U.S. patent application number 16/686598 was filed with the patent office on 2020-03-19 for a golf ball comprising a very-low melt flow inner cover layer composition.
The applicant listed for this patent is Acushnet Company. Invention is credited to Mark L. Binette, Robert Blink, David A. Bulpett, Brian Comeau, Michael J. Sullivan.
Application Number | 20200086174 16/686598 |
Document ID | / |
Family ID | 47556153 |
Filed Date | 2020-03-19 |
United States Patent
Application |
20200086174 |
Kind Code |
A1 |
Bulpett; David A. ; et
al. |
March 19, 2020 |
A GOLF BALL COMPRISING A VERY-LOW MELT FLOW INNER COVER LAYER
COMPOSITION
Abstract
A golf ball including a core; an inner cover layer formed from a
first thermoplastic composition and having a thickness of about
0.005 inches to 0.40 inches and a surface hardness of about 60
Shore D or greater; and an outer cover layer formed from a
thermoplastic polyurethane material and having a thickness of about
0.01 inches to 0.075 inches and a surface hardness of about 60
Shore D or less. The thermoplastic composition has a first melt
flow index at 280.degree. C. under a 10-kg load of less than about
35 g/10 min and a second melt flow index at 265.degree. C. under a
5-kg load of less than about 10 g/10 min.
Inventors: |
Bulpett; David A.; (Boston,
MA) ; Blink; Robert; (Newport, RI) ; Binette;
Mark L.; (Mattapoisett, MA) ; Comeau; Brian;
(Berkley, MA) ; Sullivan; Michael J.; (Old Lyme,
CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Acushnet Company |
Fairhaven |
MA |
US |
|
|
Family ID: |
47556153 |
Appl. No.: |
16/686598 |
Filed: |
November 18, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15936500 |
Mar 27, 2018 |
10478674 |
|
|
16686598 |
|
|
|
|
14799849 |
Jul 15, 2015 |
9925417 |
|
|
15936500 |
|
|
|
|
13633180 |
Oct 2, 2012 |
9084916 |
|
|
14799849 |
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|
12469381 |
May 20, 2009 |
8337331 |
|
|
13633180 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A63B 37/0043 20130101;
A63B 37/0076 20130101; A63B 37/0063 20130101; A63B 37/0051
20130101; A63B 37/0045 20130101; A63B 37/0003 20130101; A63B
37/0087 20130101; A63B 37/0064 20130101; A63B 37/0044 20130101;
A63B 37/0048 20130101; A63B 37/0062 20130101; A63B 2037/0079
20130101; A63B 37/12 20130101; A63B 37/0033 20130101; A63B 37/0031
20130101; A63B 37/0075 20130101; A63B 37/0092 20130101 |
International
Class: |
A63B 37/00 20060101
A63B037/00; A63B 37/12 20060101 A63B037/12 |
Claims
1. A golf ball comprising: a core; an inner cover layer comprising
a first thermoplastic composition and having a thickness of about
0.005 inches to about 0.40 inches and a surface hardness of about
60 Shore D or greater; and an outer cover layer comprising a
thermoplastic polyurethane and having a thickness of about 0.01
inches to about 0.075 inches and a surface hardness of about 60
Shore D or less; wherein the first thermoplastic composition
comprises a first melt flow index at 280.degree. C. under a 10-kg
load of less than about 35 g/10 min and a second melt flow index at
265.degree. C. under a 5-kg load of less than about 10 g/10
min.
2. The golf ball of claim 1, wherein the first melt flow index is
about 20 g/10 min or less.
3. The golf ball of claim 2, wherein the first melt flow index is
about 10 g/10 min or less.
4. The golf ball of claim 3, wherein the second melt flow index is
about 5 g/10 min or less.
5. The golf ball of claim 1, wherein the first thermoplastic
composition has a third melt flow index at 190.degree. C. under a
2.16-kg load of less than about 2 g/10 min.
6. The golf ball of claim 5, wherein the third melt flow index is
less than about 1 g/10 min.
7. The golf ball of claim 1, wherein the first thermoplastic
composition comprises an ionomer.
8. The golf ball of claim 7, wherein the first thermoplastic
composition comprises a higher-melting-temperature thermoplastic
resin.
9. The golf ball of claim 7, wherein the first thermoplastic
composition comprises a reactive polymer.
10. The golf ball of claim 7, wherein the ionomer is neutralized by
a metal cation to 80 wt % or greater.
11. The golf ball of claim 10, wherein the ionomer is neutralized
by a metal cation to 90 wt % or greater.
12. The golf ball of claim 1, wherein the first thermoplastic
composition comprises an amine or a peroxide compound.
13. The golf ball of claim 1, wherein the core comprises an inner
core and an outer core layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/936,500, filed Mar. 27, 2018, which is a
continuation of U.S. patent application Ser. No. 14/799,849, filed
Jul. 15, 2015, now U.S. Pat. No. 9,925,417, which is a continuation
of U.S. patent application Ser. No. 13/633,180, filed Oct. 2, 2012,
now U.S. Pat. No. 9,084,916, which is a continuation-in-part of
U.S. patent application Ser. No. 12/469,381, filed May 20, 2009,
now U.S. Pat. No. 8,337,331, the entire disclosures of which are
hereby incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to golf balls, and
more particularly to golf balls having multi-layer covers
comprising a thermoplastic inner cover layer, and a thermoset outer
core layer.
BACKGROUND OF THE INVENTION
[0003] Golf balls having multi-cover layers are known as is the use
of ionomers and highly neutralized polymers as cover layers.
Several patents and published applications in the prior art teach
that it is essential for cover materials to have good flow
properties, in particular they should have a high melt flow rate as
demonstrated by having a high Melt Flow Index (MFI). For example,
U.S. Pat. No. 7,572,195 to Egashira et al., U.S. Pub. Appl. No.
2010/0167841 to Okabe et al., and U.S. Patent Application Serial
No. 2010/0190580 to Higuchi et al. all teach compositions for use
as golf ball inner cover layers that have MFI's of greater than 2.
Other references such as U.S. Patent Application Serial Nos.
2010/0069173 to Okabe et al. and 2010/0075777 to Shigemitsu et al.
teach compositions for use as golf ball inner cover layers that are
blends of low MFI materials and high MFI materials. Other
references teach a broad range of MFI, such as U.S. Patent
Application Serial No. 2011/0092312 to Shigemitsu, but only
measured at a relatively low temperature, 190.degree. C., and are
silent as to the need for the material to be low melt flow at the
higher temperatures at which inner cover leakage may occur.
[0004] Generally, golf ball cover layers are formed from
thermoplastic and/or thermoset compositions. The present invention,
however, provides a novel multi-cover layer golf ball construction
wherein an inner cover comprises a very low melt flow
thermoplastic, and an outer cover layer comprises a thermoset or
thermoplastic composition. A problem with molding a thermosetting
composition requiring an elevated temperature and/or pressure to
cure, over a higher melt flow thermoplastic composition such as an
ionomer, is that the ionomer tends to flow out or "leak" out
through the thermosetting layer during overmolding--in general,
there exist tremendous difficulties in molding high-temperature
thermoset materials over any soft layer. The invention herein seeks
to reduce or eliminate "leakage" by either 1) reducing the melt
flow of the ionomeric material or 2) otherwise increasing the heat
resistance of the ionomer by modifying either the ionomeric resin
itself prior to molding or via a post-mold treatment to the
ionomeric golf ball layer.
[0005] Ionomeric materials have long been used as layers of golf
balls, very commonly as inner or outer cover layers. Ionomers have
excellent toughness, crack resistance, resilience, and a wide range
of hardness values and moduli, which make them ideally suited for
these types of layers. Methods have been developed to compression
or injection mold ionomers into golf ball layers-such methods
involve heating the materials to soften and melt them thereby
promoting flow to form the desired layers. Ionomers have relatively
low vicat softening points (47-71.degree. C.) and low melting
temperatures (70-96.degree. C.) which makes them readily moldable
but also gives them inherently low resistance to heat and very poor
high-temperature properties. As such, the inventive thermoplastic
inner cover layers attempt to make use of materials having very low
flow at elevated temperatures and/or high resistance to heat.
[0006] Most ionomers suitable for conventional golf ball layers
have a percent neutralization of from 19 wt % to 69 wt %. Higher
levels of neutralization have previously been unsuitable for use by
manufacturers or disclosed in the prior art as being useful,
without addition of high levels of metal cation-fatty acid flow
modifiers, due to the difficulty of molding more highly-neutralized
ionomers (>70 wt % neutralization). Whereas the conventional
low-neutralization (19-69 wt %) ionomers may be easily injection
molded at temperatures of about 300.degree. F. (149.degree. C.) to
450.degree. (232.degree. C.), the highly-neutralized and/or treated
ionomers of the invention must be molded at elevated temperatures
of from about 500.degree. F. (260.degree. C.) to 680.degree. F.
(360.degree. C.) and, more preferably, about 550.degree. F.
(288.degree. C.) to 650.degree. F. (343.degree. C.), temperatures
previously thought undesirable. When compression molding
conventional ionomers (using a two-step process in which half
shells are first injection molded, then placed around a core and
compression molded into a ball) temperatures as low as 250.degree.
F. (121.degree. C.) and typically from about 250.degree. F.
(121.degree. C.) to 350.degree. F.). (177.degree. are used. The
inventive ionomers must be processed at temps well above
350.degree. F. (177.degree. C.).
[0007] The inventive constructions herein (i.e., thermoset or
thermoplastic outer cover layers molded over a thermoplastic
ionomeric layer) additionally involve the molding of a material
requiring curing or processing at a temperature well above the
softening and melting temperature of conventional ionomers. This
presents a problem that the invention herein seeks to solve, that
is, provide ionomeric compositions that will not significantly
soften and flow at the conditions that occur when overmolding with
a material that requires elevated temperatures to form said
overmolded layer.
[0008] Commercially ionomers are available in a wide range of melt
flows, the melt flow being determined by the degree of
neutralization of the acid moiety of the acid copolymer with
various metal cations, optimized for physical properties such as
toughness and elongation while maintaining melt-processability.
Neutralization to 90% and higher is known but is not considered a
commercially-viable and usable product because of the loss of
melt-processability (producing a low melt flow or intractable
material), particularly for copolymers with high acid levels. For
example, U.S. Pat. No. 6,777,472 generally describes a process for
modification of highly-neutralized ionomers by the addition of a
sufficient amount of specific organic fatty acids (or metal salts
thereof) in order to maintain melt-processability--unmodified,
highly-neutralized ionomers are typically considered unworkable
materials because of their low-melt-flow properties.
[0009] Various methods of covalent crosslinking the outermost cover
of golf balls are known. For example, U.S. Pat. No. 5,891,973
generally discloses an ionomer-covered golf ball that is irradiated
via electron beam exposure to increase the resistance to scuff and
cut resistance when impacted with a golf club. Covalent
crosslinking of non-ionomeric golf ball cover materials with the
addition of peroxide is generally disclosed in U.S. Pat. No.
6,303,704 which is also aimed at improving the scuff and cut
resistance of softer covers. Ionomer outermost covers, particularly
low modulus ionomers are susceptible to softening when exposed to
elevated temperatures, thereby losing dimple definition and
negatively impacting aerodynamic properties of the ball. One method
to overcome this drawback is the irradiation via electron beam or
exposure of the dimpled golf ball to gamma radiation, which is
generally disclosed in U.S. Pat. No. 6,350,793. None of these
references, however, disclose using novel low-melt-flow (or
altered, temperature resistant) thermoplastics as a core layer
sandwiched between two, thermosetting rubber core layers.
[0010] There remains a need, therefore, for low melt flow and/or
high temperature resistant thermoplastic ionomeric materials for
use in the novel multi-layer golf ball covers herein. The use of
these compositions significantly reduces or eliminates the
"leakage" of the ionomeric layer into or through the outer core
layer, thereby giving a ball having improved consistency of
properties as well as improved durability and much reduced
susceptibility to breakage when struck with a club head.
SUMMARY OF THE INVENTION
[0011] The present invention is directed to a golf ball having a
core, an inner cover layer, and an outer cover layer. The inner
cover layer is formed from a thermoplastic composition and has a
thickness of about 0.005 to 0.40 inches and a surface hardness of
about 60 Shore D or greater. The outer cover layer is formed from a
thermoset material and has a thickness of about 0.01 to 0.05 inches
and a surface hardness of about 60 Shore D or less. The
thermoplastic composition has a first melt flow index at
280.degree. C. under a 10-kg load of less than about 35 g/10 min
and a second melt flow index at 265.degree. C. under a 5-kg load of
less than about 10 g/10 min.
[0012] The first melt flow index is about 20 g/10 min or less,
preferably about 10 g/10 min or less. The second melt flow index is
about 5 g/10 min or less. In another embodiment, the thermoplastic
composition has a third melt flow index at 190.degree. C. under a
2.16-kg load of less than about 2 g/10 min, more preferably less
than about 1 g/10 min. The thermoplastic composition may include an
ionomer. The ionomer is typically neutralized by a metal cation to
70 wt. % or greater, more preferably 80 wt. % or greater, most
preferably 90 wt. % or greater. The thermoplastic composition may
include an amine or a peroxide compound, be treated with radiation,
or include an ionomer and a higher-melting-temperature
thermoplastic resin. The thermoplastic composition may
alternatively include an ionomer and a reactive polymer. The core
may also be a `dual core`, including an inner core and an outer
core layer.
[0013] The present invention is also directed to a golf ball formed
from a core, an inner cover, and an outer cover. The inner cover
layer may be formed from a first thermoplastic composition and has
a thickness of about 0.005 to 0.10 inches and a surface hardness of
about 60 Shore D or greater. The outer cover layer is formed from a
second thermoplastic composition, in a particular embodiment,
thermoplastic polyurethane, and has a thickness of about 0.01 to
0.05 inches and a surface hardness of about 60 Shore D or less. The
first thermoplastic composition preferably has a first melt flow
index at 280.degree. C. under a 10-kg load of less than about 35
g/10 min and a second melt flow index at 265.degree. C. under a
5-kg load of less than about 10 g/10 min. In a preferred
embodiment, the first and second melt flow indices are less than
the melt flow index of the second thermoplastic composition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] These and other aspects of the present invention may be more
fully understood with reference to, but not limited by, the
following drawings:
[0015] FIG. 1 is a representative cross-section of a golf ball of
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0016] A golf ball having a core and a multi-layer cover enclosing
the core is disclosed. The core generally comprises a thermosetting
rubber single or multiple layer core, and may further comprise a
thermoplastic inner, intermediate, or outer core layer. The inner,
intermediate, and/or outer core layers may be formed of more than
one layer. The multi-layer core has an overall outer diameter
within a range having a lower limit of 1.000 or 1.300 or 1.400 or
1.500 or 1.600 or 1.610 inches and an upper limit of 1.620 or 1.630
or 1.640 inches. In a particular embodiment, the single or
multi-layer core has an overall outer diameter of 1.500 inches or
1.510 inches or 1.530 inches or 1.550 inches or 1.570 inches or
1.580 inches or 1.590 inches or 1.600 inches or 1.610 inches or
1.620 inches.
[0017] In one preferred embodiment, the core consists of a single
layer formed from a thermoset rubber composition. In another
embodiment, the center and/or outer core layer consists of two
layers, each of which is formed from the same or different
thermoset rubber compositions.
