which comprises the first layer
provides for a gain in coefficient of restitution over
the coefficient of restitution of the core. The
increase in the coefficient of restitution provides a
ball which serves to attain or approach the maximum
initial velocity limit of 255 feet per second as
provided by the United States Golf Association
(U.S.G.A.) rules. The relatively soft, low flexural
modulus outer layer provides for the advantageous "feel"
and playing characteristics of a balata covered golf
ball.
In various attempts to produce a durable, high
spin ionomer golf ball, the golfing industry has blended
the hard ionomer resins with a number of softer
ionomeric resins. U.S. Patent Nos. 4884,814 and
5,120,791 are directed to cover compositions containing
blends of hard and soft ionomeric resins. The hard
copolymers typically are made from an olefin and an
unsaturated carboxylic acid. The soft copolymers are
generally made from an olefin, an unsaturated carboxylic
acid, and an acrylate ester. It has been found that
golf ball covers formed from hard=soft ionomer blends
tend to become scuffed more readily than covers made of
hard ionomer alone. It would be useful to develop a
golf bail having a combination of softness and
durability which is better than the softness-durability
combination of a golf ball cover made from a hard-soft
ionomer blend.
3o Most professional golfers and good amateur
golfers desire a golf ball that provides distance when
hit off a driver, control and stopping ability on full
iron shots, and high spin on short "touch and feel"
shots. Many conventional two-piece and thread wound
performance golf balls have undesirable high spin rates
on full shots. The excessive spin on full shots is a
sacrifice made in order to achieve more spin which is
SUBSTITUTE SHEET (RULE 2B)
I
CA 02283788 1999-09-09
WO 98143709 PCTIUS98106159
- 6 -
desired on the shorter touch shots. It would be
beneficial to provide a golf ball which has high spin
for touch shots without generating excessive spin or
full shots.
These and other objects and features of the
invention will be apparent from the following summary
and description of the invention, the drawings and from
the claims.
Summary of the Invention
In one aspect, the present invention provides
a golf ball comprising a dual core comprising a center
component and a core layer disposed about the center
component. The golf ball further comprises an inner
cover layer molded on the inner cover layer. The inner
cover layer is formed from a high acid ionomer including
at least 16% by weight of an alpha, beta-unsaturated
carboxylic acid. The outer cover layer is formed from a
relatively soft polymeric material such as low flexural
modulus ionomer resins and non-ionomeric thermoplastic
elastomers.
In yet another aspect, the present invention
provides a multi-layer golf ball comprising a dual core
component that includes an interior spherical center
component and a core layer disposed about the spherical
center component. The golf ball further comprises an
inner cover layer molded over the core layer of the dual
core, and an outer cover layer molded over the inner
cover layer. The inner and outer cover layers have
particular properties. The inner cover layer comprises
an ionomeric resin including at least 15% by weight of
an alpha, beta-unsaturated carboxylic acid and has a
modulus of from about 15,000 to about 70,000 psi. The
outer cover layer comprises a blend of a sodium or zinc
salt of a particular copolymer and a particular
unsaturated monocarboxylic acid, and a sodium or zinc
salt of a certain terpolymer, acrylic acid and a
SUBSTITUTE SHEET (RULE 25~
CA 02283788 1999-09-09
WO 98143709 PC"TIUS98/06159
particular unsaturated monomer of the acrylate ester
class. The outer cover layer has a modules of from
about 1,000 to about 30,000 psi.
In yet another embodiment, the present
invention provides a mufti-layer golf ball comprising a
spherical dual core, an inner cover layer molded over
the dual core, and an outer cover layer molded over the
inner cover layer. The inner cover layer comprises an
ionomeric resin including 17% to 25% of an alpha, beta-
unsaturated carboxylic acid, and has a modules of from
about 15,000 to about 70,000 psi. The outer cover layer
comprises a non-ionomeric thermoplastic selected from
the group consisting of polyester elastomer, polyester
urethane, and polyester amide. The outer cover layer
has a modules in the range of 1,000 to 30,000 psi.
In a further aspect, the present invention
also provides a golf ball comprising a dual core, an
inner cover layer molded on the dual core, an outer
cover layer molded on the inner cover layer, and at
least one outer core layer disposed about the dual core.
The inner cover layer comprises a high acid ionomer
including at least 16% of an alpha, beta-unsaturated
carboxylic acid. The outer cover layer comprises a
relatively soft polymeric material of low flexural
modules ionomer resins and non-ionomeric thermoplastic
elastomers.
In yet another aspect, the present invention
provides a mufti-layer golf ball comprising a spherical
dual core including an interior spherical center and a
core layer disposed about the center. The golf ball
further comprises an inner cover layer molded over the
spherical dual core, an outer cover layer molded aver
the inner cover layer, and at least one inner core layer
disposed between the dual core and the inner cover
layer. The inner cover layer comprises an ionomeric
resin including at least 16% of an alpha, beta-
unsaturated carboxylic acid, and has a modules of from
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06I59
_ g _
15,000 to 70,000 psi. The outer cover layer comprises a
particular blend of a sodium or zinc salt of a certain
copolymer and a sodium or zinc salt of a terpolymer.
The outer cover layer has a modulus of 1,000 to 30,000
psi.
Moreover, the present invention provides a
mufti-layer golf ball comprising a dual core component,
an inner cover molded over the dual core, an outer core
layer molded over the inner cover, and at least one
outer core layer disposed between the dual core and the
inner cover layer. The inner cover layer comprises an
ionomeric resin including 17% to 25% of an alpha, beta-
unsaturated carboxylic acid and has a modulus of 15,000
to 70,000 psi. The outer cover layer comprises a non-
ionomeric thermoplastic of a polyester elastomer, a
polyester polyurethane and a polyester amide. The outer
cover has a modulus in the range of 1,000 to 3,000 psi.
Brief Description of the Drawings
FIGURE 1 is a cross-sectional view of a
preferred embodiment golf ball in accordance with the
present invention illustrating a core and a cover
comprising an inner layer and an outer dimpled layer;
FIGURE 2 is a diametrical cross-sectional view
of the preferred embodiment golf ball depicted in FIGURE
1 having a core and a cover comprising an inner layer
surrounding the core and an outer layer having a
plurality of dimples;
FIGURE 3 is a cross-sectional view of another
preferred embodiment golf ball in accordance with the
present invention comprising a dual core component;
FIGURE 4 is a cross-sectional view of yet
another preferred embodiment golf ball in accordance
with the present invention comprising a dual core
component;
FIGURE 5 is a cross-sectional view of another
preferred embodiment golf ball in accordance with the
SU85T1TUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 9 _
present invention comprising a dual core component and
an outer cover layer;
FIGURE 6 is a cross-sectional view of yet
another preferred embodiment golf ball in accordance
with the present invention comprising a dual core
component and an outer core layer; and
FIGURE 7 is a schematic view of an assembly
used for molding a preferred embodiment golf ball in
accordance with the present invention.
Detailed Description of the
Preferred Embodim nts
The present invention is directed to a golf
ball comprising a dual-core component and a multi-layer
cover. The novel multi-layer golf ball covers of the
present invention include a first or inner layer or ply
of a high acid (greater than 16 weight percent acid)
ionomer blend or, more preferably, a low acid (16 weight
percent acid or less) ionomer blend and second or outer
layer or ply comprised of a comparatively softer, low
modulus ionomer, ionomer blend or other non-ionomeric
thermoplastic or thermosetting elastomer such as
polyurethane or polyester elastomer. The multi-layer
golf balls of the present invention can be of standard
or enlarged size. Preferably, the inner layer or ply
includes a blend of low acid ionomers and has a Shore D
hardness of 70 or greater and the outer cover layer
comprised of polyurethane and has a Shore D hardness of
about 45 (i.e., Shore C hardness of about 65).
The present invention golf balls utilize a
unique dual-core configuration. Preferably, the cores
comprise (i) an interior spherical center component
' formed from a thermoset material, a thermoplastic
material, or combinations thereof; and (ii) a core layer
disposed about the spherical center component, the core
layer formed from a thermoset material, a thermoplastic
material, or combinations thereof. The cores may
SUBSTITUTE SHEET (RULE 28)
i
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 10 -
further comprise (iii) an optional outer core layer
disposed about the core layer. The outer core layer may
be formed from a thermoset material, a thermoplastic
material, or combinations thereof.
Although the present invention is primarily
directed to golf balls comprising a dual core component
and a multi-layer cover as described herein, the present
invention also includes golf balls having a dual core
component and conventional covers comprising balata,
various thermoplastic materials, cast polyurethanes, or
any other known cover materials.
It has been found that multi-layer golf balls
having inner and outer cover layers exhibit higher
C.O.R. values and have greater travel distance in
comparison with balls made from a single cover layer.
In addition, it has been found that use of an inner
cover layer constructed of a blend of low acid (i.e., 16
weight percent acid or less) ionomer resins produces
softer compression and higher spin rates than inner
cover layers constructed of high acid ionomer resins.
This is compounded by the fact that the softer
polyurethane outer layer adds to the desirable ~~feel«
and high spin rate while maintaining respectable
resilience. The soft outer layer allows the cover to
deform more during impact and increases the area of
contact between the club face and the cover, thereby
imparting more spin on the ball. As a result, the soft
polyurethane cover provides the ball with a balata-like
feel and playability characteristics with improved
distance and durability.
Consequently, the overall combination of the
unique dual core configuration, described in greater
detail herein, and the multi-layer cover construction of
inner and outer cover layers made, for example, from
blends of low acid ionomer resins and polyurethane
results in a standard size or oversized golf ball having
enhanced resilience (improved travel distance) and
sues-rrrurE sHe~ cRU~ zs~
CA 02283788 1999-09-09
WO 98/43709 PCTIUS98/06159
- 11 -
durability (i.e. cut resistance, etc.) characteristics
while maintaining and in many instances, improving the
ball's playability properties..
The combination of a low acid ionomer blend
inner cover layer with a soft, relatively low modulus
ionomer, polyurethane based elastomer outer cover layer
provides for good overall coefficient of restitution
(i.e., enhanced resilience) while at the same time
demonstrating improved compression and spin. The outer
cover layer generally contributes to a more desirable
feel and spin, particularly at lower swing speeds with
highly lofted clubs such as half wedge shots.
Accordingly, the present invention is directed
to a golf ball comprising a dual-core configuration and
an improved mufti-layer cover which produces, upon
molding each layer around a core to formulate a multi-
layer cover, a golf ball exhibiting enhanced distance
(i.e., resilience) without adversely affecting, and in
many instances, improving the ball's playability
(hardness/softness) and/or durability (i.e., cut
resistance, fatigue resistance, etc.) characteristics.
Figures 1 and 2 illustrate a preferred
embodiment golf ball 5 in accordance with the present
invention. It will be understood that none of the
referenced figures are to scale. And so, the
thicknesses and proportions of the various layers and
the diameter of the various core components are not
necessarily as depicted. The golf ball 5 comprises a
mufti-layered cover 12 disposed about a core 10. The
core 10 of the golf ball can be formed of a solid, a
liquid, or any other substances that may be utilized to
form the novel dual core described herein. The mufti-
layered cover 12 comprises two layers: a first or inner
layer or ply 14 and a second or outer layer or ply 16.
