U.S. patent application number 09/894240 was filed with the patent office on 2002-02-07 for filler-impregnated golf ball core blend.
Invention is credited to Cavallaro, Christopher, Morgan, William, Pasqua, Samuel A. JR..
Application Number | 20020016224 09/894240 |
Document ID | / |
Family ID | 27539569 |
Filed Date | 2002-02-07 |
United States Patent
Application |
20020016224 |
Kind Code |
A1 |
Pasqua, Samuel A. JR. ; et
al. |
February 7, 2002 |
Filler-impregnated golf ball core blend
Abstract
A golf ball comprising a core and a cover, wherein the core
comprises a blend of a first polybutadiene-based material and a
second polybutadiene-based material pre-impregnated with at least
about 50 weight percent of a filler.
Inventors: |
Pasqua, Samuel A. JR.;
(Tiverton, RI) ; Cavallaro, Christopher;
(Lakeville, MA) ; Morgan, William; (Barrington,
RI) |
Correspondence
Address: |
William B. Lacy
Acushnet Company
333 Bridge Street
Fairhaven
MA
02719
US
|
Family ID: |
27539569 |
Appl. No.: |
09/894240 |
Filed: |
June 27, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09894240 |
Jun 27, 2001 |
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09883423 |
Jun 18, 2001 |
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09883423 |
Jun 18, 2001 |
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09775793 |
Feb 5, 2001 |
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09775793 |
Feb 5, 2001 |
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09625544 |
Jul 25, 2000 |
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09625544 |
Jul 25, 2000 |
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09207690 |
Dec 9, 1998 |
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6132324 |
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09207690 |
Dec 9, 1998 |
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08863788 |
May 27, 1997 |
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5885172 |
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Current U.S.
Class: |
473/376 |
Current CPC
Class: |
C08G 18/10 20130101;
C08G 18/3225 20130101; A63B 37/0033 20130101; B29C 39/00 20130101;
B29D 99/0042 20130101; B29L 2031/54 20130101; A63B 37/12 20130101;
B29C 45/00 20130101; A63B 37/0064 20130101; B29C 35/02 20130101;
C09D 175/04 20130101; A63B 37/0003 20130101; C08G 18/10 20130101;
A63B 2037/087 20130101 |
Class at
Publication: |
473/376 |
International
Class: |
A63B 037/12; A63B
037/02 |
Claims
What is claimed is:
1. A golf ball comprising a core and a cover, wherein the core
comprises a blend of a first polybutadiene-based material and a
second polybutadiene-based material pre-impregnated with at least
about 50 weight percent of a filler.
2. The golf ball of claim 1, wherein the filler is selected from
the group consisting of precipitated hydrated silica; clay; talc;
asbestos; glass fibers; aramid fibers; mica; calcium metasilicate;
barium sulfate; zinc sulfide; lithopone; silicates; silicon
carbide; diatomaceous earth; polyvinyl chloride; carbonates;
calcium carbonate; magnesium carbonate; titanium; tungsten;
aluminum; bismuth; nickel; molybdenum; iron; lead; copper; boron;
cobalt; beryllium; zinc; tin; steel; brass; bronze; boron carbide;
tungsten carbide; metal oxides; zinc oxide; iron oxide; aluminum
oxide; titanium oxide; magnesium oxide; zirconium oxide;
particulate carbonaceous materials; graphite; carbon black; cotton
flock; natural bitumen; cellulose flock; leather fiber; glass and
ceramic microspheres; fly ash; and mixtures thereof.
3. The golf ball of claim 2, wherein the filler is tungsten.
4. The golf ball of claim 1, wherein the second polybutadiene-based
material is pre-impregnated with at least about 70 weight percent
of a filler.
5. The golf ball of claim 1, wherein the second polybutadiene-based
material is pre-impregnated with at least about 80 weight percent
of a filler.
6. The golf ball of claim 1, wherein the core comprises a center
and an outer core layer.
7. The golf ball of claim 1, where in the cover comprises an outer
cover layer and an inner cover layer.
8. The golf ball of claim 7, wherein at least one of the outer or
inner cover layers has a thickness of about 0.03 to about 0.04
inches.
9. The golf ball of claim 7, wherein the outer cover layer
comprises a thermoplastic or thermoset polyurethane.
10. The golf ball of claim 1, wherein the core has an outer
diameter of at least about 1.55 inches.
11. The golf ball of claim 1, wherein the core has a weight of less
than about 1.62 oz.
12. The golf ball of claim 11, wherein the core has a weight of
less than about 1.6 oz.
13. The golf ball of claim 1, wherein the second
polybutadiene-based material comprises less than about 5 percent
filler by weight.
14. The golf ball of claim 13, wherein the second
polybutadiene-based material comprises less than about 1 percent
filler by weight.
15. The golf ball of claim 14, wherein the second
polybutadiene-based material comprises less than about 0.05 percent
filler by weight.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of co-pending
application Ser. No. 09/883,423, filed Jun. 18, 2001, which is a
continuation-in-part of co-pending application Ser. No. 09/775,793,
filed Feb. 5, 2001, which is a continuation-in-part of co-pending
application Ser. No. 09/625,544, filed Jul. 25, 2000, which is a
continuation of application Ser. No. 09/207,690, filed Dec. 9,
1998, now U.S. Pat. No. 6,132,324, which is a divisional of
application Ser. No. 08/863,788, filed May 27, 1997, now U.S. Pat.
No. 5,885,172, the disclosures of which are all hereby incorporated
by express reference thereto.
FIELD OF THE INVENTION
[0002] This invention relates generally to golf balls having a core
and a cover, each having at least one layer, and, in particular, to
a golf ball core comprising a blend of a polybutadiene-based
material and a polybutadiene-based material pre-impregnanted with
tungsten filler.
BACKGROUND OF THE INVENTION
[0003] Conventional golf balls can be divided into two general
classes: solid and wound. Solid golf balls include one-piece,
two-piece (i.e., solid core and a cover), and multi-layer (i.e.,
solid core of one or more layers and/or a cover of one or more
layers) golf balls. Wound golf balls typically include a solid,
hollow, or fluid-filled center, surrounded by a tensioned
elastomeric material, and a cover. It is also possible to surround
a hollow or fluid-filled center with a plurality of solid layers.
Solid balls have traditionally been considered longer and more
durable than wound balls, but many solid constructions lack the
"feel" provided by the wound construction.
[0004] More recently, by altering solid golf ball construction and
composition, manufacturers have been able to vary a wide range of
playing characteristics, such as compression, velocity, "feel," and
spin, optimizing each or all as needed. In particular, a variety of
core and cover layer constructions, such as multi-layer golf balls
having dual cover layers and/or dual core layers, have been
investigated and now allow many non-wound balls to exhibit
characteristics previously unattainable in a solid-construction
golf ball. These golf ball layers are typically constructed with a
number of polymeric compositions and blends, including
polybutadiene rubber, thermoplastic and thermoset materials,
polyurethanes, polyamides, and ethylene-based ionomers.
[0005] The core of solid golf balls is the "engine" of the ball,
providing the velocity required for good distance. Too hard a core,
however, can result in a golf ball that provides poor "feel,"
particularly apparent when hit by an accomplished golfer.
Manufacturers are constantly experimenting with various core
compositions and constructions in an effort to optimize both feel
and distance. Most conventional solid cores comprise polybutadiene
rubber or some modified form thereof. For example, polybutadiene
has a number of isomers (i.e., cis-, trans-, and vinyl-) or may
contain a variety of filler materials (i.e., ZnO, W, or
microspheres). When fillers, such as tungsten, are included, they
are generally combined with the polybutadiene master batch just
prior to the molding step. The result is a plethora of tungsten
dust, an obvious hazard that also clogs golf ball molds and is
difficult to clean.
[0006] It has been determined that, by adding tungsten (or other
filler) to a second batch of polybutadiene rubber in concentrated
amounts and subsequently blending the second batch, in a
predetermined amount, with the master batch, tungsten can be added
to the master batch in a non-hazardous manner.
