U.S. patent application number 09/841910 was filed with the patent office on 2002-10-31 for multilayer golf ball with hoop-stress layer.
Invention is credited to Halko, Roman D., Morgan, William E., Vieira, Emanuel.
Application Number | 20020160862 09/841910 |
Document ID | / |
Family ID | 25286014 |
Filed Date | 2002-10-31 |
United States Patent
Application |
20020160862 |
Kind Code |
A1 |
Morgan, William E. ; et
al. |
October 31, 2002 |
Multilayer golf ball with hoop-stress layer
Abstract
The invention includes a golf ball having a center, a
hoop-stress layer of high tensile elastic modulus material wrapped
or wound about the core, at least one layer of a resilient
elastomeric material, and a cover of at least one layer. The center
in the golf ball can be a fluid with an encapsulating shell or a
solid. A binding material can be used in conjunction with the
hoop-stress layer to facilitate positioning of the hoop-stress
layer around the center for easier manufacturing.
Inventors: |
Morgan, William E.;
(Barrington, RI) ; Halko, Roman D.; (San Diego,
CA) ; Vieira, Emanuel; (New Bedford, MA) |
Correspondence
Address: |
SWIDLER BERLIN SHEREFF FRIEDMAN, LLP
3000 K STREET, NW
BOX IP
WASHINGTON
DC
20007
US
|
Family ID: |
25286014 |
Appl. No.: |
09/841910 |
Filed: |
April 25, 2001 |
Current U.S.
Class: |
473/376 |
Current CPC
Class: |
A63B 37/0046 20130101;
A63B 37/0003 20130101; A63B 37/0075 20130101; A63B 37/0049
20130101; A63B 37/0074 20130101 |
Class at
Publication: |
473/376 |
International
Class: |
A63B 037/06 |
Claims
What is claimed is:
1 A golf ball comprising four or more layers, wherein one of the
layers is a hoop-stress layer, comprising at least one material
with a tensile elastic modulus of at least about 10,000 kpsi,
situated between two of the three innermost layers.
2 The golf ball of claim 1 comprising the following layers: a
fluid-filled center; an encapsulating shell comprising at least one
layer to contain the fluid; a hoop-stress layer comprising at least
one material with a tensile elastic modulus of at least about
10,000 kpsi disposed about or within the at least one layer of the
encapsulating shell; at least one layer comprising a resilient
elastomeric component disposed about the hoop-stress layer; and a
cover comprising at least one layer and being disposed about the at
least one layer including a resilient elastomeric component.
3 The golf ball of claim 2, wherein the hoop-stress layer comprises
a wire, thread, or filament.
4 The golf ball of claim 2, wherein the hoop-stress layer comprises
glass, aromatic polyamid, carbon, metal, shape memory alloy,
natural fiber, or a combination thereof.
5 The golf ball of claim 4, wherein the at least one material
forming the hoop-stress layer is wound or wrapped in a criss-cross,
basket weave, or open pattern.
6 The golf ball of claim 5, wherein the at least one material
forming the hoop-stress layer comprises a plurality of braided
elements.
7 The golf ball of claim 2, wherein the at least one material
forming the hoop-stress layer has a tensile elastic modulus of at
least about 20,000 kpsi.
8 The golf ball of claim 3, wherein the wire, thread, or filament
has a first cross-sectional area that is coated with a binding
material to create a second cross-sectional area greater than the
first.
9 The golf ball of claim 2, wherein the at least one layer forming
the encapsulating shell comprises two layers and the material
forming the hoop-stress layer is disposed therebetween.
10 The golf ball of claim 1 comprising: a fluid-filled center; an
encapsulating shell comprising at least one layer to contain the
fluid; at least one layer comprising a first resilient elastomeric
component; a hoop-stress layer comprising at least one material
with a tensile elastic modulus of at least 10,000 kpsi disposed
about or within the at least one layer of the first resilient
elastomeric component; at least one layer comprising a second
resilient elastomeric component disposed about the hoop-stress
layer; and a cover comprising at least one layer and being disposed
about the at least one layer including a second resilient
elastomeric component.
11 The golf ball of claim 10, wherein the first resilient
elastomeric component is the same as the second resilient
elastomeric component.
12 The golf ball of claim 10, wherein the first resilient
elastomeric component differs from the second resilient elastomeric
component.
13 The golf ball of claim 10, wherein the at least one material
forming the hoop-stress layer comprises a wire, thread, or
filament.
14 The golf ball of claim 10, wherein the at least one material
forming the hoop-stress layer comprises glass, aromatic polyamid,
carbon, metal, shape memory alloy, natural fiber, or a combination
thereof.
15 The golf ball of claim 14, wherein the at least one material
forming hoop-stress layer is wound or wrapped in a criss-cross,
basket weave, or open pattern.
16 The golf ball of claim 15, wherein the at least one material
forming the hoop-stress layer comprises a plurality of braided
elements.
17 The golf ball of claim 10, wherein the at least one material
forming the hoop-stress layer has a tensile elastic modulus of at
least about 20,000 kpsi.
18 The golf ball of claim 13, wherein the wire, thread, or filament
has a first cross-sectional area that is coated with a binding
material to create a second cross-sectional area greater than the
first.
19 The golf ball of claim 10, wherein at least one layer comprising
a first resilient elastomeric component comprises two layers and
the at least one material forming the hoop-stress layer is disposed
therebetween.
20 The golf ball of claim 1 comprising: at least one core layer
comprising a first resilient elastomeric component; a hoop-stress
layer comprising at least one fibrous material with a tensile
elastic modulus of at least about 10,000 kpsi wound about the at
least one core layer; at least one intermediate layer comprising a
second resilient elastomeric component disposed about the
hoop-stress layer; and a cover comprising at least one layer and
being disposed about the at least one intermediate layer.
21 The golf ball of claim 20, wherein the first resilient
elastomeric component has a compression of greater than about
50.
