U.S. patent application number 11/535767 was filed with the patent office on 2007-05-10 for highly neutralized acid polymer compositions having a low moisture vapor transmission rate and their use in golf balls.
Invention is credited to Pamela V. Arnold, Murali Rajagopalan, Michael J. Sullivan.
Application Number | 20070105661 11/535767 |
Document ID | / |
Family ID | 38004487 |
Filed Date | 2007-05-10 |
United States Patent
Application |
20070105661 |
Kind Code |
A1 |
Rajagopalan; Murali ; et
al. |
May 10, 2007 |
Highly Neutralized Acid Polymer Compositions having a Low Moisture
Vapor Transmission Rate and Their Use in Golf Balls
Abstract
The present invention is directed to a golf ball having at least
one layer formed from a moisture resistant composition having a
moisture vapor transmission rate of 12.5 gmil/100 in.sup.2/day or
less, a flexural modulus of from 50 kpsi to 70 kpsi, and comprising
a highly neutralized acid polymer, wherein the highly neutralized
acid polymer is produced by a process comprising contacting the
acid polymer with a sufficient amount of a lithium-based cation
source, in the presence of a melt flow modifier, to increase the
level of neutralization of the copolymer to at least 70%. Golf
balls of the present invention include one-piece, two-piece,
multi-layer, and wound golf balls. The composition may be present
in any one or more of a core layer, a cover layer, or an
intermediate layer.
Inventors: |
Rajagopalan; Murali; (South
Dartmouth, MA) ; Sullivan; Michael J.; (Barrington,
RI) ; Arnold; Pamela V.; (Fairhaven, MA) |
Correspondence
Address: |
ACUSHNET COMPANY
333 BRIDGE STREET
P. O. BOX 965
FAIRHAVEN
MA
02719
US
|
Family ID: |
38004487 |
Appl. No.: |
11/535767 |
Filed: |
September 27, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11468975 |
Aug 31, 2006 |
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11535767 |
Sep 27, 2006 |
|
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11270066 |
Nov 9, 2005 |
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11468975 |
Aug 31, 2006 |
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Current U.S.
Class: |
473/374 |
Current CPC
Class: |
A63B 37/0074 20130101;
A63B 37/0041 20130101; A63B 37/0037 20130101; A63B 37/0076
20130101; A63B 37/0086 20130101; A63B 37/0033 20130101; A63B
37/0064 20130101; A63B 37/0036 20130101; A63B 37/0043 20130101;
A63B 37/003 20130101; A63B 37/12 20130101; A63B 37/0069 20130101;
A63B 37/0052 20130101; A63B 37/0045 20130101; A63B 37/0047
20130101; A63B 37/0049 20130101; A63B 37/0075 20130101; A63B
37/0061 20130101; A63B 37/0056 20130101; A63B 37/0066 20130101;
A63B 37/0048 20130101; A63B 37/02 20130101; A63B 37/0087 20130101;
A63B 37/0093 20130101; A63B 37/0091 20130101; A63B 37/0073
20130101 |
Class at
Publication: |
473/374 |
International
Class: |
A63B 37/06 20060101
A63B037/06 |
Claims
1. A golf ball having at least one layer formed from a moisture
resistant composition, the moisture resistant composition having a
moisture vapor transmission rate (MVTR) of 12.5 gmil/100
in.sup.2/day or less, a flexural modulus of from 50 kpsi to 75
kpsi, and comprising a highly neutralized acid polymer, wherein the
highly neutralized acid polymer is the salt of a copolymer of from
80 wt % to 90 wt % of an olefin selected from ethylene and
propylene; from 10 wt % to 20 wt % of an
.alpha.,.beta.-ethylenically unsaturated carboxylic acid selected
from acrylic acid, methacrylic acid, maleic acid, fumaric acid, and
itaconic acid; and from 0 wt % to 10 wt % of a softening monomer
selected from methyl acrylate, propyl acrylate, and butyl acrylate;
based on the total weight of the copolymer; wherein the highly
neutralized acid polymer is produced by a process comprising
contacting the copolymer with a sufficient amount of a
lithium-based cation source, in the presence of a melt flow
modifier, to increase the level of neutralization of the copolymer
to at least 70%; and wherein the moisture resistant composition has
a coefficient of restitution (COR) of at least 0.800, as measured
on a solid sphere formed from the moisture resistant composition
and having a diameter of 1.550 inches.
2. The golf ball of claim 1, wherein the olefin is ethylene.
3. The golf ball of claim 2, wherein the .alpha.,.beta.-unsaturated
carboxylic acid is (meth) acrylic acid.
4. The golf ball of claim 3, wherein the softening monomer is
selected from methyl acrylate and butyl acrylate.