The inner layer 14 can be ionomer, ionomer blends, non-
ionomer, non-ionomer blends, or blends of ionomer and
non-ionomer. The outer layer 16 is softer than the
SUBSTITUTE SHEET (RULE 26)
I
CA 02283788 1999-09-09
WO 98/43709 PGT/US98/06159
- 12 -
inner layer and can be ionomer, ionomer blends, non-
ionomer, non-ionomer blends or blends of ionomer and
non-ionomer.
In a first preferred embodiment, the inner
layer 14 is comprised of a high acid (i.e. greater than
16 weight percent acid) ionomer resin or high acid
ionomer blend. Preferably, the inner layer is comprised
of a blend of two or more high acid (i.e., at least 16
weight percent acid) ionomer resins neutralized to
various extents by different metal cations. The inner
cover layer may or may not include a metal stearate
(e. g., zinc stearate) or other metal fatty acid salt.
The purpose of the metal stearate or other metal fatty
acid salt is to lower the cost of production without
affecting the overall performance of the finished golf
ball. In a second embodiment, the inner layer 14 is
comprised of a low acid (i.e., 16 weight percent acid or
less) ionomer blend. Preferably, the inner layer is
comprised of a blend of two or more low acid (i.e., 16
weight percent acid or less) ionomer resins neutralized
to various extents by different metal cations. The
inner cover layer may or may not include a metal
stearate (e. g., zinc stearate) or other metal fatty acid
salt. The purpose of the metal stearate or other metal
fatty acid salt is to lower the cost of production
without affecting the overall performance of the
finished golf ball.
Two principal properties involved in golf ball
performance are resilience and hardness. Resilience is
determined by the coefficient of restitution (C.O.R.),
the constant "e" which is the ratio of the relative
velocity of two elastic spheres after direct impact to _
that before impact. As a result, the coefficient of
restitution ("e") can vary from 0 to 1, with 1 being
equivalent to an elastic collision and 0 being
equivalent to an inelastic collision.
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98!43709 PCTNS98106159
- 13 -
Resilience (C.O.R.), along with additional
factors such as club head speed, angle of trajectory and
ball configuration (i.e., dimple pattern) generally
determine the distance a ball will travel when hit.
Since club head speed and the angle of trajectory are
factors not easily controllable by a manufacturer,
factors of concern among manufacturers are the
coefficient of restitution (C.O.R.) and the surface
configuration of the ball.
The coefficient of restitution (C.O.R.) in
solid core balls is a function of the composition of the
molded core and of the cover. In balls containing a
dual core (i.e., balls comprising an interior spherical
center component, a core layer disposed about the
spherical center component, and a cover), the
coefficient of restitution is a function of not only the
composition of the cover, but also the composition and
physical characteristics of the interior spherical
center component and core layer. Both the dual core and
the cover contribute to the coefficient of restitution
in the golf balls of the present invention.
In this regard, the coefficient of restitution
of a golf ball is generally measured by propelling a
ball at a given speed against a hard surface and
measuring the ball's incoming and outgoing velocity
electronically. As mentioned above, the coefficient of
restitution is the ratio of the outgoing velocity to the
incoming velocity. The coefficient of restitution must
be carefully controlled in all commercial golf balls in
order for the ball to be within the specifications
regulated by the United States Golf Association
(U.S.G.A.) Along this line, the U.S.G.A. standards
indicate that a ~~regulation~~ ball cannot have an initial
velocity (i.e., the speed off the club) exceeding 255
feet per second. 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
SUBSTITUTE SHEET tRULE 26)
i
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06I59
- 14 -
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.).
The hardness of the ball is the second
principal property involved in the performance of a golf
ball. The hardness of the ball can affect the
playability of the ball on striking and the sound or
"click" produced. Hardness is determined by the
deformation (i.e., compression) of the ball under
various load conditions applied across the ball's
diameter (i.e., the lower the compression value, the
harder the material). As indicated in U.S. Patent No.
4,674,751, softer covers permit the accomplished golfer
to impart proper spin. This is because the softer
covers deform on impact significantly more than balls
having "harder" ionomeric resin covers. As a result,
the better player is allowed to impart fade, draw or
backspin to the ball thereby enhancing playability.
Such properties may be determined by various spin rate
tests.
It has been found that a hard inner layer
provides for a substantial increase in resilience (i.e.,
enhanced distance? over known multi-layer covered balls.
The softer outer layer provides for desirable "feel" and
high spin rate while maintaining respectable resiliency.
The soft outer layer allows the cover to deform more
during impact and increases the area of contact between
the club face and the cover, thereby imparting more spin
on the ball. As a result, the soft cover provides the
ball with a balata-like feel and playability
characteristics with improved distance and durability.
Consequently, the overall combination of the inner and
outer cover layers results in a golf ball having
enhanced resilience (improved travel distance) and
durability (i.e., cut resistance, etc.) characteristics
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCTIUS98/06159
- 15 -
while maintaining and in many instances, improving the
playability properties of the ball.
. The combination of a hard inner cover layer
with a soft, relatively low modulus ionomer, ionomer
blend or other non-ionomeric thermoplastic elastomer
outer cover layer provides for excellent overall
coefficient of restitution (i.e., excellent resilience)
because of the improved resiliency produced by the inner
cover layer. While some improvement in resiliency is
also produced by the outer cover layer, the outer cover
layer generally provides for a more desirable feel and
high spin, particularly at lower swing speeds with
highly lofted clubs such as half wedge shots.
Inner Cover Layer
The inner cover layer is harder than the outer
cover layer and generally has a thickness in the range
of 0.01 to 0.10 inches, preferably 0.03 to 0.07 inches
for a 1.68 inch ball and 0.05 to 0.10 inches for a 1.72
inch (or more) ball. The core and inner cover layer
together form an inner ball having a coefficient of
restitution of 0.780 or more and more preferably 0.790
or more, and a diameter in the range of 1.48 - 1.66
inches for a 1.68 inch ball and 1.50 - 1.70 inches for a
1.72 inch (or more) ball. The inner cover layer has a
Shore D hardness of 60 or more. It is particularly
advantageous if the golf balls of the invention have an
inner layer with a Shore D hardness of 65 or more. The
above-described characteristics of the inner cover layer
provide an in~qer ball having a PGA compression of 100 or
less. It is found that when the inner ball has a PGA
compression of 90 or less, excellent playability
results.
The inner layer compositions include the high
acid ionomers such as those developed by E.I. DuPont de
Nemours & Company under the trademark "Surlyn~" and by
Exxon Corporation under the trademark "Escor~" or trade
suesTrrurE sHEEr tAU~ 2s~
i
CA 02283788 1999-09-09
WO 98/43709 PCTlUS98/06159
- 16 -
name "Iotek", or blends thereof. Examples of
compositions which may be used as the inner layer herein
are set forth in detail in a continuation of U.S.
Application Serial No. 08/174,765, which is a
continuation of U.S. Application Serial No. 07/776,803
filed October 15, 1991, and Serial No. 08/493,089, which
is a continuation of 07/981,751, which in turn is a
continuation of Serial No. 07/901,660 filed June 19,
1992, all of which are incorporated herein by reference.
Of course, the inner layer high acid ionomer
compositions are not limited in any way to those
compositions set forth in said applications.
The high acid ionomers which may be suitable
for use in formulating the inner layer compositions are
ionic copolymers which are the metal, i.e., sodium,
zinc, magnesium, etc., salts of the reaction product of
an olefin having from about 2 to 8 carbon atoms and an
unsaturated monocarboxylic acid having from about 3 to 8
carbon atoms. Preferably, the ionomeric resins are
copolymers of ethylene and either acrylic or methacrylic
acid. In some circumstances, an additional comonomer
such as an acrylate ester (i.e., iso- or n-
butylacrylate, etc.) can also be included to produce a
softer terpolymer. The carboxylic acid groups of the
copolymer are partially neutralized (i.e., approximately
10-100%, preferably 30-70s) by the metal ions. Each of
the high acid ionomer resins which may be included in
the inner layer cover compositions of the invention
contains greater than about 16% by weight of a
carboxylic acid, preferably from about 17% to about 250
by weight of a carboxylic acid, more preferably from
about 18.5% to about 21.5% by weight of a carboxylic
acid.
Although the inner layer cover composition of
several embodiments of the present invention preferably
includes a high acid ionomeric resin, the scope of the
patent embraces all known high acid ionomeric resins
SU9STITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PGT/US98/06l59
- 17 -
falling within the parameters set forth above, only a
relatively limited number of these high acid ionomeric
resins have recently become commercially available.
The high acid ionomeric resins available from
Exxon under the designation "Escor~" and or "Iotek", are
somewhat similar to the high acid ionomeric resins
available under the "Surlyn°" trademark. However, since
the Escor~/Iotek ionomeric resins are sodium or zinc
salts of polyethylene-acrylic acid? and the "Surlyn~"
l0 resins are zinc, sodium, magnesium, etc. salts of
polyethylene-methacrylic acid), distinct differences in
properties exist.
Examples of the high acid methacrylic acid
based ionomers found suitable for use in accordance with
this invention include Surlyn~8220 and 8240 (both
formerly known as forms of Surlyn AD-8422), Surlyn°9220
(zinc canon), Surlyn°SEP-503-1 (zinc cation), and
Surlyn~SEP-503-2 (magnesium cation). According to
DuPont, all of these ionomers contain from about 18.5 to
about 21.5% by weight methacrylic acid.
More particularly, Surlyn~ AD-8422 is
currently commercially available from DuPont in a number
of different grades (i.e., AD-8422-2, AD-8422-3, AD-
8422-5, etc.) based upon differences in melt index.
According to DuPont, Surlyn~ 8422, which is believed
recently to have been redesignated as 8220 and 8240,
offers the following general properties when compared to
Surlyn~ 8920, the stiffest, hardest of all on the low
acid grades (referred to as "hard" ionomers in U.S.
Patent No. 4,884,814?:
suesmu~ sHE~ ~RU~ zs~
I
CA 02283788 1999-09-09
WO 98143709 PC'T/US98/06159
- 18 -
LOW ACID HIGH ACID
(15 wt% Acid) (>20 wt% Acid}
SURLYN~ SURLYN~ SURLYN~
8920 8422-2 8422-3
IONOMER
Cation Na Na Na
Melt Index 1.2 2.8 1.0
Sodium, Wt% 2.3 1.9 2.4
Base Resin MI 60 60 60
MP1, C 88 86 85
FPl, C 47 48.5 45
COMPRESSION MOLDING
Tensile Break,
psi 4350 4190 5330
Yield, psi 2880 3670 3590
Elongation, s 315 263 2gg
Flex Mod,
K psi 53.2 76.4 88
3
Shore D .
hardness 66 67 68
1 DSC second heat, 10°C/min heating rate.
2 Samples compression molded at 150°C annealed 24
hours at 60°C. 8422-2, -3 were homogenized at
190°C before molding.