22 The golf ball of claim 20, wherein the first resilient
elastomeric component is the same as the second resilient
elastomeric component.
23 The golf ball of claim 20, wherein the first resilient
elastomeric component differs from the second resilient elastomeric
component.
24 The golf ball of claim 20, wherein the at least one material
forming forming the hoop-stress layer comprises a wire, thread, or
filament.
25 The golf ball of claim 20, wherein the at least one material
forming the hoop-stress layer comprises glass, aromatic polyamid,
carbon, metal, shape memory alloy, natural fiber, or a combination
thereof.
26 The golf ball of claim 25, wherein the at least one material
forming the hoop-stress layer is wound or wrapped in a criss-cross,
basket weave, or open pattern.
27 The golf ball of claim 26, wherein the at least one material
forming the hoop-stress layer comprises a plurality of braided
elements.
28 The golf ball of claim 20, wherein the at least one material
forming the hoop-stress layer has a tensile elastic modulus of at
least about 20,000 kpsi.
29 The golf ball of claim 24, wherein the wire, thread, or filament
has a first cross-sectional area that is coated with a binding
material to create a second cross-sectional area greater than the
first.
30 The golf ball of claim 20, wherein at least one core layer
comprising a first resilient elastomeric component comprises two
layers and the at least one material forming the hoop-stress layer
is disposed therebetween.
31 A golf ball having four or more layers comprising: a center; a
cover comprising at least one layer; and a hoop-stress layer
comprising at least one material with a tensile elastic modulus of
at least about 10,000 kpsi, situated between two of the three
innermost layers, wherein the material has a first cross-sectional
area and the material is coated with a binding material to provide
a coated material with a second cross-sectional area greater than
the first.
32 The golf ball of claim 31, wherein the center is a solid.
33 The golf ball of claim 31, wherein the center is comprised of a
fluid-filled.
34 The golf ball of claim 31, wherein the center has a diameter
from about 0.5 inch to 1.55 inches.
35 The golf ball of claim 34, wherein the center has a diameter
from about 1.1 inches to 1.5 inches.
36 The golf ball of claim 31, wherein the center is surrounded by
an elastic wound layer.
37 The golf ball of claim 31, wherein the second cross-sectional
area is at least about 5 percent larger than the first
cross-sectional area.
38 The golf ball of claim 31, wherein the hoop-stress layer is
comprised of a continuous strand having a diameter from about 0.004
to 0.02 inches.
39 The golf ball of claim 31, wherein the binding material
comprises of thermoplastic polyvinyl butyral, thermoplastic epoxy,
thermoplastic polyester phenolic, thermoplastic polyamide,
thermosetting adhesive epoxy, thermoplastic polyamide-imide, or
combinations thereof.
40 The golf ball of claim 31, wherein the cover material has a
hardness of less then about 75 Shore D.
41 The golf ball of claim 40, wherein the cover material has a
hardness of less than about 65 Shore D.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to golf balls, and more
specifically, to a golf ball having a hoop-stress layer within a
layered construction used to eliminate or substantially inhibit
permanent deformation of the ball. In particular, it is directed to
a golf ball having at least four layers comprising a core, a
hoop-stress layer including at least one material with a tensile
elastic modulus of at least about 10,000 kpsi, at least one
resilient elastomeric layer, and cover layer. The golf balls of the
present invention can provide decreased spin and improved
resiliency for better distance.
BACKGROUND OF THE INVENTION
[0002] There are many methods for manufacturing golf balls. One
type of golf ball includes a tensioned material wound around a
spherical center. Another type of golf ball uses solely solid
layers, typically of thermoset or thermoplastic materials. Wound
balls typically have either a solid rubber or fluid center around
which many yards of a tensioned elastic thread, typically
polyisoprene, are wrapped to form a wound core. One or more added
layers of thermoset or thermoplastic materials may surround the
thread layer to complete the golf ball construction. Prior art golf
balls with liquid centers have traditionally been enclosed by a
layer of wrapped elastic material.
[0003] A wound material layer differs from a solid resilient
material layer in that the wound layer is often able to more
readily elongate and compress in a direction lateral to the
impacting force. For this reason, wound golf balls have a tendency
to more easily compress at impact as compared to a solid golf ball
(Dalton, Golf and Science III, 1999).
[0004] It has long been the goal of golf ball manufacturers to
create a non-wound construction golf ball with the performance and
feel properties of wound balls. Golf ball designs have been
introduced which use multilayer non-wound constructions. These
include double cover designs with solid, single member cores; dual
core designs with two core members and a single cover layer; balls
with multiple core and/or multiple cover layers; and balls with
liquid centers that do not have elastic windings. U.S. Pat. Nos.
5,480,155 and 5,150,906 by Molitor et al., U.S. Pat. Nos. 5,683,312
and 5,919,100 by Boehm et al. are examples of non-wound liquid
center balls. Hollow golf balls having a spherical cavity in the
center are disclosed by Boehm et al. and further described in U.S.
Pat. No. 5,944,621 to Tsujinaka et al.
[0005] One technique suggested in the prior art to avoid the
problem of an overly hard stiff cover was disclosed in U.S. Pat.
No. 4,431,193 issued to Nesbitt. Rather than have a single layer
cover over the core, the cover would be molded in two layers: a
hard stiff inner layer of a high flexural modulus material that
provides significant hoop stress, surrounded by a soft, flexible
outer cover of a lower flexural modulus material. Balls of this
design have been sold bearing the Strata name for some time,
however, because of the inner layer thickness of about 0.045 inches
to 0.050 inches and the high flexural modulus of greater than
50,000 psi, the golf balls have a hard feel to which many golfers
object.
[0006] U.S. Pat. 5,713,801 issued to Aoyama teaches a method for
making a golf ball providing a core of solid resilient material,
winding a high elastic modulus fiber on the core to create a first
wound layer to form a "hoop-stress layer," and molding an outer
layer of resilient material about the first wound layer. The
invention includes a golf ball having a substantially spherical
core, a first wound layer of high tensile elastic modulus fibers
wound about the core, and a second molded layer of a resilient
material surrounding the wound layer The core in the above method
and apparatus may also be made of a center wound with a low modulus
fiber and provided with an initial tension.