5. The golf ball of claim 1, wherein the copolymer comprises from
13 wt % to 18 wt % of the acid, based on the total weight of the
copolymer.
6. The golf ball of claim 1, wherein the copolymer comprises from
15.0 wt % to 15.8 wt % of the acid, based on the total weight of
the copolymer.
7. The golf ball of claim 1, wherein the moisture resistant
composition has a flexural modulus of from 60 kpsi to 70 kpsi.
8. The golf ball of claim 1, wherein the moisture resistant
composition has a COR of at least 0.810.
9. The golf ball of claim 1, wherein the moisture resistant
composition has a COR of at least 0.820.
10. The golf ball of claim 1, wherein the moisture resistant
composition has an MVTR of 5.0 g mil/100 in.sup.2/day or less.
11. The golf ball of claim 1, wherein the moisture resistant
composition has a melt flow index of at least 0.5 g/10 min.
12. The golf ball of claim 1, wherein the moisture resistant
composition has a melt flow index of at least 1.5 g/10 min.
13. The golf ball of claim 1, wherein the moisture resistant
composition has a melt flow index of from 1.5 g/10 min to 2.0 g/10
min.
14. The golf ball of claim 1, wherein the ball is a one-piece golf
ball formed from the moisture resistant composition.
15. The golf ball of claim 1, wherein the ball is a two-piece golf
ball consisting of a core and a cover, and wherein the core is
formed from the moisture resistant composition.
16. The golf ball of claim 1, wherein the ball is a two-piece golf
ball consisting of a core and a cover, and wherein the cover is
formed from the moisture resistant composition.
17. The golf ball of claim 1, wherein the ball comprises an inner
core layer, an outer cover layer, and one or more intermediate
layer(s) disposed between the inner core layer and the outer cover
layer, and wherein at least one of the inner core layer, outer
cover layer, and intermediate layer(s) is formed from the moisture
resistant composition.
18. A golf ball having at least one layer formed from a moisture
resistant composition, the moisture resistant composition having a
moisture vapor transmission rate (MVTR) of 5.0 g-mil/100
in.sup.2/day or less, a flexural modulus of from 50 kpsi to 75
kpsi, and comprising a highly neutralized acid polymer, wherein the
highly neutralized acid polymer is the salt of a copolymer of from
74 wt % to 85 wt % of ethylene; from 15 wt % to 16 wt % of acrylic
acid; and from 0 wt % to 10 wt % of a softening monomer selected
from methyl acrylate and butyl acrylate; based on the total weight
of the copolymer; wherein the highly neutralized acid polymer is
produced by a process comprising contacting the copolymer with a
sufficient amount of a lithium-based cation source, in the presence
of a melt flow modifier, to increase the level of neutralization of
the copolymer to 100%; and wherein the moisture resistant
composition has a coefficient of restitution (COR) of at least
0.800, as measured on a solid sphere formed from the moisture
resistant composition and having a diameter of 1.550 inches.
19. The golf ball of claim 18, wherein the melt flow modifier is
zinc stearate.
20. The golf ball of claim 18, wherein the moisture resistant
composition has a COR of at least 0.820.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 11/468,975, filed Aug. 31, 2006, which is a
continuation-in-part of U.S. application Ser. No. 11/270,066, filed
Nov. 9, 2005, the entire disclosures of which are hereby
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention is directed to compositions having a
moisture vapor transmission rate of 12.5 gmil/100 in.sup.2/day or
less, a flexural modulus of from 50 kpsi to 70 kpsi, and comprising
a highly neutralized acid polymer, and to the use of such
compositions in golf balls. Highly neutralized acid polymers of the
present invention are prepared with a cation source selected from
ions and compounds of lithium.
BACKGROUND OF THE INVENTION
[0003] Conventional golf balls can be divided into two general
classes: solid and wound. Solid golf balls include one-piece,
two-piece (i.e., solid core and a cover), and multi-layer (i.e.,
solid core of one or more layers and/or a cover of one or more
layers) golf balls. Wound golf balls typically include a solid,
hollow, or fluid-filled center, surrounded by a tensioned
elastomeric material, and a cover.
[0004] Golf ball core and cover layers are typically constructed
with polymer compositions including, for example, polybutadiene
rubber, polyurethanes, polyamides, ionomers, and blends thereof.
Ionomers, particularly highly neutralized ionomers, are a preferred
group of polymers for golf ball layers because of their toughness,
durability, and wide range of hardness values. However,
conventional highly neutralized ionomers are hydrophilic, due to
the highly hydrophilic nature of the cation sources traditionally
used to neutralize the ionomers, e.g., magnesium and magnesium
salts of fatty acids. As a result of their hydrophilic nature,
conventional highly neutralized ionomers can absorb a significant
amount of moisture, e.g., 2,000 to 10,000 parts per million (ppm),
which can result in processing difficulties, such as creating voids
in the part during an injection molding process, and a reduction in
golf ball performance, such as decreased coefficient of restitution
("COR") and stiffness due to the plasticization of ionic aggregates
by water molecules.