[0018] Suitable rubber compositions for forming the core layer
comprise a base rubber, an initiator agent, a co-agent, and
optionally one or more of a zinc oxide, zinc stearate or stearic
acid, antioxidant, and a soft-and-fast agent. Suitable base rubbers
include natural and synthetic rubbers including, but not limited
to, polybutadiene, polyisoprene, ethylene propylene rubber ("EPR"),
styrene-butadiene rubber, styrenic block copolymer rubbers (such as
"SI", "SIS", "SB", "SBS", "SIBS", and the like, where "S" is
styrene, "I" is isobutylene, and "B" is butadiene), butyl rubber,
halobutyl rubber, polystyrene elastomers, polyethylene elastomers,
polyurethane elastomers, polyurea elastomers, metallocene-catalyzed
elastomers and plastomers, copolymers of isobutylene and
p-alkylstyrene, halogenated copolymers of isobutylene and
p-alkylstyrene, copolymers of butadiene with acrylonitrile,
polychloroprene, alkyl acrylate rubber, chlorinated isoprene
rubber, acrylonitrile chlorinated isoprene rubber, and combinations
of two or more thereof. Diene rubbers are preferred, particularly
polybutadiene, styrene-butadiene, and mixtures of polybutadiene
with other elastomers wherein the amount of polybutadiene present
is at least 40 wt % based on the total polymeric weight of the
mixture. Particularly preferred polybutadienes include high-cis
neodymium-catalyzed polybutadienes and cobalt-, nickel-, or
lithium-catalyzed polybutadienes. Suitable examples of
commercially-available polybutadienes include, but are not limited
to, BUNA CB high-cis neodymium-catalyzed polybutadiene rubbers,
such as BUNA CB 23, and TAKTENE high-cis cobalt-catalyzed
polybutadiene rubbers, such as TAKTENE 220 and 221 from Lanxess
Corp.; SE BR-1220 from Dow Chemical Company; EUROPRENE NEOCIS BR 40
and BR 60 from Polimeri Europa; UBEPOL-BR rubbers from UBE
Industries, Inc.; BR 01 from Japan Synthetic Rubber Co., Ltd.; and
NEODENE high-cis neodymium-catalyzed polybutadiene rubbers, such as
NEODENE BR 40 from Karbochem.
[0019] Suitable initiator agents include organic peroxides, high
energy radiation sources capable of generating free radicals, and
combinations thereof. High energy radiation sources capable of
generating free radicals include, but are not limited to, electron
beams, ultra-violet radiation, gamma radiation, X-ray radiation,
infrared radiation, heat, and combinations thereof.
[0020] Suitable organic peroxides include, but are not limited to,
dicumyl peroxide; n-butyl-4,4-di(t-butylperoxy) valerate;
1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane;
2,5-dimethyl-2,5-di(t-butylperoxy) hexane; di-t-butyl peroxide;
di-t-amyl peroxide; t-butyl peroxide; t-butyl cumyl peroxide;
2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3;
di(2-t-butyl-peroxyisopropyl)benzene; dilauroyl peroxide; dibenzoyl
peroxide; t-butyl hydroperoxide; lauryl peroxide; benzoyl peroxide;
and combinations thereof. Examples of suitable
commercially-available peroxides include, but are not limited to
PERKADOX BC dicumyl peroxide from Akzo Nobel, and VAROX peroxides,
such as VAROX ANS benzoyl peroxide and VAROX 231
1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane from RT Vanderbilt
Company, Inc. Peroxide initiator agents are generally present in
the rubber composition in an amount of at least 0.05 parts by
weight per 100 parts of the base rubber, or an amount within the
range having a lower limit of 0.05 parts or 0.1 parts or 0.8 parts
or 1 part or 1.25 parts or 1.5 parts by weight per 100 parts of the
base rubber, and an upper limit of 2.5 parts or 3 parts or 5 parts
or 6 parts or 10 parts or 15 parts by weight per 100 parts of the
base rubber.
[0021] Co-agents are commonly used with peroxides to increase the
state of cure. Suitable coagents include, but are not limited to,
metal salts of unsaturated carboxylic acids; unsaturated vinyl
compounds and polyfunctional monomers (e.g., trimethylolpropane
trimethacrylate); phenylene bismaleimide; and combinations thereof.
Particular examples of suitable metal salts include, but are not
limited to, one or more metal salts of acrylates, diacrylates,
methacrylates, and dimethacrylates, wherein the metal is selected
from magnesium, calcium, zinc, aluminum, lithium, nickel, and
sodium. In a particular embodiment, the co-agent is selected from
zinc salts of acrylates, diacrylates, methacrylates,
dimethacrylates, and mixtures thereof. In another particular
embodiment, the coagent is zinc diacrylate. When the co-agent is
zinc diacrylate and/or zinc dimethacrylate, the co-agent is
typically included in the rubber composition in an amount within
the range having a lower limit of 1 or 5 or 10 or 15 or 19 or 20
parts by weight per 100 parts of the base rubber, and an upper
limit of 24 or 25 or 30 or 35 or 40 or 45 or 50 or 60 parts by
weight per 100 parts of the base rubber. When one or more less
active co-agents are used, such as zinc monomethacrylate and
various liquid acrylates and methacrylates, the amount of less
active coagent used may be the same as or higher than for zinc
diacrylate and zinc dimethacrylate co-agents. The desired
compression may be obtained by adjusting the amount of
crosslinking, which can be achieved, for example, by altering the
type and amount of co-agent.
[0022] The rubber composition optionally includes a curing agent.
Suitable curing agents include, but are not limited to, sulfur;
N-oxydiethylene 2-benzothiazole sulfenamide;
N,N-di-ortho-tolylguanidine; bismuth dimethyldithiocarbamate;
N-cyclohexyl 2-benzothiazole sulfenamide; N,N-diphenylguanidine;
4-morpholinyl-2-benzothiazole disulfide; dipentamethylenethiuram
hexasulfide; thiuram disulfides; mercaptobenzothiazoles;
sulfenamides; dithiocarbamates; thiuram sulfides; guanidines;
thioureas; xanthates; dithiophosphates; aldehyde-amines;
dibenzothiazyl disulfide; tetraethylthiuram disulfide;
tetrabutylthiuram disulfide; and combinations thereof.
[0023] The rubber composition optionally contains one or more
antioxidants. Antioxidants are compounds that can inhibit or
prevent the oxidative degradation of the rubber. Some antioxidants
also act as free radical scavengers; thus, when antioxidants are
included in the rubber composition, the amount of initiator agent
used may be as high or higher than the amounts disclosed herein.
Suitable antioxidants include, for example, dihydroquinoline
antioxidants, amine type antioxidants, and phenolic type
antioxidants.
[0024] The rubber composition may contain one or more fillers to
adjust the density and/or specific gravity of the core. Exemplary
fillers include precipitated hydrated silica, clay, talc, asbestos,
glass fibers, aramid fibers, mica, calcium metasilicate, zinc
sulfate, barium sulfate, zinc sulfide, lithopone, silicates,
silicon carbide, diatomaceous earth, polyvinyl chloride, carbonates
(e.g., calcium carbonate, zinc carbonate, barium carbonate, and
magnesium carbonate), metals (e.g., titanium, tungsten, aluminum,
bismuth, nickel, molybdenum, iron, lead, copper, boron, cobalt,
beryllium, zinc, and tin), metal alloys (e.g., steel, brass,
bronze, boron carbide whiskers, and tungsten carbide whiskers),
oxides (e.g., zinc oxide, tin oxide, iron oxide, calcium oxide,
aluminum oxide, titanium dioxide, magnesium oxide, and zirconium
oxide), particulate carbonaceous materials (e.g., graphite, carbon
black, cotton flock, natural bitumen, cellulose flock, and leather
fiber), microballoons (e.g., glass and ceramic), fly ash, regrind
(i.e., core material that is ground and recycled), nanofillers and
combinations thereof. The amount of particulate material(s) present
in the rubber composition is typically within a range having a
lower limit of 5 parts or 10 parts by weight per 100 parts of the
base rubber, and an upper limit of 30 parts or 50 parts or 100
parts by weight per 100 parts of the base rubber. Filler materials
may be dual-functional fillers, such as zinc oxide (which may be
used as a filler/acid scavenger) and titanium dioxide (which may be
used as a filler/brightener material).
[0025] The rubber composition may also contain one or more
additives selected from processing aids, processing oils,
plasticizers, coloring agents, fluorescent agents, chemical blowing
and foaming agents, defoaming agents, stabilizers, softening
agents, impact modifiers, free radical scavengers, accelerators,
scorch retarders, and the like. The amount of additive(s) typically
present in the rubber composition is typically within a range
having a lower limit of 0 parts by weight per 100 parts of the base
rubber, and an upper limit of 20 parts or 50 parts or 100 parts or
150 parts by weight per 100 parts of the base rubber.
[0026] The rubber composition optionally includes a soft-and-fast
agent. Preferably, the rubber composition contains from 0.05 phr to
10.0 phr of a soft-and-fast agent. In one embodiment, the
soft-and-fast agent is present in an amount within a range having a
lower limit of 0.05 or 0.1 or 0.2 or 0.5 phr and an upper limit of
1.0 or 2.0 or 3.0 or 5.0 phr. In another embodiment, the
soft-and-fast agent is present in an amount of from 2.0 phr to 5.0
phr, or from 2.35 phr to 4.0 phr, or from 2.35 phr to 3.0 phr. In
an alternative high concentration embodiment, the soft-and-fast
agent is present in an amount of from 5.0 phr to 10.0 phr, or from
6.0 phr to 9.0 phr, or from 7.0 phr to 8.0 phr. In another
embodiment, the soft-and-fast agent is present in an amount of 2.6
phr.
[0027] Suitable soft-and-fast agents include, but are not limited
to, organosulfur and metal-containing organosulfur compounds;
organic sulfur compounds, including mono, di, and polysulfides,
thiol, and mercapto compounds; inorganic sulfide compounds; blends
of an organosulfur compound and an inorganic sulfide compound;
Group VIA compounds; substituted and unsubstituted aromatic organic
compounds that do not contain sulfur or metal; aromatic
organometallic compounds; hydroquinones; benzoquinones;
quinhydrones; catechols; resorcinols; and combinations thereof.
[0028] As used herein, "organosulfur compound" refers to any
compound containing carbon, hydrogen, and sulfur, where the sulfur
is directly bonded to at least 1 carbon. As used herein, the term
"sulfur compound" means a compound that is elemental sulfur,
polymeric sulfur, or a combination thereof. It should be further
understood that the term "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 elemental
sulfur.
[0029] Particularly suitable as soft-and-fast agents are
organosulfur compounds having the following general formula:
##STR00001##
where R.sub.1-R.sub.5 can be C.sub.1-8 alkyl groups; halogen
groups; thiol groups (--SH), carboxylated groups; sulfonated
groups; and hydrogen; in any order; and also pentafluorothiophenol;
2-fluorothiophenol; 3-fluorothiophenol; 4-fluorothiophenol;
2,3-fluorothiophenol; 2,4-fluorothiophenol; 3,4-fluorothiophenol;
3,5-fluorothiophenol 2,3,4-fluorothiophenol;
3,4,5-fluorothiophenol; 2,3,4,5-tetrafluorothiophenol;
2,3,5,6-tetrafluorothiophenol; 4-chlorotetrafluorothiophenol;
pentachlorothiophenol; 2-chlorothiophenol; 3-chlorothiophenol;
4-chlorothiophenol; 2,3-chlorothiophenol; 2,4-chlorothiophenol;
3,4-chlorothiophenol; 3,5-chlorothiophenol; 2,3,4-chlorothiophenol;
3,4,5-chlorothiophenol; 2,3,4,5-tetrachlorothiophenol;
2,3,5,6-tetrachlorothiophenol; pentabromothiophenol;
2-bromothiophenol; 3-bromothiophenol; 4-bromothiophenol;
2,3-bromothiophenol; 2,4-bromothiophenol; 3,4-bromothiophenol;
3,5-bromothiophenol; 2,3,4-bromothiophenol; 3,4,5-bromothiophenol;
2,3,4,5-tetrabromothiophenol; 2,3,5,6-tetrabromothiophenol;
pentaiodothiophenol; 2-iodothiophenol; 3-iodothiophenol;
4-iodothiophenol; 2,3-iodothiophenol; 2,4-iodothiophenol;
3,4-iodothiophenol; 3,5-iodothiophenol; 2,3,4-iodothiophenol;
3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;
2,3,5,6-tetraiodothiophenoland; zinc salts thereof; non-metal salts
thereof, for example, ammonium salt of pentachlorothiophenol;
magnesium pentachlorothiophenol; cobalt pentachlorothiophenol; and
combinations thereof. Preferably, the halogenated thiophenol
compound is pentachlorothiophenol, which is commercially available
in neat form or under the tradename STRUKTOL, a clay-based carrier
containing the sulfur compound pentachlorothiophenol loaded at 45
percent (correlating to 2.4 parts PCTP). STRUKTOL is commercially
available from Struktol Company of America of Stow, Ohio. PCTP is
commercially available in neat form and in the salt form from
eChinachem of San Francisco, Calif. Most preferably, the
halogenated thiophenol compound is the zinc salt of
pentachlorothiophenol.
[0030] Suitable metal-containing organosulfur compounds include,
but are not limited to, cadmium, copper, lead, and tellurium
analogs of diethyldithiocarbamate, diamyldithiocarbamate, and
dimethyldithiocarbamate, and combinations thereof.
[0031] Suitable disulfides include, but are not limited to,
4,4'-diphenyl disulfide; 4,4'-ditolyl disulfide; 2,2'-benzamido
diphenyl disulfide; bis(2-aminophenyl) disulfide;
bis(4-aminophenyl) disulfide; 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'-dithiodinaphthalene; 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; and combinations thereof.
[0032] Suitable inorganic sulfide compounds 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.
[0033] Suitable Group VIA compounds include, but are not limited
to, elemental sulfur and polymeric sulfur, such as those from
Elastochem, Inc. of Chardon, Ohio; sulfur catalyst compounds which
include PB(RM-S)-80 elemental sulfur and PB(CRST)-65 polymeric
sulfur, each of which is available from Elastochem, Inc; tellurium
catalysts, such as TELLOY, and selenium catalysts, such as VANDEX,
from RT Vanderbilt Company, Inc.
[0034] Suitable substituted and unsubstituted aromatic organic
components that do not include sulfur or a metal include, but are
not limited to, 4,4'-diphenyl acetylene, azobenzene, and
combinations thereof. The aromatic organic group preferably ranges
in size from C.sub.6-20, more preferably from C.sub.6-10.
[0035] Suitable substituted and unsubstituted aromatic
organometallic compounds include, but are not limited to, those
having the formula
(R.sub.1).sub.x--R.sub.3-M-R.sub.4--R.sub.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.6-24 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.6-24
aromatic group; and M includes an azo group or a metal component.
Preferably, R.sub.3 and R.sub.4 are each selected from a C.sub.6-10
aromatic group, more preferably selected from phenyl, benzyl,
naphthyl, benzamido, and benzothiazyl. Preferably R.sub.1 and
R.sub.2 are each selected from substituted and unsubstituted
C.sub.1-10 linear, branched, and cyclic alkyl, alkoxy, and
alkylthio groups, and C.sub.6-10 aromatic groups. When R.sub.1,
R.sub.2, R.sub.3, and 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 and sulfonamide; and phosphates and phosphites. When M is
a metal component, it may be any suitable elemental metal. The
metal is generally a transition metal, and is preferably tellurium
or selenium.
[0036] Suitable hydroquinones include, but are not limited to,
compounds represented by the following formula, and hydrates
thereof:
##STR00002##
[0037] where each of R.sub.1, R.sub.2, R.sub.3, and R.sub.4 is
independently selected from hydrogen, a halogen group (F, Cl, Br,
I), an alkyl group, a carboxyl group (--COOH) and metal salts
thereof (e.g., --COO.sup.-M.sup.+) and esters thereof (--COOR), an
acetate group (--CH.sub.2COOH) and esters thereof (--CH.sub.2COOR),
a formyl group (--CHO), an acyl group (--COR), an acetyl group
(--COCH.sub.3), a halogenated carbonyl group (--COX), a sulfo group
(--SO.sub.3H) and esters thereof (--SO.sub.3R), a halogenated
sulfonyl group (--SO.sub.2X), a sulfino group (--SO.sub.2H), an
alkylsulfinyl group (--SOR), a carbamoyl group (--CONH.sub.2), a
halogenated alkyl group, a cyano group (--CN), an alkoxy group
(--OR), a hydroxy group (--OH) and metal salts thereof (e.g.,
--O.sup.-M.sup.+), an amino group (--NH.sub.2), a nitro group
(--NO.sub.2), an aryl group (e.g., phenyl, tolyl, etc.), an aryloxy
group (e.g., phenoxy, etc.), an arylalkyl group (e.g., cumyl
(--C(CH.sub.3).sub.2--C.sub.6H.sub.6) or benzyl
(--CH.sub.2--C.sub.6H.sub.6)), a nitroso group (--NO), an acetamido
group (--NHCOCH.sub.3), and a vinyl group (--CH.dbd.CH.sub.2).
