U.S. patent application number 10/159329 was filed with the patent office on 2003-12-04 for golf ball intermediate layer.
Invention is credited to Kim, Hyun Jin, Snell, Dean A..
Application Number | 20030224871 10/159329 |
Document ID | / |
Family ID | 29582878 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030224871 |
Kind Code |
A1 |
Kim, Hyun Jin ; et
al. |
December 4, 2003 |
Golf ball intermediate layer
Abstract
A golf ball intermediate layer consists essentially of a
specified triblock copolymer or its hydrogenation product, a
specified block copolymer, or mixtures of these. The layer
unexpectedly provides for improved ball performance with respect to
spin rate, feel, and durability, without the expected disadvantages
of use of such a layer. The layer can be incorporated into a wide
variety of known ball constructions.
Inventors: |
Kim, Hyun Jin; (Carlsbad,
CA) ; Snell, Dean A.; (Oceanside, CA) |
Correspondence
Address: |
SHEPPARD, MULLIN, RICHTER & HAMPTON LLP
333 SOUTH HOPE STREET
48TH FLOOR
LOS ANGELES
CA
90071-1448
US
|
Family ID: |
29582878 |
Appl. No.: |
10/159329 |
Filed: |
May 29, 2002 |
Current U.S.
Class: |
473/351 ;
525/316 |
Current CPC
Class: |
C08L 51/006 20130101;
C08L 2666/02 20130101; C08L 53/00 20130101; C08L 53/00 20130101;
A63B 37/0052 20130101; C08L 53/025 20130101; A63B 37/0047 20130101;
C08L 53/025 20130101; C08L 51/006 20130101; B32B 25/14 20130101;
A63B 37/0003 20130101; A63B 37/0046 20130101; A63B 37/0045
20130101; C08L 53/025 20130101; C08L 51/006 20130101; C08L 2666/02
20130101 |
Class at
Publication: |
473/351 ;
525/316 |
International
Class: |
A63B 037/00 |
Claims
We claim:
1. A golf ball intermediate layer consisting essentially of: one or
more triblock copolymers; one or more hydrogenation products of the
triblock copolymers; one or more hydrogenated diene block
copolymers; or mixtures thereof; wherein each triblock copolymer
has (i) a first polymer block comprising an aromatic vinyl
compound, (ii) a second polymer block comprising a conjugated diene
compound, and (iii) a hydroxyl group located at a block copolymer,
wherein each hydrogenated diene block copolymer has a
polystyrene-reduced number-average molecular weight of from 50,000
to 600,000 and is a hydrogenation product of (i) an A-B block
copolymer, in which A is an alkenyl aromatic compound polymer
block, and B is either (1) a conjugated diene homopolymer block,
wherein the vinyl content of the conjugated diene portion is more
than 60%, or (2) an alkenyl aromatic compound-conjugated diene
random copolymer block wherein the vinyl content of the conjugated
diene portion is 15-60%, or (ii) an A-B-C block copolymer, in which
A and B are as defined above and C is an alkenyl aromatic
compound-conjugated diene copolymer tapered block, wherein the
proportion of the alkenyl aromatic compound increases gradually, or
(iii) an A-B-A block copolymer, in which A and B are as defined
above, wherein in each of the hydrogenated diene block copolymers,
the weight proportion of the alkenyl aromatic compound to
conjugated diene is from 5/95 to 60/40, the content of the bound
alkenyl aromatic compound in at least one block A is at least 3% by
weight, the total of the bound alkenyl aromatic compound contents
in the two block A's or the block A and the block C is 5% to 25% by
weight based on the total monomers, and at least 80% of the double
bond unsaturations of the conjugated diene portion is saturated by
the hydrogenation.
2. A golf ball intermediate layer as defined in claim 1, wherein
the aromatic vinyl compound is selected from the group consisting
of styrene, methylstyrene, 4-propylstyrene, 1,3-dimethylstyrene,
vinylnaphthalene, and vinlyanthracene.
3. A golf ball intermediate layer as defined in claim 1, wherein
the conjugated diene compound is selected from the group consisting
of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene,
1,3-pentadiene, and 1,3-hexadiene.
4. A golf ball intermediate layer as defined in claim 1, wherein
each of the one or more triblock copolymers has a number average
molecular weight between about 30,000 and about 1,000,000.
5. A golf ball intermediate layer as defined in claim 1, wherein
the ratio by weight of the triblock copolymers to the hydrogenated
diene block copolymers ranges between 99:1 and 1:99.
6. A golf ball intermediate layer as defined in claim 1, further
comprising fillers, stabilizers, colorants, processing aids,
antioxidants, or mixtures thereof.
7. A golf ball intermediate layer as defined in claim 6, wherein
the fillers have specific gravity of greater than about 2.
8. A golf ball comprising a core, a cover, and an intermediate
layer as defined in claim 1 situated between the core and the
cover.
9. A golf ball as defined in claim 8, wherein the core comprises an
inner core and one or more outer cores encasing the inner core.
10. A golf ball as defined in claim 8, wherein the core comprises
liquid.