In comparing Surlyn~ 8920 to Surlyn~ 8422-2
and Surlyn~ 8422-3, it is noted that the high acid
Surlyn~ 8422-2 and 8422-3 ionomers have a higher tensile
yield, lower elongation, slightly higher Shore D
hardness and much higher flexural modulus. Surlyn~ 8920
contains 15 weight percent methacrylic acid and is 590
neutralized with sodium.
In addition, Surlyn~SEP-503-1 (zinc cation)
and SurlynoSEP-503-2 (magnesium cation) are high acid
zinc and magnesium versions of the Surlyn~AD 8422 high
acid ionomers. When compared to the Surlyn° AD 8422
high acid ionomers, the Surlyn~ SEP-503-1 and SEP-503-2
ionomers can be defined as follows:
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98143709 PCT/US98106159
- 19 -
Surlvn~ Ionomer Ion Melt Index Neutralization
AD 8422-3 Na 1.0 45
~ SEP 503-1 Zn 0.8 38
SEP 503-2 Mg 1.8 43
Further, Surlyn~ 8162 is a zinc cation ionomer
resin containing approximately 20% by weight (i.e., 18.5
- 21.5% weight) methacrylic acid copolymer that has been
30 - 70% neutralized. Surlyn° 8162 is currently
commercially available from DuPont.
Examples of the high acid acrylic acid based
ionomers suitable for use in the present invention also
include the Escor~ or Iotek high acid ethylene acrylic
acid ionomers produced by Exxon such as Ex 1001, 1002,
959, 960, 989, 990, 1003, 1004, 993, 994. In this
regard, Escor~ or Iotek 959 is a sodium ion neutralized
ethylene-acrylic neutralized ethylene-acrylic acid
copolymer. According to Exxon, Ioteks 959 and 960
contain from about 19.0 to 21.0% by weight acrylic acid
with approximately 30 to about 70 percent of the acid
groups neutralized with sodium and zinc ions,
respectively. The physical properties of these high
acid acrylic acid based ionomers are set forth in Tables
1 and 2 as follows:
SUBSTITUTE SHEET (RULE 26)
ICA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 20 -
TABLE 1
Physical Prop erties VariousIonomers
of
ESCOR ESCOR's -
(IOTEK) (IOTEK)
PROPERTY Ex1001 959 Ex1003
Ex1002
Ex1004 960
Melt index,
g/10 min 1.0 1.6 2.0 1.1 2.0 1.8
Cation Na Na Na Zn Zn Zn
Melting
Point, F 183 183 172 180 180.5 174
Vicat
Softening
Point, F 125 125 130 133 131 131
Tensile 34.9 22.5 4600 29.8 20.6 3500
~ Break MPa MPa psi MPa MPa psi
Elongation
15 i~ Hreak, % 348 325 387 437 430
341
Hardness,
Shore D 63 62 66 54 53 57
Flexural 365 38D 66,D00 147 130 27
000
Modulus MPa MPa psi MPa MPa ,
i
ps
20 TABLE 2
Physical Prop erties VariousIonomers
of
EX 989 EX 993 EX 994 EX 990
Melt index g/10 min 1.30 1.25 1.32 1.24
Moisture ppm 482 214 997 654
Cation type - Na Li K Zn
2 M+ content by wt% 2.74 0.87 4.54 0
AAS
Zn content by wt% 0 0 0 3.16
AAS
Density kg/m= 959 945 976 977
Vicat softeningC 52.5 51 50 55.0
point
CrystallizationC 40.2 39.8 44.9 54.4
point
Melting point C 82.6 81.0 80.4 81.D
Tensile at yieldMPa 23.8 24.6 22 16.5
Tensile at breakMPa 32.3 31.1 29.7 23.8
Elongation at % 330 260 340
break
357
1% secant modulusMPa 389 379 312 205
3 Flexural modulusMPa 340 368 303 183 '
5
Abrasion resistancemg 20.0 9.2 15.2 2D.5
Hardness Shore - 62 62.5 61 56
D
Zwick Rebound % 61 63 59 48
Fur thermore, as a resu lt of
the
development
by
40 the assignee of this pplicationof a new high
a number
of
SUBSTITUTE SHEET (RULE 25)
CA 02283788 1999-09-09
WO 98/43709 PC"f/US98/06159
- 21 -
acid ionomers neutralized to various extents by several
different types of metal cations, such as by manganese,
lithium, potassium, calcium and nickel cations, several
new high acid ionomers and/or high acid ionomer blends
besides sodium, zinc and magnesium high acid ionomers or
ionomer blends are now available for golf ball cover
production. It has been found that these new cation
neutralized high acid ionomer blends produce inner cover
layer compositions exhibiting enhanced hardness and
resilience due to synergies which occur during
processing. Consequently, the metal cation neutralized
high acid ionomer resins recently produced can be
blended to produce substantially higher C.O.R.'s than
those produced by the low acid ionomer inner cover
compositions presently commercially available.
More particularly, several new metal cation
neutralized high acid ionomer resins have been produced
by the inventor by neutralizing, to various extends,
high acid copolymers of an alpha-olefin and an alpha,
beta-unsaturated carboxylic acid with a wide variety of
different metal cation salts. This discovery is the
subject matter of U.S. Application Serial No.
08/493,089, incorporated herein by reference. It has
been found that numerous new metal cation neutralized
high acid ionomer resins can be obtained by reacting a
high acid copolymer (i.e., a copolymer containing
greater than 16% by weight acid, preferably from about
17 to about 25 weight percent acid, and more preferably
about 20 weight percent acid), with a metal cation salt
capable of ionizing or neutralizing the copolymer to the
extent desired (i.e., from about 10% to 90%).
The base copolymer is made up of greater than
16% by weight of an alpha, beta-unsaturated carboxylic
acid and an alpha-olefin. Optionally, a softening
comonomer can be included in the copolymer. Generally,
the alpha-olefin has from 2 to l0 carbon atoms and is
preferably ethylene, and the unsaturated carboxylic acid
SUBSTITUTE SHEET (RULE 26)
I
CA 02283788 1999-09-09
WO 98/43709 PCTIUS98/06159
- 22 -
is a carboxylic acid having from about 3 to 8 carbons.
Examples of such acids include acrylic acid, methacrylic
acid, ethacrylic acid, chloroacrylic acid, crotonic
acid, malefic acid, fumaric acid, and itaconic acid, with
acrylic acid being preferred.
The softening comonomer that can be optionally
included in the inner cover layer for the golf ball of
the invention may be selected from the group consisting
of vinyl esters of aliphatic carboxylic acids wherein
the acids have 2 to 10 carb/n atoms, vinyl ethers
wherein the alkyl groups contains 1 to 10 carbon atoms,
and alkyl acrylates or methacrylates wherein the alkyl
group contains 1 to 10 carbon atoms. Suitable softening
comonomers include vinyl acetate, methyl acrylate,
methyl methacrylate, ethyl acrylate, ethyl methacrylate,
butyl acrylate, butyl methacrylate, or the like.
Consequently, examples of a number of
copolymers suitable for use to produce the high acid
ionomers included in the present invention include, but
are not limited to, high acid embodiments of an
ethylene/acrylic acid copolymer, an ethylene/methacrylic
acid copolymer, an ethylene/itaconic acid copolymer, an
ethylene/maleic acid copolymer, an ethylene/methacrylic
acid/vinyl acetate copolymer, an ethylene/acrylic
acid/vinyl alcohol copolymer, etc. The base copolymer
broadly contains greater than 16o by weight unsaturated
carboxylic acid, from about 39 to about 83% by weight
ethylene and from 0 to about 40% by weight of a
softening comonomer. Preferably, the copolymer contains
about 20% by fight unsaturated carboxylic acid and
about 80o by weight ethylene. Most preferably, the
copolymer contains about 20% acrylic acid with the
remainder being ethylene.
Along these lines, examples of the preferred
high acid base copolymers which fulfill the criteria set
forth above, are a series of ethylene-acrylic copolymers
which are commercially available from The Dow Chemical
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCTIUS98/06159
- 23 -
Company, Midland, Michigan, under the ~~Primacor~~
designation. These high acid base copolymers exhibit
the typical properties set forth below in Table 3.
TABLE 3
Tvoical Properties of Primacor
Ethylene-Acrylic Acid Copolymers
GRADE PERCENT DENSITY MELT TENSILE FLEXURA VICAT SHORE D
ACID , glcc INDEX, YD. ST L SOFT PT HARDNES
g/lOmin (psi) MODULUS (°C)
(psi)
ASTM D-792 D-1238 D-638 D-790 D-1525 D-2240
5980 20.0 0.958 300.0 - 4800 43 50
1 ~ 5990 20.0 0.955 1300.0 650 2600 40 42
5990 20.0 0.955 1300.0 650 3200 4p 4'
5981 20.0 0.960 300.0 900 3200 46 48
5981 20.0 0.960 300.0 900 3200 46 48
5983 20.0 0.958 500.0 850 3100 44 45
1 5 5991 20.0 0.953 2600.0 635 2600 38 40
'The Melt Index values are obtained according to ASTM D-1238, at 190°C.
Due to the high molecular weight of the
Primacor 5981 grade of the ethylene-acrylic acid
20 copolymer, this copolymer is the more preferred grade
utilized in the invention.
The metal cation salts utilized in the
invention are those salts which provide the metal
cations capable of neutralizing, to various extents, the
25 carboxylic acid groups of the high acid copolymer.
These include acetate, oxide or hydroxide salts of
lithium, calcium, zinc, sodium, potassium, nickel,
magnesium, and manganese.
Examples of such lithium ion sources are
30 lithium hydroxide monohydrate, lithium hydroxide,
lithium oxide and lithium acetate. Sources for the
calcium ion include calcium hydroxide, calcium acetate
and calcium oxide. suitable zinc ion sources are zinc
acetate dihydrate and zinc acetate, a blend of zinc
35 oxide and acetic acid. Examples of sodium ion sources
SUBSTITUTE SHEET (RULE 26j
I
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 24 -
are sodium hydroxide and sodium acetate. Sources for
the potassium ion include potassium hydroxide and
potassium acetate.. Suitable nickel ion sources are
nickel acetate, nickel oxide and nickel hydroxide.
Sources of magnesium include magnesium oxide, magnesium
hydroxide, magnesium acetate. Sources of manganese
include manganese acetate and manganese oxide.
The new metal cation neutralized high acid
ionomer resins are produced by reacting the high acid
base copolymer with various amounts of the metal cation
salts above the crystalline melting point of the
copolymer, such as at a temperature from about 200°F to
about 500°F, preferably from about 250°F to about 350°F
under high shear conditions at a pressure of from about
10 psi to 10,000 psi. Other well known blending
techniques may also be used. The amount of metal cation
salt utilized to produce the new metal cation
neutralized high acid based ionomer resins is the
quantity which provides a sufficient amount of the metal
cations to neutralize the desired percentage of the
carboxylic acid groups in the high acid copolymer. The
extent of neutralization is generally from about 10% to
about 90%.
As indicated below in Table 4 and more
specifically in Example 1 in U.S. Application Serial No.