Particularly preferred hydroquinones include compounds represented
by the above formula, and hydrates thereof, wherein each of
R.sub.1, R.sub.2, R.sub.3, and R.sub.4 is independently selected
from the group consisting of: a metal salt of a carboxyl group
(e.g., --COO.sup.-M.sup.+), an acetate group (--CH.sub.2COOH) and
esters thereof (--CH.sub.2COOR), a hydroxy group (--OH), a metal
salt of a hydroxy group (e.g., --O.sup.-M.sup.+), an amino group
(--NH.sub.2), a nitro group (--NO.sub.2), an aryl group (e.g.,
phenyl, tolyl, etc.), an aryloxy group (e.g., phenoxy, etc.), an
arylalkyl group (e.g., cumyl (--C(CH.sub.3).sub.2--C.sub.6H.sub.6)
or benzyl (--CH.sub.2--C.sub.6H.sub.6)), a nitroso group (--NO), an
acetamido group (--NHCOCH.sub.3), and a vinyl group
(--CH.dbd.CH.sub.2). Examples of particularly suitable
hydroquinones include, but are not limited to, hydroquionone;
tetrachlorohydroquinone; 2-chlorohydroquionone;
2-bromohydroquinone; 2,5-dichlorohydroquinone;
2,5-dibromohydroquinone; tetrabromohydroquinone;
2-methylhydroquinone; 2-t-butylhydroquinone;
2,5-di-t-amylhydroquinone; and 2-(2-chlorophenyl)hydroquinone
hydrate. Hydroquinone and tetrachlorohydroquinone are particularly
preferred, and even more particularly preferred is
2-(2-chlorophenyl)hydroquinone hydrate.
[0038] Suitable benzoquinones include, but are not limited to,
compounds represented by the following formula, and hydrates
thereof:
##STR00003##
where each of R.sub.1, R.sub.2, R.sub.3, and R.sub.4 is
independently selected from the ligands disclosed above for the
hydroquinones. Particularly preferred benzoquinones include
compounds represented by the above formula, and hydrates thereof,
where each of R.sub.1, R.sub.2, R.sub.3, and R.sub.4 is
independently selected from the group consisting of: a metal salt
of a carboxyl group (e.g., --COO.sup.-M.sup.+), an acetate group
(--CH.sub.2COOH) and esters thereof (--CH.sub.2COOR), a hydroxy
group (--OH), a metal salt of a hydroxy group (e.g.,
--O.sup.-M.sup.+), an amino group (--NH.sub.2), a nitro group
(--NO.sub.2), an aryl group (e.g., phenyl, tolyl, etc.), an aryloxy
group (e.g., phenoxy, etc.), an arylalkyl group (e.g., cumyl
(--C(CH.sub.3).sub.2--C.sub.6H.sub.6) or benzyl
(--CH.sub.2--C.sub.6H.sub.6)), a nitroso group (--NO), an acetamido
group (--NHCOCH.sub.3), and a vinyl group (--CH.dbd.CH.sub.2).
Methyl p-benzoquinone and tetrachloro p-benzoquinone are more
particularly preferred.
[0039] Suitable quinhydrones include, but are not limited to,
compounds represented by the following formula, and hydrates
thereof:
##STR00004##
where each of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6,
R.sub.7, and R.sub.8 is independently selected from the ligands
disclosed above for the hydroquinones and benzoquinones.
Particularly preferred quinhydrones include compounds represented
by the above formula, and hydrates thereof, wherein each of
R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, and
R.sub.8 is independently selected from a metal salt of a carboxyl
group (e.g., --COO.sup.-M.sup.+), an acetate group (--CH.sub.2COOH)
and esters thereof (--CH.sub.2COOR), a hydroxy group (--OH), a
metal salt of a hydroxy group (e.g., --O.sup.-M.sup.+), an amino
group (--NH.sub.2), a nitro group (--NO.sub.2), an aryl group
(e.g., phenyl, tolyl, etc.), an aryloxy group (e.g., phenoxy,
etc.), an arylalkyl group (e.g., cumyl
(--C(CH.sub.3).sub.2--C.sub.6H.sub.6) or benzyl
(--CH.sub.2--C.sub.6H.sub.6)), a nitroso group (--NO), an acetamido
group (--NHCOCH.sub.3), and a vinyl group (--CH.dbd.CH.sub.2).
Particularly preferred quinhydrones also include compounds
represented by the above formula wherein each of R.sub.1, R.sub.2,
R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, and R.sub.8 is
hydrogen.
[0040] Suitable catechols include, but are not limited to,
compounds represented by the following formula, and hydrates
thereof:
##STR00005##
where each of R.sub.1, R.sub.2, R.sub.3, and R.sub.4, is
independently selected from the ligands disclosed above for the
hydroquinones, benzoquinones, and quinhydrones.
[0041] Suitable resorcinols include, but are not limited to,
compounds represented by the following formula, and hydrates
thereof:
##STR00006##
where each of R.sub.1, R.sub.2, R.sub.3, and R.sub.4 is
independently selected from the ligands disclosed above for the
hydroquinones, benzoquinones, quinhydrones, and catechols.
2-Nitroresorcinol is particularly preferred.
[0042] When the rubber composition includes one or more
hydroquinones, benzoquinones, quinhydrones, catechols, resorcinols,
or a combination thereof, the total amount of hydroquinone(s),
benzoquinone(s), quinhydrone(s), catechol(s), and/or resorcinol(s)
present in the composition is typically at least 0.1 parts by
weight or at least 0.15 parts by weight or at least 0.2 parts by
weight per 100 parts of the base rubber, or an amount within the
range having a lower limit of 0.1 parts or 0.15 parts or 0.25 parts
or 0.3 parts or 0.375 parts by weight per 100 parts of the base
rubber, and an upper limit of 0.5 parts or 1 part or 1.5 parts or 2
parts or 3 parts by weight per 100 parts of the base rubber.
[0043] In a particularly preferred embodiment, the soft-and-fast
agent is selected from zinc pentachlorothiophenol,
pentachlorothiophenol, ditolyl disulfide, diphenyl disulfide,
dixylyl disulfide, 2-nitroresorcinol, and combinations thereof.
[0044] Referring to FIG. 1, in one embodiment of the present
invention the golf ball 10 includes a core 12, the materials of
which are described above, an inner cover layer 14, and an outer
cover layer 16.
[0045] The inner cover layers of the present invention are formed
from a thermoplastic ionomeric material that either 1) has a low
melt flow index and/or 2) has an improved heat resistance.
Preferably, the thermoplastic, ionomeric compositions are used to
form an inner cover layer in a multi-layer cover
[0046] Improved heat resistance is important to this cover
construction, as described in detail in the background section,
because the outer cover includes a thermosetting or thermoplastic
outer cove layer that must be molded over the ionomeric inner cover
layer. When using a conventional ionomeric composition, which has
low heat resistance and relatively high melt flow properties,
flow-out or leakage of the ionomeric layer into (and possibly
through) the overmolded thermoset or thermoplastic layer during
compression molding at an elevated temperature and pressure is a
problem.
[0047] In one embodiment, a reduced melt flow ionomer is made by
neutralizing about 70 wt. % or more, 75 wt. % or more, preferably
80 wt. % or more, more preferably at least 90 wt. %, and most
preferably at least about 95 wt. % of the acid groups without the
use of any "ionic plasticizer" such as the fatty acids or fatty
acid salts required to form the highly-neutralized polymers. In a
preferred embodiment a high acid ionomer containing 19 wt. % to 20
wt. % methacrylic or acrylic acid is neutralized with a blend of
zinc and sodium cations to the 95 wt. % level such that the melt
flow of the composition at 190.degree. C. is very low (less than
0.5 g/10 min) and the melt flow at 280.degree. C. is less than
about 0.50 g/10 min.
[0048] The melt flow indices of the thermoplastic, preferably
ionomeric, polymers used to form the inner cover layers of the
invention should have a melt flow index, as measured at 280.degree.
C. under a mass of 10 kg, of less than about 35 g/10 min,
preferably less than about 20 g/10 min, and most preferably less
than about 10 g/10 min. In a preferred embodiment, these melt flow
indices have concurrent melt flow indices, as measured at
265.degree. C. under a mass of 5 kg, of less than about 10 g/10
min, preferably less than about 5 g/10 min. In a preferred
particularly embodiment, both of these melt flow indices further
have concurrent melt flow indices, as measured at 190.degree. C.
and 230.degree. C. under a mass of 2.16 kg, of less than about 2
g/10 min, preferably less than about 1 g/10 min, more preferably
less than about 0.5 g/10 min, and most preferably less than about
0.1 g/10 min.
[0049] Other preferred cation sources include lithium, magnesium,
manganese, aluminum, potassium, calcium, zirconium, barium, etc.
When aluminum is used it is preferably used at low levels with
another cation source, such as zinc, sodium, or lithium, since
aluminum has a dramatic effect on melt flow reduction and often
cannot be used alone at high levels. Very high surface area cation
sources, such as micro and nano-scale cation sources, are
particularly preferred.
[0050] Where processability of such highly-neutralized ionomers may
become very difficult, a small level of plasticizer may be
tolerable without adversely affecting the heat resistance
properties. For example, perhaps 0.5 phr to 5 phr of a fatty acid,
polyethylene glycol, wax, bis-stearamide, mineral, or phthalate,
may be used.
[0051] In another embodiment, an amine or pyridine compound is
used, preferably in addition to a metal cation, to produce a
reduced melt flow ionomer. Suitable examples include ethylamine,
methylamine, diethylamine, tert-butylamine, dodecylamine, etc.
[0052] The addition of fillers, fibers, flakes is also believed to
promote low flow. Particularly preferred additives of this nature
include, but are not limited to, very-high-surface-area fillers
that have an affinity for the acid groups in ionomer. In
particular, fillers, fibers or flakes having cationic nature such
that they may also contribute to the neutralization of the ionomer
are suitable. Aluminum oxide comprising fillers are preferred.
Also, silica, fumed silica, or precipitated silica, such as those
sold under the tradename HISIL from PPG Industries, or carbon
black. Nano-scale materials are also preferred and include, but are
not limited to, nanotubes, nanoflakes, nanofillers, or
nanoclays.
[0053] In another embodiment, a peroxide or other source of free
radicals is added to the ionomer and is allowed to react (in an
extruder or in an injection molding machine, just prior to the golf
ball layer being molded). The peroxide is added at a relatively low
activity level of about 0.01 to 5.00 phr, more preferably about
0.025 to 2.50 phr, and most preferably about 0.05 to 1.50 phr.
[0054] In another embodiment, a pre-molded layer of a golf ball
comprising an ionomeric composition is treated with radiation
(i.e., such as e-beam, gamma, X-ray, UV, etc.) to effect
crosslinking and thus increase the heat resistance of the layer.
Additionally, post-molding treatment, involving dipping or soaking
the ionomer layer in a solution of a neutralizing or crosslinking
agent, may be employed to reduce flow of the surface of the layer
upon exposure to heating while adding the outer core layer. For
example, exposing the molded layer to a peroxide solution followed
by heating to crosslink the "skin" of the ionomer layer, or soaking
the molded layer in a solution of aluminum acetylacetonate or
aluminum isopropoxide to neutralize the "skin" of the ionomer
layer, are suitable.
[0055] The low flow and/or improved heat resistance compositions
herein may be used in any core and/or cover layer where a layer is
molded over the low flow composition in a manner that would cause
conventional materials to flow or flow-through that layer upon
heating. For example the low flow composition may be used in a
center, intermediate, or outer core layer, or in a cover layer of a
multilayer golf ball, wherein the low flow composition is
overmolded with a material that requires processing at such a
temperature at or above the flow or melt temperature of the
substrate layer.
[0056] A preferred embodiment includes the inner cover layers
disclosed herein. Another preferred embodiment is a thermoplastic
inner cover layer over which is molded a crosslinked diene rubber
composition requiring a cure temperature well above the melting
point of the thermoplastic inner cover layer material. Another
preferred embodiment is an inner cover layer of a multilayer golf
ball wherein the outer cover layer comprises a crosslinked diene
rubber composition. An alternative embodiment is an inner cover
layer of a multilayer golf ball where the outer cover layer
comprises a thermoplastic polyurethane or polyurea that is
processed at elevated temperatures. Typically such materials are
either injection molded directly over the inner cover layer using a
retractable pin molding process or by first injection molding half
shells of the TPU followed by compression molding the half shells
over the inner layer (which has previously been molded over the
core). It is the latter process of compression molding a high melt
temperature material (i.e., TPU) over the inner cover layer which
is very difficult to perform without the inner cover "leaking" out
at the equator. Any combination of neutralization and treatment or
altering method disclosed herein may also be used.
[0057] In another embodiment a blend of ionomer and a higher
temperature melting thermoplastic resin is employed. For example, a
blend of ionomer with polyamide, polyester, polyethylene and PE
containing low levels of (meth)acrylic acid, HYTREL etc., will
increase the temperature resistance of the thermoplastic core
layer. A preferred example is a blend of a zinc ionomer (copolymer
or terpolymer type) with NYLON 11 or NYLON 12 (although NYLON 6 or
NYLON 66 may also be used). Nylons with better moisture stability
are preferred.
[0058] In another embodiment an organosilane is grafted onto the
ionomer backbone using a catalyst via extrusion producing a still
mainly thermoplastic material which is then injection or
compression molded into an inner cover layer. The bulk of the
crosslinking is achieved later by reacting this layer by exposing
it to moisture where the water molecules diffuse into the cover and
react with the organosilane side chains producing siloxane
crosslinks which directly join together the ionomer chains creating
a crosslinked network that is more resistant to heat and
pressure
[0059] Another embodiment is a blend of ionomer with a reactive
polymer, such as an epoxy resin or an epoxy-group functional
polymer, such as glycidyl (meth)acrylate polymers disclosed in U.S.
Pat. No. 4,968,752 to DuPont-Mitsui or U.S. Pat. Nos. 5,155,157 and
5,091,478. Also suitable are epoxy-acid-tert amines as disclosed in
U.S. Pat. No. 6,087,417. A FUSABOND-type polymer containing very
high levels of maleic anhydride may also be suitable. Other
examples include DuPont BEXLOY and REFLECTIONS polymers.
[0060] Other suitable thermoplastic compositions for use in the
inner cover layers include, but are not limited to, the following
polymers (including homopolymers, copolymers, and derivatives
thereof) having good inherent thermal stability (e.g., they melt at
a high enough temperature) and used at levels so as to not cause
detrimental flow-through: (a) polyesters, particularly those
modified with a compatibilizing group such as sulfonate or
phosphonate, including modified poly(ethylene terephthalate),
modified poly(butylene terephthalate), modified poly(propylene
terephthalate), modified poly(trimethylene terephthalate), modified
poly(ethylene naphthenate), and those disclosed in U.S. Pat. Nos.