[0007] U.S. Pat. 5,913,736 issued to Maehara et al. builds upon
Aoyama to describe a hoop-stress layer made of a shape memory alloy
(Ti-Ni) wound around a core so as to provide a shaped memory alloy
layer.
[0008] Thus, it would be advantageous to provide a golf ball having
at least four or more layers, including a hoop-stress layer and at
least one resilient elastomeric layer, to form a golf ball with
improved performance characteristics.
SUMMARY OF THE INVENTION
[0009] The present invention is directed to a multilayer golf ball
including four or more layers, wherein one of the layers is a
hoop-stress layer, including at least one material with a tensile
elastic modulus of at least about 10,000 kpsi, located between two
of the three innermost layers. Such a golf ball can advantageously
provide a softer feel similar to a conventional wound ball, while
also providing the low spin rates of a conventional solid
composition ball. As discussed in detail below, the multilayer golf
ball of the present invention, with a hoop-stress layer, is
provided by forming a ball having various structural components
(e.g., core, hoop-stress layer, resilient elastomeric layer, and
cover) each having desired properties and which may be formed from
a variety of materials.
[0010] In a first embodiment of the invention, the golf ball
includes a fluid-filled center, an encapsulating shell of at least
one layer to contain the fluid, a hoop-stress layer including at
least one material with a tensile elastic modulus of at least about
10,000 kpsi, preferably 20,000 kpsi, disposed about or within the
at least one layer of the encapsulating shell, at least one layer
including a resilient elastomeric component disposed about the
hoop-stress layer, and a cover including at least one layer
disposed about the resilient elastomeric component. Preferably, the
hoop-stress layer includes a wire, thread, or filament. In one
embodiment, the hoop-stress layer includes glass, aromatic
polyamid, carbon, metal, shape memory alloy, natural fiber, or a
combination thereof. The hoop-stress layer can be wound or wrapped
in a criss-cross, basket weave, or open pattern and include
multiple braided elements. In one embodiment, the wire, thread, or
filament of the hoop-stress layer is coated with a binding
material. In another embodiment, the at least one layer forming the
encapsulating shell includes two layers and the material forming
the hoop-stress layer is disposed therebetween.
[0011] In a second embodiment, the golf ball includes a
fluid-filled center, an encapsulating shell of at least one layer
to contain the fluid, at least one layer including a first
resilient elastomeric component, a hoop-stress layer including at
least one material with a tensile elastic modulus of at least about
10,000 kpsi, preferably about 20,000 kpsi, disposed about or within
the at least one layer including a first resilient elastomeric
component, at least one layer including a second resilient
elastomeric component disposed about the hoop-stress layer, and a
cover including at least one layer disposed about the at least one
layer including a second resilient elastomeric component.
Preferably, the hoop-stress layer includes a wire, thread, or
filament. In one embodiment, the material forming the hoop-stress
layer includes glass, aromatic polyamid, carbon, metal, shape
memory alloy, natural fiber, or a combination thereof. The
hoop-stress layer can be wound or wrapped in a criss-cross, basket
weave, or open pattern and include multiple braided elements. In
one embodiment, the wire, thread, or filament of the hoop-stress
layer is coated with a binding material. In another embodiment, the
first and second resilient elastomeric components are the same. Yet
in another embodiment, the first and second resilient elastomeric
components are different from each other.
[0012] In a third embodiment of the invention, the golf ball
includes at least one core layer including a first resilient
elastomeric component, a hoop-stress layer including at least one
material with a tensile elastic modulus of at least about 10,000
kpsi, preferably about 20,000 kpsi, wound about or embedded within
the surface of the at least one core layer, at least one
intermediate layer of a second resilient elastomeric component
disposed about the hoop-stress layer; and a cover of at least one
layer disposed about the at least one intermediate layer.
Preferably, the hoop-stress layer includes a wire, thread, or
filament made of glass, aromatic polyamid, carbon, metal, shape
memory alloy, natural fiber, or a combination thereof. The
hoop-stress layer can be wound or wrapped in a criss-cross, basket
weave, or open pattern and include multiple braided elements. In
one embodiment, the wire, thread, or filament of the hoop-stress
layer is coated with a binding material. In another embodiment, the
first and second resilient elastomeric components are the same. Yet
in another embodiment, the first and second resilient elastomeric
components differ. In one embodiment, the first resilient
elastomeric component has a compression of greater than about
50.
[0013] A fourth embodiment of the invention includes a golf ball
with a center, a cover of at least one layer, and a hoop-stress
layer including at least one material with a tensile elastic
modulus of at least about 10,000 kpsi, preferably about 20,000
kpsi, located between two of the three innermost layers, wherein
the material has a first cross-sectional area and the material is
coated in a binding material to create a second cross-sectional
area greater than the first. The center can be solid or
fluid-filled with a diameter from about 0.5 inch to 1.55 inches,
preferably from about 1.1 inches to 1.5 inches. In one preferred
embodiment, the center is surrounded by an additional surrounding
elastic wound layer. The hoop-stress layer can include a continuous
strand having a diameter from about 0.004 to 0.04 inches.