11. A golf ball as defined in claim 8, further comprising one or
more layers situated between the core and the cover.
12. A golf ball as defined in claim 8, further comprising a layer
of rubber thread situated between the core and the cover.
13. A golf ball as defined in claim 8, wherein the cover comprises
copolymeric ionomer, terpolymeric ionomer, or mixtures thereof.
14. A golf ball as defined in claim 8, wherein the cover comprises
elastomeric material.
15. A golf ball intermediate layer as defined in claim 1, wherein
the intermediate layer has a thickness between about 0.005 in. and
about 0.1 in.
16. A golf ball intermediate layer as defined in claim 15, wherein
the intermediate layer has a thickness between about 0.01 in. and
about 0.05 in.
17. A golf ball intermediate layer as defined in claim 16, wherein
the intermediate layer has a thickness between about 0.02 in. and
about 0.05 in.
18. A golf ball intermediate layer as defined in claim 1, wherein
the intermediate layer is prepared using injection molding.
19. A golf ball intermediate layer as defined in claim 1, wherein
the intermediate layer is prepared using compression molding.
20. A golf ball intermediate layer as defined in claim 1, wherein
the intermediate layer is prepared by depositing a powder material
over a golf ball portion.
21. A golf ball intermediate layer consisting essentially of a
triblock copolymer, the triblock copolymer having (a) a first
polymer block comprising styrene or .alpha.-methylstyrene, (b) a
second polymer block comprising isoprene or 1,3-butadiene, and (c)
a hydroxyl group located at a block copolymer, or a hydrogenation
product of the triblock copolymer, or mixtures thereof.
22. A golf ball intermediate layer as defined in claim 21, wherein
the intermediate layer has a thickness of about 0.1 in.
23. A golf ball intermediate layer consisting essentially of one or
more hydrogenated diene block copolymers, wherein each hydrogenated
diene block copolymer has a polystyrene-reduced number-average
molecular weight of from 50,000 to 600,000 and is a hydrogenation
product of (i) an A-B block copolymer, in which A is an alkenyl
aromatic compound polymer block, and B is either (1) a conjugated
diene homopolymer block, wherein the vinyl content of the
conjugated diene portion is more than 60%, or (2) an alkenyl
aromatic compound-conjugated diene random copolymer block wherein
the vinyl content of the conjugated diene portion is 15-60%, or
(ii) an A-B-C block copolymer, in which A and B are as defined
above and C is an alkenyl aromatic compound-conjugated diene
copolymer tapered block, wherein the proportion of the alkenyl
aromatic compound increases gradually, or (iii) an A-B-A block
copolymer, in which A and B are as defined above, wherein in each
of the hydrogenated diene block copolymers, the weight proportion
of the alkenyl aromatic compound to conjugated diene is from 5/95
to 60/40, the content of the bound alkenyl aromatic compound in at
least one block A is at least 3% by weight, the total of the bound
alkenyl aromatic compound contents in the two block A's or the
block A and the block C is 5% to 25% by weight based on the total
monomers, and at least 80% of the double bond unsaturations of the
conjugated diene portion is saturated by the hydrogenation.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to golf ball intermediate
layers and, more particularly, to golf ball intermediate layers
made from a composition that optimizes ball performance.
[0002] Golf balls generally include a core and at least one cover
layer surrounding the core. Balls can be classified as two-piece,
wound, or multi-layer balls. Two-piece balls include a spherical
inner core and an outer cover layer. Wound balls include a core, a
rubber thread wound under tension around the core to a desired
diameter, and a cover layer, typically of balata material.
Multi-layer balls include a core, a cover layer, and one or more
intermediate layers. Generally, two-piece balls have good
durability and ball distance when hit, but poor "feel"--the overall
sensation transmitted to the golfer while hitting the ball--and low
spin rate, which results in poor ball control. Wound balls having
balata covers generally have high spin rate, leading to good
control, and good feel, but they have short distance and poor
durability in comparison to two-piece balls. A good way to optimize
the requirements of good speed, spin, feel, and durability is
through a multi-layer construction.
[0003] Multi-layer balls generally have performance characteristics
between those of two-piece and wound balls; that is, multi-layer
balls exhibit distance and durability inferior to two-piece balls
but superior to wound balata balls, and they exhibit feel and spin
rate inferior to wound balata balls but superior to two-piece
balls. In particular, use of an intermediate layer to improve spin
rate often can lead to substantial loss of ball speed, and
therefore distance. Therefore, efforts have focused on designing
intermediate layers for golf balls on producing layers that provide
high spin rate without loss of ball distance or durability. These
efforts have not met with complete success.
[0004] Material characteristics of the compositions used in any
intermediate layer in multi-layer balls are among the important
factors that determine the performance of the resulting golf balls.