08/493,089, a number of new types of metal cation
neutralized high acid ionomers can be obtained from the
above indicated process. These include new high acid
ionomer resins neutralized to various extends with
manganese, lithium, potassium, calcium and nickel
cations. In addition, when a high acid ethylene/acrylic
acid copolymer is utilized as the base copolymer
component of the invention and this component is
subsequently neutralized to various extents with the
metal cation salts producing acrylic acid based high
acid ionomer resins neutralized with cations such as
sodium, potassium, lithium, zinc, magnesium, manganese,
sues~,wTE sHe~ cRU~ zs~
CA 02283788 1999-09-09
WO 98/43709 PCTIUS98/06159
- 25 -
calcium and nickel, several new cation neutralized
acrylic acid based high acid ionomer resins are
produced.
. TABLE 4
Metal Cation Neutralized Hitch Acid Ionomers
Wt-% Wt-% Melt Shore
Formulation Neutralization C.O.R.D
Cation Index Hardness
Salt
No.
1(NaOH) 6.98 67.5 0.9 .804 71
2(NaOH) 5.66 54.0 2.4 .808 73
3(NaOH) 3.84 35.9 12.2 .812 69
4(NaOH) 2.91 27.0 17.5 .812 (brittle)
5(MnAc) 19.6 71.? 7.5 .809 73
6(MnAc) 23.1 88.3 3.5 .814 77
~-5 7(~C) 15.3 53.0 7.5 .810 72
8(MnAc) 26.5 106 0.7 .813 (brittle)
9(LiOH) 4.54 71.3 0.6 .810 74
10(LiOH) 3.38 52.5 4.2 .818 72
il(LiOH) 2.34 35.9 18.6 .815 72
12(KOH) 5.30 36.0 19.3 Broke 70
2 13(KOH) 8.26 57.9 7.18 .804 70
0
14(KOH) 10.7 77.0 9.3 .801 67
15(ZnAc) 17.9 71.5 0.2 .806 71
16(ZnAc) 13.9 53.0 0.9 .797 69
17(ZnAc) 9.91 36.1 3.4 .793 67
2 18(MgAC) 17.4 70.7 2.8 .814 74
19(MgAc) 20.6 87.1 1.5 .815 76
20(MgAc) 13.8 53.8 4.1 .814 74
21(CaAc) 13.2 69.2 1.1 .813
22(CaAc) 7.12 34.9 74
Controls:50/50 Blend of 10.1 .808
Ioteks 8000/7030 70
C. O.R.=.810/65
DuPont High Acid Shore
Surlyn~ 8422 D Hardness
(Na) C.O.R.=.811/70
DuPOnt High Acid Shore
Surlyn~' 8162 D Hardness
(Zn) C.O.R.=.807/65
Exxon High Acid Shore
Iotek EX-960 D Hardness
(Zn) C.O.R.=.796/65
Shore
D Hardness
TABLE 4 (continued)
suesnruTE sHe~ (AUK Zs~
I
CA 02283788 1999-09-09
WO 98/43709 PGT/US98/05159
- 26 -
Wt-% Wt-~ Melt
Formulation Cation Salt Neutralizatio Index C.O.R.
No. n
23(Mg0) 2.91 53.5 2.5 .813
24(Mg0) 3.85 71.5 2.8 .g08
25(Mg0) 4.76 89.3 1.1 .809
26(Mg0) 1.96 35.7 7.5 .815
Control for Formulations 23-26 is 50/50 Iotek 8000/7030,
C.O.R.=.g14, Formulation 26 C.O.R. was normalized to that control accordingly
TABLE 4 (continued?
Wt-~ Wt-% Melt
Formulation Cation Salt Neutralizatio Index C.O.R. Shore D
N°-' n Fiardnes
s
27(NiAc) 13.04 61.1 0.2 .802 71
28{NiAC) 10.71 48.9 0.5 .799 72
1 5 29(NiAc) 8.26 36.7 1.8 .796 69 '
30(NiAC) 5.66 24.4 7.5 .786 64
Control for Formulation Nos. 27-30 is 50/50 Iotek 8000/7030, C.O.R.=.807
When compared to low acid versions of similar
cation neutralized ionomer resins, the new metal cation
neutralized high acid ionomer resins exhibit enhanced
hardness, modulus and resilience characteristics. These
are properties that are particularly desirable in a
number of thermoplastic fields, including the field of
golf ball manufacturing.
When utilized in the construction of the inner
layer of a multi-layered golf ball, it has been found
that the new acrylic acid based high acid ionomers
extend the range of hardness beyond that previously
obtainable while maintaining the beneficial properties
(i.e. durability, click, feel, etc.) of the softer low
acid ionomer covered balls, such as balls produced
utilizing the low acid ionomers disclosed in U.S. Patent
Nos. 4,884,814 and 4,911,451.
Moreover, as a result of the development of a
number of new acrylic acid based high acid ionomer
resins neutralized to various extents by several
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 27 -
different types of metal cations, such as manganese,
lithium, potassium, calcium and nickel cations, several
new ionomers or ionomer blends are now available for
production of an inner cover layer of a multi-layered
golf ball. By using these high acid ionomer resins,
harder, stiffer inner cover layers having higher
C.O.R.s, and thus longer distance, can be obtained.
More preferably, it has been found that when
two or more of the above-indicated high acid ionomers,
l0 particularly blends of sodium and zinc high acid
ionomers, are processed to produce the covers of multi-
layered golf balls, (i.e., the inner cover layer herein)
the resulting golf balls will travel further than
previously known multi-layered golf balls produced with
low acid ionomer resin covers due to the balls' enhanced
coefficient of restitution values.
The low acid ionomers which may be suitable
for use in formulating the inner layer compositions of
several of the embodiments of the subject invention are
ionic copolymers which are the metal, i.e., sodium,
zinc, magnesium, etc., salts of the reaction product of
an olefin having from about 2 to 8 carbon atoms and an
unsaturated monocarboxylic acid having from about 3 to 8
carbon atoms. Preferably, the ionomeric resins are
copolymers of ethylene and either acrylic or methacrylic
acid. In some circumstances, an additional comonomer
such as an acrylate ester (i.e., iso- or n-
butylacrylate, etc.) can also be included to produce a
softer terpolymer. The carboxylic acid groups of the
copolymer are~artially neutralized (i.e., approximately
10-100%, preferably 30 - 70%) by the metal ions. Each
of the low acid ionomer resins which may be included in
the inner layer cover compositions of the invention
. contains 16% by weight of less of a carboxylic acid.
The inner layer compositions include the low
acid ionomers such as those developed and sold by E.I.
DuPont de Nemours & Company under the trademark
SUBSTITUTE SHEET (RULE 25)
I
CA 02283788 1999-09-09
WO 98143709 PCTNS98/06159
- 28 -
"Surlyn°" and by Exxon Corporation under the trademark
"Escor°" or tradename "Iotek," or blends thereof.
The low acid ionomer resins available from
Exxon under the designation "Escor°" and/or "Iotek," are
somewhat similar to the low acid ionomeric resins
available under the "Surlyn°" trademark. However, since
the Escor~/Iotek ionomeric resins are sodium or zinc
salts of polyethylene-acrylic acid) and the "Surlyn~"
resins are zinc, sodium, magnesium, etc. salts of
polyethylene-methacrylic acid), distinct differences in
properties exist.
When utilized in the construction of the inner
layer of a multi-layered golf ball, it has been found
that the low acid ionomer blends extend the range of
compression and spin rates beyond that previously
obtainable. More preferably, it has been found that
when two or more low acid ionomers, particularly blends
of sodium and zinc ionomers, are processed to produce
the covers of multi-layered golf balls, (i.e., the inner
cover layer herein) the resulting golf balls will travel
further and at an enhanced spin rate than previously
known multi-layered golf balls. Such an improvement is
particularly noticeable in enlarged or oversized golf
balls.
The use of an inner layer formulated from
blends of lower acid ionomers produces multi-layer golf
balls having enhanced compression and spin rates. These
are the properties desired by the more skilled golfer.
In yet another embodiment of the inner cover
layer, a blend of high and low acid ionomer resins is
used. These can be the ionomer resins described above,
combined in a weight ratio which preferably is within
the range of 10:90 to 90:10 parts of high and low acid
ionomer resins.
A further additional embodiment of the inner
cover layer is primarily based upon the use of a fully
non-ionomeric thermoplastic material. Suitable non-
SUBSTITUTE SHEET (RULE 26j
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 29 -
ionomeric materials include metallocene catalyzed
polyolefins or polyamides, polyamide/ionomer blends,
polyphenylene ether/ionomer blends, etc., which have a
shore D hardness of a60 and a flex modulus of greater
than about 30,000 psi, or other hardness and flex
modulus values which are comparable to the properties of
the ionomers described above. Other suitable materials
include but are not limited to thermoplastic or
thermosetting polyurethanes, a polyester elastomer such
as that marketed by DuPont under the trademark Hytrel°,
or a polyester amide such as that marketed by Elf
Atochem S.A. under the trademark Pebax°, a blend of two
or more non-ionomeric thermoplastic elastomers, or a
blend of one or more ionomers and one or more non-
ionomeric thermoplastic elastomers. These materials can
be blended with the ionomers described above in order to
reduce cost relative to the use of higher quantities of
ionomer.
Outer Cover Layer
While the dual core component described below,
and the hard inner cover layer formed thereon, provide
the multi-layer golf ball with power and distance, the
outer cover layer 16 is comparatively softer than the
inner cover layer. The softness provides for the feel
and playability characteristics typically associated
with balata or balata-blend balls. The outer cover layer
or ply is comprised of a relatively soft, low modulus
(about 1,000 psi to about 10,100 psi) and, in an
alternate embodiment, low acid (less than 16 weight
percent acid) ionomer, an ionomer blend, a non-ionomeric
thermoplastic or thermosetting material such as, but not
limited to, a metallocene catalyzed polyolefin such as
EXACT material available from EXXON, a polyurethane, a
polyester elastomer such as that marketed by DuPont
under the trademark Hytrel~, or a polyester amide such
as that marketed by Elf Atochem S.A. under the trademark
SUBSTITUTE SHEET (RULE 2B)
i
CA 02283788 1999-09-09
WO 98!43709 PCT/US98/06159
- 30 -
Pebax~, a blend of two or more non-ionomeric
thermoplastic or thermosetting materials, or a blend of
one or more ionomers and one or more non-ionomeric
thermoplastic materials. The outer layer is fairly thin
S (i.e. from about 0.010 to about 0.10 inches in
thickness, more desirably 0.03 to 0.06 inches in
thickness for a 1.680 inch ball and 0.04 to 0.07 inches
in thickness for a 1.72 inch or more ball), but thick
enough to achieve desired playability characteristics
while minimizing expense. Thickness is defined as the
average thickness of the non-dimpled areas of the outer
cover layer. The outer cover layer, such as layer 16,
16 has a Shore D hardness of 55 or less, and more
preferably SO or less.
In one embodiment, the outer cover layer
preferably is formed from an ionomer which constitutes
at least 75 weight o of an acrylate ester-containing
ionic copolymer or blend of acrylate ester-containing
ionic copolymers. This type of outer cover layer in
combination with the core and inner cover layer
described above results in golf ball covers having a
favorable combination of durability and spin rate. The
one or more acrylate ester-containing ionic copolymers
each contain an olefin, an acrylate ester, and an acid.