[0005] Therefore, a desire remains for compositions containing
highly neutralized acid polymers and having improved moisture vapor
resistance properties. The present invention describes such
compositions and the use thereof in a variety of golf ball core and
cover layers.
SUMMARY OF THE INVENTION
[0006] In one embodiment, the present invention is directed to a
golf ball having at least one layer formed a moisture resistant
composition. The moisture resistant composition has a moisture
vapor transmission rate of 12.5 gmil/100 in.sup.2/day or less, a
flexural modulus of from 50 kpsi to 70 kpsi, and comprises a highly
neutralized polymer. The highly neutralized polymer is the salt of
a copolymer of from 80 wt % to 90 wt % of an olefin selected from
ethylene and propylene, from 10 wt % to 20 wt % of an
.alpha.,.beta.-ethylenically unsaturated carboxylic acid, and from
0 wt % to 10 wt % of a softening monomer, based on the total weight
of the copolymer. The .alpha.,.beta.-ethylenically unsaturated
carboxylic acid is selected from acrylic acid, methacrylic acid,
maleic acid, fumaric acid, and itaconic acid. The softening monomer
is selected from methyl acrylate, propyl acrylate, and butyl
acrylate. The highly neutralized acid polymer is produced by a
process comprising contacting the copolymer with a sufficient
amount of a lithium-based cation source, in the presence of a melt
flow modifier, to increase the level of neutralization of the
copolymer to at least 70%.
[0007] In another embodiment, the present invention is directed to
a golf ball having at least one layer formed a moisture resistant
composition. The moisture resistant composition has a moisture
vapor transmission rate of 5.0 gmil/100 in.sup.2/day or less, a
flexural modulus of from 50 kpsi to 70 kpsi, and comprises a highly
neutralized polymer. The highly neutralized polymer is the salt of
a copolymer of from 74 wt % to 85 wt % of ethylene, from 15 wt % to
16 wt % of acrylic acid, and from 0 wt % to 10 wt % of a softening
monomer, based on the total weight of the copolymer. The softening
monomer is selected from methyl acrylate and butyl acrylate. The
highly neutralized acid polymer is produced by a process comprising
contacting the copolymer with a sufficient amount of a
lithium-based cation source, in the presence of a melt flow
modifier, to increase the level of neutralization of the copolymer
to 100%.
DETAILED DESCRIPTION OF THE INVENTION
[0008] Golf balls of the present invention include one-piece
two-piece, multi-layer, and wound golf halls having a variety of
core structures, intermediate layers, covers, and coatings. Golf
ball cores may consist of a single, unitary layer, comprising the
entire core from the center of the core to its outer periphery, or
they may consist of a center surrounded by at least one outer core
layer. The center, innermost portion of the core is preferably
solid, but may be hollow or liquid-, gel-, or gas-filled. The outer
core layer may be solid, or it may be a wound layer formed of a
tensioned elastomeric material. Golf ball covers may also contain
one or more layers, such as a double cover having an inner and
outer cover layer. Optionally, additional layers may be disposed
between the core and cover.
[0009] Golf balls of the present invention have at least one layer
formed from a moisture resistant composition comprising a highly
neutralized polymer as disclosed herein. The moisture resistant
composition can be present in any one or more of a core layer, a
cover layer, or an intermediate layer disposed between the core or
cover.
[0010] For purposes of the present disclosure, a composition is
"moisture resistant" if it has a moisture vapor transmission rate
("MVTR") of 12.5 gmil/100 in.sup.2/day or less. Preferably, the
composition has an MVTR of 8.0 gmil/100 in.sup.2/day or less, or
6.5 gmil/100 in.sup.2/day or less, or 5.0 gmil/100 in.sup.2/day or
less, or 4.0 gmil/100 in.sup.2/day or less, or 2.5 gmil/100
in.sup.2/day or less, or 2.0 gmil/100 in.sup.2/day or less. As used
herein, moisture vapor transmission rate (MVTR) is given in
g-mil/100 in.sup.2/day, and is measured at 20.degree. C., and
according to ASTM F1249-99.
[0011] Moisture resistant compositions of the present invention
comprise a highly neutralized acid polymer ("HNP"). As used herein,
"highly neutralized" refers to the acid polymer after at least 70%,
preferably at least 80%, more preferably at least 90%, even more
preferably at least 95%, and even more preferably 100%, of the acid
groups thereof are neutralized. The HNP may be neutralized by a
cation, a salt of an organic acid, a suitable base of an organic
acid, or any combination of two or more thereof.