In particular, the composition of intermediate layers is important
in determining the ball's speed and spin rate. Various materials
having different physical properties are used to make intermediate
layers to create a ball having the most desirable performance
possible. Most intermediate layers incorporate soft or hard
ionomeric resins. Such ionomeric resins generally are ionic
copolymers of an olefin and a metal salt of a unsaturated
carboxylic acid, or ionomeric terpolymers having a co-monomer
within its structure. These resins vary in resiliency, flexural
modulus, and hardness. Examples of these resins include those
marketed under the name SURLYN manufactured by E. I. DuPont de
Nemours & Company of Wilmington, Del., and IOTEK manufactured
by Exxon Mobil Corporation of Irving, Tex. Many intermediate layers
also incorporate elastomeric resins along with the ionomeric
layers. Elastomeric resins used in golf ball covers include a
variety of thermoplastic or thermoset elastomers available.
Examples of these elastomers include those marketed under the name
PEBAX manufactured by Atofina Chemicals of Philadelphia, Pa. Other
materials commonly used in intermediate layers include polyester
elastomer, such as HYTREL, manufactured by E. I. DuPont de Nemours
& Company, and thermoplastic urethane, such as ESTANE,
manufactured by BF Goodrich of Cleveland, Ohio.
[0005] Each of the materials discussed above has particular
characteristics that can lead to good golf ball properties when
used in an intermediate layer. However, none of these materials
optimizes all of the important properties of a ball intermediate
layer, and improvement of one of these properties by use of a
particular material often can lead to worsening of another.
Therefore, to improve golf ball properties, some of the materials
discussed above are blended to produce improved intermediate
layers. As discussed above, ideally an intermediate layer should
provide good spin rate, without sacrificing the ball's speed.
Therefore, an ionomer often is combined in an intermediate layer
with an elastomer. In fact, most non-wound intermediate layers
incorporate ionomer resins. The resulting blend will provide
acceptable ball spin and speed. A number of patents disclose
preferred intermediate layers incorporating elastomers and ionomer
resins.
[0006] A particular material that has been disclosed for use in
golf ball compositions is a triblock copolymer having a first
polymer block comprising an aromatic vinyl compound, a second
polymer block comprising a conjugated diene compound, and a
hydroxyl group located at a block copolymer, or the hydrogenation
product of this triblock copolymer. The hydroxyl group can be at
the terminal block copolymer or elsewhere in the block copolymer
structure. The aromatic vinyl compound preferably is selected from
the group consisting of styrene, methylstyrene, 4-propylstyrene,
1,3-dimethylstyrene, vinylnaphthalene, and vinlyanthracene. The
conjugated diene compound preferably is selected from the group
consisting of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene,
1,3-pentadiene, and 1,3-hexadiene. The triblock copolymer
preferably has a number average molecular weight between about
30,000 and about 1,000,000. An example of this material in which
the triblock copolymer having a hydroxyl group is located at the
terminal block copolymer is sold under the trade name HG-252 by
Kuraray Company of Kurashiki, Japan.
[0007] The material is described in detail in U.S. Pat. No.
5,693,711 to Akiba et al. ("the Akiba '711 patent"), herein
incorporated by reference. The Akiba '711 patent discloses and
claims compositions incorporating the specified triblock polymer
and ionomer, as well as golf ball cover compositions incorporating
both of these, with the weight ratio of ionomer to block polymer
ranging from 98:2 to 50:50. The disclosed cover composition
provides flexibility and toughness to the ball cover. The Akiba
'711 patent does not, however, discuss use of the material in
intermediate layers, or compositions incorporating the triblock
copolymer without also incorporating ionomer.
[0008] A patent that illustrates the prior understanding of use of
the specified triblock copolymer in intermediate layers for golf
balls is U.S. Pat. No. 5,948,862 to Sano et al., which discloses
use in intermediate layers of thermoplastic elastomer having
terminal OH groups, such as the specified triblock copolymer, only
in combination with ionomer or specified block copolymers. Also,
U.S. Pat. No. 6,334,820 B 1 to Sasaki discloses and claims golf
ball intermediate layers incorporating the specified triblock
copolymer and a hard ionomer having specified hardness and flexural
modulus. The hard ionomer is described as providing the resulting
ball with increased resilience. This is consistent with the
previous understanding of use of the triblock copolymer as
requiring blending with a hard polymer, such as the hard ionomers
specified in the Sasaki patent, to avoid poor resilience in the
resulting balls.
[0009] It has been demonstrated that the specified triblock
copolymer, like most elastomers, can be used to make satisfactory
golf ball intermediate layer when blended with hard,
non-elastomeric materials, such as high acid copolymeric ionomers.
However, even with blending of materials to improve properties, use
of the materials discussed above is not completely satisfactory. In
general, it is difficult to make an intermediate layer that
provides good performance without blending into the layer
non-elastomeric materials, such as copolymeric ionomers having high
acid-content copolymers. Also, the need to blend these materials
itself provides for possible manufacturing difficulties and the
need for increased monitoring and quality control during the
manufacturing process.
[0010] In view of the above discussion, it is apparent that golf
ball intermediate layers are needed that allow the optimization of
many ball performance properties without the worsening of other
properties. The ball intermediate layers also should provide little
or no processing and preparation difficulties. The present
invention fulfills this need and other needs, and provides further
related advantages.