6,353,050, 6,274,298, and 6,001,930, the entire disclosures of
which are hereby incorporated herein by reference, and blends of
two or more thereof; (b) polyamides, polyamide-ethers, and
polyamide-esters, and those disclosed in U.S. Pat. Nos. 6,187,864,
6,001,930, and 5,981,654, the entire disclosures of which are
hereby incorporated herein by reference, and blends of two or more
thereof; (c) polyurethanes, polyureas, polyurethane-polyurea
hybrids, and blends of two or more thereof; (d) fluoropolymers,
such as those disclosed in U.S. Pat. Nos. 5,691,066, 6,747,110 and
7,009,002, the entire disclosures of which are hereby incorporated
herein by reference, and blends of two or more thereof; (e)
polystyrenes, such as poly(styrene-co-maleic anhydride),
acrylonitrile-butadiene-styrene, poly(styrene sulfonate),
polyethylene styrene, and blends of two or more thereof; (f)
polyvinyl chlorides and grafted polyvinyl chlorides, and blends of
two or more thereof; (g) polycarbonates, blends of
polycarbonate/acrylonitrile-butadiene-styrene, blends of
polycarbonate/polyurethane, blends of polycarbonate/polyester, and
blends of two or more thereof; (h) polyethers, such as polyarylene
ethers, polyphenylene oxides, block copolymers of alkenyl aromatics
with vinyl aromatics and polyamicesters, and blends of two or more
thereof; (i) polyimides, polyetherketones, polyamideimides, and
blends of two or more thereof; and (j) polycarbonate/polyester
copolymers and blends.
[0061] Other suitable thermoplastic compositions for use in the
inner cover layers include, but are not limited to, the following
polymers (including homopolymers, copolymers, and derivatives
thereof) treated by a radiation source (discussed above) and/or a
peroxide (or other altering method described herein) so as to not
cause detrimental flow-through: (a) non-ionomeric acid polymers,
such as E/Y- and E/X/Y-type copolymers, wherein E is an olefin
(e.g., ethylene), Y is a carboxylic acid such as acrylic,
methacrylic, crotonic, maleic, fumaric, or itaconic acid, and X is
a softening comonomer such as vinyl esters of aliphatic carboxylic
acids wherein the acid has from 2 to 10 carbons, alkyl ethers
wherein the alkyl group has from 1 to 10 carbons, and alkyl
alkylacrylates such as alkyl methacrylates wherein the alkyl group
has from 1 to 10 carbons; and blends of two or more thereof; (b)
metallocene-catalyzed polymers, such as those disclosed in U.S.
Pat. Nos. 6,274,669, 5,919,862, 5,981,654, and 5,703,166, the
entire disclosures of which are hereby incorporated herein by
reference, and blends of two or more thereof; (c) polypropylenes
and polyethylenes, particularly grafted polypropylene and grafted
polyethylenes that are modified with a functional group, such as
maleic anhydride of sulfonate, and blends of two or more thereof;
(d) polyvinyl acetates, preferably having less than about 9% of
vinyl acetate by weight, and blends of two or more thereof; and (e)
polyvinyl alcohols, and blends of two or more thereof.
[0062] Ionomeric compositions suitable for forming the inner cover
layer comprise one or more acid polymers, each of which is
partially- or highly-neutralized (up to 100% and without the use of
fatty acid/salts), and optionally additives, fillers, and/or melt
flow modifiers. Suitable acid polymers are salts of homopolymers
and copolymers of .alpha.,.beta.-ethylenically unsaturated mono- or
di-carboxylic acids, and combinations thereof, optionally including
a softening monomer, and preferably having an acid content (prior
to neutralization) of from 1 wt % to 30 wt %, more preferably from
5 wt % to 20 wt %. The acid polymer is preferably neutralized to 70
wt % or higher, including up to 100 wt %, with a suitable cation
source, such as metal cations and salts thereof, organic amine
compounds, ammonium, and combinations thereof. Preferred cation
sources are metal cations and salts thereof, wherein the metal is
preferably lithium, sodium, potassium, magnesium, calcium, barium,
lead, tin, zinc, aluminum, manganese, nickel, chromium, copper, or
a combination thereof.
[0063] Suitable additives and fillers include, for example, blowing
and foaming agents, optical brighteners, coloring agents,
fluorescent agents, whitening agents, UV absorbers, light
stabilizers, defoaming agents, processing aids, mica, talc,
nanofillers, antioxidants, stabilizers, softening agents, fragrance
components, plasticizers, impact modifiers, acid copolymer wax,
surfactants; inorganic fillers, such as zinc oxide, titanium
dioxide, tin oxide, calcium oxide, magnesium oxide, barium sulfate,
zinc sulfate, calcium carbonate, zinc carbonate, barium carbonate,
mica, talc, clay, silica, lead silicate, and the like; high
specific gravity metal powder fillers, such as tungsten powder,
molybdenum powder, and the like; regrind, i.e., cover material that
is ground and recycled; and nano-fillers.
[0064] In a particular embodiment, the inner cover layer is formed
from a blend of two or more ionomers. In a particular aspect of
this embodiment, the intermediate core layer is formed from a 50/50
wt % blend of two different highly-neutralized ethylene/methacrylic
acid copolymers.
[0065] In another particular embodiment, the inner cover layer is
formed from a blend of one or more ionomers and a maleic
anhydride-grafted non-ionomeric polymer. In a particular aspect of
this embodiment, the non-ionomeric polymer is a
metallocene-catalyzed polymer. In another particular aspect of this
embodiment, the inner cover layer is formed from a blend of a
highly-neutralized ethylene/methacrylic acid copolymer and a maleic
anhydride-grafted metallocene-catalyzed polyethylene.
[0066] In yet another particular embodiment, the inner cover layer
is formed from a composition selected from the group consisting of
highly-neutralized ionomers optionally blended with a maleic
anhydride-grafted non-ionomeric polymer; polyester elastomers;
polyamide elastomers; and combinations of two or more thereof.
[0067] The thermoplastic inner cover layer is optionally treated or
admixed with a thermoset diene composition to reduce or prevent
flow upon overmolding. Optional treatments may also include the
addition of peroxide to the material prior to molding, or a
post-molding treatment with, for example, a crosslinking solution,
electron beam, gamma radiation, isocyanate or amine solution
treatment, or the like. Such treatments may prevent the inner cover
layer from melting and flowing or "leaking" out at the mold
equator, as the thermoset outer cover layer is molded thereon at a
temperature necessary to crosslink the outer core layer, which is
typically from 280.degree. F. (138.degree. C.) to 360.degree. F.
(182.degree. C.) for a period of about 5 to 30 minutes.
[0068] The following examples are representative of the novel inner
cover layer compositions of the invention and are non-limiting in
scope of what materials are suitable. Table I below presents 14
compositions, the first 10 being representative of the invention
and the final 4 being controls.
TABLE-US-00001 TABLE I Cross- Final linking Neutral'zn Final e-beam
Cross-linking Reagent Achieved Ionomer dose Base polymer Ratio
Reagent Added* (Mole %) Type (Mrad) Low-flow Ex 1 SURLYN .RTM.
9120.sup.a 100 NaOH ~41 77 Na/Zn -- Ex 2 SURLYN .RTM. 9120 100 NaOH
~51 87 Na/Zn -- Ex 3 PRIMACOR .RTM. 100 Li(OH).cndot.H.sub.20 90 86
Li -- 5986.sup.b Ex 4 PRIMACOR .RTM. 100 Li(OH).cndot.H.sub.20 98
95 Li -- 5986 Ex 5 PRIMACOR .RTM. 100 Li(OH).cndot.H.sub.20 105 100
Li -- 5986 Ex 6 NUCREL .RTM. 2906.sup.c 100 Zn
diacetate.cndot.2H.sub.20 110 ~100 Zn -- Treated Ex 7 SURLYN .RTM.
8140.sup.d/ 50/50 -- 0 37 Na/Zn 10 SURLYN .RTM. 9120 Ex 8 SURLYN
.RTM. 8140/ 50/50 -- 0 37 Na/Zn 20 SURLYN .RTM. 9120 Ex 9 SURLYN
.RTM. 8140/ 50/50 -- 0 37 Na/Zn 30 SURLYN .RTM. 9120 Ex 10 SURLYN
.RTM. 9120 100 PERKADOX .RTM. 0 36 Zn -- BC Comparative CE1 SURLYN
.RTM. 9120 100 NaOH ~23 59 Na/Zn -- CE2 SURLYN .RTM. 8140/ 50/50 --
0 37 Na/Zn -- SURLYN .RTM. 9120 CE3 SURLYN .RTM. 8940.sup.e/ 75/25
-- 0 38 Na/Zn -- SURLYN .RTM. 9910.sup.f CE4 HPF 2000.sup.g 100 --
0 ~100 Mg -- *to achieve additional mole % neutralization as
indicated .sup.apartially Zn-neutralized, 19 wt. % methacrylic
acid-ethylene copolymeric ionomer from DuPont .sup.bunneutralized,
20.5 wt % acrylic acid-ethylene copolymer from Dow
.sup.cunneutralized, 19 wt % methacrylic acid-ethylene copolymer
from DuPont .sup.dpartially Na-neutralized, 19 wt % methacrylic
acid-ethylene copolymeric ionomer from DuPont .sup.epartially
Na-neutralized, 15 wt % methacrylic acid-ethylene copolymeric
ionomer from DuPont .sup.fpartially Zn-neutralized, 15 wt %
methacrylic acid-ethylene copolymeric ionomer from DuPont
.sup.gfully Mg-neutralized, ~40% fatty acid salt modified, acrylic
acid-ethylene-n-butyl acrylate terpolymeric ionomer available from
DuPont .sup.hdicumyl peroxide available from Akzo Nobel
[0069] Examples 1-6 and CE1 were made by combining the base polymer
and the cross-linking reagent in a twin-screw extruder at
appropriate zone temperatures, screw speed, and feed rates to
achieve the final mole % neutralization indicated in TABLE I. It is
well known that cross-linking reagents can be added to the extruder
directly as a powder, as a caustic aqueous solution, or as a
masterbatch on a suitable carrier polymer. Examples 7-9 were made
by injection molding a dry-blend of SURLYN 8140 and 9120 around a
core, and then radiation treating as indicated. The melt flow index
was then measured by removing and grinding the layer. Example 10
was made by compounding 0.5 phr of Perkadox BC into SURLYN 9120 and
curing for 15 min at 350.degree. F. prior to measuring melt flow.
Comparative examples 2-3 were prepared by melt blending.
TABLE-US-00002 TABLE II Melt Flow Condition - Temp (.degree.
C.)/Mass (kg) 190/2.16 230/2.16 265/5 280/10 (g/10 min) (g/10 min)
(g/10 min) (g/10 min) Pass/Fail Low-flow Ex 1 L 0.70 8.00 33.4 Pass
Ex 2 L 0.34 3.76 19.5 Pass Ex 3 L 0.46 9.7 44 Pass Ex 4 L L 2.9
18.0 Pass Ex 5 L L 0.90 5.49 Pass Ex 6 L 0.39 3.83 14.35 Pass
Treated Ex 7 L L 0.37 5.82 Pass Ex 8 L L L 0.12 Pass Ex 9 L L L L
Pass Ex 10 L 0.13 3.86 18.4 Pass Comparative CE1 0.25 1.64 18.16
~79 Fail CE2 2.41 14.34 ~86 x Fail CE3 2.14 9.38 ~77 x Fail CE4
1.28 11.17 ~61 x Fail x = unmeasurable (flow was too high to make a
meaningful measurement) L = low flow (flow was so low that no
measureable material was extruded)
[0070] The melt flow rate characterizes the resistance to flow of a
molten plastic material and was determined in accordance with ASTM
Standard D1238-04C using a Tinius-Olsen Extrusion Plastometer. The
quantity of melt flow is measured by placing the sample in a heated
barrel where it is held for a certain time then forced through a
die using a weighted piston. The ASTM standard specifies the barrel
and die dimensions and suggests a number of temperature and weight
conditions typically chosen to give results between 0.15 and 50
g/10 min. Melt flow results are reported as grams of material
extruded over a 10-minute time interval at a specified temperature
and load.
[0071] TABLE II contains melt flow data for each of the examples
and comparative examples, as well pass/fail data indicating whether
a rubber outer cover layer could be compression molded over a layer
of each material in TABLE I without that layer leaking out into the
rubber outer cover layer. Most of the melt flow temperature and
mass conditions in TABLE II can be found in the ASTM method that
was used to generate the data in the table. The 190.degree. C./2.16
kg condition is an industry standard used to report the melt flow
of ionomers. Conventional thought was that an ionomer with a melt
flow index, under these conditions, of less than about 0.5 would be
unmoldable (not melt processible) for golf ball applications. The
ASTM method suggests that if a melt flow value below about 0.15
g/10 minutes is obtained, that a higher temperature and/or mass
should be used and suggests alternative combinations. TABLE II
shows a progression of increasing temperature/mass combinations to
better characterize the flow properties of each material.
Generally, materials should be compared to each other under
identical melt flow conditions. In some cases, however, information
can be obtained by comparing melt flow values under different
conditions. For example, a material that has a melt flow of 3 g/10
minutes at 280.degree. C./10 kg flows less than a material that has
the same melt flow at 190.degree. C./2.16 kg. The melt flow
conditions that we selected were also useful in determining
injection molding conditions for each material and as a predictor
of overmolding success or failure--CE1-4 all have
substantially-higher melt flow values at a given condition relative
to the inventive examples and are, therefore, insufficient for the
inventive cover layers. The absolute value of the melt flow at each
condition can be used to predict the suitability of a candidate
material for golf ball constructions described herein.
[0072] Suitable compositions for forming the outer cover layer
include the rubber compositions disclosed above for forming the
center layer(s). The outer cover layer composition may be the same
or a different rubber composition than the composition(s) used to
form the center layer(s).
[0073] The outer cover layer may further comprise from 1 to 100 phr
of a stiffening agent. Suitable stiffening agents include, but are
not limited to, ionomers, acid copolymers and terpolymers,
polyamides, and polyesters. A transpolyisoprene (e.g., TP-301
transpolyisoprene from Kuraray) or transbutadiene rubber may also
be added to increase stiffness to a cover layer and/or improve
cold-forming properties, which may improve processability by making
it easier to mold inner cover layer half-shells during the golf
ball manufacturing process. When included in a cover layer
composition, the stiffening agent is preferably present in an
amount of from 5 to 10 pph.
[0074] In one embodiment, the specific gravity of one or more of
the cover layers is increased. Suitable fillers for increasing
specific gravity include, but are not limited to, metal and metal
alloy powders, including, but not limited to, bismuth powder, boron
powder, brass powder, bronze powder, cobalt powder, copper powder,
nickel-chromium iron metal powder, iron metal powder, molybdenum
powder, nickel powder, stainless steel powder, titanium metal
powder zirconium oxide powder, tungsten metal powder, beryllium
metal powder, zinc metal powder, and tin metal powder; metal
flakes, including, but not limited to, aluminum flakes; metal
oxides, including, but not limited to, zinc oxide, iron oxide,
aluminum oxide, titanium dioxide, magnesium oxide, zirconium oxide,
and tungsten trioxide; metal stearates; particulate carbonaceous
materials including, but not limited to, graphite and carbon black;
and nanoparticulates and hybrid organic/inorganic materials.
Particularly suitable density-increasing fillers include, but are
not limited to, tungsten, tungsten oxide, tungsten metal powder,
zinc oxide, barium sulfate, and titanium dioxide.
[0075] In another embodiment, the specific gravity of one or more
of the cover layers is reduced. The specific gravity of a layer can
be reduced by incorporating cellular resins, low specific gravity
fillers, fibers, flakes, or spheres, or hollow microspheres or
balloons, such as glass bubbles or ceramic zeospheres, in the
polymeric matrix. The specific gravity of a layer can also be
reduced by foaming. Typical physical foaming/blowing agents include
volatile liquids such as freons, other halogenated hydrocarbons,
water, aliphatic hydrocarbons, gases, and solid blowing agents,
i.e., compounds that liberate gas as a result of desorption of gas.
Typical chemical foaming/blowing agents include inorganic agents,
such as ammonium carbonate and carbonates of alkali metals, and
organic agents, such as azo and diazo compounds. Suitable azo
compounds include, but are not limited to,
2,2'-azobis(2-cyanobutane), 2,2'-azobis(methylbutyronitrile),
azodicarbonamide, p,p'-oxybis(benzene sulfonyl hydrazide),
p-toluene sulfonyl semicarbazide, and p-toluene sulfonyl hydrazide.