[0012] Suitable HNPs are salts of homopolymers and copolymers of
.alpha.,.beta.-ethylenically unsaturated mono- or dicarboxylic
acids, and combinations thereof. The term "copolymer," as used
herein, includes polymers having two types of monomers, those
having three types of monomers, and those having more than three
types of monomers. Preferred acids are (meth) acrylic acid,
ethacrylic acid, maleic acid, crotonic acid, fumaric acid, itaconic
acid. More preferred acid are (meth) acrylic acid, maleic acid,
fumaric acid, and itaconic acid. (Meth) acrylic acid is
particularly preferred. As used herein, "(meth) acrylic acid" means
methacrylic acid and/or acrylic acid. Likewise, "(meth) acrylate"
means methacrylate and/or acrylate. Preferred acid polymers are
copolymers of a C.sub.3 to C.sub.8 .alpha.,.beta.-ethylenically
unsaturated mono- or dicarboxylic acid and ethylene or a C.sub.3 to
C.sub.6 .alpha.-olefin, optionally including a softening monomer.
Particularly preferred acid polymers are copolymers of ethylene and
an acid selected from (meth) acrylic acid, maleic acid, fumaric
acid, and itaconic acid, preferably (meth) acrylic acid. More
preferred are copolymers of ethylene and acrylic acid.
[0013] When a softening monomer is included, the acid polymer is
referred to herein as an E/X/Y-type copolymer, wherein E is
ethylene, X is a C.sub.3 to C.sub.8 .alpha.,.beta.-ethylenically
unsaturated mono- or dicarboxylic acid as described above, and Y is
a softening monomer. The softening monomer is typically an alkyl
(meth) acrylate, wherein the alkyl groups have from 1 to 12 carbon
atoms, preferably from 1 to 8. Preferred E/X/Y-type copolymers are
those wherein Y is selected from (meth) acrylate, propyl (meth)
acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, methyl
(meth) acrylate, and ethyl (meth) acrylate. Particularly preferred
are E/X/Y-type copolymers wherein Y is selected from methyl
acrylate, propyl acrylate, and butyl acrylate. More preferred
E/X/Y-type copolymers are ethylene/(meth) acrylic acid/methyl
acrylate and ethylene/(meth) acrylic acid/butyl acrylate.
[0014] The amount of ethylene or C.sub.3 to C.sub.6 .alpha.-olefin
in the acid copolymer is typically at least 15 wt %, preferably at
least 25 wt %, more preferably at least 40 wt %, more preferably at
least 60 wt %, more preferably from 80 wt % to 90 wt %, and even
more preferably from 74 wt % to 85 wt %, based on the total weight
of the copolymer. The amount of C.sub.3 to C.sub.8
.alpha.,.beta.-ethylenically unsaturated mono- or dicarboxylic acid
in the acid copolymer is typically within a range having a lower
limit of 1 wt %, or 3 wt %, or 4 wt %, or 5 wt %, or 10 wt %, or 13
wt %, or 15 wt %, and an upper limit of 15.8 wt %, or 16 wt %, or
18 wt %, or 20 wt %, or 25 wt %, or 30 wt %, or 35 wt %, based on
the total weight of the copolymer. The amount of optional softening
comonomer in the acid copolymer is typically within a range having
a lower limit of 0 wt %, or 5 wt % and an upper limit of 10 wt %,
or 20 wt %, or 30 wt %, or 35 wt %, or 40 wt %, or 50 wt %, based
on the total weight of the copolymer.
[0015] The acid polymer may be partially neutralized prior to being
neutralized to 70% or higher. Suitable partially neutralized acid
polymers include, but are not limited to, Surlyn.RTM. ionomers,
commercially available from E.I. du Pont de Nemours and Company;
AClyn.RTM. ionomers, commercially available from Honeywell
International Inc.; Iotek.RTM. ionomers, commercially available
from ExxonMobil Chemical Company; and Clarix.RTM. ionomers,
commercially available from A. Schulman, Inc.
[0016] In a particular embodiment, the acid polymer is a partially
neutralized ethylene/acrylic acid copolymer produced with a Na- or
Li- based cation source, such as Clarix.RTM. ionomers, commercially
available from A. Schulman, Inc.
[0017] Additional suitable acid polymers are more fully described,
for example, in U.S. Pat. No. 6,953,820 and U.S. patent application
Publication No. 2005/0049367, the entire disclosures of which are
hereby incorporated herein by reference.