In a blend of two or more acrylate ester-containing
ionic copolymers, each copolymer may contain the same or
a different olefin, acrylate ester and acid than are
contained in the other copolymers. Preferably, the
acrylate ester-containing ionic copolymer or copolymers
are terpolymers, but additional monomers can be combined
into the copolymers if the monomers do not substantially
reduce the scuff resistance or other good playability
properties of the cover.
For a given copolymer, the olefin is selected
from the group consisting of olefins having 2 to 8
carbon atoms, including, as non-limiting examples,
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 31 -
ethylene, propylene, butene-1, hexene-1 and the like.
Preferably the olefin is ethylene.
The acrylate ester is an unsaturated monomer
having from 1 to 21 carbon atoms which serves as a
softening comonomer. The acrylate ester preferably is
methyl, ethyl, n-propyl, n-butyl, n-octyl, 2-ethylhexyl;
or 2-methoxyethyl 1-acrylate, and most preferably is
methyl acrylate or n-butyl acrylate. Another suitable
type of softening comonomer is an alkyl vinyl ether
selected from the group consisting of n-butyl, n-hexyl,
2-ethylhexyl, and 2-methoxyethyl vinyl ethers.
The acid is a mono- or dicarboxylic acid and
preferably is selected from the group consisting of
methacrylic, acrylic, ethacrylic, a-chloroacrylic,
crotonic, malefic, fumaric, and itaconic acid, or the
like, and half esters of malefic, fumaric and itaconic
acid, or the like. The acid group of the copolymer is
l0-100% neutralized with any suitable cation, far
example, zinc, sodium, magnesium, lithium, potassium,
2o calcium, manganese, nickel, chromium, tin, aluminum, or
the like. It has been found that particularly good
results are obtained when the neutralization level is
about 50-100%.
The one or more acrylate ester-containing
ionic copolymers each has an individual Shore D hardness
of about 5-64. The overall Shore D hardness of the
outer cover is 55 or less, and generally is 40-55. It
is preferred that the overall Shore D hardness of the
outer cover is in the range of 40-50 in order to impart
particularly good playability characteristics to the
ball.
. The outer cover layer of the invention is
formed over a core to result in a golf ball having a
coefficient of restitution of at least 0.770, more
preferably at least 0.780, and most preferably at least
0.790. The coefficient of restitution of the ball will
depend upon the properties of both the core and the
SUBSTITUTE SHEET (RULE 2B)
I
CA 02283788 1999-09-09
W O 98143709 PG"T/US98J06159
- 32 -
cover. The PGA compression of the golf ball is 100 or
less, and preferably is 90 or less.
The acrylate ester-containing ionic copolymer
or copolymers used in the outer cover layer can be
obtained by neutralizing commercially available acrylate .
ester-containing acid copolymers such as polyethylene-
methyl acrylate-acrylic acid terpolymers, including
ESCOR ATX (Exxon Chemical Company) or poly (ethylene-
butyl acrylate-methacrylic acid) terpolymers, including
NUCREL (DuPont Chemical Company). Particularly
preferred commercially available materials include ATX
320, ATX 325, ATX 310, ATX 350, and blends of these
materials with NUCREL 010 and NUCREL 035. The acid
groups of these materials and blends are neutralized
with one or mare of various cation salts including zinc,
sodium, magnesium, lithium, potassium, calcium,
manganese, nickel, etc. The degree of neutralization
ranges from 10-1000. Generally, a higher degree of
neutralization results in a harder and tougher cover
material. The properties of non-limiting examples of
commercially available un-neutralized acid terpolymers
which can be used to form the golf ball outer cover
layers of the invention are provided below in Table 5.
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 33 -
TABLE 5
Properties of Un-Neutralized Acid Ter,~~olv~riers
Flex
Melt Index Modulus
dg/min Acid No. MPa Hardness
Trade Name ASTM D 1238 % KOH (ASTM D790,~ (Shore D)
ATX 310 6 45 80 44
ATX 320 5 45 50 34
ATX 325 20 45 9 30
ATX 350 6 15 20 28
Nucrel O10 11 60 40 40
Nucrel 035 35 60 59 40
The ionomer resins used to form the outer
cover layers can be produced by reacting the acrylate
ester-containing acid copolymer with various amounts of
the metal cation salts at a temperature above the
crystalline melting point of the copolymer, such as a
temperature from about 200'F to about 500'F, preferably
from about 250'F to about 350'F, under high shear
conditions at a pressure of from about 100 psi to 10,000
psi. Other well known blending techniques may also be
used. The amount of metal cation salt utilized to
produce the neutralized ionic copolymers is the quantity
which provides a sufficient amount of the metal cations
to neutralize the desired percentage of the carboxylic
acid groups in the high acid copolymer. When two or
more different copolymers are to be used, the copolymers
can be blended before or after neutralization.
Generally, it is preferable to blend the copolymers
before they are neutralized to provide for optimal
mixing.
The compatibility of the acrylate ester-
containing copolymers with each other in a copolymer
blend produces a golf ball outer cover layer having a
surprisingly good scuff resistance for a given hardness
suesmu'~ SHEET (RULE 2B)
I
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 34 -
of the outer cover layer. The golf ball according to
the invention has a scuff resistance of no higher than
3Ø It is preferred that the golf ball has a scuff
resistance of no higher than about 2.5 to ensure that
the golf ball is scuff resistant when used in
conjunction with a variety of types of clubs, including
sharp-grooved irons, which are particularly inclined to
result in scuffing of golf ball covers. The best
results according to the invention are obtained when the
outer cover layer has a scuff resistance of no more than
about 2Ø
Additional materials may also be added to the
inner and outer cover layer of the present invention as
long as they do not substantially reduce the playability
properties of the ball. Such materials include dyes
(for example, Ultramarine Blue sold by Whitaker, Clark,
and Daniels of South Plainsfield, N.J.) (see U.S. Pat.
No. 4,679,795), pigments such as titanium dioxide, zinc
oxide, barium sulfate and zinc sulfate; W absorbers;
antioxidants; antistatic agents; and stabilizers.
Moreover, the cover compositions of the present
invention may also contain softening agents such as
those disclosed in U.S. Patent Nos. 5,312,857 and
5,306,760, including plasticizers, metal stearates,
processing acids, etc., and reinforcing materials such
as glass fibers and inorganic fillers, as long as the
desired properties produced by the golf ball covers of
the invention are not impaired.
The outer layer in another embodiment of the
invention includes a blend of a soft (low acid) ionomer
resin with a small amount of a hard (high acid) ionomer
resin. A low modules ionomer suitable for use in the
outer layer blend has a flexural modules measuring from
about 1,000 to about 10,000 psi, with a hardness of
about 20 to about 40 on the Shore D scale. A high
modules ionomer herein is one which measures from about
15,000 to about 70,000 psi as measured in accordance
SU6ST1TUTE SHEET (RULE 26j
CA 02283788 1999-09-09
WO 98J43709 PCT/US98/06159
- 35 -
with ASTM method D-790. The hardness may be defined as
at least 50 on the Shore D scale as measured in
accordance with ASTM method D-2240.
Soft ionomers primarily are used in
formulating the hard/soft blends of the cover
compositions. These ionomers include acrylic acid and
methacrylic acid based soft ionomers. They are
generally characterized as comprising sodium, zinc, or
other mono- or divalent metal cation salts of a
terpolymer of an olefin having from about 2 to 8 carbon
atoms, methacrylic acid, acrylic acid, or another, a, f3-
unsaturated carboxylic acid, and an unsaturated monomer
of the acrylate ester class having from 1 to 21 carbon
atoms. The soft ionomer is preferably made from an
acrylic acid base polymer is an unsaturated monomer of
the acrylate ester class.
Certain ethylene-acrylic acid based soft
ionomer resins developed by the Exxon Corporation under
the designation "Iotek 7520" (referred to experimentally
by differences in neutralization and melt indexes as LDX
195, LDX 196, LDX 218 and LDX 219) may be combined with
known hard ionomers such as those indicated above to
produce the inner and outer cover layers. The
combination produces higher C.O.R.s at equal or softer
hardness, higher melt flow (which corresponds to
improved, more efficient molding, i.e., fewer rejects]
as well as significant cost savings versus the outer
layer of multi-layer balls produced by other known hard-
soft ionomer blends as a result of the lower overall raw
materials cost and improved yields.
While the exact chemical composition of the
resins to be sold by Exxon under the designation Iotek
7520 is considered by Exxon to be confidential and
proprietary information, Exxon's experimental product
data sheet lists the following physical properties of
the ethylene acrylic acid zinc ionomer developed by
Exxon:
suesmu~ SHEET (RULE 28)
ICA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 36 -
TABLE 6
Phvsical Properties of Iotek 7520
Property Value ASTM Method Units Typical
Melt Index D-1238 g/10
min.
2
Density D-1505 kg/m3 0.962
Cation Zinc
Melting Point D-3417 C 66
Crystallization
Point D-3417 C 49
Vicat Softening
Point D-1525 C 42
Plague Properties ( 2 mm thick CompressionMolded
Plaques)
Tensile at Break D-638 MPa 10
Yield Point D-638 MPa None
Elongation at Break D-638 % 760
1% Secant Modulus D-638 MPa 22
Shore D Hardness D-2240 32
Flexural Modulus D-790 MPa 26
Zwick Rebound ISO 4862 % 52
De Mattia Flex
Resistance D-430 Cycles >5000
In addition, test data collected by the
inventor indicates that Iotek 7520 resins have Short D
hardnesses of about 32 to 36 (per ASTM D-2240), melt
flow indexes of 310.5 g/10 min (at 190°C. per ASTM D-
1288), and a flexural modulus of about 2500 - 3500 psi
(per ASTM D-790}. Furthermore, testing by an
independent testing laboratory by pyrolysis mass
spectrometry indicates at Iotek 7520 resins are
SUBSTITUTE SHEET (RULE 25)
CA 02283788 1999-09-09
WO 98/43709 PCTIITS98/06159
- 37 -
generally zinc salts of a terpolymer of ethylene,
acrylic acid, and methyl acrylate.
Furthermore, the inventor has found that a
newly developed grade of an acrylic acid based soft
ionomer available from the Exxon Corporation under the
designation Iotek 7510 is also effective when combined
with the hard ionomers indicated above in producing golf
ball covers exhibiting higher C.O.R. values at equal or
softer hardness than those produced by known hard-soft
l0 ionomer blends. In this regard, Iotek 7510 has the
advantages (i.e. improved flow, higher C.O.R. values at
equal hardness, increased clarity, etc.) produced by the
Iotek 7520 resin when compared to the methacrylic acid
base soft ionomers known in the art (such as the Surlyn°
8625 and Surlyn~ 8629 combinations disclosed in U.S.
Patent No. 4,8884,814).