Preferably, the binding material coats the wire, thread, or
filament of the hoop-stress layer so that the second
cross-sectional area is at least about 5 percent larger than the
first cross-sectional area. The binding material can include
thermoplastic polyvinyl butyral, thermoplastic epoxy, thermoplastic
polyester phenolic, thermoplastic polyamide, thermosetting adhesive
epoxy, thermoplastic polyamide-imide, or combinations thereof. In
one embodiment, the cover material has a hardness of less than
about 75 Shore D, and in another embodiment, the materials has a
hardness less than about 65 Shore D.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Further features and advantages of the invention can be
ascertained from the following detailed description which is
provided in connection with the attached drawings, wherein:
[0015] FIG. 1 illustrates a cut-away view of a multilayer non-wound
golf ball with a hoop-stress layer in accordance with the present
invention;
[0016] FIG. 2 illustrates a cross-section of a multilayer non-wound
fluid center golf ball with a hoop-stress layer and at least one
resilient elastomeric layer in accordance with one embodiment of
the present invention;
[0017] FIG. 3 illustrates a cross-section of a multilayer non-wound
fluid center golf ball with a hoop-stress layer and a plurality of
resilient elastomeric layers in accordance with the second
embodiment of the present invention;
[0018] FIG. 4 illustrates a cross-section of a multilayer non-wound
solid center golf ball with a hoop-stress layer in accordance with
the third embodiment of the present invention; and
[0019] FIG. 5 illustrates a cross-section of a multilayer golf ball
with a hoop-stress layer coated with a binding material in
accordance with the fourth embodiment of the present invention.
DEFINITIONS
[0020] The term "about," as used herein in connection with one or
more numbers or numerical ranges, should be understood to refer to
all such numbers, including all numbers in a range.
[0021] As used herein, the term "fluid" includes a liquid, a paste,
a gel, a gas (including air, regardless of pressure) or any
combination thereof.
[0022] As used herein, the term "multilayer" means at least four
layers and includes fluid-center balls, wound balls, hollow-center
balls, and balls with at least two intermediate layers and/or cover
layers.
[0023] As used herein, "cis-to-trans catalyst," means any component
or a combination thereof that will convert at least a portion of
cis-isomers to trans-isomers of polybutadiene at a given
temperature.
[0024] As used herein, the term "parts per hundred", also known as
"phr", is defined as the number of parts by weight of a particular
component present in a mixture, relative to 100 parts by weight of
the total polymer component. Mathematically, this can be expressed
as the weight of an ingredient divided by the total weight of the
polymer, multiplied by a factor of 100.
[0025] As used herein, the term "molecular weight" is defined as
the absolute weight average molecular weight. The molecular weight
is determined by the following method: approximately 20 mg of
polymer is dissolved in 10 mL of tetrahydrofaran ("THF"), which may
take a few days at room temperature depending on the polymer's
molecular weight and distribution. One liter of THF is filtered and
degassed before being placed in a high-performance liquid
chromatography ("HPLC") reservoir. The flow rate of the HPLC is set
to 1 mL/min through a Viscogel column. This non-shedding, mixed
bed, column model GMHHR-H, which has an ID of 7.8 mm and 300 mm
long is available from Viscotek Corp. of Houston, Tex. The THF flow
rate is set to 1 mL/min for at least one hour before sample
analysis is begun or until stable detector baselines are achieved.
During this purging of the column and detector, the internal
temperature of the Viscotek TDA Model 300 triple detector should be
set to 40.degree. C. This detector is also available from Viscotek
Corp. The three detectors (i.e., Refractive Index, Differential
Pressure, and Light Scattering) and the column should be brought to
thermal equilibrium, and the detectors should be purged and zeroed,
to prepare the system for calibration according to the instructions
provided with this equipment. A 100-.mu.L aliquot of sample
solution can then be injected into the equipment and the molecular
weight of each sample can be calculated with the Viscotek's triple
detector software. When the molecular weight of the polybutadiene
material is measured, a dn/dc of 0.130 should always be used. It
should be understood that this equipment and these methods provide
the molecular weight numbers described and claimed herein, and that
other equipment or methods will not necessarily provide equivalent
values as used herein.
DETAILED DESCRIPTION OF THE INVENTION
[0026] It has now been discovered that the use of a plurality of
resilient elastomeric layers in combination with a wound or wrapped
hoop-stress layer providing the necessary hoop-stress, in forming
golf balls, according to the present invention, can advantageously
provide desirable performance improvements in a golf ball.
[0027] The present invention advantageously allows the center
components, i.e., solids or fluids, to return to shape post-impact,
thus avoiding permanent deformation, with a different approach,
that of providing several intermediate layers, including a
hoop-stress layer disposed between the center and cover of the golf
ball. The hoop-stress layer is formed of a wound, high tensile
elastic modulus material, such as a thread, fiber, filament, or
wire. This wound high tensile elastic modulus layer can be
incorporated within one or more layers of a multilayer center,
particularly when the innermost member is a fluid. The hoop-stress
layer does not need to be applied directly to the center, but can
be wound about any layer between the center and the outermost cover
layer. The hoop-stress layer can be incorporated within one or more
layers of a solid multilayer center, wherein the innermost layer(s)
of the center are subject to high deflections upon impact with a
golf club. In addition, a binding material can coat the hoop-stress
layer so that the layer will remain properly positioned around the
center or core of the golf ball.
[0028] The golf ball of the invention is believed to provide a
further benefit for a golfer's short game. The spin of a ball after
being struck with a large force, such as with a driver, is
controlled by the relationship between the softness (flexibility)
of the cover and the compressibility of the center of the golf
ball. When the impact force is low, such as in the short game, the
resulting spin of a golf ball is controlled almost entirely by
surface (cover) hardness. A softer cover is desired by golfers to
improve short game spin, however, it also increases driver spin and
decreases distance. To some extent, softening the center can reduce
the driver spin of soft-covered balls, but if both the cover and
the core are too soft, the golf ball loses resiliency and the
resulting initial velocity and distance that are also desired in a
golf ball. Therefore, golf ball manufacturers are challenged with
making a soft cover golf ball with low driver spin, which the
present invention advantageously provides.
[0029] Thus, improved golf balls can be prepared according to the
invention by: (a) providing a center; (b) winding or wrapping a
hoop-stress layer of high tensile elastic modulus material about
the center, optionally with one or more layers disposed
therebetween; (c) surrounding the hoop-stress layer with at least
one layer formed including a resilient elastomeric component; and
(d) disposing a cover including at least one layer.