[0018] The acid polymers of the present invention can be direct
copolymers wherein the polymer is polymerized by adding all
monomers simultaneously, as described in, for example, U.S. Pat.
No. 4,351,931, the entire disclosure of which is hereby
incorporated herein by reference. Ionomers can be made from direct
copolymers, as described in, for example, U.S. Pat. No. 3,264,272
to Rees, the entire disclosure of which is hereby incorporated
herein by reference. Alternatively, the acid polymers of the
present invention can be graft copolymers wherein a monomer is
grafted onto an existing polymer, as described in, for example,
U.S. patent application Publication No. 2002/0013413, the entire
disclosure of which is hereby incorporated herein by reference.
[0019] Suitable cation sources for producing HNPs of the present
invention are ions and compounds of lithium. Suitable cation
sources also include mixtures of lithium cations with other
cations. Other cations suitable for mixing with lithium cations to
produce HNPs of the present invention include, but are not limited
to, the "less hydrophilic" cations disclosed in U.S. patent
application Publication No. 2006/0106175; conventional HNP cations,
such as those disclosed in U.S. Pat. Nos. 6,756,436 and 6,824,477;
and the cations disclosed in U.S. patent application Publication
No. 2005/026740. The entire disclosure of each of these references
is hereby incorporated herein by reference.
[0020] While other cations may be present in the composition, the
percentage of lithium salts in the composition is preferably 50% or
higher, or 55% or higher, or 60% or higher, or 65% or higher, or
70% or higher, or 80% or higher, or 90% or higher, or 95% or
higher, or 100%, based on the total salts present in the
composition. The equivalent % is determined by multiplying the mol
% of the cation by the valence of the cation. The amount of cation
source used is readily determined based on the desired level of
neutralization.
[0021] Compositions of the present invention include one or more
invention HNPs (i.e., produced using a lithium-based cation
source), and optionally include one or more conventional HNPs
(i.e., produced using a conventional cation source). The total
amount of invention and optional conventional HNPs in the
composition is preferably at least 30 wt %, more preferably at
least 50 wt %, even more preferably from 50 wt % to 99.5 wt %, and
even more preferably from 600 wt % to 98 wt %, based on the total
polymeric weight of the composition. Preferably the amount of
invention HNPs present in the composition is at least 30 wt %,
based on the total polymeric weight of the composition.
[0022] Moisture resistant compositions of the present invention
optionally comprise one or more organic acids and/or salts thereof.
Suitable organic acids are aliphatic organic acids, aromatic
organic acids, saturated monofunctional organic acids, unsaturated
monofunctional organic acids, multiunsaturated monofunctional
organic acids, and dimerized derivatives thereof. Particularly
suitable are aliphatic, monofunctional organic acids, preferably
having fewer than 36 carbon atoms. Particular examples of suitable
organic acids include, but are not limited to, caproic acid,
caprylic acid, capric acid, lauric acid, stearic acid, behenic
acid, erucic acid, oleic acid, linoleic acid, myristic acid,
benzoic acid, palmitic acid, phenylacetic acid, naphthalenoic acid,
and dimerized derivatives thereof. Particularly suitable organic
acid salts include those produced by a cation source selected from
barium, lithium, sodium, zinc, bismuth, potassium, strontium,
magnesium, calcium, and combinations thereof. In a particular
embodiment, the organic acid salt is selected from zinc stearate
and calcium stearate. Particularly preferred is zinc stearate.
Suitable organic acids are more fully described, for example, in
U.S. Pat. No. 6,756,436, the entire disclosure of which is hereby
incorporated herein by reference.
[0023] Moisture resistant compositions of the present invention
optionally contain one or more additives and/or one or more
fillers. Suitable additives include, but are not limited to,
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, and
surfactants. Suitable fillers include, but are not limited to,
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., core material that is ground and
recycled; and nano-fillers. Filler materials may be dual-functional
fillers, for example, zinc oxide (which may be used as a
filler/acid scavenger) and titanium dioxide (which may be used as a
filler/brightener material). Further examples of suitable fillers
and additives include, but are not limited to, those disclosed in
U.S. patent application Publication No. 2003/0225197, the entire
disclosure of which is hereby incorporated herein by reference.
[0024] Moisture resistant compositions of the present invention
optionally contain one or more non-fatty acid melt flow modifiers.
Suitable non-fatty acid melt flow modifiers include polyamides,
polyesters, polyacrylates, polyurethanes, polyethers, polyureas,
polyhydric alcohols; and combinations thereof. Additional melt flow
modifiers, suitable for use in compositions of the present
invention, include those described in copending U.S. patent
application Publication No. 2006/0063893 and U.S. patent
application Ser. No. 11/216,726, the entire disclosures of which
are hereby incorporated herein by reference.