In addition, Iotek 7510, when compared to
Iotek 7520, produces slightly higher C.O.R. values at
equal softness/hardness due to the Iotek 7510's higher
hardness and neutralization. Similarly, Iotek 7510
produces better release properties (from the mold
cavities) due to its slightly higher stiffness and lower
flow rate than Iotek 7520. This is important in
production where the soft covered balls tend to have
lower yields caused by sticking in the molds and
subsequent punched pin marks from the knockouts.
According to Exxon, Iotek 7510 is of similar
chemical composition as Iotek 7520 (i.e. a zinc salt of
a terpolymer of ethylene, acrylic acid, and methyl
acrylate) but is more highly neutralized. Based upon
FTIR analysis, Iotek 7520 is estimated to be about 30-40
wt.-% neutralized and Iotek 7510 is estimated to be
about 40-60 wt.-% neutralized. The typical properties
of Iotek 7510 in comparison of those of Iotek 7520 in
comparison of those of Iotek 7520 are set forth below:
SUBSTITUTE SHEET (RULE 26)
l I
CA 02283788 1999-09-09
WO 9$/43709 PCT/CTS98I06159
- 38 -
TABLE 7
Physical Properties of Iotek 7510
in Comparison to Iotek 7520
IOTEK 7520 IOTEK 7510
MI, g/10 min
2.0 0.8
Density, g/cc
0.96 0.97
Melting Point, F 151 149
Vicat Softening Point, F 108 109
Flex Modulus, psi 3800 5300
Tensile Strength, psi 1450 1750
Elongation, % 760 690
Hardness, Shore D 32 35
The hard ionomer resins utilized to produce
the outer cover layer composition hard/soft blends
include ionic copolymers which are the sodium, zinc,
magnesium, lithium, etc. salts of the reaction product
of an olefin having from 2 to 8 carbon atoms and an
unsaturated monocarboxylic acid having from 3 to 8
carbon atoms. The carboxylic acid groups of the
copolymer may be totally or partially (i.e.
approximately 15-75 percent) neutralized.
The hard ionomeric resins are likely
copolymers of ethylene and acrylic and/or methacrylic
acid, with copolymers of ethylene and acrylic acid being
the most preferred. Two or more types of hard ionomeric
resins may be blended into the outer cover layer
compositions in order to produce the desired properties
of the resulting golf balls.
As discussed earlier herein, the hard
ionomeric resins introduced under the designation Escor~
and sold under the designation "Iotek" are somewhat
similar to the hard ionomeric resins sold under the
Surlyn~ trademark. However, since the "Iotek" ionomeric
resins are sodium or zinc salts of polyethylene-acrylic
acid) and the Surlyn° resins are zinc or sodium salts of
SU6STITUTE SHEET (RULE 2B)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 39 -
polyethylene-methacrylic acid) some distinct
differences in properties exist. As more specifically
indicated in the data set forth below, the hard "Iotek"
resins (i.e., the acrylic acid based hard ionomer
resins) are the more preferred hard resins for use in
formulating the outer layer blends for use in the
present invention. In addition, various blends of
"Iotek" and Surlyn° hard ionomeric resins, as well as
other available ionomeric resins, may be utilized in the
to present invention in a similar manner.
Examples of commercially available hard
ionomeric resins which may be used in the present
invention in formulating the outer cover blends include
the hard sodium ionic copolymer sold under the trademark
Surlyn~ 8940 and the hard zinc ionic copolymer sold
under the trademark Surlyn° 9910. Surlyn~ 8940 is a
copolymer of ethylene with methacrylic acid and about 15
weight percent acid which is about 29 percent
neutralized with sodium ions. this resin has an average
melt flow index of about 2.8. Surlyn° 9910 is a
copolymer of ethylene and methacrylic acid with about 15
weight percent acid which is about 58 percent
neutralized with zinc ions. The average melt flow index
of Surlyn~ 9910 is about 0.7. The typical properties of
Surlyn~ 9910 and 8940 are set forth below in Table 8:
TABLE 8
~ical Properties of Commercially Available Hard
Surlvn~ Resins Suitable for Use in the Outer Layer
Blends of the Present Invention
3 ~ ASTM D 8940 9910 8920 8528 9970 9730
Cation Type Sodium Zinc SodiumSodiumZinc Zinc
Melt flow index,
gms/10 min. D-1238 2.8 0.7 0.9 1.3 14.D 1.6
3 5 Specific Gravity,
J/~' D-792 0.95 0.97 0.95 0.94 0.95 0.95
Hardness, Shore D D-2240 66 64 66 60 62 63
sussmu~ sHeEr ~RU~ zs~
ICA 02283788 1999-09-09
WO 98143709 PCT/US98/06159
- 40 -
Tensile Strength,
(kpsi), MPa D-638 (4.8) (3.6) (5.4) (4.2) (4.1)
(3.2)
33.1 24.8 37.2 29.0 22.0 28.0
Elongation, ~ D-638 470 290 350 450 460 460
Flexural Modulus,
(kpsi) MPa D-790 (51) (48) (55) (32) (28) (30)
350 330 380 220 190 210
Tensile Impact (23C)
KJ/mz (ft.-lbs./in') D-i822S 1020 865 1160 760 1240
1020
(485) (485) (410) (550) (590)
(360)
Vicat Temperature,C D-1525 63 62 58 73 61 73
Examples of the mor e pertinent acrylic acid
based hard ionomer resin suit able for use in th
e present
outer cover composition sold under the "Iotek'~
trade
name by the Exxon Corporation include Iotek 8000, 8010,
8020, 8030, 7030, 7010, 7020, 1002, 1003, 959 and 960.
The physical properties of Io tek 959 and 960 are shown
above. The typical propertie s of the remainder f these
o
and other Iotek hard ionomers suited f
i
or use
n
formulating the outer layer over com
c o
iti
p set
s
on are
forth below in Table 9:
TABLE 9
~ical Properties of Iotek Ionomers
Resin ASTM
2
5
Properties Method Units 4000 4010 8000 8020 8030
Cation type zinc zinc sodium sodium
sodium
Melt index D-1238 g/10 min. 2.5 1.5 0.8 1.6 2.8
Density D-1505 kg/m' 963 963 954 960 960
Melting Point D-3417 C 90 90 90 87.5 87.5
3 Crystallization D-3417 C 62 64 56 53
0
55
Point
Vicat Softening D-1525 C 62 63 61 64 67
Point
% Weight Acrylic Acid 16 11
3 % of Acid Groups
5
cation neutralized 30 40
Plaque ASTM
Properties Method Units 4000 4010 8000 8020 8030
(3 mm thick,
4 compression molded)
0
Tensile at break D-638 MPa 24 26 36 31.5 28
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98143709 PCTIUS98/06159
- 41 -
Yield point D-638MPa none none21 21 23
Elongation at D-638% 395 420 350 410 395
break
1% Secant modulusD-638MPa 160 160 300 35D 390
Shore Hardness D-2240-- 55 55 61 58 59
D
Film Properties
(50 micron film
2.2:1
Blow-up ratio) 4000 40108000 8020 8030
Tensile at Break D-882MPa 41 39 42 52 47.4
MD D-882MPa 37 38 38 38 40.5
TD
1 0 Yield point MD D-882MPa 15 17 17 23 21.6
TD D-882MPa 14 15 15 21 20.7
Elongation at
Break
MD D-882% 310 270 260 295 305
TD D-882% 360 340 280 340 345
1 5 1% Secant modulusD-882MPa 210 215 390 380 380
MD D-882MPa 200 225 380 350 345
TD
Dart Drop Impact D-1709g/micron 12.4 12.520.3
Resin
Properties MethodUnits 7010 7020 7030
2 0 Cation type zinc zinc zinc
Melt Index D-1238g/10 min. 0.8 1.5 2.5
Density D-1505kg/m~ 960 96D
960
Melting Point D-3417oC 90 90 90
2 5 Crystallization
Point D-3417oC -- _-
vicat Softening
Point D-1525oC 60 63 62.5
%Weight Acrylic
3 0 Acid -- -- --
% of Acid Groups
Cation Neutralized __
Plaque ASS
Properties MethodUnits 7010 7020 7030
3 5 (3 mm thick,
compression molded)
Tensile at break D-638MPa 38 38 38
Yield Point D-638MPa none none none
Elongation at D-638% 500 420 395
break
4 0 1% Secant modulusD-638MPa -- -_
Shore Hardness D-2240-- 57 55 55
D
It has bee n determined ft
that
when
hard/so
ionomer blends are sed for e layer,good
u th outer
cover
45 results are achieved when the relative combination is
in
SUBSTITUTE SHEET (RULE 28)
I
CA 02283788 1999-09-09
WO 98143709 PGT/US98/06159
- 42 -
a range of about 3-25 percent hard ionomer and about 75-
97 percent soft ionomer.
Moreover, in alternative embodiments, the
outer cover layer formulation may also comprise up to
100 wt % of a soft, low modulus non-ionomeric
thermoplastic material including a polyester
polyurethane such as B.F. Goodrich Company's Estane°
polyester polyurethane X-4517. The non-ionomeric
thermoplastic material may be blended with a soft
ionomer. For example, polyamides blend well with soft
ionomer. According to B.F. Goodrich, Estane~ X-4517 has
the following properties:
Properties of Estane~ X-4517
Tensile 1430
1000
815
200% 1024
300% 1193
Elongation 541
Youngs Modulus 1825
Hardness A/D 88/39
Bayshore Rebound 59
Solubility in Water Insoluble
Melt processing temperature >350oF (>177oC)
Specific Gravity (Hz0=1) 1.1-1.3
Other soft, relatively low modulus non-
ionomeric thermoplastic elastomers may also be utilized
to produce the outer cover layer as long as the non-
ionomeric thermoplastic elastomers produce the
playability and durability characteristics desired
without adversely effecting the enhanced travel distance
characteristic produced by the high acid ionomer resin
composition. These include, but are not limited to
thermoplastic polyurethanes such as Texin thermoplastic
polyurethanes from Mobay Chemical Co. and the Pellethane
thermoplastic polyurethanes from Dow Chemical Co.; non-
ionomeric thermoset polyurethanes including but not
limited to those disclosed in U.S. Patent 5,334,673;
SUBSTITUTE SHEET (RULE 25)
CA 02283788 1999-09-09
WO 98143709 PCT/US98106159
- 43 -
cross-linked metallocene catalyzed polyolefins;
ionomer/rubber blends such as those in Spalding U.S.
Patents 4,986,545; 5,098,105 and 5,187,013; and, Hytrel
polyester elastomers from DuPont and Pebax
polyesteramides from Elf Atochem S.A.
Dual Core
As noted, the present invention golf balls
utilize a unique dual core configuration. Preferably,
the cores comprise (i) an interior spherical center
l0 component formed from a thermoset material, a
thermoplastic material, or combinations thereof and (ii)
a core layer disposed about the spherical center
component, the core layer~formed from a thermoset
material, a thermoplastic material, or combinations
thereof. Most preferably, the core layer is disposed
immediately adjacent to, and in intimate contact with
the center component. The cores may further comprise
(iii) an optional outer core layer disposed about the
core layer. Most preferably, the outer core layer is
disposed immediately adjacent to, and in intimate
contact with the core layer. The outer core layer may
be formed from a thermoset material, a thermoplastic
material, or combinations thereof.