SUMMARY OF THE INVENTION
[0007] The present invention is directed to a A golf ball
comprising a core and a cover, wherein the core comprises a blend
of a first polybutadiene-based material and a second
polybutadiene-based material pre-impregnated with at least about 50
weight percent of a filler. In one embodiment, the filler is
selected from the group consisting of precipitated hydrated silica;
clay; talc; asbestos; glass fibers; aramid fibers; mica; calcium
metasilicate; barium sulfate; zinc sulfide; lithopone; silicates;
silicon carbide; diatomaceous earth; polyvinyl chloride;
carbonates; calcium carbonate; magnesium carbonate; titanium;
tungsten; aluminum; bismuth; nickel; molybdenum; iron; lead;
copper; boron; cobalt; beryllium; zinc; tin; steel; brass; bronze;
boron carbide; tungsten carbide; metal oxides; zinc oxide; iron
oxide; aluminum oxide; titanium oxide; magnesium oxide; zirconium
oxide; particulate carbonaceous materials; graphite; carbon black;
cotton flock; natural bitumen; cellulose flock; leather fiber;
glass and ceramic microspheres; fly ash; and mixtures thereof.
Preferably the filler is tungsten. The second polybutadiene-based
material should be pre-impregnated with at least about 70 weight
percent of a filler and, more preferably, at least about 80 weight
percent of a filler.
[0008] In one ball construction, the core comprises a center and an
outer core layer and, in another, the cover comprises an outer
cover layer and an inner cover layer. At least one of the outer or
inner cover layers, if present, has a thickness of about 0.03 to
about 0.04 inches and, preferably, the outer cover layer comprises
a thermoplastic or thermoset polyurethane. The core should have an
outer diameter of at least about 1.55 inches and/or a weight of
less than about 1.62 oz. Prefeerably, the core has a weight of less
than about 1.6 oz.
[0009] The second polybutadiene-based material can include less
than about 5 percent filler by weight, more preferably, less than
about 1 percent filler by weight, and most preferably, less than
about 0.05 percent filler by weight.
Definitions
[0010] As used herein, substituted and unsubstituted "aryl" groups
means a hydrocarbon ring bearing a system of conjugated double
bonds, typically comprising 4n+2.pi. ring electrons, where n is an
integer. Examples of aryl groups include, but are not limited to
phenyl, naphthyl, anisyl, tolyl, xylenyl and the like. According to
the present invention, aryl also includes heteroaryl groups, e.g.,
pyrimidine or thiophene. These aryl groups may also be substituted
with any number of a variety of functional groups. In addition to
the functional groups described herein in connection with
carbocyclic groups, functional groups on the aryl groups can
include hydroxy and metal salts thereof, mercapto and metal salts
thereof, halogen; amino, nitro, cyano, and amido; carboxyl
including esters, acids, and metal salts thereof, silyl; acrylates
and metal salts thereof, sulfonyl or sulfonamide; and phosphates
and phosphites; and a combination thereof.
[0011] As used herein, the term "Atti compression" is defined as
the deflection of an object or material relative to the deflection
of a calibrated spring, as measured with an Atti Compression Gauge,
that is commercially available from Atti Engineering Corp. of Union
City, N.J. Atti compression is typically used to measure the
compression of a golf ball. Compression values are dependent on the
diameter of the article being measured. When the Atti Gauge is used
to measure cores having a diameter of less than 1.680 inches, it
should be understood that a metallic or other suitable shim is used
to make the measured object 1.680 inches in diameter.
[0012] As used herein, substituted and unsubstituted "carbocyclic"
means cyclic carbon-containing compounds, including, but not
limited to cyclopentyl, cyclohexyl, cycloheptyl, adamantyl, and the
like. Such cyclic groups may also contain various substituents in
which one or more hydrogen atoms has been replaced by a functional
group. Such functional groups include those described above, and
lower alkyl groups having from 1-28 carbon atoms. The cyclic groups
of the invention may further comprise a heteroatom.
[0013] As used herein, "cis-to-trans catalyst" means any component
or a combination thereof that will convert at least a portion of
cis-polybutadiene isomer to trans-polybutadiene isomer at a given
temperature. It should be understood that the combination of the
cis-isomer, the trans-isomer, and any vinyl-isomer, measured at any
given time, comprises 100 percent of the polybutadiene.
[0014] As used herein, the term "coefficient of restitution"
("COR") for golf balls is defined as the ratio of the rebound
velocity to the inbound velocity when balls are fired into a rigid
plate. The inbound velocity is understood to be 125 ft/s.
[0015] As used herein, the term "dynamic stiffness" is defined as
load divided by the deflection for a 1.4-mm spherical radius
penetration probe oscillating at 1 Hz with an amplitude of 100
.mu.m. The probe dynamically penetrates the surface of a sample
material. Material samples of spherical cores were prepared by
sectioning out a 6-mm-thick layer along the equator of core to
produce a disk 6-mm-thick with one surface containing the geometric
center of the core. By positioning the probe at any selected radial
position on the disk, a dynamic stiffness measurement may be
obtained. Accurate dynamic measurements may be made by keeping the
material sample at a substantially uniform temperature. The dynamic
stiffness was acquired using a Dynamic Mechanical Analyzer, Model
DMA 2980 available from TA Instruments Corporation of New Castle,
Del. The instrument setting for the DMA 2980 were 1-Hz frequency,
100-.mu.m amplitude, 0.3-N static load, and auto strain of 105
percent. The 1.4-mm spherical radius probe is available from TA
Instruments as a penetration kit accessory to the DMA 2980. The DMA
2980 is equipped with a temperature-controlled chamber that enables
testing at a wide variety of ambient temperatures.
[0016] The method and instrument utilized for measuring "dynamic
stiffness" may also be used to measure loss tangent. Loss tangent
is the ratio of loss modulus to storage modulus. Loss modulus is
the portion of modulus which is out of phase with displacement and
storage modulus is the portion of modulus which is in phase with
displacement. The DMA 2980 automatically calculates and reports
loss tangent.
[0017] As used herein, the term "fluid" includes a liquid, a paste,
a gel, a gas, or any combination thereof.
[0018] As used herein, the term "Group VIA" means a component that
includes a sulfur, selenium, tellurium, or a combination
thereof.
[0019] As used herein, the term "sulfur component" means a
component that is elemental sulfur, polymeric sulfur, or a
combination thereof. It should be further understood that
"elemental sulfur" refers to the ring structure of S.sub.8 and that
"polymeric sulfur" is a structure including at least one additional
sulfur relative to the elemental sulfur.
[0020] As used herein, the term "molecular weight" is defined as
the absolute weight average molecular weight.
[0021] As used herein, the term "multilayer" means at least two
layers and includes fluid or liquid center balls, wound balls,
hollow-center balls, and balls with at least two intermediate
layers and/or cover layers.
[0022] 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.
[0023] As used herein the term "resilience index" is defined as the
difference in loss tangent (tan .delta.) measured at 10 cpm and
1000 cpm divided by 990 (the frequency span) multiplied by 100,000
(for normalization and unit convenience). The loss tangent is
measured using an RPA 2000 manufactured by Alpha Technologies of
Akron, Ohio. The RPA 2000 is set to sweep from 2.5 to 1000 cpm at a
temperature of 100.degree. C. using an arc of 0.5 degrees. An
average of six loss tangent measurements were acquired at each
frequency and the average is used in calculation of the resilience
index.
[0024] As used herein, the term "substantially free" means less
than about 5 weight percent, preferably less than about 3 weight
percent, more preferably less than about 1 weight percent, and most
preferably less than about 0.01 weight percent.
[0025] As used herein, "flexural modulus" is measured by ASTM
D6272-98, Procedure B, as modified, about two weeks after polymer
formation.
[0026] As used herein, the term "stiffness" refers to the flexural
modulus.
[0027] As used herein, "hardness" refers to the hardness of the
material forming the particular layer of the ball being discussed,
as measured by ASTM D2240-00. Hardness does not refer to the
hardness measured on the golf ball.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] The present invention is directed to a golf ball core
comprising a blend of a first polybutadiene-based material and a
second polybutadiene-based material impregnated with a filler.
Preferably the core comprises the tungsten-impregnated
polybutadiene ("W-PB") of the present invention. In one embodiment,
golf ball includes a core of one or more layers, such as a center
and outer core layer, the center comprising the W-PB, a cover
layer, and a layer disposed between the core and the cover.
Optionally, the center is covered with a wound layer.
[0029] Thus, improved golf ball cores can be prepared according to
the invention by including a blend of a first amount of
polybutadiene or a reaction product thereof and a second amount of
polybutadiene that has been pre-impregnated with tungsten or other
filler; and disposing a cover including at least one layer,
preferably including a polyurethane material, over the core or
optional intermediate layer.