[0025] In some embodiments, moisture resistant compositions of the
present invention further comprise an impact modifier. Suitable
impact modifiers include, but are not limited to, homopolymers and
copolymers of alkyl (meth)acrylate, metallocene-catalyzed grafted
and non-grafted polymers, and epoxy acrylates.
[0026] Moisture resistant compositions of the present invention are
optionally produced by blending the HNP with one or more additional
polymers, such as thermoplastic polymers and elastomers. Examples
of thermoplastic polymers suitable for blending with the invention
HNPs include, but are not limited to, polyolefins, polyamides,
polyesters, polyethers, polyether-esters, polyether-amides,
polyether-urea, polycarbonates, polysulfones, polyacetals,
polylactones, acrylonitrile-butadiene-styrene resins, polyphenylene
oxide, polyphenylene sulfide, styrene-acrylonitrile resins, styrene
maleic anhydride, polyimides, aromatic polyketones, ionomers and
ionomeric precursors, acid homopolymers and copolymers,
conventional ionomers and HNPs (e.g., ionomeric materials sold
under the trade names DuPont.RTM. HPF 1000 and DuPont.RTM. HPF
2000, commercially available from E.I. du Pont de Nemours and
Company), rosin-modified ionomers, bimodal ionomers, polyurethanes,
grafted and non-grafted metallocene-catalyzed polymers, single-site
catalyst polymerized polymers, high crystalline acid polymers,
cationic ionomers, epoxy-functionalized polymers,
anhydride-functionalized polymers, and combinations thereof.
Particular polyolefins suitable for blending include one or more,
linear, branched, or cyclic, C.sub.2-C.sub.40 olefins, particularly
polymers comprising ethylene or propylene copolymerized with one or
more C.sub.2-C.sub.40 olefins, C.sub.3-C.sub.20 .alpha.-olefins, or
C.sub.3-C.sub.10 .alpha.-olefins. Particular conventional HNPs
suitable for blending include, but are not limited to, one or more
of the HNPs disclosed in U.S. Pat. Nos. 6,756,436, 6,894,098, and
6,953,820, the entire disclosures of which are hereby incorporated
herein by reference. Examples of elastomers suitable for blending
with the invention polymers include natural and synthetic rubbers,
including, but not limited to, ethylene propylene rubber ("EPR"),
ethylene propylene diene rubber ("EPDM"), hydrogenated and
non-hydrogenated 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,
copolymers of isobutylene and para-alkylstyrene, halogenated
copolymers of isobutylene and para-alkylstyrene, natural rubber,
polyisoprene, copolymers of butadiene with acrylonitrile,
polychloroprene, alkyl acrylate rubber, chlorinated isoprene
rubber, acrylonitrile chlorinated isoprene rubber, polybutadiene
rubber, and thermoplastic vulcanizates. Additional suitable blend
polymers include those described in U.S. Pat. No. 5,981,658, for
example at column 14, lines 30 to 56, and in U.S. patent
application Publication No. 2005/0267240, for example at paragraph
[0073], the entire disclosures of which are hereby incorporated
herein by reference. The blends described herein may be produced by
post-reactor blending, by connecting reactors in series to make
reactor blends, or by using more than one catalyst in the same
reactor to produce multiple species of polymer. The polymers may be
mixed prior to being put into an extruder, or they may be mixed in
an extruder.
[0027] The present invention is not limited by any particular
method or any particular equipment for making the moisture
resistant composition. In a preferred embodiment, the composition
is prepared by the following process. An acid polymer is fed into a
melt extruder, such as a single or twin-screw extruder. A suitable
amount of cation source selected from ions and compounds of Li is
added to the molten polymer, such that at least 70% of all acid
groups present are neutralized, including the acid groups of the
acid polymer and the acid groups of optional organic acid.
Preferably at least 80%, more preferably at least 90%, more
preferably at least 95%, and even more preferably at least 100%, of
all acid groups present are neutralized. The acid polymer may be
partially neutralized prior to contact with the cation source,
preferably with a cation source selected from metal ions and
compounds of Na and/or Li. The resulting mixture is intensively
mixed prior to being extruded as a strand from the die-head.
Additional materials such as additives, fillers, melt flow
modifiers, and impact modifiers, are optionally incorporated during
the process.
[0028] Further examples of suitable moisture resistant compositions
include, but are not limited to, compositions containing an HNP
neutralized by a less hydrophilic cation source as disclosed in
U.S. patent application Publication No. 2006/0106175, the entire
disclosure of which is hereby incorporated herein by reference.