SUMMARY OF THE INVENTION
[0011] The present invention is embodied in a golf ball
intermediate layer consisting essentially of one or more specified
triblock polymers, hydrogenation products of these triblock
copolymers, or specified block copolymers, or mixtures of these.
Each of the triblock copolymers and their hydrogenation products
incorporate: a first polymer block comprising an aromatic vinyl
compound; a second polymer block comprising a conjugated diene
compound; and a hydroxyl group located at a block copolymer. Each
block copolymer is a hydrogenated diene block copolymer having a
polystyrene-reduced number-average molecular weight of from 50,000
to 600,000. Each hydrogenated diene block copolymer is a
hydrogenation product of: (a) an A-B block copolymer, in which A is
an alkenyl aromatic compound polymer block, and B is either a
conjugated diene homopolymer block, in which the vinyl content of
the conjugated diene portion is more than 60%, or an alkenyl
aromatic compound-conjugated diene random copolymer block in which
the vinyl content of the conjugated diene portion is from 15% to
60%, or; (b) an A-B-C block copolymer, in which A and B are as
defined above, and C is an alkenyl aromatic compound-conjugated
diene copolymer tapered block in which the proportion of the
alkenyl aromatic compound increases gradually, or; (c) an A-B-A
block copolymer in which A and B are as defined above. In each
block copolymer, the weight proportion of the alkenyl aromatic
compound to conjugated diene is from 5/95 to 60/40, and the content
of the bound alkenyl aromatic compound in at least one block A is
at least 3% by weight, and the total of the bound alkenyl aromatic
compound contents in the two block A's or the block A and the block
C is from 5% to 25% by weight based on the total monomers. Also, in
the hydrogenated diene block copolymer, which as described above is
a hydrogenation product, at least 80% of the double bond
unsaturations of the conjugated diene portion is saturated by the
hydrogenation.
[0012] In each triblock copolymer, the aromatic vinyl compound
preferably is selected from the group consisting of styrene,
methylstyrene, 4-propylstyrene, 1,3-dimethylstyrene,
vinylnaphthalene, and vinlyanthracene, and the conjugated diene
compound preferably is selected from the group consisting of
1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene,
1,3-pentadiene, and 1,3-hexadiene. Each triblock copolymer
preferably has a number average molecular weight between about
30,000 and about 1,000,000. Preferably, the ratio by weight of
triblock copolymer to hydrogenated diene block copolymer ranges
between 99:1 and 1:99.
[0013] The intermediate layer can further comprise fillers,
stabilizers, colorants, processing aids, antioxidants, or mixtures
of these. The fillers used can be heavy fillers having specific
gravity greater than about 2. The present invention also is
embodied in a golf ball incorporating a core, a cover, and the
above-specified intermediate layer situated between the core and
the cover. In these golf balls, the core can include an inner core
and one or more outer cores encasing the inner core. The core also
can include liquid. The golf ball can incorporate one or more
layers situated between the core and the cover, or a layer of
rubber thread situated between the core and the cover. The ball
covers can include copolymeric ionomer, terpolymeric ionomer, or
mixtures thereof. The ball covers also can include elastomeric
material.
[0014] Preferably, the intermediate layer of the present invention
has a thickness between about 0.005 in. and about 0.1 in, more
preferably between about 0.01 in. and about 0.05 in., and most
preferably between about 0.02 in. and about 0.05 in. The
intermediate layer can be prepared using injection molding,
compression molding, or by depositing a powder material over a golf
ball portion.
[0015] The present invention also resides in an intermediate layer
consisting essentially of the above-specified triblock copolymer,
in which the aromatic vinyl comprises styrene or a-methylstyrene
and the conjugated diene compound comprises isoprene or
1,3-butadiene, preferably having a thickness of about 0.1 inches.
The present invention also resides in an intermediate layer
consisting essentially of the above-specified block copolymers.
[0016] Other features and advantages of the present invention
should become apparent from the following detailed description of
the preferred embodiments.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] The present invention resides in an intermediate layer for a
golf ball that consists essentially of one or more specified
triblock polymers, hydrogenation products of these triblock
copolymers, or specified block copolymers, or mixtures of these.
Therefore, the intermediate layer is substantially free of
non-elastomeric (particularly ionomeric) polymers. The intermediate
layer provides for excellent golf ball properties without
introducing processing difficulties. As described above, each
triblock copolymer incorporates: a first polymer block comprising
an aromatic vinyl compound; a second polymer block comprising a
conjugated diene compound; and a hydroxyl group located at a block
copolymer, or a hydrogenation product of the triblock copolymer, or
mixtures of these. The aromatic vinyl compound preferably is
selected from the group consisting of styrene, methylstyrene,
4-propylstyrene, 1,3-dimethylstyrene, vinylnaphthalene, and
vinlyanthracene, and the conjugated diene compound preferably is
selected from the group consisting of 1,3-butadiene, isoprene,
2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Each
triblock copolymer preferably has a number average molecular weight
between about 30,000 and about 1,000,000.