[0030] Depending on the desired properties, balls prepared
according to the invention can exhibit substantially the same or
higher resilience, or coefficient of restitution ("COR"), with a
decrease in compression or modulus, compared to balls of
conventional construction. Additionally, balls prepared according
to the invention can also exhibit substantially higher resilience,
or COR, without an increase in compression, compared to balls of
conventional construction.
[0031] Another measure of this resilience is the "loss tangent," or
tan .delta., which is obtained when measuring the dynamic stiffness
of an object. The rigidity or compressive stiffness of a golf ball
may be measured, for example, by the dynamic stiffness. To produce
golf balls having a desirable compressive stiffness, the dynamic
stiffness of the polybutadiene should be less than about 50,000 N/m
at -50.degree. C. Preferably, the dynamic stiffness should be from
about 10,000 to 40,000 N/m at -50.degree. C., more preferably, the
dynamic stiffness should be from about 20,000 to 30,000 N/m at
-50.degree. C. The polybutadiene preferably has a loss tangent
below about 0.1 at -50.degree. C., and more preferably below about
0.07 at -50.degree. C.
[0032] The center composition preferably includes at least one
rubber material having a resilience index of at least about 40.
Preferably, the resilience index is at least about 50. A comparison
of a number of polybutadiene polymers are listed in Table 1 below.
Polymers that produce resilient golf balls and, therefore, are
suitable for use in the center or other portions of a golf ball
according to the present invention include, but are not limited to,
CB23, CB22, BR60, and 1207G.
1TABLE 1 Resilience Index of example polybutadiene polymers Tan
.delta. at Resilience Index at Rubber 10 cpm 1000 cpm 100.degree.
C. CB23 0.954 0.407 55 CB22 0.895 0.358 54 BR-60 0.749 0.350 40
BR-40 0.841 0.446 40 Taktene 8855 0.720 0.414 31 CARIFLEX BR1220
0.487 0.439 5 BUDENE 1207G 0.825 0.388 44
[0033] A suitable pre-impregnated polybutadiene-based material
includes Poly-dispersion RD-1185P, commercially available from
Rhein Chemie of Trenton, N.J. The second polybutadiene-based
material preferably contains greater than about 50 percent filler,
by weight, more preferably greater than about 70 percent filler, by
weight, and most preferably greater than about 80 percent filler,
by weight. In the most preferred embodiment, the filler is
tungsten. The second polybutadiene-based material can include less
than about 5 percent filler by weight, more preferably, less than
about 1 percent filler by weight, and most preferably, less than
about 0.05 percent filler by weight.
[0034] The golf ball core polybutadiene material, including W-PB,
typically has a hardness of at least about 15 Shore A, preferably
from about 30 Shore A to 80 Shore D, more preferably from about 50
Shore A to 60 Shore D. In one preferred embodiment, the core has a
hardness of about 20 to 85 Shore C, preferably from about 40 to 80
Shore C, and more preferably from about 60 to 70 Shore C at the
geometric center. The specific gravity is typically greater than
about 0.7, preferably greater than about 1.0, for the golf ball
polybutadiene material (including W-PB).
[0035] Additionally, the unvulcanized rubber, such as
polybutadiene, in golf balls prepared according to the invention
typically has a Mooney viscosity of about 40 to about 80,
preferably from about 45 to about 60, and more preferably from
about 45 to about 55. Mooney viscosity is typically measured
according to ASTM D 1646-99.
[0036] In another embodiment, at least one of the core center or
outer layer includes a reaction product that includes a
cis-to-trans catalyst, a first amount of polybutadiene, a second
amount of polybutadiene including a filler, a free radical source,
and a crosslinking agent. Preferably, the polybutadiene is used to
form at least a portion of the center of the golf ball. Preferably,
the polybutadiene has a first dynamic stiffness measured at
-50.degree. C. that is less than about 130 percent of a second
dynamic stiffness measured at 0.degree. C. More preferably, the
first dynamic stiffness is less than about 125 percent of the
second dynamic stiffness. Most preferably, the first dynamic
stiffness is less than about 110 percent of the second dynamic
stiffness.
[0037] Thus, the invention also includes a method to convert the
cis-isomer of the polybutadiene to the trans-isomer during a
molding cycle and to form a golf ball. Various combinations of
polymers, cis-to-trans catalysts, fillers, crosslinkers, and a
source of free radicals, may be used. To obtain a higher resilience
and lower compression center or intermediate layer, a
high-molecular weight polybutadiene with a cis-isomer content
preferably greater than about 90 percent is converted to increase
the percentage of trans-isomer content at any point in the golf
ball or portion thereof, preferably to increase the percentage
throughout substantially all of the golf ball or portion thereof,
during the molding cycle. More preferably, the cis-polybutadiene
isomer is present in an amount of greater than about 95 percent of
the total polybutadiene content. Without wishing to be bound by any
particular theory, it is believed that a low amount of
1,2-polybutadiene isomer ("vinyl-polybutadiene") is desired in both
the initial polybutadiene and the reaction product. Typically, the
vinyl polybutadiene isomer content is less than about 7 percent.
Preferably, the vinyl polybutadiene isomer content is less than
about 4 percent. More preferably, the vinyl polybutadiene isomer
content is less than about 2 percent. Without wishing to be bound
by any particular theory, it is also believed that the resulting
mobility of the combined cis- and trans-polybutadiene backbone is
responsible for the lower modulus and higher resilience of the
reaction product and golf balls including the same. The W-PB may be
blended with the master batch of polybutadiene rubber prior to,
during, or after conversion takes place. In one embodiment, the
second polybutadiene-based material (the W-PB) undergoes a
cis-to-trans conversion as well.
[0038] In one embodiment the coefficient of restitution of the golf
ball at a club head speed of 160 ft/s is at least about 0.76 and
the magnitude of the gradient of the coefficient of restitution to
an inbound velocity is at least about 0.001 s/ft.
[0039] The invention also relates to a golf ball having at least a
center including a first polybutadiene and a second W-PB, each
having a molecular weight of greater than about 300,000 and a
resilience index of at least about 40, having an outer diameter of
at least about 1.00 inches, an inner cover layer surrounding the
optional outer core layer, and an outer cover layer disposed around
the inner cover layer, the outer cover layer including a
polyurethane composition formed from a prepolymer having less than
7.5 percent by weight unreacted isocyanate groups and the inner
cover comprising polyisoprene. Preferrably, the center has an outer
diameter of at least about 1.51 inches, more preferrably at least
about 1.55 inches.
[0040] To produce a polymer reaction product that exhibits the
higher resilience and lower modulus (lower compression) properties
that are desirable and beneficial to golf ball playing
characteristics, high-molecular-weight cis-1,4-polybutadiene,
preferably may be converted to the trans-isomer during the molding
cycle. "High-molecular weight" typically means that the
polybutadiene material has a molecular weight average of greater
than about 200,000. Preferably, the polybutadiene molecular weight
is greater than about 250,000, more preferably from about 300,000
to 500,000. The cis-to-trans conversion requires the presence of a
cis-to-trans catalyst, such as an organosulfur or metal-containing
organosulfur compound, a substituted or unsubstituted aromatic
organic compound that does not contain sulfur or metal, an
inorganic sulfide compound, an aromatic organometallic compound, or
mixtures thereof. The cis-to-trans catalyst component may include
one or more of the cis-to-trans catalysts described herein. For
example, the cis-to-trans catalyst may be a blend of an
organosulfur component and an inorganic sulfide component.
[0041] In one embodiment, the at least one organosulfur component
is substantially free of metal, which typically means less than
about 10 weight percent metal, preferably less than about 3 weight
percent metal, more preferably less than about 1 weight percent
metal, and most preferably only trace amounts of metal, such as
less than about 0.01 weight percent. In another embodiment, the
organosulfur component is completely free of metal.