[0029] In order to be processable, the moisture resistant
composition of the present invention has a melt flow index of at
least 0.5 g/10 min (190.degree. C., 2.16 kg). Preferably, the melt
flow index of the moisture resistant composition is at least 0.8
g/10 minor at least 1.0 g/10 min, or within the range having a
lower limit of 0.8 or 1.0 or 1.5 g/10 min, and an upper limit of
2.0 or 4.0 or 5.0 or 10.0 g/10 min. For purposes of the present
disclosure, melt flow index is measured according to ASTM D1238 and
the results are given in g/10 min (190.degree. C., 2.16 kg).
[0030] Moisture resistant compositions of the present invention
preferably have a flexural modulus within the range having a lower
limit of 50 kpsi or 60 kpsi and an upper limit of 70 kpsi or 75
kpsi.
[0031] Preferably, moisture resistant compositions of the present
invention are impact resistant as evident from having no failures
when a 1.550 inch diameter solid sphere formed from the composition
is fired from an air cannon 50 times. Suitable equipment for
performing the impact resistance test includes the equipment used
to measure COR, as described below.
[0032] Moisture resistant compositions of the present invention
have a COR of at least 0.800, preferably at least 0.810, and more
preferably 0.820. The COR of the moisture resistant composition is
measured on a 1.550 inch diameter solid sphere formed from the
moisture resistant composition, according to the COR procedure set
forth below. Moisture resistant compositions of the present
invention generally have a compression of from 50 to 160, as
measured on a 1.550 inch diameter solid sphere formed from the
moisture resistant composition.
[0033] Moisture resistant compositions of the present invention can
be used in a variety of applications. For example, moisture
resistant compositions containing HNPs are suitable for use in golf
equipment, including, but not limited to, golf balls, golf shoes,
and golf clubs.
[0034] Golf balls of the present invention can be wound, one-piece,
two-piece, or multi-layer balls, wherein one or more layers are
formed from a moisture resistant composition comprising a highly
neutralized acid polymer and having a melt index of 1.0 g/10 min or
greater. In golf balls having two or more layers which comprise
such moisture resistant composition, the composition of one layer
may be the same or a different composition as another layer. The
layer(s) comprising the moisture resistant composition can be any
one or more of a core layer (such as a center or an outer core
layer), an intermediate layer, or a cover layer. Compositions of
the present invention can be either foamed or filled with density
adjusting materials to provide golf balls having modified moments
of inertia.
[0035] Golf balls of the present invention generally have a
coefficient of restitution ("COR") of 0.780 or higher, and
preferably have a COR of 0.790 or higher, more preferably 0.800 or
higher. Golf balls of the present invention generally have a
compression of 100 or less and preferably have a compression of
from 80 to 90.
[0036] Golf ball cores of the present invention can be single-,
dual-, or multi-layer cores and generally have an overall diameter
of from 1.50 inches to 1.62 inches, and preferably have an overall
diameter of 1.50 inches. Dual-layer cores of the present invention
generally have a inner core layer (or "center") having a diameter
of from 0.50 inches to 1.55 inches and an outer core layer having a
thickness of from 0.03 inches to 0.25 inches. Golf ball covers of
the present invention can be single-, dual-, or multi-layer covers.
Single-layer covers of the present invention generally have a
thickness of from 0.025 inches to 0.090 inches. Each layer of dual-
and multi-layer covers of the present invention generally has a
thickness of from 0.025 inches to 0.060 inches.
[0037] The present invention is not limited by any particular
process for forming the golf ball layers. It should be understood
that the layers can be formed by any suitable technique, including
injection molding, compression molding, casting, and reaction
injection molding. Preferably, thermoset cover materials are formed
into golf ball cover layers by casting or reaction injection
molding and thermoplastic cover materials are formed into golf ball
cover layers by compression or injection molding techniques.
[0038] In a preferred embodiment, the present invention provides a
two-piece golf ball having a compression molded rubber core and an
injection or compression molded cover layer which comprises a
moisture resistant composition as described herein.
[0039] In another preferred embodiment, the present invention
provides a two-piece golf ball having a core and a polyurethane or
polyurea cover, wherein the core comprises a moisture resistant
composition as described herein.
[0040] In another preferred embodiment, the present invention
provides a multi-layer golf ball comprising an inner core layer, an
outer core layer, and a cover having one or more layers. At least
one of the inner core layer and the outer core layer comprises a
moisture resistant composition as described herein.
[0041] In another preferred embodiment, the present invention
provides a multi-layer golf ball comprising a core having one or
more layers, an inner cover layer, and an outer cover layer. At
least one of the inner cover layer and the outer cover layer
comprises a moisture resistant composition as described herein.