[0018] In view of the prior understanding and disclosures
discussing use of the specified triblock copolymer in ball
compositions, it has been surprisingly found that this triblock
copolymer can be used successfully as essentially the entire
composition of an intermediate layer. As discussed above, prior
understanding of ball manufacture has been that the specified
triblock copolymer are preferred for use in golf ball layers only
when blended with harder polymers, typically high acid-content
copolymeric ionomers. This blending has been considered necessary,
because the softness of the specified triblock polymer has made it
apparently unsuitable for its exclusive use in intermediate layers.
Generally, soft elastomeric materials in ball compositions have
contributed to improved feel and spin rate of the resulting balls,
at the expense of ball speed. Addition of ionomers, particularly
copolymeric ionomers, to these compositions has been believed
necessary to produce balls having acceptable speed when hit.
[0019] In view of the above, it has been surprisingly observed that
use of a composition consisting essentially of the specified
triblock copolymer in an intermediate layer unexpectedly provides
for superior ball properties. These superior properties exist
despite the common perception that ball layers incorporating only a
soft elastomer, such as the specified triblock copolymer, would
produce balls having unacceptable properties, such as a low
coefficient of restitution and resulting low ball speed. This
perception is reflected in the patents previously discussed
incorporating soft elastomers blended with harder components. In
contrast to these patents, the intermediate layers of the present
invention are free of harder bulk polymer materials, such as high
acid-content ionomers.
[0020] It also has been found that, in addition to the
above-specified triblock copolymer, an additional type of specified
block copolymer can be used in ball intermediate layers, either
alone, or in combination with the specified triblock copolymer, to
produce intermediate layers having improved properties. This
specified block copolymer is described in U.S. Pat. Nos. 5,191,024
and 5,306,779, both to Shibata et al. (the "Shibata '024" and
"Shibata '779" patents, respectively), herein incorporated by
reference.
[0021] Each specified block copolymer in the intermediate layer of
the present invention is a hydrogenated diene block copolymer
having a polystyrene-reduced number-average molecular weight of
50,000 to 600,000. Each specified block copolymer is a
hydrogenation product of either: (i) an A-B block copolymer, in
which A is an alkenyl aromatic compound polymer block, and B is
either (1) a conjugated diene homopolymer block, in which the vinyl
content of the conjugated diene portion is more than 60%,
(described in the '024 patent), or (2) an alkenyl aromatic
compound-conjugated diene random copolymer block having 15% to 60%
of vinyl content of the conjugated diene portion (described in the
'779 patent); or (ii) an A-B-C block copolymer in which A and B are
as defined above, and C is an alkenyl aromatic compound-conjugated
diene copolymer tapered block, in which the proportion of the
alkenyl aromatic compound increases gradually; or (iii) an A-B-A
block copolymer in which A and B are as defined above. In the
specified block copolymer, the weight proportion of the alkenyl
aromatic compound to the conjugated diene is from 5/95 to 60/40.
Also, in the specified block copolymer, the content of the bound
alkenyl aromatic compound in at least one block A is at least 3% by
weight, and the total of the bound alkenyl aromatic compound
contents in the two block A's or the block A and the block C is 3%
to 50% by weight based on the total monomers. In the specified
block copolymer, which as stated above is a hydrogenation product,
at least 80% of the double-bond unsaturations of the conjugated
diene portion is saturated by the hydrogenation.
[0022] An intermediate layer within the scope of the present
invention consists essentially of one or more of the
above-specified triblock copolymer or its hydrogenation products,
one or more of the above-specified block copolymer, or a mixture of
these compounds. Preferred mixtures have weight ratios of the
specified triblock copolymer to the specified block copolymer
ranging between 99:1 and 1:99.
[0023] Suitability of the specified block copolymer alone in an
intermediate layer is surprising, because it, like the specified
triblock copolymer, is an elastomeric material considered too soft
to be suitable for use in an intermediate layer without
incorporation of a harder material, such as a copolymeric ionomer.
Likewise, layers consisting essentially of only the specified
triblock copolymer and/or the specified block copolymer are
surprisingly found to provide good ball properties when used in an
intermediate layer.
[0024] In addition to the specified triblock copolymer and/or
specified block copolymer, intermediate layers of the present
invention also can consist of small amounts of materials commonly
added to ball compositions, such as colorants, stabilizers,
antioxidants, processing aids, fillers, or mold release agents.
Compositions within the scope of the present invention also can
incorporate inorganic fillers, such as titanium dioxide, calcium
carbonate, zinc sulfide or zinc oxide. Additional fillers can be
chosen to impart additional density to blends of golf balls and
ball compositions within the scope of the present invention, such
as zinc oxide, barium sulfate, tungsten or any other metallic
powder having density greater than that of base polymeric resin,
preferably having a specific gravity greater than about 2. Any
organic or inorganic fibers, either continuous or non-continuous,
also can be included the compositions. Intermediate layers of the
present invention can be used in a variety of ball designs,
including balls having solid, liquid, or multi-layer cores, with
our without wound layers. Any of these ball configurations can
incorporate an intermediate layer consisting essentially of the
specified triblock copolymer and/or block copolymer.