[0030] In FIG. 1, a golf ball center 95 is surrounded by a
hoop-stress layer 105 of high tensile elastic modulus of at least
10,000 kpsi with one or more layers 100 disposed therebetween. This
hoop-stress layer is surrounded by at least one layer including a
resilient elastomeric component 110. A cover 115 of at least one
layer surrounds the resilient elastomeric layer 110.
[0031] In one embodiment, shown in FIG. 2, the golf ball of the
invention has a fluid center 120 surrounded by an encapsulating
shell 125 of at least one layer. The hoop-stress layer 130 is
preferably wound or wrapped around the encapsulating shell 125 or,
in an embodiment not shown, the encapsulating shell 125 is made up
of multiple layers and the the hoop-stress layer is disposed
therebetween. Hoop-stress layer 130 has the characteristics
described herein. At least one layer comprising a resilient
elastomeric component 135 surrounds the hoop-stress layer 130 and
preferably has at least one layer that is a solid. A cover 140, of
one or more layers optionally, but preferably, surrounds layer
135.
[0032] In a second embodiment shown in FIG. 3, a golf ball
including a fluid center is contained by an encapsulating shell, a
first resilient elastomeric layer, a hoop-stress layer, a second
resilient elastomeric layer, and a cover. The plurality of layers
can decrease or eliminate permanent ball deformation without
adversely increasing the hardness of the ball or its components. An
encapsulating shell 125 of at least one layer contains the fluid
center 120. A first resilient elastomeric material 145 of at least
one layer surrounds the encapsulating shell 125 and fluid center
120. The hoop-stress layer 130 is preferably wound or wrapped
around the first resilient elastomeric layer 145 or, in one
embodiment (not shown) the first resilient elastomeric component
145 includes more than one layer and the hoop-stress layer is
disposed therebetween. A second resilient elastomeric component 135
of at least one layer surrounds the hoop-stress layer 130. A cover
140 of one or more layers can be formed around the second resilient
elastomeric layer 135. The components forming the first and second
resilient elastomeric layers need not necessarily be the same, but
in one embodiment, the components have the same
characteristics.
[0033] A third embodiment of the invention is shown in FIG. 4
relating to a golf ball with at least four layers including a solid
center and a hoop-stress layer. Such a golf ball can provide good
short-game spin, and the resulting ability to better control the
golf ball in and around the green, without adversely impacting
other characteristics in an undesirable fashion. The center of the
golf ball is made of a first resilient elastomeric material 150
surrounded by a hoop-stress layer 155 of high tensile elastic
modulus material. Center layer 150 includes at least one layer and
preferably has at least one of the layers being a solid material. A
second resilient elastomeric component 160 encases the hoop-stress
layer. A cover 165 of one or more layers can surround resilient
elastomeric material 160.
[0034] In the fourth embodiment of the invention, the wire, thread,
or filament of the hoop-stress layer is coated with a binding
material to create a low spin, highly resilient multilayer golf
ball. The binding material surrounding the hoop-stress layer
advantageously ensures the hoop-stress layer repeatable proper
positioning around the center during manufacturing. FIG. 5 shows a
center 190 surrounded by a hoop-stress layer 195. The center can be
a fluid or a solid. If the center is fluid, an encapsulating shell
of at least one layer surrounds the center and the hoop-stress
layer would then surround the encapsulating shell or be
sufficiently embedded within one or more layers of the
encapsulating shell. The center preferably has a diameter ranging
from about 1 inch to about 1.59 inches. More preferably, the
diameter of the center ranges from about 1.2 inches to about 1.4
inches. In one preferred embodiment (not shown), an elastic wound
layer can be placed within the center 190 and the hoop-stress layer
195. The hoop-stress layer 195 is preferably made of a continuous
single strand with a diameter ranging from about 0.004 inches to
about 0.02 inches and preferably includes a high specific gravity
alloy, preferably steel, brass, or bronze.
[0035] The wire, thread or filament of hoop-stress layer 195 is
coated with a binding material 200 that will adhere to the center
and itself when activated. The cover 205 surrounds the inner layers
of the ball and can be made of at least one layer of any suitable
thermoset or thermoplastic material available to one of ordinary
skill in the art. In one embodiment, the cover material preferably
has a hardness of less than about 75 Shore D. In another
embodiment, the cover material has a hardness of less than about 65
Shore D.
The Centers
[0036] The centers employed in the golf balls of the present
invention preferably have a diameter of about 0.5 inches to about
1.6 inches, more preferably about 1.1 inches to about 1.5
inches.
[0037] If the center of a golf ball is fluid with a rigid solid
member surrounding the center, such a construction is likely to
affect overall performance of the golf ball as if it ere a hard
center with a flexural modulus of greater than about 50,000 psi.
Hard center properties increase golf ball spin, thus hindering the
purpose of fluid center. Therefore, in other embodiments of the
invention shown in FIG. 2, FIG. 3, and FIG. 5, the encapsulating
shell used to help retain the fluid must be sufficiently flexible,
i.e., have a flexural modulus less than about 50,000 psi, to allow
the center of the ball to promote decreased spin while still
returning rapidly to its original shape post-impact.
[0038] In one embodiment, shown in FIG. 4, center is solid and has
the characteristics of the resilient elastomeric components
described herein, and is preferably polybutadiene. In one
embodiment, the center has a compression of greater than about
50.