[0042] As used herein when referring to the invention, the term
"organosulfur compound(s)" or "organosulfur component(s)," means at
least one of 4,4'-diphenyl disulfide; 4,4'-ditolyl disulfide;
2,2'-benzamido diphenyl disulfide; bis(2-aminophenyl)disulfide;
bis(4-aminophenyl)disulf- ide; bis(3-aminophenyl)disulfide;
2,2'-bis(4-aminonaphthyl)disulfide; 2,2'-bis(3-aminonaphthyl)
disulfide; 2,2'-bis(4-aminonaphthyl)disulfide;
2,2'-bis(5-aminonaphthyl)disulfide;
2,2'-bis(6-aminonaphthyl)disulfide;
2,2'-bis(7-aminonaphthyl)disulfide; 2,2'-bis(8-aminonaphthyl)
disulfide; 1,1'-bis(2-aminonaphthyl)disulfide;
1,1'-bis(3-aminonaphthyl)disulfide;
1,1'-bis(3-aminonaphthyl)disulfide;
1,1'-bis(4-aminonaphthyl)disulfide; 1,1'-bis(5-aminonaphthyl)
disulfide; 1,1'-bis(6-aminonaphthyl)disulfide;
1,1'-bis(7-aminonaphthyl)disulfide;
1,1'-bis(8-aminonaphthyl)disulfide;
1,2'-diamino-1,2'-dithiodinaphthalene;
2,3'-diamino-1,2'-dithiodinaphthal- ene;
bis(4-chlorophenyl)disulfide; bis(2-chlorophenyl)disulfide;
bis(3-chlorophenyl)disulfide; bis(4-bromophenyl)disulfide;
bis(2-bromophenyl)disulfide; bis(3-bromophenyl)disulfide;
bis(4-fluorophenyl)disulfide; bis(4-iodophenyl)disulfide;
bis(2,5-dichlorophenyl)disulfide; bis(3,5-dichlorophenyl)disulfide;
bis(2,4-dichlorophenyl)disulfide; bis(2,6-dichlorophenyl)disulfide;
bis(2,5-dibromophenyl)disulfide; bis(3,5-dibromophenyl) disulfide;
bis(2-chloro-5-bromophenyl)disulfide;
bis(2,4,6-trichlorophenyl)disulfide- ;
bis(2,3,4,5,6-pentachlorophenyl)disulfide;
bis(4-cyanophenyl)disulfide; bis(2-cyanophenyl) disulfide;
bis(4-nitrophenyl)disulfide; bis(2-nitrophenyl)disulfide;
2,2'-dithiobenzoic acid ethylester; 2,2'-dithiobenzoic acid
methylester; 2,2'-dithiobenzoic acid; 4,4'-dithiobenzoic acid
ethylester; bis(4-acetylphenyl)disulfide;
bis(2-acetylphenyl)disulfide; bis(4-formylphenyl) disulfide;
bis(4-carbamoylphenyl)disulfide; 1,1'-dinaphthyl disulfide;
2,2'-dinaphthyl disulfide; 1,2'-dinaphthyl disulfide;
2,2'-bis(1-chlorodinaphthyl)disulfide; 2,2'-bis(1-bromonaphthyl)
disulfide; 1,1'-bis(2-chloronaphthyl)disulfide;
2,2'-bis(1-cyanonaphthyl)- disulfide;
2,2'-bis(1-acetylnaphthyl)disulfide; and the like; or a mixture
thereof. Preferred organosulfur components include 4,4'-diphenyl
disulfide, 4,4'-ditolyl disulfide, or 2,2'-benzamido diphenyl
disulfide, or a mixture thereof. A more preferred organosulfur
component includes 4,4'-ditolyl disulfide. The organosulfur
cis-to-trans catalyst, when present, is preferably present in an
amount sufficient to produce the reaction product so as to contain
at least about 12 percent trans-polybutadiene isomer, but typically
is greater than about 32 percent trans-polybutadiene isomer based
on the total resilient polymer component. In another embodiment,
metal-containing organosulfur components can be used according to
the invention. Suitable metal-containing organosulfur components
include, but are not limited to, cadmium, copper, lead, and
tellurium analogs of diethyldithiocarbamate, diamyldithiocarbamate,
and dimethyldithiocarbamate, or mixtures thereof.
[0043] Suitable substituted or unsubstituted aromatic organic
components that do not include sulfur or a metal include, but are
not limited to, 4,4'-diphenyl acetylene, azobenzene, or a mixture
thereof. The aromatic organic group preferably ranges in size from
C.sub.6 to C.sub.20, and more preferably from C.sub.6 to C.sub.10.
Suitable inorganic sulfide components include, but are not limited
to titanium sulfide, manganese sulfide, and sulfide analogs of
iron, calcium, cobalt, molybdenum, tungsten, copper, selenium,
yttrium, zinc, tin, and bismuth.
[0044] A substituted or unsubstituted aromatic organic compound may
also be included in the cis-to-trans catalyst. Suitable substituted
or unsubstituted aromatic organic components include, but are not
limited to, components having the formula
(R.sub.1).sub.x-R.sub.3-M-R.sub.4-(R.su- b.2).sub.y, wherein
R.sub.1 and R.sub.2 are each hydrogen or a substituted or
unsubstituted C.sub.1-20 linear, branched, or cyclic alkyl, alkoxy,
or alkylthio group, or a single, multiple, or fused ring C.sub.6 to
C.sub.24 aromatic group; x and y are each an integer from 0 to 5;
R.sub.3 and R.sub.4 are each selected from a single, multiple, or
fused ring C.sub.6 to C.sub.24 aromatic group; and M includes an
azo group or a metal component. R.sub.3 and R.sub.4 are each
preferably selected from a C.sub.6 to C.sub.10 aromatic group, more
preferably selected from phenyl, benzyl, naphthyl, benzamido, and
benzothiazyl. R.sub.1 and R.sub.2 are each preferably selected from
a substituted or unsubstituted C.sub.1-10 linear, branched, or
cyclic alkyl, alkoxy, or alkylthio group or a C.sub.6 to C.sub.10
aromatic group. When R.sub.1-R.sub.4 are substituted, the
substitution may include one or more of the following substituent
groups: hydroxy and metal salts thereof; mercapto and metal salts
thereof; halogen; amino, nitro, cyano, and amido; carboxyl
including esters, acids, and metal salts thereof; silyl; acrylates
and metal salts thereof; sulfonyl or sulfonamide; and phosphates
and phosphites. When M is a metal component, it may be any suitable
elemental metal available to those of ordinary skill in the art.
Typically, the metal will be a transition metal, although
preferably it is tellurium or selenium. In one embodiment, the
aromatic organic compound is substantially free of metal, while in
another embodiment the aromatic organic compound is completely free
of metal.
[0045] The cis-to-trans catalyst can also include a Group VIA
component. Elemental sulfur and polymeric sulfur are commercially
available from, e.g., Elastochem, Inc. of Chardon, Ohio. Exemplary
sulfur catalyst compounds include PB(RM-S)-80 elemental sulfur and
PB(CRST)-65 polymeric sulfur, each of which is available from
Elastochem, Inc. An exemplary tellurium catalyst under the
tradename TELLOY.RTM. and an exemplary selenium catalyst under the
tradename VANDEX.RTM. are each commercially available from RT
Vanderbilt. The cis-to-trans catalyst is typically present in an
amount from about 0.1 to 10 parts per hundred of the total
resilient polymer component. Preferably, the cis-to-trans catalyst
is present in an amount from about 0.1 to 8 parts per hundred of
the total resilient polymer component. More preferably, the
cis-to-trans catalyst is present in an amount from about 0.1 to 5
parts per hundred of the total resilient polymer component. The
cis-to-trans catalyst is typically present in an amount sufficient
to produce the reaction product so as to increase the
trans-polybutadiene isomer content to contain from about 5 percent
to 70 percent trans-polybutadiene based on the total resilient
polymer component.
[0046] A free-radical source, often alternatively referred to as a
free-radical initiator, is required in the composition and method.
The free-radical source is typically a peroxide, and preferably an
organic peroxide. Suitable free-radical sources include di-t-amyl
peroxide, di(2-t-butyl-peroxyisopropyl)benzene peroxide,
3,3,5-trimethyl cyclohexane, a-a bis(t-butylperoxy)
diisopropylbenzene,
1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, dicumyl
peroxide, di-t-butyl peroxide, 2,5-di-(t-butylperoxy)-2,5-dimethyl
hexane, n-butyl-4,4-bis(t-butylperoxy) valerate, lauryl peroxide,
benzoyl peroxide, t-butyl hydroperoxide, and the like, and any
mixture thereof. The peroxide is typically present in an amount
greater than about 0.1 parts per hundred of the total resilient
polymer component, preferably about 0.1 to 15 parts per hundred of
the polymer, and more preferably about 0.2 to 5 parts per hundred
of the total polymer. It should be understood by those of ordinary
skill in the art that the presence of certain cis-to-trans
catalysts according to the invention may require a larger amount of
free-radical source, such as the amounts described herein, compared
to conventional cross-linking reactions. The initiator(s) at 100%
activity are preferably added in an amount ranging from about 0.05
phr to 5 phr based upon 100 parts of polybutadiene. More
preferably, the amount of initiator added ranges from about 0.15
phr to 4 phr, and most preferably from about 0.25 phr to 3 phr. The
free radical source may alternatively or additionally be one or
more of an electron beam, UV or gamma radiation, x-rays, or any
other high energy radiation source capable of generating free
radicals. It should be further understood that heat often
facilitates initiation of the generation of free radicals.