[0025] Preferred thicknesses for the intermediate layers of the
present invention are between about 0.005 in. and about 0.1 in.,
more preferably between about 0.01 in. and about 0.05 in., and most
preferably between about 0.02 in. and about 0.05 in. Intermediate
layers of the present invention can be prepared using a variety of
methods, including: 1) injection molding of the entire layer, 2)
injection molding to form half cups, which are compression molded
to form the entire layer; compression molding from a sheet of the
material or 3) coating a ball portion with a powder consisting of
the material.
[0026] Balls incorporating intermediate layers of the present
invention can have a wide variety of suitable covers. The specified
triblock copolymer may be used as part of the cover composition, as
well as a variety of ionomeric, non-ionomeric resins, or
combinations of these, known for use in ball covers. Nonlimiting
examples of suitable ionomeric cover materials include copolymeric
ionomers and terpolymeric ionomers, or mixtures of these.
Copolymeric ionomers are obtained by neutralizing at least a
portion of carboxylic groups in a copolymer of an a-olefin and an
.alpha., .beta.-unsaturated carboxylic acid having 3 to 8 carbon
atoms, with a metal ion. Examples of suitable a-olefins include
ethylene, propylene, 1-butene, and 1-hexene. Examples of suitable
unsaturated carboxylic acids include acrylic, methacrylic,
ethacrylic, alphachloroacrylic, crotonic, maleic, fumaric, and
itaconic acid. Copolymeric ionomers include ionomers having varied
acid contents and degrees of acid neutralization, neutralized by
monovalent or bivalent cations, such as lithium, sodium, potassium,
magnesium, calcium, barium, lead, tin, zinc, aluminum, or a
combination of these cations.
[0027] Terpolymeric ionomers suitable as cover materials are
obtained by neutralizing at least portion of carboxylic groups in a
terpolymer of an .alpha.-olefin, and an .alpha.,.beta.-unsaturated
carboxylic acid having 3 to 8 carbon atoms and an
.alpha.,.beta.-unsaturated carboxylate having 2 to 22 carbon atoms
with metal ion. Examples of suitable .alpha.-olefins include
ethylene, propylene, 1-butene, and 1-hexene. Examples of suitable
unsaturated carboxylic acids include acrylic, methacrylic,
ethacrylic, alphachloroacrylic, crotonic, maleic, fumaric, and
itaconic acid. Terpolymeric ionomers include ionomers having varied
acid contents and degrees of acid neutralization, neutralized by
monovalent or bivalent cations, such as lithium, sodium, potassium,
magnesium, calcium, barium, lead, tin, zinc, aluminum, or a
combination of these cations.
[0028] Nonlimiting examples of suitable non-ionomeric polymers for
use as cover materials with balls incorporating intermediate layers
within the scope of the present invention include thermoplastic
elastomer, thermoset elastomer, thermoplastic rubber, thermoplastic
vulcanizate, polycarbonate, polyolefin, polyamide, copolymeric
polyamide, polyesters, polyurethane, polyarylate, polyacrylate,
polyphenyl ether, modified-polyphenyl ether, high-impact
polystyrene, diallyl phthalate polymer, metallocene catalyzed
polymers, acrylonitrile-styrene-butadiene (ABS),
styrene-acrylonitrile (SAN) (including olefin-modified SAN and
acrilonitrile styrene acrylonitrile), styrene-maleic anhydryde
(S/MA) polymer, styrenic copolymer, styrenic terpolymer, cellulose
polymer, liquid crystal polymer (LCP),
ehtylene-propylene-diene-monomer (EPDM), ethylene vinyl acetate
(EVA), and polysiloxane. Suitable polyamides include resins
obtained by: 1) polycondensation of a dicarboxylic acid, such as
oxalic acid, adipic acid, sebacic acid, terephthalic acid,
isophthalic acid or 1,4 cyclohexylidicarboxylic acid, with a
diamine, such as ethylenediamine, tetramethylenediamine,
pentamethylenediamine, hexamethylenediamine or
decamethylenediamine, 1,4-cyclohexyldiamine or m-xylylenediamine,
2) a ring-opening polymerization of cyclic lactam, such as
.epsilon.-caprolactam or .omega.-laurolactam; polycondensation of
an aminocarboxylic acid, such as 6-aminocaproic acid,
9-aminononaoic acid, 11-aminoudecanoic acid or 12-aminododecanoic
acid, or 3) copolymerization of a cyclic lactam with a dicarboxylic
acid and a diamine. Specific examples of suitable polyamides
include Nylon 6; Nylon 4,6; Nylon 6,6; Nylon 6,9; Nylon 6,10; Nylon
6,12; Nylon 11; Nylon 12; copolymerized Nylon; Nylon 6/6, 6; Nylon
6/6, T; Nylon 6, 6/6, 10; and Nylon MXD6
[0029] Examples of suitable non-ionomeric polymers for use in cover
materials with golf balls incorporating intermediate layers within
the scope of the present invention include those sold under the
trademarks LEXAN, VALOX, NORYL, and NORYL GTX, marketed by GE
Plastics of Pittsfield, Mass., CRISTAMID and RILSAN marketed by
ATOFINA Chemicals of Philadelphia, Pa., GRILAMID marketed by
EMS-CHEMIE of Sumter, S.C., ZYTEL marketed by E. I. DuPont de
Nemours & Co. of Wilmington, Del., TENITE marketed by Eastman
Chemical Company of Kingsport, Tenn., EXXPOL marketed by Exxon
Mobil of Houston, Tex., and ESTANE marketed by B F Goodrich of
Cleveland, Ohio.