The present invention provides several
additionally preferred embodiment golf balls utilizing
the unique dual core configuration and the previously
described cover layers. Referring to FIGURE 3, a
preferred embodiment golf ball 35 is illustrated
comprising a core 30 formed from a thermoset material
surrounded by a core layer 32 formed from a
thermoplastic material. A multi-layer cover 34
surrounds the core 30 and core layer 32. The mufti-
layer cover 34 preferably corresponds to the previously
described mufti-layer cover 12.
As illustrated in FIGURE 4, another preferred
embodiment golf ball 45 in accordance with the present
SUBSTITUTE SHEET (RULE 2B)
CA 02283788 1999-09-09
WO 98/43709 PCTlUS98106159
- 44 -
invention is illustrated. The preferred embodiment golf
ball 45 comprises a core 40 formed from a thermoplastic
material surrounded by a core layer 42. The core layer
42 is formed from a thermoset material. A multi-layer
cover 44 surrounds the core 40 and the core layer 42.
Again, the multi-layer cover 44 preferably corresponds
to the previously described multi-layer cover 12.
FIGURE 5 illustrates yet another preferred
embodiment golf ball 55 in accordance with the present
invention. The preferred embodiment golf ball 55
comprises a core 50 formed from a thermoplastic
material. A core layer 52 surrounds the core 50. The
core layer 52 is formed from a thermoplastic material
which may be the same as the material utilized with the
core 50, or one or more other or different thermoplastic
materials. The preferred embodiment golf ball 55
utilizes an optional outer core layer 54 that surrounds
the core component 50 and the core layer 52. The outer
core layer 54 is formed from a thermoplastic material
which may be the same or different than any of the
thermoplastic materials utilized by the core 5o and the
core layer 52. The golf ball 55 further comprises a
mufti-layer cover S6 that is preferably similar to the
previously described mufti-layer cover 12.
FIGURE 6 illustrates yet another preferred
embodiment golf ball 65 in accordance with the present
invention. The preferred embodiment golf ball 65
comprises a core 60 formed from a thermoplastic,
thermoset material, or any combination of a thermoset
and thermoplastic material. A core layer 62 surrounds
the core 60. The core layer 62 is formed from a
thermoset material. The preferred embodiment golf ball
65 also comprises an optional outer core layer 64 formed
from a thermoplastic material. A mufti-layer cover 66,
preferably similar to the previously described multi
layer cover 12, is disposed about, and generally
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 45 -
surrounds, the core 60, the core layer 62 and the outer
core 64.
A wider array of thermoset materials can be
utilized in the present invention dual cores. Examples
of suitable thermoset materials include butadiene or any
natural or synthetic elastomer, including metallocene
polyolefins, polyurethanes, silicones, polyamides,
polyureas, or virtually any irreversibly cross-linked
resin system. It is also contemplated that epoxy,
phenolic, and an array of unsaturated polyester resins
could be utilized.
The thermoplastic material utilized in the
present invention golf balls and, particularly their
dual cores, may be nearly any thermoplastic material.
Examples of typical thermoplastic materials for
incorporation in the golf balls of the present invention
include, but are not limited to, ionomers, polyurethane
thermoplastic elastomers, and combinations thereof. It
is also contemplated that a wide array of other
thermoplastic materials could be utilized, such as
polysulfones, fluoropolymers, polyamide-imides,
polyarylates, polyaryletherketones, polyaryl
sulfones/polyether sulfones, polybenzimidazoles,
polyether-imides, polyimides, liquid crystal polymers,
polyphenylene sulfides; and specialty high-performance
resins, which would include fluoropolymers,
polybenzimidazole, and ultrahigh molecular weight
polyethylenes.
Additional examples of suitable thermoplastics
include meta3~ocenes, polyvinyl chlorides,
acrylonitrile-butadiene-styrenes, acrylics, styrene-
acrylonitriles, styrene-malefic anhydrides, polyamides
(nylons), polycarbonates, polybutylene terephthalates,
polyethylene terephthalates, polyphenylene
ethers/polyphenylene oxides, reinforced polypropylenes,
and high-impact polystyrenes.
SUBSTITUTE SHEET (RULE 2B)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98106159
- 46 -
Preferably, the thermoplastic materials have
relatively high melting points, such as a melting point
of at least about 300°F. Several examples of these
preferred thermoplastic materials and which are
commercially available include, but are not limited to,
Capron (a blend of nylon and ionomer), Lexan
polycarbonate, Pebax, and Hytrel. The polymers or resin
system may be cross-linked by a variety of means such as
by peroxide agents, sulphur agents, radiation or other
IO cross-linking techniques.
Any or all of the previously described
components in the cores of the golf ball of the present
invention may be formed in such a manner, or have
suitable fillers added, so that their resulting density
is decreased or increased. For example, any of these
components in the dual cores could be formed or
otherwise produced to be light in weight. For instance,
the components could be foamed, either separately or in-
situ. Related to this, a foamed light weight filler
agent may be added. In contrast, any of these
components could be mixed with or otherwise receive
various high density filler agents or other weighting
components such as relatively high density fibers or
particulate agents in order to increase their mass or
weight.
The following commercially available
thermoplastic resins are particularly preferred for use
in the noted dual cores employed in the golf balls of
the present invention: Capron 8351 (available from
Allied Signal Plastics), Lexan ML5776 (from General
Electric), Pebax 3533 (a polyether block amide from Elf
Atochem), and Hytrel 64074 (from DuPont). Properties of
these four preferred thermoplastics are set forth below
in Tables 10-13. When forming a golf ball in accordance
with the present invention, if the interior center
component of the dual core is to comprise a
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 47 -
thermoplastic material, it is most preferred to utilize
Pebax thermoplastic resin.
TABLE 10
CAPRON 8351
DAM 50%RH ASTM Test
MECHANICAL
Tensile Strength, Yield, psi (MPa) 7,80 0 (54) D-638
--
Flexural Strength, psi IMPa 9,500 (65) -- D-790
Flexural Modulus, psi (MPa) 230,000 (1,585)D-790
--
1 ~ Ultimate Elongation, % 200 -- D-638
Notched Izod Impact, ft-lbs/in (J/M) No Break -- D-256
Drop Weight Impact, ft-lbs (J) 150 (200) -- D-3029
Drop weight Impact, C -40F, ft-lbs (J) 150 (200) -- D-3029
PHYSICAL
Specific Gravity 1.07 -- D-792
THERMAL
Melting point, F (C) 420 (215) -- D-789
Heat Deflection ~ 264 psi F (C) 140 (60) -- D-648
TABLE 11
20 Lexan ML5776
PROPERTY TYPICAL DATAUNIT METHOD
MECHANICAL
Tensile Strength, yield, Type 850D psi ASTM 638
I, 0.125" D
Tensile Strength, break, Type 9500 psi ASTM 638
I, 0.125" D
2 5 Tensile Elongation, yield, 110.0 % ASTM 638
Type I, D
0.125'
Flexural Strength, yield, 0.125" 12000 psi ASTM 79D
D
Flexural Modulus, 0.125" 310000 psi ASTM 790
D
IMPACT
3 ~ Izod Impact, unnotched, 73F 60.0 ft-lb/in ASTM 4812
D
Izod Impact, notched, 73F 15.5 ft-lb/in ASTM 256
D
Izod Impact, notches 73F, 0.250" 12.0 ft-lb/in ASTM 256
D
SUBSTITUTE SHEET (RULE 26)
ICA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
48
Instrumented Impact Energy 48.0 ft-lbs ASTM D 3763
Q Peak, 73F
THERMAL
HDT, 264 psi, 0.250", unannealed257 deg F ASTM D 648
Thermal Index, Elec Prop 80 deg C UL 7468
Thermal Index, Mech Prop with 80 deg C UL 7468
Impact
Thermal Index, Mech Prop without80 deg C UL 7468
Impact
PHYSICAL
Specific Gravity, solid 1.19 - ASTM D 792
Water Absorption, 24 hours 0.150 % ASTM D 570
~ 73F
1 Mold Shrinkage, flow, 0.125" 5.7 in/in E-3 ASTM D 955
O
Melt Flow Rate, nom'1, 300C/l.2kgf(0)7.5 g/10 min ASTM D 1238
FLAME CHARACTERISTICS
UL File Number, USA E121562 -
94HB Rated Stested thickness) 0.060 inc h ULg4
TABLE 12
PEBAX~ RESINS
ASTM
TEST
2 PROPERTY
O
METHOD UNITS 3533
Specific Gravity D792
Water Absorption
Equilibrium
0.5
(20C, 50% R.H.>)
2 24 Hr. Immersion D570
5
1.2
Hardness D2240 35D
Tensile Strength, UltimateD638 psi 5600
Elongation, Ultimate D638 % 580
Flexural Modulus D790 i
ps 2800
3 mpact, Notc'heed D256 ft-
O IZ
C lb./in. NH
-40oC
NB
Abrasion Resistance D1044 Mg/1000 104
H18/1000g Cycles
3 Tear Resistance NotchedD624C lb./in. 260
5
Melting Point D3418 F 306
Vicat Softening Point D1525 F 165
HDT 66 psi D648 F 115
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PGT/US98/06159
- 49 -
Compression Set
(24 hr., 160°F) D395A % 54
TABLE 13
HYTREL 64074
Thermoplastic Elastomer
PHYSICAL
Dens/Sp Gr ASTM D792 1.1800 s
p gr 23/23C
Melt Flow ASTM D1238 5.20 ~E - 190 C/2.16 kg g/10/min
Wat Abs ASTM D570 2.100 %
MECHANICAL
Elong~Brk ASTM D638 ~ 230.0%
Flex Mod ASTM D790 9500psi
TnStr~Brk ASTM D638 2000psi
IMPACT
Notch Izod ASTM D256 No Break ~ 73.0 F X0.2500 inft-lb/in
0.50 C~ -40.0 F Q0.2500 inft-lb/in
HARDNESS
Shore ASTM D2240 40 Shore D
2 0 THERMAL
DTUL066 ASTM D648 122 F
Melt Point 338.0 F
Vicat Soft ASTM D1525 248 F
Melt Point
The cores of the inventive golf balls
typically have a coefficient of restitution of about
0.750 or more, more preferably 0.770 or more and a PGA
compression of about 90 or less, and more preferably 70
or less. The cores have a weight of 25 -40 grams and
preferably 30 - 40 grams. The core can be compression
molded from a slug of uncured or lightly cured elastomer
composition comprising a high cis content polybutadiene
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PC"T/US98/06159
- 50 -
and a metal salt of an a, (3, ethylenically unsaturated
carboxylic acid such as zinc mono- or diacrylate or
methacrylate. to achieve higher coefficients of
restitution and/or to increase hardness in the core, the
manufacturer may include a small amount of a metal oxide
such as zinc oxide. In addition, larger amounts of
metal oxide than are needed to achieve the desired
coefficient may be included in order to increase the
core weight so that the finished ball more closely
approaches the U.S.G.A. upper weight limit of 1.620
ounces. Non-limiting examples of other materials which
may be used in the core composition including compatible
rubbers or ionomers, and low molecular weight fatty
acids such as stearic acid. Free radical initiator
catalysts such as peroxides are admixed with the core
composition so that on the application of heat and
pressure, a curing or cross-linking reaction takes
place.