[0047] A crosslinking agent is included to increase the hardness of
the reaction product. Suitable crosslinking agents include one or
more metallic salts of unsaturated fatty acids or monocarboxylic
acids, such as zinc, aluminum, sodium, lithium, nickel, calcium, or
magnesium acrylate salts, and the like, and mixtures thereof.
Preferred acrylates include zinc acrylate, zinc diacrylate, zinc
methacrylate, and zinc dimethacrylate, and mixtures thereof. The
crosslinking agent must be present in an amount sufficient to
crosslink a portion of the chains of polymers in the resilient
polymer component. For example, the desired compression may be
obtained by adjusting the amount of crosslinking. This may be
achieved, for example, by altering the type and amount of
crosslinking agent, a method well-known to those of ordinary skill
in the art. The crosslinking agent is typically present in an
amount greater than about 0.1 percent of the resilient polymer
component, preferably from about 10 to 40 percent of the resilient
polymer component, more preferably from about 10 to 30 percent of
the resilient polymer component. When an organosulfur is selected
as the cis-to-trans catalyst, zinc diacrylate may be selected as
the crosslinking agent and is preferably present in an amount of
less than about 25 phr. Suitable, commercially available, zinc
diacrylates include those from the Sartomer Corporation.
[0048] As used herein, the term "fillers" includes any compound or
composition that can be used to adjust the density and/or other
properties of the subject golf ball core. Fillers are typically
polymeric or mineral particles. Exemplary fillers include
precipitated hydrated silica; clay; talc; asbestos; glass fibers;
aramid fibers; mica; calcium metasilicate; barium sulfate; zinc
sulfide; lithopone; silicates; silicon carbide; diatomaceous earth;
polyvinyl chloride; carbonates such as calcium carbonate and
magnesium carbonate; metals such as titanium, tungsten, aluminum,
bismuth, nickel, molybdenum, iron, lead, 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. Fillers may be added at any point in the molding or
blending process. In the most preferred embodiment, the filler,
preferably tungsten, is added to a second amount of polybutadiene
rubber prior to blending with the first amount of polybutadiene
rubber to form the core.
[0049] 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 1.62 oz 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, the specific gravity can be about 2 to 6. In
one embodiment, the center material can have a specific gravity of
about 1 to 5, preferably about 1.1 to 2.
[0050] Antioxidants may also optionally be included in the
polybutadiene material in the centers produced according to the
present invention. Antioxidants are compounds that can inhibit or
prevent the oxidative degradation of the polybutadiene.
Antioxidants useful in the present invention include, but are not
limited to, dihydroquinoline antioxidants, amine type antioxidants,
and phenolic type antioxidants.
[0051] Other optional ingredients, such as accelerators, e.g.,
tetramethylthiuram, peptizers, processing aids, processing oils,
plasticizers, dyes and pigments, as well as other additives well
known to those of ordinary skill in the art may also be used in the
present invention in amounts sufficient to achieve the purpose for
which they are typically used.
[0052] The polymers, free-radical initiator, filler(s), and any
other materials used in forming either the golf ball center or any
portion of the core, in accordance with invention, may be combined
to form a mixture by any type of mixing known to one of ordinary
skill in the art. Suitable types of mixing include single pass and
multi-pass mixing, and the like. The crosslinking agent, and any
other optional additives used to modify the characteristics of the
golf ball center or additional layer(s), may similarly be combined
by any type of mixing. A single-pass mixing process where
ingredients are added sequentially is preferred, as this type of
mixing tends to increase efficiency and reduce costs for the
process. The preferred mixing cycle is single step wherein the
polymer, cis-to-trans catalyst, filler, zinc diacrylate, and
peroxide are added sequentially. Suitable mixing equipment is well
known to those of ordinary skill in the art, and such equipment may
include a Banbury mixer, a two-roll mill, or a twin screw extruder.
Conventional mixing speeds and temperatures for combining polymers
are typically used. Suitable mixing speeds and temperatures are
well-known to those of ordinary skill in the art, or may be readily
determined without undue experimentation.
[0053] The mixture can be subjected to, e.g., a compression or
injection molding process, to obtain solid spheres for the center
or hemispherical shells for forming an intermediate layer. The
polymer mixture is subjected to a molding cycle in which heat and
pressure are applied while the mixture is confined within a mold.
The cavity shape depends on the portion of the golf ball being
formed. The compression and heat liberates free radicals by
decomposing one or more peroxides, which may initiate the
cis-to-trans conversion and crosslinking simultaneously. The
temperature and duration of the molding cycle can be readily
selected based upon the type of peroxide and cis-trans catalyst
selected. The molding cycle may have a single step of molding the
mixture at a single temperature for a fixed time duration. The
molding cycle may also include a two-step process, in which the
polymer mixture is held in the mold at an initial temperature for
an initial duration of time, followed by holding at a second,
typically higher temperature for a second duration of time. In a
preferred embodiment of the current invention, a single-step cure
cycle is employed. Single-step processes are effective and
efficient, reducing the time and cost of a two-step process.
[0054] The polybutadiene, cis-to-trans conversion catalyst,
additional polymers, free-radical initiator, filler, and any other
materials used in forming either the golf ball center or any
portion of the core, in accordance with the invention, may be
combined to form a golf ball by an injection molding process, which
is also well-known to one of ordinary skill in the art. Although
the curing time depends on the various materials selected, a
particularly suitable curing time is about 5 to 18 minutes,
preferably from about 8 to 15 minutes, and more preferably from
about 10 to 12 minutes. Those of ordinary skill in the art will be
readily able to adjust the curing time upward or downward based on
the particular materials used and the discussion herein.
[0055] The cured polymer component, which contains a greater amount
of trans-polybutadiene than the uncured polymer component, is
formed into an article having a first hardness at a point in the
interior and a surface having a second hardness such that the
second hardness differs from the first hardness by greater than 10
percent of the first hardness. Preferably, the article is a sphere
and the point is the midpoint of the article. In another
embodiment, the second hardness differs from the first by greater
than 20 percent of the first hardness. The cured article also has a
first amount of trans-polybutadiene at an interior location and a
second amount of trans-polybutadiene at a surface location, wherein
the first amount is at least about 6 percent less than the second
amount, preferably at least about 10 percent less than the second
amount, and more preferably at least about 20 percent less than the
second amount. The interior location is preferably a midpoint and
the article is preferably a sphere.
[0056] The compression of the core, or portion of the core, of golf
balls prepared according to the invention is typically from about
15 to 100. In one embodiment, the compression is below about 50,
more preferably below about 25. In a preferred embodiment, the
compression is from about 60 to 90, more preferably from about 70
to 85. Various equivalent methods of measuring compression exist.
For example, a 70 Atti compression is equivalent to a center
hardness of 3.2 mm deflection under a 100 kg load and a "spring
constant" of 36 kgf/mm. In one embodiment, the golf ball core has a
deflection of about 3.3 mm to 7 mm under a 130 kg-10 kg test.
[0057] In one embodiment, the center includes a material formed
from a conversion reaction of polybutadiene having a first amount
of trans-isomer, a free radical source, and at least one
cis-to-trans catalyst. In a preferred embodiment, the reaction
occurs at a temperature and for a time sufficient to form a
polybutadiene reaction product having a second amount of
trans-isomer greater than the first amount of trans-isomer. In one
embodiment, the cis-to-trans catalyst includes at least one of an
organosulfur compound, an inorganic sulfur compound, an aromatic
organometallic compound, a metal-organosulfur compound, tellurium,
selenium, elemental sulfur, a polymeric sulfur, or an aromatic
organic compound. Preferably, the catalyst includes an organosulfur
component, and in one preferred embodiment the catalyst includes at
least one of 4,4'-diphenyl disulfide, 4,4'-ditolyl disulfide, or
2,2'-benzamido diphenyl disulfide, or a combination thereof. The
cis-to-trans catalyst is typically present in an amount from about
0.1 to 10 parts per hundred of polybutadiene. In a most preferred
embodiment, the center also includes a second amount of W-PB.