[0030] Balls incorporating intermediate layers within the scope of
the present invention also incorporate core compositions known for
use in golf balls. An example of a suitable core formulation
comprises a thermoplastic elastomer, such as crosslinked diene
elastomer of the polybutadiene cis-1,4 type containing a reaction
product with zinc oxide and zinc diacrylate, along with a
crosslinking agent, such as dicumyl peroxide or sulfur-containing
compounds.
EXAMPLE
[0031] Multi-layer golf balls were prepared to test the performance
of intermediate layers within the scope of the present invention.
The balls were labeled as Types 1 to 4, with two dozen in each
type. Type 1 to 3 balls incorporated cores having diameters of 1.48
inches and intermediate layers having thicknesses of 0.1 inches,
while Type 4 balls incorporated cores having diameters of 1.58
inches. All of the ball cores had compressions of 75. Type 1 balls
incorporated intermediate layers within the scope of the present
invention, consisting entirely of the triblock copolymer, marketed
as HG-252, described above. Type 2 and 3 balls incorporated
intermediate layers within the scope of the prior art. These
intermediate layers comprised blends of SURLYN 9120, SURLYN 8140,
and PEBAX 3533. Type 4 balls did not incorporate intermediate
layers and were provided as comparison to represent typical
two-piece balls.
[0032] Cover layers having thickness of 0.05 inches were placed on
all of the balls. Type 1, 2, and 4 balls had covers comprising
ionomer blends having a Shore D hardness of 62. Type 3 balls had
covers comprising ionomer blends having a Shore D hardness of 57.
The percentage compositions of the intermediate layers and
hardnesses of the cover materials are provided in Table below.
1TABLE 1 Ball Constructions Ball Type 1 2 3 4 Intermediate Layer
None HG-252 % 100 0 0 Surlyn 9120 % 0 15 15 Surlyn 8140 % 0 15 15
Pebax 3533 % 0 70 70 Cover Material Hardness 62 62 57 62 Shore
D
[0033] Testing
[0034] In addition to the balls discussed above, several golf balls
currently available on the market were tested for the same
parameters. These balls included the HP Tour manufactured by
Acushnet Corporation of Fairhaven, Mass., the Revolution
manufactured by MaxFli Golf of Greenville, S.C., and the Tour
Accuracy, manufactured by Nike Corporation of Beaverton, Oreg.
[0035] All of the balls were tested for spin rate and speed when
hit with an 8-iron, and speed when hit with a driver. The balls
also were tested for ball compression and surface hardness on the
Shore D scale (as distinguished from the cover material hardness
shown in Table 1). As discussed above, high spin rate when hit by a
short iron is desirable, because it allows for improved control of
the ball when hit. High ball speed is desirable, because it leads
to greater flying distance of the ball. Low PGA compression
provides for improved ball feel. In addition to these properties,
the balls also were tested for shear-cut resistance by hitting them
with a pitching wedge at controlled speed. Three of each type of
ball were used for this testing. Each ball was assigned a numerical
score from 1 (no visible damage) to 5 (substantial material
displaced), and these scores were averaged for each ball type to
produce the shear-cut resistance numbers below.
[0036] Results
[0037] Results of the tests are show in Table 2 below.
2TABLE 2 Ball Performance 8 Iron 8 Iron Driver Shear Hardness Spin
Speed PGA Speed Re- Ball Type (Shore D) (rpm) (mph) Comp. (mph)
sistance 1 60 8,376 109.5 74 159.6 1.0 2 62 7,799 109.6 81 159.5
1.8 3 58 7,907 109.1 79 159.5 2.7 4 62 7,473 110.3 80 160.6 1.8 HP
Tour 58 7,653 109.3 71 158.6 2.0 Revolution 54 8,206 109.3 78 159.6
2.6 Tour 49 8,110 110.5 77 158.1 4.2 Accuracy
[0038] Discussion
[0039] 1 Comparison of Type 1 and 2 Balls
[0040] As discussed above, Type 1 balls incorporated intermediate
layers within the scope of the present invention. Type 2 balls
represents prior art balls identical to Ball Type 1, except for
incorporation of conventional intermediate layers comprising
copolymeric ionomer and polyetheramide elastomer.