[0039] Many golf balls use fillers added to the elastomeric
composition in the cores to adjust the density and/or specific
gravity of the core. In a preferred embodiment, the golf balls of
the present invention use little filler, if any. As used herein,
the term "fillers" includes any compound or composition that can be
used to vary the density and other properties of a layer or portion
of a golf ball. If needed, fillers useful in the golf ball
according to the present invention include, for example,
precipitated hydrated silica; clay; talc; asbestos; glass fibers;
aramid fibers; mica; calcium metasilicate; barium sulfate; zinc
sulfide; lithopone; silicates; silicon carbide; diatomaceous earth;
carbonates such as calcium carbonate and magnesium carbonate;
metals such as titanium, tungsten (e.g., powdered), lead, aluminum,
bismuth, nickel, molybdenum, iron, copper, boron, cobalt,
beryllium, zinc, and tin; metal alloys such as steel, brass,
bronze, boron carbide whiskers, and tungsten carbide whiskers;
metal oxides such as zinc oxide, iron oxide, aluminum oxide,
titanium oxide, magnesium oxide, and zirconium oxide; particulate
carbonaceous materials such as graphite, carbon black, cotton
flock, natural bitumen, cellulose flock, and leather fiber; micro
balloons such as glass and ceramic; fly ash; and combinations
thereof. The amount and type of filler utilized is governed by the
amount and weight of other ingredients in the composition, since a
maximum golf ball weight of 45.93 g (1.62 ounces) has been
established by the United States Golf Association (USGA).
Appropriate fillers generally used have a specific gravity from
about 2 to 20. In one preferred embodiment, a filler having a
specific gravity of about 12 to 20 can be included.
The Encapsulating Shell
[0040] Any suitable shell material, or blend thereof, capable of
inhibiting or preventing fluid loss from the ball available to
those of ordinary skill in the art may be used to form the
encapsulating shells of the present invention.
[0041] Exemplary materials for use in the shell include thermoset
or thermoplastic materials; including polyisoprene; natural rubber;
a polyether-ester copolymer; castable thermoset urethanes; vinyl
resins, such as those formed from polymerization of vinyl chloride
or from copolymerization of vinyl chloride with vinyl acetate,
acrylic esters, or vinylidene chloride; polyolefins, such as
polyethylene, polypropylene, polybutylene, and copolymers such as
polyethylene methacrylate, polyethylene vinyl acetate, polyethylene
methacrylic or acrylic acid, polypropylene acrylic acid, or
terpolymers thereof with acrylate esters and their metal ionomers;
polyamides, such as poly (hexamethylene adipamide) or others
prepared from diamines and dibasic acids, poly(caprolactam), PEBAX,
a poly(ether-amide) block copolymer commercially available from Elf
Atochem having an address in Philadelphia, Pa., and blends of
polyamides with SURLYN, polyethylene or copolymers thereof, EPDM;
acrylic resins; thermoplastic rubbers, such as urethanes, olefinic
thermoplastic rubbers such as styrene and butadiene block
copolymers or isoprene or ethylene-butylene rubber; polyphenylene
oxide resins or blends thereof with polystyrene; thermoplastic
polyesters, such as PET, PBT, PETG, and elastomers such as HYTREL,
which is commercially available from E.I. DuPont De Nemours &
Company of Wilmington, Del.; blends and alloys including
polycarbonate with ABS, PBT, PET, SMA, PE elastomers, and PVC with
ABS or EVA or other elastomers; blends of thermoplastic rubbers
with polyethylene, polypropylene, polyacetal, nylon, polyesters,
cellulose esters; metallocene catalyzed polyolefins; silicone;
polybutylene terephthalate; or the like; or any combination
thereof.
[0042] The encapsulating shells employed in the golf balls of the
present invention preferably have a thickness from about 0.01
inches to 0.12 inches, more preferably about 0.04 inches to 0.09
inches. In one preferred embodiment, the encapsulating shell
thickness is about 0.03 inches. The outer diameter of the
encapsulating shell is preferably from about 1 to about 1.5
inches.
The Hoop-Stress Layer
[0043] The hoop-stress layer of the present invention has a tensile
modulus of at least about 10,000 kpsi and is formed of a high
tensile "filament" which can be a thread, filament, or wire,
preferably glass, aromatic polyamids, carbon, metals, shape memory
alloys, or natural fibers, or a combination or blend thereof. The
hoop-stress layer is wound or wrapped about the core of one or more
layers. In a more preferred embodiment, the wound layer has a
tensile modulus of at least about 20,000 kpsi. If a wound layer is
created using a high density material, such as a metal, the ball
will have an increased moment of inertia, and thus will tend to
spin less when struck with a golf club and yet retain its spin
longer during flight. The use of high density materials in the
hoop-stress layer can advantageously permit the fillers from other
components of the golf ball to be reduced or removed while keeping
the overall golf ball weight constant. Specifically, removing
fillers from elastomeric components such as the resilient
elastomeric material used as another layer of the ball can soften
and increase resilience of the components and even the ball.
[0044] Any suitable winding or wrapping method known to those of
ordinary skill in the art can be used to form the hoop-stress
layer. Preferably, the hoop-stress layer is created winding strands
in a criss-cross, basket weave, or open pattern, which requires
fewer wraps than a great circle pattern and a less dense
application to obtain spherical symmetry.
[0045] The crisscross pattern typically employs a fairly large
lateral rotation during winding. One such suitable method is
described in U.S. Pat. 4,938,471 to Nomura et al., wherein at least
8 turns of every ten turns of strands around the center have a
crossing angle between two consecutive turns in the range of
12.degree. to 45.degree.. The hoop-stress layer can include
multiple strands that are braided, or otherwise entwined, during
the winding or wrapping process.
[0046] In one embodiment, a binding material preferably coats the
material having a first cross-sectional area which forms the
hoop-stress layer, to create a second cross-sectional area greater
than the first. The binding material preferably causes the strands
of the hoop-stress layer to swell so as to increase the
cross-sectional area of each strand. This can advantageously permit
repeatable proper positioning of the hoop-stress layer around the
center or core of the golf ball. In a preferred embodiment, the
binding material increases the cross-sectional area of the
hoop-stress layer by at least about five (5) percent. In a
preferred embodiment, the cross-sectional area can be increased by
at least about ten (10) percent.
[0047] The binding material can include one or more thermoplastic
or thermoset materials. Thermoplastics can become tacky upon
heating thus improving adhesion within the hoop-stress layer or
even fully melt to fuse with some or all of the hoop-stress layer.