[0058] Preferably, the core has an outer diameter of at least about
1.0 inch, more preferably about 1.3 to 1.6 inches, most preferably
from about 1.55 inches to about 1.6 inches. As stated above, the
outer layer may be formed of windings of at least one thread. In
this case, the center diameter is preferably at least about 1.4
inches.
[0059] Thread materials including polyisoprene, polyether urea,
polyester, polyethylene, polypropylene, or combinations thereof may
be used with the present invention. Threads used in the present
invention may be formed using a variety of processes including
conventional calendering and slitting. Furthermore, processes such
as melt spinning, wet spinning, dry spinning or polymerization
spinning may also be used to provide threads. Other useful polymers
include poly(olefins), aliphatic polyamides, and aromatic
polyesters, all of which are suitable thread materials.
[0060] Threads formed of multiple strands can also be prepared
according to the invention by reference to U.S. Pat. No. 6,149,535,
the disclosure of which is hereby incorporated herein by express
reference thereto.
[0061] The thread preferably includes a polymeric material.
Suitable polymers include polyether urea, such as LYCRA.RTM.;
polyester urea; polyester block copolymers, such as HYTREL.RTM.;
isotactic-poly(propylene- ); polyethylene; polyamide;
poly(oxymethylene); polyketone; poly(ethylene terephthalate); such
as DACRON.RTM.; poly(p-phenylene terephthalamide); such as
KEVLAR.RTM.; poly(acrylonitrile); such as ORLON.RTM.;
trans-diaminodicyclohexylmethane and dodecanedicarboxylic acid,
such as QUINA.RTM.. LYCRA.RTM., HYTREL.RTM., DACRON.RTM.,
KEVLAR.RTM., ORLON.RTM., and QUINA.RTM. are available from E.I.
DuPont de Nemours & Co. of Wilmington, Del. Glass fiber and,
for example, S-GLASS.RTM. from Corning Corporation can also be
used. Also, D7 Globe thread by Globe Manufacturing of Fall River,
Mass. can be used. Indeed, a mixture of any of the thread materials
discussed herein can be included in a thread layer of the
invention.
[0062] A golf ball of the present invention can also be formed by
initially forming a shell by compression molding hemispherical
cups, the cups are bonded together to form the shell to create a
cavity and filling the cavity with fluid or liquid to form a fluid
filled center. In one embodiment, the shell is covered by a solid
layer. In another embodiment, a thread can then be wound directly
around the shell to form the wound layer as previously described if
there are no additional layers desired between the center and wound
layer; otherwise, the intermediate layer(s)are formed around the
shell before the tensioned material is disposed about the center
layers. The cover can then be disposed about the wound layer.
[0063] Properties that are desirable for the cover are good
moldability, high abrasion resistance, high tear strength, high
resilience, and good mold release, among others. The cover
typically has a thickness to provide sufficient strength, good
performance characteristics and durability. The cover preferably
has a thickness of less than about 0.1 inches, more preferably,
less than about 0.05 inches, and most preferably, from about 0.01
to about 0.04 inches. In another embodiment, the outer cover layer
is less than 0.02 inches and preferably less than 0.01 inches. The
invention is particularly directed towards a multilayer golf ball
that includes a core, an inner cover layer, and an outer cover
layer. In this embodiment, preferably, both the inner and outer
cover layers has a thickness of less than about 0.05 inches, more
preferably the thickness of each cover layer is from about 0.02 to
about 0.04 inches.
[0064] In the embodiment with an inner and outer cover layers, the
inner cover layer can be prepared as follows. Although injection or
compression molding, or casting, can be used, in one preferred
embodiment the inner cover is formed over the core by using
compression molding. A suitable speed for increasing the pressure
to close the molds around the cores can be readily determined.
Thus, a time on the order of greater than 1 second to about 30
seconds, preferably 2 seconds to 20 seconds may be suitable
depending on other process conditions and the materials involved.
In one preferred embodiment, a time of about 10 to about 15 seconds
is most suitable for closing the mold. It should be understood that
this time is measured from when each half of the mold is in contact
with the polyisoprene material there between and relates to the
time over which the pressure on the molds and centers is increased
to fully close the molds. This method advantageously helps inhibit
or avoid weld lines that can occur using injection molding
methods.
[0065] The inner cover may be made of any natural or synthetic
balata material, i.e., trans-polyisoprene, blends of balata with
other materials, or similar materials that may be molded about a
core including the first polybutadiene-based material and the
second W-PB of the present invention, thermoset and thermoplastic
materials, ionomers, polyamides, polyureas, and polyurethanes. In
one embodiment, compression molding is used to form the inner cover
layer. In one embodiment, the inner cover may also contain
styrene-butadiene rubber ("SBR") or SBR-reinforced resin, for
example, available as PLIOLITE.RTM. from Goodyear Tire & Rubber
Co. of Akron, Ohio as a stiffener, and one or more fillers to
adjust the specific gravity. Suitable fillers include those
described herein. Preferred fillers are those that have a small
particle size and high specific gravity, such as tungsten. The
inner cover may, but is not required to be, vulcanized as it is
applied to the wound core, or in a post molding step. The outer
surface of the inner cover layer may be treated prior to
application of the outer cover, by one or more of halogenation,
chemical surface modification or treatment (i.e., silane coupling
agents), UV radiation, electron beam exposure, microwave radiation,
coating (via spray, dip, or electrostatic application), plasma, or
corona discharge, as described in co-pending U.S. patent
application Ser. No. 09/389,058, which is incorporated herein by
express reference thereto. Preferably, the treatment will increase
adhesion of the inner cover layer to the outer cover. The treatment
may be used to activate a material compounded into the base
material which will have the same preferred interaction with the
outer cover to facilitate, for example, adhesion. The treatment may
further be used to activate a material such that the softening
point of the base material is increased, improving the temperature
stability of the final product.
[0066] For a ball having a diameter of 1.68 inches, the outer
diameter of the inner cover layer, if present, is preferably from
about 1.55 inches to 1.67 inches. In one embodiment, the outer
diameter is from about 1.6 inches to about 1.64 inches. An
exemplary inner cover layer outer diameter is 1.62 inches. In
another embodiment, the outer diameter is between about 1.66 and
about 1.67 inches. The inner cover layer preferably has a thickness
of about 0.01 inches to 0.1 inches, preferably about 0.02 inches to
0.05 inches. In one preferred embodiment, the thickness of the
inner cover layer is about 0.03 inches to 0.04 inches. In another
embodiment, the inner cover is between 0.05 and 0.09 inches. In one
preferred embodiment, the inner cover layer has a hardness of about
20 to 80 Shore D, preferably about 50 to 75 Shore D, and more
preferably about 52 to 64 Shore D when measured on the core. The
compression of the core and inner cover layer is typically from
about 20 to 100, preferably from about 30 to 75. In one preferred
embodiment, the core and inner cover layer compression is from
about 40 to 70. In one embodiment, the inner cover layer has a
specific gravity of about 0.8 to 1.3, preferably about 0.9 to 1.2.
The loss tangent of the inner cover layer can, in one embodiment,
be from about 0.03 to 0.08 from a temperature of about -30.degree.
C. to 20.degree. C. The elasticity and complex modulus of the inner
cover layer can be from about 5,000 to 12,000 kgf/cm.sup.2 over a
temperature of about -30.degree. C. to 20.degree. C.
[0067] The cover layer, or outer cover layer, can include any
materials known to those of ordinary skill in the art, including
thermoplastic and thermosetting materials, but preferably the cover
layer can include any suitable materials, such as:
[0068] (1) Polyurethanes, such as those prepared from polyols and
diisocyanates or polyisocyanates and those disclosed in U.S. Pat.
No. 5,334,673; and
[0069] (2) Polyureas, such as those disclosed in U.S. Pat. No.
5,484,870.
[0070] The cover preferably includes a polyurethane composition
comprising the reaction product of at least one polyisocyanate and
at least one curing agent. The curing agent can include, for
example, one or more diamines, one or more polyols, or a
combination thereof. The at least one polyisocyanate can be
combined with one or more polyols to form a prepolymer, which is
then combined with the at least one curing agent. Thus, when
polyols are described herein they may be suitable for use in one or
both components of the polyurethane material, i.e., as part of a
prepolymer and in the curing agent. The polyurethane composition
may be used in forming the inner cover, outer cover, or both. In
one preferred embodiment, the outer cover includes the polyurethane
composition.