Blowing agents also include CELOGEN foaming/blowing agents from
Lion Copolymer; OPEX foaming/blowing agents from Chemtura
Corporation; nitroso compounds, sulfonylhydrazides, azides of
organic acids and their analogs, triazines, triazole and tetrazole
derivatives, sulfonyl semicarbazides, urea derivatives, guanidine
derivatives, and esters such as alkoxyboroxines. Blowing agents
also include agents that liberate gasses as a result of chemical
interaction between components, such as mixtures of acids and
metals, mixtures of organic acids and inorganic carbonates, mixture
of nitrites and ammonium salts, and the hydrolytic decomposition of
urea. Suitable foaming/blowing agents also include expandable
microspheres, such as EXPANCEL microspheres from Akzo Nobel.
[0076] The specific gravity of each of the cover layers is from
0.50 g/cm.sup.3 to 5.00 g/cm.sup.3. Cover layers having an
increased specific gravity preferably have a specific gravity of
0.95 g/cm.sup.3 or greater, or 1.00 g/cm.sup.3 or greater, or 1.05
g/cm.sup.3 or greater, or 1.10 g/cm.sup.3 or greater, or 1.20
g/cm.sup.3 or greater, or 1.30 g/cm.sup.3 or greater, or 1.40
g/cm.sup.3 or greater. Cover layers having a reduced specific
gravity preferably have a specific gravity of 1.05 g/cm.sup.3 or
less, or 0.95 g/cm.sup.3 or less, or 0.90 g/cm.sup.3 or less, or
0.85 g/cm.sup.3 or less. In a particular embodiment, the specific
gravity of inner cover is 0.95 g/cm.sup.3 or greater, or greater
than 1.05 g/cm.sup.3, or 1.15 g/cm.sup.3 or greater; and the
specific gravity of the outer cover layer is 1.30 g/cc or less, or
1.20 g/cm.sup.3 or less, or from 0.90 g/cm.sup.3 to 1.20
g/cm.sup.3. In a particular aspect of this embodiment, the specific
gravity of the outer cover layer is less than the specific gravity
of the intermediate layer. In another particular aspect of this
embodiment, the inner core is formed from a composition wherein the
specific gravity has been decreased; and the outer core layer is
formed from a composition wherein the specific gravity has been
increased, preferably with tungsten filler. The weight distribution
of core and cover layers disclosed herein can be varied to achieve
certain desired parameters, such as spin rate, compression, and
initial velocity.
[0077] The core preferably has an overall diameter of 1.25 inches
or greater, or 1.35 inches or greater, or 1.390 inches or greater,
or 1.45 inches or greater, or an overall diameter within a range
having a lower limit of 0.25 or 0.50 or 0.75 or 1.00 or 1.25 or
1.35 or 1.39 or 1.40 or 1.44 inches and an upper limit of 1.46 or
1.49 or 1.50 or 1.55 or 1.58 or 1.60 inches.
[0078] The core has a center hardness within a range having a lower
limit of 20 or 25 or 30 or 35 or 40 or 45 or 50 or 55 Shore C and
an upper limit of 60 or 65 or 70 or 75 or 90 Shore C. The core has
an outer surface hardness within a range having a lower limit of 20
or 50 or 70 or 75 Shore C and an upper limit of 75 or 80 or 85 or
90 or 95 Shore C.
[0079] The core has a negative hardness gradient, a zero hardness
gradient, or a positive hardness gradient of up to 45 Shore C.
Preferably, the center has a positive hardness gradient wherein the
difference between the center hardness and the surface hardness of
the center is from 10 to 45 Shore C.
[0080] The core has an overall compression of 90 or less, or 80 or
less, or 70 or less, or 60 or less, or 50 or less, or 40 or less,
or 20 or less, or a compression within a range having a lower limit
of 10 or 20 or 30 or 35 or 40 and an upper limit of 50 or 60 or 70
or 80 or 90.
[0081] One or more optional outer core layers are formed from
thermoset or thermoplastic compositions and have a thickness within
a range having a lower limit of 0.005 or 0.01 or 0.02 or 0.04
inches and an upper limit of 0.05 or 0.10 or 0.20 or 0.30 or 0.40
inches In one embodiment, the outer core layer has a surface
hardness of 45 Shore C or greater, or 70 Shore C or greater, or 75
Shore C or greater, or 80 Shore C or greater, or a surface hardness
within a range having a lower limit of 45 or 70 or 80 Shore C and
an upper limit of 90 or 95 Shore C. In a particular aspect of this
embodiment, the surface hardness of the outer core layer is greater
than the surface hardness of the center. In another particular
aspect of this embodiment, the surface hardness of the outer core
layer is less than the surface hardness of the center. In another
embodiment, the outer core layer has a surface hardness within a
range having a lower limit of 50 or 60 or 65 Shore C and an upper
limit of 70 or 75 or 80 Shore C. In a particular aspect of this
embodiment, the surface hardness of the outer core layer is less
than the surface hardness of the center.
[0082] In another embodiment, the outer core layer has a surface
hardness of 20 Shore C or greater, or 30 Shore C or greater, or 35
Shore C or greater, or 40 Shore C or greater, or a surface hardness
within a range having a lower limit of 20 or 30 or 35 or 40 or 50
Shore C and an upper limit of 60 or 70 or 80 Shore C. In a
particular aspect of this embodiment, the outer core layer is
formed from a rubber composition selected from those disclosed in
U.S. Patent Application Publication Nos. 2009/0011857 and
2009/0011862, the entire disclosures of which are hereby
incorporated herein by reference.
[0083] Golf ball cores of the present invention typically have a
coefficient of restitution ("COR") at 125 ft/s of at least 0.750,
or at least 0.775 or at least 0.780, or at least 0.782, or at least
0.785, or at least 0.787, or at least 0.790, or at least 0.795, or
at least 0.798, or at least 0.800.
[0084] Suitable outer cover materials include, but are not limited
to, ionomer resins and blends thereof (e.g., SURLYN ionomer resins
and DuPont HPF 1000 and HPF 2000; IOTEK ionomers from ExxonMobil;
AMPLIFY IO ionomers of ethylene acrylic acid copolymers from Dow;
and CLARIX ionomer resins from Schulman); polyurethanes; polyureas;
copolymers and hybrids of polyurethane and polyurea; polyethylene,
including, for example, low density polyethylene, linear low
density polyethylene, and high density polyethylene; polypropylene;
rubber-toughened olefin polymers; acid copolymers, e.g.,
(meth)acrylic acid, which do not become part of an ionomeric
copolymer; plastomers; flexomers; styrene/butadiene/styrene block
copolymers; styrene/ethylene-butylene/styrene block copolymers;
dynamically vulcanized elastomers; ethylene vinyl acetates;
ethylene methyl acrylates; polyvinyl chloride resins; polyamides,
amide-ester elastomers, and graft copolymers of ionomer and
polyamide, including, for example, PEBAX thermoplastic polyether
block amides from Arkema, Inc.; crosslinked trans-polyisoprene and
blends thereof; polyester-based thermoplastic elastomers, such as
HYTREL from DuPont; polyurethane-based thermoplastic elastomers,
such as ELASTOLLAN from BASF; synthetic or natural vulcanized
rubber; and combinations thereof. In a particular embodiment, the
cover is a single layer formed from a composition selected from the
group consisting of ionomers, polyester elastomers, polyamide
elastomers, and combinations of two or more thereof.
[0085] Compositions comprising an ionomer or a blend of two or more
ionomers are particularly suitable cover materials. Preferred
ionomeric outer cover compositions include: (a) a composition
comprising a "high acid ionomer" (i.e., having an acid content of
greater than 16 wt %), such as SURLYN 8150; (b) a composition
comprising a high acid ionomer and a maleic anhydride-grafted
non-ionomeric polymer (e.g., FUSABOND functionalized polymers). A
particularly preferred blend of high acid ionomer and maleic
anhydride-grafted polymer is a 84 wt %/16 wt % blend of SURLYN 8150
and FUSABOND; c) a composition comprising a 50/45/5 blend of SURLYN
8940/SURLYN 9650/NUCREL 960, preferably having a material hardness
of from 80 to 85 Shore C; (d) a composition comprising a 50/25/25
blend of SURLYN.RTM. 8940/SURLYN 9650/SURLYN 9910, preferably
having a material hardness of about 90 Shore C; (e) a composition
comprising a 50/50 blend of SURLYN 8940/SURLYN 9650, preferably
having a material hardness of about 86 Shore C; (f) a composition
comprising a blend of SURLYN 7940/SURLYN 8940, optionally including
a melt flow modifier; (g) a composition comprising a blend of a
first high acid ionomer and a second high acid ionomer, wherein the
first high acid ionomer is neutralized with a different cation than
the second high acid ionomer (e.g., 50/50 blend of SURLYN 8150 and
SURLYN 9150), optionally including one or more melt flow modifiers
such as an ionomer, ethylene-acid copolymer or ester terpolymer;
and (h) a composition comprising a blend of a first high acid
ionomer and a second high acid ionomer, wherein the first high acid
ionomer is neutralized with a different cation than the second high
acid ionomer, and from 0 to 10 wt % of an ethylene/acid/ester
ionomer wherein the ethylene/acid/ester ionomer is neutralized with
the same cation as either the first high acid ionomer or the second
high acid ionomer or a different cation than the first and second
high acid ionomers (e.g., a blend of 40-50 wt % SURLYN 8140, 40-50
wt % SURLYN 9120, and 0-10 wt % SURLYN 6320).
[0086] Ionomeric outer cover compositions can be blended with
non-ionic thermoplastic resins, particularly to manipulate product
properties. Examples of suitable non-ionic thermoplastic resins
include, but are not limited to, polyurethane, poly-ether-ester,
poly-amide-ether, polyether-urea, thermoplastic polyether block
amides (e.g., PEBAX block copolymers from Arkema, Inc.),
styrene-butadiene-styrene block copolymers,
styrene(ethylene-butylene)-styrene block copolymers, polyamides,
polyesters, polyolefins (e.g., polyethylene, polypropylene,
ethylene-propylene copolymers, polyethylene-(meth)acrylate,
plyethylene-(meth)acrylic acid, functionalized polymers with maleic
anhydride grafting, FUSABOND functionalized polymers from DuPont,
functionalized polymers with epoxidation, elastomers (e.g.,
ethylene propylene diene monomer rubber, metallocene-catalyzed
polyolefin) and ground powders of thermoset elastomers.
[0087] Ionomer golf ball outer cover compositions may include a
flow modifier, such as, but not limited to, NUCREL acid copolymer
resins, and particularly NUCREL 960, from DuPont.
[0088] Polyurethanes, polyureas, and blends and hybrids of
polyurethane/polyurea are also particularly suitable for forming
cover layers. When used as cover layer materials, polyurethanes and
polyureas can be thermoset or thermoplastic. Thermoset materials
can be formed into golf ball layers by conventional casting or
reaction injection molding techniques. Thermoplastic materials can
be formed into golf ball layers by conventional compression or
injection molding techniques.
[0089] While the inventive golf ball may be formed from a variety
of differing cover materials, preferred outer cover layer materials
include, but are not limited to, (1) polyurethanes, such as those
prepared from polyols or polyamines and diisocyanates or
polyisocyanates and/or their prepolymers, and those disclosed in
U.S. Pat. Nos. 5,334,673 and 6,506,851; (2) polyureas, such as
those disclosed in U.S. Pat. Nos. 5,484,870 and 6,835,794; (3)
polyurethane-urea hybrids, blends or copolymers comprising urethane
or urea segments; and (4) other suitable polyurethane compositions
comprising a reaction product of at least one polyisocyanate and at
least one curing agent are disclosed in U.S. Pat. Nos. 7,105,610
and 7,491,787, all of which are incorporated herein by
reference.
[0090] Suitable polyurethane compositions comprise a reaction
product of at least one polyisocyanate and at least one curing
agent. The curing agent can include, for example, one or more
polyamines, one or more polyols, or a combination thereof. The
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, the polyols described herein are suitable for use in
one or both components of the polyurethane material, i.e., as part
of a prepolymer and in the curing agent. Suitable polyurethanes are
described in U.S. Pat. No. 7,331,878, which is incorporated by
reference in its entirety.
[0091] Exemplary polyisocyanates suitable for use in the outer
cover layers of the invention include, but are not limited to,
4,4'-diphenylmethane diisocyanate ("MDI"); polymeric MDI;
carbodiimide-modified liquid MDI; 4,4'-dicyclohexylmethane
diisocyanate; p-phenylene diisocyanate ("PPDI"); m-phenylene
diisocyanate; toluene diisocyanate ("TDI");
3,3'-dimethyl-4,4'-biphenylene diisocyanate;
isophoronediisocyanate; 1,6-hexamethylene diisocyanate ("HDI");
naphthalene diisocyanate; xylene diisocyanate; p-tetramethylxylene
diisocyanate; m-tetramethylxylene diisocyanate; ethylene
diisocyanate; propylene-1,2-diisocyanate;
tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate;
dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;
cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate;
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; methyl
cyclohexylene diisocyanate; triisocyanate of HDI; triisocyanate of
2,4,4-trimethyl-1,6-hexane diisocyanate; tetracene diisocyanate;
napthalene diisocyanate; anthracene diisocyanate; isocyanurate of
toluene diisocyanate; uretdione of hexamethylene 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-isocyanate, tri-isocyanate, 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, typically less
than about 0.1% free monomer isocyanate 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.
[0092] 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 8.0% NCO, more preferably
no greater than about 7.8%, and most preferably no greater than
about 7.5% NCO with a level of NCO of about 7.2 or 7.0, or 6.5% NCO
commonly used.
[0093] Any polyol available to one of ordinary skill in the art is
suitable for use according to the invention. 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. In one preferred embodiment,
the polyol includes polyether polyol. 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.
[0094] In another embodiment, polyester polyols are included in the
polyurethane material. Suitable polyester polyols include, but are
not limited to, polyethylene adipate glycol; polybutylene adipate
glycol; polyethylene propylene adipate glycol;
o-phthalate-1,6-hexanediol; poly(hexamethylene adipate) glycol; and
mixtures thereof. The hydrocarbon chain can have saturated or
unsaturated bonds, or substituted or unsubstituted aromatic and
cyclic groups.
[0095] 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.
[0096] In yet another embodiment, polycarbonate polyols are
included in the polyurethane material of the invention. Suitable
polycarbonates include, but are not limited to, polyphthalate
carbonate and poly(hexamethylene carbonate) glycol. The hydrocarbon
chain can have saturated or unsaturated bonds, or substituted or
unsubstituted aromatic and cyclic groups. In one embodiment, the
molecular weight of the polyol is from about 200 to about 4000.
[0097] Polyamine curatives are also suitable for use in 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'-dialkyl diamino
diphenyl methane; p,p'-methylene dianiline; m-phenylenediamine;
4,4'-methylene-bis-(2-chloroaniline);
4,4'-methylene-bis-(2,6-diethylaniline);
4,4'-methylene-bis-(2,3-dichloroaniline);
4,4'-diamino-3,3'-diethyl-5,5'-dimethyl diphenylmethane;
2,2',3,3'-tetrachloro diamino diphenylmethane; 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 300, from Albermarle Corporation of Baton Rouge, La.
Suitable polyamine curatives, which include both primary and
secondary amines, preferably have molecular weights ranging from
about 64 to about 2000.
[0098] At least one of a diol, triol, tetraol, or
hydroxy-terminated curatives 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
PTMEG; 1,3-bis(2-hydroxyethoxy) benzene;
1,3-bis-[2-(2-hydroxyethoxy) ethoxy] benzene;
1,3-bis-{2-[2-(2-hydroxyethoxy) ethoxy]ethoxy} benzene;
1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol;
resorcinol-di-(.beta.-hydroxyethyl)ether;
hydroquinone-di-(.beta.-hydroxyethyl)ether; and mixtures thereof.
Preferred hydroxy-terminated curatives include
1,3-bis(2-hydroxyethoxy) benzene; 1,3-bis-[2-(2-hydroxyethoxy)
ethoxy]benzene; 1,3-bis-{2-[2-(2-hydroxyethoxy) ethoxy]ethoxy}
benzene; 1,4-butanediol, and mixtures thereof. 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.