A thermoplastic component might also include a blowing agent to
create a foamed structure within the hoop-stress layer. Examples of
thermoplastics useful in the binding material include thermoplastic
polyvinyl butyral, thermoplastic epoxy, thermoplastic polyester
phenolic, thermoplastic polyamide, thermoplastic polyamide-imide,
or a combinations thereof. A thermoset material, such as
thermosetting adhesive epoxy, may alternatively respond to an
elevated temperature to promote intra- and/or inter- layer adhesion
and cause the hoop-stress layer to swell.
[0048] The binding material can be activated, for example, by heat,
pressure, chemical or photo-activation, before, during, or after
the winding process.
[0049] The hoop-stress layer can include one or more strands, but
is preferably made of a single continuous strand with a diameter
ranging from about 0.004 inches to 0.04 inches. The material
forming the hoop-stress layer preferably includes one or more high
specific gravity alloys.
[0050] Examples of suitable high specific gravity alloys are alloys
that have specific gravities greater than about 7.6, which include
steel, brass, bronze, copper, nickel, lead, titanium, gold, silver,
and platinum. Exemplary alloys include steel, brass, and bronze as
they provide the best combination of tensile strength (greater than
about 250 N/mm.sup.2) and high specific gravity (ranging from about
7.6 to about 9). While gold, silver, and platinum have higher
specific gravities than other suitable alloys, they tend to be
expensive; copper and nickel have similar specific gravities as the
exemplary alloys, but do not tend to provide comparable strength;
and titanium is strong, but tend to have a lower specific gravity
than steel.
[0051] The hoop-stress layers employed in the golf balls of the
present invention preferably have a thickness from about 0.01
inches to 0.1 inches, more preferably about 0.02 inches to 0.08
inches. In one exemplary embodiment, the hoop-stress layer has a
thickness of about 0.04 inches. The outer diameter of the
hoop-stress layer is preferably from about 1.3 to about 1.63
inches.
The Resilient Elastomeric Layer(s)
[0052] A representative base composition for forming a resilient
elastomeric material includes polybutadiene and, in parts by weight
based on 100 parts polybutadiene. In a preferred embodiment, the
composition also includes 20 to 50 parts of a metal salt
diacrylate, dimethacrylate, or monomethacrylate, preferably zinc
diacrylate. The polybutadiene preferably has a cis 1,4 content of
above about 90% and more preferably above about 96%.
[0053] Preferred commercial sources of polybutadiene include Shell
1220 manufactured by Shell Chemical, Neocis BR40 and BR60
manufactured by Enichem Elastomers, Ubepol BR150 and 360
manufactured by Ube Industries, Ltd., CB23 manufactured by Bayer
AG, and BUDENE 1207G, manufactured by Goodyear. If desired, the
polybutadiene can also be mixed with other elastomers known in the
art, such as natural rubber, styrene butadiene, and/or isoprene in
order to further modify the properties of the material. When a
mixture of elastomers is used, the amounts of other constituents in
the core composition are generally based on 100 parts by weight of
the total elastomer mixture.
[0054] Also, the resilient elastomeric layer may include a
resilient controlled-isomer polybutadiene polymer that typically
includes at least about 10 percent up to 80 percent trans-isomer
content with the rest being cis-isomer and vinyl-isomer distributed
randomly, pseudo-randomly, or in block fashion along the same
polybutadiene backbone. Such materials are disclosed in U.S. patent
application No. 09/741,052, filed Dec. 21, 2000, which is
incorporated by reference herein.
[0055] Metal salt diacrylates, dimethacrylates, and
monomethacrylates suitable for use in this invention include those
wherein the metal is magnesium, calcium, zinc, aluminum, sodium,
lithium or nickel. Zinc diacrylate is preferred, because it
provides golf balls with a high initial velocity in the USGA test.
The zinc diacrylate can be of various grades of purity. For the
purposes of this invention, the lower the quantity of zinc stearate
present in the zinc diacrylate the higher the zinc diacrylate
purity. Zinc diacrylate containing about 1 to 10 percent zinc
stearate is preferable. In one embodiment, it is more preferable to
use zinc diacrylate containing about 4 to 8 percent zinc stearate.
Suitable commercially available zinc diacrylates include those from
Rockland React-Rite, Inc. of Rockmart, Ga. and Sartomer Co., Inc.
of Exton, Pa. The preferred concentrations of zinc diacrylate that
can be used are about 20 phr to 50 phr based upon 100 parts of
polybutadiene or alternately, polybutadiene with a mixture of other
elastomers.
[0056] Free radical initiators are used to promote cross-linking of
the metal salt diacrylate, dimethacrylate, or monomethacrylate and
the polybutadiene. Any suitable free radical initiators can be used
in the invention. Exemplary initiators include, but are not limited
to, peroxide compounds. Exemplary peroxides include dicumyl
peroxide, 1,1-di (t-butylperoxy) 3,3,5-trimethyl cyclohexane, a-a
bis (t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5 di
(t-butylperoxy) hexane, or di-t-butyl peroxide, and mixtures
thereof. Other useful initiators would be readily apparent to one
of ordinary skill in the art without any need for experimentation.
The initiator(s) at 100 percent activity are preferably added in an
amount ranging between about 0.05 and 2.5 phr based upon 100 parts
of butadiene, or butadiene mixed with one or more other elastomers.
More preferably, the amount of initiator added ranges between about
0.15 and 2 phr and most preferably between about 0.25 phr and 1.5
phr.
[0057] In one embodiment, the resilience index of the core is
greater than about 40, preferably greater than about 45. In one
preferred embodiment, the resilience index of the core is greater
than about 50. The core compression can thus be reduced, thereby
decreasing the overall spin rate of the ball without a significant
loss in golf ball initial velocity. An exemplary finished ball
velocity according to the present invention can advantageously be
about 253.5 to 254.5 ft/s. These correspond to CORs of 0.812 and
0.818 respectively. Polymers that produce resilient cores include,
but are not limited to, CB23, BR60, or a blend thereof. CB23 is
commercially available from Bayer Corporation of Akron, Ohio.