[0071] In a different preferred embodiment, the curing agent
includes a polyol curing agent. In a more preferred embodiment, the
polyol curing agent includes ethylene glycol; diethylene glycol;
polyethylene glycol; propylene glycol; polypropylene glycol; lower
molecular weight polytetramethylene ether glycol;
1,3-bis(2-hydroxyethoxy)benzene;
1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene;
1,3-bis-{2-[2-(2-hydroxyethox- y)ethoxy]ethoxy}benzene;
1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol;
resorcinol-di-(.beta.-hydroxyethyl)ether;
hydroquinone-di-(.beta.-hydroxy- ethyl)ether; trimethylol propane,
or mixtures thereof.
[0072] In one embodiment, the polyurethane composition includes at
least one isocyanate and at least one curing agent. In yet another
embodiment, the polyurethane composition includes at least one
isocyanate, at least one polyol, and at least one curing agent. In
a preferred embodiment, the isocyanate includes
4,4'-diphenylmethane diisocyanate, polymeric 4,4'-diphenylmethane
diisocyanate, carbodiimide-modified liquid 4,4'-diphenylmethane
diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, p-phenylene
diisocyanate, toluene diisocyanate, isophoronediisocyanate,
p-methylxylene diisocyanate, m-methylxylene diisocyanate,
o-methylxylene diisocyanate, or a mixture thereof. In another
preferred embodiment, the at least one polyol includes a polyether
polyol, hydroxy-terminated polybutadiene, polyester polyol,
polycaprolactone polyol, polycarbonate polyol, or mixtures thereof.
In yet another preferred embodiment, the curing agent includes a
polyamine curing agent, a polyol curing agent, or a mixture
thereof. In a more preferred embodiment, the curing agent includes
a polyamine curing agent. In a most preferred embodiment, the
polyamine curing agent includes
3,5-dimethylthio-2,4-toluenediamine, or an isomer thereof;
3,5-diethyltoluene-2,4-diamine, or an isomer thereof;
4,4'-bis-(sec-butylamino)-diphenylmethane;
1,4-bis-(sec-butylamino)-benze- ne;
4,4'-methylene-bis-(2-chloroaniline);
4,4'-methylene-bis-(3-chloro-2,6- -diethylaniline); trimethylene
glycol-di-p-aminobenzoate;
polytetramethyleneoxide-di-p-aminobenzoate; N,N'-dialkyldiamino
diphenyl methane; p,p'-methylene dianiline; phenylenediamine;
4,4'-methylene-bis-(2-chloroaniline);
4,4'-methylene-bis-(2,6-diethylanil- ine);
4,4'-diamino-3,3'-diethyl-5,5'-dimethyl diphenylmethane;
2,2',3,3'-tetrachloro diamino diphenylmethane;
4,4'-methylene-bis-(3-chlo- ro-2,6-diethylaniline); or mixtures
thereof.
[0073] Any polyisocyanate available to one of ordinary skill in the
art is suitable for use according to the invention. Exemplary
polyisocyanates include, but are not limited to,
4,4'-diphenylmethane diisocyanate ("MDI"), polymeric MDI,
carbodiimide-modified liquid MDI, 4,4'-dicyclohexylmethane
diisocyanate ("H.sub.12MDI"), p-phenylene diisocyanate ("PPDI"),
toluene diisocyanate ("TDI"), 3,3'-dimethyl-4,4'-biphenylene
diisocyanate ("TODI"), isophoronediisocyanate ("IPDI"),
hexamethylene diisocyanate ("HDI"), naphthalene diisocyanate
("NDI"); xylene diisocyanate ("XDI"); p-tetramethylxylene
diisocyanate ("p-TMXDI"); m-tetramethylxylene diisocyanate
("m-TMXDI"); ethylene diisocyanate; propylene-1,2-diisocyana- te;
tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate;
1,6-hexamethylene-diisocyanate ("HDI"); dodecane-1,12-diisocyanate;
cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate;
cyclohexane-1,4-diisocyanate;
1-isocyanato-3,3,5-trimethyl-5-isocyanatome- thylcyclohexane;
methyl cyclohexylene diisocyanate; triisocyanate of HDI;
triisocyanate of 2,4,4-trimethyl-1,6-hexane diisocyanate ("TMDI");
tetracene diisocyanate; naphthalene diisocyanate; anthracene
diisocyanate; and mixtures thereof. Polyisocyanates are known to
those of ordinary skill in the art as having more than one
isocyanate group, e.g., di-, tri-, and tetra-isocyanate.
Preferably, the polyisocyanate includes MDI, PPDI, TDI, or a
mixture thereof, and more preferably, the polyisocyanate includes
MDI. It should be understood that, as used herein, the term "MDI"
includes 4,4'-diphenylmethane diisocyanate, polymeric MDI,
carbodiimide-modified liquid MDI, and mixtures thereof and,
additionally, that the diisocyanate employed may be "low free
monomer," understood by one of ordinary skill in the art to have
lower levels of "free" monomer isocyanate groups than conventional
diisocyanates, i.e., the compositions of the invention typically
have less than about 0.1% free monomer groups. Examples of "low
free monomer" diisocyanates include, but are not limited to Low
Free Monomer MDI, Low Free Monomer TDI, and Low Free Monomer
PPDI.
[0074] The at least one polyisocyanate should have less than about
14% unreacted NCO groups. Preferably, the at least one
polyisocyanate has no greater than about 7.5% NCO, more preferably,
from about 2.5% to about 7.5%, and most preferably, from about 4%
to about 6.5%.
[0075] Any polyol available to one of ordinary skill in the art is
suitable for use according to the invention. In one embodiment, the
molecular weight of the polyol is from about 200 to about 6000.
Exemplary polyols include, but are not limited to, polyether
polyols, hydroxy-terminated polybutadiene (including
partially/fully hydrogenated derivatives), polyester polyols,
polycaprolactone polyols, and polycarbonate polyols. Examples
include, but are not limited to, polytetramethylene ether glycol
("PTMEG"), polyethylene propylene glycol, polyoxypropylene glycol,
and mixtures thereof. The hydrocarbon chain can have saturated or
unsaturated bonds and substituted or unsubstituted aromatic and
cyclic groups. Preferably, the polyol of the present invention
includes PTMEG.
[0076] In another embodiment, polyester polyols are included in the
polyurethane material of the invention. Suitable polyester polyols
include, but are not limited to, polyethylene adipate glycol,
polybutylene adipate glycol, polyethylene propylene adipate glycol,
ortho-phthalate-1,6-hexanediol, and mixtures thereof. The
hydrocarbon chain can have saturated or unsaturated bonds, or
substituted or unsubstituted aromatic and cyclic groups.
[0077] In another embodiment, polycaprolactone polyols are included
in the materials of the invention. Suitable polycaprolactone
polyols include, but are not limited to, 1,6-hexanediol-initiated
polycaprolactone, diethylene glycol initiated polycaprolactone,
trimethylol propane initiated polycaprolactone, neopentyl glycol
initiated polycaprolactone, 1,4-butanediol-initiated
polycaprolactone, and mixtures thereof. The hydrocarbon chain can
have saturated or unsaturated bonds, or substituted or
unsubstituted aromatic and cyclic groups.
[0078] In yet another embodiment, the polycarbonate polyols are
included in the polyurethane material of the invention. Suitable
polycarbonates include, but are not limited to, polyphthalate
carbonate. The hydrocarbon chain can have saturated or unsaturated
bonds, or substituted or unsubstituted aromatic and cyclic
groups.
[0079] Polyamine curatives are also suitable for use in the curing
agent of the polyurethane composition of the invention and have
been found to improve cut, shear, and impact resistance of the
resultant balls. Preferred polyamine curatives include, but are not
limited to, 3,5-dimethylthio-2,4-toluenediamine and isomers
thereof, 3,5-diethyltoluene-2,4-diamine and isomers thereof, such
as 3,5-diethyltoluene-2,6-diamine;
4,4'-bis-(sec-butylamino)-diphenylmethane- ;
1,4-bis-(sec-butylamino)-benzene,
4,4'-methylene-bis-(2-chloroaniline);
4,4'-methylene-bis-(3-chloro-2,6-diethylaniline);
polytetramethyleneoxide- -di-p-aminobenzoate; N,N'-dialkyldiamino
diphenyl methane; p,p'-methylene dianiline ("MDA");
m-phenylenediamine ("MPDA"); 4,4'-methylene-bis-(2-chl- oroaniline)
("MOCA"); 4,4'-methylene-bis-(2,6-diethylaniline);
4,4'-diamino-3,3'-diethyl-5,5'-dimethyl diphenylmethane;
2,2',3,3'-tetrachloro diamino diphenylmethane;
4,4'-methylene-bis-(3-chlo- ro-2,6-diethylaniline); trimethylene
glycol di-p-aminobenzoate; and mixtures thereof. Preferably, the
curing agent of the present invention includes
3,5-dimethylthio-2,4-toluenediamine and isomers thereof, such as
ETHACURE.RTM.300. Suitable polyamine curatives, which include both
primary and secondary amines, preferably have weight average
molecular weights ranging from about 64 to about 2000.