[0099] 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.
[0100] In a preferred embodiment of the present invention,
saturated polyurethanes are used to form one or more of the cover
layers, preferably the outer cover layer, and may be selected from
among both castable thermoset and thermoplastic polyurethanes.
[0101] In this embodiment, the saturated polyurethanes of the
present invention are substantially free of aromatic groups or
moieties. Saturated polyurethanes suitable for use in the invention
are a product of a reaction between at least one polyurethane
prepolymer and at least one saturated curing agent. The
polyurethane prepolymer is a product formed by a reaction between
at least one saturated polyol and at least one saturated
diisocyanate. A catalyst may be employed to promote the reaction
between the curing agent and the isocyanate and polyol, or the
curing agent and the prepolymer.
[0102] Saturated diisocyanates which can be used include, without
limitation, ethylene diisocyanate; propylene-1,2-diisocyanate;
tetramethylene-1,4-diisocyanate; 1,6-hexamethylene-diisocyanate;
2,2,4-trimethylhexamethylene diisocyanate;
2,4,4-trimethylhexamethylene diisocyanate;
dodecane-1,12-diisocyanate; dicyclohexylmethane diisocyanate;
cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate;
cyclohexane-1,4-diisocyanate;
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane;
isophorone diisocyanate; methyl cyclohexylene diisocyanate;
triisocyanate of HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexane
diisocyanate. The most preferred saturated diisocyanates are
4,4'-dicyclohexylmethane diisocyanate and isophorone
diisocyanate.
[0103] Saturated polyols are appropriate for use in this invention
and include, without limitation, polyether polyols such as PTMEG
and poly(oxypropylene) glycol. Suitable saturated polyester polyols
include polyethylene adipate glycol, polyethylene propylene adipate
glycol, polybutylene adipate glycol, polycarbonate polyol and
ethylene oxide-capped polyoxypropylene diols. Saturated
polycaprolactone polyols which are useful in the invention include
diethylene glycol-initiated polycaprolactone,
1,4-butanediol-initiated polycaprolactone, 1,6-hexanediol-initiated
polycaprolactone; trimethylol propane-initiated polycaprolactone,
neopentyl glycol initiated polycaprolactone, and PTMEG-initiated
polycaprolactone. The most preferred saturated polyols are PTMEG
and PTMEG-initiated polycaprolactone.
[0104] Suitable saturated curatives include 1,4-butanediol,
ethylene glycol, diethylene glycol, PTMEG, propylene glycol;
trimethanolpropane; tetra-(2-hydroxypropyl)-ethylenediamine;
isomers and mixtures of isomers of cyclohexyldimethylol, isomers
and mixtures of isomers of cyclohexane bis(methylamine);
triisopropanolamine; ethylene diamine; diethylene triamine;
triethylene tetramine; tetraethylene pentamine;
4,4'-dicyclohexylmethane diamine;
2,2,4-trimethyl-1,6-hexanediamine;
2,4,4-trimethyl-1,6-hexanediamine; diethyleneglycol
di-(aminopropyl)ether;
4,4'-bis-(sec-butylamino)-dicyclohexylmethane;
1,2-bis-(sec-butylamino)cyclohexane; 1,4-bis-(sec-butyl amino)
cyclohexane; isophorone diamine; hexamethylene diamine; propylene
diamine; 1-methyl-2,4-cyclohexyl diamine; 1-methyl-2,6-cyclohexyl
diamine; 1,3-diaminopropane; dimethylamino propylamine;
diethylamino propylamine; imido-bis-propylamine; isomers and
mixtures of isomers of diaminocyclohexane; monoethanolamine;
diethanolamine; triethanolamine; monoisopropanolamine; and
diisopropanolamine. The most preferred saturated curatives are
1,4-butanediol, 1,4-cyclohexyldimethylol and
4,4'-bis-(sec-butylamino)-dicyclohexylmethane.
[0105] Alternatively, other suitable polymers include partially- or
fully-neutralized ionomer, metallocene, or other single-site
catalyzed polymer, polyester, polyamide, non-ionomeric
thermoplastic elastomer, copolyether-esters, copolyether-amides,
polycarbonate, polybutadiene, polyisoprene, polystryrene block
copolymers (such as styrene-butadiene-styrene),
styrene-ethylene-propylene-styrene,
styrene-ethylene-butylene-styrene, and the like, and blends
thereof. Thermosetting polyurethanes or polyureas are suitable for
outer cover layers.
[0106] Additionally, polyurethane can be replaced with or blended
with a polyurea material. Polyureas are distinctly different from
polyurethane compositions, but also result in desirable aerodynamic
and aesthetic characteristics when used in golf ball components.
The polyurea-based compositions are preferably saturated in
nature.
[0107] Without being bound to any particular theory, it is now
believed that substitution of the long chain polyol segment in the
polyurethane prepolymer with a long chain polyamine oligomer soft
segment to form a polyurea prepolymer, improves shear, cut, and
resiliency, as well as adhesion to other components. Thus, the
polyurea compositions of this invention may be formed from the
reaction product of an isocyanate and polyamine prepolymer
crosslinked with a curing agent. For example, polyurea-based
compositions of the invention may be prepared from at least one
isocyanate, at least one polyether amine, and at least one diol
curing agent or at least one diamine curing agent.
[0108] Any polyamine available to one of ordinary skill in the art
is suitable for use in the polyurea prepolymer. Polyether amines
are particularly suitable for use in the prepolymer. As used
herein, "polyether amines" refer to at least polyoxyalkyleneamines
containing primary amino groups attached to the terminus of a
polyether backbone. Due to the rapid reaction of isocyanate and
amine, and the insolubility of many urea products, however, the
selection of diamines and polyether amines is limited to those
allowing the successful formation of the polyurea prepolymers. In
one embodiment, the polyether backbone is based on tetramethylene,
propylene, ethylene, trimethylolpropane, glycerin, and mixtures
thereof.
[0109] Suitable polyether amines include, but are not limited to,
methyldiethanolamine; polyoxyalkylenediamines such as,
polytetramethylene ether diamines, polyoxypropylenetriamine, and
polyoxypropylene diamines; poly(ethylene oxide capped oxypropylene)
ether diamines; propylene oxide-based triamines;
triethyleneglycoldiamines; trimethylolpropane-based triamines;
glycerin-based triamines; and mixtures thereof. In one embodiment,
the polyether amine used to form the prepolymer is JEFFAMINE D2000
from Huntsman Chemical Co. of Austin, Tex.
[0110] The molecular weight of the polyether amine for use in the
polyurea prepolymer may range from about 100 to about 5000. In one
embodiment, the polyether amine molecular weight is about 200 or
greater, preferably about 230 or greater. In another embodiment,
the molecular weight of the polyether amine is about 4000 or less.
In yet another embodiment, the molecular weight of the polyether
amine is about 600 or greater. In still another embodiment, the
molecular weight of the polyether amine is about 3000 or less. In
yet another embodiment, the molecular weight of the polyether amine
is between about 1000 and about 3000, more preferably is between
about 1500 to about 2500, and most preferably from 2000 to 2500.
Because lower molecular weight polyether amines may be prone to
forming solid polyureas, a higher molecular weight oligomer, such
as JEFFAMINE D2000, is preferred.
[0111] Other suitable castable polyurea compositions for use in the
golf balls of the present invention include those formed from the
reaction product of a prepolymer formed from an isocyanate and an
amine-terminated PTMEG and an amine-terminated curing agent, and
those formed from the reaction product of a polyurea prepolymer
cured with an amine-terminated PTMEG. In either scenario, the
amine-terminated PTMEG is terminated with secondary amines. In
addition, the amine-terminated PTMEG may be a copolymer with
polypropylene glycol, wherein the PTMEG is end-capped with one or
more propylene glycol units to form the copolymer.
[0112] Another suitable composition includes a prepolymer including
the reaction product of an isocyanate-containing component and an
amine-terminated component, wherein the amine-terminated component
includes a copolymer of PTMEG and polypropylene glycol including at
least one terminal amino group; and an amine-terminated curing
agent. In this aspect of the invention the prepolymer may include
about 4% to about 9% NCO groups by weight of the prepolymer.
[0113] In one embodiment, the at least one terminal amino group
includes secondary amines. In another embodiment, the at least one
terminal amino group includes a terminal secondary amino group at
both ends of the copolymer. In yet another embodiment, the
amine-terminated curing agent includes a secondary diamine.
[0114] The polyureas of the present invention also include a
polyurea composition formed from a prepolymer formed from the
reaction product of an isocyanate-containing compound and an
isocyanate-reactive compound, wherein the isocyanate-reactive
compound includes PTMEG homopolymer having a molecular weight of
about 1800 to 2200 and terminal secondary amino groups; and an
amine-terminated curing agent. In this aspect of the invention, the
prepolymer may include about 6% to about 8% NCO groups by weight of
the prepolymer. In addition, the PTMEG homopolymer may have a
molecular weight of about 1900 to about 2100. In one embodiment,
the amine-terminated curing agent includes a secondary diamine.
[0115] In one embodiment, the polyalkylene glycol includes
polypropylene glycol, polyethylene glycol, and copolymers or
mixtures thereof. In another embodiment, the amino groups include
secondary amino groups. The amine-terminated curing agent may
include an amine-terminated PTMEG. In one embodiment, the
amine-terminated PTMEG includes at least one terminal secondary
amino group.
[0116] Conventional aromatic polyurethane/urethane elastomers and
polyurethane/urea elastomers are generally prepared by curing a
prepolymer of diisocyanate and long chain polyol with at least one
diol curing agent or at least one diamine curing agent,
respectively. In contrast, the use of a long chain amine-terminated
compound to form a polyurea prepolymer has been shown to improve
shear, cut, and resiliency, as well as adhesion to other
components.
[0117] The use of an amine-terminated PTMEG and/or an
amine-terminated copolymer of PTMEG and polypropylene glycol
("PPG") in the prepolymer or as a curing agent provide enhanced
shear, cut, and resiliency as compared to conventional polyurea
elastomers. For example, the compositions of the invention have
improved durability and performance characteristics over that of a
polyurea composition formed with amine-terminated PPG.
[0118] The polyurea-based compositions of this invention may be
formed in several ways: a) from a prepolymer that is the reaction
product of an isocyanate-containing component and amine-terminated
PTMEG chain extended with a curing agent; b) from a prepolymer that
is the reaction product of an isocyanate-containing component and
an amine-terminated copolymer of PTMEG and PPG chain extended with
a curing agent; c) from a prepolymer that is the reaction product
of a polyurea-based prepolymer chain extended with an
amine-terminated PTMEG; and d) from a prepolymer that is the
reaction product of a polyurea-based prepolymer chain extended with
an amine-terminated copolymer of PTMEG and PPG.
[0119] For example, the compositions of the invention may be
prepared from at least one isocyanate-containing component, at
least one amine-terminated copolymer of PTMEG and PPG, preferably a
secondary diamine, and at least one amine-terminated curing agent,
preferably a secondary aliphatic diamine or primary aromatic
diamine curing agent. The presence of PTMEG in the backbone
provides better shear resistance as compared to a backbone
including only PPG. Commercially-available amine-terminated PTMEG
and/or copolymer of PTMEG and PPG include those sold by Huntsman
Chemical under the tradenames XTJ-559, XTG-604, XTG-605, and
XTG-653.
[0120] As briefly discussed above, some amines may be unsuitable
for reaction with the isocyanate because of the rapid reaction
between the two components. In particular, shorter chain amines are
fast reacting. In one embodiment, however, a hindered secondary
diamine may be suitable for use in the prepolymer. It is believed
that an amine with a high level of stearic hindrance, e.g., a
tertiary butyl group on the nitrogen atom, has a slower reaction
rate than an amine with no hindrance or a low level of hindrance.
For example, 4,4'-bis-(sec-butylamino)-dicyclohexylmethane
(CLEARLINK 1000) may be suitable for use in combination with an
isocyanate to form the polyurea prepolymer.
[0121] Any isocyanate available to one of ordinary skill in the art
is suitable for use in the polyurea prepolymer. Isocyanates for use
with the present invention include aliphatic, cycloaliphatic,
araliphatic, aromatic, any derivatives thereof, and combinations of
these compounds having two or more isocyanate groups per molecule.
The isocyanates may be organic polyisocyanate-terminated
prepolymers. The isocyanate-containing reactable component may also
include any isocyanate-functional monomer, dimer, trimer, or
multimeric adduct thereof, prepolymer, quasi-prepolymer, or
mixtures thereof. Isocyanate-functional compounds may include
monoisocyanates or polyisocyanates that include any isocyanate
functionality of two or more.
[0122] Suitable isocyanate-containing components include
diisocyanates having the generic structure:
O.dbd.C.dbd.N--R--N.dbd.C.dbd.O, where R is preferably a cyclic,
aromatic, or linear or branched hydrocarbon moiety containing from
about 1 to about 20 carbon atoms. The diisocyanate may also contain
one or more cyclic groups or one or more phenyl groups. When
multiple cyclic or aromatic groups are present, linear and/or
branched hydrocarbons containing from about 1 to about 10 carbon
atoms can be present as spacers between the cyclic or aromatic
groups. In some cases, the cyclic or aromatic group(s) may be
substituted at the 2-, 3-, and/or 4-positions, or at the ortho-,
meta-, and/or para-positions, respectively. Substituted groups may
include, but are not limited to, halogens, primary, secondary, or
tertiary hydrocarbon groups, or a mixture thereof. Copolymeric
isocyanates, such as Bayer DESMODUR HL, which is a copolymer of TDI
and HDI, are preferred.
[0123] Examples of diisocyanates that can be used with the present
invention include, but are not limited to, substituted and isomeric
mixtures including 2,2'-, 2,4'-, and 4,4'-diphenylmethane
diisocyanate; 3,3'-dimethyl-4,4'-biphenylene diisocyanate; toluene
diisocyanate; polymeric MDI; carbodiimide-modified liquid
4,4'-diphenylmethane diisocyanate; p-phenylene diisocyanate;
m-phenylene diisocyanate; triphenyl methane-4,4'- and triphenyl
methane-4,4'-triisocyanate; naphthylene-1,5-diisocyanate; 2,4'-,
4,4'-, and 2,2-biphenyl diisocyanate; polyphenyl polymethylene
polyisocyanate; mixtures of MDI and PMDI; mixtures of PMDI and TDI;
ethylene diisocyanate; propylene-1,2-diisocyanate;
tetramethylene-1,2-diisocyanate; tetramethylene-1,3-diisocyanate;
tetramethylene-1,4-diisocyanate; 1,6-hexamethylene-diisocyanate;
octamethylene diisocyanate; decamethylene diisocyanate;
2,2,4-trimethylhexamethylene diisocyanate;
2,4,4-trimethylhexamethylene diisocyanate;
dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;
cyclohexane-1,2-diisocyanate; cyclohexane-1,3-diisocyanate;
cyclohexane-1,4-diisocyanate; methyl-cyclohexylene diisocyanate;
2,4-methylcyclohexane diisocyanate; 2,6-methyl cyclohexane
diisocyanate; 4,4'-dicyclohexyl diisocyanate; 2,4'-dicyclohexyl
diisocyanate; 1,3,5-cyclohexane triisocyanate;
isocyanatomethylcyclohexane isocyanate;
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane;
isocyanatoethylcyclohexane isocyanate;
bis(isocyanatomethyl)-cyclohexane diisocyanate;
4,4'-bis(isocyanatomethyl) dicyclohexane;
2,4'-bis(isocyanatomethyl) dicyclohexane; isophorone diisocyanate;
triisocyanate of HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexane
diisocyanate; 4,4' dicyclohexylmethane diisocyanate;
2,4-hexahydrotoluene diisocyanate; 2,6-hexahydrotoluene
diisocyanate; 1,2-, 1,3-, and 1,4-phenylene diisocyanate; aromatic
aliphatic isocyanate, such as 1,2-, 1,3-, and 1,4-xylene
diisocyanate; m-tetramethylxylene diisocyanate; p-tetramethylxylene
diisocyanate; trimerized isocyanurate of any polyisocyanate, such
as isocyanurate of toluene diisocyanate; trimer of diphenylmethane
diisocyanate; trimer of tetramethylxylene diisocyanate;
isocyanurate of hexamethylene diisocyanate; isocyanurate of
isophorone diisocyanate; and mixtures thereof; dimerized uredione
of any polyisocyanate, such as uretdione of toluene diisocyanate;
uretdione of hexamethylene diisocyanate; and mixtures thereof;
modified polyisocyanate derived from the above isocyanates and
polyisocyanates; and mixtures thereof.