[0042] Golf balls of the present invention may have at least one
layer formed from a composition other than the moisture resistant
composition disclosed above. Suitable materials for golf ball core,
intermediate and cover layers of the present invention include, but
are not limited to, polyethylene, including, for example, low
density polyethylene, linear low density polyethylene, and high
density polyethylene; polypropylene; rubber-toughened olefin
polymers; copolyether-esters; copolyether-amides; polycarbonates;
acid copolymers which do not become part of an ionomeric copolymer;
plastomers; flexomers; vinyl resins, such as those formed by the
copolymerization of vinyl chloride with vinyl acetate, acrylic
esters or vinylidene chloride; styrene/butadiene/styrene block
copolymers; styrene/ethylene-butylene/styrene block copolymers;
acrylonitrile-butadiene-styrene polymers; fluoropolymers;
dynamically vulcanized elastomers; ethylene vinyl acetates;
ethylene methacrylates and ethylene ethacrylates; ethylene
methacrylic acid, ethylene acrylic acid, and propylene acrylic
acid; polyvinyl chloride resins; copolymers and homopolymers
produced using a metallocene or other single-site catalyst;
polyamides, amide-ester elastomers, and graft copolymers of ionomer
and polyamide, including, for example, Pebax.RTM. thermoplastic
polyether block amides, commercially available from Arkema Inc;
polyphenylene oxide resins or blends of polyphenylene oxide with
high impact polystyrene, such as NORYL.RTM., commercially available
by General Electric Company of Pittsfield, Mass.; crosslinked
transpolyisoprene blends; polyurethanes; polyureas; polyester-based
thermoplastic elastomers, such as Hytrel.RTM., commercially
available from E.I. du Pont de Nemours and Company, and LOMOD.RTM.,
commercially available from General Electric Company;
polyurethane-based thermoplastic elastomers, such as
Elastollan.RTM., commercially available from BASF; natural and
synthetic rubbers; partially and fully neutralized ionomers; and
combinations thereof. Suitable golf ball materials and
constructions also include, but are not limited to, those disclosed
in U.S. Pat. Nos. 6,117,025, 6,767,940, and 6,960,630, the entire
disclosures of which are hereby incorporated herein by
reference.
[0043] Particularly preferred materials for outer cover layers of
the present invention include castable reactive materials,
preferably selected from aliphatic and aromatic thermoset
polyurethanes and aliphatic and aromatic thermoset polyureas.
[0044] Additionally suitable cover layer materials and methods for
forming them are further disclosed, for example, in U.S. Pat. Nos.
5,484,870, 6,818,724, and 6,835,794, the entire disclosures of
which are hereby incorporated herein by reference.
[0045] For purposes of the present invention, compression 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 42.7 mm (1.68 inches); thus,
smaller objects, such as golf ball cores, must be shimmed to a
total height of 42.7 mm to obtain an accurate reading.
[0046] For purposes of the present invention, COR is determined
according to a known procedure wherein a golf ball or golf ball
subassembly (e.g., a golf ball core) is fired from an air cannon at
a given velocity (125 ft/s for purposes of the present invention).
Ballistic light screens are located between the air cannon and the
steel plate 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 incoming transit time period
to the outgoing transit time period, COR=T.sub.in/T.sub.out.
EXAMPLES
[0047] It should be understood that the examples below are for
illustrative purposes only. In no manner is the present invention
limited to the specific disclosures therein.
Example 1 and Comparative Example 2
[0048] In Example 1, a composition was prepared by mixing an
ethylene/acrylic acid ionomer (15 wt % acid, partially neutralized
with a Li-based cation source), lithium hydroxide, zinc stearate,
and antioxidant. The relative amounts of each component used are
indicated in Table 1. The melt flow index, flexural modulus, and
Shore D hardness of the composition was measured, and the results
are reported in Table 1. TABLE-US-00001 TABLE 1 Melt Flow Index
ethylene/acrylic lithium zinc Irganox .RTM. (g/10 min Flexural
Hardness acid ionomer hydroxide stearate 1010 @230.degree. C.,
Modulus (Shore Example (parts) (pph) (pph) (g) 2.16 kg) (kpsi) D) 1
100 4.89 30.0 10 0.6 65.8 62 2 100 0 0 0 1.6 60.5 61
[0049] Each of the above compositions was injection molded to form
a solid sphere having a diameter of 1.55 in (3.94 cm). The sphere
was evaluated for compression, hardness, and COR at 125 ft/sec. The
results are reported in Table 2. TABLE-US-00002 TABLE 2 Hardness
Example Compression (Shore D) COR 1 147 64 0.825 2 155 65 0.772
[0050] When numerical lower limits and numerical upper limits are
set forth herein, it is contemplated that any combination of these
values may be used.
[0051] 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 and for all jurisdictions in which
such incorporation is permitted.
[0052] 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.
* * * * *