[0080] At least one of a diol, triol, tetraol, or
hydroxy-terminated curative may be added to the aforementioned
polyurethane composition. Suitable diol, triol, and tetraol groups
include ethylene glycol; diethylene glycol; polyethylene glycol;
propylene glycol; polypropylene glycol; lower molecular weight
polytetramethylene ether glycol; 1,3-bis(2-hydroxyethoxy)benzene;
1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benze- ne;
1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene;
1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol;
resorcinol-di-(4-hydroxyethyl)ether;
hydroquinone-di-(4-hydroxyethyl)ether; and mixtures thereof.
Preferred hydroxy-terminated curatives include ethylene glycol;
diethylene glycol; 1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol,
trimethylol propane, and mixtures thereof.
[0081] Preferably, the hydroxy-terminated curatives have molecular
weights ranging from about 48 to 2000. It should be understood that
molecular weight, as used herein, is the absolute weight average
molecular weight and would be understood as such by one of ordinary
skill in the art.
[0082] Both the hydroxy-terminated and amine curatives can include
one or more saturated, unsaturated, aromatic, and cyclic groups.
Additionally, the hydroxy-terminated and amine curatives can
include one or more halogen groups. The polyurethane composition
can be formed with a blend or mixture of curing agents. If desired,
however, the polyurethane composition may be formed with a single
curing agent.
[0083] Any method known to one of ordinary skill in the art may be
used to combine the polyisocyanate, polyol, and curing agent of the
present invention. One commonly employed method, known in the art
as a one-shot method, involves concurrent mixing of the
polyisocyanate, polyol, and curing agent. This method results in a
mixture that is inhomogenous (more random) and affords the
manufacturer less control over the molecular structure of the
resultant composition. A preferred method of mixing is known as a
prepolymer method. In this method, the polyisocyanate and the
polyol are mixed separately prior to addition of the curing agent.
This method affords a more homogeneous mixture resulting in a more
consistent polymer composition.
[0084] An optional filler component may be chosen to impart
additional density to blends of the previously described
components. The selection of the filler component is dependent upon
the characteristics of the golf ball desired. Examples of fillers
for use in the filler component of the polyurethane include those
described herein for the polybutadiene reaction component. Similar
or identical additives, such as nanoparticles, fibers, glass
spheres, and/or various metals, such as titanium and tungsten, can
be added to the polyurethane compositions of the present invention,
as well, in amounts as needed to modify one or more golf ball
properties. Additional components that can be added to the
polyurethane composition include UV stabilizers and other dyes, as
well as optical brighteners and fluorescent pigments and dyes. Such
additional ingredients may be added in any amounts that will
achieve their desired purpose.
[0085] Due to the very thin nature, it has been found by the
present invention that the use of a castable, reactive material,
which is applied in a fluid form, makes it possible to obtain very
thin outer cover layers on golf balls. Specifically, it has been
found that castable, reactive liquids, which react to form a
urethane elastomer material, provide desirable very thin outer
cover layers.
[0086] The castable, reactive liquid employed to form the urethane
elastomer material can be applied over the inner core using a
variety of application techniques such as spraying, dipping, spin
coating, or flow coating methods which are well known in the art.
An example of a suitable coating technique is that which is
disclosed in U.S. Pat. No. 5,733,428, the disclosure of which is
hereby incorporated herein in its entirety by express reference
thereto.
[0087] The cover, or the outer cover if both inner and outer cover
layers are present, is preferably formed around the core by mixing
and introducing the material in the mold halves. It is important
that the viscosity be measured over time, so that the subsequent
steps of filling each mold half, introducing the core into one half
and closing the mold can be properly timed for accomplishing
centering of the core cover halves fusion and achieving overall
uniformity. A suitable viscosity range of the curing urethane mix
for introducing cores into the mold halves is determined to be
approximately from about 2,000 cP to about 30,000 cP, with the
preferred range of about 8,000 cP to about 15,000 cP.
[0088] To start the cover formation, mixing of the prepolymer and
curative can be accomplished in motorized mixer including mixing
head by feeding through lines metered amounts of curative and
prepolymer. Top preheated mold halves are filled and placed in
fixture units using pins moving into holes in each mold. After the
reacting materials have resided in top mold halves for about 10 to
about 80 seconds, a core is lowered at a controlled speed into the
gelling reacting mixture. At a later time, a bottom mold half or a
series of bottom mold halves have similar mixture amounts
introduced into the cavity.
[0089] A ball cup can hold the ball core through reduced pressure
(or partial vacuum) in hose. Upon location of the coated core in
the halves of the mold after gelling for about 10 to about 80
seconds, the vacuum is released allowing core to be released. The
mold halves, with core and solidified cover half thereon, are
removed from the centering fixture unit, inverted and mated with
other mold halves which, at an appropriate time earlier, have had a
selected quantity of reacting polyurethane prepolymer and curing
agent introduced therein to commence gelling.
[0090] Similarly, U.S. Pat. No. 5,006,297 and U.S. Pat. No.
5,334,673 both also disclose suitable molding techniques which may
be utilized to apply the castable reactive liquids employed in the
present invention. The disclosures of each patent is hereby
expressly incorporated herein by express reference thereto. The
method of the invention, however, is not limited to the use of
these techniques.
[0091] In one embodiment, the cover typically has a loss tangent of
0.16 to 0.075 from -30.degree. C. to 20.degree. C. In one
embodiment, the complex modulus of the cover layer on the ball is
from about 1000 to 2800 kgf/cm from -30.degree. C. to 20.degree. C.
In one embodiment, the specific gravity of the cover material is
from about 1 to 2, preferably from about 1.1 to 1.4. In one
preferred embodiment, the cover material has a specific gravity of
about 1.15 to 1.25.
[0092] When golf balls are prepared according to the invention,
they typically will have dimple coverage greater than about 60
percent, preferably greater than about 65 percent, and more
preferably greater than about 75 percent. The flexural modulus of
the cover on the golf balls is typically greater than about 500
psi, and is preferably from about 500 psi to 80,000 psi.
[0093] As discussed herein, the outer cover layer is preferably
formed from a relatively soft polyurethane material. In particular,
the material of the outer cover layer should have a material
hardness, as measured by ASTM D2240-00, from about 20 to about 60
Shore D, preferably from about 30 to about 50 Shore D. In one
embodiment, the material hardness of the outer cover material is
about 45 Shore D. When the hardness of the outer cover material is
measured directly on the golf ball, the values tend to be higher
than then the material hardness. In one embodiment, the outer cover
hardness, as measured on the golf ball, is from about 45 to about
60 Shore D. The inner cover layer, preferably has a material
hardness of about 50 to about 70 Shore D, more preferably from
about 60 to about 65 Shore D. In an alternative embodiment, the
inner cover layer has a hardness, when measured on the golf ball,
of about 45 to about 64 Shore D.
[0094] The resultant golf balls typically have a coefficient of
restitution of greater than about 0.7, preferably greater than
about 0.75, and more preferably greater than about 0.78. The golf
balls also typically have an Atti compression of at least about 40,
preferably from about 50 to 120, and more preferably from about 60
to 100.
[0095] The core material of the present invention may also used in
golf equipment and, in particular, polymeric inserts for golf clubs
such as putters, drivers, and irons, and golf shoe components, such
as soles and uppers.
[0096] 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.
[0097] While it is apparent that the illustrative embodiments of
the invention herein disclosed fulfills the objectives stated
above, it will be appreciated that numerous modifications and other
embodiments may be devised by those of ordinary skill in the art.
For example, the present invention could use more than one thread
where the threads are chemically, physically or mechanically
distinct from each other. Therefore, it will be understood that the
appended claims are intended to cover all such modifications and
embodiments which come within the spirit and scope of the present
invention.
* * * * *