[0041] It is commonly believed that golf ball speed for a
multi-layer ball increases with increasing high acid copolymeric
ionomer content in the ball intermediate layer composition.
Therefore, it was expected that Type 1 balls, incorporating no
ionomeric material in their intermediate layers would show lower
ball speed than Type 2 balls, incorporating 30% copolymeric ionomer
in their mantles. However, as the data indicate, Type 1 balls
actually showed comparable driver and 8 Iron speed to Type 2 balls.
Despite the higher speeds, Type 1 balls also demonstrated
substantially higher 8 Iron spin rates. These data indicate that
Type 1 balls will travel approximately the same distance as Type 2
balls when hit with the same force, and also demonstrate superior
controllability when hit with an 8 Iron.
[0042] In addition to good ball speed and spin performance, Type 1
balls had lower PGA compressions than Type 2 balls, indicating
better "feel" when hit. Also, Type 1 balls showed substantially
superior shear-cut resistance. In general, exclusive use of the
triblock copolymer in the intermediate layers provided for superior
overall properties in golf balls. These results would not be
expected based on the previous understanding of soft elastomers
such as the triblock copolymer and the known performance
characteristics of intermediate layers.
[0043] 2. Comparison of Type 1 and 3 Balls
[0044] Type 3 balls represent prior art balls similar to Type 2
balls, except for a greater percentage of terpolymeric Ionomer in
the ball covers. Increasing terpolymeric ionomer content in a cover
for a multi-layer ball is a known method for attempting to lower
cover hardness, improve ball feel, and increase spin rate, at the
cost of other aspects of ball performance, such as ball speed or
shear-cut resistance. In this case, ball speeds for Type 1 and Type
3 balls are essentially identical. However, demonstrated spin rates
are much lower for Type 3 balls than for Type 1 balls. Also, though
Type 3 balls demonstrated lower PGA compressions than Type 2 balls,
they demonstrated PGA compressions higher than Type 1 balls.
Further, shear-cut resistance for Type 3 balls was markedly worse
than for Type 1, and even Type 2, balls. These data indicate that
use of the intermediate layers of the present invention is far
superior in improving golf ball properties than modification of
ball cover compositions, as is more commonly attempted.
[0045] 3. Comparison of Type 1 and 4 Balls
[0046] Type 4 balls have a two-piece structure; i.e., having no
intermediate layer. The cores were slightly larger than those in
Type 1 balls; essentially, the portion of the Type 1 balls that
comprised the core and intermediate layer were the core of the Type
4 balls.
[0047] As discussed above, two-piece balls are known to provide
superior ball speed and durability than comparable multi-layer
balls, at the cost of reduced spin and inferior "feel." This
reduction in spin and feel generally increases with use of softer
mantles. Therefore, it would be expected that Type 4 balls would
show substantially higher ball speed than Type 1 balls
incorporating soft HG-252 intermediate layers. As expected, Type 1
balls incorporating intermediate layers within the scope of the
present invention demonstrated superior 8 Iron spin rates to the
two-piece Type 4 balls. However, Type 4 balls demonstrated only
slightly higher ball speeds than Type 1 balls, and they exhibited
worse shear-cut resistance than the Type 1 balls. Type 1 balls also
exhibited much lower PGA compressions than Type 4 balls, indicating
that the Type 1 balls have far superior "feel." The data indicate
that use of intermediate layers of the present invention can
overcome the traditional disadvantages of multi-layer balls
incorporating prior art intermediate layers.
[0048] 4. Comparison of Type 1 and Marketed Balls
[0049] The marketed balls represent a wide range of prior art
balls, each having two-piece, multi-layer, or wound constructions.
Type 1 balls demonstrated higher spin rate, comparable ball speeds,
and far superior durability than the marketed balls. PGA
compression for the Type 1 balls was lower than for all but the HP
Tour balls, which had the lowest spin rates. In general, Type 1
balls demonstrate a superior combination of performance
characteristics than the marketed balls. Specifically, Ball Type 1
demonstrated superior ball speed, spin rate, and shear-cut
resistance than the HP Tour, a two-piece ball. Ball Type 1
demonstrated superior ball spin rate and shear-cut resistance than
the Revolution, a ball having a wound core and a thermoset
polyurethane cover. Finally, Ball Type 1 showed superior spin rate,
ball speed, and, remarkably, shear-cut resistance than the Tour
Accuracy, a ball having a thermoplastic polyurethane cover.
[0050] Generally, it is difficult to produce golf balls having high
spin rate when hit by a short iron, long distance when hit, low PGA
compression, soft hit-feel, and good durability. Type 1 balls
incorporating intermediate layers within the scope of the present
invention exhibited all of these. As discussed above, these
performance results contradict the prior understanding of the
effect of exclusive use of soft elastomers such as the specified
triblock copolymer, and they demonstrate the utility of the
intermediate layers of the present invention in maximizing
desirable ball properties.
[0051] Although the invention has been disclosed in detail with
reference only to the preferred embodiments, those skilled in the
art will appreciate that additional golf ball intermediate layers
can be made without departing from the scope of the invention.
* * * * *