[0124] Examples of saturated diisocyanates that can be used with
the present invention include, but are not limited to, ethylene
diisocyanate; propylene-1,2-diisocyanate; tetramethylene
diisocyanate; tetramethylene-1,4-diisocyanate;
1,6-hexamethylene-diisocyanate; octamethylene diisocyanate;
decamethylene diisocyanate; 2,2,4-trimethylhexamethylene
diisocyanate; 2,4,4-trimethylhexamethylene diisocyanate;
dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;
cyclohexane-1,2-diisocyanate; cyclohexane-1,3-diisocyanate;
cyclohexane-1,4-diisocyanate; methyl-cyclohexylene diisocyanate;
2,4-methylcyclohexane diisocyanate; 2,6-methylcyclohexane
diisocyanate; 4,4'-dicyclohexyl diisocyanate; 2,4'-dicyclohexyl
diisocyanate; 1,3,5-cyclohexane triisocyanate;
isocyanatomethylcyclohexane isocyanate;
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane;
isocyanatoethylcyclohexane isocyanate;
bis(isocyanatomethyl)-cyclohexane diisocyanate;
4,4'-bis(isocyanatomethyl) dicyclohexane;
2,4'-bis(isocyanatomethyl) dicyclohexane; isophorone diisocyanate;
triisocyanate of HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexane
diisocyanate; 4,4' dicyclohexylmethane diisocyanate;
2,4-hexahydrotoluene diisocyanate; 2,6-hexahydrotoluene
diisocyanate; and mixtures thereof. Aromatic aliphatic isocyanates
may also be used to form light stable materials. Examples of such
isocyanates include 1,2-, 1,3-, and 1,4-xylene diisocyanate;
meta-tetramethylxylene diisocyanate; p-tetramethylxylene
diisocyanate; trimerized isocyanurate of any polyisocyanate, such
as isocyanurate of toluene diisocyanate, trimer of diphenylmethane
diisocyanate, trimer of tetramethylxylene diisocyanate,
isocyanurate of hexamethylene diisocyanate, isocyanurate of
isophorone diisocyanate, and mixtures thereof; dimerized uredione
of any polyisocyanate, such as uretdione of toluene diisocyanate,
uretdione of hexamethylene diisocyanate, and mixtures thereof;
modified polyisocyanate derived from the above isocyanates and
polyisocyanates; and mixtures thereof. In addition, the aromatic
aliphatic isocyanates may be mixed with any of the saturated
isocyanates listed above for the purposes of this invention.
[0125] The number of unreacted NCO groups in the polyurea
prepolymer of isocyanate and polyether amine may be varied to
control such factors as the speed of the reaction, the resultant
hardness of the composition, and the like. For example, the number
of unreacted NCO groups in the polyurea prepolymer of isocyanate
and polyether amine may be less than about 14%. In one embodiment,
the polyurea prepolymer has from about 5% to 11% unreacted NCO
groups, preferably from about 6% to 9.5% unreacted NCO groups. In
one embodiment, the percentage of unreacted NCO groups is about 3%
to 9%. Alternatively, the percentage of unreacted NCO groups in the
polyurea prepolymer may be about 7.5% or less, more preferably,
about 7% or less. In another embodiment, the unreacted NCO content
is from about 2.5% to 7.5%, more preferably from about 4% to
6.5%.
[0126] When formed, polyurea prepolymers may contain about 10% to
20% by weight of the prepolymer of free isocyanate monomer. Thus,
in one embodiment, the polyurea prepolymer may be stripped of the
free isocyanate monomer. For example, after stripping, the
prepolymer may contain about 1% or less free isocyanate monomer. In
another embodiment, the prepolymer contains about 0.5% by weight or
less of free isocyanate monomer.
[0127] The polyether amine may be blended with additional polyols
to formulate copolymers that are reacted with excess isocyanate to
form the polyurea prepolymer. In one embodiment, less than about
30% polyol by weight of the copolymer is blended with the saturated
polyether amine. In another embodiment, less than about 20% polyol
by weight of the copolymer, preferably less than about 15% by
weight of the copolymer, is blended with the polyether amine. The
polyols listed above with respect to the polyurethane prepolymer,
e.g., polyether polyols, polycaprolactone polyols, polyester
polyols, polycarbonate polyols, hydrocarbon polyols, other polyols,
and mixtures thereof, are also suitable for blending with the
polyether amine. The molecular weight of these polymers may be from
about 200 to about 4000, but also may be from about 1000 to about
3000, and more preferably are from about 1500 to about 2500.
[0128] The polyurea composition can be formed by crosslinking the
polyurea prepolymer with a single curing agent or a blend of curing
agents. The curing agent of the invention is preferably an
amine-terminated curing agent, more preferably a secondary diamine
curing agent so that the composition contains only urea linkages.
In one embodiment, the amine-terminated curing agent may have a
molecular weight of about 64 or greater. In another embodiment, the
molecular weight of the amine-curing agent is about 2000 or less.
As discussed above, certain amine-terminated curing agents may be
modified with a compatible amine-terminated freezing point
depressing agent or mixture of compatible freezing point depressing
agents.
[0129] Suitable amine-terminated curing agents include, but are not
limited to, ethylene diamine; hexamethylene diamine;
1-methyl-2,6-cyclohexyl diamine; tetrahydroxypropylene ethylene
diamine; 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine;
4,4'-bis-(sec-butylamino)-dicyclohexylmethane;
1,4-bis-(sec-butylamino)-cyclohexane;
1,2-bis-(sec-butylamino)-cyclohexane; derivatives of
4,4'-bis-(sec-butylamino)-dicyclohexylmethane;
4,4'-dicyclohexylmethane diamine;
1,4-cyclohexane-bis-(methylamine);
1,3-cyclohexane-bis-(methylamine); diethylene glycol
di-(aminopropyl)ether; 2-methylpentamethylene-diamine;
diaminocyclohexane; diethylene triamine; triethylene tetramine;
tetraethylene pentamine; propylene diamine; 1,3-diaminopropane;
dimethylamino propylamine; diethylamino propylamine; dipropylene
triamine; imido-bis-propylamine; monoethanolamine, diethanolamine;
triethanolamine; monoisopropanolamine, diisopropanolamine;
isophoronediamine; 4,4'-methylenebis-(2-chloroaniline);
3,5;dimethylthio-2,4-toluenediamine;
3,5-dimethylthio-2,6-toluenediamine;
3,5-diethylthio-2,4-toluenediamine;
3,5-diethylthio-2,6-toluenediamine;
4,4'-bis-(sec-butylamino)-diphenylmethane and derivatives thereof;
1,4-bis-(sec-butylamino)-benzene; 1,2-bis-(sec-butylamino)-benzene;
N,N'-dialkylamino-diphenylmethane; N,N,N',N'-tetrakis
(2-hydroxypropyl)ethylene diamine;
trimethyleneglycol-di-p-aminobenzoate;
polytetramethyleneoxide-di-p-aminobenzoate;
4,4'-methylenebis-(3-chloro-2,6-diethyleneaniline);
4,4'-methylenebis-(2,6-diethylaniline); m-phenylenediamine;
paraphenylenediamine; and mixtures thereof. In one embodiment, the
amine-terminated curing agent is
4,4'-bis-(sec-butylamino)-dicyclohexylmethane.
[0130] Suitable saturated amine-terminated curing agents include,
but are not limited to, ethylene diamine; hexamethylene diamine;
1-methyl-2,6-cyclohexyl diamine; tetrahydroxypropylene ethylene
diamine; 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine;
4,4'-bis-(sec-butylamino)-dicyclohexylmethane;
1,4-bis-(sec-butylamino)-cyclohexane;
1,2-bis-(sec-butylamino)-cyclohexane; derivatives of
4,4'-bis-(sec-butylamino)-dicyclohexylmethane;
4,4'-dicyclohexylmethane diamine;
4,4'-methylenebis-(2,6-diethylaminocyclohexane;
1,4-cyclohexane-bis-(methylamine);
1,3-cyclohexane-bis-(methylamine); diethylene glycol
di-(aminopropyl)ether; 2-methylpentamethylene-diamine;
diaminocyclohexane; diethylene triamine; triethylene tetramine;
tetraethylene pentamine; propylene diamine; 1,3-diaminopropane;
dimethylamino propylamine; diethylamino propylamine;
imido-bis-propylamine; monoethanolamine, diethanolamine;
triethanolamine; monoisopropanolamine, diisopropanolamine;
isophoronediamine; triisopropanolamine; and mixtures thereof. In
addition, any of the polyether amines listed above may be used as
curing agents to react with the polyurea prepolymers.
[0131] 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.
[0132] 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.
[0133] Cover compositions may include one or more filler(s), such
as the fillers given above for rubber compositions of the present
invention (e.g., titanium dioxide, barium sulfate, etc.), and/or
additive(s), such as coloring agents, fluorescent agents, whitening
agents, antioxidants, dispersants, UV absorbers, light stabilizers,
plasticizers, surfactants, compatibility agents, foaming agents,
reinforcing agents, release agents, and the like.
[0134] The cover preferably has a surface hardness of 70 Shore D or
less, or 65 Shore D or less, or 60 Shore D or less, or 55 Shore D
or less. The cover preferably has a material hardness of 70 Shore D
or less, or 65 Shore D or less, or 60 Shore D or less, or 55 Shore
D or less. Alternatively, the cover preferably has a surface
hardness of 60 Shore D or greater, or 65 Shore D or greater. The
cover preferably has a material hardness of 60 Shore D or greater,
or 65 Shore D or greater.
[0135] In a particular embodiment, the cover is a dual- or
multi-layer cover including an inner or intermediate cover layer
formed from a composition of the present invention and an outer
cover layer formed from a polyurethane- or polyurea-based
composition. The inner cover layer preferably has a surface
hardness of 70 Shore D or less, or 65 Shore D or less, or less than
65 Shore D, or a Shore D hardness of from 50 to 65, or a Shore D
hardness of from 57 to 60, or a Shore D hardness of 58, and a
thickness within a range having a lower limit of 0.010 or 0.020 or
0.030 inches and an upper limit of 0.045 or 0.080 or 0.120 inches.
The outer cover layer is preferably formed from a castable or
reaction injection moldable polyurethane, polyurea, or copolymer or
hybrid of polyurethane/polyurea. Such cover material is preferably
thermosetting, but may be thermoplastic. The outer cover layer
composition preferably has a material hardness of 85 Shore C or
less, or 45 Shore D or less, or 40 Shore D or less, or from 25
Shore D to 40 Shore D, or from 30 Shore D to 40 Shore D. The outer
cover layer preferably has a surface hardness within a range having
a lower limit of 20 or 30 or 35 or 40 Shore D and an upper limit of
52 or 58 or 60 or 65 or 70 or 72 or 75 Shore D. The outer cover
layer preferably has a thickness within a range having a lower
limit of 0.01 or 0.015 or 0.025 inches and an upper limit of 0.035
or 0.04 or 0.045 or 0.05 or 0.055 or 0.075 or 0.08 or 0.115
inches.
[0136] A moisture vapor barrier layer is optionally employed
between the core and the cover. Moisture vapor barrier layers are
further disclosed, for example, in U.S. Pat. Nos. 6,632,147; and
7,182,702, the entire disclosures of which are hereby incorporated
herein by reference.
[0137] In addition to the materials disclosed above, any of the
core or cover layers may comprise one or more of the following
materials as long as they are not used at such a level as to
negatively affect thermal stability of the blend, increase melt
flow beyond a critical level, or otherwise work against the
inventive objective disclosed herein: thermoplastic elastomer,
thermoset elastomer, synthetic rubber, thermoplastic vulcanizate,
copolymeric ionomer, terpolymeric ionomer, polycarbonate,
polyolefin, polyamide, copolymeric polyamide, polyesters,
polyester-amides, polyether-amides, polyvinyl alcohols,
acrylonitrile-butadiene-styrene copolymers, polyarylate,
polyacrylate, polyphenylene ether, impact-modified polyphenylene
ether, high impact polystyrene, diallyl phthalate polymer,
metallocene-catalyzed polymers, styrene-acrylonitrile ("SAN"),
olefin-modified SAN, acrylonitrile-styrene-acrylonitrile,
styrene-maleic anhydride ("S/MA") polymer, styrenic copolymer,
functionalized styrenic copolymer, functionalized styrenic
terpolymer, styrenic terpolymer, cellulose polymer, liquid crystal
polymer ("LCP"), ethylene-propylene-diene rubber ("EPDM"),
ethylene-vinyl acetate copolymer ("EVA"), ethylene propylene rubber
("EPR"), ethylene vinyl acetate, polyurea, and polysiloxane.
Suitable polyamides for use as an additional material in
compositions disclosed herein also include resins obtained by: (1)
polycondensation of (a) a dicarboxylic acid, such as oxalic acid,
adipic acid, sebacic acid, terephthalic acid, isophthalic acid or
1,4-cyclohexanedicarboxylic acid, with (b) a diamine, such as
ethylenediamine, tetramethylenediamine, pentamethylenediamine,
hexamethylenediamine, or decamethylenediamine,
1,4-cyclohexyldiamine or m-xylylenediamine; (2) a ring-opening
polymerization of cyclic lactam, such as .epsilon.-caprolactam or
co-laurolactam; (3) polycondensation of an aminocarboxylic acid,
such as 6-aminocaproic acid, 9-aminononanoic acid,
11-aminoundecanoic acid or 12-aminododecanoic acid; or (4)
copolymerzation of a cyclic lactam with a dicarboxylic acid and a
diamine. Specific examples of suitable polyamides include NYLON 6,
NYLON 66, NYLON 610, NYLON 11, NYLON 12, copolymerized NYLON, NYLON
MXD6, and NYLON 46.
[0138] Other preferred materials suitable for use as an additional
material in golf ball compositions disclosed herein include SKYPEL
polyester elastomers from SK Chemicals of South Korea; SEPTON
diblock and triblock copolymers from Kuraray Corporation of
Kurashiki, Japan; and KRATON diblock and triblock copolymers from
Kraton Polymers of Houston, Tex.
[0139] Ionomers are also well suited for blending with compositions
disclosed herein. Suitable ionomeric polymers include
.alpha.-olefin/unsaturated carboxylic acid copolymer- or
terpolymer-type ionomeric resins. Copolymeric ionomers are obtained
by neutralizing at least a portion of the carboxylic groups in a
copolymer of an .alpha.-olefin and an .alpha.,.beta.-unsaturated
carboxylic acid having from 3 to 8 carbon atoms, with a metal ion.
Terpolymeric ionomers are obtained by neutralizing at least a
portion of the carboxylic groups in a terpolymer of an
.alpha.-olefin, an .alpha.,.beta.-unsaturated carboxylic acid
having from 3 to 8 carbon atoms, and an .alpha.,.beta.-unsaturated
carboxylate having from 2 to 22 carbon atoms, with a metal ion.
Examples of suitable .alpha.-olefins for copolymeric and
terpolymeric ionomers include ethylene, propylene, 1-butene, and
1-hexene. Examples of suitable unsaturated carboxylic acids for
copolymeric and terpolymeric ionomers include acrylic, methacrylic,
ethacrylic, .alpha.-chloroacrylic, crotonic, maleic, fumaric, and
itaconic acid. Copolymeric and terpolymeric ionomers include
ionomers having varied acid contents and degrees of acid
neutralization, neutralized by monovalent or bivalent cations as
disclosed herein.