Wound cores are generally produced by winding
a very long elastic thread around a solid or liquid
filled balloon center. The elastic thread is wound
around the center to produce a finished core of about
1.4 to 1.6 inches in diameter, generally. However, the
preferred embodiment golf balls of the present invention
preferably utilize a solid core, or rather a solid dual
core configuration, as opposed to a wound core.
Method of Makincr Golf Ball
In preparing golf balls in accordance with the
present invention, a hard inner cover layer is molded
(by injection molding or by compression molding) about a
core (preferably a solid core, and most preferably a
dual core). A comparatively softer outer layer is
molded over the inner layer.
The dual cores of the present invention are
preferably formed by compression molding techniques.
However, it is fully contemplated that liquid injection
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98143709 PCTNS98106159
- 51 -
molding or transfer molding techniques could be
utilized.
For purposes of example, a preferred method of
making the golf ball 45 depicted in FIGURE 4 is as
follows. Specifically, a thermoset material, i.e. a
core layer 42, is formed about an inner core component
40 comprising a thermoplastic material as follows:
Referring to FIGURE 7, preforms 75 of a thermoset
material, i.e. utilized to form the core layer 42, are
l0 preheated in an oven for one-half hour at 170°F and
placed in the bottom 73 of a molding assembly 70. A
Teflon-coated plate 75 with two hemispheres 77 and 78,
each about 0.840 inches in diameter, is placed on top of
the preforms. Additional preforms, preheated as
described above, are placed in the corresponding
cavities of a top mold 72. The bottom mold 73 is
engaged with the top mold 72 and the assembly flipped or
otherwise inverted. The bottom one half of the mold
assembly 70 then becomes the top one half of the mold
assembly. The mold assembly 70 is then placed in a
press and cold formed at room temperature using
approximately 10 tons of pressure in a steam press. The
molding assembly 70 is closed for approximately two
minutes and pressure released. The molding assembly 70
is then opened and the Teflon plate 76 is removed
thereby leaving one or more essentially perfectly formed
one-half shells in cavities in the thermoset material.
Previously formed thermoplastic core centers are then
placed in the bottom cavities and the top portion 72 of
the molding assembly 70 is placed on the bottom 73 and
the materials disposed therebetween cured. The golf
ball produced by this method had an inner core diameter
of 0.840 inches in diameter. The outer core diameter
. had a final diameter of 1.470 inches, and a pre-mold
diameter of 1.490 inches. A relatively hard inner cover
layer is then molded about the resulting dual core
component. The diameter of the inner cover was 1.570
SUB8T1TUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98143709 PCTIUS98/06159
- 52 -
inches. A comparatively softer outer cover layer is
then molded about the inner cover layer. The outer
cover diameter was 1.680 inches. Details of molding the
inner and outer covers are set forth below.
Four golf balls in accordance with the present
invention were formed, each using a preferred and
commercially available high melting point thermoplastic
material as an inner core component. Table 14, set
forth below, summarizes these balls.
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
53
v m
~n ~ M o
O M O1 ch O
r-i O
U
O 01 N tn u1 M O O
~ I I I I O ~ ~ ~ CO ~ O O
N I ~ ~ CV ~ I~ N
r-1 I I I I Lf1 t11 l ~
I OD C
~ N N
t-I
O p lf1M ri
,
U '-I '-a '-i
ri
U7
v
r~ r~ I
v ~ M
L''
r~i Lfl 01 M N rl C4 1~
~-I M 00 ,-1 rl l0 ~ ~
O M I~ d' ~
M N L~ l0 O Q
JJ ~ lp t~ ~ N rl ~ ~ t~ ~ In r~ N
d~ V~ N ~ 01 t~ CO C'
x O ~ ''-~''~ ,..i r;
C7 ~' ' ~
O
.,.
.p.J fx
M O S-1
-r1
o ca ya
k
L~ Ul ~
.L~ 0
r, .x ro ~
o ~ , 0 0
. v~ ~~~
O
Ll1 l0 tf1 ~ N ~-I ~ ~ l~ ~ lfl ~ '~ 1J
M N ~~ 01 L~ 00 L~ U1 .~".,
f3~ O ~ r-~r-i '-'~~ d~ ~
. "
7" D W
U7
r
01 W
M
Lf1 .
I ~ ~ ~ 00 ~ tI1
.S',y-1 ('~1 p lD l M
I M ~
flS . ' 00 0 O N ~ ' O O l0
I~ I OD ~ N .-1 O ~ L!1
N t~ CO 00 lD
' to
a o vo O ~ ,
~ ~ M
E-~ a
a
~mn o
~-I ~ M OD O l~ l0 ~ ~ p~ ~ ~ N d' O O
~~ I t!1 O ~ pp ~ d~ d1
~ , l~ W~ ~ N rl ~ l~ ~ N Lf1 ~-I O
O N I~ lp ~ L!7
I l~ l~
U O O ,-~ M ,.~ ~'
l0 ' .
,--~
N
O v v
.,-I
r--I r--i
N N rd
~ U U ~ v
_ wu ra ~ ~ ~.. ~-I ,..,
U~ o w y~
w ~ v
~i ~
E o ~ y~ . . W E u~ E
rt3 ?~ v r>~ v ra o 0 0 0
.s; S-I O N f ~ O
v (ll ~
U7
-1 .~ ~.1 .~: S1 d~ r-1
U rJl oN~ -1 O O N N
'-' ~-- f3~ b U Ol-ri U CJl- O
(ZS U -I '~
. l 01 r
v T3U~1 d~.k~-~a ~vm ~ N ? ri
~~000~*
~ I O m - . ~" ~
'O v -- ~ '~" t
v " E
N v r- ~ ~ ~~ .,
v rno ~I y~ ~
a
U U U v tns~ v
N ''"~ tIW.. N -ri .,
~ O O ~'. L; E U N
r-I i E
3:
r i4 S-t
-'-r v -~-I .-I w v O f ~-I ~-I
N ~ .~ -~ ~ O -.i N ~1l
M O O
3 S~ c~ U N N cn 3 m 3 U u~ u~ to
tn N N U U U cn E-~
0 ~ v r-I r-1 ~
o s~ ~n
~ . ~ m x ~-.~
O O u~
U O ,~ ra N U rd r-1
U ~
U t~ ~ ~ ~ ~ 4i
N ~ ~ ~ v~ O .~
N
O N N '?
O w A G1 ~ ~ O ~ .t1
U ~- c~
SUBSTITUTE SHEET (RULE 2$)
CA 02283788 1999-09-09
WO 98143709 PCT/US98/06159
- 54 -
Generally, the inner cover layer which is
molded over the core, or preferably a dual core
component, is about 0.01 inches to about 0.10 inches in
thickness, preferably about 0.03-0.07 inches thick. The
inner ball which includes the core and inner cover layer
preferably has a diameter in the range of 1.25 to 1.60
inches. The outer cover layer is about 0.01 inches to
about 0.10 inches in thickness. Together, the core, the
inner cover layer and the outer cover layer combine to
form a ball having a diameter of 1.680 inches or more,
the minimum diameter permitted by the rules of the United
States Golf Association and weighing no more than 1.62
ounces.
Most preferably, the resulting golf balls in
accordance with the present invention have the following
dimensions:
Size Specifications: Preferred Most Preferred
Inner Core - Max. 1.250" 1.00"
- Min. 0.500" 0.70"
Outer Core - Max. 1.600" 1.570"
- Min. 1.500" 1.550"
(1) Cover Thickness
(Total)
- Max. 0.090" 0.065"
- Min. 0.040" 0.055"
In a particularly preferred embodiment of the
invention, the golf ball has a dimple pattern which
provides coverage of 650 or more. The golf ball
typically is coated with a durable, abrasion-resistant,
relatively non-yellowing finish coat.
The various cover composition layers of the
present invention may be produced according to
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 55 -
conventional melt blending procedures. Generally, the
copolymer resins are blended in a Banbury type mixer,
two-roll mill, or extruder prior to neutralization.
After blending, neutralization then occurs in the melt or
molten states in the Banbury mixer. Mixing problems are
minimal because preferably more than 75 wt %, and more
preferably at least 80 wt °s of the ionic copolymers in
the mixture contain acrylate esters and, in this respect,
most of the polymer chains in the mixture are similar to
each other. The blended composition is then formed into
slabs, pellets, etc., and maintained in such a state
until molding is desired. Alternatively, a simple dry
blend of the pelletized or granulated resins which have
previously been neutralized to a desired extent and
colored 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 such as
an inorganic filler, etc., may be added and uniformly
mixed before initiation of the molding process. A
similar process is utilized to formulate the high acid
ionomer resin compositions used to produce the inner
cover layer. In one embodiment of the invention, a
masterbatch of non-acrylate ester-containing ionomer with
pigments and other additives incorporated therein is
mixed with the acrylate ester-containing copolymers in a
ratio of about 1 - 7 weight s masterbatch and 93 - 99
weight % acrylate ester-containing copolymer.
The golf balls of the present invention can be
produced by molding processes which include but are not
limited to those which are currently well known in the
golf ball art. For example, the golf balls can be
produced by injection molding or compression molding the
. novel cover compositions around a wound or solid molded
core to produce an inner ball which typically has a
diameter of about 1.50 to 1.67 inches. The core,
preferably of a dual core configuration, may be formed as
SUBSTITUTE SHEET (RUt,E 26j
I
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06159
- 56 -
previously described. The outer layer is subsequently
molded over the inner layer to produce a golf ball having
a diameter of 1.620 inches or more, preferably about
1.680 inches or more. Although either solid cores or
wound cores can be used in the present invention, as a
result of their lower cost and superior performance solid
molded cores are preferred over wound cores. The
standards for both the minimum diameter and maximum
weight of the balls are established by the United States
Golf Association (U.S.G.A.).
In compression molding, the inner cover
composition is formed via injection at about 380°F to
about 450°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° to 300°F for about 2 to 10
minutes, followed by cooling at 50° to 70°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° to about
100°F. Subsequently, the outer cover layer is molded
around 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.
After molding, the golf balls produced may
undergo various further processing steps such as buffing,
painting and marking as disclosed in U.S. Patent No.
4,911,451.
The resulting golf ball produced from the hard
inner layer and the relatively softer, low flexural
modulus outer layer provide for an improved multi-layer
golf ball having a unique dual core configuration which
provides for desirable coefficient of restitution and
durability properties while at the same time offering the
SUBSTITUTE SHEET (RULE 26)
CA 02283788 1999-09-09
WO 98/43709 PCT/US98/06I59
- 57 -
feel and spin characteristics associated with soft balata
and balata-like covers of the prior art.
The invention has been described with reference
to the preferred embodiments. Obviously, modifications
and alterations will occur to others upon a reading and
understanding the preceding detailed description. It is
intended that the invention be construed as including all
such modifications and alterations in so far as they come
within the scope of the appended claims or the
equivalents thereof.
suBSgHeFf (RUB zs~