[0058] The resilient elastomeric material may have a molecular
weight of greater than about 200,000, and in one embodiment,
preferably greater than about 300,000. More preferably, the
molecular weight of the rubber material of the resilient
elastomeric layer is greater than about 350,000.
[0059] Each layer that includes a resilient elastomeric component
can be the same or different from any other resilient elastomeric
layers in the golf ball.
The Cover
[0060] Any number of a wide variety of cover materials may be used
in the present invention such as ionomer resins, polyurethanes,
balata and blends thereof, with ionomer resins being preferred
(such as the variety of ionomers sold by the DuPont Chemical
Company under the trade name of "Surlyn"), all of which are well
known to those of ordinary skill in the art. The cover of the
present invention include at least one layer, preferably of a
thermoplastic or thermosetting material.
[0061] The cover layer, which may include an inner and outer cover
layer, can each include any materials known to those of ordinary
skill in the art, including thermoplastic and thermosetting
materials, but preferably the inner cover layer can include any
suitable materials, such as ionic copolymers of ethylene and an
unsaturated monocarboxylic acid which are available under the
trademark SURLYN of E.I. DuPont de Nemours & Co., of
Wilmington, Del., or IOTEK or ESCOR of Exxon. These are copolymers
or terpolymers of ethylene and methacrylic acid or acrylic acid
partially neutralized with salts of zinc, sodium, lithium,
magnesium, potassium, calcium, manganese, nickel or the like, in
which the salts are the reaction product of an olefin having from 2
to 8 carbon atoms and an unsaturated monocarboxylic acid having 3
to 8 carbon atoms. The carboxylic acid groups of the copolymer may
be totally or partially neutralized and might include methacrylic,
crotonic, maleic, fumaric or itaconic acid.
[0062] This golf ball can likewise include one or more
homopolymeric or copolymeric materials, such as:
[0063] (1) Vinyl resins, such as those formed by the polymerization
of vinyl chloride, or by the copolymerization of vinyl chloride
with vinyl acetate, acrylic esters or vinylidene chloride;
[0064] (2) Polyolefins, such as polyethylene, polypropylene,
polybutylene and copolymers such as ethylene methylacrylate,
ethylene ethylacrylate, ethylene vinyl acetate, ethylene
methacrylic or ethylene acrylic acid or propylene acrylic acid and
copolymers and homopolymers produced using a single-site catalyst
or a metallocene catalyst;
[0065] (3) Polyurethanes, such as those prepared from polyols and
diisocyanates or polyisocyanates and those disclosed in U.S. Pat.
No. 5,334,673;
[0066] (4) Polyureas, such as those disclosed in U.S. Pat. No.
5,484,870;
[0067] (5) Polyamides, such as poly(hexamethylene adipamide) and
others prepared from diamines and dibasic acids, as well as those
from amino acids such as poly(caprolactam), and blends of
polyamides with SURLYN, polyethylene, ethylene copolymers,
ethyl-propylene-non-conjugated diene terpolymer, and the like;
[0068] (6) Acrylic resins and blends of these resins with poly
vinyl chloride, elastomers, and the like;
[0069] (7) Thermoplastics, such as urethanes; olefinic
thermoplastic rubbers, such as blends of polyolefins with
ethylene-propylene-non-conjug- ated diene terpolymer; block
copolymers of styrene and butadiene, isoprene or ethylene-butylene
rubber; or copoly(ether-amide), such as PEBAX, sold by Atofina of
Philadelphia, Pa. (formerly Elf Atochem);
[0070] (8) Polyphenylene oxide resins or blends of polyphenylene
oxide with high impact polystyrene as sold under the trademark
NORYL by General Electric Company of Pittsfield, Mass.;
[0071] (9) Thermoplastic polyesters, such as polyethylene
terephthalate, polybutylene terephthalate, polyethylene
terephthalate/glycol modified and elastomers sold under the
trademarks HYTREL by E.I. DuPont de Nemours & Co. of
Wilmington, Del., and LOMOD by General Electric Company of
Pittsfield, Mass.;
[0072] (10) Blends and alloys, including polycarbonate with
acrylonitrile butadiene styrene, polybutylene terephthalate,
polyethylene terephthalate, styrene maleic anhydride, polyethylene,
elastomers, and the like, and polyvinyl chloride with acrylonitrile
butadiene styrene or ethylene vinyl acetate or other elastomers;
and
[0073] (11) Blends of thermoplastic rubbers with polyethylene,
propylene, polyacetal, nylon, polyesters, cellulose esters, and the
like.
[0074] The covers employed in the golf balls of the present
invention preferably have a thickness from about 0.02 inches to 0.1
inches. More preferably, the cover has a thickness of about 0.04
inches to 0.085 inches, preferably about 0.04 inches to 0.065
inches.
[0075] The cover layer is formed preferably by injection or
compression molding, reaction injection molding, casting, or
another process(es) well known to those of ordinary skill in the
art of manufacturing golf balls.
[0076] The multilayer golf ball of the invention can have an
overall diameter of any size. Although the United States Golf
Association specifications limit the minimum size of a competition
golf ball to 1.68 inches in diameter or more, there is no
specification as to the maximum diameter. Moreover, golf balls of
any size can be used for recreational play. The preferred diameter
of the present golf balls is from about 1.68 inches to 1.8 inches.
The more preferred diameter is from about 1.68 inches to 1.76
inches. The most preferred diameter is about 1.68 inches to 1.7
inches.
[0077] It is to be understood that the invention is not to be
limited to the exact configuration as illustrated and described
herein. For example, it should be apparent that a variety of
materials would be suitable for use in the composition or method of
making the golf ball according to the Detailed Description.
Accordingly, all expedient modifications readily attainable by one
of ordinary skill in the art from the disclosure set forth herein,
or by routine experimentation therefrom, are deemed to be within
the spirit and scope of the invention as defined by the appended
claims.
* * * * *