[0140] Silicone materials are also well suited for blending with
compositions disclosed herein. Suitable silicone materials include
monomers, oligomers, prepolymers, and polymers, with or without
adding reinforcing filler. One type of silicone material that is
suitable can incorporate at least one alkenyl group having at least
2 carbon atoms in their molecules. Examples of these alkenyl groups
include, but are not limited to, vinyl, allyl, butenyl, pentenyl,
hexenyl, and decenyl. The alkenyl functionality can be located at
any location of the silicone structure, including one or both
terminals of the structure. The remaining (i.e., non-alkenyl)
silicon-bonded organic groups in this component are independently
selected from hydrocarbon or halogenated hydrocarbon groups that
contain no aliphatic unsaturation. Non-limiting examples of these
include: alkyl groups, such as methyl, ethyl, propyl, butyl,
pentyl, and hexyl; cycloalkyl groups, such as cyclohexyl and
cycloheptyl; aryl groups, such as phenyl, tolyl, and xylyl; aralkyl
groups, such as benzyl and phenethyl; and halogenated alkyl groups,
such as 3,3,3-trifluoropropyl and chloromethyl. Another type of
suitable silicone material is one having hydrocarbon groups that
lack aliphatic unsaturation. Specific examples include:
trimethylsiloxy-endblocked dimethylsiloxane-methylhexenylsiloxane
copolymers; dimethylhexenylsiloxy-endblocked
dimethylsiloxane-methylhexenylsiloxane copolymers;
trimethylsiloxy-endblocked dimethylsiloxane-methylvinylsiloxane
copolymers; trimethylsiloxyl-endblocked
methylphenylsiloxane-dimethylsiloxane-methylvinysiloxane
copolymers; dimethylvinylsiloxy-endblocked dimethylpolysiloxanes;
dimethylvinylsiloxy-endblocked dimethylsiloxane-methylvinylsiloxane
copolymers; dimethylvinylsiloxy-endblocked
methylphenylpolysiloxanes; dimethylvinylsiloxy-endblocked
methylphenylsiloxane-dimethylsiloxane-methylvinylsiloxane
copolymers; and the copolymers listed above wherein at least one
group is dimethylhydroxysiloxy. Examples of commercially-available
silicones suitable for blending with compositions disclosed herein
include SILASTIC.RTM.. silicone rubber from Dow Corning Corporation
of Midland, Mich.; BLENSIL.RTM. silicone rubber from GE of
Waterford, N.Y.; and ELASTOSIL.RTM. silicones from Wacker Chemie AG
of Germany.
[0141] Other types of copolymers can also be added to the golf ball
compositions disclosed herein. For example, suitable copolymers
comprising epoxy monomers include styrene-butadiene-styrene block
copolymers in which the polybutadiene block contains an epoxy
group, and styrene-isoprene-styrene block copolymers in which the
polyisoprene block contains epoxy. Examples of
commercially-available epoxy functionalized copolymers include ESBS
A1005, ESBS A1010, ESBS A1020, ESBS AT018, and ESBS AT019
epoxidized styrene-butadiene-styrene block copolymers from Daicel
Chemical Industries of Japan.
[0142] Ionomeric compositions used to form golf ball layers of the
present invention can be blended with non-ionic thermoplastic
resins, particularly to manipulate product properties. Examples of
suitable non-ionic thermoplastic resins include, but are not
limited to, polyurethane, poly-ether-ester, poly-amide-ether,
polyether-urea, PEBAX.RTM. thermoplastic polyether block amides
from Arkema Inc., styrene-butadiene-styrene block copolymers,
styrene(ethylene-butylene)-styrene block copolymers, polyamides,
polyesters, polyolefins (e.g., polyethylene, polypropylene,
ethylene-propylene copolymers, ethylene-(meth)acrylate,
ethylene-(meth)acrylic acid, functionalized polymers with maleic
anhydride grafting, epoxidation, etc., elastomers (e.g., EPDM,
metallocene-catalyzed polyethylene) and ground powders of the
thermoset elastomers.
[0143] Compositions disclosed herein can be either foamed or filled
with density adjusting materials to provide desirable golf ball
performance characteristics.
[0144] The present invention is limited to elevated temperature
molding due to the very-low-flow nature of the thermoplastic
intermediate core layers. It should be understood that while any of
the other core and/or cover layer(s) can be formed by any suitable
technique, including injection molding, compression molding,
casting, and reaction injection molding, the thermoplastic inner
cover layers are generally formed by injection molding or
compression molding. In particular, the core center and outer core
layers may be formed by any conventional means for forming
thermosetting layers comprising a vulcanized or otherwise
crosslinked diene rubber including, but not limited to, compression
molding, rubber-injection molding, casting of a liquid rubber, and
laminating.
[0145] When the thermoplastic inner cover layers are formed with
injection molding, the composition is typically in a pelletized or
granulated form that can be fed into the throat of an injection
molding machine where it is melted and conveyed via a screw in a
heated barrel at temperatures of from 400.degree. F. (204.degree.
C.) to 680.degree. F. (360.degree. C.), preferably from 520.degree.
F. (271.degree. C.) to 650.degree. F. (343.degree. C.). The molding
temperatures are significantly higher temperatures than typically
used for conventional injection molding of ionomeric materials.
[0146] The molten composition is ultimately injected into a closed
mold cavity, which may be cooled, at ambient or at an elevated
temperature, but typically the mold is cooled to a temperature of
from 50.degree. F. (10.degree. C.) to 70.degree. F. (21.degree.
C.). After residing in the closed mold for a time of about 1 to 300
seconds, preferably about 20 to 120 seconds, the core and/or core
plus one or more additional core or cover layers is removed from
the mold and either allowed to cool at ambient or reduced
temperatures or is placed in a cooling fluid such as water, ice
water, dry ice in a solvent, or the like.
[0147] When compression molding is used to form a core center or
outer core layer, the composition is first formed into a preform or
slug of material, typically cylindrically-shaped or roughly
spherical-shaped, at a weight slightly greater than the desired
weight. Prior to this step, the composition may be first extruded
or otherwise melted and forced through a die after which it is cut
into the preform. The preform is then placed into a compression
mold cavity and compressed at a mold temperature of from
150.degree. F. (66.degree. C.) to 400.degree. F. (204.degree. C.),
preferably from 250.degree. F. (121.degree. C.) to 400.degree. F.
(204.degree. C.), and more preferably from 300.degree. F.
(149.degree. C.) to 400.degree. F. (204.degree. C.). When
compression molding a cover layer, half-shells of the cover layer
material are first formed via injection molding. A core is then
enclosed within two half-shells, which is then placed into a
compression mold cavity and compressed.
[0148] Reaction injection molding processes are further disclosed,
for example, in U.S. Pat. Nos. 6,083,119, 7,208,562, 7,281,997,
7,282,169, and 7,338,391, the entire disclosures of which are
hereby incorporated herein by reference.
[0149] Golf balls of the present invention typically have a
coefficient of restitution of 0.700 or greater, preferably 0.750 or
greater, and more preferably 0.780 or greater. Golf balls of the
present invention typically have a compression of 40 or greater, or
a compression within a range having a lower limit of 50 or 60 and
an upper limit of 100 or 120. Golf balls of the present invention
will typically have dimple coverage of 60% or greater, preferably
65% or greater, and more preferably 75% or greater.
[0150] The USGA specifications limit the minimum size of a
competition golf ball to 1.68 inches. There is no specification as
to the maximum diameter and golf balls of any size can be used for
recreational play. Golf balls of the present invention can have an
outer diameter of any size. The preferred outer diameter is within
a range having a lower limit of 1.680 inches and an upper limit of
1.740 or 1.760 or 1.780 or 1.800 inches.
[0151] Golf balls of the present invention preferably have a moment
of inertia ("MOI") of about 70 to 95 gcm.sup.2, preferably about 75
to 93 gcm.sup.2, and more preferably about 76 to 90 gcm.sup.2. For
low MOI embodiments, the golf ball preferably has an MOI of 85
gcm.sup.2 or less, or 83 gcm.sup.2 or less. For high MOI
embodiment, the golf ball preferably has an MOI of 86 gcm.sup.2 or
greater, or 87 gcm.sup.2 or greater. MOI is measured on a model
MOI-005-104 Moment of Inertia Instrument manufactured by Inertia
Dynamics of Collinsville, Conn.
[0152] Compression is an important factor in golf ball design. For
example, the compression of the core can affect the ball's spin
rate off the driver and the feel. As disclosed in "Compression by
Any Other Name," Science and Golf IV, Proceedings of the World
Scientific Congress of Golf (Eric Thain ed., Routledge, 2002) by J.
Dalton, several different methods can be used to measure
compression, including Atti compression, Riehle compression,
load/deflection measurements at a variety of fixed loads and
offsets, and effective modulus. For purposes of the present
invention, "compression" refers to Atti compression and is measured
according to a known procedure, using an Atti compression test
device, wherein a piston is used to compress a ball against a
spring. The travel of the piston is fixed and the deflection of the
spring is measured. The measurement of the deflection of the spring
does not begin with its contact with the ball; rather, there is an
offset of approximately the first 1.25 mm (0.05 inches) of the
spring's deflection. Very low stiffness cores will not cause the
spring to deflect by more than 1.25 mm and therefore have a zero
compression measurement. The Atti compression tester is designed to
measure objects having a diameter of 1.680 inches; thus, smaller
objects, such as golf ball cores, must be shimmed to a total height
of 1.680 inches to obtain an accurate reading. Conversion from Atti
compression to Riehle (cores), Riehle (balls), 100 kg deflection,
130-10 kg deflection or effective modulus can be carried out
according to the formulas given in the Dalton article.
[0153] COR, as used herein, is determined according to a procedure
where a golf ball or golf ball subassembly (e.g., a core) is fired
from an air cannon at two given velocities and calculated at a
velocity of 125 ft/s. Ballistic light screens are located between
the air cannon and the steel plate at a fixed distance to measure
ball velocity. As the ball travels toward the steel plate, it
activates each light screen, and the time at each light screen is
measured. This provides an incoming transit time period inversely
proportional to the ball's incoming velocity. The ball impacts the
steel plate and rebounds though the light screens, which again
measure the time period required to transit between the light
screens. This provides an outgoing transit time period inversely
proportional to the ball's outgoing velocity. COR is then
calculated as the ratio of the outgoing transit time period to the
incoming transit time period, COR=V(out)/V(in)=T(in)/T(out).
[0154] The surface hardness of a golf ball layer is obtained from
the average of a number of measurements taken from opposing
hemispheres, taking care to avoid making measurements on the
parting line of the core or on surface defects, such as holes or
protrusions. Hardness measurements are made pursuant to ASTM D-2240
"Indentation Hardness of Rubber and Plastic by Means of a
Durometer." Because of the curved surface, care must be taken to
insure that the golf ball or golf ball subassembly is centered
under the durometer indentor before a surface hardness reading is
obtained. A calibrated, digital durometer, capable of reading to
0.1 hardness units is used for all hardness measurements and is set
to take hardness readings at 1 second after the maximum reading is
obtained. The digital durometer must be attached to, and its foot
made parallel to, the base of an automatic stand. The weight on the
durometer and attack rate conform to ASTM D-2240.
[0155] The center hardness of a core is obtained according to the
following procedure. The core is gently pressed into a
hemispherical holder having an internal diameter approximately
slightly smaller than the diameter of the core, such that the core
is held in place in the hemispherical portion of the holder while
concurrently leaving the geometric central plane of the core
exposed. The core is secured in the holder by friction, such that
it will not move during the cutting and grinding steps, but the
friction is not so excessive that distortion of the natural shape
of the core would result. The core is secured such that the parting
line of the core is roughly parallel to the top of the holder. The
diameter of the core is measured 90 degrees to this orientation
prior to securing. A measurement is also made from the bottom of
the holder to the top of the core to provide a reference point for
future calculations. A rough cut is made slightly above the exposed
geometric center of the core using a band saw or other appropriate
cutting tool, making sure that the core does not move in the holder
during this step. The remainder of the core, still in the holder,
is secured to the base plate of a surface grinding machine. The
exposed `rough` surface is ground to a smooth, flat surface,
revealing the geometric center of the core, which can be verified
by measuring the height from the bottom of the holder to the
exposed surface of the core, making sure that exactly half of the
original height of the core, as measured above, has been removed to
within .+-.0.004 inches. Leaving the core in the holder, the center
of the core is found with a center square and carefully marked and
the hardness is measured at the center mark according to ASTM
D-2240. Additional hardness measurements at any distance from the
center of the core can then be made by drawing a line radially
outward from the center mark, and measuring the hardness at any
given distance along the line, typically in 2 mm increments from
the center. The hardness at a particular distance from the center
should be measured along at least two, preferably four, radial arms
located 180.degree. apart, or 90.degree. apart, respectively, and
then averaged. All hardness measurements performed on a plane
passing through the geometric center are performed while the core
is still in the holder and without having disturbed its
orientation, such that the test surface is constantly parallel to
the bottom of the holder, and thus also parallel to the properly
aligned foot of the durometer. Hardness points should only be
measured once at any particular geometric location.
[0156] For purposes of the present disclosure, a hardness gradient
of a center is defined by hardness measurements made at the outer
surface of the center and the center point of the core. "Negative"
and "positive" refer to the result of subtracting the hardness
value at the innermost portion of the golf ball component from the
hardness value at the outer surface of the component. For example,
if the outer surface of a solid center has a lower hardness value
than the center (i.e., the surface is softer than the center), the
hardness gradient will be deemed a "negative" gradient. In
measuring the hardness gradient of a center, the center hardness is
first determined according to the procedure above for obtaining the
center hardness of a core. Once the center of the core is marked
and the hardness thereof is determined, hardness measurements at
any distance from the center of the core may be measured by drawing
a line radially outward from the center mark, and measuring and
marking the distance from the center, typically in 2 mm increments.
All hardness measurements performed on a plane passing through the
geometric center are performed while the core is still in the
holder and without having disturbed its orientation, such that the
test surface is constantly parallel to the bottom of the holder.
The hardness difference from any predetermined location on the core
is calculated as the average surface hardness minus the hardness at
the appropriate reference point, e.g., at the center of the core
for a single, solid core, such that a core surface softer than its
center will have a negative hardness gradient.
[0157] Hardness gradients are disclosed more fully, for example, in
U.S. Pat. No. 7,429,221, and U.S. patent application Ser. Nos.
11/939,632; 11/939,634; 11/939,635; and Ser. No. 11/939,637; the
entire disclosure of each are hereby incorporated herein by
reference.
[0158] It should be understood that there is a fundamental
difference between "material hardness" and "hardness as measured
directly on a golf ball." For purposes of the present disclosure,
material hardness is measured according to ASTM D2240 and generally
involves measuring the hardness of a flat "slab" or "button" formed
of the material. Hardness as measured directly on a golf ball (or
other spherical surface) typically results in a different hardness
value. This difference in hardness values is due to several factors
including, but not limited to, ball construction (i.e., core type,
number of core and/or cover layers, etc.), ball (or sphere)
diameter, and the material composition of adjacent layers. It
should also be understood that the two measurement techniques are
not linearly related and, therefore, one hardness value cannot
easily be correlated to the other.
[0159] When numerical lower limits and numerical upper limits are
set forth herein, it is contemplated that any combination of these
values may be used. All patents, publications, test procedures, and
other references cited herein, including priority documents, are
fully incorporated by reference to the extent such disclosure is
not inconsistent with this invention.
[0160] While the illustrative embodiments of the invention have
been described with particularity, it will be understood that
various other modifications will be apparent to and can be readily
made by those of ordinary skill in the art without departing from
the spirit and scope of the invention. Accordingly, it is not
intended that the scope of the claims appended hereto be limited to
the examples and descriptions set forth herein, but rather that the
claims be construed as encompassing all of the features of
patentable novelty which reside in the present invention, including
all features which would be treated as equivalents thereof by those
of ordinary skill in the art to which the invention pertains.
* * * * *